Motor drive control device and idling detection method for motor

Abstract

To provide a motor drive control device capable of detecting presence / absence of an idling state of a motor in a short time and stably.SOLUTION: A motor drive control device comprises: a control circuit which generates a drive control signal; a drive circuit which includes an inverter circuit including a switch provided correspondingly to a coil of each phase of a motor and rotates a rotor of the motor by alternately turning on / turning off the switches in accordance with the drive control signal; and a phase voltage detection circuit for detecting a phase voltage which is generated between the inverter circuit and the coil of each phase of the motor. The control circuit generates an idling control signal and changes over a switch state of the inverter circuit. Therefore, in a case where idling occurs in the rotor of the motor, a current which circulates between the coil of the motor and the inverter circuit is generated, and it is then determined that the idling occurs in the motor on the basis of the phase voltage which is generated in the phase voltage detection circuit by inductive kickback which occurs when a path of the current is cut off.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Generally, in motors (hereinafter also referred to as "fan motors") used in fans for cooling the inside of electronic devices such as servers, the motor may enter a state in which it continues to rotate due to inertia or the action of an external force, even though it is not being driven by a drive circuit for driving the motor, a state known as idling.

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

[0004] [Patent Document 1] JP 2018-170928 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method described in Patent Document 1 detects the rotation speed of a motor in an idling state, but there are cases where it is sufficient to detect whether or not the motor is in an idling state in a short time without detecting the rotation speed of the idling motor. 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, winding resistance measurement and rotor initial position detection, which utilize the current flowing through the shunt resistor by energizing the coil of the motor, are adversely affected by the change in the periodic induced voltage and induced current, and therefore must be performed when the motor is not idling. For this reason, the presence or absence of the idling state of the motor can be used as a judgment index for executing various processes.

[0006] In addition, while the presence or absence of the motor in an idling state can be easily detected by using a position sensor, it is preferable to be able to detect the presence or absence of the motor in an idling state without using a position sensor, since this allows the device configuration to be simplified.

[0007] Furthermore, in the case of detecting free rotation of a motor using phase voltages, conventional methods turn off all of the switching elements that make up the inverter circuit to create a high impedance state, and, in the same way as driving a motor, detect whether the rotor is free rotation by utilizing the zero crossing of the differential voltage between the induced voltage generated in each winding due to rotor rotation and the neutral point voltage which is a combination of the voltages of all the windings. However, at low speeds, the generated induced voltage is small and the time to detect the zero crossing is long, so there is a problem that there is a limit to the minimum detectable rotation speed, and it is not possible to stably determine whether the motor is free rotation in a short period of time.

[0008] For these reasons, there is a demand for a motor drive control device that can stably detect whether or not the motor is in an idling state in a short period of time with a simple configuration without using a position sensor.

[0009] The present invention is intended to solve the above-mentioned problems, and aims to provide a motor drive control device that can stably detect whether or not a motor is spinning in a short period of time without using a position sensor. [Means for solving the problem]

[0010] A motor drive control device according to a representative embodiment of the present invention includes a control circuit that generates a drive control signal for driving a motor having a coil of at least one phase; an inverter circuit including high-side switches and low-side switches connected in series to each other and provided corresponding to the coils of each phase of the motor, and a drive circuit that rotates a rotor of the motor by alternately turning on and off the high-side switch and the low-side switch in response to the drive control signal to switch the direction of current flow through the coil of the corresponding phase; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coil of each phase of the motor, wherein the control circuit generates an idling control signal in place of the drive control signal and switches a switch state of the inverter circuit, thereby determining that the motor is idling based on the phase voltage generated in the phase voltage detection circuit due to inductive kickback that occurs in the inverter circuit when the path of the induced current is interrupted after generating an induced current that circulates between the coil of the motor and the inverter circuit when the control circuit determines that the motor is idling. Effect of the Invention

[0011] According to one aspect of the present invention, a motor drive control device can stably detect whether or not a motor is in an idling state within a short period of 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 equipped with a motor drive control device 10 according to an embodiment. [Diagram 2]10 is a diagram for explaining a switch state corresponding to a free mode, which is switched by a spin control signal Id. FIG. [Diagram 3] 10 is a diagram for explaining a switch state corresponding to a charging mode, which is switched by a spin control signal Id. FIG. [Figure 4] 10 is a diagram for explaining a switch state corresponding to a discharge mode, which is switched by an idling control signal Id. FIG. [Diagram 5] 1 is a diagram showing a functional block configuration of a control circuit 1 in a motor drive control device 10 according to an embodiment. [Figure 6] 2 is a diagram showing an example of the configuration of a differential voltage detection circuit 15. FIG. [Figure 7] 2 is a diagram illustrating an example of the configuration of a voltage determination unit 16. FIG. [Figure 8] FIG. 2 is a diagram illustrating an example of the configuration of a voltage measuring unit 17. [Figure 9] 1 is a timing chart showing an example of a signal waveform from when a speed command signal Sc is input after power is applied to a motor unit 100 until a determination of free spin is completed. FIG. [Figure 10] 1 shows a first waveform pattern indicating a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating idly and a resultant differential voltage pattern. [Figure 11] 13 is a second waveform pattern showing a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating freely and a resultant differential voltage pattern. [Figure 12] 13 is a third waveform pattern showing a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating freely and a resultant differential voltage pattern. [Figure 13] 13 is a fourth waveform pattern showing a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating freely and a resultant differential voltage pattern. [Figure 14]13 is a fifth waveform pattern showing a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating freely and a resultant differential voltage pattern. [Figure 15] 13 is a sixth waveform pattern showing a phase voltage pattern generated in a phase voltage detection circuit in a discharge mode when the rotor of a motor 3 is rotating freely and a resultant differential voltage pattern. [Figure 16] 5 is a flowchart showing an example of a process flow when power is turned on in a control circuit 1 of a motor drive control device 10 according to an embodiment. [Figure 17] 11 is a flowchart showing an example of a flow of measurement selection based on a measurement type selection signal Ss and a measurement phase selection signal Sm output from a state control unit 12. [Figure 18] 4 is a flowchart showing an example of a flow of ADC offset measurement by the control circuit 1 of the motor drive control device 10. [Figure 19] 4 is a flowchart showing an example of a flow of slip detection by the control circuit 1 of the motor drive control device 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, as an example, reference numerals in the drawings corresponding to components of the invention are given in parentheses.

[0014] [1] A motor drive control device (10) according to a representative embodiment of the present invention includes a control circuit (1) that generates a drive control signal (Sd) for driving a motor having a coil of at least one phase, and an inverter circuit (2a) including high-side switches (Q1, Q3, Q5) and low-side switches (Q2, Q4, Q6) connected in series to each other and provided corresponding to the coil of each phase of the motor (3), and a drive circuit (2) that alternately turns on and off the high-side switch and the low-side switch in response to the drive control signal to switch the direction of current flow to the coil of the corresponding phase, thereby rotating a rotor of the motor. and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and a coil of each phase of the motor, wherein the control circuit generates an idling control signal (Id) in place of the drive control signal and switches the switch state of the inverter circuit, thereby determining that the motor is idling based on the phase voltage generated in the phase voltage detection circuit due to inductive kickback that occurs in the inverter circuit when an induced current is generated that circulates between the motor coil and the inverter circuit when the path of the induced current is interrupted by switching the switch state of the inverter circuit.

[0015] [2] In the motor drive control device described in [1] above, the control circuit may have a first switching unit (21a) that switches from a first switch state in which all of the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switch state in which all of the high-side switches or the low-side switches included in the inverter circuit are turned on, a second switching unit (21b) that switches from the second switch state to the first switch state, and an idling determination unit (22) that determines whether the motor is idling based on a phase voltage generated in the phase voltage detection circuit when switching from the second switch state to the first switch state.

[0016] [3] In the motor drive control device described in [2] above, the control circuit may have a differential voltage detection circuit that detects, as a differential voltage detection signal, a difference voltage between a phase voltage of one selected phase in the phase voltage detection circuit and a neutral point voltage that is a combination of the phase voltages of all phases in the phase voltage detection circuit, and the idling determination unit may determine that the motor is idling based on the differential voltage detection signal.

