JP4581603B2 - Electric motor drive - Google Patents

Description

  The present invention relates to an electric motor drive device that drives an electric motor such as a brushless DC motor at an arbitrary rotation speed.

  In recent years, in an apparatus for driving an electric motor such as a compressor in an air conditioner, there is an increasing need to reduce power consumption from the viewpoint of protecting the global environment.

  Among them, as one of the power saving technologies, an inverter that drives a highly efficient electric motor such as a brushless DC motor at an arbitrary frequency is widely used.

  Furthermore, as a driving technique, a sine wave driving technique that is more efficient and can reduce noise is attracting attention as compared with the rectangular wave driving that is driven by a rectangular wave current.

  When driving an electric motor such as a compressor in an air conditioner, it is difficult to install a sensor that detects the rotor position of the motor. A sinusoidal drive technology has been devised.

  As a method for estimating the position of the rotor, there is a method in which an induced voltage generated in a stator winding of an electric motor is estimated (see, for example, Patent Document 1).

  FIG. 13 shows a system configuration of the electric motor drive device of Patent Document 1.

  The electric motor drive device 3 includes an inverter 5 including freewheeling diodes 6a to 6b paired with a plurality of switching elements 5a to 5f, a speed control unit 11, a current control unit 12, a PWM signal generation unit 13, and an induced voltage estimation unit. 14 and a rotor position speed estimation unit 15.

  The input voltage from the AC power source 1 is rectified to DC by the rectifier circuit 2, and the DC voltage is converted into a three-phase AC voltage by the AC / DC converter 5, thereby driving the electric motor 4 that is a brushless DC motor.

  In the motor driving device 3, the speed control unit 11 sets the target speed ω * and the current speed ω1 (the current value of the estimated speed estimated by the rotor magnetic pole position speed estimating means 15) in order to realize the target speed given from the outside. The current command value I * is calculated by proportional-integral control (hereinafter referred to as PI control) so that the speed error Δω with respect to

  The current control unit 12 includes a stator winding phase current command value created based on the current command value I * calculated by the speed control unit 11, and currents obtained from the current detectors 7a and 7b and the current detection unit 9. The voltage command value v * is calculated by PI control so that the current error from the detected value becomes zero.

  The induced voltage estimation unit 14 is detected by the current detection value of the motor 4 detected by the current detectors 7a and 7b and the current detection unit 9, the voltage command value v *, the voltage dividing resistors 8a and 8b, and the DC voltage detection unit 10. Based on the information on the DC voltage of the inverter 5 thus generated, the induced voltage generated in each phase of the stator winding of the electric motor 4 is estimated.

  The rotor position speed estimation means 15 estimates the magnetic pole position and speed of the rotor in the electric motor 4 using the induced voltage estimated by the induced voltage estimation unit 14. Based on the information on the estimated rotor magnetic pole position, the current control unit 12 generates a signal for driving the switching elements 5a to 5f in order for the inverter 5 to output the voltage command value v *. The drive signal is converted into a drive signal for electrically driving the switching elements 5a to 5f by the PWM signal generator 13. The switching elements 5a to 5f are operated by the drive signal.

  With the above configuration, position sensorless sine wave drive is performed.

  Here, a general triangular wave comparison type PWM sine wave drive operation will be described. FIG. 12 is a diagram for explaining the operation of PWM sine wave drive for one phase. The magnitude of the output voltage command value of the inverter as a signal wave and the triangular wave as a carrier wave are compared, and the upper arm and the lower arm are based on the comparison result. The PWM signal for operating the switching elements is determined.

In addition, in order to perform PWM sine wave drive, the magnitude of the output voltage command value of the inverter that is a signal wave must be equal to or less than the triangular wave that is a carrier wave (see, for example, Non-Patent Document 1).

  Therefore, if the line voltage peak value of the inverter output is V and the DC voltage value of the inverter is Vdc, the relationship as shown in Expression (1) is established.

V ≦ √3 / 2 · Vdc = 0.866 Vdc (1)
That is, the maximum value of the output voltage of the inverter is 0.866 times the DC voltage (voltage utilization rate 86.6%), and the voltage is not sufficiently utilized.

  Therefore, as an inverter control method for improving the voltage utilization factor of the inverter, for example, an inverter control method described in Patent Document 2 as shown in FIG. 11 has been proposed.

  In FIG. 11, a three-phase two-phase conversion circuit 111 for three-phase to two-phase conversion of a three-phase AC voltage command given to the inverter, and first and second AC waveform signals and amplitude signals having the same frequency are separately calculated. A vector conversion circuit 112, a triple harmonic generator 113 for generating a triple harmonic signal having the same phase as the AC voltage command even if the frequency of the AC waveform signal is tripled, and a gain 114 for the amplitude signal Adders 116a to 116c that generate a final AC voltage command by adding a signal obtained by multiplying the signal obtained by multiplying the predetermined value and the third harmonic signal by the multiplier 115 to the original AC voltage command. With.

  Here, in the triple harmonic generation circuit 113, a triple harmonic signal having the same phase as the original AC voltage command is generated by performing an operation based on the triple angle formula expressed by Equation (2). The

V3f ′ = 4 · V1c ³ −3 · V1c (2)
(V3f ′: triple harmonic signal, V1c: AC waveform signal separated by the vector conversion circuit 112)
Japanese Patent No. 3419725 JP 2003-134443 A Inverter Drive Handbook (pp. 463-472) Inverter Drive Handbook Editorial Board Edition 1995 First Edition, published by Nikkan Kogyo Shimbun

  However, since the configuration described in Patent Document 1 does not have a means for improving the voltage utilization rate of the inverter, there is a problem that the motor cannot be operated at a high speed and the performance of the motor drive device is degraded. Was.

  Here, since a general brushless DC motor has a permanent magnet inside, it can generate electric power while rotating, but the amount of electric power generation increases in proportion to the number of rotations.

  Further, in order to operate the brushless DC motor as an electric motor instead of a generator, the voltage (output voltage of the inverter) applied to the brushless DC motor must be larger than the amount of power generation. Therefore, in the high-speed region, the voltage applied to the brushless DC motor (inverter output voltage) must be increased, but if there is no means for improving the voltage utilization rate of the inverter, the rotation speed It reaches its peak and cannot drive at high speed.

In addition, when using the method described in Patent Document 2 in order to improve the voltage utilization rate of the inverter, it is necessary to calculate the cube of the AC voltage command value in the calculation based on the triple angle formula. The calculation amount of the calculation means and the increase in the memory will not only increase the cost of the calculation means, but also increase the software design man-hour when changing from the conventional calculation means to the calculation means suitable for the calculation based on the triple angle formula. It had the problem that.

