CN107786078A

CN107786078A - Discharge circuit

Info

Publication number: CN107786078A
Application number: CN201610723615.6A
Authority: CN
Inventors: 谢兴艺
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-08-25
Filing date: 2016-08-25
Publication date: 2018-03-09

Abstract

A kind of discharge circuit, it is electrically connected with the output end of power factor correction circuit, and the output end of the power factor correction circuit is defined as first node, has a filter capacitor in the power factor correction circuit.The discharge circuit includes a control unit and a discharge cell.The control unit includes a NPN type triode, first PNP type triode and a first resistor.The base stage of first NPN type triode electrically connects with an external voltage, its grounded emitter, its colelctor electrode is electrically connected with the base stage of first PNP type triode, and the emitter stage of first PNP type triode electrically connects with the first node, and its colelctor electrode is grounded by the first resistor.The discharge cell includes second PNP type triode and a discharge resistance.The base stage of second PNP type triode is electrically connected with the colelctor electrode of first PNP type triode, and its emitter stage is electrically connected by the discharge resistance with the first node.

Description

Discharge circuit

Technical field

The present invention relates to a kind of discharge circuit, more particularly to a kind of consumption power is smaller and discharge time is adjustable automatic High voltage discharge circuit.

Background technology

Drive circuit is mainly used to, by the DC voltage of input, make the regulation of voltage level, and stabilizes it set A magnitude of voltage, its using drive Shang Qiao and lower bridge power component switching and produce pulse wave, this pulse wave passes through inductance capacitance group Into low pass filter after produce steady dc voltage, to supply various electronic products, referring specifically to VolkanKursun Et al. " the HIGH INPUT VOLTAGE STEP-DOWN DC-DCCONVERTERS that are delivered in IEEE systems for 2004 The texts of FORINTEGRATION IN A LOW VOLTAGE CMOS PROCESS " one.

In the driving circuit, generally require one power factor correction circuit of increase (Power Factor Corrector, PFC), to change the waveform of input current and phase angle, the higher hamonic wave in correcting current.Specifically, the Active PFC Circuit includes a filter capacitor, to pass through the higher hamonic wave in the filter capacitor effectively correcting current.The filter capacitor Size depends on the size of load, and load is bigger, and the filter capacitor is also bigger.

When the power is turned on, normal work is loaded, the higher hamonic wave that the filter capacitor can effectively in correcting current, together When, the filter capacitor will store electric energy.However, when power supply disconnects, load is stopped, the electricity being stored in the filter capacitor It can not be discharged, and need to be put the electric energy being stored in the filter capacitor by discharging naturally, its discharge time by loading It is longer, easily there is high pressure electric shock.To avoid high pressure Danger Electric shock risk, the general height that will be stored in using resistance in the filter capacitor Pressure discharges.And in order to avoid consuming excessive power, and the filter capacitor is discharged from big resistance.But from big Conductive discharge, its discharge time is longer, so that the voltage storage time being stored in the filter capacitor is longer, it would still be possible to cause height Press Danger Electric shock risk.

In view of this, it is necessary to provide that a kind of consumption power is smaller and discharge time adjustable discharge circuit.

The content of the invention

It will illustrate a kind of to consume the automatic high pressure that power is smaller and discharge time can be adjusted and discharge electricity with embodiment below Road.

A kind of discharge circuit, it is electrically connected with the output end of power factor correction circuit, and the power factor correction circuit Output end be defined as first node, there is a filter capacitor in the power factor correction circuit.The discharge circuit includes one Individual control unit and a discharge cell.The control unit includes a NPN type triode, first PNP type triode An and first resistor.The base stage of first NPN type triode electrically connects with an external voltage, its grounded emitter, its Colelctor electrode electrically connects with the base stage of first PNP type triode, the emitter stage of first PNP type triode and first node electricity Connection, its colelctor electrode are grounded by the first resistor.The discharge cell includes second PNP type triode and an electric discharge Resistance, the base stage of second PNP type triode electrically connect with the colelctor electrode of first PNP type triode, and its emitter stage passes through this Discharge resistance electrically connects with the first node, its grounded collector.

Relative to prior art, when the circuit is on, the power factor correction circuit normal work, the filter capacitor is used for The higher hamonic wave in power circuit is filtered out, and stores electric energy.The base stage external voltage of the NPN type triode and turn on, its current collection Pole tension convergence zero, first PNP type triode conducting, the collector voltage of first PNP type triode is close to first segment Point voltage, so that second PNP type triode is ended, therefore, discharge circuit consumption power is smaller.When a circuit is open, The NPN type triode is ended with first PNP type triode, second PNP type triode conducting, so that being stored in the filter Electric energy in ripple electric capacity is discharged automatically by the discharge cell, to avoid high pressure Danger Electric shock risk.And regulation can be passed through The resistance big minor adjustment discharge time of the discharge resistance, realize repid discharge purpose.

Brief description of the drawings

Fig. 1 is the circuit diagram of discharge circuit provided in an embodiment of the present invention.

Embodiment

Embodiment of the present invention is described in further detail below in conjunction with accompanying drawing.

Fig. 1 is referred to, a kind of discharge circuit 10 provided in an embodiment of the present invention, it is parallel to power factor correction circuit 20 Between load.Specifically, the input Vin of the power factor correction circuit 20 electrically connects with power output end, the power because The output end of plain correcting circuit 20 is defined as first node A.There is a filter capacitor 21 in the power factor correction circuit 20, It is used to filter out the higher hamonic wave in source current.

The discharge circuit 10 includes a control unit 30 and a discharge cell 40.

