TWI861718B - Resonant converter and resonant conversion circuitry - Google Patents

Abstract

A resonant converter includes a first conversion circuit, a resonant transformer circuit, a second conversion circuit and a switching circuit. The resonant transformer circuit is coupled to multiple first bridge arm units of the first conversion circuit, and is configured to convert a first voltage into a second voltage. The second conversion circuit is coupled to the resonant transformer circuit, and includes multiple second bridge arm units and multiple multi-level switching elements. The switching circuit is coupled to the second conversion circuit to selectively change connection positions of the second bridge arm units, so that the second conversion circuit converts the second voltage into a first DC(direct current) voltage by the second bridge arm units instead of by the multi-level switching elements, or the second conversion circuit converts the second voltage into a second DC(direct current) voltage by the second bridge arm units and multi-level switching elements.

Description

Resonant converter and resonant conversion circuit system

This disclosure relates to a technology for converting power, particularly a resonant converter and a resonant conversion circuit system.

In recent years, with the improvement of environmental awareness, electric vehicles using electricity as a power source have become more and more popular. Correspondingly, the importance and application demand of power conversion circuits have also increased. Therefore, how to improve the current power conversion circuit is one of the important topics in this field.

The present disclosure relates to a resonant converter, including a first conversion circuit, a resonant transformer circuit, a second conversion circuit and a switching circuit. The first conversion circuit includes a plurality of first bridge arm units and is used to output a first voltage. The resonant transformer circuit is coupled to the first bridge arm units and is used to convert the first voltage into a second voltage. The second conversion circuit is coupled to the resonant transformer circuit and includes a plurality of second bridge arm units and a plurality of multi-stage switch elements. The switching circuit is coupled to the second conversion circuit for selectively changing the connection positions of the second bridge arm units so that the second conversion circuit converts the second voltage into the first DC voltage through the second bridge arm units instead of the multi-level switch elements, or converts the second voltage into the second DC voltage through the second bridge arm units and the multi-level switch elements.

The present disclosure also relates to a resonant conversion circuit system, including a first resonant converter and a second resonant converter. The first resonant converter includes a first front-stage conversion circuit and a first resonant transformer circuit. The first front-stage conversion circuit is used to generate a first voltage according to a plurality of first front-stage control signals. The first resonant transformer circuit is coupled to the first front-stage conversion circuit to convert the first voltage into a second voltage. The second resonant converter includes a second front-stage conversion circuit and a second resonant transformer circuit. The second front-stage conversion circuit is used to generate a third voltage according to a plurality of second front-stage control signals. The second resonant transformer circuit is coupled to the second front-stage conversion circuit to convert the third voltage into a fourth voltage, and the second resonant transformer circuit is also coupled to the first resonant transformer circuit. The first front-stage control signals and the second front-stage control signals are interlaced with each other.

The present disclosure also relates to a resonant conversion circuit system, including a first resonant converter, a second resonant converter and a state selection circuit. The first resonant converter includes a first front-stage conversion circuit, a first resonant transformer circuit and a first rear-stage conversion circuit. The first front-stage conversion circuit includes a plurality of first front-stage bridge arm units and is used to output a first voltage. The first resonant transformer circuit is coupled to the first front-stage bridge arm units to convert the first voltage into a second voltage. The first rear-stage conversion circuit is coupled to the first resonant transformer circuit and includes a plurality of first rear-stage bridge arm units. The second resonant converter includes a second front-stage conversion circuit, a second resonant transformer circuit and a second rear-stage conversion circuit. The second front-stage conversion circuit includes a plurality of second front-stage bridge arm units and is used to output a third voltage. The second resonant transformer circuit is coupled to the second front-stage bridge arm units to convert the third voltage into a fourth voltage. The second rear-stage conversion circuit is coupled to the second resonant transformer circuit and includes a plurality of second rear-stage bridge arm units. The state selection circuit is coupled to the first resonant converter and the second resonant converter to selectively connect the first resonant converter and the second resonant converter in series or connect the first resonant converter and the second resonant converter in parallel.

The resonant converter disclosed in this disclosure can selectively change the connection position of the bridge arm unit by switching the circuit, so that the conversion circuit can have different circuit structures to meet different charging and discharging requirements.

