Parallel current sharing control system and method

Abstract

The invention discloses a parallel current sharing control system and method, and relates to the field of power supply technology and electronic technology, and the system comprises a plurality of parallel single power supply modules, an upper computer, a photoelectric conversion module, a PLC, and a parallel current sharing circuit. The single power supply module comprises a magnetic filter power supply MFPS for providing required large current for the plasma electrode; the upper computer provides a man-machine interaction interface, so that a user can conveniently operate and monitor a power supply detection signal; the photoelectric conversion module converts an optical signal into an electric signal, or conversely, the electric signal is used for optical fiber communication; the PLC is used for transmitting a preset signal and a power supply detection signal; and the parallel current sharing circuit is used for realizing current distribution balance among a plurality of power supplies. Through parallel current sharing control, the output power of the system is effectively improved, the stress load of a single power supply module is reduced, the service life of equipment is prolonged, and the stability of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of power supply technology and electronic technology, and specifically relates to a parallel current sharing control system and method. The method realizes high-precision current output by connecting multiple power modules in parallel to meet application scenarios with high requirements for current accuracy and stability. Background Art

[0002] In the research of controllable magnetic confinement nuclear fusion, neutral beam injection is one of the commonly used and relatively efficient auxiliary heating methods. Its power supply system plays the role of energy supply in the generation and transmission of neutral beams. The neutral beam power supply system has extremely high precision requirements for each power supply. High precision means that the voltage or current fluctuation of the power supply output is extremely small, which can ensure that the negative ion source maintains stable performance during operation. In the neutral beam power supply system, the magnetic filter power supply (MFPS) mainly provides the required large current for the plasma electrode, thereby generating a magnetic field to deflect electrons, thereby increasing the negative ion yield. Its high-precision and low-ripple current output can reduce the magnetic field fluctuation caused by current fluctuations, thereby improving the quality and stability of the negative ion beam. In order to meet the requirements of the neutral beam power supply system of the negative ion source for high precision, low ripple and large current output of the magnetic filter power supply, the present invention proposes a method for achieving high-precision and large current output by connecting multiple power modules in parallel. Summary of the invention

[0003] The purpose of the present invention is to provide a parallel current sharing control system and method to solve the problem of high-precision and large-current output requirements of the negative ion source neutral beam power supply system for the magnetic filter power supply. The total output current can be adjusted in the range of 0 to 6000A, and the output ripple is less than 1%, which is applied to the CRAFT NNBI power supply system.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a parallel current sharing control system, comprising: a plurality of single power supply modules in parallel, a host computer, a photoelectric conversion module, a PLC, and a parallel current sharing circuit; The single power module includes a magnetic filter power supply MFPS, which provides the required high current for the plasma electrode; The host computer provides a human-computer interaction interface to facilitate user operation and monitoring of power detection signals; The photoelectric conversion module converts optical signals into electrical signals, or vice versa, for optical fiber communications; PLC is used for transmission of preset setting signals and power supply detection signals; The parallel current sharing circuit is used to achieve balanced current distribution among multiple power supplies.

[0005] The present invention has the following beneficial effects: 1. Parallel current sharing Share the load current through multiple single power modules, which can effectively increase the total output power of the system, while reducing the stress of each power module and avoiding overload of a single device. This method reduces the heat and current load of each device, prolongs the life of the equipment and improves the reliability of the system.

[0006] 2. Reduce costs: Through modular design, the power supply system can be standardized and mass-produced, reducing production costs. Modular design also facilitates maintenance and upgrades, reducing the cost and time cost of later system maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A schematic diagram of a power-level main circuit of a single power supply module provided by the present invention; Figure 2 A schematic diagram of a full-bridge inverter circuit provided by the present invention; Figure 3 A PWM drive schematic diagram provided by the present invention; Figure 4 A schematic diagram of local control and remote control provided by the present invention; Figure 5 A remote control flow chart provided by the present invention; Figure 6 This is a schematic diagram of the parallel current sharing circuit provided by the present invention. DETAILED DESCRIPTION

