KR101323921B1 - Power conversion device and operating method thereof - Google Patents

Abstract

PURPOSE: A power conversion apparatus and an operating method thereof are provided to control a current flowing in an electrolytic condenser depending on the temperature of the electrolytic condenser, thereby improving the stability of the electrolytic condenser. CONSTITUTION: A method for operating a power conversion apparatus comprises the steps of: measuring the temperature of an electrolytic condenser (S601); comparing the measured temperature of the electrolytic condenser with a reference temperature (S602); outputting a first current if the measured temperature is within a reference temperature range (S603); and outputting a second current if the measured temperature is out of the reference temperature range (S605,S606). The second current is lower than the first current. [Reference numerals] (AA) Start; (BB) No; (CC) Yes; (DD) High temperature; (EE) End; (FF) Low temperature; (S601) Measure the temperature of an electrolytic condenser; (S602) Is the temperature out of a reference temperature range ?; (S603) Perform a normal action; (S604) Is the temperature low ?; (S605) Perform a first safe mode; (S606) Perform a second safe mode

Description

Power conversion device and its operation method {POWER CONVERSION DEVICE AND OPERATING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion device, and more particularly, to a power conversion device and a method of operating the same that can perform a stable operation even under a change in external environment.

Electric vehicles are cars that use batteries and electric motors without petroleum fuels and engines. Electric vehicles were first produced in 1873, but they were not put to practical use due to technical limitations such as heavy weight of batteries and charging time.

On the other hand, electric vehicles were produced in small quantities from the United States until the mid-1920s with advantages such as simple structure, durability, and easy operation. In recent years, regulations on exhaust emissions from vehicles have been rising due to environmental pollution (pollution) problems in the United States and Europe, and oil prices are soaring that electric vehicles are attracting attention as next-generation vehicles. In other words, electric vehicles using pollution-free electric energy are able to fundamentally solve environmental problems such as harmful exhaust gas and noise of internal combustion engines that occupy about 70% of air pollution factors, The resource life can be extended more than twice.

Accordingly, various technologies related to electric vehicles have been developed since 1990. In other words, automobile manufacturers are developing a variety of technologies to improve the relatively low battery capacity, long charge time, short travel distance, and slow running speed, which are technical problems of electric vehicles.

Recently, in order to overcome the long charging time which is one of the problems of electric vehicles, an interface part for a charging infrastructure for charging electric vehicles has been developed. The interface component for the electric vehicle charging infrastructure includes a charging interface module and a charging stand that connect the vehicle to an external power system and supply electric energy to the vehicle using electric power as an electric power source. The charging stand is a device that corresponds to the existing lubrication equipment, and includes a power control device and a charge monitoring device for linking the electric automobile with the commercial AC power system.

As such, the electrical equipment provided in the electric vehicle must maintain stability in order to operate even in sub-zero environments.

However, the electrolytic capacitor provided in the power factor correction circuit including the charger for an electric vehicle is greatly affected by temperature, and the temperature affects the operation stability of the electrolytic capacitor.

That is, the electrolytic capacitor has a characteristic of increasing an equivalent series resistance (ESR) at low temperatures, and as the equivalent series resistance increases, power loss increases and an allowable current ripple decreases.

However, in the past, a function for stabilizing an electrolytic capacitor at a low temperature has not been provided. Accordingly, since the stability of the electrolytic capacitor may be lowered at a low temperature, a method for improving the stability of the electrolytic capacitor at a low temperature is needed.
(Patent Document 1) KR1020010036564 A1
(Patent Document 2) KR1020090100575 A1

Embodiments according to the present invention provide a power conversion apparatus and an operation method thereof capable of performing a stable power conversion operation even at low temperatures.

In addition, an embodiment according to the present invention provides a power conversion device and an operation method thereof that can ensure the operational stability of the electrolytic capacitor included in the power conversion device.

It is to be understood that the technical objectives to be achieved by the embodiments are not limited to the technical matters mentioned above and that other technical subjects not mentioned are apparent to those skilled in the art to which the embodiments proposed from the following description belong, It can be understood.

An operating method of a power conversion apparatus according to an embodiment of the present invention includes the steps of measuring the temperature of the electrolytic capacitor for constant voltage output; Comparing the measured temperature with a preset reference temperature range; Outputting a first current through the power converter when the measured temperature is in the reference temperature range; And outputting a second current lower than the first current through the power converter when the measured temperature is out of the reference temperature range.

