Motor drive control device and method for detecting initial position of rotor

Abstract

The invention provides a motor drive control device and a method for detecting the initial position of a rotor, which can detect the position of the rotor of a motor in a short time through a low-resolution current measuring device. The present invention is provided with: a control circuit for generating a drive control signal; a drive circuit having an inverter circuit including a switch provided corresponding to a coil of each phase of the motor, the drive circuit rotating a rotor of the motor by alternately turning on / off the switch according to the drive control signal; the shunt resistor is arranged between the phase inverter circuit and the ground; and a bidirectional current detection circuit that detects a current flowing through the shunt resistor in a bidirectional manner, the control circuit sequentially switches the energization sections without rotating the rotor of the motor, and energizes and cuts off the coil in the energization direction. The position of the rotor is estimated based on a peak value of an energization current for each of the energization sections and a peak value of a recoil current generated by inductive recoil.

Description

Technical Field

[0001] The invention relates to a motor drive control device and a method for detecting an initial position of a rotor. Background Art

[0002] In a three-phase BLDC motor (brushless dc motor) without a position sensor, the following method is known for detecting the initial position of the rotor of a stopped motor: in one-phase excitation or 1-2-phase excitation, when power is supplied in every six directions, the winding is excited by supplying power, and the "arrival time to reach a specified current" or "maximum current within a specified time" is measured. The time generated by the influence of magnetic saturation of the coil in each power supply direction or the difference generated by the current is used to detect the magnetic pole position (initial position) of the rotor (Patent Documents 1, 2, 3). Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2010-41881 Patent Document 2: Japanese Patent Application Publication No. 2016-19454 Patent Document 3: Japanese Patent Application Publication No. 2021-164191 Summary of the invention Problems to be solved by the invention

[0004] In the existing detection method of the magnetic pole position of the rotor, in the SPMSM (Surface Permanent Magnet Synchronous Motor) with small salient polarity, in the case of small current, the influence of the magnetic saturation of the coil is small, and there is a problem that the rotor position cannot be uniquely determined within the range of 60 degrees (power-on section). In the case of large current, although the rotor position is determined by the magnetic saturation of the coil, there is a problem that magnetic noise such as "clicking" is generated due to power-on, and the rotor rotates against the intention. In addition, when the resolution of the current measurement is low, the measured difference becomes smaller, thereby there is a problem that the detection of the magnetic pole position of the rotor becomes difficult.

[0005] The present inventors have conducted in-depth research on the above-mentioned problems and found that: in the current measurement of the 1-shunt method, a bidirectional current detection circuit is used to utilize both the current flowing in the grounding direction when power is on and the rebound current generated by the inductive rebound flowing in the inverter circuit direction when power is off. As a result, the initial position of the rotor can be detected in a short time by a low-resolution current measuring device without increasing the current in order to increase the difference in the current measured within a specified time in each power-on direction. By starting the next power-on after the rebound current converges to zero, correct current measurement can be performed, shortening the measurement time of power-on in all six directions, thereby completing the present invention.

[0006] The present invention is intended to solve the above-mentioned problem, and its object is to provide a motor drive control device capable of detecting the initial position of a rotor in a short time by using a low-resolution current measuring device. Technical Solution

[0007] A motor drive control device according to a representative embodiment of the present invention is characterized in that it comprises: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit having an inverter circuit, the inverter circuit comprising a high-side switch and a low-side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, the drive circuit alternately turning on / off the high-side switch and the low-side switch according to the drive control signal, and rotating the rotor of the motor by switching the energization direction of the coil of the corresponding phase; a shunt resistor provided between the inverter circuit and ground; and a bidirectional current detection circuit for detecting a current flowing through the inverter circuit in both directions, in a grounding direction from the inverter circuit toward the ground and in a direction of the inverter circuit as the opposite direction. The control circuit switches the high-side switch and the low-side switch of the inverter circuit on / off in a manner that the energized sections are switched in sequence without rotating the rotor of the motor, and generates an initial position detection signal for energizing and disconnecting the coil corresponding to the energized section. Based on the current detected in the bidirectional current detection circuit when generating the initial position detection signal, the peak value of the energized current flowing in the grounding direction when the energization is on and the peak value of the kickback current caused by the inductive kickback flowing in the direction of the inverter circuit when the energization is disconnected are obtained for each energized section, and the position of the rotor is estimated based on the peak value of the energized current and the peak value of the kickback current in each energized section. Effects of the Invention

[0008] According to one aspect of the present invention, the initial position of the rotor can be detected in a short time by a current measuring device with a low resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 11 is a diagram showing a configuration of a motor unit 100 including a motor drive control device 10 according to an embodiment. Figure 2 1 is a diagram showing a configuration example of the current detection circuit 22 of the motor drive control device 10 . Figure 3 The diagram shows the switching state and current vector of the inverter circuit 2 a in each energization section of the three-phase motor 3 . Figure 4 It is a diagram showing the specific direction of the current vector. Figure 5 It is a diagram for explaining the switch state corresponding to the free mode switched according to the idling control signal Id. Figure 6 It is a diagram for explaining the switch state corresponding to the charging mode switched according to the idle control signal Id. Figure 7 It is a diagram for explaining the switch state corresponding to the discharge mode switched according to the idle control signal Id. Figure 8 1 is a diagram showing a functional block configuration of a control circuit 1 in a motor drive control device 10 according to the embodiment. Fig. 9 1 is a diagram showing a configuration example of the current measuring unit 16 included in the control circuit 1 of the motor drive control device 10 . Fig.10 This is a timing chart showing an example of a signal waveform from when the speed command signal Sc is input when the rotor of the motor 3 is not moving at all to when the rotor idling detection is completed. Fig.11 This is a timing chart showing an example of a signal waveform from when the speed command signal Sc is input when the rotor of the motor 3 is moving until the rotor idling detection is completed. Fig.12 This is a timing chart showing an example of a signal waveform from when the motor unit 100 is powered on, the speed command signal Sc is input, and it is confirmed that the rotor has stopped, to when the rotor initial position detection is completed. Fig.13 1 is a timing chart showing another example of the signal waveform after the motor unit 100 is powered on, the speed command signal Sc is input, and the rotor is confirmed to be stopped, until the rotor initial position detection is completed. Fig.14 This is a timing chart showing another example of the signal waveform of energization / disconnection of one energization section in the rotor initial position detection after the motor unit 100 is powered on, the speed command signal Sc is input, and the rotor is confirmed to have stopped. Fig.15This is a flowchart showing an example of the flow of processing when the power is turned on in the control circuit 1 of the motor drive control device 10 according to the embodiment. Fig.16 1 is a flowchart showing an example of a flow of offset measurement performed by the control circuit 1 of the motor drive control device 10 . Fig.17 1 is a flowchart showing an example of a flow of the rotor stop waiting process performed by the control circuit 1 of the motor drive control device 10 . Fig.18 1 is a flowchart showing an example of a flow of measuring the rotor initial position by the control circuit 1 of the motor drive control device 10 . Fig.19 1 is a flowchart showing an example of a flow of measuring the rotor initial position in the energized section n by the control circuit 1 of the motor drive control device 10 . DETAILED DESCRIPTION

[0010] 1. Overview of implementation methods First, a typical embodiment of the invention disclosed in this application will be described in outline. Note that, in the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are indicated in parentheses.

[0011] [1] A motor drive control device according to a representative embodiment of the present invention is characterized in that it comprises: a control circuit (1) for generating a drive control signal (Sd) for driving a motor having a coil of at least one phase; a drive circuit (2) having an inverter circuit (2a), wherein the inverter circuit includes high-side switches (Q1, Q3, Q5) and low-side switches (Q2, Q4, Q6) connected in series with each other and arranged corresponding to the coils of each phase of the motor, wherein the drive circuit turns on / off the high-side switches and the low-side switches alternately according to the drive control signal, and rotates the rotor of the motor by switching the current supply direction of the coil of the corresponding phase; a shunt resistor (Rs) provided between the inverter circuit and the ground; and a bidirectional current detection circuit (30) for detecting a current in a direction from the inverter circuit toward the ground and in a direction from the inverter circuit toward the ground as its phase. The current flowing through the shunt resistor is detected bidirectionally in the direction of the inverter circuit in the opposite direction. The control circuit turns on / off the high-side switch and the low-side switch of the inverter circuit in a manner of switching the energized sections in sequence without rotating the rotor of the motor, and generates an initial position detection signal (Pd) for energizing and disconnecting in the energizing direction of the coil corresponding to the energizing section. Based on the current detected in the bidirectional current detection circuit when generating the initial position detection signal, the peak value of the energizing current flowing toward the grounding direction when the energization is on and the peak value of the kickback current caused by the inductive kickback flowing toward the inverter circuit direction when the energization is disconnected are obtained for each energizing section, and the position of the rotor is estimated based on the peak value of the energizing current and the peak value of the kickback current in each energizing section.

[0012] [2] In the motor drive control device described in [1] above, it can also be set as: the control circuit has: an initial position detection signal generating unit (131), which generates the initial position detection signal input to the inverter circuit to energize and disconnect the coil in the energization direction in turn according to each energization section; a peak current acquisition unit (132), which acquires the peak value of the energization current and the peak value of the rebound current in each energization section; and a position estimation unit (133), which estimates the position of the rotor based on the peak value of the energization current and the peak value of the rebound current in each energization section.

[0013] [3] In the motor drive control device described in [2] above, the initial position detection signal generating unit may generate the initial position detection signal for energizing the next energizing section after confirming that the magnitude of the kickback current has converged to zero.

[0014] [4] In the motor drive control device described in [2] above, the peak current acquisition unit may acquire a peak value of the energizing current and acquire the kickback current after a masking time has elapsed.

[0015] [5] In the motor drive control device described in [2] above, it can also be set as: the position estimation unit compares the total current value of the power-on current and the recoil current in each of the power-on segments, and estimates the position corresponding to the power-on segment with the largest total current value as the position of the rotor.

[0016] [6] In the motor drive control device described in [5] above, it can also be configured that: when the power-on segment that becomes the maximum total current value cannot be determined as one, the position estimation unit obtains the power-on segment in which the peak value of the power-on current flowing in the grounding direction becomes the maximum and the power-on segment in which the peak value of the rebound current generated by the inductive rebound flowing in the inverter circuit direction becomes the maximum, and estimates the position of the rotor based on the number of power-on segments obtained.

[0017] [7] In the motor drive control device described in [5] above, it can also be set as follows: when the power-on segment with the maximum total current value cannot be determined as one, the position estimation unit further obtains the difference of three bidirectional currents for each power-on segment based on the total current value, wherein the total current value is a current value obtained by summing the peak value of the power-on current flowing in the grounding direction and the peak value of the rebound current generated by the inductive rebound flowing in the inverter circuit direction. When the maximum value of the difference of the three bidirectional currents is one, it is estimated that the position of the rotor is at a position corresponding to the power-on segment with a larger total current value among the two power-on segments of the bidirectional power-on where the current difference is the maximum value.

[0018] [8] In the motor drive control device described in [2] above, it can also be set as: the initial position detection signal generating unit generates the initial position detection signal, wherein the initial position detection signal is set to be divided into a plurality of prescribed times to carry out energization in the energization direction of the coil corresponding to the energization section.

[0019] [9] In the motor drive control device described in [2] above, it can also be configured that: the initial position detection signal generating unit generates the initial position detection signal, wherein the initial position detection signal is set to the timing of the cut-off in the power-on section, so that the switch in the high-side switch and the low-side switch of the inverter circuit that is in a complementary relationship with the switch when power is on is turned on.

[0020]

[10] In the motor drive control device described in [1] above, it can also be set as: the control circuit also has: a first switching unit (121a), switching from a first switching state in which the high-side switch and the low-side switch included in the inverter circuit are all disconnected to a second switching state in which at least two of the high-side switch or the low-side switch included in the inverter circuit are connected; a second switching unit (121b), switching from the second switching state to the first switching state; and an idling determination unit (122), when switching from the second switching state to the first switching state, determining whether the rotor of the motor is idling based on the current flowing through the shunt resistor, and the control circuit generates the initial position detection signal after confirming that the rotor of the motor is not idling through the idling determination unit.

[0021]

[11] In the motor drive control device described in

[10] above, it can also be set as: the control circuit also has a position estimation unit, which estimates the position of the rotor based on the peak value of the current in each of the energized sections and the peak value of the kickback current, and the control circuit also has a current measuring unit, which detects the output signal from the bidirectional current detection circuit as an offset in advance when no current flows through the shunt resistor, and when determining the idling and estimating the position of the rotor, adjusts the signal output from the bidirectional current detection circuit by the offset and outputs it to the idling determination unit and the position estimation unit.

[0022]

[12] A representative embodiment of the present invention is a rotor initial position detection method, which is a rotor initial position detection method executed in a motor drive control device, wherein the motor drive control device comprises: a control circuit, which generates a drive control signal for driving a motor having a coil of at least one phase; a drive circuit, which has an inverter circuit, wherein the inverter circuit includes a high-side switch and a low-side switch which are connected in series with each other and are arranged corresponding to the coils of each phase of the motor, wherein the drive circuit turns on / off the high-side switch and the low-side switch alternately according to the drive control signal, and rotates the rotor of the motor by switching the energization direction of the coil of the corresponding phase; a shunt resistor, which is arranged between the inverter circuit and the ground; and a bidirectional current detection circuit, which detects current in a grounding direction from the inverter circuit toward the ground and in the inverter circuit direction which is the opposite direction. The current flowing through the shunt resistor is detected in both directions, and the initial position detection method of the rotor is characterized in that it includes: a first step, in which the high-side switch and the low-side switch of the inverter circuit are turned on / off in a manner of switching the power-on sections in sequence without rotating the rotor of the motor, to generate an initial position detection signal for energizing and cutting off in the power-on direction of the coil corresponding to the power-on section; a second step, based on the current detected in the bidirectional current detection circuit when generating the initial position detection signal, for each of the power-on sections, obtaining the peak value of the power-on current flowing toward the grounding direction when the power is on and the peak value of the rebound current generated by the inductive rebound and flowing toward the direction of the inverter circuit when the power is cut off; and a third step, estimating the position of the rotor based on the peak value of the power-on current and the peak value of the rebound current in each of the power-on sections.

