Solid-state constant-current extensible high-power soft starting device and extension device thereof

Abstract

The utility model discloses a solid-state constant-current extensible high-power soft starting device and an extension device thereof. The soft starting device comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a triode V2, a diode D1, an NMOSFET tube Q1, a first capacitor C1, a second capacitor C2 and a plurality of charging capacitors. Wherein the first resistor R1 and the second resistor R2 are connected in series between the positive electrode and the negative electrode of a power supply, the connection point of the two is connected with the collector of the triode V2 through the first capacitor C1 and the third resistor R3 which are connected in parallel, and the emitter is connected with the negative electrode of the power supply through the diode D1; the connection point is further connected with the grid electrode of the NMOSFET Q1, the source electrode of the NMOSFET Q1 is connected with the base electrode of the triode V2 and connected with the negative electrode of the power supply through the fourth resistor R4, the second capacitor C2 is located between the grid electrode and the negative electrode of the power supply, and the charging capacitors are connected between the positive electrode and the drain electrode of the power supply in parallel. According to the utility model, the surge during startup can be suppressed, and the surge generated when the load power is greatly changed can be suppressed in real time.

Description

Technical Field

[0001] The utility model belongs to the field of electronic technology, and in particular relates to a solid-state constant-current expandable high-power soft starting device and an expansion device thereof. Background Art

[0002] For high-power power supplies, since there is a large capacitor at the input end, the current of the capacitor charging needs to be limited during startup, otherwise it will cause a great impact on the front-end power supply system. There have been a lot of studies on surge suppression methods. From the perspective of surge response methods, they can be divided into two categories: preventing surge generation and preventing surge damage. Soft start at startup is an effective way to prevent surge generation.

[0003] Commonly used soft start circuits are generally the following three types: thermistor soft start circuit, the advantages of this circuit: simple circuit, high reliability, disadvantages: limited applicability, especially high power and temperature adaptability; relay soft start circuit, advantages: good soft start effect, can effectively prevent power-on shock, disadvantages: complex circuit, high cost, when the relay is closed, arc interference may occur, affecting the life of the relay; solid semiconductor soft start circuits often use P-channel MOSFET, but the inherent properties of P-channel MOSFET are not suitable for controlling high power and high voltage occasions.

[0004] Commonly used soft start circuits usually only reduce the instantaneous inrush current at startup, but cannot control the size of the starting current. When the load changes, the starting current also changes and even generates surges, which does not provide surge protection. The device has poor versatility and is usually not scalable. N-channel MOSFET soft start circuits are suitable for controlling high power and high voltage occasions and have simple circuits, small size, low cost, high reliability, and thorough surge suppression. Utility Model Content

[0005] In order to solve the technical problems existing in the prior art, the utility model provides a solid-state constant current expandable high-power soft start device and its expansion device, which solves the problem that the commonly used soft start circuit cannot control the size of the starting current and the starting current also changes when the load changes and even generates a surge.

[0006] The technical solutions adopted by the utility model to solve the above technical problems are as follows:

[0007] A solid-state constant current expandable high-power soft start device, the device comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a transistor V2, a diode D1, an NMOSFET tube Q1, a first capacitor C1, a second capacitor C2 and a plurality of charging capacitors;

[0008] Among them, the first resistor R1 and the second resistor R2 are connected in series between the positive and negative electrodes of the power supply, the connection point of the first resistor R1 and the second resistor R2 is connected to the collector of the transistor V2 through the first capacitor C1 and the third resistor R3 connected in parallel, and the emitter of the transistor V2 is connected to the negative electrode of the power supply through the diode D1; the connection point of the first resistor R1 and the second resistor R2 is also connected to the gate of the NMOSFET tube Q1, the source of the NMOSFET tube Q1 is connected to the base of the transistor V2 and is connected to the negative electrode of the power supply through the fourth resistor R4, the second capacitor C2 is located between the gate of the NMOSFET tube Q1 and the negative electrode of the power supply, and a plurality of charging capacitors are connected in parallel between the positive electrode of the power supply and the drain of the NMOSFET tube Q1.

