Motor drive control device and method for detecting idle running of motor

Abstract

The invention provides a motor drive control device and a motor idling detection method, which can stably detect whether a motor is in an idling state in a short time. A motor drive control device includes: a control circuit configured to generate a drive control signal; a drive circuit having an inverter circuit including a switch provided corresponding to a coil of each phase of the motor, the drive circuit alternately turning on / off the switch according to the drive control signal to rotate a rotor of the motor; and a phase voltage detection circuit configured to detect a phase voltage generated between the inverter circuit and a coil of each phase of the motor, the control circuit being configured to generate an idle control signal to switch a switching state of the inverter circuit to idle a rotor of the motor, and the phase voltage detection circuit being configured to detect a phase voltage generated between the inverter circuit and the coil of each phase of the motor. After the current circulating between the coil of the motor and the inverter circuit is generated, it is determined that the motor is idle on the basis of the phase voltage generated by the phase voltage detection circuit according to the induced backlash generated when the path of the current is switched.

Description

Technical Field

[0001] The invention relates to a motor drive control device and a motor idling detection method. Background Art

[0002] Generally speaking, in a motor used in a fan for cooling the inside of an electronic device such as a server (hereinafter also referred to as a "fan motor"), even if the motor is not driven by a drive circuit for driving the motor, the motor may be in a rotating state, a so-called idling state, due to inertia or external force.

[0003] Patent document 1 describes a method for detecting the idling condition of a motor rotor. In this method, the rotation speed of the motor is extracted based on the current flowing through the current detection resistor while a predetermined switching element among a plurality of switching elements constituting the inverter circuit of the motor is energized, thereby detecting the rotation speed of the fan of the outdoor unit that is in an idling state due to external force even when the air conditioner is stopped. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-170928 Summary of the invention Problems to be solved by the invention

[0005] However, the method described in Patent Document 1 is to detect the rotation speed of a motor in an idling state, but sometimes the rotation speed of an idling motor is not detected, as long as the motor can be detected in a short time whether it is in an idling state. For example, when the rotor of the motor is idling, an induced electromotive force is generated, and when the coil of the motor and the inverter circuit do not form a closed circuit, an induced voltage is periodically generated in the coil (winding) of the motor, and when the coil of the motor and the inverter circuit form a closed circuit, an induced current is periodically generated in the coil of the motor. At this time, the winding resistance measurement and rotor initial position detection using the current flowing in the shunt resistor when the coil of the motor is energized are adversely affected by the periodic changes in the induced voltage and induced current, and therefore need to be implemented when the motor is not idling. Therefore, whether the motor is in an idling state can be used as a judgment indicator for executing various processes.

[0006] Furthermore, whether the motor is in an idling state can be easily detected by using a position sensor, but if the motor is in an idling state can be detected without using a position sensor, it is preferable in that the device configuration can be simplified.

[0007] Moreover, when using phase voltage to detect the idling of the motor, in the previous method, by setting all the switching elements that constitute the inverter circuit to be disconnected and put into a high impedance state, similar to the drive of the motor, the zero crossing of the differential voltage between the induced voltage generated in each winding due to the rotation of the rotor and the neutral point voltage obtained by synthesizing the voltages of all the windings can be used to detect whether the rotor is in an idling state. However, at low speeds, the induced voltage generated is small and the zero crossing detection time becomes longer. Therefore, there is a limit to the minimum detectable speed, and there is a problem that a stable motor idling judgment cannot be made in a short time.

[0008] Therefore, a motor drive control device is desired that can detect whether or not a motor is in an idling state stably in a short time with a simple configuration without using a position sensor.

[0009] The present invention is to solve the above-mentioned technical problems, and its object is to provide a motor drive control device that can stably detect whether the motor is in an idling state in a short time without using a position sensor. Technical Solution

[0010] A motor drive control device according to a representative embodiment of the present invention comprises: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit having an inverter circuit including a high side switch and a low side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, wherein the high side switch and the low side switch are alternately turned on / off according to the drive control signal to switch the energization direction of the coil of the corresponding phase, thereby rotating the rotor of the motor; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coils of each phase of the motor, wherein in the control circuit, when an idling control signal is generated instead of the drive control signal to switch the switch state of the inverter circuit to make the rotor of the motor idling, after an induced current circulates between the coil of the motor and the inverter circuit, the motor idling is determined based on the phase voltage generated in the phase voltage detection circuit according to the inductive kick generated in the inverter circuit when the path of the induced current is cut off. Effects of the Invention

[0011] According to one aspect of the present invention, a motor drive control device can stably detect whether a motor is in an idling state in a short time without using a position sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 1 is a diagram showing a configuration of a motor unit 100 including a motor drive control device 10 according to an embodiment. Figure 2It is a diagram for explaining the switch state corresponding to the free mode switched by the idling control signal Id. Figure 3 It is a diagram for explaining the switch state corresponding to the charging mode switched by the idling control signal Id. Figure 4 It is a diagram for explaining the switch state corresponding to the discharge mode switched by the idle control signal Id. Figure 5 1 is a diagram showing a functional block configuration of a control circuit 1 in a motor drive control device 10 according to the embodiment. Figure 6 2 is a diagram showing a configuration example of the differential voltage detection circuit 15 . Figure 7 It is a diagram showing a configuration example of the voltage determination unit 16 . Figure 8 It is a diagram showing a configuration example of the voltage measuring unit 17 . Fig. 9 1 is a diagram showing a timing chart showing an example of a signal waveform from when the speed command signal Sc is input after the power supply to the motor unit 100 is turned on until the determination of idling is completed. Fig.10 This is a first pattern of waveforms showing a pattern of a phase voltage generated in the phase voltage detection circuit in the discharge mode and a pattern of a differential voltage generated as a result thereof when the rotor of the motor 3 is idling. Fig.11 This is a second pattern showing a waveform of a phase voltage pattern generated in the phase voltage detection circuit in the discharge mode and a resultant differential voltage pattern when the rotor of the motor 3 is idling. Fig.12 This is a third pattern showing a waveform of a phase voltage pattern generated in the phase voltage detection circuit in the discharge mode and a resultant differential voltage pattern when the rotor of the motor 3 is idling. Fig.13 This is a fourth pattern showing the waveform of the pattern of the phase voltage generated in the phase voltage detection circuit in the discharge mode and the pattern of the differential voltage generated as a result thereof when the rotor of the motor 3 is idling. Fig.14 This is a fifth pattern showing the waveform of the pattern of the phase voltage generated in the phase voltage detection circuit in the discharge mode and the pattern of the differential voltage generated as a result thereof when the rotor of the motor 3 is idling. Fig.15 This is a sixth pattern showing the waveform of the pattern of the phase voltage generated in the phase voltage detection circuit in the discharge mode and the pattern of the differential voltage generated as a result thereof when the rotor of the motor 3 is idling. Fig.16This is a flowchart showing an example of a process flow when the power is turned on in the control circuit 1 of the motor drive control device 10 according to the embodiment. Fig.17 1 is a flowchart showing an example of the flow of measurement selection based on the measurement type selection signal Ss and the measurement phase selection signal Sm output from the state control unit 12 . Fig.18 This is a flowchart showing an example of the flow of ADC offset measurement implemented by the control circuit 1 of the motor drive control device 10 . Fig.19 1 is a flowchart showing an example of the flow of idling detection implemented by the control circuit 1 of the motor drive control device 10 . DETAILED DESCRIPTION

[0013] 1. Overview of implementation methods First, a typical embodiment of the invention disclosed in this application will be described in outline. Note that, in the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are indicated in parentheses.

[0014] [1] A motor drive control device (10) according to a representative embodiment of the present invention is characterized in that it comprises: a control circuit (1) for generating a drive control signal (Sd) for driving a motor having at least one phase of a coil; a drive circuit (2) having an inverter circuit (2a) including high-side switches (Q1, Q3, Q5) and low-side switches (Q2, Q4, Q6) connected in series with each other and arranged corresponding to the coils of each phase of the motor (3), wherein the high-side switches and the low-side switches are alternately turned on / off according to the drive control signal to switch the energization direction of the coil of the corresponding phase, This causes the rotor of the motor to rotate; and a phase voltage detection circuit for detecting the phase voltage generated between the inverter circuit and the coils of each phase of the motor. In the control circuit, when an idling control signal (Id) is generated instead of the drive control signal and the switching state of the inverter circuit is switched to cause the rotor of the motor to idle, after an induced current circulates between the coil of the motor and the inverter circuit, the motor is judged to be idling based on the phase voltage generated in the phase voltage detection circuit according to the induced kick generated in the inverter circuit when the path of the induced current is cut off.

[0015] [2] It may also be that in the motor drive control device described in [1] above, the control circuit has: a first switching unit (21a), switching from a first switching state in which all the high-side switches and the low-side switches included in the inverter circuit are disconnected to a second switching state in which all the high-side switches or the low-side switches included in the inverter circuit are connected; a second switching unit (21b), switching from the second switching state to the first switching state; and an idling determination unit (22), when switching from the second switching state to the first switching state, determining that the motor is idling based on the phase voltage generated in the phase voltage detection circuit.

[0016] [3] It may also be that in the motor drive control device described in [2] above, the control circuit has a differential voltage detection circuit, and the differential voltage detection circuit detects the difference voltage between the phase voltage of a selected phase in the phase voltage detection circuit and the neutral point voltage obtained by synthesizing the phase voltages of all phases in the phase voltage detection circuit as a differential voltage detection signal, and the idling determination unit determines whether the motor is idling based on the differential voltage detection signal.

[0017] [4] In the motor drive control device described in [3] above, the idling determination unit may use the differential voltage detection signal detected by the differential voltage detection circuit in the second switch state as a reference voltage.

[0018] [5] It may also be that in the motor drive control device described in [4] above, when switching from the second switch state to the first switch state, the differential voltage detection signal detected multiple times in the differential voltage detection circuit is used as the measurement voltage, and the maximum variable voltage difference between the reference voltage and the measurement voltage is calculated. When the calculated maximum variable voltage difference is greater than a threshold value, it is determined that the motor is in an idling state.

[0019] [6] A motor idling detection method according to a representative embodiment of the present invention is characterized in that the motor idling detection method is executed in a motor drive control device, wherein the motor drive device comprises: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit having an inverter circuit including a high-side switch and a low-side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, wherein the high-side switch and the low-side switch are alternately turned on / off according to the drive control signal to switch the energization direction of the coil of the corresponding phase, thereby causing the rotor of the motor to rotate. rotation; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coils of each phase of the motor, the motor idling detection method comprising: a first step of switching from a first switching state in which all the high-side switches and the low-side switches included in the inverter circuit are disconnected to a second switching state in which all the high-side switches or the low-side switches included in the inverter circuit are connected; a second step of switching from the second switching state to the first switching state; and a third step of determining, when switching to the first switching state, whether the motor is idling based on the phase voltage.

