Electric pump and method for notifying fault condition of electric pump

Abstract

The present invention comprises: a pump; a motor that drives the pump; a motor drive unit that has a switch element and drives the motor by electric power output from the switch element; and a control unit that outputs, to the motor drive unit, a PWM signal for driving the switching element, wherein in the electric pump in which the PWM signal output from the control unit is used for monitoring a state of the motor, when the motor is abnormally stopped, the control unit sets the frequency of the PWM signal used for monitoring the state of the motor to a frequency outside a frequency domain used when the motor is normally used.

Description

[Technical field]

[0001] The present invention relates to an electric pump and a method for notifying a fault state of the electric pump. This application claims priority to U.S. Provisional Application No. 62 / 958,313, filed January 8, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] Patent Document 1 describes an electric pump that includes a control unit that outputs a pulse signal that indicates the rotation state of a motor. In the electric pump described in Patent Document 1, a motor drives a pump connected to the motor, and a drive unit including a plurality of semiconductor switching elements drives the motor with a three-phase AC voltage. An input signal for driving the motor is input from an ECU (electronic control unit) to a control unit of the electric pump. The control unit of the electric pump outputs a drive signal for driving the motor to the drive unit based on the input signal input from the ECU. The control unit of the electric pump also outputs a pulse signal indicating the rotation state of the motor to the ECU. The control unit is configured to change both the frequency and the duty ratio of the pulse signal so as to be able to distinguish whether the motor is in a driving state or a stopped state, and to distinguish a plurality of states of the motor in the stopped state. Specifically, the control unit combines information on the frequency of the pulse signal and information on the duty ratio, and outputs the combined information to the ECU as one pulse signal. The control unit is configured to be able to change (control) the frequency and the duty ratio of one pulse signal individually.

[0003] Patent document 1 also describes that when the motor is stopped, the control unit sets the frequency of the pulse signal to 4 Hz, and that the control unit changes the duty ratio of the pulse signal in response to multiple states of the motor when it is stopped. Furthermore, Patent Document 1 describes that when the motor is stopped normally, the control unit sets the frequency of the pulse signal to 4 Hz and the duty ratio of the pulse signal to 50%, and that when the motor is stopped normally, the input signal sent from the ECU to the control unit is a stop signal for stopping the motor.

[0004] Patent Document 1 also describes that when the motor is in a driving state (i.e., not stopped), the control unit varies the pulse signal within a frequency range different from 4 Hz depending on the motor rotation speed. In the electric pump described in Patent Document 1, when the motor rotation speed is 160 rpm or less, the frequency of the pulse signal is set to 4 Hz (even though the motor is not stopped), and when the motor rotation speed is higher than 160 rpm, the frequency of the pulse signal increases linearly as the motor rotation speed increases. Patent document 1 also describes that when the motor is operating normally, the control unit sets the duty ratio of the pulse signal to 50%, and when the motor is in an abnormal operating state due to idling of the pump, the control unit sets the duty ratio of the pulse signal to 70%, and that it is sufficient that the duty ratio when the motor is operating normally and the duty ratio when the motor is operating abnormally are different from each other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-080382 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a typical electric pump that uses a PWM (Pulse Width Modulation) signal as an I / F (interface) signal, the frequency of the PWM signal output (transmitted) from a control unit is used as a parameter indicating the rotation speed of the motor. When both the signal frequency and duty ratio are changed as in the technology described in Patent Document 1 in order to communicate the fault state of the electric pump motor to an ECU or the like, the ECU or the like needs to recognize both the signal frequency and duty ratio, which places a burden on the processing capacity of the ECU or the like.

[0007] In view of the above-mentioned problems, the present invention aims to provide an electric pump and a method for notifying a fault state of an electric pump that enables detailed monitoring of the state of the motor during an abnormal stop while suppressing an increase in the processing burden of monitoring the state of the motor. [Means for solving the problem]

[0008] One aspect of the present invention is an electric pump comprising a pump, a motor for driving the pump, a motor drive unit having a switching element and driving the motor with power output from the switching element, and a control unit for outputting a PWM signal for driving the switching element to the motor drive unit, wherein the PWM signal output from the control unit is used to monitor the condition of the motor, and when the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the condition of the motor to a frequency outside the frequency range used when the motor is normal.

[0009] One aspect of the present invention is an electric pump comprising: a pump; a motor for driving the pump; a motor drive unit having a switching element and driving the motor with power output from the switching element; and a control unit for outputting a PWM signal for driving the switching element to the motor drive unit, wherein the PWM signal output from the control unit is used to monitor the state of the motor, and when the motor stops abnormally, the control unit sets the duty ratio of the PWM signal used to monitor the state of the motor to a duty ratio different from the duty ratio used when the motor is normal, and the control unit comprises an output switching unit for switching whether to output the PWM signal to the motor drive unit, and when the motor stops abnormally, the output switching unit does not output the PWM signal used to monitor the state of the motor to the motor drive unit.

[0010] One aspect of the present invention is an electric pump comprising a pump, a motor for driving the pump, a motor drive unit having a switching element and driving the motor with power output from the switching element, and a control unit for outputting a PWM signal for driving the switching element to the motor drive unit, wherein the PWM signal output from the control unit is used to monitor the condition of the motor, and when the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the condition of the motor to a frequency outside the frequency range used when the motor is normal, and sets the duty ratio of the PWM signal used to monitor the condition of the motor to a duty ratio different from the duty ratio used when the motor is normal.

[0011] One aspect of the present invention is a method for notifying a fault state of an electric pump comprising a pump, a motor for driving the pump, a motor drive unit having a switching element and driving the motor using power output from the switching element, and a control unit for outputting a PWM signal to the motor drive unit that drives the switching element, wherein the PWM signal output from the control unit is used to monitor the state of the motor, the method comprising: a first step in which, when the motor is normal, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency within a first frequency range; and a second step in which, when the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency within a second frequency range different from the first frequency range.

[0012] One aspect of the present invention is a method for notifying a fault state of an electric pump comprising a pump, a motor for driving the pump, a motor drive unit having a switching element and driving the motor with power output from the switching element, and a control unit for outputting a PWM signal for driving the switching element to the motor drive unit, wherein the PWM signal output from the control unit is used to monitor the state of the motor, the method comprising: a first step in which, when the motor is normal, the control unit sets the duty ratio of the PWM signal used to monitor the state of the motor to a first duty ratio; and a second step in which, when the motor abnormally stops, the control unit sets the duty ratio of the PWM signal used to monitor the state of the motor to a second duty ratio different from the first duty ratio, and wherein the PWM signal used to monitor the state of the motor when the motor abnormally stops is not output to the motor drive unit. Effect of the Invention