[0009] Furthermore, the device also includes another diode, the positive and negative electrodes of the diode are respectively connected to the source and drain of the NMOSFET tube Q1.

[0010] A soft start expansion device comprises a plurality of the above-mentioned solid-state constant current expandable high-power soft start devices, wherein the plurality of the above-mentioned solid-state constant current expandable high-power soft start devices are connected in parallel at both ends of a power supply.

[0011] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0012] 1. Real-time performance: It can not only suppress the surge at startup, but also suppress the surge caused by large changes in load power in real time;

[0013] 2. Fast constant current: PID negative feedback amplifier circuit realizes sampling and amplification closed-loop fast constant current control to prevent surge;

[0014] 3. Full solid-state: The switch device uses solid-state semiconductor devices, which are small in size, small in interference, and easy to control;

[0015] 4. Scalability: It can be used in multiple channels in parallel and have multiple channels with equal current, strong applicability and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the principle diagram of the solid-state constant current soft start device capable of expanding high power of the utility model;

[0017] Figure 2 The utility model is a schematic diagram of a solid-state constant current soft start device capable of expanding high power. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each implementation method of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0019] The utility model provides a solid-state constant current expandable high-power soft start device, which is suitable for current surge suppression during the startup process of large-capacity capacitors. The device adopts solid semiconductor switching devices, realizes constant current control through PID control, realizes the startup soft start function, effectively suppresses startup surge impact, and can be expanded in parallel to control the startup soft start of high-power circuits.

[0020] like Figure 1 As shown, the circuit is mainly composed of a sampling circuit, a PID control negative feedback amplifier circuit, a solid-state constant current control switch circuit and a reference circuit. Multiple circuits can be connected in parallel to achieve power expansion function. The sampling circuit samples the current flowing through the switch circuit and converts the current signal into a voltage signal; the negative feedback amplifier circuit uses the fixed voltage drop of the PN junction of the semiconductor device to form a voltage reference signal; the difference between the sampled voltage signal and the voltage reference signal is used as the input of the amplifier circuit. If the difference is greater than zero, the amplifier circuit will have current, which will reduce the gate-source voltage of the switch tube, and realize constant current under the comprehensive control of the negative feedback and PID circuits until the charging is completed.

[0021] The constant current is calculated according to the following formula:

[0022]

[0023] Where I is the constant current, U is the reference voltage amplitude, and R is the sampling resistor value. The constant current control current can be changed by changing the value of R.

[0024] The selection of power switch tube mainly considers its withstand voltage and power consumption. The power consumption calculation formula is as follows:

[0025] P=(UU L )*I (2)

[0026] Where U is the input voltage, UL is the load voltage, and I is the constant current. If the load is a large capacitive load, UL is zero when the power is turned on and the current I is uncontrolled, so the switch tube consumes a lot of power at the moment of power on, which is the main reason for the damage to the startup MOSFET.

[0027] In some embodiments, the sampling circuit converts the current signal into a voltage signal through the precision sampling resistor R4; the negative feedback PID amplifier circuit, resistors R1-R4, transistor V2, diode D1, NMOSFET tube Q1, capacitors C1 and C2 form a negative feedback amplifier circuit, a differential circuit, and an integral circuit, wherein the differential circuit improves the circuit response sensitivity, and the integral circuit suppresses oscillation to ensure the stability of the amplifier circuit; the reference circuit uses the transistor V2 and the diode PN junction D1 to fix the voltage drop to realize the voltage reference circuit function.

[0028] The current signal is converted into a voltage signal through a precision sampling resistor and input into the subsequent negative feedback PID amplifier circuit. The size of the circuit startup charging current can be changed by changing the size of the resistor to achieve a constant current charging effect, effectively suppressing the startup surge caused by the short circuit caused by the large load capacitance at the moment of startup, thus realizing the soft start function.