[0020] 2. Specific examples of implementation methods Hereinafter, specific examples of the embodiments of the present invention will be described with reference to the drawings. It should be noted that in the following description, the same reference numerals are given to the common components in each embodiment, and repeated descriptions are omitted.

[0021] <<Implementation Method>> Figure 1 1 is a diagram showing a configuration of a motor unit 100 including a motor drive control device 10 according to an embodiment.

[0022] like Figure 1 As shown, the motor unit 100 includes a motor 3 and a motor drive control device 10 for controlling the rotation of the motor 3. The motor unit 100 can be applied to various devices that use a motor as a driving source, such as a fan and a remote-controlled drone.

[0023] The motor 3 is, for example, a permanent magnet synchronous motor (PMSM). In the present embodiment, the motor 3 is, for example, a surface magnet synchronous motor (SPMSM) having three-phase coils (windings) Lu, Lv, and Lw. The coils Lu, Lv, and Lw are, for example, Y-connected to each other. In this case, the coils may be Δ-connected to each other.

[0024] The motor drive control device 10 supplies a 120-degree energization rectangular wave drive signal to the motor 3 , for example, to cause a 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 .

[0025] The motor drive control device 10 includes a control circuit 1 , a drive circuit 2 , and a current detection circuit 2 c .

[0026] It should be noted that Figure 1 The components of the motor drive control device 10 shown in FIG. 1 are part of the whole. Figure 1 In addition to the components shown in the figure, other components may be included.

[0027] The drive circuit 2 drives the motor 3 based on a drive control signal Sd output from the control circuit 1 described later. The drive circuit 2 includes, for example, an inverter circuit 2a and a pre-drive circuit 2b. A current detection circuit 2c is provided between the inverter circuit 2a of the drive circuit 2 and the ground.

[0028] The inverter circuit 2a is a circuit that is disposed between a DC power supply Vin and a ground potential, and drives the coils Lu, Lv, and Lw of the motor 3 as a load based on an input drive control signal Sd. Specifically, in the embodiment, the inverter circuit 2a has three switch branches including two drive transistors connected in series, and the two drive transistors are alternately turned on / off (switching action) based on the input drive control signal Sd, thereby driving the motor 3 as a load.

[0029] More specifically, the inverter circuit 2a has switch branches corresponding to the U phase, V phase, and W phase of the motor 3, respectively. Figure 1 As shown, each corresponding switch branch has two driving transistors (hereinafter also referred to as "switching elements") Q1 and Q2, Q3 and Q4, Q5 and Q6 connected in series between the DC power supply Vin and the ground potential via the current detection circuit 2c.

[0030] Here, the driving transistors Q1, Q3, Q5 (equivalent 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, Q6 (equivalent to low-side switches) of the lower arm of the coil of the motor 3 are, for example, N-channel MOSFETs. It should be noted that the driving transistors Q1 to Q6 may be other types of FETs, such as IGBTs (Insulated Gate Bipolar Transistors).

[0031] For example, the switch branch corresponding to U has switch elements Q1 and Q2 connected in series with each other. The point at which switch element Q1 and switch element Q2 are connected in common is connected to one end of coil Lu as a load. The switch branch corresponding to V has switch elements Q3 and Q4 connected in series with each other. The point at which switch element Q3 and switch element Q4 are connected in common is connected to one end of coil Lv as a load. The switch branch corresponding to W has switch elements Q5 and Q6 connected in series with each other. The point at which switch element Q5 and switch element Q6 are connected in common is connected to one end of coil Lw as a load. In addition, switch elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 respectively have parasitic diode characteristics ( Figure 1 (not shown in the figure).

[0032] The pre-driving circuit 2 b generates a driving signal for driving the inverter circuit 2 a based on the driving control signal Sd output from the control circuit 1 .

[0033] The drive control signal Sd is a signal for controlling the drive of the motor 3, for example, a PWM (Pulse Width Modulation) signal. Specifically, the drive control signal Sd is a signal for switching the energization mode of the coils Lu, Lv, and Lw of the motor 3 determined by the on / off state of each switching element constituting the inverter circuit 2a. More specifically, the drive control signal Sd includes six PWM signals corresponding to the switching elements Q1 to Q6 of the inverter circuit 2a.

[0034] The pre-drive circuit 2b generates six drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl that can supply sufficient power to the control electrodes (gate electrodes) of each switching element Q1 to Q6 of the drive inverter circuit 2a based on the six PWM signals that are the drive control signals Sd provided from the control circuit 1.

[0035] By inputting these drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, the switching elements Q1 to Q6 are turned on / off (switching action). For example, the switching elements Q1, Q3, and Q5 of the upper arm and the switching elements Q2, Q4, and Q6 of the lower arm of each corresponding switch branch are alternately turned on / off. Thus, power is supplied from the DC power supply Vin to each phase of the motor 3, causing the motor 3 to rotate.

[0036] The current detection circuit 2c is connected to the DC line of the inverter circuit 2a to detect the current flowing in the DC line. Specifically, the current detection circuit 2c includes a resistor (hereinafter also referred to as a "shunt resistor") Rs as a current detection element. The shunt resistor Rs is connected in series with the inverter circuit 2a, for example, between the DC power supply Vin and the ground potential. That is, the shunt resistor Rs of the current detection circuit 2c is, for example, Figure 1 As shown, it is connected to the negative side (ground side) of the inverter circuit 2a. In the driving of the motor, the inverter circuit 2a is controlled, and the winding currents Iu, Iv, and Iw of each phase flowing in the three-phase coils Lu, Lv, and Lw of the motor 3 flow through the shunt resistor Rs of the current detection circuit 2c. The current detection circuit 2c detects the voltage drop of the current flowing in the shunt resistor Rs based on the differential voltage across the two ends of the shunt resistor Rs, and as a detection result, outputs a shunt current detection signal Vs corresponding to the current flowing in the shunt resistor Rs to the control circuit 1. As described later, the shunt resistor Rs can function as an overcurrent detection circuit.

[0037] Wiring (hereinafter also referred to as "phase voltage detection circuit") for measuring the phase voltages Vu, Vv, Vw generated in each phase is connected between the inverter circuit 2a and the coils Lu, Lv, Lw of each phase of the motor 3, and inputted to the control circuit 1. In the control circuit 1, the differential voltage (difference voltage between the neutral point voltage and the phase voltage of one selected phase: value corresponding to the phase voltage of the selected phase) measured based on the phase voltages Vu, Vv, Vw generated in each phase is used in the drive control of the motor and the idling detection of the motor described later.

[0038] The control circuit 1 generates a drive control signal Sd for driving the motor 3 based on a speed command signal Sc input from the outside and indicating a target state of the action of the motor 3, and controls the driving of the motor 3. Specifically, the control circuit 1 generates the drive control signal Sd and provides it to the drive circuit 2 so that the motor 3 is in the action state specified by the speed command signal Sc.

[0039] In the motor idling detection, the control circuit 1 generates an idling control signal Id described later instead of the drive control signal Sd to detect the idling of the motor 3. Specifically, when the motor 3 is not driven according to the drive control signal Sd, the control circuit 1 generates the idling control signal Id and provides it to the drive circuit 2, so that each switching element Q1 to Q6 of the inverter circuit 2a becomes a switching state specified by the idling control signal Id.

[0040] Here, the switching states of the switching elements Q1 to Q6 of the inverter circuit 2a corresponding to the three modes (free mode, charging mode, and discharging mode) for detecting the idling of the motor 3, which are switched by the idling control signal Id generated by the control circuit 1, are described.

[0041] Figures 2 to 4 It is a diagram for explaining the states of each switch switched by the idling control signal Id. Figures 2 to 4 , the state of the current flowing in the coil of the motor 3 and the inverter circuit 2a when the motor 3 is idling is shown by arrows. The inverter circuit 2a is connected to the DC power supply Vin, and is connected to the ground via the shunt resistor Rs as a part of the current detection circuit 2c. In addition, wiring (phase voltage detection circuit) for measuring the phase voltages Vu, Vv, and Vw by the control circuit 1 is connected between each phase of the coil of the motor 3 and the inverter circuit 2a.

[0042] The idling control signal Id is in free mode ( Figure 2 )、Charging Mode( Figure 3 )、Discharge Mode( Figure 4 Specifically, the idling control signal Id changes the switching state of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a from Figure 2 The first switch state shown in (corresponding to the free mode) is set to Figure 3 The second switching state shown in FIG. 1 (corresponding to the charging mode) is Figure 4 As shown, the switch is switched to the first switch state (corresponding to the discharge mode) again, so that the idling of the motor 3 can be detected.

[0043] (Free Mode) After the power is turned on, when the idling control signal Id is output from the control circuit 1 at a predetermined timing, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched to the first switching state by the idling control signal Id output from the control circuit 1. Specifically, Figure 2 As shown, in the inverter circuit 2a, all the switch states of the switching elements Q1 to Q6 are switched to off.

[0044] like Figure 2 As shown in FIG. 1 , in the first switching state, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, and a voltage is generated in the phase voltage detection circuit. However, due to the disconnection of each switching element Q1 to Q6 and the clamping of the parasitic diode, an induced current that circulates between the coil of the motor 3 and the inverter circuit 2a is not generated. At this time, an induced voltage corresponding to the idling speed is generated in the phase voltage detection circuit.

[0045] (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 switching state to the second switching state by the idling control signal Id output from the control circuit 1. The second switching state is a switching state in which, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of each phase, and the generated induced current circulates in a closed circuit formed by the coil and the switched elements Q1 to Q6 that are turned on. Specifically, in the inverter circuit 2a, the first switching state in which all the switching states of the switching elements Q1 to Q6 are turned off is switched to, for example, the second switching state in which all the switching states of the switching elements Q1 to Q6 are turned off. Figure 3 As shown, only the switching state of the switching elements Q2 , Q4 , and Q6 of the lower arms of the switching elements Q1 to Q6 is set to the second switching state of being turned on.

[0046] like Figure 3 As shown, in the inverter circuit 2a, when the switching state of the switching elements Q2, Q4, and Q6 of the lower arm of each switching element Q1 to Q6 is set to the second switching state of being turned on, when the rotor of the motor 3 is idling, an induced current that circulates between the coil of the motor 3 and the inverter circuit 2a is generated in the coil of each phase, and the generated induced current circulates in the closed circuit formed by the coil and the switching elements Q2, Q4, and Q6 of the lower arm that have been turned on. However, at this time, no induced voltage is generated in the phase voltage detection circuit.

[0047] Specifically, when the motor is idling, the rotor rotates relative to the coil, and in the coils of each phase, an induced voltage (eu, ev, ew) proportional to the rotation speed is generated with polarity in the direction that hinders the change of magnetic flux at the electrical angle period of the motor rotation with each phase shifted by 120 degrees. At this time, the current waveform becomes a phase that is delayed by 90 degrees relative to the voltage waveform.

