Motor control device and electric pump device

Abstract

A motor control device and an electric pump device are provided. The motor control device controls a motor of an electric pump, and has a drive section that supplies a drive current to the motor, a control section that controls the drive section in accordance with a rotational speed command value, thereby controlling a rotational speed of the motor, and a current detection section that detects the drive current supplied to the motor, and supplies a current detection value that indicates a detection result of the drive current to the control section, the control section determining whether or not a heterogeneous fluid intake abnormality has occurred in the electric pump in accordance with a first current detection value acquired at a first timing at which the rotational speed command value changes from a first command value to a second command value, and a second current detection value acquired after the first timing.

Description

Technical Field

[0001] This invention relates to motor control devices and electric pump devices. Background Technology

[0002] Patent document 1 discloses a power conversion device that integrates the current values ​​of each phase of a motor and determines that the current detection system of the phase whose integrated value is above a reference value has malfunctioned.

[0003] Patent Document 1: Japanese Patent Application Publication No. 11-289795

[0004] In the technology of the aforementioned Patent Document 1, when the change in the current value of each phase deviates from the normal change in the current value as the speed increases, the abnormality cannot be detected quickly, which may lead to the failure of the electric pump. Summary of the Invention

[0005] One aspect of the present invention is a motor control device that controls the motor of an electric pump, wherein the motor control device comprises: a drive unit that provides a drive current to the motor; a control unit that controls the drive unit according to a speed command value, thereby controlling the speed of the motor; and a current detection unit that detects the drive current supplied to the motor and provides a current detection value representing the detection result of the drive current to the control unit, wherein the control unit determines whether the electric pump has experienced an abnormal intake of foreign fluid based on a first current detection value obtained at a first time when the speed command value changes from a first command value to a second command value and a second current detection value obtained after the first time.

[0006] One aspect of the present invention is an electric pump device comprising: an electric pump; and a motor control device of the above-described manner, which controls the motor of the electric pump.

[0007] According to the above-described manner of the present invention, a motor control device and an electric pump device are provided that are capable of detecting abnormal situations in which a foreign fluid is sucked into an electric pump. Attached Figure Description

[0008] Figure 1 This is a schematic block diagram of an electric pump device having the motor control device of this embodiment.

[0009] Figure 2 This is a flowchart showing the first pump malfunction diagnosis process performed by the control unit when the motor is in a stable rotational state.

[0010] Figure 3 This is the first example of a graph showing the time variation of the speed command value, the actual speed, and the current detection value.

[0011] Figure 4 This is a flowchart showing the second pump malfunction diagnosis process performed by the control unit when the motor is in a stable rotational state.

[0012] Figure 5 This is the second example of a graph showing the time-varying changes in the speed command value, actual speed, and current detection value.

[0013] Label Explanation

[0014] 10: Motor control device; 11: Motor drive circuit (drive unit); 12: Shunt resistor (current detection unit); 13: Control unit; 14: Storage unit; 20: Motor; 30: Pump; 40: Electric pump; 100: Electric pump device; 200: DC power supply; F: Cooling oil. Detailed Implementation

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic block diagram of an electric pump device 100 having the motor control device 10 of this embodiment. Figure 1 As shown, the electric pump unit 100 includes a motor control unit 10 and an electric pump 40. The electric pump 40 includes a motor 20 and a pump 30. The electric pump unit 100 is, for example, a device that supplies cooling oil F to a drive motor mounted in a hybrid vehicle.

[0017] The motor 20 of the electric pump 40 is, for example, an internal rotor type three-phase brushless DC motor. The motor 20 has a shaft 21, a U-phase terminal 22u, a V-phase terminal 22v, a W-phase terminal 22w, a U-phase coil 23u, a V-phase coil 23v, a W-phase coil 23w, and a rotation angle sensor 24.

[0018] In addition, although Figure 1 The diagram is omitted, but motor 20 has a motor housing and a rotor and stator housed within the motor housing. The rotor is a rotating body supported by bearing components inside the motor housing. The stator is fixed inside the motor housing in a manner that surrounds the outer circumference of the rotor, generating the electromagnetic force required to rotate the rotor.

[0019] Shaft 21 is a shaft-like body coaxially engaged with the rotor, extending radially inward along the rotor axis. The U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w are exposed metal terminals on the surface of the motor housing. These terminals are electrically connected to the motor drive circuit 11 of the motor control device 10, as detailed later. The U-phase coil 23u, V-phase coil 23v, and W-phase coil 23w are excitation coils located on the stator. They are connected in a star configuration inside the motor 20.

