Motor drive control device and motor drive control method

Abstract

To provide a motor drive control device capable of detecting a position of a rotor of a motor by a current measurement device of low resolution in a short time.SOLUTION: A motor drive control device has a control circuit generating a drive control signal, a drive circuit having an inverter circuit including a switch provided corresponding to a coil of each phase of a motor and rotating a rotor of the motor by alternately turning on / off the switch according to the drive control signal, a shunt resistor provided between the inverter circuit and ground, and a bidirectional current detection circuit detecting current flowing through the shunt resistor in both directions. The control circuit performs energization and interruption in an energization direction of the coil by sequentially switching energization sectors without rotating the rotor of the motor, and estimates a position of the rotor based on a peak value of energization current per energization sector and the peak value of kickback current by inductive kickback.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor drive control device and a motor drive control method. [Background technology]

[0002] In a position sensorless three-phase brushless DC motor (BLDC motor), a method for detecting the rotor's initial position when the motor is stopped is known in which, with one-phase or one-two phase excitation, current is passed through the windings for each of six directions of current flow, and the "time to reach a specified current" or the "maximum current in a specified time" is measured to detect the rotor's magnetic pole position (initial position) using the difference in time or current caused by the influence of magnetic saturation of the coil for each current flow direction (Patent Documents 1, 2, and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-41881 A [Patent Document 2] JP 2016-19454 A [Patent Document 3] Patent Publication No. 2021-164191 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional method of detecting the magnetic pole position of the rotor, in a surface permanent magnet synchronous motor (SPMSM) with small saliency, the effect of magnetic saturation of the coil is small when the current is small, and the rotor position is not uniquely determined within a 60-degree range (current-carrying sector), while in the case of a large current, the rotor position is determined by magnetic saturation of the coil, but there are problems such as a "click" sound caused by current flow and the rotor rotating unintentionally. Also, when the resolution of the current measurement is low, the measured difference becomes small, making it difficult to detect the magnetic pole position of the rotor.

[0005] The inventors have thoroughly investigated the above problems and have discovered that in current measurement using the single shunt method, by utilizing a bidirectional current detection circuit and utilizing both the current flowing toward ground when current is applied, and the kickback current due to inductive kickback that flows toward the inverter circuit when current is cut off, it is possible to detect the rotor initial position in a short time using a low-resolution current measuring device without increasing the current flowing in order to increase the difference in current measured in a specified time for each current flow direction, and that correct current measurement can be performed when the next current flow is started after the kickback current has converged to zero, thereby shortening the measurement time for current flow in all six directions, thereby arriving at the present invention.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a motor drive control device that can detect the initial rotor position in a short time using a low-resolution current measuring device. [Means for solving the problem]

[0007] A motor drive control device according to a representative embodiment of the present invention includes a control circuit that generates a drive control signal for driving a motor having a coil of at least one phase, and an inverter circuit including a high-side switch and a low-side switch connected in series to each other and provided corresponding to the coil of each phase of the motor, and a drive circuit that alternately turns on and off the high-side switch and the low-side switch in response to the drive control signal to switch the direction of current flow to the coil of the corresponding phase, thereby rotating a rotor of the motor, a shunt resistor provided between the inverter circuit and ground, and a bidirectional current detection circuit that detects a current flowing through the shunt resistor in both directions, that is, in the ground direction from the inverter circuit to ground and in the opposite direction, that is, in the inverter circuit direction. and wherein the control circuit turns on and off the high-side switch and the low-side switch of the inverter circuit so as to sequentially switch current-carrying sectors without rotating the rotor of the motor, thereby generating an initial position detection signal for energizing and cutting off current in a current-carrying direction of a coil corresponding to the current-carrying sector, and obtains, for each current-carrying sector, a peak value of a current-carrying current that flows in the direction toward ground when current is applied and a peak value of a kickback current due to inductive kickback that flows in the direction toward the inverter circuit when current is cut off, based on a current detected in the bidirectional current detection circuit when the initial position detection signal is generated, and estimates a position of the rotor based on the peak value of the current-carrying current and the peak value of the kickback current for each current-carrying sector. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to detect the initial rotor position in a short time using a low-resolution current measuring device. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a motor unit 100 equipped with a motor drive control device 10 according to an embodiment. [Diagram 2]2 is a diagram showing an example of the configuration of a current detection circuit 22 of the motor drive control device 10. FIG. [Diagram 3] 2 is a diagram showing the switch states and current vectors of an inverter circuit 2a in each current-carrying sector of a three-phase motor 3. FIG. [Figure 4] FIG. 2 is a diagram showing a specific direction of a current vector. [Diagram 5] 10 is a diagram for explaining a switch state corresponding to a free mode, which is switched by a spin control signal Id. FIG. [Figure 6] 10 is a diagram for explaining a switch state corresponding to a charging mode, which is switched by a spin control signal Id. FIG. [Figure 7] 10 is a diagram for explaining a switch state corresponding to a discharge mode, which is switched by an idling control signal Id. FIG. [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 an embodiment. [Figure 9] 2 is a diagram showing an example of the configuration of a current measuring unit 16 included in a control circuit 1 of a motor drive control device 10. FIG. [Figure 10] FIG. 11 is a timing chart showing an example of a signal waveform from when a speed command signal Sc is input until rotor idling detection is completed when the rotor of the motor 3 is not moving at all. [Figure 11] FIG. 11 is a timing chart showing an example of a signal waveform from when a speed command signal Sc is input until detection of rotor idling is completed while the rotor of the motor 3 is moving. [Figure 12] 1 is a timing chart showing an example of a signal waveform from when a speed command signal Sc is input after power is applied to the motor unit 100 and when it is confirmed that the rotor has stopped until detection of the rotor's initial position is completed. FIG. [Figure 13] FIG. 11 is a timing chart showing another example of signal waveforms from when the motor unit 100 is powered on, when the speed command signal Sc is input, and when it is confirmed that the rotor has stopped, until when detection of the rotor initial position is completed. [Figure 14]FIG. 11 is a timing chart showing yet another example of a signal waveform of energization / cutoff for one energized sector in rotor initial position detection after power is applied to the motor unit 100, a speed command signal Sc is input, and the rotor is confirmed to have stopped. [Figure 15] 5 is a flowchart showing an example of a process flow when power is turned on in a control circuit 1 of a motor drive control device 10 according to an embodiment. [Figure 16] 4 is a flowchart showing an example of a flow of offset measurement by the control circuit 1 of the motor drive control device 10. [Figure 17] 4 is a flowchart showing an example of a flow of waiting for a rotor to stop by control circuit 1 of motor drive control device 10. [Figure 18] 4 is a flowchart showing an example of a flow of measurement of the rotor initial position by the control circuit 1 of the motor drive control device 10. [Figure 19] 10 is a flowchart showing an example of a flow of measurement of the rotor initial position in a current-carrying sector n by the control circuit 1 of the motor drive control device 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[0011] [1] A motor drive control device (10) according to a representative embodiment of the present invention includes a control circuit (1) that generates a drive control signal (Sd) for driving a motor having a coil of at least one phase, an inverter circuit (2a) including high-side switches (Q1, Q3, Q5) and low-side switches (Q2, Q4, Q6) connected in series to each other and provided corresponding to the coil of each phase of the motor (3), and a drive circuit (2) that alternately turns on and off the high-side switch and the low-side switch in response to the drive control signal to switch the direction of current flow to the coil of the corresponding phase, thereby rotating a rotor of the motor, and a shunt resistor (Rs) provided between the inverter circuit and ground, and a current flowing through the shunt resistor is controlled in both a ground direction from the inverter circuit to ground and a reverse direction, that is, an inverter circuit direction. and a bidirectional current detection circuit (30) for detecting a current in a direction parallel to the rotor of the motor, the control circuit turning on and off the high-side switch and the low-side switch of the inverter circuit so as to sequentially switch the current-carrying sectors without rotating the rotor of the motor, to generate an initial position detection signal (Pd) for energizing and cutting off the current in the current-carrying direction of the coil corresponding to the current-carrying sector, and obtaining, for each current-carrying sector, a peak value of a current-carrying current flowing in the direction toward ground when the current is applied and a peak value of a kickback current due to inductive kickback flowing in the direction toward the inverter circuit when the current is cut off, based on a current detected by the bidirectional current detection circuit when the initial position detection signal is generated, and estimating a position of the rotor based on the peak value of the current-carrying current and the peak value of the kickback current for each current-carrying sector.

[0012] [2] In the motor drive control device described in [1] above, the control circuit may have an initial position detection signal generation unit (131) that generates the initial position detection signal that is input to the inverter circuit to sequentially energize and cut off the current in the current direction of the coil for each current supply sector, a peak current acquisition unit (132) that acquires a peak value of the current supply current and a peak value of the kickback current for each current supply sector, and a position estimation unit (133) that estimates a position of the rotor based on the peak value of the current supply current and the peak value of the kickback current for each current supply sector.

[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 energized sector 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 mask time has elapsed.

[0015] [5] In the motor drive control device described in [2] above, the position estimation unit may compare the total current value of the energized current and the kickback current for each energized sector, and estimate the position corresponding to the energized sector with the maximum total current value as the rotor position.

[0016] [6] In the motor drive control device described in [5] above, when the current-carrying sector with the maximum total current value cannot be determined as a single one, the position estimation unit may acquire the current-carrying sector with the maximum peak value of the current flowing in the direction of ground and the current-carrying sector with the maximum peak value of the kickback current due to inductive kickback flowing in the direction of the inverter circuit, and estimate the rotor position according to the number of current-carrying sectors acquired.

[0017] [7] In the motor drive control device described in [5] above, when the current supply sector with the maximum total current value cannot be determined as one, the position estimation unit further obtains three bidirectional current differences from a total current value, which is a current value obtained by adding up, for each of the current supply sectors, the peak value of the current supply current flowing in the direction of ground and the peak value of the kickback current due to inductive kickback flowing in the direction of the inverter circuit, and when the maximum value of the current differences of the three bidirectional currents is one, it may be estimated that the rotor position is at a position corresponding to the current supply sector with the largest total current value among the two bidirectional current supply sectors with the maximum current difference.

[0018] [8] In the motor drive control device described in [2] above, the initial position detection signal generating unit may generate the initial position detection signal set so that the current in the current direction of the coil corresponding to the current-carrying sector is divided into multiple predetermined times.

[0019] [9] In the motor drive control device described in [2] above, the initial position detection signal generating unit may generate the initial position detection signal set to turn on one of the high-side switch and the low-side switch of the inverter circuit, which is in a complementary relationship with respect to the time when current is applied, at the timing of interruption in the current-applied sector.

[0020]

[10] In the motor drive control device described in [1] above, the control circuit may further have a first switching unit (121a) that switches from a first switch state in which all of the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switch state in which at least two of the high-side switches or the low-side switches included in the inverter circuit are turned on, a second switching unit (121b) that switches from the second switch state to the first switch state, and an idling determination unit (122) that determines whether the rotor of the motor is spinning based on a current flowing through the shunt resistor when switching from the second switch state to the first switch state, and the control circuit may generate the initial position detection signal after confirming in the idling determination unit that the rotor of the motor is not spinning.

[0021]

[11] In the motor drive control device described in

[10] above, the control circuit may further have a position estimation unit that estimates a position of the rotor based on a peak value of the energization current for each energized sector and a peak value of the kickback current, and the control circuit may further have a current measurement unit that detects in advance an output signal from the bidirectional current detection circuit as an offset when no current flows through the shunt resistor, and adjusts the signal output from the bidirectional current detection circuit with the offset when determining whether or not there is an idling motion and estimating the position of the rotor, and outputs the adjusted signal to the idling motion determination unit and the position estimation unit.

