GaN-based series resonant single-stage topology circuit

Abstract

The invention discloses a GaN-based series resonant single-stage topology circuit, which adopts a first-stage circuit to simultaneously realize the functions of power factor correction and isolated DC-DC conversion, in which the isolated DC-DC conversion adopts a series resonant soft switch, and a power factor correction auxiliary inductor works in a discontinuous mode. The isolation DC-DC conversion transformer and the power factor correction auxiliary inductor can also adopt an integrated magnetic element design. According to the technology, the power of a single module is broken through to be more than 2kW, wide input voltage (85-305VAC) and complex load scenes are compatible, and a power supply solution with high efficiency, compactness and reliability is provided for leading-edge fields such as electric vehicle over-charging piles, high-computing-power data centers and intelligent power grids.

Description

Technical Field

[0001] The present invention relates to a GaN-based series resonant single-stage topology circuit, belonging to the technical field of topology circuits. Background Art

[0002] Driven by the energy transition and the demand for high-density power supplies, high-frequency operation, wide-range voltage regulation, and high energy efficiency have become the core challenges in power electronics technology. Traditional silicon-based devices are limited by a low critical breakdown field strength (0.3 MV / cm) and high reverse recovery losses, and their switching frequencies (<100 kHz) and power densities are approaching physical limits. Gallium nitride (GaN) HEMT devices, with high electron mobility (>2000 cm 2 / V·s), zero reverse recovery losses, and MHz-level switching capabilities (above 4 MHz), provide a new path for the miniaturization and high efficiency of power systems, but their potential needs to be released through topological innovation.

[0003] As Figure 1 shown, the mainstream AC / DC architectures mostly adopt a two-stage solution of "BOOST-PFC + LLC-DC / DC". Although the single-stage efficiency reaches 97%, the inter-stage losses reduce the overall efficiency to less than 95%, and the component redundancy restricts the power density. Existing single-stage solutions also have bottlenecks: the flyback CrM architecture has a limited efficiency (<92%) due to the bridge rectifier and multiple coupled coil designs, and the power rating is below 200 W; the improved LLC topology (such as patents CN115549476A / CN114710050A) expands the input range, but relies on fixed resonant cavity parameters and a bridge rectifier, with a narrow voltage regulation range (±10%) and a significant efficiency ceiling (<94%). Although gallium nitride (GaN) technology shows great potential in high-frequency and high-power applications, the current single-stage topology circuit solutions on the market still have the following gaps: High-efficiency single-stage topology: There is a lack of high-efficiency single-stage topology circuits that can simultaneously achieve PFC and isolated DC / DC functions on the market, especially in high-power applications; Wide voltage range: Existing single-stage topology circuits have limitations in wide voltage input and output, and cannot meet the requirements of specific application scenarios such as battery charging; Integrated design: There is a lack of a design that integrates all magnetic components within the same magnetic core, resulting in a large system volume and high cost; High efficiency and high power density: Existing technologies are difficult to achieve high power density while achieving high efficiency, restricting their applications in fields such as data centers and electric vehicles.

[0004] In response to the above industry pain points, the present invention proposes a GaN-based series resonant single-stage topology circuit to improve the integration and working efficiency, and provide a power solution with high efficiency, compactness, and reliability for cutting-edge fields such as electric vehicle supercharging piles, high-computing power data centers, and smart grids. Summary of the Invention

[0005] The object of the present invention is to provide a GaN-based series resonant single-stage topology circuit.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A GaN-based series resonant single-stage topology circuit includes: an AC source, a rectification and bypass circuit, a GaN HEMT (gallium nitride high electron mobility transistor) M1, a GaN HEMT M2, a PFC current correction auxiliary inductor Lpa, a resonant capacitor Cra, a resonant inductor Lr, an energy storage capacitor CB, a transformer Ta, a secondary rectification circuit, an output filter capacitor Co, and an output load resistor Ro;

