A wide gain LLC resonant converter

Abstract

The utility model relates to the field of DC conversion in power electronics technology, concretely relates to a wide gain LLC resonant converter. A wide gain LLC resonant converter, including transformer and its primary excitation inductance L m , resonant inductance L r , resonant capacitor C r , switching circuit, rectifier output circuit, the primary excitation inductance L m , resonant inductance L r , resonant capacitor C r constitute the resonant cavity. The utility model's LLC resonant converter changes the connection mode of rectifier output circuit, switches different rectifier output circuit topology structure, widens the gain range of LLC resonant converter, realizes the full domain ZVS, expands the input voltage range of converter.

Description

Technical Field

[0001] This utility model relates to the field of DC-DC conversion in power electronics technology, and particularly to a wide-gain LLC resonant converter. Background Technology

[0002] The LLC resonant converter is a high-efficiency topology paradigm in modern power electronics. With its excellent energy conversion efficiency and highly integrated design, it has become one of the core technologies for DC-DC power conversion. Based on the resonant transmission mechanism, this circuit utilizes a precisely tuned LC resonant network to achieve zero-voltage turn-on (ZVS) and zero-current turn-off (ZCS) of the power switching devices, fundamentally overcoming the loss bottleneck in traditional hard-switching operations and significantly improving system energy efficiency. Its outstanding comprehensive performance has led to its large-scale application in high-end industrial scenarios such as distributed photovoltaic energy storage devices.

[0003] A major challenge facing distributed photovoltaic energy storage devices is their wide output voltage fluctuation range, which requires LLC resonant converters to maintain efficient operation under a wide input voltage range. However, due to the inherent limitations of the gain characteristic curve of traditional LLC resonant converters, LLC topologies struggle to maintain efficient and stable operation over a wide input voltage range. Input voltage deviations from the rated value will lead to abnormal LLC operation: excessively high voltage forces the switching frequency to be much higher than the resonant frequency, causing gain attenuation and loss of ZVS conditions, resulting in efficiency degradation; excessively low voltage requires operation at extremely low frequencies, which, although improving gain, easily triggers capacitive turn-on, bringing huge current stress and turn-on losses, seriously threatening the safety of the switching transistors. Utility Model Content

[0004] The purpose of this invention is to provide a wide-gain LLC resonant converter. This resonant converter switches between 2x gain mode and 4x gain mode by changing the connection method of the rectifier output circuit, breaking through the inherent limitation of the narrow gain range of traditional LLC topologies, widening the gain range of LLC resonant converters, and achieving high efficiency and stability with full-domain ZVS and a wide input voltage range.

[0005] To achieve the above-mentioned objectives of this utility model, the following technical solution is used:

[0006] A wide-gain LLC resonant converter includes a transformer and its primary magnetizing inductor L. m Resonant inductor L r Resonant capacitor C r Switching circuit, rectifier output circuit; the primary-side magnetizing inductor L m Resonant inductor L r Resonant capacitor C rThe resonant cavity is formed; the switching circuit includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a first inductor L. b1 Second inductor L b2 DC input capacitor C in DC-side output capacitor C bus Input voltage U in The rectifier output circuit includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a first diode D. 01 Second diode capacitor D 02 Third diode D 03 Fourth diode D 04 Output capacitor C0, load R0.

[0007] Furthermore, the switching transistor is an N-MOSFET power transistor.

[0008] Furthermore, the resonant cavity is composed of the resonant inductor L r One end and the resonant capacitor C r One end is connected to the resonant inductor L. r The other end is connected to the upper end of the primary winding of the transformer, and the resonant capacitor C r The other end is connected to the source of the first switch S1, and the primary magnetizing inductor L m It is connected in parallel with the primary winding of the transformer.

[0009] Furthermore, the switching circuit consists of the source of the first switching transistor S1, the drain of the second switching transistor S2, and the first inductor L. b1 One end of each is connected together, and the source of the third switch S3, the drain of the fourth switch S4, and the second inductor L are connected together. b2 One end of each switch is connected together, and the drain of the first switch S1 is connected to the drain of the third switch S3 at point A; the source of the second switch S2 is connected to the source of the fourth switch S4 at point B; the first inductor L b1 The other end, the second inductor L b2 The other end, the input voltage U in The positive terminal is connected to the DC-side input capacitor C. in One end of the input voltage U is connected together with the other end of the input voltage U. in The negative terminal, the DC side input capacitor C in The other end, the DC-side output capacitor C bus One end of each capacitor is connected to point B; the DC-side output capacitor C busThe other end is connected to point A.

