Control device, electric pump, control method, and program

Abstract

The present invention provides a control device, an electric pump, a control method, and a program capable of detecting output sticking failures of a temperature sensor. [Solution] A control device for an electric pump equipped with a motor and a temperature sensor, comprising a control unit that rotates the motor based on a rotation speed command value. The control unit can perform a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value that is higher than the first rotation speed command value, and when the temperature obtained based on the temperature sensor at the time the rotation speed command value changes to the second rotation speed command value is lower than a threshold temperature determined for the second rotation speed command value. In the determination process, if the change in the amount of the obtained temperature remains within a predetermined threshold for a predetermined time, and the obtained temperature is lower than a threshold temperature determined for the second rotation speed command value, the control unit outputs a signal indicating that there is an abnormality in the temperature sensor.

Description

[Technical Field]

[0001] The present invention relates to a control device, an electric pump, a control method, and a program. [Background technology]

[0002] Electric pumps equipped with temperature sensors are known (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-103005 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In the electric pump described above, there was a risk of a failure in the temperature sensor where the temperature value obtained based on the temperature sensor would not change, or would hardly change, even when the temperature of the object being measured changed. In the following explanation, this failure will be referred to as "output sticking failure".

[0005] In view of the above circumstances, one of the objectives of the present invention is to provide a control device, an electric pump, a control method, and a program capable of detecting output sticking failures of a temperature sensor. [Means for solving the problem]

[0006] One embodiment of the control device of the present invention is a control device for an electric pump equipped with a motor and a temperature sensor, comprising a control unit that rotates the motor based on a rotation speed command value. The control unit can perform a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value that is higher than the first rotation speed command value, and when the temperature obtained based on the temperature sensor at the time the rotation speed command value changes to the second rotation speed command value is lower than a threshold temperature determined for the second rotation speed command value. The threshold temperature is a temperature determined based on the value of the acquired temperature that saturates when the motor is rotated based on the rotation speed command value when the temperature sensor is functioning normally. In the determination process, the control unit outputs a signal indicating that there is an abnormality in the temperature sensor when the change in the acquired temperature remains within a predetermined threshold for a predetermined time, and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value.

[0007] One embodiment of the electric pump of the present invention comprises the control device described above, the motor, a pump unit driven by the motor, and the temperature sensor.

[0008] One aspect of the control method of the present invention is a control method for an electric pump comprising a motor and a temperature sensor, comprising: rotating the motor based on a rotation speed command value; and executing a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value higher than the first rotation speed command value, and the acquired temperature obtained based on the temperature sensor at the time the rotation speed command value changes to the second rotation speed command value is lower than a threshold temperature determined for the second rotation speed command value. The threshold temperature is a temperature determined based on the value of the acquired temperature that saturates when the motor is rotated based on the rotation speed command value when the temperature sensor is functioning normally. The determination process includes outputting a signal indicating that there is an abnormality in the temperature sensor when the change in the acquired temperature remains within a predetermined threshold for a predetermined time, and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value.

[0009] One aspect of the program of the present invention involves causing a computer to execute the above-described control method. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to detect a failure in the output of a temperature sensor in an electric pump. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an electric pump in one embodiment. [Figure 2] Figure 2 is a flowchart showing some of the processes performed by a control device in one embodiment. [Figure 3] Figure 3 is a graph showing an example of the relationship between the rotational speed command value and the threshold temperature in one embodiment. [Figure 4] Figure 4 shows an example of the change in motor rotation speed and the change in acquired temperature obtained based on the temperature sensor when the rotation speed command value increases in one embodiment. [Figure 5]FIG. 5 is a flowchart showing an example of the determination process in one embodiment.

Embodiments of the Invention

[0012] The electric pump 100 of the present embodiment shown in FIG. 1 is mounted on a vehicle. The vehicle on which the electric pump 100 is mounted is a vehicle that uses a motor as a power source, such as a hybrid electric vehicle (HEV), a plug-in hybrid vehicle (PHV), or an electric vehicle (EV). The electric pump 100 supplies oil as the fluid F to a drive device that includes a motor for rotating the vehicle axle. Note that the fluid F sent by the electric pump 100 is not particularly limited and may be a fluid other than oil, such as water.

[0013] As shown in FIG. 1, the electric pump 100 of the present embodiment includes a control device 10 and an electric pump body 40. The electric pump body 40 has a motor 20 and a pump section 30. That is, the electric pump 100 includes the motor 20 and the pump section 30. In the present embodiment, the motor 20 is a three-phase motor. More specifically, the motor 20 is an inner rotor type three-phase brushless DC motor. The motor 20 has a rotor 20a and a stator 20b. The rotor 20a rotates around the central axis of the motor 20. The rotor 20a has a shaft 21 that extends along the central axis of the motor 20. The stator 20b has a plurality of coils. The plurality of coils includes a U-phase coil 23u, a V-phase coil 23v, and a W-phase coil 23w. The motor 20 has a U-phase terminal 22u, a V-phase terminal 22v, and a W-phase terminal 22w. The U-phase coil 23u is connected to the U-phase terminal 22u. The V-phase coil 23v is connected to the V-phase terminal 22v. The W-phase coil 23w is connected to the W-phase terminal 22w.

