An isolated dc-dc conversion unit

Abstract

The utility model discloses an isolation type DC-DC conversion unit, including power unit, gate drive unit, PWM unit, heat dissipation unit, PWM unit is connected with gate drive unit, and gate drive unit is connected with power unit, and heat dissipation unit is connected with power unit, power unit includes input filter unit, DC-DC unit, resonance unit, rectifier unit, output filter unit that connect in proper order. Can between input power supply and output alternating current power supply electrical isolation, effectively protect electronic equipment from input power supply interference and surge voltage, avoid the noise in input power supply and interference signal transmission to load circuit, when system failure, limit the spread range of failure, improve the flexibility of system, applicability, reliability.

Description

Technical Field

[0001] This utility model relates to a switching power supply, and more particularly to an isolated DC-DC converter unit. Background Technology

[0002] While non-isolated power supply systems offer some design and cost advantages, they also present potential hazards and risks. In many applications, such as medical equipment, rail transportation, and industrial automation, electrical isolation ensures the safety of operators and equipment, preventing current leakage and ground faults. Researching isolated DC-DC converters can improve the electrical safety and reliability of systems, especially in high-voltage and high-power environments. Lack of isolation can lead to current returning directly to ground in the event of a device failure, increasing the risk of electric shock.

[0003] Non-isolated power supply systems are prone to electromagnetic interference, affecting system stability and performance. Because there is no isolation between the input and output, load changes can cause voltage fluctuations between the source and load, leading to signal interference. Non-isolated power supply systems may also have lower conversion efficiency than isolated power supplies, resulting in increased energy loss and greater complexity in heat dissipation design.

[0004] In non-isolated designs, the direct connection between input and output circuits allows faults to propagate rapidly throughout the system, affecting multiple connected devices and potentially causing serious consequences in critical applications such as healthcare and transportation. Due to safety and performance concerns, the use of non-isolated power supplies is limited in high-voltage applications, impacting system flexibility and applicability.

[0005] In view of the above, this utility model is hereby proposed. Utility Model Content

[0006] The purpose of this invention is to provide an isolated DC-DC converter unit to solve the aforementioned technical problems in the prior art.

[0007] The objective of this utility model is achieved through the following technical solution:

[0008] The isolated DC-DC converter unit of this utility model includes a power unit, a gate drive unit, a PWM unit, and a heat dissipation unit;

[0009] The PWM unit is connected to the gate driving unit, the gate driving unit is connected to the power unit, and the heat dissipation unit is connected to the power unit.

[0010] The power unit includes an input filter unit, a DC-DC unit, a resonant unit, a rectifier unit, and an output filter unit connected in sequence.

[0011] Compared with the prior art, the isolated DC-DC converter unit provided by this utility model can electrically isolate the input power supply and the output AC power supply, 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 the system fails, thereby improving the system's flexibility, applicability and reliability, and solving the problems existing in the prior art. Attached Figure Description

[0012] Figure 1 A block diagram of an isolated DC-DC converter unit provided in an embodiment of this utility model;

[0013] Figure 2 for Figure 1 Schematic diagram of the circuit topology of the medium power unit;

[0014] Figure 3 for Figure 1 Block diagram of the gate drive unit;

[0015] Figure 4 for Figure 1 Block diagram of the PWM unit. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments, which do not constitute a limitation on the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0017] First, the following explanations are provided for the terms that may be used in this article:

[0018] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0019] The terms “including,” “contains,” “comprising,” “having,” or other similar semantic descriptions shall be interpreted as non-exclusive inclusion.

[0020] The contents not described in detail in the embodiments of this utility model are existing technologies known to those skilled in the art. Where specific conditions are not specified in the embodiments of this utility model, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Reagents or instruments used in the embodiments of this utility model whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] The isolated DC-DC converter unit of this invention includes a power unit, a gate drive unit, a PWM unit, and a heat dissipation unit;

[0022] The PWM unit is connected to the gate driving unit, the gate driving unit is connected to the power unit, and the heat dissipation unit is connected to the power unit.

[0023] The power unit includes an input filter unit, a DC-DC unit, a resonant unit, a rectifier unit, and an output filter unit connected in sequence.

[0024] The DC-DC unit includes switching transistors M1 to M4 and an isolation transformer T1. The drains of switching transistors M1 and M3 are connected to the positive terminal of the input filter unit. The drain of switching transistor M2 is connected to the source of switching transistor M1 and pin 1 of the isolation transformer T1. The drain of switching transistor M4 is connected to the source of switching transistor M3 and pin 2 of the isolation transformer T1. The sources of switching transistors M2 and M4 are connected to the negative terminal of the input filter unit.

