JP3397013B2 - Control device for synchronous motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor control device using a permanent magnet for a rotor, and particularly when a difference in position detection value occurs due to displacement of the permanent magnet, the difference is detected and automatically corrected. The present invention relates to a control device for a synchronous motor.

[0002]

2. Description of the Related Art Vector control is used to control a synchronous motor. In order to perform vector control of the synchronous motor, first, the current flowing through the armature of the synchronous motor and the voltage applied to the armature are measured, and the measured value is converted into a rotating coordinate dq coordinate system that rotates in synchronization with the rotor. After the conversion, the current is controlled on the dq coordinate system after the conversion to generate the control operation signal. Then, this control operation signal is converted back into AC coordinates to control the synchronous motor. In these coordinate conversions, the position information of the magnetic poles of the rotor at that moment is necessary. The position information of this magnetic pole is usually obtained from the rotation angle of the rotor by providing an angle sensor on the rotor.

[0003]

However, in the conventional vector control as described above, for example, in the case of a rotor using a permanent magnet for the field, the positional relationship between the rotor and the permanent magnet must be determined. If a deviation occurs, even if the angle sensor accurately detects the rotation angle of the rotor, the position of the magnetic pole that the vector control recognizes based on the angle sensor differs from the actual position. When converting the current and voltage detected in the dq coordinate system that rotates with the rotor, the coordinate conversion is not performed normally, and as a result, accurate current control cannot be performed. There is a problem that the permanent magnet is permanently demagnetized, such as a decrease in efficiency and the generation of overcurrent.

On the other hand, there is so-called sensorless control in which a magnetic pole is estimated by calculation without using an angle sensor and coordinate conversion is performed using this estimated position. However, in sensorless control, it is necessary to make the update cycle of the angle estimated to obtain the momentary angle information equal to the current control cycle,
Therefore, if the update cycle is not short in the high rotation range, the angle of rotation within that time becomes large and the controllability deteriorates. Further, in order to solve this, in order to speed up the cycle so that the calculation can be performed faster, it is necessary to improve the performance of the MPU or the like that performs the calculation, and there is a problem that the cost increases.

When the sensorless control is actually used, an error is likely to be included in the PWM waveform of the voltage in the low speed region due to the small duty ratio, and further, the voltage information cannot be obtained at the time of stop, so that the magnetic pole position can be estimated. There is a problem that it is difficult. In view of the above problems, the present invention provides a vector control device capable of accurately detecting the position of a magnetic pole and performing accurate coordinate conversion even if a positional relationship between a rotor and a permanent magnet is deviated. Is intended.

[0006]

Therefore, the invention according to claim 1 is, in a synchronous motor using a permanent magnet for a rotor, an inverter for converting direct current power into alternating current to supply power to the synchronous motor. A current detecting means for detecting a current flowing from the inverter to the armature coil of the synchronous motor, a voltage detecting means for detecting a voltage applied to the armature coil, and a position for detecting a rotational position of a rotor of the synchronous motor. Detecting means, magnetic pole position estimating means for estimating and calculating the magnetic pole position of the rotor based on the detected current and detected voltage, the detected rotational position of the rotor and the magnetic pole position estimating means. Error calculating means for calculating an error from the magnetic pole position, and the actual position of the permanent magnet provided on the rotor and the detected rotational position of the rotor from the calculated error. A deviation detecting means for detecting a deviation,
And a correction unit that corrects the detected deviation. According to a second aspect of the present invention, in the configuration of the first aspect, there is provided speed detection means for detecting a rotation speed of the rotor, and the correction means corrects the deviation according to the rotation speed of the rotor. did.

