# Dual Active Bridge

This example shows a Dual Active Bridge converter with: * an input voltage of 95 V, * an output voltage of 380 V, * a initial output power of 1 kW raised to 2 kW at 200 ms.

## PWM control

Each bridge with a duty cycle of 50%. The phase-shift between the two bridges is set by the discrete controller (PI regulator) in order to regulate the output voltage.

## Power semiconductor switches

Mosfets of this example are set with conduction parameters: a first R_{on} resistance for the channel conduction mechanism (forward and reverse conduction when the transistor's gate id driven high) and a second R_{on} resistance and a V_f drop voltage for the body diode.

*Note* : with the command used in this example, mosfets are always used in *synchronous rectification mode* which means that the controlled conduction mechanism (channel) is the major contributor for conducting the reverse current compared to the body diode conduction.

## Transformer ratio

The transformer ratio can be chosen according required values of primary and secondary voltages. Here a secondary voltage of 380V is required and a primary voltage of 95V is considered to be the lowest possible value (worst case), which leads to a transformer ratio of 4.

## Inductor design

The expression below gives the maximum power which can be transferred for a phase-shift angle of \pi / 2 [1]:

with m = \frac{V_2}{V_1} the transformer ratio

A maximum power of 2 kW and a margin of 10 % is considered. At a switching frequency of 250 kHz, with V_1 = 95V and V_2 = 380V, this leads to a maximun inductor value of 2.051 \mu H.

This value is compatible with typical values of leakage inductors of high-frequency transformers with these levels of power, voltages and ratio.

[1] M. Blanc, Y. Lembeye, J.P. Ferrieux, Dual Active Bridge (DAB) pour la conversion continu-continu, Techniques de l'ingĂ©nieur E3975, 2019.