[0025] Pin 3 of the isolation transformer T1 is connected to the resonant unit, pin 4 of the isolation transformer T1 is connected to the rectifier unit, the resonant unit is connected to the rectifier unit, and the rectifier unit is also connected to the output filter unit.

[0026] The gate driving unit includes gate drivers US1~US4 and auxiliary power units U1~U4;

[0027] The gate driver US1 is connected to the gate of the auxiliary power unit U1 and the gate of the switching transistor M1, the gate driver US2 is connected to the gate of the auxiliary power unit U2 and the gate of the switching transistor M2, the gate driver US3 is connected to the gate of the auxiliary power unit U3 and the gate of the switching transistor M3, and the gate driver US4 is connected to the gate of the auxiliary power unit U4 and the gate of the switching transistor M4.

[0028] The gate drivers US1 to US4 are selected from KA103 silicon carbide MOS driver chips.

[0029] The PWM unit includes a PWM control unit, an auxiliary power unit, over-temperature protection, input over-voltage protection, and output over-voltage and over-current protection units, and is connected to an alarm indicator light.

[0030] 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.

[0031] The PWM control unit uses the EG1611 control chip.

[0032] In summary, the isolated DC-DC converter unit of this utility model embodiment electrically isolates the input power supply and the output AC power supply, effectively protecting electronic equipment from input power supply interference and surge voltage, preventing noise and interference signals in the input power supply from being transmitted to the load circuit, and limiting the propagation range of the fault when a system fault occurs. Through quasi-resonant soft-switching technology, zero-current turn-on and turn-off of the switching transistor are achieved, reducing the losses caused by switching, reducing the transformer size, improving efficiency, and reducing costs.

[0033] To more clearly demonstrate the technical solution and effects provided by this utility model, the following detailed description of the embodiments of this utility model is provided with reference to specific examples.

[0034] Design concept:

[0035] The isolated DC-DC converter unit adopts a vertical multi-layer layout, saving space and electrically isolating the input and output AC power supplies. This effectively protects electronic equipment from input power interference and surge voltage, preventing noise and interference signals from the input power supply from being transmitted to the load circuit. Furthermore, it limits the propagation range of faults in the event of a system failure, improving system flexibility, applicability, and reliability. Utilizing fully domestically produced components, it features overcurrent, overvoltage, and overtemperature protection. Through quasi-resonant soft-switching technology, it achieves zero-current turn-on and turn-off of the switching transistors, reducing losses from switching and allowing for a smaller transformer size, improved efficiency, and lower costs.

[0036] Example 1

[0037] Reference Figures 1 to 4 As shown:

[0038] Reference Figure 1 As shown, the isolated DC-DC converter unit is divided into four parts: a power unit, a gate drive unit, a PWM unit, and a heat dissipation unit. It converts the input DC voltage of 360V~380V into an isolated DC output of 360V~380V through a DC-DC converter.

[0039] Reference Figure 2 As shown, the main circuit topology of the power unit adopts a full-bridge quasi-resonant soft-switching full-bridge circuit. Silicon carbide MOSFETs are selected for the full-bridge circuit, which feature excellent high-temperature characteristics, excellent high-frequency characteristics, fast switching speed, low conduction loss, small size, and light weight, supporting DC high-voltage input of 360V~380V. After transformer isolation, an LC quasi-resonant circuit is used, ensuring that the power MOSFETs operate in zero-current (ZCS) turn-on and turn-off modes in each PWM cycle. This reduces the heat generation of the switching transistors, minimizes switching losses, reduces transformer size, improves efficiency, lowers costs, and reduces the heat dissipation burden.

[0040] The resonant unit consists of an L and a C in series, and the resonant frequency is given by the formula:

[0041] L includes the leakage inductance of the transformer. The inductance and capacitance values ​​are calculated according to the formula. A ferrite core with high permeability is selected for the inductor, and excitation wire is wound around it to reduce heat generation. A high-voltage, high-frequency resonant capacitor is selected for the capacitor.

[0042] The back-end rectifier unit uses silicon carbide diodes to build a rectifier bridge, which rectifies the AC output from the transformer to output a stable DC high voltage of 360V~380V.

