CN2478271Y

CN2478271Y - High frequency high voltage switch mains for electrostatic cooker hood

Info

Publication number: CN2478271Y
Application number: CN 01219678
Authority: CN
Inventors: 刘俊颖
Original assignee: Guangyu Huihui Science & Tech Development Co Ltd (sino-Joint Adventure) Foshan C
Current assignee: Guangyu Huihui Science & Tech Development Co Ltd (sino-Joint Adventure) Foshan C
Priority date: 2001-04-18
Filing date: 2001-04-18
Publication date: 2002-02-20
Anticipated expiration: 2011-04-18

Abstract

The utility model relates to a high-frequency high-voltage switch power supply for the static lampblack purifier; wherein the power supply is the PWM Pulse Width Modulation structure, with the advantages of output short-circuit protection and prevention against the overshoot when the machine is started. When the over-current occurs on the load, the short-circuit protection circuit directly recovers the PWM circuit and switches off the high-voltage power supply output. When the high-voltage power supply is switched on, the circuit preventing the overshoot eliminates the output overshot voltage of the power supply through the PWM circuit. The circuit ensures the safety of the high-voltage transformer, the high-frequency and high-voltage rectifying element, the high-voltage filtration capacitor and the high-power switch pipe of the high-voltage power supply during overload or overshoot, thereby ensuring the reliability of long-time work of the high-voltage power supply and the supported static lampblack purifier.

Description

The high-frequency and high-voltage Switching Power Supply that a kind of electrostatic smoke purifier is used

The utility model relates to the switch power technology field, the high-frequency and high-voltage Switching Power Supply that particularly a kind of static cigarette clearing machine is used.

The high-frequency and high-voltage Switching Power Supply major loop that existing electrostatic smoke purifier is used is the circuit structure that adopts the PWM-type Switching Power Supply, it is made up of input filtering and rectifier 1, converter 2, booster circuit 3, high-frequency and high-voltage rectification, filter circuit 4, referring to shown in Figure 1.The core parts of converter are two high-power FETs, two pipes are under 12 controls of PWM (containing drive circuit) control circuit, alternate conduction with end, be transformed into the pulse voltage that operating frequency is 50KHz, this pulse voltage output amplitude after high frequency transformer boosts is the pulse voltage of 12KV, by exporting high direct voltage after high-frequency and high-voltage full-bridge rectification, the high-frequency and high-voltage filtering.The high voltage source output voltage can change in 0～10KV scope, is controlled by PWM.Because electrostatic smoke purifier is operated in outdoor, external environment condition poor (high temperature, low temperature, high humidity, salt fog), when clearing machine moves, condition of work is quite abominable in the machine, the oil smoke that contains more moisture content and other medium is during by field generator, high-voltage breakdown, sparkover often take place, and cause the high voltage source output short-circuit and damage.The load 5 of high voltage source is a field generator, it is a capacity load, together with the inductance and the resistance of the high frequency transformer side of paying coil, output loop constitutes a L-C-R circuit, and the L-C-R circuit certainly leads to an overshoot voltage and an electric current that brings disaster to power supply during the power supply start.In order to guarantee smoke purifier for a long time normally, effectively, work reliably, must thoroughly solve above-mentioned two problems, develop a kind of high-frequency and high-voltage Switching Power Supply that can really be used for electrostatic smoke purifier.

The purpose of this utility model is to provide a kind of reliable operation, protection to move the high-frequency and high-voltage Switching Power Supply that electrostatic smoke purifier efficiently uses.

