LPS architecture for UPS systems

• US 9,979,218 B2
• Filed: 11/22/2013
• Issued: 05/22/2018
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Prakash, Indra
• Primary Examiner(s): Cox, Cassandra
• Application Number:
  US15/035,475
• Publication Number:
  US 20160352127A1
• Time in Patent Office: 1,642 Days
• Field of Search: None
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02J 9/067 using multi-primary transformers, e.g. transformer having one primary for each AC energy source and a secondary for the loads

Abstract

At least some embodiments herein provide a UPS comprising an input, a transformer including at least one primary winding, a relay, a sense circuit, and a current control circuit, wherein the sense circuit is configured to monitor input power, control the relay to couple, in a first mode, the input to the at least one primary winding when input power is above an input threshold, and control the relay to decouple, in a second mode, the input from the at least one primary winding when input power is below the input threshold, and wherein the current control circuit is configured, in the first mode, to control current from an AC source through the at least one primary winding to generate an output voltage and, in the second mode, to control current from a DC source through the at least one primary winding to generate the output voltage.

Claims

1. An Uninterruptible Power Supply (UPS) system, the UPS system comprising:

an input configured to be coupled to an AC power source;

a transformer including;

at least one primary winding configured to be coupled to a DC power source; and

at least one secondary winding;

a relay configured to selectively couple the input to the at least one primary winding;

a sense circuit coupled to the input and the relay;

a current control circuit coupled to the at least one primary winding; and

at least one output line coupled to the at least one secondary winding,

wherein the sense circuit is configured to monitor a level of input AC power at the input, determine whether the level of input AC power is above an input power threshold level, control the relay to couple, in a first mode of operation of the UPS, the input to the at least one primary winding in response to a determination that the input AC power is above the input power threshold level, and control the relay to decouple, in a second mode of operation of the UPS, the input from the at least one primary winding in response to a determination that the input AC power is below the input power threshold level, and

wherein the current control circuit is configured, in the first mode of operation of the UPS, to control current from the AC power source through the at least one primary winding to generate an output voltage at the at least one output line and, in the second mode of operation of the UPS, to control current from the DC power source through the at least one primary winding to generate the output voltage at the at least one output line.

2. The UPS system of claim 1, wherein the at least one primary winding of the transformer includes:

a first primary winding selectively coupled to the input via the relay; and

a second primary winding configured to be coupled to the DC source via a DC line.

3. The UPS system of claim 2, wherein the relay is configured to selectively couple the input to the first primary winding, wherein the sense circuit is configured, in the first mode of operation of the UPS, to control the relay to couple the input to the first primary winding, and wherein the current control circuit is configured, in the first mode of operation of the UPS, to control current from the AC power source through the first primary winding to generate the output voltage at the at least one output line.

4. The UPS system of claim 2, wherein the sense circuit is configured, in the second mode of operation of the UPS, to control the relay to decouple the input from the first primary winding, and wherein the current control circuit is configured, in the second mode of operation of the UPS, to control current from the DC power source through the second primary winding to generate the output voltage at the at least one output line.

5. The UPS system of claim 2, further comprising a current limit changing circuit configured to be coupled between the DC power source and the transformer, wherein the current control circuit is further configured to operate the current limit changing circuit to adjust a current limit of the transformer in the second mode of operation of the UPS.

6. The UPS system of claim 2, further comprising:

a controller coupled to the DC line;

a converter coupled to the input;

an inverter coupled to the converter via a DC bus; and

a battery charger coupled to the DC bus and the DC line,

wherein the DC power source is a battery coupled to the DC line,

wherein the battery charger is configured to provide DC power from the DC bus to the battery and DC line, and

wherein the controller is configured to monitor a voltage level of the DC line and, in response to determining that the voltage level of the DC line is above a DC line voltage threshold, to operate the sense circuit to drive the UPS into the second mode of operation.

7. The UPS system of claim 6, further comprising:

a DC bus line coupled between the DC bus and the first primary winding; and

a switch configured to selectively couple the battery and battery charger to the second primary winding,

wherein, in a third mode of operation of the UPS, the controller is further configured, in response to determining that the voltage level of the DC line is below the DC line voltage threshold, to operate the switch to decouple the battery and battery charger from the second primary winding, and

wherein, in the third mode of operation of the UPS, the current control circuit is further configured to control current from the DC bus line through the first primary winding to generate the output voltage at the at least one output line.

