3results about How to "Reduce harmonic current" patented technology

The application discloses a carrier frequency control method, a control device and an air conditioner for power factor correction, wherein the carrier frequency control method is a special carrier frequency control method used near the zero-crossing point of the variable carrier frequency control method; for the carrier frequency corresponding to the input voltage / input current near the zero-crossing point, the carrier frequency is limited to a fixed value or is increased with the decrease of the input voltage / input current, so that the input current of the PFC circuit near the zero-crossing point cannot follow the input voltage, the current harmonic of the PFC circuit is reduced, and the working stability of the PFC circuit is improved.

The invention discloses a permanent magnet synchronous motor and a single-resistor current sampling method. The permanent magnet synchronous motor controls a three-phase inverter based on an SVPWM strategy, and the method comprises the following steps: in a current control period, acquiring flow directions of A, B and C three-phase current; according to the flow direction of the ABC three-phase current and a sector where a target voltage vector is located, whether the minimum time window of single-resistor sampling in the current control period can cancel dead time or not is determined; and according to the determined minimum time window, determining whether to adjust the two-phase sampling in the current control period. According to the scheme provided by the invention, sampling can be carried out by directly utilizing the dead time under some conditions, so that the number of times of PWM waveform adjustment is reduced, the stability of the system is improved, and the collected current is closer to the same moment.

The utility model discloses a special high-performance four-quadrant frequency converter for the electromagnetic industry, which belongs to the technical field of power electronics, and comprises a main topology part and a control part, the main topology part comprises an input filtering part, a rectification filtering part and an inversion part, the input filtering part comprises a network side inductor L1, a filtering capacitor C1 and a machine side inductor L2, and the rectification filtering part comprises a three-phase half-bridge insulated gate bipolar transistor module, a first bus capacitor Cd1, a second bus capacitor Cd2, a first voltage-sharing resistor Rd1, a second voltage-sharing resistor Rd2 and a buffer loop. The inversion part comprises one or three paths of three-phase half-bridge insulated gate bipolar transistor modules, and the control part comprises a power supply board, a detection board, a rectification side main control board, an inversion side main control board, a rectification side driving board, an inversion side driving board and a driving board.