US-12620904-B2 - Power conversion circuit

US12620904B2US 12620904 B2US12620904 B2US 12620904B2US-12620904-B2

Abstract

A power conversion circuit, includes the following elements. A first transformer, comprising a first winding coil and a second winding coil. A primary side circuit, connected to the first winding coil, the primary side circuit comprising a first power supply and a plurality of first switching units. A secondary side circuit, connected to the second winding coil, the secondary side circuit comprises a second power supply, a plurality of second switching units and a coupling circuit. When one of the first switching units and the second switching units generates a surge voltage, a surge energy associated with the surge voltage is guided to the second power supply through the coupling circuit.

Inventors

Guan-Lun CHEN

Assignees

LITE-ON TECHNOLOGY CORPORATION

Dates

Publication Date: 20260505
Application Date: 20231214
Priority Date: 20230307

Claims (15)

1 . A power conversion circuit, comprising: a first transformer, comprising a first winding coil and a second winding coil; a primary side circuit, connected to the first winding coil, the primary side circuit comprising a first power supply and a plurality of first switching units; and a secondary side circuit, connected to the second winding coil, the secondary side circuit comprises a second power supply, a plurality of second switching units and a coupling circuit, wherein the coupling circuit comprises a third winding coil, a fourth winding coil and a rectifying element, and the rectifying element is a diode having an anode connected to a ground end through the fourth winding coil and having a cathode connected to an output end of the second power supply, wherein when one of the first switching units and the second switching units generates a surge voltage, a surge energy associated with the surge voltage is guided to the second power supply through the coupling circuit.
2 . The power conversion circuit according to claim 1 , wherein the first switching units are connected to the first winding coil in a full-bridge configuration, and the first power supply is connected to the first winding coil through the first switching units.
3 . The power conversion circuit according to claim 1 , wherein the second switching units are connected to the second winding coil in a full-bridge configuration, and the second power supply is connected to the second winding coil through the second switching units.
4 . The power conversion circuit according to claim 1 , wherein the first winding coil and the second winding coil have a first turns ratio, and according to the value of the first turns ratio, the primary side circuit is associated with a low voltage side or a high voltage side, and the secondary side circuit is associated with the high voltage side or the low voltage side.
5 . The power conversion circuit according to claim 1 , wherein the primary side circuit further comprises a first capacitor, the first capacitor is connected to the first power supply in parallel, and the secondary side circuit further comprises a second capacitor, the second capacitor is connected to the second power supply in parallel.
6 . The power conversion circuit according to claim 1 , wherein the third winding coil and the fourth winding coil form a second transformer, and one of the second switching units is connected to the output end of the second power supply through the third winding coil.
7 . The power conversion circuit according to claim 6 , wherein the fourth winding coil is connected to the output end of the second power supply through the rectifying element, and the surge energy is guided to the output end of the second power supply.
8 . The power conversion circuit according to claim 1 , wherein the third winding coil and the fourth winding coil have a second turns ratio, and two ends of the third winding coil have a voltage difference, when a product of the voltage difference of the third winding coil and the second turns ratio meets a predefined condition, the rectifying element is turned on to guide the surge energy to the output end of the second power supply.
9 . The power conversion circuit according to claim 8 , wherein two ends of the fourth winding coil have a voltage difference, and a potential of the anode of the diode is equal to the voltage difference of the fourth winding coil, the voltage difference of the fourth winding coil is equal to a product of the voltage difference of the third winding coil and the second turns ratio.
10 . The power conversion circuit according to claim 9 , wherein the output end of the second power supply and the ground end have a voltage difference, when the potential of the anode of the diode is greater than a sum of a forward bias voltage and the voltage difference of the second power supply, the rectifying element is turned on to guide the surge energy to the output end of the second power supply.
11 . The power conversion circuit according to claim 10 , wherein a first value is equal to the sum of the forward bias voltage of the diode and the voltage difference of the second power source divided by the voltage difference of the third winding coil, and the first value is less than the second turns ratio.
12 . A power conversion circuit, comprising: a first transformer, comprising a first winding coil and a second winding coil; a primary side circuit, connected to the first winding coil, the primary side circuit comprising a first power supply and a plurality of first switching units; and a secondary side circuit, connected to the second winding coil, the secondary side circuit comprises a second power supply, a plurality of second switching units and a coupling circuit, wherein the coupling circuit comprises a third winding coil, a fourth winding coil and a rectifying element, and the rectifying element is a diode, an anode of the diode is connected to the fourth winding coil, and a cathode of the diode is connected to at an output end of the first power supply, wherein when one of the first switching units and the second switching units generates a surge voltage, a surge energy associated with the surge voltage is guided to the second power supply through the coupling circuit.
13 . A power conversion circuit, comprising: a first transformer, comprising a first winding coil and a second winding coil; a primary side circuit, connected to the first winding coil, the primary side circuit comprising a first power supply and a plurality of first switching units; and a secondary side circuit, connected to the second winding coil, the secondary side circuit comprises a second power supply, a plurality of second switching units and a coupling circuit, wherein the coupling circuit comprises a third winding coil, a fourth winding coil and a rectifying element, and the rectifying element is a third switching unit, a first end of the third switching unit is connected to the fourth winding coil, and a second end of the third switching unit is connected to the output end of the second power supply, wherein when one of the first switching units and the second switching units generates a surge voltage, a surge energy associated with the surge voltage is guided to the second power supply through the coupling circuit.
14 . The power conversion circuit according to claim 13 , wherein the third winding coil and the fourth winding coil have a second turns ratio, two ends of the third winding coil have a voltage difference, when a product of the voltage difference of the third winding coil and the second turns ratio meets a predefined condition, the rectifying element is turned on to guide the surge energy to the output end of the second power supply.
15 . The power conversion circuit according to claim 13 , wherein two ends of the fourth winding coil have a voltage difference, and a potential of the first end of the third switching unit is equal to the voltage difference of the fourth winding coil, and the voltage difference of the fourth winding coil is equal to a product of the voltage difference of the third winding coil and the second turns ratio.

