JP7418674B1 - power conversion system - Google Patents

Abstract

A power conversion system (1A) includes a power conversion device connected between a power source (4) and a motor (5) to convert power, and noise information corresponding to noise current of switching noise generated by the power conversion device. a noise information detection device (20) that detects a damping variable resistor (25) that reduces a noise current, and a damping variable resistor (25) that is connected to a main power line and a damping resistor that are connected to a power converter. detects at least one of temperature information (31) and current information (32) of the damping resistor, which changes in accordance with changes in the common mode choke coil (3) and the damping resistor connection wire (22) passed through the damping resistor connection wire (22). The power conversion device determines whether the noise level of the noise current is greater than a reference value based on noise information including at least one of temperature information and current information, and determines whether the noise level is greater than a reference value. If it is larger than the reference value, the switching carrier frequency is lowered.

Description

The present disclosure relates to a power conversion system that performs power conversion using switching elements.

Power conversion devices such as inverters and converters switch at high speed and therefore generate switching noise. This switching noise increases in proportion to the switching carrier frequency, which is the frequency of the signal that controls switching between on and off of the switching element.

In order to deal with switching noise, suppliers of power conversion devices generally measure the noise level according to the switching carrier frequency in advance and disclose the measurement results. As a result, in the equipment where the power converter is installed, measures are taken according to the measurement results. However, common mode noise, which propagates through the ground in particular, greatly depends on the surrounding environment in which the power converter is installed, such as the grounding condition of the power supply, whether or not a shielded cable is used, and the stray capacitance of the motor. There may be a discrepancy between the level value and the noise level value measured at the supplier. Furthermore, in order to measure the actual noise level of switching noise, it is necessary to use a dedicated measuring instrument, and it is not easy to measure. As a result, countermeasures are often delayed, as countermeasures are considered only after problems due to switching noise, such as malfunctions in peripheral equipment, occur. If a problem occurs after the equipment is in operation, it can lead to large losses. Put it away. Therefore, it is desired to reduce switching noise in power converters.

The elevator control device described in Patent Document 1 includes: a common mode reactor connected in series with a power conversion device between a power source and a motor; a magnetic saturation suppression coil wound around a magnetic material of the common mode reactor; A magnetic saturation suppressing resistor is provided adjacent to the magnetic saturation suppressing coil. This elevator control device determines whether or not the magnetic material is magnetically saturated based on the elevator operation pattern, and if it is determined that the magnetic material is magnetically saturated, it installs a magnetic saturation suppression coil and a magnetic saturation suppression resistor. By connecting them to form a closed circuit and preventing magnetic saturation, the noise reduction effect is maintained.

Japanese Patent Application Publication No. 2010-104200

However, with the technology of Patent Document 1, it is necessary to measure a large number of experimental values in advance as magnetic saturation conditions used to determine whether or not magnetic saturation occurs for each piece of equipment in which an elevator control device is installed. There is a problem in that it takes time and effort to reduce switching noise.

The present disclosure has been made in view of the above, and aims to provide a power conversion system that can easily reduce switching noise.

In order to solve the above-mentioned problems and achieve the objectives, the power conversion system of the present disclosure includes a power conversion device that is connected between a power source and a motor to convert power, and a switching noise generated by the power conversion device. and a noise information detection device that detects noise information that is information corresponding to the noise current. The noise information detection device includes a damping resistor that reduces noise current, and a common mode choke coil through which a main power line connected to the power converter is passed and an electric wire connected to the damping resistor is passed. Further, the noise information detection device includes a sensor that detects at least one of temperature information, which is information about the temperature of the damping resistor, and current information, which is information about the current flowing through the damping resistor, which changes according to a change in the noise current. The power conversion device receives noise information including at least one of temperature information and current information from the noise information detection device, and determines whether the noise level of the noise current is larger than a reference value based on the noise information. However, if the noise level is higher than the reference value, the switching carrier frequency is lowered.

The power conversion system according to the present disclosure has the effect that switching noise can be easily reduced.

