Holdup time circuit and method for bridgeless PFC converter

1. A circuit comprising:

a charge device comprising

(a) a first terminal coupled to a bridgeless power factor correction circuit; and

(b) a second terminal coupled to an energy storage apparatus;

a discharge device comprising

(a) a third terminal coupled to the energy storage apparatus; and

(b) a fourth terminal coupled to the bridgeless power factor correction circuit;

the energy storage apparatus; and

the bridgeless power factor correction circuit comprising

(a) a first boost converter, a second boost converter and a first switch coupled between an input of the first boost converter of the bridgeless power factor correction circuit and ground; and

(b) a second switch coupled between an input of the second boost converter of the bridgeless power factor correction circuit and ground.

2. The circuit of claim 1 , wherein the charge device is an n-type metal oxide semiconductor transistor coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus.

3. The circuit of claim 1 , wherein:

the charge device is a diode coupled between an output of a first inductor of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is an n-type metal oxide semiconductor transistor coupled between an input of a second inductor of the bridgeless power factor correction circuit and the energy storage apparatus.

4. The circuit of claim 1 , wherein:

the charge device is a diode coupled between an output of a second inductor of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is an n-type metal oxide semiconductor transistor coupled between an input of a first inductor of the bridgeless power factor correction circuit and the energy storage apparatus.

5. The circuit of claim 1 , wherein:

the charge device is a first n-type metal oxide semiconductor transistor coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is a second n-type metal oxide semiconductor transistor coupled between an input of a first inductor of the bridgeless power factor correction circuit and the energy storage apparatus.

6. The circuit of claim 1 , wherein:

the charge device is a first n-type metal oxide semiconductor transistor coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is a second n-type metal oxide semiconductor transistor coupled between an input of a second inductor of the bridgeless power factor correction circuit and the energy storage apparatus.

7. The circuit of claim 1 , wherein:

the charge device is a first n-type metal oxide semiconductor transistor coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is formed by a second n-type metal oxide semiconductor transistor and a third n-type metal oxide semiconductor transistor, wherein

(a) the second n-type metal oxide semiconductor transistor is coupled between an input of a first inductor of the bridgeless power factor correction circuit and the energy storage apparatus; and

(b) the third n-type metal oxide semiconductor transistor is coupled between an input of a second inductor of the bridgeless power factor correction circuit and the energy storage apparatus.

8. A system comprising:

a bridgeless power factor correction circuit comprising

(a) a first boost converter coupled between an input ac source and an output;

(b) a second boost converter coupled between the input ac source and the output;

(c) a first switch coupled between an input of the first boost converter and ground;

(d) a second switch coupled between an input of the second boost converter and ground;

(e) a first surge protection diode coupled between the input of the first boost converter and the output; and

(f) a second surge protection diode coupled between the input of the second boost converter and the output;

a charge device comprising

(a) a first terminal coupled to the bridgeless power factor correction circuit; and

(b) a second terminal coupled to an energy storage apparatus;

a discharge device comprising

(a) a third terminal coupled to the energy storage apparatus; and

(b) a fourth terminal coupled to the bridgeless power factor correction circuit; and

the energy storage apparatus.

9. The system of claim 8 , further comprising a controller having control signal connections to the charge device, the discharge device and the bridgeless power factor correction circuit.

10. The system of claim 9 , wherein the controller is configured to:

turn on the charge device and turn off the discharge device when the input ac source is in normal operation; and

turn on the discharge device and turn off the charge device when the input ac source has a dropout.

11. The system of claim 9 , wherein the controller is configured to:

in a first half cycle of the input ac source, activate the first boost converter and the second switch; and

in a second half cycle of the input ac source, activate the second boost converter and the first switch.

12. The system of claim 8 , wherein:

the charge device is diode coupled between a first inductor of the first boost converter and the energy storage apparatus; and

the discharge device is a switching element coupled between the energy storage apparatus and an input of the second boost converter.

13. The system of claim 8 , wherein:

the charge device is diode coupled between a second inductor of the second boost converter and the energy storage apparatus; and

the discharge device is a switching element coupled between the energy storage apparatus and an input of the first boost converter.

14. The system of claim 8 , wherein:

the charge device is a first switching element coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is a second switching element coupled between the energy storage apparatus and an input of the bridgeless power factor correction circuit.

15. The system of claim 8 , wherein:

the charge device is a first switching element coupled between an output of the bridgeless power factor correction circuit and the energy storage apparatus; and

the discharge device is formed by a second switching element and a third switching element wherein

the second switching element is coupled between the energy storage apparatus and a first input of the bridgeless power factor correction circuit; and

the third switching element is coupled between the energy storage apparatus and a second input of the bridgeless power factor correction circuit.

16. A method comprising:

charging an energy storage apparatus through a charge device, wherein the charge device is coupled between a bridgeless power factor correction circuit and the energy storage apparatus;

detecting a dropout of an input ac source; and

discharging the energy storage apparatus through a discharge device, wherein the discharge device is coupled between the energy storage apparatus and an input of the bridgeless power factor correction circuit.

17. The method of claim 16 , further comprising:

detecting a first half cycle of the input ac source;

activating a first boost converter and a second switch coupled between an input of a second boost converter and ground; and

charging the energy storage apparatus from the first boost converter through the charge device.

18. The method of claim 16 , further comprising:

detecting a second half cycle of the input ac source;

activating a second boost converter and a first switch coupled between an input of a first boost converter and ground; and

charging the energy storage apparatus from the second boost converter through the charge device.

19. The method of claim 16 , further comprising:

detecting the dropout of the input ac source using a controller;

activating the discharge device using the controller; and

activating a first boost converter.

20. The method of claim 16 , further comprising:

detecting the dropout of the input ac source using a controller;

activating the discharge device using the controller; and

activating a second boost converter.