JP3701655B2 - Electric motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor control device, and more particularly to a motor control device suitable for driving a synchronous motor without a sensor.
[0002]
[Prior art]
Conventionally, as an apparatus for driving a synchronous motor without a sensor, for example, an apparatus disclosed in Japanese Patent Laid-Open No. 11-75394 is known. In order to drive a synchronous motor using an inverter, it is necessary to detect the rotor position of the motor and appropriately switch ON / OFF of a plurality of switching elements built in the inverter according to the rotor position. . For this reason, when starting the drive from the state where the rotor of the motor is idling, it is necessary to first detect the rotor position.
[0003]
The above-described conventional device turns on at least one of the switching elements incorporated in the inverter to short-circuit the coil of the motor when the drive start of the motor is requested in a situation where the rotor is idling. When the coil of the motor is short-circuited in a state where the rotor is idling, a current caused by the counter electromotive force flows through the coil. The conventional apparatus detects the rotor position based on the coil current.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-75394 [Patent Document 2]
JP 2001-69784 A [Patent Document 3]
US Pat. No. 4,924,043 gazette
[Problems to be solved by the invention]
However, when the rotor idles, the state of the switching element in the inverter changes, and as a result, if a short-circuit current flows through the coil of the motor, the output torque of the motor changes or abnormal noise occurs around the motor. Such a phenomenon occurs. For this reason, the above-mentioned conventional device has a characteristic that when the drive of the electric motor is started from the idling state, the drive cannot always be started smoothly.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric motor control device capable of smoothly driving an electric motor in an idling state.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first invention is a motor control device that drives an electric motor using an inverter,
Back electromotive voltage acquisition means for acquiring back electromotive voltage generated in each phase coil of the electric motor without passing through the inverter;
Rotor position acquisition means for acquiring the rotor position of the electric motor based on the counter electromotive voltage;
Rotor driving means for controlling signals to be supplied to a plurality of switching elements included in the inverter so that the rotor rotates according to the rotor position;
Inverter cutting means for locking all of the plurality of switching elements in an off state until the rotor position is acquired after power driving of the electric motor is requested,
Inverter disconnect release means for releasing the off-state lock at the time when the rotor position is acquired;
It is characterized by providing.
[0008]
According to a second invention, in the first invention, the electric motor is for electrically driving a turbocharger of an internal combustion engine.
[0009]
The third invention is the first or second invention, wherein
An alignment mode means for controlling a signal supplied to the plurality of switching elements so that the rotor position is locked at a predetermined position when power driving of the electric motor is required;
Ramp mode means for controlling signals supplied to the plurality of switching elements so that the rotational speed of the rotor is increased to a speed at which the rotor position can be acquired after the rotor is locked at the predetermined position;
It is characterized by providing.
[0010]
According to a fourth invention, in any one of the first to third inventions,
Rotation determination means for determining whether or not the electric motor is rotating when power driving of the electric motor is requested;
When it is determined that the electric motor is not rotating when power driving of the electric motor is requested, an inverter disconnection prohibiting unit that prohibits the operation of the inverter disconnecting unit;
It is characterized by providing.
[0011]
According to a fifth invention, in any one of the first to fourth inventions,
The rotor driving means switches signals supplied to the plurality of switching elements so that each phase coil of the electric motor is sequentially in a non-energized state,
The counter electromotive voltage acquisition means sequentially acquires counter electromotive voltages generated in a non-energized coil.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.
[0013]
Embodiment 1 FIG.
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the present embodiment includes an internal combustion engine 10. An intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. A turbocharger unit 16 is disposed between the intake passage 12 and the exhaust passage 14.
[0014]
The turbocharger unit 16 includes a turbine 18 located on the exhaust passage 14 side and a compressor 20 located on the intake passage 12 side. Furthermore, between the turbine 18 and the compressor 20, an electric motor 24 having a common rotating shaft 22 is disposed. The turbocharger 16 can drive the compressor 20 by rotating the turbine 18 by exhaust energy or by rotating the rotating shaft 22 by the electric motor 24. The compressor 20 can generate a high supercharging pressure downstream thereof by being driven in this way.
[0015]
The intake passage 12 is provided with a bypass passage 26 that communicates the upstream and downstream of the compressor 20. The bypass passage 26 is provided with a bypass valve 28 that opens when the supercharging pressure becomes excessive. An intercooler 30 and a throttle valve 32 are disposed downstream of the compressor 20. The throttle valve 32 is an electronically controlled valve that is driven by a throttle motor 34 based on the accelerator opening. In the vicinity of the throttle valve 32, a throttle position sensor 36 for detecting the throttle opening and an accelerator position sensor 38 for detecting the accelerator opening are arranged.