[0022]

[12] A method for detecting an initial position of a rotor according to a representative embodiment of the present invention is a rotor initial position detection method executed in a motor drive control device including: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; and an inverter circuit including a high-side switch and a low-side switch connected in series to each other and provided corresponding to the coil of each phase of the motor, the drive circuit alternately turning on and off the high-side switch and the low-side switch in response to the drive control signal to switch the current flow direction of the coil of the corresponding phase, thereby rotating the rotor of the motor; a shunt resistor provided between the inverter circuit and ground; and a bidirectional current detection circuit for detecting a current flowing through the shunt resistor in both directions, that is, in the ground direction from the inverter circuit to ground and in the inverter circuit direction, which is the opposite direction. a first step of generating an initial position detection signal for turning on and off the high-side switch and the low-side switch of the inverter circuit so as to sequentially switch current-carrying sectors without rotating a rotor of the motor, thereby energizing and cutting off a current in a current-carrying direction of a coil corresponding to the current-carrying sector; a second step of acquiring, for each current-carrying sector, a peak value of a current-carrying current flowing in the direction toward ground when current is applied and a peak value of a kickback current due to inductive kickback flowing in the direction toward the inverter circuit when current is cut off, based on a current detected in the bidirectional current detection circuit when the initial position detection signal is generated; and a third step of estimating a position of the rotor based on the peak value of the current-carrying current and the peak value of the kickback current for each current-carrying sector.

[0023] 2. Specific examples of embodiments DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, components common to the respective embodiments are designated by the same reference numerals, and repeated description will be omitted.

[0024] <Embodiment> FIG. 1 is a diagram showing a configuration of a motor unit 100 equipped with a motor drive control device 10 according to an embodiment.

[0025] 1, the motor unit 100 includes a motor 3 and a motor drive control device 10 that controls the rotation of the rotor of the motor 3. The motor unit 100 can be applied to various devices that use a motor as a drive source, such as a fan or a drone (unmanned aerial vehicle).

[0026] The motor 3 is, for example, a permanent magnet synchronous motor (PMSM). In this embodiment, the motor 3 is, for example, a surface permanent magnet synchronous motor (SPMSM) having three-phase coils (windings) Lu, Lv, and Lw. The coils Lu, Lv, and Lw are, for example, connected in a Y (star) configuration. In this case, the coils may be connected in a Δ (delta) configuration.

[0027] The motor drive control device 10, for example, applies a sine wave drive signal to the motor 3, thereby causing a sine wave drive current to flow periodically 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 the components of the motor drive control device 10 shown in FIG. 1 are only a portion of the whole, and the motor drive control device 10 may have other components in addition to those shown in FIG.

[0030] The drive circuit 2 drives the motor 3 based on a drive control signal Sd output from a 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 ground.

[0031] The inverter circuit 2a is a circuit disposed between a DC power supply Vin and a ground potential, and drives coils Lu, Lv, and Lw of a motor 3 as a load based on an input drive control signal Sd. Specifically, in the embodiment, the inverter circuit 2a has three switching legs, each including two drive transistors connected in series, and drives the motor 3 as a load by alternately turning on and off the two drive transistors (switching operation) based on the input drive control signal Sd.

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

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

[0034] For example, the switching leg corresponding to the U phase has switching elements Q1 and Q2 connected in series. The point where the switching elements Q1 and Q2 are commonly connected is connected to one end of the coil Lu as a load. The switching leg corresponding to the V phase has switching elements Q3 and Q4 connected in series. The point where the switching elements Q3 and Q4 are commonly connected is connected to one end of the coil Lv as a load. The switching leg corresponding to the W phase has switching elements Q5 and Q6 connected in series. The point where the switching elements Q5 and Q6 are commonly connected is connected to one end of the coil Lw as a load. In addition, the switching elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 each have a parasitic diode characteristic from the ground side to the power supply side.

[0035] The pre-drive circuit 21 generates a drive signal for driving the inverter circuit 2a based on the drive 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 current conduction pattern of the coils Lu, Lv, and Lw of the motor 3, which is determined by the on / off state of each switching element constituting the inverter circuit 2a. More specifically, the drive control signal Sd includes six types of PWM signals corresponding to each switching element Q1 to Q6 of the inverter circuit 2a.

[0037] The pre-drive circuit 21 generates six types of drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl that can supply sufficient power to drive the control electrodes (gate electrodes) of each of the switching elements Q1 to Q6 of the inverter circuit 2a, based on six types of PWM signals as drive control signals Sd supplied from the control circuit 1.

[0038] These drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl are input to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, causing each of the switching elements Q1 to Q6 to perform an on-off operation (switching action). For example, the switching elements Q1, Q3, and Q5 of the upper arm and the switching elements Q2, Q4, and Q6 of the lower arm of the switching leg corresponding to each phase alternately perform an on-off operation. As a result, power is supplied from the DC power supply Vin to each phase of the motor 3, causing the rotor of the motor 3 to rotate.

[0039] The current detection circuit 22 is connected to the DC line of the inverter circuit 2a and detects the current flowing through the DC line. Specifically, it includes one 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 between, for example, a DC power supply Vin and a ground potential. That is, the shunt resistor Rs of the current detection circuit 22 is connected to the negative side (ground side) of the inverter circuit 2a as shown in FIG. 1. For example, in motor driving, 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 a voltage drop due to the current flowing through the shunt resistor Rs from 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] 2 is a diagram showing an example of the configuration 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 a shunt resistor Rs.

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

[0042] Specifically, the bidirectional current detection circuit 30 in FIG. 2 obtains a differential voltage across the shunt resistor Rs, amplifies the differential voltage at a predetermined gain using an amplifier (AMP) using a differential amplifier circuit, and outputs the voltage drop signal Vout across the shunt resistor Rs. The delay circuit 31 smoothes the voltage drop signal Vout using a circuit including a resistor R3 and a capacitor C3, and outputs the voltage drop signal Vs corresponding to the current flowing through the shunt resistor Rs to the control circuit 1. The bidirectional current detection circuit 30 applies a voltage Vdc / 2 that offsets the amplifier output to the positive terminal of the differential amplifier circuit, and is configured to detect both positive and negative voltage drops across the shunt resistor Rs, that is, to measure bidirectional currents. At this time, the current detection signal Vs outputs a signal in the range from 0 to Vdc, which is Vdc / 2 when the shunt current Is is zero. Note that the voltage that offsets the amplifier output is not limited to Vdc / 2, and a voltage that offsets the amplifier output may 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 a shunt current Is in the shunt resistor Rs by using the current measurement unit 16 described later, in which the ground direction from the inverter circuit 2a to the ground (the direction of the arrow Is in the figure) is a positive value, and the inverter circuit direction, which is the opposite direction from the ground to the inverter circuit 2a, is a negative value.

[0044] In the current detection circuit 22, while the motor 3 is being driven by the drive control signal Sd, the current that has passed through the coil of the motor 3 and flowed back to the inverter circuit 2a passes through the shunt resistor Rs. That is, in the current detection circuit 22, a current flows in the ground direction from the inverter circuit 2a to the ground, so that a positive shunt current Is can be measured by the current measurement unit 16 described later.

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

[0046] In the motor drive control device 10 of this embodiment, the switch states of the switching elements Q1 to Q6 of the inverter circuit 2a are switched so as to sequentially switch the current-carrying sectors without rotating the rotor of the motor 3, and the initial position of the rotor is detected by estimating the position of the rotor based on the current flowing through the shunt resistor Rs when current is applied and cut off in the current-carrying direction of the coil corresponding to the current-carrying sector.

[0047] In order to detect the initial position of the rotor, in the motor drive control device 10 of this embodiment, the drive circuit 2 receives an initial position detection signal Pd, which is different from the drive control signal Sd for driving the motor, from the control circuit 1 described later, and switches each switching 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, the high-side switches Q1, Q3, Q5 and low-side switches Q2, Q4, Q6 of the inverter circuit 2a are turned on and off so as to sequentially switch the energized sectors without rotating the rotor of the motor 3, thereby energizing and cutting off the current in the energizing direction of the coil corresponding to the energized sector.

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

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

[0050] The pre-drive circuit 21 generates signals capable of supplying sufficient power to switch the switch states of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, based on six types of signals as the initial position detection signal Pd supplied from the control circuit 1. Drive signals as these switching signals are input to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, thereby switching the switch states of the switching elements Q1 to Q6.

[0051] Here, the sequential switching of the energized sectors without rotating the rotor of the motor 3 will be described.

[0052] 3 and 4 are diagrams for explaining current-carrying sectors in the motor 3. Fig. 3 is a diagram showing the switch states and current vectors of the inverter circuit 2a in each current-carrying sector of the three-phase motor 3, and Fig. 4 is a diagram showing specific directions of the current vectors.

[0053] 3, in the case of a three-phase motor 3, there are six current-carrying sectors at 60 degrees intervals. The current-carrying sectors are sequentially switched to one of the six current-carrying sectors based on the initial position detection signal Pd.

[0054] As shown in FIG. 3, when the energization method is one-phase excitation, in energization sector 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, in current supply sector 2, the U-phase high-side switching element Q1 and the V-phase low-side switching element Q4 are turned on, and the current vector is oriented at 150°; in current supply sector 3, the U-phase high-side switching element Q1 and the W-phase low-side switching element Q6 are turned on, and the current vector is oriented at 210°; in current supply sector 4, the W-phase high-side switching element Q5 and the U-phase low-side switching element Q2 are turned on, and the current vector is oriented at 30°; in current supply sector 5, the V-phase high-side switching element Q3 and the U-phase low-side switching element Q2 are turned on, and the current vector is oriented at 330°; and in current supply sector 6, the W-phase high-side switching element Q5 and the V-phase low-side switching element Q4 are turned on, and the current vector is oriented at 90°.

[0055] As shown in FIG. 3, when the energization method is 1-2 phase excitation, in energization sector 1, the V- and U-phase high-side switching elements Q3 and Q1 and the W-phase low-side switching element Q6 are turned on, and the current vector is in the direction of 240°. In energization sector 2, the U- and W-phase high-side switching elements Q1 and Q5 and the V-phase low-side switching element Q4 are turned on, and the current vector is in the direction of 120°. In energization sector 3, the U-phase high-side switching element Q1 and the W- and V-phase low-side switching elements Q6 and Q4 are turned on, and the current vector is in the direction of 18°. In the current supply sector 4, the high-side switching elements Q5 and Q3 of the W- and V-phases and the low-side switching element Q2 of the U-phase are turned on, and the current vector is in the direction of 0°, in the current supply sector 5, the high-side switching element Q3 of the V-phase and the low-side switching elements Q2 and Q6 of the U- and W-phases are turned on, and the current vector is in the direction of 300°, and in the current supply sector 6, the high-side switching element Q5 of the W-phase and the low-side switching elements Q4 and Q2 of the V- and U-phases are turned on, and the current vector is in the direction of 60°. Note that in the following description of this embodiment, an example will be given of the current supply method being the 1-2 phase excitation method.

[0056] It can be seen that when one of the six current carrying sectors is switched as shown in FIG. 3, the current vector is switched to one of the directions shown in FIG.

[0057] In normal motor driving, the drive control signal Sd for driving the motor switches the energized sectors so that the current vector rotates gradually every 60 degrees. For example, the energized sectors are switched in the order of energized sector 3, energized sector 1, energized sector 5, energized sector 4, energized sector 6, and energized sector 2 to energize the switching elements. When the rotation direction of the motor is reversed, the order of the energized sectors is reversed. In contrast, in rotor initial position detection, the energized sectors are switched in sequence without rotating the rotor of the motor 3, so that the energized sectors are switched so as to cancel the current vector. For example, the energized sectors are switched in the order of energized sector 3, energized sector 4, energized sector 6, energized sector 1, energized sector 5, and energized sector 2. For example, the energized sectors 3 and 4 may be treated as bidirectional energization because their current vectors are opposite to each other.