[0007]

According to the present invention, the position of the rotor is detected by the position detecting means, and the detected value is compared with the magnetic pole position of the permanent magnet estimated by the magnetic pole position estimating means to determine the rotational position of the rotor. Since the deviation between the magnetic pole position of the permanent magnet and the magnetic pole position of the permanent magnet is detected and further corrected, it is not necessary to make the position update cycle in the magnetic pole position estimation means equal to the current control cycle.
The calculation load of the MPU that performs the calculation is reduced. In addition, the synchronous motor can be controlled even at low speed or when stopped. When the positional deviation is corrected according to the rotation speed, the corresponding correction can be performed in the rotation range where the estimated reliability is different.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples. FIG. 1 shows an embodiment of the present invention. First, the structure will be described. The synchronous motor 3 is a synchronous motor that uses a two-pole permanent magnet for the rotor. DC power from the battery 1 is converted into three-phase AC power by an inverter 2 composed of a switching element such as an IGBT, and then supplied to the synchronous motor 3. Rotation angle θse of the rotor of the synchronous motor 3
n is detected by the angle sensor 4.

The outputs of the U and V phases of the inverter 2 are detected by the current sensors 5 and 6 for the alternating currents iu and iv flowing through the armature coil and by the voltage sensors 12 and 13 for the voltages vu and vv applied to the armature. To be done. As the angle sensor 4, a resolver, a rotary encoder using an optical type or a direct resistance element, or the like is used. The controller 200 performs vector control on the rotation coordinates based on the rotation speed ω obtained from the torque command value T * and the rotation angle θsen of the rotor, and controls the current flowing through the armature coil to follow the control command. To do.

The rotating coordinate is a dq coordinate system which rotates in synchronization with the rotor as shown in FIG. 2 and defines a d-axis in the magnetic flux direction and a q-axis in the direction perpendicular thereto. Therefore, when the u and v phases of the three-phase alternating current are used to convert to the dq coordinate system, it is according to the equation (1). Further, the conversion formula from the dq coordinate system to the three-phase alternating current becomes the formula (2).

[Equation 1]

[Equation 2]

The controller 200 will be described below. In the current command generator 8, the relationship between the torque command value T * and the q-axis current iq * and the relationship between the rotation speed ω of the rotor and the d-axis current id * are set. Outputs the current commands id * and iq * on the dq coordinate system to the current controller 10. The 3/2 converter 9 stores the conversion formula from the u and v phase signals shown in Formula 1 to the d and q axis signals of the dq coordinate system, and the current detected by the current sensors 5 and 6 is stored. iu and iv are currents i on the dq coordinate system
The coordinates are converted into d and iq and output to the current regulator 10.

The current controller 10 performs proportional or integral control based on the current commands id *, iq * from the current command generator 8 and the currents id, iq converted by the 3/2 converter 9. The control operation command obtained by
3 to the converter 11. The 2/3 converter 11 has the formula 2
The three-phase alternating current u, v,
A conversion formula for converting into a w-phase signal is stored, and the control operation command on the dq coordinates is converted into a three-phase AC control command signal of u, v, and w here and output to the inverter 2.

Next, the position detection of the magnetic pole used for the coordinate conversion will be described. For a synchronous motor whose rotor is rotating at an electrical angular velocity ω as shown in FIG. 2, the current-voltage equation is represented by the dq coordinate system as shown in equation (3).

[Equation 3] Here, Vd and Vq are d-axis and q-axis voltages, id and iq are d
Axis, q axis current, Rd, Rq are d axis, q axis armature resistance, L
d and Lq are d-axis and q-axis inductances, and ψf is a field interlinkage magnetic flux. The voltages Vd, Vq on the dq coordinate system of the above equation,
The currents id and iq can be obtained by coordinate-converting the armature voltage / current of each phase measured by the voltage sensors 12 and 13 and the current sensors 5 and 6 by the equation (1). Therefore, the magnetic pole position can be estimated by solving θ from the voltage-current equation of the equation (3).

The magnetic pole position estimation calculator 15 stores the equivalent model of the synchronous motor represented by the equation (3) and the coordinate conversion equation represented by the equation (1), and the detected armature current i
u, iv, and voltages Vu, Vd are first subjected to coordinate conversion by equation (1) to become id, iq, Vd, Vq on dq coordinates. Equation (3) is applied to the value, and the magnetic pole position θ′cal is estimated through the integral calculation.