In addition, the power conversion apparatus according to an embodiment of the present invention converts AC power supplied from the outside into a DC power supply, a boost converter including a electrolytic capacitor for constant voltage output; A DC-DC converter connected to an output terminal of the boost converter and converting the DC power converted through the boost converter into DC power for battery charging; And a controller configured to measure a temperature of the electrolytic capacitor provided in the boost converter, and to control an output current of the DC-DC converter according to the measured temperature, wherein the controller is configured such that the temperature of the electrolytic capacitor is a reference temperature. If within the range, the reference current is output through the DC-DC converter, and if the temperature of the electrolytic capacitor is out of the reference temperature range, the current lower than the reference current is output through the DC-DC converter. .

According to the embodiment of the present invention, the stability of the electrolytic capacitor can be improved by controlling the current flowing through the capacitor according to the temperature. In other words, by increasing the temperature of the electrolytic capacitor at a low temperature, the equivalent series resistance is reduced, and the allowable current ripple is increased, so that the size of the electrolytic capacitor can be made compact while improving the stability of the electrolytic capacitor.

In addition, since a digital signal processor (DSP) is generally employed in power conversion circuits including automotive electronics, it can be easily implemented at no additional cost.

1 is a view showing a power conversion apparatus according to an embodiment of the present invention.
2 is a view showing operating characteristics for each temperature of the electrolytic capacitor C1 according to the embodiment of the present invention.
3 is a graph illustrating a tracking current value at low temperature according to the first embodiment of the present invention.
4 is a graph illustrating a tracking current value at low temperature according to the second embodiment of the present invention.
5 is a graph illustrating a tracking current value at a high temperature according to an exemplary embodiment of the present invention.
6 is a view for explaining a method of operating a power conversion apparatus according to an embodiment of the present invention.
FIG. 7 is a view for explaining a method of performing a first safe mode shown in FIG. 6.
FIG. 8 is a diagram for describing a method of performing a second safe mode shown in FIG. 6.

The following merely illustrates the principles of the invention. Thus, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. Furthermore, all of the conditional terms and embodiments listed herein are, in principle, only intended for the purpose of enabling understanding of the concepts of the present invention, and are not to be construed as limited to such specifically recited embodiments and conditions do.

It is also to be understood that the detailed description, as well as the principles, aspects and embodiments of the invention, as well as specific embodiments thereof, are intended to cover structural and functional equivalents thereof. It is also to be understood that such equivalents include all elements contemplated to perform the same function irrespective of the currently known equivalents as well as the equivalents to be developed in the future, i.e., the structure.

1 is a view showing a power conversion apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the power converter 100 may include an input rectifier 110, a boost converter 120, a DC-DC converter 130, a PWM output unit 140, a memory unit 150, and a controller ( 160).

The DC-DC converter 130 includes an inverter unit 132 and an output rectifier 134.

The input rectifier 110 is a full-bridge diode and rectifies the commercial AC power input through the power input terminal into a DC power source.

In particular, the input rectifier 110 converts the current by the counter electromotive force of the inductor coil L1 when the first switching element Q1 included in the boost converter 120 is turned off. 120 to the output side to increase the power conversion efficiency.

The boost converter 120 may also be referred to as a power factor corrector, and in addition to a boost function for outputting a boosted DC voltage, a function of correcting (improving) the power factor by creating an input current having a phase such as an output voltage and an input voltage Has

The boost converter 120 receives the rectified DC power through the input rectifier 110 and boosts the voltage from the input DC power to provide the first switching element Q1 and the inductor coil. (L1) and electrolytic capacitor C1 are included.

Producing an input current having the same phase as the output voltage and the input voltage of the boost converter 120 is controlled by the PWM output unit 140 that controls the switching operation of the first switching element Q1, that is, the PWM output. The PWM signal output through the unit 140 may be achieved.

The electrolytic capacitor C1 is a constant voltage output capacitor for keeping the DC output voltage of the boost converter 120 constant and outputting the same by the charging voltage thereof.

