JP3387682B2 - Control method of brushless 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 rotation control technology for a sensorless DC brushless motor (hereinafter referred to as a brushless motor), and more particularly, to a method for controlling a brushless motor in which a mode transition from start-up to position detection operation is performed in the shortest time. It is about.

[0002]

2. Description of the Related Art In a brushless motor control method of this kind, generally, when a brushless motor is started, acceleration is performed by a synchronous operation, and when acceleration is performed to a position detection operation to a sufficient extent, a mode is shifted to a position detection operation, that is, an electric machine. When the position detection of the rotor is sufficiently possible due to the induced voltage generated in the child winding, the energization of the armature winding is switched based on the position detection to rotate the rotor.

Therefore, for example, the control device shown in FIG. 13 is required. This control device converts the AC power supply 1 into a predetermined DC power supply, and switches the DC power supply to supply it to the armature winding of the brushless motor (DCM) 2 and the terminal voltage of the brushless motor 2. A position detection circuit 4 for detecting the position of the rotor 2a by (induced voltage), and a control circuit (microcomputer) 5 for turning on / off a plurality of switching elements of the inverter unit 3 based on this position detection. It has and.

As the position detecting circuit 4, an analog type or a digital type has been proposed so far. In the former case, the interphase voltage (terminal voltage (induced voltage) of each phase) is integrated, the integrated signal is compared with the reference voltage, and the energization switching timing of the brushless motor is based on this comparison result. To get In the latter case, the interphase voltage is compared with a predetermined reference value (for example, 1/2 of the winding terminal voltage e) without being integrated, and the comparison result is input to a microcomputer to determine the rotor position. The detection process is executed, and the energization switching timing of the brushless motor is obtained based on this position detection.

In the former analog system, it takes time for the output of the integrator to stabilize, that is, even if position detection is possible due to the induced voltage, position detection operation is not performed unless the output of the integrator is stable. Since it is not possible to shift to the mode, the time for synchronous operation from startup becomes long.

The latter digital system does not have the drawbacks of the analog system, but has a problem due to load fluctuations, and it is difficult to perform processing for mode transition. For example, the rotor 2a and the stator 2 as shown in the schematic view of FIG.
A case of a three-phase four-pole brushless motor having the configuration of b will be described as an example. The stator 2b has a plurality of armature windings (for example, 24 slots), and the armature windings are looped and inserted into the brushless motor 2. Further, in FIG. 14, two circuits are included, the white circles indicate the first circuit (in the two circuits), and the shaded circles indicate the position detection coil cross section of the second circuit. That is, one rotation in the electrical angle corresponds to half a revolution in mechanical angle, open circles and the hatched circles in the figure indicates the phase of the non-conductive <br/> communication state, in this case, the non-conduction armature Position detection is performed using the induced voltage generated on the line W.

First, the magnetic flux change point A of the rotor 2a is shown in FIG.
When the position is set to, the energization of each armature winding is set to the magnetic field in the figure, that is, the magnetic flux change point A of the rotor 2a is rotated by 90 degrees from 0 to 6 (clockwise rotation). ). Then, it is assumed that the non-conduction of the armature winding 3,9 of the first circuit state, the armature windings 15, 21 of the second circuit and the non-conduction state.

Then, when the magnetic flux change point A of the rotor 2a passes through the position of the white circle in the meantime, the induced voltage generated in the armature winding of the white circle is just half the terminal voltage e of the winding. It will be Similarly, in the non-energized phase of the second circuit, the induced voltage becomes 1/2. The position can be detected based on the intersection (the point that is ½ of e) between the induced voltage and the predetermined reference voltage.

However, during synchronous operation of the brushless motor 2, it is not known at which position the rotating magnetic field of the stator 2b and the rotor 2a are rotating in equilibrium due to the relationship between the load and the applied voltage. For example, when the energized state shown in FIG. 14 is reached, the magnetic flux change point A of the rotor 2a should exist between 0 and 6 in the figure, but the magnetic flux change point A is more advanced than 3 in the figure. If so, the 1/2 point (position detection timing) described above cannot be detected.

