JP2012010456A - Drive control apparatus for three-phase ac motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent current from being abruptly changed while performing an adequate energization control responding to requests of a phase control.SOLUTION: A motor drive control apparatus performs a drive control of a three-phase motor in a 180° energization mode to perform an advance angle control for output timing of energization pattern based on calculated phase angles φ1 and φ2. When change of the phase angle is 60° or more at phase switch timing (time t1), MOSFETs at all phases are temporarily turned off and the advance angle control for the output timing of the energization pattern is performed at the phase angle φ2 after the phase switch.

Description

  The present invention relates to a drive control device that controls the driving of a three-phase AC motor using a three-phase bridge, and more particularly to the driving of a three-phase AC motor that appropriately controls the output timing of a drive signal to each switching element of the three-phase bridge. The present invention relates to a control device.

  Conventionally, when driving a three-phase motor mounted on, for example, a motorcycle, a prior art that controls the driving using a full-wave rectification bridge circuit (three-phase bridge) is known (for example, see Patent Document 1). .)

  As shown in the above prior art (Patent Document 1), six semiconductor switching elements (FET, IGBT, thyristor, etc.) are incorporated in a bridge circuit that drives a three-phase motor. By controlling OFF by a control circuit (for example, PIC), the direct current output from the battery can be converted into a three-phase alternating current.

  When driving a three-phase motor as shown in the above prior art (Patent Document 1), the switching elements of the three-phase bridge are switched on or off in a predetermined order, and the U-phase, V-phase, and W-phase are switched. Control for supplying drive current to each coil in a predetermined order is performed. At this time, energization of the drive current is controlled in a half cycle (180 ° energization mode) for each phase, and steady motor drive is realized by repeating such energization with a phase difference of 120 °. It has become.

JP 2007-181364 A (paragraphs 0031 to 0037, FIGS. 3 and 5)

  Normally, when a three-phase motor is driven, the required torque of the motor also varies according to the variation of the load. In order to cope with such torque fluctuations, a phase control method is generally used for driving a three-phase motor. As is well known from many prior art documents, phase control is a control method that advances or retards the energization timing of the coil with respect to the position of the magnet of each phase (position as viewed relative to the coil). Generally, when the amount of advance (phase angle) increases, a larger torque can be obtained.

  However, when driving the three-phase motor in the 180 ° energization mode as described above, the energization order to each phase changes every 1/6 cycle (1/3 of a half cycle = 60 °). When the phase angle in control changes significantly (60 ° or more), the energization sequence determined in advance for each phase changes irregularly. In this case, before and after the change of the phase angle of 60 ° or more, the direction in which current flows simultaneously in specific two-phase (for example, U-phase and W-phase) coils is switched, and as a result, the current flowing in all-phase coils Is likely to fluctuate rapidly (for example, an overcurrent occurs), and control that requires a change in phase angle of 60 ° or more is extremely difficult.

  Accordingly, an object of the present invention is to provide a technique for suppressing a rapid fluctuation in current while performing appropriate energization control in response to a request in phase control.

In order to solve the above problems, the present invention employs the following solutions.
The drive control device for a three-phase AC motor of the present invention has a configuration including a driver circuit and a control circuit. Of these, the driver circuit has a function of converting the direct current output from the battery into a drive current having a three-phase waveform by a plurality of switching elements, and individually supplying the drive current to each phase of the three-phase alternating current motor. The control circuit generates a drive signal that instructs each switching element to switch to the energized state or the non-energized state at the same cycle as the three-phase waveform, and calculates the phase angle based on the phase of the three-phase AC motor. The function of controlling the output timing of the drive signal based on the above.

  In particular, when the control circuit determines that the amount of change in the output timing of the drive signal is equal to or greater than a predetermined angle from the calculation result of the phase angle, the control circuit switches all the switching elements of each phase to the non-energized state. After outputting the drive signal for instructing, the drive signal is output based on the calculation result of the phase angle.

