Motor control device

Abstract

This invention provides a motor control device that omits a sensor for detecting the rotational position of the motor, while still ensuring adequate motor output and enabling proper control of the motor's operation. [Solution] In the motor control device 100, the control unit 132, 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), acquires the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases at multiple timings, and sets the switching timing for switching the energized state of the corresponding phase from the first to the third phase based on the state of the time change of the absolute value of the difference acquired at multiple timings, setting the switching timing according to the time length between the multiple timings at which the absolute value of the difference was acquired.

Description

Technical Field

[0001] The present invention relates to a motor 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 a power generation output is wound, is used as a starting motor of the internal combustion engine, and controls to charge a secondary battery such as a lead battery mounted on the vehicle, and controls to start the internal combustion engine by rotating its crankshaft. A motor control device has been proposed.

[0003] Under such circumstances, Patent Document 1 relates to a driving method of a sensorless brushless DC motor, and a control unit 5 calculates a change rate of a voltage with respect to time from an induced voltage of one phase of three phases of a current supplied to the motor, and determines a timing at which the induced voltage obtained from such a change rate becomes a maximum value and a minimum value as a timing (commutation timing) for switching an energization state of a phase of the current supplied to the motor.

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 inventors' research, the configuration disclosed in Patent Document 1 determines the commutation timing using the induced voltage during periods when no power is supplied to one phase. Therefore, there are certain limitations on the number of times the commutation timing can be determined and the accuracy of the determined commutation timing. Furthermore, according to the inventors' research, increasing the number of times the commutation timing is determined to improve the accuracy of the determined commutation timing leads to an increase in the period when no power is supplied, which tends to result in a trade-off with the motor output. In other words, currently, there is a strong demand for a novel configuration that can appropriately secure the motor output and appropriately control the motor's operation in a simplified configuration that omits the sensor for detecting the motor's rotational position.

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

[0007] To achieve the above objectives, the present invention provides a motor control device 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, wherein the control device acquires the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases at multiple timings, and sets a switching timing for switching the energized state of the corresponding phase from the first to the third phase based on the state of the time change of the absolute value of the difference acquired at the multiple timings, wherein one aspect of the control device is that it sets the switching timing according to the time length between the multiple timings at which the absolute value of the difference was acquired. [Effects of the Invention]

[0008] According to the motor control device according to the first aspect of the present invention described above, in 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, the motor control device has a control unit that acquires the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases at multiple timings, and sets a switching timing for switching the energized state of the corresponding phase from the first to the third phase based on the state of the time change of the absolute value of the difference acquired at the multiple timings, wherein the control unit sets the switching timing according to the time length between the multiple timings at which the absolute value of the difference was acquired, and thus it is possible to appropriately secure the output of the motor and appropriately control the operation of the motor with a simplified configuration that omits a sensor for detecting the rotational position of the motor. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing a motor 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 control device in this embodiment, together with the engine control device and motor. [Figure 3] Figure 3 is a flowchart showing an example of the operation of the motor control device in this embodiment. [Figure 4] Figure 4 is a time chart showing an example of the operation of the motor control device in this embodiment. [Figure 5] Figure 5 is a magnified view of a portion of the waveform diagram in Figure 4, overlaid on top of each other. [Modes for carrying out the invention]

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

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

[0012] Figure 1 is a schematic diagram showing the motor 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 opposite side of the intake pipe IM, and an exhaust passage 16 communicating with the combustion chamber 10 is formed in the exhaust pipe EM. The cylinder head 9 is provided with an exhaust valve 17 that communicates with the combustion chamber 10 and the exhaust passage 16 in an openable and closable manner. In addition, as the rotational position corresponding to the rotational position of the crankshaft 7, the rotational position of the exhaust cam of the mechanism that opens and closes the exhaust valve 17 may be adopted.