[0058] In addition, in rotor initial position detection, current is applied to the current-carrying sector for a predetermined magnetic saturation time. Here, the magnetic saturation time will be explained. When current is applied to the coil of the motor 3, a magnetic field is gradually generated in the coil according to the length of the current-carrying time. However, the magnetic field generated is limited by the relationship between the magnetic pole positions of the rotor and the stator, and the state of the coil when the magnetic field generated reaches its limit is called a state where magnetic saturation has been reached. When the magnetic pole positions of the rotor and the stator are in a position where they have a certain relationship, the speed at which magnetic saturation is reached is fast due to a synergistic effect. The time required for magnetic saturation when the magnetic pole positions of the rotor and the stator are in a position where they have a certain relationship is defined as a predetermined magnetic saturation time, and the current-carrying time in the current-carrying sector is set to this predetermined magnetic saturation time. Therefore, in current-carrying sectors other than the position where the magnetic pole positions of the rotor and the stator are in a certain relationship, the speed at which magnetic saturation is reached is slow, so magnetic saturation does not occur in the "predetermined magnetic saturation time". The specified magnetic saturation time does not have to be exactly the same as the time required for magnetic saturation when the magnetic pole positions of the rotor and stator are in a fixed relationship, and may be adjusted within a range that allows for discrimination from positions other than those in which the magnetic pole positions of the rotor and stator are in a fixed relationship. When this magnetic saturation is reached, a large current flows through the coil, making it possible to detect the rotor initial position by measuring the "maximum current in a specified time."

[0059] Next, it will be explained how the initial position of the rotor can be detected by estimating the rotor position based on the current flowing through the shunt resistor Rs when current is applied and cut off in the current application direction of the coil corresponding to the current application sector.

[0060] As described above, when the coil of the motor 3 is energized, the shunt current Is flows in the direction toward ground through the shunt resistor Rs of the current detection circuit 22, just as when the motor is driven. Conventionally, the position of the rotor has been estimated based on the magnitude of the peak current value of this shunt current Is. In contrast, the motor drive control device 10 of this embodiment focuses on the fact that a kickback current occurs in the shunt resistor Rs of the current detection circuit 22 due to inductive kickback that flows in the direction toward the inverter circuit when the energization is interrupted, and measures this as a negative value of the shunt current Is.

[0061] In each energized sector, by energizing the coil in the energized direction and then cutting it off, the current continues to flow in the energized coil direction. For the coil, this current is in the same direction as when energized, but for the shunt resistor Rs, it is in the inverter circuit direction opposite to the ground direction when energized. The peak of the current is almost equal to the peak value of the energized current. In other words, in the energized sector where magnetic saturation has occurred in the coil, the peak value of the kickback current detected in the reverse inverter circuit direction is larger than in other energized sectors, just like the peak value of the energized current detected in the ground direction of the shunt resistor Rs. Therefore, it can be seen that not only the peak value of the energized current for each energized sector, but also the peak value of the kickback current can be used to estimate the rotor position.

[0062] In this manner, the motor drive control device 10 of the present embodiment uses the bidirectional current detection circuit 30 as the current detection circuit 22 to estimate the rotor position based on the peak value of the energization current and the peak value of the kickback current for each energization sector. When estimating the rotor position, the range of current values ​​to be detected is expanded, so the difference in current measured by energization for a specified time for each energization sector becomes large, and the initial position of the rotor can be detected more accurately with a small current without increasing the energization current to increase the difference in current measured for a specified time for each energization direction. Therefore, the motor drive control device 10 of the present embodiment can use a detection device with low resolution. The difference in magnitude between the peak value of the energization current and the peak value of the kickback current for each energization sector also occurs in the same way when the coil is one-phase and switching elements are provided above and below both ends of the coil.

[0063] In the motor drive control device 10 of this embodiment, the initial position detection of the rotor must be performed in a state where the rotor of the motor 3 is not spinning freely in order to measure the current caused by energization for a specified time. That is, in the motor drive control device 10 of this embodiment, a rotor stop waiting process must be performed before the initial position detection of the rotor is performed. In this case, in addition to the driving of the motor 3 by the drive control signal Sd and the detection of the initial position of the rotor by the initial position detection signal Pd described above, a configuration may be provided for determining that the rotor of the motor 3 is spinning freely when the motor 3 is not driven by the drive control signal Sd. In the motor drive control device 10 of this embodiment, by having a configuration for determining the spinning of the rotor, the initial position detection of the rotor can be performed after confirming that the rotor of the motor 3 is not spinning freely.

[0064] In the motor drive control device 10 of this embodiment, by switching the switch states of each switching element Q1 to Q6 of the inverter circuit 2a, when the rotor of the motor 3 is rotating, an induced current is generated by the induced electromotive force and circulates between the coil of the motor 3 and the inverter circuit 2a.When the current path is interrupted, an inductive kickback occurs in the inverter circuit 2a, and it is determined that the rotor of the motor 3 is spinning freely based on the kickback current flowing through the shunt resistor Rs.

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

[0066] The idling control signal Id is a signal for switching each of the switching elements constituting the inverter circuit 2a to a switch state corresponding to three modes for detecting 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 is therefore not a signal for alternately switching each switching element on and off, but is, for example, a high-level or low-level signal having a predetermined length. The idling control signal Id includes six types of signals corresponding to each of the switching elements Q1 to Q6 of the inverter circuit 2a.

[0067] Based on the idling control signal Id output from the control circuit 1, the pre-drive circuit 21 generates a drive signal as a switching signal for switching the switch state of each switching element constituting the inverter circuit 2a.

[0068] The pre-drive circuit 21 generates signals capable of supplying sufficient power to switch the switch states of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, based on six types of signals as the idling control signals Id supplied from the control circuit 1. Drive signals as these switching signals are input to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, thereby switching the switch states of the switching elements Q1 to Q6.

[0069] Here, a description will be given of the switch states corresponding to the three modes (free mode, charge mode, and discharge mode) for detecting the idling of the rotor of the motor 3, which are switched by the idling control signal Id.

[0070] 5 to 7 are diagrams for explaining the states of the switches switched by the idling control signal Id. In Fig. 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 source Vin and is also connected to ground via a shunt resistor Rs, which is a part of the current detection circuit 22.

[0071] The idling control signal Id is a signal that switches the switch state to the corresponding free mode (Fig. 5), charge mode (Fig. 6), and discharge mode (Fig. 7) in that order. Specifically, the idling control signal Id switches the switch state of the control electrode (gate electrode) of each of the switching elements Q1 to Q6 of the inverter circuit 2a from the first switch state (corresponding to the free mode) shown in Fig. 5 to the second switch state (corresponding to the charge mode) shown in Fig. 6, and then switches it back to the first switch state (corresponding to the discharge mode) as shown in Fig. 7, thereby making it possible to detect idling of the rotor of the motor 3.

[0072] (Free Mode) After power is turned on, when the control circuit 1 outputs an idling control signal Id in response 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 switch state by the idling control signal Id output from the control circuit 1. Specifically, as shown in Fig. 5, in the inverter circuit 2a, the switch states of all of the switching elements Q1 to Q6 are switched to OFF.

[0073] 5, in this first switch state, when the rotor of the motor 3 is rotating idly, an induced electromotive force is generated in the coil of each phase, but because each of the switching elements Q1 to Q6 is turned off and the parasitic diodes are clamped, no current is generated circulating between the coil of the motor 3 and the inverter circuit 2a. Also, at this time, no current flows through the shunt resistor Rs.

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

[0075] 6, in the inverter circuit 2a, when the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 are switched on to the second switching state, if the rotor of the motor 3 is rotating idly, an induced current is generated in the coils of each phase by an induced electromotive force, which circulates between the coils of the motor 3 and the inverter circuit 2a, and the generated induced current circulates in the closed circuit formed by the coils and the switching elements Q2, Q4, and Q6 of the lower arms that are turned on. At this time, the shunt resistor Rs is not included in the closed circuit, so no current flows through the shunt resistor Rs.

[0076] Specifically, when the rotor of the motor 3 is rotating idly, the rotation of the rotor relative to the coil generates induced voltages (eu, ev, ew) in each phase coil that are proportional to the rotation speed, with a polarity in the direction that generates a current that hinders changes in the magnetic flux, with a period of electrical angle due to the rotor rotation with each phase shifted by 120 degrees. At this time, the current waveform is 90 degrees behind the voltage waveform.

[0077] (Discharge mode) Next, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched from the second switch state back to the first switch state by the idling control signal Id output from the control circuit 1. Specifically, for example, in the inverter circuit 2a, the switch states of the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 are switched on, and then switched back to the first switch state, as shown in FIG.

[0078] As shown in FIG. 7, when the rotor of the motor 3 is rotating idly, the path of the circulating induced current is cut off when the inverter circuit 2a changes from the second switch state to the first switch state. At this time, the induced current (A in FIG. 7) that has been circulating in the coils of the motor 3 tries to continue to flow through the windings (coils) of the motor 3, and an inductive kickback occurs in the inverter circuit 2a. During the short time until the voltage fluctuation due to the inductive kickback converges within the voltage range clamped by the parasitic diodes of the switching elements Q1 to Q6, a voltage rise occurs at the connection point between the upper arm and the lower arm of the leg on the downstream side of the induced current, and a current flows from the coil to the power supply via the parasitic diode of the switching element Q1 of the upper arm, and a voltage drop occurs at the connection point between the upper arm and the lower arm of the leg on the upstream side of the induced current, and a current flows from the ground to the coil via the parasitic diodes of the switching elements Q4 and Q6 of the lower arm, and a current (B in FIG. 7) flows from the ground of the shunt resistor Rs to the inverter circuit.

[0079] In the motor drive control device 10 of this 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 in the discharge mode, and if it is determined that a predetermined current has flowed, it can determine that the rotor of the motor 3 is spinning freely.

[0080] In the above example, the second switch state corresponding to the charging mode is described by taking as an example a case in which the switch states of the lower arm switching elements Q2, Q4, and Q6 of the switching elements Q1 to Q6 of the inverter circuit 2a are turned on as shown in FIG. 6, but is not limited to this.

[0081] The second switch state also includes a state in which any two of the switching elements Q1, Q3, and Q5 of the upper arms of the switching elements Q1 to Q6 or the switching elements Q2, Q4, and Q6 of the lower arms are turned on. In this switch state, when the rotor of the motor 3 is rotating idly, an induced electromotive force is generated in the coils of each phase, and an induced current generated in a closed circuit formed by the coils and the transistors of the switching elements Q1 to Q6 that are turned on circulates. In other words, the second switch state can be said to be a switch state in which, when the rotor of the motor 3 is rotating idly, an induced electromotive force is generated in the coils of each phase, and an induced current generated in a closed circuit formed by the coils and the transistors of the switching elements Q1 to Q6 that are turned on circulates.

[0082] On the other hand, when the switch state of any one of the switching elements Q1, Q3, Q5 of the upper arm or the switching elements Q2, Q4, Q6 of the lower arm of each switching element Q1 to Q6 is turned on, a closed circuit does not always exist, and therefore the induced current does not always circulate, and therefore this is not included in the second switch state.

