The main circuit is the power replacement part of the power supply for the asynchronous motor, and the main circuit of the inverter can be roughly divided into two categories: the voltage type is to change the DC of the voltage source to the communication of the DC port of the inverter, and the filter is the capacitor. The current type is an inverter that changes the DC of the current source to communication, and its DC loop filter is inductor. It consists of three parts: a "rectifier" that converts the power supply to DC power, a "flat wave circuit" that absorbs the voltage ripples generated by the converter and inverter, and an "inverter" that converts DC power to communication power.
The control circuit is a circuit that supplies power to the main circuit of the asynchronous motor (voltage and frequency can be adjusted) to supply control signals, which consists of "operation circuit" of frequency and voltage, "voltage and current detection circuit" of the main circuit, "speed detection circuit" of the motor, "driving circuit" that expands the control signal of the operation circuit, and "protection circuit" of the inverter and motor.
(1) Calculation circuit: Compare the external speed, torque and other instructions 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: detect voltage, current, etc. with the main loop potential barrier.
(3) Drive circuit: the circuit that drives the main circuit equipment. It blocks the main circuit equipment from the control circuit and turns it off.
(4) Speed detection circuit: The signal of the speed detector (TAPLA, etc.) installed on the shaft of the asynchronous motor is the speed signal, which is sent into the operation loop, and the motor can be made to run according to the command speed according to the instruction and calculation.
(5) Protection circuit: detect the voltage, current, etc. of the main circuit, and when there is an overload or overvoltage and other abnormalities, in order to avoid damage to the inverter and asynchronous motor, the inverter will stop working or press the voltage, current, and inverter to use protection and maintenance.
Because the inverter can adapt to the multi-faceted requirements of the production process, especially in the application of industrial automation control, the communication frequency conversion speed regulation technology has now risen to the mainstream of industrial automation control. The function of the communication speed regulation system can now be comparable to the DC speed regulation system, and even surpass the DC system. The all-digital control mode it chooses can greatly enhance the information processing. At the same time, it continuously integrates practical experience and skills into the software functions, and it has become possible to choose the chaotic control that cannot be achieved by imitating the control method, so that the reliability, operability and protection of the inverter can be enriched. Because the inverter has a series of advantages such as good speed regulation function, high speed regulation and high operation efficiency, convenient operation and suitable interface with other equipment, it is more and more widely used.
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