JP6485342B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor, and more particularly to a motor control device that controls driving of a sensorless three-phase brushless DC motor.

  For example, Patent Document 1 discloses an apparatus for controlling the driving of a sensorless three-phase brushless DC motor. Hereinafter, the sensorless three-phase brushless DC motor is referred to as a sensorless three-phase BLDC motor. By controlling the drive current at the start of the sensorless three-phase BLDC motor to a target value, this device suppresses torque fluctuations due to fluctuations in the drive current value and improves the startup performance of the sensorless three-phase BLDC motor. I am trying.

JP 2008-148379 A

  However, the above configuration requires a circuit and control software for feedback of the current flowing through the sensorless three-phase BLDC motor and detection of the acceleration of the rotor, which complicates the configuration of the device and increases the cost of the device. To do.

  Therefore, a motor control device that can improve the starting performance of a sensorless three-phase BLDC motor while suppressing the complexity of the configuration and the increase in cost is provided.

  A motor control device according to the present invention is a control device that controls driving of a sensorless three-phase BLDC motor, and includes a current detection circuit unit that detects a current flowing through the sensorless three-phase BLDC motor, and a sensorless three-phase BLDC motor. A control circuit unit for controlling the drive current, and based on a current value before starting detected by the current detection circuit unit before starting the sensorless three-phase BLDC motor by the control circuit unit, the sensorless three-phase The drive current at the time of starting the BLDC motor is adjusted.

  According to this configuration, the driving current at the time of starting is calculated based on the detected current value before starting without depending on the feedback of the current flowing through the sensorless three-phase BLDC motor and the circuit or control software for detecting the acceleration of the rotor. It can be adjusted to the target value. Therefore, it is possible to improve the starting performance of the sensorless three-phase BLDC motor while suppressing the complexity of the configuration and the increase in cost.

The figure which shows the structural example of the motor control apparatus which concerns on this embodiment. Flow chart showing an example of motor drive control The figure which shows an example of the state which sent the electric current before the start of a motor Timing chart showing an example of motor drive control Diagram comparing duty of drive signal corrected based on current value before start The figure which shows an example of the control waveform at the time of the start of a motor The figure which shows the correction example of the duty of a drive signal (the 1) FIG. 2 is a diagram illustrating an example of correcting a duty of a drive signal (No. 2) The figure which shows the example of a relationship between the electricity supply pattern before the motor start based on 2nd Embodiment, and the electric current value before a start. The figure which shows the example of control of the drive current at the time of the start of a motor The figure which shows the example of control of the drive current at the time of the starting of the motor which concerns on 3rd Embodiment The figure which shows an example of the current ripple control which concerns on 4th Embodiment

Hereinafter, a plurality of embodiments according to a motor control device will be described with reference to the drawings. In each embodiment, substantially the same elements are denoted by the same reference numerals, and description thereof is omitted.
(First embodiment)
A motor control device 10 illustrated in FIG. 1 includes an inverter circuit unit 11, a current detection circuit unit 12, a control circuit unit 13, and a gate drive circuit unit 14. The inverter circuit unit 11 is configured by connecting six switching elements 11a in a three-phase bridge. A DC power supply 15 is supplied to the inverter circuit unit 11. Each phase output terminal of the inverter circuit unit 11 is connected to each phase stator winding 17U, 17V, 17W of the sensorless three-phase BLDC motor 17 via a wire harness 16, respectively. Hereinafter, the sensorless three-phase BLDC motor 17 is simply referred to as “motor 17”.

  The current detection circuit unit 12 detects the current flowing through the motor 17 based on the terminal voltage of the resistor 18. The control circuit unit 13 includes a microcomputer or a logic circuit, and outputs a control signal to the gate drive circuit unit 14 while monitoring the current value detected by the current detection circuit unit 12. The control signal output from the control circuit unit 13 includes a PWM signal, a control signal for controlling driving of the high-side switching element 11a, a control signal for controlling driving of the low-side switching element 11a, and the like. .

  The gate drive circuit unit 14 generates a drive signal based on the control signal input from the control circuit unit 13 and outputs the drive signal to the inverter circuit unit 11. The inverter circuit unit 11 is switching-controlled by a drive signal input from the gate drive circuit unit 14. That is, the inverter circuit unit 11 drives the motor 17 by generating a drive current by turning on / off the plurality of switching elements 11 a based on the drive signal output from the gate drive circuit unit 14.