  As described above, when the drive control device of the present invention determines that a significant phase angle change (change of a predetermined angle or more) occurs during the phase control, the drive control device does not simply change to a new phase angle as it is. Rather, the control for switching all the switching elements to the non-energized state (OFF) is executed once in advance. In this case, since the output from the driver circuit is once turned off for all phases, the drive current that temporarily flows through the windings in the three-phase AC motor is also lost accordingly. Even if the output timing of the drive signal is controlled with a new phase angle from this state, since the current flow has disappeared before that, the rapid current caused by the reversal of the current direction as described above No change (overcurrent) occurs.

  In addition, the drive control device of the present invention may further include a storage circuit that stores an energization control map that predefines the switching order of the energized state and the non-energized state of the plurality of switching elements for each phase. In this case, the control circuit inputs a position detection signal output by a position sensor corresponding to each phase winding in accordance with the rotation of the three-phase AC motor and energizes each switching element to switch to the energized state in the energization control map. The combination of patterns is defined in advance as six output stages that circulate in the order from the first to the sixth for each phase section corresponding to six equal parts of one period of each phase, and each output stage is defined based on the position detection signal. A drive signal is generated while shifting in the order of the order. In addition, when the control circuit determines that it is necessary to shift to an output stage that skips the order of the order in controlling the output timing of the drive signal based on the calculation result of the phase angle, it applies to all switching elements of each phase. On the other hand, after outputting a drive signal for instructing switching to a non-energized state, the drive signal is output by shifting to an output stage that skips the order of order.

  For example, when each phase of a three-phase AC motor is driven in the 180 ° energization mode, the output stage is changed in order by changing the energization pattern of each phase switching element for each 60 ° phase section. Become. However, even in this case, if the fluctuation range becomes 60 ° or more due to the switching of the phase angle, the transition order of the output stage becomes irregular, and the phenomenon that the direction of the current is switched simultaneously in the two phases as described above. Can occur.

  Therefore, in the present invention, when it is found that the order of transition of the output stage is irregular with respect to the phase control, the current flow is temporarily reduced by de-energizing all the phase switching elements before and after the stage transition. It is resetting. Even if the state is shifted from this state to the next output stage in an irregular order, the current flow is reset in advance, and in this case, the same result as the restart of phase control is obtained. Therefore, it is possible to prevent a phenomenon in which the directions of currents are switched at the same time in two phases, and to realize appropriate phase control.

  Alternatively, the control circuit periodically calculates the phase angle based on the position detection signal, and determines that the difference between the previous phase angle calculation result and the latest phase angle calculation result is equal to or greater than a predetermined angle. In this case, after outputting a drive signal for instructing switching to a non-energized state for all switching elements of each phase, the output timing of the drive signal is controlled based on the latest calculation result of the phase angle. Is preferred.

  If it is said aspect, it can prevent reliably that the rapid change of an electric current arises before and after the big change of a phase angle.

  According to the drive control device for a three-phase AC motor of the present invention, it is possible to cope with a large change in the phase angle that could not be practically controlled so far, and the phase angle region that cannot be handled in the phase control (control prohibition) Phase control can be realized without providing a region.

It is a figure showing roughly the composition of the motor drive control device of one embodiment. It is a timing chart showing the concept of the basic drive control of the three-phase motor by a control circuit with various state changes. It is a figure which shows the flow of the drive current at the time of performing drive control in the 1st output stage. It is a timing chart showing the concept of phase control by a control circuit together with various state changes. It is a figure which contrasts and shows the difference in the state change by the presence or absence of an output stage jump. 6 is a timing chart showing a state change when a stage jump occurs during phase control. It is a timing chart which showed the state change at the time of implementing the optimal countermeasure with respect to the phenomenon of a stage skip. It is a flowchart which shows the example of a procedure of the phase angle control process performed in a control circuit. It is a timing chart which shows the state change at the time of implementing a countermeasure as a verification example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a configuration of a motor drive control device 10 according to an embodiment. This motor drive control device 10 is for controlling the drive of a three-phase motor 12, which is a three-phase AC motor, for example. The three-phase motor 12 functions as a drive source of the power system by being mounted on a power system (not shown) such as a motorcycle.