8. The UPS system of claim 6, further comprising:

a neutral line selectively coupled to the input via the relay and selectively coupled to the input via a neutral backfeed relay,

wherein in the second mode of operation of the UPS, the sense circuit is configured to control the relay to decouple the input from the neutral line, and

wherein in the second mode of operation of the UPS, the controller is configured to control the neutral backfeed relay to couple the input to the neutral line.

9. The UPS system of claim 6, further comprising a manual switch coupled to the switch, wherein the manual switch is configured to operate the switch to couple the battery and battery charger to the second primary winding in response to a user activating the manual switch.

10. The UPS system of claim 1, wherein the transformer is a flyback transformer.

11. The UPS system of claim 1, wherein the sense circuit comprises a sense transformer coupled to the input and configured to receive the input AC power and generate an AC input power sense signal related to the input AC power.

12. The UPS system of claim 11, wherein the sense circuit further comprises:

a first rectifier coupled to the sense transformer and configured to rectify the AC input power sense signal into a rectified signal; and

a voltage regulator coupled to the first rectifier and the relay and configured to generate a supply voltage based on the rectified signal and provide the supply voltage to the relay.

13. The UPS system of claim 12, wherein the sense circuit further comprises:

a second rectifier coupled to the input and configured to rectify the input AC power into a rectified input power sense signal;

an amplifier coupled to the second rectifier and configured to generate an input reference signal based on the rectified input power sense signal; and

a comparator coupled to the amplifier and configured to compare the input reference signal to the input power threshold level and provide a relay control signal to the relay to operate the relay to couple the input to the at least one primary winding in response to a determination that the input reference signal is above the input power threshold level.

14. The UPS system of claim 13, wherein the comparator is further configured to provide the relay control signal to the relay to operate the relay to decouple the input from the at least one primary winding in response to a determination that the input reference signal is below the input power threshold level.

15. The UPS system of claim 12, wherein the at least one output line is coupled to the relay and configured to provide the output voltage to the relay.

16. A method for providing DC power within a UPS system comprising an input configured to be coupled to an AC power source, and a transformer including a first primary winding configured to be coupled to the AC power source, a second primary winding configured to be coupled to a DC power source, and at least one secondary winding coupled to at least one output line, the method comprising:

monitoring a level of input AC power at the input;

determining, with a sense circuit coupled to the input, whether the level of input AC power is above an input power threshold;

coupling, in a first mode of operation of the UPS, the input to the first primary winding in response to a determination by the sense circuit that the input AC power is above the input power threshold;

decoupling, in a second mode of operation of the UPS, the input from the first primary winding in response to determination by the sense circuit that the input AC power is below the input power threshold;

controlling current, in the first mode of operation of the UPS, from the AC power source through the first primary winding to generate an output voltage at the at least one output line; and

controlling current, in the second mode of operation of the UPS, from the DC power source through the second primary winding to generate the output voltage at the at least one output line.

17. The method of claim 16, further comprising adjusting a current limit of the transformer in the second mode of operation of the UPS.

18. The method of claim 16, wherein the UPS system further comprises a converter coupled to the input, an inverter coupled to the converter via a DC bus, and a battery charger coupled to the DC bus, wherein the DC power source is a battery coupled to the battery charger, and wherein the method further comprises:

monitoring a level of voltage provided by the battery and the battery charger to the second primary winding;

determining whether the level of voltage provided by the battery and the battery charger to the second primary winding is above a DC voltage threshold; and

operating the UPS in the second mode of operation in response to a determination that the level of voltage provided by the battery and the battery charger to the second primary winding is above the DC voltage threshold.

19. The method of claim 18, further comprising:

operating the UPS in a third mode of operation in response to a determination that the level of voltage provided by the battery and the battery charger to the second primary winding is below the DC voltage threshold; and

controlling, in the third mode of operation of the UPS, current from the DC bus through the first primary winding to generate the output voltage at the at least one output line.

20. An Uninterruptible Power Supply (UPS), the UPS comprising:

an input configured to be coupled to an AC mains supply;

a converter coupled to the input;

an inverter coupled to the converter with a DC bus;

a battery charger coupled to the DC bus;

a DC power source coupled to the battery charger;

a transformer coupled to the AC mains supply, the DC power source, and the DC bus; and

means for selecting one of the AC mains supply, the DC power source, and the DC bus to provide power to the transformer and for generating an output DC voltage with the transformer based on the power received from the selected one of the AC mains supply, the DC power source, and the DC bus.