A series resonant dc-dc converter

Abstract

The utility model belongs to the power electronic conversion technical field, specifically is a series resonance DC-DC series connection ware, include: two -way staggered parallel topology: two sets of symmetry resonant unit (including full -bridge circuit H1 / H2, resonance network Lr -Cr, high frequency transformer T1 / T2), its vice edge connection reconfigurable rectifier unit (six groups of rectifier bridge arm D1-D6), support full parallel / mixed connection / full series three kinds of hardware connection mode, integrated magnetic piece module: adopt three -column type magnetic core, the middle column is around the original side winding and opens 0.5mm air gap, both sides column winding vice side winding, utilize the leakage inductance as the resonance inductance, micro -channel cooling system: aluminium alloy baseboard inlay cross section 2mm * 2mm spiral water channel, through the AlN ceramic baseplate heat conduction. Technical effect: power density reaches 3.2kW / L;The output voltage range is widened to 150-800VDC;Full load range realizes soft switch (ZVS / ZCS);10kW working condition chip temperature rise is less than or equal to 15 DEG C;It is applicable to new energy automobile charging and data center power supply system.

Description

Technical Field

[0001] This utility model belongs to the field of power electronic conversion technology, specifically a series resonant DC-DC converter. Background Technology

[0002] Series resonant converters (SRCs) have become a core technology in the modern DC-DC conversion field due to their soft-switching characteristics and high power density.

[0003] However, existing technologies still face three major bottlenecks: Power density limitation: The DC-side capacitor of traditional SRC is bulky. When the ratio of the resonant capacitor to the DC-side capacitor is close to 1, the current characteristics of the high-frequency link change significantly, leading to an increase in the size of passive components. This restricts the application of converters in space-constrained scenarios (such as on-board chargers).

[0004] Narrow soft-switching range: Although conventional LLC converters can achieve zero-voltage turn-on (ZVS) and zero-current turn-off (ZCS), their soft-switching characteristics are easily lost over a wide input voltage range. Experiments show that when the input voltage fluctuates by more than ±20%, the ZVS capability of the hysteresis arm decreases significantly, leading to increased switching losses.

[0005] Thermal management challenges: Under high-power conditions (>5kW), the internal hot spot temperature of the converter can exceed 100℃, making it difficult for traditional air-cooling solutions to meet temperature control requirements. Sustained high-temperature operation will lead to magnetic component saturation and MOSFET failure, significantly reducing reliability.

[0006] To address the above issues, existing technologies have proposed some solutions: Capacitor optimization design: Power density is improved by reducing the size of the DC-side capacitor, but the switching frequency control algorithm needs to be redesigned; Multi-mode control: The output voltage range is widened by using series-parallel topology switching, but electronic switches are required, introducing additional failure risks; Water cooling: Cooling water circuits are laid around the converter, but the structure is complex and increases the system weight.

[0007] Therefore, this utility model provides a series resonant DC-DC series converter. Utility Model Content

[0008] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0009] The technical solution adopted by this utility model to solve its technical problem is as follows: A series resonant DC-DC converter of this utility model includes: a power conversion unit; a symmetrical resonant channel; and two sets of parallel power paths, each path comprising: The full-bridge circuit (H1 / H2) consists of four MOSFETs; the series resonant network includes a resonant inductor (Lr), a resonant capacitor (Cr), and the primary side of the high-frequency transformer (T1 / T2); the reconfigurable rectifier unit consists of six rectifier bridge arms (D1-D6) (three full-bridge rectifier arms (D1-D2, D3-D4, D5-D6) are connected to the secondary side of the transformer, forming three electrical connection structures).

[0010] Preferably, the heat dissipation structure is as follows: microchannel substrate: a spiral water channel with a cross-section of 2mm×2mm is opened inside the aluminum alloy substrate; layered thermal conduction structure: from top to bottom, power device → 0.2mm thermally conductive silicone grease layer → AlN ceramic insulating layer → microchannel substrate.

[0011] Preferably, the magnetic integrated module has the following characteristics: a three-column magnetic core with the primary winding wound on the middle column and the secondary winding wound on both side columns; and an air gap structure with a 0.5mm air gap in the middle column.

[0012] Preferably, the resonant network includes: a resonant inductor (Lr), a resonant capacitor (Cr), and the primary side of the transformer (T1 / T2) connected in series between the AC sides of H1 and H2.

[0013] Preferably, the rectifier unit includes: reconfigurable connection of the cathode and anode of D1-D6 to realize three modes: full parallel connection, mixed connection, and full series connection.