[0013] According to the present invention, it is possible to provide an electric pump and a method for notifying a fault state of an electric pump that enable detailed monitoring of the state of a motor during an abnormal stop while suppressing an increase in the burden of processing to monitor the state of the motor. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram showing an example of a configuration of an electric pump and the like according to the first embodiment. [Diagram 2] 1 is a diagram showing an example of the relationship between the number of rotations (rotational speed) [rpm] during normal operation and during overrotation of a motor and the frequency [Hz] of a PWM signal output from a control unit to a motor drive unit or the like. [Diagram 3] 3 is a diagram showing an example of a waveform of a PWM signal output from a control unit in the case shown at point A in FIG. 2. FIG. [Figure 4] 4 is a diagram showing the waveform of a PWM signal used to monitor the state of a motor when the motor abnormally stops in a first example of the electric pump of the first embodiment. FIG. [Diagram 5] 13 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor when the motor abnormally stops in a third example of the electric pump of the first embodiment. FIG. [Figure 6] 13 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor when the motor abnormally stops in a fourth example of the electric pump of the first embodiment. FIG. [Figure 7] 4 is a flowchart illustrating an example of a process executed in the electric pump of the first embodiment. [Figure 8] 13 is a diagram showing the waveform of a PWM signal used to monitor the state of a motor when the motor abnormally stops in a first example of an electric pump according to a second embodiment. FIG. [Figure 9] 13 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor when the motor abnormally stops in a third example of the electric pump according to the second embodiment. FIG. [Figure 10] 13 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor when the motor abnormally stops in a fourth example of the electric pump according to the second embodiment. FIG. [Figure 11] 10 is a flowchart illustrating an example of a process executed in the electric pump of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of an electric pump and a method for notifying a fault state of an electric pump according to the present invention will be described.

[0016] First Embodiment FIG. 1 is a diagram showing an example of the configuration of an electric pump 1 and the like according to the first embodiment. In the example shown in FIG. 1, the electric pump 1 includes a pump 11, a motor 12, a motor drive unit 13, and a control unit . The pump 11 performs pressure transfer of a fluid (medium) such as water, oil, fuel, etc. The motor 12 drives the pump 11. The motor driving unit 13 is, for example, an inverter circuit, and includes a switching element 13A and a rotation speed information processing unit 13B. The switching element 13A is, for example, a semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The motor driving unit 13 drives the motor 12 with power output from the switching element 13A. The rotation speed information processing unit 13B obtains information indicating the rotation speed of the motor 12 from the motor 12, and transmits the information to the control unit 14. The control unit 14 is, for example, a gate drive circuit, and outputs a PWM (Pulse Width Modulation) signal to the motor drive unit 13 for driving the switching element 13A.

[0017] 1, a monitoring device MD monitors the state of the motor 12. The PWM signal output from the control unit 14 is used for monitoring the state of the motor 12 by the monitoring device MD. That is, in the example shown in FIG. 1, the control unit 14 is configured to be able to output a PWM signal to both the motor driving unit 13 and the monitoring device MD. In detail, the control unit 14 includes an output switching unit 14A and a rotation speed feedback unit 14B. The output switching unit 14A switches whether or not to output a PWM signal to the motor driving unit 13. The rotation speed feedback unit 14B acquires information indicating the rotation speed of the motor 12 transmitted by the rotation speed information processing unit 13B. Furthermore, the rotation speed feedback unit 14B generates a PWM signal indicating the rotation speed of the motor 12 based on the information indicating the rotation speed of the motor 12. The control unit 14 transmits the PWM signal indicating the rotation speed of the motor 12 generated by the rotation speed feedback unit 14B to the monitoring device MD. That is, in the example shown in FIG. 1, the control unit 14 is capable of outputting a PWM signal for driving the switching element 13A to the motor drive unit 13, and is also capable of outputting a PWM signal indicating the rotation speed of the motor 12 to the monitoring device MD.

[0018] 2 is a diagram showing an example of the relationship between the number of rotations (rotational speed) [rpm] when motor 12 is normal and when it is overrotating, and the frequency [Hz] of the PWM signal output from control unit 14 to motor drive unit 13, etc. The normal state of motor 12 includes a time when motor 12 is rotating normally and a time when motor 12 is stopped normally. In the example shown in Figure 2, as shown at point A, when motor 12 rotates steadily at 5000 rpm, a PWM signal of 125 Hz is output from control unit 14 to motor drive unit 13, and is also output from control unit 14 to monitoring device MD. As shown by point B, when the motor 12 rotates steadily at 800 rpm, a 20 Hz PWM signal is output from the control unit 14 to the motor drive unit 13 and also from the control unit 14 to the monitoring device MD. As shown at point C, when motor 12 stops normally (i.e., when motor 12 is normal and the rotation speed of motor 12 is 0 rpm), a 4 Hz PWM signal is not output from control unit 14 to motor drive unit 13, but is output from control unit 14 to monitoring device MD. As shown by point D, when the motor 12 rotates at 8000 rpm (more specifically, over-rotates), a 200 Hz PWM signal is output from the control unit 14 to the motor drive unit 13, and is also output from the control unit 14 to the monitoring device MD.

[0019] Fig. 3 is a diagram showing an example of the waveform of the PWM signal output from the control unit 14 in the case shown at point A in Fig. 2. In detail, Fig. 3(A) shows an example of the waveform of the PWM signal output from the control unit 14 in the case shown at point A in Fig. 2, Fig. 3(B) shows an example of the waveform of the PWM signal output from the control unit 14 in the case shown at point B in Fig. 2, Fig. 3(C) shows an example of the waveform of the PWM signal output from the control unit 14 in the case shown at point C in Fig. 2, and Fig. 3(D) shows an example of the waveform of the PWM signal output from the control unit 14 in the case shown at point D in Fig. 2.

[0020] In the example shown in Figures 2 and 3(A), when the motor 12 rotates steadily at 5000 [rpm], the control unit 14 outputs a PWM signal with a frequency of 125 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 125 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 is rotating steadily at 5000 [rpm]. At this time, the control unit 14 sends a PWM signal to the motor control unit 13 to rotate the motor 12 at 5000 [rpm]. In the example shown in Figures 2 and 3(B), when the motor 12 rotates steadily at 800 [rpm], the control unit 14 outputs a PWM signal with a frequency of 20 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 20 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 is rotating steadily at 800 [rpm]. At this time, the control unit 14 outputs a PWM signal to the motor control unit 13 to rotate the motor 12 at 800 [rpm].

[0021] 2 and 3(C), when the motor 12 stops normally, the control unit 14 outputs a PWM signal with a frequency of 4 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 4 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 has stopped normally. At this time, the control unit 14 does not output a PWM signal to the motor control unit 13. 2 and 3(D), when the motor 12 over-rotates at 8000 rpm, the control unit 14 outputs a PWM signal with a frequency of 200 Hz and a duty ratio of 50% to the motor drive unit 13 and the monitoring device MD. Therefore, the monitoring device MD, which receives the PWM signal with a frequency of 200 Hz and a duty ratio of 50%, can recognize that the motor 12 is over-rotating at 8000 rpm. In detail, the monitoring device MD estimates that the electric pump 1 is in an abnormal load reduction state due to, for example, the loss of the pumping medium.

[0022] In the examples shown in Figures 2 and 3, the sections indicated by the bidirectional arrows in Figure 2 (sections where the frequency of the PWM signal is higher than 4 [Hz] and lower than 20 [Hz] (sections where the rotation speed of motor 12 is higher than 0 [rpm] and lower than 800 [rpm]) and sections where the frequency of the PWM signal is higher than 125 [Hz] (sections where the rotation speed of motor 12 is higher than 5000 [rpm])) correspond to areas that are not normally used.

