Motor drive devices and in-vehicle systems

Abstract

To provide a motor driving device that can predict the degree of deterioration of an electrolytic capacitor without increasing the number of components.SOLUTION: A motor driving device acquires the number of rotations of a motor and the peripheral temperature of an electrolytic capacitor as actual operating information indicating the actual operating states of the motor, and measures the duration for every actual operating state (S71-S73). The motor driving device acquires the lifetime associated with the operating state corresponding to the actual operating information from the lifetime data. The motor driving device calculates the consumption rate of the life that is the ratio of the duration to the lifetime (S75).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a motor drive device and an in-vehicle system. [Background technology]

[0002] There is a technique for determining the deterioration state of an electrolytic capacitor based on the difference between the surface temperature of the electrolytic capacitor and the ambient temperature (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-131362 Summary of the Invention [Problem to be solved by the invention]

[0004] Some motor drive devices rotate a fan by driving a motor to cool an object. Some motor drive devices are configured with an electrolytic capacitor between the power supply and the drive circuit. In such motor drive devices, the motor drive time can be extended due to increased cooling demands. However, driving the motor for a long period of time can cause the electrolytic capacitor to dry up. When the electrolytic capacitor reaches the end of its life due to dry-up or other reasons, the motor drive device may become unable to drive the motor.

[0005] Therefore, motor drive devices are required to predict the degree of degradation of electrolytic capacitors so that they can be replaced before the end of their life and prevent the motor from becoming unable to be driven. One possible way to predict the degree of degradation of electrolytic capacitors is to use the technology described in Patent Document 1. However, the technology described in Patent Document 1 requires at least a temperature sensor to detect the surface temperature of the electrolytic capacitor and a temperature sensor to detect the ambient temperature, which increases the number of parts.

[0006] One disclosed object is to provide a motor drive device that can predict the degree of degradation of an electrolytic capacitor without increasing the number of parts, and another disclosed object is to provide an in-vehicle system that can predict the degree of degradation of an electrolytic capacitor without increasing the number of parts. [Means for solving the problem]

[0007] The motor drive device disclosed herein is A motor drive device that includes an electrolytic capacitor connected in parallel to a power supply and drives a motor to rotate a cooling fan, a rotation speed acquisition unit (11) that acquires the rotation speed of the motor; a temperature detection unit (14) for detecting the ambient temperature of the electrolytic capacitor; a deterioration prediction unit (13) for predicting a degree of deterioration of the electrolytic capacitor; times Indicated by rotation speed and ambient temperature Motor a storage device (16) in which lifetime data is stored in which the lifetime of the electrolytic capacitor in each operating state is associated with the operating state; The deterioration prediction unit a measurement step (S71 to S74) of acquiring the rotation speed from the rotation speed acquisition unit and the ambient temperature from the temperature detection unit as actual operation information indicating the actual operation state of the motor, and measuring the duration of each actual operation state; and a prediction step (S75) of obtaining the lifetime associated with the operating state corresponding to the actual operation information from the lifetime data, and calculating the consumption rate, which is the ratio of the duration to the lifetime, to predict the degree of deterioration of the electrolytic capacitor.

[0008] In this way, the motor drive device predicts the degree of deterioration of the electrolytic capacitor by calculating the consumption rate from the lifetime obtained from the lifetime data and the measured duration. Therefore, the motor drive device does not need to use multiple temperature sensors, etc., and can predict the degree of deterioration of the electrolytic capacitor without increasing the number of parts.

[0009] The in-vehicle system disclosed herein is a motor drive device and an electronic control device that outputs a motor rotation instruction to the motor drive device, the electronic control device being configured to be mountable on a vehicle; The motor drive device includes a notification step (S90) of notifying the electronic control device of the consumption rate.

[0010] Since the in-vehicle system includes the motor drive device, the degree of deterioration of the electrolytic capacitor can be predicted without increasing the number of parts.

