JP6127895B2 - Motor control device and motor control method - Google Patents

Description

  The present invention relates to a motor control device and a motor control method for PWM-controlling a brushless DC motor by a position sensorless method.

  As a driving method of a brushless DC motor, there is a so-called position sensorless method in which a zero-cross point of an induced voltage generated in a stator winding of a motor is detected and an energized phase is sequentially switched based on the zero-cross point (for example, Patent Document 1). , 2). The zero cross point is the switching timing in the direction of the current flowing through the winding of the energized phase, or the induced voltage that appears in the winding of the non-energized phase, In this application, it is a timing that changes across a voltage of a neutral point). The detection of the zero cross point is performed on the induced voltage appearing in the winding of the phase that is not energized. However, when PWM control of the motor is performed via the inverter circuit, a return current flows through the free wheel diode (or parasitic diode) at the timing when the switching element such as a transistor is turned off.

JP 7-123777 A Japanese Patent Laid-Open No. 9-9676

However, since the zero cross point cannot be detected during the period in which the reflux current flows, the detectable period is narrowed accordingly. When the detectable period is narrowed, it becomes difficult to follow control when the rotational speed of the motor fluctuates or when the rotational speed increases.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor control device and a motor control method capable of controlling a period during which a return current flows in an inverter circuit.

  According to the motor control device of claim 1, the terminal voltage comparator compares each phase terminal voltage of the motor with a threshold voltage corresponding to the neutral point voltage of the motor, and the zero cross timing signal generator A zero cross timing signal is generated from the comparison result of the phase in which the energization is turned off in the inverter circuit, which is output from the voltage comparator. The energization pattern switch outputs an energization signal so as to switch the energization pattern of each phase based on the PWM signal based on the zero cross timing signal. And the recirculation | reflux control time measuring device measures the recirculation | reflux control time which is the time when the recirculation | current current is flowing into the inverter circuit. If comprised in this way, since the length of the recirculation | reflux control time can be grasped | ascertained concretely, according to the measurement result, the control for shortening the recirculation | reflux control time can be performed.

State the reflux control time counter, as a starting point the timing of energization signal indicates a power-off, showing output from the terminal voltage comparator, a phase comparison result which is determined by the direction of current flowing through the motor, the disappearance of the circulating current Is measured as the reflux control time. That is, the return current is generated at the timing when the switching element of the energized phase in the inverter circuit is turned off, and flows in a pulse shape exceeding the neutral point equivalent voltage of the motor. Therefore, the period during which the return current flows can be measured by referring to the change in the signal output from the terminal voltage comparator.

The the reflux control time counter, the W-phase direction of the current from the V-phase, or a W periods flowing to the V phase from phase, based on the comparison result output from the terminal voltage comparator corresponding to U-phase U Measure the phase reflux control time. In the period in which the direction of current flows from the U phase to the W phase or from the W phase to the U phase, the V phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the V phase. measure. In the period in which the direction of current flows from the U phase to the V phase or from the V phase to the U phase, the W phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the W phase. measure. Therefore, the reflux control time can be measured for each phase according to the energization direction between the U, V, and W phases.

Conductible pattern switch from one phase of the upper arm side of inverter circuit, when switching the energization pattern for energizing the different one phase of the lower arm, the one phase of the upper arm side of inverter circuit, the lower arm Control is performed to shorten the reflux control time by temporarily generating a three-phase energization pattern for energizing different two phases. When a three-phase energization pattern is generated in this way, a current is diverted from one phase on the upper arm side to two phases on the lower arm side, and one of them is turned off to generate a reflux current. . Since the amount of reflux current generated at that time becomes smaller, the reflux control time can be shortened. Therefore, the period for detecting the zero cross point of the induced voltage can be extended.

According to the motor control device of the second aspect , the energization pattern switching unit delays the end timing of the energization on period after the next time by a predetermined time if the recirculation control time exceeds the first control range. Control is performed so that the control time is within the first control range. Further, when the recirculation control time enters the second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined time. By adjusting the reflux control time in this way, the reflux control time can be shortened within a range that does not completely disappear.

