Motor idling detection device, motor control device, motor idling detection method, and program

Abstract

To provide a motor idling detection device capable of detecting motor idling without employing high-precision current sensors.SOLUTION: A motor voltage calculation unit 16 calculates the motor voltage applied to a motor 50 on the basis of the power supply voltage and the duty ratio of the PWM control of an inverter 20. An idling determination unit 18 compares the calculated motor voltage with an idling determination threshold for determining idling of the motor 50, and on the basis of the comparison result, determines whether the motor 50 is idling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for detecting idling of a motor that drives a pump that sucks and discharges liquid. [Background technology]

[0002] For example, Patent Document 1 discloses a device that determines whether an oil pump driven by a motor has an abnormal rotation and stops the oil pump. This device detects the oil temperature and calculates a threshold value corresponding to the detected oil temperature by referring to a map of threshold values ​​that are set to a larger value as the oil temperature decreases. The device then compares the motor drive current with the calculated threshold value, and if the motor drive current is smaller than the threshold value, it determines that the oil pump has an abnormal rotation (air intake abnormality) and stops the oil pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-299665 Summary of the Invention [Problem to be solved by the invention]

[0004] When a pump that sucks and discharges liquid is driven by a motor, the pump rotates using the lubricant provided by the liquid. Therefore, if the pump is driven by the motor without the presence of liquid, it may have a negative impact on the pump's performance, such as its lifespan. For this reason, Patent Document 1 compares the motor's drive current with a threshold value and determines whether the oil pump is experiencing an air intake abnormality based on the comparison result.

[0005] When the motor drives the oil pump without oil, the load on the motor becomes very small and the motor runs idle. Because the motor's drive current is very small when the motor is running idle, it is susceptible to errors and variations. Therefore, the device described in Patent Document 1 requires a high-precision current sensor to accurately measure the motor's drive current, which creates a problem.

[0006] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a motor idling detection device, a motor idling detection method, and a program that are capable of detecting motor idling without using a high-precision current sensor. It is also an object of the present disclosure to provide a motor control device equipped with such a motor idling detection device. [Means for solving the problem]

[0007] In order to achieve the above object, a motor idling detection device according to the present disclosure is a motor idling detection device that detects idling of a motor (50) that drives a pump that sucks and discharges liquid, an acquisition unit (16) that acquires a motor voltage applied to the motor; The motor control device is provided with an idling determination unit (18) that compares the motor voltage acquired by the acquisition unit with an idling determination threshold value for determining whether the motor is idling, and determines whether the motor is idling or not based on the comparison result.

[0008] A motor idling detection method according to the present disclosure is a motor idling detection method executed by at least one processor (13) to detect idling of a motor (50) that drives a pump that draws and discharges liquid, the method comprising: Obtaining a motor voltage applied to a motor; The acquired motor voltage is compared with a spin determination threshold for determining whether the motor is spinning, and whether the motor is spinning is determined based on the comparison result.

[0009] The program according to the present disclosure is a program for causing at least one processor (13) to detect idling of a motor (50) that drives a pump that sucks and discharges liquid, At least one processor has Obtaining a motor voltage applied to a motor; The acquired motor voltage is compared with a spin determination threshold value for determining whether the motor is spinning, and whether the motor is spinning is determined based on the comparison result.

[0010] In the above-described motor idling detection device, motor idling detection method, and program, the motor voltage applied to the motor is acquired. The acquired motor voltage is compared with an idling determination threshold for determining whether the motor is idling. Whether the motor is idling is determined based on the comparison result. Therefore, the motor idling detection device, motor idling detection method, and program disclosed herein can detect motor idling without using a highly accurate current sensor.

[0011] Here, when the motor is driven to rotate by PWM-controlling the switching elements (21-26) constituting the inverter (20), the motor voltage is preferably calculated and obtained from the duty ratio of the PWM control and the power supply voltage applied to the inverter, which makes it possible to obtain the motor voltage simply and accurately.