[0029] The negative feedback PID amplifier circuit is composed of an amplifier circuit (resistors R1-R4, transistor V2, diode D1), a power adjustment circuit (NMOSFET and V1), a differential capacitor C1, and an integral capacitor C2. The negative feedback PID amplifier circuit processes the voltage signal of the sampling resistor R4 to form a stable and fast negative feedback closed-loop control network.

[0030] like Figure 2 As shown, a solid-state constant current soft start device capable of expanding high power includes:

[0031] The sampling circuit converts the current signal into a voltage signal through the precision sampling resistor R4.

[0032] Negative feedback PID amplifier circuit, resistors R1-R4, transistor V2, diode D1, NMOSFET Q1, capacitors C1 and C2 form a negative feedback amplifier circuit, a differential circuit, and an integral circuit, wherein the differential circuit improves the circuit response sensitivity, and the integral circuit suppresses oscillation to ensure the stability of the amplifier circuit; a solid semiconductor device NMOSFET is used as a soft start switch to control the current main loop.

[0033] The voltage reference circuit uses the fixed voltage drop of the PN junction of the transistor and the diode to realize the voltage reference function.

[0034] In addition, high-power expansion can be achieved by connecting multiple circuits in parallel, and the constant current of each channel can be controlled to achieve multi-channel current equalization effect.

[0035] In summary, the utility model provides a solid-state constant current soft start device that can expand high power. The device adopts a solid semiconductor switch device, realizes constant current control through PID control, realizes the startup soft start function, effectively suppresses the startup surge impact, and can be expanded in parallel to control the startup soft start of a higher power circuit. The circuit is mainly composed of a sampling circuit, a PID-controlled negative feedback amplifier circuit, a solid-state constant current control switch circuit, and a voltage reference circuit. The circuit can be connected in parallel to realize the power expansion function. The sampling circuit samples the current flowing through the switch circuit and converts the current signal into a voltage signal; the fixed voltage drop of the PN junction of the semiconductor device constitutes a voltage reference circuit; the difference between the sampled voltage signal of the sampling circuit and the voltage signal of the voltage reference circuit is used as the input of the amplifier circuit. If the difference is greater than zero, the amplifier circuit will have current, and this current will reduce the gate-source voltage of the switch tube, and realize constant current under the comprehensive control of negative feedback and PID circuits.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A solid-state constant current soft start device capable of expanding high power, characterized in that: The device includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a transistor V2, a diode D1, an NMOSFET tube Q1, a first capacitor C1, a second capacitor C2 and a plurality of charging capacitors; Among them, the first resistor R1 and the second resistor R2 are connected in series between the positive and negative electrodes of the power supply, the connection point of the first resistor R1 and the second resistor R2 is connected to the collector of the transistor V2 through the first capacitor C1 and the third resistor R3 connected in parallel, and the emitter of the transistor V2 is connected to the negative electrode of the power supply through the diode D1; the connection point of the first resistor R1 and the second resistor R2 is also connected to the gate of the NMOSFET tube Q1, the source of the NMOSFET tube Q1 is connected to the base of the transistor V2 and is connected to the negative electrode of the power supply through the fourth resistor R4, the second capacitor C2 is located between the gate of the NMOSFET tube Q1 and the negative electrode of the power supply, and a plurality of charging capacitors are connected in parallel between the positive electrode of the power supply and the drain of the NMOSFET tube Q1.

2. The solid-state constant current soft start device capable of expanding high power according to claim 1 is characterized in that: The device also includes another diode, the positive and negative electrodes of the diode are respectively connected to the source and drain of the NMOSFET tube Q1.

3. A soft start expansion device, characterized in that: It comprises several solid-state constant current expandable high-power soft-start devices as described in claim 1 or 2, and the several solid-state constant current expandable high-power soft-start devices are connected in parallel at both ends of a power supply.

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