[0011] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a motor drive device. [Figure 2] 4 is a flowchart showing a processing operation of the motor driving device. [Figure 3] 10 is a flowchart showing a life calculation process for the motor drive device. [Figure 4] 10 is a flowchart showing a notification process of the motor drive device. [Figure 5] This is an image shown by the lifetime data. [Figure 6] This is an image showing the lifespan consumption rate. [Figure 7] 10 is an image showing the change over time in rotation speed and life consumption rate. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] 1 to 6, a motor drive device 100 will be described. The motor drive device 100 drives and controls a motor 300. For example, a brushless motor for driving and rotating a cooling fan can be used as the motor 300. The cooling fan can cool an engine or electronic control device of a vehicle, for example. However, the present disclosure is not limited to this, and can also be used as a motor drive device 100 for controlling a motor 300 used in another device (unit).

[0015] <Overall structure> The overall configuration of the motor drive device 100, including its peripheral devices, will be described using FIG. 1. As shown in FIG. 1, the motor drive device 100 is electrically connected to a power supply 200, a motor 300, and a host ECU 400. The motor drive device 100 and the host ECU 400 can be considered to be part of an in-vehicle system. The in-vehicle system may also include the power supply 200 and the motor 300. In this embodiment, as an example, an in-vehicle system that can be mounted on a vehicle equipped with an engine as a power source is employed. In the drawings, the motor 300 is referred to as M, and the host ECU 400 as ECU. ECU is an abbreviation for Electronic Control Unit.

[0016] The power supply 200 is a DC power supply. The power supply 200 is electrically connected to the three-phase inverter 20. The power supply 200 supplies electric power for driving the motor 300.

[0017] The motor 300 is, for example, a three-phase motor including a stator, a rotor, and a shaft attached to the rotor. The stator has three phases: U, V, and W. Each of the U, V, and W phases of the stator generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by an electromagnet under the control of the microcomputer 10. The rotor is provided with a rotor magnet. The rotor magnet rotates the rotor by the rotating magnetic field generated by the stator. A shaft and a cooling fan are fixed to the rotor. The shaft and the cooling fan rotate with the rotation of the rotor. The fan rotates together with the shaft, enabling airflow. Note that, hereinafter, the rotation of the motor 300 is equivalent to the rotation of the rotor. Furthermore, the acceleration of the motor 300 refers to the acceleration of the rotor.

[0018] Host ECU 400 transmits a rotation instruction signal to motor drive device 100. In response to this, host ECU 400 instructs motor 300 to rotate. The rotation instruction signal may employ a duty ratio or the like that instructs motor 300 to rotate.

[0019] Furthermore, the host ECU 400 receives deterioration information indicating the degree of deterioration of the electrolytic capacitor 30 from the motor drive device 100. The deterioration information is a lifetime consumption rate and a cumulative consumption rate. The lifetime consumption rate and the cumulative consumption rate will be described in detail later.

[0020] The host ECU 400 issues a warning to the vehicle interior based on the received deterioration information. The host ECU 400 issues a warning by turning on a warning light, or by audio or visual notification via the navigation system. In other words, the host ECU 400 notifies the vehicle user of the degree of deterioration of the electrolytic capacitor 30. This allows the host ECU 400 to notify the user when it is time to replace the electrolytic capacitor 30. Furthermore, by notifying the user of the replacement time, the host ECU 400 can prevent increased costs due to unnecessary part replacement.

[0021] Furthermore, the host ECU 400 may store the received deterioration information in a non-volatile memory or the like in a state that allows it to be externally referenced as part of the diagnostic information. This allows the deterioration information to be read at a factory, a dealer, or the like. Furthermore, the host ECU 400 reflects the deterioration information in control. The reflection of the deterioration information in control will be described in detail later.

