Who knows how the frequency converter works
4 inverter circuit
Inverter circuit In contrast to the rectifier circuit, the inverter circuit converts the DC voltage into the AC voltage of the desired frequency, and turns on and off the power switch device of the upper bridge and the lower bridge at the determined time. Which can be in the output U, V, W three phase phase difference between the 120 ° electrical angle of the three-phase AC voltage.
3. Control circuit
Now the basic converter with 16-bit, 32-bit microcontroller or DSP as the control core, in order to achieve full digital control.
The frequency converter is the output voltage and frequency adjustable speed control device. The circuit that provides the control signal is called the main control circuit. The control circuit is composed of the following circuits: "operation circuit" of frequency and voltage, "voltage and current detection circuit" of main circuit, and "speed detection circuit" of motor. The control signal of the operation circuit is sent to the "drive circuit" and the "protection circuit" of the inverter and the motor
Inverter to take the control mode, that is, speed control, turn control, PID or other means
Rectifier circuit
The function of the rectifier circuit is to convert the AC power into a DC power supply. Rectifier circuit is generally a separate rectifier module.
The inverter is actually an inverter, which first turns the alternating current into direct current, and then switches the DC power with the electronic components into AC power, and the inverter is equipped with a variable frequency The frequency is adjustable in a certain range, and it is used to control the number of revolutions of the motor, so that the number of revolutions can be adjusted within a certain range.The frequency converter is widely used in the speed regulation of AC motor. Technology development direction, with the development of power electronics technology, AC frequency conversion technology from theory to practice gradually mature. Inverter not only smooth speed, large range, high efficiency, start current is small, smooth operation, and energy saving effect is obvious. Therefore, the exchange frequency control has gradually replaced the traditional traditional slip speed, variable speed control, DC speed control system, more and more widely used in metallurgy, textile, printing and dyeing, smoke machine production lines and buildings, Water supply and other fields. Generally divided into rectifier circuit, flat wave circuit, control circuit, inverter circuit, and so on several major parts.
2. flat wave circuit
In addition, the ripple current generated by the inverter also changes the DC voltage. In order to suppress the voltage fluctuation, the inductor and the capacitor absorb the pulsating voltage (current). In general, the DC voltage of the rectifier is rectified and the DC voltage is rectified. General inverter power supply of the DC part of the main circuit in terms of margin, so eliminating the need for a simple capacitor filter smoothing circuit.
