Motor drive control device

Abstract

This invention provides a motor drive control device that can appropriately drive and control a motor with a simplified configuration that omits a sensor for detecting the rotational position of the motor. [Solution] In the motor drive control device 100, the control unit 132 drives the motor 110, which has a first coil corresponding to the first phase (U phase, V phase, W phase), a second coil corresponding to the second phase (V phase, W phase, U phase), and a third coil corresponding to the third phase (W phase, U phase, V phase), by switching between a first state in which only the first phase is turned off, a second state in which only the second phase is turned off, and a third state in which only the third phase is turned off. At the same time, the control unit 132 measures the voltage of the first phase at a timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears, and obtains a measured voltage. The larger the absolute value of this measured voltage, the earlier the timing of switching from the first state to the second state is advanced.

Description

Technical Field

[0001] The present invention relates to a motor drive control device.

Background Art

[0002] In recent years, in vehicles such as automobiles, a three-phase alternator including a rotor having a field flux generating magnet connected to a crankshaft (crankshaft) of an internal combustion engine and driven along with its rotation, and a stator around which a stator winding for generating power output is wound, is used as a starting motor of the internal combustion engine, and is controlled to charge a secondary battery such as a lead battery mounted on the vehicle, and at the same time, by rotating the crankshaft of the internal combustion engine, a motor drive control device for controlling its starting has been proposed.

[0003] Under such circumstances, Patent Document 1 relates to a motor drive circuit. When driving a sensorless brushless motor, a current slope generator 2 that forms the rising and falling slopes of each phase of the motor current using the voltage slope generated by charging a capacitor during energization switching, a detection prohibition interval signal generator 1 that masks spike noise generated along with energization switching using the discharge time of the capacitor, and a zero-cross detection window generator 3 that detects the zero-cross point of the induced electromotive voltage of each phase of the motor coil and generates a zero-cross pulse indicating the position of each rising zero-cross point and falling zero-cross point of each phase, and discloses a configuration in which the magnitude of the discharge current of the capacitor that determines the detection prohibition interval is made variable according to the magnitude of the motor current command when enabling zero-cross detection after the detection prohibition interval.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, according to the inventor's research, the configuration disclosed in Patent Document 1 attempts to mask the spike noise generated during the power switching of a sensorless motor, which omits a sensor for detecting the motor's rotational position, using a detection prohibition section signal corresponding to the motor coil current. However, since it only detects the zero-crossing point of the induced electromotive force, it requires additional components such as a capacitor to absorb the energy generated when switching the energized state of one phase of the current supplied to the motor to a non-energetic state, making the configuration complicated. In other words, currently, there is a strong demand for a novel configuration that can appropriately control the operation of the motor while suppressing the effects of the back electromotive force (flyback voltage) generated when switching the energized state of one phase of the current supplied to the motor to a non-energetic state with a simplified configuration.

[0006] The present invention was made after the above considerations, and aims to provide a motor drive control device that can appropriately drive and control the operation of a motor with a simplified configuration that omits a sensor for detecting the rotational position of the motor. [Means for solving the problem]

[0007] To achieve the above objectives, the present invention provides a motor drive control device having a control unit that drives a motor having a first coil corresponding to a first phase, a second coil corresponding to a second phase, and a third coil corresponding to a third phase, while switching between a first state in which only the first phase is turned off, a second state in which only the second phase is turned off, and a third state in which only the third phase is turned off, wherein the control unit measures the voltage of the first phase at a timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears, and obtains a measured voltage, and the larger the absolute value of the measured voltage, the earlier the timing of switching from the first state to the second state is advanced, thereby switching from the first state to the second state. [Effects of the Invention]

[0008] The motor drive control device according to the first aspect of the present invention described above has a motor having a first coil corresponding to the first phase, a second coil corresponding to the second phase, and a third coil corresponding to the third phase, and has a control unit that drives the motor while switching between a first state in which only the first phase is turned off, a second state in which only the second phase is turned off, and a third state in which only the third phase is turned off. The control unit measures the voltage of the first phase at a timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears, and obtains a measured voltage. The larger the absolute value of the measured voltage, the earlier the timing of switching from the first state to the second state is advanced. As a result, with a simplified configuration that omits a sensor for detecting the rotational position of the motor, the voltage of the unpowered phase (induced electromotive force) can be measured and the operation of the motor can be appropriately driven and controlled while suppressing the influence of the back electromotive force (flyback voltage) generated when switching the powered state of one phase of the current supplied to the motor to an unpowered state. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing a motor drive control device in an embodiment of the present invention, together with an internal combustion engine, an engine control device, and a three-phase AC generator motor. [Figure 2] Figure 2 is a schematic diagram showing the circuit configuration and functional blocks of the motor drive control device in this embodiment, along with the engine control device and motor. [Figure 3] Figure 3 is a flowchart showing an example of the operation of the motor drive control device in this embodiment. [Figure 4] Figure 4 is a time chart showing an example of the operation of the motor drive control device in this embodiment. [Modes for carrying out the invention]

[0010] Hereinafter, with due reference to the drawings, the motor drive control device according to an embodiment of the present invention will be described in detail.

