Feedback from the unit supplier reminds you that in the variable frequency speed regulation system, when the load of the motor is a potential energy load, such as oil field pumping units, mining hoists, etc; Or large inertia loads such as fans, cement pipes, dynamic balancing machines, etc; When fast braking loads are required for steel mills, large gantry planers, machine tool spindles, etc., the motor inevitably undergoes a power generation process. That is, the motor rotor is dragged by external forces or the load's own moment of inertia is maintained, causing the actual speed of the motor to be greater than the synchronous speed output by the frequency converter. The electrical energy generated by the motor will be stored in the DC bus filtering capacitor of the frequency converter. If this energy is not consumed, the DC bus voltage will quickly rise, affecting the normal operation of the frequency converter.
Energy feedback unit, by automatically detecting the DC bus voltage of the frequency converter, inverts the DC voltage of the DC link of the frequency converter into an AC voltage that is in the same frequency and phase as the grid voltage. The energy feedback unit of the frequency converter is connected to the AC grid after multiple noise filtering links, thereby achieving the purpose of energy feedback to the grid. The energy feedback unit of the frequency converter quotes that the electricity fed back to the grid reaches more than 97% of the generated energy, effectively saving electricity.
The principle and characteristics of high-power energy feedback unit
1. Adopting AC-DC-AC direct high voltage (high high) mode, the main circuit switching element is IGBT. The hivert yvf high-voltage inverter adopts a series connection of power units and a stacked wave boosting method.
2. The power unit uses IGBT for synchronous rectification, and the synchronous rectification controller detects the input voltage of the unit grid in real time. The energy feedback unit image of the frequency converter is used to obtain the phase of the grid input voltage using phase-locked control technology. By controlling the phase difference between the rectifier inverter switch tube and the grid voltage, the flow of electrical power between the grid and the power unit can be controlled. Inverted phase, the power unit feeds back electrical energy to the grid, while conversely, electrical power is injected into the power unit from the grid. The magnitude of electrical power is directly proportional to the phase difference. The magnitude and direction of electrical power are determined by the unit voltage. In terms of synchronous rectification, the rectification side is equivalent to an energy feedback unit of a stabilized power supply crane frequency converter. The phase difference between the power grid and the inverter corresponding to the magnitude and direction of electrical power is generated by the deviation between the unit voltage and the unit setting value through PID regulation.
The energy feedback debugging of old chemical equipment can not only verify the newly developed high-power energy feedback unit, but also conduct aging tests on the products of the high-power energy feedback unit under various load conditions. The experimental unit can be connected to the RL load of the aging equipment to conduct load operation experiments on the products. Make the performance of the product more stable and complete.