As described above, when the position cannot be detected,
As a matter of course, the mode cannot be switched to the position detection operation.

On the other hand, when the brushless motor 2 is in the synchronous operation state, if it is an analog system, the integrator outputs a triangular wave delayed by about π / 2, so that an accurate point (energization switching timing) can be obtained. I can't
In this vicinity, it is possible to relatively easily switch the mode to the position detection operation.

[0012]

However, in the above brushless motor control method, when the position detection is an analog method, the synchronous operation time of the brushless motor 2 becomes long, and it takes about 10 to 20 seconds, for example. The transition will be slow.

Therefore, a digital system tends to be adopted as the position detection, and the digital system is effective from the viewpoint of efficient operation. In other words, during synchronous operation, vibration and noise are large, and when applied to an air conditioner, pipes are stressed.Therefore, it is necessary to make the synchronous operation as short as possible and make the mode transition as soon as possible. This is because the quicker the transition, the faster the cooling and heating, and the better the comfort.

Therefore, it is conceivable to adopt the above digital system even at the time of starting. However, when the digital method is adopted, 1/2 point (position detection timing) may not be detected as in the conventional example.

Further, as shown in FIG. 13, from the viewpoint of simplification of the position detection circuit 4 in the digital system, the position detection lines are reduced (shown by the chain double-dashed line in the figure), and the undetected timing of this reduced line. There is a predictive drive method in which (the energization switching timing of the armature winding) is calculated based on the phase of position detection, and the energization of the armature winding of each phase is switched. For example, using the armature winding U to detect the position of the rotor 2a,
Based on this position detection, the position detection of the rotor 2 by the other armature windings V and W is predicted to obtain the energization switching timing.

However, in this predictive driving method, since the energization switching timing of the armature winding is interpolated by calculation, special consideration is required even when the brushless motor 2 is started.

The present invention has been made in view of the above-mentioned problems, and an object thereof is a method of controlling a brushless motor, which can surely perform a mode transition from a start of the brushless motor to a position detection operation in the shortest time. To provide.

[0018]

To achieve the above object, the present invention provides a terminal voltage (induced voltage) of at least one armature winding of a plurality of armature windings of a brushless motor and a predetermined reference voltage. detecting a position from the intersection of round rotor with a control method for a brushless motor for performing a position detecting operation by switching the energization of the pre-Symbol the armature windings by the position detection on the basis of the brushless motor Upon startup ,
A first step of positioning the rotor in place ,
After positioning the rotor, energize the armature winding
To switch the rotor to obtain the position detection point.
Together with the position detection point that appears first from the positioning point
Time to and / or adjacent locations that appear afterwards
The second step of measuring the time between the detection points,
The load condition of the brushless motor from the time
Then, the predetermined coefficient according to the load condition was measured.
The position detection point of the other phase is predicted by multiplying by the time and the armature winding
Third step to obtain the energization switching timing for the wire
And the energization switching switch obtained in the third step.
Positioning operation can be performed by switching the energization of each phase with iming
Until the brushless motor is accelerated until
It is characterized by switching to the position detection operation
It

[0019]

Further, according to the present invention , the position of the rotor is determined from the intersection of the terminal voltage (induced voltage) of at least one armature winding of the plurality of armature windings of the three-phase four-pole brushless motor and the predetermined reference voltage. detecting a location, contact with the control method of a brushless motor that the position detection based on performing energization position detection operation by switching of the armature winding of the brushless motor
Then , when the brushless motor is started, the rotor is positioned at a predetermined position, and then the armature winding is mounted.
The first energization change is set to 60 degree phase advance and
The power switch is set to a 30-degree phase advance, and the first energization switch is performed.
After that, the position of the rotor rotated by 15 degrees is detected.
As a point, measure the time until the position is detected, and
After switching the energization after that, the position of the rotor is detected.
Each time, the time between each of these position detection points is measured, and
The load state of the brushless motor can be determined from the time measured.
Judgment, and use the predetermined coefficient according to the load condition to measure the time.
The position detection point of the other phase by multiplying the time
Obtain the energization switching timing for the child winding and
The rotating magnetic field with a 30-degree phase advance is generated at the power switching timing.
The brushless until the position detection operation becomes possible.
Switch to the same position detection operation when the motor accelerates
It is characterized by doing so.

