Voltage spike absorption circuit and fire-fighting power supply

Abstract

The utility model relates to the technical field of power electronics, in particular to a voltage spike absorption circuit and a fire-fighting power supply, which are reasonable in structure, safe and reliable, and capable of improving the quality and operation stability of a power supply product, and is characterized by being provided with a power absorption resistor, a damping resistor, an absorption capacitor and a clamping diode, compared with the prior art, the power supply has the remarkable advantages that the structure is reasonable, the safety and the reliability are realized, the quality and the operation stability of a power supply product can be improved, and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power electronics, specifically a voltage peak absorption circuit and fire-fighting power supply which are reasonable in structure, safe and reliable, and can improve the quality of power supply products and the operational stability. BACKGROUND

[0002] With the development of life technology, people's requirements for safe life are higher and higher, and more and more fire emergency products are applied in life. The circuits in fire emergency products often use BOOST and BUCK circuits. In the process of rapid switching of the power tube in the circuit, voltage spikes often occur at the DS end of the power tube. If the spikes are not handled properly, it will cause increased line loss and power tube breakdown damage. In order to solve this problem, a conventional application is to connect an RC absorption circuit with a resistor and a capacitor in series at the DS end of the power MOSFET. However, the absorption effect of this circuit is poor, the power of the absorption resistor is very large, which causes the temperature to be very high sometimes during operation, and the temperature of the absorption resistor will affect the driving and temperature rise of the power tube when the layout is drawn. SUMMARY

[0003] The utility model discloses a circuit structure simple, low in cost and simple to control voltage peak absorption circuit and fire-fighting power supply are provided to solve the defects and insufficient of prior art.

[0004] The utility model discloses a circuit structure simple, low in cost and simple to control voltage peak absorption circuit and fire-fighting power supply are provided to solve the defects and insufficient of prior art.

[0005] A voltage peak absorption circuit is characterized in that it is provided with a power absorption resistor, a damping resistor, an absorption capacitor and a clamping diode. The damping resistor and the absorption capacitor are connected in series and then connected in parallel with the power absorption resistor, and then connected to the cathode of the clamping diode.

[0006] The anode of the clamping diode is connected to a node where the energy storage inductor and the power tube MOSFET are connected, and the node where the damping resistor and the absorption capacitor are connected in series and then connected in parallel with the power absorption resistor is connected to the other end of the energy storage inductor, that is, the voltage peak absorption circuit is connected in parallel with the power inductor.

[0007] The power absorption resistor adopts two or more resistors in series or parallel connection, the multiple resistors in series or parallel connection can share power loss, and the temperature of the single resistor is prevented from being too high due to concentrated heat dissipation.

[0008] The damping resistor is realized by two or more resistors in parallel or series connection, and further, the absorption capacitor is realized by two or more capacitors in parallel or series connection. The scheme can reduce voltage / current stress: damping resistor in series connection: in a high-voltage scene, multiple resistors in series connection can share voltage, and the risk of breakdown caused by insufficient voltage resistance of a single resistor is avoided. For example, in the BOOST boost circuit of the fire power supply, if the peak voltage reaches several hundred volts, the series connection of the resistors can evenly distribute the voltage pressure, and the absorption capacitor is in parallel connection: multiple capacitors in parallel connection can reduce the equivalent series resistance (ESR) and the equivalent series inductance (ESL), improve the high-frequency peak absorption efficiency, and reduce residual oscillation. The fault tolerance capability can be improved, and when the capacitors are in parallel connection, if a single capacitor is short-circuited and fails, other capacitors can still work; when the resistors are in parallel connection, the open circuit of a single resistor does not affect the overall function, and the system robustness is enhanced. At the same time, the layout and parasitic parameters can be optimized, and multiple small-size resistors / capacitors in dispersed arrangement can reduce parasitic inductance (such as pin inductance), which is especially suitable for high-frequency switching scenes (such as MHz-level switching frequency of the BUCK circuit), and the absorption effect is prevented from being deteriorated due to parasitic parameters.

[0009] The utility model further provides a kind of fire power supply, there is BOOST boost circuit and BUCK step-down circuit, and the BOOST boost circuit or BUCK step-down circuit is equipped with power inductor and power tube

[0010] MOSFET, characterized by being equipped with the voltage peak absorption circuit as described above, and the voltage peak absorption circuit is in parallel connection with power inductor.

[0011] This invention controls the peak voltage of the power transistor using a clamping diode during operation, and dissipates the peak energy through a series resistor and capacitor. Compared with a snubber circuit connected in parallel to the power transistor's drain and source terminals, this circuit can more effectively reduce peak voltage for the same power device. Furthermore, the snubber circuit can be placed below the inductor, further reducing the PCB area and improving PCB utilization. Traditional RC snubber circuits are directly connected in parallel to the power transistor's drain and source terminals (e.g., between the drain and source terminals of a MOSFET), requiring close proximity to the power transistor to shorten traces. However, a heat dissipation area or drive signal isolation area is usually required around the power transistor, preventing the snubber circuit from being placed below the inductor. This design connects the snubber circuit in parallel with the power inductor, rather than directly to the power transistor's drain and source terminals. Inductors typically occupy a large area and are relatively low in height on a PCB (e.g., flat wire-wound inductors), making the space below them difficult to utilize. This design, through circuit topology adjustment, allows the snubber circuit to be placed directly below the inductor, fully utilizing the PCB's vertical space and reducing the overall area.