[0010] Furthermore, the first capacitor C1, the second capacitor C2, and the fourth diode D 04 The fourth capacitor C4 and one end of the third capacitor C3 are connected in series in sequence, and the other end of the first capacitor C1 is connected to the upper end of the secondary winding of the transformer, and the other end of the third capacitor C3 is connected to the lower end of the secondary winding of the transformer. The fourth diode D is connected in series. 04 The anode of the fourth diode is connected in series with the second capacitor C2. 04 The cathode of the fifth switch S5 is connected in series with the fourth capacitor C4, and the drain of the fifth switch S5 is connected with the drain of the sixth switch S6.

[0011] Furthermore, the source of the fifth switch S5 is connected to the series connection line between the first capacitor C1 and the second capacitor C2, and the source of the fifth switch S5 is also connected to the first diode D. 01 cathode, second diode D 02 The anode connection, the first diode D 01 The anode of the second diode is connected to the lower end of the secondary winding of the transformer. 02 The cathode of the sixth switch S6 is connected to the drain of the eighth switch S8, the source of the eighth switch S8 is connected to the series connection line between the third capacitor C3 and the fourth capacitor C4, and the source of the sixth switch S6 is connected to the fourth diode D. 04 The anode.

[0012] Furthermore, the drain of the seventh switch S7 is connected to the third diode D. 03 The cathode terminal of the seventh switch S7 is connected to the source terminal of the fourth diode D. 04 The anode terminal is connected to the third diode D. 03 The anode of the diode is connected to the source of the eighth switch S8; the output capacitor C0 is connected in parallel with the load R0, and one end of the output capacitor C0 is connected to the first diode D. 01 The anode of the output capacitor C0 is connected to the fourth diode D. 04 The cathode.

[0013] The beneficial effects of this utility model are that by changing the connection method of the rectifier output circuit, the wide gain range of the LLC resonant converter is broadened, achieving high efficiency and stability with full-range ZVS and a wide input voltage range. Attached Figure Description

[0014] Figure 1This is a schematic diagram of a wide-gain LLC resonant converter topology according to the present invention;

[0015] Figure 2 This is a schematic diagram of a voltage doubler rectifier topology of a specific embodiment of a wide-gain LLC resonant converter according to this utility model;

[0016] Figure 3 This is a schematic diagram of a four-voltage rectifier topology of a specific embodiment of a wide-gain LLC resonant converter according to this utility model;

[0017] Figure 4 This is a schematic diagram of the switching circuit signal of a specific embodiment of a wide-gain LLC resonant converter according to this utility model. Detailed Implementation Plan

[0018] To make the embodiments of this utility model clearer, the specific implementation methods of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described herein are only some examples of this utility model and do not cover all possible implementation methods. All other implementation methods obtained by those skilled in the art based on this utility model without creative effort within the spirit and principles of this utility model are within the protection scope of this utility model.

[0019] Figure 1 This is a schematic diagram of a wide-gain LLC resonant converter topology according to this utility model. Figure 1 As shown, it includes the transformer and its primary magnetizing inductance L. m Resonant inductor L r Resonant capacitor C r The circuit includes a switching circuit and a rectifier output circuit. This embodiment of a wide-gain LLC resonant converter expands the gain range of the LLC resonant converter by changing the connection method of the rectifier output circuit, achieving ZVS across the entire voltage range and improving efficiency and stability over a wide input voltage range.

[0020] Furthermore, in Figure 1 The wide-gain LLC resonant converter mentioned above includes a transformer and its primary-side magnetizing inductor L. m Resonant inductor L r Resonant capacitor C r Switching circuit, rectifier output circuit; the primary-side magnetizing inductor L m Resonant inductor L r Resonant capacitor C r The resonant cavity is formed; the switching circuit includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a first inductor L. b1 Second inductor L b2 DC input capacitor C inDC-side output capacitor C bus Input voltage U in The rectifier output circuit includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a first diode D. 01 Second diode capacitor D 02 Third diode D 03 Fourth diode D 04 Output capacitor C0, load R0.

[0021] Furthermore, the switching transistor is an N-MOSFET power transistor.

[0022] Furthermore, the resonant cavity is composed of the resonant inductor L r One end and the resonant capacitor C r One end is connected to the resonant inductor L. r The other end is connected to the upper end of the primary winding of the transformer, and the resonant capacitor C r The other end is connected to the source of the first switch S1, and the primary magnetizing inductor L m It is connected in parallel with the primary winding of the transformer.

