UPS electricity supply control circuit and UPS electricity supply

• US 9,570,930 B2
• Filed: 10/19/2011
• Issued: 02/14/2017
• Est. Priority Date: 10/22/2010
• Status: Expired due to Fees

• Current Assignee: Vertiv Tech Co., Ltd. (Vertiv Holdings Co.)
• Original Assignee: Emerson Network Power Company Limited (Emerson Electric Company)
• Inventors: Ni, Tong
• Primary Examiner(s): Kitov, Zeev V
• Application Number:
  US13/880,002
• Publication Number:
  US 20130200708A1
• Time in Patent Office: 1,945 Days
• US Class Current: 1/1
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02J 9/067 using multi-primary transformers, e.g. transformer having one primary for each AC energy source and a secondary for the loads
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/337 in push-pull configuration H02M3/33576 takes precedence; with self-oscillating arrangements H02M3/3382, H02M3/3385

Abstract

A UPS control circuit and a UPS is provided. The UPS includes a rechargeable battery and a UPS control circuit connected with the rechargeable battery. The UPS control circuit includes an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, a control circuit, and a multipurpose DC/DC circuit connected between the rechargeable battery and an output terminal of the rectification circuit. The multipurpose DC/DC circuit is controlled by the control circuit. In a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit. In a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit. Therefore, no independent charging circuit is needed to charge the rechargeable battery, causing a simpler circuit structure and a lower cost, and providing greater value to the customer.

Claims

1. An uninterruptable power supply (UPS) circuit connected with a rechargeable battery, the UPS circuit comprising an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit, wherein:

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit are connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises a battery/mains power selector switch and an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, and a first filter capacitor group;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

when the battery mode is selected by the battery/mains power selector switch,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted into a first AC voltage, which is applied to the primary side of the isolation transformer resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group, to supply an input voltage to the inversion circuit;

when the mains power mode is selected by the battery/mains power selector switch,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the first rectification circuit and the first filter capacitor group to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor and a second switching transistor;

each of the first switching transistor and the second switching transistor comprises a body diode;

the first rectification circuit is a half-wave rectification circuit formed by the body diode of the first switching transistor and the body diode of the second switching transistor;

the first filter capacitor group comprises a first capacitor;

the second switching transistor group comprises a third switching transistor and a fourth switching transistor;

the second rectification circuit is a bridge rectifier;

the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a center tap of the primary winding of the isolation transformer via the battery/mains power selector switch;

a cathode of the rechargeable battery is connected to (i) a dotted terminal of the primary winding of the isolation transformer via the first switching transistor, and (ii) a non-dotted terminal of the primary winding of the isolation transformer via the second switching transistor;

the first capacitor is connected between the center tap of the primary winding of the isolation transformer and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the third switching transistor and then the fourth switching transistor with an intersection of the third switching transistor and the fourth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is also connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.

2. The UPS control circuit according to claim 1, wherein:

the second switching transistor group further includes a fifth switching transistor and a sixth switching transistor; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal of the secondary winding of the isolation transformer.

3. An uninterruptable power supply (UPS) circuit connected with a rechargeable battery, the UPS circuit comprising an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit, wherein:

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit are connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, and a first filter capacitor group;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

in the battery mode,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted into a first AC voltage, which is applied to the primary side of the isolation transformer, resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group, to supply an input voltage to the inversion circuit;

in the mains power mode,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer, resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the first rectification circuit and the first filter capacitor group to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor;

each of the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor comprises a body diode;

the first rectification circuit is a full-wave rectification circuit formed by the body diode of the first switching transistor, the body diode of the second switching transistor, the body diode of the third switching transistor, and the body diode of the fourth switching transistor;

the first filter capacitor group comprises a first capacitor;

the second switching transistor group comprises a fifth switching transistor and a sixth switching transistor;

the second rectification circuit is a bridge rectifier;

the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a cathode of the rechargeable battery via the first switching transistor and the second switching transistor;

the anode of the rechargeable battery is also connected to the cathode of the rechargeable battery via the third switching transistor and the fourth switching transistor with (i) an intersection of the first switching transistor and the second switching transistor connected to a dotted terminal of the primary winding of the isolation transformer, and (ii) an intersection of the third switching transistor and the fourth switching transistor connected to a non-dotted terminal of the primary winding of the isolation transformer;

the first capacitor is connected between the anode and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.

