CN214591155U - Leading adjustable boost circuit of pulse power supply for electrostatic precipitator - Google Patents

Abstract

The utility model provides a leading adjustable boost circuit of pulse power supply for electrostatic precipitator, including leading adjustable boost circuit, the pulse forms the circuit, pulse step up transformer and the body power plant that gathers dust, leading adjustable boost circuit includes three-phase interchange 380V power, buck-boost circuit that rectifier circuit and a plurality of switch tube that constitute by a plurality of diodes are constituteed, the three-phase interchange 380V power forms the direct current about 540V after rectifier circuit rectification, electric capacity C8 by two series connections, C9 partial pressure, then form output 0 behind buck-boost circuit by the switch tube is constituteed-2200V is adjustable direct current, the diode includes D23-D28, the switch tube includes Q9-Q16, switch tube Q9 ~ 11, Q13 ~ 14, Q16 is two buck circuits during operation, switch tube Q9, Q11 ~ 12, Q14 ~ 16 during operation is two boost circuits. The adjustable booster circuit can solve the problems that the existing adjustable booster circuit is high in manufacturing cost and needs a transformer to transform voltage, and is simple in structure, simple and convenient to manufacture, low in production cost and small in overall circuit size.

Description

Leading adjustable boost circuit of pulse power supply for electrostatic precipitator

Technical Field

The utility model relates to a leading adjustable boost circuit of pulse power supply, concretely relates to leading adjustable boost circuit of pulse power supply for electrostatic precipitator.

Background

With the increasing severity of environmental problems and the emergence of new environmental protection standards, in the field of electrostatic dust removal, the conventional high-voltage direct-current power supply, including a power frequency power supply, a three-phase power supply and a high-frequency power supply, cannot further improve the dust removal efficiency, so that the application of a high-voltage pulse power supply gradually grows. Meanwhile, researches show that the high-frequency power supply and the pulse power supply are matched with each other for use, so that the dust removal efficiency can be effectively improved, the energy consumption of the electric dust remover is reduced, and the electric dust remover has better economical efficiency.

The schematic diagram of the pulse power supply is shown in fig. 1: firstly, a pulse power supply is supplied by 380V alternating current three-phase, and forms 0V-2200V adjustable direct current voltage after being converted by a preposed adjustable booster circuit, then the voltage is applied to a pulse forming circuit to generate a narrow voltage pulse, the voltage is boosted by a pulse booster transformer, a voltage narrow pulse with the peak value of 60 kV-80 kV can be generated, and the voltage narrow pulse is sent to a dust collection body power plant for dust collection. In the above circuits, the prepositive adjustable booster circuit is more critical, and the pulse power supply products at home and abroad in the current market are mainly realized by two circuits:

the other is a three-phase silicon controlled adjustable booster circuit, and the schematic diagram is shown in fig. 2: the circuit in figure 2 is that a three-phase alternating current 380V power supply is subjected to voltage regulation by three-phase anti-parallel silicon controlled rectifier, and then is subjected to voltage boosting, rectification and filtering by a three-phase power frequency transformer to form adjustable direct current of 0-2200V. The voltage regulating circuit of the three-phase silicon controlled rectifier has the defects of complex control, need of a synchronous circuit, larger volume of a three-phase transformer, easy runaway of the silicon controlled rectifier when the circuit is provided with a capacitive load and loss of a post-stage circuit.

Another type of adjustable boost circuit is a high frequency boost circuit, the schematic of which is shown in fig. 3: the three-phase alternating current 380V power supply forms about 540V direct current after rectification, then the direct current is converted into high-frequency alternating current through an inverter consisting of Q1, Q2, Q3 and Q4, then the high-frequency alternating current is boosted through a high-frequency boosting transformer, and the high-frequency alternating current forms 0-2200V adjustable direct current after high-frequency rectification. The technical scheme has the defects that the circuit is complex in structure, more components are arranged, the size of the high-frequency transformer is larger, the high-frequency rectifier diode is not easy to select, and the reliability of the high-frequency rectifier circuit is not easy to design.

The common disadvantages of the two power sources are: (1) a transformer is needed, a silicon controlled power supply circuit needs a power frequency transformer, a high-frequency power supply circuit needs a high-frequency transformer, and the two transformers have larger volumes and higher prices because the pre-booster circuit needs to output larger power; (2) the secondary side of the transformer needs a high-voltage rectifier diode, and the reliability required by the diode is very high, so that the circuit structure, the volume efficiency, the component price, the volume, the cost and the efficiency are low, and the circuits adopted by the pulse power supply products are not ideal at present.

