JP6844028B2 - Power converter - Google Patents

Description

The present invention relates to a power converter.

In recent years, for example, in the field of automobiles, motor and generator systems that have both a power source and power generation, such as electric vehicles or hybrid vehicles, have been rapidly advanced. Most of these systems are composed of a generator that combines power and power generation, and a power converter that controls the generator. The power conversion device, it is necessary electrolytic capacitor for smoothing a voltage store energy. As the electrolytic capacitor, a low-profile aluminum electrolytic capacitor or a hybrid type electrolytic capacitor is used in order to reduce the size of the power conversion device. The hybrid type electrolytic capacitor is a mixture of an aluminum electrolytic capacitor and a conductive polymer. By suppressing the equivalent series resistance (ESR), the hybrid type electrolytic capacitor can suppress the heat generation with the current applied, and can be further miniaturized as compared with the aluminum electrolytic capacitor. As the output of the electric motor increases in order to improve fuel efficiency, the current applied to the electrolytic capacitor tends to increase.

In these electrolytic capacitors, if the electrolytic solution evaporates due to heat generated when a current is applied, the leakage current increases or the capacitance decreases, and their deterioration exceeds a certain value, a failure occurs. In addition, if the power converter does not operate for a long time and no voltage is applied to the electrolytic capacitor, moisture will infiltrate into the electrolytic capacitor and the aluminum oxide film or aluminum foil will corrode, resulting in deterioration and shortage. There is a problem of life.

Patent Document 1 describes a method for preventing corrosion of the aluminum foil in the electrolytic capacitor due to humidity when a voltage is not applied to the electrolytic capacitor in the electric capacitor because the power conversion device does not operate for a long period of time. ing. This power converter measures the time from stop with a timer, connects the main power supply and the electrolytic capacitor after a certain period of time, and applies a voltage to the electrolytic capacitor to apply the electrolytic solution originally contained in the electrolytic capacitor. Promotes the repairing action of the aluminum oxide film, and suppresses the deterioration of the electrolytic capacitor.

Japanese Unexamined Patent Publication No. 2006-213433

However, for such deterioration due to humidity of the electrolytic capacitor or deterioration due to long-term use, the aluminum oxide film may not be sufficiently repaired by simply applying a voltage.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a power conversion device capable of sufficiently repairing an aluminum oxide film.

In order to solve the above problems, the power conversion device of the present invention has a power conversion unit that converts and outputs the power supplied from the power source, a smoothing capacitor connected to the power conversion unit, and a smoothing capacitor and a power source. A switch for connecting or disconnecting a capacitor, a detector that detects at least one of the temperature of the smoothing capacitor or the voltage across the smoothing capacitor, and a power converter based on the data obtained from the detector. It is equipped with a control device that controls the switch after the operation is stopped. The smoothing capacitor is composed of an aluminum electrolytic capacitor or a hybrid aluminum electrolytic capacitor.

According to the present invention, power conversion is performed based on data obtained from a detector that detects at least one of the temperature of a smoothing capacitor composed of an aluminum electrolytic capacitor or a hybrid aluminum electrolytic capacitor or the voltage across the smoothing capacitor. Controls a switch to connect or disconnect the smoothing capacitor and power source after the device is shut down. As a result, the aluminum oxide film of the smoothing capacitor can be sufficiently repaired.

It is a figure which shows the structure of the power conversion apparatus 19 of Embodiment 1. FIG. And temperature electrolytic capacitors is a diagram showing the relationship between the rate of decrease of the leakage current before and after applying a DC voltage to an electrolytic capacitor. It is a flowchart which shows the control procedure of the power conversion apparatus 19 of Embodiment 1. FIG. It is a flowchart which shows the control procedure of the power conversion apparatus 19 of Embodiment 2. It is a figure which shows the structure of the power conversion apparatus 29 of Embodiment 3. It is a flowchart which shows the control procedure of the power conversion apparatus 29 of Embodiment 3. It is a flowchart which shows the control procedure of the power conversion apparatus 29 of Embodiment 4. It is a figure which shows the structure of the power conversion apparatus 39 of Embodiment 5. It is a flowchart which shows the control procedure of the power conversion apparatus 39 of Embodiment 5. It is a figure which shows the structure of the power conversion apparatus 49 of Embodiment 6. It is a flowchart which shows the control procedure of the power conversion apparatus 49 of Embodiment 6. It is a flowchart which shows the control procedure of the power conversion apparatus 49 of Embodiment 7. It is a figure which shows the waveform of the d-axis voltage Vd of a motor 18, the d-axis current Id of a motor 18, and the current Ic of a smoothing capacitor 13 in Embodiment 8.

Hereinafter, embodiments will be described with reference to the drawings. In the following description, an inverter for driving a three-phase AC motor for an automobile used in an electric vehicle or a hybrid vehicle will be described, but the present invention is not limited thereto. The present invention is applicable to various power conversion devices such as an air conditioner using an aluminum electrolytic capacitor or a hybrid aluminum electrolytic capacitor as a smoothing capacitor, an elevator, and an inverter for driving an escalator motor.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of the power conversion device 19 of the first embodiment.

The power conversion device 19 includes a power conversion unit 14, a smoothing capacitor 13, a switch 12, a temperature detector 15, and a control device 17.

The power conversion unit 14 includes switching elements 14a, 14b, 14c, 14d, 14e, and 14f. The power conversion unit 14 converts the DC power supplied from the power source 11 into three-phase AC power and supplies it to the motor 18. The power source 11 is composed of a battery.

The power conversion unit 14 includes an upper arm switching element 14a and a lower arm switching element 14b for the U phase. The switching elements 14a and 14b are connected in series. The power conversion unit 14 includes an upper arm switching element 14c and a lower arm switching element 14d for the V phase. The switching elements 14c and 14d are connected in series. The power conversion unit 14 includes an upper arm switching element 14e and a lower arm switching element 14f for the W phase. The switching elements 14e and 14f are connected in series. Diodes Da, Db, Dc, Dd, De, and Df are connected in parallel to the switching elements 14a to 14f, respectively. For the switching elements 14a to 14f, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistor) are used.