[0017] [4] In the motor drive control device described above in [3], 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] 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 a measurement voltage, and a maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage is maximum is calculated, and if the calculated maximum fluctuation voltage difference is larger than a threshold value, it may be determined that the motor is in an idling state.

[0019] [6] A method for detecting idling of a motor according to a representative embodiment of the present invention is a method for detecting idling of a motor, the method being executed in a motor drive control device including: a control circuit for generating a drive control signal for driving a motor having a coil of at least one phase; an inverter circuit including high-side switches and low-side switches connected in series to each other and provided corresponding to the coils of each phase of the motor, and which rotates a rotor of the motor by alternately turning on and off the high-side switches and the low-side switches in response to the drive control signal to switch the direction of current flow through the coil of the corresponding phase; and a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and the coil of each phase of the motor, the method including: a first step of switching from a first switch state in which all of the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switch state in which all of the high-side switches or the low-side switches included in the inverter circuit are turned on; a second step of switching from the second switch state to the first switch state; and a third step of determining that the motor is idling based on the phase voltage when the first switch state is switched to.

[0020] 2. Specific examples of embodiments DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, components common to the respective embodiments are designated by the same reference numerals, and repeated description will be omitted.

[0021] <Embodiment> FIG. 1 is a diagram showing a configuration of a motor unit 100 equipped with a motor drive control device 10 according to an embodiment.

[0022] 1, the motor unit 100 includes a motor 3 and a motor drive control device 10 that controls the rotation of the motor 3. The motor unit 100 can be applied to various devices that use a motor as a drive source, such as a fan or a drone (unmanned aerial vehicle).

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

[0024] The motor drive control device 10 applies a 120-degree conduction rectangular wave drive signal to the motor 3, for example, to periodically pass drive current through the three-phase coils Lu, Lv, and Lw of the motor 3, causing the rotor of the motor 3 to rotate.

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

[0026] It should be noted that the components of the motor drive control device 10 shown in FIG. 1 are only a portion of the whole, and the motor drive control device 10 may have other components in addition to those shown in FIG.

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

[0028] The inverter circuit 2a is a circuit disposed between a DC power supply Vin and a ground potential, and drives coils Lu, Lv, and Lw of a motor 3 as a load based on an input drive control signal Sd. Specifically, in the embodiment, the inverter circuit 2a has three switching legs, each including two drive transistors connected in series, and drives the motor 3 as a load by alternately turning on and off the two drive transistors (switching operation) based on the input drive control signal Sd.

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

[0030] Here, the driving transistors Q1, Q3, and Q5 (corresponding to high-side switches) of the upper arm of the coil of the motor 3 are, for example, N-channel MOSFETs, and the driving transistors Q2, Q4, and Q6 (corresponding to low-side switches) of the lower arm of the coil of the motor 3 are, for example, N-channel MOSFETs. Note that the driving transistors Q1 to Q6 may be other types of FETs, such as IGBTs (Insulated Gate Bipolar Transistors).

[0031] For example, the switching leg corresponding to the U phase has switching elements Q1 and Q2 connected in series. The common connection point of the switching elements Q1 and Q2 is connected to one end of the coil Lu as a load. The switching leg corresponding to the V phase has switching elements Q3 and Q4 connected in series. The common connection point of the switching elements Q3 and Q4 is connected to one end of the coil Lv as a load. The switching leg corresponding to the W phase has switching elements Q5 and Q6 connected in series. The common connection point of the switching elements Q5 and Q6 is connected to one end of the coil Lw as a load. In addition, the switching elements Q1 and Q2, Q3 and Q4, and Q5 and Q6 each have a parasitic diode characteristic from the ground side to the power supply side (not shown in FIG. 1).

[0032] The pre-drive circuit 2b generates a drive signal for driving the inverter circuit 2a based on the drive 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 current conduction pattern of the coils Lu, Lv, and Lw of the motor 3, which is determined by the on / off state of each switching element constituting the inverter circuit 2a. More specifically, the drive control signal Sd includes six types of PWM signals corresponding to each switching element Q1 to Q6 of the inverter circuit 2a.

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

[0035] These drive signals Vuh, Vul, Vvh, Vvl, Vwh, and Vwl are input to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a, causing each of the switching elements Q1 to Q6 to perform an on-off operation (switching action). For example, the switching elements Q1, Q3, and Q5 of the upper arm and the switching elements Q2, Q4, and Q6 of the lower arm of the switching leg corresponding to each phase alternately perform an on-off operation. As a result, power is supplied from the DC power supply Vin to each phase of the motor 3, causing the motor 3 to rotate.

[0036] The current detection circuit 2c is connected to the DC line of the inverter circuit 2a and detects the current flowing through the DC line. Specifically, it includes one resistor (hereinafter also referred to as a "shunt resistor") Rs as a current detection element. The shunt resistor Rs is connected in series with the inverter circuit 2a between, for example, a DC power supply Vin and a ground potential. That is, the shunt resistor Rs of the current detection circuit 2c is connected to the negative side (ground side) of the inverter circuit 2a, for example, as shown in FIG. 1. When driving the motor, the inverter circuit 2a is controlled, and the winding currents Iu, Iv, and Iw of each phase that flow through 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 a voltage drop due to the current flowing through the shunt resistor Rs from the differential voltage across the shunt resistor Rs, and outputs a shunt current detection signal Vs corresponding to the current flowing through the shunt resistor Rs to the control circuit 1 as a detection result. The shunt resistor Rs can function as an overcurrent detection circuit, as will be described later.

[0037] Between the inverter circuit 2a and the coils Lu, Lv, Lw of each phase of the motor 3, wiring (hereinafter also referred to as a "phase voltage detection circuit") for measuring the phase voltages Vu, Vv, Vw generated in each phase is connected and input to the control circuit 1. In the control circuit 1, a differential voltage (a difference voltage between the neutral point voltage and the phase voltage of a selected phase: a value according to the phase voltage of the selected phase) measured based on the phase voltages Vu, Vv, Vw generated in each phase is used when controlling the drive of the motor or detecting idling of the motor, which will be described later.

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

[0039] In detecting idling of the motor, the control circuit 1 generates an idling control signal Id (described later) instead of the drive control signal Sd and detects idling of the motor 3. Specifically, when the motor 3 is not being driven by the drive control signal Sd, the control circuit 1 generates an idling control signal Id and provides it to the drive circuit 2 so that each of the switching elements Q1 to Q6 of the inverter circuit 2a is in a switch state designated by the idling control signal Id.

[0040] Here, we will explain the switch states of each switching element Q1 to Q6 of the inverter circuit 2a corresponding to the three modes (free mode, charge mode, and discharge mode) for detecting idling of the motor 3, which are switched by the idling control signal Id generated by the control circuit 1.

[0041] 2 to 4 are diagrams for explaining the states of the switches switched by the idling control signal Id. In Fig. 2 to 4, the state of the current flowing through the coil of the motor 3 and the inverter circuit 2a when the motor 3 is idling is indicated by arrows. The inverter circuit 2a is connected to a DC power source Vin and is also connected to ground via a shunt resistor Rs, which is part of the current detection circuit 2c. Furthermore, 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 a signal that switches the switch state to the corresponding free mode (Fig. 2), charge mode (Fig. 3), and discharge mode (Fig. 4) in that order. Specifically, the idling control signal Id switches the switch state of the control electrode (gate electrode) of each of the switching elements Q1 to Q6 of the inverter circuit 2a from the first switch state (corresponding to the free mode) shown in Fig. 2 to the second switch state (corresponding to the charge mode) shown in Fig. 3, and then back to the first switch state (corresponding to the discharge mode) as shown in Fig. 4, thereby making it possible to detect idling of the motor 3.

[0043] (Free Mode) When the control circuit 1 outputs an idling control signal Id at a predetermined timing after power is turned on, the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a are switched to a first switch state by the idling control signal Id output from the control circuit 1. Specifically, as shown in Fig. 2, in the inverter circuit 2a, the switch states of all of the switching elements Q1 to Q6 are switched to OFF.

