EMI Noise Source Reduction of Single-Ended Isolated Converters Using Secondary Resonance Technique

Chen, Zhangyong,Chen, Yong,Chen, Qiang,Jiang, Wei,Zhong, Rongqiang The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

Aiming at the problems of large dv/dt and di/dt in traditional single-ended converters and high electromagnetic interference (EMI) noise levels, a single-ended isolated converter using the secondary resonance technique is proposed in this paper. In the proposed converter, the voltage stress of the main power switch can be reduced and the voltage across the output diode is clamped to the output voltage when compared to the conventional flyback converter. In addition, the peak current stress through the main power switch can be decreased and zero current switching (ZCS) of the output diode can be achieved through the resonance technique. Moreover, the EMI noise coupling path and an equivalent model of the proposed converter topology are presented through the operational principle of the proposed converter. Analysis results indicate that the common mode (CM) EMI noise and the differential mode (DM) EMI noise of such a converter are deduced since the frequency spectra of the equivalent controlled voltage sources and controlled current source are decreased when compared with the traditional flyback converter. Furthermore, appropriate parameter selection of the resonant circuit network can increase the equivalent impedance in the EMI coupling path in the low frequency range, which further reduces the common mode interference. Finally, a simulation model and a 60W experimental prototype of the proposed converter are built and tested. Experimental results verify the theoretical analysis.

An Improved Model Predictive Direct Speed Control with Synchronous Prediction and Weight Factor Optimization for PMSM Application

Chen Zhangyong,Xiao Fangbo,Chen Yong,Tang Weihan,Chen Zhiyuan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

In permanent magnet synchronous motor (PMSM) application, model predictive direct speed control is usually utilized to eliminate cascade loop structure existed in traditional vector control. However, asynchronous prediction equation (ASPE) with one-step delay is mostly required to achieve optimal voltage vector to drive the PMSM motors, which exist the problem of asynchronous prediction of speed and current. It is shown that in this paper the synchronous prediction equation (SPE) does not have the prediction delay, but it cannot realize the speed tracking control. Aim to solve the above problems, an improved PMSM model predictive direct speed control with synchronous prediction and Weight factor optimization is proposed in this paper. Firstly, the Taylor synchronization prediction equation (TSPE) is used to realize the speed and current prediction synchronization and the speed tracking control. Secondly, in order to improve the response speed of the system, a quadratic cost function considering the weight factor optimization is used for cost evaluation, and the Lyapunov direct method is used to design the weight factor with taking into account the stability and rapidity of the system. Finally, in order to verify the effectiveness of the proposed method, the MATLAB simulation and hardware-in-the-loop experiments are carried out. The results show that the proposed control method achieves predictive synchronous between speed and current, fast and stable speed tracking control, and the setting time is faster than the ASPE, and the TSPE without considering the weight factor.

IPOS three-state boost converter and its volt-second balance method based output voltage sharing control strategy for bipolar DC bus applications

Chen, Zhangyong,Feng, Chenchen,Chen, Gen,Chen, Yong,Zhu, Xintong The Korean Institute of Power Electronics 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9

The bipolar DC bus configuration has been widely used in DC nano-grids due to its flexibility and stability. Input-parallel-output-series (IPOS) converters are utilized in bipolar DC bus and RES applications due to their simple structure. However, there is a big challenge with this structure. To ensure system safety and stability, the two output voltages of an IPOS converter need to be balanced. On this basis, an IPOS three-state boost converter with a balanced output voltage is proposed in this paper. At the same time, output voltage balance can be obtained by adjusting the duration of the three-state converter based on the volt-second balance method. In the proposed strategy, a switch series diode is added to the IPOS Boost converter topology, and the voltage across the main inductor can be changed through one degree of freedom, where the corresponding output voltage is regulated due to a change in inductor voltage. In addition, under different dead time conditions, adjusting the gate drive of the switch can be used to achieve voltage balance. Moreover, a comprehensive analysis and relative calculations are provided. Finally, a 20-200 V prototype is built to verify the analysis.

Asymmetrical Pulse-Width-Modulated Full-Bridge Secondary Dual Resonance DC–DC Converter

Zhangyong Chen,Qun Zhou,Jianping Xu,Xiang Zhou 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

A full-bridge secondary dual-resonant DC?DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.

Asymmetrical Pulse-Width-Modulated Full-Bridge Secondary Dual Resonance DC-DC Converter

Chen, Zhangyong,Zhou, Qun,Xu, Jianping,Zhou, Xiang The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

A full-bridge secondary dual-resonant DC-DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.

ZVT Series Capacitor Interleaved Buck Converter with High Step-Down Conversion Ratio

Chen, Zhangyong,Chen, Yong,Jiang, Wei,Yan, Tiesheng The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

Voltage step-down converters are very popular in distributed power systems, voltage regular modules, electric vehicles, etc. However, a high step-down voltage ratio is required in many applications to prevent the traditional buck converter from operating at extreme duty cycles. In this paper, a series capacitor interleaved buck converter with a soft switching technique is proposed. The DC voltage ratio of the proposed converter is half that of the traditional buck converter and the voltage stress across the one main switch and the diodes is reduced. Moreover, by paralleling the series connected auxiliary switch and the auxiliary inductor with the main inductor, zero voltage transition (ZVT) of the main switches can be obtained without increasing the voltage or current stress of the main power switches. In addition, zero current turned-on and zero current switching (ZCS) of the auxiliary switches can be achieved. Furthermore, owing to the presence of the auxiliary inductor, the turned-off rate of the output diodes can be limited and the reverse-recovery switching losses of the diodes can be reduced. Thus, the efficiency of the proposed converter can be improved. The DC voltage gain ratio, soft switching conditions and a design guideline for the critical parameters are given in this paper. A loss analysis of the proposed converter is shown to demonstrate its advantages over traditional converter topologies. Finally, experimental results obtained from a 100V/10V prototype are presented to verify the analysis of the proposed converter.