  The three-phase motor 12 has, for example, U-phase, V-phase, and W-phase windings (motor coils, stator coils, etc.) 12u, 12v, and 12w, and also has, for example, permanent magnets (magnets) as a rotor (not shown). . Three permanent magnets are provided corresponding to the U-phase, V-phase, and W-phase windings 12u, 12v, and 12w, respectively. Further, for example, an output shaft of a three-phase motor 12 is connected to a rotor (not shown), and an output torque can be obtained by rotation of the rotor.

  The motor drive control device 10 described above mainly includes a driver circuit 20 and a control unit 30. Of these, the driver circuit 20 forms a three-phase bridge using MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz that are, for example, six switching elements.

  A battery 24 is connected to a terminal (not shown) of the driver circuit 20, and another load 26 (for example, another electric circuit) is also connected to the battery 24.

  The control unit 30 includes a control circuit 32 that is, for example, a central processing unit (CPU). The control circuit 32 (storage circuit such as a built-in ROM) stores a control program, an energization control map in which energization patterns for the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz are determined in advance, and the three-phase motor 12 The phase angle table and the like necessary for the phase control of this are stored. The control program and the energization control map will be further described later with examples.

  The control unit 30 includes an output circuit 38 and an input circuit 40 as external interfaces. The control unit 30 outputs drive signals for the respective MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz through the output circuit 38, and switches to energization (ON) or non-energization (OFF), respectively.

  Further, the torque command value Tr for the three-phase motor 12 and the voltage signal Vbatt of the battery 24 are input to the control unit 30 from the input circuit 40 as external signals. These external signals are supplied to the control unit 30 as control signals for the power system on which the three-phase motor 12 is mounted.

  In addition, the three-phase motor 12 is provided with a position sensor 42. The position sensor 42 is a magnetic sensing device using, for example, a Hall element or a magnetoresistive element. As the three-phase motor 12 rotates, the magnetic sensing device outputs position detection signals corresponding to the windings 12u, 12v, and 12w of each phase. This position detection signal is input to the control circuit 32 via the input circuit 40 of the control unit 30. The position sensor 42 may be, for example, an angle sensor provided in the rotor, but may be provided in other locations as long as it can detect a change in position of each phase accompanying the rotation of the three-phase motor 12. May be good.

[Basic control example]
FIG. 2 is a timing chart showing the concept of basic drive control of the three-phase motor 12 by the control circuit 32 together with various state changes. This will be specifically described below.

[Position sensor signal]
2A: First, the control circuit 32 acquires position sensor signals for each of the U phase, V phase, and W phase based on the position detection signal output from the position sensor 42 described above. At this time, if the rotation of the three-phase motor 12 is steady (for example, rotating in the positive direction and the rotation speed and output torque are constant), the position sensor signal is observed as an ideal three-phase rectangular wave signal as shown in the figure. can do. That is, the position sensor signals of each phase are shifted by 120 ° in the order of U phase, V phase, and W phase, and from the rising edge (upward edge) to the falling edge (downward edge) for a half cycle of each phase ( 180 °).

[Energization control map]
In FIG. 2, (B): In the control circuit 32, an energization pattern in which the order of switching each of the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz individually to ON or OFF is preliminarily defined is stored as an energization control map. Yes. The control circuit 32 determines an energization pattern corresponding to the current position information with reference to the energization control map using the rise change or fall change of the position sensor signal as a reference (interrupt trigger). In addition, due to the circuit configuration of the driver circuit 20 (three-phase bridge), the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz for each of the U-phase, V-phase, and W-phase must always be turned on when one of them is switched on. Is switched to OFF.

[Output stage]
In FIG. 2, (C): In the drive control, the above-described combination of the energization patterns is defined as “first to sixth output stages” in advance, and logic that shifts these output stages in order is employed. For example, for the section (phase 60 °) from the timing when the position sensor signal rises for the U phase to the time when the position sensor signal falls for the W phase, this is referred to as a “first output stage”. Subsequently, for a section (phase 60 °) from the timing when the position sensor signal falls for the W phase to the time when the position sensor signal rises for the V phase, this is referred to as a “second output stage”. In addition, for the section (phase 60 °) from the timing when the position sensor signal rises for the V phase to the time when the position sensor signal falls for the U phase, this is referred to as a “third output stage”. Subsequently, for a section (phase 60 °) from the timing when the position sensor signal falls for the U phase to the time when the position sensor signal rises for the W phase, this is referred to as a “fourth output stage”. Further, for a section (phase 60 °) from the timing when the position sensor signal rises for the W phase to the time when the position sensor signal falls for the V phase, this is referred to as a “fifth output stage”. Then, for the section (phase 60 °) from the timing when the position sensor signal falls for the V phase to the time when the position sensor signal rises for the U phase next, this can be set as the “sixth output stage”.

