A high-voltage sinusoidal power supply for dielectric barrier discharge

Abstract

This invention relates to a high-voltage sinusoidal power supply for dielectric barrier discharge, belonging to the field of plasma power supply technology. The high-voltage sinusoidal power supply includes an inverter unit and a load connected in series. The inverter unit also has an oscillation unit connected in series. The oscillation unit includes an energy storage capacitor and a first switching transistor. The energy storage capacitor and the first switching transistor are connected in series to a DC power supply. A resonant inductor and a second switching transistor are connected in parallel across the energy storage capacitor. The primary winding of a first transformer is connected in parallel across the resonant inductor. The secondary winding of the first transformer is connected in series with the inverter unit. This invention obtains a high-voltage sinusoidal wave with peak oscillation by superimposing high-frequency oscillations onto the sinusoidal wave output by an existing high-voltage sinusoidal power supply. This concentrates the high energy of the improved high-voltage sinusoidal power supply at the peak of the sinusoidal wave, providing instantaneous high-energy output. The high-energy output of the high-voltage sinusoidal power supply enables the reaction generating nitrogen and oxygen reactive particles to proceed efficiently, thereby improving the generation efficiency of nitrogen and oxygen reactive particles.

Description

Technical Field

[0001] This invention relates to a high-voltage sinusoidal power supply for dielectric barrier discharge, belonging to the field of plasma power supply technology. Background Technology

[0002] Dielectric barrier discharge (DBD) is a gas discharge phenomenon in which an insulating dielectric is inserted into the discharge space. When the insulating dielectric is air, it is called air dielectric barrier discharge. Air dielectric barrier discharge technology is favored due to its readily available materials, uniform discharge characteristics, and high stability. It can effectively generate a large number of nitrogen-oxygen reactive species (RONS), which have important applications in energy conversion, environmental protection, and biomedicine. To increase the yield of these reactive species, the power density of the plasma power source can be adjusted. For example, different excitation power sources can be selected, and the discharge intensity of the plasma and the level of reactive species generated can be adjusted by changing the power of the excitation power source. Specifically, as the power of the excitation power source increases, the energy of electrons in the plasma increases, leading to more collisions between electrons and other particles, accelerating the physical and chemical reaction rates within the plasma, thereby increasing the concentration of reactive species (such as free radicals and ions).

[0003] However, for air barrier discharge, continuously increasing the power density may lead to a change in the discharge mode, which significantly affects the types of gaseous products. Air barrier discharge can be classified into two modes based on its main gaseous products: ozone-producing and nitrogen oxide-producing. With increasing power density, the discharge mode may shift from ozone-producing to nitrogen oxide-producing, and the main products change from ozone to nitric oxide (NO) and nitrogen dioxide (NO2). Therefore, because power density has a significant impact on the air barrier discharge mode, the power supply used for this discharge must have high stability to avoid undesirable mode transitions during discharge.

[0004] In industrial applications, air barrier discharge (DBD) is a form of plasma discharge. The power supplies that excite DBD are mainly divided into two categories: sinusoidal power supplies and pulsed power supplies. Sinusoidal power supplies are typically based on AC resonant circuit designs and can be further subdivided into voltage-type and current-type resonant power supplies depending on the type of DC power supply. Pulsed power supplies, on the other hand, can be classified into DC-type, Marx-type, and voltage-multiplying types, depending on the principle of pulse generation.

[0005] The existing sinusoidal power supply includes a series-connected inverter unit and a load. The inverter unit includes a full-bridge inverter, whose DC terminal is connected to a DC power supply. The AC terminal of the full-bridge inverter is connected to a series-connected inductor and capacitor. The primary winding of a transformer is connected in parallel to the capacitor, and the secondary winding of the transformer is connected in series with the load. This sinusoidal power supply performs poorly in terms of both nitrogen and oxygen reactive particle generation efficiency and energy efficiency. The specific reasons are as follows:

[0006] 1. The root cause of low efficiency in the generation of nitrogen and oxygen reactive particles:

[0007] (1) Limitations of working principle: The sinusoidal power supply generates a continuous sinusoidal signal. When used to excite nitrogen and oxygen reactive particles, its energy transfer mode is relatively simple and slow. In the process of generating nitrogen and oxygen reactive particles, a specific energy excitation mode is required to promote the chemical reaction or physical process. However, the sinusoidal power supply may not be able to provide enough energy pulses or specific frequency excitation to efficiently excite the generation of nitrogen and oxygen reactive particles.

