JP2001359294A - Method for controlling brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control load pulsation and change of load pulsation due to variation of rotation, and also to widen the operation range of torque control. SOLUTION: An application voltage of a brushless motor is compensated, using the basic compensation voltage pattern for controlling load pulsation of the brushless motor, and meanwhile, only one rotation of the brushless motor is divided equally into m sections of section 0,..., section m-1 in terms of a mechanical angle, the load pulsation of each section is detected in the section times t10,..., t1m-1, the section time interval of L rotations is detected, average values α0,..., αm-1 for section time intervals are calculated for L rotations by each section, an average value β for the average values α0, αm-1 for each section time interval is calculated. The difference between the average values, α0,..., αm-1 for each section time and the average value β is calculated, so as to adjust the basic compensation voltage pattern to make the average values α0,..., αm-1 for each section time approximate closer to the average value β. Thereby, a new basic compensation voltage pattern can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control technology for a brushless motor used for a motor such as an air conditioner (compressor), and more particularly, to suppressing load pulsation during one rotation and reducing vibration and noise. The present invention relates to a method for controlling a brushless motor.

[0002]

2. Description of the Related Art As a control method of a brushless motor,
Since the torque and the armature winding current are in a proportional relationship,
There is a method using a method of detecting a current of an armature winding and feeding back the current to perform torque control. In this torque control, real-time control can be performed, but a current sensor for detecting the current of the armature winding is required.

On the other hand, there is a control method in which torque control is performed for each time (section time) of a position detection interval based on a rotor position detection signal. In this case, the voltage pattern may be empirically determined in advance according to the use state of the brushless motor, and this voltage pattern may be added to the applied voltage for each section time, so that components such as a current sensor are not required.

A control device for controlling the brushless motor includes, for example, as shown in FIG.
/ DC conversion circuit 2 converts the DC power supply into a predetermined DC power supply.
a, Wa, X, Y and Z are switched and supplied to the armature windings U, V and W of the brushless motor (DCM) 4.

The position detecting circuit 5 compares an induced voltage waveform (induced voltage waveform generated in a non-energized phase) included in the terminal voltage of the armature windings U, V, W of the brushless motor 4 with a basic value. To detect a half point of the induced voltage waveform.
A position detection signal including the / 2 point is output to a control circuit (mainly composed of a microcomputer) 6.

[0006] The control circuit 6 detects the induced voltage 1 by the edge (rising edge, falling edge) of the input position detection signal.
/ 2 points (rotor position detection points) are detected, and a position detection interval is calculated based on the current position detection time and the previous position detection time.

For example, a time corresponding to a value equal to or less than 30 degrees of the electrical angle is calculated from the past position detection intervals, and the calculated time is added to the current position detection time to estimate the next energization switching time. When the estimated time comes, a predetermined drive signal is output to the inverter circuit 3 via the drive circuit 7 to switch the energization, and the energization of the armature windings U, V, W is appropriately switched.

When the load pulsates, the speed of the brushless motor 4 fluctuates during one rotation, and as a result, the brushless motor 4 generates mechanical vibration and generates noise. For example, in a compressor or the like, there is a periodic rotation fluctuation during one rotation due to the refrigerant discharge and compression cycles, and the rotation fluctuation includes a position detection error and a rotation unevenness due to torque ripple and the like. When such rotation fluctuation is considered as load pulsation, the energization switching is deviated from the optimal timing due to the load pulsation, and the above-described vibration and noise are generated.

Therefore, as described above, a voltage pattern obtained in advance according to the load pulsation is stored in the internal memory, each section is detected by the position detection signal, and the voltage pattern is applied for each section. Correct the voltage. The voltage pattern is, for example, an increase / decrease amount of an ON width of a PWM on / off ratio when the brushless motor 4 is controlled by a PWM control method. Therefore, since the applied voltage of the brushless motor 4 increases and decreases in accordance with the pulsation of the load, the pulsation of the load is canceled, and the vibration and noise of the brushless motor 4 can be suppressed.

[0010]

However, in the above-described brushless motor control method, since the voltage pattern for canceling the load pulsation is fixed to one, a change in load condition and the like and a speed fluctuation (speed change) are required. ), It is difficult to determine one optimal voltage pattern. Further, torque control for correcting the applied voltage based on the voltage pattern becomes positive feedback, causing vibration, and it is difficult to suppress vibration and noise.

