CURRENT BALANCE CIRCUIT

• US 20130002214A1
• Filed: 09/26/2011
• Published: 01/03/2013
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: CHIU, YI-GUO
• Granted Patent: US 8,482,265 B2
• Time in Patent Office: Days
• US Class Current: 323/271
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: H03K 17/122 in field-effect transistor switches
• CPC Class Codes: H03K 17/145 in field-effect transistor switches

Abstract

A current balance circuit includes a first branch and a second branch in parallel between a power supply unit and at least one load, which respectively include a switch. The current balance circuit detects and compares currents flowing through the first branch and the second branch. The current balance circuit also generates triangle waves and reversed triangle waves, compares voltage of a control pole of a first switch with the triangle waves, and compares voltage of the control pole of a second switch with the reversed triangle waves. Then the current balance circuit controls if the triangle waves and the reversed triangle waves are input to the first switch and the second switch according to the currents flowing through the first branch and the second branch to adjust impedance of the first switch and the second switch to balance the currents flowing through the first branch and the second branch.

Claims

1. A current balance circuit, comprising:

a first branch, comprising a first switch with a control pole and a first resistor connected in series between a power supply unit and at least one load;

a second branch, comprising a second switch with a control pole and a second resistor connected in series between the power supply and the at least one load;

a current feedback and comparison circuit, connected to the first resistor and the second resistor in parallel, to detect and compare currents flowing through the first branch and the second branch;

a triangle and reversed triangle wave generator, to generate triangle waves and reversed triangle waves;

a first multiplexer, comprising a first input terminal, a second input terminal, a control terminal, and an output terminal, the first input terminal receiving the triangle waves, the second input terminal being suspended, and the output terminal outputting first control signals to the control pole of the first switch to control the first switch and connected to the ground via a first capacitor;

a second multiplexer, comprising a first input terminal, a second input terminal, a control terminal, and an output terminal, the first input terminal of the second multiplexer receiving the reversed triangle waves, the second input terminal of the second multiplexer being suspended, and the output terminal of the second multiplexer outputting second control signals to the control pole of the second switch to control the second switch and connected to the ground via a second capacitor; and

a gate signal control circuit, connected to the current feedback and comparison circuit, the first switch, the second switch, the triangle and reversed triangle wave generator, and the control terminals of the first multiplexer and the second multiplexer, to compare voltage of the control pole of the first switch with the triangle waves, compare voltage of the control pole of the second switch with the reversed triangle waves, and to control input switch of the first multiplexer and the second multiplexer according to the currents flowing through the first branch and the second branch to adjust impedance of the first switch and the second switch to balance the currents flowing through the first branch and the second branch.

2. The current balance circuit of claim 1, wherein the first switch further comprises a first pole connected to the power supply unit and a second pole connected to the first resistor.

3. The current balance circuit of claim 2, wherein the first switch is a P channel metal oxide semiconductor field effect transistor (P-MOSFET), the control pole of the first switch is a gate of the P-MOSFET, the first pole of the first switch is a source of the P-MOSFET, and the second pole of the first switch is a drain of the P-MOSFET.

4. The current balance circuit of claim 1, wherein the second switch further comprises a first pole connected to the power supply unit and a second pole connected to the second resistor.

5. The current balance circuit of claim 4, wherein the second switch is a P channel metal oxide semiconductor field effect transistor (P-MOSFET), the control pole of the second switch is a gate of the P-MOSFET, the first pole of the second switch is a source of the P-MOSFET, and the second pole of the second switch is a drain of the P-MOSFET.

6. The current balance circuit of claim 1, wherein the current feedback and comparison circuit comprises:

a first amplifier, comprising a first input terminal, a second input terminal, and an output terminal, the first input terminal of the first amplifier connected to one end of the first resistor, and the second input terminal of the first amplifier connected to another end of the first resistor;

a second amplifier, comprising a first input terminal, a second input terminal, and an output terminal, the first input terminal of the second amplifier connected to one end of the second resistor, and the second input terminal of the second amplifier connected to another end of the second resistor; and

a first comparator, comprising an inverting input terminal, a non-inverting input terminal, and an output terminal, the non-inverting input terminal connected to the output terminal of the first amplifier, the inverting input terminal connected to the output terminal of the second amplifier, and the output terminal of the first comparator outputting comparison signals.

7. The current balance circuit of claim 6, wherein the gate signal control circuit comprises:

a second comparator, comprising an inverting input terminal, a non-inverting input terminal, and an output terminal, the non-inverting input terminal of the second comparator connected to the control pole of the first switch, and the inverting input terminal of the second comparator receiving the triangle waves;

a third comparator, comprising an inverting input terminal, a non-inverting input terminal, and an output terminal, the non-inverting input terminal of the third comparator connected to the control pole of the second switch, and the inverting input terminal of the third comparator receiving the reversed triangle waves;

an exclusive NOR gate, comprising a first input terminal, a second input terminal, and an output terminal, the first input terminal of the exclusive NOR gate connected to the output terminal of the first comparator, the second input terminal of the exclusive NOR gate connected to the output terminal of the second comparator, and the output terminal of the exclusive NOR gate connected to the control terminal of the first multiplexer; and

an exclusive OR gate, comprising a first input terminal, a second input terminal, and an output terminal, the first input terminal of the exclusive OR gate connected to the output terminal of the first comparator, the second input terminal of the exclusive OR gate connected to the output terminal of the third comparator, and the output terminal of the exclusive OR gate connected to the control terminal of the second multiplexer.

8. The current balance circuit of claim 1, wherein the gate signal control circuit controls the first multiplexer and the second multiplexer switch to the first input terminals when the currents flow through the first branch and the second branch are different and the triangle waves or the reversed triangle waves corresponding to the branch with the greater current is rising, and controls the first multiplexer and the second multiplexer switch to the second input terminals when the currents flow through the first branch and the second branch are different and the triangle waves or the reversed triangle waves corresponding to the branch with the greater current is dropping.