[0023] 2. Specific examples of implementation methods Hereinafter, specific examples of the embodiments of the present invention will be described with reference to the drawings. It should be noted that in the following description, the same reference numerals are given to the common components in each embodiment, and repeated descriptions are omitted.

[0024] Implementation Method Figure 1 1 is a diagram showing a configuration of a motor unit 100 including a motor drive control device 10 according to an embodiment.

[0025] like Figure 1 As shown, the motor unit 100 includes a motor 3 and a motor drive control device 10 for controlling the rotation of a rotor of the motor 3. The motor unit 100 can be applied to various devices using a motor as a drive source, such as a fan and a drone (unmanned aerial vehicle).

[0026] The motor 3 is, for example, a permanent magnet synchronous motor (PMSM). In the present embodiment, the 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) connection. In this case, the coils may also be connected to each other in a Δ (delta) connection.

[0027] The motor drive control device 10 supplies a sinusoidal wave drive signal to the motor 3 to cause a sinusoidal wave drive current to periodically flow through the three-phase coils Lu, Lv, and Lw of the motor 3 , thereby rotating the rotor of the motor 3 .

[0028] The motor drive control device 10 includes a control circuit 1 , a drive circuit 2 , and a current detection circuit 22 .

[0029] It should be noted that it can also be, Figure 1 The components of the motor drive control device 10 shown are part of the whole. Figure 1 In addition to the components shown, other components may be included.

[0030] The drive circuit 2 drives the motor 3 based on a drive control signal Sd output from the control circuit 1 described later. The drive circuit 2 includes, for example, an inverter circuit 2a and a pre-drive circuit 21. A current detection circuit 22 is provided between the inverter circuit 2a of the drive circuit 2 and the ground.

[0031] The inverter circuit 2a is arranged between the DC power supply Vin and the ground potential, and is a circuit that drives the coils Lu, Lv, and Lw of the motor 3 as a load based on the input drive control signal Sd. Specifically, in the embodiment, the inverter circuit 2a has three switch branches including two drive transistors connected in series, and the two drive transistors are alternately turned on / off (switching action) based on the input drive control signal Sd, thereby driving the motor 3 as a load.

[0032] More specifically, the inverter circuit 2a has switch branches corresponding to the U phase, V phase, and W phase of the motor 3, respectively. Figure 1 As shown, each corresponding switch branch has two driving transistors (hereinafter also referred to as "switching elements") Q1 and Q2, Q3 and Q4, Q5 and Q6 connected in series between the DC power supply Vin and the ground potential via the current detection circuit 22.

[0033] Here, the driving transistors Q1, Q3, Q5 (equivalent to high-side switches) of the upper bridge arm of the coil of the motor 3 are, for example, N-channel MOSFETs, and the driving transistors Q2, Q4, Q6 (equivalent to low-side switches) of the lower bridge arm of the coil of the motor 3 are, for example, N-channel MOSFETs. It should be noted that the driving transistors Q1 to Q6 may also be other types of FETs, for example, other types of transistors such as IGBTs (Insulated Gate Bipolar Transistors).

[0034] For example, the switch branch corresponding to U has switch elements Q1 and Q2 connected in series with each other. The point at which the switch element Q1 and the switch element Q2 are connected in common is connected to one end of the coil Lu serving as a load. The switch branch corresponding to V has switch elements Q3 and Q4 connected in series with each other. The point at which the switch element Q3 and the switch element Q4 are connected in common is connected to one end of the coil Lv serving as a load. The switch branch corresponding to W has switch elements Q5 and Q6 connected in series with each other. The point at which the switch element Q5 and the switch element Q6 are connected in common is connected to one end of the coil Lw serving as a load. In addition, the switch elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 respectively have parasitic diode characteristics in the direction from the ground side to the power supply side.

[0035] The pre-driving circuit 21 generates a driving signal for driving the inverter circuit 2 a based on the driving control signal Sd output from the control circuit 1 .

[0036] The drive control signal Sd is a signal for controlling the drive of the motor 3, for example, a PWM (Pulse Width Modulation) signal. Specifically, the drive control signal Sd is a signal for switching the energization mode of the coils Lu, Lv, and Lw of the motor 3 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 the switching elements Q1 to Q6 of the inverter circuit 2a.

[0037] The pre-drive circuit 21 generates six drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl that can supply sufficient power to drive the control electrodes (gate electrodes) of each switching element of the inverter circuit 2a based on six PWM signals as the drive control signal Sd supplied from the control circuit 1.

[0038] By inputting these drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, the switching elements Q1 to Q6 are turned on / off (switching action). For example, the switching elements Q1, Q3, and Q5 of the upper bridge arm and the switching elements Q2, Q4, and Q6 of the lower bridge arm of each corresponding switch branch are alternately turned on / off. Thus, power is supplied from the DC power supply Vin to each phase of the motor 3, and the rotor of the motor 3 rotates.

[0039] The current detection circuit 22 is connected to the DC line of the inverter circuit 2a and detects the current flowing in the DC line. Specifically, it includes a resistor (hereinafter also referred to as a "shunt resistor") Rs as a current detection element. The shunt resistor Rs is connected in series with the inverter circuit 2a, for example, between the DC power supply Vin and the ground potential. That is, the shunt resistor Rs of the current detection circuit 22 is, for example, Figure 1 As shown, it is connected to the negative side (ground side) of the inverter circuit 2a. For example, in the motor drive, the inverter circuit 2a is controlled, and the winding currents Iu, Iv, and Iw flowing through the three-phase coils Lu, Lv, and Lw of the motor 3 flow through the shunt resistor Rs of the current detection circuit 22. The current detection circuit 22 detects the voltage drop caused by the current flowing through the shunt resistor Rs based on the differential voltage across the shunt resistor Rs, and outputs a current detection signal Vs corresponding to the current flowing through the shunt resistor Rs to the control circuit 1 as a detection result.

[0040] Figure 2 1 is a diagram showing a configuration example of the current detection circuit 22 of the motor drive control device 10. The current detection circuit 22 includes a bidirectional current detection circuit 30 and a delay circuit 31 in addition to the shunt resistor Rs.

[0041] Figure 2 The current detection circuit 22 outputs a current detection signal Vs corresponding to the current flowing through the shunt resistor Rs.

[0042] Specifically, Figure 2The bidirectional current detection circuit 30 obtains the differential voltage at both ends of the shunt resistor Rs, amplifies it with a specified gain through an amplifier (AMP) using a differential amplifier circuit, and outputs it as a voltage drop signal Vout in the shunt resistor Rs. The delay circuit 31 smoothes the voltage drop signal Vout through a circuit composed of a resistor R3 and a capacitor C3, and outputs it to the control circuit 1 as a current detection signal Vs corresponding to the current flowing through the shunt resistor Rs. The bidirectional current detection circuit 30 is configured to apply a voltage Vdc / 2 that offsets the output of the amplifier to the positive terminal of the differential amplifier circuit, detect the positive and negative sides of the voltage drop generated in the shunt resistor Rs, and thus measure the bidirectional current. At this time, the current detection signal Vs outputs a signal ranging from 0 to Vdc, which becomes Vdc / 2 when the shunt current Is is zero. It should be noted that the voltage that offsets the output of the amplifier is not limited to Vdc / 2, and the voltage that offsets the output of the amplifier can also be applied to the negative terminal of the differential amplifier circuit.

[0043] The bidirectional current detection circuit 30 in the current detection circuit 22 can detect the shunt current Is in the shunt resistor Rs through the current measuring unit 16 described later, with the grounding direction from the inverter circuit 2a toward the ground (the arrow direction of Is in the figure) being set to a positive value and the opposite direction from the ground toward the inverter circuit 2a being set to a negative value.

[0044] In the current detection circuit 22, when the motor 3 is driven based on the drive control signal Sd, the current flowing through the inverter circuit 2a again passes through the shunt resistor Rs via the coil of the motor 3. That is, in the current detection circuit 22, the current flows in the grounding direction from the inverter circuit 2a toward the ground, so the positive shunt current Is can be measured by the current measuring unit 16 described later.

[0045] The motor drive control device 10 of the present embodiment has a configuration for detecting the initial position of the rotor when the rotor of the motor 3 is not rotating, in addition to driving the motor 3 based on the drive control signal Sd.

[0046] In the motor drive control device 10 of the present embodiment, the switching states of the switching elements Q1 to Q6 of the inverter circuit 2a are switched by switching the energized sections in sequence without rotating the rotor of the motor 3, and the position of the rotor is estimated based on the current flowing through the shunt resistor Rs when the energization direction of the coil corresponding to the energization section is turned on and off, thereby detecting the initial position of the rotor.

[0047] In order to detect the initial position of the rotor, in the motor drive control device 10 of the present embodiment, the drive circuit 2 receives an initial position detection signal Pd different from a drive control signal Sd for driving the motor from the control circuit 1 described later, and switches each switch element constituting the inverter circuit 2a to a switch state for detecting the initial position of the rotor based on the received initial position detection signal Pd. Specifically, based on the initial position detection signal Pd, each switch element constituting the inverter circuit 2a switches the energized sections in sequence without rotating the rotor of the motor 3, and turns on / off the high side switches Q1, Q3, Q5 and the low side switches Q2, Q4, Q6 of the inverter circuit 2a, and energizes and cuts off the energization direction of the coil corresponding to the energized section.

[0048] The initial position detection signal Pd is a signal for switching the switching elements constituting the inverter circuit 2a to a switch state for detecting the initial position of the rotor. The initial position detection signal Pd is different from the drive control signal Sd for driving the motor, and is not a signal for rotating the rotor of the motor 3. Therefore, it is not a signal (PWM signal) for alternately switching the on / off of each switching element, and is, for example, a high-level or low-level signal with a predetermined length. The initial position detection signal Pd includes six signals corresponding to the switching elements Q1 to Q6 of the inverter circuit 2a.

[0049] The pre-driving circuit 21 generates a driving signal as a switching signal for switching the switching state of each switching element constituting the inverter circuit 2 a based on the initial position detection signal Pd output from the control circuit 1 .

[0050] The pre-driving circuit 21 generates a signal capable of supplying enough power to switch the switching state of the control electrode (gate electrode) of each switching element Q1 to Q6 of the inverter circuit 2a based on the six signals as the initial position detection signal Pd supplied from the control circuit 1. The switching state of each switching element Q1 to Q6 is switched by inputting a driving signal as these switching signals to the control electrode (gate electrode) of each switching element Q1 to Q6 of the inverter circuit 2a.

[0051] Here, the case where the energized sections are sequentially switched without rotating the rotor of the motor 3 will be described.

[0052] Figure 3 , 4 This is a diagram for explaining the energized section in the motor 3 . Figure 3 2 is a diagram showing the switching state and current vector of the inverter circuit 2a in each energized section of the three-phase motor 3. Figure 4 It is a diagram showing the specific direction of the current vector.

[0053] like Figure 3As shown, in the case of the three-phase motor 3, there are six energized sections every 60 degrees. Based on the initial position detection signal Pd, the six energized sections are switched in sequence.

[0054] like Figure 3 As shown, when the energization method is one-phase excitation, in the energization section 1, the high-side switching element Q3 of the V phase and the low-side switching element Q6 of the W phase are turned on, and the current vector is in the direction of 270°. Similarly, it is shown that: in the power-on section 2, the switch element Q1 on the high side of the U phase and the switch element Q4 on the low side of the V phase are turned on, and the current vector is in the direction of 150°; in the power-on section 3, the switch element Q1 on the high side of the U phase and the switch element Q6 on the low side of the W phase are turned on, and the current vector is in the direction of 210°; in the power-on section 4, the switch element Q5 on the high side of the W phase and the switch element Q2 on the low side of the U phase are turned on, and the current vector is in the direction of 30°; in the power-on section 5, the switch element Q3 on the high side of the V phase and the switch element Q2 on the low side of the U phase are turned on, and the current vector is in the direction of 330°; in the power-on section 6, the switch element Q5 on the high side of the W phase and the switch element Q4 on the low side of the V phase are turned on, and the current vector is in the direction of 90°.

[0055] like Figure 3 As shown, it is shown that: when the power-on mode is 1-2 phase excitation, in the power-on section 1, the high-side switching elements Q3 and Q1 of the V and U phases and the low-side switching element Q6 of the W phase are turned on, and the current vector is in the direction of 240°. In the power-on section 2, the high-side switching elements Q1 and Q5 of the U and W phases and the low-side switching element Q4 of the V phase are turned on, and the current vector is in the direction of 120°. In the power-on section 3, the high-side switching element Q1 of the U phase and the low-side switching elements Q6 and Q4 of the W and V phases are turned on. The current vector is in the direction of 180°. In the power-on section 4, the high-side switch elements Q5 and Q3 of the W and V phases and the low-side switch element Q2 of the U phase are turned on, and the current vector is in the direction of 0°. In the power-on section 5, the high-side switch element Q3 of the V phase and the low-side switch elements Q2 and Q6 of the U and W phases are turned on, and the current vector is in the direction of 300°. In the power-on section 6, the high-side switch element Q5 of the W phase and the low-side switch elements Q4 and Q2 of the V and U phases are turned on, and the current vector is in the direction of 60°. It should be noted that in this embodiment, the following exemplifies the case where the power-on mode is a 1-2 phase excitation mode.

