The accuracy of control links directly affects the compensation effect of active power filter (APF). Fast repetitive control (FRC) strategy based on single synchronous rotating frame is proposed, for improving the steady‐state compensation accuracy and dynamic response. Based on the fundamental rotating mathematical model of APF, the fundamental component of output instruction current can be converted to DC component by synchronous rotation coordinate transformation, and 6 k ± 1 times harmonics can be transferred to 6 k times harmonics. Then, a hybrid control method based on proportion‐integral (PI) control combined with FRC is proposed. The experimental results of the prototype proved that the method advantages in steady‐state compensation accuracy, adaptability to load variation and dynamic performance.

Energy storage technology has become critical for supporting China’s large-scale access to renewable energy. As the interface between the battery energy storage system (BESS) and power grid, the stability of the PCS (power conversion system) plays an essential role. Here, we present a topology of a 10 kV high-voltage energy storage PCS without a power frequency transformer for the establishment of a large-scale energy storage system. We analyzed the energy storage converter’s mechanism and characteristics and also introduced the power-control strategy of the HVAC (high-voltage AC) and LVDC (low-voltage DC) converter module. On this basis, a 10 kV/1 MW high-capacity PCS prototype was designed. Additionally, by simulation and experiment, we proved the correctness of the PCS scheme. The topology and control strategy proposed in this paper can provide cases and technical support for the subsequent promotion and application of new energy and power station energy storage.

To ensure the reliable operation of power converters and prevent catastrophic failures, this paper proposes a novel online fault diagnosis strategy for a four-level converter. The core of this strategy is an optimized multi-kernel extreme learning machine model. Specifically, the model extracts multi-scale features from three-phase output currents by combining Gaussian and polynomial kernels and employs particle swarm optimization to determine the optimal kernel fusion scheme. Experimental validation was performed on an online diagnosis platform for a four-level converter. The results show that the proposed method achieves a high diagnostic accuracy of 99.35% for open-circuit faults. Compared to conventional methods, this strategy significantly enhances diagnostic speed and accuracy through its optimized multi-kernel mechanism.

Electric vehicle (EV) chargers play an important role in the popularity of electric vehicles. In order to improve the efficiency of EV chargers, this paper replaces the discrete inductors in an interleaved Boost PFC topology with a coupled inductor. Theoretical analysis of the Boost PFC topology was presented, and the coupled inductor was designed, with simulation verification. Experimental testing of the designed coupled inductor was done on a 7 kW EV charger platform. The experimental results show that the designed coupled inductor can improve the efficiency of an EV charger.