  Next, an example of drive control of the motor 17 by the motor control device 10 will be described. That is, as illustrated in FIG. 2, the control circuit unit 13 passes a current through an arbitrary phase of the motor 17 before starting the motor 17 (S <b> 1). At this time, the pattern of the energized phase in which the current flows is a pattern in which the current I flows in different phases on the high side and the low side, for example, as shown in FIG. That is, a combination pattern in which the high-side side and the low-side side are in phase is excluded as the energized phase pattern in which current flows.

  And the control circuit part 13 detects the electric current value which flows into the motor 17 as an electric current value before starting by the electric current detection circuit part 12 (S2). At this time, the control circuit unit 13 monitors the current value detected by the current detection circuit unit 12, and specifies the current value as the pre-starting current value after the detected current value is stabilized. And the control circuit part 13 will turn off the electricity supply to the motor 17, if the electric current value before start-up is specified.

  Then, the control circuit unit 13 corrects the duty of the drive signal when starting the motor 17 based on the detected current value before starting (S3). The duty correction control at the time of starting is configured by the processing of these steps S1 to S3. The duty correction control at the start is control for correcting the duty of the drive signal in order to control the drive current at the start of the motor 17 to a target value suitable for the motor 17 to be driven.

  When the duty of the drive signal is corrected by the start-time duty correction control, the control circuit unit 13 shifts to motor start control. In the motor start control, the control circuit unit 13 executes the positioning control (S4) of the motor 17 and subsequently executes the other control (S5) of the motor 17 and then the sensorless which is the steady control of the motor 17. Drive control (S6) is executed. That is, when the rotor of the motor 17 is positioned, the control circuit unit 13 performs other control to conduct current regardless of the detection result of the magnetic pole position of the rotor based on the induced voltage of the motor 17. Switching to sensorless drive control is performed in which energization is performed according to the detection result of the rotor magnetic pole position based on the voltage.

  As illustrated in FIG. 4, according to the above-described drive control example of the motor 17, as indicated by the symbol A, the control circuit unit 13 first supplies a current to an arbitrary phase of the motor 17 before starting the motor 17. Shed. In this case, the control circuit unit 13 energizes the motor 17 with an energized phase pattern that is a combination of the U phase on the high side and the W phase on the low side. Then, as indicated by reference numeral B, the control circuit unit 13 specifies the starting current value after the current flowing through the motor 17 is stabilized. And if the control circuit part 13 specifies the electric current value at the time of a start, as shown with the code | symbol C, the electricity supply to the motor 17 will be turned off. Then, the control circuit unit 13 corrects the duty of the drive signal based on the specified starting current value. Note that the current monitor value shown in the figure is not a current value actually flowing through the motor 117 but a waveform of a current value detected by the current detection circuit unit 12.

  As illustrated in FIG. 5, at this time, when the current value before starting is relatively large, for example, when the current value is larger than a predetermined threshold, the control circuit unit 13 reduces the duty of the drive signal to reduce the motor 17. Control is performed so that the drive current generated at start-up approaches or matches the target value. On the other hand, when the current value before starting is relatively small, for example, when the current value is smaller than a predetermined threshold, the control circuit unit 13 increases the duty of the driving signal and aims at the driving current generated when the motor 17 is started. Control to approach or match the value.

  When the duty of the drive signal is corrected, the control circuit unit 13 shifts to motor start control and starts the motor 17. At this time, since the duty of the drive signal is corrected, the drive current at the start is adjusted and controlled to the target value N as shown by the arrow D1 or the arrow D2 in FIG. Therefore, at the time of positioning control, a current of the target value N flows through the motor 17, and the motor 17 can be started while suppressing fluctuations in torque caused by fluctuations in the drive current value. In the other control and sensorless control thereafter, the amplitude of the induced voltage increases due to the increase in the rotational speed of the motor 17, and the drive current gradually decreases. Then, when the increase in the rotational speed of the motor 17 stops and reaches a constant rotational speed, the decrease in drive current also stops and is maintained at a constant value. In motor start control, so-called PWM control is performed in order to control output energy.

  As illustrated in FIG. 6, in the positioning control of the motor start control, the control circuit unit 13 turns on the switching element 11 a of the arbitrary phase on the high side and selects a phase other than the phase selected on the high side on the low side. The switching element 11a is turned on, and the other switching elements 11a are turned off. Thereby, the motor 17 is energized by an energized phase pattern in which current flows in different phases on the high side and the low side.