[0016]
An exhaust gas recirculation (EGR) passage 40 communicates with the exhaust passage 14 upstream of the turbine 18. The EGR passage 40 is a passage for returning a part of the exhaust gas to the intake system, and communicates with the intake passage 12 via the EGR valve 42. A catalyst 44 is disposed in the exhaust passage 14 downstream of the turbine 18. The exhaust gas discharged from the internal combustion engine 10 passes through the turbine 18, is purified by the catalyst 44, and is then released to the atmosphere.
[0017]
The system of this embodiment includes an ECU 50 for controlling the entire system, a controller 52 for controlling the state of the electric motor 24, and a battery 54 for supplying electric power necessary for the operation of the system. Since the system according to the present embodiment has features in the part related to the control of the electric motor 24, the contents of the ECU 50 and the controller 52 will be described below within a range necessary for explaining the features.
[0018]
FIG. 2 is a block diagram for explaining the contents of a configuration provided for driving the electric motor 24 in the system of the present embodiment. In the present embodiment, the electric motor 24 is a permanent magnet type synchronous electric motor, and has three coils of a U phase, a V phase, and a W phase.
[0019]
The configuration shown in FIG. 2 includes an inverter 60. Inverter 60 is provided with switching element pairs 62 and 64 and freewheeling diode pairs 66 and 68 corresponding to the U-phase coil of electric motor 24. In addition, switching element pairs 70 and 72 and freewheeling diode pairs 74 and 76 corresponding to the V-phase coil, switching element pairs 78 and 80 corresponding to the W-phase coil, and freewheeling diode pairs 82 and 84 are included therein. Is provided.
[0020]
A battery 54 is connected to the inverter 60, and a power supply voltage is applied to both sides of the above-described three switching element pairs and three free wheel diode pairs. According to the inverter 60, an appropriate magnetic field is sequentially generated in the U-phase coil, the V-phase coil, and the W-phase coil by appropriately turning ON / OFF the built-in switching element, and the electric motor 24 is appropriately synchronized and operated. Can do.
[0021]
The system shown in FIG. 2 includes a motor control circuit 86. The motor control circuit 86 includes a voltage generated at both ends of the U-phase coil of the electric motor 24 (hereinafter referred to as “U voltage”), a voltage generated at both ends of the V-phase coil (hereinafter referred to as “V voltage”), and a W-phase. It has a function of detecting a voltage generated at both ends of the coil (hereinafter referred to as “W-phase voltage”). The motor control circuit 86 detects the rotor position of the electric motor 24 based on the U voltage, the V voltage, and the W voltage, and is appropriate for each of the six switching elements built in the inverter 60 based on the detected position. It has a function of supplying a gate signal. Further, the motor control circuit 86 has a function of generating a VCO signal that fluctuates at a cycle corresponding to the rotational speed of the electric motor 24 after the rotor position of the electric motor 24 is detected.
[0022]
The system shown in FIG. 2 includes a turbo controller 88 and an inverter disconnect transistor 90. The turbo controller 88 is a unit for appropriately controlling the state of the turbocharger unit 16 according to the operating state of the internal combustion engine 10. Specifically, the inverter disconnection transistor 90 is supplied with a start signal supplied to the motor control circuit 86 when the electric power assist of the turbocharger unit 16 is required or receives a VCO signal generated by the motor control circuit 86. The process of switching the state is executed.
[0023]
The inverter disconnect transistor 90 is a transistor for uniformly fixing the six gate signal lines respectively connected to the six switching elements built in the inverter 60 to the ground potential. The switching elements incorporated in the inverter 60 are all elements that are turned off when the gate voltage is set to the ground potential. Therefore, according to the inverter disconnection transistor 90, it is possible to fix the inverter 60 in an inactive state regardless of what gate signal the motor control circuit 86 issues.
[0024]
Next, the basic operation of the motor control circuit 86 will be described in more detail with reference to FIGS.
FIG. 3 is a timing chart for explaining the increasing tendency of the motor rotation speed realized when the motor control circuit 86 controls the electric motor 24 according to the basic operation after the activation. As shown in FIG. 3, after the start signal is supplied from the turbo controller 88, the motor control circuit 86 first controls the electric motor 24 in the align mode.