SUMMERY OF THE UTILITY MODEL

In order to solve certain or some technical problem that exists among the prior art, the utility model provides an electrostatic precipitator is with leading adjustable boost circuit of pulse power supply can solve the problem that current adjustable boost circuit cost of manufacture is high and must the transformer carry out the vary voltage, simple structure, the simple and convenient and low in production cost of preparation, the whole small of circuit.

For solving the above-mentioned prior art problem, the utility model discloses a following scheme:

the utility model provides a leading adjustable boost circuit of pulse power supply for electrostatic precipitator, includes leading adjustable boost circuit, pulse formation circuit, pulse step up transformer and gathers dust body power plant, leading adjustable boost circuit includes three-phase interchange 380V power, the buck-boost circuit of constituteing by a plurality of diodes and a plurality of switch tubes, three-phase interchange 380V power passes through form the direct current about 540V after the rectifier circuit rectification, then form output 0-2200V behind the buck-boost circuit of constituteing by the switch tube and be adjustable direct current, the switch tube includes Q5-Q8, the diode includes D17-D22, switch tube Q5, Q6, Q7 are the buck circuit when working, switch tube Q5, Q7, Q8 are the boost circuit when working.

The biggest advantage of this circuit scheme is that circuit structure is simple, and the components and parts are less, but the biggest problem is, in order to output 2200V voltage, the withstand voltage of Q7, Q8's switch tube must 3300V, withstand voltage 3300V's IGBT is more expensive, and the reliability of switch tube work is also not high when exporting 2200V, and electric capacity C7 also must adopt 3300V high-voltage capacitor, and the price is also more expensive, therefore the utility model discloses make further improvement to this kind of circuit, propose following circuit scheme:

furthermore, a capacitor filter with capacitors C8 and C9 connected in series is arranged behind the rectifying circuits D23-D28 in the pre-adjustable boost circuit, the center point of the series connection of the capacitors C8 and C9 is grounded, a capacitor C10 is connected behind the capacitor C8 in parallel, a buck-boost circuit composed of switching tubes Q9, Q10, Q11 and Q12 is connected, a capacitor C10 is connected behind the capacitor C9 in parallel, and a buck-boost circuit composed of switching tubes Q13, Q14, Q15 and Q16 is connected.

Furthermore, the switching tubes of the two buck-boost circuit diagonals connected behind the capacitors C8 and C9 work simultaneously, that is, the switching tubes Q9, Q12, Q14 and Q15 work simultaneously, the switching tubes Q10, Q11, Q13 and Q16 work simultaneously, and two groups of switching tubes are turned on alternately.

Further, when the output voltage minus a hysteresis is greater than the input voltage, the two buck-boost circuits connected behind the capacitors C8 and C9 are both in a boost state, that is, the switching tubes Q9 and Q14 are fully opened, the switching tubes Q10 and Q13 are fully closed, the switching tubes Q11 and Q12 are in complementary PWM conduction, and the switching tubes Q15 and Q16 are in complementary PWM conduction.

Further, when the sum of the output voltage and a hysteresis is smaller than the input voltage, the two buck-boost circuits connected behind the capacitors C8 and C9 are both in a buck state, that is, the switching tubes Q11 and Q16 are fully opened, the switching tubes Q12 and Q15 are fully closed, the switching tubes Q9 and Q10 are in complementary PWM conduction, and the switching tubes Q13 and Q14 are in complementary PWM conduction.

Furthermore, when the output voltage minus a hysteresis quantity is smaller than the input voltage and the output voltage plus a hysteresis quantity is larger than the input voltage, one of the two serial buck-boost circuits works in a boost state and the other works in a buck state.

Further, the method for switching the Buck circuit to the boost circuit in the Buck-boost circuit comprises the following steps: firstly, setting the switching to boost duty ratio as 5%, adjusting the duty ratio of another buck which is not switched, if the output requirement is not met after the duty ratio is adjusted to 95%, fixing the buck duty ratio, and adjusting the boost duty ratio until the requirement is met.

Further, the method for switching from the boost circuit to the Buck circuit in the Buck-boost circuit comprises the following steps: and setting the switching buck duty ratio to be 95%, adjusting the duty ratio of another boost without switching, and if the output voltage does not meet the requirement after being adjusted to be 5%, fixing the duty ratio and adjusting the buck duty ratio until the requirement is met.