[0012] Furthermore, the motor control device according to the present disclosure includes: The motor idling detection device described above; and an execution unit (12) that, in response to the detection of idling of the motor by the motor idling detection device, performs at least one of the following: storing the detection of idling of the motor; notifying a higher-level control device (40) that instructs a control target value of the motor; and stopping the rotation of the motor.

[0013] As a result, the motor control device according to the present disclosure can achieve the effect of taking appropriate measures when the motor spins, in addition to the effects achieved by the motor spin detection device described above.

[0014] The reference numbers in parentheses above merely indicate an example of a correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0015] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing the overall configuration of a motor control device including a motor slippage detection device according to a first embodiment. [Figure 2] 5 is a flowchart showing a process for determining whether a motor is spinning and a procedure to be taken when the motor is spinning, in the first embodiment. [Figure 3] FIG. 4 is a diagram for explaining a spin determination threshold in the first embodiment. [Figure 4] 3 is a flowchart showing the details of the motor idling determination process in step S140 of the flowchart in FIG. 2. [Figure 5] FIG. 10 is a diagram for explaining a spin determination threshold value in the second embodiment. [Figure 6] 10 is a flowchart showing a process for determining whether a motor is spinning and a procedure to be taken when the motor is spinning, in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present disclosure will be described below with reference to the drawings. Note that identical or similar configurations may be omitted from description by assigning the same reference numerals across multiple drawings. When only a portion of a configuration is described in each embodiment, the configuration of another previously described embodiment may be applied to the remaining portions of the configuration. Furthermore, configurations of multiple embodiments may be partially combined, even if not explicitly described, as long as there is no particular problem with the combination.

[0018] (First embodiment) FIG. 1 is a block diagram showing the overall configuration of a motor control device 1 equipped with a motor idling detection device according to this embodiment. The motor control device 1 according to this embodiment can be mounted on, for example, a vehicle and used to drive a motor 50 of a fuel pump that draws up fuel stored in a fuel tank and supplies it to a fuel injection system. However, the use of the motor 50 driven and controlled by the motor control device 1 according to this embodiment is not limited to this. For example, the motor 50 may drive an oil pump that circulates engine oil in the vehicle. The motor 50 may also drive a washer pump that draws in and discharges windshield washer fluid. Furthermore, the motor 50 may be used to drive a pump that draws in and discharges liquid outside of a vehicle.

[0019] The motor 50 controlled by the motor control device 1 according to this embodiment may be, for example, a three-phase brushless motor having a permanent magnet in the rotor and three-phase stator coils in the stator. However, the motor 50 controlled by the motor control device 1 according to this embodiment is not limited to a three-phase brushless motor, and may also be a brushed motor or an induction motor. Furthermore, the motor may be a two-phase or three-or-more-phase multi-phase motor.

[0020] As shown in FIG. 1, the motor control device 1 of this embodiment includes a controller 10 and an inverter 20. The controller 10 includes a power supply voltage measurement unit 11, a control unit 12, a duty calculation unit 15, a motor voltage calculation unit 16, a rotation speed detection unit 17, and a spin determination unit 18. Each component of the controller 10 may be configured by software, hardware, or a combination of software and hardware. For example, the motor voltage calculation unit 16 and the spin determination unit 18 may be implemented by a program executed by the processor 13 included in the control unit 12. Alternatively, the motor voltage calculation unit 16 and the spin determination unit 18 may be implemented by a program executed by at least one processor different from the processor 13 included in the control unit 12. Furthermore, at least some of the functions of the motor voltage calculation unit 16 and the spin determination unit 18 may be implemented by a hardware circuit.

[0021] The power supply voltage measuring unit 11 measures the power supply voltage supplied from the power supply 30 to the inverter 20. For example, the power supply voltage measuring unit 11 includes a resistor and an A / D converter. The A / D converter converts the power supply voltage applied to the resistor into a digital value and outputs the digital value to the control unit 12 and the motor voltage calculation unit 16.

[0022] The control unit 12 has a processor 13 and a memory 14. The processor 13 of the control unit 12 executes various processes in accordance with a control program stored in the memory 14, thereby performing motor control. For example, the control unit 12 receives the power supply voltage measured by the power supply voltage measurement unit 11. The control unit 12 then determines whether the received power supply voltage is within a predetermined normal voltage range. If the control unit 12 determines that the power supply voltage is within the predetermined normal voltage range, the control unit 12 executes motor control. In other words, if the power supply voltage is at an abnormal value, the control unit 12 can stop motor control.