[0011] [Engine configuration] First, with reference to Figure 1, the configuration of the engine, which is the controlled object of the engine control device in which the motor drive control device cooperates in this embodiment, will be described in detail.

[0012] Figure 1 is a schematic diagram showing the motor drive control device in this embodiment together with the engine, engine control device, and motor.

[0013] As shown in Figure 1, the engine 1, which is an internal combustion engine, is typically mounted on a vehicle such as a motorcycle (not shown), has a four-stroke cycle, and its operation is controlled by an engine control device 50. It is equipped with a cylinder block 2. Cooling water passages 3 are formed within the side walls of the cylinder block 2, through which cooling water flows to cool the cylinder block 2 and its interior. A water temperature sensor 4 is provided in the cooling water passages 3 to detect the temperature of the cooling water flowing through them.

[0014] For the sake of explanation, the engine 1 is shown as a single-cylinder engine in the diagram, but the engine 1 may have multiple cylinders, and the cylinder arrangement may be in line, horizontally opposed, V-type, etc. Also, for the sake of explanation, the engine 1 is shown as water-cooled in the diagram, but it may be air-cooled, in which case a temperature sensor capable of detecting the temperature of the engine 1 may be mounted on the cylinder block 2, etc., instead of the water temperature sensor 4.

[0015] A piston 5 is located inside the cylinder block 2. The piston 5 is connected to a crankshaft 7, which has a rotation axis, via a connecting rod 6. A recurctor 70 is mounted on the crankshaft 7 coaxially with its rotation axis. Multiple teeth 72 are arranged continuously at basically constant intervals on the outer circumference of the recurctor 70, but in some predetermined sections there are toothless sections 73 where the teeth 72 are absent. A crank angle sensor 8 is provided near the recurctor 70 to detect the rotation angle (rotation position) of the crankshaft 7 around its rotation axis, in order to calculate the rotational speed of the engine 1, etc. A cylinder head 9 is mounted on the top of the cylinder block 2. The internal space defined by the top surface of the piston 5 and the inner surfaces of the cylinder block 2 and cylinder head 9 respectively becomes the combustion chamber 10.

[0016] The cylinder head 9 is provided with a spark plug 11 that ignites the air-fuel mixture in the combustion chamber 10. The ignition operation of the spark plug 11 is controlled by the engine control device 50, which controls the energization state of the ignition coil (not shown in the figure).

[0017] Furthermore, the cylinder head 9 is provided with an intake valve 13 that can open and close to connect the combustion chamber 10 and the intake passage 12. The intake passage 12 is formed in an intake manifold IM mounted on the cylinder head 9, and the intake manifold IM includes a fuel injector 14 that injects fuel into the intake passage 12 and a throttle valve 15 positioned upstream of the fuel injector 14. A throttle opening sensor 106 is provided for the throttle valve 15 to detect its opening degree. In addition, an intake pressure sensor 107 is provided for the fuel injector 14 and the intake passage 12 between the fuel injector 14 to detect the intake pressure of the engine 1. The fuel injection operation (valve opening operation) of the fuel injector 14 is controlled by the energization state of its solenoid valve (not shown) being controlled by the engine control device 50. The fuel injector 14 may also inject fuel directly into the combustion chamber 10. Alternatively, the rotational position of the intake cam of the mechanism that opens and closes the intake valve 13 may be used as the rotational position corresponding to the rotational position of the crankshaft 7.

[0018] An exhaust pipe EM is attached to the cylinder head 9 on the side opposite to the intake pipe IM, and an exhaust passage 16 communicating with the combustion chamber 10 is formed in the exhaust pipe EM. An exhaust valve 17 that opens and closes the combustion chamber 10 and the exhaust passage 16 is provided in the cylinder head 9. Note that the rotational position of the exhaust cam of the mechanism that opens and closes the exhaust valve 17 may be adopted as the rotational position corresponding to the rotational position of the crankshaft 7.