A diagram showing a first configuration example of a power conversion system according to an embodiment. A diagram showing a second configuration example of the power conversion system according to the embodiment Flowchart showing the processing procedure of the process executed by the power conversion system according to the embodiment A diagram for explaining processing when the power conversion system according to the embodiment lowers the switching carrier frequency before noise information reaches the noise determination value. A diagram showing an example of a hardware configuration for realizing a control unit according to an embodiment.

Below, a power conversion system according to an embodiment of the present disclosure will be described in detail based on the drawings.

Embodiment.
FIG. 1 is a diagram showing a first configuration example of a power conversion system according to an embodiment. The power conversion system 1A is a system that performs power conversion using switching elements. The power conversion system 1A uses power from the power source 4 to drive the motor 5, automatically detects switching noise, and automatically reduces the switching noise. The power conversion system 1A includes a semiconductor power conversion device 10, a noise information detection device 20, an input power wire 6 that is a main power line for all three phases, and an output power wire 7 that is a main power line for all three phases. We are prepared.

The power conversion system 1A is connected to a power source 4 and a motor 5. The power conversion system 1A is a system in which a damping variable resistor 25 is mounted on the power supply 4 side (primary side). That is, in the power conversion system 1A, the noise information detection device 20 having the damping variable resistor 25 is a power conversion device having the power source 4 and a PWM (Pulse Width Modulation) converter (not shown). It is connected between the semiconductor power conversion device 10 and the semiconductor power conversion device 10 .

The semiconductor power conversion device 10 is a device that is connected between a power source 4 and a motor 5 and converts power. The semiconductor power conversion device 10 is connected to a power source 4 via an input power wire 6 and to a motor 5 via an output power wire 7.

The noise information detection device 20 detects noise information that is information corresponding to switching noise generated by the semiconductor power conversion device 10. The noise information detection device 20 includes a common mode choke coil 3, a damping variable resistor 25, a temperature sensor 21, a current sensor 8, a damping resistor connection line 22, a temperature sensor connection line 23, and a current sensor connection line 24. have. The damping resistance connection line 22, the temperature sensor connection line 23, and the current sensor connection line 24 are electric wires. The noise information detection device 20 of the embodiment detects noise information using the damping variable resistor 25.

The common mode choke coil 3 is arranged on the input power wire 6. In the common mode choke coil 3, an input power wire 6 and a damping resistance connection line 22 connected to a damping variable resistance 25 are passed through the center of the cylindrical portion.

The damping variable resistor 25 is a resistor that reduces noise current of switching noise by attenuating vibration, and is connected to the damping resistor connection line 22. The damping resistance connecting line 22 extends from one end of the damping variable resistance 25 , passes through the annular interior of the annular common mode choke coil 3 , and is connected to the other end of the damping variable resistance 25 . A current sensor 8 is connected to the damping resistor connection line 22 .

The damping variable resistor 25 is a resistor whose resistance value can be changed. That is, the resistance value of the damping variable resistor 25 is variable depending on the user of the power conversion system 1A. Therefore, the power conversion system 1A can easily adjust the degree of noise reduction.

The current sensor 8 measures the current flowing through the damping resistor connection line 22 (hereinafter sometimes referred to as damping circuit current). Current sensor 8 is connected to semiconductor power conversion device 10 via current sensor connection line 24 . Current sensor 8 transmits current information 32 indicating the measurement result of the current flowing through damping resistor connection line 22 to semiconductor power conversion device 10 via current sensor connection line 24 .

Further, a temperature sensor 21 is arranged on the damping variable resistor 25 . The temperature sensor 21 measures the temperature of the damping variable resistor 25 (hereinafter sometimes referred to as damping resistance temperature). Temperature sensor 21 is connected to semiconductor power conversion device 10 via temperature sensor connection line 23 . The temperature sensor 21 transmits temperature information 31 indicating the measurement result of the temperature of the damping variable resistor 25 to the semiconductor power conversion device 10 via the temperature sensor connection line 23.