[0008] (2) Disconcentrated energy distribution: The energy of a sinusoidal power supply is uniformly distributed throughout the cycle, lacking the instantaneous high energy output of a pulsed power supply. For some reaction systems that require high-energy excitation to effectively generate nitrogen and oxygen reactive particles, the energy of a sinusoidal power supply is insufficient to enable the reaction to proceed efficiently, resulting in low production efficiency.

[0009] 2. The root cause of the low energy efficiency of nitrogen and oxygen reactive particles:

[0010] (1) Energy transmission loss: During the energy transmission process, the sinusoidal power supply may generate a lot of heat loss in the transmission line or load due to its continuity. Especially in the case of long-distance transmission or high impedance load, the energy loss is more obvious, resulting in a reduction in the actual energy used for effective operation and a decrease in energy efficiency.

[0011] (2) Harmonic distortion: Actual sinusoidal power supplies often have harmonic distortion, that is, the output voltage or current waveform contains high-order harmonic components. These harmonic components not only cannot be effectively used for the operation of the load, but also increase the energy loss and heat generation of the system, reducing the overall energy efficiency.

[0012] The existing pulse power supplies have high manufacturing and maintenance costs, large equipment size, poor stability, and limited service life. The specific reasons are as follows:

[0013] 1. The root cause of high manufacturing and maintenance costs:

[0014] (1) Complex design and manufacturing process: Pulse power supplies require precise control of the charging and discharging process of capacitors to achieve stable pulse current or voltage output, which involves complex circuit design and high-precision components. For example, in order to generate nanosecond-level pulses, special high-speed switching devices and precision control circuits are required, and the design and manufacturing costs of these devices and circuits are high.

[0015] (2) High requirements for components: Pulse power supplies operate at high voltage, high current and high frequency, which places high demands on the voltage resistance, shock resistance and high frequency performance of components. For example, high voltage capacitors, high frequency transformers and high speed semiconductor devices are required. These components are relatively expensive and are easily damaged during use, which increases maintenance costs.

[0016] 2. The root cause of the large size of the equipment:

[0017] (1) Energy storage component requirements: In order to achieve pulse output, the pulse power supply needs to be equipped with large energy storage components, such as capacitor banks or inductors. These energy storage components are not only large in size but also heavy in weight, which increases the size and weight of the entire device.

[0018] (2) Complex heat dissipation design: Pulse power supplies generate a lot of heat during operation, requiring a complex heat dissipation system to ensure normal operation of the equipment. For example, large-area heat sinks, fans or water cooling systems are needed, which also occupy a lot of space and increase the size of the equipment.

[0019] 3. The root cause of poor stability:

[0020] (1) Pulse parameter fluctuations: The output pulse parameters of the pulse power supply, such as pulse width, amplitude and frequency, are easily affected by factors such as power supply voltage fluctuations, load changes and ambient temperature. For example, when the power supply voltage changes suddenly, it may cause instability in pulse width and amplitude, affecting the normal operation of the equipment.

[0021] (2) Electromagnetic interference: During operation, pulse power supplies generate strong electromagnetic interference. These interference signals may affect their own control circuits and other electronic devices, leading to system instability. For example, the high-frequency electromagnetic waves generated by the pulse power supply may interfere with nearby communication equipment or control systems, affecting their normal operation.

[0022] 4. The root cause of limited service life:

[0023] (1) Component aging: Components in pulse power supplies, such as capacitors, semiconductor devices and transformers, are prone to aging and damage under long-term high voltage, high current and high frequency operating conditions. For example, the electrolyte in capacitors will gradually dry out over time, resulting in a decrease in capacitance and an increase in leakage current, which will ultimately affect the performance and lifespan of the equipment.

[0024] (2) Switching device losses: The switching devices in the pulse power supply generate a lot of heat and electrical stress during frequent switching, which leads to device fatigue and damage. For example, high-frequency switching devices generate a certain amount of energy loss and heat during each switching process, which will lead to a decline in device performance and a shortened lifespan over a long period of time.

[0025] In summary, the aforementioned problems limit their widespread application. Summary of the Invention

[0026] The purpose of this invention is to provide a high-voltage sinusoidal power supply for dielectric barrier discharge, in order to solve the problem of low generation efficiency of nitrogen and oxygen reactive particles caused by the non-concentrated energy distribution of existing high-voltage sinusoidal power supplies.