  In this case, the control circuit unit 13 performs positioning control twice. In the first positioning control, for example, the high-side U-phase switching element 11a and the low-side W-phase switching element 11a are turned on, and the other switching elements 11a are turned off. And by this energization, the rotor of the motor 17 moves and an induced voltage is generated. Therefore, a sinusoidal vibration is generated in the drive current. Thereafter, as the operation of the rotor converges, the amplitude of the drive current gradually decreases, and when the rotor stops, the drive current does not oscillate. Thereafter, a current determined by the voltage applied to the motor 17 and the motor impedance flows to the motor 17.

  Next, in the second positioning control, the control circuit unit 13 sets the energization phase so that the first and second energization phase differences are other than 0 deg and 180 deg in electrical angle. In this case, the energization phase in the first positioning control was the U phase on the high side and the W phase on the low side. Therefore, in the second positioning control, the motor 17 is energized by an energized phase pattern in which the high side, which is 60 deg away from the electrical angle, is the V phase and the low side is the W phase.

  Next, in other control, the control circuit unit 13 energizes the motor 17 with a predetermined energization phase pattern, PWM duty, and energization time to rotate the rotor. At this time, the control circuit unit 13 sets the energized phase so as to generate torque in the desired rotation direction from the energized state by the energized phase pattern in the second positioning control. In this case, the energization phase in the second positioning control was the V phase on the high side and the W phase on the low side. Therefore, the control circuit unit 13 switches the initial energization phase of the other control to an energization phase pattern in which, for example, the high side separated by 60 degrees in the electrical angle is the V phase and the low side is the U phase, and energizes the motor 17. Do.

  Thereafter, the control circuit unit 13 sequentially switches the energized phases so as to generate torque in a desired rotation direction. At this time, the control circuit unit 13 switches so that the phase difference between the energized phases is, for example, 60 degrees in terms of electrical angle. In this case, the energization phase in the second positioning control was the V phase on the high side and the W phase on the low side, and the energization phase in the other control was the V phase on the high side and the U phase on the low side. Therefore, in the subsequent phase, the control circuit unit 13 switches to the energized phase pattern in which the high side is the W phase and the low side is the U phase, and then switches to the energized phase pattern in which the high side is the W phase and the low side is the V phase. To go. Thereafter, the control circuit unit 13 shifts to sensorless control at the timing when the position of the rotor can be detected. The control circuit unit 13 controls the rotation of the rotor by switching the energized phase according to the detected position while detecting the position of the rotor. The phase difference between the energized phases can be changed without being limited to 60 degrees as long as the electrical angle is other than 0 deg and 180 deg.

  Next, an example of correcting the duty of the drive signal will be described. In the first correction example illustrated in FIG. 7, the control circuit unit 13 corrects the duty of the drive signal based on one threshold value T. That is, when the current value before starting is larger than the predetermined threshold value T, the control circuit unit 13 decreases the duty of the driving signal to bring the driving current generated when starting the motor 17 close to the target value, or Control to match. On the other hand, when the current value before starting is smaller than the predetermined threshold T, the control circuit unit 13 increases the duty of the driving signal to bring the driving current generated when starting the motor 17 close to the target value, or Control to match.

The duty of the drive signal at the time of start-up, that is, the duty of the drive signal after correction, can be calculated based on the ratio between the current value before start-up and the threshold T based on the following equation (1), for example.
Duty at start-up = Duty reference value at start-up x threshold value / current value before start-up (1)

  It should be noted that the duty reference value at the start is determined by the drive current at the start of the motor 17 under a predetermined condition, for example, a condition where a predetermined power supply voltage is applied, an impedance condition of an actual current path, or the like. The duty ratio matches a predetermined target value. Further, the duty of the drive signal at the start may be calculated based on, for example, the difference between the pre-start current value and the threshold value T.

