3-phase high power UPS

• US 7,688,048 B2
• Filed: 02/21/2007
• Issued: 03/30/2010
• Est. Priority Date: 02/21/2007
• Status: Active Grant

• Current Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Nielsen, Henning Roar
• Primary Examiner(s): Paladini; Albert W
• Assistant Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US11/677,303
• Publication Number:
  US 20080197706A1
• Time in Patent Office: 1,133 Days
• Field of Search: 323/265, 323/267, 323/268, 323/282, 307/151, 361/90
• US Class Current: 323/268
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 5/40 with intermediate conversion into dc
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters

Abstract

A 3-phase uninterruptible power supply (UPS) including first, second, and third AC/DC converters, a DC/DC converter, and at least one DC/AC converter coupled to multiple electrical buses. The first, second, and third AC/DC converters each being configured to receive AC power and to provide multiple DC signals to the multiple electrical buses. The DC/DC converter being configured to convert DC voltages present on the multiple electrical buses to a DC voltage that can be used to charge a battery. The DC/AC converter being configured to receive DC power from the multiple electrical buses and to provide an AC output. The 3-phase UPS being configured such that when suitable AC power is provided to the AC/DC converters, the DC/DC converter is configured to charge a battery, and when suitable AC power is not provided to the AC/DC converters, the DC/DC converter is configured to provide DC power to the multiple electrical buses using power provided by the battery.

Claims

1. A circuit for use with four-level DC power including first, second, third, and fourth voltages, the circuit comprising:

first, second, third, and fourth nodes configured to receive the four-level DC power;

first, second, third, fourth, fifth, and sixth switches coupled in series between the first and fourth nodes, wherein the second node is coupled to a junction of the second and third switches and the third node is coupled to a junction of the fourth and fifth switches;

a first diode coupled in parallel with the first switch;

a second diode coupled in parallel with the second switch;

a third diode coupled in parallel with the third switch;

a fourth diode coupled in parallel with the fourth switch;

a fifth diode coupled in parallel with the fifth switch;

a sixth diode coupled in parallel with the sixth switch;

a first resonant tank coupled to a junction of the first and second switches and to the junction of the third and fourth switches; and

a second resonant tank coupled to the junction of the third and fourth switches and to the junction of the fifth and sixth switches;

wherein the first and second resonant tanks are configured to shift energy between at least two of the first, second, third, and fourth nodes if an absolute value of the first voltage differs from an absolute value of the fourth voltage; and

wherein the first and second resonant tanks are configured to shift energy between at least two of the first, second, third, and fourth nodes if an absolute value of the second voltage differs from an absolute value of the third voltage.

2. The circuit of claim 1 wherein:

the first resonant tank comprises a first capacitor coupled in series with a first inductor; and

the second resonant tank comprises a second capacitor coupled in series with a second inductor.

3. The circuit of claim 1 wherein the circuit further comprises a controller configured to actuate the first, second, third, fourth, fifth, and sixth switches into respective on and off states.

4. The circuit of claim 3 wherein the controller is a pulse width modulation (PWM) controller.

5. The circuit of claim 3 wherein the controller is configured to cause the circuit to operate in one of two states, wherein:

in a first state the first, third, and fifth switches are in the respective on states and the second, fourth, and sixth switches are in their respective off states; and

in a second state, the first, third, and fifth switches are in their respective off states and the second, fourth, and sixth switches are actuated in their respective on states.

6. The circuit of claim 3 wherein the controller is configured to cause the circuit to repeatedly alternate between the first and the second states at a frequency substantially equal to the resonant frequencies of the first and second resonant tanks.

7. The circuit of claim 3 wherein the controller is configured to cause the circuit to repeatedly alternate between the first and second states such that amplitudes of square waves induced at junctions of the second and third switches, the third and fourth switches, and the fifth and sixth switches are substantially equal when the absolute value of the first and fourth voltages are substantially equal and the absolute value of the second and third voltages are substantially equal.

8. The circuit of claim 3 wherein the controller is configured to cause the first, second, third, fourth, fifth, and sixth switches to alternate between the first and second states at substantially a fifty percent duty cycle.

9. The circuit of claim 1 further comprising a third inductor coupled between the junction of the third and fourth switches and a neutral.

10. The circuit of claim 1 further comprising:

a first capacitor is coupled between the first node and the second node;

a second capacitor is coupled between the second node and a neutral;

a third capacitor is coupled between the neutral and the third node; and

a fourth capacitor is coupled between the third node and the fourth node.