[0027] To achieve the above objectives, the present invention includes:

[0028] The present invention provides a high-voltage sinusoidal power supply for dielectric barrier discharge, comprising an inverter unit and a load connected in series. The inverter unit is also connected in series with an oscillation unit. The oscillation unit includes an energy storage capacitor and a first switching transistor. The energy storage capacitor and the first switching transistor are connected in series to a DC power supply. A resonant inductor and a second switching transistor are connected in parallel across the energy storage capacitor. The primary side of a first transformer is connected in parallel across the resonant inductor. The secondary side of the first transformer is connected in series with the inverter unit.

[0029] The energy storage capacitor is used to store energy and resonate with the resonant inductor to generate oscillation. The first switching transistor is used to control the start time of the oscillation, the second switching transistor is used to control the oscillation time, and the first transformer is used to increase the oscillation voltage. The high-voltage sine wave output by the inverter unit and the high-frequency oscillation output by the oscillation unit are superimposed to obtain the high-voltage sine wave with peak oscillation.

[0030] Furthermore, the first switching transistor is a field-effect transistor.

[0031] Furthermore, the second switching transistor is a field-effect transistor.

[0032] Furthermore, the inverter unit includes an inverter, the DC terminal of which is used to connect to a DC power supply, and the AC terminal of the inverter is connected to a series-connected filter inductor and filter capacitor. The primary side of the second transformer is also connected in parallel to the filter capacitor, and the secondary side of the second transformer is connected in series with the load.

[0033] Furthermore, the inverter employs a unipolar frequency multiplication sinusoidal pulse width modulation control strategy.

[0034] Furthermore, the inverter adopts a full-bridge inverter.

[0035] Furthermore, the load includes a load resistor and a load capacitor connected in parallel.

[0036] The beneficial effects of this invention are:

[0037] This invention is an improved version, providing a high-voltage sinusoidal power supply for dielectric barrier discharge. By superimposing high-frequency oscillations onto the sinusoidal wave output by an existing high-voltage sinusoidal power supply, a high-voltage sinusoidal wave with peak oscillations is obtained. This changes the original single and slow energy transfer mode, enabling the improved high-voltage sinusoidal power supply to provide specific frequency excitation or instantaneous high-frequency excitation to efficiently excite the generation of nitrogen and oxygen reactive particles. Simultaneously, the high energy of this improved high-voltage sinusoidal power supply is concentrated at the peak of the sinusoidal wave to provide instantaneous high-energy output. For certain reaction systems that require high-energy excitation to effectively generate nitrogen and oxygen reactive particles, the high-energy output of the high-voltage sinusoidal power supply can make the reaction for generating nitrogen and oxygen reactive particles proceed efficiently, thereby improving the generation efficiency of nitrogen and oxygen reactive particles.

[0038] The improved high-voltage sinusoidal power supply specifically includes an inverter unit and a load connected in series. The inverter unit, used to output a high-voltage sinusoidal wave, is also connected in series with an oscillation unit, used to output high-frequency oscillation. The oscillation unit includes an energy storage capacitor and a first switching transistor. The energy storage capacitor and the first switching transistor are connected in series to a DC power supply. A resonant inductor and a second switching transistor are connected in parallel across the energy storage capacitor. The primary side of a first transformer is connected in parallel across the resonant inductor. The secondary side of the first transformer is connected in series with the inverter unit. The energy storage capacitor is used to store energy and resonate with the resonant inductor to generate oscillation. The first switching transistor is used to control the start time of the oscillation, the second switching transistor is used to control the oscillation time, and the first transformer is used to increase the oscillation voltage. The high-voltage sinusoidal wave output by the inverter unit and the high-frequency oscillation output by the oscillation unit are superimposed to obtain a high-voltage sinusoidal wave with peak oscillation. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the circuit unit connection in a high-voltage sinusoidal power supply;

[0040] Figure 2 This is the circuit topology diagram of a high-voltage sinusoidal power supply;

[0041] Figure 3 It is a measured voltage waveform diagram of a high-voltage sinusoidal power supply;

[0042] Figure 4 It is a graph showing the change in the concentration of the main gaseous products when a high-voltage sinusoidal power supply is used for dielectric barrier discharge.

