Motor-driven oil pump

Abstract

To provide a motor-driven oil pump capable of stably supplying a hydraulic pressure even under a cryogenic environment.SOLUTION: A motor-driven oil pump comprises: an oil pump which discharges oil; a motor which drives the oil pump; and a motor control device which controls the motor. In a case where a measurement value of a third phase current Ic acquired from a current detection circuit exceeds a threshold Ith, specifically, in a case where it is estimated that a viscosity of the oil is in such an extremely high state that a rotor shaft of a motor part cannot be rotated, the motor control device sets a d-axis current command value at a value that is larger than zero.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electric oil pump. [Background technology]

[0002] A hybrid vehicle is equipped with a hydraulic pressure supply device that supplies hydraulic pressure to the transmission. The hydraulic pressure supply device is a mechanical oil pump driven by the driving force of the engine and an electric oil pump driven by a motor. In such a hybrid vehicle, by controlling the motor when the engine is stopped and the mechanical oil pump becomes inoperable, the electric oil pump can supply the hydraulic pressure required for the transmission.

[0003] Patent Document 1 discloses a method for controlling a motor drive device in an electric oil pump when the oil temperature in the transmission is at an extremely low temperature below a predetermined reference temperature. This control method measures the oil temperature in the transmission, and when the oil temperature in the transmission is at an extremely low temperature below the predetermined reference temperature, performs duty control so that the rotation speed of the electric oil pump reaches a target rotation speed, and after duty control, performs feedback control to maintain the target rotation speed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-122310 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, the viscosity of oil in an extremely low-temperature environment (-40°C or below) is extremely high compared to the viscosity of oil in a normal temperature environment. Therefore, if duty control is performed to set the rotation speed of an electric oil pump to a target rotation speed when the oil viscosity is extremely high, as in the technology described in Patent Document 1, the load torque of the motor increases, resulting in an increase in the output current value output from the motor drive device to the motor. The motor drive device is equipped with a fail-safe function that stops the supply of current to the motor if the output current value exceeds an upper limit. Therefore, if the output current value of the motor drive device increases due to extremely high oil viscosity as described above, the fail-safe function will be activated, making it impossible to drive the motor and supply the required hydraulic pressure.

[0006] In view of the above circumstances, an object of the present invention is to provide an electric oil pump that can stably supply oil pressure even in an extremely low temperature environment. [Means for solving the problem]

[0007] One aspect of the electric oil pump of the present invention includes an oil pump that discharges oil, a motor that drives the oil pump, and a motor control device that controls the motor, and when a measured value of a phase current of the motor exceeds a threshold value, the motor control device sets a d-axis current command value to a value greater than zero. [Effects of the Invention]

[0008] According to the above aspect of the present invention, an electric oil pump is provided that can stably supply oil pressure even in an extremely low temperature environment. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram that schematically shows an electric oil pump according to this embodiment. [Figure 2] FIG. 2 is a diagram schematically showing a cross section of the motor section and the oil pump section. [Figure 3]FIG. 3 is a flowchart showing each process executed by the motor control device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing a schematic diagram of an electric oil pump 100 according to this embodiment. As shown in Fig. 1, the electric oil pump 100 includes a motor control device 10, a motor unit 20, and an oil pump unit 30. The electric oil pump 100 is a device that supplies cooling oil F to a drive motor mounted on, for example, a hybrid vehicle.

[0011] The motor unit 20 drives the oil pump unit 30. The motor unit 20 is, for example, an inner rotor type three-phase brushless DC motor. The motor unit 20 has a rotor shaft 21, a first terminal 22a, a second terminal 22b, a third terminal 22c, a first coil 23, a second coil 24, and a third coil 25.

[0012] 2, the motor unit 20 has a rotor 26 and a stator 27 housed in a motor housing (not shown). The rotor 26 is a rotating body rotatably supported by bearing components inside the motor housing. The stator 27 is fixed inside the motor housing while surrounding the outer circumferential surface of the rotor 26, and generates the electromagnetic force required to rotate the rotor 26.

[0013] The rotor shaft 21 is an axial body that penetrates the radially inner side of the rotor 26 in the axial direction and is coaxially joined to the rotor 26. The first terminal 22a, the second terminal 22b, and the third terminal 22c are each metal terminals exposed from the surface of the motor housing. As will be described in detail later, the first terminal 22a, the second terminal 22b, and the third terminal 22c are each electrically connected to the drive circuit 11 of the motor control device 10. The first coil 23, the second coil 24, and the third coil 25 are each excitation coils provided in the stator 27. In FIG. 2, only the first coil 23 is shown as a representative example.