This is because the pulsation shape of the load changes due to changes in load conditions and the like and speed fluctuations, so that the rotation of the brushless motor 4 fluctuates. This rotation fluctuation not only adds to the load pulsation but also increases the load pulsation. This is because the pulsation is not one shape. Therefore, it is sufficient to prepare a plurality of voltage patterns in response to the fluctuation of the load pulsation. However, the voltage patterns are enormous, and the resulting memory capacity is enormous, which is not very realistic.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to appropriately suppress pulsation even when load pulsation changes and to enable stable rotation control by suppressing rotation fluctuation to achieve vibration control. And noise, and P
An object of the present invention is to provide a brushless motor control method capable of expanding an operation range of torque control at the time of WM control.

[0013]

In order to achieve the above-mentioned object, the present invention provides a brushless motor in which a DC power supply is set to an input power supply voltage of an inverter means, and a switching means of the inverter means is turned on and off in a predetermined manner. The brushless motor is detected by detecting the position of the rotor of the brushless motor, controlling the inverter means based on the detected position, and switching the energization of the armature winding of the brushless motor. In the method of controlling a brushless motor for controlling the rotation of the brushless motor, the brushless motor has one basic correction voltage pattern for suppressing load pulsation of the brushless motor, and the applied voltage of the brushless motor is corrected using the basic correction voltage pattern. One rotation of the brushless motor is equally divided into multiple sections by mechanical angle, and load pulsation in each section is And obtains the section time of each section for a plurality of rotations, and adjusts the basic correction voltage pattern so that the section time average value approaches the average value of the section time for the same rotation for each section. The applied voltage of the brushless motor is corrected by the adjusted basic correction voltage pattern to suppress the load pulsation, and to suppress the fluctuation of the load pulsation due to the rotation fluctuation of the brushless motor, while controlling the brushless motor by a PWM control method. The duty of the PWM waveform is 1
When the voltage has reached 00%, the DC voltage of the input power supply voltage of the inverter means is stepped up by a predetermined value, and its duty is made smaller than 100% or its duty is set to 1
It is characterized in that the torque control can be continued by maintaining the torque control value at 00%.

A method for controlling a brushless motor according to the present invention comprises:
In order to suppress the load pulsation of the brushless motor, one rotation of the brushless motor is equally divided into a plurality of sections by a mechanical angle, and one basic correction voltage pattern for correcting the applied voltage of the brushless motor for each section is defined as While correcting the applied voltage of the brushless motor using the basic correction voltage pattern, while measuring the time of each section, calculating the section time average value for a plurality of rotations for each section, The average value is calculated by adding the section time average value and dividing the divided value by the number of divisions, and adjusting the basic correction voltage pattern according to the difference between the average value and the section time average value. The applied voltage of the brushless motor is corrected by the basic correction voltage pattern to suppress the load pulsation of the brushless motor, and to suppress the fluctuation of the load pulsation. When the brushless motor is controlled by the PWM control method, when the duty of the PWM waveform has reached 100%, the DC voltage of the input power supply voltage of the inverter means is increased by a predetermined value, and the duty is reduced. It is characterized in that the torque control can be continued by keeping the duty smaller than 100% or maintaining the duty at 100%.

The basic correction voltage pattern is preferably stored in advance as an initial value and updated each time the adjustment is performed. Thereby, in the torque control for suppressing the load pulsation, the convergence of the control is performed in a short time, and
There is no hunting in the torque control.

The amount by which the basic correction voltage pattern is adjusted is the difference between the average value of each section and the average value. In the section where the average value of the section time is larger than the average value, the difference is calculated by the basic correction voltage pattern. , The voltage applied to the brushless motor is increased, and in a section where the average value of the section time is smaller than the average value, the difference may be subtracted from the basic correction voltage pattern to reduce the applied voltage of the brushless motor. As a result, the basic correction voltage pattern becomes optimal corresponding to the shape of the load pulsation that is actually occurring. That is, basic correction voltage patterns that suppress load pulsations of various shapes can be obtained.

[0017]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described in detail with reference to FIG. In FIG. 2,
The same parts as those in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 1, in the brushless motor control method according to the present invention, times t10,..., T1m- in a section (0 to m-1) obtained by dividing one rotation into m (positive integers).
1 and the section time average value α0 (= (t1) for a plurality of rotations (L (positive integer) rotations) for each section.
0 + ... + t1m-1) / L),..., Α1m-1 (= tL
+ TLm-1) / L), the average value β of these section time average values α0,..., Α1m-1 is calculated, and the section time average values α0,. Is adjusted to increase or decrease the basic correction voltage pattern in accordance with the difference from the above, to obtain a new basic correction voltage pattern.