[0020] The U-phase coil 23u is electrically connected between the U-phase terminal 22u and the neutral point N. The V-phase coil 23v is electrically connected between the V-phase terminal 22v and the neutral point N. The W-phase coil 23w is electrically connected between the W-phase terminal 22w and the neutral point N. The energizing states of the U-phase coil 23u, V-phase coil 23v, and W-phase coil 23w are controlled by the motor control device 10, thereby generating the electromagnetic force required to rotate the rotor. As the rotor rotates, the shaft 21 also rotates synchronously with the rotor.

[0021] The rotation angle sensor 24 detects the rotation angle of the shaft 21 and outputs a rotation angle signal PS, representing the detection result, to the motor control device 10. The rotation angle sensor 24 can be, for example, a Hall sensor, an incremental encoder, or an absolute encoder.

[0022] Pump 30 is located on one axial side of shaft 21 of motor 20 and is driven by motor 20 via shaft 21 to discharge cooling oil F. Pump 30 has an oil inlet 31 and an oil outlet 32. After being drawn into the interior of pump 30 through oil inlet 31, cooling oil F is discharged to the outside of pump 30 through oil outlet 32. Thus, by connecting pump 30 and motor 20 axially adjacent to each other on shaft 21, an electric pump 40 is formed.

[0023] The motor control unit 10 is a device that controls the motor 20 of the electric pump 40 based on the speed command signal CS output from a higher-level control device (not shown) and the rotation angle signal PS output from the rotation angle sensor 24. As an example, the aforementioned control unit is an on-board ECU (Electronic Control Unit) mounted in a hybrid vehicle. The motor control unit 10 includes a motor drive circuit 11 (drive unit), a shunt resistor 12 (current detection unit), a control unit 13, and a storage unit 14.

[0024] The motor drive circuit 11 is a circuit that provides drive current to the motor 20. Specifically, the motor drive circuit 11 converts the DC power supply voltage provided by the DC power supply 200 into a three-phase AC voltage and outputs it to the motor 20. Thus, the motor drive circuit 11 provides three-phase AC current to the motor 20 as drive current. As an example, the DC power supply 200 is a battery installed in a hybrid vehicle.

[0025] Motor drive circuit 11 has a U-phase upper arm switch Q UH V-phase upper arm switch Q VH W-phase upper arm switch Q WH U-phase lower side arm switch Q UL V-phase lower arm switch Q VL and the W-phase lower side arm switch Q WL In this embodiment, each arm switch is, for example, an N-channel MOS-FET.

[0026] U-phase upper arm switch Q UH The drain terminal, the upper arm switch of phase V, Q VH The drain terminal and the upper arm switch of phase W Q WH The drain terminals are electrically connected to the positive terminal of the DC power supply 200. The U-phase lower arm switch Q... UL The source extreme element, V-phase lower side arm switch Q VL The source extreme element and the lower side arm switch Q of the W phase WL The source terminals are electrically connected to the negative terminal of the DC power supply 200 via shunt resistor 12. Additionally, the negative terminal of the DC power supply 200 is connected to the vehicle ground.

[0027] U-phase upper arm switch Q UH The source terminal is connected to the U-phase terminal 22u of motor 20 and the U-phase lower arm switch Q. UL The drain terminals are electrically connected respectively. The upper arm switch Q of phase V is connected. VH The source terminal is connected to the V-phase terminal 22V of motor 20 and the V-phase lower arm switch Q. VL The drain terminals are electrically connected respectively. The upper arm switch Q of phase W is connected. WH The source terminal and motor 20's W-phase terminal 22w and W-phase lower arm switch Q WL The drain terminals are electrically connected respectively.

[0028] U-phase upper arm switch Q UH The gate terminal, the upper arm switch Q of the V phase VH The gate terminal and the upper arm switch Q of phase W WH The gate terminals are electrically connected to the control unit 13. Additionally, the lower arm switch Q of phase U is... UL The gate terminal, the lower arm switch of phase V, Q VLThe gate terminal and the lower arm switch Q of phase W WL The gate terminals are also electrically connected to the control unit 13.

[0029] As described above, the motor drive circuit 11 is an inverter consisting of a three-phase full-bridge circuit with three upper arm switches and three lower arm switches. This motor drive circuit 11, configured in this way, converts the DC power supply voltage provided by the DC power supply 200 into a three-phase AC voltage and outputs it to the motor 20 by controlling the switching of each arm switch via the control unit 13. Thus, a three-phase AC current is supplied from the motor drive circuit 11 to the motor 20 as the drive current.