The semiconductor power conversion device 10 includes a storage section 11, a control section 12, a PWM generation section 13, and a semiconductor power conversion section 14. The storage section 11, the control section 12, the PWM generation section 13, and the semiconductor power conversion section 14 are configured using semiconductor elements.

The storage unit 11 stores an error history 33 indicating a history of errors that have occurred in the power conversion system 1A. The error history 33 includes information on whether or not an error has occurred, the history of the damping resistance temperature when the error occurred, the damping circuit current, and the like. Further, the error history 33 may include information such as the rate of increase in damping resistance temperature, the rate of increase in damping circuit current, and the number of times errors occur when errors occur.

The control unit 12 receives temperature information 31 from the temperature sensor 21 of the noise information detection device 20 . Further, the control unit 12 receives current information 32 from the current sensor 8 of the noise information detection device 20. Information including at least one of temperature information 31 and current information 32 is noise information. The control unit 12 also reads out the error history 33 from the storage unit 11.

The control unit 12 generates a frequency command (hereinafter referred to as fc command 34), which is a command specifying a switching carrier frequency, based on at least one of the temperature information 31 and the current information 32. The switching carrier frequency is the frequency of a signal that controls switching between on and off of a switching element. Further, the control unit 12 may generate the fc command 34 by referring to the error history 33.

When the damping resistance temperature indicated by the temperature information 31 is higher than the temperature threshold, the control unit 12 generates an fc command 34 indicating a switching carrier frequency lower than the current switching carrier frequency. Further, when the damping circuit current indicated by the current information 32 is higher than the current threshold value, the control unit 12 generates an fc command 34 indicating a switching carrier frequency lower than the current switching carrier frequency.

Furthermore, the control unit 12 predicts whether or not an error will occur thereafter, based on at least one of the temperature information 31 and the current information 32, and the error history 33. If the control unit 12 determines that an error will occur thereafter, it generates an fc command 34 indicating a switching carrier frequency lower than the current switching carrier frequency. The control unit 12 transmits the generated fc command 34 to the PWM generation unit 13.

The PWM generation unit 13 generates a PWM signal based on the fc command 34. The PWM signal is, for example, a signal for controlling a PWM converter (not shown) included in the semiconductor power conversion section 14. PWM generation section 13 transmits the PWM signal to semiconductor power conversion section 14 .

The semiconductor power converter 14 includes a PWM converter, an inverter (not shown), and the like, and converts the power sent from the power source 4. In the semiconductor power converter 14, the PWM converter converts the AC power sent from the power source 4 into DC power based on the PWM signal. Further, in the semiconductor power converter 14, an inverter converts DC power into AC power to drive the motor 5.

In this way, in the power conversion system 1A in which the damping variable resistor 25 is connected to the PWM converter and the power source 4, the power source 4 and the semiconductor power conversion device 10 are connected via the input power wire 6, and the semiconductor power conversion device 10 is connected to the power source 4 through the input power wire 6. and motor 5 are connected via an output power wire 7. A common mode choke coil 3 is disposed on the input power wire 6, a damping resistance connection line 22 is connected to the common mode choke coil 3 in a non-contact manner, and a damping variable resistance 25 is connected to the damping resistance connection line 22. It is connected. Further, a temperature sensor 21 is arranged near the damping variable resistor 25, and the temperature sensor 21 is connected to the semiconductor power conversion device 10 via a temperature sensor connection line 23.

In the power conversion system 1A, the resistance connected to the damping resistance connection line 22 passing through the common mode choke coil 3 is a damping variable resistance 25, and the resistance value is variable. As a result, for the power conversion system 1A, it is possible to select a resistance value regardless of the amount of noise in the power conversion system 1A, and it is also possible to consume power by the damping variable resistor 25. It also becomes easy to select the current sensor 8 to be connected in series with the current sensor 8. In addition, in the power conversion system 1A, when it is desired to change the resistance value according to the capacity of the inverter, the size of the equipment in which the power conversion system 1A is installed, etc., the damping variable resistor 25 is used, so that the resistance value can be easily changed. can be changed.