[0056] like Figure 3 As shown in FIG. 1 , it can be seen that when switching to one of the six energized sections, the current vector switches to Figure 4 in either direction shown.

[0057] In a normal motor drive, in a driving control signal Sd for driving a motor, the energized sections are switched in such a manner that the current vector gradually rotates every 60 degrees. For example, the energized sections are switched in the order of energized section 3, energized section 1, energized section 5, energized section 4, energized section 6, and energized section 2, and the switching element is energized. In the case of reversing the rotation direction of the motor, the order of the energized sections is reversed. In contrast, in the rotor initial position detection, the energized sections are switched in sequence without rotating the rotor of the motor 3, so that the energized sections are switched in such a manner that the current vector is eliminated. For example, the energized sections are switched in the order of energized section 3, energized section 4, energized section 6, energized section 1, energized section 5, and energized section 2. It should be noted that, for example, since the current vectors are relative, the energized sections 3 and energized sections 4 can also be regarded as bidirectional energization.

[0058] In addition, in the detection of the rotor initial position, the power supply in the power supply section is only carried out for the prescribed magnetic saturation time. Here, the magnetic saturation time is explained. When the coil of the motor 3 is energized, a magnetic field is gradually generated in the coil according to the length of the power supply time. However, due to the relationship between the magnetic pole positions of the rotor and the stator, the generated magnetic field has a limit, and the state of the coil where the generated magnetic field reaches the limit is called the state of reaching magnetic saturation. When the magnetic pole positions of the rotor and the stator are in a certain relationship, the speed of reaching magnetic saturation is fast through synergy. The time required for magnetic saturation when the magnetic pole positions of the rotor and the stator are in a certain relationship is defined as the prescribed magnetic saturation time, and the power supply time in the power supply section is set to the prescribed magnetic saturation time. Therefore, in the power supply section other than the position where the magnetic pole positions of the rotor and the stator are in a certain relationship, the speed of reaching magnetic saturation is slow, so magnetic saturation does not occur within the "prescribed magnetic saturation time". The prescribed magnetic saturation time may not be completely consistent with the time required for magnetic saturation when the magnetic pole positions of the rotor and the stator are in a certain relationship, and may also be adjusted within a range other than the position that can be identified as the magnetic pole positions of the rotor and the stator being in a certain relationship. When the magnetic saturation is reached, a large current flows through the coil, so the rotor initial position can be detected by measuring the "maximum current within a predetermined time".

[0059] Next, a description will be given of how the initial position of the rotor can be detected by estimating the position of the rotor based on the current flowing through the shunt resistor Rs when energizing and disconnecting the coil in the energizing direction corresponding to the energizing section.

[0060] As described above, when the coil of the motor 3 is energized, similarly to the motor drive, the shunt current Is flows toward the ground in the shunt resistor Rs of the current detection circuit 22. Conventionally, the position of the rotor is estimated based on the magnitude of the current value of the peak value of the shunt current Is. In contrast, in the motor drive control device 10 of the present embodiment, it is set to focus on the kickback current generated by the inductive kickback that flows toward the inverter circuit direction in the shunt resistor Rs of the current detection circuit 22 when the energization is cut off, and measure it as the negative value of the shunt current Is.

[0061] In each energized section, the current is cut off after energizing the coil in the energized direction, so that the current continues to flow in the energized direction of the coil. This current is in the same direction as when energized for the coil, but is in the inverting circuit direction on the opposite side of the grounding direction when energized for the shunt resistor Rs. The peak value of this magnitude is approximately equal to the peak value of the energized current. That is, in the case of a energized section where magnetic saturation occurs in the coil, the peak value of the kickback current detected in the inverting circuit direction in the opposite direction is larger than that of other energized sections, similar to the peak value of the energized current detected in the grounding direction of the shunt resistor Rs. Therefore, it can be seen that not only the peak value of the energized current in each energized section can be used to estimate the position of the rotor, but also the peak value of the kickback current can be used to estimate the position of the rotor.

[0062] Thus, in the motor drive control device 10 of the present embodiment, it is set that: the bidirectional current detection circuit 30 is used as the current detection circuit 22, and the position of the rotor is estimated based on the peak value of the energized current and the peak value of the kickback current in each energized section. When estimating the position of the rotor, the range of the current value to be detected is expanded, so the difference of the current measured in the energization within a specified time in each energized section becomes larger, and there is no need to increase the energized current in order to increase the difference of the current measured within a specified time in each energized direction, and the initial position of the rotor can be detected with a smaller current and higher accuracy. Therefore, in the motor drive control device 10 of the present embodiment, a detection device with a low resolution can be used. Even in the case where the coil is one-phase and switching elements are provided above and below both ends of the coil, the difference in the magnitude of the peak value of the energized current and the peak value of the kickback current in each energized section is also generated.

[0063] In the motor drive control device 10 of the present embodiment, in the initial position detection of the rotor, the current generated by the energization within a predetermined time is measured, so it is necessary to perform the detection when the rotor of the motor 3 is not idling. That is, in the motor drive control device 10 of the present embodiment, it is necessary to perform a rotor stop waiting process before implementing the initial position detection of the rotor. In this case, in addition to the driving of the motor 3 based on the drive control signal Sd and the initial position detection of the rotor based on the initial position detection signal Pd described above, there may also be a structure for determining that the rotor of the motor 3 is idling when the driving of the motor 3 is not performed by the drive control signal Sd. In the motor drive control device 10 of the present embodiment, by having a structure for determining the idling of the rotor, the initial position detection of the rotor can be performed after confirming that the rotor of the motor 3 is not idling.

[0064] In the motor drive control device 10 of the present embodiment, by switching the switching states of the switching elements Q1 to Q6 of the inverter circuit 2a, when the rotor of the motor 3 rotates, after an induced current circulates between the coil of the motor 3 and the inverter circuit 2a by the induced electromotive force, the inductive kickback generated in the inverter circuit 2a when the current path is cut off makes it determined that the rotor of the motor 3 is idling based on the kickback current flowing through the shunt resistor Rs.

[0065] In order to detect the idling of the rotor of the motor 3, in the motor drive control device 10 of the present embodiment, the drive circuit 2 receives an idling control signal Id different from the drive control signal Sd for driving the motor from the control circuit 1 described later, and switches each switch element constituting the inverter circuit 2a to a switch state for detecting the idling of the rotor of the motor 3 based on the received idling control signal Id. Specifically, based on the idling control signal Id, each switch element constituting the inverter circuit 2a is switched to a switch state corresponding to three modes (free mode, charging mode, and discharging mode). The three modes for detecting the idling of the rotor of the motor 3 will be described later.

[0066] The idling control signal Id is a signal for switching the switching elements constituting the inverter circuit 2a to switch states corresponding to the three modes for detecting the idling of the rotor of the motor 3. Unlike the drive control signal Sd for driving the motor, the idling control signal Id is not a signal for applying a drive voltage to the coil of the motor 3, and therefore is not a signal for alternately switching the on / off of each switching element, and is, for example, a high level or low level signal having a predetermined length. The idling control signal Id includes six signals corresponding to the switching elements Q1 to Q6 of the inverter circuit 2a.

[0067] The pre-driving circuit 21 generates a driving signal as a switching signal for switching the switching state of each switching element constituting the inverter circuit 2 a based on the idle control signal Id output from the control circuit 1 .

[0068] The pre-driving circuit 21 generates a signal capable of supplying enough power to switch the switching state of the control electrode (gate electrode) of each switching element Q1 to Q6 of the inverter circuit 2a based on the six signals as the idle control signal Id supplied from the control circuit 1. The switching state of each switching element Q1 to Q6 is switched by inputting a driving signal as these switching signals to the control electrode (gate electrode) of each switching element Q1 to Q6 of the inverter circuit 2a.

[0069] Here, the switch states corresponding to the three modes (free mode, charging mode, and discharging mode) for detecting the idling of the rotor of the motor 3 switched according to the idling control signal Id will be described.

[0070] Figures 5 to 7 1 is a diagram for explaining the states of each switch switched according to the idling control signal Id. Figures 5 to 7 , arrows indicate the state of current flowing through the coil of the motor 3 and the inverter circuit 2a when the rotor of the motor 3 is idling. The inverter circuit 2a is connected to a DC power supply Vin and is grounded via a shunt resistor Rs as a part of the current detection circuit 22.

[0071] Idle control signal Id is in free mode ( Figure 5 )、Charging Mode( Figure 6 )、Discharge Mode( Figure 7 Specifically, the idling control signal Id changes the switching state of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a from Figure 5 The first switching state shown (corresponding to the free mode) is switched to Figure 6 The second switch state shown (corresponding to the charging mode) and Figure 7 The diagram shows a switch back to the first switching state (corresponding to the discharge mode), whereby idling of the rotor of the motor 3 can be detected.

[0072] (Free Mode) After the power is turned on, when the idling control signal Id is output from the control circuit 1 according to the speed command signal Sc, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched to the first switching state according to the idling control signal Id output from the control circuit 1. Specifically, Figure 5 As shown, in the inverter circuit 2a, the switch states of the switch elements Q1 to Q6 are all switched to off.

[0073] like Figure 5As shown, in the first switching state, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, but due to the disconnection of each switching element Q1 to Q6 and the clamping of the parasitic diode, no current circulates between the coil of the motor 3 and the inverter circuit 2a. In addition, at this time, no current flows through the shunt resistor Rs.

[0074] (Charging Mode) Next, according to the idling control signal Id output from the control circuit 1, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched from the first switching state to the second switching state. The second switching state is a switching state in which when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, and the generated induced current circulates in a closed circuit formed by the coil and the switched elements Q1 to Q6 that are turned on. Specifically, in the inverter circuit 2a, for example, Figure 6 As shown, the first switching state in which all the switching elements Q1 to Q6 are turned off is switched to the second switching state in which only the switching elements Q2 , Q4 , and Q6 of the lower arm of the switching elements Q1 to Q6 are turned on.

[0075] like Figure 6 As shown, in the inverter circuit 2a, when the switch state of the switch elements Q2, Q4, and Q6 of the lower bridge arm of each switch element Q1 to Q6 is set to the second switch state of being turned on, when the rotor of the motor 3 is idling, an induced current that circulates between the coil of the motor 3 and the inverter circuit 2a is generated by the induced electromotive force in the coil of each phase, and the generated induced current circulates in the closed circuit formed by the coil and the switched lower bridge arm switch elements Q2, Q4, and Q6. In addition, at this time, since the shunt resistor Rs is not included in the closed circuit, no current flows through the shunt resistor Rs.

[0076] Specifically, when the rotor of the motor 3 is idling, the rotor rotates relative to the coil, and in the coil of each phase, an induced voltage (eu, ev, ew) proportional to the rotation speed is generated with a polarity in the direction of generating a current that hinders the change of the magnetic flux at an electrical angle period generated by the rotation of the rotor with each phase shifted by 120 degrees. At this time, the current waveform becomes a phase that is delayed by 90 degrees relative to the voltage waveform.

[0077] (Discharge Mode) Next, according to the idle control signal Id output from the control circuit 1, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched from the second switching state to the first switching state again. Figure 7As shown, the switching state of the switching elements Q2, Q4, and Q6 of the lower bridge arm of each switching element Q1 to Q6 is switched from the second switching state in which the switching states of the switching elements Q2, Q4, and Q6 are turned on to the first switching state in which the switching states of all the switching elements Q1 to Q6 are turned off.

[0078] like Figure 7 As shown in FIG. 1 , when the rotor of the motor 3 is idling, in the inverter circuit 2a, when the second switching state is changed to the first switching state, the path of the circulating induced current is cut off. At this time, in the winding (coil) of the motor 3, the induced current ( Figure 7 A) continues to flow, thus generating an inductive kickback in the inverter circuit 2a. In the short period of time until the voltage variation caused by the inductive kickback converges within the voltage range clamped by the parasitic diodes of each switching element Q1 to Q6, a voltage rise occurs at the connection point between the upper bridge arm and the lower bridge arm of the branch on the downstream side of the induced current, and the current flows from the coil to the power supply side via the parasitic diode of the switching element Q1 of the upper bridge arm. A voltage drop occurs at the connection point between the upper bridge arm and the lower bridge arm of the branch on the upstream side of the induced current, and the current flows from the ground to the coil via the parasitic diodes of the switching elements Q4 and Q6 of the lower bridge arm. The current ( Figure 7 B) flows from the ground of the shunt resistor Rs to the inverter circuit direction.

[0079] In the motor drive control device 10 of the present embodiment, the current detection circuit 22 detects the kickback current flowing through the shunt resistor Rs due to the inductive kickback generated in the inverter circuit 2a during the discharge mode, and when it is determined that a specified current has flowed, it can be determined that the rotor of the motor 3 is idling.

[0080] It should be noted that, in the above example, as the second switch state corresponding to the charging mode, Figure 6 As shown, the case where the switching state of the switching elements Q2, Q4, and Q6 of the lower arm of each switching element Q1 to Q6 of the inverter circuit 2a is turned on is described as an example, but the present invention is not limited to this.

[0081] As the second switching state, it also includes setting any two of the switching elements Q1, Q3, Q5 of the upper bridge arm of the switching elements Q1 to Q6 or the switching elements Q2, Q4, Q6 of the lower bridge arm to the on state. In this switching state, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, and the generated induced current circulates in a closed circuit formed by the coil and the turned-on transistors of the switching elements Q1 to Q6. That is, the second switching state can be said to be a switching state in which when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, and the generated induced current circulates in a closed circuit formed by the coil and the turned-on transistors of the switching elements Q1 to Q6.

[0082] On the other hand, when the switching state of any one of the switching elements Q1, Q3, Q5 of the upper bridge arm or the switching elements Q2, Q4, Q6 of the lower bridge arm of each switching element Q1 to Q6 is set to on, since there is no closed circuit at all, the induced current never circulates and is therefore not included in the second switching state.