[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 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 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 control device in the present embodiment. Further, FIG. 4 is a time chart showing an example of the operation of the motor control device in the present embodiment, and FIG. 5 is a partially enlarged view showing a part of the waveform diagram of FIG. 4 superimposed. In FIG. 4, in order from top to bottom, the temporal change in the energization state of the U-phase of the current supplied to the motor, the temporal change in the energization state of the V-phase of the current supplied to the motor, and the temporal change in the energization state of the W-phase of the current supplied to the motor are shown, each with the induced electromotive voltage superimposed, and in the fourth position from top to bottom, the induced electromotive voltage from the U-phase to the W-phase of the current supplied to the motor is shown superimposed. Also, in FIG. 4, an example of operating the motor with so-called 180-degree energization is shown, but the same measurement principle is applicable when measuring the induced electromotive voltage during a period that is not in the non-energized (off) state.

[0021] As shown in FIG. 2, the engine control device 50 is activated when the starter 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 ignition operation of the spark plug 11 by controlling the energization state of an ignition coil (not shown) and controls the fuel injection operation (valve opening operation) of the fuel injection valve 14 by controlling the energization state 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). Necessary control and processing programs and control and processing data are stored in such a memory, and 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 to calculating the rotational speed of the engine 1 based on the output signal sent from the crank angle sensor 8, 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, the engine ECU 60 may determine that the tooth portion 72 of the reluctor 70 has passed near the crank angle sensor 8 and send an output signal indicating that the tooth portion 72 has passed near the crank angle sensor 8 to the motor control device 100.

[0023] Furthermore, the motor 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 control device 100 may not be separate units but may constitute a single integrated control device.

[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. 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 when driven by the engine 1. 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 current supplied to the motor 110. In the figure, the control unit 132 is shown as a functional block 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 multi-purpose starter motor, a dedicated starter motor without a power generation function may be used separately, and the motor ECU 130 may control it in the same way.

[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, from the viewpoint of appropriately securing the output of the motor 110 and appropriately controlling the operation of the motor 110, the control unit 132 preferably sets the switching timing for switching the energized state of the corresponding phase from the first to the third phases, based on the state of the time change of the absolute value of the absolute value of the difference acquired at multiple timings.

[0041] Furthermore, from the viewpoint of ensuring the output of the motor 110 more appropriately, the control unit 132 calculates the timing for obtaining the absolute value of the difference a second time and the timing when the absolute value of the difference becomes zero, based on the timing of the first acquisition of the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases. If the time length between the timing of obtaining the absolute value of the difference a second time and the timing when the absolute value of the difference becomes zero is less than a first threshold, it is preferable to prohibit obtaining the absolute value of the difference a second time.

[0042] Furthermore, from the viewpoint of ensuring the output of the motor 110 more appropriately, it is preferable that the control unit 132 prohibits obtaining the absolute value of the difference a second time when the time interval between the first timing for obtaining the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases, and the timing for obtaining the absolute value of the difference calculated based on the first timing for the second time, is less than the second threshold.

[0043] Furthermore, from the viewpoint of ensuring a more appropriate output from the motor 110 and more appropriate control of the motor 110's operation, when the control unit 132 prohibits obtaining a second absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases, it is preferable to set the switching timing to the timing at which the absolute value of the difference calculated based on the first timing becomes zero.

[0044] The motor control device 100, having the configuration described above, has a motor 110 with 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). In this motor 110, the motor control device 100 sets the switching timing of the corresponding phase from the first to the third phase according to the time length between multiple timings in which the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other phases is obtained, and performs a switching process to switch the energized state of the corresponding phase. The operation of the motor control device 100 when performing this process will be described in detail below with reference to Figures 3 to 5.

[0045] 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.

[0046] In step S1, the control unit 132 keeps the switching process in the process of step S1 for a predetermined period corresponding to the time during which it is performing the so-called forced commutation process. Once this predetermined period has elapsed, the process of step S1 is terminated, and the switching process proceeds to the process of step S2. This predetermined period is typically measured by a program timer or the like.

[0047] In Figure 4, the switching process is waiting during the process of step S1 for the period prior to time t1.

