Resonant snubber inverter

• US 5,642,273 A
• Filed: 09/30/1994
• Issued: 06/24/1997
• Est. Priority Date: 09/30/1994
• Status: Expired due to Fees

• Current Assignee: Martin Marietta Energy Systems, Inc.
• Original Assignee: Martin Marietta Energy Systems, Inc.
• Inventors: Chen, Daoshen, McKeever, John W., White, Clifford P., Lai, Jih-Sheng, Scudiere, Matthew B., Young, Robert W. Sr., Ott, George W. Jr.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US08/316,612
• Time in Patent Office: 998 Days
• Field of Search: 363/16, 363/55, 363/56, 363/97, 363/98, 363/131, 363/132, 323/222
• US Class Current: 363/56.12
• CPC Class Codes: H02M 1/34 Snubber circuits
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H03K 17/08148 in composite switches
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption
• 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

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Claims

1. An auxiliary resonant snubber circuit connected to a main inverter circuit having a main power source for soft switching of inverter circuit main switches, the snubber circuit comprising:

a plurality of snubber branches connected to said main circuit, wherein each snubber branch includes an inductor connected in series with only one semiconductor switch, for conducting current from said main power source through said plurality of snubber branches to produce resonant currents that result in zero voltage across predetermined main switches.

2. The snubber circuit as described in claim 1, further comprising sources of capacitance connected in parallel with each of said main switches, wherein said main switches conduct current from said main power source to said snubber branches for production of resonant currents, said resonant currents producing zero voltage across said main switches by repetitively charging and discharging said sources of capacitance to enable zero voltage turn-on of said inverter circuit main switches.

3. A method for achieving lossless resonant snubbing during switching of an inverter circuit having a first upper main switch and a first lower main switch connected in series, and a second upper main switch and a second lower main switch connected in series, each of the main switches having a parallel capacitance associated with the switch, comprising the steps of:

turning on the first lower main switch and second upper main switch so that the first lower and second upper main switches conduct current;

providing resonant snubber branches, one snubber branch being connected at junctions between each upper and lower main switches;

turning on a predetermined auxiliary switch located within a resonant snubber branch so that increasing current flows in said resonant snubber branch;

turning off said first lower and second upper main switches, thereby initiating resonant discharge of capacitances located in parallel with the first upper main switch and the second lower main switch to produce zero voltage across said first upper and second lower main switches;

turning on said first upper and second lower main switches at said zero voltage condition.

4. A resonant, snubber-based, soft switching, multi-phase, inverter circuit for achieving lossless switching of circuit components, comprising:

a main inverter circuit having a plurality of main switches and sources of capacitance connected to said main switches, said main circuit producing a plurality of current phases;

an auxiliary resonant snubber circuit connected to said inverter circuit and having a plurality of resonant snubber branches for repetitively producing zero voltage across each of said main switches and sources of capacitance, each of said snubber branches comprising an inductor and an auxiliary switch connected in series with said inductor, each auxiliary switch having a source, gate, and drain;

a protective diode having an anode and a cathode, said cathode being connected to the sources of said auxiliary switches; and

a controller for controlling said main and auxiliary switches to achieve lossless switching by switching said auxiliary switches to produce zero voltage conditions across said main switches and by switching on said main switches during said zero voltage conditions.

5. The inverter circuit as described in claim 4, wherein said sources of capacitance further comprises capacitance in parallel with each of said main switches, said capacitance being resonated by said snubber branches during turn-on of said main switches.

6. The inverter circuit as described in claim 4, said main inverter circuit further comprising for each current phase:

an upper semiconductor switch and a lower semiconductor switch, each having a source, gate, and drain;

means for connecting the source of the upper semiconductor switch to the drain of the lower semiconductor switch;

a reverse blocking diode antiparalleled against each of said semiconductor switches; and

means for connecting the source of the lower semiconductor switch to the anode of said protective diode;

wherein the alternating current for each phase is produced at the source-drain junction of the two semiconductor switches for each phase.

