Motor drive control device and motor drive control method

Abstract

The present invention provides a motor drive control device that can reliably avoid false detection of zero-crossings used for current switching due to spikes and ringing appearing in the voltage waveform of induced voltage and reference voltage, regardless of the motor load. [Solution] The system comprises a control circuit (1) that generates a drive control signal (Sd) for driving a motor (3) having at least one phase of coils, a drive circuit (2), and a phase voltage detection circuit. The control circuit, after switching the energized phase to the coil, detects the occurrence and resolution of inductive kickback occurring in the unenergized phase of the coil, and then masks zero-cross detection for a first predetermined time after detecting the resolution of the inductive kickback.

Description

Technical Field

[0001] The present invention relates to a motor drive control device and a method for driving and controlling a motor.

Background Art

[0002] When a three-phase BLDC (brushless dc motor) is driven by a sensorless 120-degree rectangular wave, energization is applied to the windings in the energized phases of the PWM (Pulse Width Modulation) drive phase and the GND (ground) phase, and commutation is performed by utilizing the zero-cross detection timing of the differential voltage between the induced voltage that appears in the non-energized phase and the reference voltage that is either the neutral point voltage or half of the power supply voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a three-phase BLDC motor is driven by a sensorless 120-degree rectangular wave, the induced voltage and the reference voltage are branched from the windings and the power supply input through wiring, and input to a measurement circuit composed of a comparator or an A / D converter via a resistance voltage dividing circuit and a delay circuit that limit the voltage range respectively, for zero-cross detection.

[0005] In such a circuit configuration, when the energizing pattern is sequentially switched and the motor is driven by energizing switching using zero-cross detection, it is known that spikes and ringing occur in the voltage waveforms of the induced voltage and reference voltage due to square wave switching. These spikes and ringing may be mistakenly detected as zero-crossings used for energizing switching. If spikes and ringing generated in the induced voltage and reference voltage are mistakenly detected as zero-crossings used for energizing switching, the energizing switch will occur earlier than intended, which can have adverse effects such as unstable motor speed and increased motor speed, causing the power consumption per rotational speed to deviate from the optimal state.

[0006] In conventional methods, in addition to a delay circuit in the measurement path, a configuration is provided in the measurement circuit that allows setting the mask time starting from the FET switching as the zero-cross detection time, thereby avoiding false detection of spikes and ringing as zero-crosses used for power switching.

[0007] By setting a mask time to start from the switching of this FET, it becomes possible to prevent false detection of spikes or ringing caused by FET switching depending on the motor's driving conditions as zero-crossings used for power switching.

[0008] Despite these workarounds, when using high-voltage, multi-pole motors for drones and driving them with high rotation, high output, and high load using the aforementioned power switching method, the power switching can cause inductive kickback (flyback pulse) to occur and persist for a long period. This can result in spikes and ringing in the voltage waveforms of the induced voltage and reference voltage due to the resolution of the inductive kickback, which may be mistakenly detected as zero-crossings used for power switching.

[0009] For example, in Patent Document 1, immediately after switching the energized stator winding, The description states that position detection is performed via a position detection mask time setting unit that starts position detection after a predetermined period of time, known as a position detection mask time (zero-crossing non-detection time), has elapsed during which fluctuations in the induced voltage are not detected. In this method, the description states that the position detection mask time is changed according to the motor's operating current, applied voltage, or rotational speed, either individually or in combination therefrom, to enable accurate position detection from low-speed to high-speed rotation.

[0010] However, the method described in Patent Document 1 assumes and sets the duration of inductive kickback based solely on estimations of the motor load. Therefore, there is a risk of discrepancies in the zero-crossing caused by spikes appearing in the voltage waveform of the induced voltage and reference voltage that actually occur, and in that case, the problem of false detection of the zero-crossing remains unresolved. Furthermore, in the case of energization switching at high rotation, high output, and high load, it is not possible to address false detection of the zero-crossing used for energization switching due to spikes or ringing that occur when inductive kickback is resolved.

[0011] For these reasons, there is a need for a motor drive control device that can reliably avoid false detection of zero-crossings used for current switching due to spikes and ringing appearing in the voltage waveform of induced voltage and reference voltage, even when driven at high rotation speeds, high output, and high load.

[0012] The present invention aims to solve the above-mentioned problems and to provide a motor drive control device that can reliably avoid erroneous detection of zero-crossings used for current switching due to spikes and ringing appearing in the voltage waveform of induced voltage and reference voltage, regardless of the motor load. [Means for solving the problem]

[0013] A motor drive control device according to a typical embodiment of the present invention includes: a control circuit that generates a drive control signal for driving a motor having at least one phase of coils; an inverter circuit that includes switches connected in series to each other and provided corresponding to the coils of each phase of the motor, and rotates the rotor of the motor by turning the switches on and off in accordance with the drive control signal to energize the coils of the corresponding phases and switching the energized phases at predetermined timings; and a phase voltage detection circuit for detecting the phase voltage generated between the inverter circuit and the coils of each phase of the motor, wherein the control circuit uses a differential voltage detection signal to determine the differential voltage between the induced voltage generated in the coil of the non-energized phase and a reference voltage based on the detected phase voltage of each phase. The control circuit comprises a differential voltage detection circuit that outputs a signal, and a PWM signal generation unit that generates a drive control signal, which is a rectangular wave signal that switches the energizing phase to the coil and switches the inverter circuit on and off to switch the energizing state of the coil that has become energized, based on zero-crossing detection using the differential voltage detection signal. The control circuit is characterized in that, after switching the energizing phase to the coil, when it detects the occurrence and resolution of inductive kickback occurring in the coil that has become unenergized, it masks the zero-crossing detection for a first predetermined time after detecting the resolution of the inductive kickback, and also masks the zero-crossing detection for a second predetermined time at the rising and falling timings of the rectangular wave signal. [Effects of the Invention]

[0014] According to one aspect of the present invention, the motor drive control device can reliably avoid erroneous detection of zero-crossings used for current switching due to spikes and ringing appearing in the voltage waveform of the induced voltage or reference voltage, regardless of the motor load. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows the configuration of a motor unit 100 equipped with a motor drive control device 10 according to an embodiment. [Figure 2]It is a diagram showing the functional block configuration of the control circuit 1 in the motor drive control device 10 according to the embodiment. [Figure 3] It is a diagram showing a configuration example of the differential voltage detection circuit 15. [Figure 4] It is a diagram showing a timing chart for explaining the detection of zero cross in one rotation of the motor (electrical angle 360 degrees) of the motor drive control device 10 according to the embodiment. [Figure 5] It is a diagram for explaining the respective timings of the PWM drive mask (synthesis), the PWM energization off mask, and the kickback cancellation mask according to the embodiment. [Figure 6] It is a diagram for explaining the respective timings of the PWM drive mask (synthesis), the PWM energization off mask, and the kickback cancellation mask according to the embodiment. [Figure 7] It is a diagram for explaining the respective timings of the PWM drive mask (synthesis), the PWM energization off mask, and the kickback cancellation mask according to the embodiment. [Figure 8] It is a diagram for explaining the respective timings of the PWM drive mask (synthesis), the PWM energization off mask, and the kickback cancellation mask according to the embodiment. [Figure 9] It is a diagram showing a flowchart of an example of the processing flow in mask processing in the PWM mask (integration) by the second mask time (PWM drive mask) and the mask time of the energization off period of the energization phase (PWM energization off mask). [Figure 10] It is a diagram for explaining the timing of the PWM mask (integration) including the PWM drive mask and the PWM energization off mask in one cycle of the PWM drive. [Figure 11] It is a diagram showing a flowchart of an example of the processing flow when executing mask processing at the first mask time (kickback cancellation mask) in the LO side energization switching. [Figure 12] It is a diagram showing a flowchart of an example of the processing flow when executing mask processing at the first mask time (kickback cancellation mask) in the HI side energization switching.

Best Mode for Carrying Out the Invention

[0016] 1. Overview of Embodiment First, an overview of typical embodiments of the invention disclosed in the present application will be described. In the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are described with parentheses.

[0017] 〔1〕A motor drive control device (10) according to a typical embodiment of the present invention includes a control circuit (1) that generates a drive control signal (Sd) for driving a motor (3) having at least one-phase coil, and an inverter circuit (2a) including switches connected in series with each other provided corresponding to the coils of each phase of the motor. The drive circuit (2) turns on and off the switches according to the drive control signal to energize the corresponding phase coil and rotates the rotor of the motor by switching the energized phase at a predetermined timing. The drive circuit (2) also includes a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coils of each phase of the motor. The control circuit includes a differential voltage detection circuit (15) that outputs, as a differential voltage detection signal (Vd), a differential voltage between an induced voltage generated in the non-energized phase coil based on the detected phase voltage of each phase and a reference voltage, and a PWM signal generation unit (14) that generates the drive control signal, which is a rectangular wave signal, for turning on and off the switches of the inverter circuit so as to switch the energized phase to the coil and switch the energization state of the coil that has become the energized phase based on zero-cross detection using the differential voltage detection signal. The control circuit masks zero-cross detection for a first predetermined time after detecting the occurrence and elimination of inductive kickback generated in the coil that has become the non-energized phase after switching the energized phase to the coil, and masks zero-cross detection for a second predetermined time at the rising and falling timings of the rectangular wave signal.

[0018] 〔2〕In the motor drive control device described in 〔1〕 above, the switch of the inverter circuit The circuit includes high-side switches (Q1, Q3, Q5) and low-side switches (Q2, Q4, Q6), and the PWM signal generation unit drives the motor by generating the drive control signals that turn on and off the high-side switches and low-side switches of the inverter circuit that energizes the coil, and the control circuit may mask the zero-cross detection for a second predetermined time at the on / off timing of the switch that is the PWM drive phase of the energized phase among the high-side switches and low-side switches of the inverter circuit.

[0019] [3] In the motor drive control device described in [1] above, the control circuit may, after the execution of the PWM drive masking process that masks the zero-crossing detection for the second predetermined time has been completed, execute the kickback elimination masking process that masks the zero-crossing detection for the first predetermined time.

[0020] [4] In the motor drive control device described in [2] above, the switch of the inverter circuit includes a high-side switch and a low-side switch, the PWM signal generation unit drives the motor by generating the drive control signal that turns on and off the switch of the inverter circuit that energizes the coil, and the control circuit may mask the zero-cross detection over the period of the power-off period, which is the period during which the switch of the energized phase PWM drive phase is turned off.

[0021] [5] In the motor drive control device described in [1] above, the control circuit may further detect the occurrence and resolution of inductive kickback occurring in the coil that has become the unenergized phase after switching the energizing phase to the coil, and when the power supply side of the energized phase is switched by HI side energizing switch, the detection direction of the differential voltage detection signal fluctuation when inductive kickback occurs is changed from positive to negative, and when inductive kickback is resolved, the detection direction of the differential voltage detection signal fluctuation is changed from negative to positive, and when the GND side of the energized phase is switched by LO side energizing switch, the detection direction of the differential voltage detection signal fluctuation when inductive kickback occurs is changed from negative to positive, and when inductive kickback is resolved, the detection direction of the differential voltage detection signal fluctuation is changed from positive to negative, thereby switching the zero-cross detection mode based on the differential voltage detection signal according to the mode of energizing switch.

[0022] [6] In the motor drive control device described in [1] above, the control circuit may detect the occurrence of inductive kickback when it detects the first zero crossing within the time it takes to complete one cycle of PWM drive after switching the energizing phase to the coil.

