Donglai Zhang

Interleaved Boost Converter with Ripple Cancellation Network

This paper presents an interleaved boost converter (IBC) with ripple cancellation network (RCN). Based on the conventional IBC, two capacitors, two coupled inductors, and two inductors are added as RCN in the proposed converter. Therefore, the proposed converter shares the same advantages of the conventional IBC and achieves input current ripple cancellation without significantly increasing the current stress and loss of the converter. Finally, a 36-V input voltage, 50-V output voltage, and 1-kW output power prototype circuit operating at 100 kHz is implemented in the laboratory to verify the expected performance. The proposed converter can achieve input current ripple cancellation in all power range with the efficiency higher than 96%. The simulation and experimental results show that the proposed IBC with RCN has great potential to be applied in high-power, high-efficiency dc/dc conversion.

Power and Voltage Balance Control of a Novel Three-Phase Solid-State Transformer Using Multilevel Cascaded H-Bridge Inverters for Microgrid Applications

This paper presents a new application of power and voltage balance control schemes for the cascaded H-bridge multilevel inverter (CHMI)-based solid-state transformer (SST) topology. To reduce load on the controller and simplify modulation algorithm, a master-slave control (MSC) strategy is designed for the dual active bridge (DAB) stage. The master controller executes all control and modulation calculations, and the slave controllers manage only device switching and protection. Due to the inherent power and dc-link voltage unbalance in cascaded H-bridge-based SST, this paper presents a compensation strategy based on three-phase dq decoupled current controller. An optimum zero-sequence component is injected in the modulation scheme so that the three-phase grid currents are balanced. Furthermore, to tightly regulate the output voltage of all the DAB modules to target value, a dynamic reference voltage method is also implemented. With this proposed control method, the three-phase grid currents and dc-link voltage in each module can be simultaneously balanced. Finally, simulation and experimental results are presented to validate the performance of the controller and its application to microgrid SST.

Input Current Ripple Cancellation Technique for Boost Converter Using Tapped Inductor

This paper presents a boost converter with a proposed tapped inductor ripple cancellation network. Based on the conventional boost converter (CBC), a small capacitor and a small inductor are added as the ripple cancellation network (RCN) in the proposed converter. Meanwhile, the tapped inductor can be easily realized by adding an extra tap in the main inductor of the CBC. Since the capacitor and inductor in the RCN do not need to handle the main power as the conventional LC input filter, the size and weight of the proposed converter are relatively small comparing the CBC with the LC input filter. The small signal and dynamic characteristics analyses show that the proposed converter has the same static and dynamic responses as the CBC, and the input current ripple cancellation can be achieved in all power ranges without significantly increasing the losses. Finally, three 36-50-V, 500-W prototypes operating at 100 kHz are implemented to verify the expected performance. The simulation and experimental results show that the proposed converters can achieve input current ripple cancellation with efficiency higher than 97.4% in all power ranges.

A Nonisolated Three-Port DC–DC Converter and Three-Domain Control Method for PV-Battery Power Systems

In order to interface one photovoltaic (PV) port, one bidirectional battery port, and one load port of a PV-battery dc power system, a novel nonisolated three-port dc/dc converter named boost bidirectional buck converter (B3C) and its control method based on three-domain control are proposed in this paper. The power flow and operating principles of the proposed B3C are analyzed in detail, and then, the dc voltage relation between three ports is deduced. The proposed converter features high integration and single-stage power conversion from both PV and battery ports to the load port, thus leading to high efficiency. The current of all three ports is continuous; hence, the electromagnetic noise can be reduced. Furthermore, the control and modulation method for B3C has been proposed for realizing maximum power point tracking (MPPT), battery management, and bus voltage regulation simultaneously. The operation can be transited between conductance mode and MPPT mode automatically according to the load power. Finally, experimental verifications are given to illustrate the feasibility and effectiveness of the proposed topology and control method.

Input/Output Current Ripple Cancellation and RHP Zero Elimination in a Boost Converter using an Integrated Magnetic Technique

This paper presents a novel integrated magnetic boost converter (IMBC) with both input/output current ripple cancellation and right-half-plane (RHP) zero elimination. The input inductor, output inductor, and the ripple cancellation network auxiliary inductor of the proposed IMBC have been integrated in one magnetic core. Two extra capacitors were added to achieve input and output current ripple cancellation. Therefore, the input current ripple of the IMBC dropped to one-twelfth of the original in a conventional boost converter, and the output current worked in continuous-conduction-mode with very small ripple. Meanwhile, the proposed IMBC has eliminated the RHP zero of the boost converter, which means higher bandwidth can be reached. The using of the integrated magnetic technique not only performs above advantages but also shows great potential for reducing the weight and volume of dc-dc converter. Finally, three 36 V input, 50 V output and 500 W prototypes operating at 100 kHz are implemented to verify the expected performance. The experimental results show that the proposed IMBC can achieve both input and output current ripple cancellation and RHP zero elimination with the maximum efficiency of 96.8%. All these advantages of the IMBC are very important especially in high dynamic response, high efficiency, and high-power application.