[0014] The pump unit 30 is driven by the motor 20. More specifically, the pump unit 30 is driven by the shaft 21 of the motor 20. The pump unit 30 has an inlet 31 and a discharge port 32. Driven by the motor 20, the pump unit 30 draws in fluid F from the inlet 31 and discharges it from the discharge port 32.

[0015] The control device 10 is a device that controls the motor 20 based on a rotation speed command value CS output from a higher-level control device (not shown). The higher-level control device (not shown) is, for example, an ECU (Electronic Control Unit) mounted on a vehicle. The control device 10 comprises a drive circuit 11, a voltage detection circuit 12, a control unit 13, a storage unit 14, a circuit board 15, and a temperature sensor 50. In other words, the electric pump 100 comprises a drive circuit 11, a voltage detection circuit 12, a control unit 13, a storage unit 14, a circuit board 15, and a temperature sensor 50. The circuit board 15 is, for example, a printed circuit board. The drive circuit 11, the voltage detection circuit 12, the control unit 13, the storage unit 14, and the temperature sensor 50 are mounted on the circuit board 15.

[0016] The drive circuit 11 is a circuit that supplies power to the motor 20. In this embodiment, the drive circuit 11 is powered by the DC power supply voltage V supplied from the DC power supply 200. M This is an inverter circuit that converts the DC power supply 200 into a three-phase AC voltage and supplies it to the motor 20. The DC power supply 200 is, for example, a battery mounted on the vehicle. The drive circuit 11 has a plurality of switching elements. The plurality of switching elements is a U-phase upper arm switch Q UH And, V-phase upper arm switch Q VH And, W-phase upper arm switch Q WH And, U-phase lower arm switch Q UL And, V-phase lower arm switch Q VL And, W-phase lower arm switch Q WLand, including. Each arm switch is, for example, an N-channel metal oxide semiconductor field effect transistor (MOSFET: Metal-Oxide-Semiconductor Field-Effect Transistor). Each arm switch may be another transistor such as an IGBT (Insulated Gate Bipolar Transistor).

[0017] The drain terminal of the U-phase upper arm switch Q UH the drain terminal of the V-phase upper arm switch Q VH and the drain terminal of the W-phase upper arm switch Q WH are each electrically connected to the positive terminal of the DC power supply 200. The source terminal of the U-phase lower arm switch Q UL the source terminal of the V-phase lower arm switch Q VL and the source terminal of the W-phase lower arm switch Q WL are each electrically connected to the negative terminal of the DC power supply 200. Note that the negative terminal of the DC power supply 200 is electrically connected to the ground in the vehicle.

[0018] The source terminal of the U-phase upper arm switch Q UH is electrically connected to the U-phase terminal 22u of the motor 20 and to the drain terminal of the U-phase lower arm switch Q UL respectively. The source terminal of the V-phase upper arm switch Q VH is electrically connected to the V-phase terminal 22v of the motor 20 and to the drain terminal of the V-phase lower arm switch Q VL respectively. The source terminal of the W-phase upper arm switch Q WH is electrically connected to the W-phase terminal 22w of the motor 20 and to the drain terminal of the W-phase lower arm switch Q WL respectively.

[0019] The gate terminal of the U-phase upper arm switch Q UH the gate terminal of the V-phase upper arm switch Q VH and the gate terminal of the W-phase upper arm switch Q WHThe gate terminals are electrically connected to the control unit 13. U-phase lower arm switch Q UL The gate terminal, V-phase lower arm switch Q VL The gate terminal and the W-phase lower arm switch Q WL The gate terminals are also electrically connected to the control unit 13.

[0020] The drive circuit 11 is composed of a three-phase full-bridge circuit having the three upper arm switches and three lower arm switches described above. With the drive circuit 11 configured in this way, each arm switch is switched by the control unit 13, thereby controlling the DC power supply voltage V supplied from the DC power supply 200. M The voltage is converted to a three-phase AC voltage and output to the motor 20.