The control unit 30 includes a NPN type triode 31, first PNP type triode 32 and one first electricity Resistance 33.Preferably, the control unit 30 further comprises a bleeder circuit 34 and a mu balanced circuit 35.

The bleeder circuit 34 includes a second resistance 341 and a 3rd resistor 342.The both ends of the second resistance 341 Electrically connected respectively with the base stage and external voltage of the NPN type triode 31, one end of the 3rd resistor 342 and the NPN type three The base stage electrical connection of pole pipe 31, other end ground connection.In the present embodiment, external voltage VDD is power factor correction circuit 20 One 15 volts or so of boost voltage of output, when power factor correction circuit 20 disconnects, external voltage VDD disconnects, i.e., For 0 volt.

The grounded emitter of the NPN type triode 31, its colelctor electrode pass through the 4th resistance 36 and first positive-negative-positive three The base stage electrical connection of pole pipe.

The mu balanced circuit 35 includes the 5th resistance 351 and first electrically connected with the 5th resistance 351 is steady Press diode 352.

The emitter stage of first PNP type triode 32 is electrically connected by the mu balanced circuit 35 with first node A, also, should The positive pole of first voltage-regulator diode 352 electrically connects with the emitter stage of first PNP type triode 32.First PNP type triode 32 colelctor electrode is grounded by the first resistor 33.

The discharge cell 40 includes second PNP type triode 41 and a discharge resistance 42.Second positive-negative-positive three The base stage of pole pipe 41 is electrically connected by second voltage-regulator diode 43 with the colelctor electrode of first PNP type triode 32.This The grounded collector of two PNP type triode 41, its emitter stage are electrically connected by the discharge resistance 42 with first node A.Preferably, The 3rd voltage-regulator diode 44 is provided between the emitter stage of second PNP type triode 41 and the discharge resistance 42.

When the circuit is on, the normal work of power factor correction circuit 20, the filter capacitor 21 are used to filter out power supply electricity Higher hamonic wave in road, and store electric energy.External voltage is connected, and the base voltage of the NPN type triode 31 is higher than its emitter stage Voltage, the NPN type triode 31 turn on, and the collector voltage of the NPN type triode 31 levels off to zero.The pole of first positive-negative-positive three The emitter voltage of pipe 32 is higher than its base voltage, and therefore, first PNP type triode 32 turns on.Second PNP type triode 41 collector voltage and its base voltage are of substantially equal, and second PNP type triode 41 is ended, and therefore, the discharge circuit disappears Wasted work rate is smaller.

Conversely, when a circuit is open, the power factor correction circuit 20 disconnects.The NPN type triode 31 with this this first PNP type triode 32 is ended, and second PNP type triode 41 turns on, so that the electric energy being stored in the filter capacitor 21 leads to Cross the discharge cell 40 to be discharged automatically, to avoid high pressure Danger Electric shock risk.

The discharge circuit 10 is used to discharge the electric energy being stored in the filter capacitor 21, and its speed that discharges depends on the electric discharge The size of resistance 42.Specifically, the discharge resistance 42 is bigger, and electric discharge is slower, and discharge time is longer, conversely, the discharge resistance 42 Smaller, electric discharge is faster, and discharge time is shorter.

The discharge circuit 10 is simple in construction, consumes power electricity that is smaller, and will being stored in automatically in filter capacitor 21 It can discharge, to avoid high pressure Danger Electric shock risk.Also, the discharge circuit 10 can be by adjusting the resistance size of the discharge resistance 42 Discharge time is adjusted, realizes repid discharge purpose.

In addition, those skilled in the art can also do other designs changed for the present invention in spirit of the invention, as long as Its technique effect without departing from the present invention.These changes done according to present invention spirit, it should all be included in institute of the present invention Within the scope of claimed.

Claims

1. a kind of discharge circuit, it is electrically connected with the output end of power factor correction circuit, and the power factor correction circuit Output end is defined as first node, has a filter capacitor in the power factor correction circuit, and the discharge circuit includes：One Control unit, it includes a NPN type triode, first PNP type triode and a first resistor, the first NPN The base stage of type triode electrically connects with an external voltage, its grounded emitter, its colelctor electrode and first PNP type triode Base stage electrically connects, and the emitter stage of first PNP type triode electrically connects with the first node, and its colelctor electrode passes through the first resistor Ground connection；One discharge cell, it includes second PNP type triode and discharge resistance second PNP type triode Base stage electrically connected with the colelctor electrode of first PNP type triode, its emitter stage passes through the discharge resistance and the first node electricity Connection, its grounded collector.

2. discharge circuit as claimed in claim 1, it is characterised in that the control unit further comprises a bleeder circuit, The bleeder circuit is arranged between the base stage of the NPN type triode and external voltage.

3. discharge circuit as claimed in claim 2, it is characterised in that the bleeder circuit includes second resistance and one the Three resistance, the both ends of the second resistance electrically connect with the base stage and external voltage of the NPN type triode respectively, the 3rd resistor One end electrically connected with the base stage of the NPN type triode, the other end ground connection.

4. discharge circuit as claimed in claim 1, it is characterised in that the control unit further comprises the 4th resistance, 4th resistance is arranged between the colelctor electrode of the NPN type triode and the base stage of first PNP type triode.

5. discharge circuit as claimed in claim 1, it is characterised in that the control unit further comprises a voltage regulation unit, The voltage regulation unit is arranged between the emitter stage of first PNP type triode and the first node.

6. discharge circuit as claimed in claim 5, it is characterised in that the voltage regulation unit includes the 5th resistance and one With the first voltage-regulator diode of the 5th resistant series, the positive pole of first voltage-regulator diode and first PNP type triode Emitter stage electrically connects.