The smoothing capacitor 13 is provided between the power source 11 and the power conversion unit 14, and smoothes the voltage supplied from the power source 11 to the power conversion unit 14. As the smoothing capacitor 13, an aluminum electrolytic capacitor or a capacitor using an electrolytic solution typified by a hybrid aluminum electrolytic capacitor (hereinafter, both capacitors are collectively referred to as an electrolytic capacitor) is used.

In the first embodiment, the temperature of the smoothing capacitor 13 is measured by the temperature detector 15. Thereby, the smoothing capacitor 13 can be repaired immediately after the automobile, the air conditioner, the elevator, or the escalator is stopped.

As the temperature detector 15, for example, a thermistor or a sensor using magnetism is used. The temperature detector 15 is installed around the smoothing capacitor 13. In order to measure the temperature of the smoothing capacitor 13 with high accuracy, it is desirable that the temperature detector 15 is installed at a position such as a side wall or a top surface of the smoothing capacitor 13 so as to be in contact with the smoothing capacitor 13.

The control device 17 controls the switch 12 based on the temperature detected by the temperature detector 15. The control device 17 is composed of a processing circuit. When the processing circuit is dedicated hardware, the processing circuit is, for example, a single circuit, a composite circuit, a programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Can be. When the processing circuit is a CPU, the function of the control device 17 is realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory. The processing circuit realizes the function of the control device 17 by executing the program stored in the memory. Here, the memory corresponds to a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, or a magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD, or the like. It should be noted that each function of the control device 17 may be partially realized by dedicated hardware and partly realized by software or firmware.

First, the conventional control of the power conversion device 19 will be described.
When the power switch of the automobile is turned on (hereinafter, the automobile may be activated), the power conversion device 19 is activated. The control device 17 connects the power source 11, the smoothing capacitor 13, and the power conversion unit 14 by turning on the switch 12. As a result, the car is ready to run. When the power conversion device 19 is started, after a device that uses the power of the power conversion device 19 such as an automobile or an air conditioner is started and the power source 11 is connected to the smoothing capacitor 13 and the power conversion unit 14. The state before the start of switching control of the switching elements 14a, 14b, 14c, 14d, 14e, 14f.

When the automobile starts running, the power converter 19 starts operating. That is, the control device 17 switches and controls the switching elements 14a, 14b, 14c, 14d, 14e, 14f of the power conversion unit 14 based on the required output of the motor 18. As a result, the DC power of the power source 11 is converted into three-phase AC power and supplied to the motor 18. The state in which the power conversion device 19 is operating means a state in which switching control of the switching elements 14a, 14b, 14c, 14d, 14e, and 14f is performed.

On the other hand, when the automobile is stopped, the power conversion device 19 stops operating. That is, the control device 17 stops the switching control of the switching elements 14a, 14b, 14c, 14d, 14e, 14f. The state in which the power conversion device 19 is stopped means a state in which the switching control of the switching elements 14a, 14b, 14c, 14d, 14e, and 14f is stopped.

At this time, in the conventional control, the control device 17 separates the power source 11, the smoothing capacitor 13, and the power conversion unit 14 by turning off the switch 12. As a result, all the electric charges accumulated in the smoothing capacitor 13 are discharged after a certain period of time due to the leakage current of the smoothing capacitor 13 itself, the wiring resistance, or the like. Here, according to the conventional example described in Patent Document 1, when the elapsed time after the power conversion device is stopped is measured by a timer and it is detected that a certain time has elapsed, a voltage is applied to the smoothing capacitor to make aluminum. In order to repair the oxide film, the power source 11 and the smoothing capacitor 13 are connected.

However, when the smoothing capacitor 13 and the power source 11 are connected, the repair speed of the aluminum oxide film is greatly affected by the temperature of the smoothing capacitor 13 in addition to the magnitude of the voltage and the application time of the voltage.

Next, the result of examining how the temperature affects the repair of the electrolytic capacitor by applying a DC voltage to the electrolytic capacitor will be described.

2, a temperature of electrolytic capacitors is a diagram showing the relationship between the rate of decrease of the leakage current before and after applying a DC voltage to an electrolytic capacitor.

In FIG. 2, the vertical axis represents the reduction rate of the leakage current, and the horizontal axis represents the temperature of the electrolytic capacitor. Leakage current when an electrolytic capacitor rated at 100 μF-63 V is installed in a constant temperature bath set at 25 ° C, 50 ° C, 75 ° C, and 100 ° C and a DC voltage (rated voltage 63 V of the electrolytic capacitor) is applied for 30 minutes. The rate of decrease is shown. For comparison, the reduction rate of the leakage current of the electrolytic capacitor left in a constant temperature bath set at 25 ° C., 50 ° C., 75 ° C., and 100 ° C. for 30 minutes without applying a DC voltage is also shown. Here, the reduction rate of the leakage current, and the initial leakage current I0, by using the leakage current I1 after 30 minutes, represented by (I1-I0) / I 0 .

Here, the degree of repair of the aluminum oxide film of the electrolytic capacitor under each condition can be estimated from the reduction rate of the leakage current after a certain period of time after applying the DC voltage to the electrolytic capacitor. When a DC voltage is applied to repair the aluminum oxide film of the electrolytic capacitor, the leakage current becomes smaller. Therefore, the larger the reduction rate of the leakage current before and after the application of the DC voltage, the higher the repair speed of the aluminum oxide film.

As shown in FIG. 2, when the temperature of the electrolytic capacitor is high, particularly when a DC voltage is applied at 50 ° C. or higher, the reduction rate of the leakage current is large and the repair of the aluminum oxide film is promoted. It was also found that the repair speed increases at 50 ° C. or higher. These experiments simulate an environment in which an electrolytic capacitor incorporated in a power converter of an automobile, an air conditioner, an elevator, or an escalator is placed, and it is considered that the same tendency is shown in an actual product.

FIG. 3 is a flowchart showing a control procedure of the power conversion device 19 of the first embodiment.
In step S10, when the operation of the power conversion device 19 is stopped due to the vehicle stopping, the process proceeds to step S11.