[0014] As shown in FIG. 1 , for example, the first coil 23, the second coil 24, and the third coil 25 are delta-connected inside the motor unit 20. One end of the first coil 23 is electrically connected to the first terminal 22a. The other end of the first coil 23 is electrically connected to the second terminal 22b. One end of the second coil 24 is electrically connected to the first terminal 22a. The other end of the second coil 24 is electrically connected to the third terminal 22c. One end of the third coil 25 is electrically connected to the second terminal 22b. The other end of the third coil 25 is electrically connected to the third terminal 22c. The energized states of the first coil 23, the second coil 24, and the third coil 25 are controlled by the motor control device 10, thereby generating an electromagnetic force required to rotate the rotor 26. As the rotor 26 rotates, the rotor shaft 21 also rotates in synchronization with the rotor 26.

[0015] The oil pump unit 30 is located on one axial side of the rotor shaft 21 of the motor unit 20, and is driven by the motor unit 20 via the rotor shaft 21. When the oil pump unit 30 is driven by the motor unit 20, the oil pump unit 30 discharges cooling oil F. The oil pump unit 30 has an oil suction port 31 and an oil discharge port 32. The cooling oil F is drawn into the oil pump unit 30 from the oil suction port 31, and then discharged from the oil discharge port 32 to the outside of the oil pump unit 30. In this way, the oil pump unit 30 and the motor unit 20 are connected adjacent to each other in the axial direction of the rotor shaft 21.

[0016] As shown in FIG. 2, the oil pump unit 30 includes an inner rotor 33 attached to the rotor shaft 21 and an outer rotor 34 surrounding the inner rotor 33. The inner rotor 33 and the outer rotor 34 are eccentrically disposed inside a pump case (not shown). The number of teeth on the outer rotor 34 is one more than the number of teeth on the inner rotor 33, and a sealed space is formed by the tooth tips of the inner rotor 33 and the outer rotor 34. When the inner rotor 33 is rotated via the rotor shaft 21, the outer rotor 34, whose outer diameter is constrained inside the pump case, receives a rotational force by meshing with the inner rotor 33 and rotates in the same direction as the inner rotor 33. Focusing on one sealed space, the volume of the sealed space gradually increases as the inner rotor 33 and the outer rotor 34 rotate, and then gradually decreases after reaching a maximum volume, repeating this process. As shown in Figure 2, this operation causes oil F to be sucked in through the intake port in the region where the volume is expanding, the oil F is temporarily separated from the intake port and discharge port in the region where the volume is maximum, and the oil F is discharged from the discharge port in the region where the volume is shrinking.

[0017] 2, some of the oil F discharged from the oil pump unit 30 flows along the rotor shaft 21 into the motor unit 20. As will be described in detail later, the motor control device 10 of this embodiment has the function of causing the motor unit 20 to generate heat by controlling the d-axis current command value. In other words, the oil F that has flowed into the motor unit 20 is heated by the motor unit 20.

[0018] Returning to Figure 1, the following description will continue. Motor control device 10 controls motor unit 20 based on a rotation speed command signal CS input from a higher-level control device (not shown). As an example, the higher-level control device is an on-board ECU (Electronic Control Unit) installed in a hybrid vehicle. Motor control device 10 includes a drive circuit 11, a current detection circuit 12, a control unit 13, and a storage unit 14.

[0019] The drive circuit 11 is driven by a DC power supply voltage V MThe drive circuit 11 converts the DC power supply voltage V supplied from the DC power supply 200 into a three-phase AC voltage and supplies it to the motor unit 20. M The DC power supply 200 is one of a plurality of batteries mounted on a hybrid vehicle, and outputs a DC power supply voltage V of 12 V to a 12 V in-vehicle system, for example. M supply.

[0020] The drive circuit 11 includes a first high-side switch Q1, a second high-side switch Q2, a third high-side switch Q3, a first low-side switch Q4, a second low-side switch Q5, and a third low-side switch Q6. In this embodiment, each switch included in the drive circuit 11 is, for example, an N-channel MOS-FET.

[0021] The drain terminal of the first high-side switch Q1, the drain terminal of the second high-side switch Q2, and the drain terminal of the third high-side switch Q3 are each electrically connected to the positive terminal of the DC power supply 200. The source terminal of the first low-side switch Q4, the source terminal of the second low-side switch Q5, and the source terminal of the third low-side switch Q6 are each electrically connected to the negative terminal of the DC power supply 200. The negative terminal of the DC power supply 200 is electrically connected to the in-vehicle ground.

