Small high-frequency adjustable ionization source power supply system

Abstract

The invention discloses a small high-frequency adjustable ionization source power supply system, and relates to the field of ionization source power supply systems. Comprising a control circuit, a voltage conversion circuit and an inversion driving circuit. The control circuit controls the voltage conversion circuit and the inverter drive circuit. The control circuit adopts a digital power supply control module, the digital power supply control module adopts a DSP2812 as a main control chip, 14 paths of PWM control signals are output at the same time through programming, and 14-path cascade debugging is carried out. The voltage conversion circuit adopts a power frequency isolation transformer mode and comprises a group of voltage regulators and a plurality of groups of isolation transformers, so that a plurality of paths of isolated 220V alternating current signals are output at the same time, and a 300V bus is provided for a subsequent inverter circuit after rectification; the inverter drive circuit inputs a switching signal and 300VDC and outputs a PWM waveform, and a magnetic coupling isolation chip is adopted in the inverter circuit; the driving chip adopts IR2103, the power device adopts a power MOS tube, and corresponding connection is carried out. The control precision is improved.

Description

Technical Field

[0001] The invention relates to the field of ionization source power supply systems, in particular to a small high-frequency adjustable ionization source power supply system. Background Art

[0002] According to the requirements for a dedicated power supply for a multi-channel strong polarization ionization source, a dedicated chip-based power supply for a multi-channel strong polarization ionization source based on variable voltage and variable frequency has the following characteristics: high voltage, high frequency, and adjustable.

[0003] First of all, the most direct and effective way to obtain high voltage is to use a large-ratio transformer to increase the commonly used 100-volt power supply voltage output to 60V~200kV. Generally, a transformer with a relatively large volume and weight is required. For applications proposed by this requirement, the high-voltage power supply based on traditional transformers cannot meet its requirements in terms of weight and volume.

[0004] In terms of higher output frequencies, they are generally generated through RC or LC sinusoidal oscillation circuits, or by using high-frequency square waves plus post-filtering. However, the LC sinusoidal oscillation circuit requires a relatively large inductor, and various oscillation circuits cannot accurately and conveniently adjust the frequency. These methods are obviously not feasible for the above requirements. The square wave voltage plus filtering method can easily and accurately adjust the frequency through digital circuits, but the quality of the output excitation signal cannot be guaranteed, especially in the process of frequency modulation, the hardware filter circuit cannot synchronously adjust the cutoff frequency, so the amplitude and waveform of the output voltage are difficult to guarantee. At the same time, the prerequisite for this method is to have a kV-level DC voltage as input, so this method is also not feasible.

[0005] In terms of adjustability, the required dedicated power supply requires that both the frequency and amplitude can be adjusted independently. Limited by the overall volume requirements of the power supply, it is obviously impossible to achieve real-time and controllable adjustment using traditional analog circuit devices and printed circuit boards. The control of frequency, amplitude and phase must be achieved through digital circuits. Therefore, it is necessary to improve the existing high-voltage source so that it can meet the requirements of a miniature high-frequency, adjustable high-voltage source. At the same time, the voltage adjustment operation is simple, which can meet the requirements of small internal space of the instrument and the use of different voltages by various modules. Summary of the invention

[0006] The present invention provides an improved small-sized high-frequency adjustable ionization source power supply system in order to solve the problem that it is not feasible to use traditional analog circuit devices and printed circuit boards to achieve real-time and controllable adjustment when designing a high-voltage, high-frequency, adjustable multi-channel strong polarization ionization source with a small volume and light weight, and a kV-level direct current voltage is required as an input.

[0007] Under the premise of avoiding the use of large and heavy transformers, the only feasible way to obtain a power supply with high voltage, frequency, amplitude and adjustable phase is to use digital circuit control to realize the superposition of multiple levels, that is, to increase the voltage value by combining multiple levels in series. The digital circuit controls the switching on and off time of the level, and then the different proportions of multiple levels in one cycle can be used to superimpose an approximately sinusoidal output waveform. At the same time, the voltage cycle can also be controlled by the clock frequency of the digital circuit, that is, the overall idea is to use digital circuits to replace analog circuits, which is similar to the reverse thinking of AD sampling, and is the direction of current industrial technology development. With its advantages of fast control speed and small size, digital power supply is expected to achieve miniaturization and lightweight of power supply. With the development of power electronics processes, technologies, and materials, the advantages and optimization space will become more obvious.