[0023] FIG. 4 is a diagram showing a waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally in the first example of the electric pump 1 of the first embodiment. In detail, FIG. 4(A) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the voltage of a power source (not shown) supplying power to the motor 12 is excessive (i.e., when the power source voltage is excessively abnormal and the rotation speed of the motor 12 is 0 [rpm]). FIG. 4(B) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the voltage of a power source supplying power to the motor 12 is excessively low (i.e., when the power source voltage is excessively low and the rotation speed of the motor 12 is 0 [rpm]). FIG. 4(C) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the temperature of the motor 12 is excessive (i.e., when the temperature is excessively abnormal and the rotation speed of the motor 12 is 0 [rpm]).

[0024] 4(A), when the motor 12 stops abnormally due to excessive power supply voltage, the control unit 14 outputs a PWM signal with a frequency of 1 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 1 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 has stopped abnormally due to excessive power supply voltage. 4B, when the motor 12 stops abnormally because the power supply voltage is too low, the control unit 14 outputs a PWM signal with a frequency of 2.5 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 2.5 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 has stopped abnormally because the power supply voltage is too low. 4(C), when the motor 12 stops abnormally because the temperature of the motor 12 is excessively high, the control unit 14 outputs a PWM signal with a frequency of 8 [Hz] and a duty ratio of 50 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 8 [Hz] and a duty ratio of 50 [%] can recognize that the motor 12 has stopped abnormally because the temperature of the motor 12 is excessively high.

[0025] That is, in the first example of the electric pump 1 of the first embodiment shown in FIG. 4, when the motor 12 abnormally stops, only the frequency of the PWM signal output from the control unit 14 is varied, thereby enabling the monitoring device MD to monitor in detail the state of the motor 12 at the time of the abnormal stop. That is, in the first example of the electric pump 1 of the first embodiment, the monitoring device MD can recognize the cause of the abnormal stop of the motor 12 (excessive power supply voltage, insufficient power supply voltage, or excessive motor temperature) without the need to vary the duty ratio of the PWM signal output from the control unit 14, that is, without the need to increase the processing burden of monitoring the state of the motor 12.

[0026] In other words, in the first example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally, the control unit 14 sets the frequency of the PWM signal used to monitor the status of the motor 12 to a frequency (1 Hz, 2.5 Hz, 8 Hz) outside the frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal. Therefore, in the first example of the electric pump 1 of the first embodiment, the monitoring device MD can distinguish between a state in which the motor 12 is normally stopped and a state in which the motor 12 is abnormally stopped, simply by recognizing the frequency of the PWM signal. In detail, the monitoring device MD can identify the cause of the abnormal stop of the motor 12, simply by recognizing the frequency of the PWM signal.

[0027] [Table 1]

[0028] Table 1 shows the PWM signals used to monitor the state of the motor 12 when the motor 12 stops due to an abnormality in the second example of the electric pump 1 of the first embodiment. As shown in Table 1, in the second example of the electric pump 1 of the first embodiment, when the motor 12 stops normally, the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 Hz, which is within the frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%.

[0029] In a second example of the electric pump 1 of the first embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault A ("undervoltage" of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 1 Hz, outside the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%. In a second example of the electric pump 1 of the first embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault B (``overvoltage'' of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 2 [Hz], outside the frequency range used when the motor 12 is normal (4 [Hz], 20 [Hz] or more and 125 [Hz] or less), and sets the duty ratio of the PWM signal to 50 [%]. In a second example of the electric pump 1 of the first embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault C ("overcurrent" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 6 Hz, outside the frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%.

[0030] In a second example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault D ("overheating" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 7 Hz, outside the frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%. In a second example of the electric pump 1 of the first embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault E ("motor lock"), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 8 Hz, outside the frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%. In a second example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault F (``command abnormality (ground fault)'' to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 10 Hz, outside the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%.

[0031] In a second example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 12 Hz, outside the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%. That is, in the second example of the electric pump 1 of the first embodiment, the duty ratio of the PWM signal used to monitor the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault) to the motor drive unit 13) and failure G (command abnormality (frequency abnormality at the time of stop command) to the motor drive unit 13) is set to 50% which is equal to the duty ratio used when the motor 12 is stopped normally. In a second example of the electric pump 1 of the first embodiment, when the motor 12 is rotating normally, the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 20 Hz to 125 Hz within the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%.

[0032] In other words, in the second example of the electric pump 1 of the first embodiment, when the motor 12 abnormally stops, by varying only the frequency of the PWM signal output from the control unit 14, it is possible for the monitoring device MD to monitor in detail the state of the motor 12 at the time of the abnormal stop. That is, in the second example of the electric pump 1 of the first embodiment, the monitoring device MD can recognize the cause of the abnormal stop of the motor 12 (excessive power supply voltage, excessive power supply voltage, motor overcurrent, motor overheating, motor lock, command abnormality (ground fault) or command abnormality (frequency abnormality at the time of the stop command)) without the need to vary the duty ratio of the PWM signal output from the control unit 14, that is, without the need to increase the processing burden of monitoring the state of the motor 12. Furthermore, in a second example of the electric pump 1 of the first embodiment, the output switching unit 14A of the control unit 14 does not output to the motor driving unit 13 a PWM signal used for monitoring the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault) to the motor driving unit 13), and failure G (command abnormality (frequency abnormality when issuing a stop command) to the motor driving unit 13).

[0033] As described above, in the second example of the electric pump 1 of the first embodiment, the monitoring device MD recognizes the frequency of the PWM signal and thereby identifies seven types of fault conditions as the cause of the abnormal stop of the motor 12, but in another example of the electric pump 1 of the first embodiment, the monitoring device MD may recognize the frequency of the PWM signal and thereby identify two types of fault conditions as the cause of the abnormal stop of the motor 12. In this example, when the fault state of motor 12 is a first fault state (e.g., "undervoltage" of the power supply), control unit 14 sets the frequency of the PWM signal used to monitor the state of motor 12 to a first frequency (e.g., 1 Hz) outside the frequency range used when motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less). When the fault state of the motor 12 is a second fault state (e.g., "overvoltage" of the power supply) different from the first fault state (e.g., "undervoltage" of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to a second frequency (e.g., 2 [Hz]) that is outside the frequency range (4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal and is different from the first frequency (e.g., 1 [Hz]). Furthermore, the control unit 14 sets the duty ratio of the PWM signal used to monitor the motor 12 in a first fault state (e.g., an "undervoltage" of the power supply) and the duty ratio of the PWM signal used to monitor the motor 12 in a second fault state (e.g., an "overvoltage" of the power supply) to a value equal to the duty ratio (50%]) used when the motor 12 is normally stopped. Also in this example, the output switching unit 14A does not output to the motor driving unit 13 a PWM signal used to monitor the motor 12 in a first fault state (e.g., an “undervoltage” of the power supply) and a second fault state (e.g., an “overvoltage” of the power supply).

[0034] FIG. 5 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally in a third example of the electric pump 1 according to the first embodiment. As described above, in the second example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 12 Hz, outside the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%. On the other hand, in a third example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the PWM signal used to monitor the state of the motor 12 to a signal composed of a pulse train combining a first pulse with a frequency of 8 [Hz] and a second pulse with a frequency of 15 [Hz], as shown in Figure 5.