  Supplementing the description to contribute to the optimal implementation of the invention, for example, in the above “first output stage”, the MOSFETs 22Tu, 22Ty, 22Tw are ON as the energization pattern in FIG. 2B, and the MOSFETs 22Tx, 22Tv, 22Tz are A combination that is OFF is specified. In this case, the control circuit 32 generates a drive signal in a designated combination, and controls the ON or OFF state of each of the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz through the output circuit 38. The control circuit 32 generates and outputs a drive signal in a combination designated by each output stage while shifting the output stages in the first to sixth circulating orders (in order). Here, for convenience, the phase angle (advance amount) is set to 0 °.

[Drive current waveform]
In FIG. 2, (D): As a result, the energization current waveforms of the U-phase, V-phase, and W-phase in the three-phase motor 12 are observed as ideal three-phase AC waveforms.

  FIG. 3 is a diagram showing the flow of drive current when drive control is performed in the first output stage. In this case, in the driver circuit 20, the MOSFETs 22Tu, 22Ty, and 22Tw are turned on, and the MOSFETs 22Tx, 22Tv, and 22Tz are turned off, so that a driving current is passed and torque is generated in the three-phase motor 12. Although not particularly shown, drive currents are also generated in the other second to sixth stages according to the respective energization patterns.

[Phase control example]
Next, FIG. 4 is a timing chart showing the concept of phase control by the control circuit 32 together with various state changes. In the phase control, the control circuit 32 mainly calculates the phase angle based on the rise or fall of the position sensor signal, and the output timing of the drive signal to the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, 22Tz based on the calculation result. Is to control.

[Advance command value]
In FIG. 4, (A): For example, the control circuit 32 determines the advance angle command value in accordance with the change in the required torque Tr for the three-phase motor 12. At this time, the control circuit 32 controls the output timing of the drive signal at the phase angle φ1 (for example, 15 °) corresponding to the current advance angle command value.

[Output stage transition timing]
In FIG. 4, (B) and (C): The output timing in this case is set to a timing advanced (forward) by the phase angle φ1 from the rising edge of the position sensor signal for the U phase, for example. Is done. In this case, the control circuit 32 generates and outputs a drive signal in a combination designated by each output stage while shifting the output stage (for example, shifting from sixth to first) at a timing advanced by the phase angle φ1.

[Voltage waveform of each phase]
In FIG. 4, (D): As a result, the voltage waveforms of the U-phase, V-phase, and W-phase in the three-phase motor 12 are observed in a state advanced by a phase angle φ1 from the position sensor signal.

[Phase switching]
Up to this point, the description has been made before the advance angle command value (phase angle φ1) changes. However, when the advance angle command value changes with a certain width, the following phenomenon occurs.

[After time t1]
In FIG. 4, (A): It is assumed that a new advance angle command value is determined at a certain time t0 and the new advance angle command value is reflected at a certain time t1. In this case, for example, the control circuit 32 controls the output timing of the drive signal at the phase angle φ2 (for example, 135 °) corresponding to the new advance command value with the next V-phase falling edge as a reference.

[Occurrence of missing stage]
4B and 4C: The output timing in this case is set to a timing advanced by a phase angle φ2 from the rising edge (0 °) of the position sensor signal for the V phase, for example. Is done. In this case, for example, the control circuit 32 shifts the output stage at a timing advanced by the phase angle φ2 with respect to the rising edge of the next V phase, for example. At this time, the change from the previous phase angle φ1 to the current phase angle φ2 The width is one stage (60 °) or more. Therefore, here, a jump occurs in the order of transition of the output stages, and two stages (120 °) are skipped from the sixth output stage so far, and the transition to the third output stage is made. As a result, an omission (here, omission of the first and second output stages) has occurred with respect to the transition of the output stage.