[0023] Furthermore, the switching circuit consists of the source of the first switching transistor S1, the drain of the second switching transistor S2, and the first inductor L. b1 One end of each is connected together, and the source of the third switch S3, the drain of the fourth switch S4, and the second inductor L are connected together. b2 One end of each switch is connected together, and the drain of the first switch S1 is connected to the drain of the third switch S3 at point A; the source of the second switch S2 is connected to the source of the fourth switch S4 at point B; the first inductor L b1 The other end, the second inductor L b2 The other end, the input voltage U in The positive terminal is connected to the DC-side input capacitor C. in One end of the input voltage U is connected together with the other end of the input voltage U. in The negative terminal, the DC side input capacitor C in The other end, the DC-side output capacitor C bus One end of each capacitor is connected to point B; the DC-side output capacitor C bus The other end is connected to point A.

[0024] Furthermore, the first capacitor C1, the second capacitor C2, and the fourth diode D 04The fourth capacitor C4 and one end of the third capacitor C3 are connected in series in sequence, and the other end of the first capacitor C1 is connected to the upper end of the secondary winding of the transformer, and the other end of the third capacitor C3 is connected to the lower end of the secondary winding of the transformer. The fourth diode D is connected in series. 04 The anode of the fourth diode is connected in series with the second capacitor C2. 04 The cathode of the fifth switch S5 is connected in series with the fourth capacitor C4, and the drain of the fifth switch S5 is connected with the drain of the sixth switch S6.

[0025] Furthermore, the source of the fifth switch S5 is connected to the series connection line between the first capacitor C1 and the second capacitor C2, and the source of the fifth switch S5 is also connected to the first diode D. 01 cathode, second diode D 02 The anode connection, the first diode D 01 The anode of the second diode is connected to the lower end of the secondary winding of the transformer. 02 The cathode of the sixth switch S6 is connected to the drain of the eighth switch S8, the source of the eighth switch S8 is connected to the series connection line between the third capacitor C3 and the fourth capacitor C4, and the source of the sixth switch S6 is connected to the fourth diode D. 04 The anode.

[0026] Furthermore, the drain of the seventh switch S7 is connected to the third diode D. 03 The cathode terminal of the seventh switch S7 is connected to the source terminal of the fourth diode D. 04 The anode terminal is connected to the third diode D. 03 The anode of the diode is connected to the source of the eighth switch S8; the output capacitor C0 is connected in parallel with the load R0, and one end of the output capacitor C0 is connected to the first diode D. 01 The anode of the output capacitor C0 is connected to the fourth diode D. 04 The cathode.

[0027] Figure 2 This is a schematic diagram of a voltage doubler rectifier topology in a specific embodiment of a wide-gain LLC resonant converter according to this utility model. (Refer to...) Figure 2 As shown, when switches S5 and S6 are turned on and switches S7 and S8 are turned off, the converter is in a double voltage rectifier output state. At this time, the gain of the converter output voltage V0 is increased by 2 times compared with the traditional LLC resonant converter.

[0028] Figure 3 This is a schematic diagram of a four-voltage rectifier topology of a wide-gain LLC resonant converter according to a specific embodiment of this utility model. (Refer to...) Figure 3As shown, when switches S7 and S8 are turned on and switches S5 and S6 are turned off, the converter is in a quadruple voltage rectifier output state. At this time, the gain of the converter output voltage V0 is increased by 4 times compared with the traditional LLC resonant converter.

[0029] Furthermore, in specific embodiments, regardless of whether the wide-gain LLC resonant converter of this invention operates in a voltage doubler rectification or a voltage quadrupler rectification output state, the control signals of switches S1 and S2 are complementary by 180°, and the control signals of switches S3 and S4 are complementary by 180°. (Refer to...) Figure 4 As shown, the duty cycle of the control signal of switch S4 is D, the duty cycle of the control signal of switch S1 is 1-D, and φ is the phase shift angle of the control signal of switch S1 lagging behind the control signal of switch S4. The relationship between the phase shift angle and the duty cycle D satisfies:

[0030] In specific embodiments, the parameters of each device can be configured according to the actual application. Preferably, in this embodiment of the invention, the input voltage U of the converter is used as the reference. in Taking an output voltage V0 of 24V within the 35~120V range as an example: when U in Within the range of 35~60V, a quadruple voltage rectification mode is adopted; when U in Within the range of 60~120V, a voltage doubler rectification mode is adopted. Once the rectification mode is selected, the output voltage V0 is maintained by finely adjusting the phase shift angle to ensure the ZVS of the switching transistor. This can be combined with phase shift control to achieve a lower voltage gain than traditional frequency converter control. This embodiment of a wide-gain LLC resonant converter expands the gain range of traditional LLC resonant converters and extends the input voltage range by switching different rectified output topologies.

