Bidirectional Power Flow Control Research Articles

Analysis, design and implementation of fuzzy logic controlled quasi-resonant zero-current switching switched-capacitor bidirectional converter

The proposed fuzzy logic controlled (FLC) system can be considered as a soft switching technique that substantially reduces the switching loss and hence attains higher efficiency by the switching capacitor converter. The proposed frequency modulation FLC quasi-resonant zero-current switching switched-capacitor (SC) converter is a new type of bidirectional power flow control conversion scheme. This device provides voltage conversion ratios from double-mode against half-mode to n-mode against 1/n-mode by adding a different number of SCs and power semiconductor switches with a small series-connected resonant inductor for forward and reverse schemes. The state-space modelling and analysis for the designed FLC take advantage of cybernetics theory. The dynamic simulation and experiments for the proposed FLC for the studied converters are used to demonstrate the validity of the constructed model under different energy conversion topologies and load conditions.

Multiple output zero-current switching switched-capacitor bidirectional dc–dc converter

The proposed circuit is a multiple output quasi-resonant (QR) zero-current switching (ZCS) switched-capacitor (SC) converter with a bidirectional power flow control conversion scheme. The principles of the proposed multiple output QR ZCS SC bidirectional dc–dc converter are described using a detailed circuit model for analysis. Simulation and experimental results are carried out to verify the validity and the soft switching performance of the proposed converter. The maximum efficiency achievable is about 94 and 92% for the forward and reverse power flow control schemes, respectively. The output voltage can be regulated by changing the switching frequency for the designed compensated closed-loop controller.

Switched-capacitor bi-directional converter performance comparison with and without quasi-resonant zero-current switching

The proposed quasi-resonant (QR) zero-current switching (ZCS) switched-capacitor (SC) converter is a new type of bi-directional power flow control conversion scheme. This device provides voltage conversion ratios from 2 against 1/2 (double-mode/half-mode) to n against 1/n (n-mode/1/n-mode) by adding a different number of SCs and power multi-oxide-semiconductor field-effect-transistor (MOSFET) switches with a small series-connected resonant inductor for forward and reverse schemes. The proposed QR SC converter presents low current stress and balanced resonant current advantages. The operating principle and theoretical analysis of the proposed bi-directional power conversion scheme are described in detail with circuit model analysis. The proposed device is compared with the conventional SC converter. Simulations and experimental verification are carried out to verify and compare the proposed QR ZCS SC bi-directional converter performance with the conventional device. At maximum efficiency, the proposed device can achieve 96% and 93% for the forward and reverse power flow control schemes, respectively.

Inverting Quasi-Resonant Switched-Capacitor Bidirectional Converter and Its Appication to Battery Equalization

The proposed quasi-resonant (QR) zero current switching (ZCS) switched-capacitor (SC) converter is a new type of bidirectional power flow control conversion scheme. The proposed converter is able to provide voltage conversion ratios from $-$3/$-$${1 \over 3}$ (triple-mode/trisection-mode) to $-n/-$${1 \over n}$ ($-$n-mode/$-$${1 \over n}$-mode) by adding a different number of switched-capacitors and power MOSFET switches with a small series connected resonant inductor for forward and reverse power flow control schemes. It possesses the advantages of low switching losses and current stress in this QR ZCS SC converter. The principle of operation, theoretical analysis of the proposed triple-mode/trisection-mode bidirectional power conversion scheme is described in detail with circuit model analysis. Simulation and experimental studies are carried out to verify the performance of the proposed inverting type ZCS SC QR bidirectional converter. The proposed converters can be applied to battery equalization for battery management system (BMS).

Reduced Switch-Count Six-Phase AC Motor Drive Systems Without Input Reactor

In this paper, two reduced switch-count six-phase ac motor drives are investigated. The first configuration considered has six legs (configuration 6L), and the second one has five legs (configuration 5L) and uses the capacitor dc-link midpoint connection. Both configurations operate without input reactors and provide both bidirectional power flow and power-factor control. Both 60 and 30 six-phase induction-machine windings are employed. Operating principles and control strategies for the topologies are presented. The proposed configurations are compared with the full-bridge (nine legs) and the half-bridge (six legs) topologies, which use the capacitor dc-link midpoint connection. These drive systems are suitable for applications where the size of the system is a critical factor. Experimental and simulation results are presented.

Single-Phase-Input Reduced-Switch-Count AC–AC Drive Systems

In this paper, two AC-AC reduced-switch-count drive systems for single- to three-phase applications are proposed. Both drive systems provide bidirectional power flow and power factor control. The operating principles of the topologies are presented, and a control strategy is proposed in order to reduce the DC-link voltage required by the converters. Moreover, the proposed configurations are compared with the conventional half-bridge (three legs) and full-bridge (five legs) topologies. These drive systems have the potential for reducing price and are suitable for applications in which the size of the system is a critical factor. Experimental and simulated results are presented.

Bidirectional power flow control of a power converter using passive Hamiltonian techniques

AbstractA controller able to achieve bidirectional power flow for a boost‐like full‐bridge rectifier is presented. It is shown that no single output yields a stable zero dynamics for power flowing both ways. The controller is computed using port Hamiltonian passivity techniques for a suitable generalized state space averaging truncation of the system, which transforms the control objectives, namely specified output mean value of the voltage dc‐bus and unity input power factor in the ac side, into a regulation problem. Simulation and experimental results for the full system confirm the correctness of the simplifications introduced to obtain the controller. Copyright © 2007 John Wiley & Sons, Ltd.