[0030] Shunt resistor 12 detects the drive current supplied to motor 20 and provides the current detection value Id, representing the detection result of the drive current, to control unit 13. One end of shunt resistor 12 is connected to the lower arm switch Q of phase U. UL V-phase lower arm switch Q VL and the W-phase lower side arm switch Q WL The source terminals of the shunt resistor 12 are electrically connected. The other end of the shunt resistor 12 is electrically connected to the negative terminal of the DC power supply 200. Furthermore, one end of the shunt resistor 12 is electrically connected to the control unit 13. The drive current supplied to the motor 20 flows into the vehicle ground via the shunt resistor 12. Therefore, a voltage proportional to the drive current appears between the terminals of the shunt resistor 12. This voltage between the terminals of the shunt resistor 12 is provided to the control unit 13 as a current detection value Id, representing the detection result of the drive current. Alternatively, a resistor voltage divider circuit may be provided between one end of the shunt resistor 12 and the control unit 13 as needed.

[0031] The control unit 13 is, for example, a microprocessor such as an MCU (Microcontroller Unit). The control unit 13 receives a speed command signal CS output from a host control device (not shown) and a rotation angle signal PS output from the rotation angle sensor 24. The control unit 13 is connected to the storage unit 14 in a communicative manner via a communication bus (not shown). The control unit 13 executes motor control processing and pump malfunction diagnostic processing, as described below, according to a program pre-stored in the storage unit 14.

[0032] In the motor control process, the control unit 13 calculates the actual rotational speed Rm of the motor 20 based on the rotation angle signal PS, and controls the motor drive circuit 11 based on the rotational speed command value Rc indicated by the rotational speed command signal CS and the actual rotational speed Rm, thereby controlling the rotational speed of the motor 20. Specifically, the control unit 13 determines the switching duty cycle of each arm switch required to make the actual rotational speed Rm of the motor 20 match the rotational speed command value Rc, and performs switching control of each arm switch according to the determined switching duty cycle. As a result, a three-phase AC voltage that makes the actual rotational speed Rm of the motor 20 match the rotational speed command value Rc is supplied from the motor drive circuit 11 to the motor 20.

[0033] In pump anomaly diagnosis and processing, the control unit 13 determines whether the electric pump 40 has experienced a foreign fluid intake anomaly based on the first current detection value obtained at the first moment when the speed command value Rc changes from the first command value Rc1 to the second command value Rc2, and the second current detection value obtained after the first moment. A foreign fluid intake anomaly refers to the intake of a fluid (a foreign fluid) with properties different from the cooling oil F into the pump 30. Foreign fluids include, for example, air, water, or gas.

[0034] The storage unit 14 includes: non-volatile memory storing programs and various setting data required for the control unit 13 to perform various processes; and volatile memory serving as a temporary data storage destination when the control unit 13 performs various processes. Non-volatile memory is, for example, EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory. Volatile memory is, for example, RAM (Random Access Memory). Figure 1 As shown, the storage unit 14 can be disposed outside the control unit 13, or it can be built into the control unit 13.

[0035] The following is a detailed explanation of the pump malfunction diagnosis and handling performed by the control unit 13.

[0036] First, refer to Figure 2 and Figure 3 The first pump malfunction diagnosis and treatment, which is the first case of pump malfunction diagnosis and treatment, will be explained. Figure 2 This is a flowchart illustrating the first pump malfunction diagnosis process performed by the control unit 13. The control unit 13 performs the first pump malfunction diagnosis process when the motor 20 is in a stable rotational state. A stable rotational state means that the motor 20 continues to rotate at the same speed as the speed command value Rc. In other words, a stable rotational state means that the actual speed Rm of the motor 20 is consistent with the speed command value Rc.

[0037] For example in Figure 3 In this context, the period from time t0 to time t1 is the period during which motor 20 is in a stable rotational state. In the following explanation, the period from time t0 to time t1 is sometimes referred to as the stable rotational period. During the stable rotational period, the actual rotational speed Rm of motor 20 is consistent with the first command value Rc1. The first command value Rc1 refers to the rotational speed command value Rc when motor 20 is in a stable rotational state. Figure 3 In the example shown, the first command value Rc1 is 1000 rpm, and the actual rotational speed Rm of motor 20 during stable rotation is also 1000 rpm. Figure 3 As shown, during stable rotation, the current detection value Id supplied from the shunt resistor 12 to the control unit 13 is constant.

[0038] The control unit 13 performs a moving average calculation of the current detection value Id in parallel with the first pump anomaly diagnosis processing. In the moving average calculation, the control unit 13 samples the current detection value Id provided from the shunt resistor 12t, i.e., the voltage between the terminals of the shunt resistor 12t, at a first time interval to obtain time-series data of the current detection value Id. The control unit 13 calculates a moving average of the current detection value Id based on the time-series data, and obtains the moving average calculated at a second time interval as the current detection value of interest. The second time interval is longer than the first time interval. For example, the first time interval is 50 μs and the second time interval is 300 ms. The control unit 13 sequentially saves the current detection values ​​of interest obtained at the second time interval through the moving average calculation of the current detection value Id as described above to the storage unit 14.