[0025]
In the align mode, a gate signal is supplied to the inverter 60 in a predetermined pattern, so that the rotor of the electric motor 24 is locked at a predetermined position. In order for the electric motor 24 to operate synchronously, the position of the rotor must be known. According to the align mode, the rotor position can always be locked at a fixed position immediately after the start of the electric motor 24, and thereafter, the synchronous operation of the electric motor 24 can be started from that position.
[0026]
When the control in the align mode is completed, the motor control circuit 86 next controls the electric motor 24 in the lamp mode. The ramp mode is a mode in which the rotational speed of the electric motor 24 is increased at an acceleration that does not cause a synchronization shift. At this stage, since the rotational speed of the rotor is not sufficient, a counter electromotive voltage sufficient to detect the rotor position is not generated in each phase coil of the electric motor 24. Therefore, in the ramp mode, the switching frequency of the gate signal is gradually increased without looking at the rotor position and assuming that there is no out-of-synchronization.
[0027]
The ramp mode is continued until the rotational speed of the electric motor 24 is increased to a rotational speed at which a sufficient counter electromotive voltage is generated in each phase coil. When a sufficient counter electromotive voltage is generated in each phase coil, the motor control circuit 86 starts motor control in the run mode. In the run mode, a counter electromotive voltage generated in each phase coil of the electric motor 24 is detected, and the rotor position is detected based on the counter electromotive voltage. Then, based on the detected rotor position, the rotational speed of the electric motor 24 is accelerated to the target rotational speed with the maximum acceleration that does not cause a synchronization shift. Thereafter, in the run mode, the gate signal switching cycle for the inverter 60 is controlled so that the rotational speed of the electric motor 24 matches the target rotational speed while detecting the rotor position.
[0028]
FIG. 4 is a timing chart for explaining the waveform of the gate signal supplied from the motor control circuit 86 to the inverter 60 and the timing at which the back electromotive voltage of each phase coil is sampled in the run mode. More specifically, FIG. 4A shows the waveform of the VCO signal generated by the motor control circuit 86. Regions # 1 to # 6 shown in FIG. 4 each correspond to a rotor rotation angle of 60 degrees. Therefore, the VCO signal is a signal indicating a change in one cycle every time the rotor rotates 60 degrees.
[0029]
FIG. 4B to FIG. 4G show gate signal waveforms supplied to the six switching elements built in the inverter 60. U1, V1, and W1 shown in these drawings mean the switching elements 62, 70, and 78 on the power supply potential side of the U-phase, V-phase, and W-phase, respectively, while U2, V2, and W2 are The switching elements 64, 72, and 80 on the ground potential side of the U phase, V phase, and W phase are meant. As shown in these drawings, in the present embodiment, a so-called 120-degree energization driving method is used in which the switching elements corresponding to the respective phase coils of the electric motor 24 are turned on for a period corresponding to 120 degrees in the process of one cycle. It has been. For this reason, in the system according to the present embodiment, a period in which both of the two switching elements corresponding to each phase coil are in the OFF state is ensured by 60 degrees for each phase during the process of one cycle.
[0030]
FIG. 4 (H) to FIG. 4 (J) show the timing for sampling the counter electromotive voltage generated in the coil for the U phase, the V phase, and the W phase. In each phase coil, during the period of 60 degrees when both of the two switching elements provided corresponding to the coil are in the OFF state, that is, during the period of 60 degrees when the coil is in a non-energized state, A counter electromotive voltage is generated. Therefore, the motor control circuit 86 sets a period (# 3 and # 6 periods in FIG. 4) in which both the switching element pairs 62 and 64 corresponding to the U phase are OFF as the U phase sampling period. Similarly, the period during which both the switching element pair 70 and 72 corresponding to the V phase are OFF (the period # 2, # 5 in FIG. 4) is set as the V phase sampling period, and further, the switching element pair 78 corresponding to the W phase. , 80 are both OFF periods (# 1, # 4 periods in FIG. 4) as W-phase sampling periods.
[0031]
As described above, in the system of the present embodiment, a 120-degree energization method is used as the driving method of the motor 24, and the back electromotive force of the coil is applied during a period of 60 degrees in which each phase coil is in a non-energized state. Sampling is going to be done. Therefore, according to the system of the present embodiment, during the execution of the run mode, the back electromotive force of each phase coil is detected, the rotor position is detected based on the back electromotive voltage, and further, based on the rotor position. Thus, the electric motor 24 can be driven synchronously.