In step S11, the control device 17 maintains the on state of the switch 12 and continues the connection between the power source 11 and the smoothing capacitor 13. Immediately after the vehicle is stopped, the temperature inside the power converter 19 in the vehicle is about 50 ° C. to 150 ° C., although it is affected by the surrounding environment, the mileage, and the traveling time. Conventionally, after the automobile is stopped, the switch 12 connecting the power source 11 and the smoothing capacitor 13 is turned off, and the power source 11 and the smoothing capacitor 13 are separated from each other. On the other hand, in the first embodiment, for the purpose of repairing the smoothing capacitor 13, the switch 12 for connecting the power source 11 and the smoothing capacitor 13 is kept on, so that the vehicle is running (that is, the power conversion device). The connection between the power source 11 and the smoothing capacitor 13 during the operation of 19) is continued even after the vehicle is stopped (that is, the operation of the power conversion device 19 is stopped).

In step S12, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S13, when the control device 17 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1 (S13: YES), the process returns to step S12. Here, the set temperature TH1 is preferably 50 ° C. or higher so that a sufficient repair rate of the oxide film as shown in FIG. 2 can be obtained. If the set temperature TH1 is too low, a sufficient repair speed of the oxide film cannot be obtained, so that repair for a long time is required, and power loss occurs due to the leakage current of the smoothing capacitor 13 itself, so that power consumption is consumed. Is large.

When the control device 17 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is less than the set temperature TH1 (S13: NO), the process proceeds to step S14.

In step S14, the control device 17 disconnects the power source 11 and the smoothing capacitor 13 by turning off the switch 12.

As described above, in the present embodiment, immediately after the automobile is stopped, that is, the operation of the power conversion device is stopped, the power source 11 and the electrolytic capacitor used as the smoothing capacitor 13 are connected at a high temperature to form an aluminum oxide film. Restoration is promoted. Further, if the power source and the smoothing capacitor are left connected after the aluminum oxide film is repaired, power is consumed due to the leakage current of the capacitor. Therefore, after the repair, the power source 11 and the smoothing capacitor 13 are separated from each other. The life of the power converter can be efficiently extended.

The timing at which the temperature detector 15 samples the temperature of the smoothing capacitor 13 can be arbitrarily set.

Further, when the self-heating temperature due to the ripple current flowing through the smoothing capacitor 13 during the operation of the power conversion device 19 becomes 5 ° C. or higher, the deterioration of the aluminum oxide film of the smoothing capacitor 13 becomes remarkable. Therefore, in this case, the effect of repairing the aluminum oxide film by applying the first embodiment becomes more remarkable.

Embodiment 2.
In the first embodiment, after the operation of the power conversion device 19 is stopped due to the vehicle stopping running, the connection between the power source 11 and the electrolytic capacitor used as the smoothing capacitor 13 is maintained and the aluminum oxide film is repaired each time. .. When the aluminum oxide film is repaired every time the operation of the power conversion device 19 is stopped, it is advantageous in terms of suppressing deterioration of the electrolytic capacitor, but the frequency of power consumption required for the repair increases. Therefore, the power conversion device of the second embodiment determines whether or not to maintain the connection between the power source 11 and the smoothing capacitor 13 for repairing the aluminum oxide film after the operation of the power conversion device is stopped.

A power converter for driving a motor such as an automobile requires a large torque when the motor is started, so that the electric charge accumulated in the electrolytic capacitor is released and a large current temporarily flows. , The deterioration of the electrolytic capacitor also increases. In particular, when the inside of the power converter becomes hot when the automobile is stopped in the summer, the deterioration of the electrolytic capacitor becomes even greater.

On the other hand, when the temperature inside the power converter is low in winter or in cold regions, the slip of the belt that transmits the power of the motor increases, and a larger current is required than during normal starting. Deterioration of the capacitor becomes large.

Therefore, when the temperature of the smoothing capacitor 13 at the time when the operation of the power conversion device 19 starts when the vehicle starts running is within a preset temperature range, the operation of the power conversion device 19 occurs when the vehicle stops. Is stopped, the connection between the power source 11 and the smoothing capacitor 13 is maintained, and the smoothing capacitor 13 is repaired. When the temperature of the smoothing capacitor 13 at the time when the operation of the power conversion device 19 starts is out of the preset temperature range, the power source 11 and the smoothing capacitor are stopped after the operation of the power conversion device 19 is stopped due to the vehicle stopping. The connection with 13 is cut off. In the case of a power converter used in an automobile, the temperature range to be set can be 0 ° C. or lower and 50 ° C. or higher in consideration of the actual environment.

Configuration of the power conversion apparatus of the second embodiment is similar to the configuration of the power conversion equipment 1 9 of the first embodiment.

FIG. 4 is a flowchart showing a control procedure of the power conversion device 19 of the second embodiment.
In step S20, when the operation of the power conversion device 19 is started by starting the traveling of the automobile, the process proceeds to step S21.

In step S21, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13 at the start of the operation of the power converter 19.

In step S22, it is determined whether or not the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is within the set temperature range.

When the temperature of the smoothing capacitor 13 detected by the temperature detector 15 is within the set temperature range (S22: YES), the process proceeds to step S23. If the temperature of the smoothing capacitor 13 is outside the set temperature range (S22: NO), the process proceeds to step S28.

In step S28, when the operation of the power conversion device 19 is stopped due to the vehicle stopping, the process proceeds to step S29.

In step S29, the control device 17 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13, disconnects the power source 11 and the smoothing capacitor 13, and ends the control.

Regarding steps S23 to S27, similarly to steps S10 to S14 of the first embodiment, when the temperature of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1, the power source 11 and the smoothing capacitor 13 Continue the connection with and repair the aluminum oxide film. When the temperature detected by the temperature detector 15 becomes less than the set temperature TH1, the control device 17 turns off the switch 12 connecting the power source 11 and the smoothing capacitor 13, and turns off the power source 11 and the smoothing capacitor 13. To disconnect.

As described above, according to the present embodiment, the power conversion device starts operation at a high temperature (for example, 50 ° C. or higher) or a low temperature (for example, a temperature of 0 ° C. or lower) at which the load of the electrolytic capacitor used as the smoothing capacitor becomes large. In some cases, it is possible to extend the life of the power converter and reduce the power consumption required for the repair by efficiently repairing the aluminum oxide film after the automobile is stopped, that is, after the power converter has stopped operating. it can.