[0023] The control unit 12 receives a target rotation speed of the motor 50 as a control target value from a rotation speed instruction unit 41 provided in the higher-level control device 40. Then, based on the received target rotation speed and the actual rotation speed of the motor 50 detected by a rotation speed detection unit 17 described later, the control unit 12 calculates command values ​​(U-phase command value, V-phase command value, W-phase command value) corresponding to each phase of the motor 50 so that the actual rotation speed approaches the target rotation speed. The calculation of these command values ​​is repeatedly performed, for example, every time the motor 50 advances by a predetermined angle. The calculated command values ​​are output to the duty calculation unit 15.

[0024] The duty calculation unit 15 compares the command value output from the control unit 12 with the triangular wave signal, and generates a PWM signal for generating a pseudo AC current to be applied to the stator coil of each phase based on the comparison result between the command value and the triangular wave signal. At the same time, the duty calculation unit 15 calculates the duty ratio of the generated PWM signal. In other words, the duty calculation unit 15 calculates the duty ratio of PWM control. The duty calculation unit 15 outputs the calculated duty ratio to the motor voltage calculation unit 16.

[0025] Here, the command value is calculated to have, for example, a sine wave shape, and the frequency of the sine wave is determined to increase (the period becomes shorter) as the target rotation number (target rotation speed) of the motor 50 increases. However, the command value may also be calculated to have a rectangular wave shape. That is, either a sine wave drive or a rectangular wave drive may be used. On the other hand, the triangular wave signal is generated, for example, using an up-down counter that alternately counts up and down. This up-down counter may be either hardware or software. The frequency and period of this triangular wave signal may also change in the same manner as the frequency and period of the command value, for example, by changing the clock frequency that counts up and down, or by changing the values ​​that count up and down. This allows the period of the generated PWM signal to be appropriately adjusted.

[0026] The PWM signals generated for each phase are output to the inverter 20. The inverter 20 has three pairs of bridge-connected switching elements (21 and 22, 23 and 24, and 25 and 26) corresponding to the U, V, and W phases of the motor 50. PWM signals are supplied to the gates of the switching elements 21 to 26, and each of the switching elements 21 to 26 is turned on and off in accordance with the corresponding PWM signal. As a result, a pseudo AC current corresponding to a command value is passed through the stator coils of each phase of the motor 50. At this time, a predetermined combination of high-potential side switching elements and low-potential side switching elements of the three pairs of switching elements 21 to 26 is simultaneously turned on, and the pseudo AC current is passed through the stator coils of each phase so as to switch the combination of the high-potential side switching elements and low-potential side switching elements to be turned on. As a result, a rotating magnetic field is generated in the three-phase stator coils, and the rotor rotates in accordance with the rotating magnetic field, thereby rotating the motor 50.

[0027] Motor voltage calculation unit 16 calculates the motor voltage to be applied to motor 50 from the duty ratio calculated by duty calculation unit 15 when PWM controlling each of switching elements 21-26 and the power supply voltage measured by power supply voltage measurement unit 11. The power supply voltage becomes the input voltage of inverter 20. The input voltage of inverter 20 is applied to motor 50 when switching elements 21-26 are turned on. Therefore, the motor voltage actually applied to motor 50 can be calculated by multiplying the input voltage of inverter 20 by the duty ratio, which is the ratio at which switching elements 21-26 are turned on. Motor voltage calculation unit 16 outputs the calculated motor voltage to spin determination unit 18. Motor voltage calculation unit 16 corresponds to the acquisition unit of the present disclosure.