[0048] In step S2, the control unit 132 measures the induced electromotive force of the corresponding phase from the U phase to the W phase for the first time. Specifically, when the drive voltage of the U phase is at a high level, the control unit 132 turns the switching element 131a from the ON state to the OFF state and keeps the switching element 131b in the OFF state, thereby de-energizing the U phase and measuring the induced electromotive force of the U phase. Once the measurement of this voltage is complete, the control unit 132 immediately returns the switching element 131a from the OFF state to the ON state and keeps the switching element 131b in the OFF state, returning the energized state of the U phase to the state before measurement. Similarly, when the drive voltage of the U-phase is low, the drive voltage of the V-phase is high, the drive voltage of the V-phase is low, the drive voltage of the W-phase is high, or the drive voltage of the W-phase is low, the control unit 132 controls the ON and OFF states of the corresponding switching elements 131a to 131f to temporarily de-energize the U-phase to W-phase and measure the induced electromotive force. Once the measurement of this voltage is complete, the control unit 132 immediately controls the ON and OFF states of the switching elements 131a to 131f to restore the energized state of the U-phase to W-phase to the state before measurement. At this time, the control unit 132 also calculates the absolute value of the difference between the measured values ​​of the induced electromotive force of the corresponding phases among the U-phase to W-phase. With this, the processing of step S2 is completed, and the switching process proceeds to the processing of step S3.

[0049] In Figure 4, the timing for the first measurement of the induced electromotive force by temporarily de-energizing the U-phase and W-phase is within the periods from time t1 to time t2, time t3 to time t4, time t5 to time t6, time t7 to time t8, time t9 to time t10, and time t11 to time t12. Furthermore, as illustrated by referring to the period from time t1 to time t2 in Figure 5, if we denote the time when the induced electromotive force of the U-phase and V-phase is measured for the first time as t1a, then the time to calculate the absolute value D1 of the difference between the first measured induced electromotive force of the U-phase and the first measured induced electromotive force of the V-phase can also be considered to be essentially time t1a.

[0050] In step S3, the control unit 132 calculates a predicted crossover timing, which is the timing at which the induced voltages of the corresponding phases from the U-phase to the W-phase intersect, based on the induced voltage values ​​of the corresponding phases from the U-phase to the W-phase measured in step S2. Specifically, the control unit 132 reads and refers to predetermined prediction time data corresponding to the induced voltage values ​​from memory, and calculates the predicted crossover timing by adding a predetermined prediction time corresponding to the time when the induced voltage of the corresponding phases from the U-phase to the W-phase was measured in step S2. In this case, the predicted crossover timing may also be calculated based on the absolute value of the difference between the measured values ​​of the induced voltages of the corresponding phases. With this, the process of step S3 is completed, and the switching process proceeds to step S4. In other words, at the predicted crossover point, the absolute value of the difference between the induced voltages of the corresponding phases becomes zero.

[0051] In step S4, the control unit 132 calculates the timing for measuring the induced electromotive force of a corresponding phase from the U-phase to the W-phase, for the second time (second induced electromotive force measurement timing), based on the induced electromotive force values ​​of the corresponding phases from the U-phase to the W-phase measured in step S2. Specifically, the control unit 132 reads and refers to predetermined data for the second measurement time corresponding to the induced electromotive force value from memory, and calculates the second induced electromotive force measurement timing by adding the predetermined second measurement time corresponding to the time when the induced electromotive force of the corresponding phase from the U-phase to the W-phase was measured in step S2. In this case, the second induced electromotive force measurement timing may also be calculated based on the absolute value of the difference between the measured values ​​of the induced electromotive force of the corresponding phases. With this, the process of step S4 is completed, and the switching process proceeds to step S5.