[0083] return Figure 1 The current detection circuit 22 is a circuit for controlling the inverter circuit 2a during motor driving and rotor initial position detection, detecting the current flowing through the three-phase coils Lu, Lv, and Lw of the motor 3 and flowing toward the ground in the shunt resistor Rs, and detecting the kickback current flowing from the ground to the inverter circuit direction of the inverter circuit 2a in the shunt resistor Rs due to inductive kickback during rotor initial position detection and rotor idling detection. The current detection circuit 22 outputs a current detection signal Vs corresponding to the current flowing through the shunt resistor Rs to the control circuit 1.

[0084] In the motor driving, the control circuit 1 generates a drive control signal Sd for driving the motor 3 based on a speed command signal Sc input from the outside and indicating a target state of the action of the motor 3, and controls the driving of the motor 3. Specifically, the control circuit 1 generates the drive control signal Sd and provides it to the drive circuit 2 so that the motor 3 is in the action state specified by the speed command signal Sc.

[0085] In addition, the control circuit 1 generates an initial position detection signal Pd instead of the drive control signal Sd during the rotor initial position detection to detect the initial position of the rotor. Specifically, the control circuit 1 generates the initial position detection signal Pd and provides it to the drive circuit 2 so that each switching element Q1 to Q6 of the inverter circuit 2a becomes a switching state specified by the initial position detection signal Pd.

[0086] The control circuit 1 also generates an idling control signal Id instead of the drive control signal Sd in the rotor idling detection when the rotor stops waiting, and detects the idling of the rotor of the motor 3. Specifically, the control circuit 1 generates the idling control signal Id and provides it to the drive circuit 2 so that each switching element Q1 to Q6 of the inverter circuit 2a is in the switching state specified by the idling control signal Id.

[0087] In an embodiment, the control circuit 1 is, for example, a program processing device (e.g., a microcontroller) having the following structure: a processor such as a CPU (central processing unit), various storage devices such as a RAM (Random Access Memory), a ROM (Read-Only Memory), and peripheral circuits such as a counter (timer), an A / D (Analog To Digital) conversion circuit, a D / A (Digital To Analog) conversion circuit, a clock generation circuit, and an input / output I / F (Interface) circuit are interconnected via a bus and dedicated lines.

[0088] It should be noted that the motor drive control device 10 can be a structure in which at least a part of the control circuit 1 and at least a part of the drive circuit 2 are packaged into an integrated circuit device (IC), or a structure in which the control circuit 1 and the drive circuit 2 are separately packaged as independent integrated circuit devices.

[0089] Figure 8 1 is a diagram showing a functional block configuration of a control circuit 1 in a motor drive control device 10 according to the embodiment.

[0090] like Figure 8 As shown, the control circuit 1 includes, for example, a drive command acquisition unit 11, a state control unit 12, a vector control unit 13, a PWM signal generation unit 14, a timing adjustment unit 15, and a current measurement unit 16 as functional blocks for generating a drive control signal Sd in a motor drive based on vector control. The control circuit 1 includes an initial position detection unit 130 and a current measurement unit 16 as functional blocks for generating an initial position detection signal Pd in ​​rotor initial position detection. The initial position detection unit 130 includes an initial position detection signal generation unit 131, a peak current acquisition unit 132, and a position estimation unit 133. In addition, the control circuit 1 includes an idling detection unit 120 and a current measurement unit 16 as functional blocks for generating an idling control signal Id in rotor idling detection. The idling detection unit 120 includes a first switching unit 121a, a second switching unit 121b, and an idling determination unit 122.

[0091] These functional blocks are realized, for example, in a program processing device as the control circuit 1 by a processor executing various calculation processes according to a program stored in a memory and controlling peripheral circuits such as a counter and an A / D conversion circuit.

[0092] The drive command acquisition unit 11 receives a speed command signal Sc from the outside, and acquires a value specifying a target operation state of the motor 3 specified by the speed command signal Sc by analyzing the received speed command signal Sc.

[0093] The speed command signal Sc includes a value indicating a target state of the operation of the motor 3. The speed command signal Sc is a signal output from a host device for controlling the motor unit 100, which is provided outside the motor drive control device 10, for example.

[0094] In the embodiment, the speed command signal Sc specifies, for example, the rotation speed of the rotor of the motor 3. The speed command signal Sc includes a value ωref that is a target rotation speed (target rotation speed) of the rotor of the motor 3.

[0095] The speed command signal Sc is, for example, a PWM signal having a duty ratio corresponding to the target rotation speed ωref. The drive command acquisition unit 11 measures, for example, the duty ratio of the PWM signal of the speed command signal Sc and outputs a rotation speed corresponding to the measured duty ratio as the target rotation speed ωref.

[0096] The state control unit 12 directly outputs the target speed ωref to the vector control unit 13 during motor driving. The state control unit 12 inputs the initial position of the rotor detected by the initial position detection unit 130 described later to the vector control unit 13, and the vector control unit 13 can be used for the starting position of the rotor in the motor 3. In this way, a smooth motor start with low current consumption, vibration and noise can be achieved. When an idling determination signal described later is generated from the idling determination unit 122, the state control unit 12 can determine whether to adopt windmill starting or forced commutation starting as the starting method of the motor. It should be noted that although in Figure 8 Although not particularly shown, the vector control unit 13 and the state control unit 12 may also have a functional unit that executes this processing.

[0097] The state control unit 12 also generates a measurement trigger signal Tm and an idling trigger signal Ir in the rotor initial position detection and rotor idling detection, and generates a current measurement value Im based on the current detection signal Vs detected in the current detection circuit 22. Specifically, the state control unit 12 generates the measurement trigger signal Tm and the idling trigger signal Ir that turn on the switch of the sampling circuit 51 of the current measuring unit 16 described later at a predetermined timing, and provides them to the current measuring unit 16. It should be noted that although Figure 8Although not particularly shown, the state control unit 12 may further include a functional unit that executes processing for generating the measurement trigger signal Tm and the idling trigger signal Ir.

[0098] The vector control unit 13 generates voltage values ​​Vα and Vβ according to the target speed ωref and the current measurement value Im in accordance with the well-known vector control in the motor drive, and outputs them to the PWM signal generation unit 14 (space vector modulation circuit: SVM (Space Vector Modulation)). At this time, the current measurement value Im is subjected to the offset adjustment described later, and is processed into the winding current measurement values ​​Iu, Iv, and Iw according to the measurement timing of the drive control signal Sd and the timing signal St generated by the timing adjustment unit 15 described later.

[0099] During motor driving, the PWM signal generating unit 14 outputs a driving control signal Sd to the driving circuit 2 to perform PWM control on the driving circuit 2 , and outputs a PWM count signal Tc, which is a signal indicating the start of counting each PWM cycle in the PWM control, to the timing adjusting unit 15 .

[0100] The timing adjustment unit 15 starts the timing-generated counter in synchronization with the start of counting of each PWM cycle during the motor driving, triggering the current measurement unit 16 to measure the current generated by the energization during the driving. Specifically, the timing adjustment unit 15 outputs the drive trigger signal Tr to the current measurement unit 16 at the current taking timing synchronized with the energization based on the PWM count signal Tc output from the PWM signal generation unit 14.

[0101] The current measuring unit 16 performs A / D conversion on the current detection signal Vs corresponding to the winding currents Iu, Iv, and Iw based on the driving trigger signal Tr or the measuring trigger signal Tm during motor driving, and then performs offset adjustment described below to generate a current measurement value Im. The current measurement value Im is output to the vector control unit 13, which performs vector control according to the current values ​​of the three phases based on the timing signal St from the timing adjustment unit 15, and calculates the magnitude of the energization in the PWM signal generation unit 14.

[0102] Fig. 9 1 is a diagram showing a configuration example of the current measuring unit 16 included in the control circuit 1 of the motor drive control device 10. The current measuring unit 16 includes a sampling circuit 51, a D / A converter 52, a comparator 53, and an offset calculator 54.

[0103] Fig. 9The current measuring unit 16 performs A / D conversion on the current detection signal Vs corresponding to the current flowing through the shunt resistor Rs input from the current detection circuit 22 at a predetermined timing, and then performs offset adjustment described later to generate a current measurement value Im used in the control circuit 1. The current measurement value Im is a value corresponding to the current flowing through the shunt resistor Rs of the current detection circuit 22.

[0104] Specifically, Fig. 9 The sampling circuit 51 is composed of, for example, a switch and a capacitor, and switches the switch on / off according to the drive trigger signal Tr, the measurement trigger signal Tm, and the idling trigger signal Ir output from the timing adjustment unit 15 or the state control unit 12 of the control circuit 1, thereby performing A / D conversion on the current detection signal Vs, which is the output voltage of the current detection circuit 22, at a predetermined timing. The A / D conversion is performed by sampling during the sampling period by the sampling circuit 51 and quantization during the holding period by the D / A converter 52 and the comparator 53. Furthermore, the offset calculator 54 performs the offset adjustment described later on the value generated by the A / D conversion, and generates a current measurement value Im corresponding to the current flowing through the shunt resistor Rs. In the motor drive, the current measurement value Im is used as the current measurement values ​​Iu, Iv, and Iw of the winding by the vector control unit 13. In addition, in the rotor initial position detection, the current measurement value Im is used by the peak current acquisition unit 132 of the state control unit 12 described later of the control circuit 1. Furthermore, in the rotor idling detection, the current measurement value Im is used by the idling determination unit 122 of the state control unit 12 described later in the control circuit 1 .

[0105] Here, the offset adjustment is explained. The current detection circuit 22 can measure the bidirectional current flowing to the shunt resistor Rs. Therefore, in the bidirectional current detection circuit 30 of the current detection circuit 22, the voltage drop signal Vout in the shunt resistor Rs and the current detection signal Vs smoothed by the delay circuit 31 are offset by the DC power supply Vdc / 2. Therefore, in the current measuring unit 16, when no current flows through the shunt resistor Rs, the current measurement value Im is a value other than 0. By performing the offset adjustment, if the current measurement value Im in the state where no current flows through the shunt resistor Rs is set to zero, it is the same as the current measurement in the existing grounding direction (from the inverter circuit 2a toward the ground), and the current direction is further clarified by the positive and negative signs.

[0106] In order to perform offset adjustment, when no current flows through the shunt resistor Rs, the state control unit 12 performs A / D conversion on the current detection signal Vs input to the current measuring unit 16 in the free mode or the charging mode, obtains the offset value in advance, and uses the obtained offset value in the offset calculator 54 of the current measuring unit 16.

[0107] Specifically, the state control unit 12 outputs an idling trigger signal Ir that turns on the switch of the sampling circuit 51 of the current measuring unit 16 when in the free mode (the initial first switch state) or the charging mode (the second switch state), performs A / D conversion on the current detection signal Vs input from the current detection circuit 22, and preliminarily determines the current measurement value generated by disabling the offset calculator 54 as the offset value. It is also possible to repeatedly disable the offset calculator 54 to generate the current measurement value, and set the average value of the current measurement values ​​generated multiple times as the offset value. In the free mode or the charging mode, regardless of whether the rotor of the motor 3 is in an idling state, no current flows through the shunt resistor Rs of the current detection circuit 22, so the current detection signal Vs detected at this time can be used as a reference for the current zero and can be used as an offset used when generating the current measurement value Im.

[0108] This offset adjustment may be performed in the free mode immediately after the power is turned on or the speed command signal Sc is input, or may be performed in the charging mode after the speed command signal Sc is input.

[0109] In the rotor idling detection, when in the discharge mode, that is, when switching from the second switch state to the first switch state, the state control unit 12 outputs an idling trigger signal Ir to turn on the switch of the sampling circuit 51 to the current measuring unit 16 at a predetermined timing, instructing the measurement of the input current detection signal Vs, and performs A / D conversion on the input current detection signal Vs, and further performs offset adjustment to generate a current measurement value Im. The current measuring unit 16 outputs the generated current measurement value Im to the idling determination unit 122 of the state control unit 12.

[0110] The idling determination unit 122 determines whether the rotor of the motor 3 is idling based on the current measurement value Im generated by the current measurement unit 16, and generates an idling determination signal indicating the idling determination result. Specifically, the idling determination unit 122 compares a preset idling threshold with the current measurement value Im generated by the current measurement unit 16, and determines that the rotor of the motor 3 is idling when the current measurement value Im, which is the maximum on the negative side of the inverter circuit direction, is smaller than the idling threshold (large negative value).

[0111] When the rotor of the motor 3 is idling, an inductive kickback is generated at the timing of switching to the discharge mode, and the current flows from the ground to the inverter circuit direction of the inverter circuit 2a. When the rotor of the motor 3 is idling at high speed, the induced electromotive force increases according to the rotation speed, and the induced current in the charging mode increases, so the period of the inductive kickback becomes longer, and the kickback current flowing in the inverter circuit direction in the shunt resistor Rs becomes larger, so it is used for judgment. The idling judgment unit 122 can use, for example, a value based on the range from the current measurement value (small negative value) of the current flowing through the shunt resistor Rs due to the inductive kickback when the rotor of the motor 3 stops to the current measurement value (large negative value) of the current flowing through the shunt resistor Rs due to the inductive kickback when idling at the lowest rotation speed as the idling threshold.

[0112] In the state control unit 12, the idling detection unit 120 includes a first switching unit 121a, a second switching unit 121b, and an idling determination unit 122. The first switching unit 121a and the second switching unit 121b are functional blocks for generating an idling control signal Id in rotor idling detection. The idling determination unit 122 is a functional block for performing rotor idling determination.