[0083] 1, the current detection circuit 22 is a circuit for detecting the energizing current that flows through the three-phase coils Lu, Lv, and Lw of the motor 3 and flows through the shunt resistor Rs toward ground when the inverter circuit 2a is controlled during motor drive and rotor initial position detection, and for detecting the kickback current that flows through the shunt resistor Rs from ground toward the inverter circuit of the inverter circuit 2a 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 driving the motor, the control circuit 1 generates a drive control signal Sd for driving the motor 3 based on a speed command signal Sc that is input from outside and indicates a target state of operation of the motor 3, and controls the driving of the motor 3. Specifically, the control circuit 1 generates the drive control signal Sd to provide to the drive circuit 2 so that the motor 3 is in the operating state specified by the speed command signal Sc.

[0085] In addition, in rotor initial position detection, the control circuit 1 generates an initial position detection signal Pd instead of the drive control signal Sd to detect the initial position of the rotor. Specifically, the control circuit 1 generates the initial position detection signal Pd so that each of the switching elements Q1 to Q6 of the inverter circuit 2a is in a switch state designated by the initial position detection signal Pd, and provides the initial position detection signal Pd to the drive circuit 2.

[0086] Furthermore, in detecting idling of the rotor while waiting for the rotor to stop, the control circuit 1 generates an idling control signal Id instead of the drive control signal Sd, and detects idling of the rotor of the motor 3. Specifically, the control circuit 1 generates the idling control signal Id so that each of the switching elements Q1 to Q6 of the inverter circuit 2a is in a switch state designated by the idling control signal Id, and provides the idling control signal Id to the drive circuit 2.

[0087] In an embodiment, the control circuit 1 is a program processing device (e.g., a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output I / F circuit are connected to each other via a bus or a dedicated line.

[0088] The motor drive control device 10 may be configured such that at least a part of the control circuit 1 and at least a part of the drive circuit 2 are packaged as a single integrated circuit device (IC), or the control circuit 1 and the drive circuit 2 are each packaged as separate integrated circuit devices.

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

[0090] As shown in FIG. 8, the control circuit 1 has 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 motor drive by vector control, for example. The control circuit 1 has 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 has an initial position detection signal generation unit 131, a peak current acquisition unit 132, and a position estimation unit 133. The control circuit 1 also has a slip detection unit 120 and a current measurement unit 16 as functional blocks for generating a slip control signal Id in rotor slip detection. The slip detection unit 120 has a first switching unit 121a, a second switching unit 121b, and a slip determination unit 122.

[0091] These functional blocks are realized, for example, in a program processing device serving as the control circuit 1, by a processor executing various arithmetic processing according to programs 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 analyzes the received speed command signal Sc to acquire a value specifying a target operating state of the motor 3 specified by the speed command signal Sc.

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

[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 of the target rotation speed (target number of revolutions) 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 a specified 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] In driving the motor, the state control unit 12 outputs the target rotation speed ωref as it is to the vector control unit 13. 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, which can use the initial position as the starting position of the rotor in the motor 3. This enables smooth starting of the motor with low current consumption, vibration, and noise. When a slip determination signal described later is generated from the slip determination unit 122, the state control unit 12 can determine whether or not to use windmill start or forced commutation start as the starting method of the motor. Although not particularly shown in FIG. 8, the vector control unit 13 and the state control unit 12 may further have a functional unit that executes such processing.

[0097] The state control unit 12 further generates a measurement trigger signal Tm and a spin trigger signal Ir in rotor initial position detection and rotor spin detection, and generates a current measurement value Im from the current detection signal Vs detected in the current detection circuit 22. Specifically, the state control unit 12 generates a measurement trigger signal Tm and a spin trigger signal Ir that turn on a switch of a sampling circuit 51 of the current measurement unit 16 (described later) at a predetermined timing, and provides them to the current measurement unit 16. Although not particularly shown in FIG. 8, the state control unit 12 may further have a functional unit that executes a process of generating the measurement trigger signal Tm and the spin trigger signal Ir.

[0098] In driving the motor, the vector control unit 13 generates voltage values ​​Vα, Vβ from the target rotation speed ωref and the measured current value Im according to well-known vector control, and outputs them to a PWM signal generating unit 14 (space vector modulation circuit: SVM (Space Vector Modulation)). At this time, the measured current value Im is subjected to offset adjustment, which will be described later, and is treated as the measured current values ​​Iu, Iv, Iw of the windings according to the measurement timing of the drive control signal Sd and a timing signal St generated by a timing adjusting unit 15, which will be described later.

[0099] In driving the motor, the PWM signal generating unit 14 outputs a drive control signal Sd to the drive circuit 2 to PWM control the drive circuit 2, and also outputs a PWM count signal Tc to the timing adjusting unit 15, which is a signal indicating the start of counting for each PWM period in the PWM control.

[0100] In driving the motor, the timing adjustment unit 15 starts a counter for generating timing in synchronization with the start of counting for each PWM period, and triggers the current measurement unit 16 to measure the current caused by the current flow during driving. Specifically, the timing adjustment unit 15 outputs a drive trigger signal Tr to the current measurement unit 16 at a current capture timing synchronized with the current flow based on the PWM count signal Tc output from the PWM signal generation unit 14.

[0101] During motor drive, the current measurement unit 16 performs A / D conversion on the current detection signal Vs corresponding to the winding currents Iu, Iv, and Iw based on the drive trigger signal Tr or the measurement trigger signal Tm, and further performs offset adjustment, which will be described later, to generate a measured current value Im. The measured current value Im is output to the vector control unit 13, which performs vector control from the three-phase current values ​​based on the timing signal St from the timing adjustment unit 15, and calculates the magnitude of current flow in the PWM signal generation unit 14.

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

[0103] 9 performs A / D conversion at a predetermined timing on the current detection signal Vs that corresponds to the current flowing through the shunt resistor Rs and is input from the current detection circuit 22, and further performs offset adjustment, which will be described later, to generate a current measurement value Im to be used by the control circuit 1. The current measurement value Im is a value that corresponds to the current flowing through the shunt resistor Rs of the current detection circuit 22.

[0104] Specifically, the sampling circuit 51 in FIG. 9 is composed of, for example, a switch and a capacitor, and the switch is switched on and off in response 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 the sample period by the sampling circuit 51 and quantizing the hold period by the D / A converter 52 and the comparator 53. The value generated by the A / D conversion is further subjected to offset adjustment by the offset calculator 54, which will be described later, and a current measurement value Im corresponding to the current flowing through the shunt resistor Rs is generated. The current measurement value Im is used by the vector control unit 13 as the winding current measurement values ​​Iu, Iv, and Iw in motor driving. The current measurement value Im is also used by the peak current acquisition unit 132 of the state control unit 12, which will be described later, in rotor initial position detection. Furthermore, in detecting rotor slip, the current measurement value Im is used by an idle-spin determination section 122 of the state control section 12 of the control circuit 1, which will be described later.

[0105] Here, offset adjustment will be described. Since the current detection circuit 22 is capable of measuring the current flowing in both directions through the shunt resistor Rs, 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 measurement unit 16, when no current flows through the shunt resistor Rs, the measured current value Im becomes a value other than zero. By adjusting the offset, if the measured current value Im when no current flows through the shunt resistor Rs is set to zero, it becomes equivalent to the conventional current measurement in the ground direction (direction from the inverter circuit 2a to the ground), and further the current direction is clarified by the positive / negative sign.

[0106] For offset adjustment, the state control unit 12 performs A / D conversion on the current detection signal Vs input to the current measurement unit 16 in the free mode or charging mode, which is a state in which no current flows through the shunt resistor Rs, to obtain an offset value in advance, and uses this obtained offset value in the offset calculator 54 of the current measurement unit 16.

[0107] Specifically, in the free mode (initial first switch state) or the charging mode (second switch state), the state control unit 12 outputs an idling trigger signal Ir that switches on the sampling circuit 51 of the current measurement unit 16, performs A / D conversion on the current detection signal Vs input from the current detection circuit 22, and specifies the current measurement value generated by disabling the offset calculator 54 as the offset value. The process of disabling the offset calculator 54 and generating the current measurement value may be repeated multiple times, and the average value of the current measurement values ​​generated multiple times may be set as the offset value. In the free mode or the charging mode, no current flows through the shunt resistor Rs of the current detection circuit 22 regardless of whether the rotor of the motor 3 is in an idling state or not. Therefore, the current detection signal Vs detected at this time can be used as a reference for zero current and can be used as an offset to be used when generating the current measurement value Im.

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

[0109] In rotor slip detection, in the discharge mode, i.e., when switching from the second switch state to the first switch state, the state control unit 12 outputs an idling trigger signal Ir to the current measurement unit 16 for switching on the sampling circuit 51 at a predetermined timing to instruct the current measurement unit 16 to measure the input current detection signal Vs, and also performs A / D conversion on the input current detection signal Vs and further performs offset adjustment to generate a measured current value Im. The current measurement unit 16 outputs the generated measured current 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 measured current 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 value with the measured current value Im generated by the current measurement unit 16, and determines that the rotor of the motor 3 is idling when the maximum measured current value Im on the negative side, which is the inverter circuit direction, is smaller than the idling threshold value (the negative value is large).

[0111] When the rotor of the motor 3 is idling, an inductive kickback occurs at the timing of switching to the discharge mode, and a current flows in the inverter circuit direction from the ground toward 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 charge mode increases, so the period of the inductive kickback becomes longer and the kickback current flowing through the shunt resistor Rs in the inverter circuit direction becomes larger, and this is used for the judgment. The idling judgment unit 122 can adopt, for example, a value in the range from a current measurement value (small negative value) due to the current flowing through the shunt resistor Rs due to the inductive kickback when the rotor of the motor 3 is stopped to a current measurement value (large negative value) corresponding to the current flowing through the shunt resistor Rs due to the inductive kickback when the rotor of the motor 3 is idling at the lowest rotation speed.

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

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

[0114] In the slip detection unit 120, in order to set the switch state to enable rotor slip detection, after power-on, the first switching unit 121a generates the first slip control signal Id1 corresponding to the free mode until the drive command acquisition unit 11 receives the speed command signal Sc. In the slip detection unit 120, the second switching unit 121b generates the second slip control signal Id2 during the charging time (period corresponding to the charging mode). In the slip detection unit 120, the first switching unit 121a again generates the first slip control signal Id1 during the discharging time (period corresponding to the discharging mode) after that. Note that after the discharging time, the first switching unit 121a may generate the first slip control signal Id1 corresponding to the free mode.

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

[0116] The charging time can be set to 10 times the time constant determined by the winding resistance and inductance of the coil of the motor 3. The coil of the motor 3 can be regarded as an RL series circuit because it has a winding resistance and an inductance, and the time until the winding current stabilizes is 10 times the time constant. For example, when the winding resistance is 0.44 Ω and the inductance is 0.4333 mH, the time constant is 1 msec. In this case, the charging time can be set to 10 msec. A longer charging time makes it clearer to determine whether the rotor is stopped or spinning at a low rotation speed, but a shorter charging time is preferable because the inverter circuit will be in a short brake state, and therefore the period of the rotor spin detection process will be shorter.

[0117] The discharge time may be a time equal to or greater than the time constant of the delay circuit 31 in the current detection circuit 22, because the kickback current flowing through the shunt resistor Rs in the inverter circuit direction attenuates and converges to zero due to inductive kickback. At this time, if the maximum current can be measured in the inverter circuit direction, it is possible to determine whether the rotor of the motor 3 is in an idling state, so the discharge time may be reached when the measured current in the inverter circuit direction becomes small. The discharge time may be set to a time equal to or greater than 0.5 times the time constant determined by the winding resistance and inductance of the coil of the motor 3. The time constant of 0.5 times is the timing at which the kickback current flowing through the shunt resistor Rs in the inverter circuit direction attenuates and converges to about 60% of the peak value, but in the discharge mode, it is sufficient to detect the maximum current in the shunt resistor Rs in the inverter circuit direction. For example, when the winding resistance is 0.44 Ω and the inductance is 0.4333 mH, the time constant is 1 msec. In this case, the discharge time may be set to 0.5 msec.