The step-up converter 120 is connected to the first switching element (Q1) to prevent the reversal of the diode, the diode (D1) also allows the current flow to the electrolytic capacitor (C1) side and the reverse to allow the current flow to the contrary It is connected to the output terminal of the 1st switching element Q1.

The DC-DC converter 130 is connected to the output terminal of the boost converter 120.

The DC-DC converter 130 includes an inverter unit 132, a transformer Tr, and an output rectifier 134.

The inverter unit 132 converts the direct current from the boost converter 120 into alternating current and has a plurality of second switching elements. The second switching element may be a semiconductor switch that is turned on or off by a gate control, and may be formed of, for example, a Silicon Coupled Rectifier (SCR) or an Insulated Gate Bipolar Transistor (IGBT) . The body diode connected in parallel to each of the second switching elements constituting the inverter unit 132 is a reversal prevention diode for disallowing current flow flowing in reverse from the output side of the inverter unit 132 to the second switching element side. .

The switching control of the second switching element of the inverter unit 132 is controlled by the PWM output unit 140 which constantly controls the final output voltage and the final output current output to the driving battery B for the electric vehicle, That is, the pulse width modulation signal PWM output by the PWM output unit 140 may be achieved.

The transformer Tr is connected to the inverter unit 132 to transfer AC power to the output rectifier 134.

The output rectifier 134 is connected to an output terminal (ie, a secondary winding) of the transformer Tr, converts AC power transmitted through the transformer Tr into DC power, and converts the converted DC power into an electric vehicle battery. That is, DC power for charging is supplied to the battery for driving the electric vehicle.

The electric vehicle power converter according to the present invention further includes a PWM output unit 140, a memory unit 150, and a controller 160 as shown in FIG. 1.

The PWM output unit 140 performs control of the first switching element included in the boost converter 120 and the second switching element included in the inverter unit 132.

In this case, the PWM output unit 140 uses the following current according to the reference current provided through the controller 160 to be described later so that the output current of the DC-DC converter 130 follows the following current. The operation of the switching element and the second switching element is controlled.

The memory unit 150 stores various information necessary for controlling the switching operation of the first and second switching elements. The memory unit 150 may be implemented as a RAM or an ROM.

Meanwhile, although the memory unit 150 is illustrated separately from the control unit 160 in the drawing, this is only an example and the memory unit 150 may be included in the control unit 160.

Information stored in the memory unit 150 stores operating condition information of the boost converter 120 according to the temperature of the electrolytic capacitor C1 included in the boost converter 120.

The operating condition information is based on the temperature of the boost converter 120, precisely the output current of the DC-DC converter 130 according to the temperature of the electrolytic capacitor (C1) included in the boost converter 120. The table for adjustment is stored.

The controller 160 measures the temperature of the electrolytic capacitor C1 and adjusts the output current of the DC-DC converter 130 according to the measured temperature. More specifically, the controller 160 provides the tracking current value according to the reference current to the PWM output unit 140 so that the output current is adjusted according to the measured temperature.

2 is a view showing operating characteristics for each temperature of the electrolytic capacitor C1 according to the embodiment of the present invention.

The operating characteristics of the electrolytic capacitor C1 change with temperature. In other words, the electrolytic capacitor C1 at low temperature is significantly increased in ESR than when operating at room temperature or high temperature. In addition, the electrolytic capacitor C1 at low temperature also exhibits a characteristic that its allowable ripple current is also reduced.

In addition, operation stability of the electrolytic capacitor C1 at high temperature may decrease due to an increase in temperature.

Accordingly, the controller 160 outputs a control signal to the PWM output unit 140 so that the electrolytic capacitor C1 always operates at a reference temperature (room temperature), thereby outputting the DC-DC converter 130. Allow the current to be regulated.

The output current of the DC-DC converter 130 affects the temperature of the electrolytic capacitor C1. That is, when the output current of the DC-DC converter 130 decreases from A to B (A> B), the temperature of the electrolytic capacitor C1 decreases.

In addition, when the DC-DC converter 130 starts to operate in a non-operating state, the electrolytic capacitor C1 generates self-heating, thereby increasing the temperature of the electrolytic capacitor C1.

Therefore, in the present invention, the output current of the DC-DC converter 130 is appropriately adjusted according to the temperature of the electrolytic capacitor C1 by using the above characteristics.