[0021] The voltage detection circuit 12 is a voltage detection unit capable of detecting the voltage applied to the motor 20. In this embodiment, the voltage detection circuit 12 is capable of detecting the terminal voltages of each of the three phases of the motor 20. The voltage detection circuit 12 is electrically connected to the U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w of the motor 20. The voltage detection circuit 12 detects the U-phase terminal voltage Vu, which is the voltage at the U-phase terminal 22u, and outputs the detected value to the control unit 13. The voltage detection circuit 12 detects the V-phase terminal voltage Vv, which is the voltage at the V-phase terminal 22v, and outputs the detected value to the control unit 13. The voltage detection circuit 12 detects the W-phase terminal voltage Vw, which is the voltage at the W-phase terminal 22w, and outputs the detected value to the control unit 13.

[0022] In this embodiment, the temperature sensor 50 is attached to the substrate 15. In this embodiment, the temperature sensor 50 is a temperature sensor for measuring the temperature of the substrate 15. The temperature sensor 50 may be of any type. The output of the temperature sensor 50 is input to the control unit 13. The control unit 13 can acquire the temperature of the substrate 15 as the acquired temperature T based on the output from the temperature sensor 50.

[0023] The control unit 13 is, for example, a microprocessor such as an MCU (Microcontroller Unit). The control method for the electric pump 100 in this embodiment is a control method performed by the control unit 13. The control unit 13 receives a rotation speed command value CS output from a higher-level control device (not shown). The rotation speed command value CS is a signal that indicates the target rotation speed of the motor 20. The control unit 13 rotates the motor 20 based on the rotation speed command value CS. In other words, the control method in this embodiment includes rotating the motor 20 based on the rotation speed command value CS. The control unit 13 is communicated with the storage unit 14. The control unit 13 executes a process to rotate the motor 20 at the target rotation speed indicated by the rotation speed command value CS, according to a program pre-stored in the storage unit 14. The rotation speed N of the motor 20 is the rotation speed of the rotor 20a.

[0024] The control unit 13 can perform a determination process to determine whether or not an abnormality has occurred in the temperature sensor 50. The abnormalities determined by the determination process include output sticking failures in which the current value detected by the temperature sensor 50 does not change, or changes very little, even when the temperature of the substrate 15 changes. The control unit 13 determines whether or not to perform the determination process when the rotation speed command value CS changes. In this embodiment, the control unit 13 determines whether or not to perform the determination process according to the flowchart shown in Figure 2.

[0025] As shown in Figure 2, when the rotation speed command value CS changes (step S110), the control unit 13 determines whether the rotation speed command value CS has increased or not (step S120). In step S120, the control unit 13 determines that the rotation speed command value CS has increased if it changes from the first rotation speed command value CS1 to the second rotation speed command value CS2, which is higher than the first rotation speed command value CS1. The first rotation speed command value CS1 is not particularly limited as long as it is lower than the second rotation speed command value CS2. The first rotation speed command value CS1 may be zero. The first rotation speed command value CS1 being zero means that the motor 20 is stopped. The second rotation speed command value CS2 is not particularly limited as long as it is higher than the first rotation speed command value CS1. The first rotation speed command value CS1, which is the rotation speed command value CS before the change, is stored in the storage unit 14, for example. The control unit 13 stores the time change of the rotation speed command value CS in the storage unit 14 from the start of driving the motor 20. The rotation speed command value CS stored in the memory unit 14 may be erased sequentially, for example, after a certain amount of time has elapsed.

[0026] If the control unit 13 determines in step S120 that the rotation speed command value CS has not increased (step S120: NO), it does not perform the determination process (step S150). On the other hand, if the control unit 13 determines in step S120 that the rotation speed command value CS has increased (step S120: YES), it determines whether the acquired temperature T obtained based on the temperature sensor 50 is lower than the threshold temperature Tsa (step S130).

[0027] The threshold temperature Tsa is determined based on the value of the acquired temperature T at which the motor 20 saturates when it is rotated based on the rotation speed command value CS, assuming the temperature sensor 50 is functioning correctly. When the motor 20 rotates, heat is generated in the control device 10. The amount of heat generated in the control device 10 increases as the rotation speed N of the motor 20 increases. Therefore, as the rotation speed N of the motor 20 increases, the temperature of the circuit board 15 of the control device 10 rises, and the acquired temperature T obtained based on the temperature sensor 50 also rises. After a certain amount of time has passed since the rotation speed N of the motor 20 increased, the rise in the acquired temperature T stops, and the acquired temperature T saturates at a certain temperature corresponding to the rotation speed N of the motor 20. In the following explanation, this saturating temperature will be called the saturation temperature Ts. The threshold temperature Tsa is determined based on the saturation temperature Ts. The threshold temperature Tsa is determined separately for each magnitude of the rotation speed command value CS. Each threshold temperature Tsa determined for each rotation speed command value CS is lower than the saturation temperature Ts for each rotation speed command value CS. Each threshold temperature Tsa is, for example, approximately 0.7 times or more and 0.9 times or less of each saturation temperature Ts. Each threshold temperature Tsa is, for example, below the lowest value of each saturation temperature Ts when variation occurs.