[0043] Reference Figure 3 As shown, the gate driver unit amplifies the PWM waveform output from the push-pull quasi-resonant control chip in the PWM unit, driving the silicon carbide MOSFET to turn on and off. The maximum operating frequency is 300kHz, the maximum output current is 30A, and the maximum drive charge is 30µA. It can drive MOSFETs in high-power circuits and features soft-turn-off protection with adjustable protection parameters to prevent the MOSFET from burning out due to excessive current. The gate driver has a negative voltage distributor that can adjust to a negative voltage when driving the MOSFET to turn off, improving the circuit's response speed and enabling soft start and soft shutdown, thereby improving circuit stability and reliability. The gate driver input power supply voltage can be between 18V and 22V. The MOSFET drive voltage is selected based on the MOSFET gate drive voltage parameters: -4V / +18V. The auxiliary power unit of the gate driver unit isolates and converts the external 24V DC auxiliary power input to 22V DC for power supply.

[0044] Reference Figure 4 As shown, the PWM unit uses a push-pull quasi-resonant control chip, powered by a 5V DC voltage generated by the auxiliary power unit. It features input undervoltage and overvoltage shutdown, overtemperature and overcurrent shutdown protection, and can output two push-pull mode 40K-100KHz PWM signals. The chip's PWM output frequency is set to 90kHz with a 50% duty cycle and a dead time of 500ns by adjusting the potentiometer. Voltage, current, and temperature feedback can be processed in real time. The chip's voltage feedback uses a shallow closed-loop voltage regulation mode, which can limit the maximum voltage and prevent excessive voltage under no-load conditions from burning out the MOSFET.

[0045] The isolated DC-DC converter unit adopts a vertical multi-layer layout. The heat dissipation unit uses an aluminum substrate, placing the power transistors that generate significant heat on the bottom plate, while some peripheral circuits, gate drive units, PWM units, etc. are placed on the upper layer, which reduces the size of the isolated DC-DC converter unit.

[0046] Compared with the prior art, this utility model 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, 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 the system fails. Through quasi-resonant soft-switching technology, the switching transistor can be turned on and off with zero current, which reduces the losses caused by switching, can reduce the size of the transformer, improve efficiency, and reduce costs.

[0047] The above description is merely a preferred embodiment of this utility model, but the scope of protection of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this utility model should be included within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of this utility model and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. An isolated DC-DC conversion unit, characterized by, Includes a power unit, a gate drive unit, a PWM unit, and a heat dissipation unit; The PWM unit is connected to the gate driving unit, the gate driving unit is connected to the power unit, and the heat dissipation unit is connected to the power unit. The power unit includes an input filter unit, a DC-DC unit, a resonant unit, a rectifier unit, and an output filter unit connected in sequence.

2. The isolated DC-DC conversion cell of claim 1, wherein, The DC-DC unit includes switching transistors M1 to M4 and an isolation transformer T1. The drains of switching transistors M1 and M3 are connected to the positive terminal of the input filter unit. The drain of switching transistor M2 is connected to the source of switching transistor M1 and pin 1 of the isolation transformer T1. The drain of switching transistor M4 is connected to the source of switching transistor M3 and pin 2 of the isolation transformer T1. The sources of switching transistors M2 and M4 are connected to the negative terminal of the input filter unit.

3. The isolated DC-DC conversion cell of claim 2, wherein, Pin 3 of the isolation transformer T1 is connected to the resonant unit, pin 4 of the isolation transformer T1 is connected to the rectifier unit, the resonant unit is connected to the rectifier unit, and the rectifier unit is also connected to the output filter unit.

4. The isolated DC-DC converter unit according to claim 3, characterized in that, The gate drive unit includes gate drivers US1~US4 and auxiliary power units U1~U4.

5. The isolated DC-DC conversion cell of claim 4, wherein, The gate driver US1 is connected to the gate of the auxiliary power unit U1 and the gate of the switching transistor M1, the gate driver US2 is connected to the gate of the auxiliary power unit U2 and the gate of the switching transistor M2, the gate driver US3 is connected to the gate of the auxiliary power unit U3 and the gate of the switching transistor M3, and the gate driver US4 is connected to the gate of the auxiliary power unit U4 and the gate of the switching transistor M4.

6. The isolated DC-DC conversion cell of claim 5, wherein, The gate drivers US1 to US4 are selected from KA103 silicon carbide MOS driver chips.

7. The isolated DC-DC converter unit according to claim 6, characterized in that, The PWM unit includes a PWM control unit, an auxiliary power unit, over-temperature protection, input over-voltage protection, and output over-voltage and over-current protection units, and is connected to an alarm indicator light.

8. The isolated DC-DC conversion cell of claim 7, wherein, 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.

9. The isolated DC-DC conversion cell of claim 8, wherein, The PWM control unit uses the EG1611 control chip.

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