[0022] The source terminal of the first high-side switch Q1 is electrically connected to the first terminal 22a of the motor unit 20 and the drain terminal of the first low-side switch Q4. The source terminal of the second high-side switch Q2 is electrically connected to the second terminal 22b of the motor unit 20 and the drain terminal of the second low-side switch Q5. The source terminal of the third high-side switch Q3 is electrically connected to the third terminal 22c of the motor unit 20 and the drain terminal of the third low-side switch Q6.

[0023] In the following description, the wiring connecting the source terminal of the first high-side switch Q1 and the first terminal 22a of the motor unit 20 may be referred to as the first wiring. The wiring connecting the source terminal of the second high-side switch Q2 and the second terminal 22b of the motor unit 20 may be referred to as the second wiring. The wiring connecting the source terminal of the third high-side switch Q3 and the third terminal 22c of the motor unit 20 may be referred to as the third wiring.

[0024] The gate terminal of the first high-side switch Q1, the gate terminal of the second high-side switch Q2, and the gate terminal of the third high-side switch Q3 are each electrically connected to the control unit 13. The gate terminal of the first low-side switch Q4, the gate terminal of the second low-side switch Q5, and the gate terminal of the third low-side switch Q6 are also each electrically connected to the control unit 13.

[0025] As described above, the drive circuit 11 is configured as a three-phase full-bridge circuit having three high-side switches and three low-side switches. The drive circuit 11 configured in this manner is configured to convert the DC power supply voltage V supplied from the DC power supply 200 into a voltage V by controlling the switching of each switch by the control unit 13. M is converted into a three-phase AC voltage and output to the motor unit 20.

[0026] The current detection circuit 12 is a circuit that detects three-phase currents of the motor unit 20. In Fig. 1, the current detection circuit 12 is directly connected to each of the first wiring, the second wiring, and the third wiring, but in reality, the current detection circuit 12 is connected to a magnetic current sensor (not shown) arranged on each wiring.

[0027] Current detection circuit 12 measures a first phase current Ia flowing through the first wiring based on the output signal of a magnetic current sensor arranged in the first wiring and outputs the measured value to control unit 13. Current detection circuit 12 measures a second phase current Ib flowing through the second wiring based on the output signal of a magnetic current sensor arranged in the second wiring and outputs the measured value to control unit 13. Current detection circuit 12 measures a third phase current Ic flowing through the third wiring based on the output signal of a magnetic current sensor arranged in the third wiring and outputs the measured value to control unit 13. The current detection circuit 12 may detect three-phase currents based on the voltages of shunt resistors instead of using magnetic current sensors.

[0028] The control unit 13 is, for example, a microprocessor such as an MCU (Microcontroller Unit). A rotation speed command signal CS output from a higher-level control device (not shown) is input to the control unit 13. The rotation speed command signal CS is a signal that indicates a target rotation speed of the motor unit 20. The control unit 13 is communicably connected to the storage unit 14 via a communication bus (not shown). The control unit 13 performs switching control of each switch included in the drive circuit 11 in accordance with a program pre-stored in the storage unit 14 so that the motor unit 20 rotates at the target rotation speed indicated by the rotation speed command signal CS.

[0029] The storage unit 14 includes a nonvolatile memory that stores programs and various setting data required for the control unit 13 to execute various processes, and a volatile memory that is used as a temporary storage destination for data when the control unit 13 executes various processes. The nonvolatile memory is, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory. The volatile memory is, for example, a RAM (Random Access Memory).

[0030] 3 is a flowchart showing each process executed by control unit 13 of motor control device 10. Control unit 13 executes a program stored in storage unit 14 to execute each process shown in FIG.

[0031] 3, the control unit 13 first receives a start command from a higher-level control device (step S1). When the control unit 13 receives the start command from the higher-level control device, it starts operating in a first mode (first control) (step S2). The first mode is a mode in which the motor unit 20 is controlled based on a first rotation speed command value when the oil pump unit 30 is started. The first rotation speed command value is included in a rotation speed command signal CS transmitted from the higher-level control device.

[0032] As an example, the control unit 13 controls the motor unit 20 by vector control. Since the vector control is generally known as a control method for the motor unit 20, which is a three-phase brushless DC motor, the vector control will be briefly described in this embodiment. The vector control can be briefly described as follows.

[0033] The control unit 13 acquires the measured values ​​of the first phase current Ia, the second phase current Ib, and the third phase current Ic from the current detection circuit 12. The control unit 13 converts the measured values ​​of the first phase current Ia, the second phase current Ib, and the third phase current Ic into two-phase currents Iα and Iβ in a fixed coordinate system using Clarke transformation.

