Silicon carbide (SiC) power devices have been investigated extensively in the past two decades, and there are many devices commercially available now. Owing to the intrinsic material advantages of SiC over silicon (Si), SiC power devices can operate at higher voltage, higher switching frequency, and higher temperature. This paper reviews the technology progress of SiC power devices and their emerging applications. The design challenges and future trends are summarized at the end of the paper.

https://ieeexplore.ieee.org/ielaam/41/8031005/7815312-aam.pdf

Review of Silicon Carbide Power Devices and Their Applications

This paper contributes to the steady-state analysis of the bidirectional dual active bridge (DAB) dc-dc converter by proposing a new model that produces equations for rms and average device currents, and rms and peak inductor/transformer currents. These equations are useful in predicting losses that occur in the devices and passive components and aid in the converter design. An analysis of zero-voltage switching (ZVS) boundaries for buck and boost modes while considering the effect of snubber capacitors on the DAB converter is also presented. The proposed model can be used to predict the converter efficiency at any desired operating point. The new model can serve as an important teaching-cum-research tool for DAB hardware design (devices and passive components selection), soft-switching-operating range estimation, and performance prediction at the design stage. The operation of the DAB dc-dc converter has been verified through extensive simulations. A DAB converter prototype was designed on the basis of the proposed model and was built for an aerospace energy storage application. Experimental results are presented to validate the new model for a 7 kW, 390/180 V, 20 kHz converter operation and the ZVS boundary operation.

High-Power Bidirectional DC–DC Converter for Aerospace Applications

Aiming for converters with high efficiency and high power density demands converter topologies with zero-voltage switching (ZVS) capabilities. This letter shows that in order to determine whether ZVS is provided at a given operating point, the stored charge within the mosfet s has to be considered and the condition $L I^2 \geq 2Q_\text{oss} V_\text{DC}$ has to be fulfilled. In the case of incomplete soft switching, nonzero losses occur which are analytically derived and experimentally verified in this letter. Furthermore, the issue of nonideal soft-switching behavior of Si superjunction mosfet s is addressed.

ZVS of Power MOSFETs Revisited

This study deals with the optimal control of hybrid energy storage systems for electric vehicle applications. These storage systems can capitalize on the high specific energy of Lithium-Ion batteries and the high specific power of modern ultracapacitors. The new predictive algorithm uses a state-based approach inspired by power systems optimization, organized as a probability-weighted Markov process to predict future load demands. Decisions on power sharing are made in real time, based on the predictions and probabilities of state trajectories along with associated system losses. Detailed simulations comparing various power sharing algorithms are presented, along with converter-level simulations presenting the response characteristics of power sharing scenarios. The full hybrid storage system along with the mechanical drivetrain is implemented and validated experimentally on a 500 W, 50 V system with a programmable drive cycle having a strong regenerative component. It is experimentally shown that the hybrid energy storage system runs more efficiently and captures the excess regenerative energy that is otherwise dissipated in the mechanical brakes due to the battery's limited charge current capability.

Predictive Algorithm for Optimizing Power Flow in Hybrid Ultracapacitor/Battery Storage Systems for Light Electric Vehicles

A switched-capacitor bidirectional dc–dc converter with a high step-up/step-down voltage gain is proposed for electric vehicles with a hybrid energy source system. The converter presented has the advantages of being a simple circuit, a reduced number of components, a wide voltage-gain range, a low voltage stress, and a common ground. In addition, the synchronous rectifiers allow zero voltage switching turn-on and turn-off without requiring any extra hardware, and the efficiency of the converter is improved. A 300 W prototype has been developed, which validates the wide voltage-gain range of this converter using a variable low-voltage side (40–100 V) and to give a constant high-voltage side (300 V). The maximum efficiency of the converter is 94.45% in step-down mode and 94.39% in step-up mode. The experimental results also validate the feasibility and the effectiveness of the proposed topology.

/pdf/a-switched-capacitor-bidirectional-dc-dc-converter-with-wide-4fru054evl.pdf

A Switched-Capacitor Bidirectional DC–DC Converter With Wide Voltage Gain Range for Electric Vehicles With Hybrid Energy Sources

A new prototype of a secondary-side phase shift soft-switching PWM dc-dc converter suitable for electric vehicle battery charging systems is presented in this paper. Wide range soft-switching operations are achievable from full load to no load by effectively utilizing the parasitic inductances of the high frequency transformer in the proposed dc-dc converter. In addition, no circulating current occurs in both of the primary and secondary side full-bridge circuits; thereby, the related idling power can be minimized. As a result, high efficiency power conversion can be maintained owing to the full range soft-switching operation and wide range output power and voltage regulations. Its operating principle is presented on the basis of theoretical analysis and simulation results, and the design procedure of the circuit parameters of the proposed dc-dc converter is described. The essential performance and its effectiveness of the proposed dc-dc converter are originally demonstrated from a practical point of view in an experiment using a 1 kW-50 kHz laboratory prototype.