[0028] Figure 3 is a graph showing an example of the relationship between the rotational speed command value CS and the threshold temperature Tsa. In Figure 3, the vertical axis represents the threshold temperature Tsa, and the horizontal axis represents the rotational speed command value CS. As shown in Figure 3, in this embodiment, the relationship between the rotational speed command value CS and the threshold temperature Tsa is represented by a linear function. As the rotational speed command value CS increases, the threshold temperature Tsa increases.

[0029] In step S130 shown in Figure 2, the control unit 13 determines whether the acquired temperature T obtained based on the temperature sensor 50 when the rotation speed command value CS increases is lower than the threshold temperature Tsa determined for the increased rotation speed command value CS, i.e., the second rotation speed command value CS2. If the control unit 13 determines in step S130 that the acquired temperature T is equal to or greater than the threshold temperature Tsa (step S130: NO), it does not perform the determination process (step S150). On the other hand, if the control unit 13 determines in step S130 that the acquired temperature T is lower than the threshold temperature Tsa (step S130: YES), it starts the determination process (step S140).

[0030] Thus, the control unit 13 can perform a determination process when the rotation speed command value CS changes from a first rotation speed command value CS1 to a second rotation speed command value CS2 which is higher than the first rotation speed command value CS1, and the acquired temperature T obtained based on the temperature sensor 50 when the rotation speed command value CS changes to the second rotation speed command value CS2 is lower than a threshold temperature Tsa determined for the second rotation speed command value CS2. In other words, the control method of this embodiment includes performing a determination process when the rotation speed command value CS changes from a first rotation speed command value CS1 to a second rotation speed command value CS2 which is higher than the first rotation speed command value CS1, and the acquired temperature T obtained based on the temperature sensor 50 when the rotation speed command value CS changes to the second rotation speed command value CS2 is lower than a threshold temperature Tsa determined for the second rotation speed command value CS2.

[0031] Furthermore, "the temperature T obtained when the rotational speed command value CS changes to the second rotational speed command value CS2" may be the temperature T obtained at the exact moment the rotational speed command value CS changes to the second rotational speed command value CS2, or it may be the temperature T obtained at a time close to the exact moment the rotational speed command value CS changes to the second rotational speed command value CS2. "The temperature T obtained at a time close to the exact moment the rotational speed command value CS changes to the second rotational speed command value CS2" includes, for example, the first temperature T obtained after the rotational speed command value CS has changed to the second rotational speed command value CS2.

[0032] Figure 4 shows an example of the change in the rotational speed N of the motor 20 and the change in the acquired temperature T obtained based on the temperature sensor 50 when the rotational speed command value CS increases. The upper graph in Figure 4 shows the change in the rotational speed N of the motor 20 over time. In the upper graph in Figure 4, the vertical axis represents the rotational speed N, and the horizontal axis represents time t. The rotational speed command value CS is indicated by a dashed line in the upper graph in Figure 4. The lower graph in Figure 4 shows the change in the acquired temperature T obtained based on the temperature sensor 50 over time. In the lower graph in Figure 4, the vertical axis represents the acquired temperature T, and the horizontal axis represents time t.

[0033] Figure 4 shows an example where the motor 20, which was stopped, is started to run at time t1. In the example in Figure 4, the rotational speed command value CS before time t1 is the first rotational speed command value CS1, which is zero. In the example in Figure 4, the rotational speed command value CS increases from the first rotational speed command value CS1 to the second rotational speed command value CS2 at time t1. As the rotational speed command value CS increases, the rotational speed N of the motor 20 also begins to increase. The rotational speed N of the motor 20 increases from the first rotational speed N1 to the second rotational speed N2 over a certain period of time from time t1. The first rotational speed N1 is the rotational speed N of the motor 20 adjusted by the control unit 13 when the rotational speed command value CS is the first rotational speed command value CS1. The first rotational speed N1 is the same value as the first rotational speed command value CS1, or a value such that the difference from the first rotational speed command value CS1 is less than or equal to a predetermined value. In the example in Figure 4, the first rotational speed N1 is zero. The second rotational speed N2 is the rotational speed N of the motor 20 that is adjusted by the control unit 13 when the rotational speed command value CS is the second rotational speed command value CS2. The second rotational speed N2 is the same value as the second rotational speed command value CS2, or a value such that the difference from the second rotational speed command value CS2 is less than or equal to a predetermined value.

[0034] In the example in Figure 4, the acquired temperature T at time t1 is value T1. In the example in Figure 4, the saturation temperature Ts when the motor 20 is rotated based on the second rotation speed command value CS2 is value T4. In the example in Figure 4, the threshold temperature Tsa determined for the second rotation speed command value CS2 is value T3, which is lower than value T4. Value T3 is higher than value T1. Therefore, in the example in Figure 4, if the rotation speed command value CS increases at time t1, the control unit 13 determines that both the determination conditions in steps S120 and S130 are met and starts the determination process.