Functional block diagram showing the processing function of the microcomputer built in the motor control device according to the first embodiment The figure which shows the whole structure of a motor control apparatus Flow chart showing control contents of rotation speed detector and energization pattern switcher Timing chart showing energization pattern in a state where a three-phase energization pattern is generated Flow chart showing the measurement process of the reflux current control time Timing chart showing signal waveforms related to measurement of return current control time The flowchart which shows the processing content of step S3 of FIG. Partial equivalent diagram of FIG. The figure which shows the terminal voltage waveform of each phase when energization off timing is not corrected FIG. 9 equivalent diagram when the power-off timing is corrected The figure which is 2nd Embodiment and shows the terminal voltage waveform of U phase and the zero cross timing signal of each phase FIG. 7 equivalent view showing the third embodiment FIG. 1 equivalent diagram showing the fourth embodiment

(First embodiment)
As shown in FIG. 2, for example, an in-vehicle motor drive control device 1 is mainly configured by a microcomputer (a microcomputer, a control circuit) 2 and an inverter circuit 3. The motor drive control device 1 is supplied with drive power via an ignition switch (IG) of the vehicle. The driving power is supplied to the inverter circuit 3 (driving circuit) via a π-type filter 6 including capacitors 4 a and 4 b and a coil 5.

  The driving power is supplied to the 5V power circuit 8 through the diode 7. The 5V power supply circuit 8 steps down the drive power supply voltage to generate a 5V control power supply, and supplies it to the power supply terminal of the microcomputer 2. A bypass capacitor 9 is connected between the power supply terminal of the microcomputer 2 and the ground. A motor rotation speed command is input to the command rotation speed receiver 10 as a low-speed PWM signal from a host controller (not shown). The command rotational speed receiver 10 generates a higher-speed PWM signal according to the input PWM command value (PWM duty) and outputs it to the input port of the microcomputer 2.

  The inverter circuit 3 includes three element modules 11U, 11V, and 11W, and each element module 11 includes two N-channel MOSFETs (switching elements) 12 and 13 connected in series. Free wheel diodes (parasitic diodes) 12D and 13D are connected between the drains and sources of the FETs 12 and 13, respectively. And the common connection point of these FET12 and 13 becomes each phase output terminal of the inverter circuit 3, and via the output terminals 1U, 1V, and 1W of the motor drive control apparatus 1, the motor 14 which is a three-phase brushless DC motor, for example. It is connected to each phase stator winding 15U, 15V, 15W. The microcomputer 2 (PWM signal output means) outputs a PWM signal to the gates of the N-channel MOSFETs 12 and 13 constituting the inverter circuit 3 by operating the built-in CPU in accordance with a control program (software). Drive control.

In addition, the element module 11 includes a terminal voltage comparator (comparator) 16 (U in FIG. 2) that compares the potential at the common connection point of the FETs 12 and 13 with the neutral point equivalent potential (sum of each phase voltage) of the motor 14. Phase only). The terminal voltage comparator 16 is used by the microcomputer 2 to detect the zero cross point of the induced voltage of the motor 14. The neutral point equivalent potential is supplied by a neutral point voltage generator 17 shown in FIG. The output signal of the comparator 16 provided in each element module 11 is input to the input port of the microcomputer 2.
The microcomputer 2 refers to the output signal of the terminal voltage comparator 16 (U, V, W) given to the input port, and is generated in the stator windings 15U, 15V, 15W when the motor 14 is rotating. The zero cross point of the induced voltage is detected.

  As shown in FIG. 1, in the microcomputer 2, the zero cross timing signal generator 21 receives an output signal from the terminal voltage comparator 16 (U, V, W), and performs zero cross of each phase of U, V, W. A rectangular-wave timing signal indicating a point with a rise edge and a fall edge is generated and output for each phase. These timing signals are input to the rotation speed measuring device 22 and the energization pattern switching device 23.

  The rotational speed measuring device 22 measures the rotational speed of the motor 14 by measuring the edge interval of the zero cross timing signal, and outputs the measurement result to the energization pattern switching device 23 and the PWM duty calculator 24. The energization pattern switching unit 23 generates a switching signal for switching the energized phase based on the PWM signal to U, V, W in accordance with the input zero-cross timing signal of each phase and the rotational speed of the motor 14. To 25.

  The PWM duty calculator 24 receives the rotational speed command via the command rotational speed receiver 10 and calculates the PWM duty command according to the difference from the rotational speed of the motor 14 measured by the rotational speed measuring device 22. And output to the PWM signal generator 25. The PWM signal generator 25 generates a PWM signal from the internally generated PWM control carrier and the duty command, and outputs U, V, and W phase PWM signals according to the energized phase switching signal. For example, 120 degree energization method (the upper arm side switching element is turned on for 120 degrees and then the upper arm side switching element is turned off, and after 60 degrees, the lower arm side switching element is turned on for 120 degrees and then the lower arm side The switching element is turned off, and after 60 degrees, the upper arm side switching element is turned on, and these operations are repeated. Note that the carrier period in PWM control is, for example, about 20 kHz.