[0008] The AC source is connected to the input end of the rectification and bypass circuit. The bypass positive output end of the rectification and bypass circuit is connected to the source electrode of the GaN HEMT M1 and is also connected to one end of the resonant capacitor Cra. The other end of the resonant capacitor Cra is connected to one end of the resonant inductor Lr. The resonant capacitor Cra and the resonant inductor Lr form a high-frequency resonant cavity. The other end of the resonant inductor Lr is connected to the same-named end of a primary winding Np2 of the transformer Ta. The drain electrode of the GaN HEMT M1 is connected to the source electrode of the GaN HEMT M2. The drain electrode of the GaN HEMT M2 is connected to the negative output end of the six-tube rectification and bypass circuit. The positive end of the energy storage capacitor C B is connected between the source electrode of the GaN HEMT M1 and the resonant capacitor C ra The negative end of the energy storage capacitor C B is connected to the drain electrode of the GaN HEMT M2. The rectification positive output end of the rectification and bypass circuit is connected to one end of the PFC current correction auxiliary inductor Lpa. The other end of the PFC current correction auxiliary inductor Lpa is connected to the same-named end of another primary winding Np1 of the transformer Ta. The primary windings Np1 and Np2 are connected in series. The different-named end of another primary winding Np1 of the transformer Ta is connected between the drain electrode of the GaN HEMT M1 and the source electrode of the GaN HEMT M2;

[0009] The output end of the secondary winding Nsa of the transformer Ta is connected to the input end of the secondary rectification circuit. The output end of the secondary rectification circuit is connected in parallel with the output filter capacitor Co and the output load resistor Ro to achieve DC output.

[0010] Preferably, the rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, and D6. Among them, diodes D1, D2, D3, and D4 form a bridge rectification structure. The positive output terminal of the bridge rectification structure is connected to the positive electrode of the bypass diode D5, and the negative output of the bypass diode D5 is the bypass positive output terminal. The positive output terminal of the bridge rectification structure is also connected to the positive electrode of the boost diode D6 through the PFC current correction auxiliary inductor Lpa. The negative output of the boost diode D6 is the rectification positive output terminal, which is connected to the same-named terminal of the other primary winding Np1 of the transformer Ta.

[0011] Preferably, the rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, and D6. Among them, diodes D1, D2, D3, and D4 form a bridge rectification structure, and the positive output terminal of the bridge rectification structure is the bypass positive output terminal. The positive electrode of diode D5 is connected between the negative electrode of diode D4 and the positive electrode of diode D1, the positive electrode of diode D6 is connected between the negative electrode of diode D2 and the positive electrode of diode D3, and the negative electrodes of diodes D5 and D6 are the positive output terminals of the bridge rectification structure, which are connected to the PFC current correction auxiliary inductor Lpa.

[0012] Preferably, the secondary rectification circuit includes four bridge-connected switching tubes S1, S2, S3, and S4. Among them, the same-named terminal of the secondary winding Nsa of the transformer Ta is connected to the source electrode of the switching tube S1. The drain electrode of the switching tube S1 is connected to the drain electrode of the switching tube S3. The source electrode of the switching tube S3 is connected to the drain electrode of the switching tube S4. The source electrode of the switching tube S4 is connected to the source electrode of the switching tube S2. The drain electrode of the switching tube S2 is connected to the source electrode of the switching tube S1. The different-named terminal of the secondary winding Nsa of the transformer Ta is connected between the source electrode of the switching tube S3 and the drain electrode of the switching tube S4. The positive terminal of the output filter capacitor Co is connected between the drain electrode of the switching tube S1 and the drain electrode of the switching tube S3. The negative terminal of the output filter capacitor Co is connected between the source electrode of the switching tube S2 and the source electrode of the switching tube S4. One end of the output load resistor Ro is connected between the drain electrode of the switching tube S1 and the drain electrode of the switching tube S3, and the other end of the output load resistor Ro is connected between the source electrode of the switching tube S2 and the source electrode of the switching tube S4.

[0013] Preferably, the switching tube is a GaN HEMT or a Si MOSFET.

[0014] Preferably, the transformer Ta further includes a resonant inductor Lm, and the resonant inductor Lm is connected in parallel with the series-connected primary windings.

