CN212231090U - Surge suppression circuit for discharging overvoltage spike - Google Patents

Abstract

The utility model discloses a surge suppression circuit of excessive pressure peak of bleeding, including establishing ties the opto-coupler between drive power supply and load, shunt, relay, with the parallelly connected triode of opto-coupler, with the divider resistance R3 of triode series connection before the relay, the collecting electrode of triode passes through RC charging circuit and connects to ground, this charging resistance R2 with by operational amplifier and field effect transistor constitute examine the voltage control circuit parallelly connected, the opto-coupler gathers the voltage division control opto-coupler that the shunt detected through another operational amplifier. When the current of the current divider is too large, the optocoupler is switched off to enable the triode to be switched on, in the time period, the resistor R2 charges the capacitor, the driving power supply provides current for the load through the resistor R3 and the triode, the resistor R3 shares partial voltage to reduce the load current until the voltage at two ends of the capacitor rises enough to switch off the triode, the voltage detection control circuit detects the charging voltage, and if the voltage exceeds a threshold value, the over-peak voltage is released and the triode is switched off.

Description

Surge suppression circuit for discharging overvoltage spike

Technical Field

The utility model relates to a teaching aid, in particular to surge suppression circuit of excessive pressure peak of releasing.

Background

The existing teaching demonstration box for automobile training generally concentrates all basic elements of automobile load in the same box body, and supplies power after a battery system or an alternating current power supply is converted into direct current. Surge is instantaneous over-current occurring in a circuit, and is transient current and voltage fluctuation which rises quickly and then falls slowly. The damage of surge voltage to the circuit is mainly caused by that the generated overvoltage exceeds the rated voltage of an electrical element, so that the electrical element is damaged, a PN junction is broken down, a control circuit fails to control, a circuit short circuit is seriously caused to cause fire, and in addition, different switching loads can be frequently switched for a long time during teaching, so that the condition of overlarge current often appears in the loads. If the condition of overlarge current is not processed in time, the load is often damaged, and the teaching work is influenced. The surge voltage in the circuit is usually suppressed by adopting a transient voltage suppression diode (TVS tube) for voltage limitation, but the TVS tube is easy to be broken down to cause short circuit when the surge is overlarge, and the consequence is more serious.

Disclosure of Invention

The utility model provides a surge suppression circuit of excessive pressure peak of releasing can restrain too high voltage in certain length and act on the load. Specifically, the method comprises the following steps: a surge suppression circuit for discharging overvoltage spikes comprises an operational amplifier UA1, an optical coupler U1, a shunt FL, a first resistor R1, a variable resistor Rw1, a triode Q1, a second resistor R2, a third resistor R3, a fourth resistor R4, a variable resistor Rw2, a capacitor C, a field effect transistor Q2 and an operational amplifier UA2, wherein the input end of the shunt FL is connected with the positive electrode of a driving power supply, the output end of the shunt FL is connected with the collector of the optical coupler U1, the emitter of the optical coupler U1 is connected with one switching end of a relay K, the voltage detection end of the shunt FL is connected with the inverted input end of the operational amplifier UA1, the output end of the operational amplifier UA1 is connected with the anode of the optical coupler U1, the cathode of the optical coupler U1 is connected with the ground, the non-phase input end of the operational amplifier UA1 is respectively connected with one end of the first resistor R1, one end of the variable resistor Rw1, and the other end of the variable resistor Rw1 is connected with the ground, the other end of the first resistor R1 is connected with a working power supply; the output end of the current divider FL is connected with one end of a second resistor R2, the collector of the triode Q1 and the source of the field effect transistor Q2, the other end of the second resistor R2 is connected with the inverting input end of the operational amplifier UA2, one end of the capacitor C and the base of the triode Q1, the other end of the capacitor C is connected with the ground, the emitter of the triode Q1 is connected with the emitter of the optocoupler U1 through a third resistor R3, the output end of the operational amplifier UA2 is connected with the gate of the field effect transistor Q2, the drain of the field effect transistor Q2 is grounded, the non-inverting input end of the operational amplifier UA2 is connected with one end of a fourth resistor R4, one end of a variable resistor two Rw2 and the other end of the variable resistor two Rw2 are connected with the ground.

Further, the transistor Q1 is an NPN transistor.

The beneficial effects of the utility model are that, utilize shunt FL when the electric current is too big, in time cut off drive power supply and relay K's lug connection, make triode Q1 switch on, until the voltage at electric capacity C both ends risees to the time of being enough to turn off triode Q1, in this time quantum, second resistance R2 charges for electric capacity C, drive power supply provides the electric current for the load through third resistance R3 and triode Q1, third resistance R3 has shared partial pressure, make load current reduce. When the current passing through the current divider FL is reduced after surge elimination, the optocoupler U1 is conducted, the third resistor R3 and the triode Q1 are short-circuited, and the driving power supply provides current for the load through the current divider FL and the optocoupler U1.

The utility model discloses a two UA2 of operational amplifier circuit pass through fourth resistance R4, and two Rw2 of variable resistance form bleeder circuit to obtain reference voltage at node b, this reference voltage inputs in the in-phase input of two UA2 of operational amplifier, can set up two Rw2 of variable resistance for suitable value, the field effect transistor switches on when electric capacity C's voltage rising reaches with the threshold value, electric capacity C discharges, release excessive pressure spike.

Drawings

The invention is described in further detail below with reference to the accompanying drawings and preferred embodiments:

fig. 1 is a circuit diagram of a preferred embodiment of the surge suppression circuit of the present invention.