[0022] <Motor driving device 100> Motor drive device 100 is a device that rotates a cooling fan by driving motor 300. Motor drive device 100 includes a microcomputer 10, a three-phase inverter 20, an electrolytic capacitor 30, a temperature sensor 41, a current sensor 42, a Hall IC 43, etc. However, motor drive device 100 only needs to include at least microcomputer 10 and electrolytic capacitor 30. In FIG. 1, the temperature sensor is indicated as TDE, the current sensor is indicated as CDE, and the Hall IC is indicated as HIC.

[0023] The three-phase inverter 20 includes a bridge circuit using, for example, six switching elements. The three-phase inverter 20 converts DC supplied from a DC power supply 200 and an electrolytic capacitor 30 into AC. The three-phase inverter 20 also switches the power supplied to each phase coil of the stator of the motor 300 in response to a drive signal from the microcomputer 10. The motor drive device 100 may also include a pre-driver between the microcomputer 10 and the three-phase inverter 20. In this case, the three-phase inverter 20 switches the power in response to the drive signal from the pre-driver.

[0024] The electrolytic capacitor 30 is connected in parallel with the power supply 200 between the power supply 200 and the three-phase inverter 20. The electrolytic capacitor 30 stabilizes the voltage supplied from the power supply 200 to the three-phase inverter 20, and also assists the power supply to the three-phase inverter 20 by storing electric charge.

[0025] A thermistor or the like for detecting temperature can be used as the temperature sensor 41. The temperature sensor 41 is provided to detect the ambient temperature of the electrolytic capacitor 30. The microcomputer 10 obtains an electrical signal corresponding to the ambient temperature from the temperature sensor 41 to detect the ambient temperature.

[0026] The current sensor 42 may be a shunt resistor or the like for detecting current. The current sensor 42 is provided to detect the drive current of the motor 300. The microcomputer 10 detects the drive current by acquiring an electrical signal corresponding to the drive current from the current sensor 42. Note that in this embodiment, the current sensor 42 may be omitted.

[0027] The Hall IC 43 outputs a sensor signal (position detection signal) that changes in accordance with the rotation of the motor 300. The Hall IC 43 has three sensor elements, one for the U phase, one for the V phase, and one for the W phase, in order to output a sensor signal in accordance with the stator coil of each phase. Therefore, the Hall IC 43 outputs pulse wave sensor signals for each of the U phase, V phase, and W phase.

[0028] The microcomputer 10 includes a processor, a memory device 16, a notification switch 17, an input / output interface, etc. The microcomputer 10 may also include peripheral circuits such as a timer and an AD converter. The microcomputer 10 is electrically connected to the three-phase inverter 20, a temperature sensor 41, a current sensor 42, a Hall IC 43, and a host ECU 400.

[0029] In the microcomputer 10, the processor executes a program stored in the memory device 16. By executing the program, the processor performs arithmetic processing using data stored in the memory device 16 and data input from the input / output interface. In the microcomputer 10, the processor executes arithmetic processing at a predetermined control period. The microcomputer 10 can realize multiple functions that can be achieved by the processor executing arithmetic processing. It can also be said that the microcomputer 10 has multiple functional blocks. The microcomputer 10 has, for example, a rotation instruction detection unit 11, a rotation speed control unit 12, a life calculation unit 13, a temperature detection unit 14, and a life notification unit 15. In FIG. 1, the rotation instruction detection unit is denoted as IDC, the rotation speed control unit as RSC, the life calculation unit as DCC, the temperature detection unit as TDC, the life notification unit as DNC, and the memory device as MMD.

[0030] The memory device 16 includes volatile memory and non-volatile memory. The memory device corresponds to a storage device. The volatile memory temporarily stores input data, calculation results of the processor, time measurement results of the timer, etc.

