Active protection circuit suitable for SSPC power loop

Abstract

The invention belongs to the technical field of aviation power distribution systems, and discloses an active protection circuit suitable for an SSPC power loop. A TVS (Transient Voltage Suppressor) and a diode are additionally arranged between a grid electrode and a drain electrode of an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), the TVS is broken down when instantaneous high voltage comes, so that the voltage is gradually applied to the grid electrode of the MOSFET, and the MOSFET is gradually turned on through charge accumulation; the diode plays a role in conducting when the TVS is broken down and plays a role in reverse prevention when the driving voltage arrives. By means of the design, the requirement for power during TVS model selection can be reduced, the TVS with the small size can be selected, and circuit refinement, miniaturization and high-safety design are achieved.

Description

Technical Field

[0001] The present invention relates to an aviation power distribution system, and belongs to the technical field of power distribution systems and power distribution products, and in particular to an active protection circuit suitable for an SSPC power circuit. Background Art

[0002] Advanced aircraft are developing towards multi-electric and full-electric. With the development of science and technology and the continuous improvement of demand, the number of electrical equipment is gradually increasing, and the number of aircraft power distribution products is also increasing. The aircraft's requirements for power distribution safety are also increasing. The power distribution channels of power distribution products need to add safer protection measures. The classification of power distribution equipment requires that the power distribution channels have high safety.

[0003] SSPC stands for Solid State Power Control. As an aircraft power distribution product, its good safety can effectively improve the safety of aircraft power distribution. There are many distribution channels in the aircraft, and power is distributed to the aircraft load through the distribution channels. When a transient high voltage appears in the distribution channel, there is a possibility that the power device will be broken down, which will make the current distribution channel unavailable.

[0004] In order to improve the safety of the power distribution channel, each power distribution channel is designed for protection so that it can perform necessary suppression when high voltage comes and protect the power devices from damage caused by high voltage shock. Usually, the protection of power devices is passive protection, that is, using high-power TVS devices at both ends of the power channel MOSFET, which is large in size and not economical. Therefore, a power device active protection circuit design suitable for SSPC is proposed to solve the above technical problems. Summary of the invention

[0005] The present invention provides an active protection circuit for a SSPC power loop, which can realize the function of actively discharging instantaneous high voltage and prevent MOSFET from being broken down and damaged.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An active protection circuit suitable for an SSPC power loop comprises: a MOSFET, a TVS tube and a diode are connected in parallel between the gate and drain of the MOSFET, when the SSPC is disconnected and there is an instantaneous high voltage at the power input end, or when a high voltage is generated at the moment when the SSPC short-circuit protection is turned off, the MOSFET is turned on to discharge the instantaneous high voltage through the source and gate of the MOSFET, so as to avoid the high voltage from breaking down and damaging the MOSFET, thereby actively protecting the MOSFET.

[0008] As a further technical solution of the present invention, when there is no instantaneous high voltage at the power input end, the on and off of the MOSFET is controlled by the driving voltage; when there is an instantaneous high voltage at the power input end and it is in the off state, the MOSFET can be actively turned on and off.

[0009] As a further technical solution of the present invention, the TVS tube is broken down when a high voltage is applied, so that the voltage is gradually applied to the source to accumulate charge at the gate of the MOSFET, turning on the MOSFET to discharge the high voltage.

[0010] As a further technical solution of the present invention, the diode plays a conducting role when the TVS tube is broken down, and plays an anti-reverse role when the driving voltage arrives, so as to ensure that the MOSFET can be turned on or off in time.

[0011] As a further technical solution of the present invention, a resistor is added to the gate input terminal of the MOSFET, which is used to limit the current of the MOSFET gate.

[0012] As a further technical solution of the present invention, the MOSFET channel type should be N-channel.

[0013] As a further technical solution of the present invention, the breakdown voltage of the TVS tube should be smaller than the breakdown voltage of the MOSFET.

[0014] As a further technical solution of the present invention, the reverse voltage of the diode should be greater than the driving voltage.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. By connecting a TVS in parallel between the gate and drain of the MOSFET, when there is an instantaneous high voltage at the input end, the MOSFET can be actively turned on to discharge the instantaneous high voltage, thereby preventing the MOSFET from being damaged by the instantaneous high voltage and protecting the MOSFET.

[0017] 2. This design realizes active protection while reducing the power requirement when selecting TVS devices. It can use smaller surface-mount TVS, and realize miniaturization of design selection while ensuring safety, thereby improving power density and economy.

[0018] 3. This design circuit not only ensures that electrical equipment is protected from the influence of high voltage, but also can suppress the influence of high voltage caused by rapid shutdown of the power circuit. It effectively improves the safety of the power distribution channel, and at the same time has the advantages of miniaturization and low cost in device selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0020] Figure 1 The present invention is an active protection circuit diagram of a power device suitable for SSPC. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0022] See also Figure 1 The present invention proposes an active protection circuit suitable for SSPC power circuit. The main function is to turn on the MOSFET when there is instantaneous high voltage at the power input end when the SSPC is disconnected, or when high voltage is generated at the moment when the SSPC short-circuit protection is turned off, so as to discharge the instantaneous high voltage through the drain and source of the MOSFET to avoid the high voltage from breaking down the MOSFET and damaging it, and actively protect the MOSFET. The key to its design is to add a TVS and a diode between the gate and drain of the MOSFET, wherein the function of the TVS tube is to be broken down when the instantaneous high voltage arrives, so that the voltage is gradually applied to the gate of the MOSFET, and the MOSFET is gradually turned on through charge accumulation. The function of the diode is to conduct when the TVS is broken down, and to prevent reverse when the driving voltage arrives. This design can reduce the power requirements when selecting TVS, and can select a smaller TVS, which can achieve circuit refinement, miniaturization, and high-safety design.