  The present invention solves the above-described conventional problems, and improves the voltage utilization rate of an inverter without increasing the cost of a calculation means such as a microcomputer by a simple calculation, and the motor drive for realizing high-speed operation of the motor An object is to provide an apparatus.

  In order to solve the above-described conventional problems, the electric motor drive device of the present invention has a plurality of switching element pairs each composed of an upper arm switching element arranged on the high voltage side and a lower arm switching element arranged on the low voltage side, An inverter that converts a DC voltage into an AC voltage of a desired frequency and voltage by the operation of the switching element and supplies the AC voltage as a drive voltage to a motor of a plurality of phases; and a current detection unit that detects a current flowing through a stator winding of the motor Current control means for creating a voltage command value for the motor from a current error between the current command value for the motor and the current detection value detected by the current detection means; and a voltage command value of 3 based on the value relating to the rotational output of the motor. Third-order harmonic phase compensation means for compensating the phase of the second-order harmonic, and third-order harmonics from the phase and voltage command value of the third-order harmonic compensated by the third-order harmonic phase compensation means. Each of the inverters based on the correction value of the voltage command value, the voltage command correction means for correcting the voltage command value by adding the third harmonic to the voltage command value, PWM signal generation means for generating a PWM signal for controlling the operation of the switching element, and the third harmonic phase compensation means increases the phase of the third harmonic in proportion to the value related to the rotational output of the motor. The third harmonic phase compensation value is set in

  By compensating for the phase shift between the voltage command value and the third harmonic by this third harmonic phase compensation means, the output voltage of the inverter can be maximized. The purpose is to improve the voltage utilization rate of the inverter without increasing the speed and realize high-speed operation of the motor.

  The electric motor drive device of the present invention has a plurality of switching element pairs each composed of an upper arm switching element arranged on the high voltage side and a lower arm switching element arranged on the low voltage side, and a DC voltage is generated by the operation of each switching element. An inverter that converts to an AC voltage of a desired frequency and voltage and supplies it as a driving voltage to a multi-phase motor, current detection means for detecting current flowing in the stator winding of the motor, current command value and current for the motor Current control means for creating a voltage command value for the motor from a current error from the current detection value detected by the detection means, voltage saturation detection means for detecting the degree of voltage saturation of the output voltage of the inverter, and voltage saturation detection A third-order harmonic that compensates for the phase of the third-order harmonic of the voltage command value based on the voltage saturation detected from the means and the value relating to the rotational output of the motor. Phase compensation means, third-order harmonic calculation means for deriving the third-order harmonic from the phase and voltage command value of the third-order harmonic compensated by the third-order harmonic phase compensation means, and the third-order harmonic as the voltage command value. Voltage command correction means for correcting the voltage command value by adding the wave, and PWM signal generation means for generating a PWM signal for controlling the operation of each switching element of the inverter based on the correction value of the voltage command value. The third-order harmonic phase compensation means sets the third-order harmonic phase compensation value so that the phase of the third-order harmonic increases in proportion to the value related to the rotational output of the motor, and then the voltage saturation is minimized. The third-order harmonic phase compensation value is successively increased or decreased so that

  The third harmonic phase compensation means compensates for a phase shift between the voltage command value and the third harmonic, and the third harmonic phase so that the voltage saturation detected from the voltage saturation detection means is minimized. By gradually increasing or decreasing the compensation amount, the output voltage of the inverter can always be maximized even if the load conditions change significantly, and simple calculations can be used without increasing the cost of computing means such as a microcomputer. The purpose is to improve the voltage utilization factor and realize high-speed operation of the electric motor.

  The motor drive device of the present invention can maximize the output voltage of the inverter by compensating for the phase shift between the voltage command value and the third harmonic by the third harmonic phase compensation means, and by a simple calculation. It is possible to improve the voltage utilization rate of the inverter without increasing the cost of calculation means such as a microcomputer and to realize high-speed operation of the electric motor.

The first invention has a plurality of switching element pairs each composed of an upper arm switching element arranged on the high voltage side and a lower arm switching element arranged on the low voltage side, and a DC voltage is converted to a desired frequency by the operation of each switching element. Detected by an inverter that converts the voltage into an AC voltage and supplies it as a drive voltage to a multi-phase motor, current detection means for detecting the current flowing in the stator winding of the motor, and a current command value and current detection means for the motor Current control means for creating a voltage command value of the motor from the current error from the detected current value, voltage saturation detection means for detecting the degree of voltage saturation of the output voltage of the inverter, and voltage saturation detection means. Third-order harmonic phase compensation means for compensating the third-order harmonic phase of the voltage command value based on the voltage saturation and the value related to the rotational output of the motor; By adding the third harmonic to the voltage command value, the third harmonic calculation means for deriving the third harmonic from the phase of the third harmonic compensated by the second harmonic phase compensation means and the voltage command value, Voltage command correction means for correcting the voltage command value; and PWM signal generation means for generating a PWM signal for controlling the operation of each switching element of the inverter based on the correction value of the voltage command value, the third harmonic. The phase compensation means sets the third harmonic phase compensation value so that the phase of the third harmonic is increased in proportion to the value related to the rotational output of the motor, and then the third order so that the voltage saturation is minimized. By gradually increasing or decreasing the harmonic phase compensation value, the phase shift between the voltage command value and the third harmonic can be compensated, and the inverter output voltage can always be maximized even when the load conditions change significantly. With a simple calculation Without cost means to improve the inverter voltage utilization, it can achieve high-speed operation of the motor.

The second invention is particularly the motor drive apparatus according to the first invention, wherein the third-order harmonic phase compensation means includes the current value of the voltage saturation and the third-order harmonic phase compensation at that time so that the voltage saturation is minimized. Each value is compared with the previous history value of the voltage saturation and the third-order harmonic phase compensation value at that time, and based on the comparison result, the third-order harmonic phase compensation value is increased or decreased by a predetermined change amount. By setting the subharmonic phase compensation value, even when the load condition changes significantly, the optimum third-order harmonic phase compensation value can be searched and set sequentially, and the inverter output voltage can always be maximized. It is possible to improve the voltage utilization rate of the inverter without increasing the cost of calculation means such as a microcomputer by simple calculation, and to realize high-speed operation of the motor.

The third aspect of the invention is particularly the electric motor drive device of the second aspect of the invention, wherein the third-order harmonic phase compensation means compensates the change amount by the difference between the current value of the voltage saturation and the previous history value, thereby obtaining the third-order. The amount of change, which is a unit amount that increases or decreases the harmonic phase compensation amount, is linearly compensated based on the ratio of change between the current value of voltage saturation and the previous history value, so it is optimal when the load situation changes significantly. By setting the third-order harmonic phase compensation amount at a high speed, the computation time associated with the setting of the third-order harmonic phase compensation amount can be shortened, and further after the third-order harmonic phase compensation amount has converged to the optimum value. Fluctuations can also be suppressed.