[0052] In step S5, the control unit 132 determines whether the second induced electromotive force measurement timing calculated in step S4 and the predicted crossover point timing calculated in step S3 are separated by a predetermined time or more. If the determination shows that they are separated by a predetermined time or more, the control unit 132 proceeds to step S6 for the switching process. On the other hand, if they are not separated by a predetermined time or more, the control unit 132 proceeds to step S9 for the switching process. The predetermined time is set in advance to ensure that the control unit 132 can actually measure the induced electromotive force of the corresponding phase from the U phase to the W phase for the second time before the predicted crossover point timing.

[0053] In step S6, the control unit 132 determines whether the timing of the first measurement of the induced electromotive force of the corresponding phase from the U-phase to the W-phase in step S2 (first induced electromotive force measurement timing) and the second induced electromotive force measurement timing calculated in step S4 are separated by a predetermined time or more. If the determination shows that they are separated by a predetermined time or more, the control unit 132 proceeds to step S7 for the switching process. On the other hand, if they are not separated by a predetermined time or more, the control unit 132 proceeds to step S9 for the switching process. The predetermined time is set in advance to ensure that when the control unit 132 measures the induced electromotive force of the corresponding phase from the U-phase to the W-phase for the second time, the measured value shows a significant difference from the measured value of the induced electromotive force of that phase measured for the first time.

[0054] In step S7, the control unit 132 measures the induced electromotive force of the corresponding phase from the U phase to the W phase for the second time. The difference between this second measurement and the first measurement of the induced electromotive force of the phase in step S2 is that the measurement timing is later, but the other measurement details are the same as the first measurement. At this time, the control unit 132 also calculates the absolute value of the difference between the measured values ​​of the induced electromotive force of the phase. With this, the process of step S7 is completed, and the switching process proceeds to step S8.

[0055] In Figure 4, the timing of the second measurement of the induced electromotive force after temporarily de-energizing the U-phase and W-phase is within the periods t1 to t2, t3 to t4, t5 to t6, t7 to t8, t9 to t10, and t11 to t12, respectively, and is after the timing of the first measurement of the induced electromotive force in step S2. Furthermore, as illustrated by referring to the period from time t1 to time t2 in Figure 5, if we consider the time when the induced electromotive force of the U-phase and V-phase is measured for the second time to be t1b, then the time to calculate the absolute value D2 of the difference between the second measured induced electromotive force of the U-phase and the second measured induced electromotive force of the V-phase can also be considered to be effectively time t1b.

[0056] In step S8, the control unit 132 calculates the switching timing based on the induced electromotive force values ​​of the corresponding phases from the U phase to the W phase measured in step S2 (first induced electromotive force measurement value) and the induced electromotive force values ​​of the same phase measured in step S7 (second induced electromotive force measurement value). Specifically, as illustrated by referring to the period from time t1 to time t2 in Figure 5, if we let t1a be the time when the first induced voltage measurement was taken, D1 be the absolute value of the difference between the first induced voltage measurement of the U phase and the first induced voltage measurement of the V phase, t1b be the time when the second induced voltage measurement was taken, D2 be the absolute value of the difference between the second induced voltage measurement of the U phase and the second induced voltage measurement of the V phase, and T1 be the length of time from time t1a when the first induced voltage measurement was taken to time t1b when the second induced voltage measurement was taken, then the length of time T2 from time t1b when the second induced voltage measurement was taken to time t2a when the induced voltages of the U phase and V phase intersect is calculated using the formula D2 / ((D1-D2) / T1). Here, since the time t1b when the second induced voltage measurement was taken is known, the switching timing is calculated as time t2a, which is obtained by adding the time length T2 to the time t1b when the second induced voltage measurement was taken. With this, the process in step S8 is completed, and the switching process proceeds to the process in step S10.

[0057] In step S9, the control unit 132 does not measure the induced electromotive force of the corresponding phase from the U phase to the W phase a second time. Therefore, it calculates the switching timing based on the predicted crossover timing calculated in step S3. Specifically, the time of the predicted crossover timing corresponds to the switching timing. With this, the process of step S9 is completed, and the switching process proceeds to step S10.