[0023] By connecting a TVS tube and a diode in parallel between the gate and drain of the MOSFET, the MOSFET can be protected from the transient high voltage that occurs when the MOSFET is quickly turned off.

[0024] This circuit has an instantaneous high voltage protection function. When an instantaneous high voltage comes, it can turn on the MOSFET, that is, turn on the drain and source to discharge the high voltage, prevent the MOSFET from being broken down, and protect the MOSFET. When there is no instantaneous high voltage at the power input end, the circuit controls the on and off of the MOSFET through the driving voltage. When there is an instantaneous high voltage at the power input end and it is in the off state, it can actively turn on and off the MOSFET.

[0025] A suitable TVS tube is connected in parallel between the gate and drain of the MOSFET. The TVS tube is broken down when a high voltage is applied, so that the voltage is gradually applied to the source to accumulate charge at the gate of the MOSFET and turn on the MOSFET to discharge the high voltage. A diode is added between the gate and drain of the MOSFET. The role of the diode is to conduct when the TVS is broken down, and to prevent reverse when the driving voltage is applied, so as to ensure that the MOSFET can be turned on or off in time. A resistor is added to the gate input of the MOSFET. The role of the resistor is to limit the current of the MOSFET gate.

[0026] The MOSFET channel type should be N-channel.

[0027] The breakdown voltage of a suitable TVS tube should be smaller than the breakdown voltage of the MOSFET.

[0028] The reverse voltage of the diode should be greater than the driving voltage.

[0029] like Figure 1 In the circuit diagram, MOSFET Q1 is used as a power switch. When the voltage difference between pin 1 and pin 3 of Q1 is greater than the turn-on voltage of Q1, pin 2 and pin 3 of Q1 will gradually turn on, so that the input voltage Vin passes through Q1 and supplies power to load 1 as Vout_1.

[0030] Under normal circumstances, when the driving voltage Vdrv_1 is greater than the turn-on voltage of Q1, Q1 is normally turned on. When the driving voltage Vdrv_1 is less than the turn-on voltage of Q1, Q1 is normally turned off.

[0031] When MOSFET Q1 is in the off state, when an instantaneous high voltage appears at the input voltage Vin, the TVS tube V2 will be broken down, and the high voltage will be applied to pin 1 of Q1 through diode V1 and current limiting resistor R1, and charge will begin to accumulate, causing a voltage difference between pin 1 and pin 3 of Q1. When the voltage difference between pin 1 and pin 3 of Q1 is greater than the turn-on voltage of Q1, Q1 will be turned on and the instantaneous high voltage Vin will be discharged to prevent MOSFET Q1 from being broken down, thereby protecting Q1.

[0032] In the figure, pin 2 of Q1 is connected to the power input Vin and the reverse cutoff end of TVS V2, the other end of TVS V2 is connected to the forward conduction end of diode V1, the other end of diode V1 is connected to the driving voltage and one end of resistor R1, the other end of resistor R1 is connected to pin 1 of Q1, and pin 3 of Q1 is connected to the ground GND_1 of driving voltage Vdrv_1 and the power supply input end of load 1, and the output ground of load 1 is PGND.

[0033] Similarly, the active protection connection method of the power part of SSPC2…SSPCn is the same as that of SSPC1.

[0034] So far, the purpose of the present invention has been achieved.

[0035] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An active protection circuit suitable for SSPC power circuit, characterized in that , including: MOSFET, a TVS tube and a diode are connected in parallel between the gate and drain of the MOSFET. When the SSPC is disconnected and there is an instantaneous high voltage at the power input end, or when the SSPC short-circuit protection is turned off and a high voltage is generated at the moment, the MOSFET is turned on to discharge the instantaneous high voltage through the source and gate of the MOSFET to avoid the high voltage from breaking down and damaging the MOSFET, thereby actively protecting the MOSFET.

2. The active protection circuit suitable for SSPC power circuit according to claim 1, characterized in that: When there is no instantaneous high voltage at the power input end, the on and off of the MOSFET is controlled by the driving voltage; when there is an instantaneous high voltage at the power input end and it is in the off state, the MOSFET can be actively turned on and off.

3. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: The TVS tube is broken down when a high voltage is applied, so that the voltage is gradually applied to the source to accumulate charge at the gate of the MOSFET, turning on the MOSFET to discharge the high voltage.

4. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: The diode plays a conducting role when the TVS tube is broken down, and plays an anti-reverse role when the driving voltage arrives, so as to ensure that the MOSFET can be turned on or off in time.

5. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: A resistor is added to the gate input terminal of the MOSFET, which is used to limit the current of the MOSFET gate.

6. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: The MOSFET channel type should be N-channel.

7. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: The breakdown voltage of the TVS tube should be smaller than the breakdown voltage of the MOSFET.

8. The active protection circuit suitable for SSPC power circuit according to claim 2, characterized in that: The reverse voltage of the diode should be greater than the driving voltage.

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