Search Results (10)

A battery charger for solid-state lithium battery packs was developed and implemented. The power stage used a phase-shifted full-bridge converter integrated with a current-doubler rectifier and synchronous rectification. Dual voltage and current control loops were employed to enable constant-voltage and constant-current charging modes. To improve the lifespan of the output filter capacitor, the current-doubler rectifier was adopted to effectively reduce output current ripple. During the initial start-up phase, as the charger transitions from constant-voltage to constant-current output mode, the use of proportional–integral control in the voltage and current loop error amplifiers may cause current overshoot during the step-rising phase, primarily due to the integral action. Therefore, this study incorporated fuzzy control, proportional control, and proportional–integral control strategies into the current-loop error amplifier. This approach effectively reduced the current overshoot during the step-rising phase, preventing the charger from mistakenly triggering the overcurrent protection mode. The analysis and design considerations of the proposed circuit topology and control loop are presented. Experimental results agree with theoretical predictions, thereby confirming the validity of the proposed approach. Full article

The paper presents a study on a phase-shift controlled zero-voltage switching (ZVS) full-bridge DC-DC converter employing synchronous rectification using the LTC3722-1 controller. This analysis aimed to examine the impact of additional commutating inductance on the establishment of ZVS conditions, the precision of switching control, and the dynamic interaction between ZVS performance and varying load conditions. The validity of this approach is achieved by presenting both simulation and experimental results, which illustrate its application in practical applications. Full article

This study presents a hard-switching full-bridge DC-DC converter with synchronous rectification based on Gallium Nitride (GaN) transistors to evaluate the advantages of GaN devices in power supplies. In comparison to traditional silicon-based devices, GaN transistors are utilized in both the primary and secondary stages of the converter, exploiting GaN’s lower on-resistance to enhance performance. The converter operates at a switching frequency of 300 kHz, with an input voltage range of 36 V to 75 V, delivering an output of 28 V/42 A. Experimental results show that the GaN-based converter achieves an output power of 1176 W within standard half-brick package dimensions. The measured peak efficiency is 97.1%, and the power density reaches 430 W/in³. These findings demonstrate that GaN-based converters offer superior efficiency and power density compared to conventional silicon-based designs, making them highly suitable for aerospace, automotive, and communication power supplies. Full article

Automotive-grade GaN power switches have recently been made available in the market from a growing number of semiconductor suppliers. The exploitation of this technology enables the development of very efficient power converters operating at much higher switching frequencies with respect to components implemented with silicon power devices. Thus, a new generation of automotive power components with an increased power density is expected to replace silicon-based products in the development of higher-performance electric and hybrid vehicles. 650 V GaN-on-silicon power switches are particularly suitable for the development of 3–7 kW on-board battery chargers (OBCs) for electric cars and motorcycles with a 400 V nominal voltage battery pack. This paper describes the design and implementation of a 6.6 kW OBC for electric vehicles using automotive-grade, 650 V, 25 mΩ, discrete GaN switches. The OBC allows bi-directional power flow, since it is composed of a bridgeless, interleaved, totem-pole PFC AC/DC active front end, followed by a dual active bridge (DAB) DC-DC converter. The OBC can operate from a single-phase 90–264 Vrms AC grid to a 200–450 V high-voltage (HV) battery and also integrates an auxiliary 1 kW DC-DC converter to connect the HV battery to the 12 V battery of the vehicle. The auxiliary DC-DC converter is a center-tapped phase-shifted full-bridge (PSFB) converter with synchronous rectification. At the low-voltage side of the auxiliary converter, 100 V GaN power switches are used. The entire OBC is liquid-cooled. The first prototype of the OBC exhibited a 96% efficiency and 2.2 kW/L power density (including the cooling system) at a 60 °C ambient temperature. Full article