[0028] The rotation speed detection unit 17 detects the rotation speed and rotation angle of the rotor (i.e., the motor 50) based on the induced voltage generated in the non-energized phase of each stator coil due to the rotation of the rotor in the motor 50. In other words, based on the induced voltage in the non-energized phase, the rotation position of the motor 50 (rotor) can be detected every time the motor 50 rotates 60 degrees. Then, the rotation speed of the motor 50 per unit time (i.e., the rotational speed) can be calculated from the time required for the motor 50 to rotate 60 degrees. The rotation speed detection unit 17 outputs the detected rotation speed and rotation angle of the motor 50 to the control unit 12 and the idling determination unit 18.

[0029] The rotation speed and rotation angle of the motor 50 may be detected using a position detection device that detects and outputs position information related to the rotation angle of the motor 50. A resolver sensor, for example, can be used as the position detection device. As is well known, a resolver sensor has coils provided on the rotor and stator of the motor 50. When the rotor rotates with an AC voltage applied to the rotor coil, the distance to the stator coil changes, and an AC voltage with varying amplitude is generated in the stator coil. The rotation speed and rotation angle of the motor 50 can be detected from this voltage change.

[0030] Alternatively, the position detector may use three Hall elements that detect the current phases of U-, V-, and W-phase currents, which are pseudo-alternating currents (pseudo-sine wave currents) applied to each of the three stator coils. These Hall elements detect current changes in a specific stator coil as changes in magnetic flux. In a three-phase brushless motor, the U-, V-, and W-phase currents, which are the three pseudo-alternating currents, are shifted in phase by 120 degrees. Therefore, by combining the detection signals from the three Hall elements, the rotational position of the motor 50 (rotor) can be detected every 60 degrees of rotation. It is also possible to detect the rotational position of the rotor by detecting changes in the rotor's magnetic flux using at least one Hall element.

[0031] The idling determination unit 18 compares the motor voltage calculated by the motor voltage calculation unit 16 with a predetermined idling determination threshold for determining idling of the motor 50. Then, the idling determination unit 18 determines whether the motor 50 is idling or not based on the comparison result between the motor voltage and the idling determination threshold. The idling determination unit 18 outputs the determination result as to whether the motor 50 is idling or not to the control unit 12. When the idling determination unit 18 determines that the motor 50 is idling, the control unit 12 performs a process at the time of idling determination. In other words, the control unit 12 corresponds to the execution unit of the present disclosure. Furthermore, the idling detection device of the present disclosure is mainly composed of the motor voltage calculation unit 16 and the idling determination unit 18. Furthermore, the idling detection device of the present disclosure also utilizes the functions of the power supply voltage measurement unit 11, the duty calculation unit 15, and the rotation speed detection unit 17, and these can also be said to be components of the idling detection device.

[0032] Next, the process for determining whether the motor 50 is spinning and the actions to be taken when the motor 50 is spinning will be described in detail with reference to the flowchart in Fig. 2. The process shown in the flowchart in Fig. 2 can be executed by at least one processor, including the processor 13, in the spin detection device by executing a program stored in a storage medium, including the memory 14. The execution of the process shown in the flowchart in Fig. 2 by the spin detection device corresponds to carrying out the spin detection method. The process shown in the flowchart in Fig. 2 is periodically and repeatedly executed by the spin detection device.

[0033] In the first step S100, the slip detection device measures the power supply voltage supplied from the power supply 30 to the inverter 20. In the following step S110, the slip detection device calculates the duty ratio when PWM controlling each of the switching elements 21 to 26 that make up the inverter 20. Then, in step S120, the slip detection device calculates the motor voltage to be applied to the motor 50 by multiplying the power supply voltage measured in step S100 by the duty ratio calculated in step S110.

[0034] In step S130, the slip detection device determines whether the calculated motor voltage is smaller than a predetermined slip determination threshold. If it is determined that the calculated motor voltage is smaller than the predetermined slip determination threshold, the slip detection device proceeds to processing in step S140. On the other hand, if it is determined that the calculated motor voltage is equal to or greater than the predetermined slip determination threshold, it is determined that slip is not occurring in the motor 50, and the slip detection device ends the processing shown in the flowchart of FIG. 2.