[0015] Preferably, it further includes another energy storage capacitor C B1 , and this energy storage capacitor C B1 is connected in series with the energy storage capacitor C B2 , and the energy storage capacitor C B1One end is connected between the source electrode of the GaN HEMT M1 and the positive terminal of the energy storage capacitor C B and the other end is connected to the resonant capacitor C ra .

[0016] Preferably, the magnetic components in the circuit can be integrated into the same magnetic core.

[0017] The present invention also discloses a control method for the above-mentioned GaN-based series resonant single-stage topology circuit, specifically:[[]]

[0018] Detect the current I of the inductor Lpa pa . If the current is in the rising stage, it is determined that the topology circuit is in the PFC energy storage stage, and M2 is controlled to conduct to form a loop. At this time, the PFC current flow direction is: the rectified positive output terminal of the rectification and bypass circuit → L pa → N P1 → M2 → the rectified negative output terminal of the rectification and bypass circuit

[0019] At this time, LLC is in the first half cycle, and the current flow direction is: the positive terminal of C B → C ra → L r → L M → M2 → the negative terminal of C B .

[0020] At this time, the secondary side is in the first half cycle, and the current flow direction is: N sa homonymous end → S1 → C o → S4 → N sa heteronymous end;

[0021] Detect the current I of the inductor Lpa pa . If the current is in the falling stage, it is determined that the topology circuit is in the PFC boost stage, and M1 is controlled to conduct to form a loop. At this time, the PFC current flow direction is: the rectified positive output terminal of the rectification and bypass circuit → L pa → N P1 → M1 → C B → the rectified negative output terminal of the rectification and bypass circuit

[0022] At this time, LLC is in the second half cycle, and the current flow direction is: the rectified positive output terminal of the rectification and bypass circuit → L pa → N P2 → L r → C ra → C B → the rectified negative output terminal of the rectification and bypass circuit

[0023] At this time, the secondary side is in the second half cycle, and the current flow direction is: N sa heteronymous end → S3 → C o → S2 → N sa homonymous end.

[0024] The present invention also discloses a GaN-based series resonant conversion device, including the above-mentioned GaN-based series resonant single-stage topology circuit, characterized by further including a control system. The control system samples the voltage of the circuit and provides control signals to each switch. When the load is greater than 50%, a frequency modulation control mode is adopted; when the load is between 10% and 50%, a dual control mode of pulse width modulation and frequency modulation is adopted; when the load is less than 10%, a fixed frequency 200 kHz hopping frequency control mode is adopted.

[0025] Preferably, the control system includes a voltage sampling system, a feedback PID adjustment system, an optocoupler, and a DSP chip that are sequentially connected by signals. The DSP chip controls Driver 1 and Driver 2. Driver 1 is used to provide drive signals to GaN HEMT M1 and GaN HEMT M2, and Driver 2 is used to provide drive signals to switching tubes S1, S2, S3, and S4.

[0026] The present invention discloses a GaN-based series resonant single-stage topology circuit, which simultaneously realizes power factor correction and isolated DC-DC conversion functions with a single-stage circuit. Among them, the isolated DC-DC conversion adopts series resonant soft-switching operation, while the power factor correction auxiliary inductor operates in a discontinuous mode. The isolated DC-DC conversion transformer and the power factor correction auxiliary inductor can also adopt an integrated magnetic component design. This technology breaks through the single-module power to more than 2 kW, is compatible with a wide input voltage (85 - 305 VAC) and complex load scenarios, and provides a power solution with high efficiency, compactness, and reliability for front-line fields such as electric vehicle superchargers, high-computing power data centers, and smart grids.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. Single-stage topology circuit: Under a set of control systems, both the PFC function and the DC / DC isolated output function are realized. An integrated magnetic component design is adopted, and all magnetic components are integrated in the same magnetic core. Compared with the traditional two-stage structure, 1 high-frequency power switch tube and 1 PFC power inductor can be saved, and the size can be reduced by about 10%.

[0029] 2. Power of several kilowatts, the power level is increased from below 200 W of the traditional flyback type to 2 kW and above.

[0030] 3. Full soft-switching, high efficiency, and low EMI: Adopt series resonant soft-switching operation, and the theoretical peak efficiency can reach more than 97%. Compared with Figure 1 the traditional two-stage circuit, the efficiency can be increased by about 2%.