[0032]
By the way, in the system of the present embodiment, the electric motor 24 shares the turbine 18 and the compressor 20 of the turbocharger unit 16 with the rotating shaft 22. The turbine 18 rotates at a certain speed even during the idling operation of the internal combustion engine 10. Therefore, even if the electric motor 24 is not electrically driven, the motor 24 is idling at a certain speed during the operation of the internal combustion engine 10.
[0033]
FIG. 5A is a timing chart for explaining the operation when the control is started by the basic control of the motor control circuit 86 from the state where the electric motor 24 is idling. As described above, when the motor control circuit 86 receives an activation command from the turbo controller 88, the motor control circuit 86 first executes an alignment mode for locking the rotor, and then goes to the run mode via the ramp mode. Therefore, if the motor 24 is idling before the start command is issued to the motor control circuit 86, the motor speed rapidly decreases with the start of the alignment mode, as shown in FIG. 5A. The abrupt decrease in the motor rotational speed described above causes distortion of the rotating shaft 22 and also causes a loss of rotational energy of the turbine 18. Therefore, it is desirable to avoid such a sudden decrease in the rotational speed.
[0034]
FIG. 5B is a timing chart for explaining the operation realized in the system of the present embodiment in order to meet the above request. As shown in this figure, in the system of the present embodiment, when the electric motor 24 has already idled at the time when the electric motor 24 is requested to start assisting the turbocharger unit 16, more strictly, each phase. When the motor 24 is already idling at a speed at which a detectable back electromotive voltage is generated in the coil, the alignment mode and the ramp mode are omitted, and the run mode is directly changed from the idling state.
[0035]
That is, the system of the present embodiment includes the inverter disconnect transistor 90 as described above. When requested to start assisting the turbocharger unit 16 by the electric motor 24, the turbo controller 88 first turns on the inverter disconnect transistor 60 and then issues a start command to the motor control circuit 86. When the inverter disconnection transistor 90 is in the ON state, the six gate signal lines leading to the inverter 60 are uniformly fixed at the ground potential, and as a result, the align mode and the ramp mode are omitted. The turbo controller 88 turns off the inverter disconnect transistor 90 when the motor control circuit 86 starts control in the run mode, that is, when the motor control circuit 86 starts outputting the VCO signal. When the inverter disconnection transistor 90 is turned off, the switching element in the inverter 60 is controlled according to the gate signal issued from the motor control circuit 86, and as a result, the control of the electric motor 24 by the run mode is realized. .
[0036]
Hereinafter, with reference to FIG. 6, the content of the specific process which the turbo controller 88 performs in order to implement | achieve said function is demonstrated.
FIG. 6 is a flowchart of a control routine executed by the turbo controller 88 to control the state of the electric motor 24 in the present embodiment. In the routine shown in FIG. 6, first, it is determined whether or not the assistance of the turbocharger unit 16 by the electric motor 24 is requested (step 100).
[0037]
As a result, when it is determined that the assist by the electric motor 24 is not requested, it is not necessary to drive the electric motor 24, so that the current processing cycle is terminated without any further processing. On the other hand, if it is determined in step 100 that the assist by the electric motor 24 is requested, then whether or not the current processing cycle is performed when the internal combustion engine 10 is started is determined. Specifically, it is determined whether or not the rotational speed of the electric motor 24 currently exceeds a predetermined determination value (step 102).
[0038]
In the present embodiment, the turbo controller 88 requests assistance by the electric motor 24 for the purpose of improving the supercharging response during the operation of the internal combustion engine 10, and also increases the intake air temperature when the internal combustion engine 10 is cold started. However, assistance by the electric motor 24 is requested. If it is determined in step 102 that the internal combustion engine 10 is being started (the rotational speed is equal to or less than the determination value), it can be determined that the assistance by the electric motor 24 is required for the latter purpose. . In that case, since the motor 24 is not idling prior to the start of driving, it can be determined that the rotational speed of the motor 24 should be increased through the align mode and the ramp mode according to the basic control of the motor control circuit 86. . If it is determined in the above step 102 that the internal combustion engine 10 is being started, the processing from step 106 to be described later is immediately executed.
[0039]
On the other hand, if it is determined in step 102 that the internal combustion engine 10 is not being started, the turbocharger unit is used for the purpose of increasing the supercharging pressure in a situation where the electric motor 24 is already idling at a certain speed. It can be determined that 16 assists are requested. In this case, the inverter disconnect transistor 90 is turned on to fix the gate signal to the ground potential (the potential at which the switching element is turned off) (step 104).
[0040]
In the routine shown in FIG. 6, next, a process for starting the motor control circuit 86 is executed (step 106).