In the angle corrector 14, the detected value θsen from the angle sensor 4 is calculated by the magnetic pole position estimating calculator 15 as described above.
Correction is performed according to the magnetic pole estimation calculation result by. To this end, a time correction amount obtained by multiplying the estimated magnetic pole position θ′cal by the calculation time Δt and the angular velocity ω is first added to calculate the estimated magnetic pole angle θcal. The correction is divided into three regions according to the rotation speed, and the correction is set not to perform the correction in the low rotation speed range where the estimation calculation is likely to include an error, but to perform the correction in the rotation speed range above a certain level.

Next, the above correction will be described with reference to the flowchart of FIG. First, in step 100, the time correction amount (ω × Δt) is added to the magnetic pole position θ′cal from the magnetic pole position estimation calculator 15 to calculate the estimated magnetic pole position θcal. In step 101, it is determined whether the rotation speed ω is smaller than a predetermined rotation speed ω1. In the low rotation speed region below the rotation speed ω1, in step 102, the change amount δ ′ of the error amount δ is set to 0, and it is determined so that the previously determined error amount δ is not changed.

In the rotation range above the rotation speed ω1, step 1
At 03, it is determined whether the rotational speed is higher than a predetermined rotational speed ω2. If the rotational speed is greater than ω2, the estimated position θcal of the magnetic pole is subtracted from the calculation angle θ to obtain the conversion amount of the error amount. If it is smaller than the rotation speed ω2, in step 104, the proportional coefficient k is changed so as to linearly change the error amount δ ′ between the rotation range where correction is not performed (less than ω1) and the rotation range where correction is performed (ω2 or more). To introduce. In this case, the proportional coefficient k can be expressed as follows. k (ω) = (ω−ω1) / (ω2-ω1) (4)

At step 106, the obtained error amount δ'is added to the currently used error amount δ to obtain a new error amount δ. In step 107, using this error amount δ, in addition to the detection value θsen of the angle sensor 4, the calculation angle θ used for control such as the next coordinate conversion is created.

FIG. 4 shows the start timing of the current control routine in the controller 200. This current control routine includes coordinate conversion and is intended to realize current control according to a command value. In this routine,
The u-phase and v-phase currents of the three-phase currents are fetched, and the angle θsen from the angle sensor 4 is set to the angle corrector 14 as described above.
The three-phase current is converted into a value on the dq coordinate system that rotates together with the permanent magnets by the calculation angle θ added with the deviation amount δ determined in step S1, and the deviation from the d-axis and q-axis current command values is calculated. Create each voltage command value. The created voltage command value is inversely converted into a three-phase alternating current and becomes a switching command to the inverter.

The calculation angle θ is the information θ from the angle sensor 4.
sen and the sum of the error amount δ between this θsen and the estimated position θcal. The angle θ for calculation detects the current and voltage of the armature at the timing of t1 as shown in FIG. 4 and estimates the magnetic pole position at that timing. However, since there is a time lag until this calculation result is obtained, the time correction is performed. The amount is obtained by multiplying the calculation time Δt by the angular velocity ω. Therefore, the required estimated position θcal is obtained by adding the magnetic pole position θ′cal to the correction amount.

The present embodiment is constructed as described above, and the armature current, while operating by the detection of the angle sensor 4,
Since the magnetic pole position of the permanent magnet is estimated from the voltage, the positional deviation between the permanent magnet and the rotor is detected from this estimation result, and the deviation is corrected according to the expected degree of calculation error. You can continue driving even if you move away from your child.

Since the calculation angle θ is the sum of the information θsen from the angle sensor 4 which is updated as the rotor rotates and the error amount δ which is updated in a cycle longer than the current control cycle, the magnetic pole position is estimated. Therefore, the angle sensor can be corrected without requiring the MPU to have much calculation load. Therefore, the effect that the operation can be continued even if the permanent magnet is displaced from the rotor is obtained.