To this end, the controller 160 measures the temperature of the electrolytic capacitor C1. After that, when the measured temperature of the electrolytic capacitor C1 belongs to the reference temperature (room temperature), the controller 160 outputs the following current value corresponding to the reference current to the PWM output unit 140. The PWM output unit 140 controls the switching operation of the first switching element and the second switching element using the following current value. That is, the PWM output unit 140 controls the first and second switching elements such that the same current as the reference current is output through the DC-DC converter 130 using the following current value.

However, when the temperature of the measured electrolytic capacitor C1 is lower than the reference temperature, the controller 160 provides the PWM output unit 140 with a tracking current value lower than the reference current, thereby providing the DC current. The output current lower than the reference current is generated through the DC converter 130.

That is, when an output current corresponding to the reference current is generated through the DC-DC converter 130 in a state where the electrolytic capacitor C1 is at a low temperature, stress occurs in the electrolytic capacitor C1, and the electrolysis An abnormality occurs in the operational stability of the capacitor C1.

Accordingly, when the measured temperature is low, the control unit 160 generates an output current lower than the reference current through the DC-DC converter 130. Accordingly, the controller 160 provides a tracking current value lower than the reference current to the PWM output unit 140 so that an output current lower than the reference current is generated through the DC-DC converter 130.

The following current value may refer to a table stored in the memory unit 150. That is, the table stored in the memory unit 150 includes a tracking current value corresponding to an output current generated by the DC-DC converter 130 based on the heat generation degree according to the temperature of the electrolytic capacitor C1. .

In this case, the controller 160 divides the range between the measured temperature of the electrolytic capacitor C1 and the reference temperature into predetermined sections, and outputs different following current values for each of the divided sections.

3 is a graph illustrating a tracking current value at low temperature according to the first embodiment of the present invention.

Referring to FIG. 3, when the currently measured temperature is a and the reference temperature is b, the controller 160 divides the temperature range between the a and b into three sections. The three sections may be 1T, 2T, and 3T shown in FIG. 3.

For example, when the reference temperature is 30 degrees and the current measured temperature is -15 degrees, the divided 1T is -15 degrees to 0 degrees, the 2T is 0 degrees to 15 degrees, and the 3T is 15 degrees to 30 degrees.

The controller 160 outputs a first following current value A in the 1T section, a second following current value B in the 2T section, and a third following in the 3T section. The current value C is output, and in the 4T section including the reference temperature, the fourth following current value D corresponding to the reference current is output.

In this case, when the output current of the DC-DC converter 130 according to the first to fourth following current values is the first to fourth output currents, the fourth output current is the same as the reference current. The third output current is smaller than the fourth output current, the second output current is smaller than the third and fourth output currents, and the first output current is smaller than the second, third and fourth output currents.

In conclusion, when the temperature of the electrolytic capacitor C1 is low, the controller 160 outputs a tracking current value so that an output current lower than a reference current is generated, and the electrolytic capacitor C1 is output based on the output tracking current value. When the temperature of) increases, the following current value is gradually increased, and finally, the following current value for outputting the same output current as the reference current is output.

4 is a graph illustrating a tracking current value at low temperature according to the second embodiment of the present invention.

Referring to FIG. 4, when the temperature of the electrolytic capacitor C1 is lower than the reference temperature, the controller 160 causes the output current lower than the reference current to be generated in the DC-DC converter 130. Determine the following current value.

Thereafter, the controller 160 gradually increases the determined following current value with time, and finally outputs a following current value for generating an output current equal to the reference current.

Meanwhile, when the temperature of the measured electrolytic capacitor C1 is higher than the reference temperature, the controller 160 controls the controller 160 to reduce the temperature of the electrolytic capacitor C1 to the reference temperature. The output current of the DC-DC converter 130 is reduced.

That is, when the temperature of the electrolytic capacitor C1 is high, the controller 160 outputs a tracking current value for generating an output current lower than a reference current in order to reduce the output current.

Thereafter, when the temperature of the electrolytic capacitor C1 decreases to the reference temperature by the output following current value, the controller 160 changes the following current value to generate an output current corresponding to the reference current. .

5 is a graph illustrating a tracking current value at a high temperature according to an exemplary embodiment of the present invention.

Referring to FIG. 5, when the temperature of the electrolytic capacitor C1 is a high temperature, the controller 160 outputs a tracking current value for generating an output current lower than a reference current.