The fourth aspect of the invention is particularly the motor drive device according to any one of the first to third aspects of the invention, wherein the third-order harmonic phase compensation value has at least a preset upper limit value or lower-limit value, The excessive compensation of the wave phase can be prevented, and unstable operation of the electric motor such as hunting and turbulence can be avoided.

A fifth invention is, in particular, in motor drive apparatus of the invention of any one of the 1-4, values for the rotational output of the motor, the compensation only third harmonic of the phase is greater than a preset reference value By doing so, it is possible to reduce the amount of calculation and memory in the calculation means such as a microcomputer, and the cost of the calculation means can be reduced.

A sixth aspect of the invention, particularly in the motor driving apparatus of any one of the first to 5 to compensate for the phase of synchronization with the control cycle of the inverter 3 harmonic, one cycle of the control period of at least an inverter The third harmonic phase can be compensated for each time, and the third harmonic phase compensation can be reflected in real time on the output voltage of the inverter.

The seventh aspect of the invention is the electric motor drive device of the sixth aspect of the invention, in particular, only when the value relating to the rotational output of the electric motor is equal to or less than a preset reference value, every three control cycles of the inverter (n ≧ 2). Compensating the phase of the subharmonic can reduce the amount of calculation and memory in the calculation means such as a microcomputer, and can realize cost reduction of the calculation means.

Eighth aspect of the invention is particularly in the motor drive device of any one of the first to 7 only if below a predetermined value there is a difference between the current value and the previous history value of the rotation speed of the motor 3 harmonic phase If the difference is larger than a predetermined value, the third harmonic phase compensation amount set in advance according to the rotation speed of the motor is set in advance, so that even if the load condition changes significantly, Set the amount of subharmonic phase compensation to a value suitable for the rotational speed to avoid unstable operation of the motor, such as hunting and turbulence, and to prevent the motor speed from being drastically reduced at high speeds. Can be improved.

A ninth aspect of the invention, particularly in the motor driving device of any one of the first 5, 7 or 8, switches the compensation so that the value becomes continuous when switching Yes No compensation of the phase of the third harmonic As a result, the control stability and reliability associated with switching with and without phase compensation of the third harmonic can be improved, and unstable operation of the electric motor such as hunting and turbulence can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a system configuration diagram of an electric motor drive device according to a first embodiment of the present invention. In FIG. 1, the electric motor drive device 3 includes an inverter 5 including free-wheeling diodes 6a to 6b paired with a plurality of switching elements 5a to 5f, a voltage detection unit 10, a speed control unit 11, a current control unit 12, PWM signal generation unit 13, induced voltage estimation unit 14, rotor position speed estimation unit 15, voltage command correction unit 16, rotation output detection unit 17, third harmonic calculation unit 18, third harmonic And a phase compensation unit 19.

  The input voltage from the AC power source 1 is rectified to DC by the rectifier circuit 2, and the DC voltage is converted into a three-phase AC voltage by the AC / DC converter 5, thereby driving the electric motor 4 that is a brushless DC motor.

  In the motor driving device 3, the speed control unit 11 sets the target speed ω * and the current speed ω1 (the current value of the estimated speed estimated by the rotor magnetic pole position speed estimating means 15) in order to realize the target speed given from the outside. The current command value I * is calculated by PI control so that the speed error Δω with respect to is zero.

  The current control unit 12 is obtained from the phase current command value of the stator winding created based on the current command value I * calculated by the speed control unit 11, the current detectors 7a and 7b, and the current detection unit 9. The voltage command value v * is calculated by PI control so that the current error from the current detection value becomes zero.

  The third-order harmonic phase compensation unit 19 determines a third-order harmonic phase compensation value so that the phase of the third-order harmonic increases in proportion to the value related to the rotation output of the electric motor 4 obtained by the rotation output detection unit 17. To do.

  The third harmonic calculation unit 18 derives the third harmonic from the phase of the third harmonic compensated by the third harmonic phase compensation unit 19 and the voltage command value v * calculated by the current control unit 12. .

  The voltage command correction unit 16 derives the voltage command correction value vh * by adding the third harmonic derived by the third harmonic calculation unit 18 to the voltage command value v *.

  The induced voltage estimation unit 14 includes the current detection value of the electric motor 4 detected by the current detectors 7a and 7b and the current detection unit 9, the voltage command value V *, the voltage dividing resistors 8a and 8b, and the DC voltage detection unit 10. Based on the detected DC voltage information of the inverter 5, the induced voltage generated in each phase of the stator winding of the electric motor 4 is estimated.

  The rotor position speed estimation means 15 estimates the magnetic pole position and speed of the rotor in the electric motor 4 using the induced voltage estimated by the induced voltage estimation unit 14. Based on the information on the estimated rotor magnetic pole position, the voltage command correction means 16 generates a signal for driving the switching elements 5a to 5f in order for the inverter 5 to output the voltage command value vh *. The drive signal is converted into a drive signal for electrically driving the switching elements 5a to 5f by the PWM signal generator 13. The switching elements 5a to 5f are operated by the drive signal.

  In FIG. 1, two current detectors 7 a and 7 b that detect the phase current of the motor 4 are provided and used for estimating the rotor position speed. However, the DC current on the input side of the inverter 5 (the inverter 5 Needless to say, means such as detecting the phase current of the electric motor 4 from the bus current) may be used.

  In FIG. 1, the speed control is performed so that the speed of the motor 4 follows the target speed ω * given from the outside. However, the torque of the motor 4 may be controlled. It goes without saying that it is good.

  First, the necessity for compensating the phase of the third harmonic will be described.

  As shown in FIG. 13, in the conventional motor driving device, the current command value I * calculated by the speed control unit 11 in the current control unit 12 to be described later is obtained from the current detectors 7a and 7b and the current detection unit 9. Since the voltage command value v * is calculated by PI control so that the current error from the detected current value becomes zero, the phase of the voltage command value v * changes according to the load condition.

  For this reason, when the phase of the voltage command value v * is greatly shifted, the phase of the voltage command value and the third harmonic is greatly shifted as shown in FIG. 9, and as a result, the voltage command correction value is changed to the voltage command value. In some cases, the voltage utilization rate of the inverter 5 cannot be improved.

  Therefore, in any case, in order to improve the voltage utilization factor of the inverter, it is necessary to compensate the phase of the third harmonic as shown in FIG.

  Next, a method for compensating the phase of the third harmonic will be described.

