A contactless soft start DC power supply switch device for suppressing inrush current

Abstract

A kind of contactless soft-start DC power supply switch device of inhibiting impact current, including metal shielding shell, input terminal group, output load terminal group, power PCB assembly, magnetic ring fixed slot;The inside of the metal shielding shell is separated into power cavity and control cavity by metal isolation partition;The inside of the power cavity is arranged MOS array contactless switch main circuit, transient energy discharge loop;The control cavity is arranged RC slow start drive module;The input terminal group, output load terminal group are fixed at the both ends of shell respectively, and the magnetic ring fixed slot of each group of terminal outlet position is integrally formed, and common mode suppression magnetic ring is clamped in the slot;The power PCB assembly adopts layered copper structure, and is divided into power ground layer and signal ground layer, and two layers of ground layer are connected by single point star, and power wiring is thick and coarse, large cross-sectional area design, reduce loop distribution inductance;Solve the problem that impact current peak of equipment switching, inductive load on-off is excessive in GJB151B standard CE107 power line conducted emission test.

Description

Technical Field

[0001] This invention relates to a contactless soft-start DC power supply switch device for suppressing inrush current, belonging to the field of electromagnetic compatibility technology of power supplies. Background Technology

[0002] 1) Explanation of the pain points of CE107 testing: GJB151B CE107 assesses transient inrush currents conducted on equipment power lines. The assessment includes three scenarios: equipment power-on and closing, disconnection of inductive loads such as relays / solenoid valves, and power-off and tripping of the entire unit. Traditional military equipment commonly uses mechanical electromagnetic contactors as power switches, which have inherent defects and are highly susceptible to exceeding CE107 limits.

[0003] 2) Defects in the structure of existing traditional mechanical contactors: a) Large surge current upon closing: The contactor contacts directly connect to the input bus, and the large-capacity electrolytic capacitor at the back end is charged instantly, forming a charging surge current with extremely high amplitude and steep rise edge. The peak value of the surge current far exceeds the CE107 limit. b) High-energy spikes generated by the interrupted arc: When the mechanical contacts disconnect the inductive load circuit, the magnetic field energy stored in the inductor is released instantaneously, generating a kilovolt-level reverse voltage, which excites a large-scale transient impact current, which is conducted and coupled along the power line, causing the CE107 time-domain waveform to seriously exceed the standard. c) Contact wear and degradation suppression effect: After repeated switching, the contact is burned, the contact resistance increases, the circuit distributed inductance increases, the LC resonance amplifies the impact oscillation, and the EMC performance of the equipment degrades after long-term use. d) No slow start control capability: Mechanical contactors conduct instantaneously at full voltage, which cannot control the voltage rise slope, cannot smoothly suppress dI / dt, and cannot reduce inrush current from the source; e) Poor layout of supporting discrete absorption devices: The existing rectification plan only hangs RC absorption and TVS tubes outside the contactor. The device leads are long and the distributed inductance is large. The transient spikes are not discharged in time and the impact suppression effect is limited.

[0004] 3) Existing soft-boot solutions are insufficient: A small number of active soft starter modules on the market only suppress power-on surges and do not integrate a load disconnection energy discharge structure; moreover, they are installed separately from mechanical contactors, resulting in messy overall wiring, excessively long power circuit leads that introduce additional inductance, and cannot simultaneously solve the two types of CE107 inrush current problems of power-on closing and load disconnection. They have low integration and are cumbersome to assemble. Summary of the Invention

[0005] The present invention aims to solve the technical problem of excessive surge current peaks generated during equipment power-on / off and inductive load switching in the GJB151B standard CE107 power line conducted emission test.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A contactless soft-start DC power switch device for suppressing inrush current includes a metal shielding housing, an input terminal block, an output load terminal block, a power PCB assembly, and a magnetic ring fixing slot. The interior of the metal shielding housing is divided into a power cavity and a control cavity by a metal partition. The power cavity is equipped with a MOS array contactless switch main circuit and a transient energy discharge circuit. The control cavity is equipped with an RC soft-start drive module; The input terminal block group and the output load terminal block group are respectively fixed to both ends of the housing. Each terminal block has an integrally formed magnetic ring fixing slot at the wire outlet position, and a common mode suppression magnetic ring is installed in the slot. The power PCB assembly adopts a layered copper-paved structure, which is divided into a power ground layer and a signal ground layer. The two ground layers are connected in a single-point star configuration. The power traces are short, thick, and have a large cross-sectional area to reduce the distributed inductance of the loop.

