Inverter quality appraisal

inverter is a kind of power control equipment that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply.
frequency converter is mainly composed of rectifier (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, detection unit, microprocessing unit, etc. The inverter relies on the switching of the internal IGBT to adjust the voltage and frequency of the output power supply, and provides the required power supply voltage according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation. In addition, the frequency converter also has many protection functions, such as overcurrent, overvoltage, overload protection, etc.
In the case of inverter quality appraisal, Zhongke Testing can provide inverter quality appraisal services.

According to different classification standards, frequency converters can be divided into several categories.
is classified according to the grid voltage level input to the inverter. The inverter can be divided into low voltage (110V, 220V, 380V, etc.), medium voltage (690V, 1140V, 2300V, etc.) and high voltage (3kV, 3.3kV, 6kV, 6.6kV, 10kV etc.) frequency converter;
is classified according to the working mode of the main circuit, and can be divided into voltage type and current type frequency converters;
is classified according to the switching method, and can be divided into PAM (pulse amplitude modulation), PWM (pulse width modulation) control frequency converter;
is classified according to the purpose, and is mainly divided into general-purpose frequency converters, special-purpose frequency converters, etc.;
is classified according to the control method, and is mainly divided into V/F control inverter and vector control inverter, etc.

GB/T 35701-2017 Ship electric propulsion frequency converter
GB/T 11299.8-1989 Satellite communication earth station radio equipment measurement method Part 2: Sub-system measurement Section 4: Upconverter and downconverter
GB/T 34123-2017 Technical specifications for inverter protection in power systems
GB/T 24625-2009 Design and application guide for synchronous motors powered by inverters
GB/T 22670-2018 Test methods for three-phase cage induction motors powered by inverters
GB/T 32877-2022 Specific test methods for determining losses and efficiency of AC motors powered by frequency converters
GB/T 22720.2-2019 Rotating electrical machines Qualification tests for partial discharge-resistant electrical insulation structures (type II) of rotating electrical machines powered by voltage-type frequency converters
GB/T 22720.1-2017 Rotating electrical machines Identification and quality control testing of electrical insulation structures of rotating machines powered by voltage-type frequency converters without partial discharge (Type I)
GB 19510.210-2013 Lamp control devices Part 2-10: Special requirements for electronic inverters and frequency converters for high-frequency cold start tubular discharge lamps (neon lamps)

The high-voltage inverter purchased by a certain company tripped five times due to quality problems within the first two months of its official production. After several repairs and inspections, it was still not in normal operation, resulting in a dispute with the equipment manufacturer.
was entrusted by the court to conduct an appraisal and analysis on "whether there are quality problems" with the inverter involved in the case.
identification analysis results:
identification analysis expert group discussed the relevant information and on-site investigation of the inverter involved in the case and made a comprehensive quality and technical analysis, and made the following suggestions and conclusions:
involved 10KV high voltage The inverter has many physical evidence features that do not meet the quality requirements stipulated in the contract, such as inconsistent device models and no panel control functions. The involved 10KV high-voltage inverter has faults such as tripping of the high-voltage side switch and its output voltage is not designed with effective margin. There is a causal relationship between the static and dynamic voltage imbalance caused by the series connection of IGBTs.