Power system with zero voltage switching
View Patent ↗A DC/DC converter includes first and second bridges comprising a plurality of switch elements and a plurality of coupling capacitors. Each coupling capacitor couples one of the switch elements of the first bridge to one of the switch elements of the second bridge. The first and second bridges are connected to a transformer comprising a first primary winding, a second primary winding, and a secondary winding. A coupled inductor comprises first and second inductors and is connected to the transformer so that the first and second primary windings are inductively coupled through the coupled inductor.
1. A DC/DC converter, comprising:
first and second bridges, each first and second bridge comprising a plurality of switch elements;
a plurality of coupling capacitors, each coupling capacitor coupling one of the switch elements of the first bridge to one of the switch elements of the second bridge;
a transformer comprising a first primary winding, a second primary winding, and a secondary winding, each of the first primary winding and the second primary winding defining first and second terminals, the first primary winding connected to the first bridge, and the second primary winding connected to the second bridge; and
a coupled inductor comprising first and second inductors, the coupled inductor connected to the transformer so that the first and second primary windings are inductively coupled through the coupled inductor.
2. The DC/DC converter of claim 1 , wherein the secondary winding of the transformer comprises a first secondary winding and a second secondary winding, each of the first secondary winding and the second secondary winding defining first and second terminals, the second terminal of the first secondary winding connected to the first terminal of the second secondary winding to form a secondary node.
3. The DC/DC converter of claim 2 , further comprising a third inductor, the third inductor connected to the secondary node.
4. The DC/DC converter of claim 3 , further comprising:
a first bridge capacitor connected in parallel with the first bridge; and
a second bridge capacitor coupled in parallel with the second bridge.
5. The DC/DC converter of claim 4 , wherein the first inductor is interposed between the first terminal of the first primary winding and the first bridge, and the second inductor is interposed between the first terminal of the second primary winding and the second bridge.
6. The DC/DC converter of claim 4 , wherein the first inductor is connected to the first terminal of the first secondary winding and the second inductor is connected to the second terminal of the second secondary winding.
7. The DC/DC converter of claim 1 , wherein the switching elements are IGBT devices.
8. The DC/DC converter of claim 1 , wherein the switching elements are MOSFET devices.
9. A DC/DC converter, comprising:
a first bridge comprising first and second switches and first and second diodes, the first bridge defining a first node and a second node, the first switch and the first diode series connected between the first and second nodes, and the second switch and second diode series connected between the first and second nodes;
a second bridge comprising third and fourth switches and third and fourth diodes, the second bridge defining the second node and a third node, the third switch and the third diode series connected between the second and third nodes, and the fourth switch and fourth diode series connected between the second and third nodes;
a first capacitor connected between the first and third switch;
a second capacitor connected between the second and fourth switch;
a transformer comprising a first primary winding, a second primary winding, and a secondary winding, each of the first primary winding and the second primary winding defining first and second terminals, the first terminal of the first primary winding connected to the second switch and second diode, and the first terminal of the second primary winding connected to the fourth switch and fourth diode; and
a coupled inductor comprising first and second inductors, the coupled inductor connected to the transformer so that the first and second primary windings are inductively coupled through the coupled inductor.
10. The DC/DC converter of claim 9 , wherein the first inductor is connected between the second terminal of the first primary winding and the first switch, and the second inductor is connected between the second terminal of the second primary winding and the third switch.
11. The DC/DC converter of claim 10 , wherein the secondary winding of the transformer comprises a first secondary winding and a second secondary winding, each of the first secondary winding and the second secondary winding defining first and second terminals, the second terminal of the first secondary winding connected to the first terminal of the second secondary winding to form a secondary node.
12. The DC/DC converter of claim 11 , further comprising a third inductor, the third inductor connected to the secondary node.
13. The DC/DC converter of claim 12 , further comprising:
a first bridge capacitor connected in parallel with the first bridge; and
a second bridge capacitor coupled in parallel with the second bridge.