[0012] Compared with the prior art, this utility model has significant advantages such as reasonable structure, safety and reliability, and the ability to improve the quality and operational stability of power supply products. Attached image description:

[0013] Appendix Figure 1 This is a schematic diagram of the circuit principle of Embodiment 1 of this utility model.

[0014] Figure labels: 1. Voltage spike absorption circuit; 2. Battery; 3. Emergency load; 4. Emergency power supply. Detailed implementation method:

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Example 1:

[0017] This example provides a voltage spike absorption circuit, as shown in the attached diagram. Figure 1 As shown, a voltage spike absorption circuit is provided, comprising a power absorption resistor (R1 and R2), a damping resistor R3, an absorption capacitor C5, and a clamping diode D3. The damping resistor R3 and the absorption capacitor C5 are connected in series and then in parallel with the power absorption resistor, and then connected to the cathode of the clamping diode D3. The anode of the clamping diode D3 is connected to the node where the energy storage inductor L1 and the power transistor Q2 are connected. The node where the damping resistor R3 and the absorption capacitor C5 are connected in series and in parallel with the power absorption resistor is connected to the other end of the energy storage inductor L1. That is, the voltage spike absorption circuit 1 is connected in parallel with the power inductor L1.

[0018] In the example, the power absorption resistor is realized by two resistors in series, that is, R1 and R2 are connected in series. In this scheme, multiple resistors in series or parallel can share the power loss, avoiding the temperature of a single resistor being too high due to concentrated heat dissipation. For example, when two resistors are connected in parallel, the current borne by each resistor is halved, and the power loss is reduced to 1 / 4 of the original, significantly reducing the heat generation and improving the system reliability. In a high-temperature environment (such as a fire power supply scene), multiple resistors in a dispersed layout can dissipate heat with the help of PCB copper foil, reducing the interference of local temperature rise on power tube driving; redundant design improves reliability, and if a single resistor fails (such as open circuit), other resistors in the parallel structure can still maintain partial absorption function, avoiding the complete loss of circuit protection, meeting the stringent requirements of fire equipment on reliability; flexible adaptation to parameter requirements, through series / parallel combination, the equivalent resistance value can be flexibly adjusted. For example, two identical resistors in parallel can achieve a halved resistance value, adapting to the peak absorption requirements of different power levels and reducing the cost of customized devices.

[0019] When the voltage peak absorption circuit in the example is applied to a fire power supply, as shown in the accompanying drawings, Figure 1 The fire power supply is provided with a BOOST boost circuit and a BUCK step-down circuit, and the BOOST boost circuit or the BUCK step-down circuit is provided with a power inductor and a power tube MOSFET, characterized in that the voltage peak absorption circuit is provided, and the voltage peak absorption circuit is connected in parallel with the power inductor; in operation, the peak voltage of the power tube is controlled by the clamping diode D3, and the peak energy is consumed by the damping resistor and the absorption capacitor connected in series, compared with the scheme of connecting the absorption circuit in parallel to the DS end of the power tube, the circuit can more effectively reduce the peak voltage under the condition of the same power device; at the same time, the absorption circuit can be arranged below the inductor, which can more effectively reduce the circuit board area and improve the utilization rate of the PCB.

[0020] Compared with the prior art, the utility model has the advantages of reasonable structure, safety and reliability, and can improve the power product quality and operation stability.

Claims

1. A voltage spike absorption circuit, characterized in that, It is equipped with a power absorption resistor, a damping resistor, an absorption capacitor, and a clamping diode. The damping resistor and the absorption capacitor are connected in series, then connected in parallel with the power absorption resistor, and finally connected to the cathode of the clamping diode.

2. The voltage spike absorption circuit according to claim 1, characterized in that, The anode of the clamping diode is connected to the node where the energy storage inductor and the power MOSFET are connected. The node where the damping resistor and the absorption capacitor are connected in series and in parallel with the power absorption resistor is connected to the other end of the energy storage inductor. That is, the voltage spike absorption circuit is connected in parallel with the power inductor.

3. The voltage spike absorption circuit according to claim 1, characterized in that, The power absorption resistor is made up of two or more resistors connected in series or in parallel.

4. A voltage spike absorption circuit according to claim 1, characterized in that, The damping resistor is achieved by connecting two or more resistors in parallel or in series.

5. A voltage spike absorption circuit according to claim 1, characterized in that, The absorption capacitor is implemented by connecting two or more capacitors in parallel or in series.

6. A fire-fighting power supply, comprising a BOOST boost circuit and a BUCK buck circuit, wherein the BOOST boost circuit or the BUCK buck circuit comprises a power inductor and a power MOSFET, characterized in that, The circuit includes a voltage spike absorption circuit as described in any one of claims 1-5, wherein the voltage spike absorption circuit is connected in parallel with a power inductor.

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