  The output signal from the terminal voltage comparator 16 (U, V, W) is also input to the reflux control time measuring device 26. The recirculation control time measuring device 26 measures the recirculation control time, which is the time during which the recirculation current flows through the free wheel diodes 12D and 13D, based on the change of the output signal, and the measurement result is sent to the energization pattern switch 23. Output. The energization phase switching signal output from the energization pattern switching unit 23 is input to the reflux control time measuring unit 26 and fed back.

As shown in FIG. 3, the microcomputer 2 measures and calculates the rotational speed of the motor 14 by the rotational speed measuring device 22 at the timing when the zero cross point is determined (S1). Then, the energization pattern switching unit 23 calculates the energization off time T _OFF in each phase energization pattern based on the current PWM signal using, for example, a relational expression determined in advance from the rotation speed (S2). Next, the energization-off start time T _OFS is calculated. Here, the energization-off start time is corrected (details will be described later) for the reflux control time (S3).

Then, the energization pattern when the next energization is turned off is determined (S4). This is a fixed pattern and is switched in a predetermined order every time a zero cross point is determined. If the energization off start time T _OFS obtained in step S3 is equal to or less than the energization off time T _{OFF in} step S2 (NO), the energization pattern determined in step S4 is output as it is (S7), and T _OFS > T If it is _OFF (YES), a three-phase energization pattern is generated in the process of switching to the energization pattern (S6). Here, the “three-phase energization pattern” means a pattern in which the lower arm side is energized in two phases while the energization is normally performed between the upper and lower arms of the inverter circuit 3 one by one.

  That is, as shown in FIG. 4B, when the energization pattern is switched, the direction of the current flowing through the motor 14 (inverter circuit 3) is Uh (upper) → Vl (lower), Uh → Wl, Vh → Wl, Vh. → It changes in the order of Ul,. In the process of switching the energization pattern in this way, a pattern of energization from the upper arm 1 phase to the lower arm 2 phase is generated such as Uh → Vl & Wl, Vh → Wl & Ul,... (Shown by a broken line in the figure). .

  The process shown in FIG. 5 is executed every 10 μs, for example. The reflux control time measuring device 26 determines the timing at which the energization of any phase of U, V, and W is switched off (S11, S19, S24). If the U-phase energization is off (S11: YES), it is determined whether the energization pattern is (Vh → Wl) or (Wh → Vl) (S12, S15). If the energization pattern is (Vh → Wl) (S12: YES) and the output signal level of the terminal voltage comparator 16U is low (S13: YES), the freewheeling diode 13UD on the U-phase lower arm side has a return current. This is a flowing period (see FIG. 6). Therefore, the counter for measuring the reflux control time is incremented (S14).

  If the energization pattern is (Wh → Vl) (S15: YES) and the output signal level of the U-phase terminal voltage comparator 16U is high (S16: YES), the U-phase upper-arm freewheel This is a period during which a return current flows through the diode 12UD (see FIG. 6). Therefore, the process proceeds to step S14. If “NO” is determined in any of steps S13 and S16, it is determined whether or not the counter value is “0” (S17). Here, if it is not “0” (NO), it indicates that the reflux control time being measured at that time has ended. Accordingly, the counter value is multiplied by 10 μs of the processing period to obtain the reflux control time, and then the counter is cleared to zero (S18). If “NO” is determined in the step S15, the process proceeds to a step S29 to clear the counter to zero.

  If the V-phase energization is off (S19: YES), it is determined whether the energization pattern is (Wh → Ul) or (Uh → Wl) (S20, S22). If the energization pattern is (Wh → Ul) (S20: YES) and the output signal level of the terminal voltage comparator 16V is low (S21: YES), the freewheeling diode 13VD on the V-phase lower arm side has a return current. This is a flowing period (see FIG. 6). Therefore, the process proceeds to step S14.

  Further, if the energization pattern is (Uh → Wl) (S22: YES) and the output signal level of the terminal voltage comparator 16V is high (S23: YES), it returns to the free wheel diode 12VD on the V-phase upper arm side. This is a period during which current flows (see FIG. 6). Therefore, the process proceeds to step S14. If "NO" is determined in any of steps S21 and S23, the process proceeds to step S17. If “NO” is determined in the step S22, the process shifts to a step S29.

  If the W-phase energization is off (S24: YES), it is determined whether the energization pattern is (Uh → Vl) or (Vh → Ul) (S25, S27). If the energization pattern is (Uh → Vl) (S25: YES) and the output signal level of the terminal voltage comparator 16W is low (S26: YES), the freewheeling diode 13WD on the W-phase lower arm side has a return current. This is a flowing period (see FIG. 6). Therefore, the process proceeds to step S14.