[0019] 〔Configuration and Operation of Control Device〕 Next, referring further to FIGS. 2 to 4, the configurations of the engine control device and the motor drive control device in the present embodiment will be described in detail together with their operations.

[0020] FIG. 2 is a schematic diagram showing the circuit configuration and functional blocks of the motor drive control device in the present embodiment together with the engine control device and the motor. FIG. 3 is a flowchart showing an example of the operation of the motor drive control device in the present embodiment. FIG. 4 is a time chart showing an example of the operation of the motor drive control device in the present embodiment. From top to bottom, it shows the change over time of the energization state of the U-phase of the current supplied to the motor, the change over time of the energization state of the V-phase of the current supplied to the motor, and the change over time of the energization state of the W-phase of the current supplied to the motor, respectively. In FIG. 4, each waveform is shown schematically, and the back electromotive voltage (flyback voltage) and the induced electromotive voltage when there is no back electromotive voltage are also superimposed on the change over time of the energization state of each phase of the current supplied to the motor. Also, FIG. 4 shows the case where the motor operates with so-called 120-degree energization, but the same change over time can be exhibited as long as the motor operates including a non-energized (off) state other than 120-degree energization.

[0021] As shown in FIG. 2, the engine control device 50 is activated when the status switch 105 is turned on and controls the operation of the engine 1. Based on output signals sent from the crank angle sensor 8, water temperature sensor 4, throttle opening sensor 106, intake pressure sensor 107, etc., it mainly controls the energization state of an ignition coil (not shown) to control the ignition operation of the spark plug 11, and controls the energization state of the fuel injection valve 14 to control the fuel injection operation (valve opening operation) of the fuel injection valve 14. It includes an engine ECU (Electronic Control Unit) 60. The engine ECU 60 is an arithmetic processing device including a microcomputer, etc., and has a memory and a timer (not shown). Such a memory stores necessary control and processing programs and control and processing data. The engine ECU 60 reads out the necessary control and processing programs and control and processing data from the memory and executes the control and processing programs to control the operations of the spark plug 11, fuel injection valve 14, etc.

[0022] In addition, based on the output signal sent from the crank angle sensor 8, the engine ECU 60 calculates the rotational speed of the engine 1. When the voltage value of the output signal sent from the crank angle sensor 8 becomes equal to or higher than a predetermined threshold value, it determines that the tooth portion 72 of the reluctor 70 has passed near the crank angle sensor 8, and may send an output signal indicating that the tooth portion 72 has passed near the crank angle sensor 8 to the motor drive control device 100.

[0023] Furthermore, the motor drive control device 100 includes a motor ECU 130 for controlling the operation of the motor 110, which is a three-phase AC generator motor. Specifically, the motor ECU 130 is activated when the starter switch 105 is turned ON, and charges the lead-acid battery 101, which is a secondary battery, by generating power with the motor 110. At the same time, it uses the motor 110 as a starter motor to rotate the crankshaft 7 of the engine 1, thereby starting the engine 1 in cooperation with the engine ECU 60 as needed. In addition to lead-acid batteries, nickel-metal hydride batteries and lithium-ion batteries can also be used as secondary batteries. Also, in the figure, reference numeral 102 indicates a load connected to the lead-acid battery 101. Note that the engine control device 50 and the motor drive control device 100 may not be separate units but may constitute a single drive control device that is integrated as a single unit.

[0024] Although the detailed configuration of the motor 110 is omitted, it is typically controlled by PWM (Pulse Width Modulation) and comprises a stator around which three-phase power generation coils (stator windings) consisting of a U-phase coil 110a, a V-phase coil 110b, and a W-phase coil 110c are wound, and a rotor which is mounted on the outer circumference of the stator and has permanent magnets for generating field flux corresponding to each of these phase coils 110a, 110b, and 110c attached to it. This rotor is mechanically connected to the crankshaft 7 of the engine 1 via a reduction gear system (not shown). Therefore, via this gear system, there is a one-to-one correspondence between the rotational position of the motor 110, that is, the rotational position of the rotor (rotational position around the rotation axis 112 schematically shown in Figure 1), and the rotational position of the engine 1, that is, the rotational position of the crankshaft 7.

[0025] The U-phase coil 110a has a connection terminal 111a that electrically connects to the other terminal of one U-phase switching element 131a of the AC / DC converter 131 and to one terminal of the other U-phase switching element 131b of the AC / DC converter 131. The V-phase coil 110b has a connection terminal 111b that electrically connects to the other terminal of one V-phase switching element 131c of the AC / DC converter 131 and to one terminal of the other V-phase switching element 131d of the AC / DC converter 131. The W-phase coil 110c has a connection terminal 111c that electrically connects to the other terminal of one W-phase switching element 131e of the AC / DC converter 131 and to one terminal of the other W-phase switching element 131f of the AC / DC converter 131.

