A PWM plus phase-shift control bidirectional DC/DC converter is proposed. In this converter, PWM control and phase-shift control are combined to reduce current stress and both conducting and switching loss, to expand ZVS range. The operation principle and analysis of the converter are explained, and ZVS condition is derived. A prototype of PWM plus phase-shift bidirectional DC/DC converter is built to verify analysis.

A pwm plus phase-shift control bidirectional dc/dc converter

This paper analyzes the interleaved boost with coupled inductors (IBCI) converter, which is an isolated topology that is suitable for high step-up applications. Two main contributions are given: an exhaustive steady-state analysis and an accurate small-signal model. The former allows for deriving a closed-form noniterative design procedure for the power-stage active and passive components. In addition, it reveals an interesting equivalence with an apparently different converter, i.e., the single active bridge. Subsequently, the IBCI converter dynamic behavior is investigated, deriving a nonlinear average model that, under small-signal approximation, can be linearized around a given operating point and used for feedback controller design. A single photovoltaic module interface converter, rated for 300-W output power, is considered as a case study to validate the analysis outcome and the design procedure. Both are fully validated by measurements taken on the laboratory prototype.

Analysis of the Interleaved Isolated Boost Converter With Coupled Inductors

A high-frequency isolated bidirectional three-level dc–dc converter is proposed for high voltage applications. Direct current slew rate (DCSR) control of leakage inductance is proposed to minimize conduction loss and current stress in facing the load variation, the mismatch of turns ratio and circuit parasitic parameters. The mode analysis and the disadvantages of conventional PWM plus phase-shift (PPS) control are addressed while these disadvantages can be dealt with by the proposed control. Comprehensive comparison between conventional PPS control and the proposed DCSR control are made within the designed low voltage side (LVS) voltage range. Besides, the implementation of the proposed DCSR control is also given. With the proposed DCSR control, lower conduction loss, lower peak current, lower voltage spike over switches can be obtained in spite of the turns-ratio mismatch, load variation, and system parasitic parameters. Zero voltage switching (ZVS) can be achieved for all power switches in spite of the power flow direction. The effectiveness of the proposed DCSR control on the proposed topology is verified by simulation and experimental results.

A ZVS Bidirectional Three-Level DC–DC Converter With Direct Current Slew Rate Control of Leakage Inductance Current

A low-cost unidirectional dc/dc converter with galvanic isolation for fuel cell electric vehicles is presented in this article. To satisfy the requirements of the fuel cell stack and powertrain system of heavy-duty vehicles, three operation modes: boost, buck-boost, and buck, are proposed. To achieve ZVS operation for low voltage side switching devices, a novel platform current control mechanism is introduced. With the help of the platform current controller, the zero-voltage-switching operation is independent of the input/output voltage ratio. Meanwhile, the near zero-current-switching can be achieved for low voltage side switches under boost mode. The steady-state analyses and small-signal models for both input and platform currents under boost mode are provided. The prototype unit is built, and the corresponding experiments are presented.

A Wide Range Unidirectional Isolated DC-DC Converter for Fuel Cell Electric Vehicles

In this paper, a high voltage-gain bidirectional dc–dc converter is proposed with zero voltage switching (ZVS) and low circulating current for the interface between the energy storage system and dc microgrid bus. A current doubler is located in the low-voltage side (LVS), and a voltage doubler is located in the high-voltage side (HVS). Therefore, high voltage gain is accomplished without a transformer of the high turns ratio. The interleaved input structure is employed to reduce the current ripple and helps to achieve voltage matching (VM) on both sides of the transformer. In the view of decoupling pulsewidth modulation plus phase shift (PPS) control strategy with two control variables, the proposed topology can achieve VM and power control through the decoupling regulations of duty cycle and phase shift angle. By analyzing the resonant process during the dead time, a fixed delta is selected to generate a bias current for full-range ZVS with low circulation losses. The optimal design is given for component parameters to accomplish full-range soft switching and circulation loss reduction. An 800-W prototype of 48–60-V input and 240-V output is constructed with 30-kHz switching frequency to verify the effectiveness of the proposed converter and the associated control strategy. The accordance between the analysis and experimental results further testifies the advantages.

