Reverse current protection circuit and power supply system

Abstract

A circuit for preventing reverse current is provided. The circuit includes a first voltage output terminal, a second voltage output terminal, a first voltage input terminal, a second voltage input terminal, a first diode, a first relay, and a second relay. The circuit controls the voltage polarity between the first and second voltage output terminals. The first diode is coupled to the first voltage input terminal. The first relay is coupled to the first diode and the second voltage input terminal. The first relay conducts its first common terminal and its first normally open terminal based on a first current from the first diode. The second relay is coupled to the first diode and the second voltage input terminal. The second relay conducts its second common terminal and its second normally open terminal based on a second current from the first diode.

Claims

1. A circuit for preventing reverse current, comprising: a first voltage output terminal and a second voltage output terminal, wherein the circuit is used to control a voltage polarity between the first and second voltage output terminals; a first voltage input terminal and a second voltage input terminal; a first diode coupled to the first voltage input terminal; a first relay coupled to the first diode and the second voltage input terminal, the first relay being used to conduct a first common terminal and a first normally open terminal of the first relay according to a first current from the first diode, wherein the first common terminal is coupled to the first voltage input terminal and the first normally open terminal is coupled to the first voltage output terminal; and a second relay coupled to the first diode and the second voltage input terminal, the second relay being used to conduct a second common terminal and a second normally open terminal of the second relay according to a second current from the first diode, the second common terminal being coupled to the second voltage input terminal and the second normally open terminal being coupled to the second voltage output terminal.

2. The circuit as claimed in claim 1 further comprises: a third diode coupled to the first voltage input terminal; and a third relay coupled to the third diode, wherein a third common terminal of the third relay is coupled to the first normally open terminal and the first voltage output terminal, and a third normally open terminal of the third relay is coupled to the second voltage input terminal.

3. The circuit as claimed in claim 2 further comprises: a third diode coupled between the second voltage input terminal and the third relay, wherein the third relay conducts the third common terminal and the third normally open terminal according to a third current from the third diode.

4. The circuit as claimed in claim 3 further comprises: a fourth relay, wherein a first coil terminal of the fourth relay is coupled to the third diode and the third relay, a second coil terminal of the fourth relay is coupled to the first voltage input terminal, a fourth common terminal of the fourth relay is coupled to the first voltage input terminal, and a fourth normally open terminal of the fourth relay is coupled to the second voltage output terminal.

5. The circuit as claimed in claim 1 further comprises: a fourth diode coupled between a third coil terminal and a fourth coil terminal of the second relay for adjusting the voltage between the third coil terminal and the fourth coil terminal.

6. The circuit as claimed in claim 1, wherein the first voltage input terminal is coupled to a DC power supply and the second voltage input terminal is coupled to ground.

7. The circuit of claim 1, wherein the first voltage output terminal is used to provide a first voltage level to a positive power supply voltage terminal of a load, and the second voltage output terminal is used to provide a second voltage level to a negative power supply voltage terminal of the load.

8. The circuit as claimed in claim 1 further comprises: a control circuit coupled to the first voltage output terminal, wherein the control circuit is configured to control the voltage of a first power supply voltage terminal of a load according to the voltage of the first voltage output terminal, wherein a second power supply voltage terminal of the load is coupled to the second voltage output terminal.

9. The circuit as claimed in claim 8 further comprises: a third relay, wherein a first coil terminal of the third relay is coupled to the control circuit, a second coil terminal of the third relay is coupled to the second voltage output terminal, a third common terminal of the third relay is coupled to the first voltage output terminal, and a third normally open terminal of the third relay is coupled to the first power supply voltage terminal.

10. The circuit as claimed in claim 1 further comprises: a light-emitting diode coupled to the first voltage output terminal and used to emit light to indicate the voltage polarity.

11. A power supply system, comprising: a reverse current protection circuit, including: a first voltage output terminal and a second voltage output terminal, the reverse current protection circuit being used to control the voltage polarity between the first and second voltage output terminals; a first voltage input terminal and a second voltage input terminal; a first diode and a second diode, respectively coupled to the first and second voltage input terminals; a first relay, coupled to the first diode and the second voltage input terminal, wherein the first relay is used to conduct a first common terminal and a first normally open terminal of the first relay according to the current from the first diode, wherein the first common terminal is coupled to the first voltage input terminal, and the first normally open terminal is coupled to the first voltage output terminal; And a second relay coupled to the second diode and the first common terminal, wherein the first relay is used to turn on a second common terminal and a second normally open terminal of the second relay according to the current from the second diode, wherein the first normally open terminal is coupled to the second voltage input terminal; And an alarm circuit, coupled to the first voltage output terminal, and used to indicate the voltage polarity between the first and second voltage input terminals.

12. The power supply system of claim 11, wherein the reverse current protection circuit further comprises: a third relay coupled to the first diode and the second voltage input terminal, wherein the third relay is configured to turn on a third common terminal of the third relay and a third normally open terminal of the first relay according to the current from the first diode.

13. The power supply system as claimed in claim 11 further includes: a DC power supply circuit for providing a power supply voltage to the first voltage input terminal.

14. The power supply system of claim 11, wherein the reverse current protection circuit further comprises: a third relay coupled to the second diode and the first voltage input terminal, wherein the third relay is configured to switch on a third common terminal according to the current from the second diode.

15. The power supply system as claimed in claim 14, wherein the reverse current protection circuit further comprises: a third diode coupled between a first coil terminal and a second coil terminal of the third relay, and used to adjust the voltage between the first coil terminal and the second coil terminal.

16. The power supply system as claimed in claim 11, wherein the first voltage input terminal is coupled to a DC power supply and the second voltage input terminal is coupled to ground.

17. The power supply system of claim 11 further comprises: a load having a positive power supply voltage terminal and a negative power supply voltage terminal, wherein the positive power supply voltage terminal is coupled to the first voltage output terminal and the negative power supply voltage terminal is coupled to the second voltage output terminal.

18. The power supply system of claim 11, wherein the warning circuit further comprises: a control circuit having a positive power supply voltage terminal and a negative power supply voltage terminal, wherein the positive power supply voltage terminal is coupled to the first voltage output terminal and the negative power supply voltage terminal is coupled to the second voltage output terminal, wherein the control circuit is configured to generate an output voltage based on the voltage of the first voltage output terminal to provide a power supply voltage to a load.

19. The power supply system of claim 18, wherein the warning circuit further comprises: a third relay, wherein a first coil terminal of the third relay is coupled to the control circuit, a second coil terminal of the third relay is coupled to the second voltage output terminal, a third common terminal of the third relay is coupled to the first voltage output terminal, and a third normally open terminal of the third relay is coupled to the load.

20. The power supply system as claimed in claim 11, wherein the warning circuit further comprises: a light-emitting diode coupled to the first voltage output terminal and used to emit light to indicate the voltage polarity.

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