[0031] 4. High operating frequency: It can operate at a high-frequency state of 500 kHz - 4 MHz or even higher. Description of the Drawings

[0032] Figure 1 Schematic diagram of a traditional two-stage circuit architecture of PFC and isolation LLC

[0033] Figure 2 GaN-based series resonant single-stage topology circuit of the present invention

[0034] Figure 3 Topology circuit of Embodiment 1

[0035] Figure 4 Topology circuit of Embodiment 2

[0036] Figure 5 Topology circuit of Embodiment 3

[0037] Figure 6 Input and rectification working path diagram of Embodiment 2

[0038] Figure 7 High-frequency energy storage working path diagram of Embodiment 2

[0039] Figure 8 High-frequency boost working path diagram of Embodiment 2

[0040] Figure 9 High-frequency energy storage and boost working timing waveform diagram of Embodiment 2

[0041] Figure 10 Control logic block diagram of Embodiment 2 Detailed implementation manners

[0042] Figure 2 Displays the circuit structure block diagram of the present invention

[0043] Embodiment 1

[0044] As Figure 3 shown, the GaN-based series resonant single-stage topology circuit of this embodiment includes an AC source, a rectification and bypass circuit, GaN HEMT M1, GaN HEMT M2, PFC current correction auxiliary inductor L pa , resonant capacitor C ra , resonant inductor L r , energy storage capacitor C B , transformer T a , secondary rectification circuit, output filter capacitor C o and output load resistor R o ;

[0045] The AC source V inConnected to the input end of the rectification and bypass circuit. Specifically, the rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, D6. Among them, diodes D1, D2, D3, D4 form a bridge rectification structure, which can be discrete rectification diodes or an integrated rectifier bridge. The positive output terminal of the AC source is connected between the negative electrode of diode D4 and the positive electrode of diode D1, and the negative output terminal of the AC source is connected between the negative electrode of diode D2 and the positive electrode of diode D3. The positive output terminal of the bridge rectification structure is connected to the positive electrode of bypass diode D5, and the negative output of bypass diode D5 is the bypass positive output terminal; the positive output terminal of the bridge rectification structure is also connected to the PFC current correction auxiliary inductor L pa Connected to the positive electrode of boost diode D6, and the negative output of boost diode D6 is the rectification positive output terminal, which is connected to the transformer T a Another primary winding N p1 Of the same name. The bypass diode D5 plays a bypass role. When the input voltage is higher than V B , it can directly charge C B Through D5; D6 is a boost diode and can also prevent current backflow.

[0046] The bypass positive output terminal of the rectification and bypass circuit is connected to the source electrode of GaN HEMT M1 and is connected to one end of the resonant capacitor C ra . The other end of the resonant capacitor C ra Is connected to one end of the resonant inductor L r . The resonant capacitor C ra And the resonant inductor L r Form a high-frequency resonant cavity. The other end of the resonant inductor L r Is connected to the same-name end of one primary winding N a Of the transformer T p2 . The drain electrode of GaN HEMT M1 is connected to the source electrode of GaN HEMT M2, and the drain electrode of GaN HEMT M2 is connected to the negative output terminal of the six-diode rectification and bypass circuit. The positive terminal of the energy storage capacitor C B Is connected between the source electrode of GaN HEMT M1 and the resonant capacitor C ra . The negative terminal of the energy storage capacitor C B Is connected to the drain electrode of GaN HEMT M2. The rectification positive output terminal of the six-diode rectification and bypass circuit is connected to the same-name end of another primary winding N a Of the transformer T p1 . The primary winding N p1 Is in series with N p2 , N p =N p1 +N p2 . The transformer T a Also includes a resonant inductor L m, the resonant inductor L m is connected in parallel with the series-connected primary winding, and the other primary winding N a of the transformer T p1 has its different-named end connected to the source of the GaN HEMT M2, and N p1 and N p2 , L m , and Nsa are all coils of the transformer T a . Lr can be an independent resonant inductor or can be formed by the leakage inductance of T a . C ra , L r , and L m together form a resonant cavity pair during the dead time, and the current correction auxiliary inductor L pa can be formed;

