3-Phase High Power UPS

• US 20080197706A1
• Filed: 02/21/2007
• Published: 08/21/2008
• 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
• Granted Patent: US 7,688,048 B2
• Time in Patent Office: Days
• US Class Current: 307/66
• 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 batter. 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. An uninterruptible power supply (UPS) comprising:

a plurality of electrical buses;

a first AC/DC converter coupled to the electrical buses and configured to receive a first input AC voltage and to convert the first input AC voltage to a plurality of DC voltages, the first AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses;

a second AC/DC converter coupled to the electrical buses and configured to receive a second input AC voltage and to convert the second input AC voltage to the plurality of DC voltages, the second AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses;

a third AC/DC converter coupled to the electrical buses and configured to receive a third input AC voltage and to convert the third input AC voltage to the plurality of DC voltages, the third AC/DC converter being configured to convey the plurality of DC voltages to the plurality of electrical buses;

a DC/DC converter coupled to the plurality of electrical buses and configured to;

convert the plurality of DC voltages to a battery DC voltage; and

convert the battery DC voltage to the plurality of DC voltages;

a first DC/AC converter coupled to the plurality of electrical buses and configured to receive the plurality of DC voltages and to convert the plurality of DC voltages into a first output AC voltage; and

a DC bus balancer configured to maintain voltages present on the electrical buses at desired levels, the DC bus balancer being configured to transfer energy between the plurality of electrical buses;

wherein the first, second, and third AC/DC converters are configured such that the first, second, and third AC/DC converters convey the plurality of DC voltages to the plurality of electrical buses when the first, second, and third input AC voltages are within a predetermined threshold; and

wherein the DC/DC converter is configured such that the DC/DC converter conveys the plurality of DC voltages to the plurality of the electrical buses when the first, second, and third input AC voltages are not within the predetermined threshold.

2. The UPS of claim 1 further comprising:

a second DC/AC converter coupled to the plurality of electrical buses and configured to receive the plurality of DC voltages and to convert the plurality of DC voltages into a second output AC voltage; and

a third DC/AC converter coupled to the plurality of electrical buses and configured to receive the plurality of DC voltages and to convert the plurality of DC voltages into a third output AC voltage.

3. The UPS of claim 2 wherein the first, second, and third DC/AC converters are configured to convey 3-phase power to a load.

4. The UPS of claim 1 wherein:

the DC/DC converter is configured to convert the plurality of DC voltages to the battery DC voltage when the first, second, and third input AC voltages are within a predetermined range; and

the DC/DC converter is configured to convert the battery DC voltage to the plurality of DC voltages when the first, second, and third input AC voltages are not within the predetermined range.

5. The UPS of claim 1 wherein a battery is coupled to the DC/DC converter and is configured to:

receive and be charged by the battery DC voltage; and

convey the battery DC voltage to the DC/DC converter.

6. The UPS of claim 1 wherein

the first AC/DC converter is coupled to a first phase of a 3-phase power source;

the second AC/DC converter is coupled to a second phase of a 3-phase power source; and

the third AC/DC converter is coupled to a third phase of a 3-phase power source.

7. An AC/DC converter comprising:

an input configured to receive an AC power signal having a positive peak voltage and a negative peak voltage;

first, second, third, and fourth outputs;

an inductor coupled to the input;

first and second switches coupled in series between the inductor and the first output, the first switch being coupled to the inductor;

a third switch coupled to the junction of the first and second switches and the second output;

fourth and fifth switches coupled in series between the inductor and the fourth output, the fourth switch being coupled to the inductor;

a sixth switch coupled to the junction of the fourth and fifth switches and the third output;

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; and

a sixth diode coupled in parallel with the sixth switch.

8. The AC/DC converter of claim 7 further comprising a controller coupled to the first, second, third, fourth, fifth, and sixth switches.

9. The AC/DC converter of claim 8 wherein the controller is configured to toggle the first, second, third, fourth, fifth, and sixth switches such that a first output DC voltage is conveyed to the first output, a second output DC voltage is conveyed to the second output, a third output DC voltage is conveyed to the third output, and a fourth output DC voltage is conveyed to the fourth output.

10. The AC/DC converter of claim 9 wherein

the first output DC voltage is equal to or greater than the positive peak input voltage multiplied by

$\frac{\sqrt{2}}{\sqrt{3}};$

the second output DC voltage is substantially equal to one-third of the first output DC voltage;

the third output DC voltage is substantially equal to one-third of the fourth output DC voltage; and

the fourth output DC voltage is equal to or less than the negative peak input voltage multiplied by

$\frac{\sqrt{2}}{\sqrt{3}}.$

11. The AC/DC converter of claim 8 wherein the controller is further configured to:

cause, when an instantaneous voltage of the AC power signal is between the first and second output DC voltages, the AC/DC converter to operate in a first state where;

the first switch is toggled on;

the second switch is repeatedly toggled on and off;

the third switch is repeatedly toggled on and off;

the fourth switch is toggled off;

the fifth switch is toggled off;

the sixth switch is toggled on;

cause, when the instantaneous voltage of the AC power signal is between the second and third output DC voltages, the AC/DC converter to operate in a second state where;

the first switch is repeatedly toggled on and off;

the second switch toggled off;

the third switch is toggled on;

the fourth switch is repeatedly toggled on and off;

the fifth switch is toggled off;

the sixth switch is toggled on;

cause, when the instantaneous voltage of the AC power signal is between the third and fourth output DC voltages, the AC/DC converter to operate in a third state where;

the first switch is toggled off;

the second switch toggled off;

the third switch is toggled on;

the fourth switch is toggled on;

the fifth switch is repeatedly toggled on and off; and

the sixth switch is repeatedly toggled on and off.

