Cause and example analysis of inverter overvoltage and undervoltage

by:V&T Technologies     2019-11-13
First, overvoltage fault, the code is (OU) Phenomenon: overvoltage alarm usually occurs during shutdown. The main reason is that the deceleration time is too short or there is a problem with the braking resistance and braking unit. Example analysis: a Taian N2 Series 3. 7kW inverter jumps 'OU' when stopping '. Analysis and maintenance: Before repairing this machine, we must first find out the reason for the 'OU' alarm. This is because the speed of cutting the rotating magnetic field of the motor rotor winding is accelerated when the inverter is slowing down, the electromotive force and current of the rotor increase, so that the motor is in the power generation state, and the feedback energy flows to the DC link through the diode parallel to the high-power switch tube in the inverter link, causing the DC bus voltage to rise, so we should focus on checking the brake loop, measuring the discharge resistance is no problem, measuring the brake tube (ET191) It is found that it has broken down, powered on after replacement, and there is no problem with fast parking. Second, undervoltage and undervoltage are also problems we often encounter in use. Mainly because the main circuit voltage is too low ( 220V series is lower than 200 V, 380V series is lower than 400 V) The main reasons: 1. Damage to one of the rectifier bridges or abnormal operation in the thyristor three roads may lead to undervoltage faults. 2. Damage to the main circuit contactor, causing DC bus voltage loss on the charging resistor may cause undervoltage; 3. The voltage detection circuit fails and the undervoltage problem occurs.
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