[0039] like Figure 2 As shown, when the control unit 13 starts the first pump malfunction diagnosis process when the motor 20 is in a stable rotating state, it first determines whether the speed command value Rc has changed from the first command value Rc1 to the second command value Rc2 (step S1). The second command value Rc2 is a value that is greater than or equal to the first command value Rc1 by a predetermined value. For example, the second command value Rc2 is a value that is greater than or equal to the first command value Rc1 by 100 rpm or more. That is, in step S1, the control unit 13 determines whether the speed command value Rc has increased from the first command value Rc1 to the second command value Rc2.

[0040] If the result in step S1 is "No", that is, if the speed command value Rc does not change from the first command value Rc1 to the second command value Rc2, the control unit 13 repeats the processing of step S1 at a predetermined time interval until the speed command value Rc changes from the first command value Rc1 to the second command value Rc2.

[0041] On the other hand, if "yes" is set in step S1, that is, if the speed command value Rc changes from the first command value Rc1 to the second command value Rc2, the control unit 13 obtains the latest current detection value of interest from the storage unit 14 as the first current detection value at the first moment when the speed command value Rc changes (step S2).

[0042] exist Figure 3 In the example shown, assume that at time t1, the speed command value Rc changes (increases) from the first command value Rc1 to the second command value Rc2. As an example, the second command value Rc2 is 2000 rpm. In this case, the control unit 13 obtains the latest current detection value of interest from the storage unit 14 at time t1 (the first timing) as the first current detection value I1.

[0043] Next, at the second timing after the first timing point when the actual rotational speed Rm of the motor 20 becomes above a predetermined value, the control unit 13 retrieves the latest current detection value from the storage unit 14 as the second current detection value (step S3). Figure 3 In the example shown, it is assumed that at time t2, the actual rotational speed Rm of motor 20 becomes above the predetermined value Rm1. As an example, the predetermined value Rm1 is the midpoint between the first command value Rc1 and the second command value Rc2 (1500 rpm). In this case, the control unit 13 obtains the latest current detection value of interest from the storage unit 14 at time t2 (the second timing) as the second current detection value I2.

[0044] like Figure 3 As shown, when the speed command value Rc changes from the first command value Rc1 to the second command value Rc2 at time t1, the control unit 13 performs motor control processing in parallel with the first pump abnormality diagnosis processing, thereby causing the actual speed Rm of the motor 20 to begin increasing towards the second command value Rc2. Under normal conditions of the electric pump 40, as the actual speed Rm of the motor 20 increases towards the second command value Rc2, the current detection value Id also increases from time t1, which is the first timing point. Figure 3 In this context, I2a is the second current detection value obtained at time t2 (the second timing point) under normal operating conditions of the electric pump 40. The second current detection value I2a lies within the reference range NR. The reference range NR is the region traversed by the trajectory of the current detection value Id, which rises from the first timing point under normal operating conditions of the electric pump 40.

[0045] exist Figure 3In this context, I2b, I2c, and I2d are the second current detection values ​​obtained at time t2 (the second opportunity) when an abnormality in the intake of a foreign fluid occurs in the electric pump 40. For example, when a foreign fluid that increases the load on the motor 20 is drawn into the electric pump 40, the current detection value Id rises from time t1 (the first opportunity), similar to normal conditions. However, because the load is larger than normal, the rising trajectory of the current detection value Id passes through the region deviating upwards from the reference range NR. I2b is the second current detection value obtained at time t2 (the second opportunity) when a foreign fluid that increases the load on the motor 20 is drawn into the electric pump 40.

[0046] For example, when a relatively small amount of heterogeneous fluid, reducing the load on motor 20, is drawn into electric pump 40, the current detection value Id rises from time t1 (the first timing point) as in normal conditions. However, because the load is smaller than normal, the rising trajectory of the current detection value Id passes through a region deviating downwards from the reference range NR. I2c is the second current detection value obtained at time t2 (the second timing point) when a relatively small amount of heterogeneous fluid, reducing the load on motor 20, is drawn into electric pump 40.

[0047] For example, when a relatively large amount of heterogeneous fluid (especially air) is drawn into the electric pump 40 to reduce the load on motor 20, the load becomes very small compared to normal conditions due to insufficient supply of cooling oil F to the electric pump 40. Therefore, the current detection value Id decreases from time t1, which is the first timing point, inversely proportional to the increase in the actual speed Rm. The trajectory of the decrease in the current detection value Id in this case passes through the region deviating downward from the reference range NR. I2d is the second current detection value obtained at time t2 (the second timing point) when a relatively large amount of heterogeneous fluid is drawn into the electric pump 40 to reduce the load on motor 20.

