High efficiency bi-directional DC converter and control method thereof

Patent metadata

Field	Value
Publication number	US-9287782-B2
Application number	US-201314068262-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Nov 23, 2012
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Disclosed herein are bi-directional DC converter circuits and control methods. In one embodiment, a method of controlling a bi-directional DC converter, can include: (i) detecting whether there is an input power supply at an input port, where the bi-directional DC converter comprises a single magnetic element; (ii) operating the bi-directional DC converter in a first operation mode to charge a battery when the input power supply is detected at the input port; (iii) operating the bi-directional DC converter in a second operation mode to transfer power from the battery to an output port for a load when the input power supply is not detected at the input port; and (iv) transferring power through the single magnetic element in both the first operation mode and the second operation mode.

First claim

What is claimed is:

1. A method of controlling a bi-directional DC converter, the method comprising:
a) detecting whether there is an input power supply at an input port, wherein said bi-directional DC converter comprises a single magnetic element;
b) operating said bi-directional DC converter in a first operation mode to charge a battery when said input power supply is detected at said input port;
c) operating said bi-directional DC converter in a second operation mode to transfer power from said battery to an output port for a load when said input power supply is not detected at said input port;
d) transferring power through said single magnetic element in both said first operation mode and said second operation mode;
e) comparing, by a first feedback circuit, a current feedback signal of said battery against a first reference voltage to generate a first error signal, comparing a voltage feedback signal of said battery against a second reference voltage to generate a second error signal, and generating a first feedback signal by selecting a lesser of said first and second error signals;
f) comparing, by a second feedback circuit, an output voltage at said output port against a third reference voltage, and generating a second feedback signal; and
g) providing, by a first selection circuit, one of said first and second feedback signals to a pulse-width modulation (PWM) control circuit that controls a charging current of said battery according to said first feedback signal, or said output voltage according to said second feedback signal.

2. The method of claim 1 , further comprising transferring power from said battery or said input port to said output port by using a power transmission branch coupled between said input port and said output port.

3. The method of claim 2 , further comprising controlling a current and an output voltage of said power transmission branch to protect said input power supply and said load of said output port.

4. The method of claim 2 , wherein said operating said bi-directional DC converter in said first operation mode comprises adjusting a charging current of said battery according to a load current requirement of said bi-directional DC converter and a value of said input power supply.

5. The method of claim 4 , wherein said adjusting said charging current of said battery comprises ensuring that said battery is charged at a maximum power and said input power supply will not be overloaded.

6. The method of claim 1 , wherein said first operation mode comprises a synchronous buck mode.

7. The method of claim 1 , wherein said second operation mode comprises a synchronous boost mode.

8. A bi-directional DC converter, comprising:
a) a single magnetic element through which power is configured to be transferred in both a first operation mode and a second operation mode;
b) a detection circuit configured to determine whether there is an input power supply at an input port;
c) said bi-directional DC converter being configured to operate in said first operation mode to charge a battery when said input power supply is detected at said input port, and to operate in said second operation mode to transfer power from said battery to an output port for a load when said input power supply is not detected at said input port;
d) a first feedback circuit configured to compare a current feedback signal of said battery against a first reference voltage to generate a first error signal, to compare a voltage feedback signal of said battery against a second reference voltage to generate a second error signal, and to generate a first feedback signal by selecting a lesser of said first and second error signals;
e) a second feedback circuit configured to compare an output voltage at said output port against a third reference voltage, and to generate a second feedback signal; and
f) a first selection circuit configured to provide one of said first and second feedback signals to a pulse-width modulation (PWM) control circuit that is configured to control a charging current of said battery according to said first feedback signal, or said output voltage according to said second feedback signal.

9. The bi-directional DC converter of claim 8 , further comprising a power transmission branch coupled between said input port and said output port, wherein said power transmission branch is configured to transfer power from said input power supply or said battery to said output port for said load.

10. The bi-directional DC converter of claim 9 , wherein said power transmission branch is configured to control a current and said output voltage to protect said input power supply and said load of said output port.

11. The bi-directional DC converter of claim 9 , wherein said bi-directional DC converter comprises a load detection circuit configured to detect a load condition, and wherein said power transmission branch is configured to be on when said load is detected as a valid state.

12. The bi-directional DC converter of claim 8 , wherein said detection circuit is configured to detect an input current of said input port to determine whether said input power supply is at said input port.

13. The bi-directional DC converter of claim 12 , wherein:
a) said input power supply is detected at said input port when said input current is greater than zero; and
b) said input power supply is not detected at said input port when said input current equals zero.

14. The bi-directional DC converter of claim 8 , further comprising an input current limiting circuit configured to limit an input current of said input power supply when said input power supply is detected at said input port.

15. The bi-directional DC converter of claim 8 , wherein said first operation mode comprises a synchronous buck mode.

16. The bi-directional DC converter of claim 8 , wherein said second operation mode comprises a synchronous boost mode.

17. The bi-directional DC converter of claim 9 , wherein said power transmission branch comprises:
a) a third switch coupled between said input port and said output port; and
b) a protection and control circuit configured to control said third switch to regulate said output voltage.

18. The bi-directional DC converter of claim 17 , wherein said protection and control circuit is configured to control said third switch to regulate a current flowing through said third switch.

19. The bi-directional DC converter of claim 14 , wherein said input current limiting circuit comprises:
a) a detection resistor configured to detect an input current of said input power supply to generate a resistance voltage; and
b) said input current limiting circuit being configured to compare said input power supply against a sum of said resistance voltage and a fourth reference voltage, and to generate a third error signal, wherein said first feedback circuit is configured to select a lesser from among said first error signal, said second error signal, and said third error signal, to generate said first feedback signal.

20. The bi-directional DC converter of claim 14 , wherein said charging current is controlled to be a maximum value when said input power supply is detected at said input port.

Assignees

• Silergy Semiconductor Technology Hangzhou Ltd

Inventors

• Chen Wei

Classifications

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title