[Voltage waveform of each phase]
In FIG. 4, (D): The voltage waveforms of the U phase, V phase, and W phase in the three-phase motor 12 are advanced by a phase angle φ2 from the position sensor signal by a new advance command value. . However, two output stages (6th to 3rd) flew at this time, resulting in an irregular change in voltage waveform in which a U-phase rise, a V-phase rise, and a W-phase fall occur simultaneously. Become.

[Differences in state changes depending on whether or not stage jumps]
FIG. 5 is a diagram showing the difference in the state change depending on the presence or absence of the output stage jump as described above. Hereinafter, each will be described in comparison.

[When there is no stage skipping (missing)]
In FIG. 5, (A): This shows the flow of drive current when the sixth output stage shifts in order from the first output stage. As indicated by thin arrows in the figure, during the sixth output stage, MOSFETs 22Tx, 22Ty, and 22Tw are turned on in the driver circuit 20, and MOSFETs 22Tu, 22Tv, and 22Tz are turned off, so that the drive current is reduced. Generate torque in the sink motor.

[Transition from 6th to 1st]
When the sixth output stage shifts in order from the first output stage, the U-phase MOSFET 22Tu is turned on and the MOSFET 22Tx is turned off, as indicated by the thick arrows in the figure, Only the direction of the phase current switches.

[If there is a stage jump (missing)]
In FIG. 5, (B): On the other hand, the flow of the drive current when the first output stage is skipped from the sixth output stage to the second output stage (the first output stage is missing) is as follows. . First, as indicated by thin arrows in the figure, during the sixth output stage, MOSFETs 22Tx, 22Ty, 22Tw are turned on and MOSFETs 22Tu, 22Tv, 22Tz are turned off in the driver circuit 20.

[Transition from 6th to 2nd]
When the sixth output stage jumps to the second output stage, the U-phase MOSFET 22Tu is ON, the MOSFET 22Tx is OFF, the W-phase MOSFET 22Tw is OFF, and the MOSFET 22Tz, as indicated by the thick arrows in the figure. When is turned ON, the directions of currents in the U phase and the W phase change together.

[Verification when stage jump occurs]
FIG. 6 is a timing chart showing a state change when a stage jump occurs during phase control. As a result of actual verification by the inventors of the present invention, the following phenomenon was observed by causing a stage jump during phase control.

  6A and 6B: Here, voltage waveforms of the U phase, the V phase, and the W phase before and after the stage jump are shown, and the state change is shown in FIG. ) And (C). That is, two output stages (from 6 to 3) flew, so that the rising of the U-phase, the rising of the V-phase, This is an irregular change in which the W phase falls simultaneously.

[Current waveform of each phase]
In FIG. 6, (C): At this time, sudden changes in current occur in all phases of the U-phase, V-phase, and W-phase, as indicated by the long and short dashed circles shown in the figure. Yes. According to the verification conducted by the inventors of the present invention, it has been found that such a sudden change in current can occur when the direction of current changes simultaneously in two or more phases in the three-phase motor 12. . Such a sudden change in current may reach a level that greatly exceeds the rated current of the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz, and may seriously damage the device.

〔counter-measure〕
The inventors of the present invention provide the following method as an optimal countermeasure for the above phenomenon. FIG. 7 is a timing chart showing a state change when an optimum countermeasure for the stage jump phenomenon is implemented.

  7A: When a new advance command value is determined at a certain time t0 and the new advance command value is reflected at the time t1 in the same manner as shown in FIG. 4A. Is assumed.

  FIG. 7B: In this case as well, the output timing of the drive signal is set to a timing advanced by a phase angle φ2 from the rising edge (0 °) of the position sensor signal for the V phase. . In this case, the control circuit 32 shifts the output stage at a timing advanced by the phase angle φ2, but at this time, the change width from the previous phase angle φ1 to the current phase angle φ2 is one stage (60 °) or more. It is known that the above stage jump occurs.

