Abstract: A fault ride-through circuit with a variable frequency transformer (VFT) and a control method thereof are provided, and the control method comprises: pretreating acquired voltages of grids, a voltage of a stator interface and a voltage of a rotor interface to obtain a rotor voltage DC component and a rotor voltage DC component; testing and treating a voltage frequency of a first grid and a voltage frequency of a second grid; carrying out a reference voltage calculation for a stator voltage DC component, a rotor voltage DC component, the voltage frequencies of the first grid and the second grid to obtain a positive voltage reference value of the first PWM convertor and the second PWM convertor; and processing the voltage reference values to obtain the switch signals for controlling the first PWM convertor and the second PWM convertor.

Abstract: A voltage balancing circuit is applied to a power supply system. The power supply system comprises N power storage devices. The voltage balancing circuit comprises: N switches, N capacitors and a controller; the N switches are respectively connected to the N serial power storage devices; the N switches are respectively connected to the first terminals of the N capacitors; the second terminals of the N capacitors are connected to a common neutral line; the controller is connected to the N switches through a control line to control the switching of the N switches. The voltage balancing circuit avoids power loss when balancing the voltage of a plurality of serial power storage devices, and is small in size and low-cost, and balances voltage quickly.

Abstract: A fault ride-through circuit with a variable frequency transformer (VFT) and a control method thereof are provided, and the control method comprises: pretreating acquired voltages of grids, a voltage of a stator interface and a voltage of a rotor interface to obtain a rotor voltage DC component and a rotor voltage DC component; testing and treating a voltage frequency of a first grid and a voltage frequency of a second grid; carrying out a reference voltage calculation for a stator voltage DC component, a rotor voltage DC component, the voltage frequencies of the first grid and the second grid to obtain a positive voltage reference value of the first PWM convertor and the second PWM convertor, and processing the voltage reference values to obtain the switch signals for controlling the first PWM convertor and the second PWM convertor.

Abstract: A voltage balancing circuit is applied to a power supply system. The power supply system comprises N power storage devices. The voltage balancing circuit comprises: N switches, N capacitors and a controller; the N switches are respectively connected to the N serial power storage devices; the N switches are respectively connected to the first terminals of the N capacitors; the second terminals of the N capacitors are connected to a common neutral line; the controller is connected to the N switches through a control line to control the switching of the N switches. The voltage balancing circuit avoids power loss when balancing the voltage of a plurality of serial power storage devices, and is small in size and low-cost, and balances voltage quickly.