7. A resonant, snubber-based, soft switching, single-phase, inverter circuit for achieving lossless switching of circuit components, comprising:

a main inverter circuit having a plurality of main switches and sources of capacitance connected to said main switches, said main circuit producing a single current phase;

an auxiliary resonant snubber circuit connected to said inverter circuit and having two resonant snubber branches for repetitively producing zero voltage across each of said main switches and sources of capacitance, each of said snubber branches comprising an inductor and only one auxiliary switch connected in series with said inductor, each auxiliary switch having a source, gate, and drain;

a protective diode having an anode and a cathode, said cathode being connected to the sources of said auxiliary switches; and

a controller for controlling said main and auxiliary switches to achieve lossless switching by switching said auxiliary switches to produce zero voltage conditions across said main switches and by switching said main switches during said zero voltage conditions.

8. The inverter circuit as described in claim 7, wherein said sources of capacitance further comprise capacitance in parallel with each of said main switches, said capacitance being resonated by said snubber branches during turn-on of said main switches.

9. The inverter circuit as described in claim 7, said main circuit further comprising:

a first semiconductor switch having a source, gate and drain;

a first reverse blocking diode antiparalleled against said first semiconductor switch;

a second semiconductor switch having a source, gate and drain;

a second reverse blocking diode antiparalleled against said second semiconductor switch;

a third semiconductor switch having a source, gate and drain;

a third reverse blocking diode antiparalleled against said third semiconductor switch;

a fourth semiconductor switch having a source, gate and drain;

a fourth reverse blocking diode antiparalleled against said fourth semiconductor switch;

means for connecting the source of the first semiconductor switch to the drain of the second semiconductor switch, forming a first semiconductor switch pair;

means for connecting the source of the third semiconductor switch to the drain of the fourth semiconductor switch, forming a second semiconductor switch pair;

means for connecting the drains of the first and third semiconductor switches; and

means for connecting the sources of the second and fourth semiconductor switches to the anode of said protective diode;

wherein the single-phase alternating current is produced at the source-drain junctions of the two semiconductor switch pairs.

10. A resonant snubber based soft switching inverter circuit for achieving lossless turn-on of circuit components during three-phase dc-to-ac power conversion, comprising:

a first semiconductor switch having a source, gate, and drain;

a first reverse blocking diode antiparalleled against said first semiconductor switch;

a first capacitance source in parallel with said first semiconductor switch;

a second semiconductor switch having a source, gate, and drain;

a second reverse blocking diode antiparalleled against said second semiconductor switch;

a second capacitance source in parallel with said second semiconductor switch;

means for connecting the source of the first semiconductor switch to the drain of the second semiconductor switch for conducting a first phase alternating current;

a third semiconductor switch having a source, gate, and drain;

a third reverse blocking diode antiparalleled against said third semiconductor switch;

a third capacitance source in parallel with said third semiconductor switch;

a fourth semiconductor switch having a source, gate, and drain;

a fourth reverse blocking diode antiparalleled against said fourth semiconductor switch;

a fourth capacitance source in parallel with said fourth semiconductor switch;

means for connecting the source of the third semiconductor switch to the drain of the fourth semiconductor switch for conducting a second phase alternating current;

a fifth semiconductor switch having a source, gate, and drain;

a fifth reverse blocking diode antiparalleled against said fifth semiconductor switch;

a fifth capacitance source in parallel with said fifth semiconductor switch;

a sixth semiconductor switch having a source, gate, and drain;

a sixth reverse blocking diode antiparalleled against said sixth semiconductor switch;

a sixth capacitance source in parallel with said sixth semiconductor switch;

means for connecting the source of the fifth semiconductor switch to the drain of the sixth semiconductor switch for conducting a third phase alternating current;

a protective diode having an anode and a cathode;

a dc voltage source having two terminals;

means for connecting one terminal of the dc voltage source to the drains of the first, third, and fifth semiconductor switches;

