High-power-density isolation DC / DC conversion circuit

Abstract

The invention discloses a high-power-density isolation DC / DC conversion circuit which comprises a power unit, a grid driving unit, a PWM control unit and a heat dissipation unit. The power unit comprises an input filtering unit, a full-bridge conversion unit composed of four switching tubes, an isolation transformer, a resonance unit, a rectification unit composed of four diodes, and an output filtering unit. The four drivers and the four auxiliary power units of the gate driving unit complete driving waveforms; the PWM control unit has over-temperature, input overvoltage, output overvoltage and overcurrent protection functions and is connected with an alarm indicating lamp, and the heat dissipation unit is connected with the power unit. 1: 1 high-power isolated output can be realized, electronic equipment can be effectively protected from interference of an input power supply and surge voltage, noise and interference signals in the input power supply are prevented from being transmitted to a load circuit, zero-current on-off of a switching tube is realized, loss caused by switching of a switch is reduced, the size of a transformer can be reduced, efficiency is improved, and cost is reduced.

Description

Technical Field

[0001] The present invention relates to a DC / DC conversion circuit, which is an important technology focused on improving the efficiency and reliability of a power electronic system, and in particular to a high power density isolated DC / DC conversion circuit. Background Art

[0002] High power density isolated DC / DC conversion circuit refers to the high power density, high efficiency, high stability and high reliability of the converter at high power levels by optimizing the design of circuit topology, control strategy and heat dissipation technology. This field is crucial for applications such as aerospace power systems, electric vehicles, solar inverters, and data center power supplies, because these applications often require power systems to be efficient, compact and reliable.

[0003] High power density isolated DC / DC conversion circuit technology is widely used in aerospace power systems, electric vehicles, solar inverters, data center power supplies and other fields. With the popularization of new energy vehicles, the rapid development of data centers and the continuous advancement of aerospace technology, the demand for high power density isolated DC / DC converters in these fields continues to grow. At the same time, with the rise of emerging technologies such as smart manufacturing and the Internet of Things, the demand for efficient, compact and reliable power systems will continue to increase. Through technological innovation and industrial upgrading, the continuous development of high power density isolated DC / DC conversion circuit technology can be promoted, providing strong support for new energy, smart manufacturing and other fields.

[0004] It is difficult for products in the prior art to meet the above requirements.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a high power density isolated DC / DC conversion circuit to solve the above technical problems existing in the prior art.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The high power density isolated DC / DC conversion circuit of the present invention comprises a power unit, a gate drive unit, a PWM control unit and a heat dissipation unit:

[0009] The power unit includes an input filter unit, a full-bridge conversion unit composed of four switch tubes M1 to M4, an isolation transformer T1, a resonance unit, a rectification unit composed of four diodes, and an output filter unit.

[0010] Compared with the prior art, the high power density isolated DC / DC conversion circuit provided by the present invention electrically isolates the input power supply and the output AC power supply, which can effectively protect electronic equipment from input power supply interference and surge voltage, avoid the noise and interference signals in the input power supply from being transmitted to the load circuit, and limit the propagation range of the fault when a system fault occurs; through the quasi-resonant soft switching technology, the zero current turning on and off of the switch tube is achieved, the loss caused by the switch switching is reduced, the size of the transformer can be reduced, the efficiency is improved, and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a principle block diagram of the high power density isolated DC / DC conversion circuit of the present invention;

[0012] Figure 2 for Figure 1 Schematic diagram of the circuit topology of the medium power unit;

[0013] Figure 3 for Figure 1 Principle block diagram of the gate drive unit;

[0014] Figure 4 for Figure 1 Principle block diagram of PWM unit. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0016] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] First, the terms that may be used in this article are explained as follows:

[0018] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0019] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0020] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0021] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0022] The high power density isolated DC / DC conversion circuit of the present invention comprises a power unit, a gate drive unit, a PWM control unit and a heat dissipation unit:

[0023] The power unit includes an input filter unit, a full-bridge conversion unit composed of four switch tubes M1 to M4, an isolation transformer T1, a resonance unit, a rectification unit composed of four diodes, and an output filter unit.

