Design method of novel pulse power supply

Abstract

The invention discloses a design method of a novel pulse power supply. The method comprises the design and architecture relation of circuits such as a switching power supply module, a numerical control processing unit, a pulse waveform generator, a signal amplification and power amplifier, a negative feedback sampling circuit and an output measurement circuit. The numerical control processing unit carries out digital synthesis according to input pulse parameters to generate pulse waveforms, the pulse waveforms are output after passing through the signal amplifier and the power amplifier, the feedback sampling circuit carries out real-time sampling on voltage and current of the pulse power supply and inputs the voltage and current to the numerical control processing unit, and the numerical control processing unit carries out closed-loop control. And high-precision pulse power supply output is achieved. Different from single-bridge or double-bridge switch chopping of an output part of a traditional pulse power supply, the method has the advantages that pulse signals output by the method are accurate and controllable, positive and negative pulse signals are under closed-loop control of a circuit, zero points of output pulses are accurate and do not deviate, small signals are accurate, pulse edges are neat, expansion is easy, and cost is low.

Description

Technical Field

[0001] The invention relates to the field of pulse power supplies, in particular to single-pulse, double-pulse, multi-pulse and arbitrary pulse power supplies with high requirements for pulse precision control. Background Art

[0002] Pulse power supplies are currently widely used in many industries such as electroplating, electrochemistry, electrolysis and ionization, sewage treatment, and heavy metal treatment. Pulse plating is a powerful means to improve the quality of the coating through the out-of-tank control method. Compared with ordinary DC plating, it has better performance and can greatly save rare and precious metals. Therefore, it is well used in functional electroplating. The pulse frequency will also have a great impact on the crystallization of the coating. If the frequency is too low, the effect is not obvious; if the frequency is too high, the waveform distortion is large, and even the pulse current will become a DC current.

[0003] The electroplating industry has higher and higher requirements for pulse power supplies. At present, pulse power supplies are all switched on and off at the output end of the DC regulated power supply to achieve pulse output of the output power supply. A single pulse is switched on and off by a set of DC power supplies, and positive and negative pulses are switched on and off by two sets of power supplies in series to achieve alternating switching of positive and negative double pulses. Most of the switching is done by half-bridge or full-bridge switching. However, this method has obvious disadvantages, especially for positive and negative pulses: First, the load will have a short suspension period during the switching process of positive and negative pulses, and the voltage conversion is too fast and uncontrolled. The conversion process produces huge burrs, which has an adverse effect on the electroplated parts; second, when the signal is small, the zero points of the two sets of power supplies in series do not match, and the two sets of power supplies have two sets of feedback control. The pulse switching process is not subject to feedback control, and the zero point has a huge drift, resulting in a large error; third, it cannot produce multi-band and multi-voltage pulse waveforms. Summary of the invention

[0004] The purpose of the present invention is to adopt a brand-new concept to design a pulse power supply so as to meet the performance requirements of the related industries for the pulse power supply, improve the accuracy of the existing pulse power supply, improve the pulse burrs, and reduce the errors in the electroplating process.

[0005] The content of the present invention is: a design method of a novel pulse power supply, the method includes a switching power supply module, a numerical control processing unit, a pulse waveform generator, a signal amplifier, a power amplifier, and a feedback sampling circuit. The numerical control processing unit performs digital synthesis according to the input pulse parameters to generate a pulse waveform, which is output after passing through the signal amplifier and the power amplifier. The feedback sampling circuit samples the voltage and current of the pulse power supply in real time and inputs them to the data processing unit, which performs closed-loop control by the numerical control processing unit to achieve high-precision pulse power output.

[0006] Compared with the prior art, the present invention has the following advantages: it is powered by a single power supply system, has only one control feedback system, and performs feedback control all the time during the positive and negative pulse output process, without an open-loop control link. It overcomes the burr problem, zero drift problem, pulse distortion problem, and the problem of being picky about loads in pulse technology of other technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a principle block diagram of a new type of pulse power supply design method.

[0008] Figure 2 It is a schematic diagram of the principle of signal amplification, voltage and current negative feedback, and voltage and current sampling circuits of a new type of pulse power supply design method. DETAILED DESCRIPTION

[0009] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0010] Implementation case, now design a 12V10A pulse plating power supply, the minimum pulse width is 30us. Figure 1 Each part in it is expanded in detail one by one.

[0011] The switching power supply module provides energy output for the entire pulse power supply, which is one of the characteristics different from ordinary pulse power supplies. The present invention divides the change of ACDC and the pulse power supply into two parts, and this switching power supply uses a ready-made module. Since the previous power amplifier needs to work at a higher voltage, a 12A positive and negative 15V dual-channel output switching power supply module is used.

[0012] The CNC processing unit is mainly responsible for the timing generation of pulse width, pulse frequency and pulse amplitude, so its performance is related to the pulse index to be designed. The CNC processing unit is generally implemented by MCU or DSP. The minimum pulse width of 30us in the index requires the CNC processing unit to complete a series of calculations such as pulse waveform output, ADC feedback sampling of voltage and current, error calculation, and feedback to the input end within 30us. After measurement, MCUs of 45MHz and above can achieve this.