Further, the method for keeping the switching point output voltage stable comprises the following steps: and (3) optimizing buck regulator parameters and boost regulator parameters in advance, storing the parameters in a flash of the single chip microcomputer controller, and taking out corresponding closed-loop control parameters at a switching point.

Compared with the prior art, the beneficial effects of the utility model reside in that:

carry out the vary voltage through leading adjustable boost circuit and improve, can realize the purpose of high frequency vary voltage under the vary voltage circumstances through the transformer not, circuit structure is simple, and components and parts are less, and rectifier diode no longer need use high-pressure rectifier diode moreover, and the cost of manufacture is low, and whole small, the effectual problem of having solved current adjustable boost circuit cost of manufacture height and having carried out the vary voltage by the transformer of preparation, simple structure, the simple manufacture is simple and convenient and low in production cost, and the whole small of circuit.

Drawings

Fig. 1 is a schematic diagram of a pulse power supply in the background art of the present invention;

FIG. 2 is a schematic diagram of a three-phase thyristor adjustable boost circuit in the background art of the present invention;

FIG. 3 is a schematic diagram of a high frequency boost circuit for an adjustable boost circuit in the background art of the present invention;

FIG. 4 is a schematic diagram of a buck-boost front-mounted adjustable boost circuit of the present invention;

fig. 5 is a schematic diagram of a serial buck-boost preposition adjustable boost circuit of the present invention;

fig. 6 is a schematic diagram of a pulse power supply adopting a serial buck-boost preposition adjustable booster circuit of the present invention;

fig. 7 is a schematic diagram of switching the serial buck-boost operation modes according to the input/output voltage relationship of the present invention.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that the embodiments or technical features described below can be arbitrarily combined to form a new embodiment without conflict.

As shown in fig. 4 to 7, a pulse power supply prepositive adjustable booster circuit for electrostatic dust collection comprises a prepositive adjustable booster circuit, a pulse forming circuit, a pulse booster transformer and a dust collection body power plant, wherein the prepositive adjustable booster circuit comprises a three-phase alternating current 380V power supply, a rectifying circuit consisting of a plurality of diodes and a buck-boost circuit consisting of a plurality of switching tubes, the three-phase alternating current 380V power supply forms about 540V direct current after being rectified by the rectifying circuit, then the direct current with adjustable output of 0-2200V is formed after passing through the buck-boost circuit consisting of the switching tubes, the diodes comprise D17-D22, the switching tubes comprise Q5-Q8, the switching tubes Q5, Q6 and Q7 are buck circuits when working, and the switching tubes Q5, Q7 and Q8 are boost circuits when working. The circuit has the greatest advantages of simple structure and fewer components.

In the above embodiment, a capacitor filter formed by serially connecting capacitors C8 and C9 is provided between the rectifying circuits D23 to D28 and the switching tubes Q9 to Q16 in the pre-adjustable voltage boost circuit, a center point of the serially connected capacitors C8 and C9 is grounded, a buck-boost circuit formed by switching tubes Q9, Q10, Q11 and Q12 is connected to the rear of the capacitor C8, and a buck-boost circuit formed by switching tubes Q13, Q14, Q15 and Q16 is connected to the rear of the capacitor C9.

The first circuit has the greatest advantages that the circuit structure is simple, the components are fewer, but the biggest problems are that the withstand voltages of the switching tubes of Q7 and Q8 are 3300V, the IGBT with the withstand voltage of 3300V is expensive, and the reliability of the operation of the switching tubes is not high when 2200V is output, so that the circuit is further improved, the improved circuit is equivalent to two buck-boost circuits which are connected in series, the input voltage of each buck-boost circuit is 270V, the output voltage of each buck-boost circuit is 0-1100V, the withstand voltages of Q9, Q10, Q13 and Q14 can be 600V, the IGBTs of Q11, Q12, Q15 and Q16 can be 1700V, the IGBTs of 600V and 1700V are not high in price, and the IGBT of 3300V is very high, so that the number of the switching tubes of the series buck-boost circuits is doubled, but is more favorable than that of a single buck-boost circuit in economic efficiency, the reliability of the work is much higher, the circuit volume is very small because of no transformer, and the serial buck-boost circuit is well matched with the pulse transformer with a center tap.