100: Resonance converter

110: First conversion circuit

120: Resonant transformer circuit

121: First resonant groove

122: Three-phase transformer

123: Second resonance groove

130: Second conversion circuit

140: Switching circuit

150: Voltage divider circuit

160: Processor

210: Full bridge circuit

220: Three-phase three-level conversion circuit

C11: Input capacitor

C12: conversion capacitor

C13: voltage divider capacitor

C14: voltage divider capacitor

BF1-BF3: First bridge arm unit

BR1-BR3: Second bridge arm unit

TX1-TX6: Transistor switch

T1-T6: Bridge arm switch

TA: Multi-level switch components

TB: Multi-level switch components

W11: First short-circuit switch

W12: First short-circuit switch

W13: Second short-circuit switch

LD: Load

300: Resonance conversion circuit system

310: First resonant converter

311: First pre-conversion circuit

312: The first resonant transformer circuit

313: The first post-conversion circuit

320: Second resonant converter

321: Second pre-stage conversion circuit

322: Second resonant transformer circuit

323: Second stage conversion circuit

330: State selection circuit

W31: Series switch

W32: First parallel switch

W33: Second parallel switch

Np: Positive output terminal

Nn: Negative output terminal

WP11-WP13: Primary Winding

WP21-WP23: Primary Winding

WS11: First winding group

WS13: First winding group

WS15: First winding group

WS21: First winding group

WS23: First winding

WS25: First winding

WS12: Second winding group

WS14: Second winding group

WS16: Second winding group

WS22: Second winding group

WS24: Second winding group

WS26: Second winding

N1-N6: Nodes

Na: Node

Nb: Node

VP1: Inductive voltage

VP2: Inductive voltage

VTA: voltage

Vout: output voltage

FIG. 1 is a schematic diagram of a resonant converter according to some embodiments of the present disclosure.

Figure 2A is a schematic diagram of the operation of a resonant converter according to some embodiments of the present disclosure.

Figure 2B is a schematic diagram of the operation of a resonant converter according to some embodiments of the present disclosure.

FIG. 3 is a schematic diagram of a resonant conversion circuit system according to some embodiments of the present disclosure.

Figure 4 is a partial schematic diagram of a resonant conversion circuit system according to some embodiments of the present disclosure.

Figure 5 is a voltage signal diagram of a resonant conversion circuit system according to some embodiments of the present disclosure.

The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clarity, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. In other words, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some commonly used structures and components will be shown in the drawings in a simple schematic manner.

In this article, when an element is referred to as "connected" or "coupled", it may refer to "electrically connected" or "electrically coupled". "Connected" or "coupled" may also be used to indicate the coordinated operation or interaction between two or more elements. In addition, although the terms "first", "second", etc. are used in this article to describe different elements, the terms are only used to distinguish elements or operations described with the same technical terms. Unless the context clearly indicates otherwise, the terms do not specifically refer to or imply an order or sequence, nor are they used to limit the present invention.

As electric vehicles become more popular, the capacity and performance of energy storage units (such as removable batteries) installed in electric vehicles are also constantly improving. When the energy storage units of electric vehicles are not installed on the electric vehicles, these idle energy storage units can be used in other aspects, such as as power supply units to provide household electricity. Similarly, charging stations (charging stations used to charge electric vehicles, also known as electric vehicle supply equipment, EVSE) can also be used to supply power to various electronic devices.

Whether it is an electric vehicle's energy storage unit or charging station, it is equipped with a power converter with bidirectional charging and discharging functions. From the development trend of the power system, the application requirements of power converters are high power and high output voltage. Therefore, the semiconductor switch in the power converter needs to have a higher voltage stress (withstand voltage), but it will lead to increased costs.

FIG. 1 is a schematic diagram of a resonant converter 100 according to some embodiments of the present disclosure. The resonant converter 100 includes a first conversion circuit 110, a resonant transformer circuit 120, a second conversion circuit 130, and a switching circuit 140. In one embodiment, the resonant converter 100 can be applied to an energy storage unit or a charging pile of an electric vehicle, but the present disclosure is not limited thereto and can also be applied to power converters for any purpose.

The first conversion circuit 110 includes a plurality of first bridge arm units BF1, BF2, and BF3. Each of the first bridge arm units BF1, BF2, and BF3 includes at least two transistor switches (such as TX1 to TX6 shown in the figure), and there is an output node between two transistor switches (such as TX1 and TX2, TX3 and TX4, TX5 and TX6) in the same first bridge arm unit BF1, BF2, and BF3. In some embodiments, the first conversion circuit 110 can receive input voltage through a power factor correction circuit (not shown in the figure) and an input capacitor C11.

In some embodiments, the resonant converter 100 further includes a processor 160. The processor 160 is used to provide a plurality of control signals to a plurality of transistor switches TX1 to TX6 in a plurality of first bridge units BF1, BF2, and BF3, respectively, so that the plurality of transistor switches TX1 to TX6 are turned on or off according to the corresponding control signals, and then the first voltage is output through the output nodes.

As shown in FIG. 1 , the first conversion circuit 110 receives a DC input voltage through the input capacitor C11 of the resonant converter 100, and then converts the input voltage into an AC first voltage through a plurality of bridge arm units BF1, BF2, and BF3. In some embodiments, the first conversion circuit 110 may be a full-bridge conversion circuit. Since those skilled in the art understand the operation of a full-bridge circuit, it will not be further described here.