[0047] The secondary rectifier circuit includes four bridge-connected switching tubes S1, S2, S3, and S4. Among them, the secondary winding N a of the transformer T sa has its same-named end connected to the source of the switching tube S1. The drain of the switching tube S1 is connected to the drain of the switching tube S3. The source of the switching tube S3 is connected to the drain of the switching tube S4. The source of the switching tube S4 is connected to the source of the switching tube S2. The drain of the switching tube S2 is connected to the source of the switching tube S1. The secondary winding N a of the transformer T sa has its different-named end connected between the source of the switching tube S3 and the drain of the switching tube S4. The positive terminal of the output filter capacitor C o is connected between the drain of the switching tube S1 and the drain of the switching tube S3. The negative terminal of the output filter capacitor C o is connected between the source of the switching tube S2 and the source of the switching tube S4. One end of the output load resistor R o is connected between the drain of the switching tube S1 and the drain of the switching tube S3. The other end of the output load resistor Ro is connected between the source of the switching tube S2 and the source of the switching tube S4. The switching tubes S1, S2, S3, and S4 can be GaN HEMTs or Si MOSFETs.

[0048] Let L pa = L r , N P1 = N P1 , and L m = 3 to 8L r .

[0049] The circuit working path of this embodiment is as follows:

[0050] PFC energy storage stage: Input a → L pa → D6 → e → N P1 → c → M2 → g;

[0051] PFC Boost stage: Input a → L pa → D6 → e → N P1 → c → M1 → d → C B → g;

[0052] First half of LLC (corresponding to PFC energy storage stage, with M2 conducting to form a loop): C B → d → C ra → L r → h → L M → c → M2 → g;

[0053] Second half of LLC (corresponding to PFC boost stage, with M1 conducting to form a loop): a → L pa → D6 → e → N P2 → h → L r → C ra → d → C B → g;

[0054] First half of secondary side (corresponding to PFC energy storage stage, with M2 conducting to form a loop): N sa → i → S1 → m → C o → n → S4 → j;

[0055] Second half of secondary side (corresponding to PFC boost stage, with M1 conducting to form a loop): N sa → j → S3 → m → C o → n → S2 → i.

[0056] Embodiment 2

[0057] As Figure 4 shown, the GaN-based series resonant single-stage topology circuit of this embodiment includes an AC source, a rectification and bypass circuit, GaN HEMT M1, GaN HEMT M2, a PFC current correction auxiliary inductor L pa , a resonant capacitor C ra , a resonant inductor L r , an energy storage capacitor C B , a transformer T a , a secondary rectification circuit, an output filter capacitor C o and an output load resistor R o ;

[0058] The AC source V inConnected to the input end of the rectification and bypass circuit. Specifically, the rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, and D6. Among them, diodes D1, D2, D3, and D4 form a bridge rectification structure, which can be discrete rectification diodes or a combined rectifier bridge stack. The positive output end of the bridge rectification structure is the bypass positive output end, connected to the source electrode of GaN HEMT M1, and connected in parallel with one end of the resonant capacitor C ra The other end of the resonant capacitor C ra is connected to one end of the resonant inductor L r The resonant capacitor C ra and the resonant inductor L r constitute a high-frequency resonant cavity. The other end of the resonant inductor L r is connected to the same-name end of a primary winding N a of the transformer T p2 ; The positive electrode of diode D5 is connected between the negative electrode of diode D4 and the positive electrode of diode D1. The positive electrode of diode D6 is connected between the negative electrode of diode D2 and the positive electrode of diode D3. The negative electrodes of diodes D5 and D6 are the positive output end of the bridge rectification structure, connected to the PFC current correction auxiliary inductor L pa . The other end of the PFC current correction auxiliary inductor L pa is connected to the same-name end of another primary winding N a of the transformer T p1 . The drain electrode of GaN HEMT M1 is connected to the source electrode of GaN HEMT M2. The drain electrode of GaN HEMT M2 is connected to the negative output end of the rectification and bypass circuit. The positive end of the energy storage capacitor C B is connected between the source electrode of GaN HEMT M1 and the resonant capacitor C ra . The negative end of the energy storage capacitor C B is connected to the drain electrode of GaN HEMT M2. The rectification positive output end of the six-tube rectification and bypass circuit is connected to the same-name end of another primary winding N a of the transformer T p1 . The primary winding N p1 is in series with N p2 , N p = N p1 + N p2 . The transformer T a also includes a resonant inductor L m . The resonant inductor L m is in parallel with the series-connected primary windings. The opposite-name end of another primary winding N a of the transformer T p1 is connected to the source electrode of GaN HEMT M2. N p1 and N p2 , L m and Nsa are all of the transformer Ta The coil, Lr can be an independent resonant inductor or can be composed of the leakage inductance of T a . C ra , L r , L m Together form a resonant cavity pair during the dead time, and the current correction auxiliary inductor L pa can be formed.