[0023] [7] A motor drive control method according to a typical embodiment of the present invention is a motor drive control device (10) that is executed in a motor drive control device (10) which includes a control circuit (1) that generates a drive control signal (Sd) for driving a motor (3) having at least one phase of coils, an inverter circuit (2a) including switches connected in series with each other and provided corresponding to the coils of each phase of the motor, and a drive circuit (2) that turns the switches on and off in accordance with the drive control signal to energize the coil of the corresponding phase and switches the energized phase at a predetermined timing to rotate the rotor of the motor, and a phase voltage detection circuit for detecting the phase voltage generated between the inverter circuit and the coils of each phase of the motor. The process includes: a first step of outputting a differential voltage detection signal (Vd) as a differential voltage detection signal (Vd) between the induced voltage generated in the coil of the non-energized phase and a reference voltage based on the phase voltage of each phase detected; a second step of performing zero-crossing detection based on the differential voltage detection signal; a third step of generating a drive control signal, which is a square wave signal, that switches the energized phase to the coil and switches the inverter circuit on and off to switch the energized state of the coil that has become energized, based on the zero-crossing detection; a fourth step of detecting the occurrence and resolution of inductive kickback that occurs in the coil that has become non-energized after switching the energized phase to the coil; and a first predetermined step after detecting the resolution of the inductive kickback. The method is characterized by comprising a fourth step of masking the zero-crossing detection over a period of time, and masking the zero-crossing detection for a second predetermined period of time during the rising and falling edges of the square wave signal.

[0024] 2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the figures. In the following description, common components in each embodiment will be denoted by the same reference numerals, and repeated descriptions will be omitted.

[0025] <Embodiment> Figure 1 shows the configuration of a motor unit 100 equipped with a motor drive control device 10 according to an embodiment.

[0026] As shown in Figure 1, the motor unit 100 comprises a motor 3 and a motor drive control device 10 that controls the rotation of the motor 3. The motor unit 100 can be applied to various devices that use a motor as a power source, such as fans and drones (unmanned aerial vehicles).

[0027] Motor 3 is, for example, a permanent magnet synchronous motor (PMSM). In this embodiment, motor 3 is, for example, a surface magnet synchronous motor (SPMSM) having three phase coils (windings) Lu, Lv, and Lw. The coils Lu, Lv, and Lw are, for example, connected to each other in a Y (star) configuration. In this case, the coils may also be connected to each other in a Δ (delta) configuration.

[0028] The motor drive control device 10 rotates the rotor of the motor 3 by periodically supplying drive current to the three-phase coils Lu, Lv, and Lw of the motor 3, for example, by providing the motor 3 with a 120-degree energized square wave drive signal.

[0029] The motor drive control device 10 includes a control circuit 1 and a drive circuit 2.

[0030] Note that the components of the motor drive control device 10 shown in Figure 1 are only a part of the whole, and the motor drive control device 10 may have other components in addition to those shown in Figure 1.

[0031] The drive circuit 2 drives the motor 3 based on the drive control signal Sd output from the control circuit 1, which will be described later. The drive circuit 2 includes, for example, an inverter circuit 2a and a pre-drive circuit 2b. The inverter circuit 2a of the drive circuit 2 is positioned between the DC power supply Vin and the ground potential.

[0032] The inverter circuit 2a is a circuit that drives the coils Lu, Lv, and Lw of the motor 3, which is a load, based on the drive control signal Sd output from the control circuit 1 and input via the pre-drive circuit 2b. Specifically, in this embodiment, the inverter circuit 2a has three switching legs, each containing two drive transistors connected in series, and drives the motor 3, which is a load, by having the two drive transistors alternately turn on and off (switching operation) based on the input drive control signal Sd.

[0033] More specifically, the inverter circuit 2a has switching legs corresponding to the U-phase, V-phase, and W-phase of the motor 3, respectively. As shown in Figure 1, each switching leg corresponding to a phase has two drive transistors (hereinafter also referred to as "switching elements") Q1 and Q2, Q3 and Q4, and Q5 and Q6 connected in series between the DC power supply Vin and the ground potential.

[0034] Here, the drive transistors Q1, Q3, and Q5 (corresponding to the high-side switches) for the upper arm of the motor 3 coil are, for example, N-channel MOSFETs, and the drive transistors Q2, Q4, and Q6 (corresponding to the low-side switches) for the lower arm of the motor 3 coil are, for example, N-channel MOSFETs. Note that the drive transistors Q1 to Q6 may be other types of FETs, for example, IGBTs (Insulated Gate FETs). Other types of transistors, such as bipolar transistors, may also be used.

[0035] For example, the switching leg corresponding to the U phase has switching elements Q1 and Q2 connected in series with each other. The point where switching elements Q1 and Q2 are commonly connected is connected to one end of the coil Lu, which is the load. The switching leg corresponding to the V phase has switching elements Q3 and Q4 connected in series with each other. The point where switching elements Q3 and Q4 are commonly connected is connected to one end of the coil Lv, which is the load. The switching leg corresponding to the W phase has switching elements Q5 and Q6 connected in series with each other. The point where switching elements Q5 and Q6 are commonly connected is connected to one end of the coil Lw, which is the load. In addition, switching elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 each have parasitic diode characteristics from the GND side to the power supply side (not shown in Figure 1).

[0036] The pre-drive circuit 2b generates a drive signal to drive the inverter circuit 2a based on the drive control signal Sd output from the control circuit 1.

[0037] The drive control signal Sd is a signal for controlling the drive of motor 3, and is a square wave signal, such as a PWM (Pulse Width Modulation) signal. Specifically, the drive control signal Sd is a signal for switching the energization pattern of the motor 3's coils Lu, Lv, and Lw, which is determined by the on / off state of each switching element constituting the inverter circuit 2a. More specifically, the drive control signal Sd includes six types of PWM signals corresponding to each switching element Q1 to Q6 of the inverter circuit 2a.

[0038] The pre-drive circuit 2b generates six types of drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl, which are capable of supplying sufficient power to drive the control electrodes (gate electrodes) of each switching element Q1 to Q6 of the inverter circuit 2a, based on six types of PWM signals (square wave signals) supplied from the control circuit 1 as drive control signals Sd.

[0039] These drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl are input to the control electrodes (gate electrodes) of each switching element Q1 to Q6 in the inverter circuit 2a, causing each switching element Q1 to Q6 to perform an on / off operation (switching operation). For example, the switching elements Q1, Q3, and Q5 on the upper arm and the switching elements Q2, Q4, and Q6 on the lower arm of the switching leg corresponding to each phase alternately perform on / off operations. As a result, power is supplied to each phase of the motor 3 from the DC power supply Vin, causing the motor 3 to rotate.

[0040] Between the inverter circuit 2a and the coils Lu, Lv, Lw of each phase of the motor 3, wiring for measuring the phase voltage signals Vu, Vv, Vw generated in each phase (hereinafter also referred to as the "phase voltage detection circuit") is connected and input to the control circuit 1. In the control circuit 1, when zero-crossing is detected as described later, the differential voltage measured based on the phase voltage signals Vu, Vv, Vw generated in each phase (the differential voltage between the induced voltage, which is the phase voltage of one phase selected as a non-energized phase, and a reference voltage that is the neutral point voltage or half of the power supply voltage: a value corresponding to the phase voltage of the selected phase) is used. In other words, zero-crossing can be detected by detecting when the differential voltage signal Vd, which is the differential voltage between the induced voltage and the reference voltage, becomes 0.

[0041] In driving the motor, the control circuit 1 generates a drive control signal Sd to drive the motor 3 based on a speed command signal Sc, which is input from an external source and specifies the target operating state of the motor 3, and controls the driving of the motor 3. Specifically, the control circuit 1 generates a drive control signal Sd so that the motor 3 is in the operating state specified by the speed command signal Sc, and provides it to the drive circuit 2. At this time, the control circuit 1 uses the differential voltage measured based on the phase voltage signals Vu, Vv, Vw to detect a zero crossing used for power switching, and generates a drive control signal Sd that switches the power supply phase of the motor 3 at an appropriate timing.

[0042] In this embodiment, the control circuit 1 is a program processing unit (e.g., a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), A / D conversion circuit, D / A conversion circuit, clock generation circuit, and input / output I / F circuit are connected to each other via a bus or dedicated line. The control circuit 1 may also include a differential voltage detection circuit 15 configured as an analog circuit, as will be described later.

[0043] The motor drive control device 10 may be configured such that at least a part of the control circuit 1 and at least a part of the drive circuit 2 are packaged as a single integrated circuit (IC), or the control circuit 1 and the drive circuit 2 may be configured such that they are each packaged as separate integrated circuit devices.

[0044] Figure 2 is a diagram showing the functional block configuration of the control circuit 1 in the motor drive control device 10 according to the embodiment.

[0045] As shown in Figure 2, the control circuit 1 includes, for example, a drive command acquisition unit 11, a state control unit 12, a square wave control unit 13, a PWM signal generation unit 14, and a differential voltage detection circuit 15 as functional blocks for generating a drive control signal Sd when driving a motor using a 120-degree energized square wave drive method. Furthermore, the state control unit 12 includes a zero-cross detection signal generation unit 121, an inductive kickback detection unit 122, and an inductive kickback mask processing unit 123 as functional blocks that output a zero-cross detection signal Zo to the square wave control unit 13 only at the necessary timing, as will be described later.

[0046] These functional blocks are realized, for example, in a program processing unit as a control circuit 1, by the processor executing various arithmetic operations according to a program stored in memory, and controlling peripheral circuits such as counters and A / D conversion circuits.

[0047] The drive command acquisition unit 11 receives a speed command signal Sc from an external source and analyzes the received speed command signal Sc to obtain a value that specifies the target operating state of the motor 3 specified by the speed command signal Sc.

[0048] The speed command signal Sc includes a value that indicates the target state of operation for the motor 3. The speed command signal Sc is, for example, a signal output from a higher-level device for controlling the motor unit 100, which is located outside the motor drive control device 10.

[0049] In this embodiment, the speed command signal Sc specifies, for example, the rotational speed of the rotor of motor 3. The speed command signal Sc includes the value ωref of the target rotational speed (target rotational speed) of the rotor of motor 3.

[0050] The speed command signal Sc is, for example, a PWM signal having a duty cycle corresponding to the specified target rotational speed ωref. The drive command acquisition unit 11 receives, for example, the PWM signal of the speed command signal Sc. The duty cycle is measured, and the rotational speed corresponding to the measured duty cycle is output as the target rotational speed ωref.

[0051] The state control unit 12 outputs the target rotational speed ωref directly to the square wave control unit 13 when driving the motor, and also outputs a zero-crossing detection signal Zo, generated based on the differential voltage detection signal Vd output from the differential voltage detection circuit 15 (described later), to the square wave control unit 13 as needed. The differential voltage detection signal Vd is a signal obtained by comparing the fluctuation of the induced voltage generated in the non-energized phase coil based on the phase voltage of each phase of the coil with a reference voltage.

[0052] The state control unit 12 outputs a zero-crossing detection signal Zo, which can be detected based on the differential voltage detection signal Vd, to the square wave control unit 13 only at the necessary timings. This prevents the output of the zero-crossing detection signal Zo when spikes or ringing occur. This configuration avoids the output of a zero-crossing detection signal Zo, which mistakenly detects spikes or ringing as zero-crossings, to the square wave control unit 13. The functional unit that performs this processing will be described later.

[0053] The rectangular wave control unit 13 outputs a drive command signal So to the PWM signal generation unit 14 and a measurement phase selection signal Sm to the differential voltage detection circuit 15 when driving the motor. The measurement phase selection signal Sm is a signal used to select the phase to be detected by the differential voltage detection circuit 15 from among the phases of the motor coil. The rectangular wave control unit 13 can select the non-energized phase as the detection target for the differential voltage detection circuit 15.