The resonant transformer circuit 120 includes a first resonant tank 121, a three-phase transformer 122, and a second resonant tank 123. The first resonant tank 121 has a resonant circuit formed by multiple sets of capacitors and inductors connected in series, which are respectively coupled to the three output nodes of the first conversion circuit 110 to resonate the received first voltage. The three-phase transformer 122 is coupled to the first resonant tank 121 to convert the first voltage into a second voltage (such as step-up or step-down). The second resonant tank 123 is coupled to the three-phase transformer 122 and includes a resonant circuit formed by multiple sets of capacitors and inductors connected in series to resonate the received second voltage.

The second conversion circuit 130 is coupled to the resonant transformer circuit 120 and includes a plurality of second bridge units BR1, BR2, BR3, a plurality of multi-level switch elements TA, TB and a conversion capacitor C12. The plurality of second bridge units BR1, BR2, BR3 include a plurality of bridge switches T1~T6. In some embodiments, the processor 160 provides a plurality of control signals for the plurality of bridge switches T1~T6 and the plurality of multi-level switch elements TA, TB in the plurality of second bridge units BR1, BR2, BR3, respectively, so that the plurality of bridge switches T1~T6 and the plurality of multi-level switch elements TA, TB are turned on or off according to the corresponding control signals.

The switching circuit 140 is coupled to the second conversion circuit 130 to selectively change the connection positions of the second bridge arm units BR1, BR2, and BR3 (e.g., by controlling the on or off of multiple switches). As shown in FIG. 1, the switching circuit 140 can make the two ends of the second bridge arm units BR1, BR2, and BR3 conduct to a plurality of multi-level switch elements TA and TB, or the switching circuit 140 can form a short circuit path between the two ends of the second bridge arm units BR1, BR2, and BR3 and the output end of the resonant converter 100. Accordingly, the second conversion circuit 130 can be switched to different circuit architectures for operation.

As mentioned above, when the switching circuit 140 short-circuits the two ends of the second bridge arm units BR1, BR2, and BR3 to the output end of the resonant converter 100, the second conversion circuit 130 can convert the second voltage into the first DC voltage through the plurality of second bridge arm units BR1, BR2, and BR3, but not through the plurality of multi-level switching elements TA and TB. In other words, at this time, the plurality of multi-level switching elements TA and TB will not cooperate with the plurality of second bridge arm units BR1, BR2, and BR3 to operate.

On the other hand, when the switching circuit 140 connects the two ends of the plurality of second bridge units BR1, BR2, BR3 to the plurality of multi-level switch elements TA, TB, the second conversion circuit 130 converts the second voltage into a second DC voltage greater than the first DC voltage through the plurality of second bridge units BR1, BR2, BR3 and the plurality of multi-level switch elements TA, TB.

In one embodiment, the resonant converter 100 further includes a voltage divider circuit 150. The voltage divider circuit 150 is coupled to the second conversion circuit 130 and includes a plurality of voltage divider capacitors C13 and C14 for providing the first DC voltage or the second DC voltage generated by the second conversion circuit 130 to the load LD. In addition, the conversion capacitor C12 may be a flying capacitor for balancing the voltages of the voltage divider capacitors C13 and C14.

Figures 2A and 2B are schematic diagrams of the operation mode of the resonant converter 100 according to some embodiments of the present disclosure. In one embodiment, the switching circuit 140 includes a plurality of first short-circuit switches W11, W12. The plurality of first short-circuit switches W11, W12 are selectively turned on or off according to the control signal provided by the processor 160. One end of the first short-circuit switch W11 is coupled to the positive output end of the resonant converter 100 (or one end of the voltage divider circuit 150). The other end of the first short-circuit switch W11 is coupled to one end of the second bridge arm units BR1, BR2, BR3. One end of the first short-circuit switch W12 is coupled to the other end of the plurality of second bridge arm units BR1, BR2, BR3. The other end of the first short-circuit switch W12 is coupled to the negative output end of the resonant converter 100 (or the other end of the voltage divider circuit 150). When the multiple first short-circuit switches W11 and W12 are turned on, a short-circuit path is formed, so the voltage or current will not flow through the multi-stage switch elements TA and TB.

As shown in FIG. 2A, in one embodiment, when the two ends of the plurality of second bridge arm units BR1, BR2, and BR3 are coupled to the output end of the resonant converter through the short-circuit path formed by the switching circuit 140 (the plurality of first short-circuit switches W11 and W12 are turned on, but the second short-circuit switch W13 is turned off), the plurality of second bridge arm units BR1, BR2, and BR3 are used as a full-bridge circuit 210 to convert the second voltage into the first DC voltage. At this time, the cross-voltage borne by each bridge arm switch T1 to T6 in the second conversion circuit 130 is equal to the voltage (first DC voltage) output by the second conversion circuit 130.

In one embodiment, the switching circuit 140 further includes a second short-circuit switch W13. The second short-circuit switch W13 is selectively turned on or off according to a control signal provided by the processor 160. One end of the second short-circuit switch W13 is coupled between the bridge switches (e.g., bridge switches T5, T6) of one of the second bridge units BR1, BR2, BR3. The other end of the second short-circuit switch W13 is coupled to a node between a plurality of voltage-dividing capacitors C13, C14.

