Jun Cheng

Bio: Jun Cheng is an academic researcher from Zhejiang University. The author has contributed to research in topics: Switched capacitor & Electronic circuit. The author has an hindex of 1, co-authored 1 publications receiving 84 citations.

Multilevel Circuit Topologies Based on the Switched-Capacitor Converter and Diode-Clamped Converter

Abstract: The novel multilevel circuit topologies are proposed in this paper. They are called multilevel circuit topologies based on switched-capacitor and diode-clamped converters (MCT-BSD). The topology structure and the operation principle, including the working states' transitions of the diode-clamped part, the voltages balancing mechanism of the dc link capacitors, and the pulse width modulated carrier control strategy are given. The switched-capacitor circuits contribute not only to balancing the voltages of capacitors but also to boosting the output voltage with a certain input dc voltage. The validity of the MCT-BSD is verified by simulations and experiments. The results show that balancing the voltages of capacitors, boosting the output voltages, and operating under the three-phase condition are all realized effectively in the MCT-BSD. The simulations also show the generalization of the MCT-BSD for n-level topologies.

Review of Battery Charger Topologies, Charging Power Levels, and Infrastructure for Plug-In Electric and Hybrid Vehicles

Abstract: This paper reviews the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrids. Charger systems are categorized into off-board and on-board types with unidirectional or bidirectional power flow. Unidirectional charging limits hardware requirements and simplifies interconnection issues. Bidirectional charging supports battery energy injection back to the grid. Typical on-board chargers restrict power because of weight, space, and cost constraints. They can be integrated with the electric drive to avoid these problems. The availability of charging infrastructure reduces on-board energy storage requirements and costs. On-board charger systems can be conductive or inductive. An off-board charger can be designed for high charging rates and is less constrained by size and weight. Level 1 (convenience), Level 2 (primary), and Level 3 (fast) power levels are discussed. Future aspects such as roadbed charging are presented. Various power level chargers and infrastructure configurations are presented, compared, and evaluated based on amount of power, charging time and location, cost, equipment, and other factors.

Circulating Harmonic Current Elimination of a CPS-PWM-Based Modular Multilevel Converter With a Plug-In Repetitive Controller

Abstract: An improved circulating current control method by applying a digital plug-in repetitive controller is discussed for harmonic elimination of a carrier-phase-shift pulse-width-modulation (CPS-PWM)-based modular multilevel converter (MMC) in this paper. The performance of the controller is analyzed in detail based on an improved circulating current control model with the consideration of the submodule voltage disturbance. It is shown that the proposed control method has the merits of simplicity, versatility, and better performance of circulating harmonic current elimination than the traditional proportional integral controller. The stability analysis of the proposed method are also discussed in the paper as well as the design principles. Finally, the experimental results including the steady-state performance and the transient response are given, which validates the feasibility and excellent performance of the proposed control scheme.

A Switched-Capacitor-Based Active-Network Converter With High Voltage Gain

Abstract: The voltage gain of traditional boost converter is limited due to the high current ripple, high voltage stress across active switch and diode, and low efficiency associated with large duty ratio operation. High voltage gain is required in applications, such as the renewable energy power systems with low input voltage. A high step-up voltage gain active-network converter with switched-capacitor technique is proposed in this paper. The proposed converter can achieve high voltage gain without extremely high duty ratio. In addition, the voltage stress of the active switches and output diodes is low. Therefore, low voltage components can be adopted to reduce the conduction loss and cost. The operating principle and steady-state analysis are discussed in detail. A prototype with 20-40-V input voltage, 200-V output voltage, and 200-W output power has been established in the laboratory. Experimental results are given to verify the analysis and advantages of the proposed converter.

Multilevel SVPWM With DC-Link Capacitor Voltage Balancing Control for Diode-Clamped Multilevel Converter Based STATCOM

Abstract: In this paper, a space vector pulsewidth modulation (PWM) (SVPWM) algorithm is proposed, which is in α'β' frame with dc-link capacitor voltage equalization for diode-clamped multilevel converters (DCMCs). The α'β' frame is a coordinate system similar to the αβ frame. In this frame, some original complex calculations are substituted by integer additions, integer subtractions, truncations, etc. It brings the time and area efficiency to fixed-point digital realization, particularly for the application in a field-programmable gate array. Meanwhile, a minimum energy property of multiple dc-link capacitors is applied as the basic principle for voltage equalization based on a capacitor current prediction algorithm. By evaluating the redundant vectors in each pulse dwelling period, the balancing algorithm chooses an optimal vector, generates the optimal PWM signals, and sustains the voltage stability. After that, an arbitrary multilevel SVPWM intellectual property core is designed and analyzed in the α'β' frame. At the end of this paper, a five-level DCMC-based static synchronous compensator is built and tested. The experimental results verify the balancing algorithm and the system steady-state and dynamic performances.

Voltage Balancing Approaches for Diode-Clamped Multilevel Converters Using Auxiliary Capacitor-Based Circuits

Abstract: An auxiliary capacitor-based balancing approach is adopted in this paper to equalize the dc-link capacitor voltages of a diode-clamped multilevel converter (DCMC). Four balancing circuits, including the generalized, one-level-capacitor, one-capacitor, and simplified one-capacitor-based configurations are discussed for a five-level DCMC system. These configurations are different in connection of the auxiliary circuits and numbers of the capacitors and switches, but they work on the same principle called ping-pong operation by utilizing the auxiliary capacitor as an equalizer between the capacitors of different voltages. The unbalance phenomenon, ping-pong principle, circuit configurations, and their switching schemes are analyzed, respectively. The superiorities of the proposed approach include balancing operation regardless of load power factor and modulation index, control simplicity, and independence from main circuits when compared to the traditional approaches. Simulations and experimental results verified the performances using the proposed balancing circuits and control strategies.