[0008] In order to make the purpose, technical solutions and advantages of the present invention more clear and understandable, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0009] The present invention provides a parallel current sharing control system, including: multiple single power modules in parallel, a host computer, a photoelectric conversion module, a PLC, and a parallel current sharing circuit; the single power module includes a magnetic filter power supply MFPS, which provides the required large current for the plasma electrode; the host computer provides a human-computer interaction interface, which is convenient for users to operate and monitor the power detection signal; the photoelectric conversion module converts the optical signal into an electrical signal, or vice versa, for optical fiber communication; the PLC is used for the transmission of preset setting signals and power detection signals; the parallel current sharing circuit is used to achieve current distribution balance among multiple power supplies. The present invention adopts a method of connecting multiple power modules in parallel to achieve high-precision large current output. The parallel current sharing shares the load current through multiple single power modules, which can effectively increase the total output power of the system, while reducing the stress of each power module and avoiding overload of a single device. This method reduces the heat and current load of each device, prolongs the life of the equipment and improves the reliability of the system.

[0010] The circuit structure of the single power module is first introduced below. The single power module includes a magnetic filter power supply (MFPS) to provide the required high current for the plasma electrode. The single power module also has a power stage main circuit, such as Figure 1 As shown, the power stage main circuit is composed of a distribution unit input, EMI filtering, AC / DC rectifier circuit, full-bridge inverter circuit, high-frequency transformer, and secondary rectifier filter. The power supply unit input is a three-phase industrial electricity of 380V, which is isolated and connected to the EMI filter input terminal through a 1:1 transformer. The EMI filter includes an X capacitor, a Y capacitor, and a common-mode inductor. The X capacitor is connected between the live wire and the neutral wire of the power line, and the Y capacitor is connected between the power line and the ground wire. The EMI filter output terminal is connected to the input terminal of the AC / DC rectifier circuit. The AC / DC rectifier circuit is composed of a three-phase rectifier circuit, including six rectifier diodes and aluminum electrolytic capacitors used for energy storage filtering. After rectification and filtering, the output is 540V. The output terminal of the AC / DC rectifier circuit is connected to the input terminal of the full-bridge inverter circuit. In order to better understand the full-bridge inverter circuit, combined with Figure 2 Explain. The full-bridge inverter circuit is composed of four IGBTs to form the upper and lower bridge arms. The sum of the IGBT's parallel capacitance and its own parasitic capacitance resonates with the transformer leakage inductance to achieve zero-voltage soft switching of the full-bridge inverter circuit switch tube. The center point of the full-bridge inverter circuit is connected to the primary winding of the high-frequency transformer. The high-frequency transformer selects 10 transformers with center taps for primary winding series connection, and the secondary windings are connected in parallel. The transformer with center tap has a turn ratio of 2:1, and the total turn ratio of the high-frequency transformer is 20:1. The secondary winding of the high-frequency transformer is connected to the input end of the secondary rectifier filter, and the secondary rectifier filter adopts an aluminum electrolytic capacitor. The output of the secondary rectifier filter is connected in parallel to both ends of the load, and the rated output is 15V / 2000A.

[0011] Secondly, combine Figure 1-Figure 3 The control method of the full-bridge inverter circuit of a single power module is introduced. The reference signal is generated by the STM32F103 microcontroller and output to the feedback pin of the ISL6754 chip, and compared with the feedback voltage of the current output of the single power module. The system uses a PID controller for feedback regulation to control the PWM output. Among them, the duty cycle of the PWM (OUTUR, OUTUL) driving the upper arm of the full-bridge inverter circuit is fixed at 50%, while the duty cycle of the PWM (OUTLR, OUTLL) of the lower arm is adjustable. Within the adjustable resonant delay time (RD), the capacitor connected in parallel with the IGBT and the sum of its own parasitic capacitance (C1, C2, C3, C4) resonates with the transformer leakage inductance (Lr) to achieve zero voltage soft switching of the full-bridge inverter circuit.