FIG. 5 shows an example of theoretical characteristics of the third-order harmonic phase compensation amount α (phase shift between the voltage command value and the third-order harmonic) when the voltage utilization factor of the inverter 5 is maximized. As shown in FIG.
The optimum third-order harmonic phase compensation amount α that maximizes the voltage utilization rate of the inverter 5 varies depending on the load conditions such as the current flowing through the motor and the rotational speed (the third-order harmonic phase compensation amount also depends on the rotational speed). The characteristic of α changes, but it is mainly due to the current flowing through the motor).

  Further, the characteristic of the third-order harmonic phase compensation amount α is expressed by a linear function with respect to the current flowing through the motor as shown in FIG. .

  Although the characteristic of the third-order harmonic phase compensation amount α is approximated by a linear function, it is not particularly limited to the first-order function. For example, the characteristic of the actual third-order harmonic phase compensation amount α Needless to say, the phase of the third harmonic may be compensated as described above.

  Further, in order to know the load condition, the rotation output detection unit 17 uses a current command value I * obtained from the speed control unit 11 described later or a phase current detection value obtained from the current detectors 7a and 7b and the current detection unit 9. Any current value (iu, iv, iw), any speed value of target speed ω * or estimated speed ω1 (estimated by rotor magnetic pole position speed estimating means 15 described later), or current command An equivalent motor output obtained by the product of either the current value of the value I * or the phase current detection value (iu, iv, iw) and the speed value of the target speed ω * or the estimated speed ω1 is output.

  Note that the current command value I *, the target speed ω *, and the estimated speed ω1 are set to one value for the driving situation and the load situation, so that the output value of the rotation output detector 18 is one. Since the current detection values (iu, iv, iw) are for three phases, they can be set to one value, for example, by calculating the effective value I1 for one phase. The equivalent motor output can be derived from the product of the current value (I * or effective value I1) and the speed value (ω * or ω1).

  However, as described above, the characteristic of the third-order harmonic phase compensation amount α mainly changes depending on the current flowing through the motor, and therefore, the current value of either the current command value I * or the effective value I1 should be used. When the load increases in proportion to the rotational speed of the electric motor, either the target speed ω * or the estimated speed ω1 may be used. Further, by using the equivalent motor output obtained by the product of the current value and the speed value, it is possible to know the situation of the load more.

  Below, the case where the output of the rotation output detection part 18 is the electric current command value I * is demonstrated concretely.

  First, the speed control unit 11 performs PI control represented by Expression (3) such that the speed error Δω (= ω * −ω1 / np) between the target speed ω * given from the outside and the estimated speed ω1 becomes zero. To calculate the current command value I *.

I * = KPW · (ω * −ω1 / np) + KIW · Σ (ω * −ω1 / np)
= KPW · Δω + KIW · ΣΔω (3)
(KPW: Speed control proportional gain, KIW: Speed control integral gain)
However, since the target speed ω * is the mechanical angular speed and the estimated speed ω1 is the electrical angular speed, the number of pole pairs np (1/2 of the number of poles) of the electric motor 4 is divided in order to set ω1 to the mechanical angular speed.

  Next, the current control unit 12 uses the current command value I * calculated by the speed control unit 11 and the current command phase βT to calculate the dq-axis current command value (id *, Iq *).

id * = − I * · sin (βT) (4)
iq * = I * · cos (βT) (5)
Further, the phase current command value (iu *, iv *, iw *) of the stator winding is determined by the dq axis current command value (id *, iq *) and the current position θ1 (by the rotor magnetic pole position speed estimation means 15). The current value of the estimated position) is obtained by performing two-phase to three-phase conversion by the calculations of Expressions (6) to (8).

  However, the estimated position θ1 is an electrical angle.

  Since the two-phase to three-phase conversion is publicly known, the description thereof is omitted.

iu * = {√ (2/3)} · {id * · cos (θ1) −iq * · sin (θ1)} (6)
iv * = {√ (2/3)} · {id * · cos (θ1−120 °) −iq * · sin (θ1−120 °)} (7)
iw * = {√ (2/3)} · {id * · cos (θ1 + 120 °) −iq * · sin (θ1 + 120 °)} (8)
Therefore, the current error between the phase current command value (iu *, iv *, iw *) and the phase current detection value (iu, iv, iw) obtained from the current detectors 7a, 7b and the current detection unit 9 becomes zero. As described above, the voltage command value (vu *, VK *, KIKn, n = 1, 2, 3 (for three phases)) is subjected to the PI control represented by the equations (9) to (11) using the current control gain. vv *, vw *) is calculated.

vu * = KPK1 · (iu * −iu) + KIK1 · Σ (iu * −iu) (9)
vv * = KPK2 · (iv * −iv) + KIK2 · Σ (iv * −iv) (10)
vw * = KPK3 · (iw * −iw) + KIK3 · Σ (iw * −iw) (11)
The phase current detection values (iu, iv, iw) are subjected to three-phase to two-phase conversion to obtain dq-axis current detection values (id, iq), and dq-axis current command values (id *, iq *) and dq-axis After obtaining the dq axis voltage command value (vd *, vq *) by PI control so that the current error from the current detection value (id, iq) becomes zero, the dq axis voltage command value (vd *, vq *) The phase voltage command values (vu *, vv *, vw *) may be obtained by performing two-phase to three-phase conversion.

  Since the three-phase to two-phase conversion is also known in the same manner as the two-phase to three-phase conversion, its description is omitted.

  Specifically, the dq-axis current command value (id, iq) is obtained by the calculations of Expressions (12) and (13).

id = {√ (2)} · {iu · sin (θ1 + 60 °) + iv · sin (θ1)} (12)
iq = {√ (2)} · {iu · cos (θ1 + 60 °) + iv · cos (θ1)} (13)
Further, the dq-axis voltage command values (vd *, vq *) are obtained by the calculations of equations (14) and (15).

vd * = KPD · (id * −id) + KID · Σ (id * −id) (14)
vq * = KPQ · (iq * −iq) + KIQ · Σ (iq * −iq) (15)
(KPD: d-axis current proportional gain, KID: d-axis current integral gain, KPQ: q-axis current proportional gain, KIQ: q-axis current integral gain)
Therefore, the phase voltage command values (vu *, vv *, vw *) are calculated by the equations (16) to (18) by converting the dq axis voltage command values (vd *, vq *) into two-phase to three-phase. Is required.

vu * = {√ (2/3)} · {vd * · cos (θ1) −vq * · sin (θ1)}
... (16)
vv * = {√ (2/3)} · {vd * · cos (θ1−120 °) −vq * · sin (θ1−120 °)} (17)
vw * = {√ (2/3)} · {vd * · cos (θ1 + 120 °) −vq * · sin (θ1 + 120 °)} (18)
Next, in the third-order harmonic phase compensation unit 19, the third-order harmonic phase compensation amount is set so that the phase of the third-order harmonic increases in proportion to the current command value I * which is the output value of the rotation output detection unit 17. Set α.