As shown in FIG. 2B , in some embodiments, when the two ends of the plurality of second bridge units BR1, BR2, BR3 are coupled to the output end of the resonant converter through a plurality of multi-level switch elements TA, TB (i.e., the plurality of first short-circuit switches W11, W12 are turned off, but the second short-circuit switch W13 is turned on), the plurality of second bridge units BR1, BR2, BR3 and the multi-level switch elements TA, TB are used as a three-phase three-level conversion circuit 220 to convert the second voltage into a second DC voltage.

As shown in FIG. 2B, when the second conversion circuit 130 operates as a three-phase three-level conversion circuit, the second DC voltage outputted by the second conversion circuit 130 will be higher than the first DC voltage (e.g., twice the first DC voltage). In addition, since the two ends of the plurality of second bridge units BR1, BR2, and BR3 are coupled to the plurality of multi-level switch elements TA and TB for coordinated operation, and the middle node of at least one second bridge unit (e.g., BR3) is coupled between the plurality of voltage divider capacitors C13 and C14, when the second conversion circuit 130 converts the voltage, the cross-voltage that each bridge switch T1 to T6 and the plurality of multi-level switch elements TA and TB need to withstand will be smaller (e.g., the cross-voltage is half of that of the full bridge circuit).

In the aforementioned embodiment, the resonant converter 100 receives an input voltage through the first conversion circuit 110 and generates an output voltage through the second conversion circuit 130. However, in other embodiments, the resonant converter 100 may also receive an input voltage through the second conversion circuit 130 and generate an output voltage through the first conversion circuit 110. In other words, the resonant converter 100 is a bidirectional resonant circuit whose input/output terminals can be swapped according to requirements.

The present disclosure selectively changes the connection positions of the two ends of the plurality of second bridge arm units BR1, BR2, and BR3 through the switching circuit 140, so that the two ends of the plurality of second bridge arm units BR1, BR2, and BR3 are coupled to the output end of the resonant converter 100 through the short-circuit path formed by the switching circuit 140, or the two ends of the plurality of second bridge arm units BR1, BR2, and BR3 are coupled to the output end of the resonant converter 100 through a plurality of multi-level switch elements TA and TB. Accordingly, different charging and discharging requirements can be flexibly responded to. For example, when the second conversion circuit 130 is applied to a load with a relatively large working voltage, the switching circuit 140 can adjust the second conversion circuit 130 to a three-phase three-level conversion circuit 220 to receive/output a relatively large voltage, and can reduce the cross-voltage that each transistor element in the second conversion circuit 130 needs to withstand. In contrast, if the second conversion circuit 130 is applied to a load with a general working voltage, the switching circuit 140 can adjust the second conversion circuit 130 to a full-bridge circuit 210 to receive/output a general voltage, and can save power consumption.

Generally speaking, the disadvantages of three-phase three-level conversion circuits are "large number of power components" and "large size", so it is difficult to design a high-density circuit. The present disclosure uses a switching circuit 140 to match multiple multi-level switch components TA and TB on the full-bridge circuit architecture. Based on this, not only can the circuit structure be simplified, but the second conversion circuit 130 can also have different circuit structures, so that it can be switched at any time according to usage requirements, for example: to achieve a wide voltage output range and a wide load range.

In the embodiment shown in FIG. 1 , each switch (e.g., a plurality of transistor switches TX1 to TX6 of a plurality of first bridge units BF1 to BF3, each bridge switch T1 to T6 of a plurality of second bridge units BR1 to BR3, a plurality of multi-level switch elements TA to TB, and a plurality of short-circuit switches W11 to W13) is controlled by a processor 160. In other words, the processor 160 is coupled to the first conversion circuit 110, the second conversion circuit 130, and the switching circuit 140. Those skilled in the art should understand that the first conversion circuit 110 and the second conversion circuit 130 are electrically isolated by the resonant transformer circuit 120, so the different control signals provided by the processor 160 to the first conversion circuit 110, the second conversion circuit 130 and the switching circuit 140 need to be isolated accordingly, which will not be elaborated here.

In addition, in one embodiment, the processor 160 can also be connected to the load LD to detect the electrode voltage of the load LD. The electrode voltage of the load LD will reflect the power supply capacity or charging requirement of the load LD, so the processor 160 can generate a detection signal by detecting the load LD, and control the switching circuit 140 according to the detection signal to change the connection position of the two ends of the plurality of second bridge arm units BR1~BR3.

FIG. 3 is a schematic diagram of a resonant converter circuit system 300 according to some embodiments of the present disclosure. The resonant converter circuit system 300 includes a first resonant converter 310 and a second resonant converter 320.