When an inductive power transfer (IPT) system conducts wireless charging for electric cars, the coupling coefficient between the coils is easily affected by fluctuations in the external environment. With frequent changes in the battery load impedance, it is difficult for the IPT system to achieve constant-voltage and constant-current (CVCC) controls. A CVCC control method is proposed for the IPT system that has a double-sided LCC compensation structure based on full-bridge synchronous rectification. The proposed method achieved good dynamic stability and was able to effectively switch between the output current and voltage of the system by adjusting only the duty cycle of the switch on the secondary side of the rectification bridge. As a result, the system efficiency was improved. The output characteristics of the double-sided LCC compensation structure was derived and the conduction condition with zero voltage was analyzed by using four switches through two conduction time series of the rectifier circuit. Then, the output voltage of the synchronized rectifier was derived. The hardware implementation of the full-bridge controllable rectifier was described in detail. Finally, a MATLAB/Simulink 2018a simulation model was developed and applied to an 11 kW prototype to analyze and validate the design. The results showed that the designed system had good CVCC output characteristics and could maintain constant output under certain coupling offsets. Compared with semi synchronous rectification methods, the proposed method had a higher efficiency, which was 95.6% at the rated load. Full article

Efficient and robust power electronic converters are vital to the success of the electrification of aircraft. Especially, low voltage auxiliary converters, which usually supply high current and low voltage loads, are not readily available industrially and need special attention. In terms of energy density and efficiency, LLC converters are among the most commonly used and efficient topologies for automotive and aerospace applications. In the case of aerospace applications, a fault-tolerant topology is highly desirable to reduce the need for redundant components and weight by removing backup systems. To solve this issue, this study introduces a new 2.0 kW LLC-based converter with a reconfigurable fault-tolerant architecture. With the help of a specially designed secondary side, the proposed converter can reconfigure itself so that even if one of the semiconductor switches fails permanently, the converter can still maintain power at nominal voltage levels, ensuring that the aircraft’s vital functionality is preserved. This paper also describes the basic operation principle, component-design aspects, conduction loss reduction techniques, and control system algorithm. Finally, a 2.0 kW experimental prototype is built to verify and demonstrate the operation of the proposed reconfigurable LLC converter. Full article

In this study, an adaptive driving method for synchronous rectification in bidirectional full-bridge LLC resonant converters used in railway applications is proposed. The drain to source voltage of the synchronous rectifier is utilized to detect the conduction of the body diode, and a suitable driving signal for synchronous rectification is generated accordingly. The proposed driving scheme is simple and can be realized using a low-cost digital signal processor (DSP). According to the experimental results, which averaged 0.4625% and 1.097%, improvement can be observed under charging and discharging mode, respectively. Full article

A novel circuit topology for an on-board battery charger for plugged-in electric vehicles (PEVs) is presented in this paper. The proposed on-board battery charger is composed of three H-bridges on the primary side, a high-frequency transformer (HFT), and a current doubler circuit on the secondary side of the HFT. As part of an electric vehicle (EV) on-board charger, it is required to have a highly compact and efficient, lightweight, and isolated direct current (DC)–DC converter to enable battery charging through voltage/current regulation. In this work, performance characteristics of full-bridge phase-shift topology are analyzed and compared for EV charging applications. The current doubler with synchronous rectification topology is chosen due to its wider-range soft-switching availability over the full load range, and potential for a smaller and more compact size. The design employs a phase-shift full-bridge topology in the primary power stage. The current doubler with synchronous recitation is placed on the secondary. Over 92% of efficiency is achieved on the isolated charger. Design considerations for optimized zero-voltage transition are disused. Full article

This study presents a new bidirectional multi-resonant DC-DC converter, which is named CLTC. The converter adds an auxiliary transformer and an extra resonant capacitor based on a LLC resonant DC-DC converter, achieving zero-voltage switching (ZVS) for the input inverting switches and zero-current switching (ZCS) for the output rectifiers in all load range. The converter also has a wide gain range in two directions. When the load is light, a half-bridge configuration is adopted instead of a full-bridge configuration to solve the problem of voltage regulation. By this method, the voltage gain becomes monotonous and controllable. Besides, the digital synchronous rectification strategy is proposed in forward mode without adding any auxiliary circuit. The conduction time of synchronous rectifiers equals the estimation value of body diodes’ conduction time with the lightest load. Power loss analysis is also conducted in different situations. Finally, the theoretical analysis is validated by a 5 kW prototype. Full article

Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS) and Zero Voltage Switching (ZVS) in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains. Full article