[0014] Preferably, the cooling system includes: a microchannel substrate tightly bonded to the bottom of the MOSFET and diode, and inlet and outlet ports using G1 / 4 threaded interfaces.

[0015] Preferably, the control module includes: a DSP controller outputting four independent PWM signals, which are connected to the gate drivers of H1 / H2 via optical fibers.

[0016] Preferably, temperature monitoring includes: an NTC thermistor soldered to the drain pin of the MOSFET in H1, with a wire passing through a magnetic ring and connected to the ADC sampling circuit. The beneficial effects of this utility model are as follows: Bidirectional interleaved parallel architecture: It adopts two parallel symmetrical resonant units, each consisting of a full-bridge inverter, a series resonant network and a high-frequency transformer, to achieve automatic power sharing and reduce single-path current stress by 50%.

[0017] Three-mode control strategy: By adjusting the phase difference of the H-bridge drive, three working modes (full parallel, mixed, and full series) can be achieved without changing the hardware connection, and the output voltage range is widened to 300-800VDC.

[0018] Integrated magnetic component design: The resonant inductor (Lr), magnetizing inductor (Lm) and high-frequency transformer are integrated into a single magnetic core, and the leakage inductance of the transformer is used as the resonant inductor, reducing the number of discrete components by 30%.

[0019] Microchannel cooling system: Spiral microchannels are embedded in the power module substrate, and thermal grease interface is used to reduce thermal resistance to 0.15℃ / W. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 This is the overall system architecture diagram; Figure 2 This is a bidirectional power flow control block diagram; Figure 3 This is a configuration diagram of interleaved parallel rectifier units; Figure 4 This is a structural diagram of a microchannel cooling system; Figure 5 This is a waveform diagram of soft switching. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0023] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings. This embodiment takes a 10kW bidirectional converter as an example, with an input voltage range of 300-400VDC and an output voltage range of 150-800VDC.

[0024] The present invention relates to a series resonant DC-DC converter, wherein the component selection and parameter design are as follows: Power module: The main switching transistor is a SiC MOSFET (Cree C3M0075120K), with a withstand voltage of 1200V and an on-resistance of 75mΩ. The rectifier diode is a SiC Schottky diode (STPSC10H12), with a withstand voltage of 1200V and a current rating of 10A. Reason: SiC devices have excellent high-frequency characteristics and almost zero reverse recovery charge, making them suitable for ZCS applications.

[0025] Resonant network: The resonant frequency fr = 100kHz; the resonant inductance Lr = 15μH (using the leakage inductance of the transformer); the resonant capacitor Cr = 170nF, using a multilayer ceramic capacitor made of C0G material; the transformer turns ratio is 1:1.8, and the primary and secondary windings are wound with Litz wire to reduce skin effect losses.

[0026] Control circuit: DSP controller: TI TMS320F28379D, dual-core 200MHz; Gate driver: ISO5852S, isolation voltage 5kVRMS; Voltage sampling: AMC1300 isolated op-amp, accuracy ±0.5%7.

[0027] The operating mode control logic in the embodiment is as follows: Mode switching strategy: Startup phase: DSP detects V_in=360VDC, V_out=400VDC (battery pack), and calculates the gain G=400 / 360≈1.11; Since G < 1.5, the full parallel mode is selected, with an output current capacity of 300A; When V_out rises to 700VDC (constant current to constant voltage), G=700 / 360≈1.94, switch to hybrid mode; If V_out needs to reach 800V and G>2.2, then switch to fully serial mode.

[0028] Key point: Mode switching occurs at the zero-crossing point of the resonant current to avoid voltage spikes.

[0029] In the embodiment, thermal management is implemented as follows: Cooling system operating parameters: Coolant: 50% ethylene glycol aqueous solution; Flow rate: 6L / min (centrifugal pump with 3m head); Inlet temperature: 30±2℃; Thermal design power: 1kW (loss at 10kW output).

[0030] Actual measured data: ambient temperature 40℃, 10kW full load operation for 2 hours, highest temperature point (H1 upper pipe) junction temperature 78℃, radiator outlet water temperature 35℃.

[0031] Performance verification in the examples: Testing was conducted on a 1.5kW prototype: Efficiency curve: Peak efficiency 98.2% (half load), 90% load efficiency >96%; Temperature rise data: Under natural cooling, the temperature rise under full load in a 30℃ environment is 42℃; after adding microchannel heat dissipation, the temperature rise is reduced to 15℃. Dynamic response: Input step change ±20%, output voltage recovery time <500μs, overshoot <5%.