[0035] Here, if the motor 50 of this embodiment drives, for example, a fuel pump that draws and discharges fuel stored in a vehicle fuel tank, if there is sufficient fuel remaining in the fuel tank, the rotation speed of the motor 50 increases. As the amount of fuel discharged increases, the load on the motor 50 increases. Therefore, as shown in FIG. 3 , the motor voltage increases as the rotation speed of the motor 50 increases. Note that even at the same rotation speed of the motor 50, the load on the motor 50 fluctuates between maximum and minimum loads due to factors such as the influence of the fuel pressure in the piping to which the fuel is discharged, differences in fuel properties depending on the country or region, and changes in fuel viscosity depending on the fuel temperature. Therefore, when the motor voltage is within the range between the motor voltage at maximum load and the motor voltage at minimum load, which changes depending on the rotation speed of the motor 50 (i.e., the normal motor voltage range), the fuel pump driven by the motor 50 can be considered to be drawing in and discharging fuel normally.

[0036] On the other hand, if the motor voltage drops below the minimum load, it can be assumed that the load on the motor 50 has decreased due to the inclusion of air in the fuel drawn in and discharged by the fuel pump. The higher the proportion of air in the fuel, the greater the drop in motor voltage compared to the minimum load. When the fuel pump draws in and discharges almost only air, the motor voltage approaches the idling motor voltage shown by the dotted line in Figure 3.

[0037] In this embodiment, a constant spin determination threshold is used as the predetermined spin determination threshold, which is smaller than (the minimum value of) the motor voltage at minimum load and larger than (the maximum value of) the spin motor voltage. By setting the spin determination threshold to a constant value that is smaller than the motor voltage at minimum load and larger than the spin motor voltage, it is possible to determine that there is a high possibility that the motor 50 is spinning (or rotating in a state close to spinning), regardless of the rotation speed of the motor 50. Note that in this embodiment, a state close to spinning is also considered to be spinning of the motor 50.

[0038] The determination process of step S130 described above determines whether the motor 50 is idling, and if it is determined that the motor 50 is idling, it is possible to implement measures at the time of the idling determination. However, in this embodiment, in order to improve the accuracy of the idling determination, the idling detection device determines in more detail whether the motor 50 is idling in step S140. Hereinafter, the idling determination process of the motor 50 in step S140 will be described in detail with reference to the flowchart of FIG.

[0039] In the first step S200, the slip detection device detects the rotation speed of the motor 50. In the following step S210, the slip detection device compares the detected rotation speed of the motor 50 with a threshold value for determining whether the motor 50 is rotating in a low rotation speed range. If it is determined that the rotation speed of the motor 50 is lower than the threshold value, the slip detection device proceeds to the processing of step S220. On the other hand, if it is determined that the rotation speed of the motor 50 is equal to or higher than the threshold value, the slip detection device proceeds to the processing of step S230.

[0040] In step S220, the spin detection device instructs the control unit 12 to increase the rotation speed of the motor 50 so that the rotation speed of the motor 50 increases to a rotation speed equal to or greater than the threshold value. When the motor 50 is rotating in the low rotation range, as shown in the graph of FIG. 3, the interval between the normal motor voltage range and the spin determination threshold narrows. Therefore, even when the motor 50 is not spinning, it may be erroneously determined that the motor voltage is lower than the spin determination threshold. On the other hand, when the motor 50 is rotating at a rotation speed higher than the low rotation range, as shown in the graph of FIG. 3, the interval between the normal motor voltage range and the spin determination threshold widens. Therefore, when the motor 50 is rotating at a rotation speed higher than the low rotation range, the possibility of the motor voltage being erroneously determined to be lower than the spin determination threshold is reduced compared to when the motor is rotating in the low rotation range. For these reasons, in this embodiment, the rotation speed of the motor 50 is increased when the motor 50 is rotating in the low rotation range, which is lower than the threshold value.