[0034] The control unit 13 converts the two-phase currents Iα and Iβ in the fixed coordinate system into a d-axis current Id and a q-axis current Iq in the rotating coordinate system by Park transformation based on the following equations (1) and (2). R " and the rotation angle θ obtained by the sensorless method R The measured value is used. Id=Iα·cosθ R +Iβ sinθ R …(1) Iq=-Iα·sinθ R +Iβ cosθ R …(2)

[0035] The control unit 13 calculates the d-axis current Id and the d-axis current command value Id REF The d-axis voltage command value Vd that makes the deviation from the d-axis current command value Id zero is calculated by PI calculation. REF is a fixed value, i.e., zero.

[0036] The control unit 13 calculates the q-axis current Iq and the q-axis current command value Iq REF The control unit 13 calculates the q-axis voltage command value Vq by PI calculation, so that the deviation from the first rotation speed command value is zero. REF For example, the control unit 13 calculates the q-axis current command value Iq at which the deviation between the measured rotation speed obtained by the sensorless method and the first rotation speed command value becomes zero. REF is calculated by PI calculation.

[0037] The control unit 13 inversely transforms the d-axis voltage command value Vd and the q-axis voltage command value Vq in the rotating coordinate system into two-phase voltage values ​​Vα and Vβ in the fixed coordinate system by inverse Park transformation based on the following equations (3) and (4). R " and the rotation angle θ obtained by the sensorless method R The measured value is used. Vα=Vd·cosθ R -Vq sinθ R …(3) Vβ=Vd·sinθ R +Vq cosθ R …(4)

[0038] The control unit 13 performs inverse conversion of the two-phase voltage values ​​Vα and Vβ into three-phase voltages by space vector conversion. The control unit 13 controls the switching of six switches included in the drive circuit 11 so that the three-phase voltages obtained by the space vector conversion are supplied to the motor unit 20. By performing the vector control as described above, a three-phase voltage for rotating the motor unit 20 at a rotation speed corresponding to the first rotation speed command value is supplied from the drive circuit 11 to the motor unit 20.

[0039] While performing the vector control as described above, the control unit 13 determines whether the measurement value of the third phase current Ic acquired from the current detection circuit 12 exceeds the threshold value Ith (step S3). If the measurement value of the third phase current Ic is equal to or less than the threshold value Ith (step S3: NO), the control unit 13 proceeds to step S4, which will be described later. On the other hand, if the measurement value of the third phase current Ic exceeds the threshold value Ith (step S3: YES), the control unit 13 proceeds to step S5, which will be described later.

[0040] Here, for example, the viscosity of oil F in an extremely low-temperature environment of -40°C or below is extremely high compared to the viscosity of oil F in a room-temperature environment. Therefore, if vector control is performed so that the rotation speed of motor unit 20 matches the first rotation speed command value when the viscosity of oil F is extremely high, the load torque of motor unit 20 increases, and as a result, the measured value of third-phase current Ic increases to the point where it exceeds threshold value Ith. In other words, if the measured value of third-phase current Ic exceeds threshold value Ith, it is inferred that the viscosity of oil F is extremely high. On the other hand, if the measured value of third-phase current Ic is equal to or lower than threshold value Ith, it is inferred that the viscosity of oil F is relatively low.

[0041] As described above, when the measured value of the third-phase current Ic is equal to or less than the threshold value Ith (step S3: NO), that is, when it is estimated that the viscosity of the oil F is relatively low, the control unit 13 proceeds to step S4, which will be described later. In this case, the control unit 13 determines whether or not a pump stop command has been received from a higher-level control device (step S4).

[0042] If the control unit 13 determines that it has not received a pump stop command (step S4: NO), it returns to step S3 and continues operating in the first mode. On the other hand, if the control unit 13 determines that it has received a pump stop command (step S4: YES), it stops controlling the motor unit 20, i.e., stops driving the oil pump unit 30, and then ends the processing shown in FIG. 3. In this way, when it is estimated that the viscosity of the oil F is relatively low, the control unit 13 operates in the first mode until it receives a pump stop command from the upper control device. As a result, the rotation speed of the motor unit 20 increases to a rotation speed that matches the first rotation speed command value.

[0043] As described above, when the measured value of the third-phase current Ic exceeds the threshold value Ith (step S3: YES), that is, when it is estimated that the viscosity of the oil F is extremely high, the control unit 13 proceeds to step S5, which will be described later. In this case, the control unit 13 starts operation in the second mode (second control) (step S5). The second mode is a mode in which the motor unit 20 is controlled based on a second rotation speed command value, which is a rotation speed equal to or less than the first rotation speed command value. For example, the second rotation speed command value is half the value of the first rotation speed command value. The second rotation speed command value may be a value calculated by the control unit 13 or may be a value stored in advance in the storage unit 14.