[0118] In the state control unit 12 , the initial position detection unit 130 has 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 generates an initial position detection signal Pd that turns on and off the high-side switches Q1, Q3, and Q5 and the low-side switches Q2, Q4, and Q6 of the inverter circuit 2a so as to sequentially switch the energized sectors without rotating the rotor of the motor 3, thereby energizing and cutting off the current in the energizing direction of the coils corresponding to the energized sectors. The initial position detection signal Pd will be described in detail later.

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

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

[0122] In the above estimation method in the position estimation unit 133, it may be difficult to determine that the total current value is the largest with little difference between the peak values ​​of the energization current and the peak value of the kickback current for each energized sector. In this case, the position estimation unit 133 may execute the same method again to estimate the rotor position, but may also identify the energized sector corresponding to the initial rotor position by executing the following two methods alone or sequentially as additional estimation methods to the above estimation.

[0123] As a first method of the additional estimation method, the position estimation unit 133 acquires the current-carrying sector in which the peak value of the current flowing in the direction to ground is the largest, and the current-carrying sector in which the peak value of the kickback current due to the inductive kickback flowing in the direction to the inverter circuit is the largest. The position estimation unit 133 estimates the position according to the number of the acquired current-carrying sectors as follows.

[0124] (1) If there is one current-carrying sector in which the peak value of the current flowing in the direction of ground is the maximum, and one current-carrying sector in which the peak value of the kickback current due to inductive kickback flowing in the direction of the inverter circuit is the maximum, and these are the same current-carrying sectors, it is estimated that the rotor position is at a position corresponding to the same current-carrying sector.

[0125] (2) If there is one current-carrying sector in which the peak value of the current flowing toward ground is the maximum, and there is one current-carrying sector in which the peak value of the kickback current due to inductive kickback flowing toward the inverter circuit is the maximum, and the current-carrying sectors are different, the rotor initial position detection process is executed again.

[0126] (3) If there is one current-carrying sector in which the peak value of the current flowing in the direction toward ground is the maximum, and there are multiple current-carrying sectors in which the peak value of the kickback current due to inductive kickback flowing in the direction toward the inverter circuit is the maximum, including one current-carrying sector in which the peak value of the current flowing is the maximum, it is estimated that the rotor position is at a position corresponding to the one current-carrying sector in which the peak value of the current flowing is the maximum.

[0127] (4) If there is one current-carrying sector in which the peak value of the current flowing in the direction toward ground is the maximum, and there are multiple current-carrying sectors in which the peak value of the kickback current due to inductive kickback flowing in the direction toward the inverter circuit is the maximum, but this does not include one current-carrying sector in which the peak value of the current flowing in the direction toward the inverter circuit is the maximum, the rotor initial position detection process is executed again.

[0128] (5) If there are multiple current-carrying sectors in which the peak value of the current flowing toward ground is the largest, and there are multiple current-carrying sectors in which the peak value of the kickback current due to inductive kickback flowing toward the inverter circuit is the largest, including one common current-carrying sector, it is estimated that the rotor position is at a position corresponding to the common current-carrying sector.

[0129] (6) If there are multiple energized sectors in which the peak value of the energized current flowing toward ground is the maximum, and if there are multiple energized sectors in which the peak value of the kickback current due to inductive kickback flowing toward the inverter circuit is the maximum, but these sectors do not include a common energized sector, the rotor initial position detection process is executed again.

[0130] As a second method of the additional estimation method, the position estimation unit 133 obtains the current differences of three bidirectional energizations from the "total current value" of each energization sector by using a total current value, which is a current value obtained by summing the peak value of the energization current flowing in the direction of ground and the peak value of the kickback current due to the inductive kickback flowing in the direction of the inverter circuit, for each energization sector. When the maximum value of the current differences of the three bidirectional energizations is one, it is estimated that the rotor position is located at a position corresponding to the energization sector with the largest "total current value" among the two energization sectors of the bidirectional energization with this maximum value. Specifically, the three bidirectional energizations are the three combinations of energization sector 4 and energization sector 3, energization sector 2 and energization sector 5, and energization sector 1 and energization sector 6, whose current vectors are 180 degrees apart from each other. In this case, for example, the current difference dIu between the energized sector 4 and the energized sector 3 is the difference between the total current value of the energized sector 4 and the total current value of the energized sector 3. The other bidirectional energizations are calculated in the same manner to obtain the current differences dIu, dIv, and dIw of the three bidirectional energizations. Next, the largest current difference among the three bidirectional energizations is identified, and it is estimated that the rotor position is located at a position corresponding to the energized sector with the largest "total current value" among the two identified bidirectional energizations. For example, if the largest current difference among the three bidirectional energizations is dIu, it is estimated that the rotor position is located at a position corresponding to the energized sector with the largest "total current value" among the energized sector 4 and the energized sector 3. In addition, if the maximum value of the current difference between the three bidirectional energizations is two and the "total current value" of the four energization sectors of these bidirectional energizations is different, it may be estimated that the rotor position is at the position corresponding to the energization sector with the largest "total current value".

[0131] Next, a detailed description will be given of the mode transition when the idling detection unit 120 detects rotor idling to confirm that the rotor of the motor 3 is stopped after power is turned on. In the state control unit 12, the idling detection unit 120 detects the rotor is not idling as a result of rotor idling detection (waits for the rotor to stop), and then the initial position detection unit 130 detects the rotor initial position.

[0132] 10 and 11 are timing charts showing an example of signal waveforms from when the speed command signal Sc is input until rotor freewheel detection is completed after power is applied to the motor unit 100. Fig. 10 is a timing chart when the rotor of the motor 3 is not moving at all, and Fig. 11 is a timing chart when the rotor of the motor 3 is moving (freewheeling).

[0133] 10 and 11 show, from top to bottom, the waveforms of the speed command signal Sc, the drive signals input to the gates of the switching elements Q1 to Q6, the idling trigger signal Ir that controls the switch of the sampling circuit 51 in the current measurement unit 16, the shunt current Is detected in the shunt resistor Rs of the current detection circuit 22, and the U-phase winding current. The shunt current Is is a current that flows through the shunt resistor Rs of the current detection circuit 22, and corresponds to the current detection signal Vs.

[0134] As shown in Figures 10 and 11, the motor drive control device 10 goes through a free mode, a charge mode, a discharge mode, and then returns to the free mode. At this time, the motor drive control device 10 starts from the free mode after power is turned on. Note that, although the timing charts shown in Figures 10 and 11 show an example in which the free mode is entered again after the discharge mode, this is not limiting.

[0135] In the free mode, the inverter circuit 2a is put into a first switch state by the first idling control signal Id1 generated by the first switching unit 121a. Specifically, the first idling control signal Id1 sets all the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a to a low level, turning off all the switches of the inverter circuit 2a. 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 becomes zero. Also, no current flows through the shunt resistor Rs.

[0136] 10 and 11, 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 acquires the current detection signal Vs output from the current detection circuit 22, and can use it as an offset since no current flows through the shunt resistor Rs.

[0137] Next, in the charging mode, the inverter circuit 2a is put into a second switch state by the second idling control signal Id2 generated by the second switching unit 121b. Specifically, the second idling control signal Id2 causes all of the drive signals input to the gates of the switching elements Q2, Q4, and Q6 of the lower arm of the switching elements Q1 to Q6 constituting the inverter circuit 2a to be at a high level, turning on all of the low-side switches of the inverter circuit 2a.

[0138] In this state, when the rotor of the motor 3 is not moving at all, no current flows through the coil of the motor 3 and the shunt resistor Rs, as in the free mode, as shown in Fig. 10. On the other hand, when the rotor of the motor 3 is moving, an induced electromotive force is generated in the coil of the motor 3, and a closed circuit is formed by the coil of the motor 3 and the switching elements Q2, Q4, and Q6 that are turned on in the inverter circuit 2a, as shown in Fig. 11, causing a current to circulate between the coil of the motor 3 and the inverter circuit 2a, and an induced current corresponding to the rotation speed of the rotor of the motor 3 flows in the coil, but at this time, the shunt resistor Rs is not included in the closed circuit, so no current flows through the shunt resistor Rs.

[0139] 10 and 11, 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 may be set to a high level at a predetermined timing. In this case, the current measuring unit 16 acquires 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. Note that if an offset is acquired in the free mode, it is not necessary to acquire the offset again at this timing.

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

[0141] In this state, if the rotor of the motor 3 is moving (spinning freely), the current circulating between the coil of the motor 3 and the inverter circuit 2a during this period will continue to flow through the coil, causing all switching elements to turn off, resulting in an inductive kickback in the inverter circuit. This inductive kickback causes a current to instantaneously increase in the inverter circuit direction from the ground toward the inverter circuit 2a in the shunt resistor Rs, and then converges to zero. At this time, the current flowing through the shunt resistor Rs is detected by the current detection circuit 22, and is continuously measured by the current measurement unit 16 to measure the maximum current in the inverter circuit direction. This makes it possible to determine in a short time that the rotor of the motor 3 is spinning freely, although it is not possible to determine the direction of rotation of the rotor of the motor 3.

[0142] In the discharge mode, when the current mask time has elapsed a predetermined mask time, the idling trigger signal Ir for measuring the shunt current Is becomes high level at a predetermined timing. The predetermined mask time is set as a period for removing electromagnetic noise caused by switching of the inverter circuit 2a due to switching of the drive signal. When the current mask time has elapsed the predetermined mask time, the current measurement unit 16 acquires the current detection signal Vs output from the current detection circuit 22 and measures the current flowing through the shunt resistor Rs.

[0143] FIG. 11 shows the shunt current Is and the U-phase winding current in two states. When the rotation speed due to the freewheeling of the rotor is low, the period of the U-phase winding current (dotted line) in the charging mode is long and the amplitude is small, and a small shunt current (dotted line) is generated on the negative side, which is the inverter circuit direction, due to inductive kickback in the discharging mode, and the kickback current flowing in the inverter circuit direction of the shunt resistor Rs is small. On the other hand, when the rotation speed due to the freewheeling of the rotor is high, the period of the U-phase winding current (dotted line) in the charging mode is short and the amplitude is large, and a large shunt current (dotted line) is generated on the negative side due to inductive kickback in the discharging mode, and the kickback current flowing in the inverter circuit direction of the shunt resistor Rs is large. In either case, the maximum current in the inverter circuit direction of the shunt current Is observed by the freewheeling determination unit 122 is smaller (a larger negative value) than the freewheeling threshold value (double-dotted line) for determining freewheeling of the rotor, so it is determined that the rotor of the motor 3 is freewheeling. If it is determined that the rotor is spinning, the rotor may be checked for stoppage by periodically repeating the rotor spin detection. At this time, the inverter circuit may be periodically put into a short brake state in order to shorten the time until the rotor stops.

[0144] Next, energization and cutoff for each energized sector when initial position detection unit 130 detects the initial rotor position from a state in which the rotor is stopped (not rotating idly) will be described in detail.

[0145] 12 and 13 are timing charts showing an example of signal waveforms from when the motor unit 100 is powered on, when the speed command signal Sc is input, when it is confirmed that the rotor has stopped, until the rotor initial position detection is completed. Fig. 14 is a timing chart showing another example of signal waveforms of energization and cutoff for one energized sector in rotor initial position detection from when the motor unit 100 is powered on, when the speed command signal Sc is input, when it is confirmed that the rotor has stopped, and then. In this embodiment, an example will be described in which the energization method is a 1-2 phase excitation method.