  FIG. 3 is a diagram showing an operation explanatory diagram of the third-order harmonic phase compensation unit 19 according to the first embodiment of the present invention. The third-order harmonic phase compensation amount α is a preset upper limit value αmax. And a lower limit value αmin, which is expressed as in Expression (19).

α = αmin (I * ≦ P1)
α = Kα · (I * −P1) + αmin (P1 <I * ≦ P2)
α = αmax (I * ≧ P2)
However, Kα = (αmax−αmin) / (P2−P1)
... (19)
Note that the third-order harmonic phase compensation amount α does not necessarily have to include both the upper limit value αmax and the lower limit value αmin as shown in FIG. 3, and one of them depends on the use environment of the motor driving device and the operating condition of the motor. You may prepare only.

  Thus, since the third-order harmonic phase compensation unit 19 according to the present embodiment has at least a preset upper limit value or lower limit value, excessive compensation of the third-order harmonic phase can be prevented, Unstable operation of the motor such as hunting and turbulence can be avoided.

  Next, a specific method regarding the timing of phase compensation of the third harmonic according to the present invention will be described below.

  The electric motor drive device of the present invention compensates the phase of the third harmonic in synchronization with the control cycle of the inverter, compensates the phase of the third harmonic for each cycle of the control cycle of the inverter, and results thereof. Can be reflected in the inverter output (PWM signal) in real time, so that the load status can be reflected in the drive performance of the electric motor without time delay.

  In addition, the motor drive device of the present invention sets the phase of the third harmonic every n cycles (n ≧ 2) of the control cycle of the inverter only when the value related to the rotational output of the motor is equal to or less than a preset reference value P1. To compensate.

  Here, referring to the characteristics of the third-order harmonic phase compensation amount α shown in FIG. 5, since the phase shift between the voltage command value and the third-order harmonic is small, the effect of the third-order harmonic phase compensation is small in this case. Become.

  Therefore, when the effect of the third-order harmonic phase compensation is small, specifically, when the third-order harmonic phase compensation unit shown in FIG. Compensating the phase of the third harmonic for each cycle (n ≧ 2) can reduce the amount of calculation and memory in the calculation means such as a microcomputer, and can realize cost reduction of the calculation means.

  Further, a specific method relating to the switching with or without compensation of the phase of the third harmonic according to the present invention will be described below.

  The electric motor drive device of the present invention compensates for the phase of the third harmonic only when the value related to the rotational output of the electric motor is larger than a preset reference value.

  Here, referring to the characteristics of the third-order harmonic phase compensation amount α shown in FIG. 5, since the phase shift between the voltage command value and the third-order harmonic is small, the effect of the third-order harmonic phase compensation is small in this case. Become.

  Therefore, when the effect of the third-order harmonic phase compensation is large, specifically, when the third-order harmonic phase compensation unit shown in FIG. By compensating for this, it is possible to reduce the amount of computation and memory in the computing means such as a microcomputer, and the cost of the computing means can be reduced.

In addition, the electric motor drive device of the present invention compensates for the phase of the third harmonic only when the difference between the current value of the motor rotation speed and the previous history value is a predetermined value δ or less, and the difference is larger than the predetermined value. In this case, the third-order harmonic phase compensation amount α set in advance according to the rotation speed of the electric motor is set.

  Therefore, even when the load conditions change significantly, the third-order harmonic phase compensation amount α can be set to a value suitable for the rotational speed to avoid unstable operation of the electric motor such as hunting and turbulence, and in the high speed range. The reliability of the electric motor drive system can be improved by preventing an extreme decrease in the rotational speed.

  Furthermore, the electric motor drive device of the present invention performs compensation switching so that the value becomes continuous when the third harmonic phase is compensated for.

  Here, FIG. 6 shows an operation explanatory diagram at the time of switching with or without the compensation of the phase of the third harmonic according to the present invention. As shown in FIG. 6, by providing a switching grace period at the time of switching with or without compensation, the third-order harmonic phase compensation amount α is not changed suddenly, so that the third-order harmonic phase is compensated. The control stability and reliability associated with the switching of the motor can be improved, and the unstable operation of the motor such as hunting and turbulence can be prevented.

  Next, in the third harmonic calculation unit 18, the voltage command value derived by the current control unit 12, specifically, the dq-axis voltage command value derived by the calculation of Expressions (14) and (15) ( vd *, vq *) and the third-order harmonic phase compensation amount α set by the third-order harmonic phase compensation unit 19 are used to calculate the third-order harmonic v3f by performing the calculation represented by the equation (20). To do.

v3f = {√ (2/3)} · {vd * · cos ( 3 · θ1 + α) −vq * · sin ( 3 · θ1 + α)} (20)
Next, in the voltage command correction unit 16, third-order harmonics are applied to the phase voltage command values (vu *, vv *, vw *) derived by the current control unit 12 as shown in equations (21) to (23). The phase voltage command correction values (vuh *, vvh *, vwh *) are derived by adding the third-order harmonics v3f derived by the calculation unit 18.

vuh * = vu * + K3f · v3f (21)
vvh * = vv * + K3f · v3f (22)
vwh * = vw * + K3f · v3f (23)
Here, K3f is a gain, and in order to maximize the voltage utilization rate of the inverter 5, a value of about 12% to 20% with respect to the phase voltage command value is desirable.

  Further, in the voltage command correction unit 16, a signal for driving the switching elements 5a to 5f in order for the inverter 5 to output the phase voltage command values (vuh *, vvh *, vwh *) obtained as described above. Is generated.

  Next, a method for estimating the induced voltage of the electric motor in this embodiment will be described.

  The induced voltage values (eu, ev, ew) induced in the windings of the respective phases use the phase current detection values (iu, iv, iw) and the phase voltage command values (vu *, vv *, vw *). Is obtained by the calculation of the equations (24) to (26).

eu = vu * −R · iu−L · d (iu) / dt (24)
ev = vv * −R · iv−L · d (iv) / dt (25)
ew = vw * −R · iw−L · d (iw) / dt (26)
Here, R is the resistance per phase of the winding of the electric motor 4, and L is its inductance. D (iu) / dt, d (iv) / dt, and d (iw) / dt are time derivatives of iu, iv, and iw, respectively.