[0048] like Figure 3 As shown, based on the first current detection value I1 obtained at the first time point and the second current detection value I2 obtained at the second time point, a parameter representing the change in the current detection value Id is calculated. It is then determined whether the calculated parameter deviates from the predetermined reference range NR, thereby determining whether the electric pump 40 has experienced an abnormal intake of a foreign fluid. In this embodiment, the control unit 13 calculates the change in the current detection value Id per unit time ΔId as a parameter representing the change in the current detection value Id, and determines whether the change ΔId deviates from the reference range NR, thereby determining whether the electric pump 40 has experienced an abnormal intake of a foreign fluid. Hereinafter, we return to... Figure 2 Let's continue with the explanation.

[0049] The control unit 13 calculates the change in current detection value Id per unit time ΔId after the first timing point based on the first current detection value I1 obtained in step S2 and the second current detection value I2 obtained in step S3, and determines whether the calculated change ΔId deviates from the reference range NR (step S4). The change in current detection value Id per unit time ΔId after the first timing point t1 is expressed by the following formula (1). In the following explanation, the change ΔId expressed by the following formula (1) is sometimes referred to as the current change. In addition, in the following formula (1), time t2 is the second timing point when the actual rotational speed Rm of the motor 20 changes to a predetermined value Rm1 or higher.

[0050] ΔId=(I2-I1) / (t2-t1)…(1)

[0051] The reference range NR is defined by the minimum and maximum values ​​of the current change ΔId that can be taken under normal conditions of the electric pump 40. The minimum and maximum values ​​of the current change ΔId under normal conditions of the electric pump 40 are determined in advance through experiments or simulations, and are stored in the storage unit 14. That is, in step S4, the control unit 13 reads the minimum and maximum values ​​of the current change ΔId from the storage unit 14, and if the calculated current change ΔId is not included in the range from the minimum to the maximum value, it is determined that the current change ΔId deviates from the reference range NR.

[0052] If the result in step S4 is "No", meaning the current change ΔId does not deviate from the reference range NR, it is inferred that the electric pump 40 is normal. In this case, the control unit 13 ends the first pump malfunction diagnosis process.

[0053] On the other hand, if the condition in step S4 is "yes," that is, if the current change ΔId deviates from the reference range NR, it is inferred that the electric pump 40 has experienced a foreign fluid suction abnormality. In this case, the control unit 13 determines that the electric pump 40 has experienced a foreign fluid suction abnormality, sends a foreign fluid suction error notification to the upper control device to notify the electric pump 40 that a foreign fluid suction abnormality has occurred, and sends an electric pump stop notification to stop the electric pump 40 (step S5).

[0054] Then, after sending a notification of a foreign fluid intake error and a notification of electric pump stop to the upper control device, the control unit 13 stops the motor 20 of the electric pump 40 by controlling the motor drive circuit 11 (step S6).

[0055] As described above, when the motor 20 is in a stable rotating state, the control unit 13 performs the first pump abnormality diagnosis process, which can detect that the electric pump 40 has experienced an abnormal intake of a foreign fluid. In addition, in the event of an abnormal intake of a foreign fluid in the electric pump 40, by stopping the motor 20 of the electric pump 40, it is possible to prevent overheating, wear, and burns in the electric pump 40.

[0056] Next, refer to Figure 4 and Figure 5 The second pump malfunction diagnosis and treatment, which is the second case of pump malfunction diagnosis and treatment, will be explained. Figure 4 This is a flowchart illustrating the second pump malfunction diagnosis process performed by the control unit 13. The control unit 13 performs the second pump malfunction diagnosis process when the motor 20 is in a stable rotating state.

[0057] For example in Figure 5 In this context, the period from time t10 to time t11 is the stable rotation period during which motor 20 is in a stable rotational state. During this stable rotation period, the actual rotational speed Rm of motor 20 is consistent with the first command value Rc1. Figure 5 In the example shown, the first command value Rc1 is 1000 rpm, and the actual rotational speed Rm of motor 20 during stable rotation is also 1000 rpm. Figure 5 As shown, during stable rotation, the current detection value Id supplied from the shunt resistor 12 to the control unit 13 is constant. The control unit 13 performs a moving average calculation of the current detection value Id in parallel with the second pump anomaly diagnosis processing.

[0058] like Figure 4 As shown, when the control unit 13 starts the second pump malfunction diagnosis process when the motor 20 is in a stable rotational state, it first determines whether the speed command value Rc has changed from the first command value Rc1 to the second command value Rc2 (step S11). The second command value Rc2 is a value that is greater than or equal to the first command value Rc1 by a predetermined value. That is, in step S11, the control unit 13 determines whether the speed command value Rc has increased from the first command value Rc1 to the second command value Rc2.