4. The UPS circuit according to claim 3, wherein:

the second switching transistor group further includes a seventh switching transistor and an eighth switching transistor; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the seventh switching transistor and then the eighth switching transistor with an intersection of the seventh switching transistor and the eighth switching transistor connected to the non-dotted terminal of the secondary winding of the isolation transformer.

5. An uninterruptable power supply (UPS) circuit connected with a rechargeable battery, the UPS circuit comprising an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit, wherein:

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit are connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, a first filter capacitor group, and a resonant circuit;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

in the battery mode,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted via the resonant circuit into a first AC voltage, which is applied to the primary side of the isolation transformer resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group, to supply an input voltage to the inversion circuit; and

in the mains power mode,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the resonant circuit, the first rectification circuit, and the first filter capacitor group to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor;

the first filter capacitor group comprises a first capacitor;

the first rectification circuit comprises a charging capacitor and an induction coil;

the second switching transistor group comprises a fifth switching transistor and a sixth switching transistor;

the second rectification circuit is a bridge rectifier;

the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a cathode of the rechargeable battery via the first switching transistor and the second switching transistor;

the anode of the rechargeable battery is also connected to the cathode of the rechargeable battery via the third switching transistor and the fourth switching transistor with an intersection of the first switching transistor and the second switching transistor connected to a dotted terminal of the primary winding of the isolation transformer via the charging capacitor and then the induction coil;

an intersection of the third switching transistor and the fourth switching transistor is connected to a non-dotted terminal of the primary winding of the isolation transformer;

the first capacitor is connected between the anode and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.

6. An uninterruptable power supply (UPS) comprising a rechargeable battery and an UPS circuit connected with the rechargeable battery, wherein:

the UPS circuit comprises an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit;

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit are connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises a battery/mains power selector switch and an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, and a first filter capacitor group;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

when the battery mode is selected by the battery/mains power selector switch,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted into a first AC voltage, which is applied to the primary side of the isolation transformer resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group to supply an input voltage to the inversion circuit;

when the mains power mode is selected by the battery/mains power selector switch,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the first rectification circuit and the first filter capacitor group to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor and a second switching transistor;

each of the first switching transistor and the second switching transistor comprises a body diode;

the first rectification circuit is a half-wave rectification circuit formed by the body diode of the first switching transistor and the body diode of the second switching transistor;

the first filter capacitor group comprises a first capacitor;

the second switching transistor group comprises a third switching transistor and a fourth switching transistor;

the second rectification circuit is a bridge rectifier;

the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a center tap of the primary winding of the isolation transformer via the battery/mains power selector switch;

a cathode of the rechargeable battery is connected to (i) a dotted terminal of the primary winding of the isolation transformer via the first switching transistor, and (ii) a non-dotted terminal of the primary winding of the isolation transformer via the second switching transistor;

the first capacitor is connected between the center tap of the primary winding of the isolation transformer and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the third switching transistor and then the fourth switching transistor with an intersection of the third switching transistor and the fourth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is also connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.

7. The UPS according to claim 6, wherein:

the second switching transistor group further includes a fifth switching transistor and a sixth switching transistor; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal of the secondary winding of the isolation transformer.

8. An uninterruptable power supply (UPS) comprising a rechargeable battery and an UPS circuit connected with the rechargeable battery, wherein:

the UPS circuit comprises an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit;

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit being connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, and a first filter capacitor group;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

in the battery mode,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted into a first AC voltage, which is applied to the primary side of the isolation transformer resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group to supply an input voltage to the inversion circuit;

in the mains power mode,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the first rectification circuit and the first filter capacitor group, to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor;

each of the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor comprises a body diode;

the first rectification circuit is a full-wave rectification circuit formed by the body diode of the first switching transistor, the body diode of the second switching transistor, the body diode of the third switching transistor, and the body diode of the fourth switching transistor;

the first filter capacitor group comprises a first capacitor;

the second switching transistor group comprises a fifth switching transistor and a sixth switching transistor;

the second rectification circuit is a bridge rectifier, and the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a cathode of the rechargeable battery via the first switching transistor and the second switching transistor;

the anode of the rechargeable battery is also connected to the cathode of the rechargeable battery via the third switching transistor and the fourth switching transistor with (i) an intersection of the first switching transistor and the second switching transistor connected to a dotted terminal of the primary winding of the isolation transformer, and (ii) an intersection of the third switching transistor and the fourth switching transistor connected to a non-dotted terminal of the primary winding of the isolation transformer;

the first capacitor is connected between the anode and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.

