High-power factor bipolar current source type dielectric barrier discharge power supply
Technical Field
The utility model relates to the field of special power supplies of power electronics, in particular to a power supply design of a dielectric barrier discharge load, and in particular relates to a high-power factor bipolar current source type dielectric barrier discharge power supply.
Background
Dielectric barrier discharge (DielectricBarrierDischarge, DBD) refers to a non-equilibrium gaseous discharge in which an insulating medium is inserted into the discharge space. Dielectric barrier discharge devices are generally composed of a high voltage electrode, a barrier dielectric, a discharge space, and a low voltage electrode (typically a ground electrode). When a sufficiently high alternating voltage is applied between the high and low voltage electrodes, the gas between the electrodes will break down, thereby forming a large number of microdischarge channels in the discharge air gap. Under the action of the microdischarge channels, a large amount of active particles will be generated in the discharge air gap. Due to the characteristics, the dielectric barrier discharge technology is widely applied to the industrial fields of ozone synthesis, light source generation with specific wavelength, material surface modification, harmful gas treatment, aerospace and the like. The current power supply is mostly a voltage type power supply, and when the voltage type power supply directly supplies power to a capacitive load such as a DBD load, uncontrolled current spikes can occur on the load, and bipolar excitation waveforms required by the DBD load are difficult to generate. In addition, the existing DBD load power supplies mostly adopt mutually independent two-stage structures (a rectifying part and an inverting part), so that the defects of multiple components, complex control and low overall power efficiency of the power supplies are commonly caused. How to design a DBD load power supply which can fully exert the DBD load performance and has simple structure, high efficiency and high power factor becomes a problem to be solved in the application field of the DBD, and has important practical significance.
Disclosure of Invention
The utility model aims to provide a high-power factor bipolar current source type dielectric barrier discharge power supply.
The technical scheme of the utility model is as follows:
the utility model provides a high-power factor bipolar current source type dielectric barrier discharge power supply, which is characterized by comprising the following components: the power supply comprises an alternating current power supply, a first diode, a second diode, a third diode, a fourth diode, an inductor, a step-up transformer with a center tap, a first switching tube and a second switching tube. The first end of the alternating current power supply is respectively connected with the anode of the first diode and the cathode of the third diode; the second end of the alternating current power supply is respectively connected with the anode of the second diode and the cathode of the fourth diode; the cathode of the first diode is respectively connected with the cathode of the second diode and the first end of the inductor; the anode of the third diode is respectively connected with the anode of the fourth diode, the first end of the first switching tube and the first end of the second switching tube; the second end of the inductor is connected with a center tap of a primary coil of the step-up transformer; the second end of the first switching tube is connected with the first end of the primary coil of the step-up transformer; the second end of the second switching tube is connected with the second end of the primary coil of the step-up transformer; the first end of the secondary coil of the step-up transformer is connected with the high-voltage electrode of the dielectric barrier discharge load; and the second end of the secondary coil of the step-up transformer is connected with the low-voltage electrode of the dielectric barrier discharge load.
Optionally, the first switching tube is the same as the second switching tube.
Optionally, the working frequencies of the first switching tube and the second switching tube are equal, and the duty ratios of the driving signals of the first switching tube and the driving signals of the second switching tube are equal.
Optionally, the duty ratio D of the first switching tube and the second switching tube ranges from: d is more than or equal to 0.5 and less than 1.
Optionally, the first switching tube and the second switching tube are NMOS; the first end of the first switching tube and the first end of the second switching tube are both drains of NMOS, and the second end of the first switching tube and the second end of the second switching tube are both sources of NMOS.
Optionally, the first switching tube and the second switching tube are both operated in a soft switching state.
Alternatively, the voltage peak value and the voltage rising rate of the dielectric barrier discharge load can be achieved by adjusting the frequency of the switching tube.
Alternatively, the correction of the power factor can be achieved by reasonably selecting the value of the inductance.
Performance advantages:
compared with the prior art, the utility model has the advantages that:
(1) The power supply disclosed by the utility model has the advantages of compact structure and simple driving control scheme, realizes the organic combination of the power factor correction circuit and the pulse excitation generation circuit, and greatly reduces the control difficulty and cost of the power supply.
(2) The power supply disclosed by the utility model provides high-frequency bipolar pulse excitation voltage with high rise rate to meet the requirement of high-performance discharge of a DBD load, and simultaneously can realize the technical indexes of high power factor and low total harmonic distortion.
(3) By controlling the duty ratio of the driving pulse, all switching tubes in the power supply can work in a soft switching state.
Drawings
FIG. 1 is a schematic diagram of a high power factor bipolar current source dielectric barrier discharge power supply according to the present utility model;
FIG. 2 is an equivalent circuit diagram of the pulse excitation generating circuit provided by the utility model;
FIG. 3 is a timing diagram of the driving of the switching tube of the pulse excitation generating circuit according to the present utility model;
fig. 4 is an equivalent circuit diagram of an operation mode in a half operation period of the pulse excitation generating circuit provided by the utility model;
fig. 5 is an equivalent circuit diagram of the power factor correction circuit provided by the utility model;
fig. 6 is a waveform diagram of the power factor correction circuit according to the present utility model.
The utility model will be described more fully hereinafter with reference to the accompanying drawings and preferred embodiments in order to facilitate an understanding of the utility model, but the scope of the utility model is not limited to the following specific embodiments.
Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present utility model.
Detailed Description
The utility model will be described more fully hereinafter with reference to the accompanying drawings and preferred embodiments in order to facilitate an understanding of the utility model, but the scope of the utility model is not limited to the following specific embodiments.
Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present utility model.
