Coupled Split Path Power Conversion Architecture

• US 20180102644A1
• Filed: 10/11/2016
• Published: 04/12/2018
• Est. Priority Date: 10/29/2013
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Perreault, David J., Afridi, Khurram K., Chen, Minjie
• Granted Patent: US 10,644,503 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• CPC Class Codes: H02M 7/12 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02M 7/68 by static converters
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Described herein are power conversion systems and related techniques which utilize a coupled split path (CSP) circuit architecture. The CSP structure combines switches, capacitors and magnetic elements in such a way that power is processed in multiple coupled split paths in a variety of voltage domains. These techniques are well suited for power conversion applications that have one or more input/output ports that have a wide voltage range, or if the application is interfacing with the ac line voltage and requires power-factor correction.

Claims

1. A coupled split path (CSP) voltage converter having one or more input ports and one or more output ports, comprising:

a set of inverter cells that are electrically coupled with their input ports cascaded to form a series chain to provide a set of terminals at the inverter cell inputs forming a set of N voltages levels of increasing magnitude relative to a reference potential;

a power distributor circuit having an input and a set of outputs, said power distributor circuit comprising an inductor and a switch network and arranged such that said power distributor circuit operates to draw power from its input and deliver power via its outputs into at least two of the N voltage levels;

a transformer having at least three windings, said transformer disposed such that each inverter cell drives a transformer winding;

and one or more rectifier circuit cells each having an output port and an input coupled to a transformer winding.

2. The coupled split path voltage converter of claim 1, wherein:

the set of terminals at the inverter inputs form N=2 voltage levels, said voltage levels providing substantially equal input voltages to said inverters.

3. The coupled split path voltage converter of claim 2 wherein:

the power distributer circuit comprises an inductor and two pairs of switches, each pair in a half-bridge configuration, said switches operating to switch one end of the inductor between a reference potential, a first voltage level of the inverter cells, and a second voltage level of the inverter cells.

4. The coupled split path voltage converter of claim 3 wherein:

at least one switch of said power distributor circuit comprises a diode.

5. The coupled split path voltage converter of claim 2 wherein:

each of said plurality of inverter circuit cells is coupled with another inverter circuit cell via a flying capacitor to provide capacitor charge transfer for voltage equalization among inverter cells; and

power transferred among the inverter and rectifier cells are exchanged by a combination of capacitive energy transfer via flying capacitors and magnetic energy transfer via the said multi-winding transformer.

6. The coupled split path voltage converter of claim 4, wherein:

the converter input is an ac voltage; and

the converter is provided with an energy buffer capacitor coupled to two nodes of the inverter circuit cells; and

the power distributor is controlled over an ac line cycle to draw energy from the ac voltage at high power factor.

7. The coupled split path voltage converter of claim 6, wherein:

the power distribution stage further comprises a second inductor or an additional inductor winding to form a coupled inductor; and

switches of the power distribution stage are further configured to operate to also provide bridgeless power factor correction rectification.

8. The apparatus recited in claim 1, wherein:

each of said plurality of inverter circuit cells is coupled with another inverter circuit cell via a flying capacitor to provide capacitor charge transfer for voltage equalization among inverter cells; and

power transferred among the inverter and rectifier cells are exchanged by a combination of capacitive energy transfer via flying capacitors and magnetic energy transfer via the said multi-winding transformer.

9. The apparatus recited in claim 8, wherein:

at least one end of the inductor in said power distributor circuit is dynamically switched among two or more of said N dc voltage levels.

10. The apparatus recited in claim 8, wherein:

said power distributor circuit comprises at least two switches configured as a half-bridge; and

the two switches are controlled by pulse-wide-modulated (PWM) signals to regulate the voltage of one or more of said voltage levels.

11. The apparatus recited in claim 10, wherein:

said converter comprises exactly two inverter cells and at least one rectifier cell;

12. The apparatus recited in claim 11, wherein

said transformer is provided as a printed-circuit-board (PCB) embedded transformer implemented in a printed circuit board;

13. The apparatus recited in claim 11, wherein the current of the inductor is made bidirectional within a switching cycle to provide zero-voltage-switching (ZVS) or near ZVS soft switching operation of one or more switches of the power distributor.

14. The apparatus recited in claim 8, wherein the plurality of N inverters are controlled by synchronized signals.

15. The apparatus recited in claim 8, wherein the net load impedances seen by the plurality of N inverters are inductive at the switching frequency of the N inverters to realize Zero Voltage Switching.

16. The apparatus recited in claim 8, wherein at east one switch in the power distributor circuit is implemented as a diode.

17. The apparatus recited in claim 1, wherein the voltage of at least one of the said input/output port comprises an ac line voltage, and the circuit performs power-factor correction via control of the switches in the power distributor circuit.

18. The apparatus recited in claim 17, wherein there is an energy buffer capacitor directly connected between the highest voltage level and the ground that is sized to buffer at least the twice-line-frequency energy for power factor correction conversion.

19. The apparatus recited in claim 18, wherein the said capacitor connected between the highest voltage level and ground is an electrolytic capacitor which buffers the energy difference between that provided at the input port and that supplied to the output port.

20. The apparatus recited in claims 17, wherein the switches and inductors utilized in the power distributor are also utilized to realize bridgeless power factor correction.

21. A power conversion method comprising:

distributing power from one input source to a plurality of N inverter circuit cells having their input ports cascaded by;

utilizing an inductor and a set of switches to deliver energy from an input to at least two of the inverter inputs by switching at least one terminal of the inductor among at least two inverter input terminals; and

balancing the input voltages of the plurality of N inverter circuit cells via one or both of switched-capacitor energy transfer and magnetic coupling;

providing power from the plurality of N inverter cells to the inputs of a three or more winding magnetic component operating via magnetic coupling to step up or down voltage;

delivering power transferred via the magnetic component to an output by rectification;

22. The power conversion method of claim 21 further comprising:

Utilizing exactly N=2 inverter cells; and

Switching one terminal of said inductor among a reference potential, the input terminal of a first inverter cell and the input terminal of a second inverter cell.

23. The power conversion method of claim 22 further comprising:

providing said input source as an ac line voltage; and

providing a twice-line-frequency energy buffer capacitor across the cascade of inverter input terminals; and

further utilizing switching of said inductor terminal to provide power factor correction.

24. The power conversion method of claim 23 further comprising:

providing a second inductor or second inductor winding to form a coupled inductor; and

further utilizing switching of first and second inductor terminals s to further provide rectification.