[0031] The nonvolatile memory stores in advance life time data relating to the life of the electrolytic capacitor 30. Over time, the electrolytic capacitor 30 leaks electrolyte to the outside, causing a significant decrease in capacitance. This causes the internal resistance of the electrolytic capacitor 30 to increase, resulting in an extremely large impedance. In this way, the electrolytic capacitor 30 experiences so-called dry-up, reaching the end of its life. As shown in FIG. 5, the life time data associates the life time of the electrolytic capacitor 30 in each operating state with each operating state indicated by the rotation speed of the motor 300 and the ambient temperature.

[0032] Here, a lifetime is associated with each of a plurality of operating states, each of which is defined by a rotational speed range and an ambient temperature range. That is, each operating state is defined by a predetermined rotational speed range and a predetermined temperature range. For example, when motor 300 is driven to rotate in an operating state in which the ambient temperature is 20°C or less and the rotational speed is 1201 to 1600 rpm, the lifetime of electrolytic capacitor 30 is 5120. The lifetime is the estimated time (period) from the start of use of electrolytic capacitor 30 or from the time of manufacture until the electrolytic capacitor 30 no longer exhibits the predetermined characteristics.

[0033] This lifetime data can be obtained through experiments, etc. The lifetime unit is 1000 hours. However, the lifetime data shown in FIG. 5 is an example. The ranges of ambient temperature, rotation speed, and lifetime are not limited to these. The ambient temperature corresponds to the ambient temperature of the electrolytic capacitor 30.

[0034] The notification switch 17 is a switch for notifying the deterioration information via a communication line to the host ECU 400. The notification switch 17 is controlled to be turned on or off by the life notification unit 15.

[0035] <Processing operation> The processing operation of the in-vehicle system will now be described with reference to Figures 2 to 4. The in-vehicle system starts the processing shown in the flowchart of Figure 2 at predetermined time intervals.

[0036] In step S10, a rotation instruction signal is transmitted from host ECU 400. Host ECU 400 transmits the rotation instruction signal to motor drive device 100 via a communication line. In step S20, motor drive device 100 receives the rotation instruction signal. Rotation instruction detection unit 11 receives the rotation instruction signal via the communication line. Rotation instruction detection unit 11 corresponds to a rotation speed acquisition unit.

[0037] In step S30, motor drive device 100 determines the instructed rotation speed. Rotation instruction detection unit 11 determines the instructed rotation speed from the received rotation instruction signal. That is, rotation speed control unit 12 obtains the instructed rotation speed indicated by the rotation instruction signal as the rotation speed of motor 300.

[0038] In step S40, the motor drive device 100 acquires the actual rotation speed. The rotation speed control unit 12 acquires the actual rotation speed of the motor 300 based on the sensor signal from the Hall IC 43.

[0039] In step S50, motor drive device 100 generates a motor drive signal. Rotation speed control unit 12 generates the motor drive signal from the command rotation speed acquired in step S30 and the actual rotation speed acquired in step S40. For example, rotation speed control unit 12 calculates a deviation by subtracting the actual rotation speed from the command rotation speed. Rotation speed control unit 12 then generates the motor drive signal from this deviation. In other words, rotation speed control unit 12 generates the motor drive signal to perform feedback control (such as PI control) based on the deviation.

[0040] In step S60, motor drive device 100 outputs a motor drive signal. Rotation speed control unit 12 outputs the motor drive signal generated in step S50 to three-phase inverter 20. Rotation speed control unit 12 drives motor 300 to rotate via three-phase inverter 20 by outputting the motor drive signal.

[0041] In step S70, the motor driving device 100 performs a lifespan calculation process. The lifespan calculation process will be described with reference to FIG. 3. The motor driving device 100 performs the process shown in the flowchart of FIG. 3 as the lifespan calculation process. The lifespan calculation process is a process for predicting the degree of deterioration of the electrolytic capacitor 30. The lifespan calculation process is mainly executed by the lifespan calculation unit 13. The lifespan calculation unit 13 corresponds to a deterioration prediction unit.

