Low-ripple bipolar constant-current power supply applied to particle accelerator

Abstract

The invention relates to a low-ripple bipolar constant-current power supply applied to a particle accelerator. The low-ripple bipolar constant-current power supply comprises a direct-current voltage input unit, a Buck circuit unit, a microprocessor, an adjustable linear circuit unit, a bipolar control circuit unit, a voltage and current sampling circuit unit and a bipolar current output unit which are connected in sequence. The low-ripple bipolar constant-current power supply device manufactured by adopting the technology has the advantages of small volume, low output ripple, good stability and strong anti-interference capability, the long-term operation stability can reach within 100ppm, and the low-ripple bipolar constant-current power supply device has a bipolar output function and can output positive current and negative current.

Description

Technical Field

[0001] The present invention relates to a low ripple bipolar constant current power supply device applied to a particle accelerator. The low ripple bipolar constant current power supply device manufactured by the technology has the advantages of small size, low output ripple, good stability, strong anti-interference ability, long-term operation stability can reach within 100ppm, and has a bipolar output function, which can output both positive polarity current and negative polarity current. Background Art

[0002] A particle accelerator is an instrument that uses electromagnetic fields to accelerate charged particles to high energies. It is widely used in basic scientific research, industrial applications, medical diagnosis and treatment, and other fields. With the continuous development of science and technology, the acceleration capability of particle accelerators has been continuously improved, and the requirements for power supply systems have become higher and higher. Especially in high-energy physics experiments, particle accelerators need to accurately control the acceleration process of particles to ensure the accuracy and reliability of experimental results.

[0003] In a particle accelerator, a low-ripple bipolar constant current power supply is one of the key devices to ensure stable acceleration of particles. Since particle accelerators have extremely high requirements for power supply accuracy, stability and ripple, power supply volume and weight, anti-interference ability, and temperature adaptability performance indicators, the design and implementation of a low-ripple bipolar constant current power supply has become an important technical challenge. Specifically, a low-ripple power supply can reduce the AC component in the power supply output and reduce interference with the particle acceleration process; the bipolar output can meet the needs of particle accelerators when accelerating different types of particles. Among the existing power supply solutions, there are mainly two types: linear regulated DC power supply and switching power supply.

[0004] The characteristics of linear regulated DC power supply are: output voltage is lower than input voltage; fast response speed, small output ripple; low noise generated during operation; strong resistance to electromagnetic interference; good stability, and little influence by load fluctuation. Disadvantages: low efficiency; large heat generation, especially for high-power power supply, heat generation leads to unstable output voltage and current, indirectly adding thermal noise to the system. Large size and weight, not conducive to carrying and installation. Moreover, linear power supply cannot achieve bipolar output. Therefore, linear power supply has many limitations in particle accelerator applications.

[0005] Advantages of switching power supply: high efficiency and stability, good output voltage stability. Small and light, easy to carry and install. Easy to digitally control and adjust, strong adaptability. Low power consumption, less environmental and energy consumption. However, switching power supply has the following disadvantages: relatively high price, sensitive to electromagnetic interference, stability is greatly affected by load fluctuations, switching noise of the switching device itself is large, and it is easy to be interfered by external electromagnetic fields. It is difficult to meet the high-precision and high-temperature performance occasions such as particle accelerators.

[0006] In view of the problems existing in the application of the above-mentioned switching power supply and linear power supply in the particle accelerator power supply, the patent of the present invention proposes a power supply device with an improved circuit topology scheme and a new control method. By improving the switching power supply and the linear power supply, a design topology and control method of a bipolar constant current source device with small size, high efficiency, good stability, strong anti-interference ability and high precision is proposed. Summary of the invention

[0007] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and provide a new bipolar constant current power supply device and control implementation method that meet the performance requirements of particle accelerator power supply on volume, stability, anti-interference ability, output accuracy, output resolution, etc., thereby solving the application problems of the existing particle accelerator power supply.