[0044] 2, in this first switch state, when the rotor of the motor 3 is rotating freely, an induced electromotive force is generated in the coils of each phase, and a voltage is generated in the phase voltage detection circuit, but because each of the switching elements Q1 to Q6 is turned off and the parasitic diodes are clamped, no induced current is generated that circulates between the coils of the motor 3 and the inverter circuit 2a. At this time, an induced voltage according to the number of rotations of the idling 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 switch state to the second switch state by the idling control signal Id output from the control circuit 1. The second switch state is a switch state in which, when the rotor of the motor 3 is idling, an induced electromotive force is generated in the coils of each phase, and the generated induced current circulates in a closed circuit formed by the coils and the switching elements among the switching elements Q1 to Q6 that are turned on. Specifically, in the inverter circuit 2a, the first switch state in which all the switching elements Q1 to Q6 are turned off is switched to a second switch state in which only the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 are turned on, as shown in FIG. 3.

[0046] 3, in the inverter circuit 2a, when the switching state of the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 is turned on to a second switching state, if the rotor of the motor 3 is rotating idly, an induced current is generated in the coil of each phase, circulating between the coil of the motor 3 and the inverter circuit 2a, and the generated induced current circulates in a closed circuit formed by the coil and the switching elements Q2, Q4, and Q6 of the lower arms that are 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 rotation of the rotor relative to the coil generates an induced voltage (eu, ev, ew) in each phase coil that is proportional to the rotation speed, with a polarity in the direction that generates a current that hinders changes in the magnetic flux, with a period of electrical angle of the motor rotation with each phase shifted by 120 degrees. At this time, the current waveform is 90 degrees behind 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 from the second switch state back to the first switch state by the idling control signal Id output from the control circuit 1. Specifically, for example, in the inverter circuit 2a, the switch states of the switching elements Q2, Q4, and Q6 of the lower arms of the switching elements Q1 to Q6 are switched on, and then switched back to the first switch state, as shown in FIG.

[0049] As shown in Fig. 4, when the rotor of the motor 3 is spinning freely, the path of the circulating induced current is cut off when the inverter circuit 2a changes from the second switch state to the first switch state. At this time, the induced current (A in Fig. 4) that had been circulating through the coil of the winding of the motor 3 tries to continue to flow through the coil, causing an inductive kickback (B in Fig. 4) in the inverter circuit 2a. Specifically, a voltage rise occurs at the connection point between the upper and lower arms of the leg of the phase on the downstream side of the induced current, and a voltage drop occurs at the connection point between the upper and lower arms of the leg of the phase on the upstream side of the induced current. This voltage fluctuation is clamped by the parasitic diodes of each switching element Q1 to Q6, so that in the case where the motor has three phases, the phase at the most downstream side of the induced current rises to Vin+Vf from the DC power supply Vin and the forward voltage Vf of the parasitic diode, and the phase at the most upstream side of the induced current drops to -Vf, and the remaining phases rise to Vin+Vf or drop to -Vf depending on the direction of the induced current, depending on the rotor position. This voltage fluctuation is short, and in the case where the motor has three phases, the voltage fluctuation time of the phase at the most downstream side and the phase at the most upstream side of the induced current is the longest, depending on the rotor position. At this time, a voltage fluctuation due to inductive kickback also occurs in the phase voltage detection circuit. This voltage fluctuation also occurs in the case where the coil has 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, the voltage generated in the phase voltage detection circuit is detected, and if it is determined that a voltage fluctuation due to inductive kickback has occurred, it can determine that the motor 3 is in an idling state.

[0051] In the above example, as the second switch state corresponding to the charging mode, as shown in Fig. 3, the case where all of the switching elements Q2, Q4, and Q6 of the lower arm among the switching elements Q1 to Q6 of the inverter circuit 2a are switched on has been described as an example, but the present invention is not limited to this. All of the switching elements Q1, Q3, and Q5 of the upper arm among the switching elements Q1 to Q6 of the inverter circuit 2a may be switched on.

[0052] The idling control signal Id is a signal for switching each of the switching elements constituting the inverter circuit 2a to a switch state corresponding to three modes for detecting idling of the 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 is therefore not a signal for alternately switching each switching element on and off, but is, for example, a high or low signal having a predetermined length. The idling control signal Id includes six types of signals corresponding to each of the switching elements Q1 to Q6 of the inverter circuit 2a.

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

[0054] The pre-drive circuit 2b generates signals capable of supplying sufficient power to switch the switch states of the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a based on six types of signals as the idling control signal Id supplied from the control circuit 1. The switch states of the switching elements Q1 to Q6 are switched by inputting drive signals as these switching signals to the control electrodes (gate electrodes) of the switching elements Q1 to Q6 of the inverter circuit 2a. The details of the idling control signal Id will be described later.

[0055] In an embodiment, the control circuit 1 is a program processing device (e.g., a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output I / F circuit are connected to each other via a bus or a dedicated line.

[0056] The motor drive control device 10 may be configured such that at least a part of the control circuit 1 and at least a part of the drive circuit 2 are packaged as a single integrated circuit device (IC), or the control circuit 1 and the drive circuit 2 are each packaged as separate integrated circuit devices.

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

[0058] 5, the control circuit 1 has a drive command acquisition unit 11, a state control unit 12, a square 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 by, for example, a 120-degree conduction square wave drive method. The control circuit 1 also has a state control unit 12, a differential voltage detection circuit 15, and a voltage measurement unit 17 as functional blocks for generating a spin control signal Id in detecting idling of the motor. The state control unit 12 has a first switching unit 21a, a second switching unit 21b, and a spin determination unit 22.

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

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

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

[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 of a target rotation speed (target rotational 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] In driving the motor, the state control unit 12 outputs the target rotation speed ωref as it is to the square wave control unit 13. The state control unit 12 can determine the motor starting method when a slip determination signal, which will be described later, is generated from the slip determination unit 22. Although not particularly shown in Fig. 5, the state control unit 12 may further have a functional unit that executes such processing.

[0065] In driving the motor, the rectangular wave control unit 13 outputs a drive command signal So to the PWM signal generation unit 14, outputs a measurement phase selection signal Sm to the differential voltage detection circuit 15, and outputs a measurement type selection signal Ss and a measurement trigger signal Tr to the voltage measurement unit 17. The measurement phase selection signal Sm is a signal for selecting a phase to be detected in the differential voltage detection circuit 15 among the phases of the motor coil. The measurement type selection signal Ss is a signal for selecting a 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 measurement in the voltage measurement unit 17, for example, a signal for turning on and 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 current directions in the drive control method using a 120-degree rectangular wave when driving the motor, the rectangular wave control unit 13 outputs a measurement phase selection signal Sm corresponding to the non-current phase (induced voltage phase) to the differential voltage detection circuit 15, receives a voltage judgment signal Vjudge indicating the timing of the zero crossing judged by the voltage judgment unit 16 of the differential voltage between the induced voltage of the selected non-current phase and the neutral point voltage, and adjusts the current switching in the drive control.

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

[0068] In order to detect whether an overcurrent occurs in the inverter circuit when driving the motor, the square wave control unit 13 outputs a measurement trigger signal Tr and a measurement type selection signal Ss to the voltage measurement unit 17, receives a voltage measurement value Vmeas corresponding to the shunt current detection signal Vs measured by the voltage measurement 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 to control the drive of the motor in response to the overcurrent.

[0069] In driving the motor, the PWM signal generating unit 14 generates a drive control signal Sd in response to the drive command signal So received from the rectangular wave control unit 13, outputs the signal to the drive circuit 2, and performs 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 to the voltage determination unit 16 and the voltage measurement unit 17 as a differential voltage detection signal Vd.

[0071] 6 is a diagram showing an example of the configuration of differential voltage detection circuit 15. Here, the example of the configuration of 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 a 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 resistance elements 151 for DC current limiting and voltage adjustment, a measurement phase selection multiplexer (MUX) 152, and a differential amplifier circuit 153. The differential voltage detection circuit 15 branches the input of the phase voltages Vu, Vv, Vw of each phase into two, combines one of the branches, and inputs it to the differential amplifier circuit 153 as a combined signal (neutral point voltage) Vn, and inputs the other to the measurement phase selection multiplexer 152. The differential amplifier circuit 153 also receives the output from the measurement phase selection multiplexer 152.