The purpose of this utility model is achieved in that the high-frequency and high-voltage Switching Power Supply that a kind of electrostatic smoke purifier is used, comprise the current rectifying and wave filtering circuit that makes alternating current 220V～power supply become high voltage direct current output, PWM type translation circuit, boost and the high-frequency and high-voltage rectification circuit, between the control end of high voltage direct current output end and PWM, be connected to short-circuit protection circuit; Input at high voltage direct current output end and PWM is connected to anti-start overshoot circuit.Described short-circuit protection circuit is by current sampling circuit, impedance matching buffer circuit IC ₁, comparison circuit IC ₃, relatively shaping circuit and pwm control circuit are formed, input signal is the current sense resistor R from the load circuit of high voltage direct current output end directly ₁Last sampling, through IC ₁Follow and be isolated in differential comparator amplifier IC ₂With the protective current set point through IC ₄Compare and enlarge after following isolation, then by comparator IC ₃Output to the IC in the pwm control circuit ₈Control end (4).The input signal of described anti-start overshoot circuit links to each other with the initialization circuit of high-frequency and high-voltage power supply output voltage, through comparing integrating circuit IC ₅Be transformed to the setting voltage that is linear shape, IC ₅Output directly and the IC in the pwm control circuit ₈Input (5) connects.

Advantage of the present utility model is: (1) short-circuit protection circuit can be exported by the high pressure of powered-down in 1ms, in time protects power supply not to be subjected to a bit damage.(2) short-circuit protection circuit directly takes out from high-voltage output end sampling, and IC selects high speed MOS type for use, thus circuit reliable, be active in one's movements.(3) soft start-up process of anti-start overshoot is extremely of short duration effectively, thoroughly eliminates the overshoot voltage that start powers on.

Fig. 1 is the utility model high-frequency and high-voltage Switching Power Supply block diagram.

Fig. 2 is the short-circuit protection circuit block diagram in the utility model.

Fig. 3 is the short-circuit protection circuit schematic diagram among the utility model embodiment.

Fig. 4 is the anti-start overshoot circuit theory diagrams among the utility model embodiment.

Fig. 5 is the pwm control circuit schematic diagram among the utility model embodiment.

Fig. 6 is the utility model embodiment circuit theory diagrams.

By following embodiment the utility model is further elaborated.

Referring to Fig. 1-shown in Figure 6, each part of the utility model is described in detail:

(1) short-circuit protection

Implement short-circuit protection two basic demands are arranged: the one, reliable; The 2nd, quick.As seen from Figure 2, this short circuit current protective circuit 10 is made up of the current sampling circuit 9, buffer circuit 14, differential comparator amplifier 15 and the comparator 16 that directly are connected in the load circuit 5.Circuit all adopts the IC of high speed MOS type.

In short-circuit protection circuit schematic diagram shown in Figure 3, wherein, VHO is the output of power supply high pressure; C1 is the high-frequency and high-voltage filter capacitor; Xc is the field generator equiva lent impedance; R ₁Be current sense resistor.Load current I _LDetecting resistance R ₁Pressure drop be the input signal of protective circuit, be subjected to the restriction of power consumption and voltage magnitude, R ₁Resistance very little, therefore by having the IC of high input impedance ₁Follow isolation, realize circuit and R ₁Direct connection; The IC of low output impedance ₁With the sampled signal V after isolating ₀₁Send into differential comparator amplifier IC ₂End of oppisite phase.IC ₂The given voltage V of in-phase end input protection current settings 11 _ISSetting voltage V _ISBy R ₆, R ₇, W ₁With IC ₄The voltage setting circuit 6 of following the isolator composition provides.IC ₂The difference comparative result is through IC ₃IC after the comparator shaping from output terminals A output high level or low level to pwm circuit ₈Reset terminal 4, control PWM operating state.

Work as I _L≤ I _LmaxThe time:

V ₀₁≤V _IS；

V ₀₃≈ E ₁, the pwm circuit operate as normal.

Otherwise, work as I _L＞I _LmaxThe time,

V ₀₁＞V _IS；

V ₀₃≈ 0, and pwm circuit quits work.

In the formula: I _LmaxFor allowing maximum load current;

V ₀₃Be IC ₃Output voltage.

E ₁Supply voltage for IC.