12. The AC/DC converter of claim 8 wherein the controller is pulse width modulation (PWM) controller.

13. The AC/DC converter of claim 12 wherein the PWM controller is configured to use a feedback loop to control the actuation of the first, second, third, fourth, fifth, and sixth switches.

14. The AC/DC converter of claim 7 further comprising a capacitor coupled between the input and a neutral.

15. The AC/DC converter of claim 7 further comprising:

a first capacitor coupled between the first and second outputs;

a second capacitor coupled between the second output and a neutral;

a third capacitor coupled between the neutral and the third output; and

a fourth capacitor coupled between the third output and the fourth output.

16. A DC/AC converter configured to convey an AC power signal having a positive peak voltage and a negative peak voltage, the DC/AC converter comprising:

an output configured to convey the AC power signal;

first, second, third, and fourth inputs, each being configured to receive a respective input voltage;

a filter coupled to the output;

first and second switches coupled in series between the filter and the first input, the first switch being coupled to the filter;

a third switch coupled to a junction of the first and second switches and the second input;

fourth and fifth switches coupled in series between the filter and the fourth input, the fourth switch being coupled to the filter;

a sixth switch coupled to a junction of the fourth and fifth switches and the third input;

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; and

a sixth diode coupled in parallel with the sixth switch.

17. The DC/AC converter of claim 16 further comprising a controller coupled to the first, second, third, fourth, fifth, and sixth switches.

18. The DC/AC converter of claim 17 wherein the controller is configured to toggle the first, second, third, fourth, fifth, and sixth switches such that the AC power signal is induced at the output.

19. The DC/AC converter of claim 18 wherein the controller is configured to toggle the first, second, third, fourth, fifth, and sixth switches such that:

the positive peak voltage of the output AC power signal is less than the DC voltage conveyed to the first input multiplied by

$\frac{\sqrt{3}}{\sqrt{2}};<br><br>\mathrm{and}$

the negative peak voltage of the output AC power signal is greater than the DC voltage conveyed to the fourth input multiplied by

$\frac{\sqrt{3}}{\sqrt{2}}.$

20. The DC/AC converter of claim 19 wherein the controller is configured to:

cause, when the AC power signal is between the DC voltages conveyed on the first and second inputs, the DC/AC converter to operate in a first state where;

the first switch is toggled on;

the second switch is repeatedly toggled on and off;

the third switch is repeatedly toggled on and off;

the fourth switch is toggled off;

the fifth switch is toggled off;

the sixth switch is toggled on;

cause, when the AC power signal is between the DC voltages conveyed on the second and third inputs, the DC/AC converter to operate in a second state where;

the first switch is repeatedly toggled on and off;

the second switch toggled off;

the third switch is toggled on;

the fourth switch is repeatedly toggled on and off;

the fifth switch is toggled off;

the sixth switch is toggled on;

cause, when the AC power signal is between the DC voltages conveyed on the third and fourth inputs, the DC/AC converter to operate in a third state where;

the first switch is toggled off;

the second switch toggled off;

the third switch is toggled on;

the fourth switch is toggled on;

the fifth switch is repeatedly toggled on and off; and

the sixth switch is repeatedly toggled on and off.

21. The DC/AC converter of claim 16 wherein the filter comprises:

an inductor coupled between the output and the junction of first and fourth switches; and

a capacitor coupled between the output and a neutral.

22. The DC/AC converter of claim 16 wherein the first, second, third, fourth, fifth, and sixth switches are configured to be controlled by a pulse width modulation (PWM) controller.

23. The DC/AC converter of claim 22 wherein the PWM controller coupled to the output and configured to control the actuation of the first, second, third, fourth, fifth, and sixth switches in accordance with a voltage level of the output.

24. The AC/DC converter of claim 16 further comprising:

a first capacitor coupled between the first and second inputs;

a second capacitor coupled between the second input and a neutral;

a third capacitor coupled between the neutral and the third input; and

a fourth capacitor coupled between the third and fourth inputs.