[0146] 12 to 14, from the top, there are shown the speed command signal Sc, the drive signals input to the gates of the switching elements Q1 to Q6, the measurement trigger signal Tm that controls the switch of the sampling circuit 51 in the current measurement unit 16, and the shunt current Is detected in the shunt resistor Rs of the current detection circuit 22. The shunt current Is is a current that flows through the shunt resistor Rs of the current detection circuit 22, and is a current that corresponds to the current detection signal Vs. The idling trigger signal Ir and the shunt current Is in the detection of the idling of the rotor until waiting for the rotor to stop have been explained in Figs. 10 and 11, so they are omitted here.

[0147] There are three methods for turning on and off the current for each power sector: [1: normal method], [2: complementary cutoff method], and [3: silent method]. Each method will be explained separately. Figure 12 is a timing chart for the normal method, Figure 13 is a timing chart for the complementary cutoff method, and Figure 14 is a timing chart for the silent method.

[0148] [1: Normal method] As shown in Fig. 12, in the normal method, the motor drive control device 10 switches between energized sectors, passing through energized mode and cutoff mode, and then returning to free mode. Note that the timing chart shown in Fig. 12 gives an example in which the free mode is entered after the final cutoff mode, but this is not limiting.

[0149] First, the energization is performed in the energization mode for the energized sector 3. In the energized sector 3, as shown in FIG. 3, energization is performed so that the current flows from the U-phase to the V-phase to the W-phase. Specifically, the initial position detection signal generating unit 131 generates an initial position detection signal Pd that turns on the switching elements Q1, Q4, and Q6 for a predetermined magnetic saturation time (t10 to t12), and the peak current acquiring unit 132 outputs a pulse of the measurement trigger signal Tm to the current measuring unit 16 at a timing (t11) just before the current energization time elapses the predetermined magnetic saturation time, taking into account the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) that flows through the shunt resistor Rs toward the ground during energization in the energized sector 3.

[0150] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q1, Q4, and Q6 from on to off. When the current mask time has passed a predetermined mask time from the timing (t12) when the switching elements Q1, Q4, and Q6 were turned off (t13), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm (t19). This allows the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs in the inverter circuit direction at the time of interruption in the energization sector 3 to be acquired, and also indicates that the shunt current Is has returned to zero again. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it notifies the initial position detection signal generation unit 131 of the fact. By receiving this notification, the initial position detection signal generator 131 can confirm that the magnitude of the kickback current has converged to zero. By utilizing this convergence of the shunt current to zero, the next current measurement becomes accurate and the measurement time per current-carrying sector can be shortened.

[0151] Next, the energization is performed in the energization mode for the energized sector 4. In the energized sector 4, as shown in FIG. 3, energization is performed so 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 an initial position detection signal Pd that turns on the switching elements Q2, Q3, and Q5 for a predetermined magnetic saturation time (t20 to t22), and the peak current acquiring unit 132 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 elapses the predetermined magnetic saturation time, taking into consideration the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) flowing in the direction of ground through the shunt resistor Rs during energization in the energized sector 4.

[0152] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q2, Q3, and Q5 from on to off. When the current mask time has passed a predetermined mask time from the timing (t22) when the switching elements Q2, Q3, and Q5 were turned off (t23), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm (t29). This allows the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs in the inverter circuit direction at the time of interruption in the energization sector 4 to be acquired, and also indicates that the shunt current Is has returned to zero again. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it notifies the initial position detection signal generation unit 131 of this fact. By receiving this notification, the initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero.

[0153] Next, the energization is performed in the energization mode for the energized sector 6. In the energized sector 6, as shown in FIG. 3, energization is performed so 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 (t29), the initial position detection signal generating unit 131 generates an initial position detection signal Pd that turns on the switching elements Q2, Q4, and Q5 for a predetermined magnetic saturation time (t30 to t32), and the peak current acquiring unit 132 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 elapses the predetermined magnetic saturation time, taking into consideration the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) flowing in the direction of ground through the shunt resistor Rs during energization in the energized sector 6.

[0154] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q2, Q4, and Q5 from on to off. When the current mask time has passed a predetermined mask time from the timing (t32) when the switching elements Q2, Q4, and Q5 are turned off (t33), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm (t39). This allows the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs toward the inverter circuit when the energization sector 6 is interrupted to be acquired, and also indicates that the shunt current Is has returned to zero again. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it notifies the initial position detection signal generation unit 131 of the fact. By receiving this notification, the initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero.

[0155] Next, the energization is performed in the energization mode for the energized sector 1. In the energized sector 1, as shown in FIG. 3, energization is performed so 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 an initial position detection signal Pd that turns on the switching elements Q1, Q3, and Q6 for a predetermined magnetic saturation time (t40 to t42), and the peak current acquiring unit 132 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 elapses the predetermined magnetic saturation time, taking into consideration the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) flowing in the direction of ground through the shunt resistor Rs during energization in the energized sector 1.

[0156] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q1, Q3, and Q6 from on to off. When the current mask time has passed a predetermined mask time from the timing (t42) when the switching elements Q1, Q3, and Q6 were turned off (t43), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm (t49). This allows the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs in the inverter circuit direction at the time of interruption in the energization sector 1 to be acquired, and also indicates that the shunt current Is has returned to zero again. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it notifies the initial position detection signal generation unit 131 of the fact. By receiving this notification, the initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero.

[0157] Next, the energization is performed in the energization mode for the energized sector 5. In the energized sector 5, as shown in FIG. 3, energization is performed so 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 (t49), the initial position detection signal generating unit 131 generates an initial position detection signal Pd that turns on the switching elements Q2, Q3, and Q6 for a predetermined magnetic saturation time (t50 to t52), and the peak current acquiring unit 132 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 elapses the predetermined magnetic saturation time, taking into consideration the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) flowing in the direction of ground through the shunt resistor Rs during energization in the energized sector 5.

[0158] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q2, Q3, and Q6 from on to off. When the current mask time has passed a predetermined mask time from the timing (t52) when the switching elements Q2, Q3, and Q6 were turned off (t53), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm (t59). This allows the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs in the inverter circuit direction at the time of interruption in the energization sector 5 to be acquired, and also indicates that the shunt current Is has returned to zero again. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it notifies the initial position detection signal generation unit 131 of the fact. By receiving this notification, the initial position detection signal generating unit 131 can confirm that the magnitude of the kickback current has converged to zero.

[0159] Next, the energization is performed in the energization mode for the energized sector 2. In the energized sector 2, as shown in FIG. 3, energization is performed so 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 an initial position detection signal Pd that turns on the switching elements Q1, Q4, and Q5 for a predetermined magnetic saturation time (t60 to t62), and the peak current acquiring unit 132 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 elapses the predetermined magnetic saturation time, taking into consideration the sampling time of the A / D conversion in the current measuring unit 16. This makes it possible to acquire the peak value of the shunt current Is (energization current) flowing in the direction of ground through the shunt resistor Rs during energization in the energized sector 2.

[0160] When the current energization time has passed a predetermined magnetic saturation time, the initial position detection signal generation unit 131 transitions to the interruption mode and generates an initial position detection signal Pd that changes the switching elements Q1, Q4, and Q5 from on to off. When the current mask time has passed a predetermined mask time from the timing (t62) when the switching elements Q1, Q4, and Q5 were turned off (t63), the peak current acquisition unit 132 starts outputting a pulse of the measurement trigger signal Tm to the current measurement unit 16. When the peak current acquisition unit 132 confirms that the shunt current Is has converged to almost zero, it stops outputting the pulse of the measurement trigger signal Tm. This makes it possible to acquire the peak value of the shunt current Is (kickback current) flowing through the shunt resistor Rs toward the inverter circuit when the energization sector 2 is interrupted, and also to determine that the shunt current Is has returned to zero again.

[0161] When current measurement is completed in all energized sectors, the system transitions to free mode, and the rotor position is estimated based on the total current value of the peak value of the energized current and the peak value of the kickback current for each energized sector, and detection of the initial rotor position is completed.

[0162] [2: Complementary blocking method] As shown in Fig. 13, the complementary cutoff method differs from the normal method in that in the complementary cutoff mode, a signal is input to switch the gates of the switching elements Q1 to Q6 so that the kickback current caused by the inductive kickback flows through the on-resistance of the switching elements instead of through the parasitic diodes of the switching elements. The other configurations are the same as those of the normal method shown in Fig. 12, so only the differences from the normal method shown in Fig. 12 will be explained.

[0163] In order to make the kickback current pass through the on-resistance of the switching elements, it is sufficient to turn on the switches among the switching elements Q1 to Q6 of the inverter circuit 2a that are complementary to the energized state. Specifically, after a dead time period for preventing short-circuiting between the upper and lower switching elements, a signal for switching the gates of the switching elements Q1 to Q6 is input so that the switches that are complementary to the energized state are turned on. That is, in the energized sector 3 that is the first energized sector, in the complementary cutoff mode, the switching elements Q2, Q3, and Q5 are turned on, which are the same as those in the energized sector 4. In the complementary cutoff mode, when it is confirmed that the shunt current Is has converged to almost zero, the on-state of the switching elements Q2, Q3, and Q5 that are intended to make the kickback current pass through the on-resistance of the switching elements is released (turned off).

[0164] Similarly, in the complementary shutdown mode, when the next energized sector is energized sector 4, the switching elements Q1, Q4, and Q6 are turned on, the same as in energized sector 3. In the complementary shutdown mode, when the next energized sector is energized sector 6, the switching elements Q1, Q3, and Q6 are turned on, the same as in energized sector 1. In the complementary shutdown mode, when the next energized sector is energized sector 1, the switching elements Q2, Q4, and Q5 are turned on, the same as in energized sector 6. In the complementary shutdown mode, when the next energized sector is energized sector 5, the switching elements Q1, Q4, and Q5 are turned on, the same as in energized sector 2. In the complementary shutdown mode, when the next energized sector is energized sector 2, the switching elements Q2, Q3, and Q6 are turned on, the same as in energized sector 5.

[0165] With this configuration, the kickback current caused by the inductive kickback generated in the inverter circuit during cutoff flows through the on-resistance rather than through the parasitic diode of the switching element, shortening the time it takes for the shunt current Is to converge to zero. As a result, it is possible to shorten the measurement time per current-carrying sector and the time required for current-carrying in all six directions to detect the rotor initial position.

[0166] [3: Silent method] As shown in FIG. 14, in the current conduction mode of the normal method, a pulse having a continuous length is generated as a drive signal during a predetermined magnetic saturation time, but in the current conduction mode of the silent method, a signal is input to switch the gates of the switching elements Q1 to Q6 by dividing the predetermined magnetic saturation time into multiple pulses of short length so that a magnetic field is gradually formed in the coil. That is, in the current conduction mode of the silent method, the current is divided into multiple predetermined times, and the current flowing through the coil is increased by repeating the current conduction with a small current. The other configurations are the same as those of the normal method shown in FIG. 12, so only the differences from the normal method shown in FIG. 12 will be described. Note that a complementary cutoff mode may be used instead of the cutoff mode.

[0167] In Fig. 14, in the energization mode, the high-side switching element is turned on and off by PWM drive, while the low-side switching element is always on. When the high-side and low-side are on at the same time, a current flows through the coil and shunt resistor, and when the high-side switching element is off, a circulating current is generated that circulates between the low-side switching element and the coil. This circulating current delays the attenuation of the current flowing through the coil, making it possible to reduce the current per energization and reduce magnetic noise. In Fig. 14, the low-side switching element is turned on at the same time as the high-side is turned on, but it can also be turned on at the same time as the energization mode starts (dotted line). Fig. 14 uses one energization sector as an example for explanation, but the other energization sectors also generate drive signals by dividing them into multiple short pulses in the same way.