  Also, if the energization pattern is (Vh → Ul) (S27: YES) and the output signal level of the terminal voltage comparator 16W is high (S28: YES), it returns to the free wheel diode 12WD on the W-phase upper arm side. This is a period during which current flows (see FIG. 6). Therefore, the process proceeds to step S14. If "NO" is determined in any of steps S26 and S28, the process proceeds to step S17. If “NO” is determined in the step S27, the process shifts to a step S29. With the above processing, as shown in FIG. 6 (c, d), the period during which the reflux current of each phase flows can be measured by the counter.

The process shown in FIG. 7 is executed at each zero cross point detection timing. The energization pattern switching unit 23 determines whether or not the reflux control time exceeds 50 μs at that time (S31) and whether or not the reflux control time is less than 20 μs (S32). Here, the first and second control ranges for the reflux control time are set as follows.
First control range: 20 μs or more and 50 μs or less Second control range: less than 20 μs Therefore, if “YES” is determined in step S31, the variable “off start correction” (initial value is 0) is set to 1 μs (predetermined time). After the addition (S32), the process proceeds to step S35. In this case, the reflux control time exceeds the first control range.

  If “YES” is determined in the step S33, the variable “off start correction” is subtracted by 1 μs (S34), and the process proceeds to the step S35. In this case, the reflux control time is within the second control range. If “NO” is determined in the step S33, the reflux control time is in the first control range, and the process directly proceeds to the step S35.

In step S35, the energization off start time T _OFS is determined as follows.
T _OFS = max (T _OFF + off start correction, energization off end time)
Here, as shown in FIG. 8, the energization-off end time is the time when the W-phase energization switches from off to on, for example, in the case where the energization direction changes from (Uh → Vl) to (Uh → Wl). . In this case, the time when the V-phase energization switches from on to off is the energization-off start time, and the time from the energization-off end time to the energization-off start time is the time during which three-phase energization is performed (three-phase energization time) )

Therefore, in step S35, when T _OFS = (energization off end time), the three-phase conduction pattern does not occur, and when T _OFS = (T _OFF + off start correction), the three-phase conduction pattern is changed. Occur. In the above example, while the energization direction shifts from (Uh → Vl) to (Uh → Wl), a period in which the upper arm 1 phase becomes (Uh → Vl, Wl) and the lower arm 2 phase is energized occurs. Will do. As a result of performing the above processing, the reflux control time is adjusted to fall within the first control range.

  If the reflux control time falls within the second control range, the reflux current may disappear completely and the measurement of the reflux control time may not be possible. In this case, the “off start correction” is reduced to reduce the three-phase. The energization time is shortened. Further, if the “off start correction” is increased to generate a three-phase energization pattern, the period during which the energized phase is turned off is delayed. In this case, the reflux control time measuring device 26 starts measuring the next reflux control time from the delayed off start time.

  In the case shown in FIG. 9, the energization-off end time and the energization-off start time always coincide with each other in the process of switching the energization pattern. As a result, when the amount of energization current is increased in order to rotate the motor at a high speed, the time during which the return current flows (return control time) becomes longer, and accordingly, the zero cross point detectable period is shortened. Then, there is a possibility that the zero cross point cannot be detected in the high speed rotation region.

  On the other hand, when the control of this embodiment is performed, as shown in FIG. 10, the time for starting to turn off the energized phase that is turned on becomes later than the normal energization pattern by “off start correction”, The three-phase energization period is generated later than the time when the energized phase is turned on. As a result, since the recirculation control time is shortened, it is possible to secure a longer period for detecting the zero cross point.

  As described above, according to the present embodiment, in FIG. 1, the terminal voltage comparator 16 (U, V, W) compares each phase terminal voltage of the motor 14 with the threshold voltage corresponding to the neutral point voltage, The zero cross timing signal generator 21 generates a zero cross timing signal from the comparison result of the phase output from the terminal voltage comparator 16 and energized by the inverter circuit 3. The energization pattern switcher 23 outputs an energization signal so as to switch the energization pattern of each phase based on the PWM signal based on the zero cross timing signal. And the recirculation | reflux control time measuring device 26 can grasp | ascertain the length of the time specifically by measuring recirculation | reflux control time, and can perform control for shortening recirculation | reflux control time according to the measurement result.