[0059] If the result in step S11 is "No", that is, if the speed command value Rc does not change from the first command value Rc1 to the second command value Rc2, the control unit 13 repeats the processing of step S11 at a predetermined time interval until the speed command value Rc changes from the first command value Rc1 to the second command value Rc2.

[0060] On the other hand, if "yes" is set in step S11, that is, if the speed command value Rc changes from the first command value Rc1 to the second command value Rc2, the control unit 13 obtains the latest current detection value of interest from the storage unit 14 as the first current detection value I1 at the first time the speed command value Rc changes (step S12).

[0061] exist Figure 5 In the example shown, assume that at time t11, the speed command value Rc changes (increases) from the first command value Rc1 to the second command value Rc2. As an example, the second command value Rc2 is 2000 rpm. In this case, the control unit 13 obtains the latest current detection value of interest from the storage unit 14 at time t11 (the first timing) as the first current detection value I1.

[0062] Next, at the second time when the actual speed Rm of the motor 20 becomes above a predetermined value after the first time, the control unit 13 obtains the latest current detection value from the storage unit 14 as the second current detection value I2 (step S13).

[0063] Next, the control unit 13 calculates the current change ΔId per unit time of the current detection value Id after the first timing based on the first current detection value I1 obtained in step S12 and the second current detection value I2 obtained in step S13, and determines whether the calculated current change ΔId deviates from the reference range NR and whether the second current detection value I2 decreases relative to the first current detection value I1 (step S14).

[0064] If step S14 is "No," meaning the current change ΔId does not deviate from the reference range NR and the second current detection value I2 does not decrease relative to the first current detection value I1, it is inferred that the electric pump 40 is normal. In this case, the control unit 13 ends the second pump anomaly diagnosis process. Alternatively, if the current change ΔId deviates from the reference range NR and the second current detection value I2 does not decrease relative to the first current detection value I1, the control unit 13 ends the second pump anomaly diagnosis process after performing the same steps S5 and deviation S6 as in the first pump anomaly diagnosis process.

[0065] On the other hand, if the condition in step S14 is "yes," that is, if the current change ΔId deviates from the reference range NR and the second current detection value I2 decreases relative to the first current detection value I1, it is inferred that a relatively large amount of heterogeneous fluid (especially air, etc.) that reduces the load on motor 20 is being drawn into electric pump 40. In this case, control unit 13 determines that insufficient oil supply has occurred in electric pump 40 due to abnormal heterogeneous fluid intake, sends a heterogeneous fluid intake error notification to the upper control device to notify electric pump 40 that a heterogeneous fluid intake abnormality has occurred, and sends a low-rotation control start notification to notify the start of low-rotation control of motor 20 (step S15).

[0066] After sending a heterogeneous fluid intake error notification and a low-rotation control start notification to the upper-level control device, the control unit 13 initiates low-rotation control (step S16) by controlling the motor drive circuit 11 to rotate the motor 20 at a speed corresponding to the first command value Rc1. Figure 5 In the example shown, it is assumed that the control unit 13 starts low-rotation control from time t12. Hereinafter, the timing at which the control unit 13 starts low-rotation control is sometimes referred to as the low-rotation control start timing. Thus, when the control unit 13 determines that the electric pump 40 has experienced an abnormal intake of foreign fluid and that the second current detection value I2 has decreased relative to the first current detection value I1, it controls the motor drive circuit 11 to make the motor 20 rotate at a speed corresponding to the first command value Rc1.

[0067] like Figure 5 As shown, when the control unit 13 starts low-speed control at time t12, the actual speed Rm of the motor 20 begins to decrease towards the first command value Rc1 starting from time t12. If the cause of the malfunction in the electric pump 40 is solely the intake of a foreign fluid, by reducing the speed of the motor 20, the supply of cooling oil F to the pump 30 is improved, thus eliminating the insufficient supply of cooling oil F to the pump 30. As a result, the load on the motor 20 increases starting from time t12, and therefore the current detection value Id also increases starting from time t12, which is the starting point of the low-speed control. Then, at time t14, when the actual speed Rm of the motor 20 coincides with the first command value Rc1, if the insufficient supply of cooling oil F to the pump 30 is completely eliminated, the current detection value Id returns to the value before time t11, which is the starting point of the command change.