[0059] The secondary rectifier circuit includes four bridge-connected switching tubes S1, S2, S3, S4. Among them, the secondary winding N a of the transformer T sa has its same-name terminal connected to the source of the switching tube S1, the drain of the switching tube S1 is connected to the drain of the switching tube S3, the source of the switching tube S3 is connected to the drain of the switching tube S4, the source of the switching tube S4 is connected to the source of the switching tube S2, the drain of the switching tube S2 is connected to the source of the switching tube S1, and the secondary winding N a of the transformer T sa has its different-name terminal connected between the source of the switching tube S3 and the drain of the switching tube S4, the positive terminal of the output filter capacitor C o is connected between the drain of the switching tube S1 and the drain of the switching tube S3, the negative terminal of the output filter capacitor C o is connected between the source of the switching tube S2 and the source of the switching tube S4, one end of the output load resistor R o is connected between the drain of the switching tube S1 and the drain of the switching tube S3, and the other end of the output load resistor Ro is connected between the source of the switching tube S2 and the source of the switching tube S4. The switching tubes S1, S2, S3, S4 can be GaN HEMT or Si MOSFET.

[0060] In this embodiment, D1 and D3 replace D5 in Embodiment 1 and play a bypass role. When the input voltage is higher than V B , it can directly charge C B through D1 and D3; D5 and D6 replace D6 in Embodiment 1 to achieve a boost function and at the same time prevent current backflow.

[0061] Figure 6 Shows the rectification effect of the rectification and bypass circuit in this embodiment. It can be seen that the input AC source is converted into a pulse circuit and a DC circuit.

[0062] Figure 7 Shows the high-frequency energy storage working path, specifically:

[0063] PFC energy storage stage: Input a → L pa → e → N P1 → c → M2 → g;

[0064] The first half cycle of LLC (corresponding to the PFC energy storage stage, with M2 conducting to form a loop): C B →d→C ra →L r →h→L M →c→M2→g;

[0065] The first half cycle of the secondary side (corresponding to the PFC energy storage stage, with M2 conducting to form a loop): N sa →i→S1→m→C o →n→S4→j.

[0066] Figure 8 The high-frequency boost working path is shown as follows:

[0067] PFC boost stage: Input a→L pa →e→N P1 →c→M1→d→C B →g;

[0068] The second half cycle of LLC (corresponding to the PFC boost stage, with M1 conducting to form a loop): a→L pa →e→N P2 →h→L r →C ra →d→C B →g;

[0069] The second half cycle of the secondary side (corresponding to the PFC boost stage, with M1 conducting to form a loop): N sa →j→S3→m→C o →n→S2→i.

[0070] The timing waveform diagrams of high-frequency energy storage and boost operation are shown in Figure 9 .

[0071] Example 3

[0072] As Figure 5 shown, the circuit structure of this example is basically the same as that of Example 2, except that it further includes another energy storage capacitor C B1 , and this energy storage capacitor C B1 is connected in series with the energy storage capacitor C B2 . One end of the energy storage capacitor C B1 is connected between the source of the GaN HEMT M1 and the positive terminal of the energy storage capacitor C B , and the other end is connected to the resonant capacitor C ra . C B1 , C B2 are energy storage capacitors, which can be electrolytic capacitors or ceramic capacitors. Usually, C B1 is a ceramic capacitor, and C B2 is an electrolytic capacitor.