The first resonant converter 310 includes a first front-stage conversion circuit 311, a first resonant transformer circuit 312, and a first rear-stage conversion circuit 313. In this embodiment, the structure of the first resonant converter 310 may be the same as the resonant converter 100 shown in FIG. 1. That is, the first front-stage conversion circuit 311 may be the first conversion circuit 110 shown in FIG. 1, and includes a plurality of first front-stage bridge arm units, such as the plurality of first bridge arm units BF1 to BF3 shown in FIG. 1. The first resonant transformer circuit 312 is the resonant transformer circuit 120 shown in FIG. 1. The first post-stage conversion circuit 313 may be the second conversion circuit 130 shown in FIG. 1, and includes a plurality of first post-stage bridge arm units, such as a plurality of second bridge arm units BR1 to BR3 shown in FIG. 1.

Similarly, the structure of the second resonant converter 320 may be the same as the resonant converter 100 shown in FIG. 1. That is, the second front-stage conversion circuit 321 may be the first conversion circuit 110 shown in FIG. 1, and include a plurality of second front-stage bridge arm units, such as the plurality of first bridge arm units BF1 to BF3 shown in FIG. 1. The second resonant transformer circuit 322 is the resonant transformer circuit 120 shown in FIG. 1. The second rear-stage conversion circuit 323 may be the second conversion circuit 130 shown in FIG. 1, and include a plurality of second rear-stage bridge arm units, such as the plurality of second bridge arm units BR1 to BR3 shown in FIG. 1.

In some embodiments, the resonant conversion circuit system 300 further includes a processor (not shown in FIG. 3 ), which is used to provide a control signal to control multiple switch elements in the first resonant converter 310 and the second resonant converter 320 respectively. Specifically, the first front-stage conversion circuit 311 is used to generate a first voltage according to multiple first front-stage control signals, and the first resonant transformer circuit 312 then converts the first voltage into a second voltage. The second front-stage conversion circuit 321 is used to generate a third voltage according to multiple second front-stage control signals, and the second resonant transformer circuit 322 then converts the third voltage into a fourth voltage.

In some embodiments, the first resonant transformer circuit 312 and the second resonant transformer circuit 322 are coupled to each other, for example: a first portion of the plurality of secondary windings in the first resonant transformer circuit 312 are coupled to each other, a first portion of the plurality of secondary windings in the second resonant transformer circuit 322 are also coupled to each other, and a second portion of the plurality of secondary windings in the first resonant transformer circuit 312 is coupled to a second portion of the plurality of secondary windings in the second resonant transformer circuit 322.

Continuing from the above, in the embodiment where the first resonant transformer circuit 312 and the second resonant transformer circuit 322 are coupled to each other, the first front-stage control signal and the second front-stage control signal are interleaved. That is, the same transistor switch (such as TX1 shown in Figure 1) at the corresponding position in the first front-stage conversion circuit 311 and the second front-stage conversion circuit 321 will be controlled in opposite states (i.e., one is turned on and the other is turned off).

Similarly, the first post-stage conversion circuit 313 converts the second voltage into a DC voltage according to a plurality of first post-stage control signals. The second post-stage conversion circuit 323 converts the fourth voltage into a DC voltage according to a plurality of second post-stage control signals. The first post-stage control signal and the second post-stage control signal are interlaced with each other, so that the first resonant converter 310 and the second resonant converter 320 can work in coordination with each other.

FIG. 4 is a schematic diagram of a first resonant transformer circuit 312 and a second resonant transformer circuit 322 according to some embodiments of the present disclosure. The first resonant transformer circuit 312 includes a plurality of primary windings WP11, WP12, WP13 and a plurality of secondary windings, and each secondary winding includes a first sub-winding (such as WS11, WS13, WS15 as shown in the figure) and a second sub-winding (such as WS12, WS14, WS16 as shown in the figure). Similarly, the second resonant transformer circuit 322 includes a plurality of primary windings WP21, WP22, WP23 and a plurality of secondary windings, and each secondary winding includes a first sub-winding (such as WS21, WS23, WS25 shown in the figure) and a second sub-winding (such as WS22, WS24, WS26 shown in the figure).

The first parts of the multiple secondary windings in the first resonant transformer circuit 312 are coupled to each other; the first parts of the multiple secondary windings in the second resonant transformer circuit 322 are also coupled to each other; and the second parts of the multiple secondary windings of the first resonant transformer circuit 312 and the second resonant transformer circuit 322 are coupled to each other. Accordingly, the voltages on the first resonant transformer circuit 312 and the second resonant transformer circuit 322 can be superimposed on each other due to interleaving, so that the voltage output by the first resonant transformer circuit 312 and the second resonant transformer circuit 322 is higher.

As shown in FIG. 4, specifically, the same corresponding ends (such as negative poles, opposite poles, and non-pointing ends) of the multiple primary windings WP11 to WP13 of the first resonant transformer circuit 312 are coupled to each other. Similarly, the same corresponding ends (such as positive poles, opposite poles, and pointing ends) of the multiple primary windings WP21 to WP23 of the second resonant transformer circuit 322 are coupled to each other.