[0021]

According to the above means, for example, in a three-phase four-pole pig-less motor, when the one-phase detection and the two-phase prediction are adopted, the rotor of the brushless motor is initially set to a predetermined value when the brushless motor is started. After the positioning, the energization timing of the armature winding of the brushless motor is calculated every time the rotor position is detected.

For example, in the case of a three-phase four-pole brushless motor, the first energization switching advances the rotating magnetic field by 60 degrees,
The subsequent energization switching advances the rotating magnetic field by 30 degrees.

When the stator (armature winding side) and the rotor of the brushless motor are in the state shown in FIG. 4, for example, the magnetic flux change point A of the rotor after the first energization switching is P
When it reaches 1 (see FIG. 7), an induced voltage ½ of the terminal voltage e is generated in the armature winding.

The energization is switched at the point e / 2 (position detection; 1/2 point), and the time up to the 1/2 point is measured, and the energization of the other phase is switched based on this measured time. Timing is predicted.

After the energization is switched, the rotating magnetic field is advanced by 30 degrees, and when an induced voltage of 1/2 of the terminal voltage e is generated in the winding of the armature, the energization is performed at this 1/2 point. Is switched, or the time to the point of e / 2 (position detection; 1/2 point) is measured,
The energization switching timing of the phase can be obtained based on this time count time. Note that the energization switching timing of the other phase is predicted based on the time counted. Also,
For example, the load state and the like are determined based on the time counted, and a coefficient corresponding to the result of this determination is applied to the time measured to obtain the relevant energization switching timing and the predicted energization switching timing.

Thereafter, the same processing is performed, and when the brushless motor is accelerated to the extent that the position detection operation can be performed, the brushless motor is switched to the position detection operation.

As described above, since the position of the rotor is already detected after the brushless motor is started, it is possible to shift the mode to the position detecting operation in the shortest time.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an induced voltage is generated in an armature winding of a brushless motor of a sensorless DC brushless motor (hereinafter referred to as a brushless motor) in the same manner as during a position detecting operation of the brushless motor. This is the focus.

Then, in the control method applying the predictive driving method, the rotor is positioned when the brushless motor is started, and the subsequent position is detected (e / 2 of the induced voltage).
(E; applied voltage (terminal voltage)) 1/2 point)
Based on the above, the energization switching of the relevant phase and the energization switching timing of the other phase are predicted, or the load state (the magnitude of the load) is determined by measuring the time for each 1/2 point, and the result of this determination is In addition, the energization of the relevant phase is switched, the energization switching timing of the other phase is predicted, and the brushless motor is accelerated in the shortest time to the extent that position detection operation is possible.

Therefore, the control device to which the brushless motor control method of the present invention is applied has the configuration shown in FIG. In the figure, the same parts as those in FIG. 13 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 1, this control device is provided with an induced voltage generated in one armature winding U of the armature windings U, V, W of the brushless motor 2 and a predetermined reference voltage (e / 2) a.
And a position detection circuit 11 for outputting a signal of the comparison result (position detection) to the control circuit (microcomputer) 10.

Further, the control circuit 10, in addition to the functions of the control circuit 5 shown in FIG. 1 3, the function of positioning the rotor upon start of the brushless motor, a position detection signal from the positioning after the position detection circuit 4 The function to judge the load condition by measuring the time for each position detection based on the above, and the U, V, W phases based on the position detection (1/2 point) in order considering the judgment result. 2 has a function of switching the energization of the armature winding, and a function of performing a mode transition from startup to position detection operation by switching the energization.

Next, the operation of the above control device will be described with reference to the time charts of FIGS. 2 and 3 and FIGS. 4, 7, 10 and 11.
And the schematic diagram of the brushless motor of FIG. 12 and the schematic diagrams of the armature windings of FIGS. 5, 6, 8 and 9. 2 (b), (c) and FIG.
(B) and (c) are virtual terminal voltages of the armature windings V and W, respectively.