[0012] In an embodiment, a parallel current sharing control method is provided, such as Figure 4As shown, the control method includes: local control and remote control. When local control is used to control the three single power modules (MFPS1, MFPS2, MFPS3), the current sequence and current value are preset using the local screen, and the power state is detected, and the detection signal of the power state is transmitted to the local screen in real time. The preset signal is transmitted to the single-chip microcomputer inside each power supply through the PLC, and the reference signal is given. The reference signal is superimposed with the error signal of the closed-loop feedback to form a new reference signal, and the full-bridge inverter circuit control method described in the embodiment of the present invention is used to adjust the output. When remote control is used, the experimental operator can remotely preset the current sequence and current value through the host computer software, and monitor the power state. The detection signal of the power state (single power module current output, multi-power module total current output) will communicate with the optical fiber and the photoelectric conversion module, and be transmitted to the host computer in real time. The preset signal is communicated through the photoelectric conversion module and the optical fiber, and is transmitted to the internal single-chip microcomputer of each power module through the PLC to give the reference signal. The reference signal is output to the feedback pin of the ISL6754 chip and superimposed with the error signal of the closed-loop feedback to form a new reference signal. The new reference signal is compared with the feedback voltage of the current output of the single power module, and a PID controller is used for closed-loop feedback to control the duty cycle of the PWM output. The full-bridge inverter circuit control method described in the embodiment of the present invention performs output regulation, and the flow chart is as follows: Figure 5 As shown below. Figure 6 right Figure 5 In the closed-loop feedback, the current output of a single power module and the total current output sampling value of multiple power modules are converted into a voltage signal V by a current amplifier. i and V ii The voltage signal of the total current output of the multi-power module is the current-sharing bus voltage V of the closed-loop feedback. ii The voltage signal V i Feedback to the current balancing controller, the current balancing controller compares the voltage signal V i The current sharing bus voltage V ii Generate error signal V a This signal is used to adjust the output of the single power module to make it close to the target current value. r And the feedback voltage V of the single power module current output f As an input signal, it is used to adjust the output current of the power module. The specific adjustment process is as follows: when the voltage at point A is equal to the current sharing bus voltage, the voltage difference across the resistor R is zero, and each power module achieves current sharing. When a voltage drop occurs across the resistor R, the current sharing controller will amplify the current sharing bus voltage V iiWith the voltage signal V i The voltage difference between the a The error signal V a The reference voltage V given by the microcontroller b The new reference voltage V is generated by superposition r and the feedback voltage V f With the new reference voltage V r As the input of the Type II error amplifier composed of an operational amplifier, an error signal is generated through PID control adjustment. The error signal is used to adjust the PWM duty cycle, thereby adjusting the output current, and ultimately achieving the purpose of current sharing.

[0013] The disclosed embodiments of the present invention can enable those skilled in the art to easily implement or apply the contents of the present invention. Various changes or adjustments made to these embodiments are also obvious to those skilled in the art. Without departing from the core idea and scope of the present invention, these changes and adjustments can also be embodied in other embodiments. It should be understood that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A parallel current sharing control system, characterized in that: include: Connect multiple single power modules, host computers, photoelectric conversion modules, PLCs, and parallel current-sharing circuits in parallel; The single power module includes a magnetic filter power supply MFPS, which provides the required high current for the plasma electrode; The host computer provides a human-computer interaction interface to facilitate user operation and monitoring of power detection signals; The photoelectric conversion module converts optical signals into electrical signals, or vice versa, for optical fiber communications; PLC is used for transmission of preset setting signals and power supply detection signals; The parallel current sharing circuit is used to achieve balanced current distribution among multiple single power modules.