[0007] The beneficial technical effects of adopting the above technical solution are: a) This invention eliminates mechanical contact arcs at the source: it adopts a MOS array contactless structure, and there is no arc during the entire process of closing and opening, which completely eliminates the large-scale impact current generated by the arc and solves the core problem of excessive peak breaking speed of CE107.

[0008] b) This invention's gradient soft-start suppresses power-on surges: It integrates an RC passive soft-start drive, which controls the voltage rise rate, smooths the bus capacitor charging process, and significantly reduces the peak value of the instantaneous inrush current during power-on, making it compatible with the power-on test conditions of GJB151B CE107.

[0009] c) The integrated discharge circuit of this invention integrates TVS, freewheeling diode and RC damping network inside the device. It has short leads and small distributed inductance, which can quickly absorb the reverse impact energy of inductive load. Compared with external discrete absorption devices, the suppression effect is improved by more than 60%.

[0010] d) The present invention uses shielding and PCB structure optimization to suppress coupling interference: built-in metal isolation partition, outgoing magnetic ring slot, and layered single-point grounding structure reduce the distributed inductance of the power circuit, suppress the spatial coupling of the inrush current and LC resonance oscillation, and use multiple means to ensure the stability of the CE107 index.

[0011] e) This invention has a long service life and stable performance: there is no mechanical contact wear, the impact suppression performance does not decrease under high and low temperature and repeated start-stop conditions, no need for later rectification and maintenance, and it is suitable for the long-term reliable use requirements of military equipment.

[0012] f) This invention has a high degree of integration and is easy to assemble: the switch, soft start, EMC absorption and shielding structure are integrated into one piece, the wiring of the whole machine is simple, the workload of EMC rectification of the whole machine is reduced, and the production and debugging costs of equipment are reduced. Attached Figure Description

[0013] Figure 1 This is a block diagram illustrating the principle of the contactless soft-start DC power supply switching device for suppressing inrush current according to the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0015] A contactless soft-start DC power switch device for suppressing inrush current includes a metal shielding housing, an input terminal block, an output load terminal block, a power PCB assembly, and a magnetic ring fixing slot. The interior of the metal shielding housing is divided into a power cavity and a control cavity by a metal partition. The power cavity is equipped with a MOS array contactless switch main circuit and a transient energy discharge circuit. The control cavity is equipped with an RC soft-start drive module; The input terminal block group and the output load terminal block group are respectively fixed to both ends of the housing. Each terminal block has an integrally formed magnetic ring fixing slot at the wire outlet position, and a common mode suppression magnetic ring is installed in the slot. The power PCB assembly adopts a layered copper-paved structure, which is divided into a power ground layer and a signal ground layer. The two ground layers are connected in a single-point star configuration. The power traces are short, thick, and have a large cross-sectional area to reduce the distributed inductance of the loop.

[0016] The main circuit of the MOS array contactless switch consists of multiple N-channel power MOS transistors connected in parallel to form a MOS array, replacing the traditional mechanical contactor contacts. The input terminal of the MOS array is connected to the positive input terminal, and the output terminal is connected to the back-end bus capacitor and the inductive load. The parallel connection of multiple MOS transistors reduces the conduction loss of a single transistor and improves the current carrying capacity. The gates of all MOS transistors are uniformly connected to the output terminal of the RC soft-start drive module.

[0017] The RC soft-start drive module is located in an independent control cavity and consists of a voltage divider resistor, a time-delay charging capacitor, and a voltage-regulating clamping diode.