means for connecting the other terminal of the dc voltage source to the sources of said second, fourth, and sixth semiconductor switches and the anode of said protective diode;

first phase means for connecting said first phase alternating current to a load;

second phase means for connecting said second phase alternating current to the load;

third phase means for connecting said third phase alternating current to the load;

a first auxiliary semiconductor switch having a source, gate and drain;

a first inductor;

means for connecting the drain of said first auxiliary semiconductor switch in series with the first inductor;

a second auxiliary semiconductor switch having a source, gate and drain;

a second inductor;

means for connecting the drain of said second auxiliary semiconductor switch in series with the second inductor;

a third auxiliary semiconductor switch having a source, gate and drain;

a third inductor;

means for connecting the drain of said third auxiliary semiconductor switch in series with the third inductor;

means for connecting the first inductor to the first phase means;

means for connecting the second inductor to the second phase means;

means for connecting the third inductor to the third phase means;

means for connecting the sources of said first, second, and third auxiliary semiconductor switches to the cathode of said protective diode; and

means for controlling the gates of all said semiconductor switches;

said semiconductor switches, diodes, and inductors having parameters selected so that resonance is established within each of said phases and across the stray capacitances of each semiconductor switch to produce zero voltage across said semiconductor switches during switching of said semiconductor switches.

11. A resonant snubber based soft switching inverter circuit for achieving lossless switching of circuit components during single-phase dc-to-ac power conversion, comprising:

a first semiconductor switch having a source, gate, and drain;

a first reverse blocking diode antiparalleled against said first semiconductor switch;

a first capacitance source in parallel with said first semiconductor switch;

a second semiconductor switch having a source, gate, and drain;

a second reverse blocking diode antiparalleled against said second semiconductor switch;

a second capacitance source in parallel with said second semiconductor switch;

means for connecting the source of the first semiconductor switch to the drain of the second semiconductor switch for conducting a first alternating current;

a third semiconductor switch having a source, gate, and drain;

a third reverse blocking diode antiparalleled against said third semiconductor switch;

a third capacitance source in parallel with said third semiconductor switch;

a fourth semiconductor switch having a source, gate, and drain;

a fourth reverse blocking diode antiparalleled against said fourth semiconductor switch;

a fourth capacitance source in parallel with said fourth semiconductor switch;

means for connecting the source of the third semiconductor switch to the drain of the fourth semiconductor switch for conducting a second alternating current;

a protective diode having an anode and a cathode;

a dc voltage source having two terminals;

means for connecting one terminal of the dc voltage source to the drains of the first and third semiconductor switches;

means for connecting the other terminal of the dc voltage source to the sources of the second and fourth semiconductor switches and the anode of said protective diode;

means for connecting the first alternating current to a load;

means for connecting the second alternating current to said load;

a first auxiliary semiconductor switch having a source, gate and drain;

a first inductor;

means for connecting the drain of said first auxiliary semiconductor switch in series with the first inductor;

a second auxiliary semiconductor switch having a source, gate and drain;

a second inductor;

means for connecting the drain of said second auxiliary semiconductor switch in series with the second inductor;

means for connecting the first inductor to the first alternating current;

means for connecting the second inductor to the second alternating current;

means for connecting the sources of the first and second auxiliary semiconductor switches to the cathode of said protective diode; and

means for controlling the gates of all said semiconductor switches;

said semiconductor switches, diodes, and inductors having parameters selected so that resonance is established across the stray capacitances of each semiconductor switch to produce zero voltage across said semiconductor switches during switching of said semiconductor switches.

12. An auxiliary resonant snubber circuit connected to a main inverter circuit for soft switching of inverter circuit main switches during dc-to-ac conversion of power from a dc power source, the snubber circuit comprising:

a plurality of snubber branches connected to said main circuit for selectively conducting current from the dc power source through one or more snubber branches to produce resonant currents that result in zero voltage conditions across predetermined main switches;

wherein each of said plurality of snubber branches includes only an inductor connected in series with a semiconductor switch.