[0073] In the differential voltage detection circuit 15, the measurement phase selection multiplexer 152 selects one of the three phase voltages Vu, Vv, Vw according to a measurement phase selection signal Sm input from the state control unit 12 or the rectangular wave control unit 13, and outputs the selected phase voltage signal Vm to the differential amplifier circuit 153. A voltage corresponding to the phase voltage of the selected phase and a composite signal Vn of the three phase voltages Vu, Vv, Vw corresponding to the neutral point voltage of the motor coil are 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. Since 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 driving the motor and detecting idling of the motor, the differential amplifier circuit 153 scales (amplifies and reduces) the signal and shifts the DC power supply Vdc / 2, outputting a differential voltage detection signal Vd that is nearly similar to the differential voltage detection signal Vd' and saturated in the voltage range from 0V to Vdc centered on Vdc / 2. In other words, the differential voltage detection signal Vd is a signal that corresponds to the phase voltage of the selected phase.

[0074] The voltage determination unit 16 is a comparator that compares the voltage of a predetermined signal with the voltage 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 when the motor is driven.

[0075] 7 is a diagram showing an example of the configuration of the voltage determination unit 16. Here, a description will be given of an example of the configuration of the voltage determination unit 16. The voltage determination unit 16 is configured to include a comparator D / A converter 161 and a comparator 162, for example, as shown in FIG.

[0076] In driving the motor, the voltage judgment unit 16 judges 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. Since the differential voltage detection signal Vd is shifted by Vdc / 2 in the differential voltage detection circuit 15, in the voltage judgment unit 16, the comparator D / A converter 161 inputs a predetermined zero crossing reference value using Vdc / 2 as an analog signal to the comparator 162. The comparator 162 compares the predetermined zero crossing reference signal input from the comparator D / A converter 161 with the differential voltage detection signal Vd, and switches the signal output, which is 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 a signal indicating the timing of the zero crossing to the square wave control unit 13 as the voltage judgment signal Vjudge.

[0077] The voltage measurement unit 17 is an A / D converter that digitizes the voltage of the input signal selected by the multiplexer, and 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.

[0078] Fig. 8 is a diagram showing an example of the configuration of voltage measurement unit 17. Here, an example of the configuration of voltage measurement unit 17 will be described. For example, as shown in Fig. 8, voltage measurement unit 17 is configured to include a measurement type selection multiplexer 171, a sampling circuit 172, a D / A converter 173 for the A / D converter, a comparator 174, and an offset calculator 175.

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

[0080] In order to detect overcurrent when driving the motor, the voltage measurement unit 17 measures a voltage measurement value Vmeas corresponding to the shunt current detection signal Vs in accordance with the measurement type selection signal Ss and measurement trigger signal Tr input from the rectangular wave control unit 13, and outputs the voltage measurement value Vmeas to the rectangular wave control unit 13.

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

[0082] Here, the ADC offset adjustment in the voltage measurement unit 17 will be 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 in the voltage range from 0V to Vdc centered on Vdc / 2 by the differential amplifier circuit 153. For this reason, the value of the voltage measurement value Vmeas is secured in advance in the charging mode as a state in which no phase voltage is generated, and the ADC offset adjustment is performed to clarify the zero point of the differential voltage detection signal Vd.

[0083] The ADC offset adjustment in the voltage measurement unit 17 is also performed when 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 voltage when no shunt current is generated. For this reason, the value of the voltage measurement value Vmeas is secured in advance in the free mode or charging mode as a state in which no shunt current is generated, and the ADC offset adjustment is performed to clarify the zero point of the shunt current detection signal Vs.

[0084] For ADC offset adjustment, the state control unit 12 inputs a measurement trigger signal Tr to the voltage measurement unit 17 so that the differential voltage detection signal Vd is in a state where it should be zero. The voltage measurement unit 17 is triggered by the measurement trigger signal Tr, and 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 and used as the ADC offset adjustment value. This ADC offset adjustment value is used by the offset calculator 175 of the voltage measurement unit 17 to perform the ADC offset adjustment.

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

[0086] In the state control unit 12, when a freewheeling of the motor is detected, the first switching unit 21a generates a freewheeling control signal Id for switching to the first switch state and the second switching unit 21b generates a freewheeling control signal Id for switching to the second switch state and outputs it to the drive circuit 2. The start of generation of the freewheeling control signal Id can be triggered by power-on or by receiving a speed command signal Sc after the motor has stopped (a predetermined time has elapsed 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 a first switch 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 a second switch 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 set the switch state capable of detecting slip, after power is turned on, the switch state is switched to a predetermined state, and in a state in which no phase voltage is generated, the ADC offset measurement of the differential voltage detection signal Vd is performed. After that, until the drive command acquisition unit 11 receives the speed command signal Sc, the first switching unit 21a generates the slip control signal Id corresponding to the free mode and waits for the start of driving the motor. After that, in the state control unit 12, in order to detect the presence or absence of a slip state immediately before driving the motor by inputting the speed command signal Sc, the second switching unit 21b generates the slip control signal Id during the charging time (period corresponding to the charging mode). After that, in the state control unit 12, the first switching unit 21a again generates the slip control signal Id during the discharging time (period corresponding to the discharging mode). Note that after the discharging time in which the determination of slip is completed, the first switching unit 21a may again generate the slip control signal Id corresponding to the free mode. Also, in order to re-detect the presence or absence of a slip state of the motor, the charging mode and the discharging mode may be executed again.

[0089] The timing of transition from the free mode to the charging mode may be, for example, after the drive command acquisition unit 11 receives the speed command signal Sc.

[0090] In detecting the idling of the motor, at the timing immediately before the mode is switched from the charging mode to the discharging mode, that is, in a state in which no phase voltage is generated immediately before the switch state is switched from the second switch state to the first switch state, the state control unit 12 outputs to the voltage measurement unit 17 a measurement type selection signal Ss for selecting the differential voltage detection signal Vd in the measurement type selection multiplexer 171, and a measurement trigger signal Tr for idling detection for turning on the switch of the sampling circuit 172, thereby instructing the voltage measurement unit 17 to measure the inputted differential voltage detection signal Vd. Based on the instruction from the state control unit 12, the voltage measurement unit 17 performs A / D conversion on the inputted differential voltage detection signal Vd, and further performs ADC offset adjustment to generate a voltage measurement value Vmeas. The voltage measurement unit 17 outputs the generated voltage measurement value Vmeas to the idling determination unit 22 of the state control unit 12. This voltage measurement value Vmeas is used as a reference voltage. After measuring this differential voltage detection signal Vd, the mode is switched to the discharging mode.

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

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

[0093] The slip threshold value can be the maximum fluctuation voltage difference value at which the difference between the reference voltage and the measured voltage of the differential voltage detection signal Vd becomes maximum at the minimum rotation speed for detecting slip (minimum slip rotation speed).

[0094] The charging time may be a time measured in advance so that the minimum voltage fluctuation time at the minimum rotation speed (minimum idling rotation speed) for detecting idling can be measured, since the voltage fluctuation time generated in the phase voltage detection circuit by inductive kickback changes depending on the rotation speed and rotor position.Shortening the charging time is desirable because it shortens the idling detection period and reduces abnormal noise in the drive system due to a short brake state during charging.

[0095] The discharge time may be a time measured in advance so that the differential voltage detection signal Vd can be measured multiple times at the minimum rotation speed (minimum idling rotation speed) for detecting idling, since the voltage fluctuation generated in the phase voltage detection circuit by the inductive kickback attenuates over time and converges to a predetermined value. In addition, when a maximum fluctuation voltage difference is measured, which is the maximum difference between the reference voltage and the measured voltage of the differential voltage detection signal Vd measured multiple times, the measurement may be terminated without waiting for the discharge time to elapse.

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

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

[0098] In Figure 9, from top to bottom, there are shown the waveforms of the speed command signal Sc, the drive signals input to the gates of the switching elements Q1 to Q6, the measurement trigger signal Tr for detecting slip, 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 differential voltage detection signal Vd output from the differential voltage detection circuit 15.

[0099] The speed command signal Sc is a signal received as the target rotation speed ωref in the state control unit 12. The state control unit 12 generates, at a predetermined timing, a spin control signal Id including each drive signal to be input to the gates of the switching elements Q1 to Q6, and also generates a measurement trigger signal Tr for spin detection to be input to the voltage measurement unit 17, triggered by power-on or reception of the speed command signal Sc.