[0041] In step S230, the spin detection device determines whether the motor voltage has remained below the spin determination threshold for a certain period of time. For example, assume that a pump driven by the motor 50 is mounted on a vehicle. The vehicle travels not only on flat roads but also on slopes and uneven roads. In such driving conditions, the liquid to be sucked by the pump may become uneven in the tank, preventing the pump from sufficiently sucking the liquid. However, it is assumed that the unevenness in the tank is temporary, and the pump will soon be able to suck the liquid. Therefore, in this embodiment, the spin detection device determines whether the motor voltage has remained below the spin determination threshold for a certain period of time. This makes it possible to accurately determine that the spin of the motor 50 is not due to a temporary imbalance in the tank, but rather to a small amount of liquid to be sucked, and that the spin of the motor 50 will continue. If it is determined in step S230 that the motor voltage has remained below the spin determination threshold for a certain period of time, the spin detection device proceeds to step S240. On the other hand, if it is determined that the state in which the motor voltage is less than the slip determination threshold does not continue for a certain period of time, the slip detection device proceeds to the processing of step S250.

[0042] In step S240, the slip detection device determines that the motor 50 is slipping. On the other hand, in step S250, the slip detection device determines that the motor 50 is not slipping. Thereafter, the slip detection device ends the processing shown in the flowchart of FIG. 4 and returns to the processing shown in the flowchart of FIG. 2.

[0043] 4 can improve the accuracy of determining whether motor 50 is idling. As a result, if motor 50 drives a fuel pump that draws up and discharges fuel stored in a vehicle fuel tank, for example, it is possible to prevent a malfunction such as an insufficient supply of fuel to the engine caused by stopping motor 50 due to an erroneous determination that motor 50 is idling.

[0044] In the flowchart of FIG. 4, in order to improve the accuracy of determining whether the motor 50 is idling, when the rotation speed of the motor 50 is in the low rotation speed range, a process for increasing the rotation speed of the motor 50 and a process for determining whether the motor voltage has remained below the idling determination threshold for a certain period of time are executed. However, the accuracy of determining whether the motor 50 is idling can be improved by executing only one of these processes. In this case, if the rotation speed of the motor 50 is in the low rotation speed range and only the process for increasing the rotation speed of the motor 50 is executed, the motor voltage and the idling determination threshold can be compared again after the rotation speed of the motor 50 is increased. Then, if the motor voltage is lower than the idling determination threshold, it can be determined that the motor 50 is idling.

[0045] In step S150 of the flowchart in Fig. 2, the idling detection device determines whether or not it has been determined in the idling determination process of the motor 50 in step S140 that the motor 50 is idling. If it is determined in step S140 that the motor 50 is idling, the idling detection device proceeds to the process of step S160. On the other hand, if it is determined in step S140 that the motor 50 is not idling, the idling detection device ends the process shown in the flowchart in Fig. 2.

[0046] In step S160, the idling detection device notifies the control unit 12 that idling of the motor 50 has been detected. In response to this notification, the control unit 12 performs a process for determining idling. For example, as a process for determining idling, the control unit 12 performs at least one of the following: storing the detection of idling of the motor 50 in the memory 14; notifying the upper control device 40, which instructs the control target value of the motor 50; and stopping the rotation of the motor 50. By storing the detection of idling of the motor 50, it is possible to estimate the impact on performance, such as the lifespan of the pump, from the stored result. Furthermore, by notifying the upper control device 40, it is possible for the upper control device 40 to take action, such as lowering the control target value. Furthermore, by stopping the rotation of the motor 50, it is possible to prevent malfunctions caused by idling of the motor 50.

[0047] The above-described measures to be taken when determining that the motor 50 is spinning may be selected according to the likelihood that the motor 50 is spinning. For example, if it is determined in step S130 that the motor voltage is lower than the spin determination threshold, this fact may be stored in memory 14; if the number of such determinations reaches a predetermined number, a notification may be sent to the higher-level control device 40; and if it is determined in step S140 that the motor 50 is spinning, the rotation of the motor 50 may be stopped.

[0048] As described above, with the spin detection device according to this embodiment, the motor voltage applied to the motor 50 is acquired by calculating it based on the power supply voltage and the duty ratio of PWM control. The acquired motor voltage is compared with a spin determination threshold for determining whether the motor 50 is spinning. Whether the motor 50 is spinning is determined based on the comparison result. Therefore, with the spin detection device according to this embodiment, it is possible to detect spinning of the motor 50 without using a high-precision current sensor. Furthermore, with the motor control device 1 according to this embodiment, it is possible to take appropriate measures when the motor 50 is spinning.