First, the control circuit 10 positions (locks) the rotor 2a so that the rotor 2a and the stator 2b of the brushless motor 2 have the relationship shown in FIG. In addition, when the brushless motor 2 is a three-phase four-pole motor, the position of the rotor 2a can be changed by switching the energization twice regardless of the position of the rotor 2a.
The state becomes as shown in. For example, as shown by the arrows in FIGS. 5 and 6, the motor current is passed from the armature winding V side to the armature winding W side, and then the motor current is passed from the armature winding V side to the armature winding U side. Just run it to the side.

After the positioning is completed by the above-mentioned two energization switching (after the magnetic flux change point A of the rotor 2a reaches the position shown in FIG. 4), the control circuit 10 causes the magnetic field of the stator 2b to be in the state shown in FIG. Switch the energization of the armature winding so that When the motor current is passed from the armature winding W side to the armature winding V side as shown in FIG.
Then, the stator 2b is advanced by 60 degrees.

In this case, as is apparent from FIG. 7, one energization of the armature winding is skipped unlike the usual energization switching. Normally (when the phase is advanced by 30 degrees), the motor current is passed from the armature winding W side to the armature winding U side as shown in FIG. Flow from the armature winding W side to the armature winding V side (Fig. 8
Shown in). That is, by advancing the magnetic field of the stator 2b by 60 degrees (clockwise direction shown in FIG. 7), the rotor 2a
When the magnetic flux change point A of 15 is advanced by 15 degrees (reached P1), the rotor 2a is rotated by the armature winding U that is in the non-conduction phase.
This is because the position of can be reliably detected.

At this time, the position detection coil is the armature winding U.
Therefore, the magnetic flux change point A of the rotor 2a is P0 at the mechanical angle.
When reaching P1 which is advanced by 15 degrees (shown in FIG. 7), an induced voltage (rise induced voltage) that is ½ of the terminal voltage e is generated in the armature winding U (FIG. 2 ( a)
Shown in).

The position detection circuit 4 compares the induced voltage generated in the armature winding U with a predetermined reference voltage (1/2 of the terminal voltage e) a, and the result of this comparison (the induced voltage and the predetermined reference voltage a Intersection point PU1; position detection point) is output to the control circuit 10.

Then, the control circuit 10 switches the energization of the U-phase at the intersection of the comparison results (shown in FIG. 2A), and measures the time to the intersection to measure the other phases (V-phase and W-phase). ) Energization switching timing is calculated. The V-phase and W-phase energization is switched at this calculated energization switching timing (shown in FIGS. 2B and 2C).

The method of starting the brushless motor 2 will be described in detail, and the process up to the mode transition to the position detection operation will be described with reference to FIG. First, the control circuit 10 measures the time TU1 (shown in FIG. 3 (a)) from the switching of energization to the state shown in FIG. 7 until the intersection point (position detection point) PU1 of the comparison result this time, and this time measurement time TU1 Based on, the energization switching timing of the U phase is obtained, and the energization switching timing of the V phase and the W phase is calculated.

Further, the load state and the applied voltage are judged based on the above-mentioned clock time TU1, and the coefficient corresponding to the judgment result is read out from the memory, and the read coefficient is multiplied by the clock time TU1. The energization switching timing (time) t1 may be calculated (indicated by broken line arrows in FIGS. 3A and 3C).

Since the control circuit 10 adopts the predictive driving method, the position detection timing by the other phase is obtained by the time count TU1 and the energization switching timing (time t1, t2, t3) is changed by changing the coefficient. It is calculated (indicated by broken line arrows in FIGS. 3A to 3C).

When the calculated time t1 is reached, the stator 2b
In order to cause the phase shift of 30 degrees by 30 degrees, energization is switched so that the armature winding of the stator 2b has the magnetic field shown in FIG. That is, when the magnetic flux change point A of the rotor 2a reaches P2, the prediction coefficient is determined to switch the energization.

