Case ID: M10-125P^

Published: 2020-02-26 10:36:24

Last Updated: 1677134929


Amit Kumar Jain
Rajapandian Ayyanar

Technology categories

Semiconductor Devices

Licensing Contacts

Shen Yan
Director of Intellectual Property - PS
[email protected]

PWM Control of Dual Active Bridge Converters

A dual active bridge (DAB) DC-DC converter is ideally
suited for high-power, galvanically isolated DC-DC conversion. The DAB DC-DC
converter has advantages of high power density, Zero Voltage Switching (ZVS),
bidirectional power transfer capability, a modular and symmetric structure, and
simple control requirements. The DAB DC-DC converter can also be used for
multi-port operation, which is a feature that is useful in interfacing several
DC sources and loads using a single converter. Notwithstanding all of the
advantages of the conventional DAB converter, for applications requiring wide
voltage variations, such as an interface for energy storage, fuel cells, or
photovoltaics, the DAB converter has limited ZVS range and high circulating
currents at low loads. The high circulating currents at low loads results in
poor efficiency when the DAB converter is under a low load condition. Thus,
there is a need for an improved DAB converter that provides an increased ZVS
range and/or increased efficiency particularly at low load conditions.

To address these issues, researchers at Arizona State
University have developed novel control schemes for bidirectional dc-dc dual
active bridge converters. The proposed control schemes combine the traditional
method of phase shift control with Pulse Width Modulation (PWM) of one single
H-bridge and two converter bridges simultaneously in a composite control scheme
that depends on the input to output voltage ratio and the load condition. One
key element is that the scheme automatically transitions between dual PWM,
single PWM, and only phase shift control by utilizing directly measured input
and output voltages, and using the load information implicit in the required
phase shift.

Potential Applications

  • Uninterruptible Power Supplies (UPS)
  • Grid Tie Renewable Resources (Photovoltaic Energy)

  • Fuel Cells

Benefits and Advantages

  • Extends the soft-switching range down to zero load

  • Reduces rms and peak currents
  • Results in significant size reduction of the transformer

  • Lower magnetic core losses
  • As an example, the efficiency at 3% load and half nominal
    output voltage is increased from 25% with phase shift control alone to 77%
    with the proposed scheme. The transformer size is also reduced by 33%.