[0032] One embodiment includes: First / second voltage regulator capacitors (C1, C2): connected to the DC input / output terminals; First / Second Converter (H1, H2): Both are full-bridge circuits composed of four MOSFETs. C1 is connected in parallel on the DC side of H1, and C2 is connected in parallel on the DC side of H2. Resonant network: includes resonant inductor (Lr), resonant capacitor (Cr), and transformer (T1). The primary windings of Lr, Cr, and T1 are connected in series between the AC sides of H1 and H2. Control module: Outputs four PWM signals to the gate drivers of H1 and H2, with an adjustable phase difference range of 0-180°; Interleaved parallel extension unit: The second set of resonant networks (Lr2,Cr2,T2) is connected in parallel with the first set to form a dual-channel power path.

[0033] Taking a 1.5kW converter as an example, C1 and C2 are 450V / 680μF electrolytic capacitors; H1 and H2 are Infineon IMZA65R048M1 CoolMOS; Lr=20μH, Cr=220nF / 630VMKP capacitors; T1 / T2 turns ratio 1:2, magnetic core is E65 / 32 / 27; control module is based on TI TMS320F28075 DSP.

[0034] The control module has bidirectional power flow management functionality: When energy flows from C1 to C2, H1 operates in inverter mode and H2 operates in rectifier mode. When energy flows from C2 to C1, H2 operates in active rectification mode, and H1 operates in synchronous rectification mode. Mode switching is automatically triggered by the DSP detecting the polarity of the port voltage. In the battery charging scenario, C1 is connected to the 360V DC bus, and C2 is connected to the battery pack. During charging, H1 inverts and H2 rectifies; during regenerative discharge, H2 inverts and H1 rectifies. Experiments show that the bidirectional conversion efficiency is >96%.

[0035] The resonant network adopts an interleaved parallel structure: The secondary sides of the two transformers (T1, T2) are connected through a full-bridge rectifier unit; The rectifier unit contains six bridge arms (D1-D6) (actually, it should be three full-bridge rectifier arms, each containing two diodes), and can be configured as follows: Full parallel mode: D1-D6 output terminals are connected in parallel, supporting low voltage and high current (48V / 300A). Hybrid mode: The secondary side of T1 is connected in series and then in parallel with the secondary side of T2, supporting medium voltage and medium current (200V / 100A). Full series mode: T1 and T2 secondary sides are connected in series, supporting high voltage and low current (800V / 25A).

[0036] The six bridge arms use Cree C3D10060A SiC diodes. Mode switching is achieved by changing the drive timing via DSP, eliminating the need for mechanical relays. The switching time from all parallel to all series connection is <100μs, and the output voltage fluctuation is <5%.

[0037] It also includes a microchannel cooling system: Aluminum alloy heat dissipation substrate: Internally milled to form a spiral channel with a cross-section of 2mm × 2mm; Thermally conductive insulating layer: AlN ceramic substrate with a thermal conductivity of 180 W / mK; Quick connector: The inlet and outlet use G1 / 4 threaded interfaces, supporting a flow rate of 6L / min; Temperature monitoring: NTC thermistors are buried near the MOSFETs of H1 and H2.

[0038] The heat sink is mounted in close proximity to the MOSFET and diode. The coolant is a 50% ethylene glycol aqueous solution. At an inlet temperature of 25°C, the chip junction temperature is <85°C under a 10kW full load condition (ambient temperature 40°C).

[0039] The control module enables soft switching across the entire load range. ZVS implementation: By adjusting the dead time (0.5-2μs), the body diode is ensured to be turned on before the MOSFET is turned on; ZCS implementation: Turn off the secondary-side SiC diode at the zero-crossing point of the resonant current to eliminate reverse recovery loss; Frequency control: The switching frequency fs is automatically adjusted according to the load change, ranging from 85-115kHz, maintaining fs / fr=0.9-1.1 (fr is the resonant frequency).

[0040] At full load, fs = 100kHz, dead time 1.2μs; at light load, fs increases to 115kHz, dead time decreases to 0.5μs. Actual measured switching losses are reduced by 60% (compared to hard switching).

[0041] It also includes an integrated magnetic module: Three-column magnetic core: the primary winding is wound on the middle column, and the secondary windings are wound on the two side columns; leakage inductance utilization: by adjusting the distance between the primary and secondary windings, the leakage inductance is controlled to 20μH and used as the resonant inductance Lr; air gap optimization: a 0.5mm air gap is opened on the middle column to make the magnetizing inductance Lm=320μH.