[0043] Explanation of reference numerals in the attached figures:

[0044] Vs1 1. First DC power supply; Q1, first switching transistor; Q2, second switching transistor; C1, energy storage capacitor; L1, resonant inductor; T1, first transformer; V s2 Second DC power supply; S1, third switch; S2, fourth switch; S3, fifth switch; S4, sixth switch; L2, filter inductor; C2, filter capacitor; T2, second transformer; R L , load resistance; C L , load capacitor. Detailed Implementation

[0045] To address the problems in the background art, this invention concentrates the high energy of the high-voltage sinusoidal power supply at the peak of the sinusoidal wave to provide instantaneous high energy output. The high energy output of the high-voltage sinusoidal power supply enables the reaction that generates nitrogen and oxygen reactive particles to proceed efficiently, thereby improving the generation efficiency of nitrogen and oxygen reactive particles.

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] An embodiment of a high-voltage sinusoidal power supply for dielectric barrier discharge:

[0048] A high-voltage sinusoidal power supply for dielectric barrier discharge, belonging to the field of discharge plasma technology, specifically relates to the design of a high-voltage sinusoidal power supply with superimposed high-frequency oscillations for dielectric barrier discharge, such as... Figure 1 As shown, the high-voltage sinusoidal power supply includes a load connected in series, an inverter unit for outputting a high-voltage sinusoidal wave, and an oscillation unit for outputting a high-frequency oscillation.

[0049] Among them, such as Figure 2 As shown, the load includes a load resistor R connected in parallel. L and load capacitance C L .

[0050] The oscillation unit includes a first switch Q1, a second switch Q2, an energy storage capacitor C1, a resonant inductor L1, and a first transformer T1. The energy storage capacitor C1 and the first switch Q1 are connected in series to the first DC power supply V. s1 The energy storage capacitor C1 is connected in parallel with a series resonant inductor L1 and a second switch Q2. The primary side of the first transformer T1 is also connected in parallel with the resonant inductor L1. The secondary side of the first transformer T1 is connected in series with the inverter unit.

[0051] Among them, the energy storage capacitor C1 is used to store energy and resonate with the resonant inductor L1 to generate oscillation; the first switch Q1 is used to control the start time of the oscillation; the second switch Q2 is used to control the oscillation time; the first transformer T1 is used to provide a high turns ratio to increase the oscillation voltage; and the first DC power supply V... s1Used to provide energy to the load; the high-voltage sine wave output by the inverter unit and the high-frequency oscillation output by the oscillation unit are superimposed to obtain the high-voltage sine wave with peak oscillation.

[0052] The inverter unit can use any existing inverter unit. Taking one as an example, the inverter unit includes an inverter, and the DC terminal of the inverter is used to connect to a second DC power supply V. s2 The inverter's AC terminal is connected to a series-connected filter inductor L2 and filter capacitor C2. The primary side of the second transformer T2 is also connected in parallel to the filter capacitor C2. The secondary side of the second transformer T2 is connected in series with the load, that is, the secondary side of the first transformer T1 and the secondary side of the second transformer T2 are connected in series with the load.

[0053] Among them, the second DC power supply V s2 The inverter is used to provide energy to the load and convert DC to AC. The filter inductor L2 and filter capacitor C2 work together to form an LC filter, which is used to smooth the output waveform. The second transformer T2 is used to provide a high turns ratio.

[0054] This invention generates LC parallel resonance by controlling the switching of the switching transistor in the oscillation unit used to generate high-frequency high-voltage oscillation. The LC parallel resonance is superimposed on the high-voltage sine wave generated by the inverter unit, thereby realizing the output of a high-voltage sine wave with high-frequency oscillation superimposed at the peak of the high-voltage sine wave.

[0055] Specifically, the first switching transistor Q1 is a field-effect transistor, but other existing switching transistors can also be used.

[0056] Specifically, the second switch Q2 is a field-effect transistor, but other existing switch transistors can also be used.

[0057] Specifically, the inverter employs a unipolar frequency multiplication sinusoidal pulse width modulation strategy.

[0058] Specifically, the inverter adopts a full-bridge inverter, which includes an H-bridge structure composed of four switching transistors: the third switching transistor S1, the fourth switching transistor S2, the fifth switching transistor S3, and the sixth switching transistor S4. All four switching transistors can be field-effect transistors. Of course, the inverter can also adopt a half-bridge inverter.

[0059] The high-voltage sinusoidal power supply of this invention is used to generate a high-voltage sinusoidal wave with peak oscillation. The basic principle for generating this waveform is: when the first switch Q1 is turned on, the first DC power supply V... s1 The energy storage capacitor C1 is charged; when the second switch Q2 is turned on, the energy storage capacitor C1 and the resonant inductor L1 form an LC parallel resonance; after the resonance is boosted by the first transformer T1, it is superimposed with the high-voltage sine wave generated by the inverter unit to obtain a high-voltage sine wave with peak oscillation.