[0113] In the idling detection unit 120, the first switching unit 121a generates a first idling control signal Id1 for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to a first switching state. In the idling detection unit 120, the second switching unit 121b generates a second idling control signal Id2 for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to a second switching state. The first and second idling control signals Id1 and Id2 (also referred to as "idling control signals Id" in this specification) generated by the first switching unit 121a and the second switching unit 121b of the idling detection unit 120 are output to the drive circuit 2.

[0114] In the idling detection unit 120, in order to achieve a switch state capable of performing rotor idling detection, after the power is turned on, the first idling control signal Id1 corresponding to the free mode is generated by the first switching unit 121a until the speed command signal Sc is received in the drive command acquisition unit 11. In the idling detection unit 120, thereafter, during the charging time (a period corresponding to the charging mode), the second idling control signal Id2 is generated by the second switching unit 121b. In the idling detection unit 120, then, during the discharging time (a period corresponding to the discharging mode), the first idling control signal Id1 is generated again by the first switching unit 121a. It should be noted that, after the discharging time, the first idling control signal Id1 corresponding to the free mode can also be generated by the first switching unit 121a.

[0115] The timing of transition from the free mode to the charging mode may be, for example, after the drive instruction acquisition unit 11 receives the speed instruction signal Sc.

[0116] The charging time can be set to a time that is 10 times the time constant specified by the winding resistance and inductance of the coil of the motor 3. The coil of the motor 3 has a winding resistance and an inductance, so it can be regarded as an RL series circuit, and the time until the winding current stabilizes is 10 times the time constant. For example, when the winding resistance is 0.44Ω and the inductance is 0.4333mH, the time constant is 1msec. In this case, the charging time can be set to 10msec. The longer the charging time, the clearer the judgment of the stop and idling of the rotor at low speed, but since the inverter circuit is in a short-circuit braking state, a shorter charging time is preferred in that the period of the rotor idling detection process is short.

[0117] Since the kickback current flowing in the direction of the inverter circuit in the shunt resistor Rs due to the inductive kickback attenuates and converges to zero, the discharge time only needs to be a time greater than the time constant of the delay circuit 31 in the current detection circuit 22. At this time, if the maximum current can be measured in the direction of the inverter circuit, it can be determined whether the rotor of the motor 3 is in an idling state, so it can also be set to reach the discharge time when the measured current in the direction of the inverter circuit becomes smaller. In addition, the discharge time can be set to a time greater than 0.5 times the time constant specified by the winding resistance and inductance of the coil of the motor 3. This is because 0.5 times the time constant is the timing when the kickback current flowing in the direction of the inverter circuit in the shunt resistor Rs converges to about 60% of the peak value due to attenuation, but in the discharge mode, it is sufficient to detect the maximum current in the direction of the inverter circuit in the shunt resistor Rs. For example, when the winding resistance is 0.44Ω and the inductance is 0.4333mH, the time constant is 1msec. In this case, the discharge time can be set to 0.5msec.

[0118] In the state control unit 12 , the initial position detection unit 130 includes an initial position detection signal generation unit 131 , a peak current acquisition unit 132 , and a position estimation unit 133 .

[0119] The initial position detection signal generating unit 131 turns on / off the high side switches Q1, Q3, Q5 and the low side switches Q2, Q4, Q6 of the inverter circuit 2a in a manner that sequentially switches the energized sections without rotating the rotor of the motor 3, thereby generating an initial position detection signal Pd that energizes and cuts off the energization direction of the coil corresponding to the energized section. The details of the initial position detection signal Pd will be described later.

[0120] The peak current acquisition unit 132 acquires the peak value of the current flowing toward the ground when energizing and the peak value of the kickback current caused by the inductive kickback flowing toward the inverter circuit when energizing for each energizing section based on the current detected in the bidirectional current detection circuit 30 when the initial position detection signal Pd is generated. The peak current acquisition unit 132 cooperates with the functional unit that performs the process of generating the measurement trigger signal Tm, and acquires the current measurement value Im measured by the current measurement unit 16 as the peak value of the current flowing and the peak value of the kickback current for each energizing section according to the measurement trigger signal Tm generated at the timing defined by the initial position detection signal Pd. The details of the specific timing will be described later.

[0121] The position estimation unit 133 estimates the position of the rotor based on the peak value of the current in each power-on section and the peak value of the kickback current. Specifically, the position estimation unit 133 compares the total current value of the peak value of the current in each power-on section and the peak value of the kickback current, and estimates that the position of the rotor is at the position corresponding to the power-on section with the largest total current value.

[0122] In the above estimation method in the position estimation unit 133, the total current value of the peak value of the energized current and the peak value of the kickback current are compared for each energized section, and it is sometimes difficult to determine that the total current value does not differ much and the total current value is the maximum. In this case, the position estimation unit 133 can perform the same method again to estimate the position of the rotor, but as an estimation method additional to the above estimation, the energized section corresponding to the initial position of the rotor can also be determined by performing the following two methods separately or in sequence.

[0123] As a first method of the additional estimation method, the position estimation unit 133 obtains the current-carrying section where the peak value of the current flowing toward the ground is the largest and the current-carrying section where the peak value of the kickback current generated by the inductive kickback flowing toward the inverter circuit is the largest. The position estimation unit 133 performs estimation as follows based on the number of the acquired current-carrying sections.

[0124] (1) When there is one energized section in which the peak value of the current flowing toward the ground is the largest, and there is one energized section in which the peak value of the recoil current generated by the inductive recoil flowing toward the inverter circuit is the largest, and when these are the same energized sections, it is estimated that the position of the rotor is at a position corresponding to the same energized section.

[0125] (2) When there is one energization section where the peak value of the current flowing toward the ground is the largest, and there is one energization section where the peak value of the kickback current generated by the inductive kickback flowing toward the inverter circuit is the largest, and these are different energization sections, the rotor initial position detection process is re-executed.

[0126] (3) When there is one energized section where the peak value of the current flowing in the direction of grounding is the largest, and there are multiple energized sections where the peak value of the recoil current generated by the inductive recoil flowing in the direction of the inverter circuit is the largest, and one energized section is included where the peak value of the current is the largest, it is estimated that the position of the rotor is at a position corresponding to the energized section where the peak value of the current is the largest.

[0127] (4) When there is one energized section where the peak value of the current flowing toward the ground is the largest, and there are multiple energized sections where the peak value of the recoil current generated by the inductive recoil flowing toward the inverter circuit is the largest, and the energized section where the peak value of the current is the largest is not included, the rotor initial position detection process is re-executed.

[0128] (5) When there are multiple energized sections where the peak value of the current flowing in the direction of grounding is the largest, and there are multiple energized sections where the peak value of the recoil current generated by the inductive recoil flowing in the direction of the inverter circuit is the largest, and when there is a common energized section, it is estimated that the position of the rotor is at a position corresponding to the common energized section.

[0129] (6) When there are multiple energized sections where the peak value of the energized current flowing in the grounding direction is the largest, and there are multiple energized sections where the peak value of the recoil current generated by the inductive recoil flowing in the inverter circuit direction is the largest, and when there are no common energized sections, the rotor initial position detection process is re-executed.

[0130] As a second method of the additional estimation method, the position estimation unit 133 uses the total current value for each energized section, and further obtains the difference of the current of three bidirectional energizations according to the "total current value" of each energized section, wherein the total current value is the current value obtained by summing the peak value of the energized current flowing in the ground direction and the peak value of the kickback current generated by the inductive kickback flowing in the inverter circuit direction. When the maximum value of the difference of the current of the three bidirectional energizations is one, it is estimated that the position of the rotor is at the position corresponding to the energized section with the larger "total current value" among the two energized sections of the bidirectional energization that become the maximum value. Specifically, the three bidirectional energizations refer to three combinations of energized sections 4 and energized sections 3, energized sections 2 and energized sections 5, and energized sections 1 and energized sections 6, where the current vectors are 180 degrees to each other. At this time, for example, the difference dIu of the current of the bidirectional energization of the energization section 4 and the energization section 3 is the difference between the total current value of the energization section 4 and the total current value of the energization section 3. The other bidirectional energizations are calculated in the same way, and the differences dIu, dIv, and DIw of the three bidirectional energization currents are obtained. Next, the largest difference of the bidirectional energization current among the differences of the three bidirectional energization currents is determined, and it is estimated that the position of the rotor is at a position corresponding to the energization section with a larger "total current value" among the two determined bidirectional energization sections. For example, when the largest value of the difference of the three bidirectional energization currents is dIu, it is estimated that the position of the rotor is at a position corresponding to the energization section with a larger "total current value" among the energization sections 4 and 3. In addition, when the maximum difference of the three bidirectionally energized currents is two and the "total current value" of the four bidirectionally energized segments is different, it can also be estimated that the position of the rotor is at the position corresponding to the energized segment with the largest "total current value".

[0131] Next, the mode transition when the idling detection unit 120 performs rotor idling detection in order to confirm that the rotor of the motor 3 has stopped after the power is turned on will be described in detail. In the state control unit 12, after confirming that the result of the rotor idling detection is that the rotor is not idling (rotor stop waiting) in the idling detection unit 120, the initial position detection unit 130 performs the rotor initial position detection.

[0132] Fig.10 and Fig.11 1 is a timing chart showing an example of a signal waveform from when the motor unit 100 is powered on and the speed command signal Sc is input to when the rotor idling detection is completed. Fig.10 is the timing diagram when the rotor of motor 3 is completely motionless, Fig.11 This is a timing chart when the rotor of the motor 3 is moving (idling).

[0133] exist Fig.10 and Fig.11, the speed command signal Sc, the drive signals input to the gates of the switching elements Q1 to Q6, the idling trigger signal Ir for controlling the switch of the sampling circuit 51 in the current measuring unit 16, the shunt current Is detected in the shunt resistor Rs of the current detection circuit 22, and the waveforms of the winding current of the U phase are shown in order from top to bottom. It should be noted that the shunt current Is is the current flowing through the shunt resistor Rs of the current detection circuit 22, and is the current equivalent to the current detection signal Vs.

[0134] like Fig.10 and Fig.11 As shown in FIG. 1 , the motor drive control device 10 passes through the free mode, the charging mode, the discharging mode, and then returns to the free mode. At this time, the motor drive control device 10 starts from the free mode after the power is turned on. It should be noted that in Fig.10 and Fig.11 In the timing chart shown, the case where the free mode is entered again after the discharge mode is taken as an example, but the present invention is not limited to this.

[0135] In the free mode, the inverter circuit 2a is set to the first switch state according to the first idling control signal Id1 generated by the first switching unit 121a. Specifically, according to the first idling control signal Id1, the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a are all low-level, and all the switches of the inverter circuit 2a are turned off. In this state, regardless of whether the rotor of the motor 3 is in an idling state or not, a closed circuit is not formed between the coil of the motor 3 and the inverter circuit 2a, so the current of the coil of the motor 3 is zero. In addition, no current flows through the shunt resistor Rs.

[0136] In addition, Fig.10 and Fig.11 In the example of FIG. 1 , in the free mode, the idling trigger signal Ir for measuring the shunt current Is is at a low level. However, during this period, the idling trigger signal Ir may be set to a high level at a predetermined timing. In this case, the current measuring unit 16 obtains the current detection signal Vs output from the current detection circuit 22, which can be used as an offset because no current flows through the shunt resistor Rs.

[0137] Next, in the charging mode, the inverter circuit 2a is set to the second switch state according to the second idle control signal Id2 generated by the second switching unit 121b. Specifically, according to the second idle control signal Id2, the gate drive signals of the switch elements Q2, Q4, and Q6 of the lower bridge arm among the switch elements Q1 to Q6 constituting the inverter circuit 2a are all set to high level, and all the low-side switches of the inverter circuit 2a are turned on.

[0138] In this state, when the rotor of the motor 3 does not move at all, Fig.10As shown in FIG. 1 , similarly to the free mode, no current flows through the coil of the motor 3 and the shunt resistor Rs. On the other hand, when the rotor of the motor 3 moves, an induced electromotive force is generated in the coil of the motor 3, as shown in FIG. Fig.11 As shown, a closed circuit is formed by the coil of the motor 3 and the switching elements Q2, Q4, and Q6 connected in the inverter circuit 2a, and a current circulates between the coil of the motor 3 and the inverter circuit 2a. An induced current corresponding to the rotation of the rotor of the motor 3 flows through the coil, but at this time, since the shunt resistor Rs is not included in the closed circuit, no current flows through the shunt resistor Rs.

[0139] In addition, Fig.10 and Fig.11 In the example, in the charging mode, the idling trigger signal Ir for measuring the shunt current Is is at a low level. However, during this period, it can also be at a high level at a specified timing. In this case, the current measuring unit 16 obtains the current detection signal Vs output from the current detection circuit 22, and since no current flows through the shunt resistor Rs, it can be used as an offset. It should be noted that when the offset is obtained in the free mode, the offset can be obtained again without the timing.

[0140] Next, in the discharge mode, the inverter circuit 2a is put into the first switch state again according to the first idle control signal Id1 generated by the first switching unit 121a. Specifically, according to the first idle control signal Id1, the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a are all low level again, and all switches of the inverter circuit 2a are turned off.

[0141] In this state, when the rotor of the motor 3 moves (idling), during this period, the current circulating between the coil of the motor 3 and the inverter circuit 2a continues to flow through the coil, so that all the switching elements are turned off, and an inductive kickback is generated in the inverter circuit. Due to this inductive kickback, a current that increases from the ground to the inverter circuit direction of the inverter circuit 2a is instantly generated in the shunt resistor Rs and converges to zero. At this time, the current flowing through the shunt resistor Rs is detected by the current detection circuit 22, and the current measurement unit 16 continuously measures the maximum current in the inverter circuit direction. Therefore, although the rotation direction of the rotor of the motor 3 cannot be determined, it can be determined in a short time that the rotor of the motor 3 is idling.