[0042] The magnetic core is made of TDK PC95 material, with 24 turns on the primary side and 48 turns on the secondary side. The integrated magnetic component is 40% smaller in volume than the discrete solution, and the power density reaches 3.2kW / L.

[0043] in Figure 2 Medium: Mode switching threshold: Automatic trigger when voltage difference > 50V; Control cycle: 10μs (implemented by DSP interrupt); in Figure 3 Its configuration features are: Full parallel Cathode shorted by D1-D6 48V / 300A Hybrid D1-D2 are connected in series with T1 200V / 100A D3-D6 bridges T2 Fully Serial D1→D2→D3→D4→D5→D6 800V / 25A in Figure 4 middle: ┌─────────────────┐ │ MOSFET Module │ │ (Thermal grease layer) │ ├─────────────────┤ │ AlN ceramic substrate │ → Thermal resistance 0.05℃ / W ├─────────────────┤ │ Microchannel waterway │ → Cross-section 2x2mm │ ~~~~~~~~~~~~~ │ └─────────────────┘ in Figure 5 Key points of the waveform: ZVS evidence: Vds = 0V before Vgs rises; ZCS evidence: The diode turns off when the current crosses zero.

[0044] The parameter table for multi-mode control is as follows: The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A series resonant DC-DC converter, characterized in that: include: First / second voltage regulator capacitors (C1, C2): connected to the DC input / output terminals; First / Second Converter (H1, H2): Both are full-bridge circuits composed of four MOSFETs. C1 is connected in parallel on the DC side of H1, and C2 is connected in parallel on the DC side of H2. Resonant network: includes resonant inductor Lr, resonant capacitor Cr, and transformer T1. The primary windings of Lr, Cr, and T1 are connected in series between the AC sides of H1 and H2. Control module: Outputs four PWM signals to the gate drivers of H1 and H2, with an adjustable phase difference range of 0-180°; Interleaved parallel extension unit: Second group of resonant network: resonant inductor Lr2, resonant capacitor Cr2 and transformer T2 are connected in parallel with the first group to form a dual-channel power path.

2. The series resonant DC-DC converter according to claim 1, characterized in that: The control module has bidirectional power flow management functionality: When energy flows from C1 to C2, H1 operates in inverter mode and H2 operates in rectifier mode. When energy flows from C2 to C1, H2 operates in active rectification mode, and H1 operates in synchronous rectification mode. Mode switching is automatically triggered by the DSP detecting the polarity of the port voltage.

3. The series resonant DC-DC converter according to claim 1, characterized in that: The resonant network adopts an interleaved parallel structure: The secondary sides of the two transformers (T1, T2) are connected through a full-bridge rectifier unit; The rectifier unit comprises six bridge arms D1-D6, which can be configured as follows: Full parallel mode: D1-D6 output terminals are connected in parallel, supporting low voltage and high current 48V / 300A; Hybrid mode: The secondary side of T1 is connected in series and then in parallel with the secondary side of T2, supporting medium voltage and medium current of 200V / 100A; Full series mode: T1 and T2 secondary sides are connected in series, supporting high voltage and low current 800V / 25A.

4. The series resonant DC-DC converter according to claim 1, characterized in that: It also includes a microchannel cooling system: Aluminum alloy heat dissipation substrate: Internally milled to form a spiral channel with a cross-section of 2mm × 2mm; Thermally conductive insulating layer: AlN ceramic substrate with a thermal conductivity of 180 W / mK; Quick connector: The inlet and outlet use G1 / 4 threaded interfaces, supporting a flow rate of 6L / min; Temperature monitoring: NTC thermistors are buried near the MOSFETs of H1 and H2.

5. A series resonant DC-DC converter according to claim 1, characterized in that: The control module enables soft switching across the entire load range. ZVS implementation: By adjusting the dead time to 0.5-2μs, the body diode is ensured to be on before the MOSFET is turned on; ZCS implementation: Turn off the secondary-side SiC diode at the zero-crossing point of the resonant current to eliminate reverse recovery loss; Frequency control: The switching frequency fs is automatically adjusted according to the load change, ranging from 85-115kHz, maintaining fs / fr=0.9-1.1, where fr is the resonant frequency.

6. A series resonant DC-DC converter according to any one of claims 1-5, characterized in that: It also includes an integrated magnetic module: Three-column magnetic core: the primary winding is wound on the middle column, and the secondary windings are wound on the two side columns; Leakage inductance utilization: By adjusting the spacing between the primary and secondary windings, the leakage inductance is controlled to 20μH and used as the resonant inductance Lr; Air gap optimization: A 0.5mm air gap is opened in the middle column to make the excitation inductance Lm=320μH.

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