As described above, the damping resistance connection line 22 connected to the damping variable resistance 25 is passed through the common mode choke coil 3 together with the input power wire 6 which is the main power line for all three phases. In the power conversion system 1A, when a noise current flows through the input power wire 6, a current proportional to the noise current also flows through the damping variable resistor 25 due to the induced electromotive force of the common mode choke coil 3, and the damping variable resistor 25 reduces the noise current. is consumed, and the temperature of the damping variable resistor 25 rises.

The damping variable resistor 25 generates heat in proportion to the noise current flowing through the damping variable resistor 25. That is, the noise current flowing through the damping variable resistor 25 and the amount of heat generated by the damping variable resistor 25 are in a proportional relationship. Therefore, the control unit 12 can determine the noise level of the noise current based on the temperature of the damping variable resistor 25 (damping resistance temperature) corresponding to the amount of heat generated by the damping variable resistor 25. The control unit 12 of the embodiment determines that the noise level is greater than the reference value when the temperature of the damping variable resistor 25 measured by the temperature sensor 21 exceeds the temperature threshold.

Further, since a current proportional to the noise current flows through the damping variable resistor 25, the control unit 12 determines the noise level of the noise current based on the current flowing through the damping variable resistor 25 (damping circuit current) measured by the current sensor 8. level can be determined. The control unit 12 of the embodiment may determine that the noise level is greater than the reference value if the current measured by the current sensor 8 exceeds the current threshold.

When the control unit 12 determines that the noise level is higher than the reference value, the semiconductor power conversion device 10 performs switching to reduce the switching carrier frequency in order to lower the noise level. Specifically, when the control unit 12 determines that the noise level is higher than the reference value, it generates the fc command 34 indicating a switching carrier frequency lower than the current switching carrier frequency.

The control unit 12 generates, for example, an fc command 34 indicating a switching carrier frequency that is lower than the current switching carrier frequency by a specific value. Further, the control unit 12 may generate, for example, an fc command 34 indicating a switching carrier frequency that is lower than the current switching carrier frequency by a specific percentage. The control unit 12 transmits the generated fc command 34 to the PWM generation unit 13.

Thereby, the PWM generation section 13 generates a PWM signal corresponding to the fc command 34 and transmits it to the semiconductor power conversion section 14. In the semiconductor power converter 14, the PWM converter converts the AC power sent from the power source 4 into DC power based on the PWM signal, and the inverter converts the DC power into AC power to drive the motor 5. .

In this way, the power conversion system 1A lowers the switching carrier frequency when determining that the noise level is higher than the reference value based on at least one of the temperature measured by the temperature sensor 21 and the current measured by the current sensor 8. Switching noise can be easily reduced.

Further, in the power conversion system 1A, noise current can be consumed by the damping variable resistor 25, so switching noise can be reduced, and efficient system operation is possible.

The power conversion system 1A may determine whether the noise level is greater than the reference value based on both the feedback value from the temperature sensor 21 and the feedback value from the current sensor 8. That is, the control unit 12 may determine whether the noise level is greater than the reference value based on both the temperature measured by the temperature sensor 21 and the current measured by the current sensor 8. Thereby, the control unit 12 can accurately determine whether the noise level is higher than the reference value.

For example, when the damping resistance temperature, which is the temperature measured by the temperature sensor 21, is higher than the temperature threshold, and the damping circuit current, which is the current measured by the current sensor 8, is higher than the current threshold, the control unit 12 adjusts the noise level. is determined to be larger than the reference value.

Further, the control unit 12 may determine that the noise level is higher than the reference value when the damping resistance temperature is higher than the temperature threshold or the damping circuit current is higher than the current threshold.

In the embodiment, the noise information detection device 20 has been described as having both the temperature sensor 21 and the current sensor 8, but the power conversion system 1A only needs to be able to detect the noise level using the damping variable resistor 25. Therefore, it is sufficient to include at least one of the temperature sensor 21 and the current sensor 8.