  In the second correction example illustrated in FIG. 8, the control circuit unit 13 corrects the duty of the drive signal based on the two threshold values Tmax and Tmin. That is, when the current value before starting is larger than the predetermined upper limit threshold Tmax, the control circuit unit 13 reduces the duty of the driving signal for generating the driving current and generates the driving current generated when starting the motor 17. Is controlled so that it approaches or matches the target value. On the other hand, when the current value before starting is smaller than the predetermined lower limit threshold Tmin, the control circuit unit 13 increases the duty of the driving signal to bring the driving current generated when starting the motor 17 closer to the target value, or , Control to match. Note that when the pre-starting current value is within the upper limit threshold Tmax and the lower limit threshold Tmin, the control circuit unit 13 maintains the drive signal without correcting the duty. That is, when the current value before starting is between the upper limit threshold value Tmax and the lower limit threshold value Tmin, the duty of the drive signal at the time of starting becomes the duty reference value at the time of starting. As a result, the drive current at the start of the motor 17 falls within a predetermined target range. The predetermined target range is illustrated by a symbol R in FIG.

  According to the motor control device 10, the drive current at the start is aimed based on the detected current value before the start, without depending on the feedback of the current flowing through the motor 17 or the circuit or control software for detecting the acceleration of the rotor. It can be adjusted to approximate or match the value. Therefore, torque fluctuations can be suppressed while suppressing the complexity of the configuration and cost increase, and the starting performance of the motor 17 can be improved.

  Further, the motor control device 10 adjusts the drive current at the start based on the actual current value before the start of the motor 17. Therefore, for example, each element in the device such as the motor 17 and the switching element 11a, the wire harness 16, and the like, the change in impedance due to the temperature characteristics, and the difference in the length of the current path including the wire harness 16 are caused. The motor 17 can be started by a driving current suitable for the configuration of the entire motor control system including the motor control device 10 and the motor 17 regardless of the change in impedance to be performed.

Further, according to the motor control device 10, by correcting the duty of the drive signal based on one threshold value T, the drive current at the start can be made constant, and the start performance of the motor 17 can be made more stable. Can do.
Further, according to the motor control device 10, by correcting the duty of the drive signal with reference to the two threshold values Tmax and Tmin, the drive current at the start can be kept within a certain range, and the start performance of the motor 17 can be reduced. It can be made more stable.

(Second Embodiment)
As illustrated in FIG. 9, in the present embodiment, the control circuit unit 13 energizes the motor 17 with a plurality of energized phase patterns Puv to Pwv before the motor 17 is started. In this case, the control circuit unit 13 includes the energized phase pattern Puv in which the high side is the U phase and the low side is the V phase, the energized phase pattern Puw in which the high side is the U phase and the low side is the W phase, the high side is the V phase, and the low side. Energized phase pattern Pvu whose side is the U phase, the high side is the V phase, the energized phase pattern Pvw where the low side is the W phase, the high side is the W phase, the energized phase pattern Pwu where the low side is the U phase, the high side is the W phase, The motor 17 is energized sequentially by 6 patterns of energized phase patterns Pwv in which the low side is the V phase. Then, the control circuit unit 13 detects pre-starting current values Iuv to Iwv detected by the current detection circuit unit 12 when energized by the energized phase patterns Puv to Pwv, respectively.

  Then, as illustrated in FIG. 10, the control circuit unit 13 calculates an average value of the current values Iuv to Iwv before starting. Then, the control circuit unit 13 adjusts the drive current when the motor 17 is started based on the calculated average value. That is, for example, when the average value is relatively large, the control circuit unit 13 reduces the duty of the drive signal so that the drive current generated when the motor 17 is started approaches or matches the target value. To control. On the other hand, when the average value is relatively small, the control circuit unit 13 increases the duty of the drive signal and controls the drive current generated when the motor 17 is started to approach or match the target value. To do.

  Strictly speaking, the impedance of the current path may vary depending on the energization phase pattern to the motor 17, that is, how the current flows through the motor 17. According to the present embodiment, the drive current is corrected using the average value of the detected current values Iuv to Iwv when the plurality of energized phase patterns Puv to Pwv are energized. Therefore, it is possible to absorb fluctuations in the impedance of the current path that occurs when different energized phase patterns Puv to Pwv are energized, and it is possible to avoid the drive current at the time of starting from deviating significantly from the target value.

(Third embodiment)
As illustrated in FIG. 11, in the present embodiment, the control circuit unit 13 energizes the motor 17 with a plurality of energized phase patterns Puv to Pwv before the motor 17 is started. The control circuit unit 13 energizes the motor 17 with the same energized phase pattern when starting the motor 17 based on the current value before starting detected by the current detection circuit unit 12 when energizing with one energized phase pattern. Adjust the drive current. That is, when the motor 17 is started, when the energization phase pattern Puv in which the high side is the U phase and the low side is the V phase is energized, the energization is performed with the same energization phase pattern Puv before the motor 17 is started. The drive current is adjusted based on the current value Iuv before starting that is sometimes detected.