[0018] When the device is powered on, the input voltage slowly charges the delay capacitor through the voltage divider resistor. The capacitor voltage gradually raises the gate potential of the MOSFET, controlling the MOSFET to conduct slowly with a gradient. The bus voltage rises smoothly, significantly reducing the slope of the capacitor charging current rise, dI / dt, and reducing the peak power-on inrush current. The Zener clamp diode limits the maximum gate voltage to prevent the MOSFET from being damaged by overvoltage.

[0019] The transient energy discharge circuit is connected in parallel at the output terminal (load side) of the MOS array and is composed of a bidirectional TVS transient suppression diode, a low-resistance freewheeling diode, and a damping RC network.

[0020] When the equipment is powered off or the inductive load is disconnected, the inductor releases reverse high-voltage surge energy, which can be quickly freed through the freewheeling diode, the TVS clamps the instantaneous high voltage on the bus, and the RC damping network absorbs the oscillation energy, suppressing the reverse surge current from being conducted outward along the power line and eliminating the CE107 breaking spike.

[0021] The metal isolation partition separates the power circuit from the control drive circuit, blocks the spatial coupling of the electromagnetic field generated by the inrush current, and prevents the drive circuit from being disturbed, which could lead to the MOSFET being falsely triggered.

[0022] The terminal wires of the magnetic ring fixing slot pass through the magnetic ring, suppressing the conduction of common-mode impulse current in the power line; the slot and the housing are integrally formed, eliminating the need for additional brackets and shortening the lead length.

[0023] The power PCB assembly features a layered ground structure: power ground and signal ground are physically separated and connected at only one point to avoid the formation of a circulating current in the ground plane and reduce common-mode interference; the power loop trace width is ≥3mm to shorten the trace length, reduce distributed inductance, and prevent LC resonance amplification of the inrush current.

[0024] Working process of this invention: 1) Power-on and closing stage A 28V DC power supply is connected to the input terminal, and the voltage is sent to the RC slow-start drive module. The delay capacitor charges slowly, the gate voltage of the MOS array gradually increases, and the MOS transistor slowly turns on. The large-capacity electrolytic capacitor on the back-end bus charges smoothly with a low slope, without instantaneous large current surges. The amplitude of the power-on inrush current is greatly reduced, meeting the CE107 power-on operating condition limit. After the capacitor is fully charged and the MOS is fully turned on, the device operates in steady state with low conduction loss.

[0025] 2) Load disconnection / system power failure phase When the device power supply is disconnected, the MOS array is turned off, and the inductive loads such as the downstream relays and solenoid valves generate a reverse induced electromotive force; the transient energy discharge circuit starts synchronously, the freewheeling diode provides a discharge path for the inductor, the TVS clamps the instantaneous high voltage, the RC network dampens the oscillating current, and the high-energy impact energy is absorbed on the spot and will not be conducted outward along the input power line, thus eliminating the CE107 breaking spike.

[0026] 3) Long-term cyclical operation There are no mechanical contact points for opening and closing throughout the process, so no electric arc will be generated; there is no contact wear problem, and the performance of the slow start and discharge structure does not degrade after repeated start and stop. It can stably suppress inrush current in both high and low temperature environments.

[0027] Embodiments of the present invention CE107 Testing Procedures for 28V / 10A Military DC Power Switching Device: a) The metal shielding shell is made of die-cast aluminum alloy, and the internal metal partition divides the cavity into two parts; b) The MOS array uses four 100V / 30A N-channel MOS transistors connected in parallel; c) RC soft-start drive module: 10kΩ voltage divider resistor, 1μF delay capacitor, 12V Zener diode clamping voltage; d) Transient energy discharge circuit: bidirectional TVS with a withstand voltage of 36V, the freewheeling diode is a fast recovery diode, and the RC damping network is a 10Ω resistor paired with a 0.1μF capacitor; e) Input and output terminals are integrated with magnetic ring slots for mounting manganese-zinc common-mode magnetic rings; f) The PCB power trace width is 4mm, and the power ground and signal ground are laid separately with single-point connection.

[0028] Innovation of this invention a) Contactless MOS arrays replace mechanical contactors; b) Cavity partition shielding structure; c) Terminal integrated magnetic ring slot; d) Layered single-point grounding PCB structure; e) RC soft start + built-in discharge composite suppression structure.