[0058] In step S10, the control unit 132 switches the energized state of the corresponding phase from the U phase to the W phase. Specifically, the control unit 132 determines which phase to switch the energized state of and its energized state according to the six typical motor position stages, and then switches the energized state of that phase.

[0059] In Figure 4, the energized state of each phase is switched by switching the drive voltage of the V phase from low to high at time t2, the drive voltage of the U phase from high to low at time t4, the drive voltage of the W phase from low to high at time t6, the drive voltage of the V phase from high to low at time t8, the drive voltage of the U phase from low to high at time t10, and the drive voltage of the W phase from high to low at time t12.

[0060] As described above, in the motor control device 100 of this embodiment, the control unit 132 acquires the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases at multiple timings 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). Based on the time change state of the absolute value of the difference acquired at multiple timings, the control unit 132 sets the switching timing for switching the energized state of the corresponding phase from the first to the third phase, according to the time length between the multiple timings in which the absolute value of the difference was acquired. Therefore, with a simplified configuration that omits a sensor for detecting the rotational position of the motor 110, the output of the motor 110 can be appropriately secured and the operation of the motor 110 can be appropriately controlled.

[0061] Furthermore, in the motor control device 100 of this embodiment, the control unit 132 calculates the timing for obtaining the absolute value of the difference a second time and the timing when the absolute value of the difference becomes zero, based on the timing of the first acquisition of the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases. If the time length between the timing of obtaining the absolute value of the difference a second time and the timing when the absolute value of the difference becomes zero is less than a first threshold, the control unit prohibits obtaining the absolute value of the difference a second time, thereby ensuring the output of the motor 110 more appropriately.

[0062] Furthermore, in the motor control device 100 of this embodiment, the control unit 132 prohibits obtaining the absolute value of the difference a second time when the time interval between the first timing for obtaining the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases, and the timing for obtaining the absolute value of the difference calculated based on the first timing for the second time, is less than the second threshold. This makes it possible to ensure the output of the motor 110 more appropriately.

[0063] Furthermore, in the motor control device 100 of this embodiment, when the control unit 132 prohibits obtaining the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases for a second time, it sets the timing at which the absolute value of the difference calculated based on the first timing becomes zero as the switching timing. This allows for more appropriate securing of the output of the motor 110 and more appropriate control of the operation of the motor 110.

[0064] 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]

[0065] As described above, the present invention provides a motor control device that can appropriately secure the motor output and appropriately control the motor's operation with a simplified configuration that omits a sensor for detecting the motor's rotational position, and is expected to be widely applicable to automobiles due to its general-purpose and universal nature. [Explanation of Symbols]

[0066] 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 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 133...Voltage receiving circuit EM... Exhaust pipe IM... Intake pipe

Claims

1. A motor control device 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, wherein the motor control device has a control unit that acquires the absolute value of the difference between the induced electromotive force of one of the first, second, and third phases and the induced electromotive force of the other one of the first, second, and third phases at multiple timings, and sets a switching timing for switching the energized state of the corresponding phase from the first to the third phase based on the state of the time change of the absolute value of the difference acquired at the multiple timings, The motor control device is characterized in that the control unit sets the switching timing according to the time length between the plurality of timings from which the absolute value of the difference is obtained.

2. The motor control device according to claim 1, characterized in that the control unit prohibits obtaining the absolute value of the difference a second time when the time interval between the timing for obtaining the absolute value of the difference a second time, calculated based on the first timing for obtaining the absolute value of the difference, and the timing when the absolute value of the difference calculated based on the first timing becomes zero, is less than a first threshold.

3. The motor control device according to claim 1, characterized in that the control unit prohibits obtaining the absolute value of the difference a second time when the time interval between the first timing for obtaining the absolute value of the difference and the timing for obtaining the absolute value of the difference calculated based on the first timing is less than a second threshold.

4. The motor control device according to claim 2 or 3, characterized in that when the control unit prohibits obtaining the absolute value of the difference a second time, it sets the timing at which the absolute value of the difference calculated based on the timing of the first time becomes zero to the switching timing.

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