Incidentally, in the case of an automobile, short operating time, when the temperature of the smoothing capacitor after the automobile is stopped (after the stop of the operation of the power converter) is not only increased to a temperature lower than the set temperature, the aluminum oxide film Is not repaired. Therefore, in step S25, the aluminum oxide film may be repaired regardless of the temperature of the smoothing capacitor.

Embodiment 3.
The power conversion device according to the third embodiment is used to oxidize aluminum by connecting the power source 11 and the smoothing capacitor 13 when the smoothing capacitor 13 is significantly deteriorated after the vehicle has stopped running, that is, after the power conversion device has stopped operating. Determine if the membrane is to be repaired.

FIG. 5 is a diagram showing the configuration of the power conversion device 29 according to the third embodiment.
The power conversion device 29 of the third embodiment differs from the power conversion device 19 of the first embodiment in that the power conversion device 29 of the third embodiment includes the voltage detector 20 and the control device 17. The point is that the control device 27 is provided instead of the above.

The voltage detector 20 detects the voltage across the smoothing capacitor 13.
Here, at the design stage of the power conversion device 29, the capacitor has a desired capacitance so that the voltage fluctuation width at both ends of the smoothing capacitor 13 becomes a constant value or less when the vehicle is running, that is, during the operation of the power conversion device 29. The smoothing capacitor 13 is selected. However, with electrolytic capacitors, the capacitance gradually decreases due to the evaporation of the electrolytic solution due to the heat generated by the application of current when the vehicle is running, or the application of a large current during low-temperature starting, so the voltage fluctuation range is large. Become. Therefore, the deterioration of the smoothing capacitor 13 can be detected from the voltage fluctuation range detected by the voltage detector 20. Then, the smoothing capacitor 13 can be repaired only when the deterioration of the smoothing capacitor 13 is large.

FIG. 6 is a flowchart showing a control procedure of the power conversion device 29 according to the third embodiment.
In step S30, when the operation of the power conversion device 29 starts by starting the traveling of the automobile, the process proceeds to step S31.

In step S31, the voltage detector 20 measures the voltage fluctuation width VB at both ends of the smoothing capacitor 13 during the operation of the power conversion device 29, and outputs the voltage fluctuation width VB to the control device 27.

In step S32, the control device 27 determines whether or not the voltage fluctuation width VB across the smoothing capacitor 13 detected by the voltage detector 20 is equal to or larger than the set voltage width THW. When it is determined that the voltage fluctuation width VB is equal to or larger than the set voltage width THW (S32: YES), the process proceeds to step S33. If the voltage fluctuation width VB is less than the set voltage width THW (S32: NO), the process proceeds to step S38.

In step S38, when the operation of the power conversion device 19 is stopped due to the vehicle stopping, the process proceeds to step S39.

In step S39, the control device 17 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13, disconnects the power source 11 and the smoothing capacitor 13, and ends the control.

Regarding steps S33 to S37, similarly to steps S10 to S14 of the first embodiment, when the temperature of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1, the power source 11 and the smoothing capacitor 13 Continue the connection with and repair the aluminum oxide film. When the temperature detected by the temperature detector 15 becomes less than the set temperature TH1, the control device 17 turns off the switch 12 connecting the power source 11 and the smoothing capacitor 13, and turns off the power source 11 and the smoothing capacitor 13. To disconnect.

As described above, in the present embodiment, when the electrolytic capacitor used as the smoothing capacitor is deteriorated, the aluminum oxide film is repaired to extend the life of the power conversion device and the consumption required for repairing the aluminum oxide film. Power can be suppressed.

Embodiment 4.
In the third embodiment, the deterioration of the smoothing capacitor 13 is detected while the automobile is running, that is, while the power conversion device 29 is operating. However, when the voltage fluctuation becomes large temporarily due to the fluctuation of the output of the motor 18 or the like while the automobile is running, the deterioration of the smoothing capacitor 13 may not be detected accurately. Therefore, in the fourth embodiment, the deterioration of the smoothing capacitor 13 is accurately detected when the vehicle is not running at the time of starting the vehicle, that is, when the power conversion device is started.

The configuration of the power conversion device of the fourth embodiment is the same as the configuration of the power conversion device 29 of the third embodiment.

FIG. 7 is a flowchart showing a control procedure of the power conversion device 29 according to the fourth embodiment.
In step S40, the power conversion device 29 is started by starting the automobile, and when the control device 27 connects the power source 11 and the smoothing capacitor 13, the process proceeds to step S41.

In step S41, the voltage detector 20 detects the voltage across the smoothing capacitor 13 to detect the time required to charge the smoothing capacitor 13 (hereinafter referred to as the charging time ) and outputs the time to the control device 27.

In step S42, the control device 27 determines whether or not the charging time of the smoothing capacitor 13 is equal to or less than the set time TT1. Here, since the charging time of the smoothing capacitor 13 is determined by the product of the output impedance of the power source 11 and the capacitance of the smoothing capacitor 13, the charging time becomes shorter as the capacitance of the smoothing capacitor 13 decreases. Therefore, the deterioration of the smoothing capacitor 13 can be determined by detecting the charging time required for charging the smoothing capacitor 13.

When the power conversion device 29 is started by starting the automobile, the detection is performed in a state where the output of the motor 18 does not fluctuate, so that the deterioration of the smoothing capacitor 13 can be detected with high accuracy.

When the charging time TC is equal to or less than the set time TT1 (S42: YES), the process proceeds to step S43. When the charging time TC exceeds the set time TT1 (S42: NO), the process proceeds to step S48.

In step S48, when the operation of the power conversion device 19 is stopped due to the vehicle stopping, the process proceeds to step S49.

In step S49, the control device 27 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13, disconnects the power source 11 and the smoothing capacitor 13, and ends the control.