[0054] The rectangular wave control unit 13 is configured to output a measurement phase selection signal Sm corresponding to the non-energized phase to the differential voltage detection circuit 15 in order to acquire the switching timing of the six energization patterns in the 120-degree rectangular wave drive control method for driving the motor. The differential voltage detection circuit 15 is configured to generate a differential voltage detection signal Vd obtained by comparing the induced voltage of the selected non-energized phase with the neutral point voltage (an example of a reference voltage).

[0055] The square wave control unit 13 controls the motor drive by generating a drive command signal So from the target rotational speed ωref and the zero-crossing detection signal Zo input from the state control unit 12, according to a drive control method using a 120-degree square wave, and outputting it to the PWM signal generation unit 14. The zero-crossing detection signal Zo is a signal that indicates the detection timing of the zero-crossing used for power switching, which is generated by the state control unit 12.

[0056] The square wave control unit 13, for example, energizes the windings from the U phase to the V phase by single-phase excitation, and causes the differential voltage detection circuit 15 to measure the differential voltage between the induced voltage (phase voltage) generated in the non-energized W phase and the neutral point voltage (reference voltage), thereby generating a differential voltage detection signal Vd. Based on the generated differential voltage detection signal Vd, the square wave control unit 13 controls the motor by outputting a drive command signal So to the PWM signal generation unit 14, which is adjusted to switch the energization using the zero-crossing detection signal Zo generated by the state control unit 12 to indicate the zero-crossing detection timing. At this time, the neutral point voltage used as the reference voltage may be a DC power supply Vin / 2 instead of a voltage obtained by combining the phase voltages of all phases. The square wave control unit 13 may also have a PWM period timer Tpwm for adjusting the switching timing of the drive signal of the PWM drive phase, and an energization switching timer Tsector for adjusting the energization switching timing.

[0057] The Tsector power switching timer is a timer that resets each time the power is switched. Since the power switching occurs in a time interval of 60 degrees of electrical angle, and the time from power switching to zero-cross detection is 30 degrees of electrical angle, it is used to measure the time from power switching to zero-cross detection and the power phase switching time from zero-cross detection to the next power switching. If the power switching is performed after waiting for a time of 30 degrees of electrical angle, it may be delayed from the optimal power switching timing for the rotor. Therefore, the advance time corresponding to the rotational speed may be subtracted from the power phase switching time of 30 degrees of electrical angle, and the power switching may be performed. In addition, the power switching timer Tsector may be used to measure the time between the previous zero crossing and the current zero crossing. That is, it may be used to measure the time between zero crossing detections. Although not specifically shown in Figure 2, the square wave control unit 13 may further have a function unit that performs such processing. The square wave control unit 13 also outputs the drive command signal So to the state control unit 12 in order to perform the mask processing described later.

[0058] In motor driving, the PWM signal generation unit 14 generates a drive control signal Sd in response to the drive command signal So received from the rectangular wave control unit 13 and outputs it to the drive circuit 2, thereby controlling the drive circuit 2 with PWM.

[0059] The differential voltage detection circuit 15 is configured to output the phase voltage of the selected phase as a differential voltage detection signal Vd to the zero-crossing detection signal generation unit 121.

[0060] Figure 3 shows an example configuration of the differential voltage detection circuit 15. The example configuration of the differential voltage detection circuit 15 will now be explained.

[0061] The differential voltage detection circuit 15 receives the phase voltage signals Vu, Vv, Vw for each phase and the measurement phase selection signal Sm as inputs, and outputs a differential voltage detection signal Vd. The differential voltage detection circuit 15 consists of multiple resistor elements 151 for DC current limiting and voltage adjustment, a measurement phase selection multiplexer (MUX) 152, and a differential amplifier circuit 153. The differential voltage detection circuit 15 splits the input of the phase voltage signals Vu, Vv, Vw for each phase into two, combines one of the branches to form a combined signal (neutral point voltage) Vn which is input to the differential amplifier circuit 153, and inputs the other to the measurement phase selection multiplexer 152. The differential amplifier circuit 153 also receives the output from the measurement phase selection multiplexer 152. At this time, the resistor elements 151 are set so that the voltage division ratio of each phase voltage and the voltage division ratio of the neutral point voltage are the same ratio. Furthermore, if a delay circuit is included, the time constants of each phase voltage and the neutral point voltage should be set to the same value.

[0062] In the differential voltage detection circuit 15, the measurement phase selection multiplexer 152 selects one of the three phase voltage signals Vu, Vv, and Vw according to the measurement phase selection signal Sm input from the square wave control unit 13 and outputs it to the differential amplifier circuit 153 as a selected phase voltage signal Vm. The differential amplifier circuit 153 receives a voltage corresponding to the phase voltage of the selected phase and a composite signal Vn of the three phase voltage signals Vu, Vv, and Vw, which correspond to the neutral point voltage of the motor coil. In other words, the differential amplifier circuit 153 receives a signal corresponding to the differential voltage detection signal Vd'. The differential voltage detection signal Vd', generated from the selected phase voltage signal Vm and the neutral point voltage Vn, has both positive and negative polarity when driving the motor. Therefore, the differential amplifier circuit 153 performs signal expansion and contraction (amplification and reduction) and shifts the DC power supply Vdc / 2, resulting in the output of a differential voltage detection signal Vd that is approximately similar to the differential voltage detection signal Vd' and saturated in the voltage range from 0V to Vdc centered on Vdc / 2. In other words, the differential voltage detection signal Vd is a signal corresponding to the phase voltage of the selected phase.

[0063] Figure 4 is a timing chart illustrating the detection of zero-crossing in the motor drive control device 10 according to the embodiment.

[0064] Figure 4 shows, from top to bottom, the waveforms of the drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl generated in the pre-drive circuit 2b in correspondence with the drive control signal Sd generated by the PWM signal generation unit 14 of the control circuit 1, in terms of electrical angle and current flow pattern. Below these, the phase voltage signals generated in each phase of the motor 3's coils Lu, Lv, and Lw are shown. The waveform of the current phase and the waveform of half the power supply voltage as a reference voltage are shown. The waveforms of the phase voltage signals shown in this figure are not actually measured in the motor drive control device 10 according to this embodiment shown in Figures 1 and 2, but are theoretically occurring phase voltages. In other words, this timing chart shows the relationship between the phase voltage signals Vu, Vv, Vw theoretically occurring in each phase Lu, Lv, Lw of the motor 3 coil when the drive signals Vuh, Vul, Vvh, Vvl, Vwl of each phase are switched based on the drive control signal Sd, and the phase voltage signals Vu, Vv, Vw theoretically occurring in each phase Lu, Lv, Lw of the motor 3 coil.

[0065] In Figure 4, each energization pattern at 60-degree electrical angles is counted by the energization switching timer Tsector. The drive signal generated in the pre-drive circuit 2b is controlled by the PWM period timer Tpwm, which is counted at each PWM period in the square wave control unit 13, using center-aligned PWM drive, and is driven with a PWM period Tperiod and a duty cycle Tduty. In this case, the duty cycle of the drive signal is Tduty / Tperiod. Note that in Figure 4, half of the power supply voltage is used as the reference voltage. When using the neutral point voltage obtained by combining the voltages of each phase as the reference voltage, the neutral point voltage fluctuates due to the on / off switching of the energized phases caused by the on / off switching of the PWM drive phase, and therefore the reference voltage also fluctuates. However, the reference voltage at zero-crossing when the power is on is the same value as the neutral point voltage and half of the power supply voltage.

[0066] Control circuit 1 generates a drive control signal Sd while switching the energizing phase based on the zero-crossing of the differential voltage signal Vd, which is the differential voltage between the induced voltage and the reference voltage. Specifically, control circuit 1 generates a drive control signal Sd adjusted to energize from coil Lu to coil Lv between electrical angles of 0 to 60 degrees, and then switches the energizing phase at electrical angle 60 degrees (LO side energizing switch) to generate a drive control signal Sd adjusted to energize from coil Lu to coil Lw between electrical angles of 60 to 120 degrees.

[0067] At this timing, as shown in Figure 4, the drive signals Vuh and Vul switch complementaryly, while between electrical angles of 0 to 60 degrees, the drive signal Vvl becomes high, and then between electrical angles of 60 to 120 degrees, the drive signal Vwl becomes high. In this case, between electrical angles of 0 to 60 degrees, the W phase is the unenergized phase, and between electrical angles of 60 to 120 degrees, the V phase is the unenergized phase.

[0068] Next, control circuit 1 switches the energized phase at an electrical angle of 120 degrees (HI-side energization switching), and generates a drive control signal Sd adjusted to energize from coil Lv to coil Lw between an electrical angle of 120 to 180 degrees. Then, it switches the energized phase at an electrical angle of 180 degrees (LO-side energization switching), and generates a drive control signal Sd adjusted to energize from coil Lv to coil Lu between an electrical angle of 180 to 240 degrees. HI-side energization switching is an energization switch that switches the power supply side of the energized phase, and LO-side energization switching is an energization switch that switches the GND side of the energized phase.

[0069] At this timing, as shown in Figure 4, the drive signals Vvh and Vvl switch complementaryly, while between electrical angles of 120 to 180 degrees, the drive signal Vwl becomes high, and then between electrical angles of 180 to 240 degrees, the drive signal Vul becomes high. In this case, between electrical angles of 120 to 180 degrees, the U phase is the unenergized phase, and between electrical angles of 180 to 240 degrees, the W phase is the unenergized phase.

[0070] Furthermore, the control circuit 1 switches the energizing phase at an electrical angle of 240 degrees (HI-side energizing switch), and generates a drive control signal Sd adjusted to energize from coil Lw to coil Lu between an electrical angle of 240 to 300 degrees. It then switches the energizing phase at an electrical angle of 300 degrees (LO-side energizing switch), and generates a drive control signal Sd adjusted to energize from coil Lw to coil Lv between an electrical angle of 300 to 360 degrees.

[0071] At this timing, as shown in Figure 4, the drive signals Vwh and Vwl switch complementaryly, while between electrical angles of 240 to 300 degrees, the drive signal Vul becomes high, and then between electrical angles of 300 to 360 degrees, the drive signal Vvl becomes high. In this case, between electrical angles of 240 to 300 degrees, the V phase is the unenergized phase, and between electrical angles of 300 to 360 degrees, the U phase is the unenergized phase.

[0072] Next, control circuit 1 switches the energized phase at an electrical angle of 360 degrees (HI side energization switch) and returns to the original electrical angle.

[0073] In this way, the control circuit 1 drives the motor so that the motor rotor rotates over an electrical angle of 360 degrees by generating a drive control signal Sd while switching the energizing phase.

[0074] As shown in Figure 4, when the motor 3 rotates in response to the drive control signal Sd generated by the PWM signal generation unit 14 of the control circuit 1, the phase voltage signal of the energized phase is either the power supply voltage or zero, but the phase voltage signal of the unenerged phase gradually fluctuates as the motor rotates. This is because an induced voltage is generated in the unenerged phase that fluctuates depending on the rotational position of the motor rotor, and the induced voltage of the unenerged phase indicates the rotational position of the motor 3's rotor. As is clear from Figure 4, when the rotor of the motor 3 is rotating ideally, the induced voltage of the unenerged phase coincides with the reference voltage at a predetermined timing. Therefore, by detecting the timing when the differential voltage between this induced voltage of the unenerged phase and the reference voltage becomes zero as a zero crossing, and using the detection timing of the zero crossing to switch the energized phase of the motor, the rotor of the motor 3 can rotate ideally. On the other hand, if inductive kickback occurs or is resolved, or if spikes or ringing are mistakenly detected as zero-crossings used for power switching, the drive control signal Sd may be output to switch power earlier than intended. This could lead to unstable motor speed, increased motor speed, and a deviation from the optimal power consumption per rotational speed.