In FIG. 4 , the positions of the same nodes N1-N6 represent mutual coupling. In some embodiments, one end (e.g., positive electrode) of the plurality of first sub-windings WS11/WS13/WS15 of the first resonant transformer circuit 312 is coupled to the first post-stage conversion circuit 313 through the resonant slot. The other end (e.g., negative electrode) of the plurality of first sub-windings WS11/WS13/WS15 of the first resonant transformer circuit 312 is respectively coupled to one of the secondary windings of the second resonant transformer circuit 322, and the coupling positions are staggered (i.e., the positive electrode is coupled to the negative electrode). For example: the first sub-winding WS11 is coupled to the first sub-winding WS21 through the node N1, the first sub-winding WS13 is coupled to the first sub-winding WS23 through the node N3, and the first sub-winding WS15 is coupled to the first sub-winding WS25 through the node N5.

In some embodiments, one end (e.g., positive pole) of the plurality of second sub-windings WS12/WS14/WS16 of the first resonant transformer circuit 312 is coupled to each other. The other end (e.g., negative pole) of the plurality of second sub-windings WS12/WS14/WS16 of the first resonant transformer circuit 312 is connected to another secondary winding of the second resonant transformer circuit 322, and the coupling positions are staggered (i.e., the positive pole is coupled to the negative pole). For example, the second sub-winding WS12 is coupled to the second sub-winding WS22 through the node N2, the second sub-winding WS14 is coupled to the second sub-winding WS24 through the node N4, and the second sub-winding WS16 is coupled to the second sub-winding WS26 through the node N6.

FIG. 5 is a schematic diagram of a voltage signal of a resonant conversion circuit system according to some embodiments of the present disclosure. In FIG. 5, it is assumed that the coil ratio of the primary winding to the secondary winding in the first resonant transformer circuit 312 and the second resonant transformer circuit 322 is 1:1. The voltage waveform of FIG. 5 includes an induced voltage VP1 on the primary winding WP11, an induced voltage VP2 on the primary winding WP21, and a voltage VTA is an induced voltage on the node N1 and the node N2. In addition, since the first resonant transformer circuit 312 and the second resonant transformer circuit 322 are interleaved, the output voltage Vout of the secondary winding in the first resonant transformer circuit 312 can be equal to the voltage difference between the nodes Na and Nb. Since the multiple induced voltages VP1 and VP2 are interleaved, and the secondary windings of the first resonant transformer circuit 312 and the second resonant transformer circuit 322 are coupled to each other through the nodes N1 and N2, the output voltage Vout will be "the sum of the induced voltages of the first resonant transformer circuit 312 and the second resonant transformer circuit 322 at the node N1".

As shown in FIG. 3, in some embodiments, the resonant conversion circuit system 300 further includes a state selection circuit 330. The state selection circuit 330 is coupled to the first resonant converter 310 and the second resonant converter 320, respectively, to selectively connect the first resonant converter 310 and the second resonant converter 320 in series, or connect the first resonant converter 310 and the second resonant converter 320 in parallel (e.g., by controlling the on or off of multiple switches).

In some embodiments, the state selection circuit 330 includes a series switch W31. The series switch W31 is coupled between the first resonant converter 310 and the second resonant converter 320. The first post-stage conversion circuit 313 is coupled to the positive output terminal Np of the resonant conversion circuit system 300 and the first end of the series switch W31. The second post-stage conversion circuit 323 is coupled to the negative output terminal Nn of the resonant conversion circuit system 300 and the second end of the series switch W31.

In some embodiments, the state selection circuit 330 includes a first parallel switch W32 and a second parallel switch W33. The first parallel switch W32 is coupled between the first end of the series switch W31 and the negative output terminal Nn. The second parallel switch W33 is coupled between the second end of the series switch W31 and the positive output terminal Np.

Accordingly, when the series switch W31 is turned on, but the plurality of parallel switches W32 and W33 are turned off, the first resonant converter 310 and the second resonant converter 320 are connected in series (referred to as "series mode"). Conversely, when the series switch W31 is turned off, but the plurality of parallel switches W32 and W33 are turned on, the first resonant converter 310 and the second resonant converter 320 are connected in parallel (referred to as "parallel mode"). In the series mode, the resonant conversion circuit system 300 can provide a larger voltage; in the parallel mode, the resonant conversion circuit system 300 can provide a larger current. Through the control of the state selection circuit 330, the resonant conversion circuit system 300 can be charged and discharged in different modes according to application requirements and load conditions.

In the embodiment shown in FIG. 3, the first resonant converter 310 and/or the second resonant converter 320 may also have a switching circuit 140 as shown in FIG. 1. That is, the switching circuit of the first resonant converter 310 may be coupled to the first rear-stage conversion circuit 313 to selectively change the connection position of the first rear-stage bridge arm unit. Accordingly, the first rear-stage conversion circuit 313 may convert the second voltage into the first DC voltage through the first rear-stage bridge arm unit but not through the first multi-level switch element (such as the plurality of multi-level switch elements TA, TB shown in FIG. 1). Alternatively, the first rear-stage conversion circuit 313 may convert the second voltage into the second DC voltage through the first rear-stage bridge arm unit and the first multi-level switch element.

