Bidirectional DC/DC converter with a step-up mode in one direction and a step-down mode in the other direction
AssigneesAscom Energy Systems AG, DaimlerChrysler AG
InventorsLudwig Vollmer, Andreas Schell, Helmut Lorenz
Life of this patent
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Abstract
A DC/DC converter which can be operated alternately as a step-up converter in a first direction of energy flow and as a step-down converter in a second direction of energy flow is disclosed. Potential isolation between the low-voltage side and the high-voltage side of the converter is achieved by a magnetic compound unit, which has not only a transformer function but also an energy store function. The converter operates as a push-pull converter in both directions of energy flow. The DC/DC converter can be used for example in motor vehicles with an electric drive fed by fuel cells.
Claims12
A DC/DC converter acting alternately as a step-up converter in a first direction of energy flow and as a step-down converter in a second direction of the energy flow, comprising:
- a magnetic compound unit having an iron core with an air gap-free limb, an air gap-containing magnetic circuit for realizing an energy store function, and an air gap-free magnetic circuit for realizing a transformer function disposed parallel to said air gap-containing magnetic circuit, said magnetic compound unit further having two series-connected low-voltage windings with a junction point there-between routed out as a center tap and two series-connected high-voltage windings, a respective low-voltage winding of said two series-connected low-voltage windings disposed together with one of said series-connected high-voltage windings on said air gap-free limb of said iron core;
- a first switch circuit connected to said two series-connected low-voltage windings;
- a first rectifier circuit connected to said two series-connected high-voltage windings;
- a first smoothing circuit connected to said first rectifier circuit;
- a controller connected to said first rectifier circuit and said two series-connected low-voltage windings;
- said controller, said first switching circuit, said first rectifier circuit and said first smoothing circuit defining step-up converter components for performing step-up converter operations;
- a second switching circuit connected to said first rectifier circuit;
- a second rectifier circuit connected to said two series-connected low-voltage windings;
- a second smoothing circuit connected to said two series-connected low-voltage windings;
- said second switching circuit, said second rectifier circuit, said second smoothing circuit and said controller defining step-down converter components for performing step-down converter operations;
- and
- an energy flow circuit for controlling a direction of energy flow.
A DC/DC step-down converter, comprising:
- a magnetic compound unit having an iron core, a low-voltage side and a high-voltage side, said iron core having an air gap-free limb, an air gap-containing magnetic circuit for realizing an energy store function, and an air gap-free magnetic circuit for realizing a transformer function and disposed parallel to said air gap-containing magnetic circuit, said magnetic compound unit further having two series-connected low-voltage windings with a junction point, there-between routed out as a center tap and two series-connected high-voltage windings, a respective low-voltage winding of said two series-connected low-voltage windings disposed together with one of said series-connected high-voltage windings on said air gap-free limb of said iron core;
- a power transistor full-bridge disposed on said high-voltage side of said magnetic compound unit;
- rectifier diodes disposed on said low-voltage side of said magnetic compound unit;
- a capacitor disposed on said low-voltage side of said magnetic compound unit;
- and
- a controller driving said power transistor full-bridge in a push-pull operation.
Dependencies are inferred from the claim text.