/pdf/a-high-frequency-link-secondary-side-phase-shifted-full-2y1slgybhe.pdf

A High Frequency-Link Secondary-Side Phase-Shifted Full-Range Soft-Switching PWM DC–DC Converter With ZCS Active Rectifier for EV Battery Chargers

This paper presents a feasibility investigation of a zero-voltage switching (ZVS) pulsewidth modulation (PWM) dc-dc converter with secondary-side phase-shifting power control scheme. The ZVS-PWM dc-dc converter treated here can achieve soft commutation in all the power devices under the wide range of output power variation. By the phase-shifting control that is based on the secondary-side rectifier linked with a high-frequency planar transformer, the effective reduction of idling power in the primary-side inverter as well as snubber-less rectifications in the secondary-side rectifier can be actually attained. The essential experimental data obtained from a 100-kHz/2.5-kW prototype are described herein to validate the soft-switching circuit and control scheme, and then the effectiveness of the dc-dc converter is discussed and evaluated from a practical point of view.

Practical Evaluations of a ZVS-PWM DC–DC Converter With Secondary-Side Phase-Shifting Active Rectifier

A novel soft-switching high-frequency (HF) resonant (HF-R) inverter for induction heating (IH) applications is presented in this paper. By adopting the current phasor control of changing a phase shift (PS) angle between two half-bridge inverter units, the IH load resonant current can be regulated continuously under the condition of wide-range soft-switching operations. In addition to this, the dual-mode power regulation scheme-based PS angle control and asymmetrical pulsewidth modulation in one inverter unit is proposed for improving the efficiency in low output power settings. The essential performances on the output power regulation and soft-switching operations are demonstrated in an experiment using its 1-kW 60-kHz HF-R inverter prototype, and then, the topological validity is evaluated from a practical point of view.

/pdf/a-new-current-phasor-controlled-zvs-twin-half-bridge-high-15e52kv62g.pdf

A New Current Phasor-Controlled ZVS Twin Half-Bridge High-Frequency Resonant Inverter for Induction Heating

In recent years, energy storage systems assisted by super capacitor have been widely researched and developed to progress power systems for the electronic vehicles. In this paper, a full-bridge/push-pull circuit-based bidirectional DC-DC converter and its control methods are proposed. From the results of detailed experimental demonstration, the proposed system is able to perform adequate charge and discharge operation between low-voltage high-current super capacitor side and high-voltage low-current side with drive train and main battery. Furthermore, conduction losses and voltage/current surge are drastically reduced by ZVS operation with loss-less snubber capacitor in high voltage side as well as the synchronous rectification in low-voltage high-current super capacitor side.

Bidirectional DC-DC Converter with Full-bridge / Push-pull circuit for Automobile Electric Power Systems

This paper presents a novel soft-switching half-bridge dc-dc converter with high-frequency link. The newly proposed soft-switching dc-dc converter consists of a single-ended half-bridge inverter controlled by an asymmetrical pulsewidth-modulation scheme and a center-tapped diode rectifier. In order to attain the wide range of soft commutation under constant switching frequency, the single active edge-resonant snubber cell composed of a lossless inductor and a switched capacitor is employed for the half-bridge inverter leg, providing and assisting zero-current-switching operations in the switching power devices. The practical effectiveness of the proposed soft-switching dc-dc converter is demonstrated by the experimental results from an 800 W - 55 kHz prototype. In addition, the feasibility of the dc-dc converter topology is proved from the viewpoints of the high efficiency and high power density.

Tomokazu Mishima

Papers

A High Frequency-Link Secondary-Side Phase-Shifted Full-Range Soft-Switching PWM DC–DC Converter With ZCS Active Rectifier for EV Battery Chargers

Practical Evaluations of a ZVS-PWM DC–DC Converter With Secondary-Side Phase-Shifting Active Rectifier

A New Current Phasor-Controlled ZVS Twin Half-Bridge High-Frequency Resonant Inverter for Induction Heating

Bidirectional DC-DC Converter with Full-bridge / Push-pull circuit for Automobile Electric Power Systems

A Novel High-Frequency Transformer-Linked Soft-Switching Half-Bridge DC–DC Converter With Constant-Frequency Asymmetrical PWM Scheme