[0073] Its working path is as follows:

[0074] PFC energy storage stage: Input a → L pa → e → N P1 → c → M2 → g;

[0075] PFC boost stage: Input a → L pa → e → N P1 → c → M1 → f → C B2 → g;

[0076] First half of LLC (corresponding to PFC energy storage stage, with M2 conducting to form a loop): C B1 、C B2 Connected in series → d → C ra → L r → h → L M → c → M2 → g;

[0077] Second half of LLC (corresponding to PFC boost stage, with M1 conducting to form a loop): a → L pa → e → N P2 → h → L r → C ra → d → C B1 、C B2 Connected in series → g;

[0078] First half of the secondary side (corresponding to PFC energy storage stage, with M2 conducting to form a loop): Nsa → i → S1 → m → Co → n → S4 → j;

[0079] Second half of the secondary side (corresponding to PFC boost stage, with M1 conducting to form a loop): N sa → j → S3 → m → C o → n → S2 → i.

[0080] The circuit control logic of Embodiments 1-3 is as Figure 10 shown. When the load is greater than 50%, frequency modulation (PFM) control is adopted. When the load is between 10% - 50%, PWM (pulse width modulation) + PFM control is adopted. When the load is less than 10%, fixed-frequency 200kHz hopping control is adopted.

[0081] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A GaN-based series resonant single-stage topology circuit, characterized in that Comprising: An AC source, a rectification and bypass circuit, a GaN HEMT M1, a GaN HEMT M2, a PFC current correction auxiliary inductor Lpa, a resonant capacitor Cra, a resonant inductor Lr, an energy storage capacitor CB, a transformer Ta, a secondary rectification circuit, an output filter capacitor Co, and an output load resistor Ro; The AC source is connected to the input end of the rectification and bypass circuit. The bypass positive output end of the rectification and bypass circuit is connected to the source electrode of GaN HEMT M1 and is also connected to one end of the resonant capacitor Cra. The other end of the resonant capacitor Cra is connected to one end of the resonant inductor Lr. The resonant capacitor Cra and the resonant inductor Lr form a high-frequency resonant cavity. The other end of the resonant inductor Lr is connected to the same-name end of a primary winding Np2 of the transformer Ta. The drain electrode of GaN HEMT M1 is connected to the source electrode of GaN HEMT M2. The drain electrode of GaN HEMT M2 is connected to the negative output end of the rectification and bypass circuit. The positive end of the energy storage capacitor C B is connected to the source electrode of GaN HEMT M1 and the resonant capacitor C ra between them. The negative end of the energy storage capacitor C B is connected to the drain electrode of GaN HEMT M2. The rectification positive output end of the rectification and bypass circuit is connected to one end of the PFC current correction auxiliary inductor Lpa. The other end of the PFC current correction auxiliary inductor Lpa is connected to the same-name end of another primary winding Np1 of the transformer Ta. The primary windings Np1 and Np2 are connected in series. The different-name end of another primary winding Np1 of the transformer Ta is connected between the drain electrode of GaN HEMT M1 and the source electrode of GaN HEMT M2; The output end of the secondary winding Nsa of the transformer Ta is connected to the input end of the secondary rectification circuit, and the output end of the secondary rectification circuit is connected in parallel with the output filter capacitor Co and the output load resistor Ro to achieve DC output.

2. The GaN-based series resonant single-stage topology circuit according to claim 1, wherein: The rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, D6, wherein the diodes D1, D2, D3, D4 form a bridge rectification structure. The positive output end of the bridge rectification structure is connected to the positive electrode of the bypass diode D5, and the negative output of the bypass diode D5 is the bypass positive output end; the positive output end of the bridge rectification structure is also connected to the positive electrode of the boost diode D6 through the PFC current correction auxiliary inductor Lpa, and the negative output of the boost diode D6 is the rectification positive output end, which is connected to the same-named end of another primary winding Np1 of the transformer Ta.