PV Isolated Three-Port Converter and Energy-Balancing Control Method for PV-Battery Power Supply Applications

A photovoltaic (PV)-based stand-alone power system is usually used to manage the energy supplied from several power sources such as PV solar arrays and battery and deliver a continuous power to the users in an appropriate form. Traditionally, three different dc/dc converters would have been used. To reduce the cost and improve the power density of the power system, an integrated solution of PV isolated dc/dc three-port converter (TPC) is proposed in this paper. Zero current switching can be achieved for all main diodes and MOSFETs to improve the efficiency, and a continuous input current of solar array is maintained by adding a magnetic switch derived from a fourth winding of the half-bridge transformer. Based on the energy-balancing part formed by boost, the control methods for the single module to realize maximum power point tracking (MPPT), battery charge control, and main bus regulation are proposed. The power system control method for multimodules in parallel is also derived, and the operation of the TPC power system can be transited between conductance mode and MPPT mode automatically. Finally, the experimental results verify that the proposed TPC, together with the proposed control method, meets the requirements of a high-power-density stand-alone PV-battery power system.

Influence of Multijunction Ga/As Solar Array Parasitic Capacitance in S3R and Solving Methods for High-Power Applications

This paper deals with the influence produced by the solar array parasitic capacitance and its solving methods in the sequential switching shunt regulator (S3R). Nowadays, the usage of triple-junction Ga/As solar cells with larger parasitic capacitance has prompted new problems about power losses, steady state, and dynamic response in the S3R, especially for high section current, voltage applications. Effects of parasitic capacitance on voltage ripple, “double sectioning,” phase margin, and output impedance are represented and analyzed, and turn-off delay caused by parasitic capacitance is mathematically modeled. A novel shunt regulator topology passive and active shunt regulator (PASR) with low switching losses, low mass, and short turn-off time delay is proposed. To further reduce the impact of delay, nonlinear control is added in the control loop, achieving better performances in the stability margin, output impedance, and dynamic performance. Simulation and experimental results are provided to validate the proposed PASR together with nonlinear control scheme.

A Novel Phase-Shift Dual Full-Bridge Converter With Full Soft-Switching Range and Wide Conversion Range

This paper proposes a novel phase-shift dual full-bridge converter with shared leading leg and dual outputs in series. Full soft-switching range of the active switches can be achieved based on the parallel full-bridge configuration of the converter, and the dual outputs of the proposed converter are connected in series. The output voltage can be regulated by primary-side phase-shift and secondary-side phase-shift dual-mode control scheme, and a wide conversion range can be achieved. Furthermore, the circulating current in the primary-side full-bridge circuits can be extinguished. Therefore, the proposed converter would be useful for constant peak power and wide output voltage range applications. Steady-state operation and relevant analysis results of the proposed converter are presented and verified on a 1.5-kW hardware prototype. The experimental results show that the proposed converter can achieve a peak efficiency of 95.3%.

Voltage Regulator Buck Converter with a Tapped Inductor for Fast Transient Response Application

In this letter, a novel voltage regulator buck converter with a tapped inductor for fast transient response applications is proposed. The output inductor of the conventional buck converter is replaced by a tapped inductor and an auxiliary switch to achieve fast transient response. Usually, the proposed converter works as a conventional buck converter with very large output inductance during the steady state to reduce the output current ripple. Once the transient load change appears, the auxiliary switch is turned ON in order to speed up the dynamic process by reducing the equivalent output inductance. A 10-V output voltage buck converter with maximum 30-A output current has been built and tested. The experimental results demonstrated the effectiveness of the proposed converter, which also means that the proposed method shows great potential for fast transient response voltage regulator applications.

Two-Phase Interleaved Inverse-Coupled Inductor Boost without Right Half Plane Zeros

This paper presents a novel two-phase interleaved inverse-coupled inductor boost (IICIB) without right half-plane (RHP) zeros. The input and output inductors in the IICIB have been all integrated into one magnetic core, and there is a 180° phase shift between the driving signals. Thanks to the coupling relationship between the four inductors in the new proposed converter, a smaller core size and higher power density can be achieved because the core size is normally determined by the energy storage requirement. Meanwhile, with the RHP zeros eliminate, a higher bandwidth with wide range of control over the applied input or output voltage can be achieved. The new converter not only has the aforementioned advantages, but also shows great potential for current ripple reduction as a result of the interleaved structure. Finally, experimental verification is provided to illustrate the effectiveness of the theoretical findings and design approaches.