When activated by the above processing, the motor control circuit 86 thereafter supplies a predetermined gate signal to the gate signal line in order to realize control in the align mode, the ramp mode, and the run mode. As a result, at the cold start, the rotational speed of the electric motor 24 is increased with the waveform shown in FIG. On the other hand, when the motor 24 has already been idling, as shown in FIG. 5B, the rotational speed of the motor 24 is maintained at the idling speed until the run mode is started.
[0041]
In the routine shown in FIG. 6, next, the rotor position is detected based on whether the motor control circuit 86 has started the control in the run mode, that is, based on the back electromotive voltage generated in each phase coil of the electric motor 24, and the rotor position is determined. Based on this, it is determined whether or not the gate signal has started to be controlled (step 108).
The motor control circuit 86 starts outputting the VCO signal as control in the run mode is started. Therefore, in this step 108, specifically, it is determined whether or not the motor control circuit 86 has started to output the VCO signal.
[0042]
If it is determined in step 108 that the motor control circuit 86 has started control in the run mode, it is then determined whether or not the frequency of the VCO signal is equal to or lower than a predetermined determination value Nf (step 110). ).
[0043]
As described above, the VCO is a signal that changes in a cycle corresponding to the rotational speed of the electric motor 24. On the other hand, the determination value Nf is a determination value for confirming whether or not the electric motor 24 is over-rotating. Therefore, if it is determined in step 110 that the VCO frequency is equal to or lower than the determination value Nf, it can be determined that the electric motor 24 is rotating at an appropriate rotational speed. In this case, thereafter, the inverter disconnect transistor is turned OFF to permit the assist in the run mode, and the fixation of the gate signal to the ground potential is released (step 112).
[0044]
On the other hand, if it is determined in step 110 that the frequency of the VCO signal is not equal to or lower than the determination value Nf, it can be determined that the motor 24 has already over-rotated at that time. In this case, thereafter, the inverter disconnect transistor is turned on to prohibit the assist by the electric motor 24, and the gate signal is fixed to the ground potential (step 114).
[0045]
As described above, according to the routine shown in FIG. 6, when the assist of the turbocharger unit 16 by the electric motor 24 is requested at the cold start, the intake air temperature is appropriately adjusted by following the basic control of the motor control circuit 86. Can be raised. And when the electric assist is requested under the situation where the electric motor 24 is already idling, omitting the alignment mode and the ramp mode without causing the rotation shaft 22 of the turbocharger unit 16 to be distorted. Further, the assist can be started without losing rotational energy. For this reason, according to the system of the present embodiment, the electric assist of the turbocharger unit 16 can always be started smoothly without causing torque fluctuations or abnormal noise.
[0046]
By the way, in Embodiment 1 mentioned above, although the electric motor 24 is limited to what assists the turbocharger unit 16, this invention is not limited to this. That is, the present invention can be widely applied to an apparatus that controls an electric motor that needs to start driving from an idling state.
[0047]
Further, in the first embodiment described above, the motor control circuit 86 is limited to one that executes the alignment mode and the ramp mode prior to the run mode, but the present invention is not limited to this. . That is, the present invention aims to prevent torque change and noise from occurring due to a change in the state of the inverter 60 when starting the driving of the motor 24 during idling, and the rotor position can be detected. Up to that, it is sufficient if the inverter 60 can be maintained in the non-operating state.
[0048]
In the first embodiment described above, the motor control circuit 86 detects the first voltage by detecting the U voltage, the V voltage, and the W voltage at the sampling timings shown in FIGS. 4 (H) to 4 (J). The “back electromotive voltage acquisition means” in the present invention is obtained by the motor control circuit 86 acquiring the rotor position on the basis of the acquired U voltage, V voltage, and W voltage. The motor control circuit 86 changes the gate signal in the patterns shown in FIGS. 4B to 4G, so that the “rotor driving means” in the first aspect of the invention is changed to the turbo controller 88. It is "inverter cutting means" of the invention by executing the processing of 104, a turbo controller 88 performs the above step 11 "Inverter cut release means" is realized, respectively, in the first embodiment is realized by executing the processing.
[0049]
In the first embodiment described above, the motor control circuit 86 performs control in the alignment mode shown in FIG. 3 or the lamp mode, so that the “alignment mode means” and the “lamp mode means” in the third aspect of the invention are used. "Is realized.