[0142] In addition, in the discharge mode, when the current masking time exceeds the predetermined masking time, the idle trigger signal Ir for measuring the shunt current Is becomes high level at a predetermined timing. The predetermined masking time is set to a period for removing the electromagnetic noise generated by the switch of the inverter circuit 2a caused by the switching of the drive signal. When the current masking time exceeds the predetermined masking time, the current measuring unit 16 obtains the current detection signal Vs output from the current detection circuit 22 and measures the current flowing through the shunt resistor Rs.

[0143] exist Fig.11 , the shunt current Is and the U-phase winding current in two states are shown. In the case of a low speed caused by the idling of the rotor, the U-phase winding current (dashed line) has a long period and a small amplitude in the charging mode, and a small shunt current (dashed line) is generated on the negative side as the inverter circuit direction due to the inductive kickback in the discharge mode, and the kickback current flowing in the inverter circuit direction of the shunt resistor Rs is small. On the other hand, in the case of a high speed caused by the idling of the rotor, the U-phase winding current (single-dot chain line) in the charging mode has a short period and a large amplitude, and a large shunt current (single-dot chain line) is generated on the negative side due to the inductive kickback in the discharge mode, and the kickback current flowing in the inverter circuit direction of the shunt resistor Rs is large. In either case, the maximum current of the shunt current Is observed by the idling determination unit 122 in the inverter circuit direction is smaller than the idling threshold (double-dot chain line) for determining the idling of the rotor (large negative value), so it is determined that the rotor of the motor 3 is idling. When it is determined to be idling, the stop of the rotor can also be confirmed by regularly repeating the rotor idling detection. At this time, in order to shorten the time until the rotor stops, the inverter circuit can also be regularly put into a short-circuit braking state.

[0144] Next, the details of energization / disconnection of each energized section when the initial position detection unit 130 performs rotor initial position detection from a state where the rotor is stopped (state where the rotor is not idling) will be described.

[0145] Fig.12 , Fig.13 Each of them is a timing chart showing an example of a signal waveform after the motor unit 100 is powered on, the speed command signal Sc is input, and the rotor is confirmed to be stopped, until the rotor initial position detection is completed. Fig.14 This is a timing diagram showing another example of the signal waveform of power on / off in one power-on section in the rotor initial position detection after the motor unit 100 is powered on, the speed command signal Sc is input, and after the rotor stops, it is confirmed. In this embodiment, the case where the power-on method is a 1-2 phase excitation method is taken as an example for description.

[0146] exist Figure 12 to Figure 14In FIG. 1 , from top to bottom, the speed command signal Sc, the drive signals input to the gates of the switching elements Q1 to Q6, the measurement trigger signal Tm for controlling the switch of the sampling circuit 51 in the current measuring unit 16, and the shunt current Is detected in the shunt resistor Rs of the current detection circuit 22 are shown in sequence. It should be noted that the shunt current Is is the current flowing through the shunt resistor Rs of the current detection circuit 22, and is the current equivalent to the current detection signal Vs. Fig.10 , Fig.11 The idling trigger signal Ir and the shunt current Is in the rotor idling detection until the rotor stops are described in , so they are omitted here.

[0147] As the methods of energizing / disconnecting each energized section, there are [1: normal method], [2: complementary disconnection method], and [3: silent method], so each method will be described separately. Fig.12 This is the usual timing diagram. Fig.13 This is the timing diagram of the complementary cut-off mode. Fig.14 It is a timing diagram of the mute mode.

[0148] [1: Normal method] like Fig.12 As shown, in the normal mode, the motor drive control device 10 switches the energized section while returning to the free mode through the energized mode and the cut-off mode. Fig.12 In the timing chart shown, the case where the free mode is entered after the last cut-off mode is taken as an example, but the present invention is not limited to this.

[0149] First, the power-on section 3 is powered on according to the power-on mode. In the power-on section 3, Figure 3 As shown, the current is energized in a manner that the current flows from the U phase to the V phase and the W phase. Specifically, the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q1, Q4, and Q6 during the prescribed magnetic saturation time (t10 to t12), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t11) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 3 can be obtained.

[0150] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q1, Q4, and Q6 from on to off. When the current masking time exceeds the prescribed masking time (t13) from the timing (t12) at which the switch elements Q1, Q4, and Q6 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it stops outputting the pulse of the measurement trigger signal Tm (t19). Thus, the peak value of the shunt current Is (rebound current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 3 can be obtained, and it can also be known that the shunt current Is has returned to zero again. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it notifies the initial position detection signal generating unit 131 of the situation. The initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to 0 by receiving the notification. By utilizing the fact that the shunt current has converged to 0, the next current measurement becomes accurate, and the measurement time per energization section can be shortened.

[0151] Next, the energizing section 4 is energized according to the energizing mode. In the energizing section 4, Figure 3 As shown, the current is energized in a manner that the current flows from the V phase to the W phase to the U phase. Specifically, after confirming that the magnitude of the kickback current has converged to zero (t19), the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q2, Q3, and Q5 during the prescribed magnetic saturation time (t20 to t22), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t21) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 4 can be obtained.

[0152] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q2, Q3, and Q5 from on to off. When the current masking time exceeds the prescribed masking time (t23) from the timing (t22) at which the switch elements Q2, Q3, and Q5 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it stops outputting the pulse of the measurement trigger signal Tm (t29). Thus, the peak value of the shunt current Is (recoil current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 4 can be obtained, and it can also be known that the shunt current Is has returned to zero again. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it notifies the initial position detection signal generating unit 131 of the situation. The initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero by receiving this notification.

[0153] Next, the energizing section 6 is energized according to the energizing mode. In the energizing section 6, Figure 3 As shown, the current is energized in a manner that the current flows from the W phase to the U phase and the V phase. Specifically, after confirming that the magnitude of the kickback current has converged to zero (t29), the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q2, Q4, and Q5 during the prescribed magnetic saturation time (t30 to t32), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t31) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 6 can be obtained.

[0154] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q2, Q4, and Q5 from on to off. When the current masking time exceeds the prescribed masking time (t33) from the timing (t32) at which the switch elements Q2, Q4, and Q5 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When the peak current acquiring unit 132 confirms that the shunt current Is has roughly converged to zero, it stops outputting the pulse of the measurement trigger signal Tm (t39). Thus, the peak value of the shunt current Is (rebound current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 6 can be obtained, and it can also be known that the shunt current Is returns to zero again. When the peak current acquiring unit 132 confirms that the shunt current Is has roughly converged to zero, it notifies the initial position detection signal generating unit 131 of the situation. The initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero by receiving this notification.

[0155] Next, the power-on segment 1 is powered on according to the power-on mode. In the power-on segment 1, if Figure 3 As shown, the current is energized in a manner that the current flows from the U phase to the V phase to the W phase. Specifically, after confirming that the magnitude of the kickback current has converged to zero (t39), the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q1, Q3, and Q6 during the prescribed magnetic saturation time (t40 to t42), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t41) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 1 can be obtained.

[0156] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q1, Q3, and Q6 from on to off. When the current masking time exceeds the prescribed masking time (t43) from the timing (t42) at which the switch elements Q1, Q3, and Q6 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it stops outputting the pulse of the measurement trigger signal Tm (t49). Thus, the peak value of the shunt current Is (recoil current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 1 can be obtained, and it can also be known that the shunt current Is has returned to zero again. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it notifies the initial position detection signal generating unit 131 of the situation. The initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero by receiving this notification.

[0157] Next, the power-on section 5 is powered on according to the power-on mode. In the power-on section 5, Figure 3 As shown, the current is energized in a manner that the current flows from the V phase to the W phase and the U phase. Specifically, after confirming that the magnitude of the kickback current has converged to zero (t49), the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q2, Q3, and Q6 during the prescribed magnetic saturation time (t50 to t52), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t51) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 5 can be obtained.

[0158] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q2, Q3, and Q6 from on to off. When the current masking time exceeds the prescribed masking time (t53) from the timing (t52) at which the switch elements Q2, Q3, and Q6 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it stops outputting the pulse of the measurement trigger signal Tm (t59). Thus, the peak value of the shunt current Is (rebound current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 5 can be obtained, and it can also be known that the shunt current Is returns to zero again. When the peak current acquiring unit 132 confirms that the shunt current Is has converged to approximately zero, it notifies the initial position detection signal generating unit 131 of the situation. The initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero by receiving this notification.

[0159] Next, the power-on segment 2 is powered on according to the power-on mode. In the power-on segment 2, Figure 3 As shown, the current is energized in a manner that the current flows from the W phase to the U phase to the V phase. Specifically, after confirming that the magnitude of the kickback current has converged to zero (t59), the initial position detection signal generating unit 131 generates the initial position detection signal Pd that turns on the switch elements Q1, Q4, and Q5 during the prescribed magnetic saturation time (t60 to t62), and the peak current acquiring unit 132 considers the sampling time of the A / D conversion in the current measuring unit 16, and outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t61) slightly before the current energization time passes the prescribed magnetic saturation time. In this way, the peak value of the shunt current Is (energization current) flowing in the shunt resistor Rs toward the ground direction when energizing in the energization section 2 can be acquired.

[0160] When the current power-on time exceeds the prescribed magnetic saturation time, the initial position detection signal generating unit 131 changes to the cut-off mode and generates the initial position detection signal Pd for changing the switch elements Q1, Q4, and Q5 from on to off. When the current masking time exceeds the prescribed masking time (t63) from the timing (t62) at which the switch elements Q1, Q4, and Q5 are turned off, the peak current acquiring unit 132 starts to output the pulse of the measurement trigger signal Tm to the current measuring unit 16. When confirming that the shunt current Is has converged to approximately zero, the peak current acquiring unit 132 stops outputting the pulse of the measurement trigger signal Tm. In this way, the peak value of the shunt current Is (recoil current) flowing in the shunt resistor Rs in the direction of the inverter circuit at the time of the cut-off in the power-on section 2 can be obtained, and it can also be known that the shunt current Is returns to zero again.

[0161] When the current measurement is completed in all the energizing sections, the mode is switched to the free mode, and the rotor position is estimated based on the total current value of the peak value of the energizing current and the peak value of the kickback current in each energizing section, and the rotor initial position detection is completed.

[0162] [2: Complementary cutting method] like Fig.13 As shown in FIG. 1 , the complementary cutoff mode is different in that, in the complementary cutoff mode instead of the cutoff mode in the normal mode, a signal for switching the gates of the switching elements Q1 to Q6 is input so that the kickback current generated by the inductive kickback is changed from passing through the parasitic diode of the switching element to passing through the on-resistance. Fig.12 The same general approach is shown, so only Fig.12 The points different from the usual method shown are explained below.

[0163] In order to make the kickback current pass through the on-resistance of the switch element, among the switch elements Q1 to Q6 of the inverter circuit 2a, it is sufficient to turn on the switches that are in a complementary relationship with respect to the time of power-on. Specifically, after the dead time period for preventing the upper and lower short circuits of the switch elements, a signal for switching the gates of the switch elements Q1 to Q6 is input so that the switches that are in a complementary relationship with respect to the time of power-on are turned on. That is, in the power-on section 3 as the initial power-on section, in the complementary cut-off mode, the switch elements Q2, Q3, and Q5 are turned on in the same manner as in the power-on section 4. In the complementary cut-off mode, when it is confirmed that the shunt current Is has converged to approximately zero, the on-state of the switch elements Q2, Q3, and Q5 for making the kickback current pass through the on-resistance of the switch elements is released (disconnected).

[0164] Similarly, when the energizing section 4 is the next energizing section, in the complementary cutoff mode, the switch elements Q1, Q4, and Q6 are turned on in the same manner as the energizing section 3. When the energizing section 6 is the next energizing section, in the complementary cutoff mode, the switch elements Q1, Q3, and Q6 are turned on in the same manner as the energizing section 1. When the energizing section 1 is the next energizing section, in the complementary cutoff mode, the switch elements Q2, Q4, and Q5 are turned on in the same manner as the energizing section 6. When the energizing section 5 is the next energizing section, in the complementary cutoff mode, the switch elements Q1, Q4, and Q5 are turned on in the same manner as the energizing section 2. When the energizing section 2 is the next energizing section, in the complementary cutoff mode, the switch elements Q2, Q3, and Q6 are turned on in the same manner as the energizing section 5.

[0165] According to this configuration, when the inverter circuit is turned off, the kickback current caused by the inductive kickback generated in the inverter circuit changes from passing through the parasitic diode of the switching element to passing through the on-resistance, so the time for the shunt current Is to converge to zero can be shortened. As a result, the measurement time of each energization section and the time required for energization in all six directions for detecting the rotor initial position can be shortened.

[0166] [3: Silent mode] like Fig.14 As shown, in the normal power-on mode, a pulse with a continuous length is generated as a drive signal during the specified magnetic saturation time, but in the silent power-on mode, the difference is that the specified magnetic saturation time is divided into a plurality of pulses of shorter lengths, and the signal of the gate of the switching element Q1 to Q6 is input to gradually form a magnetic field in the coil. That is, in the silent power-on mode, the power-on is divided into a plurality of specified times, and the power-on is repeatedly performed with a small current, thereby increasing the current flowing through the coil while performing the power-on. Other structures and Fig.12 The same general approach is shown, so only Fig.12 It should be noted that a complementary cut-off mode may be used instead of a cut-off mode.

[0167] exist Fig.14 In the power-on mode, the high-side switch element is turned on / off by PWM driving, and the low-side switch element is always turned on. In the power-on mode where the high and low sides are turned on at the same time, current flows through the coil and the shunt resistor, and while the high-side switch element is turned off, a circulating current is generated that circulates through the low-side switch element and the coil. This circulating current delays the attenuation of the current flowing through the coil, thereby reducing the current per power-on and reducing magnetic noise. At this time, Fig.14 In , the low-side switching element is turned on simultaneously with the high-side switching, but it can also be turned on simultaneously with the start of the power-on mode (dashed line). Fig.14 In the description, one energized section is cited as an example for explanation, but other energized sections are also divided into a plurality of shorter pulses to generate driving signals.