  In this countermeasure, when the control circuit 32 determines that the stage jump occurs when the phase angle φ1 is changed to the next phase angle φ2 by the new advance angle command value, the MOSFETs 22Tu, 22Tv, An OFF command for 22Tw, 22Tx, 22Ty, and 22Tz is output. Thereafter, based on the phase angle φ2 corresponding to the new advance command value, the control circuit 32 skips two stages (120 °) from the previous sixth output stage and shifts to the third output stage.

  (C) in FIG. 7: As a result, the U-phase, the V-phase, the W-phase, before the transition from the sixth output stage to the third output stage, as surrounded by the long and short dashed circles shown in the figure. The voltage waveform is turned off in all phases, and sudden changes in current do not occur in all phases of the U phase, V phase, and W phase.

[Mode of stage transition]
(D) in FIG. 7: Regarding the transition of the output stage, although the loss (missing of the first and second output stages) occurs as in FIG. 6B, the sixth output stage and the third output stage It can be seen that an all-phase OFF period is provided between the two.

  FIG. 8 is a flowchart illustrating a procedure example of the phase angle control process executed in the control circuit 32. Through this processing, the control circuit 32 can suitably realize the above countermeasure. The control circuit 32 generates an interrupt trigger based on the rising edge or the falling edge of the position sensor signal, and periodically executes this phase angle control process.

  Step S100: First, the control circuit 32 (CPU) acquires various parameters necessary for calculating the phase angle. In this example, the torque command value Tr is acquired as a parameter.

  Step S102: Next, the control circuit 32 calculates the current phase angle φn. This calculation can be performed, for example, using a phase angle control map stored in the control circuit 32 in advance. The phase angle control map, for example, takes a parameter such as a torque command value Tr as an argument and returns a corresponding phase angle value.

  Step S104: The control circuit 32 obtains a difference (| Δφ |) between the phase angle φn−1 calculated at the time of the previous processing execution and the phase angle φn calculated this time. It is assumed that the previous phase angle φn−1 is stored in the buffer area of the RAM of the control circuit 32, for example. In addition, the control circuit 32 newly stores the phase angle φn that is the current calculation result in the buffer area of the RAM of the control circuit 32. As a result, since the previous phase angle φn−1 is rewritten by the current calculation result, the value obtained this time can be used as the previous phase angle φn−1 in the subsequent processing (at the time of the next interruption). .

  Step S106: The control circuit 32 compares the difference (| Δφ |) obtained in the previous step S104 with a predetermined phase angle φs (60 °). As a result, when it is determined that the phase angle difference (| Δφ |) is equal to or larger than the predetermined phase angle φs (Yes), the control circuit 32 next executes step S108.

  Steps S108 and S110: In this case, at the time t0, the control circuit 32 generates an OFF command (a drive signal for instructing OFF) for the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz. The generated drive signal is output OFF at time t1.

  When the procedure so far is completed, the control circuit 32 once returns to the process before the interruption. Then, when the phase angle control process is started at the next interrupt timing (when the timer corresponding to the phase angle φn is interrupted), the control circuit 32 executes steps S100 to S104 described above again.

  Steps S104 and S106: When the difference (| Δφ |) between the current phase angle φn and the previous phase angle φn−1 eventually becomes less than φs, the control circuit 32 next executes step S112.

  Step S112: The control circuit 32 sets the current phase angle φn as a phase angle to be actually output. Specifically, the energization pattern and advance time calculated from the phase angle φn are stored in the buffer area of the RAM. Here, the advance time is the time from t1 to outputting the energization pattern.

  Step S110: The control circuit 32 outputs the energization pattern calculated at time t0 after time t1 + advance time. As a result, at the current interruption, the MOSFETs 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, and 22Tz of each phase are switched ON or OFF according to the respective energization patterns at the output stage advanced to the latest phase angle φn. The drive control of the three-phase motor 12 is executed. Thereby, the output torque corresponding to the torque command value Tr of the system is exhibited from the three-phase motor 12.

[Example of countermeasure verification]
FIG. 9 is a timing chart showing a state change when the above countermeasure is implemented as a verification example.

  In FIG. 9, (A), (B): Here, the voltage waveforms of the U phase, V phase, and W phase before and after the stage jump when the countermeasure is implemented are shown. This is the same as that shown in (C) and (D) of FIG. That is, the voltage waveform is OFF in all phases of the U phase, the V phase, and the W phase before the transition from the sixth output stage to the third output stage (phase switching point).