Detailed Description

Referring to fig. 1, a surge suppression circuit for discharging an overvoltage spike includes an operational amplifier UA1, an optical coupler U1, a shunt FL, a first resistor R1, a variable resistor Rw1, a transistor Q1, a second resistor R2, a third resistor R3, a fourth resistor R4, a variable resistor Rw2, a capacitor C, a field effect transistor Q2, and an operational amplifier UA2, an input terminal of the shunt FL is connected to an anode of a driving power source, an output terminal of the shunt FL is connected to a collector of the optical coupler U1, an emitter of the optical coupler U1 is connected to a switching terminal of the relay K, a voltage detection terminal of the shunt FL is connected to an inverting input terminal of the operational amplifier UA1, an output terminal of the operational amplifier UA1 is connected to an anode of the optical coupler U1, a cathode of the operational amplifier U1 is connected to ground, a non-inverting input terminal of the operational amplifier UA1 is connected to one end of the first resistor R1, one end of the variable resistor Rw1, and another end of the variable resistor Rw1 is connected to ground, the other end of the first resistor R1 is connected with a working power supply; the output end of the current divider FL is connected with one end of a second resistor R2, the collector of the triode Q1 is connected, the source of the field-effect tube Q2 is connected, the other end of the second resistor R2 is connected with the inverting input end of the second operational amplifier UA2, one end of the capacitor C and the base of the triode Q1, the other end of the capacitor C is connected to ground, the emitter of the triode Q1 is connected with the emitter of the optocoupler U1 through a third resistor R3, the output end of the second operational amplifier UA2 is connected with the gate of the field-effect tube Q2, the drain of the field-effect tube Q2 is grounded, the non-inverting input end of the second operational amplifier UA2 is connected with one end of a fourth resistor R4, one end of a variable resistor two Rw2 and the other end of the variable resistor.

When the voltage divider is used, a voltage dividing circuit is formed by the first resistor R1 and the first variable resistor Rw1, a reference voltage is obtained at a node a, the reference voltage is input into a non-inverting input end of the operational amplifier UA1, a voltage on a voltage detection resistor is output by a voltage detection end of the current divider FL, the voltage reflects the magnitude of a current I, a proper reference voltage is obtained by adjusting the first variable resistor Rw1, the reference voltage is compared with the voltage output by the voltage detection end, the reference voltage is higher than the voltage output by the voltage detection end under the normal condition of the current I, the operational amplifier UA1 outputs a high level, a collector and an emitter of the optical coupler U1 are conducted, the current I normally flows into a load, when the current I is overlarge, the voltage output by the voltage detection end is higher than the reference voltage, the operational amplifier UA1 outputs a low level, the collector and the emitter of the optical coupler U1 are cut off, the current I is cut off, and a voltage difference is generated between the, the shunt FL charges the capacitor C through the second resistor R2, when the base voltage of the triode Q1 is larger than the emitter and smaller than the collector, the triode Q1 is conducted, the driving power supply provides current for the load through the third resistor R3 and the triode Q1, and the third resistor R3 shares partial voltage, so that the load current is reduced. Until the voltage at the both ends of electric capacity C rose to when being enough to turn off triode Q1, if surge elimination this time quantum, the opto-coupler U1 switched on makes triode Q1 short circuit, and drive power supply resumes to supply power to the load through opto-coupler U1, the utility model discloses an operational amplifier circuit two UA2 is still through fourth resistance R4, and variable resistance two Rw2 form bleeder circuit to obtain reference voltage at node b, this reference voltage input to operational amplifier two UA2 in the homophase input end, can set up variable resistance two Rw2 as appropriate value, and when electric capacity C's voltage rose reach with threshold value time field effect tube Q2 switches on, electric capacity C discharges, releases the excessive pressure spike, when making load element on the car that the withstand voltage ability is relatively weak was received in the system of high voltage by mistake, had passed second resistance R2 promptly, after the protection ageing that electric capacity C decided, when the voltage was too big, input voltage can be stopped.

While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited to the details of the embodiments shown, but is capable of various modifications and changes without departing from the spirit of the invention.

Claims (2)

1. A surge suppression circuit for discharging overvoltage spikes comprises an operational amplifier UA1, an optical coupler U1, a shunt FL, a first resistor R1, a variable resistor Rw1, a triode Q1, a second resistor R2, a third resistor R3, a fourth resistor R4, a variable resistor Rw2, a capacitor C, a field-effect tube Q2 and an operational amplifier UA2, and is characterized in that the input end of the shunt FL is connected with the positive electrode of a driving power supply, the output end of the shunt FL is connected with the collector of the optical coupler U1, the emitter of the optical coupler U1 is connected with a switching end of a relay K, the voltage detection end of the shunt FL is connected with the inverting input end of the operational amplifier UA1, the output end of the operational amplifier UA1 is connected with the anode of the optical coupler U1, the cathode of the optical coupler U1 is connected with the ground, the non-inverting input end of the operational amplifier UA1 is respectively connected with one end of a first resistor R1 and one end of a variable resistor Rw1, the other end of the first variable resistor Rw1 is connected to the ground, and the other end of the first resistor R1 is connected with the working power supply; the output end of the current divider FL is connected with one end of a second resistor R2, the collector of the triode Q1 and the source of the field effect transistor Q2, the other end of the second resistor R2 is connected with the inverting input end of the operational amplifier UA2, one end of the capacitor C and the base of the triode Q1, the other end of the capacitor C is connected with the ground, the emitter of the triode Q1 is connected with the emitter of the optocoupler U1 through a third resistor R3, the output end of the operational amplifier UA2 is connected with the gate of the field effect transistor Q2, the drain of the field effect transistor Q2 is grounded, the non-inverting input end of the operational amplifier UA2 is connected with one end of a fourth resistor R4, one end of a variable resistor two Rw2 and the other end of the variable resistor two Rw2 are connected with the ground.

2. The surge suppression circuit according to claim 1, wherein said transistor Q1 is an NPN transistor.

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