[0060] The oscillation unit is used to generate high-frequency oscillations. Within a complete switching cycle, the oscillation unit has eight operating modes, four in the positive half-cycle and four in the negative half-cycle. The four operating modes (modes five to eight) in the positive half-cycle are the same as those in the negative half-cycle. The four operating modes (modes one to four) in the positive half-cycle are described as follows:

[0061] Mode 1: First switch Q1 is turned on, second switch Q2 is turned off, and the first DC power supply V... s1 Charge the energy storage capacitor C1;

[0062] Mode 2: The first switch Q1 is on and both the second switch Q2 are off, and the voltage across the energy storage capacitor C1 remains at V. s1 The voltage remains unchanged. At this time, the drain-source voltage of the first switching transistor Q1 is zero.

[0063] Mode 3: The first switch Q1 is off, the second switch Q2 is on, the energy storage capacitor C1 and the resonant inductor L1 resonate in parallel to generate oscillation, and the peak value of the output oscillation voltage is NV. s1 The oscillation frequency is Where N is the ratio of the number of turns of the secondary winding to the number of turns of the primary winding of the first transformer T1, and V s1 L1 is the voltage value of the first DC power supply, L1 is the inductance value of the resonant inductor, and C1 is the capacitance value of the energy storage capacitor.

[0064] Mode 4: Both the first switch Q1 and the second switch Q2 are in the off state. Due to the loss of some energy during the oscillation, the voltage of the energy storage capacitor C1 drops slightly and remains unchanged.

[0065] The inverter unit generates a high-voltage sine wave. The H-bridge of the inverter unit employs a unipolar frequency-doubling SPWM modulation strategy to generate the sine wave, and it has four different operating states in each switching cycle. This modulation strategy uses two inverted triangular waves v. c With -v c As a carrier signal, the sine wave v r As a modulated wave, output control is achieved by adjusting the modulation index.

[0066] Among these, the unipolar frequency-doubled SPWM modulation strategy, compared to unipolar and bipolar SPWM modulation strategies, produces an output waveform with the fewest harmonic components and the highest harmonic order, thus allowing for the use of smaller filters. Furthermore, in plasma applications, where power supply frequencies are typically high, reaching several thousand to tens of kilohertz, the carrier frequency needs to be increased to several hundred kilohertz to ensure the precision of the output waveform, posing a greater challenge to the processor's clock speed. Therefore, to reduce processor load and improve waveform quality, the unipolar frequency-doubled SPWM modulation strategy is chosen. This modulation strategy not only optimizes the output waveform performance but also improves the efficiency and stability of the entire system.

[0067] The optimization of output waveform performance is reflected in the following two aspects:

[0068] 1) Higher output frequency: Unipolar frequency-doubled SPWM doubles the output frequency by adding a frequency multiplication process to the unipolar SPWM. For example, at the same carrier frequency, the output frequency of unipolar frequency-doubled SPWM is twice that of unipolar SPWM. This means that the output waveform is closer to a sine wave, with less harmonic content and higher waveform quality.

[0069] 2) Reduce high-frequency harmonics: Due to the increase in output frequency, unipolar frequency-doubled SPWM can filter out high-frequency harmonics more effectively, thereby reducing harmonic distortion in the output waveform. This makes the output voltage closer to the ideal sine wave and improves power quality.

[0070] The improvement in system efficiency is reflected in the following two aspects:

[0071] 1) Reduced switching losses: Unipolar frequency-doubled SPWM reduces the number of switching operations by optimizing the switching strategy. For example, in unipolar frequency-doubled SPWM, the switching frequency is higher, but the actual switching losses are lower because the switching device only performs one switching operation per cycle. This reduces the system's energy consumption and improves overall efficiency.

[0072] 2) Reduced filter size: Due to the increased output frequency, unipolar frequency-doubled SPWM can achieve the same filtering effect using a smaller filter. The smaller filter not only reduces cost but also decreases the system's size and weight, further improving system efficiency.

[0073] The improvement in system stability is reflected in the following two aspects:

[0074] 1) Better dynamic response: The high output frequency of unipolar frequency-doubled SPWM enables the system to respond faster to load changes and has better dynamic performance. This allows the system to adjust its output more quickly and maintain stable operation when faced with load changes.