[0168] According to this structure, the magnetic sound such as "clicking" caused by power supply can be avoided. Fig.14 In the power-on mode, the high-side switch element is turned on / off by PWM driving, and the low-side switch element is turned on, but the present invention is not limited to this. For example, the high-side switch element may be turned on, and the low-side switch element may be driven by PWM. Moreover, although the duty cycle of the PWM drive is set to be constant, the present invention is not limited to this. For example, the duty cycle of the PWM drive may be gradually increased.

[0169] Next, a description will be given of a flow of processing performed by the control circuit 1 from when the power is turned on to when the motor is started in the motor drive control device 10 according to the embodiment.

[0170] Fig.15 This is a flowchart showing an example of the flow of processing when the power is turned on in the control circuit 1 of the motor drive control device 10 according to the embodiment. Fig.16 1 is a flowchart showing an example of the flow of the offset measurement process performed by the control circuit 1 of the motor drive control device 10 . Fig.17 1 is a flowchart showing an example of the flow of the rotor stop waiting process performed by the control circuit 1 of the motor drive control device 10 . Fig.18 1 is a flowchart showing an example of the flow of the rotor initial position measurement process performed by the control circuit 1 of the motor drive control device 10 . Fig.19 1 is a flowchart showing an example of the flow of the rotor initial position measurement process in the energized section n performed by the control circuit 1 of the motor drive control device 10 .

[0171] First, when the power is turned on in the motor drive control device 10, Fig.15 As shown, in the state control unit 12, the free mode is selected (step S110), and the first switching unit 121a generates a first idling control signal Id1 for switching to a first switching state, so that the switching elements Q1 to Q6 constituting the inverter circuit 2a are in a switching state corresponding to the free mode (all FETs are disconnected) (step S111).

[0172] The state control unit 12 generates a first idling control signal Id1 for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switching state according to the first idling control signal Id1 generated in step S111. Figure 5 As shown, the switching elements Q1 to Q6 constituting the inverter circuit 2a are in the first switching state in response to the first free-wheeling control signal Id1.

[0173] Next, the state control unit 12 executes an offset measurement process (step S200 ).

[0174] When the state control unit 12 starts the offset measurement process, Fig.16 As shown, first, the counter of the number of offset measurements is reset to zero, and the offset calculator 54 is disabled (step S201).

[0175] Next, the state control unit 12 outputs the idling trigger signal Ir, controls the switch of the sampling circuit 51 of the current measuring unit 16, performs A / D conversion on the current detection signal Vs output from the current detection circuit 22, and generates a current measurement value Im corresponding to the current flowing through the shunt resistor Rs (step S202). It should be noted that the shunt current Is at this time is zero, but due to the voltage that offsets the output of the amplifier of the bidirectional current detection circuit 30, the current measurement value Im becomes a value other than zero.

[0176] When the shunt current measurement in step S202 is completed, the state control unit 12 increments the counter of the number of offset measurements by "+1" (step S203).

[0177] The state control unit 12 checks the counter of the number of deviation measurements, and determines whether the current number of deviation measurements exceeds a predetermined number of deviation measurements (step S204 ).

[0178] If the current offset measurement number does not exceed the prescribed offset measurement number (step S204: No), the process returns to step S202. On the other hand, if the current offset measurement number exceeds the prescribed offset measurement number (step S204: Yes), the average value of the values ​​obtained in the measurement of step S202 is obtained as the offset value, and the offset calculator 54 is enabled (step S205). Through this offset adjustment, the current measurement value Im is zero when no current flows through the shunt resistor Rs, is a positive value when the current flows in the grounding direction of the shunt resistor Rs, and is a negative value when the current flows in the inverter circuit direction.

[0179] return Fig.15 After the offset measurement in step S200, the state control unit 12 determines whether the drive instruction acquisition unit 11 has received the speed instruction signal Sc from the host device (step S120).

[0180] When it is determined that the speed command signal Sc has not been received (step S120 : No), the re-determination of step S120 is performed immediately after a predetermined time has passed.

[0181] When it is determined that the speed command signal Sc is received (step S120 : Yes), the rotor stop waiting is executed (step S300 ).

[0182] During the rotor stop waiting in S300, since the switch state is already the first switch state corresponding to the free mode, in the state control unit 12, as shown in FIG. Fig.17As shown, first, the charging mode is selected (step S310), and the second switching unit 121b generates a second idling control signal Id2 that switches to the second switch state corresponding to the charging mode (all LO side FETs are turned on). At this time, in the state control unit 12, the charging time is reset (step S311).

[0183] The state control unit 12 generates a second idling control signal Id2 for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the second switching state according to the second idling control signal Id2 generated in step S310. Figure 6 As shown, the switching elements Q1 to Q6 constituting the inverter circuit 2a are in the second switching state in response to the second free-wheeling control signal Id2.

[0184] In the state control unit 12, the second switching unit 121b determines whether the current charging time has passed a predetermined charging time after the second idle control signal Id2 is generated in step S311 (step S312).

[0185] In the state control unit 12, when the current charging time has passed the prescribed charging time after the second switching unit 121b generates the second idle control signal Id2 (step S312: Yes), the state control unit 12 changes to the discharge mode (step S320), and the first switching unit 121a generates the first idle control signal Id1 that switches to the first switch state (all FETs are off) corresponding to the discharge mode. At this time, the state control unit 12 resets the discharge time and the masking time (step S321).

[0186] The state control unit 12 switches the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switching state by generating the first idle control signal Id1 generated in step S321. Figure 7 As shown, the switching elements Q1 to Q6 constituting the inverter circuit 2a respond to the first free-wheeling control signal Id1 and are in the first switching state again.

[0187] The state control unit 12 determines whether the current masking time has exceeded a predetermined masking time (step S322). When the current masking time has exceeded the predetermined masking time (step S322: Yes), the state control unit 12 executes the shunt current measurement process (step S323).

[0188] In the shunt current measurement process of step S323, the state control unit 12 outputs the idling trigger signal Ir to the current measuring unit 16, controls the switch of the sampling circuit 51 of the current measuring unit 16, performs A / D conversion on the current detection signal Vs output from the current detection circuit 22, and then performs offset adjustment to generate the current measurement value Im. The current measuring unit 16 outputs the current measurement value Im to the idling determination unit 122 of the state control unit 12. The current measurement value Im corresponds to the current flowing through the shunt resistor Rs of the current detection circuit 22.

[0189] The idling determination unit 122 of the state control unit 12 determines whether the absolute value of the current measurement value Im is less than the threshold current value of the idling threshold value (step S324). When the state control unit 12 determines that the absolute value of the current measurement value Im is less than the threshold current value (step S324: Yes), since the rotor is in a stopped state, the rotor stop waiting process is terminated and the mode is switched to the free mode (step S330). On the other hand, when the state control unit 12 determines that the absolute value of the current measurement value Im is not less than the threshold current value (step S324: No), since the rotor is in an idling state, the rotor stop waiting process (step S324) is executed again.

[0190] return Fig.15 The state control unit 12 sequentially performs rotor initial position measurement (step S400 ) and rotor initial position estimation (step S500 ) for performing rotor initial position detection in the initial position detection unit 130 .

[0191] like Fig.18 As shown, in the rotor initial position measurement (step S400), when the initial position detection signal generating unit 131 of the initial position detecting unit 130 generates the initial position detection signal Pd for energizing / disconnecting each energizing section, the switching elements Q1 to Q6 of the inverter circuit 2a are turned on and off to energize / disconnect the coil. The peak current acquiring unit 132 of the initial position detecting unit 130 acquires the current measurement value Im of the current measuring unit 16 at a predetermined timing to perform current measurement of all energizing sections. In this embodiment, specifically, rotor initial position measurement 1 (step S601) is performed on the energized segment 3, rotor initial position measurement 2 (step S602) is performed on the energized segment 4 in sequence, rotor initial position measurement 3 (step S603) is performed on the energized segment 6, rotor initial position measurement 4 (step S604) is performed on the energized segment 1, rotor initial position measurement 5 (step S605) is performed on the energized segment 5, and rotor initial position measurement 6 (step S606) is performed on the energized segment 2.

[0192] like Fig.19As shown, in the rotor initial position measurement n which is the rotor initial position measurement in a power-on section (step S600), in the initial position detection unit 130, the power-on mode is first selected (step S610), the power-on time is reset, and the initial position detection signal Pd is generated by the initial position detection signal generation unit 131, wherein the initial position detection signal Pd turns on the switch elements Q1 to Q6 corresponding to the power-on section to become a switch state corresponding to the power-on section of the measured rotor initial position measurement n (step S611).

[0193] The peak current acquisition unit 132 determines whether the current power-on time has passed the prescribed power-on time as the prescribed magnetic saturation time (step S612). If the prescribed power-on time has not passed (step S612: No), the peak current acquisition unit 132 waits until the prescribed power-on time has passed. If the current power-on time has passed the prescribed power-on time (step S612: Yes), the peak current acquisition unit 132 performs shunt current measurement (step S613). The peak current acquisition unit 132 obtains the current measurement value Im obtained by measuring the current flowing through the shunt resistor Rs as the peak value of the power-on current in the power-on mode.

[0194] When the current energization time exceeds a predetermined energization time, the initial position detection signal generating unit 131 changes to the cutoff mode (step S620 ), resets the masking time, and generates the initial position detection signal Pd for turning off all the switching elements Q1 to Q6 (step S621 ).

[0195] The peak current acquisition unit 132 determines whether the current masking time has passed the prescribed masking time (step S622). If the prescribed masking time has not passed (step S622: No), the peak current acquisition unit 132 waits until the prescribed masking time has passed. If the current masking time has passed the prescribed masking time (step S622: Yes), the peak current acquisition unit 132 performs shunt current measurement (step S623). The peak current acquisition unit 132 acquires the current measurement value Im obtained by measuring the current flowing through the shunt resistor Rs as the peak value of the kickback current in the cutoff mode.

[0196] When the current masking time has passed the prescribed masking time, the initial position detection signal generating unit 131 determines whether the absolute value of the current measurement value Im obtained by measuring the current flowing through the shunt resistor Rs is less than the threshold current value corresponding to the zero current as a zero current wait for the kickback current (step S624). When the initial position detection signal generating unit 131 determines that the absolute value of the current measurement value Im is not less than the threshold current value (step S624: No), since it is in a state of not converging to zero current, it performs the shunt current measurement process (step S625) and performs the determination of step S624 again. On the other hand, when the initial position detection signal generating unit 131 determines that the absolute value of the current measurement value Im is less than the threshold current value (step S624: Yes), since it is in a state of converging to zero current, it temporarily changes to a free mode in which no signal is provided to the switching elements Q1 to Q6 of the inverter circuit 2a (step S630). By the zero current wait for the kickback current, a state in which no current flows through the shunt resistor Rs is achieved. That is, since the state is not affected by the immediately preceding energized section, the rotor initial position in the next energized section can be measured with accurate current measurement, and the measurement time for each energized section can be shortened, thereby shortening the measurement time for all six directions of energization for the rotor initial position measurement.

[0197] return Fig.15 When the peak values ​​of the energized current and the kickback current are obtained for all energized sections, the position estimating unit 133 performs rotor initial position estimation (step S500). When the rotor position is estimated by the rotor initial position estimation, the motor is driven by excitation, forced commutation starting, etc.

[0198] As described above, in the control circuit 1 of the motor drive control device 10 of the embodiment, the high-side switches Q1, Q3, Q5 and the low-side switches Q2, Q4, Q6 of the inverter circuit 2a are turned on / off in a manner that the power-on sections are switched in sequence without rotating the rotor of the motor 3, and an initial position detection signal Pd is generated for energizing and disconnecting the coil corresponding to the power-on section. Based on the current detected in the bidirectional current detection circuit 30 when the initial position detection signal Pd is generated, the peak value of the power-on current flowing in the grounding direction when energizing and the peak value of the rebound current caused by the inductive rebound flowing in the direction of the inverter circuit when the power is disconnected are obtained for each power-on section, and the position of the rotor is estimated based on the peak value of the power-on current and the peak value of the rebound current in each power-on section.

[0199] Thus, the motor drive control device 10 can estimate the position of the rotor in a short time using a low-resolution current measuring device.

[0200] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the control circuit 1 has: an initial position detection signal generating unit 131, which generates an initial position detection signal Pd which is input to the inverter circuit 2a to sequentially energize and disconnect the coil in the energization direction in each energization section; a peak current acquisition unit 132, which acquires the peak value of the energization current and the peak value of the rebound current in each energization section; and a position estimation unit 133, which estimates the position of the rotor based on the peak value of the energization current and the peak value of the rebound current in each energization section.

[0201] Thus, the position of the rotor can be estimated based on the peak current and the peak kick current of each energizing section obtained by switching the energizing sections in sequence without rotating the rotor of the motor 3 by energizing and disconnecting the switching elements Q1 to Q6 of the inverter circuit 2a.

[0202] Furthermore, in the motor drive control device 10 of the above embodiment, the initial position detection signal generating unit 131 generates the initial position detection signal Pd for energizing the next energizing section after confirming that the magnitude of the kickback current has converged to zero.

[0203] As a result, the rotor initial position measurement in the next energization section can be performed with accurate current measurement, and the time between energization sections can be shortened, thereby shortening the measurement time of the rotor initial position measurement for all six directions of energization.

[0204] Furthermore, in the motor drive control device 10 of the above-described embodiment, the peak current acquisition unit 132 acquires the peak value of the energized current and acquires the kickback current after the masking time has elapsed.

[0205] Thereby, the peak value of the kickback current can be obtained.