[0008] To this end, a low ripple bipolar constant current power supply for a particle accelerator is provided, comprising a DC voltage input unit, a Buck step-down circuit unit, a microprocessor, an adjustable linear circuit unit, a bipolar control circuit unit, a voltage and current sampling circuit unit, and a bipolar current output unit connected in sequence; the DC voltage input unit is configured as a flyback power supply module; the Buck step-down circuit unit comprises a switch tube Q1, a switch tube Q2, an inductor Lr1, a capacitor C1, and a capacitor C2, the drain of the switch tube Q1 is connected to the source of the switch tube Q2 to form a series branch, the series branch is connected in parallel with the capacitor C1 and then connected across the two output ends of the DC voltage input unit, the connection point of the series branch is connected to the inductor Lr1 and the capacitor C2 to be connected to the negative output end of the DC voltage input unit, the two ends of the capacitor C2 are used as the output of the Buck step-down circuit unit, and the microprocessor The processor controls the on and off of the switch tube Q1 and the switch tube Q2 through PWM; the adjustable linear circuit unit includes a transistor Q3, a transistor Q4, and a capacitor C3. The transistor Q3 and the transistor Q4 form a Darlington structure with the base of the transistor Q3 as the control end, which is connected to the positive output end of the Buck buck circuit unit. The base of the transistor Q3 is connected to the negative output end of the Buck buck circuit unit through the capacitor C3. The microprocessor outputs analog quantity to control the base of the transistor Q3 through the DAC chip and the operational amplifier unit; the bipolar control circuit unit forms a bridge circuit through four switch tubes controlled by the microprocessor; the voltage and current sampling circuit unit samples the output voltage and output current of the main loop to the microprocessor; the bipolar current output unit includes a capacitor group connected in parallel to the output end of the main loop, and the capacitor group forms a filtering processing system in combination with an external particle accelerator coil load.

[0009] As an improved solution, the Buck step-down circuit unit adopts a voltage loop control system. The set voltage of the Buck circuit voltage loop is 1 / N of the output voltage of the DC voltage input unit, where N is an integer. The output voltage sampling signal detected by the voltage and current sampling circuit unit and the set voltage are sent to the voltage proportional integral differential PID controller for closed-loop control. The output of the closed-loop control is a pulse width modulation signal generated by a microprocessor to control the conduction of the switch tubes Q1 and Q2; the adjustable linear circuit unit adopts a current closed-loop control system, and the set current and the output current sampling signal detected by the voltage and current sampling circuit unit are put into the current proportional integral differential Pid regulator to calculate the size of the analog output signal DA of the adjustable linear circuit, and then the analog signal DA is amplified by an operational amplifier to control the conduction of transistors Q3 and Q4.

[0010] Furthermore, synchronous control of the switch tubes Q1 and Q2 is adopted to form an alternating complementary conduction with dead zone control.

[0011] Furthermore, the dead time is set to be between 100 nanoseconds and 500 nanoseconds.

[0012] Furthermore, the PWM switching frequency must be greater than 100kHz.

[0013] Further, when the difference between the output current of the power supply and the set current is less than the first threshold, the duty cycle of the pulse width of the Buck buck circuit unit is determined. When the output duty cycle is greater than 80%, the current is fine-tuned through the adjustable linear circuit unit. If the output duty cycle of the Buck buck circuit unit is less than 50%, the value of the set voltage of the Buck buck circuit is reduced. After the output voltage of the Buck buck circuit is stable, the adjustable linear circuit unit is continuously fine-tuned. This control is continuously cyclically performed until the output duty cycle of the Buck buck circuit is greater than 80% and the difference between the output current of the power supply and the set current is less than the first threshold. The set voltage of the Buck buck circuit is fixed and the current is continuously fine-tuned through the adjustable linear circuit unit. When the output current of the power supply cannot reach a difference less than the first threshold with the set current within the set time, and the duty cycle of the Buck buck circuit is always greater than 80%, the set voltage of the Buck buck circuit is increased.

[0014] As another improvement scheme, the switch tube in the Buck step-down circuit adopts a high-speed MOSFET.

[0015] As another improvement scheme, the voltage and current sampling circuit unit performs data conversion through a high-precision ADC chip, and the microprocessor reads the high-precision ADC chip through an SPI or I2C bus.

[0016] Beneficial effects of the present invention:

[0017] The purpose of the present invention is to address the problems that the switching power supply is relatively expensive, is sensitive to electromagnetic interference, and its stability is greatly affected by load fluctuations. The switching noise of the switching device itself is large, and it is easily interfered by external electromagnetic fields. The linear power supply has low operating efficiency and generates a lot of heat, especially for high-power power supplies. The heat generation causes the output voltage and current to be unstable, which indirectly adds thermal noise to the system. The large size and weight make it difficult to carry and install. Moreover, the linear power supply cannot achieve bipolar output and other problems. The patent of the present invention proposes a power supply device and control method with an improved circuit topology scheme. Through the improvement of the switching power supply and the linear power supply, the power supply device has the characteristics of small size, high stability, strong anti-interference ability, high output accuracy, high output resolution, etc., which solves the application problem of poor performance of the existing particle accelerator power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a block diagram of a low ripple bipolar constant current power supply circuit;