[0075] In the motor drive control device 10 of this embodiment, the zero-crossing detection signal Zo is output to the square wave control unit 13 only at the necessary timing by mask processing, thereby avoiding situations that would adversely affect the motor drive.

[0076] Figures 5 to 8 are timing charts illustrating the timing of the kickback elimination mask according to the embodiment. Figures 5 and 6 show examples where the time from the onset to the elimination of inductive kickback is relatively short due to low load, while Figures 7 and 8 show examples where the time from the onset to the elimination of inductive kickback is relatively long due to high load. Inductive kickback is a spike-like rise or fall in induced voltage that occurs in the non-energized phase when the energized phase is switched.

[0077] Figures 5 to 8 show, from top to bottom, the waveforms of the HI-side drive signal of the PWM drive phase in the power switching timer Tsector and PWM period timer Tpwm, the waveform of the LO-side drive signal of the PWM drive phase, the waveform of the LO-side drive signal of the GND phase, the waveform of the phase voltage signal of the induced voltage phase, the PWM drive masks (composite) Tpwm_mask_f, Tpwm_mask_r, PWM power-off masks Tde_mask_f, Tde_mask_r, kickback elimination mask Tkb_end_mask, zero-crossing detection signal Zo, and zero-crossing detection mode, which will be described later. The HI-side and LO-side of the PWM drive phase (power-on phase) are the same phase and are switched complementaryly in this example. The PWM drive mask (composite) and PWM power-off mask are shown separately for the first and second halves of the center-aligned PWM.

[0078] In Figures 5 to 8, the drive signals for the HI and LO sides of the PWM drive phase, which is the power supply side of the energized phase, are switched complementaryly, and the drive signal for the LO side of the GND phase, which is the GND side of the energized phase, The current is high. Figures 5 and 7 show examples where the energized phase is switched by switching the GND phase, which is the GND side of the energized phase (LO side energization switch), and Figures 6 and 8 show examples where the energized phase is switched by switching the PWM drive phase, which is the power supply side of the energized phase (HI side energization switch). As with Figure 4, half of the power supply voltage is used as the reference voltage in Figures 5 to 8.

[0079] As shown in Figures 5 and 7, when the energized phase is switched by switching the GND phase, which is the GND side of the energized phase (LO side energization switch), inductive kickback occurs in the direction of the power supply. After the inductive kickback is resolved, an induced voltage appears and gradually increases. As shown in Figures 6 and 8, when the energized phase is switched by switching the PWM drive phase, which is the power supply side of the energized phase (HI side energization switch), inductive kickback occurs in the direction of GND. After the inductive kickback is resolved, an induced voltage appears and gradually decreases.

[0080] In all the figures, inductive kickback occurs in the non-energized phase immediately after the energized phase is switched. Regardless of the length of time from the onset to the resolution of the inductive kickback, it can be seen that spikes and ringing occur in the non-energized phase for a while after the inductive kickback has resolved. Furthermore, it can be seen that spikes and ringing occur each time the drive signal of the PWM drive phase of the energized phase is switched.

[0081] Conventional zero-cross detection mask time masks the generation of the zero-cross detection signal Zo each time the drive signal of the energized PWM drive phase is switched. The time during which this masking is performed in accordance with the drive signal of the energized PWM drive phase is called the second mask time (PWM drive mask). This configuration avoids the misdetection of spikes and ringings that occur when the switch is turned on and off due to the switching of the drive signal of the energized PWM drive phase as zero-crosses that are used for energization switching.

[0082] In the control circuit 1 of the motor drive control device 10 of this embodiment, in addition to the second mask time, the state control unit 12 further masks the generation of the zero-cross detection signal Zo for a while after the inductive kickback has been resolved. The time during which this masking is performed as the inductive kickback is resolved is called the first mask time (kickback resolution mask). This configuration prevents the detection of spikes or ringing that occur as a result of the resolution of inductive kickback that is not synchronized with the drive signal of the PWM drive phase as zero-crosses that are mistakenly used for power switching. The first mask time (kickback resolution mask) is the section indicated by the shaded area in Figures 5 to 8.

[0083] Thus, in the control circuit 1 of the motor drive control device 10 of this embodiment, masking is performed over both the first mask time and the second mask time, so that the zero-crossing detection signal Zo is output to the square wave control unit 13 only at the necessary timing.

[0084] In the control circuit 1 of the motor drive control device 10 of this embodiment, the occurrence and resolution of inductive kickback are detected based on the differential voltage detection signal Vd generated from the induced voltage of the non-energized phase, so inductive kickback can be detected with high accuracy.

[0085] Here, the configuration of a functional unit in the state control unit 12 that outputs a zero-crossing detection signal Zo to the square wave control unit 13 only at the necessary timing will be described. This functional unit is realized by a zero-crossing detection signal generation unit 121, an inductive kickback detection unit 122, and an inductive kickback mask processing unit 123.

[0086] The zero-crossing detection signal generation unit 121 generates a zero-crossing detection signal Zo indicating that a zero-crossing has been detected based on the differential voltage detection signal Vd. The device receives a differential voltage detection signal Vd, detects when the differential voltage detection signal Vd reaches a predetermined value in a predetermined fluctuation detection direction, and generates a zero-cross detection signal Zo. The predetermined value is, for example, "zero (0)".

[0087] The zero-crossing detection signal generation unit 121 may detect fluctuations in the differential voltage detection signal Vd using the differential voltage detection signal Vd as a digital signal, and detect a zero-crossing when the value of the differential voltage detection signal Vd becomes "zero". Alternatively, it may be configured to determine a zero-crossing by comparing the differential voltage detection signal Vd as an analog signal with a voltage value corresponding to a zero-crossing using a comparator. Furthermore, it may be configured to determine a zero-crossing by comparing the differential voltage detection signal Vd as an analog signal with a voltage value corresponding to a zero-crossing using an A / D converter, or by comparing the voltage values ​​obtained by quantifying the induced voltage, which is the selected phase voltage signal Vm, with the neutral point voltage Vn, to determine a zero-crossing.

[0088] The zero-crossing detection signal generation unit 121 masks the generation of the zero-crossing detection signal Zo for a second predetermined time period at the rising and falling timings of the square wave signal generated by the drive command signal So input from the square wave control unit 13 to the state control unit 12. The second predetermined time period is set to be sufficient time for spikes and ringing that occur in conjunction with the switching of the PWM signal to stop.

[0089] The zero-crossing detection signal generation unit 121 has a PWM-driven mask timer that measures the second mask time (PWM-driven mask) in order to determine whether or not to perform mask processing during the second mask time (PWM-driven mask). The zero-crossing detection signal generation unit 121 performs mask processing and does not generate the zero-crossing detection signal Zo while the time measured by the PWM-driven mask timer corresponds to the second mask time. On the other hand, the zero-crossing detection signal generation unit 121 generates the zero-crossing detection signal Zo without performing mask processing when the time measured by the PWM-driven mask timer is not the time corresponding to the second mask time. In addition to the second mask time (PWM-driven mask), the zero-crossing detection signal generation unit 121 may also perform mask processing during the mask time of the power-off period of the energized phase when the HI side of the PWM-driven phase is low (PWM power-off mask) using a PWM-driven mask timer, as described later.

[0090] The zero-crossing detection signal generation unit 121 performs masking during a second masking period, thereby masking the generation of the zero-crossing detection signal Zo for a second predetermined period of time at the on / off timing of the PWM drive phase switch in the energized phase among the high-side and low-side switches of the inverter circuit 2a.

[0091] The zero-cross detection signal generation unit 121 generates a zero-cross detection signal Zo with a delay if a zero-cross occurs during the masking period due to the PWM drive mask or PWM power-off mask, and the mask is released after the masking period has elapsed, and the zero-cross state is maintained (the differential voltage signal Vd, which indicates the differential voltage between the induced voltage and the reference voltage, temporarily becomes zero, and then the state after the polarity of the differential voltage signal Vd changes is maintained). On the other hand, if a zero-cross that occurred during the masking period is resolved, and the mask is released after the masking period has elapsed, and the zero-cross state is released (the differential voltage signal Vd, which indicates the differential voltage between the induced voltage and the reference voltage, temporarily becomes zero, and then returns to the state before the polarity of the differential voltage signal Vd changed), the zero-cross detection signal Zo is not generated, and the zero-cross detection signal Zo is not generated.

[0092] The inductive kickback detection unit 122 monitors the zero-cross detection signal Zo input from the zero-cross detection signal generation unit 121 to detect and resolve inductive kickback that occurs in the coil after the energized phase has been switched and the coil is in the non-energized phase, and to use the zero-cross detection signal Zo to switch the energized phase. The system determines the presence of inductive kickback and notifies the inductive kickback mask processing unit 123 of the timing of the zero-crossing used for detecting and eliminating inductive kickback and switching the power supply.

[0093] The inductive kickback detection unit 122 monitors the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121 to determine the occurrence and resolution of inductive kickback and the zero-cross used for power switching. The inductive kickback detection unit 122 monitors the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121 and determines the occurrence and resolution of inductive kickback and the zero-cross used for power switching according to the generation order of the zero-cross detection signal Zo from the power switching.

[0094] The zero-crossing detection signal generation unit 121 switches the fluctuation detection direction (comparator detection direction) of the differential voltage detection signal Vd from negative to positive or from positive to negative, depending on whether it detects the occurrence or elimination of inductive kickback in the energizing pattern. For example, as shown in Figures 5 and 7, when the energizing phase is switched by switching the GND phase, which is the GND side of the energizing phase (LO side energizing switch), the fluctuation detection direction of the differential voltage detection signal Vd when inductive kickback occurs is from negative to positive, and when inductive kickback is eliminated, the fluctuation detection direction of the differential voltage detection signal Vd is from positive to negative. On the other hand, as shown in Figures 6 and 8, when the energizing phase is switched by switching the PWM drive phase, which is the power supply side of the energizing phase (HI side energizing switch), the fluctuation detection direction of the differential voltage detection signal Vd when inductive kickback occurs is from positive to negative, and when inductive kickback is eliminated, the fluctuation detection direction of the differential voltage detection signal Vd is from negative to positive. The zero-crossing detection signal generation unit 121 sequentially generates zero-crossing detection signals Zo due to kickback occurrence and kickback cessation by switching the direction of fluctuation detection.

[0095] The inductive kickback detection unit 122 detects the occurrence and resolution of inductive kickback, and then detects zero-crossings used for power switching by switching the fluctuation detection direction (comparator detection direction) of the differential voltage detection signal Vd from negative to positive, or from positive to negative. For example, as shown in Figures 5 and 7, when the power supply phase is switched by switching the GND phase, which is the GND side of the power supply phase (LO side power supply switching), the fluctuation detection direction of the differential voltage detection signal Vd is switched from negative to positive to detect zero-crossings used for power switching. On the other hand, as shown in Figures 6 and 8, when the power supply phase is switched by switching the PWM drive phase, which is the power supply side of the power supply phase (HI side power supply switching), the fluctuation detection direction of the differential voltage detection signal Vd is switched from positive to negative to detect zero-crossings used for power switching. The zero-crossing detection signal generation unit 121 sequentially generates zero-crossing detection signals Zo by detecting zero-crossings used for power switching after kickback occurrence and resolution by switching the fluctuation detection direction.

[0096] The inductive kickback detection unit 122 cancels the output of the zero-cross detection signal Zo to the square wave control unit 13 if it determines that either kickback has occurred or has been resolved, as shown by the dotted line in the timing chart showing the zero-cross detection signal Zo in Figures 5 to 8. Note that the output of the zero-cross detection signal Zo due to zero-cross detection used for power switching is not affected by the cancellation process.