[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 voltage detection circuit 15, and as a result, the differential voltage detection circuit 15 outputs the differential voltage detection signal Vd.

[0101] As shown in Fig. 9, the motor drive control device 10 passes through the free mode, the charge mode, the discharge 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 power is turned on. Note that, in the timing chart shown in Fig. 9, a case where the motor drive control device 10 goes back to the free mode (free mode (2)) after the discharge mode is taken as an example, but is not limited to this.

[0102] In the free mode, the inverter circuit 2a is put into a first switch state by the idling control signal Id. Specifically, the idling control signal Id generated by the first switching unit 21a sets all the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a to low, turning off all the switches of the inverter circuit. In this state, since no closed circuit is formed, the winding current of the selected phase is 0 A, and no current flows.

[0103] In this state, when the rotor of the motor 3 is rotating idly, an induced electromotive force is generated in the coil of the motor 3, and the phase voltage Vu of the U phase, which is the selected phase voltage signal Vm, oscillates with a positive saddle wave with an amplitude due to the induced voltage according to the idling speed and a period according to the idling speed due to the influence of the clamping of the parasitic diodes when all switching elements Q1 to Q6 are turned off. The positive saddle wave means a waveform with a concave at the apex of a circular arc on the positive side, similar to a full-wave rectified wave. The neutral point voltage Vn, which is the composite of the phase voltages of all phases, oscillates with an amplitude due to the induced voltage according to the idling speed and a positive full-wave rectified wave with a period three times the phase voltage due to all switching elements Q1 to Q6 being turned off. The positive full-wave rectified wave means a full-wave rectified wave with a circular arc apex on the positive side. The differential voltage detection signal Vd' of the selected phase voltage signal Vm and neutral point voltage Vn input to the differential amplifier circuit 153 oscillates as a sine wave with an amplitude due to an induced voltage according to the idling speed and a period according to the idling speed when all switching elements Q1 to Q6 are turned off. At this time, the differential voltage detection signal Vd becomes a signal that is nearly similar to the differential voltage detection signal Vd' and is saturated in the voltage range from 0V to Vdc centered on Vdc / 2 by the differential amplifier circuit 153.

[0104] Next, in the charging mode, the inverter circuit 2a is put into a second switch state by the idling control signal Id. Specifically, the idling control signal Id generated by the second switching unit 21b causes all of the drive signals input to the gates of the switching elements Q2, Q4, and Q6 in the lower arm of the switching elements Q1 to Q6 constituting the inverter circuit 2a to be set to high, thereby turning on all of the low-side switches of the inverter circuit.

[0105] In this state, when the rotor of motor 3 is rotating freely, an induced electromotive force is generated in the coil of motor 3, and as shown in Figure 3, a closed circuit is formed by the coil of motor 3 and switching elements Q2, Q4, and Q6 that are turned on in inverter circuit 2a, generating a current that circulates between the coil of motor 3 and inverter circuit 2a, and the winding current of the selected phase oscillates in a sine wave with an amplitude due to the induced current corresponding to the idling speed and a period corresponding to the idling speed.

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

[0107] Next, in the discharge mode, the inverter circuit 2a is again put into the first switch state by the idling control signal Id. Specifically, the idling control signal Id generated by the first switching unit 21a causes all the drive signals input to the gates of the switching elements Q1 to Q6 constituting the inverter circuit 2a to be low again, turning off all the switches of the inverter circuit.

[0108] In this state, if the rotor of the motor 3 is rotating freely, the current circulating between the coil of the motor 3 and the inverter circuit 2a during the charging mode tends to continue to flow through the coil, causing inductive kickback by turning off all of the switching elements Q1 to Q6.

[0109] In the discharge mode, due to the occurrence of inductive kickback, the phase voltage of the U phase, which is the selected phase voltage signal Vm, drops if it is the most upstream phase of the induced current, rises if it is the most downstream phase of the induced current, and rises or drops depending on the direction of the induced current for the remaining phases. The induced voltage is clamped by a parasitic diode, and the voltage fluctuation time of the most downstream and most upstream phases of the induced current is the longest. The neutral point voltage Vn changes in stages because the voltage fluctuations due to the inductive kickbacks, which differ for each phase, are combined. After that, the effects of inductive kickback are eliminated, and the phase voltage of the U phase, which is the selected phase voltage signal Vm, and the neutral point voltage Vn converge to Vin / 2. Since the motor coil and the inverter circuit do not form a closed circuit due to the discharge mode, the effects of the induced voltage due to the motor running appear at node A of the selected phase voltage signal Vm and node B of the neutral point voltage Vn, and the selected phase voltage signal Vm, neutral point voltage Vn, and differential voltage detection signal Vd' oscillate with waveforms similar to those in free mode (1).

[0110] In discharge mode, when the phase voltage of the U phase, which is the selected phase voltage signal Vm, rises, the differential voltage detection signal Vd' becomes positive, the effects of inductive kickback are eliminated, and the sine wave oscillation caused by the induced voltage starts from a falling waveform that converges to 0 V. When the phase voltage of the U phase, which is the selected phase voltage signal Vm, drops, the differential voltage detection signal Vd' becomes negative, the effects of inductive kickback are eliminated, and the sine wave oscillation caused by the induced voltage starts from a rising waveform that converges to 0 V. The differential voltage detection signal Vd' changes in stages due to voltage fluctuations that differ for each phase, and there are six types of waveform patterns (positive side two steps up and down, positive side one step, positive side two steps down and up, negative side two steps up and down, negative side one step, negative side two steps down and up). At this time, the differential voltage detection signal Vd becomes a signal that is approximately similar to the differential voltage detection signal Vd' and is saturated in the voltage range from 0V to Vdc with Vdc / 2 as the center by the differential amplifier circuit 153.

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

[0112] 10 to 15 are waveforms showing the phase voltage patterns generated in the phase voltage detection circuit due to inductive kickback and the resulting differential voltage patterns in the discharge mode when the rotor of motor 3 is spinning freely. The voltages of these signals fluctuate in the following six patterns depending on the rotor position of motor 3. Note that Figs. 10 to 15 only show the phase voltage of the U phase, which is the selected phase voltage signal Vm, the neutral point voltage Vn, and the differential voltage detection signal Vd', and for simplification, the effect of the induced voltage due to the motor spinning is omitted.

[0113] When the rotor of the motor 3 is stopped (not spinning), no voltage fluctuations due to inductive kickback occur in the discharge mode, and therefore the phase voltages of each phase do not change from 0V, regardless of the position of the rotor of the motor 3. As a result, the phase voltage of the U phase, which is the selected phase voltage signal Vm, and the neutral point voltage Vn are both 0V, and the differential voltage detection signal Vd' is also 0V.

[0114] 10 is a diagram showing a waveform pattern of the first pattern. In this pattern, the U phase is the most downstream side of the induced current, the V phase is the most upstream side of the induced current, and the W phase is the downstream side of the induced current. In this case, the V phase and the W phase may be interchanged.

[0115] In this pattern, in the first half, the U-phase phase voltage Vu, which is the selected phase voltage signal Vm, rises from the DC power supply Vin and the forward voltage Vf of the parasitic diode to Vin+Vf, the V-phase phase voltage Vv drops to -Vf, and the W-phase phase voltage Vw rises to Vin+Vf. The neutral point voltage Vn, which is the composite voltage of these voltages, converges to approximately Vin*2 / 3 (in this specification, "*" represents 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 voltage Vu and the V-phase voltage Vv are maintained, but the W-phase voltage Vw, which has a shorter voltage fluctuation time, drops to approximately Vin / 2. 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 Vin / 2. After that, the effect of 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 of two steps below and above the positive side, i.e., a waveform that takes two positive values ​​and whose values ​​change from a positive low voltage to a positive high voltage.

[0118] 11 is a diagram showing a waveform pattern of the second pattern. In this pattern, the U phase is downstream of the induced current, the V phase is most upstream of the induced current, and the W phase is most downstream of the induced current. In this case, the V phase and the W phase may be interchanged.