[0075] 2) Reduced electromagnetic interference: Due to the increased output frequency and reduced switching frequency, unipolar frequency-doubled SPWM generates lower electromagnetic interference (EMI). This helps improve the system's immunity to interference and enhances system stability.

[0076] The selection criteria for filters under different sinusoidal pulse width modulation strategies are as follows:

[0077] For unipolar SPWM, LC filters, which are filter circuits composed of inductors and capacitors, are typically chosen. The selection criteria are as follows: the voltage waveform of a unipolar SPWM output varies within only one polarity range per cycle, for example, only between 0 and +Udc. This waveform contains many low-order harmonics, requiring filters to remove these harmonics and make the output voltage closer to a sine wave. LC filters can effectively filter out low-order harmonics and also have the advantages of simple structure and low cost.

[0078] For bipolar SPWM, an LC filter can also be used, but in some cases, a more complex filter, such as an LCL filter, may be required. The selection criteria are as follows: the voltage waveform output by a bipolar SPWM has two polarity changes within one cycle, for example, from +Udc to -Udc. Although this waveform has relatively low harmonic content, its low output frequency necessitates a filter to remove residual low-order harmonics. LCL filters offer better filtering performance than LC filters, effectively removing low-order harmonics, but their structure is more complex and their cost is higher.

[0079] For unipolar frequency-doubled SPWM, a smaller LC filter can be selected. The selection criteria are as follows: Unipolar frequency-doubled SPWM doubles the output frequency by adding a frequency multiplication process to the unipolar SPWM. Due to the higher output frequency, the filter design can be more compact and smaller. A smaller LC filter can meet the filtering requirements, while also offering advantages such as low cost and light weight.

[0080] The similarities among the three modulation strategies described above are as follows:

[0081] Basic principle: All three modulation strategies are based on sinusoidal pulse width modulation (SPWM) technology, which controls the amplitude and frequency of the output voltage by adjusting the pulse width.

[0082] Application scenarios: They are widely used in power electronics fields such as inverters and motor control to achieve the regulation and control of AC power.

[0083] The control objectives are all to make the output voltage waveform closer to a sine wave, improve power quality, and reduce harmonic interference to the power grid.

[0084] The differences between the three modulation strategies mentioned above are as follows:

[0085] 1) Output waveform:

[0086] Unipolar SPWM: The output waveform changes only within one polarity range in one cycle, for example, only between 0 and +Udc, and the waveform is relatively simple.

[0087] Bipolar SPWM: The output waveform has two polarity changes within one cycle, such as from +Udc to -Udc. The waveform is closer to a sine wave and has a lower harmonic content.

[0088] Single-pole frequency-doubled SPWM: Through frequency doubling, the frequency of the output waveform is doubled, resulting in better waveform quality and less harmonic content.

[0089] 2) Switching frequency:

[0090] Unipolar SPWM: The switching frequency is relatively low, the switching loss is small, but the output voltage ripple is large.

[0091] Bipolar SPWM: Higher switching frequency, greater switching losses, but higher output voltage quality.

[0092] Single-pole frequency-doubled SPWM: The switching frequency is relatively high, but due to the frequency multiplication process, the actual output frequency is even higher, and the filter size is smaller.

[0093] 3) Filter requirements:

[0094] Unipolar SPWM: Requires a large LC filter to filter out low-order harmonics.

[0095] Bipolar SPWM: May require more complex filters, such as LCL filters, to filter out residual low-order harmonics.

[0096] Single-pole frequency-doubled SPWM: It can use a smaller LC filter, which has good filtering effect and low cost.

[0097] 4) Efficiency and cost:

[0098] Unipolar SPWM: High efficiency and low cost, but the output voltage ripple is large.

[0099] Bipolar SPWM: Relatively low efficiency and high cost, but high output voltage quality.

[0100] Single-pole frequency-doubling SPWM: It has good overall performance, which can increase the output frequency and use a smaller filter, and has advantages in both cost and efficiency.