[0024] The driving waveform is completed through the four drivers US1 to US4 of the gate driving unit and the four auxiliary power units U1 to U4;

[0025] The PWM control unit has over-temperature, input over-voltage, output over-voltage, and over-current protection functions, and is connected to an alarm indicator light. The heat dissipation unit is connected to the power unit.

[0026] According to the gate driving unit and the PWM control unit, the switch tubes M1 to M4 are adjusted to realize the function of isolated voltage stabilization output.

[0027] By controlling the switch tubes M1 to M4, the function of isolated and voltage-regulated output is realized.

[0028] This circuit realizes 1:1 high power isolated output.

[0029] In the present invention:

[0030] The switch tubes M1 to M4 mainly include silicon carbide MOS tubes, model YJD212060NCTGH; the drain electrodes of the switch tubes M1 and M3 are both connected to the positive electrode of the input filter unit, the drain electrode of the switch tube M2 is respectively connected to the source electrode of the switch tube M1 and the pin 1 of the isolation transformer T1, the drain electrode of the switch tube M4 is respectively connected to the source electrode of the switch tube M3 and the pin 2 of the isolation transformer T1, and the source electrodes of the switch tubes M2 and M4 are connected to the negative electrode of the input filter unit;

[0031] The 3rd pin of the isolation transformer T1 is connected to the resonance unit, the 4th pin of the isolation transformer T1 is connected to the rectification unit, the resonance unit is connected to the rectification unit, and the rectification unit is also connected to the output filter unit;

[0032] The gate drive unit includes gate drivers US1-US4 and auxiliary power units U1-U4, wherein the gate driver US1 is connected to the auxiliary power unit U1 and the gate of the switch tube M1 respectively, the gate driver US2 is connected to the auxiliary power unit U2 and the gate of the switch tube M2 respectively, the gate driver US3 is connected to the auxiliary power unit U3 and the gate of the switch tube M3 respectively, and the gate driver US4 is connected to the auxiliary power unit U4 and the gate of the switch tube M4 respectively;

[0033] The gate drivers US1-US4 use KA103 silicon carbide MOS driver chips;

[0034] The PWM unit includes a PWM control unit, an auxiliary power unit, an over-temperature, input over-voltage and output over-voltage, and an over-current protection unit, and is connected to an alarm indicator light; the PWM control unit is connected to the auxiliary power unit, the PWMH pin of the PWM control unit is connected to the gate drivers US1 and US4, and the PWML pin is connected to the gate drivers US2 and US3;

[0035] The PWM control unit uses the EG1611 control chip;

[0036] The heat dissipation unit is connected to the power unit.

[0037] Compared with the prior art, the high power density isolated DC / DC conversion circuit provided by the present invention solves the following difficulties:

[0038] The ability to electrically isolate the input power supply from the output AC power supply can effectively protect electronic equipment from input power supply interference and surge voltage, prevent noise and interference signals in the input power supply from being transmitted to the load circuit, and limit the propagation range of the fault when a system fault occurs, thereby improving the flexibility, applicability and reliability of the system.

[0039] The high power density isolated DC / DC conversion circuit of the present invention isolates an input DC voltage of 360 to 380V through DC-DC conversion to output a DC voltage of 360 to 380V.

[0040] The main circuit diagram of the power unit adopts a full-bridge quasi-resonant soft-switching full-bridge circuit. The full-bridge MOS tube uses a silicon carbide MOS tube, which supports a high-voltage input of 360V to 380V DC. After transformer isolation, LC quasi-resonance is adopted, and the power MOS tube works in zero current (ZCS) start and shut down mode in each PWM cycle.

[0041] The resonant unit is composed of L and C in series resonance, and the resonant frequency is based on the formula:

[0042] Where L includes the leakage inductance of the transformer. Calculate the inductance and capacitance values ​​according to the formula. For the inductance, choose a ferrite core with high magnetic permeability and wrap it around the excitation wire to reduce heat generation. For the capacitor, choose a high-voltage and high-frequency resonant capacitor.