[0035] In this embodiment, the control unit 13 performs a determination process according to the flowchart shown in Figure 5. As shown in Figure 5, when the determination process is started, the control unit 13 determines whether the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta (step S141). The predetermined threshold is, for example, greater than or equal to the maximum value of the variation that occurs in the acquired temperature T when the temperature of the object measured using the temperature sensor 50 has not changed. "Variation that occurs in the acquired temperature T when the temperature of the object has not changed" refers to, for example, the variation that occurs when the analog signal output from the temperature sensor 50 is converted to a digital signal. The state in which the change in the acquired temperature T is within a predetermined threshold is a state in which it can be determined that the acquired temperature T has not substantially changed. The predetermined time ta is, for example, about 10 seconds or more and 60 seconds or less.

[0036] If the control unit 13 determines that the change in the acquired temperature T has not remained within a predetermined threshold for a predetermined time ta, it repeatedly executes step S141 (step S141: NO). For example, if the rotation speed command value CS changes before it is determined that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta, the control unit 13 cancels the determination process. "If the rotation speed command value CS changes before it is determined that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta" includes the case where the rotation speed command value CS becomes zero and the motor 20 stops before it is determined that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta.

[0037] If the control unit 13 determines in step S141 that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta (step S141: YES), it determines whether the acquired temperature T is lower than the threshold temperature Tsa (step S142). In step S142, the control unit 13 determines whether the acquired temperature T at the time it determined that the change in the acquired temperature T remained within a predetermined threshold for a predetermined time ta is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. Alternatively, in step S142, the control unit 13 may determine whether the average value of the acquired temperature T acquired within the predetermined time ta is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. If the control unit 13 determines in step S142 that the acquired temperature T is greater than or equal to the threshold temperature Tsa (step S142: NO), it terminates the determination process (step S144).

[0038] In step S142, the control unit 13 determines that the acquired temperature T is lower than the threshold temperature Tsa (step S142: YES), and outputs an error signal (step S143). This error signal indicates that there is an abnormality in the temperature sensor 50. More specifically, this error signal indicates that there is an output sticking failure in the temperature sensor 50. In step S143, the control unit 13 outputs this error signal to the higher-level control unit. Thus, in the determination process, the control unit 13 outputs a signal indicating that there is an abnormality in the temperature sensor 50, i.e., the error signal described above, when the change in the acquired temperature T remains within a predetermined threshold for a predetermined time ta, and the acquired temperature T is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. In other words, the determination process includes outputting an error signal indicating that there is an abnormality in the temperature sensor 50 when the change in the acquired temperature T remains within a predetermined threshold for a predetermined time ta, and the acquired temperature T is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. After outputting the error signal, the control unit 13 terminates the determination process (step S144).

[0039] The determination process will be explained in more detail using the example in Figure 4. First, we will explain the case in Figure 4 where the determination process is performed when the temperature sensor 50 is functioning normally. In the example in Figure 4, if the temperature sensor 50 is functioning normally, the acquired temperature T changes from time t1 onwards as shown by the waveform Wt indicated by the dashed line in the lower graph of Figure 4. In the example in Figure 4, if the temperature sensor 50 is functioning normally, as shown by the waveform Wt, the acquired temperature T increases logarithmically with respect to time t from value T1, and saturates at value T4. In the example in Figure 4, if the temperature sensor 50 is functioning normally, at time t4, which is after time t1, the value of the acquired temperature T becomes value T4, which is the saturation temperature Ts. Since the acquired temperature T stops changing or hardly changes at the saturation temperature Ts, the amount of change in the acquired temperature T will be within the predetermined threshold mentioned above. Therefore, when the acquired temperature T changes as shown in waveform Wt, at time t5, after a predetermined time ta has elapsed from time t4, the control unit 13 determines that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta (step S141: YES). In this case, the control unit 13 determines, for example, whether the acquired temperature T at time t5 is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2 (step S142). When the acquired temperature T changes as shown in waveform Wt, the acquired temperature T at time t5 is the saturation temperature Ts, which is value T4, and is therefore higher than the threshold temperature Tsa, which is value T3, determined for the second rotation speed command value CS2. Therefore, in step S142, the control unit 13 determines that the acquired temperature T is not lower than the threshold temperature Tsa (step S142: NO), and terminates the determination process (S144).