Subsequently, the controller 160 maintains the output following current value. When the temperature of the electrolytic capacitor C1 decreases to the reference temperature by the output following current value, the output current corresponding to the reference current is decreased. The following current value is output for generation.

According to the embodiment of the present invention, the stability of the electrolytic capacitor can be improved by controlling the current flowing through the capacitor according to the temperature. In other words, by increasing the temperature of the electrolytic capacitor at a low temperature, the equivalent series resistance is reduced, and the allowable current ripple is increased, so that the size of the electrolytic capacitor can be made compact while improving the stability of the electrolytic capacitor.

In addition, since a digital signal processor (DSP) is generally employed in power conversion circuits including automotive electronics, it can be easily implemented at no additional cost.

6 is a view for explaining a method of operating a power conversion apparatus according to an embodiment of the present invention, FIG. 7 is a view for explaining a method of performing a first safe mode shown in FIG. 6, and FIG. 8 is shown in FIG. 6. A diagram for describing a method of performing a second safe mode.

Referring to FIG. 6, first, the temperature of the electrolytic capacitor C1 is measured (step 601).

Thereafter, the measured temperature of the electrolytic capacitor C1 is compared with the reference temperature, and accordingly, it is determined whether the temperature of the electrolytic capacitor C1 is out of the range of the reference temperature (step 602).

As a result of the determination (step 602), if the temperature of the electrolytic capacitor (C1) falls within the reference temperature range, the normal operation is performed (step 603). That is, the follow-up current value for generating an output current corresponding to the reference current is output through the DC-DC converter 130.

However, when the determination result (step 602), the temperature of the electrolytic capacitor (C1) is out of the reference temperature range, it is determined whether the temperature of the electrolytic capacitor (C1) is lower than the reference temperature (low temperature) (step 604) ).

If the determination result (step 604), the temperature of the electrolytic capacitor (C1) is lower than the reference temperature, the first safety mode is performed (step 605). That is, it enters the low temperature derating mode.

In operation 604, when the temperature of the electrolytic capacitor C1 is higher than the reference temperature (high temperature), the second safety mode is performed (step 606). That is, it enters the high temperature derating mode.

Hereinafter, the first and second safety modes will be described in more detail.

Referring to FIG. 7, first, when the temperature of the electrolytic capacitor C1 is lower than the reference temperature, the heating condition according to the temperature of the measured electrolytic capacitor C1 is checked (step 701). The heat generation condition may be checked through a table stored in the memory unit 150.

Thereafter, an estimated current value for outputting a current lower than the reference current is generated according to the checked heating condition (step 702).

Prior to this, the temperature section between the measured temperature of the electrolytic capacitor C1 and the reference temperature is divided into a plurality of sections. In this case, a case where the section is divided into two will be described as an example.

As the sections are divided into two, firstly, the estimated current values checked according to the heating conditions are output to the first sections.

Thereafter, the temperature of the electrolytic capacitor C1 that changes according to the output estimated current value is measured (step 703).

It is determined whether or not the temperature of the measured electrolytic capacitor C1 has risen (step 704). That is, it is determined whether the temperature of the electrolytic capacitor C1 has risen to a temperature corresponding to the second section.

Thereafter, if the temperature of the electrolytic capacitor C1 has risen (step 704), it is determined whether the temperature rises within the reference temperature range (step 705).

As a result of the determination (step 705), if the elevated temperature does not belong to the reference temperature range (low temperature), the applied following current value is increased. In this case, the increased following current value is smaller than the following current value corresponding to the reference current.

On the other hand, if it is determined in step 705 that the elevated temperature is within the reference temperature range, the applied following current value is increased to a following current value for generating an output current corresponding to the reference current (step 707). .

Thereafter, the power conversion apparatus is normally operated based on the increased following current value (step 708).

In addition, referring to FIG. 8, if the temperature of the electrolytic capacitor C1 is a high temperature condition higher than the reference temperature, the cooling condition according to the temperature of the electrolytic capacitor C1 is checked. The cooling condition may include a tracking current value and application time information for reducing the temperature to a reference temperature according to the temperature of the electrolytic capacitor C1.