[0035] In other words, in a third example of the electric pump 1 of the first embodiment, the control unit 14 sets the PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally to a signal consisting of a pulse train combining a first pulse at a first frequency (8 [Hz]) outside the frequency range (4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal, and a second pulse at a second frequency (15 [Hz]) outside the frequency range (4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal and different from the first frequency (8 [Hz]). Therefore, in the third example of the electric pump 1 of the first embodiment, the control unit 14 can output to the monitoring device MD a variety of PWM signals used to monitor the state of the motor 12 when the motor 12 abnormally stops, making it possible to identify a wider variety of fault conditions than seven types. Also in the third example of the electric pump 1 of the first embodiment, the output switching unit 14A does not output to the motor drive unit 13 a PWM signal used for monitoring the state of the motor 12 when the motor 12 stops abnormally.

[0036] FIG. 6 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally in a fourth example of the electric pump 1 according to the first embodiment. In a fourth example of the electric pump 1 of the first embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the PWM signal used to monitor the state of the motor 12 to a signal composed of a pulse train combining a first pulse having a frequency of 8 [Hz] repeated, for example, three times and a second pulse having a frequency of 15 [Hz] repeated, for example, three times, as shown in FIG. 6.

[0037] In other words, in a fourth example of the electric pump 1 of the first embodiment, the control unit 14 sets the PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally to a signal composed of a pulse train combining a first pulse repeated multiple times at a first frequency (8 [Hz]) outside the frequency range (4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal, and a second pulse repeated multiple times at a second frequency (15 [Hz]) that is different from the first frequency (8 [Hz]) and outside the frequency range (4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal. Therefore, in the fourth example of the electric pump 1 of the first embodiment, as in the third example of the electric pump 1 of the first embodiment, the control unit 14 can output to the monitoring device MD many types of PWM signals used to monitor the state of the motor 12 when the motor 12 abnormally stops, and can identify a wider range of fault conditions than seven types. Also in the fourth example of the electric pump 1 of the first embodiment, the output switching unit 14A does not output to the motor drive unit 13 a PWM signal used for monitoring the state of the motor 12 when the motor 12 stops abnormally.

[0038] FIG. 7 is a flowchart illustrating an example of a process executed in the electric pump 1 of the first embodiment. In the example shown in Fig. 7, in step S11, the control unit 14 judges whether the motor 12 is in a normal state. For example, when the voltage of the power supply supplying power to the motor 12 is excessively high, when the voltage of the power supply is excessively low, when the temperature of the motor 12 is excessive (i.e., when the motor 12 is overheated), when the current flowing through the motor 12 is excessive (i.e., when the motor 12 is overcurrented), when the motor is locked, when a command abnormality (ground fault) occurs to the motor drive unit 13, when a command abnormality (frequency abnormality at the time of a stop command) occurs to the motor drive unit 13, when the motor 12 is in an overrotating state, etc., the control unit 14 judges that the motor 12 is in an abnormal state and proceeds to step S17. On the other hand, when the control unit 14 judges that the motor is in a normal state, the control unit 14 proceeds to step S12.

[0039] In step S12, the control unit 14 determines whether or not the motor is stopped. If the control unit 14 determines that the motor is stopped (i.e., the motor 12 is normally stopped), the process proceeds to step S13. On the other hand, if the control unit 14 determines that the motor is not stopped (i.e., the motor 12 is rotating steadily), the process proceeds to step S15.

[0040] In step S13, the control unit 14 sets the frequency of the PWM signal to 4 Hz, which is a frequency within the first frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%. Next, in step S14, the control unit 14 outputs the PWM signal in which the frequency (4 [Hz]) and duty ratio (50 [%]) were set in step S13 to the monitoring device MD without outputting the signal to the motor driving unit 13. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12.

[0041] In step S15, the control unit 14 sets the frequency of the PWM signal to a frequency within the first frequency range (4 Hz, 20 Hz to 125 Hz) used when the motor 12 is normal, which is 20 Hz to 125 Hz, and sets the duty ratio of the PWM signal to 50%. Next, in step S16, the control unit 14 outputs a PWM signal whose frequency (a frequency between 20 [Hz] and 125 [Hz]) and duty ratio (50 [%]) have been set in step S15 to the monitoring device MD. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12. At this time, the control unit 14 outputs a PWM signal to the motor control unit 13 for rotating the motor 12 at a rotation speed between 800 [rpm] and 5000 [rpm].

[0042] In step S17, the control unit 14 determines whether or not the motor is stopped. If the control unit 14 determines that the motor is stopped (i.e., the motor 12 has stopped abnormally), the process proceeds to step S18. On the other hand, if the control unit 14 determines that the motor is not stopped (i.e., the motor 12 is rotating abnormally), the process proceeds to step S20.

[0043] In step S18, the control unit 14 sets the frequency of the PWM signal to a frequency (e.g., 1 Hz, 2.5 Hz, 8 Hz, etc.) within a second frequency range (less than 4 Hz, a frequency range higher than 4 Hz and lower than 20 Hz) different from the first frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%. Next, in step S19, the control unit 14 outputs the PWM signal whose frequency (for example, a frequency of 1 [Hz], 2.5 [Hz], 8 [Hz], etc.) and duty ratio (50 [%]) have been set in step S18 to the monitoring device MD without outputting the signal to the motor driving unit 13. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12.

[0044] In step S20, the control unit 14 sets the frequency of the PWM signal to a frequency (e.g., 200 Hz) higher than the first frequency range (4 Hz, 20 Hz or more and 125 Hz or less) used when the motor 12 is normal, and sets the duty ratio of the PWM signal to 50%. Next, in step S21, the control unit 14 outputs the PWM signal whose frequency (e.g., 200 [Hz]) and duty ratio (50 [%]) have been set in step S20 to the monitoring device MD. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12. At this time, the control unit 14 outputs the PWM signal for rotating the motor 12 to the motor control unit 13.

[0045] <Second embodiment> A second embodiment of the electric pump and the method for notifying of a fault state of the electric pump according to the present invention will now be described. The electric pump 1 of the second embodiment is configured similarly to the electric pump 1 of the above-described first embodiment, except for the points described below. Therefore, the electric pump 1 of the second embodiment can achieve the same effects as the electric pump 1 of the above-described first embodiment, except for the points described below.

[0046] FIG. 8 is a diagram showing a waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally in the first example of the electric pump 1 of the second embodiment. In detail, FIG. 8(A) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the voltage of the power supply supplying power to the motor 12 is excessive (that is, when the power supply voltage is excessively abnormal and the rotation speed of the motor 12 is 0 [rpm]). FIG. 8(B) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the voltage of the power supply supplying power to the motor 12 is excessively low (that is, when the power supply voltage is excessively low and the rotation speed of the motor 12 is 0 [rpm]). FIG. 8(C) shows an example of a waveform of a PWM signal output from the control unit 14 when the motor 12 stops abnormally because the temperature of the motor 12 is excessive (that is, when the temperature is excessively abnormal and the rotation speed of the motor 12 is 0 [rpm]).