[0168] This configuration makes it possible to prevent the generation of a "banging" magnetic sound caused by energization. In FIG. 14, in the energization mode, the high-side switching element is turned on and off by PWM drive and the low-side switching element is turned on, but this is not limited to this. For example, the high-side switching element may be turned on and the low-side switching element may be PWM driven. Furthermore, the duty of the PWM drive is constant, but this is not limited to this. For example, the duty of the PWM drive may be gradually increased.

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

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

[0171] First, when the motor drive control device 10 is powered on, as shown in FIG. 15, the free mode is selected in the state control unit 12 (step S110), and the first switching unit 121a generates a first idling control signal Id1 that switches the switching elements Q1 to Q6 that constitute the inverter circuit 2a to a first switch state (all FETs off) corresponding to the free mode (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 a first switch state in accordance with the first idling control signal Id1 generated in step S111. In response to this first idling control signal Id1, the switching elements Q1 to Q6 constituting the inverter circuit 2a are set to the first switch state as shown in FIG.

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

[0174] When starting the offset measurement process, as shown in FIG. 16, the state control unit 12 first clears the counter for the number of offset measurements and disables the offset calculator 54 (step S201).

[0175] Next, the state control unit 12 outputs an idling trigger signal Ir, controls the switch of the sampling circuit 51 of the current measurement 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). Note that although the shunt current Is at this time is zero, the voltage that offsets the output of the amplifier of the bidirectional current detection circuit 30 makes the current measurement value Im a value other than zero.

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

[0177] The state control unit 12 checks the counter for the number of offset measurements and determines whether the current number of offset measurements has exceeded a predetermined number of offset measurements (step S204).

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

[0179] Returning to FIG. 15, after the offset measurement in step S200, the state control unit 12 determines whether or not the drive command acquisition unit 11 has received a speed command signal Sc from a higher-level device (step S120).

[0180] If it is determined that the speed command signal Sc has not been received (step S120: No), the process returns to step S120 after a predetermined time has elapsed.

[0181] If it is determined that the speed command signal Sc has been received (step S120: Yes), the process waits for the rotor to stop (step S300).

[0182] In the rotor stop waiting in S300, since the switch state is already the first switch state corresponding to the free mode, the state control unit 12 first selects the charge mode (step S310) as shown in Fig. 17, and the second switching unit 121b generates the second idling control signal Id2 for switching to the second switch state (all LO side FETs on) corresponding to the charge mode. At this time, the charge time is reset in the state control unit 12 (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 switch state in accordance with the second idling control signal Id2 generated in step S310. In response to this second idling control signal Id2, the switching elements Q1 to Q6 constituting the inverter circuit 2a are set to the second switch state, for example, as shown in FIG.

[0184] In the state control unit 12, the second switching unit 121b determines whether or not the current charging time has elapsed a predetermined charging time since the second idling control signal Id2 was generated in step S311 (step S312).

[0185] In the state control unit 12, when the current charging time has elapsed a predetermined charging time since the second switching unit 121b generated the second idling control signal Id2 (step S312: Yes), the state control unit 12 transitions to the discharging mode (step S320), and the first switching unit 121a generates the first idling control signal Id1 for switching to the first switch state (all FETs off) corresponding to the discharging mode. At this time, the discharge time and the mask time are reset in the state control unit 12 (step S321).

[0186] The state control unit 12 switches the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switch state by generating the first idling control signal Id1 generated in step S321. That is, in response to the first idling control signal Id1, the switching elements Q1 to Q6 constituting the inverter circuit 2a are again put into the first switch state, for example, as shown in FIG.

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

[0188] In the shunt current measurement process of step S323, the state control unit 12 outputs an idling trigger signal Ir to the current measurement unit 16, controls the switch of the sampling circuit 51 of the current measurement unit 16, performs A / D conversion on the current detection signal Vs output from the current detection circuit 22, and further performs offset adjustment to generate a current measurement value Im. The current measurement 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 a 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 smaller than the threshold current value of the idling threshold (step S324). If the state control unit 12 determines that the absolute value of the current measurement value Im is smaller than the threshold current value (step S324: Yes), the rotor is in a stopped state, so the rotor stop waiting process is terminated and the state control unit 12 transitions to the free mode (step S330). On the other hand, if the state control unit 12 determines that the absolute value of the current measurement value Im is not smaller than the threshold current value (step S324: No), the rotor is in an idling state, so the rotor stop waiting process is executed again (step S324).

[0190] Returning to FIG. 15, in order to cause the initial position detection unit 130 to detect the initial position of the rotor, the state control unit 12 sequentially executes initial rotor position measurement (step S400) and initial rotor position estimation (step S500).

[0191] 18, in rotor initial position measurement (step S400), when an initial position detection signal generating unit 131 of the initial position detection unit 130 generates an initial position detection signal Pd for energizing / cutting off for each energized sector, the switching elements Q1 to Q6 of the inverter circuit 2a are turned on and off to energize / cut off the coils. A peak current acquiring unit 132 of the initial position detection unit 130 acquires the current measurement value Im of the current measuring unit 16 at a predetermined timing, thereby measuring the current for all energized sectors. In this embodiment, specifically, initial rotor position measurement 1 is performed for energized sector 3 (step S601), then initial rotor position measurement 2 is performed for energized sector 4 (step S602), initial rotor position measurement 3 is performed for energized sector 6 (step S603), initial rotor position measurement 4 is performed for energized sector 1 (step S604), initial rotor position measurement 5 is performed for energized sector 5 (step S605), and initial rotor position measurement 6 is performed for energized sector 2 (step S606).

[0192] As shown in FIG. 19, in initial rotor position measurement n (step S600), which is a rotor initial position measurement in one current-carrying sector, the initial position detection unit 130 first selects a current-carrying mode (step S610), resets the current-carrying time, and generates an initial position detection signal Pd by the initial position detection signal generation unit 131 for turning on one of the switching elements Q1 to Q6 corresponding to the current-carrying sector so as to achieve a switch state according to the current-carrying sector of the initial rotor position measurement n to be measured (step S611).

[0193] The peak current acquisition unit 132 determines whether the current conduction time has passed a predetermined conduction time, which is a predetermined magnetic saturation time (step S612), and if the predetermined conduction time has not passed (step S612: NO), waits until the predetermined conduction time has passed. If the current conduction time has passed the predetermined conduction time (step S612: YES), the peak current acquisition unit 132 performs shunt current measurement (step S613). The peak current acquisition unit 132 acquires a current measurement value Im, which measures the current flowing through the shunt resistor Rs, as the peak value of the conduction current in the conduction mode.

[0194] When the current energization time has elapsed a predetermined energization time, the initial position detection signal generating unit 131 transitions to the cutoff mode (step S620), resets the mask time, and generates an initial position detection signal Pd that turns off all of the switching elements Q1 to Q6 (step S621).

[0195] The peak current acquisition unit 132 determines whether the current mask time has passed a predetermined mask time (step S622), and if the predetermined mask time has not passed (step S622: NO), waits until the predetermined mask time has passed. If the current mask time has passed the predetermined mask time (step S622: YES), the peak current acquisition unit 132 performs shunt current measurement (step S623). The peak current acquisition unit 132 acquires a 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 mask time has elapsed a predetermined mask time, the initial position detection signal generating unit 131 waits for the kickback current to reach zero and determines whether the absolute value of the current measurement value Im, which measures the current flowing through the shunt resistor Rs, is smaller than the threshold current value corresponding to zero current (step S624). If the initial position detection signal generating unit 131 determines that the absolute value of the current measurement value Im is not smaller than the threshold current value (step S624: NO), the current has not converged to zero current, so it performs shunt current measurement processing (step S625) and performs the determination of step S624 again. On the other hand, if the initial position detection signal generating unit 131 determines that the absolute value of the current measurement value Im is smaller than the threshold current value (step S624: YES), the current has converged to zero current, so it temporarily transitions to a free mode in which no signal is given to the switching elements Q1 to Q6 of the inverter circuit 2a (step S630). This waiting for the kickback current to reach zero current results in a state in which no current flows through the shunt resistor Rs. In other words, since there is no influence from the previous energized sector, it is possible to perform correct current measurement in the rotor initial position measurement of the next energized sector, and the measurement time per energized sector is shortened, thereby shortening the measurement time for all six-directional energization in the rotor initial position measurement.

[0197] 15, once the peak values ​​of the energizing current and the kickback current are acquired for all energized sectors, the position estimator 133 executes rotor initial position estimation (step S500). Once the rotor position is estimated by the initial rotor position estimation, excitation, motor drive by forced commutation start, etc. are executed.

[0198] As described above, the control circuit 1 of the motor drive control device 10 according to the embodiment turns on and off the high-side switches Q1, Q3, Q5 and low-side switches Q2, Q4, Q6 of the inverter circuit 2a so as to sequentially switch the current-carrying sectors without rotating the rotor of the motor 3, and generates an initial position detection signal Pd that performs current supply and cut-off in the current-carrying direction of the coil corresponding to the current-carrying sector. Based on the current detected in the bidirectional current detection circuit 30 when the initial position detection signal Pd is generated, the control circuit 1 obtains, for each current-carrying sector, a peak value of the current that flows toward ground when current is supplied, and a peak value of the kickback current due to inductive kickback that flows toward the inverter circuit when current is cut off, and estimates the rotor position based on the peak value of the current supply and the peak value of the kickback current for each current-carrying sector.

[0199] This enables the motor drive control device 10 to estimate the rotor position using a low-resolution current measuring device in a short period of time.

[0200] Furthermore, in the motor drive control device 10 according to the above embodiment, the control circuit 1 has an initial position detection signal generation unit 131 which generates an initial position detection signal Pd which is input to the inverter circuit 2a to sequentially energize and cut off the current in the current flow direction of the coil for each current flow sector, a peak current acquisition unit 132 which acquires the peak value of the current flow and the peak value of the kickback current for each current flow sector, and a position estimation unit 133 which estimates the position of the rotor based on the peak value of the current flow and the peak value of the kickback current for each current flow sector.

[0201] This makes it possible to estimate the rotor position based on the peak value of the energizing current and the peak value of the kickback current for each energizing sector obtained by sequentially switching, energizing, and cutting off each switching element Q1 to Q6 of the inverter circuit 2a without rotating the rotor of the motor 3.

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

[0203] This makes it possible to perform correct current measurement in the initial rotor position measurement of the next current-carrying sector, and also shortens the time between current-carrying sectors, thereby shortening the measurement time for all six-directional current-carrying in the initial rotor position measurement.

[0204] Furthermore, in the motor drive control device 10 according to the above embodiment, the peak current acquisition unit 132 acquires the peak value of the energizing current, and acquires the kickback current after the mask time has elapsed.

[0205] This makes it possible to obtain the peak value of the kickback current.

[0206] Furthermore, in the motor drive control device 10 according to the above embodiment, the position estimation unit 133 compares the total current value of the energized current and the kickback current for each energized sector, and estimates the position corresponding to the energized sector with the maximum total current value as the rotor position.

[0207] This makes it possible to estimate the rotor position based on a larger current measurement range than in the past.

[0208] Furthermore, in the motor drive control device 10 according to the above embodiment, when the current-carrying sector with the maximum total current value cannot be determined as a single one, the position estimation unit 133 acquires the current-carrying sector with the maximum peak value of the current flowing in the direction of ground and the current-carrying sector with the maximum peak value of the kickback current due to inductive kickback flowing in the direction of the inverter circuit, and estimates the rotor position according to the number of current-carrying sectors acquired.