[0040] Next, we will explain the case in the example of Figure 4 where an output lock failure occurs in the temperature sensor 50 at time t2, which is after time t1 and before time t4. In this case, the acquired temperature T changes as shown by the solid line in the lower graph of Figure 4. Specifically, in this case, the acquired temperature T changes along the waveform Wt from time t1 to time t2, and at time t2 it becomes constant or nearly constant at value T2. Value T2 is higher than value T1 and lower than value T3. "The acquired temperature T becomes nearly constant at value T2" ​​means, for example, that there is a fluctuation in value around value T2, and the amount of change in said fluctuation is within the predetermined threshold mentioned above. Since the acquired temperature T is constant or nearly constant at value T2 from time t2 onward, the amount of change in the acquired temperature T is within the predetermined threshold mentioned above. Therefore, when the acquired temperature T changes as shown by the solid line in the lower graph of Figure 4, at time t3, after a predetermined time ta has elapsed from time t2, the control unit 13 determines that the change in the acquired temperature T has remained within a predetermined threshold for a predetermined time ta (step S141: YES). In this case, the control unit 13 determines, for example, whether the acquired temperature T at time t3 is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2 (step S142). When the acquired temperature T changes as shown by the solid line in the lower graph of Figure 4, the acquired temperature T at time t3 is value T2, which is lower than value T3, which is the threshold temperature Tsa determined for the second rotation speed command value CS2. Therefore, in step S142, the control unit 13 determines that the acquired temperature T is lower than the threshold temperature Tsa (step S142: YES) and outputs an error signal (step S143). After outputting the error signal, the control unit 13 terminates the determination process (S144).

[0041] As described above, in the determination process, the control unit 13 outputs an error signal indicating that there is a malfunction in the temperature sensor 50 if the change in the acquired temperature T remains within a predetermined threshold for a predetermined time ta, and the acquired temperature T is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. In other words, the determination process includes outputting an error signal indicating that there is a malfunction in the temperature sensor 50 if the change in the acquired temperature T remains within a predetermined threshold for a predetermined time ta, and the acquired temperature T is lower than the threshold temperature Tsa determined for the second rotation speed command value CS2. Therefore, when the acquired temperature T stops changing or stops changing almost completely, and the acquired temperature T is lower than the threshold temperature Tsa based on the saturation temperature Ts, the control unit 13 can determine that the state of no change is not due to the acquired temperature T reaching the saturation temperature Ts, but rather due to the acquired temperature T not changing normally. This allows the control device 10 to detect an output sticking failure in the temperature sensor 50. Therefore, a malfunction of the temperature sensor 50 can be detected early, and the malfunction of the object whose temperature is measured by the temperature sensor 50 can be suppressed.

[0042] For example, when the rotation speed command value CS decreases, the heat generated by the rotation of the motor 20 decreases, but the temperature of the object whose temperature is measured using the temperature sensor 50 does not change as easily as when the rotation speed command value CS increases. Therefore, when attempting to detect an output sticking failure based on the change in acquired temperature T when the rotation speed command value CS decreases, the possibility of misjudgment increases compared to when the rotation speed command value CS increases. Furthermore, even when the rotation speed command value CS increases, if the acquired temperature T at the time the rotation speed command value CS increases is above the threshold temperature Tsa determined for the increased rotation speed command value CS, the acquired temperature T will not fall below the threshold temperature Tsa. Therefore, the control unit 13 cannot determine whether the state in which the acquired temperature T no longer changes is a state in which the acquired temperature T has reached the saturation temperature Ts, or a state in which an output sticking failure has occurred in the temperature sensor 50.

[0043] To address the above problem, in this embodiment, the control unit 13 executes a determination process when the rotation speed command value CS changes from a first rotation speed command value CS1 to a second rotation speed command value CS2 which is higher than the first rotation speed command value CS1, and the acquired temperature T obtained based on the temperature sensor 50 when the rotation speed command value CS changes to the second rotation speed command value CS2 is lower than a threshold temperature Tsa determined for the second rotation speed command value CS2. In other words, the control method of this embodiment includes executing a determination process when the rotation speed command value CS changes from a first rotation speed command value CS1 to a second rotation speed command value CS2 which is higher than the first rotation speed command value CS1, and the acquired temperature T obtained based on the temperature sensor 50 when the rotation speed command value CS changes to the second rotation speed command value CS2 is lower than a threshold temperature Tsa determined for the second rotation speed command value CS2. Therefore, the determination process is executed when the acquired temperature T rises from a state where it is lower than the threshold temperature Tsa. Therefore, it is possible to accurately determine whether or not an output sticking failure has occurred in the temperature sensor 50 while suppressing erroneous judgments by the control unit 13 during the determination process.