[0043] The back-end rectifier unit uses silicon carbide diodes to build a rectifier bridge to rectify the AC output of the transformer and output a stable DC high voltage of 360V to 380V.

[0044] The gate drive unit amplifies the PWM waveform output by the push-pull quasi-resonant control chip in the PMW unit, and drives the silicon carbide MOS tube to turn on and off. The maximum operating frequency can reach 300KHz, the maximum output current is 30A, and the maximum drive charge is 30u. It can drive the MOS tube in the larger power circuit, has a soft shutdown protection function, and can adjust the protection parameters to prevent the MOS tube from burning due to excessive current flowing through it. The gate driver is equipped with a negative voltage distributor, which can be adjusted to a negative voltage when the MOS is turned off, thereby improving the response speed of the circuit, realizing the soft start and soft shutdown of the power supply, and thus improving the stability and reliability of the circuit. The gate driver input power supply voltage can be between 18 and 22V. The MOS tube drive voltage is selected according to the MOS tube gate drive voltage parameters: -4 / +18V, and the auxiliary power unit of the gate drive unit isolates and transforms the external DC 24V auxiliary power input into DC 22V to provide power supply.

[0045] The PMW unit uses a push-pull quasi-resonant control chip, which is powered by a 5V DC voltage generated by an auxiliary power unit. It has input undervoltage and overvoltage shutdown, overtemperature and overcurrent shutdown protection functions, and can output two push-pull mode 40K-100KHz PWM signals. By adjusting the potentiometer, the chip PWM output frequency is set to 90kHz, 50% duty cycle output, and the dead time is 500nS. The voltage, current, and temperature feedback can be processed in real time. The chip voltage feedback adopts a shallow closed-loop voltage regulation mode, which can achieve the highest voltage limit and prevent the phenomenon of burning the MOS tube due to excessive voltage when no-load.

[0046] The isolated DC-DC conversion unit adopts a vertical multi-layer layout. The heat dissipation unit adopts an aluminum substrate. The power tube devices with severe heat generation are placed on the bottom plate, and some peripheral circuits, gate drive units, PWM units, etc. are placed on the upper layer, which reduces the size of the isolated DC-DC conversion unit.

[0047] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0048] Example 1

[0049] like Figure 1 , 2 , 3, 4 as shown:

[0050] Reference Figure 1 As shown, the isolated DC-DC conversion unit is divided into four parts: a power unit, a gate drive unit, a PWM unit, and a heat dissipation unit, which converts the input DC 360-380V voltage into an isolated DC 360-380V output voltage through DC-DC conversion.

[0051] Reference Figure 2 As shown in the figure, the main circuit diagram of the power unit adopts a full-bridge quasi-resonant soft-switching full-bridge circuit. Among them, the full-bridge MOS tube selects silicon carbide MOS tube, which has the characteristics of excellent high-temperature characteristics, excellent high-frequency characteristics, fast switching speed, small conduction loss, small size, and light weight, and supports high-voltage input of DC 360V~380V. After transformer isolation, LC quasi-resonance is adopted, and the power MOS tube works in zero current (ZCS) start-up and shutdown mode in each PWM cycle, which reduces the heat generation of the switch tube, reduces the switch loss of the MOS tube, and can reduce the size of the transformer, improve efficiency, reduce costs, and reduce the heat dissipation burden.

[0052] The resonant unit is composed of L and C in series resonance, and the resonant frequency is based on the formula:

[0053] Where L includes the leakage inductance of the transformer. Calculate the inductance and capacitance values ​​according to the formula. For the inductance, choose a ferrite core with high magnetic permeability and wrap it around the excitation wire to reduce heat generation. For the capacitor, choose a high-voltage and high-frequency resonant capacitor.

[0054] The back-end rectifier unit uses silicon carbide diodes to build a rectifier bridge to rectify the AC output of the transformer and output a stable DC high voltage of 360V to 380V.

