A Universal Soft Switching Dual Active Bridge Converter for Electric

Vehicle Charging Infrastructure towards Sustainable Electric

Transportation

Department of Electrical and Electronics Engineering, Birla Institute of Technology Mesra,

Ranchi, INDIA

Abstract: - This paper introduces a modified Dual Active Bridge (DAB) converter integrated with an

attributes, output features and crucial design parameters. A meticulous design of a 3kW DAB-LLC2

converter is conducted using MATLAB/Simulink software and the comprehensive results are

documented, providing valuable insights into the converter's performance and applicability for EV

charging infrastructure for sustainable electric transportation.

Key-Words: - DAB-LLC2, soft switching, universal Zero Voltage Switching (ZVS), uni-directional power flow,

Switching Frequency, Resonant Frequency

Received: February 15, 2024. Revised: August 27, 2024. Accepted: September 28, 2024. Published: October 16, 2024.

smog, acid rain, and the discharge of harmful gases.

The adoption of renewable energy sources

represents a comprehensive and viable solution to

this challenge. By harnessing energy from

renewable sources, the generation process is

executed without emitting greenhouse gases,

consequently mitigating air pollution. Furthermore,

this transition to renewable energy not only

addresses environmental concerns but also bolsters

energy supply diversity, thereby reducing reliance

electric cars, neighborhood electric vehicles, and

plug-in hybrids, and the electricity source for

recharging. The charging infrastructure comprises

three primary categories: Level 1, Level 2, and DC

fast charging, each offering distinct power outputs.

Notably, the utilization of DAB converters,

renowned for their bi-directional current

management capabilities, presents lightweight,

efficient, and reliable solutions. However, higher

operating frequencies result in increased losses,

In the papers, [4] - [6] introduces a semi dual active

bridge converter featuring a symmetric bipolar

output tailored for bipolar DC distribution systems.

This innovative converter effectively addresses

challenges related to pole voltage imbalance by

incorporating a switched-capacitor circuit, thereby

offering a combination of cost-efficiency and high-

power conversion capabilities. A notable advantage

of this design is the mitigation of the need for

additional voltage balancing and feedback control in

components, and diminished dependence on

magnetic components.

Within the DAB configuration, multiple modulation

techniques have been explored for the efficient

management of soft switching [10] - [12]. These

techniques include Single Phase Shift (SPS),

Extended Phase Shift (EPS), Double Phase Shift

(DPS), and Triple Phase Shift (TPS) respectively.

role in determining the system's efficiency, control

complexity, and overall performance within the

DAB framework. Researchers and practitioners

explore these modulation techniques to tailor the

DAB operation to specific application requirements

and optimize its functionality.

In this article, an enhanced open loop DAB

with the primary objective of mitigating switching

losses and providing a symmetrical array of output

strategically directed towards optimizing and

reducing the overall duration of the charging

process. The subsequent sections of this article

focus on a thorough and detailed investigation of

these advancements. Through a comprehensive

exploration of these developments, the article aims

to elucidate their impact on charging efficiency,

operational dynamics, and the broader implications

for electric vehicle charging infrastructure. The

meticulous examination of these innovations

2. Problem Formulation

This section elucidates the configuration of the

DAB-LLC2 resonant converter. The operational

sequence commences with the provision of a

DC supply voltage, denoted as Vin, to a single-

phase inverter. Subsequently, this inverter is

intricately linked to a single-phase rectifier

through the intermediary of a High-Frequency

(HF) transformer. The primary function of the

HF transformer lies in furnishing electrical

The components comprising Lpr and Lp

represent the resonant leakage and magnetizing

inductances of the primary transformer, serving

as the resonating inductors, while Cpr denotes

the primary resonant capacitor interconnected in

series. An additional LLC arrangement is

implemented on the secondary side of the

transformer. Here, Ls designates the secondary

magnetizing inductance, aligned in series with a

resonant inductor Lsr. Furthermore, a secondary

assumption is made regarding the ideal

characteristics of all switches. Moreover, it is

postulated that the capacitors utilized within the

3. Problem Solution

system's operational continuity and efficiency.

primary side are:

󰇛󰇜󰇛󰇜󰇛󰇜

 (5)

󰇛󰇜󰇛󰇜

In this operational mode, the primary current ip

follows its conventional path, progressively

increasing from zero, thereby magnetizing

inductors Lpr and Lp. Simultaneously, the

capacitor Cpr undergoes discharge through the

circuit. On the secondary side, current flows

sequence of events within the mode contributes

to the controlled magnetization of inductors,

discharge of capacitors, and the strategic

activation and deactivation of switches,

collectively optimizing the energy flow and

operational efficiency of the system.

󰇛󰇜󰇛󰇜

This operational mode allocates a specific dead

to the overall operational continuity and

efficiency of the system.

󰇛󰇜󰇛󰇜󰇛󰇜

The operational sequence on the primary side of

the DAB remains consistent with the preceding

cycle. The capacitor Cpr undergoes discharge to

reach a null voltage and subsequently begins

charging in the opposite direction.

Concurrently, on the secondary side, switches

values. This orchestrated series of events

contributes to the controlled energy transfer and

dynamic performance of the DAB system,

aligning with the specified operational

objectives within the given cycle.

3.1.1 Results and Discussion

3.1.1.1 Simulation Results

A 3kW DAB converter has been subjected to

simulation using MATLAB/SIMULINK

software platform, operating at a switching

frequency of 100 kHz. In this simulation, four

inductors are utilized, denoted by Lpr, Lsr, Lp

and Ls of 15μH, 10μH and 720μH respectively

with their capacitors Cpr and Csr of 60nF and

this property, with a focus on two switches on

the primary side and two on the secondary side.

Specifically, Fig. 4 provides insights into the

ZVS behavior of switch Sp1, while Fig. 5

captures the ZVS dynamics of switch Sp3. The

subsequent representations in Fig. 6 and Fig. 7

depicts the ZVS property across the secondary

switches, namely Ss1 and Ss3. These results not

only elucidate the ZVS phenomena in the

highlighted switches but also extend to the

sinusoidal behavior. Simultaneously, Fig. 9

captures the voltage behavior of both resonant

capacitors, providing critical information on the

energy storage and discharge patterns in the

converter.

Fig. 10 depicts the terminal voltages of primary

and secondary side of the converter, Vab and Vcd

respectively Fig. 11 portrays the output voltage

and output current characteristics of the

converter explaining the constant dc output

Table 1. Parameter Selection of the Proposed

Converter

Fig. 8 Simulation result illustrating the ZVS

behavior of switch Sp3.

Fig. 9 Simulation result illustrating the ZVS

behavior of switch Ss1

Fig. 10 Simulation result illustrating the ZVS

behavior of switch Ss3

Fig. 11 Simulation result showing the primary

current (ip) and secondary current (is)

Fig 12 illustrates the efficiency curve of both

the proposed DAB and a conventional DAB,

offering a comparative analysis of their

respective performance. The graphical

representation evidently indicates a superiority

in efficiency for the proposed DAB in

comparison to the conventional counterpart.

Fig. 14 Simulation result showing output voltage

(Vo) and output current (Io)

the proposed converter. Remarkably, the 3kW

converter successfully fulfills a significant

demand for current supply to the load, as

depicted in the simulation and validated with

[7] C. Yu et al., "High Efficiency Bidirectional

[8] Z. Sun, Q. Wang, L. Xiao and Q. Wu, "A

[10] T. Liu, X. Ma, X. Hao, L. Huang, X. Yu

[11] J. Tian, F. Wang, F. Zhuo and H. Deng,

[13] N. Soltau, H. A. B. Siddique and R. W. De