[0044] Motor control device 10 is provided with a fail-safe function that stops the supply of current to motor unit 20 when the output current value exceeds an upper limit. Therefore, if the output current value of motor control device 10 increases due to the extremely high viscosity of oil F as described above, the fail-safe function will be activated, making it impossible to drive motor unit 20 and supply the necessary hydraulic pressure. Therefore, when it is estimated that the viscosity of oil F is extremely high as described above, control unit 13 operates in the second mode, which controls motor unit 20 based on a second rotation speed command value that is equal to or lower than the first rotation speed command value, thereby suppressing the output current value of motor control device 10 and preventing the fail-safe function from being activated.

[0045] While performing vector control during operation in the second mode, the control unit 13 determines whether the measurement value of the third-phase current Ic acquired from the current detection circuit 12 exceeds the threshold value Ith (step S6). If the measurement value of the third-phase current Ic is equal to or less than the threshold value Ith (step S6: NO), the control unit 13 proceeds to step S7, which will be described later. On the other hand, if the measurement value of the third-phase current Ic exceeds the threshold value Ith (step S6: YES), the control unit 13 proceeds to step S8, which will be described later.

[0046] If the measured value of the third-phase current Ic exceeds the threshold value Ith even after switching from the first mode to the second mode, it is assumed that the viscosity of the oil F is so extremely high that the rotor shaft 21 of the motor unit 20 cannot rotate. On the other hand, if the measured value of the third-phase current Ic is equal to or less than the threshold value Ith while operating in the second mode, it is assumed that the viscosity of the oil F is relatively low and the motor unit 20 is rotating at a rotation speed close to the second rotation speed command value.

[0047] As described above, when the measured value of the third-phase current Ic is equal to or less than the threshold value Ith during operation in the second mode (step S6: NO), that is, when it is estimated that the viscosity of the oil F is relatively low and the motor unit 20 is rotating at a rotation speed close to the second rotation speed command value, the control unit 13 proceeds to step S7, which will be described later. In this case, the control unit 13 determines whether a predetermined time has elapsed since the start of operation in the second mode (step S7).

[0048] If the control unit 13 determines that the predetermined time has not elapsed (step S7: NO), it returns to step S6 and continues operation in the second mode. On the other hand, if the control unit 13 determines that the predetermined time has elapsed (step S7: YES), it returns to step S2 and starts operation in the first mode again. In this way, if it is estimated that the viscosity of the oil F is relatively low and the motor unit 20 is rotating at a rotation speed close to the second rotation speed command value, the control unit 13 continues operation in the second mode until the predetermined time has elapsed since starting operation in the second mode.

[0049] It is estimated that after a predetermined time has passed, the viscosity of oil F will decrease significantly due to heat generated by the hybrid vehicle's engine. Therefore, even if the first mode is switched back to and motor unit 20 is controlled based on the first rotation speed command value after the predetermined time has passed, the output current value will not increase enough to activate the fail-safe function. Therefore, by switching from the second mode to the first mode after a predetermined time has passed since starting operation in the second mode, the rotation speed of motor unit 20 can be increased to a rotation speed that matches the first rotation speed command value instructed by the upper control device.

[0050] As described above, when the control unit 13 is operating in the second mode, if the measured value of the third-phase current Ic exceeds the threshold value Ith (step S6: YES), that is, if it is estimated that the viscosity of the oil F is so extremely high that the rotor shaft 21 of the motor unit 20 cannot rotate, the control unit 13 proceeds to step S8, which will be described later. In this case, the control unit 13 determines whether the d-axis current command value Id REF is set to a value greater than zero (step S8).

[0051] In normal vector control, in order to maximize the efficiency of the motor unit 20, the d-axis current command value Id REF is fixed to zero. The d-axis current command value Id REF If the d-axis current command value Id is changed to a value greater than zero, the efficiency of the motor unit 20 deteriorates, and the motor unit 20 generates heat. REF The oil F is heated by utilizing the heat generated by the motor unit 20 when the d-axis current command value Id REF By setting the value of the oil F to be greater than zero, the oil F that has entered the inside of the motor section 20 is heated by the motor section 20.