[0013] The pulse signal generator generates a small pulse signal under the control of the numerical control processing unit. This can be achieved by using the PWM output of the numerical control processing unit through RC filtering, or by directly using the digital-to-analog converter DAC. Since the pulse signal can be positive or negative, the output signal must be shifted to a negative voltage so that positive and negative signals can be output.

[0014] Figure 2 It shows the principle diagram of signal amplification, voltage and current negative feedback, and voltage and current sampling circuit. This process amplifies the small signal of the pulse power supply to 12V10A.

[0015] The operational amplifier and power amplifier are designed as a whole, mainly considering the bandwidth and frequency response of the pulse signal. The voltage and current of the pulse signal of the small signal are amplified to the set value. Common audio operational amplifiers can be used, which generally have a bandwidth of 50KHz, and can achieve square wave signals within 10Khz after filtering. The power amplifier can be realized by push-pull NPN and PNP transistors, or NMOS and PMON MOS tubes.

[0016] The goal is to design a 12V pulse voltage output, so the supply voltage of the operational amplifier and power amplifier must be at least 15V. The power tube uses a MOS tube, and the output voltage of the operational amplifier must be at least + / - 13V. The power tube uses a triode, and the output voltage of the operational amplifier must be at least + / - 14V.

[0017] The negative feedback loop is a relatively important hardware circuit. The pulse power supply needs to output voltage and current stably and accurately. A single negative feedback circuit cannot meet the requirements, so an analog switch is needed here to select the voltage feedback and current feedback. The only thing to note is that the static operating point of the circuit is different when the voltage feedback and current feedback are used, and the signal zero point and sampling zero point of the circuit need to be calibrated separately.

[0018] R4 / R3 is the negative feedback gain. R1 and R2 are not necessary, the main purpose is to keep the input small signal within the negative feedback voltage range. In this example, it is plus or minus 0.5V, so R1 and R2 need to keep the input small signal within the range of plus or minus 0.5V.

[0019] There is a detail that needs to be explained here. The measurement circuit and the negative feedback circuit are originally two independent circuits, but considering that the measurement of the current signal requires the consumption of energy in the circuit, it is best to share the current feedback signal and the current sampling signal in one circuit. The current sampling circuit corresponds to a current output of 10A, using a 0.05 ohm resistor, a voltage of 0.5V, and a power of 5W; if a 10A shunt is used, the voltage is 0.075V. But 0.075V is too small for the negative feedback signal, so a 0.05 ohm sampling resistor is used here. By replacing the Hall current sensor, as long as the current feedback signal can be above 0.5V, the requirement can be met.

[0020] The output measurement of the pulse power supply output part requires real-time measurement of voltage and current. Here, the voltage and current values ​​of the current band must be measured after the pulse waveform changes and before the next change, and acquired by the CNC processing unit. Voltage measurement can be sent to the analog-to-digital conversion circuit after voltage division. The current signal needs to be converted into a voltage signal through a shunt or a Hall current sensor and sent to the analog-to-digital conversion circuit, and the CNC processing unit performs data processing.

Claims

1. A design method for a new type of pulse power supply, characterized in that: The method includes: A pulse small signal generating circuit, wherein the circuit generates a small signal waveform of a pulse power supply according to the set pulse parameters by a numerical control processing unit; A signal amplification and power amplification circuit, which amplifies the current and voltage of the pulse signal to the set value of the pulse power supply; Signal feedback control circuit to realize the constant voltage or constant current control loop of the pulse power supply; The power supply output measurement circuit fine-tunes the output signal to achieve accurate output; Switching power supply module realizes the energy supply of power supply.

2. The design method of a novel pulse power supply according to claim 1, characterized in that: The pulse waveform is realized in a small signal, and the small signal is processed into a positive, negative, or zero-value small signal, rather than directly switching a half-H bridge or full-H bridge under a large current and voltage on the output side to obtain a pulse power supply.

3. The design method of a novel pulse power supply according to claim 1 is characterized in that: Signal amplification and power amplifier circuits amplify small signals of pulse waveforms, and the amplification circuits are not limited to Class AB, Class C, Class D and Class E power amplifiers.

4. The design method of a novel pulse power supply according to claim 1 is characterized in that: The signal feedback control circuit combines the voltage and current feedback to select one of the two, and performs negative feedback at the hardware analog circuit level on the signal amplification and power amplification circuit as a whole, and is separated from the output measurement circuit.

5. The design method of a novel pulse power supply according to claim 1 is characterized in that: The power supply output measurement circuit is separated from the feedback circuit and is used for software feedback. The numerical control processing unit adjusts the waveform parameters of the small pulse signal to compensate for the errors of the signal amplification and power amplification circuits.

6. The design method of a novel pulse power supply according to claim 1 is characterized in that: The switching power supply module adopts an independent module to realize the circuit overvoltage, overcurrent, short circuit, EMC and EMI, etc., separated from the pulse function.

7. A design method for a novel pulse power supply according to claims 1, 2 and 5, characterized in that: The numerical control processing unit can generate waveform parameters, generate digital waveform data, and receive output measurement signals. Therefore, this method completes the digital control of the entire system, has the performance advantages of a digital control circuit, and can be connected to a human-computer interaction UI system and a network communication module.

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