[0048] (Discharge Mode) Next, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched back from the second switching state to the first switching state by the idling control signal Id outputted from the control circuit 1. Specifically, for example, in the inverter circuit 2a, the switching states of the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 are switched back from the second switching state to the first switching state. Figure 4 As shown, all the switch states of the switch elements Q1 to Q6 are set to the first switch state of being off.

[0049] like Figure 4 As shown, when the rotor of the motor 3 is idling, in the inverter circuit 2a, when the second switching state is changed to the first switching state, the path of the circulating induced current is cut off. At this time, in the coil of the winding of the motor 3, the induced current ( Figure 4A) continues to flow in the coil, thus generating an inductive kickback in the inverter circuit 2a ( Figure 4 B). Specifically, a voltage rise occurs at the connection point between the upper arm and the lower arm of the branch of the phase on the downstream side of the induced current, and a voltage drop occurs at the connection point between the upper arm and the lower arm of the branch of the phase on the upstream side of the induced current. This voltage change is clamped by the parasitic diodes of each switching element Q1 to Q6. Therefore, when the number of phases of the motor is three-phase, the voltage of each phase is increased to Vin+Vf at the most downstream side of the induced current, and the voltage of the phase on the most upstream side of the induced current is decreased to -Vf from the DC power supply Vin and the forward voltage Vf of the parasitic diode according to the position of the rotor. The voltage of the remaining phases increases to Vin+Vf or decreases to -Vf according to the direction of the induced current. In addition, this voltage change is in a short time. When the number of phases of the motor is three-phase, the voltage change time of the phase on the most downstream side of the induced current and the phase on the most upstream side is the longest according to the position of the rotor. At this time, a voltage change based on the inductive kick is also generated in the phase voltage detection circuit. This voltage fluctuation also occurs in the case where the coil is one-phase and switching elements are provided above and below both ends of the coil.

[0050] In the motor drive control device 10 of the present embodiment, when the voltage generated in the phase voltage detection circuit is detected and it is determined that a voltage fluctuation due to an inductive kick has occurred, it can be determined that the motor 3 is in an idling state.

[0051] It should be noted that, in the above example, as the second switch state corresponding to the charging mode, Figure 3 As shown, the case where all the switch states of the switch elements Q2, Q4, and Q6 of the lower arm of each switch element Q1 to Q6 of the inverter circuit 2a are set to be turned on is described as an example, but the present invention is not limited to this. All the switch states of the switch elements Q1, Q3, and Q5 of the upper arm of each switch element Q1 to Q6 of the inverter circuit 2a may also be set to be turned on.

[0052] The idling control signal Id is a signal for switching each switching element constituting the inverter circuit 2a to a switch state corresponding to three modes for detecting idling of the motor 3. Unlike the drive control signal Sd for driving the motor, the idling control signal Id is not a signal for generating a drive voltage in the coil of the motor 3, and therefore is not a signal for alternately switching the on / off of each switching element, for example, a high or low signal having a predetermined length. The idling control signal Id includes six signals corresponding to the switching elements Q1 to Q6 of the inverter circuit 2a.

[0053] The pre-driving circuit 2 b generates a driving signal as a switching signal for switching the switching state of each switching element constituting the inverter circuit 2 a based on the idling control signal Id output from the control circuit 1 .

[0054] The pre-driving circuit 2b generates a signal capable of supplying sufficient power to switch the switching state of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a based on six signals as the idling control signal Id supplied from the control circuit 1. As these switching signals, the driving signal is input to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, thereby switching the switching state of the switching elements Q1 to Q6. The details of the idling control signal Id will be described later.

[0055] In an embodiment, the control circuit 1 is, for example, a program processing device (e.g., a microcontroller) having the following structure: a processor such as a CPU (central processing unit), various storage devices such as a RAM (Random Access Memory), a ROM (Read-Only Memory), and peripheral circuits such as a counter (timer), an A / D (Analog To Digital) conversion circuit, a D / A (Digital To Analog) conversion circuit, a clock generation circuit, and an input / output I / F (Interface) circuit are interconnected via a bus and dedicated lines.

[0056] It should be noted that the motor drive control device 10 may be a structure in which at least a portion of the control circuit 1 and at least a portion of the drive circuit 2 are packaged into an integrated circuit device (IC), or a structure in which the control circuit 1 and the drive circuit 2 are respectively packaged into independent integrated circuit devices.

[0057] Figure 5 1 is a diagram showing a functional block configuration of a control circuit 1 in a motor drive control device 10 according to the embodiment.

[0058] like Figure 5 As shown, the control circuit 1 includes, for example, a drive command acquisition unit 11, a state control unit 12, a rectangular wave control unit 13, a PWM signal generation unit 14, a differential voltage detection circuit 15, a voltage determination unit 16, and a voltage measurement unit 17 as functional blocks for generating a drive control signal Sd in driving a motor based on a 120-degree energization rectangular wave drive method. In addition, the control circuit 1 includes, as functional blocks for generating an idling control signal Id in detecting idling of the motor, a state control unit 12, a differential voltage detection circuit 15, and a voltage measurement unit 17. The state control unit 12 includes a first switching unit 21a, a second switching unit 21b, and an idling determination unit 22.

[0059] These functional blocks are realized, for example, in a program processing device as the control circuit 1 by a processor executing various calculation processes according to a program stored in a memory and controlling peripheral circuits such as a counter and an A / D conversion circuit.

[0060] The drive command acquisition unit 11 receives a speed command signal Sc from the outside, analyzes the received speed command signal Sc, and thereby acquires a value that specifies a target operating state of the motor 3 specified by the speed command signal Sc.

[0061] The speed command signal Sc includes a value indicating a target state of the operation of the motor 3. The speed command signal Sc is a signal output from a host device for controlling the motor unit 100, which is provided outside the motor drive control device 10, for example.

[0062] In the embodiment, the speed command signal Sc specifies, for example, the rotation speed of the rotor of the motor 3. The speed command signal Sc includes a value ωref that is a target rotation speed (target rotation speed) of the rotor of the motor 3.

[0063] 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.

[0064] The state control unit 12 directly outputs the target speed ωref to the rectangular wave control unit 13 during the driving of the motor. The state control unit 12 can determine the starting method of the motor when the idle determination signal described later is generated from the idle determination unit 22. Figure 5 Although not particularly shown, the state control unit 12 may also have a functional unit that executes this processing.

[0065] The rectangular wave control unit 13 outputs the drive command signal So to the PWM signal generation unit 14, outputs the measurement phase selection signal Sm to the differential voltage detection circuit 15, and outputs the measurement type selection signal Ss and the measurement trigger signal Tr to the voltage measurement unit 17 during the driving of the motor. The measurement phase selection signal Sm is a signal for selecting a phase to be detected in the differential voltage detection circuit 15 from among the phases of the motor coil. The measurement type selection signal Ss is a signal for selecting the type of measurement in the voltage measurement unit 17, for example, a signal for selecting which of the input shunt current detection signal Vs and the differential voltage detection signal Vd is to be detected in the voltage measurement unit 17 described later. The measurement trigger signal Tr is a signal for triggering the measurement in the voltage measurement unit 17, for example, a signal for turning on / off a switch of a sampling circuit 172 in the voltage measurement unit 17 described later.

[0066] In order to obtain the switching timing of the six energization directions under the driving control method based on the 120-degree rectangular wave during the driving of the motor, the rectangular wave control unit 13 outputs the measurement phase selection signal Sm corresponding to the non-energized phase (induced voltage phase) to the differential voltage detection circuit 15, receives the voltage judgment signal Vjudge indicating the timing of the zero crossing of the differential voltage between the induced voltage of the selected non-energized phase and the neutral point voltage determined by the voltage judgment unit 16, and adjusts the energization switching in the driving control.

[0067] The rectangular wave control unit 13 generates a drive command signal So according to the target rotation speed ωref and the voltage judgment signal Vjudge in the drive control method based on the 120-degree rectangular wave, and outputs it to the PWM signal generation unit 14, thereby controlling the drive of the motor. The voltage judgment signal Vjudge is a signal indicating the timing of the zero crossing determined by the voltage judgment unit 16. The rectangular wave control unit 13 energizes the windings from the U phase to the V phase, for example, by two-phase excitation, and measures the differential voltage between the induced voltage (phase voltage) generated in the non-energized phase W phase and the neutral point voltage in the differential voltage detection circuit 15, and performs energization switching according to the timing of the zero crossing of the comparison result of the output value of the D / A converter 161 as a comparison device determined by the voltage judgment unit 16 described later and the differential voltage detection signal Vd, thereby controlling the drive of the motor. At this time, the neutral point voltage can use Vin (DC power supply) / 2 instead of the voltage obtained by synthesizing the phase voltages of all phases.

[0068] In order to detect whether an overcurrent is generated in the inverter circuit during the driving of the motor, the rectangular wave control unit 13 outputs a measurement trigger signal Tr and a measurement type selection signal Ss to the voltage measuring unit 17, receives a voltage measurement value Vmeas corresponding to the shunt current detection signal Vs measured in the voltage measuring unit 17 at a predetermined timing, and detects an overcurrent based on the voltage measurement value Vmeas. When an overcurrent is detected, the drive command signal So may be adjusted so as to perform drive control of the motor corresponding to the overcurrent.

[0069] The PWM signal generating unit 14 generates a drive control signal Sd based on the drive command signal So received from the rectangular wave control unit 13 during the driving of the motor, and outputs the signal to the drive circuit 2 to perform PWM control on the drive circuit 2 .

[0070] The differential voltage detection circuit 15 is configured to output the phase voltage of the selected phase as a differential voltage detection signal Vd to the voltage determination unit 16 and the voltage measurement unit 17 .

[0071] Figure 6 2 is a diagram showing a configuration example of the differential voltage detection circuit 15. Here, the configuration example of the differential voltage detection circuit 15 will be described.

[0072] The differential voltage detection circuit 15 receives the phase voltages Vu, Vv, Vw of each phase and the measurement phase selection signal Sm, and outputs a differential voltage detection signal Vd. The differential voltage detection circuit 15 is composed of a plurality of resistor elements 151 for DC current limitation and voltage adjustment, a multiplexer (MUX) 152 for measurement phase selection, and a differential amplifier circuit 153. The differential voltage detection circuit 15 branches the input of the phase voltages Vu, Vv, Vw of each phase into two, synthesizes one of the branches and inputs it as a synthesized signal (neutral point voltage) Vn to the differential amplifier circuit 153, and inputs the other branch to the measurement phase selection multiplexer 152. The output from the measurement phase selection multiplexer 152 is also input to the differential amplifier circuit 153.

