Vishnu Mahadeva Iyer

Optimal design methodology for dual active bridge converter under wide voltage variation

Dual active bridge (DAB) converter is a popular topology for bidirectional on-board electric vehicle (EV) charger systems and other energy storage applications. In such systems, wide variation in the battery voltage makes design of the DAB converter non-trivial. The focus of this paper is on the optimal selection of DAB parameters when there is a wide variation in the output voltage. Different optimal strategies based on a minimal Euclidean norm approach, namely ‘minimal rms current design’, ‘minimal peak current design’ and ‘minimal power loss design’ are compared to illustrate the effect on system performance with output voltage variation. The proposed optimal design approaches are shown to be superior to a conventional design approach. A loss model for the DAB converter that can be used in the optimal design process is presented. The proposed optimal strategies are validated with experimental results using a laboratory prototype.

Hybrid control strategy to extend the ZVS range of a dual active bridge converter

This paper presents a hybrid control strategy for a dual active bridge (DAB) based dc-dc converter which combines the benefits of traditional phase shift and burst mode modulation schemes. The advantage of using such a control strategy stems from the fact that it can extend the zero voltage switching (ZVS) range of all power switches in both the primary and secondary bridges when there is a wide variation in input or output voltage. In addition, the hybrid control strategy improves the light load efficiency of the DAB converter. The paper focuses on the development of the average and small signal models for the DAB converter with the hybrid modulation scheme. Digital implementation considerations of the hybrid control scheme are discussed. The effectiveness of the proposed control strategy has been tested and validated through simulations and experiments.

Design, Package, and Hardware Verification of a High-Voltage Current Switch

In this paper, an attempt has been made to demonstrate various package design considerations to accommodate series connection of high voltage Si-IGBT (6500V/25A die) and SiC-Diode (6500V/25A die). The effects of connecting the cathode of the series diode to the collector of the IGBT versus connecting the emitter of the IGBT to the anode of the series diode have been analyzed in regards to parasitic line inductance of the structure. Various simulation results have then been used to redesign and justify the optimized package structure for the final current switch design. The package is fabricated using the optimized parameters. A double pulse test-circuit has been assembled. Initial hardware results have been shown to verify functioning. The main motivation of this work is to enumerate detailed design considerations for packing a high voltage current switch package.

A dual loop current control structure with improved disturbance rejection for grid connected converters in the synchronous rotating reference frame

Increase in renewable energy penetration, in the recent past, has been one of the primary causes for serious issues in power quality of the utility grid. This has ushered in the need for a robust and stable control system for reference tracking and disturbance rejection of grid-connected converters. Conventionally, due to its simplicity and ability to achieve zero steady-state error, a simple proportional integral (PI) controller is used in the synchronous reference frame (

Design, package, and hardware verification of a high voltage current switch

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Extreme fast charging station architecture for electric vehicles with partial power processing

) for current control of voltage-source based grid-connected systems. However, the PI controller by itself, may not suffice for adequate disturbance rejection, especially when the utility grid voltages contain other harmonics in addition to the fundamental component. This paper introduces and analyzes a dual-loop current control structure, which utilizes two independent controllers, one for reference tracking and the other for disturbance rejection in the

Proportional integral — Resonant and dual loop current control structure comparison for grid connected converters in the rotating frame

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Stationary reference frame based current control structure with improved disturbance rejection for grid connected converters

frame. A small signal model of the dual-loop current control has been presented and its robustness under grid impedance variation, examined. Extensive experimental results are presented to validate the dual-loop control strategy for improved disturbance rejection capability and filtering action during the presence of grid voltage disturbances and grid impedance variations, without compromising the reference tracking performance.

Small-Signal Stability Assessment and Active Stabilization of a Bidirectional Battery Charger

This paper demonstrates various electrical and package design considerations in series connecting a high-voltage (HV) silicon (Si)-IGBT (6500-V/25-A die) and a silicon carbide-junction barrier Schottky diode (6500-V/25-A die) to form an HV current switch. The effects of connecting the cathode of the series diode to an IGBT collector, versus connecting the IGBT emitter to the anode of the series diode, are analyzed in regards to minimizing the parasitic inductance. An optimized package structure is discussed and an HV current switch module is custom fabricated in the laboratory. An HV double pulse test circuit is used to verify the switching performance of the current switch module. Low-voltage and HV converter prototypes are developed and tested to ensure thermal stability of the same. The main motivation of this paper is to enumerate detailed design considerations for packaging an HV current switch.