[0049] (Second embodiment) Next, a motor control device 1 equipped with a motor slip detection device according to a second embodiment of the present disclosure will be described. The motor control device 1 according to this embodiment has the same configuration as the motor control device 1 according to the first embodiment. Therefore, a description of the configuration will be omitted.

[0050] In the first embodiment described above, the spin determination threshold is set to a constant value that is smaller than the motor voltage under minimum load and larger than the spin motor voltage. In contrast, in the present embodiment, the spin determination threshold is set to vary with the rotation speed of the motor 50, being larger when the motor 50 rotation speed is high compared to when it is low. For example, as shown in the graph of FIG. 5 , the spin determination threshold is set to increase in proportion to the increase in the rotation speed of the motor 50 within a range that is smaller than the motor voltage under minimum load and larger than the spin motor voltage. This makes it possible to determine that the motor 50 is approaching a spinning state, regardless of the rotation speed of the motor 50, based on the comparison result between the motor voltage and the spin determination threshold. Note that the graph of FIG. 5 illustrates an example in which the spin determination threshold increases linearly with the increase in the rotation speed of the motor 50. However, the spin determination threshold may also increase stepwise with the increase in the rotation speed of the motor 50, for example.

[0051] 6 is a flowchart showing the process for determining whether the motor 50 is spinning and the steps to be taken when the motor 50 is spinning, in this embodiment. The same step numbers are assigned to steps that perform the same processes as in the flowchart of FIG. 2, and the explanation thereof will be omitted.

[0052] In the flowchart of FIG. 6, the processes of steps S122 and S124 are added to the flowchart of FIG. 2. In step S122, the slip detection device detects the rotation speed of the motor 50. In the following step S124, the slip detection device sets a slip determination threshold corresponding to the detected rotation speed of the motor 50, for example, by referring to a map that stores the relationship between the rotation speed of the motor 50 and the slip determination threshold. In this way, the slip determination value can be set to change according to the rotation speed of the motor 50, so that when the rotation speed of the motor 50 is high, the slip determination value is larger than when the rotation speed is low. Then, in step S130, the slip detection device compares the motor voltage calculated in step S120 with the slip determination threshold set in step S124.

[0053] The above describes preferred embodiments of the present disclosure, but the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms within the scope of the gist of the present disclosure.

[0054] For example, in each of the above-described embodiments, the motor voltage applied to the motor 50 is obtained by calculating it based on the power supply voltage and the duty ratio of PWM control. However, the motor voltage can also be obtained by measuring the voltage of each stator coil of the motor 50 and calculating it from the measured voltage.

[0055] Finally, this specification discloses the following technical ideas and combinations thereof. The combinations of the following technical ideas apply not only to a motor idling detection device but also to a motor idling detection method and program.

[0056] (Technical thought 1) A motor idling detection device for detecting idling of a motor (50) that drives a pump that sucks and discharges liquid, an acquisition unit (16) that acquires a motor voltage applied to the motor; and an idling determination unit (18) that compares the motor voltage acquired by the acquisition unit with an idling determination threshold value for determining whether the motor is idling, and determines whether the motor is idling based on the comparison result.

[0057] (Technical thought 2) The motor is rotationally driven by PWM control of switching elements (21-26) constituting an inverter (20), The motor idling detection device according to Technical Idea 1, wherein the acquisition unit calculates the motor voltage from a duty ratio of the PWM control and a power supply voltage applied to the inverter.

[0058] (Technical Thought 3) The motor idling detection device according to Technical Idea 1 or 2, wherein the idling judgment threshold changes according to the rotation speed of the motor so that it is larger when the rotation speed of the motor is high than when the rotation speed is low.

[0059] (Technical Thought 4) The motor idling detection device according to any one of Technical Ideas 1 to 3, wherein the idling determination unit increases the rotation speed of the motor based on the motor voltage dropping below the idling determination threshold, and determines that the motor is idling if the motor voltage after the rotation speed has increased is lower than the idling determination threshold.