A High Voltage-Gain Bidirectional DC–DC Converter With Full-Range ZVS Using Decoupling Control Strategy

A novel interleaved high step-up converter is proposed in this paper to satisfy the high power and high step-up conversion requirements. The interleaved structure is applied to reduce the input and output current ripples, which is helpful to reduce the impact to the filter capacitors. A voltage gain extension cell based on the coupled inductors is introduced in the conventional interleaved boost converter to extend the conversion ratio and reduce the switch voltage stresses. Thus, low on-resistance switches can be applied to reduce the conduction losses. Moreover, the passive lossless clamp circuits are adopted to clamp the switch turn-off voltage spikes and recycle the leakage inductance energy. Furthermore, each coupled inductor not only works as a filter inductor, but also works as a transformer with a relatively low magnetizing inductance, which benefits to reduce the volume of the magnetic cores. Finally, a 48V-input 380V-output 1kW prototype is built to demonstrate the theoretical analysis.

Performance analysis of interleaved boost converter with voltage gain extension cell

A novel isolated zero-voltage-switching (ZVS) bidirectional DC-DC converter (BDC) with coupled inductors is proposed in this paper. The series half bridge structure in the high-voltage side reduces the switch voltage stress to half of the high-side voltage, which extends the high-side voltage when using power MOSFETs. Furthermore, all the switches can achieve ZVS soft-switching performance at any load condition by adopting the active clamp circuits and the PWM plus phase shift (PPS) control strategy. Thus, the BDC can operate at high frequency to achieve high power density and still with high efficiency for high voltage dc bus applications. Finally, a 1.5kW 100kHz 48V/800V prototype is built to verify the effectiveness of the proposed circuit.

Performance analysis of a ZVS bidirectional DC-DC converter with reduced voltage stress on high voltage side

The circuit performance of the Phase-shift (PS) and PWM plus phase-shift (PPS) control schemes is compared in this paper to optimize the bidirectional conversion efficiency. The comparison is implemented with the isolated winding-coupled zero voltage switching (ZVS) bidirectional DC-DC converter (BDC). The theoretical analysis, simulation and experimental results show that the PPS control strategy is an optimal case of the PS control when the low-side voltage and high-side voltage is matched. Furthermore, the PPS control can enhance the capability of the power transmission and reduce the current stress of the power switches compared with PS control. Moreover, ZVS operation can be realized from no load to full load with PPS control scheme. However, there is one case in PS control, where ZVS operation is not reached. Finally, the experimental results prove that the efficiency with PPS scheme is higher than that with PS scheme. The conclusions can be extended to other PS and PPS controlled BDCs.

Performance comparison of Phase-shift (PS) and PWM plus Phase-shift (PPS) control schemes for bidirectional DC-DC converters

When operating in island mode, DC-based microgrid mainly starts up through batteries and bidirectional DC-DC converters. In conventional way, an extra start-up circuit is required to limit the surge current, which not only decreases the efficiency but also increases the cost. In this paper, the generation mechanism of the surge current is analyzed, through which the duty cycle control scheme is proposed. Without an auxiliary start-up circuit, the converter can safely start up with controllable peak current value by using this method. Detailed analysis and formula derivation of the scheme in different operation modes are presented and the simulation and experimental results are exhibited to verify the effectiveness of the scheme, which provides a simple, safe and economic way for black start-up.

http://ieeexplore.ieee.org/iel7/6926643/6953358/06953814.pdf

Hongbin Yu

Papers

Performance analysis of interleaved boost converter with voltage gain extension cell

Performance analysis of a ZVS bidirectional DC-DC converter with reduced voltage stress on high voltage side

Performance comparison of Phase-shift (PS) and PWM plus Phase-shift (PPS) control schemes for bidirectional DC-DC converters

Duty cycle-based start-up control for a ZVS bidirectional DC-DC converter