The utility model provides a leading adjustable boost circuit has the pulse transformer that the center was taken a percentage with the pulse formation circuit of establishing ties, former limit and can cooperate well, constitutes pulse power supply, and the withstand voltage of switch tube Q17, Q18 in the pulse formation circuit also can reduce one time moreover, uses withstand voltage 1700V's IGBT, has improved the reliability and the economic nature of circuit.

For the serial buck-boost circuit, the control strategy of the circuit is very important, and there are several control methods: the following control methods are specifically classified and explained:

firstly, a first control strategy: the simplest control strategy, embodiments of which include: the switching tubes of the diagonal lines of the two buck-boost circuits connected behind the capacitors C8 and C9 work simultaneously, namely the switching tubes Q9, Q12, Q14 and Q15 work simultaneously, the switching tubes Q10, Q11, Q13 and Q16 work simultaneously, and the two groups of switching tubes are conducted alternately.

The control method has the disadvantages that 8 tubes work all the time, the loss is large, the efficiency is low, the noise is large, two sensitive points of the inductance are large, the circuit noise is large than buck-boost, the control method has the advantages that the control method is simple, one path of complementary PWM can be realized, and the control method is not optimized enough.

Secondly, in the second control strategy, when the output voltage minus a hysteresis quantity is greater than the input voltage, that is, when Vin is less than Vout- Δ V, the two buck-boost circuits connected behind the capacitors C8 and C8 both operate in boost states, that is, the switching tubes Q9 and Q14 are fully opened, the switching tubes Q10 and Q13 are fully closed, the switching tubes Q11 and Q12 are in complementary PWM conduction, and the switching tubes Q15 and Q16 are in complementary PWM conduction.

And when the output voltage plus a hysteresis quantity is smaller than the input voltage, namely when Vin is larger than Vout + delta V, the two buck-boost circuits connected behind the capacitors C8 and C9 work in a buck state, namely the switching tubes Q11 and Q16 are fully opened, the switching tubes Q12 and Q15 are fully closed, the switching tubes Q9 and Q10 are in complementary PWM conduction, and the switching tubes Q13 and Q14 are in complementary PWM conduction.

And when the hysteresis quantity subtracted by the output voltage is smaller than the input voltage and the hysteresis quantity added by the output voltage is larger than the input voltage, namely Vout-delta V is less than Vin and less than Vout + delta V, the two serial buck-boost circuits respectively work for the boost circuit and the buck circuit, namely one buck-boost circuit works in the buck state, one buck-boost circuit works in the boost state, the circuit working in the buck state outputs 0.5 Vout-delta V, the circuit working in the boost state outputs 0.5Vout + delta V, and the two outputs are connected in series and are also Vout. This is also one of the advantages of the serial buck-boost, and the present embodiment proposes the above-mentioned new control strategy in consideration of the circuit characteristics of the serial buck-boost.

From the above embodiments, when Vin < Vout- Δ V, both the serial buck-boost circuits work in boost state, when Vin > Vout + Δ V, both the serial buck-boost circuits work in buck state, and when Vout- Δ V < Vin < Vout + Δ V, one buck-boost circuit works in buck state, so that the serial buck-boost circuits are completely prevented from working in buck-boost state, the working efficiency of the circuits is improved, and the working noise of the circuits is reduced. Two buck-boost circuits connected in series, one of which is working in buck state and outputs 0.5Vout- Δ V, and the other of which is working in boost state and outputs 0.5Vout + Δ V, will cause unbalance of the series voltage, but because Δ V is small, the unbalance is not large, and the unbalance will not affect the operation of the following circuit, because the operation characteristics of the following circuit depend on the total voltage of the series circuit, which is also Vout.

In fig. 7, Vin is the input voltage of the serial buck-boost, Vout is the output voltage of the serial buck-boost, and the serial buck-boost in block 1, block 2, block 3, one block and one block operate in the buck state, and the other block operates in the boost state, according to the relationship between the input voltage and the output voltage, the three regions can be divided into three regions. And the switching from the areas 1 and 3 to the areas 2 and the switching from the area 2 to the areas 1 and 3 have hysteresis characteristics, namely, the delta V entering the area 3 is small and is described by the two dotted lines at the inner part, and the delta V exiting the area 3 is large and is described by the two dotted lines at the outer part, so that switching oscillation around the switching point can be prevented.