[Current waveform of each phase]
In FIG. 9, (C): When all phases are turned off from the phase switching timing (time t1), a sudden change in current does not occur in all phases of the U phase, the V phase, and the W phase. Thereafter, when the phase control is executed by jumping to the third output stage at the next interruption (time t2), the MOSFETs 22Tu, 22Tv, and 22Tz in the three-phase motor 12 are turned on. This creates a state where no current flows, so there is no sudden change in current.

  According to the motor drive control device 10 of the above-described embodiment, the phase control can be safely realized even with respect to a change in the phase angle, which has been practically difficult until now. Thereby, control is enabled without providing an uncontrollable area (control prohibited area) on the logic. Thereby, the control efficiency of the three-phase motor 12 can be greatly improved, which can greatly contribute to improving the followability to the required torque and the torque performance.

  The present invention is not limited to the embodiments described above, and can be implemented with various modifications. In one embodiment, the concept of “output stage” is used for phase control. However, this concept is not particularly necessary for implementing the present invention. That is, when the control circuit 32 senses that the phase angle is about to change at a predetermined angle (60 °) or more, a control logic that turns off all-phase MOSFETs once may be employed.

  In addition, the phase angle change (15 ° → 135 °) described in the embodiment is merely an example, and the control method of the embodiment can be applied to other changes of 60 ° or more.

  In one embodiment, a transition example from the sixth output stage to the third output stage is given as an example of stage jumping, but between other stages (for example, first → third, second → fourth, etc.). Needless to say, the method of the embodiment can be applied even when stage skipping (missing) occurs.

DESCRIPTION OF SYMBOLS 10 Motor drive control apparatus 12 Three-phase motor 12u, 12v, 12w Winding 20 Driver circuit 22Tu, 22Tv, 22Tw, 22Tx, 22Ty, 22Tz MOSFET
24 battery 30 control unit 32 control circuit 38 output circuit 40 input circuit 42 position sensor

Claims (3)

A driver circuit that converts the direct current output from the battery into a drive current having a three-phase waveform with a plurality of switching elements and supplies the drive current to each phase winding of the three-phase AC motor;
Based on the phase angle calculated based on the phase of the three-phase AC motor, while generating a drive signal instructing switching to the energized state or the non-energized state for each switching element at the same cycle as the three-phase waveform And a control circuit for controlling the output timing of the drive signal,
The control circuit includes:
In order to instruct all the switching elements of each phase to be switched to a non-energized state when it is determined from the phase angle calculation result that the amount of change in the output timing of the drive signal is equal to or greater than a predetermined angle. After the output of the drive signal, the drive signal is output based on the calculation result of the phase angle. In the drive control apparatus of the three-phase AC motor according to claim 1,
A storage circuit that stores an energization control map that predefines the switching order of the energized state and non-energized state of the plurality of switching elements for each phase;
The control circuit includes:
A combination of energization patterns in which position detection signals output by position sensors corresponding to the windings of the respective phases are input as the three-phase AC motor rotates, and each switching element is switched to an energized state in the energization control map. Are defined in advance as six output stages that circulate in a first to sixth order for each phase section corresponding to six equal parts of one period of each phase, and each output stage is defined based on the position detection signal. While generating the drive signal while shifting in the order of the order,
When controlling the output timing of the drive signal based on the calculation result of the phase angle, if it is determined that it is necessary to shift to the output stage that exceeds the order of the order, all the switching elements of the respective phases Output the drive signal for instructing to switch to the non-energized state, and then output the drive signal by shifting to the output stage that skipped the order of the order. Electric motor drive control device. In the drive control apparatus of the three-phase AC motor according to claim 2,
The control circuit includes:
When the phase angle is calculated periodically based on the position detection signal, and it is determined that the difference between the previous calculation result of the phase angle and the latest calculation result of the phase angle is a predetermined angle or more, After outputting the drive signal for instructing switching to the non-energized state for all the switching elements of each phase, the output timing of the drive signal is controlled based on the latest phase angle calculation result A drive control device for a three-phase AC motor, characterized in that.