[0055] Reference Figure 3As shown, the gate drive unit amplifies the PWM waveform output by the push-pull quasi-resonant control chip in the PMW unit, drives the silicon carbide MOS tube to turn on and off, and the maximum operating frequency can reach 300KHz, the maximum output current is 30A, and the maximum drive charge is 30u. It can drive the MOS tube in the larger power circuit, has a soft shutdown protection function, and can adjust the protection parameters to prevent the MOS tube from burning due to excessive current flowing through it. The gate driver is equipped with a negative voltage distributor, which can be adjusted to a negative voltage when the MOS is turned off, thereby improving the response speed of the circuit, realizing the soft start and soft shutdown of the power supply, and thus improving the stability and reliability of the circuit. The gate driver input power supply voltage can be between 18 and 22V. The MOS tube drive voltage is selected according to the MOS tube gate drive voltage parameters: -4 / +18V, and the auxiliary power unit of the gate drive unit isolates and transforms the external DC 24V auxiliary power input into DC 22V to provide power supply.

[0056] Reference Figure 4 As shown, the PMW unit adopts a push-pull quasi-resonant control chip, which is powered by a DC 5V voltage generated by an auxiliary power unit. It has input undervoltage and overvoltage shutdown, overtemperature and overcurrent shutdown protection functions, and can output two push-pull mode 40K-100KHz PWM signals. By adjusting the potentiometer, the chip PWM output frequency is set to 90kHz, 50% duty cycle output, and the dead time is 500nS. The voltage, current, and temperature feedback can be processed in real time. The chip voltage feedback adopts a shallow closed-loop voltage regulation mode, which can achieve the highest voltage limit and prevent the phenomenon of burning the MOS tube due to excessive voltage when no-load.

[0057] The isolated DC-DC conversion unit adopts a vertical multi-layer layout. The heat dissipation unit adopts an aluminum substrate. The power tube devices with severe heat generation are placed on the bottom plate, and some peripheral circuits, gate drive units, PWM units, etc. are placed on the upper layer, which reduces the size of the isolated DC-DC conversion unit.

[0058] The beneficial effects of the present invention are as follows: compared with the prior art, the isolated DC-DC conversion unit provided electrically isolates the input power supply and the output AC power supply, which can effectively protect the electronic equipment from input power supply interference and surge voltage, avoid the noise and interference signals in the input power supply from being transmitted to the load circuit, and at the same time limit the propagation range of the fault when a system fault occurs; through the quasi-resonant soft switching technology, the zero-current turning on and off of the switch tube is achieved, the loss caused by the switch switching is reduced, the size of the transformer can be reduced, the efficiency is improved, and the cost is reduced.

[0059] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A high power density isolated DC / DC conversion circuit, characterized in that: Including power unit, gate drive unit, PWM control unit and heat dissipation unit: The power unit comprises an input filtering unit, a full-bridge conversion unit composed of four switch tubes (M1-M4), an isolation transformer T1, a resonance unit, a rectification unit composed of four diodes, and an output filtering unit.

2. The high power density isolated DC / DC conversion circuit according to claim 1, characterized in that: The driving waveform is completed through the 4 drivers (US1~US4) of the gate driving unit and the 4 auxiliary power units (U1~U4); The PWM control unit has over-temperature, input over-voltage, output over-voltage, and over-current protection functions, and is connected to an alarm indicator light. The heat dissipation unit is connected to the power unit.

3. The high power density isolated DC / DC conversion circuit according to claim 2, characterized in that: According to the gate driving unit and the PWM control unit, the switch tubes M1 to M4 are adjusted to realize the function of isolated voltage stabilization output.

4. The high power density isolated DC / DC conversion circuit according to claim 3, characterized in that: By controlling the switch tubes M1 to M4, the function of isolated and voltage-regulated output is realized.

5. The high power density isolated DC / DC converter circuit according to any one of claims 1 to 4, characterized in that: This circuit realizes 1:1 high power isolated output.

Images