[0097] The state control unit 12 sets multiple zero-cross detection modes when detecting a zero-cross used for kickback occurrence, kickback resolution, and power supply switching. The multiple zero-cross detection modes include, for example, a kickback zero-cross detection mode, a kickback start mode, a kickback end mode, and a post-zero-cross detection mode. The kickback zero-cross detection mode is set when a zero-cross used for power supply switching is detected due to power supply switching, the kickback start mode is set when the resolution of inductive kickback is detected, and the resolution of inductive kickback is detected, and the kickback end mode is set when a zero-cross used for power supply switching is detected due to the resolution of inductive kickback, and the post-zero-cross detection mode The mode is set by the detection of a zero crossing before the next power switch. If inductive kickback occurs, the kickback / zero crossing detection mode, kickback start mode, kickback end mode, and post-zero crossing detection mode are set in sequence. If inductive kickback does not occur, or if the duration of inductive kickback is extremely short, the post-zero crossing detection mode is set after the kickback / zero crossing detection mode.

[0098] Furthermore, the state control unit 12 utilizes a timer (power switching timer) that measures the time since the power switching of the square wave control unit 13. For zero crossings detected by the zero crossing detection signal generation unit 121 and determined by the inductive kickback detection unit 122, the state control unit 12 measures the detection time from the power switching for each of the zero crossings used for kickback occurrence, kickback resolution, and power switching.

[0099] During power switching, inductive kickback may not occur under low load conditions, or the time from when inductive kickback occurs until it resolves may be extremely short, making it impossible to detect the zero-crossing caused by inductive kickback. In this case, without detecting the zero-crossing caused by inductive kickback, the zero-crossing of the induced voltage and reference voltage used for power switching occurs within a certain time range, centered around an electrical angle of 30 degrees, from the previous power switching, depending on the motor's characteristics. Since both the zero-crossing caused by inductive kickback and the zero-crossing used for power switching have the same direction of change in the sign of the differential voltage between the induced voltage and the reference voltage, it is important to distinguish between them.

[0100] On the other hand, if the time from the occurrence of inductive kickback to its resolution is sufficiently long, a zero-cross due to inductive kickback will occur immediately after the power switch. In this case, zero-crosses that occur during the masking period by the PWM drive mask or PWM power-off mask are detected (with a delay from the actual occurrence of the zero-cross) because the zero-cross state is maintained when the mask is released after the masking period has elapsed. Therefore, although the start timing of the PWM cycle is not synchronized with the power switch for zero-crosses due to inductive kickback, there is a period between the power switch and one cycle of PWM drive that is not masked by the PWM drive mask or PWM power-off mask, so it can be detected within the elapsed time from the power switch to one cycle of PWM drive.

[0101] In either of these cases, the zero-crossing caused by inductive kickback and the zero-crossing used for power switching can be determined not by the direction in which the sign of the differential voltage between the induced voltage and the reference voltage changes, but by using the elapsed time from the previous power switching to the occurrence of the first zero-crossing.

[0102] When the state control unit 12 is set to kickback zero-cross detection mode, the inductive kickback detection unit 122 detects the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121 and performs a kickback zero-cross determination process. That is, based on the detection timing of the zero-cross detection signal Zo in kickback zero-cross detection mode, the inductive kickback detection unit 122 performs a determination process to determine whether the detected zero-cross is due to a kickback or a zero-cross used for power switching.

[0103] Specifically, the inductive kickback detection unit 122 performs a kickback / zero-cross determination process that determines that a kickback has occurred if the detection timing of the zero-cross detection signal Zo is within a specified time since the power-on switch, and determines that the zero-cross used for power-on switching is a zero-cross if the detection timing of the zero-cross detection signal Zo is not within a specified time since the power-on switch.

[0104] If the inductive kickback detection unit 122 determines that a kickback has occurred, it performs a kickback occurrence detection process. Specifically, the inductive kickback detection unit 122 switches the state control unit 12 to kickback start mode and notifies the inductive kickback mask processing unit 123 of the occurrence of an inductive kickback.

[0105] When the state control unit 12 is set to kickback start mode, the inductive kickback detection unit 122 detects the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121, determines that the kickback has been resolved, and performs kickback resolution detection processing. That is, the inductive kickback detection unit 122 switches the state control unit 12 to kickback end mode and notifies the inductive kickback mask processing unit 123 that the inductive kickback has been resolved.

[0106] The inductive kickback detection unit 122 performs a zero-cross detection process when the state control unit 12 is set to kickback zero-cross detection mode and the kickback zero-cross determination process determines that a zero-cross is for power switching, or when it detects a zero-cross detection signal Zo when it is set to kickback termination mode. In other words, the inductive kickback detection unit 122 transitions the state control unit 12 to the post-zero-cross detection mode and notifies the inductive kickback mask processing unit 123 of the detection of a zero-cross used for power switching.

[0107] As described above, when the state control unit 12 is set to kickback zero-cross detection mode or kickback start mode, the inductive kickback detection unit 122 detects the occurrence and resolution of inductive kickback by detecting the zero-cross detection signal Zo, and notifies the inductive kickback mask processing unit 123 of the timing of the zero-cross used for the detection of the occurrence and resolution of inductive kickback and for switching the power supply.

[0108] The inductive kickback mask processing unit 123, after the state control unit 12 has transitioned to kickback termination mode, processes a new zero-cross detection signal Zo as a zero-cross used for power switching, and performs a process to mask the output of the zero-cross detection signal Zo for a predetermined period of time. The process of masking the output of the zero-cross detection signal Zo is any process that prevents the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121, which is caused by spikes or ringing resulting from the elimination of inductive kickback, from being output to the square wave control unit 13.

[0109] The inductive kickback mask processing unit 123 masks the output of the zero-cross detection signal Zo for a first predetermined time after the inductive kickback detection unit 122 detects the elimination of inductive kickback. The first predetermined time is set to be a sufficient time for ringing that occurs after the elimination of inductive kickback to stop. The first predetermined time and the second predetermined time are of the same length, but they may be independently defined times.

[0110] The inductive kickback mask processing unit 123 has a kickback elimination mask timer to determine whether or not to perform mask processing during a first mask time (kickback elimination mask). The kickback elimination mask timer measures the first mask time when it receives notification of the elimination of inductive kickback detected by the inductive kickback detection unit 122. The inductive kickback mask processing unit 123 performs mask processing for the duration that the time measured by the kickback elimination mask timer corresponds to the first mask time, and does not output the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121 to the square wave control unit 13. On the other hand, the inductive kickback mask processing unit 123 does not perform mask processing for any duration other than that that corresponds to the first mask time, and outputs the zero-cross detection signal Zo generated by the zero-cross detection signal generation unit 121 to the square wave control unit 13.

[0111] In Figure 5, the occurrence of inductive kickback during LO-side energization switching is indicated by the first "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. This zero-crossing is masked by a PWM mask (integrated: a combination of a PWM drive mask (combined) and a PWM energization off mask), which prevents the generation of the zero-crossing detection signal Zo. In this case, the zero-crossing detection signal Zo is generated at a delayed timing after the mask is removed when the induced voltage becomes greater than the reference voltage, and is used by the inductive kickback detection unit 122 to detect the occurrence of kickback.

[0112] The elimination of inductive kickback is indicated by a second "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. At this timing, a zero-crossing detection signal Zo is generated and used by the inductive kickback detection unit 122 to detect the elimination of kickback.

[0113] The zero-cross used for power switching occurs when the PWM mask (integrated) is off, and a zero-cross detection signal Zo is generated at the timing indicated by the white + mark due to the zero-crossing of the induced voltage and the reference voltage. This signal is also used for zero-cross detection in the inductive kickback detection unit 122 for power switching.

[0114] In Figure 6, the occurrence of inductive kickback during HI-side energization switching is indicated by the first "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. At this timing, a zero-crossing detection signal Zo is generated and used by the inductive kickback detection unit 122 to detect the occurrence of kickback.

[0115] The elimination of inductive kickback is indicated by a second "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. This zero-crossing is masked by a PWM mask (integration), which prevents the generation of the zero-crossing detection signal Zo. When the induced voltage becomes greater than the reference voltage, the zero-crossing detection signal Zo is generated at a delayed timing after the mask is released and is used in the inductive kickback detection unit 122 to detect the elimination of kickback. Therefore, the start of the kickback elimination mask is delayed.

[0116] The zero-cross used for power switching is masked by the PWM mask (integration), and since the PWM mask (integration) is off, the induced voltage becomes smaller than the reference voltage, causing the zero-cross detection signal Zo to be generated at a delayed timing indicated by the white + mark. The generated zero-cross detection signal Zo is then used for zero-cross detection in the inductive kickback detection unit 122 for power switching.

[0117] In Figure 7, the occurrence of inductive kickback during LO-side energization switching is indicated by the first "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. This zero-crossing is masked by a PWM mask (integration), which prevents the generation of the zero-crossing detection signal Zo. When the induced voltage becomes greater than the reference voltage, the zero-crossing detection signal Zo is generated at a delayed timing after the mask is removed and is used by the inductive kickback detection unit 122 to detect the occurrence of kickback.

[0118] The elimination of inductive kickback is indicated by a second "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. At this timing, a zero-crossing detection signal Zo is generated and used by the inductive kickback detection unit 122 to detect the elimination of kickback.

[0119] A zero-cross, indicated by a white "X," occurs when the induced voltage is greater than the reference voltage. However, the output of the zero-cross detection signal Zo is masked by the kickback mask.

[0120] The zero-cross used for power switching occurs when the PWM mask (integrated) is off, and a zero-cross detection signal Zo is generated at the timing indicated by the white + mark due to the zero-crossing of the induced voltage and the reference voltage. This signal is also used for zero-cross detection in the inductive kickback detection unit 122 for power switching.

[0121] In Figure 8, the occurrence of inductive kickback during HI-side energization switching is indicated by the first "x" mark resulting from the zero-crossing of the electromotive force and the reference voltage. At this timing, a zero-crossing detection signal Zo is generated and used by the inductive kickback detection unit 122 to detect the occurrence of kickback.

[0122] The elimination of inductive kickback is indicated by a second "x" mark resulting from the zero-crossing of the induced voltage and the reference voltage. This zero-crossing is masked by a PWM mask (integration), which prevents the generation of the zero-crossing detection signal Zo. When the induced voltage becomes greater than the reference voltage, the zero-crossing detection signal Zo is generated at a delayed timing after the mask is released and is used in the inductive kickback detection unit 122 to detect the elimination of kickback. Therefore, the start of the kickback elimination mask is delayed.

[0123] A zero-cross, indicated by a white "X," occurs when the induced voltage is lower than the reference voltage. However, the output of the zero-cross detection signal Zo is masked by the kickback mask.

[0124] The zero-cross used for power switching occurs when the PWM mask (integrated) is off and the induced voltage is lower than the reference voltage. This generates a zero-cross detection signal Zo at a delayed timing indicated by the white + mark, and the generated zero-cross detection signal Zo is used for zero-cross detection in the inductive kickback detection unit 122 for power switching.

[0125] Next, the operation of the mask processing associated with square wave switching by the control circuit 1 of the motor drive control device 10 according to the embodiment will be described.

[0126] First, we will explain the processing flow during masking in a PWM mask (integrated) that includes the second mask time (PWM drive mask) and the mask time for the power-off period of the energized phase (PWM power-off mask).