9. The UPS according to claim 8, wherein:

the second switching transistor group further includes a seventh switching transistor and an eighth switching transistor; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the seventh switching transistor and then the eighth switching transistor with an intersection of the seventh switching transistor and the eighth switching transistor connected to the non-dotted terminal of the secondary winding of the isolation transformer.

10. An uninterruptable power supply (UPS) comprising a rechargeable battery and a UPS circuit connected with the rechargeable battery, wherein:

the UPS circuit comprises an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, and a control circuit;

the input filtering circuit, the rectification circuit, the inversion circuit, the static transfer switch, and the output filtering circuit are connected sequentially;

an output terminal of the input filtering circuit is connected with an input terminal of the static transfer switch;

the rectification circuit, the inversion circuit, and the static transfer switch are controlled by the control circuit;

the UPS circuit further comprises a multipurpose DC/DC circuit connected between an output terminal of the rectification circuit and the rechargeable battery;

the multipurpose DC/DC circuit is connected with and controlled by the control circuit, such that

in a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit, and

in a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit;

the multipurpose DC/DC circuit comprises an isolation transformer;

a primary side of the isolation transformer is provided with a first switching transistor group, a first rectification circuit, a first filter capacitor group, and a resonant circuit;

a secondary side of the isolation transformer is provided with a second switching transistor group, a second rectification circuit, and a second filter capacitor group;

in the battery mode,

the control circuit controls the first switching transistor group to be rapidly switched between on and off, such that an output voltage of the rechargeable battery is converted via the resonant circuit into a first AC voltage, which is applied to the primary side the isolation transformer resulting in a second AC voltage on the secondary side of the isolation transformer, and

at a same time, the control circuit controls the second switching transistor group to be turned off, such that the second AC voltage is converted into a DC voltage via the second rectification circuit and the second filter capacitor group to supply an input voltage to the inversion circuit;

in the mains power mode,

the control circuit controls the second switching transistor group to be rapidly switched between on and off, such that an output voltage of the rectification circuit is converted into a third AC voltage, which is applied to the secondary side of the isolation transformer resulting in a fourth AC voltage on the primary side of the isolation transformer, and

the fourth AC voltage is converted into a DC voltage via the resonant circuit, the first rectification circuit, and the first filter capacitor group to charge the rechargeable battery;

the first switching transistor group comprises a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor;

the first filter capacitor group comprises a first capacitor;

the first rectification circuit comprises a charging capacitor and an induction coil;

the second switching transistor group comprises a fifth switching transistor and a sixth switching transistor;

the second rectification circuit is a bridge rectifier;

the second filter capacitor group comprises a third capacitor and a fourth capacitor;

an anode of the rechargeable battery is connected to a cathode of the rechargeable battery via the first switching transistor and the second switching transistor;

the anode of the rechargeable battery is also connected to the cathode of the rechargeable battery via the third switching transistor and the fourth switching transistor with (i) an intersection of the first switching transistor and the second switching transistor connected to a dotted terminal of the primary winding of the isolation transformer via the charging capacitor and then the induction coil, and (ii) an intersection of the third switching transistor and the fourth switching transistor connected to a non-dotted terminal of the primary winding of the isolation transformer;

the first capacitor is connected between the anode and the cathode of the rechargeable battery;

a dotted terminal of the secondary winding of the isolation transformer is connected to a first input terminal of the bridge rectifier;

a non-dotted terminal of the secondary winding of the isolation transformer is connected to a second input terminal of the bridge rectifier;

a positive output terminal of the bridge rectifier is connected to a negative output terminal of the bridge rectifier via the fifth switching transistor and then the sixth switching transistor with an intersection of the fifth switching transistor and the sixth switching transistor connected to the non-dotted terminal or the dotted terminal of the secondary winding of the isolation transformer; and

the positive output terminal of the bridge rectifier is connected to the negative output terminal of the bridge rectifier via the third capacitor and then the fourth capacitor with an intersection of the third capacitor and the fourth capacitor connected to a center tap of the secondary winding of the isolation transformer.