In the aforementioned embodiment, the resonant converter circuit system 300 receives the input voltage through the first front-stage converter circuit 311 and the second front-stage converter circuit 321, but in other embodiments, the resonant converter 100 can also receive the input voltage through the first rear-stage converter circuit 313 and the second rear-stage converter circuit 323. In other words, the resonant converter circuit system 300 is a bidirectional resonant circuit system, and its input/output terminals can be swapped according to needs.

The above-mentioned embodiments of the present disclosure are based on the resonant converter 100 shown in FIG. 1 and are matched with the switching circuit 140; or the resonant transformer circuits of multiple resonant converters 310 and 320 are coupled; or multiple resonant converters 310 and 320 are matched with the state selection circuit 330. The above three application methods are combined with each other, but the characteristics of each other can be applied independently of each other. For example, the resonant converter can couple the resonant transformer circuits of multiple resonant converters, but there is no need to configure the state selection circuit. Similarly, multiple resonant converters can switch between series or parallel modes through the state selection circuit, but there is no need to couple the multiple resonant transformer circuits.

The various elements, method steps or technical features in the aforementioned embodiments can be combined with each other and are not limited to the order of text description or diagram presentation in this disclosure.

Although the contents of this disclosure have been disclosed in the form of implementation as above, it is not intended to limit the contents of this disclosure. Anyone familiar with this art can make various changes and modifications without departing from the spirit and scope of the contents of this disclosure. Therefore, the scope of protection of the contents of this disclosure shall be subject to the scope of the patent application attached hereto.

100: Resonance converter

110: First conversion circuit

120: Resonant transformer circuit

121: First resonant groove

122: Three-phase transformer

123: Second resonance groove

130: Second conversion circuit

140: Switching circuit

150: Voltage divider circuit

160: Processor

C11: Input capacitor

C12: conversion capacitor

C13: voltage divider capacitor

C14: voltage divider capacitor

BF1-BF3: First bridge arm unit

BR1-BR3: Second bridge arm unit

TX1-TX6: Transistor switch

T1-T6: Bridge arm switch

TA: Multi-level switch components

TB: Multi-level switch components

W11: First short-circuit switch

W12: First short-circuit switch

W13: Second short-circuit switch

LD: Load

Claims (20)