[0073] In the differential voltage detection circuit 15, the measurement phase selection multiplexer 152 selects any one of the three phase voltages Vu, Vv, and Vw as the selected phase voltage signal Vm and outputs it to the differential amplifier circuit 153 according to the measurement phase selection signal Sm input from the state control unit 12 or the rectangular wave control unit 13. A synthesized signal Vn of the three phase voltages Vu, Vv, and Vw corresponding to the neutral point voltage of the motor coil is input to the differential amplifier circuit 153. That is, a signal corresponding to the differential voltage detection signal Vd' is input to the differential amplifier circuit 153. The differential voltage detection signal Vd' generated from the selected phase voltage signal Vm and the neutral point voltage Vn has both positive and negative polarities in the motor drive and the motor idling detection, so the differential amplifier circuit 153 performs signal scaling (amplification / reduction) and shifting of the DC power supply Vdc / 2, and outputs the differential voltage detection signal Vd saturated in the voltage range of 0V to Vdc centered at Vdc / 2 and substantially similar to the differential voltage detection signal Vd'. That is, the differential voltage detection signal Vd becomes a signal corresponding to the phase voltage of the selected phase.

[0074] The voltage determination unit 16 is a comparison device that compares the voltage of a predetermined signal with that of an input signal, and is configured to determine the zero crossing of the differential voltage between the induced voltage and the neutral point voltage during the driving of the motor.

[0075] Figure 7 1 is a diagram showing a configuration example of the voltage determination unit 16. Here, the configuration example of the voltage determination unit 16 is described. Figure 7 As shown in FIG. 1 , the voltage determination unit 16 is configured to include a comparison device D / A converter 161 and a comparison device 162 .

[0076] The voltage determination unit 16 determines the zero crossing of the differential voltage between the induced voltage and the neutral point voltage based on the differential voltage detection signal Vd corresponding to the phase voltage of the selected phase during the driving of the motor. The differential voltage detection signal Vd is shifted by Vdc / 2 in the differential voltage detection circuit 15, so in the voltage determination unit 16, the comparison device D / A converter 161 inputs the prescribed zero crossing reference value using Vdc / 2 as an analog signal to the comparison device 162. The comparison device 162 compares the prescribed zero crossing reference signal input from the comparison device D / A converter 161 with the differential voltage detection signal Vd, switches the signal output as the comparison result at the timing when the value of the differential voltage detection signal Vd with respect to the zero crossing reference signal changes from the high voltage side to the low voltage side or from the low voltage side to the high voltage side, and outputs the signal indicating the timing of the zero crossing as the voltage determination signal Vjudge to the rectangular wave control unit 13.

[0077] The voltage measuring unit 17 is configured to output a voltage measurement value Vmeas corresponding to the differential voltage detection signal Vd or the shunt current detection signal Vs to the state control unit 12 and the rectangular wave control unit 13 by using an A / D converter that digitizes the voltage of the input signal selected by the multiplexer.

[0078] Figure 8 1 is a diagram showing a configuration example of the voltage measuring unit 17. Here, the configuration example of the voltage measuring unit 17 is described. Figure 8 As shown, the voltage measuring unit 17 includes a multiplexer 171 for selecting a measurement type, a sampling circuit 172 , a D / A converter 173 for A / D conversion, a comparator 174 , and an offset calculator 175 .

[0079] The voltage measuring unit 17 selects either the differential voltage detection signal Vd or the shunt current detection signal Vs according to the measurement type selection signal Ss, uses the measurement trigger signal Tr as a trigger, performs A / D conversion on the voltage in the selected detection signal, and performs ADC voltage measurement. Furthermore, the voltage measurement value Vmeas obtained by performing the ADC offset adjustment described later is output to the state control unit 12 and the rectangular wave control unit 13.

[0080] The voltage measuring unit 17 measures a voltage measurement value Vmeas corresponding to the shunt current detection signal Vs based on the measurement type selection signal Ss and the measurement trigger signal Tr input from the rectangular wave control unit 13 for overcurrent detection during motor driving, and outputs the voltage measurement value Vmeas to the rectangular wave control unit 13 .

[0081] After the power is turned on or at the timing of idling determination, the voltage measuring unit 17 measures the voltage measurement value Vmeas corresponding to the differential voltage detection signal Vd based on the measurement type selection signal Ss and the measurement trigger signal Tr input from the state control unit 12 for idling detection, and outputs it to the state control unit 12.

[0082] Here, the ADC offset adjustment in the voltage measuring unit 17 is described. When the differential voltage detection signal Vd is selected by the measurement type selection signal Ss, the differential voltage detection signal Vd generated from the selected phase voltage signal Vm and the neutral point voltage Vn in the differential voltage detection circuit 15 becomes a signal saturated within the voltage range of 0V to Vdc centered on Vdc / 2 through the differential amplifier circuit 153. Therefore, in the charging mode, as a state in which the phase voltage is not generated in advance, the value of the voltage measurement value Vmeas is ensured, and the zero point of the differential voltage detection signal Vd is clarified by performing the ADC offset adjustment.

[0083] The ADC offset adjustment in the voltage measuring unit 17 is also performed in the case where the shunt current detection signal Vs is selected by the measurement type selection signal Ss. The shunt current detection signal Vs may become a value other than zero due to a shift or bias when the shunt current is not generated. Therefore, in the state where the shunt current is not generated in advance, the value of the voltage measurement value Vmeas is ensured in the free mode and the charging mode, and the zero point of the shunt current detection signal Vs is clarified by performing the ADC offset adjustment.

[0084] For ADC offset adjustment, the state control unit 12 inputs the measurement trigger signal Tr to the voltage measuring unit 17 when the differential voltage detection signal Vd is originally zero. The voltage measuring unit 17 is triggered by the measurement trigger signal Tr, performs A / D conversion on the signal input to the sampling circuit 172, and performs ADC voltage measurement. The difference between the measured value and "0" is calculated as the ADC offset adjustment value. The ADC offset adjustment value is used by the offset calculator 175 of the voltage measuring unit 17 to perform ADC offset adjustment.

[0085] Here, the idling determination controlled by the state control unit 12 will be further described.

[0086] In the state control unit 12, when the motor idling is detected, the first switching unit 21a is switched to the first switch state, and the second switching unit 21b generates an idling control signal Id switched to the second switch state and outputs it to the drive circuit 2. The start of the generation of the idling control signal Id can be triggered by power-on or reception of the speed command signal Sc after the motor stops (a predetermined time has passed since the speed command signal Sc was interrupted).

[0087] In the state control unit 12, the first switching unit 21a generates an idling control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switching state. In the state control unit 12, the second switching unit 21b generates an idling control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the second switching state. The idling control signal Id generated by the first switching unit 21a and the second switching unit 21b of the state control unit 12 is output to the drive circuit 2.

[0088] In the state control unit 12, in order to achieve a switch state capable of idling detection, after the power is turned on, the switch is switched to a predetermined switch state, and in a state where no phase voltage is generated, after the ADC offset measurement of the differential voltage detection signal Vd is performed, until the speed command signal Sc is received in the drive command acquisition unit 11, the idling control signal Id corresponding to the free mode is generated by the first switching unit 21a, and the start of the motor drive is waited. In the state control unit 12, thereafter, the presence or absence of the idling state is detected by the input of the speed command signal Sc just before the driving motor is driven, and the idling control signal Id is generated by the second switching unit 21b during the charging time (a period corresponding to the charging mode). In the state control unit 12, thereafter, the idling control signal Id is generated again by the first switching unit 21a during the discharging time (a period corresponding to the discharging mode). It should be noted that after the discharging time when the idling determination is completed, the idling control signal Id corresponding to the free mode can be generated again by the first switching unit 21a. Furthermore, in order to re-detect whether the motor is in an idling state, the charging mode and the discharging mode may be executed again.

[0089] The timing for entering the charging mode from the free mode may be, for example, after the driving instruction acquisition unit 11 receives the speed instruction signal Sc.

[0090] In the idling detection of the motor, the state control unit 12 outputs the measurement type selection signal Ss for selecting the differential voltage detection signal Vd by the measurement type selection multiplexer 171 and the measurement trigger signal Tr for idling detection for turning on the switch of the sampling circuit 172 to the voltage measuring unit 17 at the timing immediately before entering the discharge mode from the charging mode, that is, in the state where the phase voltage is not generated immediately before switching from the second switch state to the first switch state, thereby instructing the measurement of the input differential voltage detection signal Vd. Based on the instruction from the state control unit 12, the voltage measuring unit 17 performs A / D conversion on the input differential voltage detection signal Vd, and further performs ADC offset adjustment to generate a voltage measurement value Vmeas. The voltage measuring unit 17 outputs the generated voltage measurement value Vmeas to the idling determination unit 22 of the state control unit 12. The voltage measurement value Vmeas is used as a reference voltage. After the measurement of the differential voltage detection signal Vd, the discharge mode is entered.

[0091] In the motor idling detection, the state control unit 12 switches from the second switch state to the first switch state in the discharge mode, and after a short mask time to avoid the influence of the switching of the switching element, outputs the measurement type selection signal Ss for selecting the differential voltage detection signal Vd by the measurement type selection multiplexer 171 and the measurement trigger signal Tr for idling detection for turning on the switch of the sampling circuit 172 to the voltage measuring unit 17 at a predetermined timing, thereby instructing the measurement of the input differential voltage detection signal Vd. Based on the instruction from the state control unit 12, the voltage measuring unit 17 performs A / D conversion on the input differential voltage detection signal Vd, and further performs ADC offset adjustment to generate a voltage measurement value Vmeas. The voltage measuring unit 17 outputs the generated voltage measurement value Vmeas to the idling determination unit 22 of the state control unit 12. The voltage measurement value Vmeas is used as the measurement voltage. The measurement of the differential voltage detection signal Vd is performed multiple times during the discharge mode.

[0092] The idling determination unit 22 determines whether the motor 3 is idling based on the voltage measurement value Vmeas generated by the voltage measuring unit 17, and generates an idling determination signal indicating the idling determination result. Specifically, the idling determination unit 22 uses the voltage measurement value Vmeas obtained by instructing the voltage measuring unit 17 to measure at multiple timings as the measurement voltage, calculates the maximum variable voltage difference with the maximum difference between the reference voltage and the measurement voltage, compares the calculated maximum variable voltage difference with a preset threshold value (idling threshold value), and determines that the motor 3 is in an idling state when the maximum variable voltage difference is greater than the idling threshold value.

[0093] The idling threshold value may utilize a value of a maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage of the differential voltage detection signal Vd is the largest in the minimum rotation speed (minimum idling rotation speed) for idling detection.

[0094] As for the charging time, the voltage variation time generated in the phase voltage detection circuit due to the inductive kickback varies according to the rotation speed and the rotor position, so the pre-determined time can be used to determine the minimum voltage variation time at the minimum rotation speed (minimum idling speed) for idling detection. When the charging time is shortened, the idling detection period becomes shorter, and the abnormal noise of the drive system caused by the braking state due to the short charging time is small, which is ideal.

[0095] As for the discharge time, the voltage variation generated in the phase voltage detection circuit due to the inductive kick decays and converges to a predetermined value as time passes. Therefore, in the minimum rotation speed (minimum idling rotation speed) for performing idling detection, the pre-determined time can be used so that the differential voltage detection signal Vd can be measured multiple times. In addition, when the maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage of the differential voltage detection signal Vd measured multiple times is the largest is measured, the measurement can be ended without waiting for the discharge time to pass.