[0019] Figure 2 The topology diagram of the low ripple bipolar constant current power supply circuit is shown;

[0020] Figure 3 The schematic diagram of the low ripple bipolar constant current power supply circuit is shown;

[0021] Figure 4 The control process diagram of low ripple bipolar constant current power supply is shown;

[0022] Figure 5 A low ripple bipolar constant current power supply control flow chart is shown;

[0023] Figure 6 The figure shows the electric field effect generated by the application of a conventional power supply device to a particle accelerator;

[0024] Figure 7 The diagram shows the electric field effect generated by the power supply device implemented by the present invention when applied to a particle accelerator. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0026] The power supply device of the present invention comprises a DC voltage input unit, a Buck step-down circuit unit, a microprocessor, an adjustable linear circuit unit, a bipolar control circuit unit, a voltage and current sampling circuit unit, and a bipolar current output unit. Figures 1 to 3 shown. Figure 1 The particle accelerator coil load is a device used to provide an accelerating magnetic field for charged particles, and is not an internal device of the power supply device of the present invention.

[0027] The DC voltage input unit uses a single-phase 220V AC to 24V DC flyback power module. The input voltage is 220V AC and can provide a stable 24V DC output. The module uses a single-phase 220V AC input and converts it into a stable 24V DC output through flyback conversion technology, providing a basic voltage for the subsequent circuit. It has the characteristics of high efficiency, small size and low cost.

[0028] The Buck step-down circuit unit includes a switch tube Q1, a switch tube Q2, an inductor Lr1, a capacitor C1, and a capacitor C2. The drain of the switch tube Q1 is connected to the source of the switch tube Q2 to form a series branch. The series branch is connected in parallel with the capacitor C1 and then connected to the two output ends of the DC voltage input unit. The connection point of the series branch is connected to the inductor Lr1 and the capacitor C2 to the negative output end of the DC voltage input unit. The two ends of the capacitor C2 serve as the output of the Buck step-down circuit unit. The microprocessor controls the switch tube Q1 and the switch tube Q2 through PWM. The Buck circuit unit receives the 24V DC output of the flyback power supply module, controls the on and off of the switch element through PWM (pulse width modulation), realizes further voltage reduction, optimizes the current waveform, and reduces the influence of the switching noise on the subsequent circuit. The switch tube of the Buck circuit adopts a high-speed MOSFET to reduce switch damage and reduce the ripple output of the power supply device.

[0029] The microprocessor MCU unit seamlessly integrates the high-precision analog processing flow, and efficiently reads the voltage and current signal sampling data captured by the high-precision ADC (analog-digital converter) chip, such as the 24-bit model ADS1256 provided by Texas Instruments, through the SPI or I2C bus to ensure the accuracy and reliability of the data. Subsequently, the MCU communicates with the high-precision DAC (digital-analog converter) chip to implement precise output control. On this basis, the MCU, as the core control engine, executes the PID (proportional-integral-differential) control algorithm, and implements a closed-loop regulation strategy for the Buck circuit system and the adjustable linear circuit, thereby accurately and stably controlling the output voltage and current, significantly improving the overall performance and accuracy of the system.

[0030] The adjustable linear circuit unit is used to isolate the switching noise of the front-stage Buck buck circuit unit and improve the accuracy and stability of the entire power supply. The adjustable linear circuit unit includes transistors Q3, transistors Q4, and capacitor C3. The transistors Q3 and Q4 form a Darlington structure with the base of the transistor Q3 as the control end, which is connected to the positive output end of the Buck buck circuit unit. The base of the transistor Q3 is connected to the negative output end of the Buck buck circuit unit through capacitor C3. The microprocessor controls the base of the transistor Q3 through the DAC chip and the output analog quantity of the operational amplifier unit. The adjustable linear circuit unit uses high-power transistors to form a linear amplifier circuit. After the high-precision analog quantity is amplified by the operational amplifier circuit, the high-power transistor is controlled to work in the linear region. After passing through the Buck buck circuit, the closed-loop control of the input current of the adjustable linear circuit is used to make the output current ripple smaller, the accuracy higher, and the stability better, and isolate the front-stage switching noise, thereby improving the overall accuracy and stability of the power supply. The high-precision digital analog output chip uses a DAC chip with a resolution of 16 bits and higher.

[0031] The bipolar control circuit unit is optimized in design and consists of four switching tubes controlled by a microprocessor to form a bridge circuit. By controlling the on and off states of the switching devices (such as MOSFET or IGBT), it can achieve flexible switching of the output voltage and current polarity, and ensure fast and smooth conversion of the current direction to meet the needs of bipolar loads.