Example 1:
as shown in fig. 1, the present utility model provides a high-power factor bipolar current source type dielectric barrier discharge power supply, wherein the power supply mainly comprises a power factor correction circuit and a pulse excitation generation circuit, and is characterized by comprising: the power supply comprises an alternating current power supply, a first diode, a second diode, a third diode, a fourth diode, an inductor, a step-up transformer with a center tap, a first switching tube and a second switching tube. The first end of the alternating current power supply is respectively connected with the anode of the first diode and the cathode of the third diode; the second end of the alternating current power supply is respectively connected with the anode of the second diode and the cathode of the fourth diode; the cathode of the first diode is respectively connected with the cathode of the second diode and the first end of the inductor; the anode of the third diode is respectively connected with the anode of the fourth diode, the first end of the first switching tube and the first end of the second switching tube; the second end of the inductor is connected with a center tap of a primary coil of the step-up transformer; the second end of the first switching tube is connected with the first end of the primary coil of the step-up transformer; the second end of the second switching tube is connected with the second end of the primary coil of the step-up transformer; the first end of the secondary coil of the step-up transformer is connected with the high-voltage electrode of the dielectric barrier discharge load; and the second end of the secondary coil of the step-up transformer is connected with the low-voltage electrode of the dielectric barrier discharge load.
In this embodiment, the first switching tube is the same type as the second switching tube.
In this embodiment, the operating frequencies of the first switching tube and the second switching tube are equal and the duty ratios of the driving signals of the first switching tube and the driving signals of the second switching tube are equal.
In this embodiment, the duty ratio D of the first switching tube and the second switching tube ranges from: d is more than or equal to 0.5 and less than 1.
An equivalent circuit diagram of the pulse excitation generating circuit is shown in fig. 2. Wherein i is S Is a current source S 1 And S is 2 A first switching tube and a second switching tube respectively, i 1 And i 2 Current through the first and second switching tube power, N P And N S Winding turns, L, of primary and secondary sides of the transformer, respectively s1 、L s2 Leakage inductance of primary coil of transformer, L m1 、L m2 Is the excitation inductance of the primary coil of the transformer. C (C) d And R is d Equivalent capacitance and equivalent resistance of DBD load, i DBD And u DBD DBD load current and load voltage, respectively.
In this embodiment, the switching transistor driving timing for controlling the circuit shown in fig. 2 is shown in fig. 3. As can be seen from fig. 3, the operating frequencies of the first switching tube and the second switching tube are equal and the duty ratios of the driving signals of the first switching tube and the driving signals of the second switching tube are equal. In a positive half switching period, the working modes of the system can be divided into the following two modes.
Modality 1 (t) 0 -t 1 ): this stage is a voltage rising mode, as shown in fig. 4 (a), in which the first switching tube and the second switching tube are turned on simultaneously for the first time, and the ac power is transferred to the dielectric barrier discharge load through the step-up transformerAnd (3) energy is input, and the excitation inductance of the step-up transformer is in an energy storage state.
Modality 2 (t) 1 -t 2 ): this phase is a voltage stabilizing mode, as shown in fig. 4 (b), in which the first switching tube is turned on and the second switching tube is turned off. The alternating current power supply transmits energy to the dielectric barrier discharge load through the transformer, the exciting inductance of the primary coil of the transformer connected with the first switching tube is in an energy storage state, the exciting inductance of the primary coil of the transformer connected with the second switching tube is in a discharge state, and the voltage of the dielectric barrier discharge load is maintained stable.
Assuming that the duty ratio of the first switching tube and the second switching tube is D, and the range of D is: d is more than or equal to 0.5 and less than 1, and the working modes of the positive half cycle and the negative half cycle of the system are consistent when the system works in a steady state.
Taking the positive half cycle as an example, the excitation characteristics of the driving circuit are analyzed.
When the system is in steady state operation, equivalent circuits of the mode 1 and the mode 2 are shown in fig. 4, and the circuit constraint equations of the mode 1 and the mode 2 are (R d Smaller and ignored):
wherein,,
simultaneous solving to obtain:
voltage peak U of DBD load m :
Average rate of rise of voltage:
where f is the switching frequency of the system. As can be seen from the expressions of the voltage peak value and the voltage rising rate, factors influencing the excitation pulse characteristics are the switching frequency, the excitation inductance and leakage inductance of the transformer, the transformation ratio N of the transformer and the equivalent inductance C of the dielectric barrier discharge load d And a current source. When a system is determined, the excitation inductance and leakage inductance of the transformer, the transformation ratio N of the transformer and the equivalent inductance C of the dielectric barrier discharge load d It is determined that the system can adjust the voltage peak and the voltage rise rate by adjusting the frequency of the switching tube to achieve the desired effect.
In this embodiment, an equivalent circuit of the power factor correction circuit is shown in fig. 5. Uncontrollable rectifier bridge input voltage u in Output current i in And a current i flowing through the inductance L S The operational waveform diagram of (a) is shown in fig. 6.
From kirchhoff's law:
and (3) solving to obtain:
wherein,,
current i flowing through inductance L S The effective values of (2) are:
where λ is the power factor of the power supply:
is consumed in the equivalent resistance R under the premise of not considering the loss eq The power is as follows:
the combination of the two above formulas can be obtained:
as can be seen from the above expression, the factor affecting the power factor is the impedance angle of the equivalent circuit. When a system determines, the power of the dielectric barrier discharge load and the power frequency alternating voltage are determined, the equivalent resistance of the equivalent circuit can be determined according to the set power factor index, and the corresponding inductance value can be obtained by the power factor expression, so that the system can correct the power factor by adjusting the inductance value, and the expected effect is achieved.