[0096] Next, the mode transition after the power of the state control unit 12 is turned on will be described in detail.

[0097] Fig. 9 1 is a diagram showing a timing chart showing an example of a signal waveform from when the speed command signal Sc is input after the power supply to the motor unit 100 is turned on until the determination of idling is completed.

[0098] exist Fig. 9 In the figure, from the top are shown in sequence: the speed command signal Sc, the drive signals of the gates of the input switching elements Q1 to Q6, the waveforms of the measurement trigger signal Tr for idling detection, the selected phase voltage signal Vm which is a phase voltage selected from the three phase voltages Vu, Vv, Vw, the neutral point voltage Vn generated by the three phase voltages Vu, Vv, Vw, and the waveforms of the differential voltage detection signal Vd output from the differential voltage detection circuit 15.

[0099] The speed command signal Sc is a signal received as a target speed ωref in the state control unit 12. The state control unit 12 uses power-on or reception of the speed command signal Sc as a trigger to generate an idling control signal Id including each drive signal of the gate of the input switching elements Q1 to Q6 at a specified timing, and generates a measurement trigger signal Tr for idling detection of the input voltage measuring unit 17.

[0100] When the state control unit 12 generates the measurement phase selection signal Sm, the selected phase voltage signal Vm and the neutral point voltage Vn are input to the differential amplifier circuit 153 , and as a result, the differential voltage detection circuit 15 outputs a differential voltage detection signal Vd.

[0101] like Fig. 9 As shown in FIG. 1 , the motor drive control device 10 goes through the free mode, the charging mode, the discharging mode, and then returns to the free mode. At this time, the motor drive control device 10 starts from the free mode (free mode (1)) after the power is turned on. It should be noted that in Fig. 9 In the timing chart shown in , the case where the discharge mode is followed by the free mode (free mode (2)) is listed, but the present invention is not limited to this.

[0102] In the free mode, the inverter circuit 2a is set to the first switching state by the idling control signal Id. Specifically, the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a are all set to low by the idling control signal Id generated by the first switching unit 21a, and all switches of the inverter circuit are turned off. In this state, a closed circuit is not formed, so the winding current of the selected phase is 0A, and no current flows.

[0103] In this state, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of the motor 3, and the phase voltage Vu of the U phase as the selected phase voltage signal Vm is freed from the influence caused by the clamping of the parasitic diode by the disconnection of all the switching elements Q1 to Q6, and vibrates with a positive side saddle wave based on the amplitude of the induced voltage corresponding to the idling speed and the period corresponding to the idling speed. The positive side saddle wave means a waveform with a concave portion at the vertex on the positive side of the arc similar to the full-wave rectified wave. The neutral point voltage Vn obtained by synthesizing the phase voltages of all phases vibrates with a positive side full-wave rectified wave based on the amplitude of the induced voltage corresponding to the idling speed and the period of three times the phase voltage by the disconnection of all the switching elements Q1 to Q6. The positive side full-wave rectified wave means a full-wave rectified wave with a vertex on the positive side on the arc. The differential voltage detection signal Vd' of the selected phase voltage signal Vm and the neutral point voltage Vn input to the differential amplifier circuit 153 oscillates with a sine wave having an amplitude of an induced voltage corresponding to the idling speed and a period corresponding to the idling speed by turning off all the switch elements Q1 to Q6. At this time, the differential voltage detection signal Vd passes through the differential amplifier circuit 153 and becomes a signal saturated in a voltage range of 0V to Vdc, which is substantially similar to the differential voltage detection signal Vd' and is centered at Vdc / 2.

[0104] Next, in the charging mode, the inverter circuit 2a is set to the second switching state by the idling control signal Id. Specifically, 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 are all set to high by the idling control signal Id generated by the second switching unit 21b, turning on all the low-side switches of the inverter circuit.

[0105] In this state, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coil of the motor 3, as shown in FIG. Figure 3 As shown, a closed circuit is formed by the coil of the motor 3 and the switching elements Q2, Q4, and Q6 connected by the inverter circuit 2a, and a current circulates between the coil of the motor 3 and the inverter circuit 2a. The winding current of the selected phase vibrates with a sinusoidal wave based on the amplitude of the induced current corresponding to the idling speed and the period corresponding to the idling speed.

[0106] In the charging mode, the phase voltage of the U phase as the selected phase voltage signal Vm converges to 0 V by turning on all the switch elements Q2, Q4, and Q6 on the LO side. The neutral point voltage Vn also converges to 0 V by turning on all the switch elements Q2, Q4, and Q6 on the LO side. The differential voltage detection signal Vd' also converges to 0 V by turning on all the switch elements Q2, Q4, and Q6 on the LO side. At this time, the differential voltage detection signal Vd is converted to Vdc / 2 by the differential amplifier circuit 153.

[0107] Next, in the discharge mode, the inverter circuit 2a is set to the first switch state again by the idle control signal Id. Specifically, the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a are all set to low again by the idle control signal Id generated by the first switching unit 21a, and all switches of the inverter circuit are turned off.

[0108] In this state, when the rotor of the motor 3 is idling, the current that circulated between the coil of the motor 3 and the inverter circuit 2a during the charging mode continues to flow through the coil, so that an inductive kick is generated by turning off all the switching elements Q1 to Q6.

[0109] In the discharge mode, due to the inductive kickback, the phase voltage of the U phase, which is the selected phase voltage signal Vm, decreases in the case of the phase on the most upstream side of the inductive current, increases in the case of the phase on the most downstream side of the inductive current, and increases or decreases in the case of the remaining phases according to the direction of the inductive current. The inductive voltage is clamped by the parasitic diode, and the voltage change time of the phase on the most downstream side of the inductive current and the phase on the most upstream side is the longest. The voltage change due to the inductive kickback that is different for each phase is synthesized, so the neutral point voltage Vn changes in stages. Afterwards, the influence of the inductive kickback is eliminated, and the phase voltage of the U phase as the selected phase voltage signal Vm and the neutral point voltage Vn converge to Vin / 2. Through the discharge mode, the coil and the inverter circuit of the motor do not form a closed circuit. Therefore, the influence of the induced voltage caused by the idling of the motor appears from the junction point A of the selected phase voltage signal Vm and the junction point B of the neutral point voltage Vn. The selected phase voltage signal Vm, the neutral point voltage Vn and the differential voltage detection signal Vd' vibrate with the same waveform as the free mode (1).

[0110] In the discharge mode, when the phase voltage of the U phase, which is the selected phase voltage signal Vm, increases, the differential voltage detection signal Vd' changes to the positive side (plus side), eliminates the influence of the inductive kickback, and starts to vibrate based on the sine wave of the inductive voltage from the falling waveform converging to 0V. When the phase voltage of the U phase, which is the selected phase voltage signal Vm, decreases, the differential voltage detection signal Vd' changes to the negative side (minus side), eliminates the influence of the inductive kickback, and starts to vibrate based on the sine wave of the inductive voltage from the rising waveform converging to 0V. The differential voltage detection signal Vd' changes in stages due to the voltage fluctuations that differ according to each phase, and there are six types of waveform patterns (positive side two-stage up and down, positive side one-stage, positive side two-stage down and up, negative side two-stage up and down, negative side one-stage, negative side two-stage down and up). At this time, the differential voltage detection signal Vd passes through the differential amplifier circuit 153 and becomes a signal saturated in the voltage range of 0V to Vdc, which is roughly similar to the differential voltage detection signal Vd' and centered at Vdc / 2.

[0111] Here, a description will be given of a waveform pattern of the differential voltage detection signal Vd′ generated in the discharge mode when the rotor of the motor 3 is idling.

[0112] Figures 10 to 15 The waveforms are the patterns of the phase voltage generated in the phase voltage detection circuit by the inductive kickback in the discharge mode when the rotor of the motor 3 is idling and the patterns of the differential voltage generated as a result. These signals change in voltage according to the six patterns shown below through the position of the rotor of the motor 3. It should be noted that Figures 10 to 15 Only the phase voltage of the U phase as the selected phase voltage signal Vm, the neutral point voltage Vn, and the differential voltage detection signal Vd′ are shown, and the influence of the induced voltage caused by the idling of the motor is omitted for simplicity.

[0113] When the rotor of the motor 3 stops (not idling), in the discharge mode, no voltage fluctuation due to the inductive kickback occurs, so the phase voltage of each phase does not change from 0 V regardless of the position of the rotor of the motor 3. Therefore, the phase voltage of the U phase as the selected phase voltage signal Vm and the neutral point voltage Vn are both 0 V, and the differential voltage detection signal Vd' is also 0 V.

[0114] Fig.10 is a diagram showing a waveform pattern of the first pattern. In this pattern, the U phase is at the most downstream side of the induced current, the V phase is at the most upstream side of the induced current, and the W phase is at the downstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0115] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, rises to Vin+Vf from the DC power supply Vin and the forward voltage Vf of the parasitic diode, the phase voltage Vv of the V phase drops to -Vf, and the phase voltage Vw of the W phase rises to Vin+Vf. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin*2 / 3 (in this specification, "*" indicates multiplication). As a result, the differential voltage detection signal Vd' converges to approximately Vin / 3.

[0116] In the second half, the voltage fluctuations of the U-phase phase voltage Vu and the V-phase phase voltage Vv are maintained, but the W-phase phase voltage Vw, which has a short voltage fluctuation time, drops to approximately Vin / 2. In addition, the neutral point voltage Vn, which is a composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately Vin / 2. Thereafter, the influence of the inductive kickback is eliminated, and the differential voltage detection signal Vd' converges to approximately 0V.

[0117] Thus, in the first pattern, the differential voltage detection signal Vd′ has a waveform pattern with two positive-side up-down steps, that is, it takes two positive values, and the values ​​have a waveform changing from a positive low voltage to a positive high voltage.

[0118] Fig.11 is a diagram showing a waveform pattern of the second pattern. In this pattern, the U phase is at the downstream side of the induced current, the V phase is at the most upstream side of the induced current, and the W phase is at the most downstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0119] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, rises to Vin+Vf, the phase voltage Vv of the V phase drops to -Vf, and the phase voltage Vw of the W phase rises to Vin+Vf. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin*2 / 3. As a result, the differential voltage detection signal Vd' converges to approximately Vin / 3.

[0120] In the second half, the voltage fluctuations of the phase voltage Vv of the V phase and the phase voltage Vw of the W phase are maintained, but the phase voltage Vu of the U phase with a short voltage fluctuation time is reduced to approximately Vin / 2. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately 0V.

[0121] Thus, in the second pattern, the differential voltage detection signal Vd′ has a waveform pattern of one level on the positive side, that is, a waveform taking a positive value.