25. A DC/DC converter for use with a battery, the DC/DC converter comprising:

first and second battery nodes configured to be coupled to the battery;

first, second, third, and fourth bus nodes;

first and second switches coupled in series between the first and second bus nodes wherein the first switch is coupled to the first bus node and the second switch is coupled to the second bus node;

a first buck-boost converter coupled to a junction of the first and second switches, to a neutral, and to the first battery node;

third and fourth switches coupled in series between the third and fourth bus nodes wherein the third switch is coupled to the third bus node and the fourth switch is coupled to the fourth bus node; and

a second buck-boost converter coupled to a junction of the third and fourth switches, to the neutral, and to the second battery node;

a first diode coupled across the first switch;

a second diode coupled across the second switch;

a third diode coupled across the third switch;

a fourth diode coupled across the fourth switch;

wherein the DC/DC converter is configured to operate in a first state to charge the battery using energy conveyed by at least one of the first, second, third, and fourth bus nodes; and

wherein the DC/DC converter is configured to operate in a second state to convey a DC voltage to at least one of the first, second, third, and fourth bus nodes using energy conveyed by the battery.

26. The DC/DC converter of claim 25 wherein:

in the first state the first and second buck-boost converters function as a buck-converter; and

in the second state the first and second buck-boost converters function as a boost converter.

27. The DC/DC converter of claim 25 wherein:

the first buck-boost converter comprises;

a first inductor coupled to the junction of the first and second switches and to the first battery node;

a first capacitor coupled between the first battery node and the neutral;

the second buck-boost converter comprises;

a second inductor coupled to the junction of the third and fourth switches and the second battery node;

a second capacitor coupled between the second battery node and the neutral.

28. The DC/DC converter of claim 25 further comprising a controller coupled to the first, second, third, and fourth switches.

29. The DC/DC converter of claim 28 wherein the controller is configured to:

in the first state;

repeatedly toggle the first and fourth switches on and off;

switch the second and third switches to an off state;

in the second state;

switch the first and fourth switches to an off state; and

repeatedly toggle the second and third switches on and off.

30. The DC/DC converter of claim 28 wherein the controller is a pulse width modulation (PWM) controller.

31. The DC/DC converter of claim 28 wherein the controller is configured to use a feedback loop to control the first, second, third, and fourth switches.

32. The DC/DC converter of claim 25 further comprising a third battery node coupled to the neutral.

33. The DC/DC converter of claim 25 further comprising:

a first capacitor coupled between the first and second bus nodes;

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

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

a fourth capacitor coupled between the third and fourth bus nodes.

34. 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.

35. The circuit of claim 34 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.

36. The circuit of claim 34 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.

37. The circuit of claim 36 wherein the controller is a pulse width modulation (PWM) controller.

38. The circuit of claim 36 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.

39. The circuit of claim 36 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.

40. The circuit of claim 36 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.

41. The circuit of claim 36 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.

42. The circuit of claim 34 further comprising a third inductor coupled between the junction of the third and fourth switches and a neutral.

43. The circuit of claim 34 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.

44. An AC/DC converter comprising:

an input configured to receive an AC power signal having a positive peak voltage and a negative peak voltage;

first, second, third, and fourth outputs;

an inductor coupled to the input;

a first circuit coupled to the inductor and to the first and second outputs, the first circuit being configured to operate in at least three states, wherein;

in a first state the first circuit is configured such that the inductor charges, and a first substantially DC voltage is conveyed to the second output;

in a second state the first circuit is configured such that the inductor discharges, and a second substantially DC voltage is conveyed to the first output;

in a third state the first circuit is configured such that the inductor discharges, and the first substantially DC voltage is conveyed to the second output;

a second circuit coupled to the inductor and to the third and fourth outputs, the second circuit being configured to operate in at least three states, wherein;

in a first state, the second circuit is configured such that the inductor charges, and a third substantially DC voltage is conveyed to the third output;

in a second state, the second circuit is configured such that the inductor discharges, and a fourth substantially DC voltage is conveyed to the fourth output; and

in a third state, the second circuit is configured such that the inductor charges, and the third substantially DC voltage is conveyed to the third output.

45. The AC/DC converter of claim 44 wherein:

an absolute value of the first and fourth substantially DC voltages are substantially equal; and

an absolute value of the second and third substantially DC voltages are substantially equal.

46. The AC/DC converter of claim 44 wherein:

the first substantially DC voltage is equal to or greater than the positive peak voltage multiplied by

$\frac{\sqrt{2}}{\sqrt{3}};<br><br>$

the second substantially DC voltage is substantially equal to one-third of the first substantially DC voltage;

the third substantially DC voltage is substantially equal to one-third of the fourth substantially DC voltage; and

the fourth substantially DC voltage is substantially equal to or less than the negative peak voltage multiplied by

$\frac{\sqrt{2}}{\sqrt{3}}.$

47. The AC/DC converter of claim 44 further comprising a controller configured to control which state the first and second circuits operate in.

48. The AC/DC converter of claim 47 wherein the controller is configured to:

vary the duty cycle of when the first circuit operates in the first and second states; and

vary the duty cycle of when the second circuit operates in the first and second states.

49. The AC/DC converter of claim 47 wherein the controller is a pulse width modulation (PWM) controller.