Stacked DC-DC converter

1. A stacked direct current to direct current (DC-DC) converter comprising:

a first DC bus including a first bus positive terminal coupled to a first one of a power source, a first bus negative terminal coupled to a second power source, and a first bus midpoint terminal directly connected to the first power source and the second power source;

a second DC bus including a second bus positive terminal coupled to a first power load, a second bus negative terminal coupled to a second power load, and a second bus midpoint terminal directly connected to the first power load and the second power load;

a first half-bridge circuit including a first half-bridge positive terminal coupled to the first bus positive terminal, a first half-bridge negative terminal coupled to the first bus midpoint terminal, and a first half-bridge midpoint terminal;

a second half-bridge circuit including a second half-bridge positive terminal coupled to the first half-bridge negative terminal, a second half-bridge negative terminal coupled to the first bus negative terminal, and a second half-bridge midpoint terminal;

a third half-bridge circuit including a third half-bridge positive terminal coupled to the second bus positive terminal, a third half-bridge negative terminal coupled to the second bus midpoint terminal, and a third half-bridge midpoint terminal;

a fourth half-bridge circuit including a fourth half-bridge positive terminal coupled to the third half-bridge negative terminal, a fourth half-bridge negative terminal coupled to the second bus negative terminal, and a fourth half-bridge midpoint terminal;

a first magnetic element coupling the first half-bridge midpoint terminal to the third half-bridge midpoint terminal; and

a second magnetic element coupling the second half-bridge midpoint terminal to the fourth half-bridge midpoint terminal.

2. The DC-DC converter of claim 1 , wherein the first DC bus includes:

a first storage element having a first terminal coupled to the first bus positive terminal and a second terminal coupled to the first bus midpoint terminal; and

a second storage element having a third terminal coupled to the first bus midpoint terminal and a fourth terminal coupled to the first bus negative terminal.

3. The DC-DC converter of claim 2 , wherein each of the first storage element and the second storage element is an array of capacitors.

4. The DC-DC converter of claim 1 , wherein the first half-bridge circuit includes:

a first diode having a first diode positive terminal coupled to the first half-bridge positive terminal and a first diode negative terminal coupled to the first half-bridge midpoint terminal;

a second diode having a second diode positive terminal coupled to the first half-bridge midpoint terminal and a second diode negative terminal coupled to the first half-bridge negative terminal;

a first switch having a first switch positive terminal coupled to the first half-bridge positive terminal, a first switch negative terminal coupled to the first half-bridge midpoint terminal, and a first switch control terminal coupled to a first control element; and

a second switch having a second switch positive terminal coupled to the first half-bridge midpoint terminal, a second switch negative terminal coupled to the first half-bridge negative terminal, and a second switch control terminal coupled to a second control element.

5. The DC-DC converter of claim 1 , wherein each of the first magnetic element and the second magnetic element is an inductor.

6. The DC-DC converter of claim 1 , wherein the first bus midpoint terminal is coupled to the second bus midpoint terminal.

7. The DC-DC converter of claim 1 , wherein the first bus midpoint terminal is coupled to the second bus midpoint terminal via an inductor.

8. A converter comprising:

a first DC bus including a first capacitive element and a second capacitive element, wherein the first capacitive element includes a first capacitor positive terminal coupled to a first power source and a first capacitor negative terminal coupled to a first bus midpoint terminal, and wherein the second capacitive element includes a second capacitor positive terminal coupled to the first bus midpoint terminal, and a second capacitor negative terminal coupled to a second power source, wherein the first bus midpoint terminal is directly connected to the first power source and the second power source;

a second DC bus including a third capacitive element and a fourth capacitive element, wherein the third capacitive element includes a third capacitor positive terminal coupled to a first power load and a third capacitor negative terminal coupled to a second bus midpoint terminal, and wherein the fourth capacitive element includes a fourth capacitor positive terminal coupled to the first bus midpoint terminal and a fourth capacitor negative terminal coupled to a second power load, wherein the second bus midpoint terminal is directly connected to the first power load and the second power load;

a first stack of half-bridges coupled to the first capacitor positive terminal, the first bus midpoint terminal, and the second capacitor negative terminal of the first DC bus;

a second stack of half-bridges coupled to the third capacitor positive terminal, the second bus midpoint terminal, and the fourth capacitor negative terminal of the second DC bus; and

a pair of magnetic elements coupling the first stack of half-bridges to the second stack of half-bridges.

9. The converter of claim 8 , wherein the first stack of half-bridges includes:

a first half-bridge circuit including a first half-bridge positive terminal coupled to the first capacitor positive terminal, a first half-bridge negative terminal coupled to the first bus midpoint terminal, and a first half-bridge midpoint terminal; and

a second half-bridge circuit including a second half-bridge positive terminal coupled to the first half-bridge negative terminal, a second half-bridge negative terminal coupled to the second capacitor negative terminal, and a second half-bridge midpoint terminal.

10. The converter of claim 8 , wherein each of the first capacitive element, the second capacitive element, the third capacitive element, and the fourth capacitive element is an array of capacitors.

11. The converter of claim 8 , wherein the first half-bridge circuit includes:

a first diode having a first diode positive terminal coupled to the first half-bridge positive terminal and a first diode negative terminal coupled to the first half-bridge midpoint terminal;

a second diode having a second diode positive terminal coupled to the first half-bridge midpoint terminal and a second diode negative terminal coupled to the first half-bridge negative terminal;

a first switch having a first switch positive terminal coupled to the first half-bridge positive terminal, a first switch negative terminal coupled to the first half-bridge midpoint terminal, and a first switch control terminal coupled to a first control element; and

a second switch having a second switch positive terminal coupled to the first half-bridge midpoint terminal, a second switch negative terminal coupled to the first half-bridge negative terminal, and a second switch control terminal coupled to a second control element.

12. The converter of claim 8 , wherein each magnetic element of the pair of magnetic elements is an inductor.

13. The converter of claim 8 , wherein the first bus midpoint terminal is coupled to the second bus midpoint terminal.

14. The converter of claim 8 , wherein the first bus midpoint terminal is coupled to the second bus midpoint terminal via an inductor.

15. An apparatus comprising:

a first DC bus including a first bus positive terminal coupled to a first one of a power source, a first bus negative terminal coupled to a second power source, and a first bus midpoint terminal directly connected to the first power source and the second power source;

a second DC bus including a second bus positive terminal coupled to a first power load, a second bus negative terminal coupled to a second power load, and a second bus midpoint terminal directly connected to the first power load and the second power load;

a first stack of half-bridges coupled to the first bus positive terminal, the first bus midpoint terminal, and the first bus positive negative terminal of the first DC bus;

a second stack of half-bridges coupled to the second bus positive terminal, the second bus midpoint terminal, and the second bus positive terminal of the second DC bus; and

a pair of magnetic elements coupling the first mirrored stack of half-bridges to the second mirrored stack of half-bridges.

16. The apparatus of claim 15 , wherein the first stack of half-bridges includes:

a first half-bridge circuit including a first half-bridge positive terminal coupled to the first bus positive terminal, a first half-bridge negative terminal coupled to the first bus midpoint terminal, and a first half-bridge midpoint terminal; and

a second half-bridge circuit including a second half-bridge positive terminal coupled to the first half-bridge negative terminal, a second half-bridge negative terminal coupled to the first bus negative terminal, and a second half-bridge midpoint terminal.

17. The apparatus of claim 15 , wherein each magnetic element of the pair of magnetic elements is an inductor.

18. The apparatus of claim 15 , wherein the first bus midpoint terminal is coupled to the second bus midpoint terminal.