Protection circuit with surge protection capability

Patent metadata

Field	Value
Publication number	US-9780641-B1
Application number	US-201615229609-A
Country	US
Kind code	B1
Filing date	Aug 5, 2016
Priority date	Jun 20, 2016
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A protection circuit includes a pre-charge rectifying circuit, a pre-charge resistor, a varistor, a switch, a main rectifying circuit, a bulk capacitor, and a control circuit. The pre-charge rectifying circuit is connected with an AC power source. The pre-charge resistor and the varistor are connected between the pre-charge rectifying circuit and the switch. The switch is further connected with a first node. The main rectifying circuit is connected between the AC power source and the first node. The bulk capacitor and the control circuit are connected between the first node and a ground terminal. The control circuit generates a first control signal to control the switch. The control circuit further generates a control signal set to control the main rectifying circuit.

First claim

What is claimed is:

1. A protection circuit, comprising:
a pre-charge rectifying circuit connected with an AC power source;
a pre-charge resistor, wherein a first terminal of the pre-charge resistor is connected with a DC output terminal of the pre-charge rectifying circuit;
a varistor, wherein a first terminal of the varistor is connected with the DC output terminal of the pre-charge rectifying circuit;
a switch having a first terminal connected with a second terminal of the pre-charge resistor, a second terminal connected with a second terminal of the varistor, and a third terminal connected with a first node, wherein when a first control signal received by the switch is inactivated, the first terminal of the switch is connected with the third terminal of the switch, wherein when the first control signal is activated, the second terminal of the switch is connected with the third terminal of the switch;
a main rectifying circuit connected with the AC power source, wherein a DC output terminal of the main rectifying circuit is connected with the first node;
a bulk capacitor connected between the first node and a ground terminal; and
a control circuit connected between the first node and the ground terminal, wherein the control circuit issues the first control signal to the switch, and the control circuit further issues a control signal set to the main rectifying circuit.

2. The protection circuit as claimed in claim 1 , wherein when the AC power source is just connected with the protection circuit, the first control signal and the control signal set are inactivated by the control circuit, and the pre-charge rectifying circuit provides a DC voltage to charge the bulk capacitor through the pre-charge resistor.

3. The protection circuit as claimed in claim 2 , where when the bulk capacitor is charged to a steady state voltage by the pre-charge rectifying circuit, the first control signal and the control signal set are activated by the control circuit, and the main rectifying circuit generates the steady state voltage to the bulk capacitor.

4. The protection circuit as claimed in claim 1 , wherein when the protection circuit generates a current in response to a surge voltage, a first portion of the current is transmitted to the bulk capacitor through the pre-charge rectifying circuit and the varistor, and a second portion of the current is transmitted to bulk capacitor through the main rectifying circuit.

5. The protection circuit as claimed in claim 1 , wherein the main rectifying circuit comprises:
a first diode, wherein an anode of the first diode is connected with the ground terminal, and a cathode of the first diode is connected with a second node;
a second diode, wherein an anode of the second diode is connected with the ground terminal, and a cathode of the second diode connected with a third node;
a third diode, wherein an anode of the third diode is connected with the ground terminal, and a cathode of the third diode is connected with a fourth node;
a first silicon controlled rectifier, wherein an anode of the first silicon controlled rectifier is connected with the second node, a cathode of the first silicon controlled rectifier is connected with the first node, and a gate control terminal of the first silicon controlled rectifier receives a second control signal of the control signal set;
a second silicon controlled rectifier, wherein an anode of the second silicon controlled rectifier is connected with the third node, a cathode of the second silicon controlled rectifier is connected with the first node, and a gate control terminal of the second silicon controlled rectifier receives a third control signal of the control signal set;
a third silicon controlled rectifier, wherein an anode of the third silicon controlled rectifier is connected with the fourth node, a cathode of the third silicon controlled rectifier is connected with the first node, and a gate control terminal of the third silicon controlled rectifier receives a fourth control signal of the control signal set,
wherein the second node, the third node and the fourth node are connected with the AC power source.

6. The protection circuit as claimed in claim 1 , wherein the protection circuit further comprises a driving circuit, and the driving circuit is connected between the first node and the ground terminal, wherein when the control circuit is enabled, the control circuit issues a driving signal set to the driving circuit.

Assignees

• Lite On Electronics Guangzhou Ltd
• Lite On Technology Corp

Inventors

• Chuang Ming-Cheng

Classifications

• H02M7/219

  in a bridge configuration · CPC title

• H02M7/06

  using discharge tubes without control electrode or semiconductor devices without control electrode · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M7/062 Primary

  Avoiding or suppressing excessive transient voltages or currents · CPC title

• H02M7/162

  in a bridge configuration · CPC title