[0031] For those skilled in the art, the above embodiments are merely illustrative and do not constitute a limitation on the scope of protection of this utility model. Within the spirit and principles of this utility model, any person skilled in the art may make various modifications, optimizations, or adjustments. These modifications should also be considered to fall within the scope of the embodiments of this utility model and are protected by this utility model.

Claims

1. A wide-gain LLC resonant converter, characterized in that, Including the transformer and its primary magnetizing inductance L m Resonant inductor L r Resonant capacitor C r Switching circuit, rectifier output circuit; The primary excitation inductor L m Resonant inductor L r Resonant capacitor C r Construct a resonant cavity; The switching circuit includes a first switching transistor S1, a second switching transistor S2, a third switching transistor S3, a fourth switching transistor S4, and a first inductor L. b1 Second inductor L b2 DC input capacitor C in DC-side output capacitor C bus Input voltage U in ; The rectifier output circuit includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a first diode D. 01 Second diode capacitor D 02 Third diode D 03 Fourth diode D 04 Output capacitor C0, load R0.

2. The wide-gain LLC resonant converter as described in claim 1, characterized in that, The switching transistor is an N-MOSFET power transistor.

3. The wide-gain LLC resonant converter as described in claim 1, characterized in that, The resonant cavity is composed of the resonant inductor L. r One end and the resonant capacitor C r One end is connected to the resonant inductor L. r The other end is connected to the upper end of the primary winding of the transformer, and the resonant capacitor C r The other end is connected to the source of the first switch S1, and the primary magnetizing inductor L m It is connected in parallel with the primary winding of the transformer.

4. A wide-gain LLC resonant converter as described in claim 1, characterized in that, The switching circuit consists of the source of the first switching transistor S1, the drain of the second switching transistor S2, and the first inductor L. b1 One end of each is connected together, and the source of the third switch S3, the drain of the fourth switch S4, and the second inductor L are connected together. b2 One end of each switch is connected together, and the drain of the first switch S1 is connected to the drain of the third switch S3 at point A; the source of the second switch S2 is connected to the source of the fourth switch S4 at point B; the first inductor L b1 The other end, the second inductor L b2 The other end, the input voltage U in The positive terminal is connected to the DC-side input capacitor C. in One end of the input voltage U is connected together; in The negative terminal, the DC side input capacitor C in The other end, the DC-side output capacitor C bus One end of each capacitor is connected to point B; the DC-side output capacitor C bus The other end is connected to point A.

5. A wide-gain LLC resonant converter as described in claim 1, characterized in that, The first capacitor C1, the second capacitor C2, and the fourth diode D 04 The fourth capacitor C4 and one end of the third capacitor C3 are connected in series in sequence, and the other end of the first capacitor C1 is connected to the upper end of the secondary winding of the transformer, and the other end of the third capacitor C3 is connected to the lower end of the secondary winding of the transformer. The fourth diode D is connected in series. 04 The anode of the fourth diode is connected in series with the second capacitor C2. 04 The cathode of the fifth switch S5 is connected in series with the fourth capacitor C4, and the drain of the fifth switch S5 is connected with the drain of the sixth switch S6.

6. A wide-gain LLC resonant converter as described in claim 1, characterized in that, The source of the fifth switch S5 is connected to the series connection line between the first capacitor C1 and the second capacitor C2, and the source of the fifth switch S5 is also connected to the first diode D. 01 cathode, second diode D 02 The anode connection, the first diode D 01 The anode of the second diode is connected to the lower end of the secondary winding of the transformer. 02 The cathode of the sixth switch S6 is connected to the drain of the eighth switch S8, the source of the eighth switch S8 is connected to the series connection line between the third capacitor C3 and the fourth capacitor C4, and the source of the sixth switch S6 is connected to the fourth diode D. 04 The anode.

7. A wide-gain LLC resonant converter as described in claim 1, characterized in that, The drain of the seventh switch S7 and the third diode D 03 The cathode terminal of the seventh switch S7 is connected to the source terminal of the fourth diode D. 04 The anode terminal is connected to the third diode D. 03 The anode of the diode is connected to the source of the eighth switch S8; the output capacitor C0 is connected in parallel with the load R0, and one end of the output capacitor C0 is connected to the first diode D. 01 The anode of the output capacitor C0 is connected to the fourth diode D. 04 The cathode.

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