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CN-122029733-A - Power conversion device and compressor control device

CN122029733ACN 122029733 ACN122029733 ACN 122029733ACN-122029733-A

Abstract

A compressor control device (100) is provided with a power conversion device (10) and a compressor (20) that compresses a refrigerant using a motor (21). The power conversion device (10) is provided with a power conversion unit (30), a control unit (40), and a leakage current detection unit (50), wherein the leakage current detection unit (50) is provided with a leakage current detector (51) that detects leakage current via a power line, and a band limiting filter (52). The control unit (40) performs a diagnosis of refrigerant stagnation, which is a diagnosis of abnormality of the compressor (20), based on the output of the leakage current detection unit (50) before the operation of compressing the refrigerant by the compressor (20), which is the normal operation of the power conversion unit (30).

Inventors

  • HENG XIN

Assignees

  • 三菱电机株式会社

Dates

Publication Date
20260512
Application Date
20231013

Claims (14)

  1. 1. A power conversion device is provided with: a power conversion unit having an inverter that includes a plurality of switching elements, converts dc power into ac power, and outputs the ac power to a load; a control unit for controlling the output of the power conversion unit, and A leakage current detection unit having a leakage current detector for detecting a leakage current via a power line passing through the power conversion unit, and a band limiting filter provided at a subsequent stage of the leakage current detector, The control unit performs abnormality diagnosis of the load based on an output of the leakage current detection unit before the normal operation of the power conversion unit.
  2. 2. The power conversion device according to claim 1, wherein, The band limiting filter of the leakage current detection unit is a band pass filter having a frequency that is an integer multiple of a switching frequency of the inverter as a pass frequency.
  3. 3. The power conversion device according to claim 2, wherein, The band limiting filter of the leakage current detection unit is configured to be variable in the passing frequency, and the passing frequency is determined based on the switching frequency of the inverter.
  4. 4. The power conversion device according to any one of claims 1 to 3, wherein, The control unit reports the result of the abnormality diagnosis to the outside.
  5. 5. The power conversion apparatus according to any one of claims 1 to 4, wherein, The control unit has a plurality of operation modes to control the power conversion unit, and changes the operation modes based on the result of the abnormality diagnosis.
  6. 6. A control device for a compressor, wherein, A power conversion device according to any one of claims 1 to 4, The compressor control device further includes a compressor as the load, the compressor having a motor and a compression mechanism driven by the motor to compress a refrigerant, The control unit performs, as the abnormality diagnosis, a diagnosis of refrigerant stagnation caused by liquefaction of the refrigerant inside the compressor based on an output of the leakage current detection unit before an operation of compressing the refrigerant by the compressor, which is the normal operation of the power conversion unit.
  7. 7. The compressor control device of claim 6, wherein, In the abnormality diagnosis, the control unit diagnoses that the refrigerant stagnation has not occurred when the output of the leakage current detection unit is within a set range, and starts the normal operation of the power conversion unit.
  8. 8. The compressor control device of claim 7, wherein, The control unit has, as operation modes of the power conversion unit, a first mode in which the normal operation is performed and a second mode in which a refrigerant stagnation eliminating operation for reducing the amount of the refrigerant liquefied in the compressor is performed, and the abnormality diagnosis is performed during the operation in the second mode.
  9. 9. The compressor control device of claim 8, wherein, The control unit further includes a third mode for performing a check operation for generating the leakage current while maintaining the operation of the compressor in a stopped state, The control unit performs the inspection operation of the power conversion unit in the third mode before the first mode and the second mode, and performs the abnormality diagnosis during the operation in the third mode.
  10. 10. The compressor control device according to claim 8 or 9, wherein, The control unit diagnoses the occurrence of the refrigerant stagnation in the abnormality diagnosis when the output of the leakage current detection unit exceeds the set range, and performs the refrigerant stagnation eliminating operation of the power conversion unit in the second mode.
  11. 11. The compressor control device of claim 10, wherein, A heater which is electrically controlled by the control part is arranged on the compressor, The control unit performs the refrigerant stagnation eliminating operation and reduces the amount of the liquefied refrigerant by heating the inside of the compressor with the heater when it is diagnosed that the refrigerant stagnation occurs in the abnormality diagnosis.
  12. 12. The compressor control device according to any one of claims 8 to 11, wherein, The refrigerant stagnation eliminating operation is an operation in which the inside of the compressor is heated by performing a constraint energization without rotating the motor.
  13. 13. The compressor control device of claim 7, wherein, The control unit is provided with a first mode for controlling the normal operation and a third mode for performing an inspection operation for generating the leakage current while maintaining the compressor in an operation stop state, The control unit performs the inspection operation of the power conversion unit in the third mode before the first mode, performs the abnormality diagnosis during the operation in the third mode, In the abnormality diagnosis, the control unit diagnoses that the refrigerant stagnates when the output of the leakage current detection unit exceeds the set range.
  14. 14. The compressor control device of claim 13, wherein, A heater which is electrically controlled by the control part is arranged on the compressor, In the abnormality diagnosis, the control unit heats the inside of the compressor by the heater to reduce the amount of the liquefied refrigerant when it is diagnosed that the refrigerant stagnates.