Subsequently, at the above-mentioned calculation time t2, the energization is switched so that the armature winding of the stator 2b has the magnetic field shown in FIG. That is, when the magnetic flux change point A of the rotor 2a reaches P3, the prediction coefficient is determined to switch the energization. Then, at the above-mentioned calculation time t3, energization is switched so that the armature winding of the stator 2b has the magnetic field shown in FIG. As a result, the magnetic flux change point A of the rotor 2a reaches from P3 to P4. Then, the armature winding U corresponds to the position detection coil, and the induced voltage (falling voltage) is generated again in the armature winding U (shown in FIG. 3A).

The position detection circuit 4 compares the induced voltage generated in the armature winding U with a predetermined reference voltage (1/2 of the terminal voltage e) a, and the result of this comparison (the induced voltage and the predetermined reference voltage). The intersection point PU2; position detection) is output to the control circuit 10.

On the other hand, the control circuit 10 controls the time T from the intersection PU1 of the previous comparison result to the intersection PU2 of the comparison result this time.
U2 (shown in FIG. 3 (a)) is clocked, and this clocked time TU
The load state and the applied voltage are determined based on 2, and the coefficient corresponding to this determination result is read from the internal memory. This read coefficient is multiplied by the measured time TU2, and the next energization switching timing (time) t4 , t5,
t6 is calculated (indicated by broken line arrows in FIGS. 3A and 3C).

[0047]

In the same manner as described above, the energization of the armature winding of the stator 2b is switched, and the induced voltage of the armature winding U and the predetermined reference voltage a from the intersection of the previous armature winding U and the predetermined reference voltage a. The time TU3 up to the intersection with and is measured, the load state and the applied voltage are determined based on the measured time TU3, and the coefficient corresponding to this determination result is read from the internal memory. This read coefficient is used as the measured time TU3
The next energization switching timing (time) t7, t
Calculate 8 and t9.

By switching the energization at the above calculation timing and repeating the same processing, the rotor 2a can be accelerated corresponding to the applied voltage of the brushless motor 2.

From the time t1 to t4, the energization switching timing is obtained in consideration of the load state and the like, so that the torque can be efficiently generated. However, since the rotor 2a is accelerating in that section, an induced voltage may be generated in the armature winding U before the time t3, that is, t3 is PU2.
It may exceed (1/2 point).

Therefore, it is preferable that the energization switching be performed early between the times t1 and t4 by the activation method shown in FIG. That is, even if the energization is switched immediately after the first 1/2 point is detected from the start of rotation, the reverse torque is not applied.

In this way, the rotor 2 is rotated until the induced voltage generated in the armature winding becomes sufficient for the position detection operation.
When a is accelerated, the mode shifts to the position detection operation.
For example, at the point of PU3 shown in FIG.
If the mode is changed to the position detection operation, the measured time TU
The modes can be easily switched by simply passing the times t7, t8, and t9 calculated based on 3 as the initial values of the position detection operation.

As described above, when the brushless motor 2 is started and rotated by the digital drive method, the rotor 2a is set at a predetermined position and the subsequent position detection (1/2 of the induced voltage) is performed.
The energization of the armature winding is switched based on e (terminal point) 1/2 point). Moreover, the first energization switching timing after positioning is skipped by one (60-degree phase advance energization), the time to the first 1/2 point is timed to determine the load status, etc. Then, the energization switching time of the armature winding is calculated.

Further, thereafter, the normal energization switching timing (energization of 30-degree phase advance) is interpolated and calculated based on the timed time between the U-phase position detections, and the load state and the like is judged from the timed time. The energization switching time of the armature winding is calculated in consideration of this determination result.

When the induced voltage is generated to a sufficient extent for the position detecting operation by switching the energization at the calculated time, the mode is shifted to the position detecting operation.

Therefore, the mode transition of the position detection operation can be smoothly performed in the shortest time from the start of the brushless motor 2,
Vibration and noise peculiar to the conventional synchronous operation can be suppressed, and when used in a compressor of an air conditioner, for example, stress on piping for refrigerant circulation can be suppressed.

In the above embodiment, the position detection is performed for one phase, but two-phase position detection may be used. Further, the coefficient according to the load state or the like may be calculated each time.