  Further, the reflux control time measuring device 26 starts from the timing when the energization signal indicates that the energization is turned off, and the comparison result of the phase determined by the direction of the current flowing through the motor 14 that is output from the terminal voltage comparator 16U indicates the disappearance of the reflux current. The time until the state shown is measured as the reflux control time. That is, the return current is generated when the N-channel MOSFET 12 or 13 of the energized phase in the inverter circuit 3 is turned off, and flows in a pulsed manner exceeding the neutral point equivalent voltage of the motor 14. Accordingly, the period during which the return current flows can be measured by referring to the change in the signal output from the terminal voltage comparator 16.

  In this case, the recirculation control time measuring device 16 determines the U phase based on the comparison result output from the terminal voltage comparator 16 during the period in which the direction of the current flows from the V phase to the W phase or from the W phase to the V phase. In the period during which the current direction flows from the U phase to the W phase or from the W phase to the U phase, the V phase reflux control is performed based on the comparison result output from the terminal voltage comparator 16V. Measure time. In the period in which the direction of current flows from the U phase to the V phase or from the V phase to the U phase, the W phase reflux control time is measured based on the comparison result output from the terminal voltage comparator 16W. Therefore, the reflux control time can be measured for each phase according to the energization direction between the U, V, and W phases.

  When the energization pattern switching unit 23 switches the energization pattern to energize from one phase on the upper arm side of the inverter circuit 3 to a different one phase on the lower arm side, A three-phase energization pattern for energizing two different phases on the arm side is temporarily generated to shorten the reflux control time. By generating the three-phase energization pattern in this way, the amount of reflux current generated when one of the currents is diverted from one phase on the upper arm side to the two phases on the lower arm side. The reflux control time can be shortened by reducing. Therefore, the period for detecting the zero cross point of the induced voltage can be extended, and the zero cross point can be stably detected even in the high-speed rotation region of the motor 14.

  Further, if the recirculation control time exceeds the first control range, the energization pattern switching unit 23 delays the end timing of the energization on period after the next time by a predetermined time so that the recirculation control time is within the first control range. Control to be. Further, when the recirculation control time enters the second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined time. By adjusting the reflux control time in this way, the reflux control time can be shortened within a range that does not completely disappear. Furthermore, since the energization pattern switching unit 23 delays the end timing of the energization on period only for the N channel MOSFETs 12 and 13 constituting the inverter circuit 3 that actually energize off, unnecessary control is performed. It is avoided to do.

  Further, when the end timing of the energization on period is delayed by the action of the energization pattern switching unit 23, the reflux control time measuring device 26 starts from the timing when the energization is turned off due to the delay. Therefore, even when a three-phase energization pattern is generated, the reflux control time can be accurately measured.

(Second Embodiment)
The second embodiment will be described below with reference to FIG. A portion indicated by hatching in FIG. 11A indicates a period in which the reflux control time is shortened by generating the three-phase energization pattern. FIG. 11B shows the zero-cross timing signal of each phase output from the zero-cross timing signal generator 21. These zero-cross timing signals are divided into sections having an electrical angle of 60 degrees according to the edge interval of these zero-cross timing signals. These signals are generated based on the output signal of the terminal voltage comparator 16. Since the terminal voltage comparator 16 is a comparator, if the comparator has hysteresis characteristics, it may have different variations on the rising edge side and the falling edge side.

  Therefore, in the second embodiment, as shown in FIG. 11, the energization pattern switch 23 corrects the energization off timing based on the reflux control time measured in the section starting at the fall edge of the zero cross timing signal. Do this for the section that starts with the edge. That is, one section is skipped and the energization off timing is corrected. The same applies to the rise edge side, and the power-off timing correction based on the reflux control time measured in the section starting at the rise edge is performed for the section starting at the next rise edge. By controlling in this way, it is possible to correct the energization off timing for the same side edge.

  As described above, according to the second embodiment, in the energization pattern switching unit 23, the edge on the same side as the edge on which the zero cross timing signal has changed when the recirculation control time measuring device 26 starts measuring the recirculation control time is displayed next time. , The end timing of the energization on period based on the measurement result is controlled. That is, since the energization off timing is corrected for the same edge, the control accuracy can be improved.

(Third embodiment)
In the third embodiment, as shown in FIG. 12, step S30 is added before step S31 shown in FIG. 7, and steps S32, S34, and S35 are replaced with steps S36 to S38. In step S30, the three-phase energization time is determined from the rotational speed of the motor 14. The three-phase energization time is set to an initial value that seems to be necessary when the rotational speed is in a region that is somewhat high. Therefore, the initial value may be 0% in the region where the rotational speed is low.