[0068] On the other hand, such as Figure 5As shown, in the case where oil leakage is one of the causes of the malfunction of the electric pump 40, similarly to the above, the current detection value Id rises from the moment t12, which is the start time of low-speed control, but does not return to the value before the moment t11, which is the moment of command change. The current detection value Id decreases over time from the moment t13, which is earlier than the moment t14, when the actual speed Rm of the motor 20 coincides with the first command value Rc1. Therefore, based on the change in the current detection value Id after the start time of low-speed control, it can be determined whether the current detection value Id remains in a state of not returning to the value before the moment of command change and decreases over time, thereby determining whether oil leakage has occurred in the delivery path of the cooling oil F, which includes the electric pump 40.

[0069] The control unit 13 reads the latest value from the current detection values ​​obtained after the low-rotation control start time from the storage unit 14 as the monitoring current detection value (step S17). Alternatively, if the current detection value to be read as the monitoring current detection value is not stored in the storage unit 14 during step S17, the control unit 13 may continue executing step S17 until the current detection value to be read as the monitoring current detection value is stored in the storage unit 14.

[0070] Next, the control unit 13 determines, based on the change in the monitored current detection value, whether the current detection value Id has decreased over time as it has not returned to the value before the command change timing (step S18). If the result in step S18 is "No", the control unit 13 returns to the processing in step S17. After returning to step S17 and updating the monitored current detection value to the latest value, the control unit 13 again proceeds to step S18, determining, based on the change in the monitored current detection value, whether the current detection value Id has decreased over time as it has not returned to the value before the command change timing. Thus, the control unit 13 monitors the change in the current detection value Id after the low-rotation control start timing.

[0071] On the other hand, if the condition in step S18 is "yes," that is, if the current detection value Id decreases over time without returning to its value before the command change, it is inferred that an oil leak has occurred in the delivery path of the cooling oil F, which includes the electric pump 40. In this case, the control unit 13 determines that an oil leak has occurred, sends an oil leak error notification to the upper control device to notify that an oil leak has occurred, and sends an electric pump stop notification to stop the electric pump 40 (step S19).

[0072] Then, after sending an oil leak error notification and an electric pump stop notification to the upper control device, the control unit 13 stops the motor 20 of the electric pump 40 by controlling the motor drive circuit 11 (step S20).

[0073] As described above, when the motor 20 is in a stable rotating state, the control unit 13 performs a second pump malfunction diagnosis process, which can detect a situation where the electric pump 40 has experienced an abnormal intake of a foreign fluid. Furthermore, in the second pump malfunction diagnosis process, if the electric pump 40 experiences an abnormal intake of a foreign fluid and the second current detection value I2 decreases relative to the first current detection value I1, the motor 20 is not stopped, but its rotation is controlled at a low speed corresponding to the first command value Rc1. Therefore, when the cause of the electric pump 40 malfunction is solely the intake of a foreign fluid, particularly air, the supply of cooling oil F to the pump 30 is improved, eliminating insufficient supply of cooling oil F to the pump 30. As a result, continuous operation is possible without stopping the electric pump 40. However, if the current detection value Id decreases over time after the low-rotation control starts and does not return to the value before the command change, i.e., it is inferred that an oil leak has occurred in the delivery path of the cooling oil F containing the electric pump 40, by stopping the motor 20, heat generation, wear, and burns in the electric pump 40 can be prevented.

[0074] As explained above, in this embodiment, the control unit 13 determines whether an abnormal intake of heterogeneous fluid has occurred in the electric pump 40 based on the first current detection value I1 obtained at the first moment when the speed command value Rc changes from the first command value Rc1 to the second command value Rc2 and the second current detection value I2 obtained after the first moment.

[0075] According to this embodiment, it is possible to detect abnormalities in the intake of heterogeneous fluids in the electric pump 40 based on changes in the current detection value generated when the rotational speed changes.

[0076] In this embodiment, the control unit 13 calculates a parameter representing the change of the current detection value Id based on the first current detection value I1 and the second current detection value I2. If the calculated parameter deviates from the specified reference range NR, it is determined that the electric pump 40 has experienced an abnormal intake of heterogeneous fluid.

[0077] Under normal operating conditions, starting from the first moment when the speed command value Rc changes from the first command value Rc1 to the second command value Rc2, the current detection value Id should rise within the specified reference range NR. However, if a foreign fluid is drawn into the electric pump 40, the trajectory of the current detection value Id starting from the first moment deviates from the reference range NR. Therefore, if the parameter representing the change in the current detection value Id deviates from the specified reference range NR, it can be determined that an abnormality in the electric pump 40 due to the intake of a foreign fluid has occurred.

[0078] In this embodiment, when the control unit 13 determines that the electric pump 40 has experienced an abnormal intake of a foreign fluid, it controls the motor drive circuit 11 to stop the motor 20.

[0079] In this way, if the electric pump 40 experiences an abnormal intake of a foreign fluid, stopping the motor 20 of the electric pump 40 can prevent overheating, wear, and burns in the electric pump 40.