[0047] 8(A), when the motor 12 stops abnormally due to excessive power supply voltage, the control unit 14 outputs a PWM signal with a frequency of 4 [Hz] and a duty ratio of 10 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 4 [Hz] and a duty ratio of 10 [%] can recognize that the motor 12 has stopped abnormally due to excessive power supply voltage. 8(B), when the motor 12 stops abnormally because the power supply voltage is too low, the control unit 14 outputs a PWM signal with a frequency of 4 [Hz] and a duty ratio of 20 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 4 [Hz] and a duty ratio of 20 [%] can recognize that the motor 12 has stopped abnormally because the power supply voltage is too low. 8(C), when the motor 12 stops abnormally because the temperature of the motor 12 is excessively high, the control unit 14 outputs a PWM signal with a frequency of 4 [Hz] and a duty ratio of 80 [%] to the monitoring device MD. Therefore, the monitoring device MD that receives the PWM signal with a frequency of 4 [Hz] and a duty ratio of 80 [%] can recognize that the motor 12 has stopped abnormally because the temperature of the motor 12 is excessively high.

[0048] That is, in the first example of the electric pump 1 of the second embodiment shown in FIG. 8, when the motor 12 abnormally stops, by varying only the duty ratio of the PWM signal output from the control unit 14, it is possible for the monitoring device MD to monitor in detail the state of the motor 12 at the time of the abnormal stop. That is, in the first example of the electric pump 1 of the second embodiment, the monitoring device MD can recognize the cause of the abnormal stop of the motor 12 (excessive power supply voltage, insufficient power supply voltage, or excessive motor temperature) without the need to vary the frequency of the PWM signal output from the control unit 14, that is, without the need to increase the processing burden of monitoring the state of the motor 12.

[0049] In other words, in the first example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally, the control unit 14 sets the duty ratio of the PWM signal used to monitor the status of the motor 12 to a duty ratio (10%, 20%, 80%) different from the duty ratio (50%]) used when the motor 12 is normal. Therefore, in the first example of the electric pump 1 of the second embodiment, the monitoring device MD can distinguish between a state in which the motor 12 is normally stopped and a state in which the motor 12 is abnormally stopped, simply by recognizing the duty ratio of the PWM signal. In detail, the monitoring device MD can identify the cause of the abnormal stop of the motor 12, simply by recognizing the duty ratio of the PWM signal. Furthermore, in the first example of the electric pump 1 of the second embodiment, the output switching unit 14A of the control unit 14 does not output to the motor drive unit 13 a PWM signal used for monitoring the state of the motor 12 when the motor 12 stops abnormally.

[0050] [Table 2]

[0051] Table 2 shows the PWM signals used to monitor the state of the motor 12 when the motor 12 stops due to an abnormality in the second example of the electric pump 1 according to the second embodiment. As shown in Table 2, in the second example of the electric pump 1 of the second embodiment, when the motor 12 stops normally, the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz] and sets the duty ratio of the PWM signal to 50 [%].

[0052] In a second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault A (``undervoltage'' of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 5 [%], which is different from the duty ratio (50 [%]) used when the motor 12 is normal. In a second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault B (``overvoltage'' of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 10 [%], which is different from 50 [%] and 5 [%]. In a second example of the electric pump 1 of the second embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault C ("overcurrent" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 20 [%,] which is different from 50 [%,] 5 [%] and 10 [%].

[0053] In a second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault D ("overheating" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 30 [%,] which is different from 50 [%,] 5 [%,] 10 [%] and 20 [%]. In a second example of the electric pump 1 of the second embodiment, when the motor 12 abnormally stops and the fault state of the motor 12 is fault E ("motor lock"), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 70 [%,] which is different from 50 [%,] 5 [%,] 10 [%,] 20 [%] and 30 [%]. In a second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault F ("command abnormality (ground fault)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 80 [%], which is different from 50 [%,], 5 [%,], 10 [%,], 20 [%,], 30 [%] and 70 [%].

[0054] In a second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 90 [%,] which is different from 50 [%,], 5 [%,], 10 [%,], 20 [%,], 30 [%,], 70 [%] and 80 [%]. That is, in the second example of the electric pump 1 of the second embodiment, the frequency of the PWM signal used to monitor the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault) to the motor drive unit 13) and failure G (command abnormality (frequency abnormality when stop command is issued) to the motor drive unit 13) is set to 4 Hz, which is equal to the frequency used when the motor 12 is stopped normally. In a second example of the electric pump 1 of the second embodiment, when the motor 12 is rotating normally, the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 20 [Hz] to 125 [Hz] within the frequency range used when the motor 12 is normal (4 [Hz], 20 [Hz] or more and 125 [Hz] or less), and sets the duty ratio of the PWM signal to 50 [%].

[0055] In other words, in the second example of the electric pump 1 of the second embodiment, when the motor 12 abnormally stops, the monitoring device MD can monitor in detail the state of the motor 12 at the time of the abnormal stop by varying only the duty ratio of the PWM signal output from the control unit 14. That is, in the second example of the electric pump 1 of the second embodiment, the monitoring device MD can recognize the cause of the abnormal stop of the motor 12 (excessive power supply voltage, excessive power supply voltage, motor overcurrent, motor overheating, motor lock, command abnormality (ground fault) or command abnormality (frequency abnormality at the time of stop command)) without the need to vary the frequency of the PWM signal output from the control unit 14, that is, without the need to increase the processing burden of monitoring the state of the motor 12. Furthermore, in a second example of the electric pump 1 of the second embodiment, the output switching unit 14A of the control unit 14 does not output to the motor driving unit 13 a PWM signal used for monitoring the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault) to the motor driving unit 13), and failure G (command abnormality (frequency abnormality when issuing a stop command) to the motor driving unit 13).

[0056] As described above, in the second example of the electric pump 1 of the second embodiment, the monitoring device MD recognizes the duty ratio of the PWM signal and thereby identifies seven types of fault conditions as the cause of the abnormal stop of the motor 12, but in another example of the electric pump 1 of the second embodiment, the monitoring device MD may recognize the duty ratio of the PWM signal and thereby identify two types of fault conditions as the cause of the abnormal stop of the motor 12. In this example, when the fault state of the motor 12 is a first fault state (e.g., “undervoltage” of the power supply), the control unit 14 sets the duty ratio of the PWM signal used to monitor the state of the motor 12 to a first duty ratio (e.g., 5%]) different from the duty ratio (50%]) used when the motor 12 is normal. When the fault state of the motor 12 is a second fault state (e.g., "overvoltage" of the power supply) different from the first fault state (e.g., "undervoltage" of the power supply), the control unit 14 sets the duty ratio of the PWM signal used to monitor the state of the motor 12 to a second duty ratio (e.g., 10%]) different from the duty ratio (50%]) used when the motor 12 is normal and the first duty ratio (e.g., 5%]). Furthermore, the control unit 14 sets the frequency of the PWM signal used to monitor the motor 12 in a first fault state (e.g., an "undervoltage" of the power supply) and the frequency of the PWM signal used to monitor the motor 12 in a second fault state (e.g., an "overvoltage" of the power supply) to a value equal to the frequency (4 Hz) used when the motor 12 is normally stopped. Also in this example, the output switching unit 14A does not output to the motor driving unit 13 a PWM signal used to monitor the motor 12 in a first fault state (e.g., an “undervoltage” of the power supply) and a second fault state (e.g., an “overvoltage” of the power supply).

[0057] FIG. 9 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops due to an abnormality in a third example of the electric pump 1 according to the second embodiment. As described above, in the second example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the failure state of the motor 12 is failure G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 4 [Hz], and sets the duty ratio of the PWM signal to 90 [%], which is different from the duty ratio (50 [%]) used when the motor 12 is normal. On the other hand, in a third example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the PWM signal used to monitor the state of the motor 12 to a signal composed of a pulse train combining a first pulse with a duty ratio of 10[%] and a second pulse with a duty ratio of 30[%], as shown in Figure 9.