Then, the obtained error amount δ is stored in a rewritable storage ROM that does not require a power supply for storage, so that the error amount δ is held even after the controller is powered off. It is also possible to operate in a corrected state immediately after the start of operation.

Further, in this way, the error amount δ is stored in the ROM or the like.
It is possible to eliminate the need for fine adjustment at the time of mounting the angle sensor at the manufacturing stage by configuring so as to be able to store. That is, rather than performing the fine adjustment of the attachment of the angle sensor mechanically, it can be realized by detecting the adjustment amount as an error amount during operation of the controller and storing it.

The proportional coefficient k for determining the change amount δ'of the correction amount may not be linear but may be nonlinear depending on the degree of the estimated calculation error. It is also possible to avoid the influence of, for example, a small estimation calculation error by setting a minimum value for the change amount δ ′ of the error amount δ and ignoring it if it is extremely small δ ′.

[0026]

As described above, according to the present invention, the position of the rotor is detected by the position detecting means, and the detected value is compared with the magnetic pole position of the permanent magnet estimated by the magnetic pole position estimating means. Since the deviation between the rotational position of the rotor and the magnetic pole position of the permanent magnet is detected and further corrected, it is necessary to make the position update cycle in the magnetic pole position estimation means equal to the current control cycle. Therefore, the calculation load of the MPU that performs the calculation is reduced. In addition, the synchronous motor can be controlled even at low speed or when stopped. As a result, cost reduction is realized and the application range of the control device is expanded. Then, if the positional deviation is corrected according to the rotation speed, the corresponding correction can be performed in the rotation range where the estimated reliability is different, and stable coordinate conversion can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a dq coordinate system.

FIG. 3 is a flowchart for calculating a correction amount.

FIG. 4 is a diagram showing a control routine.

[Explanation of symbols]

1 battery 2 inverter 3 synchronous motor 4 angle sensor 5, 6 Current sensor 7 differentiator 8 Current command generator 9 3/2 converter 10 Current regulator 11 2/3 converter 12, 13 Voltage sensor 14 Angle corrector 15 Magnetic pole position estimation calculator 200 controller

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-335277 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7 / 628 H02P 21/00 H02P 6/00-6/24

Claims (2)

(57) [Claims] 1. A synchronous motor using a permanent magnet as a rotor, comprising: an inverter for converting direct current power into alternating current to supply power to the synchronous motor; and a current flowing from the inverter to an armature coil of the synchronous motor. Current detecting means for detecting, voltage detecting means for detecting the voltage applied to the armature coil, position detecting means for detecting the rotational position of the rotor of the synchronous motor, and the detected current and detected voltage. Magnetic pole position estimating means for estimating and calculating the magnetic pole position of the rotor based on the above; error calculating means for calculating an error between the detected rotational position of the rotor and the magnetic pole position estimated by the magnetic pole position estimating means; Deviation detecting means for detecting a deviation between the actual position of the permanent magnet provided on the rotor and the detected rotational position of the rotor from the calculated error; A controller for a synchronous motor, comprising: a correction unit that corrects a deviation. 2. A synchronous motor using a permanent magnet as a rotor, comprising: an inverter for converting direct current power into alternating current to supply power to the synchronous motor; and an electric current flowing from the inverter to an armature coil of the synchronous motor. Current detecting means for detecting, voltage detecting means for detecting a voltage applied to the armature coil, position detecting means for detecting the position of the rotor of the synchronous motor, and based on the detected current and detected voltage Magnetic pole position estimating means for estimating and calculating the magnetic pole position of the rotor; error calculating means for calculating an error between the detected rotational position of the rotor and the magnetic pole position estimated by the magnetic pole position estimating means; Deviation detecting means for detecting deviation between the actual position of the permanent magnet provided on the rotor and the detected rotational position of the rotor from the error,
Comprising: a correction unit that corrects the detected deviation, and a speed detection unit that detects the rotation speed of the rotor, wherein the correction unit corrects the deviation according to the rotation speed of the rotor. Characteristic synchronous motor control device.