[0042] In step S71, the current operating state is determined (measurement step). The life calculation unit 13 determines the current operating state of the motor 300. To do so, the life calculation unit 13 acquires the current ambient temperature of the electrolytic capacitor 30 and the current rotation speed of the motor 300. The current operating state corresponds to the actual operating state.

[0043] The life calculation unit 13 uses the ambient temperature detected by the temperature detection unit 14 as the current ambient temperature of the electrolytic capacitor 30. The temperature detection unit 14 detects the ambient temperature based on an electrical signal from the temperature sensor 41. The life calculation unit 13 also uses the commanded rotation speed indicated by the rotation command signal acquired by the rotation command detection unit 11 as the current rotation speed of the motor 300. The ambient temperature and the commanded rotation speed (rotation speed) here correspond to actual operation information that indicates the actual operating state of the motor 300.

[0044] As described above, in this embodiment, the current rotation speed of the motor 300 is obtained from the rotation command signal. However, the rotation speed is not limited to this. The life calculation unit 13 may obtain the rotation speed from the voltage or frequency of the rotation command signal, the sensor signal of the Hall IC 43, the target rotation speed for control, the circuit current value, etc. In this way, the rotation speed can be obtained regardless of the specifications of the rotation command signal.

[0045] In step S72, the duration of the current operating state is counted (measurement step). The lifespan calculation unit 13 counts the duration of the current operating state using a counter. It can also be said that the lifespan calculation unit 13 measures the duration of each operating state. At this time, the lifespan calculation unit 13 stores the duration, which is the count value of the counter, in volatile memory.

[0046] In step S73, it is determined whether or not there has been a change in the operating state (measurement step). The life calculation unit 13 determines whether or not there has been a change in the current operating state of the motor 300. If the life calculation unit 13 determines that there has been a change, it proceeds to step S74, and if it determines that there has not been a change, it returns to step S72. In this way, the life calculation unit 13 measures the duration of each actual operating state. The duration can also be considered as the operating time of the electrolytic capacitor 30.

[0047] For example, when the life time data in Figure 5 is used, even if the current rotation speed is changed from 1300 to 1400, it is determined that the operating state remains unchanged. On the other hand, even if the current rotation speed is changed from 1200 to 1400, it is determined that the operating state has changed.

[0048] In step S74, the duration is added. The life calculation unit 13 adds the duration of the current operating state counted as described above to the nonvolatile memory.

[0049] In step S75, the life consumption rate is calculated from the addition result (prediction step). First, the life calculation unit 13 acquires the life associated with the operating state corresponding to the actual operation information from the life time data. The life calculation unit 13 calculates the life consumption rate, which is the ratio of the addition result (cumulative duration) to the acquired life time. The life consumption rate is the operating time of the electrolytic capacitor 30 in a certain operating state relative to the life time. Therefore, the life consumption rate can also be said to be the degree of deterioration. In this way, the life calculation unit 13 predicts the degree of deterioration of the electrolytic capacitor 30. The life consumption rate corresponds to the consumption rate.

[0050] This point will be explained using the diagram of life consumption rate in Figure 6. The hatched areas in Figure 6 indicate the parts that were actually in operation. The life consumption rate is expressed as operation time / life time. Therefore, the number in the numerator of each life consumption rate is the operation time, and the number in the denominator is the life time. The operation time is measured using a counter. The life time is obtained from the life time data.

[0051] Figure 6 shows an example in which the life consumption rate is calculated for operating conditions A to D. Operating condition A is when the ambient temperature is in the range of 0 to 20°C and the rotation speed is 1201 to 1600 rpm. Operating condition B is when the ambient temperature is in the range of 41 to 60°C and the rotation speed is 1601 to 2000 rpm. Operating condition C is when the ambient temperature is in the range of 61 to 80°C and the rotation speed is 1601 to 2000 rpm. Operating condition D is when the ambient temperature is in the range of 81 to 100°C and the rotation speed is 2001 to 2400 rpm.