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

[0210] Furthermore, in the motor drive control device 10 according to the above embodiment, when the current supply sector with the maximum total current value cannot be determined as one, the position estimation unit 133 obtains the current differences of three bidirectional currents from the total current value, which is the current value obtained by summing the peak value of the current supply current flowing in the direction of ground and the peak value of the kickback current due to inductive kickback flowing in the direction of the inverter circuit, for each current supply sector, and when the maximum current difference of the three bidirectional currents is one, it estimates that the rotor position is at a position corresponding to the current supply sector with the largest total current value out of the two bidirectional current supply sectors with the maximum current difference.

[0211] This makes it possible to estimate the rotor position.

[0212] Furthermore, in the motor drive control device 10 according to the above embodiment, the initial position detection signal generating unit 131 generates an initial position detection signal Pd that is set so that the energization in the energization direction of the coil corresponding to the energized sector is divided into multiple predetermined times.

[0213] This allows the amount of current flowing each time to be reduced, making it possible to avoid the occurrence of a "banging" magnetic sound.

[0214] In the motor drive control device 10 according to the above embodiment, the initial position detection signal generating unit 131 generates an initial position detection signal Pd that is set to turn on one of the high-side switches Q1, Q3, Q5 and the low-side switches Q2, Q4, Q6 of the inverter circuit 2a, which is in a complementary relationship with respect to the time when current is applied, at the timing of cut-off in the current-applied sector.

[0215] According to this, at the time of interruption, the kickback current due to the inductive kickback generated in the inverter circuit 2a passes through the on-resistance instead of through the parasitic diode of the switching element, so that the time for the shunt current Is to converge to zero can be shortened. As a result, the time required to detect the rotor initial position can be shortened.

[0216] In the motor drive control device 10 according to the above embodiment, the control circuit 1 further includes a first switching unit 121a that switches from a first switch state in which all of the high-side switches Q1, Q3, Q5 and the low-side switches Q2, Q4, Q6 included in the inverter circuit 2a are turned off to a second switch 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 turned on, a second switching unit 121b that switches from the second switch state to the first switch state, and an idling determination unit 122 that determines whether the rotor of the motor 3 is spinning based on the current flowing through the shunt resistor Rs when switching from the second switch state to the first switch state. The control circuit 1 generates an initial position detection signal Pd after confirming in the idling determination unit 122 that the rotor of the motor 3 is not spinning.

[0217] According to this, since it is possible to detect whether the rotor of the motor 3 is in an idling state or not, it is possible to shorten the waiting time for the rotor to stop.

[0218] Furthermore, in the motor drive control device 10 according to the above embodiment, the control circuit 1 further includes a current measuring unit 16 that detects in advance the output signal Vs from the bidirectional current detection circuit 30 as an offset when no current flows through the shunt resistor Rs, and adjusts the signal Vs output from the bidirectional current detection circuit 30 with the offset when determining whether or not there is a spin and estimating the rotor position, and outputs the adjusted signal to the spin determination unit 122 and the position estimation unit 133.

[0219] This makes it possible to detect the value of the current flowing through the shunt resistor Rs even when the current becomes negative.

[0220] <<Extension of the embodiment>> The invention made by the present inventors has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

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

[0222] In the embodiment, the motor drive control device 10 is described based on an example in which a position sensor and a measurement circuit for each phase voltage are not used, but a position sensor and a measurement circuit for each phase voltage may be provided. Even in this case, the position sensor and the measurement circuit for each phase voltage do not need to be used when detecting rotor idling. As the position sensor, a Hall element that outputs a Hall signal may be used, or instead of such a Hall signal, another signal corresponding to the rotational position of the rotor of the motor 3 may be input as a rotational position detection signal. For example, an encoder, a resolver, or the like may be provided, and the detection signal may be input to the control circuit 1. As the measurement circuit for each phase voltage, an A / D converter or a signal from a comparator that compares each phase voltage with the neutral point voltage may be input as a rotational position detection signal.

[0223] In the embodiment, the control circuit 1 is not limited to the above-mentioned circuit configuration. The control circuit 1 can be configured in various ways to achieve the object of the present invention.

[0224] Specifically, in the current measuring unit 16, instead of the sampling circuit 51, a spin determination circuit may be configured using a comparator, and a signal serving as a spin threshold may be output from the D / A converter. When the maximum current detection signal Vs in the inverter circuit direction exceeds this spin threshold, it may be determined that the motor rotor is spinning, and a spin determination signal may be output to the state control unit 12.

[0225] In the embodiment, the rotor idle detection process is performed after the rotor stop waiting process is completed, but the rotor initial position detection process may be performed after waiting for a predetermined time to elapse, assuming that the rotor is stopped. The rotor idle detection process for confirming that the rotor has stopped is not limited to the method described above.

[0226] In the embodiments, the motor drive is not limited to sine wave drive, and the motor drive control method is not limited to vector control. For example, 120-degree energization control may be used.

[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. The number of poles of the motor 3 is also not limited. The order of the energized sectors is also not limited to the order described above.

[0228] The above-described flowchart is a specific example, and the present invention is not limited to this flowchart. For example, other processes may be inserted between each step, or the processes may be parallelized. [Explanation of symbols]

[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 command acquisition unit, 12... state control unit, 13... vector control unit, 14... PWM signal generation unit, 15... timing adjustment unit, 16... current measurement unit, 120... slip detection unit, 121a... first switching unit, 121b... second switching unit, 122... slip 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 conversion comparator, 53... comparator, 54... offset calculator, 100... motor unit, Q1 to 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... measured current, Iu, Iv, Iw... winding current, ωref... target rotation 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 control circuit that generates a drive control signal for driving a motor having at least one phase coil; a drive circuit including an inverter circuit including high-side switches and low-side switches connected in series to each other and provided corresponding to the coils of each phase of the motor, the drive circuit alternately turning on and off the high-side switches and the low-side switches in response to the drive control signal to switch the current flow direction of the coils of the corresponding phase, thereby rotating the rotor of the motor; a shunt resistor provided between the inverter circuit and ground; a bidirectional current detection circuit that detects a current flowing through the shunt resistor in both directions, that is, a ground direction from the inverter circuit toward the ground and an inverter circuit direction that is the opposite direction; The control circuit includes: generating an initial position detection signal for turning on and off the high-side switch and the low-side switch of the inverter circuit so as to sequentially switch the energized sectors without rotating the rotor of the motor, and energizing and cutting off the energized coils in the energizing direction corresponding to the energized sectors; based on a current detected by the bidirectional current detection circuit when the initial position detection signal is generated, a peak value of a current flowing in the direction toward ground when the current is applied and a peak value of a kickback current caused by an inductive kickback flowing in the direction toward the inverter circuit when the current is cut off are obtained for each of the energized sectors; estimating a position of the rotor based on a peak value of the energizing current and a peak value of the kickback current for each energizing sector; Motor drive control device.

2. 2. The motor drive control device according to claim 1, The control circuit includes: an initial position detection signal generating unit that generates the initial position detection signal by inputting the initial position detection signal to the inverter circuit to sequentially energize and cut off the current in the current direction of the coil for each current-carrying sector; a peak current acquisition unit that acquires a peak value of the energizing current and a peak value of the kickback current for each of the energizing sectors; a position estimator configured to estimate a position of the rotor based on a peak value of the energizing current and a peak value of the kickback current for each energizing sector. Motor drive control device.

3. 3. The motor drive control device according to claim 2, The initial position detection signal generation unit generating the initial position detection signal for energizing the next energized sector after confirming that the magnitude of the kickback current has converged to zero; Motor drive control device.

4. 3. The motor drive control device according to claim 2, The peak current acquisition unit A peak value of the energizing current is obtained, and the kickback current is obtained after a mask time has elapsed. Motor drive control device.

5. 3. The motor drive control device according to claim 2, the position estimation unit compares a total current value of the energization current and the kickback current for each energized sector, and estimates, as the position of the rotor, a position corresponding to the energized sector having a maximum total current value. Motor drive control device.

6. 6. The motor drive control device according to claim 5, when the current-carrying sector with the maximum total current value cannot be determined as a single current-carrying sector, the position estimation unit acquires the current-carrying sector with the maximum peak value of the current-carrying current flowing in the direction toward the ground and the current-carrying sector with the maximum peak value of the kickback current due to the inductive kickback flowing in the direction toward the inverter circuit, and estimates the rotor position according to the number of the acquired current-carrying sectors. Motor drive control device.

7. 6. The motor drive control device according to claim 5, When the current supply sector with the maximum total current value cannot be determined as one, the position estimation unit obtains current differences of three bidirectional currents from a total current value, which is a current value obtained by summing the peak value of the current supply current flowing in the direction to ground and the peak value of the kickback current due to inductive kickback flowing in the direction to the inverter circuit, for each of the current supply sectors, and when the maximum current difference of the three bidirectional currents is one, it estimates that the rotor position is at a position corresponding to the current supply sector with the largest total current value among the two bidirectional current supply sectors with the maximum current difference. Motor drive control device.

8. 3. The motor drive control device according to claim 2, the initial position detection signal generation unit generates the initial position detection signal set so that energization in a current direction of the coil corresponding to the current-carrying sector is performed in a divided number of predetermined times. Motor drive control device.

9. 3. The motor drive control device according to claim 2, the initial position detection signal generating unit generates the initial position detection signal set to turn on a high-side switch and a low-side switch of the inverter circuit, the high-side switch and the low-side switch being in a complementary relationship with respect to a time when the current is applied, at a timing of interruption in the current-applied sector. Motor drive control device.

10. 2. The motor drive control device according to claim 1, the control circuit includes a first switching unit configured to switch from a first switching state in which all of the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switching state in which at least two of the high-side switches or the low-side switches included in the inverter circuit are turned on; A second switching unit that switches from the second switch state to the first switch state; a slip determination unit that determines whether a rotor of the motor is slipping based on a current flowing through the shunt resistor when the switch state is switched from the second switch state to the first switch state, the control circuit generates the initial position detection signal after confirming that the rotor of the motor is not rotating freely by the rotation determining unit. Motor drive control device.

11. The motor drive control device according to claim 10, the control circuit further includes a position estimator that estimates a position of the rotor based on a peak value of the energizing current and a peak value of the kickback current for each energizing sector, the control circuit further includes a current measuring unit that detects an 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 with the offset when determining whether or not there is an idling motion and estimating a position of the rotor, and outputs the adjusted signal to the idling motion determination unit and the position estimation unit. Motor drive control device.

12. a drive circuit including an inverter circuit including high-side switches and low-side switches connected in series to each other and provided corresponding to the coils of each phase of the motor, and which alternately turns on and off the high-side switches and the low-side switches in response to the drive control signal to switch the direction of current flow through the coil of the corresponding phase, thereby rotating a rotor of the motor; a shunt resistor provided between the inverter circuit and ground; and a bidirectional current detection circuit that detects a current flowing through the shunt resistor in both directions, that is, in a ground direction from the inverter circuit to ground and in the inverter circuit direction, which is the opposite direction, a first step of generating an initial position detection signal for turning on and off the high-side switch and the low-side switch of the inverter circuit so as to sequentially switch energized sectors without rotating a rotor of the motor, thereby energizing and cutting off a current in a current direction of a coil corresponding to the energized sector; a second step of acquiring, for each of the energized sectors, a peak value of an energization current flowing in the direction toward ground when the energization is performed and a peak value of a kickback current due to an inductive kickback flowing in the direction toward the inverter circuit when the energization is interrupted, based on a current detected by the bidirectional current detection circuit when the initial position detection signal is generated; and a third step of estimating a position of the rotor based on a peak value of the energization current and a peak value of the kickback current for each energization sector. A method for detecting the initial position of a rotor.

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