The protection function of frequency converter can be divided into the following two categories

The protection function of frequency converter in automatic industrial washing machine? We all know that frequency conversion motor is used in automatic industrial washing machine, so why use frequency converter? Here are some functions of frequency converter in automatic industrial washing machine The protection function of frequency converter can be divided into the following two categories: (1) after detecting the abnormality, the control signal of power semiconductor device is blocked to make the motor stop automatically. (2) After the abnormal state is detected, corrective actions are automatically carried out, such as over-current stall prevention and regeneration overvoltage stall prevention. (3) Such as over-current cut-off, regeneration overvoltage cut-off, semiconductor cooling fan overheating and instantaneous power failure protection. The function of the protection circuit of the inverter is to judge the operation status of the inverter by detecting the output voltage, current and other parameters of the main circuit. When the current, voltage, temperature and other parameters are abnormal, in order to prevent the list of protection functions in the variable frequency speed regulation system, the protection functions of the frequency converter are as follows: 1 Instantaneous over-current protection: when the rectifier, inverter or load side of the inverter is short-circuit, and the current flowing through the rectifier and inverter switch device reaches the abnormal value (exceeding the allowable value), the instantaneous over-current protection action stops the operation of the frequency converter. Overload protection: when the output current of inverter exceeds the set value, and the current duration reaches the set time limit value, in order to prevent the switch device damage of inverter, overload protection action stops the operation of inverter. Overload protection has inverse time characteristic, usually using relay or electronic thermal protection (composed of electronic circuit). 3. Regeneration overvoltage protection: when the motor of the variable frequency speed regulation system is rapidly decelerating, the DC circuit voltage of the frequency converter will rise due to the feedback of the system regenerative power, and sometimes it will exceed the allowable value of the voltage and damage the electronic devices in the frequency converter. In order to suppress the regeneration overvoltage, the method of stopping the inverter or limiting the fast deceleration is adopted to realize the over-voltage protection of the system. Instantaneous power failure protection: for the instantaneous power failure within a few milliseconds, the inverter control circuit can work normally. However, if the instantaneous power failure is more than tens of MS, the control circuit will not work normally and the main circuit will lose power. In order to avoid the electrical or mechanical failure or accident caused by the misoperation of frequency conversion speed regulation system caused by instantaneous power failure, the frequency conversion and speed regulation system is equipped with instantaneous power failure protection to stop the operation of the inverter after the instantaneous power failure. Grounding over-current protection: when the load of frequency conversion speed regulation system is grounded, the grounding over-current protection function is set to protect the inverter of frequency converter. However, in order to ensure personal safety, leakage circuit breaker should be installed. 6 temperature abnormal protection: for the inverter with cooling fan, when the fan is abnormal, the temperature inside the frequency converter will rise, and the inverter will be damaged due to temperature overrun. Therefore, the cooling fan motor of frequency converter should be protected by thermal relay, and the heat sink of inverter switch device should be equipped with temperature sensor, and the inverter of inverter should be stopped after abnormal temperature is detected. The load protection functions of frequency converter are as follows: overload protection: the overload detection unit and inverter overload protection share the same industrial washing machine, but considering the overheat of the motor in the variable frequency speed regulation system at low speed, the temperature sensor is embedded in the winding of the asynchronous motor, or the electronic thermal protection installed in the inverter is used to detect the overheating of the motor. When the motor overload protection action is frequent, we can consider reducing the motor load, increasing the capacity of the motor and frequency converter. Over (over speed) protection: when the output frequency of the frequency converter or the speed of the asynchronous motor of the variable frequency speed regulation system exceeds the specified value, the over (over speed) protection acts to stop the operation of the frequency converter. The other protection functions of frequency converter are as follows: preventing stall over-current: when the frequency conversion speed regulating system is accelerating rapidly, if the asynchronous electric tracking is slow, the over-current protection circuit will act and the motor can not continue to run. Therefore, before the load current is reduced, it is necessary to control the speed of frequency rise or frequency decrease. The same control is sometimes applied to the over-current in constant speed operation. Prevention of stall regeneration overvoltage: the regenerative energy generated by the variable frequency speed regulation system during deceleration causes the DC voltage of the main circuit to rise. In order to prevent the protection action of the regeneration overvoltage circuit, the control should be carried out before the DC voltage rises to suppress the speed of frequency drop and prevent the speed control system from stalling. Instantaneous voltage loss or undervoltage of power supply: when instantaneous voltage loss or undervoltage occurs, the frequency converter will be able to maintain continuous operation. Some frequency converters can also track the motor speed and adjust the output frequency when the power supply voltage is restored. Automatic industrial washing machine, microprocessor abnormal protection.