[0052] In actual operating state A, the operating time is 512 and the lifespan is 5120, so the lifespan consumption rate is 10%. In actual operating state B, the operating time is 24 and the lifespan is 240, so the lifespan consumption rate is 10%. In actual operating state C, the operating time is 12 and the lifespan is 60, so the lifespan consumption rate is 20%. In actual operating state D, the operating time is 1.5 and the lifespan is 12, so the lifespan consumption rate is 50%. The operating time here is the cumulative time of the duration added up in step S74.

[0053] In this way, the lifespan calculation unit 13 calculates the lifespan consumption rate using the duration stored in the volatile memory each time the actual operating state changes. Then, the lifespan calculation unit 13 may cumulatively add up the calculated lifespan consumption rates and store them in the non-volatile memory. In the example of FIG. 6, the lifespan calculation unit 13 cumulatively adds up a lifespan consumption rate of 10% in actual operating state A, a lifespan consumption rate of 10% in actual operating state B, a lifespan consumption rate of 20% in actual operating state C, and a lifespan consumption rate of 50% in actual operating state D. Therefore, the lifespan consumption rate in this case is 90%. Furthermore, a consumption rate obtained by cumulatively adding up multiple lifespan consumption rates is also referred to as a cumulative consumption rate. The cumulative consumption rate corresponds to a cumulative value.

[0054] After storing the cumulative consumption rate in the nonvolatile memory, motor drive device 100 may execute a notification process shown in the flowchart of FIG.

[0055] In step S80, it is determined whether or not the cumulative consumption rate has exceeded the life threshold (determination step). If it is determined that the cumulative consumption rate has exceeded the life threshold, the life calculation unit 13 proceeds to step S90, and if it is determined that the cumulative consumption rate has not exceeded the life threshold, the flow chart of Fig. 4 ends. Note that the life calculation unit 13 may proceed to step S90 if the cumulative consumption rate has reached the life threshold, or may end the flow chart of Fig. 4 if the cumulative consumption rate has not reached the life threshold.

[0056] In step S90, the cumulative consumption rate is notified to the host ECU 400 (notification step). When it is determined that the cumulative consumption rate has reached the life threshold, the life notification unit 15 notifies the host ECU 400 of the cumulative consumption rate. The life notification unit 15 turns on the notification switch 17. This causes the life notification unit 15 to notify the host ECU 400 of the cumulative consumption rate by pulling down the communication line between the life notification unit 15 and the host ECU 400 to ground. In other words, the life notification unit 15 forcibly pulls down the rotation instruction signal to ground and notifies the host ECU 400 of the cumulative consumption rate by duty. This allows the motor drive device 100 to notify the host ECU 400 of the degree of deterioration of the electrolytic capacitor 30.

[0057] However, the method of notifying the cumulative consumption rate is not limited to this. Motor drive device 100 may notify host ECU 400 via a signal line different from the communication line. Also, motor drive device 100 may notify not only duty but also frequency or voltage value. Furthermore, motor drive device 100 may notify not only duty but also frequency or voltage value. Furthermore, motor drive device 100 may notify not only duty but also frequency or voltage value.

[0058] The microcomputer 10 may notify the host ECU 400 not only when the cumulative consumption rate reaches the life threshold value. The microcomputer 10 may notify the host ECU 400 every time it calculates the cumulative consumption rate, or every time it stores the cumulative consumption rate in non-volatile memory. The microcomputer 10 may also notify the host ECU 400 of the lifetime consumption rate for each operating state. In other words, the microcomputer 10 may notify the host ECU 400 every time it calculates the lifetime consumption rate. The host ECU 400 then accumulates the notified lifetime consumption rates to calculate the cumulative consumption rate.