[0026] The motor ECU 130 is a processing unit including a microcomputer, and has memory and timers (not shown in the diagram). The memory stores the necessary control and processing programs and control and processing data, and the motor ECU 130 reads the necessary control and processing programs and data from the memory and executes the control and processing programs to control the operation of the motor 110, which is a generator motor.

[0027] Specifically, the motor ECU 130 includes an AC (Alternate Current) / DC (Direct Current) converter 131, which is a power converter, and a control unit 132 that sends control signals to the AC / DC converter 131 to control its operation, drives the engine 1 to start the engine 1, and controls the motor 110 to generate power driven by the engine 1. The control unit 132 includes a voltage measurement timer 132a that measures the voltage (induced electromotive force) of the unpowered phase when switching the energized state of one phase of the current supplied to the motor 110 to unpowered, and an energization timer 132b that measures the length of time until the end of the unpowered phase period according to the measured voltage of the unpowered phase. Furthermore, the motor ECU 130 includes a voltage receiving circuit 133 that receives the voltage between the other terminal of the U-phase switching element 131a and one terminal of the U-phase switching element 131b and the connection terminal 111a of the U-phase coil 110a, the voltage between the other terminal of the V-phase switching element 131c and one terminal of the V-phase switching element 131d and the connection terminal 111b of the V-phase coil 110b, and the voltage between the other terminal of the V-phase switching element 131c and one terminal of the V-phase switching element 131d and the connection terminal 111b of the V-phase coil 110b. Based on the voltage values ​​received by the voltage receiving circuit 133, the motor ECU 130 can detect the energized state of the U-phase, V-phase, and W-phase of the current supplied to the motor 110. In the diagram, the control unit 132, voltage measurement timer 132a, and power supply timer 132b are shown as functional blocks used when executing the control program.

[0028] The AC / DC converter 131 typically has three-phase bridged switching elements 131a, 131b, 131c, 131d, 131e, and 131f, and converts the three-phase AC current supplied from the motor 110 into DC current by turning each of the switching elements 131a, 131b, 131c, 131d, 131e, and 131f on or off according to a control signal from the control unit 132, and also supplies the DC current to the lead-acid battery 101. In this case, the motor 110 is driven by the engine 1 and functions as a generator that is so-called retarded by the control unit 132 via the AC / DC converter 131. Furthermore, the AC / DC converter 131 converts the DC current supplied from the lead-acid battery 101 into a three-phase AC current by turning on or off each of the switching elements 131a, 131b, 131c, 131d, 131e, and 131f according to the control signal from the control unit 132, and supplies this three-phase AC current to the motor 110. In this case, the AC / DC converter 131 functions as a DC / AC converter, and the motor 110 functions as a starter motor that drives the engine 1 by transmitting the rotation of its rotor to the crankshaft 7 of the engine 1 via the reduction gear system. Note that the switching elements 131a, 131b, 131c, 131d, 131e, and 131f are typically transistors, and in Figure 2, they are shown as N-type MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) as an example. Furthermore, instead of using motor 110 as a general-purpose starter motor, a dedicated starter motor without a power generation function may be used separately, and the motor ECU 130 may similarly control its drive.

[0029] Specifically, the AC / DC converter 131 has a pair of switching elements 131a, 131b, 131c, 131d, 131e, and 131f corresponding to each of the three phases: U-phase, V-phase, and W-phase.

[0030] In other words, in the AC / DC converter 131, a pair of U-phase switching elements 131a and 131b are electrically connected. When switching element 131a is ON and switching element 131b is OFF, the U-phase drive voltage is set to a high level, and when switching element 131a is OFF and switching element 131b is ON, the U-phase drive voltage is set to a low level.

[0031] Furthermore, in the AC / DC converter 131, a pair of V-phase switching elements 131c and 131d are electrically connected. When switching element 131c is ON and switching element 131d is OFF, the V-phase drive voltage is set to a high level, and when switching element 131c is OFF and switching element 131d is ON, the V-phase drive voltage is set to a low level.

[0032] Furthermore, in the AC / DC converter 131, a pair of W-phase switching elements 131e and 131f are electrically connected. When switching element 131e is ON and switching element 131f is OFF, the W-phase drive voltage is set to a high level, and when switching element 131e is OFF and switching element 131f is ON, the W-phase drive voltage is set to a low level.