[0044] In this embodiment, each threshold temperature Tsa determined for each rotation speed command value CS is lower than the acquired temperature T value at which the motor 20 saturates when the motor 20 is rotated based on each rotation speed command value CS when the temperature sensor 50 is functioning normally, i.e., the saturation temperature Ts. Therefore, even if there is variation in the saturation temperature Ts and the acquired temperature T stops changing at a lower-than-usual saturation temperature Ts, it is possible to suppress the control unit 13 from mistakenly determining that the state at which the low saturation temperature Ts has been reached is a state caused by an output sticking failure. By setting each threshold temperature Tsa to, for example, the lowest value of each saturation temperature Ts when variation occurs, it is possible to more effectively suppress the control unit 13 from mistakenly determining that the state at which the acquired temperature T stops changing at a value lower than each threshold temperature Tsa is a state caused by reaching the saturation temperature Ts.

[0045] In this embodiment, the temperature sensor 50 is attached to the substrate 15 on which the control unit 13 is mounted. In other words, the control method of this embodiment includes acquiring the temperature of the substrate 15 on which the control unit 13 that performs the determination process is mounted as the acquired temperature T based on the temperature sensor 50. Therefore, the control unit 13 can acquire the temperature of the substrate 15 as the acquired temperature T and can determine whether the temperature of each element mounted on the substrate 15 is within an appropriate temperature range. This makes it possible to suppress the failure of each element mounted on the substrate 15 due to heat. As described above, in this embodiment, since the control unit 13 can detect output sticking failures that occur in the temperature sensor 50, failures of the temperature sensor 50 can be detected early, and failures of elements mounted on the substrate 15 due to heat can be further suppressed.

[0046] In this embodiment, the relationship between the rotational speed command value CS and the threshold temperature Tsa is expressed by a linear function. Therefore, the threshold temperature Tsa can be appropriately determined according to the rotational speed command value CS. Consequently, the above-described determination process can be executed with high accuracy regardless of the value to which the rotational speed command value CS rises, and the occurrence of misjudgments in the determination process can be further suppressed.

[0047] The control unit 13 is a computer that executes the control method including the determination process of this embodiment described above. The control device 10 has a program installed that causes the control unit 13, which is the computer, to execute the control method including the determination process described above. At least part of the functions of the control unit 13 are realized, for example, by executing the program, i.e., software, stored in the storage unit 14.

[0048] At least a portion of the functions of the control unit 13 may be implemented by hardware including circuit components such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or by collaboration between software and hardware. The storage unit 14, which stores a program that causes the control unit 13, which is a computer, to execute the control method including the determination process of this embodiment described above, may be implemented by a storage medium such as RAM (Random Access Memory), ROM (Read Only Memory), HDD (hard disk drive), and flash memory. The storage unit 14 is not particularly limited as long as it can store a program that causes the computer to execute the control method including the determination process of this embodiment described above, and may be a microcomputer or a disk medium such as a CD-ROM. The storage unit 14 may be provided outside the control device 10. In this case, the control unit 13 may communicate with the storage unit 14 by wired communication or wireless communication and execute the program stored in the storage unit 14.

[0049] The present invention is not limited to the embodiments described above, and other configurations and methods may be adopted within the scope of the technical idea of ​​the present invention. The threshold temperature may be any value as long as it is determined based on the value of the acquired temperature at which saturation occurs when the motor is rotated based on the rotation speed command value when the temperature sensor is functioning normally. The relationship between the rotation speed command value and the threshold temperature is not particularly limited. The threshold temperature may be determined for each predetermined range of the rotation speed command value. The object whose temperature is measured using the temperature sensor is not particularly limited and may be other than a substrate. The object whose temperature is measured using the temperature sensor may be a fluid such as oil delivered by an electric pump. The applications of the electric pump to which the present invention is applied are not particularly limited. The electric pump may be mounted on any equipment. The electric pump does not have to be mounted on a vehicle.