(2) anti-start overshoot

Can realize soft start as long as the pulse duration that the time gives two high-power switch tubes of major loop in start is one by 0 to the linear change control signal of setting width, the overshoot of stopping to start shooting damages power supply.

So in the anti-start overshoot circuit theory diagrams of Fig. 4, IC ₅The in-phase input end of integrator inserts the set point of output voltage, IC ₅Output B inserts the IC in the pwm circuit ₈Input 5, the soft start when realizing the power supply start.The set point of output voltage is by R ₁₀, R ₂₀, W ₂The initialization circuit of forming provides, and buffer time is by R ₁₇C ₂Decision.

Pwm circuit 12 shown in Figure 5 is by IC ₆, IC ₇, IC ₈Form IC ₆, IC ₈Be 555 time-base circuits.IC ₆Form a multivibrator circuit, IC ₈Form a monostable circuit.After powering on, IC ₆The square-wave pulse that produces is through IC ₇Anti-phase, produce negative hopping edge pulse, affact IC ₈Trigger end 2.In brief, IC ₆Be IC ₈Clock circuit.IC ₈Control end 5 inserts by IC ₅The control voltage that anti-start overshoot circuit is sent here, its reset terminal 4 is received the output terminals A of short-circuit protection circuit.Fig. 6 has provided the complete pwm control circuit with short-circuit protection and anti-start overshoot function of the utility model.The each several part circuit of composition PWM particularly short-circuit protection is addressed in detail with the operation principle of anti-start overshoot circuit.But should stress the IC among Fig. 6 ₈(555) 5 ends of the monostable circuit of circuit composition are not the common connections by 0.01 μ f capacity earth, but the control voltage that put-into error amplifies, when its 5 end is controlled voltage less than 2/3Vcc, capacitor C ₄Charging voltage when arriving level corresponding to control voltage, the R-S trigger in 555 circuit just changes reset mode over to, trigger output uprises capacitor C ₄Discharge, pulse duration just reduces along with the reduction of control voltage like this.The VD of converter is directly proportional with the unbalanced pulse width, and pulse duration is and control being in proportion of voltage.When if VD increases, sampling voltage V _CvIncrease, be added to IC ₅Inverting input, IC ₅Output voltage descend IC ₈The control voltage of (555 circuit) 5 ends descends, and output pulse width descends, and makes the output voltage of DC converter descend, thereby keeps the stable of output voltage.

Claims

1, the high-frequency and high-voltage Switching Power Supply used of a kind of electrostatic smoke purifier, comprise the current rectifying and wave filtering circuit that makes the alternating current 220V power supply become high voltage direct current output, PWM type translation circuit, boost and the high-frequency and high-voltage rectification circuit, it is characterized in that, between the control end of high voltage direct current output end and PWM, be connected to short-circuit protection circuit; Input at high voltage direct current output end and PWM is connected to anti-start overshoot circuit.

2, the high-frequency and high-voltage Switching Power Supply used of electrostatic smoke purifier according to claim 1, it is characterized in that: described short-circuit protection circuit is by current sampling circuit, impedance matching buffer circuit IC ₁, comparison circuit IC ₃, relatively shaping circuit and pwm control circuit are formed, input signal is the current sense resistor R from the load circuit of high voltage direct current output end directly ₁Last sampling, through IC ₁Follow and be isolated in differential comparator amplifier IC ₂With the protective current set point through IC ₄Compare and enlarge after following isolation, then by comparator IC ₃Output to the IC in the pwm control circuit ₈Control end (4).

3, the high-frequency and high-voltage Switching Power Supply used of electrostatic smoke purifier according to claim 1, it is characterized in that: the input signal of described anti-start overshoot circuit links to each other with the initialization circuit of high-frequency and high-voltage power supply output voltage, through integrating circuit IC relatively ₅Be transformed to the setting voltage that is linear shape, IC ₅Output directly and the IC in the pwm control circuit ₈Input (5) connects.