[0052] For example, in step S8, the control device 13 calculates the d-axis current command value Id by multiplying the sum of the difference ΔIc between the measured value of the third-phase current Ic and the predetermined current value Is and the integral value of the difference ΔIc by a proportionality coefficient kp. REF The difference ΔIc is expressed by the following equation (5), and the d-axis current command value Id REF is expressed by the following equation (6): For example, the predetermined current value Is is preferably the same as the threshold value Ith, but may be a value different from the threshold value Ith.

[0053]

number

[0054] As can be seen from the above equations (5) and (6), the more the measured value of the third-phase current Ic deviates from the predetermined current value Is (the higher the viscosity of the oil F), the more the d-axis current command value Id REF On the other hand, the closer the measured value of the third-phase current Ic is to the predetermined current value Is (the lower the viscosity of the oil F), the closer the d-axis current command value Id REF Since the value of the third-phase current Ic is low, the oil F is heated with a relatively small amount of heat. In this way, the oil F is heated with an appropriate amount of heat depending on the viscosity of the oil F (the difference ΔIc between the measured value of the third-phase current Ic and the predetermined current value Is), so the power consumption during heating can be reduced.

[0055] The control unit 13 determines a d-axis current command value Id REF While performing vector control based on the d-axis current command value Id, the control unit 13 determines whether the measured value of the third-phase current Ic acquired from the current detection circuit 12 is equal to or less than the threshold value Ith (step S9). If the measured value of the third-phase current Ic is greater than the threshold value Ith (step S9: NO), the control unit 13 REF It is determined whether a predetermined time has elapsed since the time when the value of the variable is set to a value greater than zero (step 10).

[0056] If the control unit 13 determines that the predetermined time has not elapsed (step S10: NO), the control unit 13 returns to step S8. On the other hand, if the control unit 13 determines that the predetermined time has elapsed (step S10: YES), the control unit 13 returns to step S8. REF is returned to a fixed value, i.e., zero (step S11). REF After resetting it to zero, the process returns to step S2 and starts operation in the first mode again.

[0057] d-axis current command value Id greater than zero REF If the measured value of the third-phase current Ic is greater than the threshold value Ith while vector control is being performed based on the d-axis current command value Id REF If it is estimated that the viscosity of the oil F is still relatively high while vector control is being performed based on REF is set to a value greater than zero until a predetermined time has elapsed. REF Vector control continues based on

[0058] It is estimated that after a predetermined time has passed, the viscosity of the oil F will be significantly reduced due to the heat generated by the engine of the hybrid vehicle being added to the heat generated by the motor unit 20. Therefore, after a predetermined time has passed, the d-axis current command value Id REF Even if the d-axis current command value Id is reset to zero, the mode is switched to the first mode, and the motor unit 20 is controlled based on the first rotation speed command value, the output current value does not increase to the extent that the fail-safe function is activated. REF By switching from the second mode to the first mode after a predetermined time has elapsed since the value is set to a value greater than zero, the rotation speed of the motor unit 20 can be increased to a rotation speed that matches the first rotation speed command value instructed by the upper control device.

[0059] If the measured value of the third-phase current Ic is equal to or smaller than the threshold value Ith (step S9: YES), the control unit 13 sets the d-axis current command value Id REFis reset to zero (step S11), and then the process returns to step S2 to start operation in the first mode again.

[0060] d-axis current command value Id greater than zero REF If the measured value of the third-phase current Ic becomes equal to or less than the threshold value Ith while vector control is being performed based on the d-axis current command value Id, it is no longer necessary to heat the oil F. Therefore, in this case, the d-axis current command value Id is set to the value Id without waiting for the lapse of a predetermined time. REF Even if the d-axis current command value Id is reset to zero, the mode is switched to the first mode, and the motor unit 20 is controlled based on the first rotation speed command value, the output current value does not increase to the extent that the fail-safe function is activated. REF If the measured value of the third-phase current Ic becomes equal to or less than the threshold value Ith before a predetermined time has elapsed since the time when Ic is set to a value greater than zero, the rotation speed of the motor unit 20 can be quickly increased to a rotation speed that matches the first rotation speed command value instructed by the upper control device by switching from the second mode to the first mode.

[0061] As described above, the electric oil pump 100 of this embodiment includes the oil pump section 30 that discharges the oil F, the motor section 20 that drives the oil pump section 30, and the motor control device 10 that controls the motor section 20. When the measured value of the third-phase current Ic of the motor section 20 exceeds the threshold value Ith, the motor control device 10 controls the d-axis current command value Id REF Set to a value greater than zero. According to this embodiment, the oil F can be heated simply by changing the control algorithm without adding components such as a temperature sensor and a heater, and therefore, an electric oil pump 100 is provided that can stably supply oil pressure even in an extremely low temperature environment. Also, according to this embodiment, the oil F can be heated while the motor section 20 is rotating (while the oil F is being discharged from the oil pump section 30). Alternatively, the oil F can be heated without rotating the motor section 20. Furthermore, according to this embodiment, the d-axis current command value Id REF The amount of heat generated can be adjusted by changing the setting value.