[0033] Here, the switching element 131a has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the high-potential side of the lead-acid battery 101, and the other input terminal electrically connected to the connection terminal 111a of the switching element 131b and the motor 110. The switching element 131a turns on and off according to a predetermined control signal applied to its control terminal from the control unit 132, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0034] Furthermore, the switching element 131b has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the connection terminal 111a of the switching element 131a and the motor 110, and the other input terminal electrically connected to the low potential side of the lead battery 101. The switching element 131b turns on and off according to a predetermined control signal applied from the control unit 132 to its control terminal, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0035] Furthermore, the switching element 131c has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the high-potential side of the lead-acid battery 101, and the other input terminal electrically connected to the connection terminal 111b of the switching element 131d and the motor 110. The switching element 131c turns on and off according to a predetermined control signal applied to its control terminal from the control unit 132, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0036] Furthermore, the switching element 131d has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the switching element 131c and the connection terminal 111b of the motor 110, and the other input terminal electrically connected to the low potential side of the lead battery 101. The switching element 131d turns on and off according to a predetermined control signal applied from the control unit 132 to its control terminal, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0037] Furthermore, the switching element 131e has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the high-potential side of the lead-acid battery 101, and the other input terminal electrically connected to the switching element 131f and the connection terminal 111c of the motor 110. The switching element 131e turns on and off according to a predetermined control signal applied to its control terminal from the control unit 132, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0038] Furthermore, the switching element 131f has a control terminal electrically connected to the control unit 132, one input terminal electrically connected to the switching element 131e and the connection terminal 111c of the motor 110, and the other input terminal electrically connected to the low potential side of the lead battery 101. The switching element 131f turns on and off according to a predetermined control signal applied from the control unit 132 to its control terminal, and when it is in the ON state, current flows from one input terminal to the other input terminal.

[0039] In other words, the control unit 132 sets the drive voltage of the U phase to a high level when switching element 131a is ON and switching element 131b is OFF, sets the drive voltage of the U phase to a low level when switching element 131a is OFF and switching element 131b is ON, or sets the drive voltage of the U phase to zero (no power: power off) when switching element 131a is OFF and switching element 131b is OFF, thereby switching the current flowing through the coil 110a between high level, low level and no power. The control unit 132 sets the drive voltage of the V phase to a high level when switching element 131c is ON and switching element 131d is OFF, and sets the drive voltage of the V phase to a high level when switching element 131c is OFF and switching element 131d is ON The current flowing through the V-phase coil 110b can be switched by setting the V-phase drive voltage to a low level when the V-phase is in the ON state, or by setting the V-phase drive voltage to zero (no power: power off) when switching element 131c is in the OFF state and switching element 131d is also in the OFF state. Furthermore, the current flowing through the W-phase coil 110c can be switched by setting the W-phase drive voltage to a high level when switching element 131e is in the ON state and switching element 131f is in the OFF state, or by setting the W-phase drive voltage to a low level when switching element 131e is in the OFF state and switching element 131f is also in the ON state, or by setting the V-phase drive voltage to zero (no power: power off) when switching element 131e is in the OFF state and switching element 131f is also in the OFF state.

[0040] Here, in a simplified configuration that omits the sensor for detecting the rotational position of the motor 110, the control unit 132 measures the voltage (induced electromotive force) of the unpowered phase (unpowered phase) and appropriately drives and controls the operation of the motor 110. In a motor 110 having a first coil (110a) corresponding to the first phase (U phase), a second coil (110b) corresponding to the second phase (V phase), and a third coil (110c) corresponding to the third phase (W phase), the control unit 132 has a first state in which only the first phase is turned off (switching element 131a is off, and switching element 131b is off, and the drive voltage of the U phase is zero), and a second state in which only the second phase is turned off (switching element 131b is off, and the drive voltage of the U phase is zero). The motor 110 is driven while switching between a second state (where 1c is off and switching element 131d is off, resulting in zero drive voltage for the V phase) and a third state (where only the third phase is off, with switching element 131e and switching element 131f off, resulting in zero drive voltage for the W phase). At the same time, the voltage of the first phase is measured at a timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears, and the measured voltage is obtained. The larger the absolute value of this measured voltage, the more preferable it is to switch from the first state to the second state earlier. Similarly, when switching from the second state to the third state, the voltage of the second phase is measured at a timing corresponding to when the back electromotive force of the second phase generated by switching from the first state to the second state disappears, and the measured voltage is obtained. The larger the absolute value of this measured voltage, the more preferable it is to switch from the second state to the third state earlier. Similarly, when switching from the third state to the first state, the voltage of the third phase is measured at a timing corresponding to when the back electromotive force of the third phase generated by switching from the second state to the third state disappears, and the measured voltage is obtained. The larger the absolute value of this measured voltage, the more preferable it is to switch from the third state to the first state earlier.Furthermore, the timing corresponding to the disappearance of the back electromotive force of each phase corresponds to the timing at which the magnitude of the absolute value of the back electromotive force of each phase becomes zero or a value that can be evaluated as virtually zero. Typically, this is defined by a time length that includes a predetermined margin over the time length from the start of the unenergized phase (from the first state to the third state) of each phase until the magnitude of the absolute value of its back electromotive force becomes zero, and corresponds to the timing length of the voltage measurement timer 132a. Also, the end of each period from the first state to the third state is defined by the time length from the completion of timing by the voltage measurement timer 132a to the end of each period from the first state to the third state, and corresponds to the timing length of the energization timer 132b.