  Moreover, the following formula is obtained by developing formula (24) to formula (26).

eu = vu * -R.iu- (la + La) .d (iu) / dt
-Las · cos (2θ1) · d (iu) / dt
-Las · iu · d {cos (2θ1)} / dt
+ 0.5 · La · d (iv) / dt
-Las · cos (2θ1-120 °) · d (iv) / dt
-Las · iv · d {cos (2θ1-120 °)} / dt
+ 0.5 · La · d (iw) / dt
−Las · cos (2θ1 + 120 °) · d (iw) / dt
-Las · iw · d {cos (2θ1 + 120 °)} / dt
... (27)
ev = vv *
-R ・ iv
− (La + La) · d (iv) / dt
−Las · cos (2θ1 + 120 °) · d (iv) / dt
-Las · iv · d {cos (2θ1 + 120 °)} / dt
+ 0.5 · La · d (iw) / dt
−Las · cos (2θ1) · d (iw) / dt
-Las · iw · d {cos (2θ1)} / dt
+ 0.5 · La · d (iu) / dt
-Las · cos (2θ1-120 °) · d (iu) / dt
-Las · iu · d {cos (2θ1-120 °)} / dt
... (28)
ew = vw *
-R ・ iw
− (La + La) · d (iw) / dt
-Las.cos (2θ1-120 °) · d (iw) / dt
-Las · iw · d {cos (2θ1-120 °)} / dt
+ 0.5 · La · d (iu) / dt
−Las · cos (2θ1 + 120 °) · d (iu) / dt
-Las · iu · d {cos (2θ1 + 120 °)} / dt
+ 0.5 · La · d (iv) / dt
−Las · cos (2θ1) · d (iv) / dt
-Las · iv · d {cos (2θ1)} / dt
... (29)
Here, R is the resistance per phase of the winding, la is the leakage inductance per phase of the winding, L
a is the average value of the effective inductance per phase of the winding, and Las is the amplitude of the effective inductance per phase of the winding. D (iu) / dt, d (iv) / dt, and d (iw) / dt are obtained by first-order Euler approximation. Note that the u-phase current iu is obtained by changing the sign of the sum of the v-phase current iv and the w-phase current iw.

  Furthermore, when Expressions (27) to (29) are simplified, Expressions (30) to (32) shown below are obtained. Here, assuming that the phase current detection values (iu, iv, iw) are sine waves, the phase current detection values (iu, iv, iw) are created from the current command amplitude I * and the current command phase βT. Simplified.

eu = vu *
+ R ・ I * ・ sin (θ1 + βT)
+1.5 · (la + La) · cos (θ1 + βT)
-1.5 · Las · cos (θ1-βT) (30)
ev = vv *
+ R ・ I * ・ sin (θ1 + βT−120 °)
+1.5 ・ (la + La) ・ cos (θ1 + βT−120 °)
-1.5 · Las · cos (θ1-βT-120 °) (31)
ew = vw *
+ R ・ I * ・ sin (θ1 + βT + 120 °)
+1.5 ・ (la + La) ・ cos (θ1 + βT + 120 °)
-1.5 · Las · cos (θ1−βT + 120 °) (32)
In the present embodiment, the induced voltage estimation unit 14 obtains an induced voltage estimated value (eu, ev, ew) from Expressions (30) to (32).

  Next, the rotor position speed estimation unit 15 estimates the magnetic pole position and speed of the rotor in the electric motor 4 using the induced voltage estimated values (eu, ev, ew). The rotor position / speed estimation unit 15 corrects the estimated position θ1 recognized by the electric motor drive device 3 using the error of the induced voltage, thereby obtaining the estimated position θ1 by converging it to a true value. Also, an estimated speed ω1 is generated therefrom.

  First, an induced voltage reference value (eum, evm, ewm) of each phase is obtained by the following equation.

eum = em · sin (θ1 + βT) (33)
evm = em · sin (θ1 + βT−120 °) (34)
ewm = em · sin (θ1 + βT + 120 °) (35)
Here, the induced voltage amplitude value em is obtained by matching the amplitude values of eu, ev, and ew.

  A deviation ε between the induced voltage reference value esm (s = u, v, w (s represents a phase)) thus obtained and the induced voltage estimated value es is obtained.

ε = es−esm (s = u, v, w) (36)
Since the estimated position θ1 becomes a true value when the deviation ε becomes 0, the estimated position θ1 is obtained by performing PI calculation using the deviation ε so that the deviation ε is converged to 0. Further, the estimated speed ω1 is obtained by calculating the fluctuation value of the estimated position θ1.

  Finally, the PWM signal generation unit 13 converts the switching elements 5a to 5f into drive signals for electrically driving based on the drive signal obtained from the voltage command correction unit 16. The switching elements 5a to 5f are operated by the drive signal.

  As described above, the electric motor drive device 3 according to the present embodiment generates the estimated position θ1 using the deviation ε between the induced voltage estimated value and the induced voltage reference value, allows the sinusoidal phase current to flow, and the third harmonic. By compensating for the phase shift between the voltage command values (vu *, vv *, vw *) and the third-order harmonic v3f by the phase compensation unit 19, the output voltage of the inverter 5 can be maximized, and by a simple calculation It is possible to improve the voltage utilization rate of the inverter 5 without increasing the cost of calculation means such as a microcomputer, and to realize high-speed operation of the motor 4.

(Embodiment 2)
FIG. 2 is a system configuration diagram of an electric motor drive device according to the second embodiment of the present invention. The same components as those of the motor drive device shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted because it is duplicated. Hereinafter, different portions will be described.

  In FIG. 2, the electric motor drive device 3 includes an inverter 5 composed of freewheeling diodes 6 a to 6 b paired with a plurality of switching elements 5 a to 5 f, a voltage detection unit 10, a speed control unit 11, a current control unit 12, PWM signal generation unit 13, induced voltage estimation unit 14, rotor position speed estimation unit 15, voltage command correction unit 16, rotation output detection unit 17, third harmonic calculation unit 18, third harmonic A phase compensation unit 19 and a voltage saturation detection unit 20 are provided.

  Parts different from the motor drive device 3 shown in FIG. 1 are as follows.

  In the third-order harmonic phase compensation unit 19, the third-order harmonic phase compensation amount α is set so that the phase of the third-order harmonic increases in proportion to the value related to the rotation output of the electric motor 4 obtained by the rotation output detection unit 17. After the setting, the voltage command is obtained by sequentially increasing / decreasing the third-order harmonic phase compensation amount α so that the voltage saturation σ representing the degree of voltage saturation of the inverter 5 obtained from the voltage saturation detector 20 is minimized. The phase shift between the value and the third harmonic is compensated.

  In FIG. 2, two current detectors 7 a and 7 b that detect the phase current of the motor 4 are provided and used for estimating the rotor position speed. However, the DC current on the input side of the inverter 5 (the inverter 5 Needless to say, means such as detecting the phase current of the electric motor 4 from the bus current) may be used.