3. The GaN-based series resonant single-stage topology circuit according to claim 1, wherein: The rectification and bypass circuit includes six diodes D1, D2, D3, D4, D5, D6, wherein the diodes D1, D2, D3, D4 form a bridge rectification structure, and the positive output end of the bridge rectification structure is the bypass positive output end; the positive electrode of the diode D5 is connected between the negative electrode of the diode D4 and the positive electrode of the diode D1, the positive electrode of the diode D6 is connected between the negative electrode of the diode D2 and the positive electrode of the diode D3, and the negative electrodes of the diodes D5 and D6 are the positive output end of the bridge rectification structure, which is connected to the PFC current correction auxiliary inductor Lpa.

4. The GaN-based series resonant single-stage topology circuit according to any one of claims 1 to 3, characterized in that: The secondary rectification circuit includes four transistors S1, S2, S3, S4 connected in a bridge. The same-named end of the secondary winding Nsa of the transformer Ta is connected to the source electrode of the switching transistor S1. The drain electrode of the switching transistor S1 is connected to the drain electrode of the switching transistor S3. The source electrode of the switching transistor S3 is connected to the drain electrode of the switching transistor S4. The source electrode of the switching transistor S4 is connected to the source electrode of the switching transistor S2. The drain electrode of the switching transistor S2 is connected to the source electrode of the switching transistor S1. The different-named end of the secondary winding Nsa of the transformer Ta is connected between the source electrode of the switching transistor S3 and the drain electrode of the switching transistor S4. The positive end of the output filter capacitor Co is connected between the drain electrodes of the switching transistors S1 and S3. The negative end of the output filter capacitor Co is connected between the source electrodes of the switching transistors S2 and S4. One end of the output load resistor Ro is connected between the drain electrodes of the switching transistors S1 and S3, and the other end of the output load resistor Ro is connected between the source electrodes of the switching transistors S2 and S4.

5. The GaN-based series resonant single-stage topology circuit according to claim 4, characterized in that: The switching transistor is a GaN HEMT or an Si MOSFET.

6. The GaN-based series resonant single-stage topology circuit according to claim 4, wherein: The transformer Ta further includes a resonant inductor Lm, and the resonant inductor Lm is connected in parallel with the series-connected primary winding.

7. The GaN-based series resonant single-stage topology circuit according to claim 4, wherein: It also includes another energy storage capacitor C B1 , and this energy storage capacitor C B1 is in series with the energy storage capacitor C B2 . One end of the energy storage capacitor C B1 is connected between the source of the GaN HEMT M1 and the positive terminal of the energy storage capacitor C B , and the other end is connected to the resonant capacitor C ra .

8. The control method of the GaN-based series resonant single-stage topology circuit according to any one of claims 1-7, characterized in that: Detect the current I of inductor Lpa pa , if the current is in the rising stage, it is determined that the topology circuit is in the PFC energy storage stage, and M2 is controlled to conduct to form a loop. At this time, the PFC current flow direction is: the rectification positive output terminal of the rectification and bypass circuit → L pa → N P1 → M2 → the rectification negative output terminal of the rectification and bypass circuit At this time, the LLC is in the first half cycle, and the current flow direction is: the positive terminal of C B → C ra → L r → L M → M2 → the negative terminal of C B ​ At this time, the secondary side is in the first half cycle, and the current flow direction is: N sa Same-named terminal → S1 → C o → S4 → N sa Opposite-named terminal; Detect the current I of inductor Lpa pa , if the current is in the descending stage, it is determined that the topology circuit is in the PFC boost stage, and M1 is controlled to conduct to form a loop. At this time, the PFC current flow direction is: the rectification positive output terminal of the rectification and bypass circuit → L pa → N P1 → M1 → C B → the rectification negative output terminal of the rectification and bypass circuit At this time, the LLC is in the second half cycle, and the current flow direction is: the positive rectifier output terminal of the rectification and bypass circuit → L pa → N P2 → L r → C ra → C B → the negative rectifier output terminal of the rectification and bypass circuit At this time, the secondary side is in the second half cycle, and the current flow direction is: N sa From the unlike-named terminal → S3 → C o → S2 → N sa To the like-named terminal.

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