[0041] Furthermore, from the viewpoint of more appropriately controlling the operation of the motor 110, the measured voltage obtained by measuring the voltage of the first phase at the timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears is the voltage obtained by measuring the voltage of the first phase after a first period has elapsed following the switch from the third state to the first state, and it is preferable that this first period be set shorter the shorter the duration of the third state. Similarly, for the back electromotive force of the second phase generated by switching from the first state to the second state, the measured voltage obtained by measuring the voltage of the second phase at the timing corresponding to when the back electromotive force of the second phase disappears is the voltage obtained by measuring the voltage of the second phase after a second period has elapsed following the switch from the first state to the second state, and it is preferable that this second period be set shorter the shorter the duration of the first state. Similarly, regarding the back electromotive force of the third phase generated by switching from the second state to the third state, the measured voltage obtained by measuring the voltage of the third phase at the timing corresponding to when such back electromotive force of the third phase disappears is the voltage obtained by measuring the voltage of the third phase after a third period has elapsed after switching from the second state to the third state, and it is preferable that this third period be set to be shorter the shorter the duration of the third state.

[0042] Furthermore, from the viewpoint of more appropriately controlling the rotational operation of the motor 110, it is preferable that the motor drive control device 100 be applied to the motor 110 used to start the engine 1.

[0043] The motor drive control device 100, having the configuration described above, measures the voltage of the first phase at the timing corresponding to when the back electromotive force of the first phase, which is generated when switching from a third state where only the third phase (W phase) is turned off to a first state where only the first phase (U phase) is turned off, disappears, and obtains a measured voltage. The larger the absolute value of this measured voltage, the earlier the timing of switching from the first state to the second state is advanced, and the switch is made from the first state to the second state, and the back electromotive force of the second phase, which is generated when switching from the first state to the second state, disappears. The voltage of the second phase is measured at the appropriate timing to obtain the measured voltage. The larger the absolute value of this measured voltage, the earlier the timing of switching from the second state to the third state is advanced. Furthermore, the voltage of the third phase is measured at the timing corresponding to when the back electromotive force of the third phase generated by switching from the second state to the third state disappears. The larger the absolute value of this measured voltage, the earlier the timing of switching from the third state to the first state is advanced. The motor drive control device 100's operation when executing this process will be explained in detail below with reference to Figures 3 and 4.

[0044] First, the flowchart shown in Figure 3 begins when the ignition switch (not shown) changes from the off state to the on state, and the motor ECU 130 starts up. The switching process then proceeds to step S1. This switching process is repeatedly executed at predetermined control cycles by reading the necessary control and processing programs and control and processing data from memory while the motor ECU 130 is running.

[0045] In step S1, the control unit 132 reads and references voltage measurement timer search table data from memory and searches for and obtains a voltage measurement timer 132a having a timing length that corresponds to the time when the back electromotive force disappears and also reflects the time required for the motor 110 to rotate 60 degrees in the unpowered phase immediately preceding the current unpowered phase (the angle range is 60 degrees in the case of 120 degrees of power supply). With this, the processing of step S1 is completed, and the switching process proceeds to step S2. The time required for the motor 110 to rotate 60 degrees in the unpowered phase immediately preceding the current unpowered phase is the one obtained by the motor ECU 130 before the processing of step S1. Furthermore, the timing length set by the voltage measurement timer 132a is set to be shorter the shorter the time required for the motor 110 to rotate in the unpowered phase immediately preceding the current unpowered phase.