A resonant converter comprises: a first conversion circuit, comprising a plurality of first bridge arm units, and used to output a first voltage; a resonant transformer circuit, coupled to the first bridge arm units, and used to convert the first voltage into a second voltage; a second conversion circuit, coupled to the resonant transformer circuit, and comprising a plurality of second bridge arm units and a plurality of multi-stage switch elements; and a first switching circuit, Coupled to the second conversion circuit, for selectively changing the connection position of the second bridge arm units, so that the second conversion circuit converts the second voltage into a first DC voltage through the second bridge arm units instead of the multi-level switch elements, or converts the second voltage into a second DC voltage through the second bridge arm units and the multi-level switch elements. A resonant converter as described in claim 1, wherein the switching circuit comprises a plurality of first short-circuit switches and a second short-circuit switch, the first short-circuit switches are coupled to the two ends of the second bridge arm units, and the second short-circuit switch is coupled between a plurality of bridge arm switches of at least one of the second bridge arm units. The resonant converter as described in claim 2 further comprises: a voltage divider circuit coupled to the second conversion circuit and comprising a plurality of voltage divider capacitors; wherein the first short-circuit switches are respectively coupled to the two ends of the voltage divider circuit, and the second short-circuit switch is coupled to the voltage divider capacitors. A resonant converter as described in claim 1, wherein the switching circuit is used to selectively change the connection position of the second bridge arm units so that the two ends of the second bridge arm units are coupled to an output end of the resonant converter through a short circuit path formed by the switching circuit, or the two ends of the second bridge arm units are coupled to the output end of the resonant converter through the multi-level switch elements. As described in claim 4, when the two ends of the second bridge arm units are coupled to the output end of the resonant converter through the multi-level switching elements, the second bridge arm units and the multi-level switching elements are used as a three-phase three-level conversion circuit. As described in claim 5, the resonant converter, wherein the two ends of the second bridge arm units are coupled to the output end of the resonant converter through the short-circuit path formed by the switching circuit, and the second bridge arm units are used as a full-bridge circuit. The resonant converter as described in claim 1 further comprises: a processor coupled to the switching circuit and used to detect an electrode voltage of a load to generate a detection signal, wherein the processor is used to control the switching circuit according to the detection signal to change the connection position of the second bridge arm units. A resonant conversion circuit system includes: a first resonant converter including a first front-stage conversion circuit and a first resonant transformer circuit, wherein the first front-stage conversion circuit is used to generate a first voltage according to a plurality of first front-stage control signals; wherein the first resonant transformer circuit is coupled to the first front-stage conversion circuit to convert the first voltage into a second voltage; and a second resonant converter including a second front-stage conversion circuit. A first resonant transformer circuit and a second resonant transformer circuit, wherein the second front stage conversion circuit is used to generate a third voltage according to a plurality of second front stage control signals; wherein the second resonant transformer circuit is coupled to the second front stage conversion circuit to convert the third voltage into a fourth voltage, and the second resonant transformer circuit is also coupled to the first resonant transformer circuit; wherein the first front stage control signals and the second front stage control signals are interlaced with each other. A resonant converter circuit system as described in claim 8, wherein the first resonant converter further comprises a first post-stage conversion circuit, the first post-stage conversion circuit is coupled to the first resonant transformer circuit, and converts the second voltage according to a plurality of first post-stage control signals; the second resonant converter further comprises a second post-stage conversion circuit, the second post-stage conversion circuit is coupled to the second resonant transformer circuit, and converts the fourth voltage according to a plurality of second post-stage control signals; wherein the first post-stage control signals and the second post-stage control signals are interlaced with each other. A resonant conversion circuit system as described in claim 9, wherein the first resonant transformer circuit includes a plurality of first primary windings and a plurality of first secondary windings, and the second resonant transformer circuit includes a plurality of second primary windings and a plurality of second secondary windings; wherein a first portion of the first secondary windings is coupled to each other, a first portion of the second secondary windings is coupled to each other, and a second portion of the first secondary windings is coupled to a second portion of the second secondary windings. A resonant conversion circuit system as described in claim 10, wherein one of the first secondary windings further comprises a first sub-winding, one end of the first sub-winding is coupled to the first post-stage conversion circuit, and the other end of the first sub-winding is coupled to one of the second secondary windings. A resonant conversion circuit system as described in claim 11, wherein one of the first secondary windings further comprises a plurality of second sub-windings, one end of the second sub-windings are coupled to each other, and the other end of the second sub-windings are coupled to the other of the second secondary windings. A resonant converter circuit system as described in claim 10, wherein one end of the first primary windings are coupled to each other. A resonant conversion circuit system includes: a first resonant converter, including: a first front-stage conversion circuit, including a plurality of first front-stage bridge arm units, and used to output a first voltage; a first resonant transformer circuit, coupled to the first front-stage bridge arm units, and used to convert the first voltage into a second voltage; and a first rear-stage conversion circuit, coupled to the first resonant transformer circuit, and including a plurality of first rear-stage bridge arm units; a second resonant converter, including: a second front-stage conversion circuit, including a plurality of second front-stage bridge arm units; A first resonant converter and a second resonant converter are provided for outputting a third voltage; a second resonant converter circuit is coupled to the second front-stage bridge arm units and is used to convert the third voltage into a fourth voltage; a second rear-stage converter circuit is coupled to the second resonant converter circuit and includes a plurality of second rear-stage bridge arm units; and a state selection circuit is coupled to the first resonant converter and the second resonant converter and is used to selectively connect the first resonant converter and the second resonant converter in series or connect the first resonant converter and the second resonant converter in parallel. A resonant conversion circuit system as described in claim 14, wherein the resonant conversion circuit system includes a positive output terminal and a negative output terminal, and the state selection circuit includes: a series switch, wherein the first post-stage conversion circuit is coupled to the positive output terminal and a first terminal of the series switch, and the second post-stage conversion circuit is coupled to the negative output terminal and a second terminal of the series switch. The resonant conversion circuit system as described in claim 15, wherein the state selection circuit further comprises: a first parallel switch coupled between the first end of the series switch and the negative output end; and a second parallel switch coupled between the second end of the series switch and the positive output end. The resonant conversion circuit system as described in claim 14, wherein the first rear-stage conversion circuit further includes a plurality of first multi-level switch elements, and the first resonant converter further includes: a switching circuit coupled to the first rear-stage conversion circuit for selectively changing the connection positions of the first rear-stage bridge arm units so that the first rear-stage conversion circuit converts the second voltage into a first direct current voltage through the first rear-stage bridge arm units but not through the first multi-level switch elements, or converts the second voltage into a second direct current voltage through the first rear-stage bridge arm units and the first multi-level switch elements. A resonant conversion circuit system as described in claim 17, wherein the switching circuit includes a plurality of first short-circuit switches and a second short-circuit switch, the first short-circuit switches are coupled to the two ends of the first rear-stage bridge arm units, and the second short-circuit switch is coupled between a plurality of bridge arm switches of at least one of the first rear-stage bridge arm units. A resonant conversion circuit system as described in claim 18, wherein when the first rear-stage conversion circuit converts the second voltage into the first DC voltage, the first rear-stage bridge arm units are used as a full-bridge circuit. The resonant conversion circuit system as described in claim 19, wherein when the first rear-stage conversion circuit converts the second voltage into the second DC voltage, the first rear-stage bridge arm units and the first multi-layer switching elements are used as a three-phase three-layer conversion circuit.

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