Zero-voltage zero-current switching (ZVZCS) phase-shift full-bridge (PSFB) dc–dc converters are candidate converters for high-power switching mode power supply because of their low cost and high efficiency. However, these converters still have some definite weaknesses, e.g., resetting obstacles of high-value currents, extra electrical stress on the power devices. Hence, customers seldom adopt these topologies in high-power applications. This article proposes a new ZVZCS PSFB dc–dc converter to solve the above problems. A clamping circuit with two mosfet s, two diodes, and a resetting transformer ensures ZCS of the lagging-leg switches over a wide load range, and no extra electrical stress arises on the primary or secondary components. The clamping circuit has a high current reset ability and can break through the power limitation of conventional ZVZCS PSFB dc–dc converters. The volume of the resetting transformer is small because of the low voltage-second product, and the added mosfet s cause low power loss because of the wide soft-switching load range and low on-resistance. The experimental results from a 12-kW prototype prove the rightness and advantages of the proposed converter.

The interaction between the permanent magnets and the armature teeth of the PMSM generates cogging torque. It causes vibration and noise. Therefore, this paper establishes the analytical formula of the cogging torque of the motor with auxiliary slots on the surface of the rotor. It shows that reasonable slots can weaken the cogging torque. But it’s essential to determine whether the air-gap flux density harmonics will increase appreciably by slotting. A V-type IPMSM with 8-pole, 48-slot is modeled to analyze the cogging torque. Two new rotor slot shapes—inwardly biased slots and outwardly biased slots—are proposed and researched to reduce the cogging torque of the V-type IPMSM. And they are compared with the traditional symmetrical auxiliary slots. Research shows that the inwardly biased slots and the symmetric auxiliary slots can obtain a better effect on the cogging torque than the outwardly biased slots. By the symmetrical auxiliary slots, the cogging torque is weakened by 75.88%, but the torque ripple increases from 22.36% to 29.60%. By the inwardly biased slots, the cogging torque is weakened by 75.64%, and the torque ripple drops from 22.36% to 12.95%. The inwardly biased slots could successfully suppress the torque ripple.

To fit the requirements of high input dc-dc power conversion, a novel zero-voltage and zero-current switching (ZVZCS) three-level dc-dc converter is proposed. Some advantages of the proposed converter are concluded as follows. The off voltages on the primary switches are clamped around Vin/2 by the input capacitors and the blocking capacitor. Two MOSFETs with low VA rating are added to provide ZVZCS for the main switches in wide load range. The switching loss of the main switches can be optimized due to the soft switching conditions of the turn-on and turn-off instants are well decoupled. The primary components can achieve reduced current stress and even current distribution due to the primary current is zero during the free-wheeling stages. As the current of the auxiliary MOSFETs is zero during most operation stages, the added conduction loss can be neglected. Furthermore, the added switching loss can also be neglected due to these MOSFETs can achieve zero-voltage turn-off and zero-current turn-on. The circuit, operation principles and some technical analyzes are discussed in this letter, and experimental results are also provided to evaluate the proposed converter.

This article proposes a global sensitivity analysis method of a wireless power transfer (WPT) system in domino structure. The sensitivity of system characteristics to capacitor deviations is studied to identify sensitive parameters that cause significant uncertainty in the output. The effect of capacitor deviations on output current, power transfer efficiency, and power factor is comprehensively investigated. Interactions between capacitors are considered, and the main effect index S and the total effect index S _T are calculated by Sobol’ method. Its results indicate that the output current, power factor, and efficiency are slightly affected by the deviation of the capacitor in series with the receiving coil. Interaction between capacitors has a significant effect on the output current and power factor. Finally, the experimental setups of the three-coil and four-coil WPT systems are built. The experimental results show that when the resonant capacitor on the receiving side is varied within ±10%, the fluctuation of the output current is less than 1.5%, the maximum variation in efficiency is less than 2%, and the power factor remains almost above 0.9. The validity of the proposed global sensitivity analysis method is verified.

A novel zero-voltage and zero-current switching (ZVZCS) full bridge (FB) three-level (TL) dc-dc converter is proposed, which can satisfy most requirements of wide operation range high input dc-dc industrial applications. Off voltage on the primary switches can be maintained to Vin/2 by the input capacitors, and no extra primary clamping device is needed. The primary switches can obtain zero-voltage switching (ZVS) or zero-current switching (ZCS) easily. Furthermore, the operation mode can be altered under different output and input conditions, which ensures high efficiency over wide operation range. The extra MOSFETs have low on-state resistance and cause less switching loss, thus, the power loss caused by these MOSFETs can be omitted. Furthermore, these components are not inserted into the circuit loop of the input capacitors and primary switches, which may reduce the voltage spike on the primary switches at turn-off instants. The VA rating of the primary switches and input capacitors is identical to that of conventional FB TL dc-dc converters, and the utilization of the DC link voltage is close to 100%. To evaluate the proposed converter, an industrial application example and some experimental results and are also provided.