In step S36, the variable “off start correction” is added by 1% (predetermined ratio), and then the process proceeds to step S35. In step S37, the variable “off start correction” is subtracted by 1%, and then the process proceeds to step S35. In this case, the reflux control time is within the second control range. In step S38, the energization-off start time T _OFS is determined as follows.
T _OFS = Energization OFF end time + max {3-phase energization time × (OFF correction), 0 s}
That is, in the third embodiment, adjustment of the energization off timing is performed based on the increase / decrease rate of the three-phase energization time.

  As described above, according to the third embodiment, when the reflux control time exceeds the first control range, the energization pattern switching unit 23 delays the end timing of the energization on period after the next time by a predetermined rate to return the reflux control time. When the control time is controlled to be within the first control range and the reflux control time is within the second control range, the end timing of the energization on period after the next time is advanced by a predetermined rate. In this case, the same effect as that of the first embodiment can be obtained.

(Fourth embodiment)
In the fourth embodiment, as shown in FIG. 13, the neutral point voltage generator 17 is omitted from the configuration shown in FIG. The terminal voltage comparator 16 is directly supplied with the neutral point voltage of the motor 14 as a threshold voltage. In the case of the fourth embodiment configured as described above, the same effect as that of the first embodiment can be obtained.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible.
In FIG. 1, each function implemented by software may be configured by hardware logic.
What is necessary is just to change suitably about the carrier period of PWM control, and the specific value of the 1st and 2nd control range according to an individual design.
It is not limited to the 120 degree energization method. For example, as shown in the second embodiment, it may be applied to a 130-degree energization method in which a three-phase energization pattern is generated from the beginning when energization switching is performed.
The present invention is not limited to the on-vehicle motor control device.
In the motor control method of claims 10 and 13 , the order of measuring the U, V, and W-phase reflux control times is not limited.

  In the drawings, 1 is a motor drive control device, 3 is an inverter circuit, 10 is an indicated rotational speed receiver, 14 is a brushless DC motor, 16 is a terminal voltage comparator, 21 is a zero cross timing signal generator, and 22 is a rotational speed measuring device. , 23 is an energization pattern switching device, 24 is a PWM duty calculator, 25 is a PWM signal generator, and 26 is a reflux control time measuring device.

Claims (15)