14. The DC/DC converter of claim 13 , wherein the switching elements are IGBT devices.
15. The DC/DC converter of claim 13 , wherein the switching elements are MOSFET devices.
16. The DC/DC converter of claim 9 , wherein the second terminal of the first primary winding is connected to the first switch and first diode, and the second terminal of the second primary winding connected to the third switch and third diode.
17. The DC/DC converter of claim 16 , wherein the transformer secondary winding comprises a first secondary winding and a second secondary winding, each of the first secondary winding and the second secondary winding defining first and second terminals, and the first inductor is connected to the first terminal of the first secondary winding and the second inductor is connected to the second terminal of the second secondary winding.
18. The DC/DC converter of claim 17 , wherein the second terminal of the first secondary winding is connected to the first terminal of the second secondary winding to form a fourth node.
19. The DC/DC converter of claim 18 , further comprising a third inductor, the third inductor connected to the fourth node.
20. The DC/DC converter of claim 19 , further comprising:
a first bridge capacitor connected in parallel with the first bridge; and
a second bridge capacitor coupled in parallel with the second bridge.
21. The DC/DC converter of claim 20 , wherein the switching elements are IGBT devices.
22. The DC/DC converter of claim 20 , wherein the switching elements are MOSFET devices.
23. A method of DC/DC conversion in a DC/DC converter comprising first and second bridges and a transformer comprising a first primary winding, a second primary winding, a first secondary winding, and a second secondary winding, comprising the steps of:
capacitively coupling the first and second bridges with coupling capacitors; and
inductively coupling the first and second primary windings with coupled inductors.
24. The method of claim 23 , wherein the step of inductively coupling the first and second primary windings with coupled inductors comprises the steps of:
connecting the first primary winding to a first inductor; and
connecting the second primary winding to a second inductor;
wherein the first and second inductors are inductively coupled.
25. The method of claim 24 wherein the step of inductively coupling the first and second primary windings with coupled inductors comprises the steps of:
connecting the first secondary winding to a first inductor; and
connecting the second secondary winding to a second inductor;
wherein the first and second inductors are inductively coupled.
26. The method of claim 22 , wherein the step of capacitively coupling the first and second bridges with coupling capacitors comprises the steps of:
coupling a first switch in the first bridge to a first switch in the second bridge with a first capacitor; and
coupling a second switch in the first bridge to a second switch in the second bridge with a second capacitor.
27. A power system comprising a plurality of power supply units (“PSUs”), each PSU having an output that is coupled to the output of other PSUs in the power system, each PSU comprising:
a power factor correction (“PFC”) assembly for receiving an AC input and generating a first DC output;
a DC/DC converter assembly that is coupled to the PFC assembly, the DC/DC converter assembly receiving the first DC output and generating a second regulated DC output, the DC/DC converter comprising:
first and second bridges, each first and second bridge comprising a plurality of switch elements;
a plurality of coupling capacitors, each coupling capacitor coupling one of the switch elements of the first bridge to one of the switch elements of the second bridge;
a transformer comprising a first primary winding, a second primary winding, and a secondary winding, each of the first primary winding and the second primary winding defining first and second terminals, the first primary winding connected to the first bridge, and the second primary winding connected to the second bridge; and
a coupled inductor comprising first and second inductors, the coupled inductor connected to the transformer so that the first and second primary windings are inductively coupled through the coupled inductor;
a control assembly that is coupled to the DC/DC converter assembly, the control assembly being operative to monitor the DC/DC converter assembly output and in response thereto to provide control signals to the DC/DC converter assembly, the control assembly comprising,
a plurality of control assembly input circuits, the control assembly input circuits being operative to measure characteristics relating to the DC/DC converter assembly and operative to generate a measured characteristics output;
a signal processor having a signal path to the control assembly input circuits, the signal processor being operative to receive the measured characteristics output, perform computations wherein the measured characteristics output is used in the computations, and generate a signal processor output; and
a plurality of control assembly output circuits, the control assembly output circuits being operative to generate error signals based on the signal processor output.