DC-Link Three-Phase-to-Three-Phase Four-Leg Converters

This paper investigates two reduced-switch-count dc-link three-phase-to-three-phase four-leg converters. The converters provide bidirectional power flow and power-factor control. A control strategy is proposed to obtain the maximum voltage utilization of the converters for applications in which the load frequency is equal to the grid frequency. Several relevant characteristics of the converters, such as voltage ratings, total harmonic distortion, shared-leg and capacitor currents, harmonic voltage, and power ratings are addressed. Experimental and simulated results are presented.

Reduced-Switch-Count Six-Leg Converters for Three-Phase-to-Three-Phase/Four-Wire Applications

Two reduced-switch-count ac/ac dc-link six-leg converters are investigated in this paper. The proposed topologies allow for three-phase-to-three-phase power conversion to supply a three-phase four-wire load without any capacitor dc-link-midpoint connection. The converters provide bidirectional power flow and power-factor control. Pulsewidth modulation techniques are derived by using the concept of local and general apportioning factors. The overall control strategy for providing dc-link voltage and power-factor control is presented. A control strategy to obtain the maximum utilization of the dc-link voltage is also proposed. In addition, several relevant characteristics of the converter are addressed, such as voltage analysis, distorted and unbalanced voltages operation, shared-leg currents, power rating, and total harmonic distortion. The proposed converters are compared to six-leg converters that use the capacitor dc-link-midpoint connection and also to the full-bridge seven-leg converter. Experimental and simulated results are presented

AC Motor Drives With a Reduced Number of Switches and Boost Inductors

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents eight three-phase ac motor-drive configurations that operate with a reduced number of switches and boost inductors. Four of the configurations are single-motor drives, and four of the configurations are double-motor drives. The drives provide both bidirectional power flow and power-factor control. This paper presents the analysis and control strategy of the systems, including current control and pulsewidth-modulation strategy. In spite of using a reduced number of components, the dc-link voltage and the machine currents of some of the proposed configurations are not much larger than the equivalent values of the conventional configurations. These drive systems are suitable for applications where the size of the system is a critical factor. The experimental results demonstrate the feasibility of the proposed topologies. </para>

Generalized Construction of ZCS Switched-Capacitor Bi-directional Converter

The proposed zero-current switching switched-capacitor (ZCS SC) DC-DC converter is an innovative bi-directional power flow control conversion scheme. A zero-current switching switched-capacitor step-up/step-down bi-directional converter is presented that can improve the current stress problem during bi-directional power flow control processing. It can provide a high voltage conversion ratio of n/1 n (n-mode/1 n-mode) us-ing four power MOSFET main switches, a set of switched-capacitors and a small resonant inductor. Simulation and experimental results are carried out to verify the concept and performance of the proposed quadruple-mode/quarter-mode bi-directional DC-DC converter.

Switched-capacitor quasi-resonant step-up/step-down bidirectional converter

A zero-current-switching (ZCS) switched-capacitor (SC) quasi-resonant (QR) converter is presented to suppress current stress during the bidirectional power flow control processing. The voltage conversion ratios 4/¼ are achieved by using the four-MOSFET switches, a switched-capacitor and resonant-inductor. Simulations and experiments are carried out to verify the performance of the ZCS SC QR bidirectional converter.

Zero-current-switching switched-capacitor bidirectional DC–DC converter

The proposed zero-current-switching switched-capacitor quasi-resonant DC–DC converter is a new type of bidirectional power flow control conversion scheme. It possesses the conventional features of resonant switched-capacitor converters: low weight, small volume, high efficiency, low EMI emission and current stress. A zero-current-switching switched-capacitor step-up/step-down bidirectional converter is presented that can improve the current stress problem during bidirectional power flow control processing. It can provide a high voltage conversion ratio using four power MOSFET main switches, a set of switched capacitors and a small resonant inductor. The converter operating principle of the proposed bidirectional power conversion scheme is described in detail with circuit model analysis. Simulation and experiment are carried out to verify the concept and performance of the proposed bidirectional DC–DC converter.

AC motor drive systems with a reduced-switch-count converter

This paper presents two reduced-switch-count AC drive systems. One of the configurations was conceived to operate with a two-phase motor and the other one with a three-phase motor. The drive systems provide both bidirectional power flow and power factor control. Pulsewidth modulation techniques for the converter control are discussed. Experimental results are presented.

A solid-state PWM phase-shifter

A solid-state, pulse-width-modulated (PWM) phase shifter, based on gate-turn-off )GTO) thyristors or other valves with force commutation capabilities, is described. Besides serving the phase-shifter function, it offers regulated control over three independent quantities: the real power passing through it and the VAR (volt-ampere reactive) on both sides to which it is connected. The power transferred can be bidirectional, and the VArs can be leading or lagging. Digital simulations show that the PWM phase-shifter reported here is capable of regulated control of bidirectional real power flow and independent regulated control of positive or negative VArs on both sides of the phase shifter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>