[0127] In this example, instead of using a PWM period timer Tpwm to measure the mask period for the second mask period (PWM drive mask) and the mask period for the power-off period of the energized phase (PWM power-off mask), a PWM mask timer Toffset,Twindow is used to measure the mask period for the PWM mask (integrated) period which includes the second mask period (PWM drive mask) and the mask period for the power-off period of the energized phase (PWM power-off mask). The PWM mask timer is provided by the zero-cross detection signal generation unit 121.

[0128] Figure 9 is a flowchart illustrating an example of the processing flow during masking in a PWM mask (integrated) that includes a second mask time (PWM drive mask) and a mask time for the power-off period of the energized phase (PWM power-off mask). Figure 10 is a diagram illustrating the timing of a PWM mask (integrated) that includes a PWM drive mask and a PWM power-off mask.

[0129] Figure 10 shows, from top to bottom, a triangular wave representing one PWM period for center-aligned PWM drive, the value of the PWM period timer Tpwm, the waveform of the drive signal on the HI side of the PWM drive phase (energized phase), the waveform of the drive signal on the LO side of the PWM drive phase (energized phase), and as masks associated with square wave switching, a PWM drive mask (PWM drive phase HI side), a PWM drive mask (PWM drive phase LO side), and a PWM drive mask obtained by combining the PWM drive mask periods of the PWM drive phase HI side and the PWM drive phase LO side. The values ​​of the PWM mask timer Toffset and Twindow are shown, along with the summation mask, the PWM power-off mask, and the PWM mask (integrated) which combines the mask period associated with square wave switching (PWM drive mask (summation) + PWM power-off mask). The HI-side PWM drive phase (power-on phase) and the LO-side PWM drive phase (power-on phase) are in the same phase and are switched complementaryly in this example. In this case, with a PWM period Tperiod, the PWM period timer has dead time from t1 to t2 and from t3 to t4, the PWM drive phase LO-side on period from 0 to t1 and from t4 to Tperiod, and the PWM drive phase HI-side on period from t2 to t3. Therefore, it is driven by duty cycle Tduty, and the duty cycle of the drive signal is Tduty / Tperiod.

[0130] In this example, the lower triangular wave defines the switching timing for the HI side of the PWM drive phase (energized phase), and the upper triangular wave defines the switching timing for the LO side of the PWM drive phase (energized phase). In this example, two triangular waves are used to create a dead time during switching by staggering the switching timings, but it is also possible to use a single triangular wave to simultaneously and complementaryly perform the switching timings for both PWM energized phases.

[0131] To prevent false detection of spikes and ringing that occur in the voltage waveform of the induced voltage and reference voltage due to square wave switching, the PWM drive mask includes Tpwm_on_mask, which is used when the switch is on, and Tpwm_off_mask, which is used when the switch is off.

[0132] The combined PWM drive masks Tpwm_mask_f and Tpwm_mask_r, which are a composite of the HI and LO periods of the PWM drive mask, represent the time in the first half of a single PWM period for center-aligned PWM drive, starting from when the LO side of the PWM drive phase is off and continuing until the time specified by Tpwm_on_mask has elapsed from when the HI side of the PWM drive phase is on, and the time in the second half of the PWM period, starting from when the HI side of the PWM drive phase is off and continuing until the time specified by Tpwm_on_mask has elapsed from when the LO side of the PWM drive phase is on.

[0133] A PWM power-off mask is used when it is desirable to avoid the influence of external electromagnetic noise on induced voltages and reference voltages during periods when the HI side of the PWM drive phase is off and power is not supplied, or when it is not possible to use the differential voltage between the reference voltage and the induced voltage due to the use of half the power supply voltage as the reference voltage or the reference voltage remaining unchanged. In the case of center-aligned PWM drive, a PWM power-off mask is provided for the first half of one PWM period, Tde_mask_f, and for the second half, Tde_mask_r. The power-off period of the powered phase due to this PWM power-off mask changes depending on the PWM drive duty cycle.

[0134] The PWM mask (integrated), which is a mask associated with square wave switching that integrates the PWM drive mask and the PWM power-off mask, is as shown in the shaded area of ​​Figure 10. In the first half of one PWM period for center-aligned PWM drive, it is the time from the start of the PWM period until the time Tpwm_on_mask has elapsed from the HI side of the PWM drive phase being turned on. In the second half, it is the time from the HI side of the PWM drive phase being turned off until the end of the PWM period, i.e., the PWM period Tperiod.

[0135] The PWM mask (integrated) works as follows: the PWM mask timer Toffset, which starts timing in sync with the PWM period timer Tpwm, masks the first half of the PWM period from 0 to t101; and the PWM mask timer Twindow, which starts timing from t101, masks the second half of the PWM period from t102 to the PWM period Tperiod.

[0136] In this embodiment, the zero-crossing detection signal generation unit 121 is generated by the rectangular wave control unit 13. The state control unit 12 receives the drive command signal So, and the zero-crossing detection signal generation unit 121 executes processing at a predetermined timing. However, it is not limited to this, and the state control unit 12, the zero-crossing detection signal generation unit 121, and the square wave control unit 13 may each execute processing independently by controlling their respective timers based on the same triangular wave timing.

[0137] As shown in Figure 9, in the masking process (step S100) in the PWM mask (integration), first, at the timing of the start of the triangular wave period, the square wave control unit 13 starts timing using the PWM period timer Tpwm, and the zero-cross detection signal generation unit 121 starts timing using the PWM mask timer Toffset (step S110). After the square wave control unit 13 starts timing using the PWM period timer Tpwm, it determines whether the PWM period timer Tpwm has reached t1, which is the LO side OFF time (step S120). At this time, from the start of the PWM period, the zero-cross detection signal generation unit 121 performs masking so as not to generate the zero-cross detection signal Zo.

[0138] When the rectangular wave control unit 13 determines that the PWM period timer Tpwm has reached the LO-side OFF time t1 (step S120: YES), it generates a drive command signal So to turn off the LO-side FET of the PWM drive phase (step S130).

[0139] The rectangular wave control unit 13 generates a drive command signal So to turn off the LO-side FET of the PWM drive phase. Then, it determines whether the PWM period timer Tpwm has reached the HI-side ON time t2 (step S140). If it determines that the PWM period timer Tpwm has reached the HI-side ON time t2 (step S140: YES), it generates a drive command signal So to turn on the HI-side FET of the PWM drive phase (step S150).

[0140] After receiving the drive command signal So for turning on the HI-side FET of the generated PWM drive phase, the zero-cross detection signal generation unit 121 further determines whether the PWM mask timer Toffset has reached the offset time t101 (step S160).

[0141] When the zero-crossing detection signal generation unit 121 determines that the PWM mask timer Toffset has reached the offset time t101 (step S160: YES), it activates the output of the zero-crossing detection signal Zo, starts timing by the PWM mask timer Twindow from zero (step S170), and then determines whether the PWM mask timer Twindow has reached the window time t102 (step S180). During this time, the mask is released so that the inductive kickback detection unit 122 can output the zero-crossing detection signal Zo.

[0142] When the zero-crossing detection signal generation unit 121 determines that the PWM mask timer Twindow has reached the window time t102 (step S180: YES), it performs a process to disable the output of the zero-crossing detection signal Zo again (step S190). At this point, it starts masking again so that the zero-crossing detection signal Zo is not output to the inductive kickback detection unit 122.

[0143] The rectangular wave control unit 13 determines whether or not the HI-side OFF time t3 of the PWM period timer Tpwm has been reached (step S200). If it determines that the HI-side OFF time t3 of the PWM period timer Tpwm has been reached (step S200: YES), it generates a drive command signal So to turn off the HI-side FET of the PWM drive phase (step S210).

[0144] The rectangular wave control unit 13 further determines whether the PWM period timer Tpwm has reached the LO side ON time t4 (step S220), and if it determines that the PWM period timer Tpwm has reached the LO side ON time t4 (step S220: YES), the LO of the PWM drive phase A drive command signal So is generated to turn on the side FET (step S230).

[0145] The square wave control unit 13 determines whether the PWM period timer Tpwm has reached the PWM period Tperiod (step S240), and if the PWM period timer Tpwm has reached the PWM period Tperiod, it returns to step S110. In this example, the offset time t101 and window time t102 of the PWM mask timer are configured to operate independently of the PWM period timer, but the offset time t101 of the PWM mask timer may be synchronized with t2+Tpwm_on_mask of the PWM period timer, or the window time t102 of the PWM mask timer may be synchronized with t3 of the PWM period timer.

[0146] Next, based on Figures 11 and 12, we will explain the processing flow when performing the masking process during the first masking time (kickback elimination mask).

[0147] Figures 11 and 12 are flowcharts illustrating an example of the processing flow when performing mask processing during the first mask time (kickback elimination mask). Figure 11 shows an example when the LO side power supply is switched, and Figure 12 shows an example when the HI side power supply is switched. The example in Figure 11 corresponds to the timing charts in Figures 5 and 7, and the example in Figure 12 corresponds to the timing charts in Figures 6 and 8.

[0148] As shown in Figure 11, in the masking process (step S300) during LO-side power switching, first, the control circuit 1 executes the LO-side power switching process (step S310). Specifically, the square wave control unit 13 changes the power supply phase setting of the inverter circuit 2a (power switching). After that, the square wave control unit 13 resets the power switching timer Tsector that is counting (step S311). Furthermore, the inductive kickback detection unit 122 sets the state control unit 12 to kickback zero-cross detection mode (step S312), and switches the fluctuation detection direction of the differential voltage detection signal Vd in the zero-cross detection signal generation unit 121 from negative to positive.

[0149] The inductive kickback detection unit 122 determines whether or not a zero cross has been detected by monitoring the zero cross detection signal Zo generated by the zero cross detection signal generation unit 121 (step S320). A zero cross can be detected by the zero cross detection signal generation unit 121 when the differential voltage detection signal Vd changes from positive to negative or from negative to positive. In step S310, the detection direction of the differential voltage detection signal Vd in the zero cross detection signal generation unit 121 is switched from negative to positive, so when the differential voltage detection signal Vd changes from negative to positive, a zero cross detection signal Zo is generated and can be determined as a zero cross (step S320: YES).

[0150] If the inductive kickback detection unit 122 determines that a zero cross has been detected (step S320: YES), it determines whether the current setting of the state control unit 12 is the kickback zero cross detection mode (step S330). In the case of the first zero cross detection after power switching, the state control unit 12 is set to the kickback zero cross detection mode in step S312, so it can be determined that the current setting is the kickback zero cross detection mode (step S330: YES).

[0151] When the inductive kickback detection unit 122 determines that the state control unit 12 is in kickback zero-cross detection mode (step S330: YES), it determines whether the detection of a zero-cross in step S320 is within a specified value for the elapsed time of the power supply switching timer Tsector, which was reset in the LO-side power supply switching process in step S310 (step S340). The specified value for the elapsed time is set to a sufficiently short time for which inductive kickback may occur, for example, the time that is one cycle of PWM drive. If the inductive kickback detection unit 122 detects a zero cross within the time it takes for one cycle of PWM drive after switching the energizing phase to the coil, it determines that inductive kickback has occurred and performs kickback occurrence detection processing (step S350). On the other hand, if the inductive kickback detection unit 122 detects a zero cross after a specified value, it determines that it has detected a zero cross to be used for energizing switching and does not perform kickback occurrence detection processing or kickback elimination detection processing, but instead performs the zero cross detection processing of step S360 described later.