[0122] Fig.12 is a diagram showing a waveform pattern of the third pattern. In this pattern, the U phase is at the most downstream side of the induced current, the V phase is at the most upstream side of the induced current, and the W phase is at the upstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0123] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, rises to Vin+Vf, the phase voltage Vv of the V phase drops to -Vf, and the phase voltage Vw of the W phase drops to -Vf. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin / 3. As a result, the differential voltage detection signal Vd' converges to approximately Vin*2 / 3.

[0124] In the second half, the voltage fluctuations of the U-phase phase voltage Vu and the V-phase phase voltage Vv are maintained, but the W-phase phase voltage Vw, which has a short voltage fluctuation time, rises to approximately Vin / 2. In addition, the neutral point voltage Vn, which is a composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately Vin / 2. Thereafter, the influence of the inductive kickback is eliminated, and the differential voltage detection signal Vd' converges to approximately 0V.

[0125] Thus, in the third pattern, the differential voltage detection signal Vd′ has a waveform pattern with two positive levels, that is, it takes two positive values, and the values ​​have a waveform that changes from a positive high voltage to a positive low voltage.

[0126] Fig.13 is a diagram showing a waveform pattern of the fourth pattern. In this pattern, the U phase is at the most upstream side of the induced current, the V phase is at the upstream side of the induced current, and the W phase is at the most downstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0127] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, drops to -Vf, the phase voltage Vv of the V phase drops to -Vf, and the phase voltage Vw of the W phase rises to Vin+Vf. In addition, the neutral point voltage Vn, which is the combined voltage of these voltages, converges to approximately Vin / 3. As a result, the differential voltage detection signal Vd' converges to approximately -Vin / 3.

[0128] In the second half, the voltage fluctuations of the U-phase phase voltage Vu and the W-phase phase voltage Vw are maintained, and the V-phase phase voltage Vv with a short voltage fluctuation time rises to approximately Vin / 2. In addition, the neutral point voltage Vn, which is a composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately -Vin / 2. Thereafter, the influence of the inductive kickback is eliminated, and the differential voltage detection signal Vd' converges to approximately 0V.

[0129] Thus, in the fourth pattern, the differential voltage detection signal Vd′ has a waveform pattern with two negative-side up-down steps, that is, it takes two negative values, and the value has a waveform changing from a negative low voltage to a negative high voltage.

[0130] Fig.14 is a diagram showing a waveform pattern of the fifth pattern. In this pattern, the U phase is at the upstream side of the induced current, the V phase is at the most upstream side of the induced current, and the W phase is at the most downstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0131] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, drops to -Vf, the phase voltage Vv of the V phase drops to -Vf, and the phase voltage Vw of the W phase rises to Vin+Vf. In addition, the neutral point voltage Vn, which is the combined voltage of these voltages, converges to approximately Vin / 3. As a result, the differential voltage detection signal Vd' converges to approximately -Vin / 3.

[0132] In the second half, the voltage fluctuations of the phase voltage Vv of the V phase and the phase voltage Vw of the W phase are maintained, but the phase voltage Vu of the U phase with a short voltage fluctuation time rises to approximately Vin / 2. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately 0V.

[0133] Thus, in the fifth pattern, the differential voltage detection signal Vd′ has a waveform pattern of a negative-side level, that is, a waveform taking a negative value.

[0134] Fig.15 is a diagram showing a waveform pattern of the sixth pattern. In this pattern, the U phase is at the most upstream side of the induced current, the V phase is at the downstream side of the induced current, and the W phase is at the most downstream side of the induced current. At this time, the V phase and the W phase can be switched.

[0135] In this pattern, in the first half, the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, drops to -Vf, the phase voltage Vv of the V phase rises to Vin+Vf, and the phase voltage Vw of the W phase rises to Vin+Vf. In addition, the neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin*2 / 3. As a result, the differential voltage detection signal Vd' converges to approximately -Vin*2 / 3.

[0136] In the second half, the voltage fluctuations of the U-phase phase voltage Vu and the W-phase phase voltage Vw are maintained, but the V-phase phase voltage Vv, which has a short voltage fluctuation time, drops to approximately Vin / 2. In addition, the neutral point voltage Vn, which is a composite voltage of these voltages, converges to approximately Vin / 2. As a result, the differential voltage detection signal Vd' converges to approximately Vin / 2. Thereafter, the influence of the inductive kickback is eliminated, and the differential voltage detection signal Vd' converges to approximately 0V.

[0137] Thus, in the sixth pattern, the differential voltage detection signal Vd′ has a two-level upper and lower waveform pattern on the negative side, that is, it takes two negative values, and the value has a waveform that changes from a negative high voltage to a negative low voltage.

[0138] according to Figures 10 to 15By using the phase voltage and neutral point voltage of at least one phase, it is possible to detect whether the motor is in an idling state based on the voltage fluctuation. At this time, the phase voltage is sometimes near 0V, but by using the phase voltage and the neutral point voltage at the same time, it is possible to confirm the voltage fluctuation of ±Vin / 3 or more, and detect the presence of a more stable motor idling state. For the phase voltage and the neutral point voltage, by directly measuring the voltage without using a differential voltage detection circuit, an idling judgment based on a threshold value can be made, but for the phase voltage and the neutral point voltage, a differential voltage is generated by a differential amplifier circuit, and the differential voltage is shifted, so that the voltage fluctuation can be processed as a positive voltage, making it easier to make an idling judgment based on a threshold value.

[0139] return Fig. 9 , after the discharge mode, it can become the free mode again. In the free mode after the discharge mode, the inverter circuit 2a is set to the first switching state by the idling control signal Id. Specifically, the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a are all set to low by the idling control signal Id generated by the first switching unit 21a, and all switches of the inverter circuit are turned off. In this state, a closed circuit is not formed, so the winding current of the selected phase is 0A, and no current flows.

[0140] In the free mode again, the phase voltage of the U phase, which is the selected phase voltage signal Vm, converges the voltage variation due to the inductive kickback by turning off all the switching elements Q1 to Q6, and vibrates with a positive saddle wave with an amplitude based on the inductive voltage corresponding to the idling speed and the clamping of the parasitic diode and a period corresponding to the idling speed. The neutral point voltage Vn, by turning off all the switching elements Q1 to Q6, converges the voltage variation due to the inductive kickback, and vibrates with a positive full-wave rectified wave with an amplitude based on the inductive voltage corresponding to the idling speed and the clamping of the parasitic diode and a period three times the phase voltage. The differential voltage detection signal Vd' vibrates with a sine wave with an amplitude based on the inductive voltage corresponding to the idling speed and a period corresponding to the idling speed by turning off all the switching elements Q1 to Q6.

[0141] The idling determination unit 22 receives the voltage measurement value Vmeas corresponding to the differential voltage detection signal Vd described above from the voltage measurement unit 17. As described above, the differential voltage detection signal Vd can also undergo various changes in the discharge mode, so the idling determination unit 22 performs a plurality of measurements of the differential voltage detection signal Vd in the discharge mode, wherein the idling determination is performed based on the differential voltage detection signal Vd when the voltage variation is the largest compared to the voltage in the charge mode.

[0142] The idling determination unit 22 repeats the measurement of the differential voltage detection signal Vd a plurality of times at a predetermined interval after a predetermined masking time has passed during a predetermined discharge time. Since the voltage variation due to the inductive kickback caused by the idling of the motor changes in a stepwise manner, it is desirable to measure the differential voltage detection signal Vd more than once. For example, the differential voltage detection signal Vd measured in advance in the charging mode is used as a reference voltage, and the maximum fluctuation voltage difference between the reference voltage and the measured voltage among the plurality of measured voltages measured in the discharge mode is calculated, and the calculated maximum fluctuation voltage difference is compared with the preset idling threshold, thereby making it possible to make an idling determination. The idling determination unit 22 can determine that the motor 3 is idling when the maximum fluctuation voltage difference exceeds the predetermined idling threshold. The idling threshold can be any value as long as it is the maximum fluctuation voltage difference that can determine the maximum difference between the reference voltage and the measured voltage of the differential voltage detection signal Vd at the minimum idling speed for idling detection. The differential amplifier circuit 153 can adjust the amplification (reduction) rate of the differential voltage detection signal Vd' within the range that can determine the idling threshold.

[0143] Next, the flow of each process in idling detection implemented by the control circuit 1 of the motor drive control device 10 according to the embodiment will be described.

[0144] Fig.16 This is a flowchart showing an example of the flow of processing when the power is turned on in the control circuit 1 of the motor drive control device 10 according to the embodiment.

[0145] First, when the power is turned on in the motor drive control device 10, Fig.16 As shown, when it is decided to switch to the free mode (step S111) in the state control unit 12, the first switching unit 21a generates an idling control signal Id (step S112) for switching to the first switching state (all switching elements Q1 to Q6 are disconnected) in order to set the switching elements Q1 to Q6 constituting the inverter circuit 2a to the switching state corresponding to the free mode.

[0146] The state control unit 12 generates an idle control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switch state based on the idle control signal Id generated in step S112. Figure 2 The first switching state is shown in FIG.

[0147] Next, when it is decided in the state control unit 12 to switch to the charging mode (step S113), the ADC offset measurement of any selected phase for idling detection is performed, so that the second switching unit 21b generates an idling control signal Id (step S114) that switches the switching elements Q1 to Q6 constituting the inverter circuit 2a to the second switching state (all LO side switching elements Q2, Q4, Q6 are turned on).

[0148] The state control unit 12 generates an idle control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the second switch state based on the idle control signal Id generated in step S114. Figure 3 The second switching state shown in FIG. 1 does not generate a phase voltage.

[0149] After step S114, the control circuit 1 performs measurement selection (step S200). For example, when idling detection is performed using the U-phase phase voltage Vu, the phase voltage signal Vm is selected as the measurement type selection signal Ss, and the U-phase phase voltage Vu is selected as the measurement phase selection signal Sm.

[0150] Fig.17 This is a flowchart showing an example of the flow of measurement selection based on the measurement type selection signal Ss and the measurement phase selection signal Sm output from the state control unit 12 or the rectangular wave control unit 13 .

[0151] When starting to measure the selection, Fig.17 As shown, first, in the voltage measuring unit 17, it is determined whether the measurement type selection signal Ss selects the shunt current measurement (step S201). It should be noted that the measurement type selection signal Ss selects the shunt current detection signal Vs for overcurrent detection during motor driving.

[0152] When the measurement type selection signal Ss selects shunt current measurement (step S201: Yes), the measurement type selection multiplexer 171 of the voltage measuring unit 17 selects the shunt current detection signal Vs as an input to the sampling circuit 172 (step S202), and the measurement selection ends.

[0153] When the measurement type selection signal Ss does not select the shunt current measurement (step S201 : No), the differential voltage detection circuit 15 determines whether the measurement phase selection signal Sm selects the U phase (step S203 ).

[0154] When the measurement phase selection signal Sm selects the U phase (step S203 : Yes), the measurement phase selection multiplexer 152 of the differential voltage detection circuit 15 selects the phase voltage Vu of the U phase for the selection phase voltage signal Vm (step S204 ).