[0046] Here, Figure 4 shows the following unpowered phases: from time t1 to time t3, only the V phase is turned off (third state); from time t3 to time t6, only the U phase is turned off (first state); from time t6 to time t8, only the W phase is turned off (second state); from time t8 to time t10, only the V phase is turned off (third state); from time t10 to time t12, only the U phase is turned off (first state); and from time t12 to time t14, only the W phase is turned off (second state).

[0047] In step S2, the control unit 132 initiates timing using the voltage measurement timer 132a and determines whether the timing period of the voltage measurement timer 132a, which was obtained in step S1, has elapsed. If the determination shows that the timing period has elapsed, the timing by the voltage measurement timer 132a is complete, and the control unit 132 proceeds to the switching process in step S3. On the other hand, if the timing period has not elapsed, the timing by the voltage measurement timer 132a is not complete, and the control unit 132 repeats the process in step S2.

[0048] Here, Figure 4 shows the back EMF that appears in the unpowered phase when only the V phase is turned off (third state) from time t1 to time t2, the back EMF that appears in the unpowered phase when only the U phase is turned off (first state) from time t3 to time t4, the back EMF that appears in the unpowered phase when only the W phase is turned off (second state) from time t6 to time t7, the back EMF that appears in the unpowered phase when only the V phase is turned off (third state) from time t8 to time t9, the back EMF that appears in the unpowered phase when only the U phase is turned off (first state) from time t10 to time t11, and the back EMF that appears in the unpowered phase when only the W phase is turned off (second state) from time t12 to time t13. Furthermore, while the example of the timing at which timing by the voltage measurement timer 132a is completed is shown, in applicable cases, timing by the voltage measurement timer 132a can also be completed within the period from time t2 to time t3, within the period from time t7 to time t8, within the period from time t9 to time t10, within the period from time t11 to time t2, and within the period from time t11 to time t2.

[0049] In step S3, the control unit 132 measures the current unpowered phase voltage based on the voltage value received by the voltage receiving circuit 133 when the timing by the voltage measurement timer 132a is completed. This completes step S3, and the switching process proceeds to step S4.

[0050] Here, Figure 4 shows an example where the voltage of the unpowered phase is measured at the time when the timing by the voltage measurement timer 132a is completed, with time t5 as a representative example. However, in applicable cases, the voltage of the unpowered phase can also be measured at the time when the timing by the voltage measurement timer 132a is completed during the period from time t2 to time t3, from time t7 to time t8, from time t9 to time t10, from time t11 to time t2, and from time t13 to time t14.

[0051] In step S4, the control unit 132 reads and references the energizing timer search table data from memory, and searches for and obtains an energizing timer 132b having a timing length corresponding to the absolute value of the current unenergized phase voltage measured in step S3. This completes step S4, and the switching process proceeds to step S5. The timing length set by the energizing timer 132b is set to be shorter the larger the absolute value of the current unenergized phase voltage.

[0052] In step S5, the control unit 132 initiates timing using the energizing timer 132b and determines whether the timing period of the energizing timer 132b, obtained in step S4, has elapsed. If the determination shows that the timing period has elapsed, the timing by the energizing timer 132b is complete, and the control unit 132 proceeds to the switching process in step S6. On the other hand, if the timing period has not elapsed, the timing by the energizing timer 132b is not complete, and the control unit 132 repeats the process in step S5. The timing period of the energizing timer 132b is set to be shorter the larger the absolute value of the current unenergized phase voltage measured in step S3.

[0053] Here, Figure 4 shows an example of when the timing by the energizing timer 132b is completed, with time t6 as a representative example. However, if applicable, the timing by the energizing timer 132b may also be completed at times t3, t8, t10, t12, and t14.

[0054] In step S6, the control unit 132 terminates the current unpowered phase (aligning the end of the current unpowered phase with the timing completed by the power timer 132b in step S5) and starts the unpowered phase immediately following the current unpowered phase. This switches the energization state of the current supplied to the motor 110, completing step S6 and ending this series of switching processes.

[0055] Here, Figure 4 shows an example where, as a representative example at time t6, the current unpowered phase is terminated and the next unpowered phase immediately following the current unpowered phase is started at the timing when the timing by the energizing timer 132b is completed. However, in applicable cases, the current unpowered phase can also be terminated and the next unpowered phase immediately following the current unpowered phase is started at the timing when the timing by the energizing timer 132b is completed at times t3, t8, t10, t12, and t14.