[0119] In this pattern, in the first half, the U-phase voltage Vu, which is the selected phase voltage signal Vm, rises to Vin+Vf, the V-phase voltage Vv falls to -Vf, and the W-phase voltage Vw rises to Vin+Vf. 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 latter half, the voltage fluctuations of the V-phase voltage Vv and the W-phase voltage Vw are maintained, but the U-phase voltage Vu, which has a shorter voltage fluctuation time, drops to approximately Vin / 2. 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 with one positive step, that is, a waveform that takes one positive value.

[0122] 12 is a diagram showing a waveform pattern of the third pattern. In this pattern, the U phase is the most downstream side of the induced current, the V phase is the most upstream side of the induced current, and the W phase is the upstream side of the induced current. In this case, the V phase and the W phase may be interchanged.

[0123] In this pattern, in the first half, the U-phase voltage Vu, which is the selected phase voltage signal Vm, rises to Vin+Vf, the V-phase voltage Vv drops to -Vf, and the W-phase voltage Vw drops to -Vf. 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 voltage Vu and the V-phase voltage Vv are maintained, but the W-phase voltage Vw, which has a shorter 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 Vin / 2. After that, the effect of 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, i.e., two positive values, and the values ​​change from a positive high voltage to a positive low voltage.

[0126] 13 is a diagram showing a waveform pattern of the fourth pattern. In this pattern, the U phase is the most upstream side of the induced current, the V phase is the most upstream side of the induced current, and the W phase is the most downstream side of the induced current. In this case, the V phase and the W phase may be interchanged.

[0127] In this pattern, in the first half, the U-phase voltage Vu, which is the selected phase voltage signal Vm, drops to -Vf, the V-phase voltage Vv drops to -Vf, and the W-phase voltage Vw rises to Vin+Vf. 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 / 3.

[0128] In the second half, the voltage fluctuations of the U-phase voltage Vu and the W-phase voltage Vw are maintained, but the V-phase voltage Vv, which has a shorter voltage fluctuation time, rises to approximately Vin / 2. 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 -Vin / 2. After that, the effect 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 of two steps below the negative side, i.e., two negative values, and the values ​​change from a negative low voltage to a negative high voltage.

[0130] 14 is a diagram showing a waveform pattern of the fifth pattern. In this pattern, the U phase is the upstream side of the induced current, the V phase is the most upstream side of the induced current, and the W phase is the most downstream side of the induced current. In this case, the V phase and the W phase may be interchanged.

[0131] In this pattern, in the first half, the U-phase voltage Vu, which is the selected phase voltage signal Vm, drops to -Vf, the V-phase voltage Vv drops to -Vf, and the W-phase voltage Vw rises to Vin+Vf. 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 / 3.

[0132] In the latter half, the voltage fluctuations of the V-phase voltage Vv and the W-phase voltage Vw are maintained, but the U-phase voltage Vu, which has a shorter voltage fluctuation time, rises to approximately Vin / 2. 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 with one negative step, that is, a waveform that takes one negative value.

[0134] 15 is a diagram showing a waveform pattern of the sixth pattern. In this pattern, the U phase is the most upstream side of the induced current, the V phase is the most downstream side of the induced current, and the W phase is the most downstream side of the induced current. In this case, the V phase and the W phase may be interchanged.

[0135] In this pattern, in the first half, the U-phase voltage Vu, which is the selected phase voltage signal Vm, drops to -Vf, the V-phase voltage Vv rises to Vin+Vf, and the W-phase voltage Vw rises to Vin+Vf. 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 voltage Vu and the W-phase voltage Vw are maintained, but the V-phase voltage Vv, which has a short voltage fluctuation time, drops to approximately Vin / 2. 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 Vin / 2. After that, the effect of 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 waveform pattern with two negative steps above and below, i.e., two negative values, and the values ​​change from a negative high voltage to a negative low voltage.

[0138] As can be seen from Figures 10 to 15, by using at least one phase's phase voltage and neutral point voltage, it is possible to detect whether the motor is in an idling state from voltage fluctuations. At this time, the phase voltage may be close to 0V, but by using the phase voltage and neutral point voltage simultaneously, it becomes possible to confirm voltage fluctuations of ±Vin / 3 or more, making it possible to more stably detect whether the motor is in an idling state. By directly measuring the phase voltage and neutral point voltage without using a differential voltage detection circuit, it is possible to determine whether the motor is in an idling state using a threshold value, but by generating a differential voltage for the phase voltage and neutral point voltage using a differential amplifier circuit and shifting the differential voltage, it becomes possible to treat the voltage fluctuation as a positive voltage, making it easier to determine whether the motor is in an idling state using a threshold value.

[0139] Returning to FIG. 9, after the discharge mode, the free mode can be entered again. In the free mode after the discharge mode, the inverter circuit 2a is put into the first switch state by the idling control signal Id. Specifically, the idling control signal Id generated by the first switching unit 21a makes all the drive signals input to the gates of the switching elements Q1 to Q6 that make up the inverter circuit 2a low, turning off all the switches of the inverter circuit. In this state, since no closed circuit is formed, the winding current of the selected phase is 0 A, 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, oscillates with a positive saddle wave with an amplitude due to the induced voltage corresponding to the idling speed and clamping of the parasitic diode and a period corresponding to the idling speed, while the voltage fluctuation due to the inductive kickback converges as all switching elements Q1 to Q6 are turned off. The neutral point voltage Vn oscillates with a positive full-wave rectified wave with an amplitude due to the induced voltage corresponding to the idling speed and clamping of the parasitic diode and a period three times that of the phase voltage, while the voltage fluctuation due to the inductive kickback converges as all switching elements Q1 to Q6 are turned off. The differential voltage detection signal Vd' oscillates with an amplitude due to the induced voltage corresponding to the idling speed and a sine wave with a period corresponding to the idling speed as all switching elements Q1 to Q6 are turned off.

[0141] The idling determination unit 22 receives the voltage measurement value Vmeas corresponding to the above-mentioned differential voltage detection signal Vd from the voltage measurement unit 17. As described above, the differential voltage detection signal Vd changes in various ways even during the discharge mode, so the idling determination unit 22 measures the differential voltage detection signal Vd multiple times during the discharge mode, and performs idling determination based on the differential voltage detection signal Vd when the voltage fluctuation is maximum compared to the voltage during the charge mode.

[0142] The idling determination unit 22 repeats the measurement of the differential voltage detection signal Vd multiple times at a predetermined interval during a predetermined discharge time, starting from the lapse of a predetermined mask time. Since the voltage fluctuation due to the inductive kickback caused by the idling of the motor changes stepwise, it is preferable to measure the differential voltage detection signal Vd multiple times rather than once. For example, the differential voltage detection signal Vd measured in advance in the charging mode is used as a reference voltage, and among the multiple measurement voltages measured in the discharging mode, a maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage is maximum is calculated, and the calculated maximum fluctuation voltage difference is compared with a preset idling threshold value to determine idling. When the maximum fluctuation voltage difference exceeds a predetermined idling threshold value, the idling determination unit 22 can determine that the motor 3 is in an idling state. The idling threshold value may be a value that can determine the maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage of the differential voltage detection signal Vd is maximum at the minimum idling rotation speed for idling detection. The differential amplifier circuit 153 may adjust the amplification (reduction) rate of the differential voltage detection signal Vd' within a range in which the idling threshold value can be determined.

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

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

[0145] First, when power is applied to the motor drive control device 10, as shown in FIG. 16, the state control unit 12 determines to switch to the free mode (step S111), and the first switching unit 21a generates an idling control signal Id that switches the switching elements Q1 to Q6 that constitute the inverter circuit 2a to a first switch state (all switching elements Q1 to Q6 off) in order to set the switching state corresponding to the free mode (step S112).

[0146] 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 a first switch state in accordance with the idling control signal Id generated in step S112. In response to this idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are set to the first switch state shown in FIG.

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

[0148] 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 switch state in accordance with the idling control signal Id generated in step S114. In response to this idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are switched to the second switch state in which no phase voltage is generated as shown in FIG.

[0149] After step S114, the control circuit 1 executes measurement selection (step S200). For example, when detecting slippage using the U-phase voltage Vu, the control circuit 1 selects the selection phase voltage signal Vm as the measurement type selection signal Ss and selects the U-phase voltage Vu as the measurement phase selection signal Sm.