  In FIG. 2, the speed control is performed so that the speed of the motor 4 follows the target speed ω * given from the outside. However, the torque of the motor 4 may be controlled. It goes without saying that it is good.

  Hereinafter, a specific method will be described.

  First, the third-order harmonic phase compensation unit 19 derives the third-order harmonic phase compensation amount α by the calculation of Expression (19), and then determines the degree of voltage saturation of the inverter 5 detected from the voltage saturation degree detection unit 20. The third-order harmonic phase compensation amount α is successively increased or decreased so that the expressed voltage saturation σ is minimized.

  FIG. 4 is a diagram for explaining the operation of the third-order harmonic phase compensation unit 19 according to the second embodiment of the present invention, and shows the characteristics of the voltage saturation σ with respect to the third-order harmonic phase compensation amount α under a certain operating condition. Yes. In FIG. 4, the third-order harmonic phase compensation amount αs that provides the minimum voltage saturation σmin is the optimum value, and by setting αs as the third-order harmonic phase compensation amount, the output voltage of the inverter 5 is maximized, that is, the inverter A voltage utilization factor of 5 is maximized.

  Next, a specific method for sequentially increasing / decreasing the third-order harmonic phase compensation amount α will be described.

  FIG. 7 is a first example of the flowchart in the second embodiment of the third-order harmonic phase compensator according to the present invention.

  First, it is determined in step S1 whether a predetermined time has elapsed. If the predetermined time has not elapsed (NO in S1), the processing described later is stopped until the predetermined time has elapsed. In step S2, the difference between the current value ωnow and the previous history value ωlast of the rotational speed ω of the motor represented by the equation (37) is calculated.

Δωn = ωnow−ωlast (37)
In step S3, the magnitude of the speed fluctuation is determined, that is, it is determined whether or not the absolute value | Δωn | of the speed difference is within a predetermined value δ. If the speed fluctuation is larger than predetermined value δ (NO in S3), the processing after step S9 described later is performed. If the speed fluctuation is within predetermined value δ (YES in S3), the current value of voltage saturation σ is read in step S4, and further the current value of voltage saturation σ represented by equation (38) in step S5. The difference between σnow and the previous history value σlast, and the difference between the current value αnow of the third-order harmonic phase compensation amount α expressed by the equation (39) and the previous history value αlast are performed.

Δσn = σnow−σlast (38)
Δαn = αnow−αlast (39)
In step S6, whether Δσn × Δαn is positive or negative is determined. If Δσn × Δαn is negative (NO in S6), the processing from step S8 described later is performed, and conversely, if Δσn × Δαn is positive (S6 In step 7), the value is decreased by a change amount Δα from the current value of the third-order harmonic phase compensation amount α in step 7.

  On the other hand, if Δσn × Δαn is negative (NO in step S6), the value is increased by the change amount Δα from the current value of the third-order harmonic phase compensation amount α. When the speed fluctuation is larger than predetermined value δ (NO in S3), third-order harmonic phase compensation amount α is set to initial value αini.

  Finally, in step S10, values are stored as shown in equations (40) to (43), the first process is terminated, and such a process is repeated every predetermined time.

ωlast = ωnow (40)
σlast = σnow (41)
αlast = αnow (42)
αnow = α (43)
Next, the processing flow as described above will be specifically described with reference to FIG.

  First, consider a case where the third-order harmonic phase compensation amount α is α1, or a case where the initial value αini is obtained when the speed fluctuation is larger than a predetermined value δ. Further, it is assumed that the value of this third-order harmonic phase compensation amount α (α1 or αini) is increased by a change amount Δα and set to α2.

  Here, since the magnitude relationship of the third-order harmonic phase compensation amount α is α1 <α2 and the magnitude relationship of the voltage saturation σ is σ1> σ2, Δσn × Δαn is negative, and the processing of Step 6 and Step 8 is performed. Thus, the third-order harmonic phase compensation amount α is further increased by the change amount Δα to α3.

  Thereafter, by repeating the same processing as described with reference to FIG. 7, the third-order harmonic phase compensation amount α can be converged to the optimum value αs.

In FIG. 4, after the convergence to the optimum value αs, the third-order harmonic phase compensation amount α varies between α3 and α4 with the optimum value αs as the center, but the change amount Δα is an appropriate value. Therefore, it is possible to minimize the performance degradation in the high-speed operation of the electric motor accompanying the fluctuation.

  As a result, even when the load condition changes significantly, the optimum third-order harmonic phase compensation value can be searched and set sequentially, and the inverter output voltage can always be maximized. It is possible to improve the voltage utilization rate of the inverter without increasing the cost of the calculation means and realize high-speed operation of the electric motor.

  Next, FIG. 8 is a second example of the flowchart in the second embodiment of the third-order harmonic phase compensation unit 19 according to the present invention. The same steps as those in the flowchart shown in FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted because it is duplicated.

  In step S21, a new change amount Δα expressed by Expression (44) is derived using the previous history value Δα0 of the change amount Δα, the current value σnow of the voltage saturation σ, and the previous history value σlast.

Δα = Δα0 × σnow / (σlast + σs) (44)
Here, σs is a minute amount for preventing zero percent.

  In step S22, after the initial value αini is set in step S9, the maximum value αmax and the minimum value αini of the third-order harmonic phase compensation amount α are read, and the processing after step S25 described later is performed.

  Further, in step S23, it is determined whether or not the third-order harmonic phase compensation amount α that is successively increased or decreased in steps S7 and S8 is within the range of the maximum value αmax and the minimum value αmin. When third-order harmonic phase compensation amount α is within the range of maximum value αmax and minimum value αmin (YES in S23), the processing after step S25 described below is performed, and conversely, when it is not within the range ( In step S23, the third-order harmonic phase compensation amount α is set to the maximum value αmax or the minimum value αmin.

  Finally, in step S25, values are stored as shown in equations (40) to (43) and (45), respectively, and the first processing is terminated, and such processing is repeated every predetermined time.

Δα0 = Δα (45)
The amount of change Δα that increases or decreases the third-order harmonic phase compensation amount α is linearly compensated based on the ratio between the current value σnow of the voltage saturation σ and the previous history value σlast, and therefore the flowchart of FIG. 7 is used. As compared with the case, the third-order harmonic phase compensation amount α can be increased or decreased at high speed to converge the voltage saturation σ to the optimum value σs.