[0056] As described above, in the motor drive control device 100 of this embodiment, the control unit 132 drives the motor 110, which has first coils (110a, 110b, 110c) corresponding to the first phase (U phase, V phase, W phase), second coils (110b, 110c, 110d) corresponding to the second phase (V phase, W phase, U phase), and third coils (110c, 110a, 110b) corresponding to the third phase (W phase, U phase, V phase), by switching between a first state in which only the first phase is turned off, a second state in which only the second phase is turned off, and a third state in which only the third phase is turned off, and also switches from the third state to the first state The voltage of the first phase is measured at a timing corresponding to when the back electromotive force of the first phase generated by switching to the second state disappears, and the measured voltage is obtained. The larger the absolute value of this measured voltage, the earlier the timing of switching from the first state to the second state is advanced. Therefore, with a simplified configuration that omits the sensor for detecting the rotational position of the motor 110, the voltage of the unpowered phase (induced electromotive force) can be measured while suppressing the effect of the back electromotive force (flyback voltage) generated when switching the energized state of one phase of the current supplied to the motor 100 to an unpowered state, and the operation of the motor 110 can be appropriately driven and controlled.

[0057] Furthermore, in the motor drive control device 100 of this embodiment, the measured voltage obtained by measuring the voltage of the first phase at the timing corresponding to when the back electromotive force of the first phase, which is generated when switching from a third state in which only the third phase is turned off to a first state in which only the first phase is turned off, disappears is the voltage obtained by measuring the voltage of the first phase after a first period has elapsed after switching from the third state to the first state. Since this first period is set to be shorter the shorter the duration of the third state, the operation of the motor 110 can be driven and controlled more appropriately.

[0058] Furthermore, since the motor drive control device 100 in this embodiment is applied to the motor 110 used to start the engine 1, it can more appropriately drive and control the operation of the motor 110.

[0059] It should be noted that the present invention is not limited to the above-described embodiments in terms of the type, shape, arrangement, number, etc. of the components, and it is of course possible to modify them as appropriate without departing from the spirit of the invention, such as by appropriately substituting the components with those that produce equivalent effects. [Industrial applicability]

[0060] As described above, the present invention provides a motor drive control device that can appropriately drive and control a motor with a simplified configuration that omits a sensor for detecting the rotational position of the motor, and is expected to be widely applicable to automobiles due to its general-purpose and universal nature. [Explanation of Symbols]

[0061] 1…Engine (internal combustion engine) 2…Cylinder block 3…Cooling water passage 4…Water temperature sensor 5... Piston 6…Connecting rod 7... Crankshaft 8... Crank angle sensor 9…Cylinder head 10… Combustion chamber 11... Spark plug 12…Intake passage 13…Intake valve 14…Fuel injection valve 15…Throttle valve 16… Exhaust passage 17… Exhaust valve 50…Engine control device 60…Engine ECU (Electronic Control Unit) 70…Relacta 72… Teeth 73... Missing tooth 100...Motor drive control device 101… Lead-acid battery 102... Load 105... Starter switch 106... Throttle position sensor 107... Intake pressure sensor 110... Generator-motor (motor) 110a... U-phase coil 110b...V-phase coil 110c...W phase coil 111a, 111b, 111c... connection terminals 112... Rotation axis 130…Motor ECU 131…AC (Alternate Current) / DC (Direct Current) Converter 131a, 131b... U-phase switching elements 131c, 131d... V-phase switching elements 131e, 131f...W-phase switching elements 132... Control Unit 132a...Voltage measurement timer 132b... Power-on timer 133...Voltage receiving circuit EM... Exhaust pipe IM... Intake pipe

Claims

1. A motor drive control device having a control unit that drives a motor having a first coil corresponding to the first phase, a second coil corresponding to the second phase, and a third coil corresponding to the third phase, while switching between a first state in which only the first phase is turned off, a second state in which only the second phase is turned off, and a third state in which only the third phase is turned off, The motor drive control device is characterized in that the control unit measures the voltage of the first phase at a timing corresponding to when the back electromotive force of the first phase generated by switching from the third state to the first state disappears, and obtains a measured voltage, and the larger the absolute value of the measured voltage, the earlier the timing of switching from the first state to the second state is advanced to switch from the first state to the second state.

2. The measured voltage is the voltage obtained by measuring the voltage of the first phase when a first period has elapsed after switching from the third state to the first state. The motor drive control device according to claim 1, characterized in that the first period is set to be shorter as the duration of the third state becomes shorter.

3. The motor drive control device according to claim 1 or 2, characterized in that it is applied to the motor used for starting an internal combustion engine.

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