As shown in FIGS. 1A and 1B, during PWM control of the motor, a section where the duty of the PWM waveform becomes 100% when the above-described new basic correction voltage pattern is added. When this occurs, the input DC voltage of the inverter circuit is stepped up by a predetermined value, and the duty of the PWM waveform is made lower than 100%, or the duty is maintained at 100% to enable the PWM control. FIGS. 1A and 1B show PW
FIG. 9 is an M waveform diagram, in which the boosted state is represented by the amplitude of a PWM waveform.

For this reason, as shown in FIG. 2, the control device to which the brushless motor control method is applied is configured such that one rotation is performed for m sections (for example, in the case of a three-phase four-pole motor, 12 sections), and the time (section time) of each section is obtained by counting 12 times. This is obtained for L rotations, and the section time is added for each section.
The added section times are each divided by L to calculate twelve section time average values α0,..., Α11, and the twelve section time average values α0,. While calculating the value β, if the difference between the section time average values α0,..., Α11 and the average value β is in the positive direction for each section, the internal memory (non-volatile memory; EEPROM) 10
A predetermined value is added to the basic correction voltage pattern a, and if the difference is in the negative direction, the predetermined value is subtracted from the basic correction voltage pattern to adjust the basic correction voltage pattern. Control circuit (microcomputer) for correcting and controlling the applied voltage of the motor 4
10 is provided.

A booster circuit 11 is provided between the AC / DC conversion circuit 2 and the inverter circuit 3, and a control circuit 10
Thus, the booster circuit 11 is controlled to boost the input power supply voltage of the inverter circuit 3 by a predetermined value.

When the brushless motor 4 is controlled by the PWM control method, a section may occur in which the duty of the PWM waveform by the basic correction voltage pattern reaches 100%. At this time, the booster circuit 11 is controlled by a control signal from the control circuit 10 to boost the output DC voltage of the AC / DC conversion circuit 2 and output the power supply voltage of the inverter circuit 3.

Further, in the air conditioner, a control device for the outdoor unit is provided with an active filter and has a function of boosting the input DC voltage of the inverter circuit 3. In this case, the active filter is used as the booster circuit 11. Note that the control circuit 10 also has the function of the control circuit 6 shown in FIG.

The basic correction voltage pattern is a voltage pattern for canceling load pulsation as in the conventional example. In this case, the basic correction voltage pattern may be, for example, a voltage pattern that cancels the pulsation at a low load in the case of a compressor. Specifically, as shown by the curve in FIG. It shall be.

A basic correction voltage pattern for correcting the voltage applied to the brushless motor 4 so as to cancel the load pulsation is obtained (see FIG. 4). In FIGS. 3 and 4, numbers 0 to 11 indicate sections in which one rotation is equally divided into 12 sections in mechanical angle based on the position detection signal as described above.

In this case, as shown in FIG. 4, the average value of the section load pulsation is compared with the average value of the load pulsation for one rotation, and the average value of the section load pulsation is calculated from the average value of the load pulsation for one rotation. In a large section, a basic correction voltage pattern for increasing the applied voltage is obtained so that the load pulsation approaches the average value of the load pulsation of one rotation. Further, in a section where the average value of the section load pulsations is smaller than the average value of the load pulsation of one rotation, a basic correction voltage pattern for reducing the applied voltage is obtained so that the load pulsation approaches the average value of the load pulsation of one rotation.

In a section in which the average value of the section load pulsation is equal to the average value of the load pulsation of one rotation, a basic correction voltage pattern in which the applied voltage remains unchanged is obtained. The basic correction voltage pattern obtained in this manner is shown in FIG. 4. As in the conventional case, when the brushless motor 4 is controlled by the PWM control method, the ON width increase / decrease amount of the PWM ON / OFF ratio is used.

Next, the operation of the control device having the above configuration will be described. First, the control circuit 10 controls the brushless motor 4 as in the prior art.
It is assumed that the number of rotations is the target number of rotations. At this time, the control circuit 10 performs the torque control to cancel the load pulsation by adding the basic correction voltage pattern of the internal memory 10a to the current applied voltage of the brushless motor 4 as in the related art. The start position of the basic correction voltage pattern is a section where the load pulsation is maximized, and the phase of the load pulsation during one rotation and the phase of the basic correction voltage pattern are matched.