  As described above, the electric motor drive device 3 according to the present embodiment generates the estimated position θ1 using the deviation ε between the induced voltage estimated value and the induced voltage reference value, allows the sinusoidal phase current to flow, and the third harmonic. The phase compensation unit 19 compensates for the phase shift between the voltage command value (vu *, vv *, vw *) and the third harmonic v3f, and the voltage saturation σ detected from the voltage saturation detection unit 20 is minimized. By gradually increasing or decreasing the third-order harmonic phase compensation amount α, the output voltage of the inverter 5 can always be maximized even if the load condition changes significantly. The voltage utilization factor of the inverter 5 can be improved without increasing the cost of the means, and the motor 4 can be operated at high speed.

As described above, the motor drive device according to the present invention can maximize the output voltage of the inverter by compensating for the phase shift between the voltage command value and the third harmonic by the third harmonic phase compensator. Because it can improve the voltage utilization rate of the inverter without increasing the cost of calculation means such as a microcomputer by simple calculation, and realize high-speed operation of the motor, an encoder such as a compressor driving motor in an air conditioner The present invention can be applied not only when the position sensor cannot be used, but also when the position sensor can be provided, such as a servo drive.

The system block diagram of the electric motor drive device in the 1st Embodiment of this invention The system block diagram of the electric motor drive device in the 2nd Embodiment of this invention Operation explanatory diagram in the first embodiment of the third-order harmonic phase compensator according to the present invention. Operation explanatory diagram in the second embodiment of the third-order harmonic phase compensator according to the present invention. The figure which shows an example of the theoretical characteristic of the 3rd harmonic phase compensation value when the voltage utilization factor of an inverter becomes the maximum Operation explanatory diagram at the time of switching of compensation of the third harmonic phase compensator according to the present invention The flowchart in 2nd Embodiment of the 3rd harmonic phase compensation part concerning this invention The flowchart in 2nd Embodiment of the 3rd harmonic phase compensation part concerning this invention Voltage waveform diagram when the third harmonic phase is not compensated Voltage waveform diagram for compensating the third harmonic phase Control block diagram of a conventional inverter control device for improving the output voltage of the inverter Operational explanation diagram of PWM wave sine wave drive of general triangular wave comparison method System configuration diagram of a conventional motor drive device

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Electric motor drive device 4 Electric motor 5 Inverter 5a-5f Switching element 6a-6f Free-wheeling diode 7a, 7b Current detector 8a, 8b Voltage dividing resistor 9 Current detection part 10 DC voltage detection part 11 Speed control part 12 Current control unit 13 PWM signal generation unit 14 Induced voltage estimation unit 15 Rotor position speed estimation unit 16 Voltage command correction unit 17 Rotation output detection unit 18 Third harmonic calculation unit 19 Third harmonic phase compensation unit 20 Voltage saturation detection Unit 31 Two-phase current command value calculation unit 32 Two-phase voltage command value calculation unit 33 Two-phase three-phase conversion unit 34 Three-phase current detection unit 35 Three-phase two-phase conversion unit 111 Three-phase two-phase conversion circuit 112 Vector conversion circuit 113 3 Harmonic generator 114 Gain 115 Multiplier 116a-116c Adder

Claims (13)

It has multiple switching element pairs consisting of upper arm switching elements arranged on the high voltage side and lower arm switching elements arranged on the low voltage side, and the DC voltage is converted to the AC voltage of the desired frequency and voltage by the operation of each switching element. And an inverter for supplying a drive voltage to a multi-phase motor, current detection means for detecting a current flowing in a stator winding of the motor, a current command value for the motor and a current detected by the current detection means Current control means for creating a voltage command value for the motor from a current error with respect to the detected value, voltage saturation detection means for detecting the degree of voltage saturation of the output voltage of the inverter, and voltage saturation detection means A third-order harmonic that compensates for the phase of the third-order harmonic of the voltage command value based on the measured voltage saturation and the value related to the rotational output of the motor. Phase compensation means, third-order harmonic calculation means for deriving the third-order harmonic from the phase of the third-order harmonic compensated by the third-order harmonic phase compensation means and the voltage command value, and the voltage command value Voltage command correction means for correcting the voltage command value by adding the third harmonic to the PWM signal for controlling the operation of each switching element of the inverter based on the correction value of the voltage command value. And a third harmonic phase compensation value so that a phase of the third harmonic is increased in proportion to a value related to the rotational output of the motor. , The third-order harmonic phase compensation value is successively increased or decreased so that the voltage saturation is minimized. The third-order harmonic phase compensation means includes a current value of the voltage saturation and a third-order harmonic phase compensation value at that time, a previous history value of the voltage saturation, and a third-order harmonic at that time so that the voltage saturation is minimized. Each of the wave phase compensation values is compared, and based on the comparison result, the third harmonic phase compensation value is increased or decreased by a predetermined change amount to set a new third harmonic phase compensation value. The electric motor drive device according to claim 1 . The motor drive device according to claim 2 , wherein the third-order harmonic phase compensation means compensates the amount of change based on a difference between a current value and a previous history value of voltage saturation. Third harmonic phase compensation value is characterized by having at least a preset upper limit value or lower limit value, the motor driving device according to any one of claims 1 to 3. The motor driving device according to any one of claims 1 to 4 , wherein the phase of the third harmonic is compensated only when a value related to the rotational output of the motor is larger than a preset reference value. Characterized in that to compensate for the phase of synchronization with the control cycle of the inverter 3 harmonic, motor driving device according to any one of claims 1-5. The phase of the third harmonic is compensated for every n cycles (n ≧ 2) of the control cycle of the inverter only when a value related to the rotational output of the motor is equal to or less than a preset reference value. 6. The electric motor drive device according to 6 . The phase of the third harmonic is compensated only when the difference between the current value and the previous history value of the electric motor is equal to or smaller than a predetermined value , and when the difference is larger than the predetermined value, the rotational speed of the electric motor is set in advance. The motor drive device according to any one of claims 1 to 7 , wherein a third-order harmonic phase compensation amount set according to the setting is set. Value when switching Yes No compensation of the phase of the third harmonic is equal to or for switching of the compensation so that the continuous, motor driving device according to claim 5, 7 or 8. The motor drive according to any one of claims 1 to 9 , further comprising speed control means for creating a current command value from a speed error between a target speed of the motor given from outside and a rotation speed of the motor. apparatus. Values for the rotational output of the motor, characterized in that it is a one of a current value of the current command value or current detection value, the motor driving device according to any one of claims 1-10. Values for the rotational output of the motor, characterized in that it is a one of the speed value of the target speed or rotational speed, the motor driving device according to any one of claims 1 to 11. The value related to the rotational output of the electric motor is an equivalent electric motor output obtained by the product of the current value of either the current command value or the detected current value and the speed value of either the target speed or the rotational speed. The electric motor drive device according to any one of claims 1 to 12 .

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