In a motor control device that drives and controls a brushless DC motor (14) having a three-phase configuration of U, V, and W via an inverter circuit (3),
An instruction speed receiver (10) for receiving an instruction value of the motor rotation speed inputted from the outside;
A rotational speed measuring device (22) for measuring the rotational speed of the motor;
A PWM duty calculator (24) for calculating a duty of a PWM (Pulse Width Modulation) signal from the indicated value and the rotational speed measured by the rotational speed measuring instrument;
A terminal voltage comparator (16) for comparing each phase terminal voltage of the motor with a threshold voltage corresponding to the neutral point voltage of the motor;
A zero-cross timing signal generator (21) that generates a zero-cross timing signal from the comparison result of the phase that is energized in the inverter circuit, output from the terminal voltage comparator;
An energization pattern switch (23) for outputting an energization signal so as to switch the energization pattern of each phase based on the PWM signal based on the zero cross timing signal;
A PWM signal generator (25) that generates the PWM signal based on the duty and the energization signal and outputs the PWM signal to the inverter circuit;
A reflux control time measuring device (26) for measuring a reflux control time in which a reflux current is flowing in the inverter circuit ;
The reflux control time measuring device outputs a comparison result of the phase determined by the direction of the current flowing through the motor, output from the terminal voltage comparator, starting from the timing when the energization signal indicates energization off. Is measured as the reflux control time, specifically,
In the period in which the direction of the current flows from the V phase to the W phase, or from the W phase to the V phase, the U phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the U phase. Measure and
In the period in which the direction of the current flows from the U phase to the W phase, or from the W phase to the U phase, the V phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the V phase. Measure and
In the period in which the direction of the current flows from the U phase to the V phase or from the V phase to the U phase, the W phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the W phase. Measure and
The energization pattern switcher switches from one phase on the upper arm side of the inverter circuit to a lower arm when switching an energization pattern to energize a different phase on the lower arm side from one phase on the upper arm side of the inverter circuit. A motor control device that controls to reduce the reflux control time by temporarily generating a three-phase energization pattern for energizing two phases on different sides . In the motor control device that drives and controls the brushless DC motor (14) via the inverter circuit (3),
An instruction speed receiver (10) for receiving an instruction value of the motor rotation speed inputted from the outside;
A rotational speed measuring device (22) for measuring the rotational speed of the motor;
A PWM duty calculator (24) for calculating a duty of a PWM (Pulse Width Modulation) signal from the indicated value and the rotational speed measured by the rotational speed measuring instrument;
A terminal voltage comparator (16) for comparing each phase terminal voltage of the motor with a threshold voltage corresponding to the neutral point voltage of the motor;
A zero-cross timing signal generator (21) that generates a zero-cross timing signal from the comparison result of the phase that is energized in the inverter circuit, output from the terminal voltage comparator;
An energization pattern switch (23) for outputting an energization signal so as to switch the energization pattern of each phase based on the PWM signal based on the zero cross timing signal;
A PWM signal generator (25) that generates the PWM signal based on the duty and the energization signal and outputs the PWM signal to the inverter circuit;
A reflux control time measuring device (26) for measuring a reflux control time in which a reflux current is flowing in the inverter circuit;
If the reflux control time exceeds the first control range, the energization pattern switching unit delays the end timing of the energization on period after the next time by a predetermined time, thereby causing the reflux control time to be in the first control range. Control to be inside,
When the reflux control time falls within a second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined time. Control device. In the motor control device that drives and controls the brushless DC motor (14) via the inverter circuit (3),
An instruction speed receiver (10) for receiving an instruction value of the motor rotation speed inputted from the outside;
A rotational speed measuring device (22) for measuring the rotational speed of the motor;
A PWM duty calculator (24) for calculating a duty of a PWM (Pulse Width Modulation) signal from the indicated value and the rotational speed measured by the rotational speed measuring instrument;
A terminal voltage comparator (16) for comparing each phase terminal voltage of the motor with a threshold voltage corresponding to the neutral point voltage of the motor;
A zero-cross timing signal generator (21) that generates a zero-cross timing signal from the comparison result of the phase that is energized in the inverter circuit, output from the terminal voltage comparator;
An energization pattern switch (23) for outputting an energization signal so as to switch the energization pattern of each phase based on the PWM signal based on the zero cross timing signal;
A PWM signal generator (25) that generates the PWM signal based on the duty and the energization signal and outputs the PWM signal to the inverter circuit;
A reflux control time measuring device (26) for measuring a reflux control time in which a reflux current is flowing in the inverter circuit;
When the reflux control time exceeds the first control range, the energization pattern switching unit delays the end timing of the energization on period after the next time by a predetermined ratio, thereby causing the reflux control time to be in the first control range. Control to be inside,
When the recirculation control time falls within a second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined ratio. Control device. The reflux control time measuring device outputs a comparison result of the phase determined by the direction of the current flowing through the motor, output from the terminal voltage comparator, starting from the timing when the energization signal indicates energization off. 4. The motor control device according to claim 2 , wherein a time until a state indicating is obtained is measured as the reflux control time. 5. If the motor has a three-phase configuration of U, V and W,
The reflux control time measuring device is based on a comparison result output from a terminal voltage comparator corresponding to the U phase during a period in which the direction of the current flows from the V phase to the W phase or from the W phase to the V phase. Measure the U-phase reflux control time,
In the period in which the direction of the current flows from the U phase to the W phase, or from the W phase to the U phase, the V phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the V phase. Measure and