[0155] When the measurement phase selection signal Sm does not select the U phase (step S203 : No), the differential voltage detection circuit 15 determines whether the measurement phase selection signal Sm selects the V phase (step S205 ).

[0156] When the measurement phase selection signal Sm selects the V phase (step S205 : Yes), the measurement phase selection multiplexer 152 of the differential voltage detection circuit 15 selects the phase voltage Vv of the V phase for the selection phase voltage signal Vm (step S206 ).

[0157] When the measurement phase selection signal Sm does not select the V phase (step S205 : No), the measurement phase selection multiplexer 152 of the differential voltage detection circuit 15 selects the phase voltage Vw of the W phase for the selection phase voltage signal Vm (step S207 ).

[0158] After steps S204 , S206 , and S207 , the differential voltage detection signal Vd is selected as an input to the sampling circuit 172 by the measurement type selection multiplexer 171 of the voltage measuring unit 17 (step S208 ), and the measurement selection is terminated.

[0159] return Fig.16 After step S200, the control circuit 1 performs ADC offset measurement (step S300).

[0160] Fig.18 17 is a flowchart showing an example of the flow of ADC offset measurement implemented by the control circuit 1 of the motor drive control device 10. By executing the ADC offset measurement, an ADC offset adjustment value can be obtained. The obtained ADC offset adjustment value can be used in the offset calculator 175.

[0161] In the voltage measuring unit 17, when the ADC offset measurement is started, Fig.18 As shown, first, the counter of the number of ADC offset measurements is cleared, the ADC offset adjustment value is reset to zero, and the offset calculator 175 is disabled (step S301).

[0162] Next, in the voltage measuring unit 17, the conversion sampling circuit 172 performs A / D conversion on the differential voltage detection signal Vd output from the differential voltage detection circuit 15 or the shunt current detection signal Vs output from the current detection circuit 2c selected by the measurement type selection multiplexer 171 of the voltage measuring unit 17, and performs ADC voltage measurement (ADC voltage measurement: step S302). It should be noted that at this time, the differential voltage detection signal Vd or the shunt current detection signal Vs is in a state equivalent to zero, but it is also possible that the measured voltage value is a value other than zero due to shift or bias.

[0163] When the ADC voltage measurement in step S302 is completed, the voltage measuring unit 17 increments the counter of the number of ADC offset measurements by "+1" (step S303).

[0164] The voltage measuring unit 17 checks the counter of the ADC offset measurement count to determine whether the current ADC offset measurement count exceeds a predetermined ADC offset measurement count (step S304 ).

[0165] If the current ADC offset measurement count does not exceed the prescribed ADC offset measurement count (step S304: No), the process returns to step S302. On the other hand, if the current ADC offset measurement count exceeds the prescribed ADC offset measurement count (step S304: Yes), the average value of the values ​​obtained in the measurement of step S302 is obtained as the ADC offset adjustment value, and the offset calculator 175 is enabled (step S305).

[0166] By the measurement selection of step S200 and the ADC offset measurement of step S300, for example, when the phase voltage Vu of the U phase is used for idling detection, the offset adjustment of the differential voltage detection signal Vd is performed. Here, the offset adjustment of the differential voltage detection signal Vd when the phase voltage of the V phase or the W phase is used for idling detection, and the offset adjustment when the shunt current detection signal Vs is selected by the measurement type selection signal Ss can be performed. In addition, as the offset adjustment value of the phase voltage, the average value of the ADC offset adjustment value of each phase voltage can be used.

[0167] return Fig.16 In the state control unit 12, when it is decided to switch to the free mode again (step S115), by ending the ADC offset measurement, the first switching unit 21a generates an idling control signal Id (step S116) for switching to the first switching state (all switching elements Q1 to Q6 are disconnected) in order to set the switching elements Q1 to Q6 constituting the inverter circuit 2a to the switching state corresponding to the free mode again.

[0168] The state control unit 12 generates an idling control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switching state based on the idling control signal Id generated in step S116. Figure 2 The first switch state is shown.

[0169] After that, the state control unit 12 waits for the start of the motor drive after the power is turned on or from the motor stop, and thus determines whether the speed command signal Sc is received in the drive command acquisition unit 11 (step S120). The state control unit 12 repeats the determination until the speed command signal Sc is received in the drive command acquisition unit 11. When the motor is stopped, as when the power is turned on, before step S120, the free mode is entered (step S115), for example, when the U-phase phase voltage Vu is used for idling detection, the phase voltage signal Vm is selected for the measurement type selection signal Ss, and the U-phase phase voltage Vu is selected for the measurement phase selection signal Sm.

[0170] When the drive command acquisition unit 11 receives the speed command signal Sc from the host device (step S120 : Yes), the state control unit 12 performs idling detection (step S400 ) to detect the presence or absence of an idling state immediately before driving the motor.

[0171] Fig.19 1 is a flowchart showing an example of a flow of idling detection implemented by the control circuit 1 of the motor drive control device 10. Here, for example, a case where idling detection is performed using the phase voltage Vu of the U phase will be described as an example.

[0172] When the idling detection of S400 is started, the switch state is already the first switch state corresponding to the free mode. Therefore, in order to enter the charging mode, in the state control unit 12, the second switching unit 21b is switched to the first switch state. Fig.19 As shown, first, an idling control signal Id switched to a second switch state corresponding to the charging mode is generated (step S410).

[0173] When in charging mode, execute Fig.17 The phase to be measured is selected (step S411). In this example, the phase voltage Vu of the U phase is used for idling detection, so the state control unit 12 selects the differential voltage detection signal Vd through the measurement type selection signal Ss, and selects the phase voltage Vu of the U phase through the measurement phase selection signal Sm. Fig.16 In the embodiment, the measurement selection S200 is executed before the ADC offset measurement S300, but in order to reset the settings of the selected measurement phase selection multiplexer 152 and the measurement type selection multiplexer 171 during the driving of the motor, the measurement selection S200 can be executed again at this timing. Fig.17 Determination selection.

[0174] Then, after the phase to be measured is selected in step S411, the charging time is reset in the state control unit 12 (step S412).

[0175] The state control unit 12 generates an idling control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the second switching state based on the idling control signal Id generated in step S410. Based on the idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are switched to the second switching state, for example, Figure 3 The second switch state is shown.

[0176] In the state control unit 12, the second switching unit 21b determines whether a predetermined charging time has elapsed after the idle control signal Id was generated in step S410 (step S413).

[0177] In the state control unit 12, when the predetermined charging time has passed after the second switching unit 21b generates the idling control signal Id (step S413: Yes), the phase voltage is not generated, and in order to make the voltage measuring unit 17 measure the voltage measurement value Vmeas, a measurement trigger signal Tr is generated (step S414), so that the voltage measuring unit 17 measures the voltage measurement value Vmeas (ADC voltage measurement). The idling determination unit 22 uses the voltage measurement value Vmeas obtained in step S414 as a reference voltage.

[0178] The state control unit 12 then enters the discharge mode, so the first switch unit 21a generates the idle control signal Id that switches to the first switch state corresponding to the discharge mode (step S420). At this time, the state control unit 12 resets the discharge time and the mask time (step S421).

[0179] The state control unit 12 generates an idle control signal Id in step S420 to switch the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switch state. That is, according to the idle control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are switched to the first switch state. Figure 4 As shown, the first switching state is returned. At this time, when the motor is idling, an inductive kickback is generated in the inverter circuit.

[0180] The state control unit 12 determines whether the mask time has passed (step S422). In the state control unit 12, when the mask time has passed (step S422: Yes), in the case of motor idling, a voltage change due to inductive kickback occurs, so in order to make the voltage measuring unit 17 measure the voltage measurement value Vmeas, a measurement trigger signal Tr is generated, and the voltage measuring unit 17 is caused to measure the voltage measurement value Vmeas (ADC voltage measurement) (step S423). The idling determination unit 22 uses the voltage measurement value Vmeas obtained in step S423 as the measurement voltage.

[0181] In the ADC voltage measurement in step S413 and step S423, the state control unit 12 outputs a measurement trigger signal Tr for idling detection to the voltage measuring unit 17, and switches the sampling circuit 172 of the voltage measuring unit 17. For example, in the case of idling detection using the phase voltage Vu of the U phase, the voltage measuring unit 17 performs A / D conversion on the differential voltage detection signal Vd corresponding to the phase voltage Vu of the U phase outputted from the differential voltage detection circuit 15, and further performs ADC offset adjustment to generate the voltage measurement value Vmeas. The voltage measuring unit 17 outputs the voltage measurement value Vmeas to the idling determination unit 22 of the state control unit 12. Therefore, the voltage measurement value Vmeas corresponds to the voltage (differential voltage detection signal Vd) of the phase voltage (selected phase voltage signal Vm) of the selected phase and the neutral point voltage (neutral point voltage Vn) and the voltage after ADC offset adjustment by the ADC offset adjustment value.

[0182] In the state control unit 12, the idling determination unit 22 determines whether the difference between the reference voltage obtained in step S414 and the measured voltage obtained in step S423 (differential voltage detection signal Vd) is greater than the maximum fluctuation voltage difference (step S424). In step S424, when it is determined that the difference between the reference voltage and the measured voltage is greater than the maximum fluctuation voltage difference (step S424: yes), the maximum fluctuation voltage difference is updated to the value of the current difference (step S425). In step S425, the difference between the reference voltage obtained in step S414 and the measured voltage obtained in step S423 is directly used as the maximum fluctuation voltage difference, and then updated.

[0183] The state control unit 12 determines whether the discharge time has passed (step S426). If the discharge time has passed (step S426: Yes), the state control unit 12 enters the free mode (step S430). On the other hand, if the discharge time has not passed (step S426: No), the state control unit 12 performs the ADC voltage measurement again (steps S423 to S425). Fig. 9As shown, after the mask time of step S422 has expired, the state control unit 12 generates the discharge measurement trigger signal Tr at a predetermined cycle until the discharge time has elapsed, and causes the voltage measurement unit 17 to measure a plurality of voltage measurement values ​​Vmeas (steps S423 to S426).

[0184] The idling determination unit 22 determines whether the motor 3 is idling based on the maximum fluctuation voltage difference generated in steps S423 to S426 (step S431). In step S431, the idling determination unit 22 compares the maximum fluctuation voltage difference with the idling threshold value to determine whether the motor 3 is idling.

[0185] When the maximum fluctuating voltage difference exceeds the threshold value (step S431 : Yes), the idling determination unit 22 determines that the motor 3 is in the idling state.

[0186] On the other hand, when the maximum fluctuation voltage difference does not exceed the threshold value (step S431: No), the idling determination unit 22 determines that the motor 3 is stopped (not idling). The idling determination unit 22 generates an idling determination signal indicating the idling determination result. The idling determination signal is used by the state control unit 12.