Model Predictive Controlled Dual Active Bridge Converter with Efficiency Optimization and Fast Dynamic Response

Chen Zhangyong,Zheng Zhanchao,Tang Xuan,Wu Yunfeng 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

In this paper, combine hybrid modulation strategy and Model predictive control (MPC) for Dual active bridge (DAB) converter is presented to achieve high efciency of wide load range and fast dynamic response for bidirectional power fow conversion. Through ofine optimization of DAB converter at steady state, only one control variable is used to reduce computational burden, and without complex algorithm in the cost function for MPC strategy. In addition, based on the simpilifed average mode of DAB converter, diferent predictive currents are derived. Besides, three scenarios of smooth mode transition for the hybrid control strategy is given in detail. Thus, fast dynamic response for mode transition and high efciency for wide range is guaranteed by the proposed strategy. Finally, an experimental prototype of DAB converter is built and tested for verifying the steady state and fast transition with diferent operation modes performance.

Soft switching high step-down series-capacitor based converter with coupled-inductor technique

Chen, Zhangyong,Chen, Yong,Zhang, Chenyu,Wu, Yunfeng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4

High voltage step-down converters are very popular in distributed power systems, voltage regular modules, automatic vehicles, etc. To avoid extreme duty cycles, a series capacitor-based buck converter with a coupled inductor is proposed in this paper. In this converter, the voltage stresses of the power switches are clamped to half of the input voltage. Thus, low voltage rating MOSFETs with a low R_ds,on could be utilized to improve the performance of the proposed converter. Moreover, synchronous MOSFETs are also used to reduce the conduction losses of the switches. Zero voltage switching (ZVS) for the main power switches is achieved using the coupled-inductor technique. In addition, through adding a bypass flowing path, a negative current is established to guarantee the ZVS condition of the power switches. The operating principle of the proposed converter is described in this paper, and the DC voltage gain ratio, automatic current sharing, soft switching condition and design guideline of the critical parameters are also given. Finally, experimental results obtained from a 60 V/200 W prototype are presented to verify the analysis of the proposed converter.

Voltage Gain Neutral-Point Shifter Converter With Step-Up/Down Capability for Wide Voltage Range Application

Chen Zhangyong,Shen Lanxiao,Liu YuLang,Wu Yunfeng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

In order to solve the problem of poor performance of traditional step-up/down converter, a novel converter with voltage gain neutral-point shifter is proposed in this paper. Compare to traditional buck-boost converter, only one series-capacitor is externally added. The coupling capacitor in proposed converter is series connected in charging power path, and therefore, the voltage stress of switches is reduced. Furthermore, when appropriately adjusting the duty cycle, half voltage stress of conventional buck-boost converter can be obtained. By using interleaved control strategy, the proposed converter has lower inductor current ripple and also has the character of higher step-down conversion ratio without any other auxiliary circuit. Moreover, the inherent current sharing character could be achieved when the duty cycle of main switch is less than 0.5. Based on these merits, the efficiency of the proposed converter can be improved. In this paper, the operational principle, the related analysis including inductor current ripple and voltage stress analysis, loss comparison analysis of the proposed converter are given. Finally, experimental prototype with 72 W is established to verify the character of the proposed converter.

Improved hybrid fixed-frequency modulation strategy for series resonant converters for wide range applications

Zhu, Xintong,Chen, Zhangyong,Chen, Yong,Chen, Gen,Feng, Chenchen The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.9

In recent years, resonant converters have been widely used in the fields of electric vehicles and renewable energy systems due to their excellent characteristics in terms of high energy density, high energy efficiency, wide output range, and wide ZVS range. Conventional resonant converters generally adopt pulse frequency modulation (PFM) in a wide range of output applications. This means the frequency varies over a wide range, which results in problems such as high switch loss, large noise, and high EMI. To solve this problem, this paper proposes a hybrid fixed-frequency modulation strategy applied to a wide range of outputs based on the series resonant converter, where asymmetrical voltage-cancellation control (AVC control) and its improved strategy (IAVC control) are applied in the normalized gain ranges of [0.5, 1] and [0, 0.5]. The proposed modulation strategy achieves lower switching loss, higher efficiency, and better ZVS characteristics in wide voltage output and load ranges. Under the same output voltage and power, to realize ZVS, the proposed hybrid modulation has a smaller switching frequency and resonant current, which improves efficiency and reduce losses, especially in the case of low voltage gain and light load conditions. Finally, experimental data obtained from an 80 V input and a 800 W power max prototype circuit are included to verify the proposed hybrid modulation strategy.