In this way, the control unit 12 determines whether the noise level is greater than the reference value based on at least one of the temperature measured by the temperature sensor 21 and the current measured by the current sensor 8.

In this way, the power conversion system 1A suppresses common mode noise using the damping variable resistor 25, and reduces the switching carrier frequency when the noise level detected using the damping variable resistor 25 is large. Can reduce noise level.

Note that the damping variable resistor 25 may be mounted on the motor 5 side (secondary side). Here, the configuration of the power conversion system when the damping variable resistor 25 is connected to the motor 5 side will be described.

FIG. 2 is a diagram showing a second configuration example of the power conversion system according to the embodiment. Among the components in FIG. 2, components that achieve the same functions as the power conversion system 1A shown in FIG. 1 are designated by the same reference numerals, and redundant explanation will be omitted.

Like the power conversion system 1A, the power conversion system 1B is a system that uses electric power from the power source 4 to drive the motor 5, automatically detects noise, and automatically reduces noise. Like the power conversion system 1A, the power conversion system 1B includes a semiconductor power conversion device 10, a noise information detection device 20, an input power wire 6, and an output power wire 7.

Power conversion system 1B is connected to power source 4 and motor 5. In the power conversion system 1B, a noise information detection device 20 having a damping variable resistor 25 is connected between the motor 5 and a semiconductor power conversion device 10 having a PWM converter.

In the power conversion system 1B, the common mode choke coil 3 is arranged on the output power wire 7. In the common mode choke coil 3, an output power wire 7 and a damping resistance connection wire 22 are passed through the center of the cylindrical portion.

Next, the processing procedure of the processing executed by the power conversion systems 1A and 1B will be explained. FIG. 3 is a flowchart illustrating a procedure of processing executed by the power conversion system according to the embodiment. Note that since the processing procedures executed by the power conversion systems 1A and 1B are the same, the processing procedures executed by the power conversion system 1A will be described here.

In the power conversion system 1A, a noise determination value (noise determination value Th described later), which is a threshold value used for determining noise information, is set by the user of the power conversion system 1A. That is, at least one of the temperature threshold and the current threshold is set in the power conversion system 1A by the user of the power conversion system 1A.

When the power conversion system 1A starts driving the motor 5, the noise information detection device 20 detects noise information using the damping variable resistor 25 (step S10). Specifically, when the power conversion system 1A includes a temperature sensor 21, the temperature sensor 21 detects the damping resistance temperature. Moreover, when the power conversion system 1A has a current sensor 8, the current sensor 8 detects the damping circuit current.

Noise information detection device 20 transmits noise information to control section 12 of semiconductor power conversion device 10 . The control unit 12 determines whether the noise information is less than or equal to the noise determination value Th (step S20). Specifically, when the power conversion system 1A includes the temperature sensor 21, the control unit 12 determines whether the damping resistance temperature measured by the temperature sensor 21 is equal to or lower than the temperature threshold. Further, when the power conversion system 1A includes the current sensor 8, the control unit 12 determines whether the damping circuit current measured by the current sensor 8 is equal to or less than the current threshold value.

If the noise information is greater than the noise determination value Th (step S20, No), the control unit 12 determines that the noise level is greater than the reference value. That is, when the damping resistance temperature is higher than the temperature threshold, the control unit 12 determines that the noise level is higher than the reference value. Further, when the damping circuit current is higher than the current threshold, the control unit 12 determines that the noise level is higher than the reference value. If the control unit 12 determines that the noise level is higher than the reference value, it lowers the switching carrier frequency (step S30).

Thereafter, the noise information detection device 20 waits for a waiting time corresponding to the resistance value of the damping variable resistor 25 (step S40), and returns to the process of step S10. Then, the noise information detection device 20 detects noise information using the damping variable resistor 25 (step S10). The control unit 12 determines whether the noise information is less than or equal to the noise determination value Th (step S20). If the noise information is less than or equal to the noise determination value Th (step S20, Yes), the control unit 12 determines that the noise level is less than or equal to the reference value, and does not change the switching carrier frequency.