[0187] return Fig.16 The state control unit 12 determines whether the motor 3 is in the idling determination according to the generated idling determination signal (step S130), and if it is determined to be in the idling determination (step S130: yes), the motor is driven by the sensorless drive. On the other hand, if it is determined not to be in the idling determination (step S130: no), the state control unit 12 drives the motor by the brake, excitation, forced commutation start, etc.

[0188] In the above-described embodiment, the control circuit 1 of the motor drive control device 10 switches the switching states of the switching elements Q1 to Q6 of the inverter circuit 2a. When the rotor of the motor 3 is idling, an induced current is generated that circulates between the coil of the motor 3 and the inverter circuit 2a. Then, the control circuit 1 determines that the motor 3 is idling based on the phase voltage generated by the induced kickback generated in the inverter circuit when the path of the induced current is cut off.

[0189] Thus, the motor drive control device 10 can detect whether the motor 3 is in an idling state stably in a short time without using a position sensor.

[0190] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the control circuit 1 has: a first switching unit 21a, which switches from a first switching state in which all the high-side switches and the low-side switches included in the inverter circuit 2a are disconnected to a second switching state in which all the high-side switches or the low-side switches included in the inverter circuit 2a are connected; a second switching unit 21b, which switches from the second switching state to the first switching state; and an idling determination unit 22, which determines that the motor is idling based on the phase voltage generated in the phase voltage detection circuit when switching from the second switching state to the first switching state.

[0191] Thus, the switching elements Q1 to Q6 of the inverter circuit 2a can be switched to switch states corresponding to three modes (free mode, charging mode, and discharging mode) for detecting the idling of the motor 3 to detect whether the motor 3 is in an idling state.

[0192] In addition, in the motor drive control device 10 of the above-mentioned embodiment, the control circuit 1 has a differential voltage detection circuit 15, and the differential voltage detection circuit 15 detects the difference voltage between the phase voltage of a selected phase in the phase voltage detection circuit and the neutral point voltage Vn obtained by synthesizing the phase voltages of all phases in the phase voltage detection circuit as a differential voltage detection signal Vd, and the idling determination unit 22 determines whether the motor 3 is idling based on the differential voltage detection signal Vd.

[0193] Thus, the neutral point voltage Vn synthesized from the phase voltages can be used to determine whether the motor 3 is idling by the difference voltage between the phase voltage of one selected phase and the neutral point voltage Vn synthesized from the phase voltages of all the phases.

[0194] Furthermore, in the motor drive control device 10 of the above-described embodiment, the idling determination unit 22 uses the differential voltage detection signal Vd detected by the differential voltage detection circuit 15 in the second switch state as the reference voltage.

[0195] Thus, in the second switching state, no induced voltage is generated in the phase voltage detection circuit, so that the idling determination unit 22 can use the differential voltage detection signal Vd detected by the differential voltage detection circuit 15 as a reference voltage for idling determination.

[0196] In addition, in the motor drive control device 10 of the above-mentioned embodiment, when switching from the second switch state to the first switch state, the differential voltage detection signal Vd detected multiple times in the differential voltage detection circuit 15 is used as the measurement voltage, and the maximum variable voltage difference in which the difference between the reference voltage and the measurement voltage is the largest is calculated. When the calculated maximum variable voltage difference is greater than the threshold value, it is determined that the motor 3 is in an idling state.

[0197] Thus, in the discharge mode, the voltage variation of the phase voltage due to the inductive kickback is utilized to stably perform the idling determination.

[0198] <<Expansion of Implementation Methods>> As mentioned above, although the invention completed by the present inventors has been specifically described based on the embodiment, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

[0199] In the embodiment, the speed command signal Sc includes the target value (target rotation speed) of the rotation speed of the motor 3 , but the present invention is not limited thereto. For example, the speed command signal Sc may be a torque command signal that specifies the torque of the motor 3 .

[0200] In addition, in the embodiment, the description is given based on the example that the motor drive control device 10 does not use a position sensor, but a position sensor may also be provided. Even in this case, the position sensor is used when driving the motor and does not need to be used when performing idling detection. As a position sensor, a Hall element that outputs a Hall signal may be used, or it may be configured to replace such a Hall signal and input other signals corresponding to the position of the rotor of the motor 3 as a rotor position detection signal. For example, it may also be configured to provide an encoder, a rotary transformer, etc., and input its detection signal to the control circuit 1. In addition, as a measurement circuit for each phase voltage, it may be configured to input the signal of an A / D converter or a comparison device that compares each phase voltage with the neutral point voltage as a rotor position detection signal.

[0201] In addition, in the embodiment, the motor drive control device 10 is described as an example in which the motor drive control device 10 can perform overcurrent detection by the current detection circuit 2c, but when overcurrent detection is not performed, the current detection circuit 2c may not be provided. In this case, the measurement type selection multiplexer 171 in the voltage measurement unit 17 can be omitted, and the measurement type selection signal Ss input to the measurement type selection multiplexer 171 can also be omitted.

[0202] In the embodiment, the control circuit 1 is not limited to the above-mentioned circuit configuration. The control circuit 1 can adopt various circuit configurations configured to meet the purpose of the present invention.

[0203] Specifically, the voltage determination unit 16 may be used instead of the voltage measurement unit 17, and a signal as a threshold value (idling threshold value) may be output from the comparison device D / A converter 161. When the maximum differential voltage detection signal Vd exceeds the threshold value, it is determined that the motor 3 is in an idling state, and an idling determination signal is output to the state control unit 12. In addition, a plurality of comparison devices and A / D converters may be used instead of the multiplexer of the differential voltage detection circuit 15 and the voltage measurement unit 17.

[0204] Furthermore, in the embodiment, by periodically repeating the charging mode and the discharging mode, it is possible to detect whether the motor is in an idling state and wait for the motor to stop.

[0205] In the embodiment, the driving of the motor is not limited to the 120-degree energization rectangular wave driving, and the 150-degree energization rectangular wave driving or the sine wave driving may also be used.

[0206] In the embodiment, the number of phases of the motor 3 driven by the motor drive control device 10 is not limited to three phases.

[0207] The above flowchart is a specific example and the present invention is not limited to the flowchart. For example, other processing may be inserted between each step, and the processing may be parallelized.

[0208] In the ADC offset measurement of step S300 in the above flowchart, it is determined whether the end of the ADC voltage measurement count exceeds the ADC offset measurement count in step S304. Alternatively, it may be determined whether the measurement time has exceeded.

[0209] In the idle running detection of step S400 in the above flowchart, it is determined whether the end of the number of ADC voltage measurements exceeds the discharge time in step S426, but it may be determined whether the number of measurements exceeds instead. Description of Reference Numerals

[0210] 1: control circuit; 2: drive circuit; 2a: inverter circuit; 2b: pre-drive circuit; 2c: current detection circuit; 3: motor; 10: motor drive control device; 11: drive instruction acquisition unit; 12: state control unit; 13: rectangular wave control unit; 14: PWM signal generation unit; 15: differential voltage detection circuit; 16: voltage determination unit; 17: voltage measurement unit; 21a: first switching unit; 21b: second switching unit; 22: idling determination unit; 151: multiple resistor elements for DC current limitation and voltage adjustment; 152: multiplexer for measurement phase selection; 153: differential amplifier circuit; 161: D / A converter for comparison device; 162: comparison device; 171: multiplexer for measurement type selection; 172: sampling circuit; 173: D / A converter for A / D converter; 174: comparator; 175: offset meter Calculator; 100: motor unit; Q1~Q6: switching elements; Rs: shunt resistor; Sc: speed command signal; Sd: drive control signal; Id: idling control signal; ωref: target speed; So: drive command signal; Sm: measurement phase selection signal; Ss: measurement type selection signal; Tr: measurement trigger signal; Vjudge: voltage judgment signal; Vmeas: voltage measurement value; Vd, Vd': differential voltage detection signal; Vm: selected phase voltage signal; Vn: neutral point voltage (synthetic signal); Vdc, Vin: DC power supply; Vs: shunt current detection signal; Vuu, Vul, Vvu, Vvl, Vwu, Vwl: drive signal; Vu, Vv, Vw: phase voltage; Lu, Lv, Lw: coil; Iu, Iv, Iw: winding current; eu, ev, ew: induced voltage.

Claims

1. A motor drive control device, comprising: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit having an inverter circuit including a high-side switch and a low-side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, wherein the high-side switch and the low-side switch are alternately turned on / off according to the drive control signal to switch the energization direction of the coils of the corresponding phases, thereby rotating the rotor of the motor; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coils of each phase of the motor, In the control circuit, In a case where the rotor of the motor is caused to idle by switching the switching state of the inverter circuit by generating an idling control signal instead of the drive control signal, after an induced current is generated that circulates between the coil of the motor and the inverter circuit, the motor is determined to be idling based on the phase voltage generated in the phase voltage detection circuit according to the induced kickback generated in the inverter circuit when the path of the induced current is cut off.

2. The motor drive control device according to claim 1, wherein: The control circuit has: a first switching unit, switching from a first switching state in which all the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switching state in which all the high-side switches or the low-side switches included in the inverter circuit are turned on; a second switching unit, switching from the second switching state to the first switching state; and The idling determination unit determines that the motor is idling based on the phase voltage generated in the phase voltage detection circuit when the second switch state is switched to the first switch state.

3. The motor drive control device according to claim 2, wherein: The control circuit includes a differential voltage detection circuit, which detects a differential voltage between a phase voltage of one phase selected in the phase voltage detection circuit and a neutral point voltage obtained by synthesizing the phase voltages of all phases in the phase voltage detection circuit as a differential voltage detection signal. The idling determination unit determines whether the motor is idling based on the differential voltage detection signal.

4. The motor drive control device according to claim 3, wherein: The idling determination unit uses the differential voltage detection signal detected by the differential voltage detection circuit in the second switch state as a reference voltage.

5. The motor drive control device according to claim 4, wherein: When switching from the second switch state to the first switch state, the differential voltage detection signal detected multiple times in the differential voltage detection circuit is used as the measurement voltage, and the maximum variable voltage difference between the reference voltage and the measurement voltage is calculated. When the calculated maximum variable voltage difference is greater than a threshold value, it is determined that the motor is in an idling state.

6. A motor idling detection method, executed in a motor drive control device, the motor drive device comprising: a control circuit, generating a drive control signal for driving a motor having a coil of at least one phase; a drive circuit, having an inverter circuit including a high-side switch and a low-side switch connected in series with each other and arranged corresponding to the coils of each phase of the motor, wherein the high-side switch and the low-side switch are alternately turned on / off according to the drive control signal to switch the energization direction of the coil of the corresponding phase, thereby rotating the rotor of the motor; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coils of each phase of the motor, the motor idling detection method comprising: The first step is to switch from a first switching state in which all the high-side switches and the low-side switches included in the inverter circuit are disconnected to a second switching state in which all the high-side switches or the low-side switches included in the inverter circuit are connected; A second step is to switch from the second switch state to the first switch state; and In a third step, when the first switch state is switched, it is determined based on the phase voltage that the motor is idling.

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