When the brushless motor 4 rotates L, as described above, the section time average α
, Α11, the average value β of the section time average values α1,..., Α12 is calculated, and the difference between the section time average values α0,. . This is because, as is clear from FIG. 3, the section pulsation differs according to the load pulsation, so that the section having a large load has a long time and the section having a small load has a short time. This is because it is reflected in time.

If the difference is in the positive direction, a predetermined value is added to the basic correction voltage pattern in that section to obtain a new basic correction voltage pattern. If the difference is in the negative direction, a predetermined value is subtracted from the basic correction voltage pattern in that section to obtain a new basic correction voltage pattern. If the difference is zero, the basic voltage pattern in that section remains unchanged.

Thus, a new basic correction voltage pattern obtained by adjusting the basic correction voltage pattern of the internal memory 10a is obtained. Note that the adjusted basic correction voltage pattern may be stored in the internal memory 10a, and the basic correction voltage pattern may be updated. Then, the applied voltage of the brushless motor 4 is corrected by the adjusted basic correction voltage pattern.

That is, since the pulsation shape of the load differs due to a change in the load condition or the like or the speed fluctuation, the rotation of the brushless motor 4 fluctuates, and this rotation fluctuation is added to the load pulsation. Also, the change is corrected. Therefore, the torque control is appropriately performed, and the load pulsation is suppressed, so that vibration and noise can be reduced.

As the predetermined value for adjusting the basic correction voltage pattern, a value corresponding to the difference between the section time average values α0,..., Α11 and the average value β is used, or the value of the difference is used as it is. Is also good. Initially, internal memory 1
If the basic correction voltage pattern stored in 0a is used as an initial value and the initial value is updated with the basic correction voltage pattern adjusted every L rotations as described above, torque control for suppressing load pulsation can be performed. It converges in a short time, and the torque control does not hunt.

When the brushless motor 4 is controlled by the PWM control method, as described above, when the basic correction voltage pattern is increased or decreased as necessary, the increased or decreased basic correction voltage pattern is applied to the current applied voltage. In some cases, the duty of the PWM waveform reaches 100% (see section n + 1 in FIG. 1A; n is a positive integer). Note that n corresponds to the section m described above.

Further, the duty may reach 100% in the section where the applied voltage is maximum. In particular, the duty tends to reach 100% in a section with a heavy load.
For this reason, the range of the torque control is limited,
Because it is not preferable, the booster circuit 11 is controlled to boost the input power supply voltage of the inverter circuit 3, and the duty of the PWM waveform is reduced as a whole with this boost (FIG. 1).
(B)). Further, the booster circuit 11 can boost the voltage in, for example, 50 V steps and can increase the voltage in a plurality of stages. Note that the maximum pressure increase may be determined by assuming the maximum load pulsation of the compressor.

As described above, since the input power supply voltage of the inverter circuit 3 is stepped up and can be stepwise stepped up, even if the duty of the PWM waveform reaches 100%, it is necessary to make the duty smaller than 100%. Can be.
Therefore, the above-described basic correction voltage pattern can be adjusted (increased), and the load pulsation can be more effectively suppressed by continuing the torque control.

When the duty of the PWM waveform reaches 100% in the section where the applied voltage is maximum during the torque control described above, the duty of the PWM waveform in that section becomes 10%.
The input power supply voltage of the inverter circuit 3 may be boosted while maintaining it at 0%. This means that the duty of the PWM waveform has reached 100%, which means that the applied voltage in that section requires 100% or more. Even if the duty of the PWM waveform is maintained at 100%, The input power supply voltage of the circuit 3 increases. Therefore, the same effect as described above can be obtained.

[0038]

As described above, according to the present invention,
The following effects are obtained. According to the first aspect of the present invention, even if there is one basic correction voltage pattern, the adjusted basic correction voltage pattern corresponds to the load pulsation that is actually occurring, and can be changed by the change in the load pulsation. In addition, the pulsation can be appropriately suppressed, and the rotation fluctuation can be suppressed to enable stable rotation control. Therefore, there is an effect that not only vibration and noise can be suppressed, but also the operation range of the torque control in the PWM control can be expanded. At this time, if the air conditioner already has an active filter, there is no need to newly provide a booster as hardware, and the cost does not increase.

According to the second aspect of the present invention, since the section time reflects the current load pulsation, the adjusted basic correction voltage pattern corresponds to the load pulsation that is actually occurring, as described above. This has the same effect as described above. In addition, there is an effect that the brushless motor is realized by software by a microcomputer which is a control means of the brushless motor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention and illustrating the operation of a method for controlling a brushless motor.