At a switching point of an operating mode, for example, at a switching point of a buck-boost circuit in a serial buck-boost circuit from buck to boost, the duty ratio is changed greatly, for example, the duty ratio of buck is 1, the duty ratio should be changed to zero when switching to boost, but boost should have a minimum duty ratio, for example, 5%, the duty ratio is fixed, the duty ratio of another buck circuit which is not switched should be reduced a little, then the duty ratio is slowly switched into closed-loop regulation again, the regulation is not enough to 95%, at this moment, the duty ratio of the buck circuit is fixed, the duty ratio of the boost circuit is then closed-loop regulated, in short, in the buck and boost operating modes, one duty ratio is fixed, and the other duty ratio is closed-loop regulated, so that the control strategy is easy to design. The regulation rule is as follows:

the method for switching the buck circuit to the boost circuit in the buck-boost circuit comprises the following steps: firstly, setting the switching to boost duty ratio as 5%, adjusting the duty ratio of another buck which is not switched, if the output requirement is not met after the duty ratio is adjusted to 95%, fixing the buck duty ratio, and adjusting the boost duty ratio until the requirement is met.

Secondly, the method for switching the boost circuit to the buck circuit in the buck-boost circuit comprises the following steps: and setting the switching buck duty ratio to be 95%, adjusting the duty ratio of another boost without switching, and if the output voltage does not meet the requirement after being adjusted to be 5%, fixing the duty ratio and adjusting the buck duty ratio until the requirement is met.

And thirdly, switching from one buck and one boost to double buck or double boost, calculating an initial duty ratio according to the duty ratio relationship of buck input and output and the duty ratio relationship of boost input and output, and then adding closed-loop regulation on the basis of the initial duty ratio.

Fourthly, the method for keeping the output voltage of the switching point stable comprises the following steps: and (3) optimizing buck regulator parameters and boost regulator parameters in advance, storing the parameters in a flash of the single chip microcomputer controller, and taking out corresponding closed-loop control parameters at a switching point.

The buck-boost circuit works in a buck state and works in a boost state, so that the transfer functions are different, the parameter settings of the buck closed-loop regulator and the boost closed-loop regulator are different, the parameters of the buck regulator and the parameters of the boost regulator are optimized in advance and stored in a flash of a single chip microcomputer controller, corresponding closed-loop control parameters are taken out at a switching point, and the stability of the output voltage of the switching point can be maintained at the points.

The determination of the switching point can be determined according to the relation of input and output, and also can be determined according to the duty ratio, if the serial buck-boost circuit is shifted from the double buck operating state to a buck and a boost operating state, the switching at this time is based on that the duty ratio is close to a threshold value, the threshold value can be a value of 90%, once the operating duty ratio exceeds the threshold value, one buck is changed into boost, the duty ratio is set to a small duty ratio value, such as 5%, and is fixed, at this time, another buck duty ratio is adjusted in a closed loop, the operating state is continued when the output voltage meets the requirement, if the duty ratio is adjusted to about 95%, the voltage still does not meet the output requirement, the duty ratio of buck is fixed, the duty ratio of boost is adjusted, the operating state is continued when the output voltage meets the requirement, the operating state is adjusted to a certain degree, such as 15%, and the output voltage still does not meet the requirement, it should switch to the dual boost operating state. If the serial buck-boost circuit is shifted from a double-boost working state to a boost and a buck working state, the switching at this time is based on that the duty ratio is close to a threshold, the threshold can be a value of about 10%, once the working duty ratio is smaller than the threshold, one boost is changed into buck, the duty ratio is set to be a large duty ratio value, such as 95%, and is fixed, at this time, the duty ratio of the other boost is adjusted in a closed loop manner, the working state is continued if the output voltage meets the requirement, if the duty ratio is adjusted to be about 5%, the voltage still does not meet the output requirement, the duty ratio of the boost is fixed, the duty ratio of the buck is adjusted, the working state is continued if the output voltage meets the requirement, the working state is adjusted to a certain degree, such as 80%, and the output voltage still does not meet the requirement, the serial buck circuit is switched to the double-boost working state. This control method defines three working areas: the high-efficiency boost circuit comprises two buck working areas, two boost working areas and a buck-boost working area, wherein the maximum and minimum duty ratios of two buck-boost circuits are connected in series, the duty ratio D is minimum 10% in the two boost working areas, the buck working area enters a buck value when the duty ratio D is smaller than the value, the boost working area enters a buck value when the duty ratio D is maximum 85% in the two buck working areas, the buck working area enters a buck value when the duty ratio D is larger than the value, the boost working area enters a boost value when the duty ratio D is larger than the value, the maximum duty ratio of the buck value is 95%, the minimum duty ratio is 80%, the minimum duty ratio of the boost is 5%, and the maximum duty ratio is 15%. In a buck and a boost working area, if the boost working area is excessive from boost to buck-boost, namely the boost duty ratio is less than 10%, the buck duty ratio is adjusted to 95%, then the boost duty ratio is adjusted, when the boost duty ratio is equal to 5%, the fixed boost duty ratio is 5%, and when the buck duty ratio is equal to 80%, the buck working area is excessive from a buck and a boost working area to a double-buck area. If the boost working area is excessive from the double-buck area to the buck, namely the buck duty ratio is larger than 85%, the boost duty ratio is adjusted to be fixed to 5%, then the buck duty ratio is adjusted, when the buck duty ratio is adjusted to be 95%, the fixed buck duty ratio is 95%, the boost duty ratio is adjusted, and when the boost duty ratio is adjusted to be 15%, the boost working area is excessive from the buck working area to the double-boost area. Such a transition is relatively smooth. Namely, in a buck and a boost working area, if the duty ratio of the buck is less than 80%, switching is carried out to the double buck working area, and the duty ratio of the boost is more than 15%, switching is carried out to the double boost working area.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention cannot be limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are all within the protection scope of the present invention.