[0152] The inductive kickback detection unit 122 determines that the first zero-cross detection since the power-on switch occurred within a specified time (step S340: YES), and if so, it determines that an inductive kickback has occurred, performs a kickback occurrence detection process (step S350), sets the state control unit 12 to kickback start mode (step S351), and returns to the process in step S320. The kickback occurrence detection process is a process associated with the detection of an inductive kickback. In the kickback occurrence detection process, the inductive kickback detection unit 122 notifies the inductive kickback mask processing unit 123 of the occurrence of an inductive kickback, cancels the output of the zero-cross detection signal Zo generated by the inductive kickback to the square wave control unit 13, and switches the fluctuation detection direction of the differential voltage detection signal Vd in the zero-cross detection signal generation unit 121 from positive to negative.

[0153] When the inductive kickback detection unit 122 determines that it has detected the second zero-crossing since the power switch (step S320: YES), it again determines whether the state control unit 12 is in kickback zero-crossing detection mode (step S330). However, since the state control unit 12 was set to kickback start mode in step S351, the result is NO. In this case, it further determines whether the state control unit 12 is in kickback start mode (step S400). However, since the state control unit 12 was set to kickback start mode in step S351, the result is YES.

[0154] When the inductive kickback detection unit 122 detects the second zero-crossing after the power switch, and the state control unit 12 determines that the kickback start mode is active (step S400: YES), it determines that the inductive kickback has been resolved and executes the kickback resolution detection process (step S410). The kickback resolution detection process is a process that accompanies the detection of the resolution of the inductive kickback. In the kickback resolution detection process, the inductive kickback detection unit 122 notifies the inductive kickback mask processing unit 123 that the inductive kickback has been resolved and cancels the output of the zero-crossing detection signal Zo generated by the resolution of the inductive kickback to the square wave control unit 13. When the inductive kickback mask processing unit 123 receives notification of the elimination of inductive kickback, it starts the kickback elimination mask timer Tkb_end_mask (step S411). Meanwhile, the inductive kickback detection unit 122 further changes the state control unit 12 from kickback start mode to kickback end mode (step S412), and switches the fluctuation detection direction of the differential voltage detection signal Vd in the zero-cross detection signal generation unit 121 from negative to positive.

[0155] When the state control unit 12 is set to kickback termination mode, the inductive kickback mask processing unit 123 disables the output of the zero-cross detection signal Zo (step S413) and determines whether the kickback elimination mask timer has reached the first mask time (step S420). If the inductive kickback mask processing unit 123 determines that the kickback elimination mask timer has reached the first mask time (step S420: YES), it enables the output of the zero-cross detection signal Zo (step S421), thereby releasing the masking process and returning to the process in step S320.

[0156] If the inductive kickback detection unit 122 determines that it has detected the third zero-crossing since the power switch (step S320: YES), the inductive kickback detection unit 122 again determines whether the state control unit 12 is in kickback zero-crossing detection mode (step S330). However, since the state control unit 12 was set to kickback termination mode in step S412, the result is NO. In this case, the unit further determines whether the state control unit 12 is in kickback start mode (step S400). However, since the state control unit 12 was set to kickback termination mode in step S412, the result is NO.

[0157] The inductive kickback detection unit 122 performs a zero-cross detection process (step S360) when it detects the third zero-cross from the power switch, which is a zero-cross detection when the state control unit 12 is set to kickback termination mode, and recognizes that it has detected a zero-cross to be used for power switching. The zero-cross detection process (step S360) is also performed for the first zero-cross from the power switch if no inductive kickback occurs. After the zero-cross detection process in step S360, the inductive kickback detection unit 122 sets the state control unit 12 to post-zero-cross detection mode (step S361) and notifies the inductive kickback mask processing unit 123 that it has detected a zero-cross to be used for power switching, recognizing that the zero-cross detection signal Zo is a zero-cross to be used for power switching.

[0158] The inductive kickback mask processing unit 123, assuming that the zero-crossing detection signal Zo in step S360 is a zero-crossing detection used for power switching, receives notification of a zero-crossing detection used for power switching. Since the first mask time has elapsed (step S420: YES) and the masking process has been released, it outputs the zero-crossing detection signal Zo generated by the zero-crossing detection signal generation unit 121 to the square wave control unit 13. The square wave control unit 13 sets the power-switching phase switching time in the power-switching timer Tsector (step S362), and the square wave control unit 13 determines whether the power-switching timer Tsector has reached the power-switching phase switching time (step S370).

[0159] When the control circuit 1 determines that the power supply switching timer Tsector of the square wave drive unit 13 has reached the power supply phase switching time (step S370: YES), it proceeds to the HI side power supply switching shown in Figure 12 (step S380).

[0160] As shown in Figure 12, in the masking process (step S500) during HI-side power switching, first, the HI-side power switching process is executed in the control circuit 1 (step S510). Specifically, the square wave control unit 13 changes the power supply phase setting of the inverter circuit 2a (power switching). After that, the square wave control unit 13 resets the power switching timer Tsector that is counting (step S511). Furthermore, the inductive kickback detection unit 122 sets the state control unit 12 to kickback zero-cross detection mode (step S512), and switches the fluctuation detection direction of the differential voltage detection signal Vd in the zero-cross detection signal generation unit 121 from positive to negative.

[0161] The inductive kickback detection unit 122 determines whether or not a zero cross has been detected by monitoring the zero cross detection signal Zo generated by the zero cross detection signal generation unit 121 (step S520). A zero cross can be detected by the zero cross detection signal generation unit 121 when the differential voltage detection signal Vd changes from positive to negative or from negative to positive. In step S510, the direction of detection of the differential voltage detection signal Vd in the zero cross detection signal generation unit 121 is switched from positive to negative, so when the differential voltage detection signal Vd changes from positive to negative, a zero cross detection signal Zo is generated and can be determined as a zero cross (step S520: YES).

[0162] The inductive kickback detection unit 122, when it determines that a zero cross has been detected, (st Step S520: YES) determines whether the current setting of the state control unit 12 is kickback zero-cross detection mode (Step S530). In the case of the first zero-cross detection after power switching, the state control unit 12 is set to kickback zero-cross detection mode in Step S512, so it can be determined that the current setting is kickback zero-cross detection mode (Step S530: YES).

[0163] When the inductive kickback detection unit 122 determines that the state control unit 12 is in kickback zero-cross detection mode (step S530: YES), it determines whether the detection of the zero-cross in step S520 occurred within a specified time of the energization switching timer Tsector, which was reset in the HI-side energization switching process in step S510 (step S540). The specified time is set to a sufficiently short time in which inductive kickback may occur, for example, the time required for one cycle of PWM drive. That is, if the inductive kickback detection unit 122 detects a zero-cross within the time required for one cycle of PWM drive after switching the energization phase to the coil, it determines that inductive kickback has occurred and performs kickback occurrence detection processing (step S550). On the other hand, if the inductive kickback detection unit 122 detects a zero crossing after a specified value, it recognizes that it has detected a zero crossing to be used for power switching, and instead of performing kickback occurrence detection processing or kickback elimination detection processing, it performs the zero crossing detection processing of step S560 described later.

[0164] The inductive kickback detection unit 122 determines that the first zero-cross detection from the power-on switch occurs when the elapsed time from the power-on switch is within a specified value (step S540: YES), and determines that an inductive kickback has occurred, performs kickback occurrence detection processing (step S550), sets the state control unit 12 to kickback start mode (step S551), and returns to the process in step S520. The kickback occurrence detection processing is the processing associated with the detection of the occurrence of an inductive kickback. In the kickback occurrence detection processing, the inductive kickback detection unit 122 notifies the inductive kickback mask processing unit 123 of the occurrence of an inductive kickback, cancels the output of the zero-cross detection signal Zo generated by the inductive kickback to the square wave control unit 13, and switches the fluctuation detection direction of the differential voltage detection signal Vd in the zero-cross detection signal generation unit 121 from negative to positive.

[0165] When the inductive kickback detection unit 122 determines that it has detected the second zero-crossing since the power switch (step S520: YES), it again determines whether the state control unit 12 is in kickback zero-crossing detection mode (step S530). However, since the state control unit 12 was set to kickback start mode in step S551, the result is NO. In this case, it further determines whether the state control unit 12 is in kickback start mode (step S600). However, since the state control unit 12 was set to kickback start mode in step S551, the result is YES.

[0166] When the inductive kickback detection unit 122 detects the second zero-crossing after the power switch, and the state control unit 12 determines that the kickback start mode is active (step S600: YES), it determines that the inductive kickback has been resolved and executes the kickback resolution detection process (step S610). The kickback resolution detection process is a process that accompanies the detection of the resolution of the inductive kickback. In the kickback resolution detection process, the inductive kickback detection unit 122 notifies the inductive kickback mask processing unit 123 that the inductive kickback has been resolved and cancels the output of the zero-crossing detection signal Zo generated by the resolution of the inductive kickback to the square wave control unit 13. When the inductive kickback mask processing unit 123 receives notification of the elimination of inductive kickback, it starts the kickback elimination mask timer Tkb_end_mask (step S611). Meanwhile, the inductive kickback detection unit 122 further kicks the state control unit 12. The setting is changed from the back start mode to the kickback end mode (step S612), and the zero-cross detection signal generation unit 121 switches the fluctuation detection direction of the differential voltage detection signal Vd from positive to negative.

[0167] When the state control unit 12 is set to kickback termination mode, the inductive kickback mask processing unit 123 disables the output of the zero-cross detection signal Zo (step S613) and determines whether the kickback elimination mask timer has reached the first mask time (step S620). If the inductive kickback mask processing unit 123 determines that the kickback elimination mask timer has reached the first mask time (step S620: YES), it enables the output of the zero-cross detection signal Zo (step S621), thereby releasing the masking process and returning to the process in step S520.

[0168] If the inductive kickback detection unit 122 determines that it has detected the third zero-crossing since the power switch (step S520: YES), the inductive kickback detection unit 122 again determines whether the state control unit 12 is in kickback zero-crossing detection mode (step S530). However, since the state control unit 12 was set to kickback termination mode in step S612, the result is NO. In this case, the state control unit 12 further determines whether it is in kickback start mode (step S600). However, since the state control unit 12 was set to kickback termination mode in step S612, the result is NO.

[0169] The inductive kickback detection unit 122 performs a zero-cross detection process (step S560) when it detects the third zero-cross from the power switch, which is a zero-cross detection when the state control unit 12 is set to kickback termination mode, and recognizes that it has detected a zero-cross to be used for power switching. The zero-cross detection process (step S560) is also performed for the first zero-cross from the power switch if no inductive kickback occurs. After the zero-cross detection process in step S560, the inductive kickback detection unit 122 sets the state control unit 12 to post-zero-cross detection mode (step S561) and notifies the inductive kickback mask processing unit 123 that it has detected a zero-cross to be used for power switching, recognizing that the zero-cross detection signal Zo is a zero-cross to be used for power switching.

[0170] The inductive kickback mask processing unit 123, assuming that the zero-crossing detection signal Zo in step S560 is a zero-crossing detection used for power switching, receives notification of a zero-crossing detection to be used for power switching. Since the first mask time has elapsed (step S620: YES) and the masking process has been released, it outputs the zero-crossing detection signal Zo generated by the zero-crossing detection signal generation unit 121 to the square wave control unit 13. The square wave control unit 13 sets the power-switching phase switching time in the power-switching timer Tsector (step S562), and the square wave control unit 13 determines whether the power-switching timer Tsector has reached the power-switching phase switching time (step S570).

[0171] When the control circuit 1 determines that the power supply switching timer Tsector of the square wave control unit 13 has reached the power supply phase switching time (step S570: YES), it proceeds to the LO side power supply switching shown in Figure 11 (step S580).