[0101] This invention provides a high-voltage sinusoidal power supply, comprising an oscillation unit, an inverter unit, and a load. The oscillation unit provides a high-frequency oscillation signal, and the inverter unit provides a high-amplitude sinusoidal signal. Since air dielectric barrier discharge can be considered as an RC load, an RC load is used as the output load driven by the power supply. The oscillation unit, inverter unit, and RC load are connected in series to form a high-voltage sinusoidal power supply. By superimposing high-frequency oscillations, the stability and uniformity of the output energy of the high-voltage sinusoidal power supply with superimposed high-frequency oscillations are enhanced, thereby solving the problems of low generation efficiency and energy efficiency of existing plasma power supplies for nitrogen and oxygen reactive particles, high manufacturing and maintenance costs, large equipment size, poor stability, and limited service life.

[0102] Because the high-voltage sinusoidal power supply of this invention has small harmonic components and high harmonic orders in its output waveform, the required filter size is significantly reduced, which directly reduces the cost of filter procurement, production, and installation. In high-frequency applications such as plasma, although the carrier frequency requirements are extremely high, this modulation strategy can alleviate the processor's clock speed pressure, avoid high expenses due to processor upgrades, and at the same time ensure efficient and stable system operation, reduce economic losses caused by downtime due to failures, and improve overall production efficiency.

[0103] The measured voltage waveform of the high-voltage sinusoidal power supply of this invention is as follows: Figure 3 As shown, this power supply can simultaneously output a sine wave and superimpose a high-frequency oscillation. The output parameters of this power supply are: sine wave amplitude of 4kV and frequency of 5kHz, and high-frequency oscillation amplitude of 2kV and frequency of 300kHz. Figure 3 The experimental waveform diagrams of the overall output of the oscillation unit, inverter unit, and high-voltage sinusoidal power supply are shown.

[0104] Specifically, Figure 3 (a) shows that, at the first DC power supply V s1 100V, second DC power supply V s2 The voltage is 0V and the load resistance is R. L Under the condition of 50kΩ, the output V of the oscillation unit o1 The oscillation amplitude reached 2kV and the oscillation frequency was 148.7kHz. The waveform obtained from the experiment basically matched the theoretical prediction. Figure 3 As shown in (b), at the first DC power supply V s1 0V, second DC power supply V s2 100V and load resistance R L Under the same 50kΩ condition, the switching frequency of the third switch S1 to the sixth switch S4 reaches 300kHz, and the output V of the inverter unit... o2 The sine wave is relatively smooth. Figure 3 (c) shows that, in the first DC power supply V s1 Second DC power supply V s2Both are 100V, and the load resistance is R. L With the same 50kΩ, the total output V of the high-voltage sinusoidal power supply o The waveform is a sine wave superimposed with high-frequency oscillations. The peak-to-peak value of the sine wave is 4kV, and the peak value of the oscillation is 2kV. The switching frequency determines the frequency of the output waveform.

[0105] The time evolution curves of the concentrations of the main gaseous products when the high-voltage sinusoidal power supply of this invention is used for dielectric barrier discharge are shown below. Figure 4 As shown.

[0106] Figure 4 Sections (a), (b), and (c) illustrate the low-power state, i.e., a power density of 0.125 W / cm². 2 Under the condition that the concentration of the main gaseous products changes with time, the discharge mode is the ozone mode. Driven by two power sources, a conventional sinusoidal power source and a sinusoidal power source with superimposed high-frequency oscillation, the plasma is excited at the beginning of the discharge (time t = 0 seconds), and ozone (O3) is rapidly generated, such as... Figure 4 As shown in (a), the ozone concentration continuously increases over the period from 0 to 100 seconds, regardless of the power source used for excitation, and then decreases slightly. With a conventional sinusoidal power source, the steady-state concentration of ozone (O3) at 300 seconds is 343.9 ppm, while with a high-voltage sinusoidal power source superimposed with high-frequency oscillations, the steady-state concentration is 294.1 ppm. The steady-state concentration of ozone excited by the conventional sinusoidal power source is 16.9% higher than that excited by the high-voltage sinusoidal power source superimposed with high-frequency oscillations, and the latter shows a more significant decrease in ozone concentration.

[0107] like Figure 4 As shown in (b), the temporal variation trend of nitrogen pentoxide (N2O5) is opposite to that of ozone (O3). In the time period from 0 to 300 seconds, the maximum concentration of nitrogen pentoxide (N2O5) reached 9.1 ppm when using a superimposed oscillating sinusoidal power supply, while the maximum concentration of nitrogen pentoxide (N2O5) when using a conventional sinusoidal power supply was 7 ppm. The maximum concentration of nitrogen pentoxide excited by the superimposed oscillating sinusoidal power supply was 30% higher than that excited by the conventional sinusoidal power supply.