[0150] FIG. 17 is a flowchart showing an example of the flow of measurement selection by 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] 17, when measurement selection is started, first, in the voltage measurement unit 17, it is determined whether or not the measurement type selection signal Ss selects the shunt current measurement (step S201). Note that the measurement type selection signal Ss selects the shunt current detection signal Vs for overcurrent detection in driving the motor.

[0152] If the measurement type selection signal Ss selects shunt current measurement (step S201: YES), the measurement type selection multiplexer 171 of the voltage measurement unit 17 selects the shunt current detection signal Vs for input to the sampling circuit 172 (step S202), and the measurement selection is completed.

[0153] If 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] If 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 as the selection phase voltage signal Vm (step S204).

[0155] If 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] If 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 as the selection phase voltage signal Vm (step S206).

[0157] If 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 as the selection phase voltage signal Vm (step S207).

[0158] After steps S204, S206, and S207, the measurement type selection multiplexer 171 of the voltage measurement unit 17 selects the differential voltage detection signal Vd for input to the sampling circuit 172 (step S208), and the measurement selection ends.

[0159] Returning to FIG. 16, after step S200, the control circuit 1 performs ADC offset measurement (step S300).

[0160] 18 is a flowchart showing an example of the flow of ADC offset measurement by the control circuit 1 of the motor drive control device 10. By performing 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] When ADC offset measurement is started in voltage measurement unit 17, as shown in FIG. 18, first, a counter for the number of ADC offset measurements is cleared, the ADC offset adjustment value is reset to zero, and offset calculator 175 is disabled (step S301).

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

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

[0164] In the voltage measuring unit 17, the counter for the number of ADC offset measurements is checked to determine whether the current number of ADC offset measurements exceeds a predetermined number of ADC offset measurements (step S304).

[0165] If the current ADC offset measurement count does not exceed the predetermined 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 predetermined ADC offset measurement count (step S304: YES), the average value of the values ​​acquired in the measurement in step S302 is acquired as the ADC offset adjustment value, and offset calculator 175 is enabled (step S305).

[0166] By the above-mentioned measurement selection in step S200 and ADC offset measurement in step S300, for example, when the phase voltage Vu of the U phase is used to detect slippage, 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 W phase is used to detect slippage, or the offset adjustment when the shunt current detection signal Vs is selected by the measurement type selection signal Ss may be performed. In addition, the average value of the ADC offset adjustment values ​​of the phase voltages may be used as the offset adjustment value of the phase voltage.

[0167] Returning to FIG. 16, when the state control unit 12 again determines to switch to the free mode (step S115), upon completion of the ADC offset measurement, the first switching unit 21a again generates an idling control signal Id for switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switch state (all switching elements Q1 to Q6 off) in order to set the switching elements Q1 to Q6 constituting the inverter circuit 2a to a switch state corresponding to the free mode (step S116).

[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 switch state in accordance with the idling control signal Id generated in step S116. In response to this idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are set to the first switch state as shown in FIG.

[0169] Thereafter, in order to wait for the motor to start driving after power-on or after the motor has stopped, the state control unit 12 judges whether or not the drive command acquisition unit 11 has received a speed command signal Sc (step S120). The state control unit 12 repeats the judgment until the drive command acquisition unit 11 receives a speed command signal Sc. When the motor is stopped, similarly to when the power is turned on, the state control unit 12 transitions to the free mode before step S120 (step S115), and for example, when the U-phase phase voltage Vu is used to detect slippage, the selected phase voltage signal Vm may be selected for the measurement type selection signal Ss, and the U-phase phase voltage Vu may be selected for the measurement phase selection signal Sm.

[0170] At the timing when the drive command acquisition unit 11 receives the speed command signal Sc from the upper device (step S120: YES), the state control unit 12 executes idling detection to detect the presence or absence of an idling state immediately before driving the motor (step S400).

[0171] 19 is a flowchart showing an example of a flow of slip detection by the control circuit 1 of the motor drive control device 10. Here, an example will be described in which slip detection is performed using the phase voltage Vu of the U phase, for example.

[0172] When the spin detection of S400 starts, since the switch state is already the first switch state corresponding to the free mode, the mode transitions to the charge mode. Therefore, in the state control unit 12, the second switching unit 21b first generates a spin control signal Id for switching to the second switch state corresponding to the charge mode, as shown in FIG. 19 (step S410).

[0173] When the charging mode is entered, the measurement selection in FIG. 17 is executed to select the phase to be measured (step S411). In this example, since the phase voltage Vu of the U phase is used to detect slippage, the state control unit 12 selects the differential voltage detection signal Vd with the measurement type selection signal Ss and selects the phase voltage Vu of the U phase with the measurement phase selection signal Sm. In FIG. 16, 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 when driving the motor, the measurement selection in FIG. 17 can be executed again at this timing.

[0174] Furthermore, after the phase to be measured is selected in step S411, the charging time is reset in 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 switch state in accordance with the idling control signal Id generated in step S410. In response to this idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are switched to the second switch state, for example, as shown in FIG.

[0176] In the state control unit 12, the second switching unit 21b determines whether or not a predetermined charging time has elapsed since the generation of the idling control signal Id in step S410 (step S413).

[0177] In the state control unit 12, when a predetermined charging time has elapsed since generating the idling control signal Id (step S413: Yes), the second switching unit 21b generates a measurement trigger signal Tr (step S414) to cause the voltage measurement unit 17 to measure the measured voltage value Vmeas as a state in which no phase voltage is generated, and causes the voltage measurement unit 17 to measure the measured voltage value Vmeas (ADC voltage measurement). The idling determination unit 22 sets the measured voltage value Vmeas obtained in step S414 as a reference voltage.

[0178] Since the state control unit 12 subsequently transitions to the discharge mode, the first switching unit 21a in the state control unit 12 generates an idling control signal Id for switching to the first switch state corresponding to the discharge mode (step S420). At this time, the discharge time and the mask time are reset in the state control unit 12 (step S421).

[0179] The state control unit 12 generates the idling control signal Id in step S420, thereby switching the switching elements Q1 to Q6 constituting the inverter circuit 2a to the first switch state. That is, in response to this idling control signal Id, the switching elements Q1 to Q6 constituting the inverter circuit 2a are again put into the first switch state, for example, as shown in Fig. 4. At this time, if the motor is idling, inductive kickback occurs in the inverter circuit.

[0180] The state control unit 12 judges whether the mask time has elapsed (step S422). When the mask time has elapsed (step S422: Yes), the state control unit 12 generates a measurement trigger signal Tr to make the voltage measurement unit 17 measure the voltage measurement value Vmeas (ADC voltage measurement) in order to make the voltage measurement unit 17 measure the voltage measurement value Vmeas because voltage fluctuations occur due to inductive kickback when the motor is idling (step S423). The idling judgment unit 22 sets the voltage measurement value Vmeas obtained in step S423 as the measurement voltage.

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

[0182] In the state control unit 12, the idling determination unit 22 determines whether or not the difference (differential voltage detection signal Vd) between the reference voltage obtained in step S413 and the measured voltage obtained in step S423 is greater than the maximum fluctuation voltage difference (step S424). If it is determined in step S424 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 current difference value (step S425). In step S425, the difference between the reference voltage obtained in step S413 and the measured voltage obtained in step S423 is treated as the maximum fluctuation voltage difference as is, and is updated thereafter.

[0183] The state control unit 12 judges whether or not the discharge time has elapsed (step S426). When the discharge time has elapsed (step S426: Yes), the state control unit 12 goes into the free mode (step S430). On the other hand, when the discharge time has not elapsed (step S426: No), the state control unit 12 executes the ADC voltage measurement again (steps S423 to S425). As shown in FIG. 9, after the mask time of step S422 has elapsed, 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 or not 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 a idling threshold value to determine whether or not the motor 3 is idling.

[0185] When the maximum fluctuation voltage difference exceeds the threshold value (step S431: YES), the idling determination unit 22 determines that the motor 3 is in an 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] 16, the state control unit 12 determines whether the motor 3 is determined to be in a state of free spin from the generated spin determination signal (step S130), and if it is determined to be in a state of free spin (step S130: YES), it drives the motor by sensorless driving. On the other hand, if it is determined not to be a state of free spin (step S130: NO), it drives the motor by braking, excitation, forced commutation start, etc.

