The main circuit is the power conversion part that provides voltage and frequency regulation power to the asynchronous motor. The main circuit of the frequency converter can be roughly divided into two categories: The voltage type is a frequency converter that converts the DC of the voltage source into AC, and the filtering of the DC loop is a capacitor. The current type is a frequency converter that converts the DC of the current source into AC, and its DC loop filter is an inductance. It consists of three parts, a "rectifier" that converts industrial frequency power into DC power, and a "flat wave loop" that absorbs the voltage pulsation generated by the converter and inverter. A large number of diode converters are used, which convert the industrial frequency power supply into a DC power supply. Two groups of transistor converters can also be used to form a reversible current converter. Because of its reversible power direction, regenerative operation can be carried out. The DC voltage rectified by the rectifier contains a pulsating voltage of 6 times the frequency of the power supply. In addition, the pulsating current generated by the inverter also changes the DC voltage. In order to suppress voltage fluctuations, inductors and capacitors are used to absorb the pulsating voltage (current). If the capacity of the device is small, if the power supply and the main circuit components have a margin, the inductor can be omitted and a simple smoothing loop can be used. Contrary to the rectifier, the inverter converts the DC power into the AC power of the required frequency. A 3-phase AC output can be obtained by turning on and off the 6 switching devices within a determined time. Take the voltage-type pwm inverter as an example to show the switching time and voltage waveform. The control circuit is a circuit that provides control signals to the main circuit of the asynchronous motor (voltage and frequency can be adjusted). It has the frequency and voltage "calculation circuit", the main circuit "voltage and current detection circuit", and the motor's "speed detection" "Circuit", the "drive circuit" that amplifies the control signal of the arithmetic circuit, and the "protection circuit" of the inverter and the motor. (1) Calculation circuit: compare the external speed, torque and other commands with the current and voltage signals of the detection circuit to determine the output voltage and frequency of the inverter. (2) Voltage and current detection circuit: It is isolated from the main circuit to detect voltage and current. (3) Drive circuit: the circuit that drives the main circuit device. It is isolated from the control circuit so that the main circuit device is turned on and off. (4) Speed ​​detection circuit: take the signal of the speed detector (tg, plg, etc.) installed on the asynchronous motor shaft machine as the speed signal, and send it to the calculation loop, and the motor can run at the command speed according to the command and calculation. (5) Protection circuit: Detect the voltage, current, etc. of the main circuit, in order to prevent damage to the inverter and asynchronous motor when an abnormality such as overload or overvoltage occurs. Truck Type Diesel Generator,Super Silent Diesel Genset,Mobile Diesel Genset,Diesel Marine Genset Jiangsu Vantek Power Machinery Co., Ltd , https://www.vantekpower.com
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