[0059] <Effects> In this way, motor drive device 100 predicts the degree of deterioration of electrolytic capacitor 30 by calculating the life consumption rate from the life time obtained from the life time data and the measured duration. Therefore, motor drive device 100 does not need to use multiple temperature sensors, etc., and can predict the degree of deterioration of electrolytic capacitor 30 without increasing the number of parts. Furthermore, since the in-vehicle system is equipped with motor drive device 100, it can predict the degree of deterioration of electrolytic capacitor 30 without increasing the number of parts. Furthermore, motor drive device 100 uses the life time data and the duration of the operating state that is actually measured, so it can predict the degree of deterioration with high accuracy.

[0060] The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure. Below, Modifications 1 and 2 will be described as other embodiments of the present disclosure. The above embodiments and Modifications 1 and 2 can be implemented independently, or can be implemented in appropriate combinations. The present disclosure is not limited to the combinations shown in the embodiments, and can be implemented in various combinations.

[0061] (Variation 1) In the motor drive device 100, current fluctuates due to variations in the load on the motor 300, which causes fluctuations in the temperatures of the switching elements of the three-phase inverter 20 and the electrolytic capacitor 30. Therefore, the microcomputer 10 may correct the life consumption rate according to the amount of current flowing through the motor 300 (deterioration prediction unit).

[0062] The microcomputer 10 obtains an electrical signal corresponding to the drive current from the current sensor 42 and detects the drive current (current value). The microcomputer 10 corrects the life consumption rate according to the difference between the detected current value and a reference value. If the current value is greater than the reference value, the microcomputer 10 corrects the life consumption rate to a higher value according to the difference. On the other hand, if the current value is smaller than the reference value, the microcomputer 10 corrects the consumption rate to a lower value according to the difference. For example, if the current value is 10% higher, the microcomputer 10 calculates the element temperature from the current value at each rotation speed and reduces the life time by the amount of the element temperature increase according to the Arrhenius law. This allows the motor drive device 100 to predict the degree of deterioration taking into account load variations.

[0063] (Variation 2) Modification 2 will be described using Figure 7. Modification 2 differs from the above embodiment in that the notified life consumption rate (deterioration information) is reflected in the control. Figure 7 shows the time changes in rotation speed and life consumption rate while the engine is idling. The left diagram is a diagram showing the case where the life consumption rate is not reflected in the control. The right diagram is a diagram showing the case where the life consumption rate is reflected in the control. In Figure 7, the solid line shows the rotation speed and the dotted line shows the life consumption rate. Note that engine idling refers to a state in which the engine is running and continues to rotate at a constant rotation speed without the accelerator being depressed.

[0064] The motor drive device 100 (microcomputer 10) notifies the host ECU 400 of the life consumption rate as well as each piece of actual operation information used to calculate the life consumption rate. Here, the microcomputer 10 transmits each life consumption rate and the actual operation information used to calculate each life consumption rate to the host ECU 400.

[0065] The host ECU 400 determines whether each piece of received actual operation information indicates a low-demand state where cooling by the cooling fan is low. That is, the host ECU 400 determines whether the ambient temperature and rotation speed in all of the received actual operation information correspond to a low-demand state. The host ECU 400 then calculates the proportion of the actual operation information that corresponds to a low-demand state.

[0066] A low-demand situation can be, for example, an ambient temperature of 40°C or less and a rotation speed of 1200 rpm or less. For example, taxis and shuttle vehicles idle for longer periods of time than general users. When idling, engine heat generation is low, so this can be considered a low-demand situation in which there is little need for cooling by a cooling fan.

[0067] Furthermore, the host ECU 400 determines whether the calculated ratio exceeds a predetermined value. If the host ECU 400 determines that the calculated ratio does not exceed the predetermined value, it can be determined that there is little operation in low demand situations. In this case, the host ECU 400 continuously transmits rotation instructions as shown in the left diagram of FIG.