2. A parallel current sharing control system according to claim 1, characterized in that: The single power supply module also includes a power stage main circuit, which consists of a distribution unit input, EMI filtering, AC / DC rectifier circuit, full-bridge inverter circuit, high-frequency transformer, and secondary rectifier filter; wherein the distribution unit input is three-phase industrial electricity 380V, which is connected to the EMI filter input end through 1:1 transformer isolation, the EMI filter output end is connected to the AC / DC rectifier circuit input end, the AC / DC rectifier circuit output end is connected to the full-bridge inverter circuit input end, the full-bridge inverter circuit output end is connected to the primary winding of the high-frequency transformer, the secondary winding of the high-frequency transformer is connected to the secondary rectifier filter input end, the secondary rectifier filter output is connected in parallel to both ends of the load, and the rated output is 15V / 2000A.

3. A parallel current sharing control system according to claim 2, characterized in that: For high-frequency transformers, select multiple transformers with center taps to connect the primary windings in series and the secondary windings in parallel. The turns ratio of the transformers with center taps is 2:1, and the total turns ratio of the high-frequency transformer is 20:

1.

4. A parallel current sharing control system according to claim 2, characterized in that: The full-bridge inverter circuit is composed of four IGBTs forming the upper and lower bridge arms. The sum of the parallel capacitance of the IGBT and its own parasitic capacitance resonates with the transformer leakage inductance to realize zero-voltage soft switching of the switch tube of the full-bridge inverter circuit. The center point of the full-bridge inverter circuit is connected to the primary winding of the high-frequency transformer. The reference signal is given by the single-chip microcomputer. The reference signal is output to the feedback pin of the chip and the feedback voltage output by the single power module current is used as the input of the Type II error amplifier composed of an operational amplifier. The error signal is generated through PID control and adjustment to control the duty cycle of the PWM output. The upper bridge arm adopts a fixed 50% duty cycle, while the lower bridge arm adopts an adjustable duty cycle drive. The PWM output acts on the full-bridge inverter circuit and realizes zero-voltage soft switching through adjustable resonance delay.

5. A parallel current sharing control system according to claim 3, characterized in that: The parallel current sharing circuit includes: a Type II error amplifier composed of an operational amplifier, a current sharing controller, a current sharing bus, a current amplifier, and a peripheral circuit composed of resistors and capacitors.

6. A parallel current sharing control system according to claim 5, characterized in that: The sampling values ​​of the current output of the single power module and the total current output of the multi-power module are converted into a voltage signal V by the current amplifier. i and V ii The voltage signal of the total current output of the multi-power module is the current sharing bus voltage V ii , the voltage signal V i Feedback to the current balancing controller, the current balancing controller compares the voltage signal V i The current sharing bus voltage V ii Generate error signal V a , which is used to adjust the output of the single power module to make it close to the target current value; the error signal V a The reference voltage V given by the microcontroller b The new reference voltage V is generated by superposition r , the operational amplifier converts the reference voltage V r And the feedback voltage V of the single power module current output f as the input signal and the feedback voltage V f With the new reference voltage V r As the input of the Type II error amplifier composed of an operational amplifier, an error signal is generated through PID control adjustment. The error signal is used to adjust the PWM duty cycle, thereby adjusting the output current, and ultimately achieving the purpose of current sharing.

7. A parallel current sharing control method, applied to the system according to claims 1-6, characterized in that: There are two modes: local control and remote control; The steps of local control are as follows: presetting the current timing and current value on the local screen, and detecting the power supply status. The detection signal of the power supply status will be transmitted to the local screen in real time. The presetting signal is transmitted to the single-chip microcomputer inside each single power supply module through the PLC to give a reference signal. The reference signal is superimposed with the error signal of closed-loop feedback to form a new reference signal, and a PID controller is used for closed-loop feedback to control the duty cycle of the PWM output; The steps of remote control are as follows: the host computer pre-sets the current timing and current value, and detects the power status. The detection signal of the power status will be transmitted to the host computer in real time. The predetermined signal communicates through the photoelectric conversion module and optical fiber, and is transmitted to the internal microcontroller of each single power module through the PLC to give a reference signal. The reference signal is superimposed with the error signal of closed-loop feedback to form a new reference signal, and a PID controller is used for closed-loop feedback to control the duty cycle of the PWM output.

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