Description

This application claims the benefit of Taiwan application Serial No. 112108262, filed Mar. 7, 2023, the disclosure of which is incorporated by reference herein in its entirety. TECHNICAL FIELD The disclosure relates to a conversion circuit, and in particular to a power conversion circuit BACKGROUND With the evolution of the technology of emerging energy sources, various energy storage systems have been widely used. For example, electric vehicles or battery cabinets both have energy storage systems. When the energy storage system performs reverse energy releasing to return power to the grid, the power conversion circuit in the energy storage system operates in a reverse boost mode. In the boost mode, when an abnormality occurs in the energy storage system and the operation must be stopped immediately, the switching elements in the power conversion circuit immediately stop and the switching elements are immediately disconnected. FIG. 1 is a circuit diagram of a power conversion circuit 2000 in the prior art. FIG. 1 only shows a secondary side circuit 2020 of the power conversion circuit 2000. The transformer 200 has a primary side winding coil P1 and a secondary side winding coil P2. The secondary side circuit 2020 is connected to the secondary side winding coil P2 of the transformer 200. The secondary side circuit 2020 comprises transistors Q1-Q4, a capacitor C2 and a second power supply 400. Transistors Q1-Q4 serve as switching elements. When an abnormality occurs in the energy storage system, the transistors Q1-Q4 are immediately disconnected, causing an instantaneous change in current, and the inductor L1 will generate a huge surge voltage. A surge energy associated with the surge voltage may damage transistors Q1-Q4. In order to reduce the surge energy associated with the surge voltage, the power conversion circuit 2000 in the prior art is further provided with a snubber circuit 600 to absorb the surge energy. The damping circuit 600 comprises a diode D01, a capacitor C01 and a resistor R01. When the snubber circuit 600 is operating, the diode D01 is turned on and absorbs the surge energy through the capacitor C01. However, since resistor R01 consumes power during normal operation, losses will occur. In response to the above-mentioned technical problems of the prior art, it is necessary to improve or replace the existing snubber circuit, so that the surge energy can be recovered and the loss can be reduced. SUMMARY According to one embodiment, the power conversion circuit includes the following elements. A first transformer, comprising a first winding coil and a second winding coil. A primary side circuit, connected to the first winding coil, the primary side circuit comprising a first power supply and a plurality of first switching units. A secondary side circuit, connected to the second winding coil, the secondary side circuit comprises a second power supply, a plurality of second switching units and a coupling circuit. When one of the first switching units and the second switching units generates a surge voltage, a surge energy associated with the surge voltage is guided to the second power supply through the coupling circuit. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a power conversion circuit 2000 in the prior art. FIG. 2A is a circuit diagram of a power conversion circuit 1000a according to an embodiment of the disclosure. FIG. 2B is a detailed circuit diagram of the coupling circuit 300a of FIG. 2A. FIG. 3A is a circuit diagram of a power conversion circuit 1000b according to another embodiment of the disclosure. FIG. 3B is a detailed circuit diagram of the coupling circuit 300b of FIG. 3A. FIG. 4 is a circuit diagram of a power conversion circuit 1000c according to yet another embodiment of the disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. DETAILED DESCRIPTION FIG. 2A is a circuit diagram of a power conversion circuit 1000a according to an embodiment of the disclosure. As shown in FIG. 2A, the power conversion circuit 1000a comprises a primary side circuit 1010, a secondary side circuit 1020 and a transformer 200. The primary side circuit 1010 is electrically isolated from the secondary side circuit 1020 through the transformer 200. The transformer 200 comprises a winding coil P1 and a winding coil P2. The winding coil P1 is disposed on the primary side of the transformer 200 and the winding coil P2 is disposed on the secondary side of the transformer 200. The winding coil P1 and the winding coil P2 have a turns ratio TNP_R. The turns ratio TNP_R is: the number of turns TNP2 of the winding coil P2 divided by the