Description

Power conversion device and compressor control device Technical Field The present disclosure relates to a power conversion device and a compressor control device. Background In a compressor that compresses a refrigerant used in an air conditioner or the like, if a state in which the temperature inside is low is maintained for a long period of time, the refrigerant existing inside the compressor becomes liquefied. This phenomenon is referred to as refrigerant stagnation. If the compressor is driven in a state where the refrigerant stagnates in this way, the proper operation of the compressor is hindered. In addition, since the liquid refrigerant reduces the impedance between the winding and the core in the compressor motor and increases the leakage current, the liquefied state of the refrigerant can be diagnosed by detecting the leakage current. The conventional compressor control device includes a compressor having a motor and a compression mechanism driven by the motor, a motor driving unit as a power conversion device, and a leakage current detection unit for detecting a leakage current generated in the motor. The control unit starts a refrigerant stagnation eliminating operation for reducing the amount of refrigerant liquefied in the interior of the compressor before a normal operation for controlling the motor driving unit to compress the refrigerant in the compressor is started, and then ends the refrigerant stagnation eliminating operation when the leakage current is equal to or less than a reference value (for example, patent document 1). Patent document 1 Japanese patent application laid-open No. 2013-100979 Disclosure of Invention Problems to be solved by the invention In the conventional technique described in patent document 1, the detected leakage current is a spike waveform, and data loss occurs according to the performance (e.g., sampling rate) of the control unit. Therefore, it is difficult to extract the detection value of the leakage current used for diagnosing the liquefied state of the refrigerant with high reliability, and it is not possible to diagnose the liquefied state of the refrigerant with high accuracy. The present disclosure has been made to solve the above-described problems, and an object of the present disclosure is to provide a power conversion device capable of extracting a detection value of a leakage current used for abnormality diagnosis of a load with high reliability and performing abnormality diagnosis of the load with high accuracy. Further, an object is to provide a compressor control device provided with such a power conversion device, which can accurately diagnose the liquefied state of the refrigerant in the compressor as a load. Solution for solving the problem The power conversion device includes a power conversion unit having an inverter that converts DC power into AC power and outputs the AC power to a load, a control unit that controls the output of the power conversion unit, and a leakage current detection unit that detects a leakage current via an energizing line passing through the power conversion unit, and a band limiting filter provided at a stage subsequent to the leakage current detection unit. The control unit performs abnormality diagnosis of the load based on the output of the leakage current detection unit before the normal operation of the power conversion unit. The compressor control device according to the present disclosure includes the power conversion device, and further includes a compressor as the load, the compressor including a motor and a compression mechanism driven by the motor to compress a refrigerant. The control unit performs, as the abnormality diagnosis, a diagnosis of refrigerant stagnation caused by liquefaction of the refrigerant inside the compressor based on an output of the leakage current detection unit before an operation of compressing the refrigerant by the compressor, which is the normal operation of the power conversion unit. ADVANTAGEOUS EFFECTS OF INVENTION According to the power conversion device of the present disclosure, the detection value of the leakage current used for abnormality diagnosis of the load can be extracted with high reliability, and the abnormality diagnosis of the load can be performed with high accuracy. In addition, according to the compressor control device of the present disclosure, the liquefaction state of the refrigerant in the compressor can be diagnosed with high accuracy. Drawings Fig. 1 is a block diagram showing a schematic configuration of a compressor control device according to embodiment 1. Fig. 2 is a diagram showing a configuration of a power conversion unit according to embodiment 1. Fig. 3 is a flowchart illustrating the operation of the compressor control device according to embodiment 1. Fig. 4 is a waveform chart showing detection of leakage current before and after passing through the band limiting filter of the leakage current detection unit according to embodiment 1. F