[0008] The present invention is realized by the following technical scheme: a small high-frequency adjustable ionization source power supply system, including a control circuit, a voltage conversion circuit and an inverter drive circuit; the control circuit controls the voltage conversion circuit and the inverter drive circuit. The control circuit adopts a digital power control module, and the digital power control module adopts DSP2812 as the main control chip. Through the programming, it simultaneously outputs 14 PWM control signals. The specific idea is: 14-way cascade debugging can be performed, and one output can be stacked to simulate the waveform of a sine wave, and the amplitude control experimental debugging can be performed, and it can also be divided into 7 cascades × 2 two-way approximate sine waves to adjust the phase difference between the two outputs. The voltage conversion circuit adopts the method of industrial frequency isolation transformer, including a group of voltage regulators and multiple groups of isolation transformers, so that multiple isolated 220V AC signals are output simultaneously, and the 300V bus is provided to the subsequent inverter circuit after rectification; the input end of the isolation transformer is connected to the voltage regulator to realize the amplitude adjustment of the rectified DC voltage. The inverter drive circuit inputs a switch signal and 300VDC and outputs a PWM waveform. The inverter circuit uses a magnetic coupling isolation chip, model ISO721; the drive chip uses IR2103, and the power device uses a power MOS tube, and corresponding connections are made.

[0009] The design of the present invention is based on a digital VVVF power supply solution, and its principle block diagram is as follows: Figure 1As shown in the figure, the working principle of the circuit is as follows: First, the boost module converts the DC voltage into multiple isolated voltages. Since it can adopt a more efficient conversion frequency and switching method, the boost module can increase the DC voltage of 12V to 48V to a DC voltage of about 100V and provide it to the frequency conversion module. Each frequency conversion module can generate a suitable AC voltage from the input DC voltage through the SPWM switching method, and then rectify the discrete digital signal output by the SPWM into an analog sine wave through the rectifier module, and finally achieve high voltage in a cascade manner. Since the voltage of the DC input to the frequency conversion module is 24V, the final single-channel output sinusoidal voltage does not exceed 100V. To achieve the maximum voltage of 200V required by the technical indicators, at least 50 modules are required to be cascaded.

[0010] Depend on Figure 2 It can be seen that the waveform simulation signal after the superposition of 5-way and 50-way outputs, (a) the waveform after the superposition of 5-way output voltage, (b) the waveform after the superposition of 50-way output voltage, (c) the comparison chart of the waveform after the superposition of 50-way output voltage and the sine signal, (d) the waveform after the superposition of 50-way output voltage and filtering. Figure 2 The simple superposition of 5-way voltage outputs is demonstrated, which intuitively reflects the principle of simulating an approximate sinusoidal signal by controlling the switching of the signal and the superposition of the output waveforms. If the number of output waveforms is increased to 50, the model is also composed of a switching signal generator, a switching power supply, and a resistive load, and a higher quality output voltage waveform can be obtained. The comparison between the superposition of 5-way outputs and the standard sinusoidal signal and the signal after filtering is shown in Figure 2. Figure 2 As shown. By comparing the simulation results of 5-way superposition and 50-way superposition, it can be seen that the superposition of multiple outputs can greatly improve the signal quality, and there is no problem with the circuit topology and switch logic in theory. As long as the functions of each module in the model can be realized in the actual hardware circuit, the goal of miniaturization or even micro-miniaturization of plasma-specific power supplies will eventually be achieved.

[0011] A small high-frequency adjustable ionization source power supply system designed by the present invention is based on the overall scheme of a dedicated power supply mainly based on digital circuits. A hardware circuit verification experiment with the input end being the mains power supply is carried out, and problems arising from the scheme in specific practice are found. The scheme is then improved and optimized in a targeted manner, specifically: 1) Use power frequency isolation transformer to output multiple mutually isolated 220V AC, and provide 200V bus to inverter circuit after rectification. This can ensure the load capacity of each output and avoid mutual interference between outputs, thus improving the reliability of the overall circuit.

[0012] 2) Replace the isolation optocoupler with a magnetic coupling device with faster switching speed. The magnetic coupling isolator is a magnetic coupler based on a chip-sized transformer. Unlike the light-emitting diode (LED) and photodiode used in traditional optocouplers, the magnetic isolation technology uses a wafer-level process to directly make a transformer on the chip. Magnetic coupling can achieve 150Mbps high-speed data isolation under low power consumption conditions. Optocouplers are difficult to achieve the same high transmission speed. At the same time, magnetic coupling has a higher cost-effectiveness than optical coupling. The magnetic coupling chip contains a Schmitt circuit inside, which can filter and shape the input and output circuits. Therefore, it can be directly connected to various high-speed control chips, such as: DSP, ARM, PLC, etc., which is very in line with the requirements of this project.

[0013] 3) Attempts were made to solve this problem by improving the circuit structure to reduce the parasitic capacitance value, or replacing it with a MOS tube with better performance. However, actual testing showed that the results were not ideal. Ultimately, the problem was solved by improving the circuit topology and providing a circuit that can discharge the parasitic capacitance when the power device is turned off.