[0206] In the motor drive control device 10 of the above embodiment, the position estimating unit 133 compares the total current value of the energizing current and the kickback current in each energizing section, and estimates the position corresponding to the energizing section having the largest total current value as the rotor position.

[0207] This makes it possible to estimate the position of the rotor based on a wider current measurement range than before.

[0208] Furthermore, in the motor drive control device 10 of the above-mentioned embodiment, when the energized segment with the maximum total current value cannot be determined as one, the position estimation unit 133 obtains the energized segment in which the peak value of the energized current flowing toward the grounding direction becomes the maximum and the energized segment in which the peak value of the rebound current generated by the inductive rebound flowing toward the inverter circuit direction becomes the maximum, respectively, and estimates the position of the rotor based on the number of energized segments obtained.

[0209] This makes it possible to more reliably estimate the position of the rotor.

[0210] Furthermore, in the motor drive control device 10 of the above-mentioned embodiment, when the power-on segment with the largest total current value cannot be determined as one, the position estimation unit 133 further obtains the difference of three bidirectional currents for each power-on segment based on the total current value, wherein the total current value is a current value obtained by summing up the peak value of the power-on current flowing in the grounding direction and the peak value of the rebound current generated by the inductive rebound flowing in the inverter circuit direction. When the maximum value of the difference of the three bidirectional currents is one, it is estimated that the position of the rotor is at a position corresponding to a power-on segment with a larger total current value among the two power-on segments with the largest current difference.

[0211] Thereby, the position of the rotor can be estimated.

[0212] In the motor drive control device 10 of the above embodiment, the initial position detection signal generating unit 131 generates the initial position detection signal Pd which is divided into a plurality of predetermined times to energize the coil in the energizing direction corresponding to the energizing section.

[0213] This can reduce the current generated by each power-on, thereby avoiding the generation of magnetic sounds such as "clicking".

[0214] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the initial position detection signal generating unit 131 generates the initial position detection signal Pd, wherein the initial position detection signal Pd is set to the timing of cut-off in the power-on section, so that the high-side switches Q1, Q3, Q5 and the low-side switches Q2, Q4, Q6 of the inverter circuit 2a that are in a complementary relationship with those when powered on are turned on.

[0215] Therefore, when the circuit is turned off, the kickback current caused by the inductive kickback generated in the inverter circuit 2a changes from passing through the parasitic diode of the switching element to passing through the on-resistance, thereby shortening the time for the shunt current Is to converge to zero. As a result, the time required for detecting the initial position of the rotor can be shortened.

[0216] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the control circuit 1 also has: a first switching unit 121a, which switches from a first switching state in which all high-side switches Q1, Q3, Q5 and low-side switches Q2, Q4, Q6 included in the inverter circuit 2a are disconnected to a second switching state in which at least two of the high-side switches Q1, Q3, Q5 or the low-side switches Q2, Q4, Q6 included in the inverter circuit 2a are connected; a second switching unit 121b, which switches from the second switching state to the first switching state; and an idling determination unit 122, which, when switching from the second switching state to the first switching state, determines whether the rotor of the motor is idling based on the current flowing through the shunt resistor Rs, and the control circuit 1 generates an initial position detection signal Pd after confirming that the rotor of the motor 3 is not idling through the idling determination unit 122.

[0217] This makes it possible to detect whether the rotor of the motor 3 is in an idling state, thereby shortening the rotor stop waiting time.

[0218] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the control circuit 1 also has a current measuring unit 16, which detects the output signal Vs from the bidirectional current detection circuit 30 as an offset in advance when no current flows through the shunt resistor Rs, and when judging idling and estimating the position of the rotor, adjusts the signal Vs output from the bidirectional current detection circuit 30 by the offset and outputs it to the idling judgment unit 122 and the position estimation unit 133.

[0219] Thus, even when the current flowing through the shunt resistor Rs is a negative current, its value can be detected.

[0220] 《Expansion of implementation methods》 As mentioned above, the invention accomplished by the present inventors has been specifically described based on the embodiments, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

[0221] In the embodiment, the speed command signal Sc includes the target value (target speed) of the speed of the motor 3 , but the present invention is not limited thereto. For example, the speed command signal Sc may be a torque command signal that specifies the torque of the motor 3 .

[0222] In addition, in the embodiment, the example in which the motor drive control device 10 does not use a position sensor and a measuring circuit for each phase voltage is described, but a position sensor and a measuring circuit for each phase voltage may also be provided. In this case, there is no need to use a position sensor and a measuring circuit for each phase voltage when detecting rotor idling. As a position sensor, a Hall element that outputs a Hall signal may be used, or it may be configured to input other signals corresponding to the rotational position of the rotor of the motor 3 as a rotational position detection signal instead of such a Hall signal. For example, an encoder, a rotary transformer, etc. may be provided, and its detection signal may be input to the control circuit 1. In addition, as a measuring circuit for each phase voltage, it may also be configured to input a signal of an A / D converter or a comparator that compares each phase voltage with the neutral point voltage as a rotational position detection signal.

[0223] In the embodiment, the control circuit 1 is not limited to the above circuit configuration. The control circuit 1 can adopt various circuit configurations that are configured to meet the purpose of the present invention.

[0224] Specifically, it can also be set as follows: in the current measuring unit 16, an idling judgment circuit using a comparator is constructed instead of the sampling circuit 51, and a signal serving as an idling threshold is output from the D / A converter. When the maximum current detection signal Vs in the direction of the inverter circuit exceeds the idling threshold, it is determined that the rotor of the motor is idling, and the idling judgment signal is output to the state control unit 12.

[0225] In addition, in the embodiment, the case where the rotor idling detection process is performed after the rotor stop waiting process is completed is cited as an example for explanation, but the rotor initial position detection process may also be performed after waiting for a predetermined time as the rotor stopped state. The rotor idling detection process for confirming the rotor stop is not limited to the method described above.

[0226] In addition, in the embodiment, the motor drive is not limited to the sine wave drive. The motor drive control method is not limited to the vector control. For example, 120-degree energization control may be adopted.

[0227] In the embodiment, the number of phases of the motor 3 driven by the motor drive control device 10 is not limited to three phases. The number of poles of the motor 3 is also not limited. The order of the energized sections is also not limited to the order described above.

[0228] The above flowchart is a specific example and the present invention is not limited to the flowchart. For example, other processing may be inserted between each step, and the processing may be parallelized. Description of Reference Numerals

[0229] 1: control circuit; 2: drive circuit; 2a: inverter circuit; 21: pre-drive circuit; 22: current detection circuit; 3: motor; 10: motor drive control device; 11: drive instruction acquisition unit; 12: state control unit; 13: vector control unit; 14: PWM signal generation unit; 15: timing adjustment unit; 16: current measurement unit; 120: idling detection unit; 121a: first switching unit; 121b: second switching unit; 122: idling determination unit; 130: initial position detection unit; 131: initial position detection signal generation unit; 132: peak current acquisition unit; 133: position estimation unit; 30: bidirectional current detection circuit; 31: delay circuit; 51: sampling circuit; 52: D / A converter; 53: comparator; 54: offset calculator; 100: motor unit; Q1~Q6: switching element; Rs: shunt resistor; Is: shunt current; Sc: speed command signal; Sd: drive control signal; Id: idling control signal; Tr: drive trigger signal; Tm: measurement trigger signal; Ir: idling trigger signal; Vs: current detection signal; Im: current measurement value; Iu, Iv, Iw: winding current; ωref: target speed; Vα, Vβ: voltage value; Tc: PWM count signal; St: timing signal; Vdc, Vin: DC power supply; Vuu, Vul, Vvu, Vvl, Vwu, Vwl: drive signal; Vout: voltage drop signal.

Claims

1. A motor drive control device, comprising: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; A drive circuit having an inverter circuit, wherein the inverter circuit includes a high-side switch and a low-side switch connected in series and arranged corresponding to the coils of each phase of the motor, wherein the drive circuit turns on / off the high-side switch and the low-side switch alternately according to the drive control signal, and rotates the rotor of the motor by switching the energization direction of the coils of the corresponding phases; A shunt resistor is provided between the inverter circuit and the ground; as well as a bidirectional current detection circuit for detecting the current flowing through the shunt resistor in a grounding direction from the inverter circuit toward the ground and in a direction of the inverter circuit which is the opposite direction thereof, The control circuit switches the energized sections in sequence without rotating the rotor of the motor, turns on / off the high-side switch and the low-side switch of the inverter circuit, and generates an initial position detection signal for energizing and disconnecting the coil in the energizing direction corresponding to the energized section. Based on the current detected in the bidirectional current detection circuit when the initial position detection signal is generated, the peak value of the current flowing toward the ground direction when the power is turned on and the peak value of the kickback current caused by the inductive kickback flowing toward the inverter circuit direction when the power is turned off are obtained for each of the energized sections. The position of the rotor is estimated based on a peak value of the energizing current and a peak value of the kickback current in each of the energizing sections.

2. The motor drive control device according to claim 1, wherein: The control circuit has: an initial position detection signal generating unit for generating the initial position detection signal input to the inverter circuit to sequentially conduct energization and disconnection of the coil in the energization direction for each energization section; a peak current acquisition unit, which acquires the peak value of the energizing current and the peak value of the kickback current in each energizing section; as well as The position estimating unit estimates the position of the rotor based on a peak value of the energizing current and a peak value of the kickback current in each of the energizing sections.

3. The motor drive control device according to claim 2, wherein: The initial position detection signal generating unit generates the initial position detection signal for energizing the next energizing section after confirming that the magnitude of the kickback current has converged to zero.

4. The motor drive control device according to claim 2, wherein: The peak current acquisition unit acquires a peak value of the energized current and acquires the kickback current after a masking time has elapsed.

5. The motor drive control device according to claim 2, wherein: The position estimating unit compares the total current value of the energizing current and the kickback current in each energizing section, and estimates a position corresponding to the energizing section having the largest total current value as the position of the rotor.

6. The motor drive control device according to claim 5, wherein: When the energized segment that becomes the maximum total current value cannot be determined as one, the position estimation unit obtains the energized segment in which the peak value of the energized current flowing toward the grounding direction becomes the maximum and the energized segment in which the peak value of the rebound current generated by the inductive rebound flowing toward the inverter circuit direction becomes the maximum, and estimates the position of the rotor based on the number of energized segments obtained.

7. The motor drive control device according to claim 5, wherein: When the energized segment with the maximum total current value cannot be determined as one, the position estimation unit further obtains the difference of three bidirectionally energized currents according to the total current value for each of the energized segments, wherein the total current value is a current value obtained by summing the peak value of the energized current flowing in the grounding direction and the peak value of the rebound current generated by the inductive rebound flowing in the inverter circuit direction. When the maximum value of the difference of the three bidirectionally energized currents is one, it is estimated that the position of the rotor is at a position corresponding to the energized segment with a larger total current value among the two bidirectionally energized segments where the current difference is the maximum value.

8. The motor drive control device according to claim 2, wherein: The initial position detection signal generating unit generates the initial position detection signal, wherein the initial position detection signal is set to be divided into a plurality of predetermined times to perform energization in the energization direction of the coil corresponding to the energization section.

9. The motor drive control device according to claim 2, wherein: The initial position detection signal generating unit generates the initial position detection signal, wherein the initial position detection signal is set to the timing of the cutoff in the energized section, so that the switch in the high side switch and the low side switch of the inverter circuit that is in a complementary relationship with the energized state is turned on.

10. The motor drive control device according to claim 1, wherein: The control circuit also has: a first switching unit, switching from a first switching state in which both the high-side switch and the low-side switch included in the inverter circuit are turned off to a second switching state in which at least two of the high-side switch or the low-side switch included in the inverter circuit are turned on; a second switching unit, switching from the second switch state to the first switch state; as well as an idling determination unit that determines whether the rotor of the motor is idling based on a current flowing through the shunt resistor when the second switch state is switched to the first switch state, The control circuit generates the initial position detection signal after the idling determination unit confirms that the rotor of the motor is not idling.

11. The motor drive control device according to claim 10, wherein: The control circuit further includes a position estimating unit that estimates the position of the rotor based on a peak value of the energizing current and a peak value of the kickback current in each of the energizing sections. The control circuit also has a current measuring unit, which detects the output signal from the bidirectional current detection circuit as an offset in advance when no current flows through the shunt resistor, and adjusts the signal output from the bidirectional current detection circuit by the offset when determining the idling and estimating the position of the rotor, and outputs it to the idling determination unit and the position estimation unit.

12. A method for detecting the initial position of a rotor, which is a method for detecting the initial position of a rotor executed in a motor drive control device, wherein: The motor drive control device comprises: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit having an inverter circuit, the inverter circuit comprising a high-side switch and a low-side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, the drive circuit alternately turning on / off the high-side switch and the low-side switch according to the drive control signal, and rotating the rotor of the motor by switching the energization direction of the coil of the corresponding phase; A shunt resistor is provided between the inverter circuit and the ground; and a bidirectional current detection circuit for detecting the current flowing through the shunt resistor in both directions, that is, a grounding direction from the inverter circuit toward the ground and a direction of the inverter circuit as the opposite direction thereof, The initial position detection method of the rotor comprises: The first step is to turn on / off the high-side switch and the low-side switch of the inverter circuit in a manner of switching the energized sections in sequence without rotating the rotor of the motor, thereby generating an initial position detection signal for energizing and disconnecting the coil in the energizing direction corresponding to the energized section; The second step is to obtain, for each of the energized sections, a peak value of the energized current flowing toward the ground direction when the energization is on and a peak value of the kickback current caused by the inductive kickback flowing toward the inverter circuit direction when the energization is cut off, based on the current detected in the bidirectional current detection circuit when the initial position detection signal is generated; and In a third step, the position of the rotor is estimated based on the peak value of the energizing current and the peak value of the kickback current in each of the energizing sections.

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