Multi-input DC/DC converters with zero-current switching
A modular-based, zero-current-switched (ZCS), isolated full-bridge boost converter with multiple inputs is disclosed. Each converter module is used to match the connected input source and control the amount of power drawn from the source. The power from various sources are combined together and delivered to the load through a multiphase transformer. The input inductor of each boost-derived converter module keeps the input current constant and acts as a current source to drive the multiphase transformer through a phase-shifted-controlled full bridge converter. By connecting an auxiliary circuit across the full-bridge input in each module, the transformer leakage inductance and output capacitance of the switching devices are used to create resonant paths for facilitating zero-current-switching of all switching devices.
1. A multi-input dc/dc converter comprising:
a plurality of input modules, each input module including at least one input terminal for coupling to a separate dc power source and a full bridge converter having four main switches;
a transformer having a plurality of primary windings and at least one secondary winding, each primary winding coupled to one of the full bridge converters;
at least one output terminal for supplying dc power to a load; and
a rectifier circuit coupled between the secondary winding of the transformer and said output terminal;
each input module further including an auxiliary circuit coupled in parallel with the full bridge converter, the auxiliary circuit configured to achieve turn-on and turn-off of the four main switches when there is substantially no current flowing through each switch being turned on or turned off.
2. The converter of claim 1 wherein the auxiliary circuit of each input module is coupled to an input side of the full bridge converter.
3. The converter of claim 1 wherein each input module further includes an input choke coupled between said input terminal and the full bridge converter.
4. The converter of claim 3 wherein each auxiliary circuit includes an auxiliary switch having a body diode that inhibits current flow from the input choke when the auxiliary switch is off.
5. The converter of claim 1 wherein each full bridge converter is a phase-shift-controlled full bridge converter.
6. The converter of claim 1 wherein each auxiliary circuit includes a switch, a capacitance, and an inductance.
7. The converter of claim 6 wherein said switch, said capacitance, and said inductance are coupled in series in each input module.
8. The converter of claim 1 wherein each auxiliary circuit includes an auxiliary switch and is configured to achieve substantially zero-current-switching of the auxiliary switch during turn-on and substantially zero-voltage-switching of the auxiliary switch during turn-off.
9. The converter of claim 8 wherein each auxiliary circuit includes a control circuit for controlling said auxiliary circuit switch.
10. The converter of claim 9 wherein each auxiliary circuit includes a current transformer coupled to said control circuit.
11. The converter of claim 1 wherein the four main switches are each configured for unidirectional operation.
12. A multi-input DC/DC converter comprising:
a plurality of input modules, each input module including at least one input terminal for coupling to a separate dc power source, a full bridge converter having four main switches, and means for achieving turn-on and turn-off of the four main switches when there is substantially no current flowing through each switch being turned on or turned off;
a transformer having a plurality of primary windings and at least one secondary winding, each primary winding coupled to one of the full bridge converters;
at least one output terminal for supplying dc power to a load; and
a rectifier circuit coupled between the secondary winding of the transformer and said output terminal.
13. The converter of claim 12 wherein said means for achieving turn-on and turn-off of the four main switches in each input module includes a switch, a capacitance, and an inductance coupled to an input side of the full bridge converter.
14. The converter of claim 7 wherein each input module includes an input choke coupled between its input terminal and its full bridge converter and wherein the switch of each auxiliary circuit includes a body diode that inhibits current flow from the input choke when the auxiliary switch is off.
15. The converter of claim 14 wherein each main switch is coupled is series with a blocking diode.
16. The converter of claim 15 wherein each auxiliary circuit is configured to achieve substantially zero-current-switching of the auxiliary switch during turn-on and substantially zero-voltage-switching of the auxiliary switch during turn-off.
17. The converter of claim 16 wherein each full bridge converter is a phase-shift-controlled full bridge converter.