[0068] On the other hand, if the host ECU 400 determines that the calculated ratio exceeds a predetermined value, it can be determined that the system is operating mostly under low demand conditions. In this case, the host ECU 400 transmits rotation instructions intermittently, as shown in the right diagram of Fig. 7. Here, as an example, an example is adopted in which the transmission time is intermittently operated for 50%.

[0069] This allows the in-vehicle system to prevent overheating. Furthermore, the in-vehicle system can reduce the life consumption rate during idling. Therefore, the in-vehicle system can slow the rate of deterioration of the electrolytic capacitor 30, as shown by the white arrow in FIG. 7. Note that even with Modification 2, the effects of the above-described embodiment can be achieved. Modification 2 can be implemented in combination with at least one of the above-described embodiment and Modification 1.

[0070] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0071] 100...motor drive device, 10...microcomputer, 20...three-phase inverter, 30...electrolytic capacitor, 41...temperature sensor, 42...current sensor, 43...Hall IC, 200...power supply, 300...motor, 400...host ECU

Claims

1. A motor drive device that includes an electrolytic capacitor connected in parallel to a power supply and drives a motor to rotate a cooling fan, a rotation speed acquisition unit (11) that acquires the rotation speed of the motor; a temperature detection unit (14) for detecting the ambient temperature of the electrolytic capacitor; a deterioration prediction unit (13) for predicting the degree of deterioration of the electrolytic capacitor; a storage device (16) storing lifetime data in which lifetime data of the electrolytic capacitor in each operating state of the motor indicated by the rotation speed and the ambient temperature is associated with the lifetime data of the electrolytic capacitor in each operating state; The deterioration prediction unit a measurement step (S71 to S74) of acquiring the rotation speed from the rotation speed acquisition unit and the ambient temperature from the temperature detection unit as actual operation information indicating the actual operation state of the motor, and measuring the duration of each of the actual operation states; a prediction step (S75) of obtaining the lifetime associated with the operating state corresponding to the actual operation information from the lifetime data, and predicting the degree of deterioration of the electrolytic capacitor by calculating a consumption rate which is the ratio of the duration to the lifetime.

2. the storage device includes a volatile memory and a non-volatile memory; In the measuring step, the duration is stored in the volatile memory; 2. The motor drive device according to claim 1, wherein in the prediction step, the consumption rate is calculated using the duration stored in the volatile memory each time the actual operating state changes, and the calculated consumption rate is cumulatively added and stored in the non-volatile memory.

3. 3. The motor drive device according to claim 1, wherein the deterioration prediction unit detects a current flowing through the motor and corrects the consumption rate in accordance with a difference between the detected current value and a reference value, and if the current value is greater than the reference value, corrects the consumption rate to a higher value in accordance with the difference, and if the current value is smaller than the reference value, corrects the consumption rate to a lower value in accordance with the difference.

4. a motor drive device according to claim 1; and an electronic control device that outputs a rotation instruction for the motor to the motor drive device; The in-vehicle system includes a notification step (S90) in which the motor drive device notifies the electronic control device of the consumption rate.

5. The motor drive device further includes a determination step (S80) of determining whether or not the cumulative value of the consumption rate has reached a threshold value, The in-vehicle system according to claim 4 , wherein the notification step notifies when it is determined that the cumulative value has reached the threshold value.

6. The vehicle is equipped with an engine as a power source, the motor drive device notifies the electronic control device of the actual operation information for calculating the consumption rate in addition to the consumption rate, 6. The in-vehicle system according to claim 4, wherein the electronic control unit determines, for all received actual operation information, whether the ambient temperature and the rotation speed in each piece of actual operation information correspond to a low-demand state in which cooling by the cooling fan is low, calculates a proportion of the actual operation information that corresponds to the low-demand state, and further determines whether the proportion exceeds a predetermined value. If it is determined that the proportion exceeds a predetermined value, the electronic control unit determines that operation is largely in the low-demand state and intermittently outputs the rotation instruction.

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