[0062] In the electric oil pump 100 of this embodiment, the motor control device 10 operates in a first mode in which the motor unit 20 is controlled based on a first rotation speed command value when the oil pump unit 30 is started, and when the measured value of the third-phase current Ic exceeds a threshold value Ith while operating in the first mode, the motor control device 10 switches to a second mode in which the motor unit 20 is controlled based on a second rotation speed command value that is equal to or less than the first rotation speed command value, and when the measured value of the third-phase current Ic exceeds the threshold value Ith while operating in the second mode, the motor control device 10 switches to a second mode in which the motor unit 20 is controlled based on a second rotation speed command value that is equal to or less than the first rotation speed command value. REF Set to a value greater than zero. According to this embodiment, even if the motor unit 20 does not rotate when the oil pump unit 30 is started and controlled based on the first rotation speed command value, the motor unit 20 can be controlled based on the second rotation speed command value, thereby preventing the fail-safe function from operating and heating the oil F while rotating the motor unit 20 as much as possible (while discharging the oil F from the oil pump unit 30).

[0063] In the electric oil pump 100 of this embodiment, the motor control device 10 calculates the d-axis current command value Id REF After a predetermined time has elapsed since the time when is set to a value greater than zero, the mode is switched from the second mode to the first mode. d-axis current command value Id REF It is estimated that after a predetermined time has elapsed since the d-axis current command value Id is set to a value greater than zero, the viscosity of the oil F will drop considerably due to the addition of heat generated by the engine of the hybrid vehicle to the heat generated by the motor unit 20. Therefore, even if the second mode is switched to the first mode after the predetermined time has elapsed and the motor unit 20 is controlled based on the first rotation speed command value, the output current value will not increase to the extent that the fail-safe function will be activated. Therefore, REF By switching from the second mode to the first mode after a predetermined time has elapsed since the value is set to a value greater than zero, the rotation speed of the motor unit 20 can be increased to a rotation speed that matches the first rotation speed command value instructed by the upper control device.

[0064] In the electric oil pump 100 of this embodiment, the motor control device 10 switches from the second mode to the first mode if the measured value of the third phase current Ic becomes equal to or less than the threshold value Ith before a predetermined time has elapsed from the time the d-axis current command value is set to a value greater than zero. d-axis current command value Id greater than zero REF If the measured value of the third-phase current Ic becomes equal to or less than the threshold value Ith while vector control is being performed based on the d-axis current command value Id, it is no longer necessary to heat the oil F. Therefore, in this case, even if the mode is switched from the second mode to the first mode without waiting for the lapse of a predetermined time and the motor unit 20 is controlled based on the first rotation speed command value, the output current value will not increase to the extent that the fail-safe function is activated. REF If the measured value of the third-phase current Ic becomes equal to or less than the threshold value Ith before a predetermined time has elapsed since the time when Ic is set to a value greater than zero, the rotation speed of the motor unit 20 can be quickly increased to a rotation speed that matches the first rotation speed command value instructed by the upper control device by switching from the second mode to the first mode.

[0065] In the electric oil pump 100 of this embodiment, the motor control device 10 calculates the d-axis current command value Id by multiplying the sum of the difference ΔIc between the measured value of the third-phase current Ic and the predetermined current value Is and the integral value of the difference ΔIc by a proportionality coefficient kp. REF Set as. The more the measured value of the third-phase current Ic deviates from the predetermined current value Is (the higher the viscosity of the oil F), the greater the d-axis current command value Id REF On the other hand, the closer the measured value of the third-phase current Ic is to the predetermined current value Is (the lower the viscosity of the oil F), the closer the d-axis current command value Id REF Since the value of the third-phase current Ic is low, the oil F is heated with a relatively small amount of heat. In this way, the oil F is heated with an appropriate amount of heat depending on the viscosity of the oil F (the difference ΔIc between the measured value of the third-phase current Ic and the predetermined current value Is), so the power consumption during heating can be reduced.

[0066] [Variations] The present invention is not limited to the above-described embodiment, and the configurations described in this specification can be combined as appropriate within the scope of not mutually contradicting each other. For example, the following modifications can be made.