[0060] (Technical Thought 5) The motor idling detection device according to Technical Idea 4, wherein the idling determination unit increases the rotation speed of the motor to determine whether the motor is idling when the rotation speed of the motor is less than a predetermined rotation speed threshold.

[0061] (Technical Thought 6) The motor idling detection device according to any one of technical ideas 1 to 5, wherein the idling determination unit determines that the motor is idling when the motor voltage remains lower than the idling determination threshold for a certain period of time.

[0062] (Technical Thought 7) The motor idling detection device according to any one of Technical Ideas 1 to 6, wherein the pump is a fuel pump that draws fuel from a fuel tank of a vehicle and delivers the drawn fuel to an engine of the vehicle.

[0063] (Technical Thought 8) A motor idling detection device according to any one of Technical Ideas 1 to 7, and an execution unit (12) that, in response to the detection of idling of the motor by the motor idling detection device, performs at least one of the following: storing the detection of idling of the motor; notifying a higher-level control device (40) that instructs a control target value of the motor; and stopping the rotation of the motor. [Explanation of symbols]

[0064] 1: Motor control device, 10: Controller, 11: Power supply voltage measurement unit, 12: Control unit, 13: Processor, 14: Memory, 15: Duty calculation unit, 16: Motor voltage calculation unit, 17: Rotation speed detection unit, 18: Idling determination unit, 20: Inverter, 21 to 26: Switching elements, 30: Power supply, 40: Upper control device, 41: Rotation speed instruction unit, 50: Motor

Claims

1. A motor idling detection device for detecting idling of a motor (50) that drives a pump that sucks and discharges liquid, an acquisition unit (16) that acquires a motor voltage applied to the motor; and an idling determination unit (18) that compares the motor voltage acquired by the acquisition unit with an idling determination threshold value for determining whether the motor is idling, and determines whether the motor is idling based on the comparison result.

2. The motor is rotationally driven by PWM control of switching elements (21 to 26) constituting an inverter (20), The motor idling detection device according to claim 1 , wherein the acquisition unit calculates the motor voltage from a duty ratio of the PWM control and a power supply voltage applied to the inverter.

3. 3. The motor idling detection device according to claim 1, wherein the idling determination threshold value changes in accordance with the rotation speed of the motor so as to be larger when the rotation speed of the motor is high than when the rotation speed of the motor is low.

4. 3. The motor idling detection device according to claim 1, wherein the idling determination unit increases the rotation speed of the motor based on the motor voltage being lower than the idling determination threshold, and determines that the motor is idling if the motor voltage after the rotation speed has increased is lower than the idling determination threshold.

5. The motor idling detection device according to claim 4 , wherein the idling determination unit increases the rotation speed of the motor in order to determine whether the motor is idling when the rotation speed of the motor is less than a predetermined rotation speed threshold value.

6. 3. The motor idling detection device according to claim 1, wherein the idling determination unit determines that the motor is idling when the motor voltage remains lower than the idling determination threshold for a certain period of time.

7. 3. The motor idling detection device according to claim 1, wherein the pump is a fuel pump that draws fuel from a fuel tank of a vehicle and delivers the drawn fuel to an engine of the vehicle.

8. The motor idling detection device according to claim 1 or 2; and an execution unit (12) that, in response to the detection of idling of the motor by the motor idling detection device, performs at least one of the following: storing the detection of idling of the motor; notifying a higher-level control device (40) that instructs a control target value of the motor; and stopping the rotation of the motor.

9. A motor idle detection method executed by at least one processor (13) for detecting idle rotation of a motor (50) that drives a pump that draws and discharges liquid, comprising: obtaining a motor voltage applied to the motor; comparing the acquired motor voltage with a spin determination threshold for determining whether the motor is spinning, and determining whether the motor is spinning based on the comparison result.

10. A program for causing at least one processor (13) to detect idling of a motor (50) that drives a pump that sucks and discharges liquid, the at least one processor; obtaining a motor voltage applied to the motor; a program for executing the program: comparing the acquired motor voltage with a spin determination threshold for determining whether the motor is spinning; and determining whether the motor is spinning based on the comparison result.

Images