FIG. 2 is a schematic block diagram for explaining a control device to which the brushless motor control method of the present invention is applied.

FIG. 3 is a schematic diagram of a load pulsation curve for explaining the operation of the control device shown in FIG. 1;

FIG. 4 is a schematic diagram of a basic correction voltage pattern for explaining the operation of the control device shown in FIG. 1;

FIG. 5 is a schematic block diagram for explaining a conventional brushless motor control device.

[Explanation of symbols]

2 AC / DC conversion circuit 3 Inverter circuit 4 Brushless motor (sensorless DC brushless motor) 5 Position detection circuit 6, 10 Control circuit (microcomputer) 10a Internal memory (non-volatile memory; EEPROM) 11 Booster circuit (active filter) L rotation m Number of divisions t Section time α Section time average (for L rotations) β average (average of section time average for one rotation)

Claims (4)

[Claims] A DC power supply is set to an input power supply voltage of an inverter means, and a switching means of the inverter means is turned on and off in a predetermined manner to apply a voltage to a brushless motor, while a position of a rotor of the brushless motor is set. A brushless motor control method for detecting, controlling the inverter means based on the position detection, switching the energization of the armature winding of the brushless motor, and controlling the rotation of the brushless motor. Having one basic correction voltage pattern for suppressing pulsation,
While the applied voltage of the brushless motor is corrected using the basic correction voltage pattern, one of the brushless motors is corrected.
The rotation is equally divided into a plurality of sections by a mechanical angle, the load pulsation of each section is detected at the same section time, the section time of each section is obtained for a plurality of rotations, and the section time average value for each section is obtained by one rotation. The basic correction voltage pattern is adjusted so as to be close to the average value of the section time average value for one minute, the applied voltage of the brushless motor is corrected by the adjusted basic correction voltage pattern, the load pulsation is suppressed, and the brushless motor is adjusted. Suppress the fluctuation of the load pulsation due to the rotation fluctuation of
On the other hand, when the brushless motor is controlled by the PWM control method, the duty of the PWM waveform is 100
%, The DC voltage of the input power supply voltage of the inverter means is stepped up by a predetermined value, and the duty is set to 1
100% or its duty is 100
%, And the torque control can be continued by maintaining the torque control value in the control method of the brushless motor. 2. The method according to claim 1, further comprising: setting a DC power supply to an input power supply voltage of the inverter means, and turning on and off a switching means of the inverter means in a predetermined manner to apply a voltage to the brushless motor, while setting a position of a rotor of the brushless motor. A brushless motor control method for detecting, controlling the inverter means based on the position detection, switching the energization of the armature winding of the brushless motor, and controlling the rotation of the brushless motor. In order to suppress pulsation, one rotation of the brushless motor is equally divided into a plurality of sections by a mechanical angle, and each section has one basic correction voltage pattern for correcting an applied voltage of the brushless motor. While correcting the applied voltage of the brushless motor using the correction voltage pattern, the time of each section is measured. , Calculate the section time average value for a plurality of rotations for each section, add the section time average value, divide it by the number of divisions to calculate an average value, and calculate each section time average value. Adjusting the basic correction voltage pattern according to the difference from the average value, and correcting the applied voltage of the brushless motor by the adjusted basic correction voltage pattern to suppress the load pulsation of the brushless motor,
The fluctuation of the load pulsation is suppressed. On the other hand, when the brushless motor is controlled by the PWM control method, the PWM
When the duty of the M waveform has reached 100%, the DC voltage of the input power supply voltage of the inverter means is stepped up by a predetermined value, and the duty is made smaller than 100%, or the duty is maintained at 100%. A method of controlling a brushless motor, wherein torque control can be continued. 3. The brushless motor control method according to claim 1, wherein the basic correction voltage pattern is stored in advance as an initial value and updated each time the adjustment is performed. 4. The amount by which the basic correction voltage pattern is adjusted is a difference between the average value of each section time and the average value. In a section where the average value of the section time is larger than the average value, the difference is corrected by the basic correction voltage. The voltage applied to the brushless motor is increased by adding the voltage to the voltage pattern, and in a section in which the section average time is smaller than the average value, the difference is subtracted from the basic correction voltage pattern to reduce the applied voltage to the brushless motor. 4. The method for controlling a brushless motor according to claim 2, wherein