Claims (5)

1. The utility model provides a leading adjustable boost circuit of pulse power supply for electrostatic precipitator, includes leading adjustable boost circuit, pulse formation circuit, pulse step up transformer and the body power plant that gathers dust, its characterized in that: the front-mounted adjustable booster circuit comprises a three-phase alternating current 380V power supply, a rectifying circuit composed of a plurality of diodes and a buck-boost circuit composed of a plurality of switching tubes, wherein the three-phase alternating current 380V power supply forms about 540V direct current after being rectified by the rectifying circuit, then the three-phase alternating current forms adjustable direct current with 0-2200V output after passing through the buck-boost circuit composed of the switching tubes, the diodes comprise D17-D22, the switching tubes comprise Q5-Q8, the switching tubes Q5, Q6 and Q7 are buck circuits when working, and the switching tubes Q5, Q7 and Q8 are boost circuits when working.

2. The pre-adjustable booster circuit of the pulse power supply for electrostatic dust collection according to claim 1, characterized in that: a capacitor filter with capacitors C8 and C9 connected in series is arranged between the rectifying circuit and the switching tubes Q9-Q16 in the preposed adjustable booster circuit, the central points of the capacitors C8 and C9 connected in series are grounded, a buck-boost circuit consisting of switching tubes Q9, Q10, Q11 and Q12 is connected behind the capacitor C8, and a buck-boost circuit consisting of switching tubes Q13, Q14, Q15 and Q16 is connected behind the capacitor C9.

3. The pre-adjustable booster circuit of the pulse power supply for electrostatic dust collection according to claim 2, characterized in that: when the output voltage minus a hysteresis quantity is greater than the input voltage, the two buck-boost circuits connected behind the capacitors C8 and C9 work in boost states, namely the switching tubes Q9 and Q14 are fully opened, the switching tubes Q10 and Q13 are fully closed, the switching tubes Q11 and Q12 are in complementary PWM conduction, and the switching tubes Q15 and Q16 are in complementary PWM conduction.

4. The pre-adjustable booster circuit of the pulse power supply for electrostatic dust collection according to claim 2, characterized in that: when the sum of the output voltage and a hysteresis quantity is smaller than the input voltage, the two buck-boost circuits connected behind the capacitors C8 and C9 work in buck states, namely the switching tubes Q11 and Q16 are fully opened, the switching tubes Q12 and Q15 are fully closed, the switching tubes Q9 and Q10 are in complementary PWM conduction, and the switching tubes Q13 and Q14 are in complementary PWM conduction.

5. The pre-adjustable booster circuit of the pulse power supply for electrostatic dust collection according to any one of claims 3 to 4, characterized in that: when the output voltage minus a hysteresis quantity is smaller than the input voltage and the output voltage plus a hysteresis quantity is larger than the input voltage, one of the two serial buck-boost circuits works in the boost state and the other works in the buck state.

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