Thereafter, a tracking current value for reducing the temperature of the electrolytic capacitor C1 is output according to the checked cooling condition (step 802). The following current value is a value for generating an output current lower than a preset reference temperature.

When the output following current value is applied, the temperature of the electrolytic capacitor C1 is measured again (step 803).

Thereafter, it is determined whether the temperature of the re-measured electrolytic capacitor C1 is within a reference temperature range (step 805).

As a result of the determination (step 805), if the temperature of the re-measured electrolytic capacitor (C1) does not fall within the reference temperature range, after waiting for a predetermined time (step 804), the process returns to the step (803).

On the other hand, if the determination result (step 805), the temperature of the re-measured electrolytic capacitor (C1) falls within the reference temperature range, the following current value corresponding to the reference current is output (step 806).

Thereafter, the power conversion apparatus is normally operated according to the output estimated current value (step 807).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

110: input rectifier
120: boost converter
130: DC-DC converter
140: PWM output section
150:
160:

Claims (14)

In the operation method of the power converter,
Measuring the temperature of the electrolytic capacitor for constant voltage output;
Comparing the measured temperature with a preset reference temperature range;
Outputting a first current through the power converter when the measured temperature is in the reference temperature range; And
And outputting a second current lower than the first current through the power converter, when the measured temperature is out of the reference temperature range. The method of claim 1,
The first current is a preset reference current,
And the second current is a current lower than the set reference current. 3. The method of claim 2,
The outputting of the second current may include:
Generating a following current value for causing the second current to be output. The method of claim 3,
The generating of the following current value may include:
And sequentially generating a plurality of following current values for gradually increasing the output second current when the measured temperature is a low temperature outside the reference temperature range. 5. The method of claim 4,
The generating of the plurality of following current values may include:
Generating a first following current value for outputting the second current;
Generating a second following current value for generating a third current higher than the second current;
Generating a third following current value for generating the first current higher than the third current. 6. The method of claim 5,
The second following current value is generated when the temperature of the electrolytic capacitor increases by a certain level by the first following current value.
And the third following current value is generated when the temperature of the electrolytic capacitor falls within the reference temperature range by the second following current value. 6. The method of claim 5,
The second following current value is generated after a predetermined time from the time when the first following current value occurs,
And the third following current value is generated after the set time from the time when the second following current value occurs. 5. The method of claim 4,
The following current value is,
Operating method of the power conversion device is determined based on the heating conditions for each temperature of the electrolytic capacitor. The method of claim 3,
The generating of the following current value may include:
Generating a tracking current value for generating a second current lower than the reference current according to a cooling condition for each temperature of the electrolytic capacitor, when the measured temperature is a high temperature outside the reference temperature range. How it works. The method of claim 9,
And generating a following current value for outputting a first current corresponding to the reference current when the temperature of the electrolytic capacitor is reduced within the reference temperature range by the generated following current value. Way. A boost converter converting AC power supplied from the outside into DC power and including an electrolytic capacitor for constant voltage output;
A DC-DC converter connected to an output terminal of the boost converter and converting the DC power converted through the boost converter into DC power for battery charging; And
It includes a control unit for measuring the temperature of the electrolytic capacitor provided in the boost converter, and controls the output current of the DC-DC converter in accordance with the measured temperature,
The control unit,
When the temperature of the electrolytic capacitor falls within the reference temperature range, the reference current is output through the DC-DC converter,
And a current lower than the reference current is output through the DC-DC converter when the temperature of the electrolytic capacitor is out of the reference temperature range. 12. The method of claim 11,
The following current value is,
And a memory unit which stores information of any one of temperature-specific heating conditions and cooling conditions of the electrolytic capacitor. 13. The method of claim 12,
The control unit,
When the measured temperature is a low temperature outside the reference temperature range, a plurality of following current values for generating a current lower than a reference current are sequentially output using the heating condition,
The change point of the plurality of following current values is
And a power conversion device that is determined by any one of a temperature of an electrolytic capacitor that changes according to the output of the following current value and an elapsed time from the time point at which the following current value is applied. 13. The method of claim 12,
The control unit,
If the measured temperature is a high temperature outside the reference temperature range, a tracking current value for generating a second current lower than the reference current until the time when the temperature of the electrolytic capacitor decreases within the reference temperature range according to the cooling condition is determined. Power converter outputting.

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