Regarding steps S43 to S47, similarly to steps S10 to S14 of the first embodiment, when the temperature of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1, the control device 27 is the power source 11. And the smoothing capacitor 13 are continued to be connected to repair the aluminum oxide film. When the temperature detected by the temperature detector 15 becomes less than the set temperature TH1, the control device 27 turns off the switch 12 connecting the power source 11 and the smoothing capacitor 13, and turns off the power source 11 and the smoothing capacitor 13. To disconnect.

According to this embodiment, deterioration of the smoothing capacitor is detected with high accuracy based on the charging time of the smoothing capacitor when the power conversion device is started, and when the smoothing capacitor deteriorates, the aluminum oxide film is repaired. Therefore, it is possible to extend the life of the power conversion device and suppress the power consumption required for repairing the aluminum oxide film.

Embodiment 5.
In the power conversion devices of the first to fourth embodiments, the aluminum oxide film of the electrolytic capacitor used as the smoothing capacitor 13 was repaired by connecting the power source 11 mounted on the automobile and the smoothing capacitor 13. By the way, in recent years, in electric vehicles and hybrid vehicles in the automobile field, the number of automobiles that charge a power source by a commercial AC power source, a solar cell mounted on the automobile, or a power supply from an external power source has been increasing. Similarly, other power conversion devices such as air conditioners and elevators may be supplied with power from an external power source such as a solar cell.

Therefore, in the fifth embodiment, the repair of the aluminum oxide film of the smoothing capacitor 13 is performed not only by connecting the power source 11 of the automobile and the smoothing capacitor 13 as described in the first to fourth embodiments, but also by power conversion. When the device is connected to a commercial power source or an external power source such as a solar cell mounted on an automobile, the external power source is used to repair the aluminum oxide film of the smoothing capacitor 13.

FIG. 8 is a diagram showing the configuration of the power conversion device 39 according to the fifth embodiment.
The power conversion device 39 of the fifth embodiment differs from the power conversion device 19 of the first embodiment in that the power conversion device 39 of the fifth embodiment includes a connection port 23, a temperature detector 15 and a control device. Instead of 17, the connection detector 24 and the control device 37 are provided.

The connection port 23 can be connected to a commercial power source or an external power source 22 such as a solar cell mounted on an automobile.

The connection detector 24 detects whether or not the external power supply 22 is connected to the connection port 23.
When the connection detector 24 detects that the external power supply 22 is connected to the connection port 23, the control device 37 turns on the switch 12 to connect the external power supply 22, the power source 11, and the smoothing capacitor 13. To connect.

FIG. 9 is a flowchart showing a control procedure of the power conversion device 39 according to the fifth embodiment.
When the connection detector 24 detects the connection between the external power supply 22 and the connection port 23 in step S50, the process proceeds to step S51.

In step S51, the control device 37 turns on the switch 12 to connect the external power source 22, the power source 11, and the smoothing capacitor 13.

In step S52, when the connection detector 24 detects that the connection between the external power supply 22 and the connection port 23 is maintained (S52: YES), the switch 12 is kept on. When the connection detector 24 detects that the connection between the external power supply 22 and the connection port 23 is cut off (S52: NO), the process proceeds to step S53.

In step S53, when the switch 12 is turned off, the control device 37 disconnects the external power supply 22, the power source 11, and the smoothing capacitor 13, and the control ends.

According to this embodiment, the aluminum oxide film can be repaired by an external power source, and the life of the power conversion device can be extended.

Here, even when the external power supply 22 is used, power is required to repair the smoothing capacitor 13, so that the switch 12 is controlled by the temperature or the deteriorated state of the smoothing capacitor 13 as described in the first to fourth embodiments. By doing so, the connection or disconnection of the external power supply 22 and the power source 11 and the smoothing capacitor 13 may be switched.

Embodiment 6.
When the traveling time of the automobile is short or when traveling in a cold region, the ambient temperature of the smoothing capacitor 13 may not rise to 50 ° C. or higher, which is suitable for repairing the aluminum oxide film. Therefore, in the sixth embodiment, the aluminum oxide film is repaired after the temperature is raised to a temperature at which the aluminum oxide film is efficiently repaired by installing a heater that raises the temperature around the smoothing capacitor 13.

FIG. 10 is a diagram showing the configuration of the power conversion device 49 of the sixth embodiment.
The power conversion device 49 of the sixth embodiment differs from the power conversion device 19 of the first embodiment in that the power conversion device 49 of the sixth embodiment includes a heater 25 that heats the periphery of the capacitor 13. The point is that the control device 47 is provided instead of the control device 17.

The heater 25 raises the temperature around the smoothing capacitor to a temperature at which the aluminum oxide film of the smoothing capacitor 13 is efficiently repaired. As the heater 25, a ceramic heater, a carbon heater, a sheathed heater, a Peltier element, or the like can be used. If the heater 25 is brought into direct contact with the smoothing capacitor 13, it may be damaged due to vibration during traveling or the like. Therefore, the heater 25 and the smoothing capacitor 13 are not brought into direct contact with each other. However, in order to efficiently heat the smoothing capacitor 13, the heater 25 is arranged as close as possible so as not to come into contact with it.

FIG. 11 is a flowchart showing a control procedure of the power conversion device 49 according to the sixth embodiment.

In step S60, when the operation of the power conversion device 49 is stopped due to the vehicle stopping, the process proceeds to step S61.

In step S61, the control device 47 maintains the on state of the switch 12 and continues the connection between the power source 11 and the smoothing capacitor 13.

In step S62, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S63, when the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1 (S63: YES), the process proceeds to step S64. When the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is less than the set temperature TH1 (S63: NO), the process proceeds to step S67. Here, TH1 is preferably 50 ° C. as in the first embodiment.

In step S64, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S65, when the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1 (S65: YES), the process returns to step S64. When the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is less than the set temperature TH1 (S65: NO), the process proceeds to step S66.

In step S66, the control device 47 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13, disconnects the power source 11 and the smoothing capacitor 13, and ends the control.

In steps S64 to S66, as in the first embodiment, after the power conversion device 49 is stopped, when the temperature TK of the smoothing capacitor 13 is equal to or higher than the set temperature TH1, smoothing is performed with the power source 11 until the temperature becomes lower than the set temperature TH1. It is connected to the capacitor 13.