[0058]

As described above, according to the brushless motor control method of the present invention, the digital method and the predictive drive method are employed, the rotor is positioned, and the first energization switching is performed. Position detection (1 / the induced voltage
1 point (or 2 phase) 1/2 point when switching the energization of the armature winding based on 2e (terminal voltage) and switching the energization and subsequent energization Since the load state etc. is measured by measuring the time between them, the energization is switched considering the result of this judgment, and it is switched to the same position detection operation when the brushless motor is accelerated to the extent that position detection operation is possible. It is possible to reliably perform the mode transition from the start of the brushless motor to the position detection operation in the shortest time without depending on load fluctuations, that is, it is possible to suppress the vibration and noise peculiar to the synchronous operation, and the compressor of the air conditioner. When used for the above, there is a useful effect that the stress on the piping for circulating the refrigerant can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a control device to which an embodiment of the present invention is applied and to which a brushless motor control method is applied.

FIG. 2 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 3 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 4 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

5 is a schematic diagram of an armature winding for explaining the operation of the control device shown in FIG.

6 is a schematic diagram of an armature winding for explaining the operation of the control device shown in FIG.

FIG. 7 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

FIG. 8 is a schematic diagram of an armature winding for explaining the operation of the control device shown in FIG.

9 is a schematic diagram of an armature winding for explaining the operation of the control device shown in FIG.

FIG. 10 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

11 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

12 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

FIG. 13 is a schematic block diagram of a conventional brushless motor control device.

14 is a schematic diagram of a brushless motor for explaining the operation of the control device shown in FIG.

[Explanation of symbols]

1 AC power supply 2 Brushless motor (DC brushless motor) 2a rotor 2b stator 3 Inverter section 4,11 Position detection circuit 5, 10 Control circuit (microcomputer) A Magnetic flux change point (of rotor 2a) U, V, W armature winding (for brushless motor 2)

Claims (2)

(57) [Claims] 1. A detecting at least one position from the intersection times rotor of the terminal voltage of the armature winding and (induced voltage) with a predetermined reference voltage among a plurality of armature windings of the brushless motor, the position a method of controlling a brushless motor for performing a position detecting operation by switching the energization of the pre-Symbol the armature winding based on the detection, upon activation of the brushless motor, a first step of positioning the rotor in a predetermined position , after positioning the rotor, the energization of the armature winding
To switch the rotor to obtain the position detection point.
Together with the position detection point that appears first from the positioning point
Time to and / or adjacent locations that appear afterwards
The second step of measuring the time between detection points, and the load state of the brushless motor from the measured time.
Condition, and a predetermined coefficient according to the load condition is calculated.
The position detection points of other phases are predicted by multiplying the time
Third for obtaining the energization switching timing for the armature winding
At the energization switching timing obtained in the third step.
Switch the energization of each phase until position detection operation is possible
The same position detection operation is performed when the brushless motor is accelerated.
A method of controlling a brushless motor, which is characterized by switching to. Wherein at least one position the intersection from the rotor of the terminal voltage of the armature winding and (induced voltage) with a predetermined reference voltage among a plurality of armature windings of the brushless motor of three-phase four-pole
Detects, in the control method for a brushless motor for performing a position detecting operation by switching the energization of the pre-Symbol the armature windings by the position detection based on, upon activation of the brushless motor, said rotor in a predetermined position After positioning , first to the armature winding
The energization switching of is set as the phase advance by 60 degrees, and the energization is cut off thereafter.
The phase is changed by 30 degrees, and after the first energization switching,
The position detection point is the 15 ° rotational position of the rotor.
Time until the position is detected, and after that,
After switching the energization, each time the rotor position is detected.
The time between each of these position detection points, and
The determined load state of the brushless motor from the time
Then, the predetermined coefficient according to the load condition was measured.
The position detection point of the other phase is predicted by multiplying by the time and the armature winding
Obtain the timing for switching the power to the line and turn off the power.
The rotating magnetic field with the 30-degree phase advance is generated at the replacement timing.
The brushless model until the position detection operation becomes possible.
A method for controlling a brushless motor, characterized in that when the motor accelerates, the operation is switched to the same position detection operation.