[0067] For example, in the above embodiment, the motor control device 10 calculates the d-axis current command value Id REF In this embodiment, the motor control device 10 is configured to switch from the second mode to the first mode after a predetermined time has elapsed since the d-axis current command value was set to a value greater than zero. Alternatively, the motor control device 10 may be configured to switch from the second mode to the first mode when the measured value of the third-phase current Ic becomes equal to or less than the threshold value Ith after the d-axis current command value is set to a value greater than zero. If the mode is switched to the first mode based solely on the elapsed time, there is a possibility that the motor unit 20 will be controlled in a state where the measured value of the third-phase current Ic is not equal to or less than the threshold value Ith (when the viscosity of the oil F is high). Therefore, by switching from the second mode to the first mode when the measured value of the third-phase current Ic is equal to or less than the threshold value Ith, the motor unit 20 can be controlled more reliably in a state where the viscosity of the oil F is low.

[0068] In the above embodiment, an electric oil pump 100 that supplies cooling oil F to a drive motor mounted on a hybrid vehicle is exemplified as an electric oil pump of the present invention, but the electric oil pump of the present invention is not limited to this, and the present invention can also be applied to, for example, an electric oil pump that supplies oil to a transmission.

[0069] The present technology can be configured as follows. (1) An electric oil pump comprising an oil pump that discharges oil, a motor that drives the oil pump, and a motor control device that controls the motor, wherein the motor control device sets a d-axis current command value to a value greater than zero when a measured value of a phase current of the motor exceeds a threshold value. (2) The electric oil pump according to (1), wherein the motor control device operates in a first mode in which the motor is controlled based on a first rotation speed command value when the oil pump is started, and when the measured value of the phase current exceeds the threshold value while operating in the first mode, the motor control device switches to a second mode in which the motor is controlled based on a second rotation speed command value that is equal to or less than the first rotation speed command value, and when the measured value of the phase current exceeds the threshold value while operating in the second mode, the motor control device sets the d-axis current command value to a value greater than zero. (3) The electric oil pump described in (2), wherein the motor control device switches from the second mode to the first mode after a predetermined time has elapsed from the point in time when the d-axis current command value is set to a value greater than zero. (4) The electric oil pump described in (3), wherein the motor control device switches from the second mode to the first mode when the measured value of the phase current becomes equal to or less than the threshold value before the predetermined time has elapsed from the time when the d-axis current command value is set to a value greater than zero. (5) The electric oil pump described in (2), wherein the motor control device switches from the second mode to the first mode when the measured value of the phase current becomes equal to or less than the threshold value after setting the d-axis current command value to a value greater than zero. (6) An electric oil pump according to any one of (1) to (5), wherein the motor control device sets the d-axis current command value to a value obtained by multiplying the sum of the difference between the measured value of the phase current and a predetermined current value and the integral value of the difference by a proportionality coefficient. [Explanation of symbols]

[0070] 10...motor control device, 11...drive circuit, 12...current detection circuit, 13...control unit, 14...storage unit, 20...motor unit, 30...oil pump unit, 100...electric oil pump, 200...DC power supply, F...cooling oil

Claims

1. an oil pump that discharges oil; a motor that drives the oil pump; a motor control device that controls the motor; Equipped with the motor control device sets a d-axis current command value to a value greater than zero when a measured value of the phase current of the motor exceeds a threshold value. Electric oil pump.

2. The motor control device includes: When the oil pump is started, the motor is controlled in a first mode based on a first rotation speed command value; when the measured value of the phase current exceeds the threshold value during operation in the first mode, switching to a second mode in which the motor is controlled based on a second rotation speed command value that is equal to or less than the first rotation speed command value; When the measured value of the phase current exceeds the threshold value during operation in the second mode, the d-axis current command value is set to a value greater than zero. The electric oil pump according to claim 1 .

3. the motor control device switches from the second mode to the first mode after a predetermined time has elapsed since the d-axis current command value was set to a value greater than zero. The electric oil pump according to claim 2.

4. the motor control device switches from the second mode to the first mode when the measured value of the phase current becomes equal to or less than the threshold value before the predetermined time has elapsed from the time when the d-axis current command value is set to a value greater than zero. The electric oil pump according to claim 3.

5. the motor control device switches from the second mode to the first mode when the measured value of the phase current becomes equal to or less than the threshold value after setting the d-axis current command value to a value greater than zero; The electric oil pump according to claim 2.

6. the motor control device sets, as the d-axis current command value, a value obtained by multiplying the sum of a difference between the measured value of the phase current and a predetermined current value and an integral value of the difference by a proportionality coefficient; The electric oil pump according to any one of claims 1 to 5.

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