Note that the semiconductor power conversion device 10 may lower the switching carrier frequency before the noise information reaches the noise determination value Th. Here, a process in which the semiconductor power conversion device 10 lowers the switching carrier frequency before the noise information reaches the noise determination value Th will be described.

FIG. 4 is a diagram for explaining processing when the power conversion system according to the embodiment lowers the switching carrier frequency before the noise information reaches the noise determination value. FIG. 4 shows an example of the transition of noise information N1 when the semiconductor power conversion device 10 adjusts the switching carrier frequency.

The semiconductor power conversion device 10 presets a noise determination value Th, which is a threshold value of the noise information N1, in accordance with an instruction from the user (st1). The threshold of the noise information N1 includes at least one of a temperature threshold and a current threshold.

When the power conversion system 1A starts driving the motor 5, the noise information detection device 20 detects noise information N1 using the damping variable resistor 25. When the noise information N1 exceeds the noise determination value Th, the semiconductor power conversion device 10 determines that an error has occurred (st2) and lowers the switching carrier frequency. As a result, the noise information N1 detected by the noise information detection device 20 decreases.

The storage unit 11 of the semiconductor power conversion device 10 stores an error history 33 indicating a history of errors that have occurred in the power conversion system 1A. The storage unit 11 here stores, as the error history 33, that the noise information N1 exceeds the noise determination value Th. When the error history 33 is stored in the storage unit 11, the control unit 12 of the semiconductor power conversion device 10 reads the error history 33 from the storage unit 11. Upon reading out the error history 33, the control unit 12 generates an fc command 34 based on the error history 33.

For example, after the noise information N1 exceeds the noise determination value Th even once, the control unit 12 generates the fc command 34 so that the noise information N1 does not exceed the noise determination value Th from then on. Specifically, based on the noise judgment value Th, the control unit 12 sets a new noise judgment value Tx that is lower than the noise judgment value Th by a specific value or a new noise judgment value Tx that is lower than the noise judgment value Th by a specific percentage. Set. After setting the new noise determination value Tx, the control unit 12 lowers the switching carrier frequency when the noise information N1 exceeds the new noise determination value Tx. Thereby, the control unit 12 can lower the switching carrier frequency before the noise information N1 exceeds the initial noise determination value Th (st3).

By the way, there is a method of measuring the magnetic flux flowing through the iron core of the common mode choke coil 3 and lowering the switching carrier frequency when the magnetic flux exceeds the protection level. In this method, since it is necessary to measure the magnetic flux flowing through the iron core, the equipment becomes complicated and expensive.

On the other hand, the power conversion systems 1A and 1B of the embodiment lower the switching carrier frequency when the noise information N1 exceeds the noise determination value Th, so it is possible to reduce switching noise without measuring the magnetic flux flowing through the iron core. becomes possible.

In this way, the power conversion systems 1A and 1B do not measure magnetic flux, so switching noise can be reduced with an inexpensive system configuration. Moreover, since the power conversion systems 1A and 1B consume noise current in the damping variable resistor 25, switching noise can be suppressed. Note that a damping resistor whose resistance value cannot be changed may be applied to the power conversion systems 1A and 1B instead of the damping variable resistor 25.

In addition, the power conversion systems 1A and 1B can automatically reduce the switching carrier frequency according to the noise level, so it is possible to prevent the power conversion systems 1A and 1B from stopping and to suppress switching noise. can.

Here, the hardware configuration of the control unit 12 will be explained. FIG. 5 is a diagram illustrating an example of a hardware configuration that implements the control unit according to the embodiment. The control unit 12 can be realized by an input device 300, a processor 100, a memory 200, and an output device 400. An example of the processor 100 is a CPU (Central Processing Unit, also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of the memory 200 are RAM (Random Access Memory) and ROM (Read Only Memory).