[0080] In this embodiment, when the control unit 13 determines that the electric pump 40 has experienced an abnormal intake of a foreign fluid and the second current detection value I2 is reduced relative to the first current detection value I1, it controls the motor drive circuit 11 to make the motor 20 rotate at a speed corresponding to the first command value Rc1.

[0081] Therefore, when the cause of the malfunction of the electric pump 40 is solely the intake of a foreign fluid, particularly air, improving the supply of cooling oil F to the pump 30 eliminates the problem of insufficient cooling oil supply to the pump 30. As a result, the electric pump 40 can operate continuously without stopping.

[0082] In this embodiment, when the current detection value decreases over time while the motor 20 is rotating at a speed corresponding to the first command value Rc1, the control unit 13 stops the motor 20.

[0083] In this way, after the low-rotation control starts, if the current detection value decreases over time and does not return to the value before the command change, i.e., if it is inferred that an oil leak has occurred, stopping the motor 20 can prevent overheating, wear, and burns in the electric pump 40.

[0084] In this embodiment, the control unit 13 calculates the above-mentioned parameters based on the first current detection value I1 and the second current detection value I2 obtained at the second timing point, wherein the second timing point is the timing point after the first timing point when the actual rotational speed Rm of the motor 20 becomes a predetermined value or higher.

[0085] Therefore, at the second moment when the actual speed Rm of the motor 20 accurately follows the change of the speed command value Rc, the second current detection value I2 is acquired, and thus the parameters representing the change of the current detection value Id can be calculated more accurately.

[0086] In this embodiment, the control unit 13 calculates the change in current detection value Id per unit time ΔId based on the first current detection value I1 and the second current detection value I2 as the aforementioned parameter.

[0087] Therefore, if the change in the current detection value Id per unit time ΔId deviates from the reference range NR, it can be determined that the electric pump 40 has experienced an abnormal intake of heterogeneous fluid.

[0088] [Variation Example]

[0089] The present invention is not limited to the above embodiments, and the various structures described in this specification can be appropriately combined within a range that does not contradict each other.

[0090] In the above embodiments, an example is given of calculating the change ΔId of the current detection value Id per unit time based on the first current detection value I1 and the second current detection value I2 as a parameter. However, the present invention is not limited to this. For example, the deviation between the first current detection value I1 and the second current detection value I2 (=I2-I1) can also be calculated as a parameter representing the change of the current detection value Id.

[0091] In the above embodiments, a method of controlling the motor based on rotational position information obtained from a rotation angle sensor is illustrated. However, a sensorless control method based on rotational position information obtained from the motor's back electromotive force, etc., can also be used.

[0092] In the above embodiments, an electric pump device 100 that supplies cooling oil F to a drive motor mounted in a hybrid vehicle is exemplified as an electric pump device of the present invention. However, the electric pump device of the present invention is not limited to this, and for example, the present invention can also be applied to an electric pump device that supplies oil to a transmission. In addition, the fluid discharged from the electric pump is not limited to oil such as cooling oil.

Claims

1. A motor control device for controlling the motor of an electric pump, wherein, The motor control device has the following features: The drive unit provides drive current to the motor; The control unit controls the drive unit according to the speed command value, thereby controlling the speed of the motor; as well as A current detection unit detects the drive current supplied to the motor and provides a current detection value, representing the detection result of the drive current, to the control unit. The control unit determines whether the electric pump has experienced an abnormal intake of foreign fluid based on a first current detection value obtained at the first moment when the speed command value changes from the first command value to the second command value, and a second current detection value obtained after the first moment. When the control unit determines that the electric pump has experienced an abnormal intake of the foreign fluid and that the second current detection value is lower than the first current detection value, it controls the drive unit to rotate the motor at a speed corresponding to the first command value. When the current detection value decreases over time while the motor is rotating at a speed corresponding to the first command value, the control unit stops the motor.

2. The motor control device according to claim 1, wherein, The control unit calculates a parameter representing the change in the current detection value based on the first current detection value and the second current detection value. If the calculated parameter deviates from the specified reference range, it determines that the electric pump has experienced an abnormal intake of the heterogeneous fluid.

3. The motor control device according to claim 2, wherein, The control unit calculates the parameter based on the first current detection value and the second current detection value obtained at the second timing point, which is the timing point after the first timing point when the actual speed of the motor becomes above a predetermined value.

4. The motor control device according to claim 2, wherein, The control unit calculates the change in the current detection value per unit time as the parameter based on the first current detection value and the second current detection value.

5. An electric pump device, comprising: Electric pumps; and The motor control device according to any one of claims 1 to 4 controls the motor of the electric pump.

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