[0014] 4) The isolation transformer hardware can be placed outside the power supply system, and multiple DC levels can be connected to the power supply system using wires, interfaces, etc. Such a discrete system structure retains the possibility of miniaturization or even chip-based power supply system.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the small-sized high-frequency adjustable ionization source power supply system provided by the present invention can realize controllable voltage and frequency, is less affected by load, and has high phase control accuracy, because each switch module can adopt unified control logic and realize unified switch signal; as the main frequency of the control chip increases, the control accuracy will be further improved, and there is a large room for performance improvement; when there are enough output power supplies isolated from each other, the inverter and output parts may no longer need boost windings, so the solution can avoid the use of transformers, making it possible to miniaturize or even micro-miniaturize the power supply dedicated to the multi-channel strong polarization ionization source. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the principle block diagram of the digital power supply solution.

[0017] Figure 2 The waveform simulation signal diagrams after the superposition of 5-way and 50-way outputs, (a) waveform diagram after the superposition of 5-way output voltage, (b) waveform diagram after the superposition of 50-way output voltage, (c) comparison diagram of the waveform after the superposition of 50-way output voltage and the sine signal, (d) waveform diagram of the filtered 50-way output voltage after superposition.

[0018] Figure 3 The schematic diagram of the present invention is a schematic diagram of the rectification to form mutually isolated DC voltages.

[0019] Figure 4 The inverter circuit schematic diagram of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with specific embodiments.

[0021] A small high-frequency adjustable ionization source power supply system: comprising a control circuit, a voltage conversion circuit and an inverter drive circuit; the control circuit controls the voltage conversion circuit and the inverter drive circuit; the control circuit adopts a digital power supply control module, and the digital power supply control module adopts DSP2812 as the main control chip, and through the writing of a program, it simultaneously outputs 14 PWM control signals, such as Figure 3 As shown, the specific idea is: 14-way cascade debugging can be performed, and one output can be stacked to simulate the waveform of a sine wave for experimental debugging of amplitude control, or it can be divided into two approximate sine waves of 7 cascades × 2 to adjust the phase difference between the two outputs; the voltage conversion circuit adopts the method of industrial frequency isolation transformer, including a group of voltage regulators and multiple groups of isolation transformers, so that multiple isolated 220V AC signals are output at the same time, and the 300V bus is provided to the subsequent inverter circuit after rectification; the input end of the isolation transformer is connected to the voltage regulator to achieve the amplitude adjustment of the rectified DC voltage; the inverter drive circuit inputs the switch signal and 300VDC, and outputs a PWM waveform. The inverter circuit adopts a magnetic coupling isolation chip, model ISO721; the drive chip adopts IR2103, the power device adopts a power MOS tube, and the corresponding connections are made, as shown in the schematic diagram Figure 4 Shown is a physical diagram of the isolation and drive circuit.

[0022] The working process of the high-frequency adjustable ionization source power supply system provided in this embodiment is as follows: first, the boost module converts the DC voltage into a multi-channel isolated voltage; the frequency conversion module generates a matching AC voltage from the input DC voltage through the SPWM switching method, and then the discrete digital signal output by the SPWM is rectified into an analog sine wave through the rectifier module, and finally the high voltage is achieved in a cascade manner.

[0023] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A small high-frequency adjustable ionization source power supply system, characterized in that: It includes a control circuit, a voltage conversion circuit and an inverter drive circuit; the control circuit controls the voltage conversion circuit and the inverter drive circuit; The control circuit adopts a digital power control module, and the digital power control module adopts DSP2812 as the main control chip. Through the programming, it can output 14 PWM control signals at the same time. The specific idea is: 14-way cascade debugging can be performed, and one output can be stacked to simulate the waveform of a sine wave to perform experimental debugging of amplitude control, or it can be divided into two approximate sine waves of 7 cascades × 2 to adjust the phase difference between the two outputs; The voltage conversion circuit adopts the method of power frequency isolation transformer, including a set of voltage regulators and multiple sets of isolation transformers, so as to simultaneously output multiple isolated 220V AC signals, and provide the 300V bus to the subsequent inverter circuit after rectification; the input end of the isolation transformer is connected to the voltage regulator to realize the amplitude adjustment of the rectified DC voltage; The inverter drive circuit inputs a switch signal and 300VDC and outputs a PWM waveform. The inverter circuit uses a magnetic coupling isolation chip, model ISO721; the drive chip uses IR2103, and the power device uses a power MOS tube, and corresponding connections are made.

2. A small high-frequency adjustable ionization source power supply system according to claim 1, characterized in that: The working process of the high-frequency adjustable ionization source power supply system is as follows: first, the boost module converts the DC voltage into a multi-channel isolated voltage; the frequency conversion module generates a matching AC voltage from the input DC voltage through the SPWM switching method, and then the discrete digital signal output by the SPWM is rectified into an analog sine wave through the rectifier module, and finally the high voltage is achieved in a cascade manner.

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