Modified dual active half bridge DC/DC converter with transformer DC bias
View Patent ↗This invention is an improvement upon the modified dual active half bridge (MDAB) DC/DC converter whereby the filter inductor is eliminated. Allowing DC bias in the transformer, the transformer's magnetizing inductance serves a secondary role of filter inductance. Due to the high currents on the low voltage side, the filter inductor is a relatively large component, often close in size to the transformer. Eliminating the filter inductor as presented here represents a significant reduction in the size and cost of the DC/DC converter, and further achieves improved efficiency of operation as losses associate with the filter inductor are also eliminated.
1. A DC-DC converter comprising:
a first DC power source and/or load;
a second DC power source and/or load;
a first half-bridge switching circuit;
a second half-bridge switching circuit; and
a transformer incorporating a series inductance as either leakage inductance or as a separate resonant inductance; wherein
the first DC power source and/or load is connected directly across a lower capacitor of the first half-bridge switching circuit,
a first winding of the transformer is connected across center nodes of the first half-bridge switching circuit,
a second winding of the transformer is connected across center nodes of the second half-bridge switching circuit, and
the second DC power source and/or load is connected across DC rails of the second half-bridge switching circuit.
2. The DC-DC converter of claim 1 , wherein the transformer has a magnetizing inductance which filters current to and from the first power source and/or load.
3. The DC-DC converter of claim 1 , further comprising a control unit which sets a switching duty cycle of both of the half-bridge switching circuits to maintain a voltage balance across the transformer.
4. The DC-DC converter of claim 3 , wherein the control unit also sets phase shift between the switching of the half-bridge switching circuits to control power flow.
5. The DC-DC converter of claim 1 , wherein the DC-DC converter is bi-directional with a source side as leading phase and a load side as lagging phase.
6. The DC-DC converter of claim 1 wherein the DC-DC converter is isolated.