The control unit 12 is realized by the processor 100 reading and executing a computer-executable control program 37 for executing the operations of the control unit 12 stored in the memory 200. The control program 37, which is a program for executing the operations of the control unit 12, can also be said to cause the computer to execute the procedures or methods of the control unit 12.

The control program 37 executed by the processor 100 has a module configuration including the control unit 12, and these components are loaded onto and generated on the main storage device.

The input device 300 receives the damping resistance temperature from the temperature sensor 21 and sends it to the processor 100. Furthermore, the input device 300 receives the damping circuit current from the current sensor 8 and sends it to the processor 100 .

The memory 200 stores a control program 37, an error history 33, a temperature threshold 35, a current threshold 36, and the like. Furthermore, the memory 200 is used as a temporary memory when the processor 100 executes various processes. The output device 400 outputs a driving current for the motor 5 to the motor 5 .

The control program 37 may be an installable or executable file stored in a computer-readable storage medium and provided as a computer program product. Further, the control program 37 may be provided to the control unit 12 via a network such as the Internet. Note that some of the functions of the control unit 12 may be realized by dedicated hardware such as a dedicated circuit, and some may be realized by software or firmware. Note that the hardware configuration of some of the functions included in the control unit 12 may be the hardware configuration shown in FIG. 5 .

According to the embodiment, the power conversion systems 1A and 1B determine whether the noise level of the noise current is larger than the reference value based on the noise information N1 detected using the damping variable resistor 25. If the noise level is determined to be higher than the reference value, the switching carrier frequency is lowered, making it possible to easily reduce switching noise. Moreover, since the power conversion systems 1A and 1B can consume noise current with the damping variable resistor 25, switching noise can be reduced.

The configuration shown in the above embodiments is an example, and it is possible to combine it with another known technology, and a part of the configuration can be omitted or changed without departing from the gist. It is possible.

1A, 1B power conversion system, 3 common mode choke coil, 4 power supply, 5 motor, 6 input power wire, 7 output power wire, 8 current sensor, 10 semiconductor power conversion device, 11 storage section, 12 control section, 13 PWM generation Part, 14 Semiconductor power conversion section, 20 Noise information detection device, 21 Temperature sensor, 22 Damping resistor connection line, 23 Temperature sensor connection line, 24 Current sensor connection line, 25 Damping variable resistor, 31 Temperature information, 32 Current information, 33 error history, 34 fc command, 35 temperature threshold, 36 current threshold, 37 control program, 100 processor, 200 memory, 300 input device, 400 output device, N1 noise information, Th noise judgment value, Tx new noise judgment value.

Claims (5)

a power conversion device connected between a power source and a motor to convert power;
a noise information detection device that detects noise information that is information corresponding to noise current of switching noise generated by the power conversion device;
Equipped with
The noise information detection device includes:
a damping resistor that reduces the noise current;
a common mode choke coil through which a main power line connected to the power converter is passed and an electric wire connected to the damping resistor is passed;
a sensor that detects at least one of temperature information, which is information about the temperature of the damping resistor, and current information, which is information about the current flowing through the damping resistor, which changes according to a change in the noise current;
has
The power conversion device includes:
The noise information including at least one of the temperature information and the current information is received from the noise information detection device, and based on the noise information, it is determined whether the noise level of the noise current is larger than a reference value. determining, and if the noise level is greater than the reference value, lowering the switching carrier frequency;
A power conversion system characterized by: The noise information detection device is connected to the power source side, which is a primary side of the power conversion device.
The power conversion system according to claim 1, characterized in that: The noise information detection device is connected to the motor side, which is a secondary side of the power conversion device.
The power conversion system according to claim 1, characterized in that: The damping resistor is a variable damping resistor with a variable resistance value.
The power conversion system according to claim 1, characterized in that: The power conversion device includes:
After the noise level exceeds the noise judgment value which is the reference value, a new noise judgment value lower than the noise judgment value is set, and when the noise level becomes larger than the new noise judgment value, the switching carrier lower the frequency,
The power conversion system according to any one of claims 1 to 4.

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