[0029] This invention is adapted for 28V airborne applications and addresses the issue of excessive inrush current in GJB151B CE107 standards by designing a contactless soft-start DC power switch. The device uses a parallel MOS array to replace the mechanical contactor to eliminate arcing, and a metal partition within the housing separates the power and control chambers. An integrated RC soft-start circuit smoothly suppresses power-on surges, and a built-in discharge circuit composed of a TVS diode, freewheeling diode, and RC damper quickly absorbs high-voltage spikes from inductive loads. The device is equipped with an integrated magnetic ring slot terminal, and the PCB uses layered copper plating with single-point grounding to reduce distributed inductance. Multiple structures work together to suppress conducted interference. This invention features high integration, zero contact loss during switching, and stable EMC performance over long-term operation. It meets the CE107 testing requirements for military DC control boxes, contactors, and other equipment, significantly simplifying the overall electromagnetic compatibility rectification work.

Claims

1. A contactless soft-start DC power supply switch device for suppressing inrush current, characterized in that: It includes a metal shielding housing, input terminal blocks, output load terminal blocks, power PCB assembly, and magnetic ring fixing slot; The interior of the metal shielding housing is divided into a power cavity and a control cavity by a metal partition. The power cavity is equipped with a MOS array contactless switch main circuit and a transient energy discharge circuit. The control cavity is equipped with an RC soft-start drive module; The input terminal block group and the output load terminal block group are respectively fixed to both ends of the housing. Each terminal outlet position is integrally formed with a magnetic ring fixing slot, and a common mode suppression magnetic ring is installed in the slot. The power PCB assembly adopts a layered copper-paved structure, which is divided into a power ground layer and a signal ground layer. The two ground layers are connected in a single-point star configuration. The power traces are short, thick, and have a large cross-sectional area to reduce the distributed inductance of the loop.

2. The contactless soft-start DC power switch device for suppressing inrush current according to claim 1, characterized in that: The main circuit of the MOS array contactless switch consists of multiple N-channel power MOS transistors connected in parallel to form a MOS array, replacing the traditional mechanical contactor contacts. The input terminal of the MOS array is connected to the positive input terminal, and the output terminal is connected to the back-end bus capacitor and the inductive load. The parallel connection of multiple MOS transistors reduces the conduction loss of a single transistor and improves the current carrying capacity. The gates of all MOS transistors are uniformly connected to the output terminal of the RC soft-start drive module.

3. The contactless soft-start DC power supply switch for suppressing inrush current according to claim 1, characterized in that: The RC soft-start drive module is located in an independent control cavity and consists of a voltage divider resistor, a time-delay charging capacitor, and a voltage-regulating clamping diode.

4. The contactless soft-start DC power switch device for suppressing inrush current according to claim 1, characterized in that: The transient energy discharge circuit is connected in parallel to the load side of the MOS array output terminal and is composed of a bidirectional TVS transient suppression diode, a low-resistance freewheeling diode, and a damping RC network.

5. The contactless soft-start DC power supply switch for suppressing inrush current according to claim 1, characterized in that: The metal isolation partition separates the power circuit from the control drive circuit, blocks the spatial coupling of the electromagnetic field generated by the inrush current, and prevents the drive circuit from being disturbed, which could lead to the MOSFET being falsely triggered.

6. The contactless soft-start DC power switch device for suppressing inrush current according to claim 1, characterized in that: The terminal wires of the magnetic ring fixing slot pass through the magnetic ring, suppressing the conduction of common-mode impulse current in the power line; the slot and the housing are integrally formed, eliminating the need for additional brackets and shortening the lead length.

7. The contactless soft-start DC power supply switch device for suppressing inrush current according to claim 1, characterized in that: The power PCB assembly features a layered copper-paved structure: power ground and signal ground are physically separated and connected at only one point to avoid the formation of a circulating current in the ground plane and reduce common-mode interference; the power loop trace width is ≥3mm to shorten the trace length, reduce distributed inductance, and prevent LC resonance amplification of the inrush current.

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