  According to the present embodiment, using the detected current values Iuv to Iwv when energizing a plurality of energized phase patterns Puv to Pwv, the drive current when energized with the same energized phase patterns Puv to Pwv at the start is corrected. . Therefore, it is possible to absorb fluctuations in the impedance of the current path that occurs when energizing different energized phase patterns Puv to Pwv, and when energizing the motor 17 with a plurality of energized phase patterns Puv to Pwv at the start, It can be avoided that the drive current greatly deviates from the target value during energization.

  The control circuit unit 13 selects any one of a plurality of pre-starting current values Iuv to Iwv detected before starting, and based on the pre-starting current values, the motors have different energized phase patterns at starting. You may comprise so that the drive current at the time of energizing 17 may be adjusted. That is, for example, based on the pre-starting current value Iuv detected when the energized phase pattern Puv is energized before starting, the motor 17 is energized with the energizing phase pattern Puv at the start, and the energized phase patterns Puw to Pwv are used. You may comprise so that the drive current at the time of energizing the motor 17 may also be adjusted.

(Fourth embodiment)
As illustrated in FIG. 12, in the present embodiment, when the current detection circuit unit 12 detects the pre-starting current value, the control circuit unit 13 sets the cycle Tmon of the drive signal for generating the drive current to a predetermined cycle. Shorter than Tsen. Note that the cycle Tsen is a cycle of a default drive signal when the motor 17 is started or a cycle of a drive signal when the motor 17 is in steady driving.

  When a current is passed through the motor 17, it is necessary to set the duty of the drive signal so as not to exceed the rated current of the motor 17. At this time, for example, if the switching element 11a is turned on / off by PWM control in a state where the duty of the drive signal is smaller than 100%, the current increases at the time of turning on, and the slope of this increase becomes smaller as time passes from on. Then, when it is turned off, the current decreases, and the slope of this decrease becomes smaller as time passes from off. Therefore, the current ripple Vsen is generated, and a difference due to the current ripple Vsen occurs in the detected current value depending on the timing of current detection by the current detection circuit unit 12.

Therefore, in the present embodiment, the cycle Tmon of the drive signal is made shorter than the cycle Tsen. Thereby, the current ripple Vsen can be reduced to the current ripple Vmon, and the difference in the detected current value due to the current ripple can be suppressed. Therefore, according to the present embodiment, variation in the detected current value due to current ripple can be suppressed.
Note that the present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist thereof.

  In the drawings, 10 is a motor control device, 12 is a current detection circuit unit, and 13 is a control circuit unit.

Claims (6)

A current detection circuit section (12) for detecting a current flowing through the motor;
A control circuit unit (13) for controlling the drive current of the motor,
The control circuit unit is a motor control device that adjusts the driving current when starting the motor based on a current value before starting detected by the current detection circuit unit before starting the motor.   The control circuit unit reduces the duty of the drive signal for generating the drive current when the pre-start current value is greater than a predetermined threshold, and the drive signal when the pre-start current value is less than the threshold. The motor control device according to claim 1, wherein the duty of the motor is increased.   The control circuit unit reduces the duty of the drive signal for generating the drive current when the pre-start current value is larger than a predetermined upper limit threshold, and when the pre-start current value is smaller than a predetermined lower limit threshold The motor control device according to claim 1, wherein the duty of the drive signal is increased, and the duty of the drive signal is maintained when the pre-starting current value is between the upper limit threshold and the lower limit threshold.   The control circuit unit energizes the motor with a plurality of energized phase patterns before starting the motor, and an average value of a plurality of pre-starting current values detected by the current detection circuit unit when energized with each energized phase pattern, respectively. 4. The motor control device according to claim 1, wherein the drive current at the time of starting the motor is adjusted based on the motor.   The control circuit unit energizes the motor with a plurality of energized phase patterns before starting the motor, and based on a pre-starting current value detected by the current detection circuit unit when energized with one energized phase pattern, 4. The motor control device according to claim 1, wherein the drive current is adjusted when the motor is energized with the same energization phase pattern when the motor is started. 5.   When the current detection circuit unit detects the pre-starting current value, the control circuit unit can set a cycle of a driving signal for generating the driving current when starting the motor or during steady driving of the motor. The motor control device according to claim 1, wherein the motor control device is shorter than the cycle.

Images