[0188] As described above, the control circuit 1 of the motor drive control device 10 according to the embodiment switches the switch states of the switching elements Q1 to Q6 of the inverter circuit 2a to generate an induced current circulating between the coil of the motor 3 and the inverter circuit 2a when the rotor of the motor 3 is spinning freely, and then determines that the motor 3 is spinning freely based on the phase voltage generated by inductive kickback that occurs in the inverter circuit when the path of the induced current is interrupted.

[0189] This allows the motor drive control device 10 to stably detect whether the motor 3 is in an idling state in a short period of time without using a position sensor.

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

[0191] According to this, it is possible to detect whether or not the motor 3 is in an idling state by switching each switching element Q1 to Q6 of the inverter circuit 2a to a switch state corresponding to three modes (free mode, charge mode, discharge mode) for detecting idling of the motor 3.

[0192] Furthermore, in the motor drive control device 10 according to the above embodiment, the control circuit 1 has a differential voltage detection circuit 15 that detects as a differential voltage detection signal Vd the difference voltage between the phase voltage of one phase selected in the phase voltage detection circuit and a neutral point voltage Vn which is a combination of the phase voltages of all the phases in the phase voltage detection circuit, and the idling determination unit 22 determines whether the motor 3 is idling based on the differential voltage detection signal Vd.

[0193] According to this, using the neutral point voltage Vn synthesized from the phase voltages, it is possible to determine whether the motor 3 is spinning freely based on the difference voltage between the phase voltage of one selected phase and the neutral point voltage Vn synthesized from the phase voltages of all phases.

[0194] Furthermore, in the motor drive control device 10 according to the above 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 a reference voltage.

[0195] According to this, in the second switch state, since no induced voltage is generated in the phase voltage detection circuit, the idling determination unit 22 can use the differential voltage detection signal Vd detected in the differential voltage detection circuit 15 as the reference voltage for idling determination.

[0196] Furthermore, in the motor drive control device 10 according to the above 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 a measurement voltage, and a maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage is maximum is calculated, and if the calculated maximum fluctuation voltage difference is larger than a threshold value, it is determined that the motor 3 is in an idling state.

[0197] According to this, in the discharge mode, the phase voltage fluctuates due to inductive kickback, making it possible to stably perform the slip determination.

[0198] <<Extension of the embodiment>> The invention made by the inventor has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

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

[0200] In the embodiment, the motor drive control device 10 is described based on an example in which a position sensor is not used, but a position sensor may be provided. Even in this case, the position sensor is used when driving the motor, and does not need to be used when detecting idling. As the position sensor, a Hall element that outputs a Hall signal may be used, or instead of such a Hall signal, another signal corresponding to the rotor position of the motor 3 may be input as a rotor position detection signal. For example, an encoder, a resolver, or the like may be provided, and the detection signal may be input to the control circuit 1. As the measurement circuit for each phase voltage, an A / D converter or a signal from a comparator that compares each phase voltage with the neutral point voltage may be input as a rotor position detection signal.

[0201] In the embodiment, the motor drive control device 10 is described with an example of a configuration capable of detecting overcurrent by the current detection circuit 2c, but if overcurrent detection is not performed, the current detection circuit 2c does not need to 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 be omitted.

[0202] In the embodiment, the control circuit 1 is not limited to the above-mentioned circuit configuration. The control circuit 1 can be configured in various ways to achieve the object of the present invention.

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

[0204] In the embodiment, the charging mode and the discharging mode may be periodically repeated to detect whether the motor is in an idling state and wait for the motor to stop.

[0205] Furthermore, in the embodiments, the driving of the motor is not limited to 120-degree energization rectangular wave driving, but 150-degree energization rectangular wave driving or sine wave driving may 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.

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

[0208] In the ADC offset measurement in step S300 of the above-described flowchart, the end of the ADC voltage measurement count is determined by determining whether or not the ADC offset measurement count in step S304 has been exceeded. Alternatively, however, it may be determined by determining whether or not the measurement time has been exceeded.

[0209] In the idling detection in step S400 of the above-described flowchart, the end of the ADC voltage measurement count is determined by determining whether or not the discharge time in step S426 has been exceeded. Alternatively, however, it may be determined by determining whether or not the measurement count has been exceeded. [Explanation of symbols]

[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 command acquisition unit, 12... state control unit, 13... rectangular wave control unit, 14... PWM signal generation unit, 15... differential voltage detection circuit, 16... voltage judgment unit, 17... voltage measurement unit, 21a... first switching unit, 21b... second switching unit, 22... idling judgment unit, 151... multiple resistance elements for DC current limiting and voltage adjustment, 152... multiplexer for selecting measurement phase, 153... differential amplifier circuit, 161... D / A converter for comparator, 162... comparator, 171... multiplexer for selecting measurement type, 172... sampling circuit, 173... D / A converter for A / D converter, 174... comparator, 175...Offset calculator, 100...Motor unit, Q1~Q6...Switching element, Rs...Shunt resistor, Sc...Speed ​​command signal, Sd...Drive control signal, Id...Idle control signal, ωref...Target rotation speed, So...Drive command signal, Sm...Measurement phase selection signal, Ss...Measurement type selection signal, Tr...Measurement trigger signal, Vjudge...Voltage judgment signal, Vmeas...Measured voltage, Vd, Vd'...Differential voltage detection signal, Vm...Selected phase voltage signal, Vn...Neutral point voltage (composite 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 control circuit that generates a drive control signal for driving a motor having at least one phase coil; a drive circuit including an inverter circuit including high-side switches and low-side switches connected in series to each other and provided corresponding to the coils of each phase of the motor, the drive circuit alternately turning on and off the high-side switches and the low-side switches in response to the drive control signal to switch the current flow direction of the coils of the corresponding phase, thereby rotating the rotor of the motor; a phase voltage detection circuit for detecting a phase voltage generated between the inverter circuit and a coil of each phase of the motor, The control circuit includes: a free-spin control signal is generated in place of the drive control signal, and a switch state of the inverter circuit is switched to generate an induced current circulating between the coil of the motor and the inverter circuit when the rotor of the motor is free-spinning, and then, when the path of the induced current is interrupted, an inductive kickback occurs in the inverter circuit, and it is determined that the motor is free-spinning based on a phase voltage generated in the phase voltage detection circuit. Motor drive control device.

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

3. 3. The motor drive control device according to claim 2, the control circuit has a differential voltage detection circuit that detects, as a differential voltage detection signal, a difference voltage between a phase voltage of one phase selected in the phase voltage detection circuit and a neutral point voltage obtained by combining the phase voltages of all phases in the phase voltage detection circuit; the idling determination unit determines whether the motor is idling based on the differential voltage detection signal. Motor drive control device.

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

5. 5. The motor drive control device according to claim 4, when switching from the second switch state to the first switch state, the differential voltage detection signal detected a plurality of times by the differential voltage detection circuit is used as a measurement voltage, a maximum fluctuation voltage difference at which the difference between the reference voltage and the measurement voltage is maximum is calculated, and if the calculated maximum fluctuation voltage difference is larger than a threshold value, it is determined that the motor is in an idling state. Motor drive control device.

6. A method for detecting idling of a motor, the method being executed in a motor drive control device comprising: a control circuit that generates 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 to each other and provided corresponding to the coil of each phase of the motor, the drive circuit alternately turning on and off the high-side switch and the low-side switch in response to the drive control signal to switch a current direction of the coil of the corresponding phase, thereby rotating a rotor of the motor; and a phase voltage detection circuit that detects a phase voltage generated between the inverter circuit and the coil of each phase of the motor, a first step of switching from a first switch state in which all of the high-side switches and the low-side switches included in the inverter circuit are turned off to a second switch state in which all of the high-side switches or the low-side switches included in the inverter circuit are turned on; a second step of switching from the second switch state to the first switch state; and a third step of determining, when the switch state is switched to the first switch state, that the motor is rotating freely based on the phase voltage. How to detect idling of a motor.

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