[0172] As described above, in the control circuit 1 of the motor drive control device 10 according to this embodiment, a differential voltage detection signal is detected, which is the differential voltage between the induced voltage generated in the coil of the non-energized phase and a reference voltage, based on the phase voltage of each phase. Based on the detected differential voltage detection signal and zero-cross detection, the control circuit 1 generates a drive command signal (So) in the PWM signal generation unit (14) to switch the energized phase to the coil and to switch the switch of the inverter circuit 2a on and off to switch the energized state of the coil that has become energized. The system detects the occurrence and resolution of inductive kickback in the coil, masks zero-cross detection for a first predetermined time after detecting the resolution of the inductive kickback, and masks zero-cross detection for a second predetermined time during the rising and falling edges of the rectangular wave signal.

[0173] According to this, the motor drive control device 10 can reliably avoid false detection of zero-crossings used for current switching due to spikes or ringing, even when driven at high rotation speeds, high output, and high load.

[0174] In the control circuit 1 of the motor drive control device 10 according to this embodiment, the motor is driven by generating a drive control signal Sd that turns on and off the high-side switch and the low-side switch of the inverter circuit 2a that energizes the coil, and the zero-cross detection is masked for a second predetermined time at the on / off timing of the switch of the PWM drive phase of the energized phase among the high-side switch and the low-side switch of the inverter circuit 2a.

[0175] According to this, even when the motor drive control device 10 is driven by controlling the inverter circuit 2a to turn on and off, it is possible to reliably avoid false detection of zero-crossings used for power switching due to spikes and ringing.

[0176] In the control circuit 1 of the motor drive control device 10 according to this embodiment, after the execution of the PWM drive masking process that masks the zero-crossing detection for a second predetermined time period is completed, a kickback elimination masking process that masks the zero-crossing detection for a first predetermined time period is executed.

[0177] According to this, the motor drive control device 10 can avoid false detection of zero-crossings used for power switching by performing masking over both the first mask time and the second mask time.

[0178] In the control circuit 1 of the motor drive control device 10 according to this embodiment, in addition to masking by the first predetermined time and the second predetermined time, the zero-cross detection is masked over the power-off period, which is the period during which the switch of the PWM drive phase of the energized phase is turned off.

[0179] According to this, the motor drive control device 10 can accurately detect the zero-crossing used for power switching, even when it is desired to avoid the influence of external electromagnetic noise on induced voltage and reference voltage during periods when power is not supplied, or when using half of the power supply voltage as the reference voltage.

[0180] In the control circuit 1 of the motor drive control device 10 according to this embodiment, the inductive kickback detection unit 122 switches the zero-cross detection mode based on the differential voltage detection signal according to the energization switching mode.

[0181] According to this method, even when no field-induced kickback occurs, or when the duration of inductive kickback is extremely short, it is possible to accurately detect the zero-crossing point used for current switching.

[0182] In the control circuit 1 of the motor drive control device 10 according to this embodiment, the inductive kickback detection unit 122 may process the occurrence of inductive kickback when it detects the first zero crossing within the time it takes for one cycle of PWM drive after switching the energizing phase to the coil.

[0183] According to this method, even if inductive kickback does not occur, the detected zero-crossing can be correctly identified as a zero-crossing used for power switching.

[0184] <<Extension of the Embodiment>> Although the present invention has been specifically described above based on embodiments, it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from its essence.

[0185] Furthermore, while the embodiment illustrates a case where the speed command signal Sc includes a target value for the rotational speed of the motor 3 (target rotational speed), it is not limited to this. For example, the speed command signal Sc may be a torque command signal that specifies the torque of the motor 3.

[0186] Furthermore, in the embodiment, the control circuit 1 is not limited to the circuit configuration described above. Various circuit configurations can be applied to the control circuit 1 to suit the objectives of the present invention.

[0187] Specifically, for example, instead of the multiplexer in the differential voltage detection circuit 15, multiple comparators or A / D converters may be used. The differential voltage detection circuit 15 may be configured as an analog circuit as shown in Figure 3, or as a digital circuit. Furthermore, the differential voltage detection circuit 15 does not need to perform a DC current 1 / 2 shift.

[0188] Furthermore, in the embodiment, the example described was one in which the drive signal for the HI-side energized phase that drives the motor is switched on and off in a complementary manner between the high-side transistor (any of the high-side switches Q1, Q3, and Q5) and the low-side transistor (any of the low-side switches Q2, Q4, and Q6). However, it is also possible to configure the system so that only the high-side transistor (any of the high-side switches Q1, Q3, and Q5) is switched on and off by the drive signal for the HI-side energized phase.

[0189] Furthermore, although the embodiment described an example in which the PWM drive is center-aligned, it may also be edge-aligned.

[0190] Furthermore, in the embodiment, the inverter circuit was described as being driven by PWM with the power supply side being the PWM drive phase and the GND side being the GND phase, with power supplied by turning on the HI side switch of the PWM drive phase and the LO side switch of the GND phase. However, the power supply side of the inverter circuit may be changed to the GND side for gate driving, and the GND phase may be changed to the power supply side for PWM driving, with power supplied by turning on the HI side switch of the power supply phase and the LO side switch of the PWM drive phase.

[0191] Furthermore, in this embodiment, the motor drive is not limited to 120-degree energized square wave drive. 150-degree energized square wave drive or sine wave drive may also be used.

[0192] Furthermore, in the embodiment, a second predetermined time is provided, and PWM drive masks Tpwm_on_mask and Tpwm_off_mask are provided, respectively. Although the same value is used as the mask time when the switching element is on and off, different values ​​may be used.

[0193] Furthermore, in this embodiment, a PWM power-off mask Tde_mask is used, which sets the power-off period of the energized phase as the mask time. However, by using the neutral point voltage instead of half the power supply voltage as the reference voltage, it is not necessary to use a PWM power-off mask.

[0194] In this embodiment, the number of phases of the motor 3 driven by the motor drive control device 10 is not limited to three phases.

[0195] The flowchart described above is just an example and is not limited to this flowchart. For example, other processes may be inserted between each step, or the processes may be parallelized. [Explanation of Symbols]

[0196] 1...Control circuit, 2...Drive circuit, 2a...Inverter circuit, 2b...Pre-drive circuit, 3...Motor, 10...Motor drive control device, 11...Drive command acquisition unit, 12...State control unit, 121...Zero-crossing detection signal generation unit, 122...Inductive kickback detection unit, 123...Inductive kickback mask processing unit, 13...Square wave control unit, 14...PWM signal generation unit, 15...Differential voltage detection circuit, 151...Multiple resistors for DC current limiting and voltage adjustment, 152...Measurement phase selection multiplexer, 153 ...differential amplifier circuit, 100...motor unit, Q1~Q6...switching element, Sc...speed command signal, Sd...drive control signal, ωref...target rotational speed, Zo...zero crossing detection signal, So...drive command signal, Sm...measurement phase selection signal, Vd,Vd'...differential voltage detection signal, Vm...selected phase voltage signal, Vn...neutral point voltage (composite signal), Vdc,Vin...DC power supply, Vuh,Vul,Vvh,Vvl,Vwh,Vwl...drive signal, Vu,Vv,Vw...phase voltage signal, Lu,Lv,Lw...coil

Claims

1. A control circuit that generates a drive control signal for driving a motor having at least one phase of coils, The drive circuit includes an inverter circuit that includes switches connected in series to each other and provided corresponding to the coils of each phase of the motor, and rotates the rotor of the motor by turning the switches on and off in accordance with the drive control signal to energize the coils of the corresponding phases and switching the energized phase at predetermined timings, The inverter circuit and the phase voltage detection circuit for detecting the phase voltage generated between the coils of each phase of the motor are provided. The aforementioned control circuit is A differential voltage detection circuit outputs a differential voltage detection signal, which is the differential voltage between the induced voltage generated in the coil of the non-energized phase and a reference voltage, based on the phase voltage of each phase detected above. The system includes a PWM signal generation unit that generates a drive control signal, which is a square wave signal that switches the energizing phase to the coil and switches the inverter circuit on and off to switch the energizing state of the coil that has become energized, based on zero-crossing detection using the differential voltage detection signal, After switching the energizing phase to the coil, the control circuit detects the occurrence and resolution of inductive kickback in the coil that is now in the unenergized phase, The zero-cross detection is masked for a first predetermined time period after detecting the elimination of the inductive kickback, and the zero-cross detection is masked for a second predetermined time period at the rising and falling timings of the square wave signal. Motor drive control device.

2. In the motor drive control device according to claim 1, The switches in the inverter circuit include a high-side switch and a low-side switch. The PWM signal generation unit drives the motor by generating the drive control signals that turn on and off the high-side switch and the low-side switch of the inverter circuit that energizes the coil. The control circuit masks the zero-cross detection for a second predetermined time period at the on / off timing of the switch that becomes the PWM drive phase of the energized phase among the high-side switch and low-side switch of the inverter circuit. Motor drive control device.

3. In the motor drive control device according to claim 1, The control circuit, after completing the execution of the PWM drive masking process that masks the zero-crossing detection for the second predetermined time, executes the kickback elimination masking process that masks the zero-crossing detection for the first predetermined time. Motor drive control device.

4. In the motor drive control device according to claim 2, The switches in the inverter circuit include a high-side switch and a low-side switch. The PWM signal generation unit drives the motor by generating the drive control signal that switches on and off the inverter circuit that energizes the coil. The control circuit masks the zero-cross detection during the power-off period, which is the period during which the switch of the PWM drive phase of the energized phase is turned off. Motor drive control device.

5. In the motor drive control device according to claim 1, The control circuit, after switching the energizing phase to the coil, further detects the occurrence and resolution of inductive kickback that occurs in the coil that is in the non-energized phase, The control circuit switches the zero-cross detection mode based on the differential voltage detection signal according to the mode of power supply switching by switching the power supply side of the energized phase when the HI side power supply switching is performed, by changing the direction of fluctuation detection of the differential voltage detection signal fluctuation when inductive kickback occurs from positive to negative, and the direction of fluctuation detection of the differential voltage detection signal fluctuation when inductive kickback is resolved from negative to positive, and by switching the GND side of the energized phase when the LO side power supply switching is performed, by changing the direction of fluctuation detection of the differential voltage detection signal fluctuation when inductive kickback occurs from negative to positive, and the direction of fluctuation detection of the differential voltage detection signal fluctuation when inductive kickback is resolved from positive to negative. Motor drive control device.

6. In the motor drive control device according to claim 1, The control circuit detects the occurrence of inductive kickback when it detects the first zero crossing within the time it takes to complete one cycle of PWM driving after switching the energizing phase to the coil. Motor drive control device.

7. A motor drive control method executed in a motor drive control device comprising: a control circuit for generating a drive control signal for driving a motor having at least one phase of coils; an inverter circuit including switches connected in series to each phase of the motor corresponding to the coils of each phase, which rotates the rotor of the motor by turning the switches on and off in accordance with the drive control signal to energize the coil of the corresponding phase and switching the energized phase at a predetermined timing; and a phase voltage detection circuit for detecting the phase voltage generated between the inverter circuit and the coils of each phase of the motor, wherein A first step is to output a differential voltage detection signal, which is the differential voltage between the induced voltage generated in the coil of the non-energized phase and a reference voltage, based on the phase voltage of each phase detected above. A second step involves detecting a zero crossing based on the differential voltage detection signal, A third step is to generate a drive control signal, which is a square wave signal, that switches the energizing phase to the coil based on the zero-crossing detection and switches the inverter circuit switch on and off to switch the energizing state of the coil in the energized phase, A fourth step involves detecting the occurrence and resolution of inductive kickback that occurs in the coil after switching the energizing phase to the coil, The method includes a fourth step of masking the zero-cross detection for a first predetermined time after detecting the elimination of the inductive kickback, and masking the zero-cross detection for a second predetermined time during the rising and falling edges of the square wave signal. A method for controlling the drive of a motor.

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