[0058] That is, in a third example of the electric pump 1 of the second embodiment, the control unit 14 sets the PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally to a signal composed of a pulse train combining a first pulse with a first duty ratio (10[%)) different from the duty ratio (50[%)) used when the motor 12 is normal, and a second pulse with a second duty ratio (30[%]) different from the duty ratio (50[%]) and the first duty ratio (10[%]) used when the motor 12 is normal. Therefore, in the third example of the electric pump 1 of the second embodiment, the control unit 14 can output to the monitoring device MD a variety of PWM signals used to monitor the state of the motor 12 when the motor 12 abnormally stops, making it possible to identify a wider variety of fault conditions than seven types. Also in the third example of the electric pump 1 of the second embodiment, the output switching unit 14A does not output to the motor drive unit 13 a PWM signal used for monitoring the state of the motor 12 when the motor 12 stops abnormally.

[0059] FIG. 10 is a diagram showing the waveform of a PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally in a fourth example of the electric pump 1 according to the second embodiment. In a fourth example of the electric pump 1 of the second embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the PWM signal used to monitor the state of the motor 12 to a signal composed of a pulse train combining a first pulse having a duty ratio of 10% repeated, for example, three times, and a second pulse having a duty ratio of 30% repeated, for example, three times, as shown in FIG. 10.

[0060] That is, in a fourth example of the electric pump 1 of the second embodiment, the control unit 14 sets the PWM signal used to monitor the state of the motor 12 when the motor 12 stops abnormally to a signal composed of a pulse train combining a first pulse repeated multiple times with a first duty ratio (10[%)) different from the duty ratio (50[%]) used when the motor 12 is normal, and a second pulse repeated multiple times with a second duty ratio (30[%]) different from the duty ratio (50[%]) and the first duty ratio (10[%]) used when the motor 12 is normal. Therefore, in the fourth example of the electric pump 1 of the second embodiment, as in the third example of the electric pump 1 of the second embodiment, the control unit 14 can output to the monitoring device MD many types of PWM signals used to monitor the state of the motor 12 when the motor 12 abnormally stops, and can identify a wider range of fault conditions than seven types. Also in the fourth example of the electric pump 1 of the second embodiment, the output switching unit 14A does not output to the motor drive unit 13 a PWM signal used for monitoring the state of the motor 12 when the motor 12 stops abnormally.

[0061] FIG. 11 is a flowchart illustrating an example of a process executed in the electric pump 1 according to the second embodiment. In the example shown in Fig. 11, in step S31, the control unit 14 judges whether the motor 12 is in a normal state. For example, when the voltage of the power supply supplying power to the motor 12 is excessively high, when the voltage of the power supply is excessively low, when the temperature of the motor 12 is excessive (i.e., when the motor 12 is overheated), when the current flowing through the motor 12 is excessive (i.e., when the motor 12 is overcurrented), when the motor is locked, when a command abnormality (ground fault) occurs to the motor drive unit 13, when a command abnormality (frequency abnormality at the time of a stop command) occurs to the motor drive unit 13, when the motor 12 is in an over-rotation state, etc., the control unit 14 judges that the motor 12 is in an abnormal state and proceeds to step S37. On the other hand, when the control unit 14 judges that the motor is in a normal state, the control unit 14 proceeds to step S32.

[0062] In step S32, the control unit 14 determines whether or not the motor is stopped. If the control unit 14 determines that the motor is stopped (i.e., the motor 12 is normally stopped), the process proceeds to step S33. On the other hand, if the control unit 14 determines that the motor is not stopped (i.e., the motor 12 is rotating steadily), the process proceeds to step S35.

[0063] In step S33, the control unit 14 sets the frequency of the PWM signal to a frequency (4 Hz) used when the motor 12 is stopped, and sets the duty ratio of the PWM signal to a first duty ratio (50%) used when the motor 12 is normal. Next, in step S34, the control unit 14 outputs the PWM signal in which the frequency (4 [Hz]) and duty ratio (50 [%]) were set in step S33 to the monitoring device MD without outputting the signal to the motor driving unit 13. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12.

[0064] In step S35, the control unit 14 sets the frequency of the PWM signal to a frequency within the frequency range (20 Hz or more and 125 Hz or less) used when the motor 12 is rotating normally, and sets the duty ratio of the PWM signal to a first duty ratio (50%]) used when the motor 12 is rotating normally. Next, in step S36, the control unit 14 outputs a PWM signal whose frequency (a frequency between 20 [Hz] and 125 [Hz]) and duty ratio (50 [%]) have been set in step S35 to the monitoring device MD. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12. At this time, the control unit 14 outputs a PWM signal to the motor control unit 13 for rotating the motor 12 at a rotation speed between 800 [rpm] and 5000 [rpm].

[0065] In step S37, the control unit 14 determines whether or not the motor is stopped. If the control unit 14 determines that the motor is stopped (i.e., the motor 12 has stopped abnormally), the process proceeds to step S38. On the other hand, if the control unit 14 determines that the motor is not stopped (i.e., the motor 12 is rotating abnormally), the process proceeds to step S40.

[0066] In step S38, the control unit 14 sets the frequency of the PWM signal to the frequency (4 Hz) used when the motor 12 is stopped, and sets the duty ratio of the PWM signal to a second duty ratio (e.g., 10%, 20%, 80%, etc.) different from the first duty ratio (50%). Next, in step S39, the control unit 14 outputs the PWM signal in which the frequency (4 [Hz]) and duty ratio (for example, "10%, " "20%, " "80%", etc.) have been set in step S38 to the monitoring device MD without outputting the signal to the motor driving unit 13. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12.

[0067] In step S40, the control unit 14 sets the frequency of the PWM signal to a frequency (e.g., 200 Hz) higher than the frequency range (20 Hz or more and 125 Hz or less) used during normal rotation of the motor 12, and sets the duty ratio of the PWM signal to 50%. Next, in step S41, the control unit 14 outputs the PWM signal whose frequency (e.g., 200 [Hz]) and duty ratio (50 [%]) have been set in step S40 to the monitoring device MD. The PWM signal output to the monitoring device MD is used to monitor the state of the motor 12. At this time, the control unit 14 outputs the PWM signal for rotating the motor 12 to the motor control unit 13.

[0068] <Third embodiment> Hereinafter, a third embodiment of the electric pump and the method for notifying of a fault state of the electric pump according to the present invention will be described. The electric pump 1 of the third embodiment is configured similarly to the electric pump 1 of the above-described first embodiment, except for the points described below. Therefore, the electric pump 1 of the third embodiment can achieve the same effects as the electric pump 1 of the above-described first embodiment, except for the points described below.

[0069] [Table 3]

[0070] Table 3 shows the PWM signals used to monitor the state of the motor 12 when the motor 12 stops abnormally in one example of the electric pump 1 according to the third embodiment. As shown in Table 3, in one example of the electric pump 1 of the third embodiment, when the motor 12 stops normally, the control unit 14 sets the frequency of the PWM signal used to monitor the status of the motor 12 to 4 [Hz] and sets the duty ratio of the PWM signal to 50 [%].