In the period in which the direction of the current flows from the U phase to the V phase or from the V phase to the U phase, the W phase reflux control time is set based on the comparison result output from the terminal voltage comparator corresponding to the W phase. The motor control device according to claim 4 , wherein measurement is performed. The energization pattern switcher switches from one phase on the upper arm side of the inverter circuit to a lower arm when switching an energization pattern to energize a different phase on the lower arm side from one phase on the upper arm side of the inverter circuit. 6. The motor control device according to claim 5 , wherein control is performed so as to shorten the reflux control time by temporarily generating a three-phase energization pattern for energizing two phases on different sides. When the energization pattern switching unit starts measurement of the reflux control time and the next edge on the same side as the edge where the zero cross timing signal has changed is reached next time, the energization on period based on the measurement result ends. The motor control device according to any one of claims 2 to 6, wherein timing is controlled. The recirculation control time counter, when the end timing of the energization on period by the action of the energization pattern switch is delayed, claims 4, characterized in that starting from the timing of the energization off by the delay 7 The motor control device according to any one of the above. The energization pattern switching unit, of the respective switching elements constituting the inverter circuit, only for those off actually energized, the claims 2 to 8, characterized in that slowing the end timing of the energization on period The motor control apparatus as described in any one. A method for controlling a brushless DC motor having a three-phase configuration of U, V, and W via an inverter circuit,
The duty of the PWM (Pulse Width Modulation) signal is calculated from the indicated value of the motor rotational speed input from the outside and the measured rotational speed of the motor.
Each phase terminal voltage of the motor is compared with a threshold voltage corresponding to the neutral point voltage of the motor, and a zero cross timing signal is generated from the comparison result of the phase in which the energization is turned off in the inverter circuit,
Based on the zero cross timing signal, to output the energization signal to switch the energization pattern of each phase by the PWM signal,
Generate the PWM signal based on the duty and the energization signal, and output to the inverter circuit,
Starting from the timing when the energization signal indicates energization off, the return current flows through the inverter circuit until the phase comparison result determined by the direction of the current flowing through the motor shows a state where the return current disappears. When measuring as the reflux control time ,
In the period in which the direction of the current flows from the V phase to the W phase or from the W phase to the V phase, the U phase reflux control time is measured based on the comparison result corresponding to the U phase,
In the period in which the direction of the current flows from the U phase to the W phase, or from the W phase to the U phase, the V phase reflux control time is measured based on the comparison result corresponding to the V phase,
In the period in which the direction of the current flows from the U phase to the V phase, or from the V phase to the U phase, the W phase reflux control time is measured based on the comparison result corresponding to the W phase,
When switching the energization pattern for energizing one phase on the upper arm side of the inverter circuit to a different one phase on the lower arm side, energizing two phases on the lower arm side from one phase on the upper arm side of the inverter circuit A motor control method characterized in that control is performed to shorten the reflux control time by temporarily generating a three-phase energization pattern to be performed . A method of controlling a brushless DC motor via an inverter circuit,
The duty of the PWM (Pulse Width Modulation) signal is calculated from the indicated value of the motor rotational speed input from the outside and the measured rotational speed of the motor.
Each phase terminal voltage of the motor is compared with a threshold voltage corresponding to the neutral point voltage of the motor, and a zero cross timing signal is generated from the comparison result of the phase in which the energization is turned off in the inverter circuit,
Based on the zero cross timing signal, to output the energization signal to switch the energization pattern of each phase by the PWM signal,
Generate the PWM signal based on the duty and the energization signal, and output to the inverter circuit,
Starting from the timing when the energization signal indicates energization off, the return current flows through the inverter circuit until the phase comparison result determined by the direction of the current flowing through the motor shows a state where the return current disappears. When measuring as the reflux control time,
If the reflux control time exceeds the first control range, the end timing of the energization on period after the next time is controlled to be delayed by a predetermined time so that the reflux control time is within the first control range,
When the reflux control time falls within a second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined time. Control method. A method of controlling a brushless DC motor via an inverter circuit,
The duty of the PWM (Pulse Width Modulation) signal is calculated from the indicated value of the motor rotational speed input from the outside and the measured rotational speed of the motor.
Each phase terminal voltage of the motor is compared with a threshold voltage corresponding to the neutral point voltage of the motor, and a zero cross timing signal is generated from the comparison result of the phase in which the energization is turned off in the inverter circuit,
Based on the zero cross timing signal, to output the energization signal to switch the energization pattern of each phase by the PWM signal,
Generate the PWM signal based on the duty and the energization signal, and output to the inverter circuit,
Starting from the timing when the energization signal indicates energization off, the return current flows through the inverter circuit until the phase comparison result determined by the direction of the current flowing through the motor shows a state where the return current disappears. When measuring as the reflux control time,
If the recirculation control time exceeds the first control range, by controlling the end timing of the energization on period after the next time by a predetermined rate, the recirculation control time is controlled to be within the first control range,
A motor control method characterized in that, when entering a second control range set in a value range less than the first control range, the end timing of the energization on period after the next time is advanced by a predetermined ratio . The motor has a three-phase configuration of U, V, and W,
In the period in which the direction of the current flows from the V phase to the W phase or from the W phase to the V phase, the U phase reflux control time is measured based on the comparison result corresponding to the U phase,
In the period in which the direction of the current flows from the U phase to the W phase, or from the W phase to the U phase, the V phase reflux control time is measured based on the comparison result corresponding to the V phase,
The flow control time of the W phase is measured based on a comparison result corresponding to the W phase during a period in which the direction of the current flows from the U phase to the V phase or from the V phase to the U phase. Item 13. The motor control method according to Item 11 or 12 . When switching the energization pattern for energizing one phase on the upper arm side of the inverter circuit to a different one phase on the lower arm side, energizing two phases on the lower arm side from one phase on the upper arm side of the inverter circuit 14. The motor control method according to claim 13 , wherein control is performed so as to shorten the reflux control time by temporarily generating a three-phase energization pattern to be performed. When an edge on the same side as the edge at which the zero cross timing signal has changed when the measurement of the reflux control time starts next time, the end timing of the energization on period is controlled based on the measurement result. The motor control method according to any one of claims 11 to 14 .

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