On the other hand, when the temperature TK of the smoothing capacitor 13 is less than the set temperature TH1 after the power conversion device 49 is stopped, the power source 11 and the smoothing capacitor 13 are temporarily separated and the smoothing capacitor 13 is heated as shown below. The operation is performed.

In step S67, the control device 47 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13 to disconnect the power source 11 and the smoothing capacitor 13.

In step S68, the control device 47 turns on the heater 25 around the smoothing capacitor 13.

In step S69, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S70, when the control device 47 determines that the temperature TK of the smoothing capacitor 13 is less than the set temperature TH2 (S70: NO), the process returns to step S69. When the control device 47 determines that the temperature TK of the smoothing capacitor 13 is equal to or higher than the set temperature TH2 (S70: YES), the process proceeds to step S71. The reason why the set temperature TH1 of steps S63 and S65 is preferably 50 ° C. is that if the temperature becomes too high, the smoothing capacitor 13 deteriorates due to the evaporation of the electrolytic solution. In step S70 when the switch 12 is not turned on, the set temperature TH2 is preferably 75 ° C.

In step S71, the control device 47 turns on the switch 12 to connect the power source 11 and the smoothing capacitor 13. By disconnecting the power source 11 and the smoothing capacitor 13, heating the smoothing capacitor 13 with the heater 25, and then connecting the power source 11 and the smoothing capacitor 13, the aluminum oxide film can be efficiently repaired. Alternatively, in step S67, the smoothing capacitor 13 can be heated by the heater 25 without disconnecting the power source 11 and the smoothing capacitor 13.

In step S72, the control device 47 starts a timer for measuring the elapsed time since the switch 12 is turned on.

In step S73, when the control device 47 determines that the elapsed time from turning on the switch 12, which is the timer value of the timer, exceeds the set time TT2 (S73: YES), the process proceeds to step S74. When the control device 47 determines that the elapsed time from turning on the switch 12, which is the timer value of the timer, does not exceed the set time TT2 (S73: NO), step S73 is continued. Here, the set time TT2 is preferably 30 minutes in order to sufficiently repair the aluminum oxide film, as shown in FIG.

In step S74, the control device 47 turns off the heater 25 around the smoothing capacitor 13.

In step S75, the control device 47 turns off the switch 12 that connects the power source 11 and the smoothing capacitor 13 to disconnect the power source 11 and the smoothing capacitor 13.

According to this embodiment, even when the temperature of the smoothing capacitor is low due to the usage of the device and the surrounding environment, the temperature of the smoothing capacitor is raised by the heater to efficiently repair the aluminum oxide film. be able to. As a result, the life of the power conversion device can be extended.

Even when the power source 11 and the smoothing capacitor 13 are connected after the power conversion device is stopped by detecting the deterioration of the smoothing capacitor as described in the third and fourth embodiments, the temperature of the smoothing capacitor is the set temperature. If it is lower than TH1, the same effect can be obtained by heating the smoothing capacitor 13 with the heater 25 and then connecting the power source 11 and the smoothing capacitor 13.

Even when the external power supply 22 is connected and connected to the smoothing capacitor 13 as described in the fifth embodiment, if the temperature of the smoothing capacitor is low, the external power supply 22 is heated after being heated by the heater 25. The same effect can be obtained by connecting the smoothing capacitor 13 and the smoothing capacitor 13.

Embodiment 7.
In the first embodiment, after the power conversion device is stopped, when the temperature of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1, the connection between the power source 11 and the smoothing capacitor 13 is continued, and aluminum is used. The oxide film was repaired. However, immediately after the power conversion device is stopped, even if the temperature of the smoothing capacitor 13 is equal to or higher than the set temperature TH1, the ambient temperature of the smoothing capacitor 13 will be lowered immediately after the power conversion device is stopped. Depending on the operating status of the device, it may not be possible to take sufficient time to repair the aluminum oxide film. Therefore, in the seventh embodiment, in the power conversion device 49 shown in FIG. 10, by heating the smoothing capacitor 13 with the heater 25, the temperature of the smoothing capacitor 13 becomes equal to or higher than the set temperature TH1 so that the set time TT3 is exceeded. To. Thereby, the aluminum oxide film can be repaired more reliably.

More specifically, the control device 47 connects the smoothing capacitor 13 and the power source 11 after the operation of the power conversion device 49 is stopped, and exceeds a predetermined set time TT3 after the operation of the power conversion device 49 is stopped. When the temperature of the smoothing capacitor 13 detected by the temperature detector 15 becomes less than the predetermined set temperature TH1, the period during which the temperature 13 of the smoothing capacitor 13 becomes the set temperature TH1 or more is the set time TT3. The smoothing capacitor 13 is heated so as to exceed the level.

FIG. 12 is a flowchart showing a control procedure of the power conversion device 49 according to the seventh embodiment.

In step S81, when the operation of the power conversion device 49 is stopped due to the vehicle stopping, the process proceeds to step S82.

In step S82, the control device 47 maintains the on state of the switch 12 and continues the connection between the power source 11 and the smoothing capacitor 13.

In step S83, the control device 47 starts a timer for measuring the period during which the temperature TK of the smoothing capacitor 13 becomes the set temperature TH1 or higher.

In step S84, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S85, when the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1 (S85: YES), the process returns to step S84. When the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is less than the set temperature TH1 (S85: NO), the process proceeds to step S86. Here, TH1 is preferably 50 ° C. as in the first embodiment.

In step S86, the control device 47 suspends the timer for measuring the period during which the temperature TK of the smoothing capacitor 13 becomes the set temperature TH1 or higher.

In step S87, when the control device 47 determines that the period during which the temperature TK of the smoothing capacitor 13, which is the timer value of the timer, exceeds the set temperature TH1 exceeds the set time TT3 (S87: YES), the process steps. Proceed to S88. When the control device 47 determines that the period during which the temperature TK of the smoothing capacitor 13, which is the timer value of the timer, becomes the set temperature TH1 or higher does not exceed the set time TT3 (S87: NO), the process proceeds to step S89. move on.

In step S88, the control device 47 disconnects the power source 11 and the smoothing capacitor 13 by turning off the switch 12 that connects the power source 11 and the smoothing capacitor 13, and ends the control.