[0071] In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault A (``undervoltage'' of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 2 [Hz], which is different from the frequency (4 [Hz]) used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 20 [%], which is different from the duty ratio (50 [%]) used when the motor 12 is normal. In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault B (``overvoltage'' of the power supply), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 2 [Hz], which is different from the frequency (4 [Hz]) used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 80 [%], which is different from the duty ratios (50 [%]) and 20 [%] used when the motor 12 is normal. In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault C ("overcurrent" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 7 [Hz], which is different from the frequencies (4 [Hz]) and 2 [Hz] used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 20 [%], which is different from the duty ratios (50 [%]) and 80 [%] used when the motor 12 is normal.

[0072] In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault D ("overheating" of the motor 12), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 7 [Hz], which is different from the frequencies (4 [Hz]) and 2 [Hz] used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 80 [%], which is different from the duty ratios (50 [%]) and 20 [%] used when the motor 12 is normal. In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault E ("motor lock"), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 10 [Hz], which is different from the frequencies (4 [Hz]), 2 [Hz], and 7 [Hz] used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 20 [%], which is different from the duty ratios (50 [%]) and 80 [%] used when the motor 12 is normal. In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault F (``command abnormality (ground fault)'' to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 15 [Hz], which is different from the frequencies (4 [Hz]), 2 [Hz], 7 [Hz] and 10 [Hz] used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 20 [%], which is different from the duty ratios (50 [%]) and 80 [%] used when the motor 12 is normal.

[0073] In one example of the electric pump 1 of the third embodiment, when the motor 12 stops abnormally and the fault state of the motor 12 is fault G ("command abnormality (frequency abnormality at the time of stop command)" to the motor drive unit 13), the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 15 [Hz], which is different from the frequencies (4 [Hz]), 2 [Hz], 7 [Hz] and 10 [Hz] used when the motor 12 stops normally, and sets the duty ratio of the PWM signal to 80 [%], which is different from the duty ratios (50 [%]) and 20 [%] used when the motor 12 is normal. That is, in one example of the electric pump 1 of the third embodiment, the frequency of the PWM signal used to monitor the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault)) to the motor drive unit 13), and failure G (command abnormality (frequency abnormality at the time of stop command) to the motor drive unit 13) is set to a frequency (less than 4 [Hz], a frequency range of 4 [Hz], 20 [Hz] or more and 125 [Hz] or less) used when the motor 12 is normal, and the duty ratio of the PWM signal is set to a duty ratio (20 [%], 80 [%]) different from the duty ratio (50 [%]) used when the motor 12 is normal. In one example of the electric pump 1 of the third embodiment, when the motor 12 is rotating normally, the control unit 14 sets the frequency of the PWM signal used to monitor the state of the motor 12 to 20 Hz to 125 Hz within the frequency range used when the motor 12 is normal (4 Hz, 20 Hz or more and 125 Hz or less), and sets the duty ratio of the PWM signal to 50%.

[0074] In other words, in one example of the electric pump 1 of the third embodiment, when the motor 12 abnormally stops, the frequency and duty ratio of the PWM signal output from the control unit 14 are varied so that the monitoring device MD can monitor in detail the state of the motor 12 at the time of the abnormal stop. That is, in one example of the electric pump 1 of the third embodiment, the monitoring device MD can recognize the cause of the abnormal stop of the motor 12 (excessive power supply voltage, insufficient power supply voltage, motor overcurrent, motor overheating, motor lock, command abnormality (ground fault) or command abnormality (frequency abnormality at the time of the stop command)) without the need to vary the duty ratio of the PWM signal output from the control unit 14 when the motor 12 is normal, that is, without the need to increase the processing burden of monitoring the state of the motor 12. Furthermore, in one example of the electric pump 1 of the third embodiment, the output switching unit 14A of the control unit 14 does not output to the motor driving unit 13 a PWM signal used to monitor the motor 12 in the states of failure A (undervoltage of the power supply), failure B (overvoltage of the power supply), failure C (overcurrent of the motor 12), failure D (overheating of the motor 12), failure E (motor lock), failure F (command abnormality (ground fault) to the motor driving unit 13), and failure G (command abnormality (frequency abnormality when issuing a stop command) to the motor driving unit 13).

[0075] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the scope of the present invention. The configurations described in the above-mentioned embodiments and examples may be combined.

[0076] In addition, all or part of the functions of each unit of the electric pump 1 in the above-mentioned embodiment may be realized by recording a program for realizing these functions in a computer-readable recording medium, reading the program recorded in the recording medium into a computer system, and executing it. Note that the "computer system" here includes hardware such as an OS and peripheral devices. In addition, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage units such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include those that dynamically hold a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and those that hold a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in such cases. Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system. [Explanation of symbols]

[0077] 1...electric pump, 11...pump, 12...motor, 13...motor drive unit, 13A...switching element, 13B...rotation speed information processing unit, 14...control unit, 14A...output switching unit, 14B...rotation speed feedback unit, MD...monitoring device

Claims

1. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency outside a frequency range used when the motor is normal; When the fault state of the motor is a first fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a first frequency outside a frequency range used when the motor is normal; When the fault state of the motor is a second fault state different from the first fault state, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a second frequency that is outside a frequency range used when the motor is normal and is different from the first frequency; the control unit sets a duty ratio of the PWM signal used for monitoring the motor in the first fault state and a duty ratio of the PWM signal used for monitoring the motor in the second fault state to a value equal to a duty ratio used when the motor is normally stopped; the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, the output switching unit does not output the PWM signal used for monitoring the motor in the first fault state and the second fault state to the motor drive unit; Electric pump.

2. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency outside a frequency range used when the motor is normal; When the fault state of the motor is a first fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 1 Hz; When the failure state of the motor is a second failure state different from the first failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 2 Hz; When the failure state of the motor is a third failure state different from the first failure state and the second failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 6 Hz; When the failure state of the motor is a fourth failure state different from the first failure state, the second failure state, and the third failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 7 Hz; When the failure state of the motor is a fifth failure state different from the first failure state, the second failure state, the third failure state, and the fourth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 8 Hz; When the failure state of the motor is a sixth failure state different from the first failure state, the second failure state, the third failure state, the fourth failure state, and the fifth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 10 Hz; When the failure state of the motor is a seventh failure state different from the first failure state, the second failure state, the third failure state, the fourth failure state, the fifth failure state, and the sixth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 12 Hz; the control unit sets a duty ratio of the PWM signal used for monitoring the motor in the first fault state, the second fault state, the third fault state, the fourth fault state, the fifth fault state, the sixth fault state, and the seventh fault state to a value equal to a duty ratio used when the motor is normally stopped; the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, the output switching unit does not output to the motor drive unit the PWM signal used for monitoring the motor in the first fault state, the second fault state, the third fault state, the fourth fault state, the fifth fault state, the sixth fault state, or the seventh fault state. Electric pump.

3. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency outside a frequency range used when the motor is normal; When the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal constituted by a pulse train combining a first pulse of a first frequency outside a frequency range used when the motor is normal and a second pulse of a second frequency outside the frequency range used when the motor is normal and different from the first frequency, the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, the output switching unit does not output the PWM signal used for monitoring the state of the motor to the motor drive unit when the motor abnormally stops. Electric pump.

4. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the frequency of the PWM signal used to monitor the state of the motor to a frequency outside a frequency range used when the motor is normal; When the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal constituted by a pulse train combining a first pulse having a first frequency outside a frequency range used when the motor is normal, repeated a plurality of times, and a second pulse having a second frequency outside the frequency range used when the motor is normal and different from the first frequency, repeated a plurality of times; the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, the output switching unit does not output the PWM signal used for monitoring the state of the motor to the motor drive unit when the motor abnormally stops. Electric pump.

5. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal configured by a pulse train combining a first pulse with a first duty ratio different from a duty ratio used when the motor is normal, and a second pulse with a second duty ratio different from the duty ratio used when the motor is normal and the first duty ratio; the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, The output switching unit is When the motor stops abnormally, the PWM signal used for monitoring the state of the motor is not output to the motor drive unit. Electric pump.

6. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, The PWM signal output from the control unit is used to monitor a state of the motor, When the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal constituted by a pulse train combining a first pulse having a first duty ratio different from a duty ratio used when the motor is normal, repeated a plurality of times, and a second pulse having a second duty ratio different from the duty ratio used when the motor is normal and the first duty ratio, repeated a plurality of times; the control unit includes an output switching unit that switches whether or not the PWM signal is to be output to the motor drive unit, The output switching unit is When the motor stops abnormally, the PWM signal used for monitoring the state of the motor is not output to the motor drive unit. Electric pump.

7. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, When the motor is in a normal state, the control unit sets a frequency of the PWM signal used for monitoring a state of the motor to a frequency within a first frequency range; When the motor abnormally stops, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a frequency within a second frequency range different from the first frequency range; When the fault state of the motor is a first fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a first frequency outside a frequency range used when the motor is normal; When the fault state of the motor is a second fault state different from the first fault state, setting the frequency of the PWM signal used to monitor the state of the motor to a second frequency that is outside a frequency range used when the motor is normal and is different from the first frequency; a step of the control unit setting a duty ratio of the PWM signal used for monitoring the motor in the first fault state and a duty ratio of the PWM signal used for monitoring the motor in the second fault state to a value equal to a duty ratio used when the motor is normally stopped; an output switching unit that switches whether or not to output the PWM signal to the motor drive unit, the output switching unit being provided in the control unit, not outputting the PWM signal used for monitoring the motor in the first fault state and the second fault state to the motor drive unit; Equipped with A method for notifying an electric pump of a fault condition.

8. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, When the motor is in a normal state, the control unit sets a frequency of the PWM signal used for monitoring a state of the motor to a frequency within a first frequency range; When the motor abnormally stops, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a frequency within a second frequency range different from the first frequency range; When the fault state of the motor is a first fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 1 Hz; When the fault state of the motor is a second fault state different from the first fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 2 Hz; When the fault state of the motor is a third fault state different from the first fault state and the second fault state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 6 Hz; When the failure state of the motor is a fourth failure state different from the first failure state, the second failure state, and the third failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 7 Hz; When the failure state of the motor is a fifth failure state different from the first failure state, the second failure state, the third failure state, and the fourth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 8 Hz; When the failure state of the motor is a sixth failure state different from the first failure state, the second failure state, the third failure state, the fourth failure state, and the fifth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 10 Hz; When the failure state of the motor is a seventh failure state different from the first failure state, the second failure state, the third failure state, the fourth failure state, the fifth failure state, and the sixth failure state, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to 12 Hz; a step of the control unit setting a duty ratio of the PWM signal used for monitoring the motor in the first fault state, the second fault state, the third fault state, the fourth fault state, the fifth fault state, the sixth fault state, and the seventh fault state to a value equal to a duty ratio used when the motor is normally stopped; an output switching unit which switches whether or not to output the PWM signal provided in the control unit to the motor drive unit, not outputting to the motor drive unit the PWM signal used for monitoring the motor in the first fault state, the second fault state, the third fault state, the fourth fault state, the fifth fault state, the sixth fault state, and the seventh fault state; Equipped with A method for notifying an electric pump of a fault condition.

9. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, When the motor is in a normal state, the control unit sets a frequency of the PWM signal used for monitoring a state of the motor to a frequency within a first frequency range; When the motor abnormally stops, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a frequency within a second frequency range different from the first frequency range; a step in which, when the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal configured by a pulse train combining a first pulse of a first frequency outside a frequency range used when the motor is normal, and a second pulse of a second frequency outside the frequency range used when the motor is normal and different from the first frequency; an output switching unit that switches whether or not to output the PWM signal to the motor drive unit, the output switching unit being provided in the control unit, not outputting the PWM signal used for monitoring the state of the motor to the motor drive unit when the motor abnormally stops; Equipped with A method for notifying an electric pump of a fault condition.

10. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, When the motor is in a normal state, the control unit sets a frequency of the PWM signal used for monitoring a state of the motor to a frequency within a first frequency range; When the motor abnormally stops, the control unit sets a frequency of the PWM signal used for monitoring the state of the motor to a frequency within a second frequency range different from the first frequency range; a step in which, when the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal constituted by a pulse train combining a first pulse having a first frequency outside a frequency range used when the motor is normal, repeated multiple times, and a second pulse having a second frequency outside the frequency range used when the motor is normal and different from the first frequency, repeated multiple times; an output switching unit that switches whether or not to output the PWM signal to the motor drive unit, the output switching unit being provided in the control unit, not outputting the PWM signal used for monitoring the state of the motor to the motor drive unit when the motor abnormally stops; Equipped with A method for notifying an electric pump of a fault condition.

11. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, a step of setting a duty ratio of the PWM signal used for monitoring a state of the motor to a first duty ratio by the control unit when the motor is normal; When the motor stops abnormally, the control unit sets a duty ratio of the PWM signal used for monitoring a state of the motor to a second duty ratio different from the first duty ratio; a step in which, when the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal configured by a pulse train combining a first pulse with a first duty ratio different from a duty ratio used when the motor is normal, and a second pulse with a second duty ratio different from the duty ratio used when the motor is normal and the first duty ratio; Equipped with When the motor abnormally stops, the PWM signal used to monitor the state of the motor is not output to the motor drive unit. A method for notifying an electric pump of a fault condition.

12. A pump, A motor that drives the pump; a motor drive unit having a switching element and configured to drive the motor using power output from the switching element; a control unit that outputs a PWM (Pulse Width Modulation) signal that drives the switching element to the motor drive unit, A method for notifying a fault state of an electric pump, wherein the PWM signal output from the control unit is used to monitor a state of the motor, a step of setting a duty ratio of the PWM signal used for monitoring a state of the motor to a first duty ratio by the control unit when the motor is normal; When the motor stops abnormally, the control unit sets a duty ratio of the PWM signal used for monitoring a state of the motor to a second duty ratio different from the first duty ratio; a step in which, when the motor stops abnormally, the control unit sets the PWM signal used for monitoring the state of the motor to a signal constituted by a pulse train combining a first pulse having a first duty ratio different from a duty ratio used when the motor is normal, repeated a plurality of times, and a second pulse having a second duty ratio different from the duty ratio used when the motor is normal and the first duty ratio, repeated a plurality of times; Equipped with When the motor abnormally stops, the PWM signal used to monitor the state of the motor is not output to the motor drive unit. A method for notifying an electric pump of a fault condition.

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