The interior permanent magnet synchronous motor (IPMSM) is known for its high output torque, strong overload capacity, and high power density, making it a popular choice in the electric vehicle industry. This paper proposes an improved multi-objective artificial hummingbird algorithm that combines chaotic mapping, adaptive weights, and dynamic crowding entropy. An optimization strategy that combines the Taguchi method with the Improved Multi-Objective Artificial Hummingbird Algorithm (IMOAHA), is proposed to minimize torque ripple and back electromotive force in the interior permanent magnet synchronous motor while simultaneously increasing the average torque of the motor. Taking the 8-pole 48-slot interior permanent magnet synchronous motor as an example, the optimization objectives include back electromotive force, average torque, and torque ripple. The rotor-related structural parameters are used as optimization variables. First, the Taguchi method is employed to identify parameters that significantly influence the optimization objectives. Subsequently, response surface fitting is used to establish the relationship between the optimization objectives and parameters. Finally, the multi-objective artificial hummingbird algorithm is utilized for optimization. By comparing the finite element analysis of the motor models before and after optimization, it is evident that the improved multi-objective artificial hummingbird algorithm can effectively enhance the performance of the interior permanent magnet synchronous motor.

In fuel-cell-powered electric vehicles, the output characteristics of the fuel cell are relatively soft, and the output voltage is unstable. Therefore, a DC-DC converter is required between the fuel cell and the inverter to transform the output voltage of the fuel cell into a suitable voltage for the motor drive. Existing non-isolated DC-DC converters cannot meet the requirements of high voltage gain, high efficiency and a wide range of output voltage simultaneously. To improve these performances, a high-gain DC-DC converter with a wide range of output voltage, based on a switched capacitor structure, is proposed in this paper. The converter supplies power to the load by connecting multiple capacitors with the input source in series in switch-on states, while the input source charges the capacitors through a series connection with an inductor in switch-off states. In comparison to existing converters, the proposed converter maintains high voltage gain at lower duty ratios and offers a wide range of output voltage. The operating principles, key waveforms and parameter design of the topology in Continuous Conduction Mode (CCM) are described and analyzed in detail, and the voltage gain of the proposed converter is compared with some other DC-DC converters. Finally, the results of simulations using Simulink and hardware experiments that were conducted to validate the theoretical analysis are described.

In the inverter circuit, the speed at which the MOSFET is impacted by the presence of a parasitic inductor within the printed circuit board (PCB) leads to a delay in the switching process. Furthermore, the parasitic inductor within the circuit can easily form an LC oscillation with the parasitic capacitor of the MOSFET. These two issues result in an inconsistency between the actual output of the MOSFET and the driving signal waveform, leading to distortion in the sinusoidal pulse width modulation (SPWM) waveform and an increase in total harmonic distortion (THD). It is a common practice to mitigate gate oscillation by introducing a resistor at the gate of the MOSFET. However, elevating the resistance leads to deceleration in the charging process of the MOSFET’s parasitic capacitor, consequently causing an increase in the switching delay, and thereby increasing THD. Therefore, an effective strategy to reduce THD is proposed in this paper, while augmenting the gate resistance, computing the MOSFET switching delay, and applying corrective compensation. In this way, the inherent issues of the switch are addressed, resulting in inverter output waveforms that closely resemble sine waves and reduced THD. Through a combination of simulation and empirical experimentation, the efficacy of the proposed approach in significantly reducing THD in the inverter’s output waveform has been empirically substantiated.

The active frequency drift (AFD) method is an effective method to detect islanding in grid-connected photovoltaic systems. However, it has some inherent drawbacks, such as generating higher harmonics. In order to reduce the harmonics and non-detection zone (NDZ), various improved AFD methods have been proposed, but they still suffer from high harmonics and reduced detection speed. To overcome these limitations, this paper proposes an innovative islanding detection technique based on AFD. Analysis reveals that the proposed method reduces harmonics by 68% compared to conventional AFD and has a larger chopping factor. Therefore, this technique offers several distinct advantages, including accelerated detection speed, reduced NDZ and harm caused by disturbances, and improved power quality. Furthermore, to verify the harmonic impact of this proposed islanding detection method, simulations and analyses are conducted using simulation software of Matlab/Simulink. An experimental prototype is set up in Laboratory. The simulation and experimental results demonstrate the superiority of the proposed method.

In this paper, a comprehensive method is proposed to derive the boost DC–DC converter from a given gain formula. The given gain formula is obtained by analyzing, generalizing, and summarizing previous boost structures in the literature. The analysis is based on the volt-second balance theory of inductors. Thus, the gain formula is only related to two elements, the connection between components and the duty cycle of the switches. Therefore, the topology corresponding to the gain can be derived and synthesized according to the connection of the inductors and the capacitor components during the commutation of the switch to meet the demand for different boost converters in different applications. Meanwhile, all the three-order gain formulas generated by this method are analyzed and three of them are selected for topology simplification and focus analysis, and the correctness of the selected topologies is verified by the simulation results and experimental results.

Due to the advantages of low harmonic, low pollution to the power grid, and easy filtering, multilevel inverters have attracted more attention in recent years. In this paper, a five-level inverter based on the differential structure is proposed. It doesn't need an additional bridge arm to change the polarity of the output voltage, but synthesize the structure of generating multiple voltages and changing the polarity of the output voltage. In addition, the special symmetrical structure of the inverter solves the problem of unbalanced capacitor voltage. The proposed five-level inverter is simulated by MATLAB/Simulink and the prototype is made to experiment.