[0108] like Figure 4 As shown in (c), the temporal variation trend of nitrous oxide (N2O) is opposite to that of ozone (O3). In the time period from 0 to 300 seconds, the maximum concentration of nitrous oxide (N2O) is 10.3 ppm when using a superimposed oscillating sinusoidal power supply, while the maximum concentration of nitrous oxide (N2O) is 8.4 ppm when using a conventional sinusoidal power supply. The maximum concentration of nitrous oxide excited by the superimposed oscillating sinusoidal power supply is 22.6% higher than that excited by the conventional sinusoidal power supply.

[0109] Figure 4 Parts (d), (e), (f), and (g) illustrate the high-power state, i.e., a power density of 0.5 W / cm². 2 The discharge mode is the nitrogen oxide mode, which describes the change in the concentration of the main gaseous products over time. In the nitrogen oxide mode, the ozone (O3) concentration excited by both the conventional sinusoidal power supply and the sinusoidal power supply with superimposed high-frequency oscillation rises rapidly, reaches its peak within tens of seconds, and then quickly drops below the detection limit.

[0110] like Figure 4 As shown in (d), when excited by a superimposed oscillating sinusoidal power supply, the peak concentration of ozone (O3) is 186.5 ppm, while when excited by a conventional sinusoidal power supply, the maximum concentration of ozone (O3) is 154.2 ppm. The maximum concentration of ozone (O3) excited by the superimposed oscillating sinusoidal power supply is 20.9% higher than that excited by the conventional sinusoidal power supply, and it completely disappears at 140 seconds, while the ozone concentration excited by the conventional sinusoidal power supply disappears completely at 160 seconds. Therefore, the ozone concentration excited by the superimposed oscillating sinusoidal power supply disappears earlier than that excited by the conventional sinusoidal power supply, indicating that the superimposed oscillating sinusoidal power supply contributes to the rapid decay of ozone (O3). Figure 4 As shown in (e), the peak concentration of nitrogen dioxide (NO2) under superimposed oscillating sinusoidal power supply excitation is 7.1% higher than that under conventional sinusoidal power supply excitation; as Figure 4 As shown in (f), the peak concentrations of dinitrogen pentoxide (N₂O₅) are basically the same in both cases; as Figure 4 As shown in (g), the peak concentration of nitrous oxide (N₂O) under superimposed oscillating sinusoidal power supply excitation is 6.3% higher than that under traditional sinusoidal power supply excitation; therefore, it can be concluded that superimposed oscillating sinusoidal power supply is more conducive to the generation of nitrogen oxides. The power density depends on the discharge power and discharge area; increasing the discharge power and decreasing the discharge area both increase the power density, and vice versa.

Claims

1. A high-voltage sinusoidal power supply for dielectric barrier discharge, comprising an inverter unit and a load connected in series, characterized in that, The inverter unit is also connected in series with an oscillation unit, which includes an energy storage capacitor and a first switching transistor. The energy storage capacitor and the first switching transistor are connected in series to a DC power supply. A series resonant inductor and a second switching transistor are also connected in parallel across the energy storage capacitor. The primary side of the first transformer is also connected in parallel across the resonant inductor. The secondary side of the first transformer is connected in series with the inverter unit. The energy storage capacitor is used to store energy and resonate with the resonant inductor to generate oscillation. The first switching transistor is used to control the start time of the oscillation, the second switching transistor is used to control the oscillation time, and the first transformer is used to increase the oscillation voltage. The high-voltage sine wave output by the inverter unit is superimposed with the high-frequency oscillation output by the oscillation unit to obtain a high-voltage sine wave with peak oscillation.

2. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 1, characterized in that, The first switching transistor is a field-effect transistor.

3. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 1, characterized in that, The second switching transistor is a field-effect transistor.

4. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 1, characterized in that, The inverter unit includes an inverter, the DC terminal of which is connected to a DC power supply, and the AC terminal of the inverter is connected to a series-connected filter inductor and filter capacitor. The primary side of a second transformer is also connected in parallel to the filter capacitor, and the secondary side of the second transformer is connected in series with the load.

5. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 4, characterized in that, The inverter employs a unipolar frequency multiplication sinusoidal pulse width modulation control strategy.

6. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 4, characterized in that, The inverter is a full-bridge inverter.

7. The high-voltage sinusoidal power supply for dielectric barrier discharge according to claim 1, characterized in that, The load includes a load resistor and a load capacitor connected in parallel.

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