In step S89, the control device 47 turns off the heater 25 around the smoothing capacitor 13.

In step S90, the temperature detector 15 detects the temperature TK of the smoothing capacitor 13.

In step S91, when the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is equal to or higher than the set temperature TH1 (S91: YES), the process proceeds to step S92. When the control device 47 determines that the temperature TK of the smoothing capacitor 13 detected by the temperature detector 15 is less than the set temperature TH1 (S91: NO), the process returns to step S90.

In step S92, the control device 47 restarts the timer for measuring the period during which the temperature TK of the smoothing capacitor 13 becomes the set temperature TH1 or higher.

In step S93, when the control device 47 determines that the period during which the temperature TK of the smoothing capacitor 13, which is the timer value of the timer, exceeds the set temperature TH1 exceeds the set time TT3 (S93: YES), the process steps. Proceed to S94. If the control device 47 determines that the period during which the temperature TK of the smoothing capacitor 13, which is the timer value of the timer, is equal to or higher than the set temperature TH1 does not exceed the set time TT3 (S93: NO), step S93 is continued. To.

In step S94, the control device 47 turns off the heater 25 around the smoothing capacitor 13.

In step S95, the control device 47 disconnects the power source 11 and the smoothing capacitor 13 by turning off the switch 12 that connects the power source 11 and the smoothing capacitor 13, and ends the control.

According to this embodiment, even when the temperature of the smoothing capacitor is low depending on how the device is used and the surrounding environment, the temperature of the smoothing capacitor can be raised by the heater to efficiently repair the aluminum oxide film. .. As a result, the life of the power conversion device can be extended.

Even when the power source 11 and the smoothing capacitor 13 are connected after the power conversion device is stopped by detecting the deterioration of the smoothing capacitor as described in the third and fourth embodiments, the temperature of the smoothing capacitor is the set temperature. When it becomes lower than TH1, the smoothing capacitor 13 is heated by the heater 25, and the same effect can be obtained by connecting the power source 11 and the smoothing capacitor 13 for a set time while maintaining the set temperature TH1. Obtainable.

Embodiment 8.
In the sixth and seventh embodiments, a heater is installed to heat the smoothing capacitor in order to efficiently repair the aluminum oxide film of the smoothing capacitor. In the present embodiment, instead of installing the heater, the smoothing capacitor 13 is heated by passing an electric current through the smoothing capacitor 13 by using the windings of the smoothing capacitor 13 and the motor 18 under the control of the power conversion device 19 shown in FIG. Can be done.

In the eighth embodiment, the motor 18 uses a synchronous motor, which is particularly used as a motor for an electric vehicle. Vector control is used as the motor control. In vector control, motor control is performed separately for the torque axis (q-axis) and the excitation axis (d-axis). In this vector control, when a current is passed through the q-axis, the electric motor generates torque, but when it is passed through the d-axis, no torque is generated and the motor 18 does not rotate.

FIG. 13 is a diagram showing waveforms of the d-axis voltage Vd of the motor 18, the d-axis current Id of the motor 18, and the current Ic of the smoothing capacitor 13 in the eighth embodiment.

When heating the smoothing capacitor 13, the control device 17 turns on the switch 12 to connect the power source 11 and the smoothing capacitor 13. The control device 17 controls the switching elements 14a to 14f of the power conversion unit 14. The control device 17 adjusts the duty ratios of the switching elements 14a to 14f in order to generate a predetermined d-axis voltage Vd by switching the power conversion unit 14.

First, in T1, the control device 17 controls the switching elements 14a to 14f so that the H level d-axis voltage Vd is applied. By applying the H-level d-axis voltage Vd, the d-axis current Id flowing through the winding of the motor 18 increases with time. At this time, the energy stored in the smoothing capacitor 13 is discharged to the motor 18 side. Therefore, the current Ic of the smoothing capacitor 13 decreases with time.

Next, in T2, the control device 17 controls the switching elements 14a to 14f to apply the L-level d-axis voltage Vd. By applying the L-level d-axis voltage Vd, the d-axis current Id flowing through the winding of the motor 18 decreases with time. At this time, the energy returns to the smoothing capacitor 13. That is, since the smoothing capacitor 13 is charged, the current Ic of the smoothing capacitor 13 increases.

T3, T4 and later repeats the behavior of T 1, T2.
As described above, the switching elements 14a to 14f of the power conversion unit 14 are controlled, discharged from the smoothing capacitor 13, electric energy is stored in the winding of the motor 18, and then the energy stored in the motor 18 is stored in the smoothing capacitor. Return to 13 and repeat the charging operation. During the charging / discharging operation of the smoothing capacitor 13, heat is generated by the internal resistance of the smoothing capacitor 13, so that the smoothing capacitor 13 can be heated.

Further, if the temperature becomes too high, the smoothing capacitor 13 deteriorates due to the evaporation of the electrolytic solution. Therefore, the switching element 14a of the power conversion unit 14 so that the temperature of the smoothing capacitor 13 becomes 50 ° C. or higher and 75 ° C. or lower. It is desirable to control ~ 14f.

It is also possible to heat the smoothing capacitor in combination with the heating by the heater described in the sixth and seventh embodiments.

Since the heating of the smoothing capacitor 13 according to the eighth embodiment controls the current flowing in the d-axis where torque is not generated, it can be carried out even when the automobile is stopped.

The heating of the smoothing capacitor 13 is carried out when the device is stopped as in the sixth and seventh embodiments, and even when the temperature of the smoothing capacitor is low depending on how the device is used and the surrounding environment, the power converter and the power converter By using the winding of the motor, the temperature of the smoothing capacitor can be raised and the aluminum oxide film can be efficiently repaired. As a result, the life of the power conversion device can be extended.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the claims.

11 power sources, 12 switches, 13 smoothing capacitors, 14 power converters, 14a, 14b, 14c, 14d, 14e, 14f switching elements, 15 temperature detectors, 17, 27, 37 controllers, 18 motors, 19, 29, 39,49 Power converter, 20 voltage detector, 22 external power supply, 24 connection detector, 25 heater, 23 connection port, Da, Db, Dc, Dd, De, Df diode.