[0050] Furthermore, this technology can be configured as follows: (1) A control device for an electric pump equipped with a motor and a temperature sensor, comprising a control unit that rotates the motor based on a rotation speed command value, wherein the control unit can perform a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value that is higher than the first rotation speed command value, and the acquired temperature obtained based on the temperature sensor when the rotation speed command value changes to the second rotation speed command value is lower than a threshold temperature determined for the second rotation speed command value, wherein the threshold temperature is a temperature determined based on the value of the acquired temperature that saturates when the motor is rotated based on the rotation speed command value when the temperature sensor is functioning normally, and in the determination process, the control unit outputs a signal indicating that there is an abnormality in the temperature sensor when the amount of change in the acquired temperature remains within a predetermined threshold for a predetermined time and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value. (2) The control device according to (1), wherein each threshold temperature determined for each rotation speed command value is lower than the value of the acquired temperature at which saturation occurs when the motor is rotated based on each rotation speed command value when the temperature sensor is functioning normally. (3) The control device according to (1) or (2), comprising a circuit board on which the control unit is mounted, and the temperature sensor being attached to the circuit board. (4) The control device according to any one of (1) to (3), wherein the relationship between the rotational speed command value and the threshold temperature is expressed by a linear function. (5) An electric pump comprising a control device as described in any one of (1) to (4), the motor, a pump unit driven by the motor, and the temperature sensor. (6) A control method for an electric pump comprising a motor and a temperature sensor, comprising: rotating the motor based on a rotation speed command value; and executing a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value higher than the first rotation speed command value, and the acquired temperature obtained based on the temperature sensor when the rotation speed command value changes to the second rotation speed command value is lower than a threshold temperature determined for the second rotation speed command value, wherein the threshold temperature is a temperature determined based on the value of the acquired temperature that saturates when the motor is rotated based on the rotation speed command value when the temperature sensor is functioning normally, and the determination process includes outputting a signal indicating that there is an abnormality in the temperature sensor when the amount of change in the acquired temperature remains within a predetermined threshold for a predetermined time and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value. (7) The control method according to (6), wherein each threshold temperature determined for each rotation speed command value is lower than the value of the acquired temperature at which saturation occurs when the motor is rotated based on each rotation speed command value when the temperature sensor is functioning normally. (8) The control method according to (6) or (7), which includes obtaining the temperature of a substrate on which the control unit that performs the determination process is mounted as the acquired temperature based on the temperature sensor. (9) The control method according to any one of (6) to (8), wherein the relationship between the rotational speed command value and the threshold temperature is expressed by a linear function. (10) A program that causes a computer to execute any of the control methods described in (6) through (9).

[0051] The configurations and methods described herein can be combined as appropriate, within the bounds of non-inconsistency. [Explanation of Symbols]

[0052] 10...Control device, 13...Control unit, 15...Circuit board, 20...Motor, 30...Pump unit, 50...Temperature sensor, 100...Electric pump, CS...Rotation speed command value, CS1...First rotation speed command value, CS2...Second rotation speed command value, T...Acquired temperature, ta...Determined time, Tsa...Threshold temperature

Claims

1. A control device for an electric pump equipped with a motor and a temperature sensor, The system includes a control unit that rotates the motor based on a rotation speed command value, The control unit can perform a determination process when the rotation speed command value changes from a first rotation speed command value to a second rotation speed command value that is higher than the first rotation speed command value, and when the rotation speed command value changes to the second rotation speed command value, the acquired temperature obtained based on the temperature sensor is lower than a threshold temperature determined for the second rotation speed command value. The threshold temperature is determined based on the value of the acquired temperature at which saturation occurs when the motor is rotated based on the rotation speed command value, assuming the temperature sensor is functioning correctly. In the determination process, the control unit outputs a signal indicating that there is an abnormality in the temperature sensor when the amount of change in the acquired temperature remains within a predetermined threshold for a predetermined period of time, and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value.

2. The control device according to claim 1, wherein each threshold temperature determined for each rotation speed command value is lower than the value of the acquired temperature at which saturation occurs when the motor is rotated based on each rotation speed command value when the temperature sensor is functioning normally.

3. The control unit is mounted on a circuit board, The control device according to claim 1, wherein the temperature sensor is attached to the substrate.

4. The control device according to claim 1, wherein the relationship between the rotational speed command value and the threshold temperature is expressed by a linear function.

5. A control device according to any one of claims 1 to 4, The motor and, A pump unit driven by the aforementioned motor, The temperature sensor and, An electric pump equipped with the following features.

6. A control method for an electric pump equipped with a motor and a temperature sensor, The motor is rotated based on the rotation speed command value, The determination process is performed when the rotational speed command value changes from a first rotational speed command value to a second rotational speed command value that is higher than the first rotational speed command value, and when the rotational speed command value changes to the second rotational speed command value, the acquired temperature obtained based on the temperature sensor is lower than a threshold temperature determined for the second rotational speed command value. Includes, The threshold temperature is determined based on the value of the acquired temperature at which saturation occurs when the motor is rotated based on the rotation speed command value, assuming the temperature sensor is functioning correctly. The determination process is a control method that includes outputting a signal indicating that there is an abnormality in the temperature sensor when the amount of change in the acquired temperature remains within a predetermined threshold for a predetermined period of time, and the acquired temperature is lower than the threshold temperature determined for the second rotation speed command value.

7. The control method according to claim 6, wherein each threshold temperature determined for each rotation speed command value is lower than the value of the acquired temperature at which saturation occurs when the motor is rotated based on each rotation speed command value when the temperature sensor is functioning normally.

8. The control method according to claim 6, which includes obtaining the temperature of a substrate on which the control unit that performs the determination process is mounted as the acquired temperature based on the temperature sensor.

9. The control method according to claim 6, wherein the relationship between the rotational speed command value and the threshold temperature is expressed by a linear function.

10. A program that causes a computer to execute the control method described in any one of claims 6 to 9.

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