[0050]
In the first embodiment described above, the turbo controller 88 executes the process of step 102, so that the “rotation determination means” in the fourth aspect of the invention is the above when the condition of step 102 is satisfied. By jumping the processing of step 104, the “inverter disconnection prohibiting means” in the fourth aspect of the present invention is realized.
[0051]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
According to the first invention, after the electric power drive of the electric motor is requested and before the rotor position is acquired, all the switching elements incorporated in the inverter can be turned off. And a rotor position is acquirable based on the counter electromotive voltage which arises in each phase coil of an electric motor without going through an inverter. For this reason, according to the present invention, the state of each phase coil is not influenced by the state of the inverter until the rotor position is acquired, and the driving of the electric motor can be started smoothly.
[0052]
According to the second invention, it is possible to smoothly drive the electric motor that electrically drives the turbocharger of the internal combustion engine.
[0053]
According to the third aspect, when the electric power drive of the electric motor is requested, the alignment mode and the lamp mode are sequentially executed. According to the present invention, since the switching element in the inverter can be turned off, it is possible to smoothly start the driving of the motor by preventing the current from flowing through each phase coil regardless of the execution of these modes. Can do.
[0054]
According to the fourth invention, when the electric power drive of the electric motor is requested, when the electric motor is not rotating, the switching element in the inverter can be prohibited from being forcibly turned off. Therefore, according to the present invention, when the electric motor is started from a stopped state, a starting behavior corresponding to the state of the inverter can be obtained.
[0055]
According to the fifth aspect, when the electric motor is driven by the rotor driving means, the respective phase coils of the electric motor are sequentially brought into a non-energized state. The rotor position can be reliably detected by sequentially acquiring the counter electromotive voltage generated in the non-energized coil.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the configuration of a first embodiment of the present invention.
FIG. 2 is a block diagram for explaining a configuration provided for driving the electric motor in the system according to the first embodiment of the present invention.
FIG. 3 is a timing chart for explaining basic control of the motor control circuit shown in FIG. 2;
4 is a timing chart for explaining control contents in a run mode executed by the motor control circuit shown in FIG. 2; FIG.
FIG. 5A is a timing chart for explaining a problem associated with controlling an electric motor by basic control. FIG. 5B is a timing chart for explaining the control contents used in the system according to the first embodiment of the present invention to solve the above problem.
FIG. 6 is a flowchart of a control routine executed by the turbo controller shown in FIG. 2 for controlling the electric motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake passage 14 Exhaust passage 16 Turbocharger unit 18 Turbine 20 Compressor 22 Rotating shaft 24 Electric motor 50 ECU (Electronic Control Unit)
52 Controller 54 Battery 60 Inverter 62, 64, 70, 72, 78, 80 Switching element 86 Motor control circuit 88 Turbo controller 90 Inverter switching transistor

Claims (5)

An electric motor control device that drives an electric motor using an inverter,
Back electromotive voltage acquisition means for acquiring back electromotive voltage generated in each phase coil of the electric motor without passing through the inverter;
Rotor position acquisition means for acquiring the rotor position of the electric motor based on the counter electromotive voltage;
Rotor driving means for controlling signals to be supplied to a plurality of switching elements included in the inverter so that the rotor rotates according to the rotor position;
After the electric power drive of the electric motor is requested, until the rotor position is acquired , an inverter disconnecting unit that locks all of the plurality of switching elements in an off state;
Inverter disconnect release means for releasing the off-state lock at the time when the rotor position is acquired
An electric motor control device comprising: 2. The motor control device according to claim 1, wherein the electric motor is for electrically driving a turbocharger of an internal combustion engine. An alignment mode means for controlling a signal supplied to the plurality of switching elements so that the rotor position is locked at a predetermined position when power driving of the electric motor is required;
Ramp mode means for controlling signals supplied to the plurality of switching elements so that the rotational speed of the rotor is increased to a speed at which the rotor position can be acquired after the rotor is locked at the predetermined position;
The motor control device according to claim 1, further comprising: Rotation determination means for determining whether or not the electric motor is rotating when power driving of the electric motor is requested;
When it is determined that the electric motor is not rotating when power driving of the electric motor is requested, an inverter disconnection prohibiting unit that prohibits the operation of the inverter disconnecting unit;
The motor control device according to claim 1, further comprising: The rotor driving means switches signals supplied to the plurality of switching elements so that each phase coil of the electric motor is sequentially in a non-energized state,
5. The motor control device according to claim 1, wherein the counter electromotive voltage acquisition unit sequentially acquires counter electromotive voltages generated in a non-energized coil. 6.

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