Claims (16)

It ’s a power converter,
A power converter that converts and outputs the power supplied from the power source,
A smoothing capacitor connected to the power converter
A switch for connecting or disconnecting the smoothing capacitor and the power source,
A detector that detects at least one of the temperature of the smoothing capacitor or the voltage across the smoothing capacitor.
A control device for controlling the switch after the operation of the power conversion device is stopped based on the data obtained from the detector is provided.
The smoothing capacitor is a power conversion device composed of an aluminum electrolytic capacitor or a hybrid aluminum electrolytic capacitor. The detector includes a temperature detector that measures the temperature of the smoothing capacitor.
The control device determines whether or not to connect the smoothing capacitor and the power source based on the data of the temperature detector, and controls the switch after the operation of the power conversion device is stopped according to the result of the determination. The power conversion device according to claim 1. In the control device, the smoothing capacitor and the power source are connected when the temperature of the smoothing capacitor detected by the temperature detector after the operation of the power conversion device is stopped is equal to or higher than a predetermined set temperature. When the temperature of the smoothing capacitor detected by the temperature detector after the operation of the power conversion device is stopped is lower than the set temperature, the smoothing capacitor and the power source are controlled. The power conversion device according to claim 2, wherein the switch is controlled so that the connection with the switch is cut off. When the temperature of the smoothing capacitor detected by the temperature detector at the start of operation of the power conversion device is within a predetermined setting range, the control device performs the temperature detector after the operation of the power conversion device is stopped. When the temperature of the smoothing capacitor detected in is equal to or higher than the set temperature, the switch is controlled so that the smoothing capacitor and the power source are connected, and after the operation of the power conversion device is stopped. The switch is controlled so that the connection between the smoothing capacitor and the power source is cut off when the temperature of the smoothing capacitor detected by the temperature detector is lower than the set temperature. 3. The power conversion device according to 3. When the temperature of the smoothing capacitor detected by the temperature detector at the start of operation of the power conversion device is out of the set range, the control device performs the smoothing capacitor and the power source after the operation of the power conversion device is stopped. The power conversion device according to claim 4, wherein the switch is controlled so that the connection with the switch is cut off. The detector includes a voltage detector that measures the voltage across the smoothing capacitor.
The control device determines whether or not to connect the smoothing capacitor and the power source based on the data of the voltage detector, and controls the switch after the operation of the power conversion device is stopped according to the result of the determination. The power conversion device according to claim 1. The detector further comprises a temperature detector that measures the temperature of the smoothing capacitor.
When the voltage fluctuation across the smoothing capacitor detected by the voltage detector during the operation of the power conversion device is equal to or larger than a predetermined set voltage width, the control device is used after the operation of the power conversion device is stopped. When the temperature of the smoothing capacitor detected by the temperature detector is equal to or higher than the set temperature, the switch is controlled so that the smoothing capacitor and the power source are connected to each other, and the power conversion device is used. When the temperature of the smoothing capacitor detected by the temperature detector after the operation is stopped is lower than the set temperature, the switch is controlled so that the connection between the smoothing capacitor and the power source is cut off. , The power conversion device according to claim 6. When the voltage fluctuation across the smoothing capacitor detected by the voltage detector during the operation of the power conversion device is less than the set voltage width, the control device and the smoothing capacitor are used after the operation of the power conversion device is stopped. The power conversion device according to claim 7, wherein the switch is controlled so that the connection with the power source is cut off. The detector further includes a temperature detector that measures the temperature of the smoothing capacitor.
When the charging time of the smoothing capacitor detected by the voltage detector at the time of starting the power conversion device is equal to or less than a predetermined set time, the control device has the temperature after the operation of the power conversion device is stopped. When the temperature of the smoothing capacitor detected by the detector is equal to or higher than the set temperature, the switch is controlled so that the smoothing capacitor and the power source are connected, and the operation of the power conversion device is stopped. When the temperature of the smoothing capacitor later detected by the temperature detector is lower than the set temperature, the switch is controlled so that the connection between the smoothing capacitor and the power source is cut off. Item 6. The power conversion device according to item 6. When the charging time of the smoothing capacitor detected by the voltage detector at the start of the power conversion device exceeds the set time, the control device causes the smoothing capacitor and the power source after the operation of the power conversion device is stopped. The power conversion device according to claim 9, wherein the switch is controlled so that the connection with the switch is cut off. The power converter
A connection detector that detects whether or not an external power supply is connected to the power converter, and
The control device turns on the switch to connect the external power supply and the power source to the smoothing capacitor when it is detected that the external power source is connected to the power conversion device. The power converter described. The detector includes a temperature detector that measures the temperature of the smoothing capacitor.
The control device connects the smoothing capacitor and the power source when the temperature of the smoothing capacitor detected by the temperature detector is less than a predetermined set temperature after the operation of the power conversion device is stopped. After shutting off and heating the smoothing capacitor until the temperature of the smoothing capacitor becomes equal to or higher than a predetermined set temperature, the switch is controlled so that the smoothing capacitor and the power source are connected. The power conversion device according to claim 1, wherein the connection between the smoothing capacitor and the power source is continued until a predetermined set time elapses. The detector includes a temperature detector that measures the temperature of the smoothing capacitor.
The control device connects the smoothing capacitor and the power source after the operation of the power conversion device is stopped, and the temperature detector is connected to the temperature detector after the operation of the power conversion device is stopped until a predetermined set time is exceeded. When the temperature of the smoothing capacitor detected in is less than a predetermined set temperature, the smoothing capacitor is heated so that the period during which the temperature of the smoothing capacitor becomes equal to or higher than the set temperature exceeds the set time. , The power conversion device according to claim 1. The power converter
The power conversion device according to claim 12 or 13, further comprising a heater for heating the smoothing capacitor. The power converter is connected to a motor and
The power conversion device according to claim 12 or 13, wherein the control device repeats charging and discharging between the smoothing capacitor and the winding of the motor in order to heat the smoothing capacitor. The power conversion device according to claim 15, wherein the control device charges and discharges between the smoothing capacitor and the winding of the motor by changing the d-axis voltage of the motor.

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