[0032] The voltage and current sampling circuit unit samples the output voltage and output current of the main circuit to the microprocessor. It is designed as a high-precision sampling circuit and relies on a dedicated high-precision sampling chip to achieve accurate measurement. The system continuously and accurately captures the power supply operating parameters and provides error-free feedback signals for the microprocessor MCU.

[0033] The bipolar current output unit includes a capacitor group connected in parallel to the output end of the main circuit, and the capacitor group forms a filtering processing system in combination with an external particle accelerator coil load. The bipolar current output unit cleverly uses the inductance of the particle accelerator coil load itself and the capacitor group to build a filtering processing system, deeply optimizes the output of the bipolar control circuit, effectively filters out clutter interference, significantly improves the stability and anti-interference ability of the power supply, and ensures that the power supply device can maintain excellent operating performance under various complex working conditions.

[0034] like Figure 4-Figure 5 As shown, the control method and steps are as follows:

[0035] 1. The polarity of the output current is determined based on whether the set current is greater than zero. If the output current is greater than zero, the bipolar control circuits Q5 and Q8 are turned on, and the output current is positively controlled.

[0036] 2. Buck circuit adopts voltage loop control system. First, the setting voltage of Buck circuit voltage loop is 1 / N of the output voltage of DC voltage input unit, N is an integer, the output voltage sampling signal detected by voltage and current sampling circuit unit and the setting voltage are sent to voltage proportional integral differential PID controller for closed loop control; the output of closed loop controller is controlled by microprocessor to generate pulse width modulation signal to control Buck circuit for voltage regulation control. In order to improve power efficiency and reduce ripple, the method of synchronous control of Q1 and Q2 switch tubes is adopted, and Q1 and Q2 switch tubes are alternately complementary turned on. Single tube Q1 control method is not adopted. Set the driving signal of Q1 and Q2 to complementary conduction, with dead zone control mode, the switching frequency of PWM pulse must be greater than 100kHz, too low frequency will lead to high output ripple voltage of power supply, low control accuracy and output resolution. Dead time is set between 100 nanoseconds and 500 nanoseconds, too low dead time is easy to cause switch tube breakdown, too high dead time leads to reduced output accuracy.

[0037] 3. The microprocessor reads high-precision voltage and current sampling signals through the serial transmission bus SPI, sends the set current and current sampling signals to the PID regulator, and calculates the duty cycle of the Buck circuit. The pulse width modulation signal generated by the pulse drive circuit controls the switching device of the Buck circuit to turn on and off, thereby realizing closed-loop control of the output current.

[0038] 4. Turn on the control of the adjustable linear circuit. The linear adjustable control circuit adopts a current closed-loop control system. By putting the output current sampling signal detected by the set current and voltage current sampling circuit unit into the current proportional integral differential Pid regulator, the size of the analog output signal DA of the adjustable linear circuit is calculated, and then the analog signal DA is amplified by the operational amplifier to control the conduction of the high-power transistors Q3 and Q4, and the high-power transistors of the adjustable linear circuit are controlled by the external high-precision analog output chip for linear output. Thereby further improving the accuracy and stability of the output current of the constant current device, while isolating the switching noise of the Buck circuit, reducing the output current ripple, and improving the anti-interference ability of the system.

[0039] 5. When the difference between the output current of the power supply and the set current is less than the first threshold, the duty cycle of the pulse width of the Buck circuit is determined; when the output duty cycle is greater than 80%, it means that the utilization rate of the Buck circuit is relatively high at this time, and there is no need to adjust the output voltage of the Buck circuit. Continue to fine-tune the linear adjustable circuit to achieve high-precision, high-resolution, and high-stability current control. If the output duty cycle of the Buck circuit is less than 50% at this time, it means that the utilization rate of the Buck circuit is relatively low at this time. At this time, first reduce the set voltage value of the Buck circuit. When the output voltage of the Buck circuit is stable, continue to fine-tune the linear adjustable circuit. Repeat this process until the duty cycle of the Buck circuit is greater than 80% and the output current reaches the set current. The system enters the stable adjustment area. At this time, fix the set voltage of the Buck circuit, and continue to adjust the output current by fine-tuning the linear adjustable circuit, thereby achieving precise and efficient control.

[0040] 6. When the output current of the power supply cannot reach a difference less than the first threshold value from the set current within the set time, and the duty cycle of the Buck buck circuit is always greater than 80%, the set voltage of the Buck buck circuit is increased, and accurate current output can be achieved through voltage closed-loop control of the Buck circuit and current closed-loop control of the linear adjustable circuit.

[0041] pass Figure 6 and Figure 7 By comparing with the power supply device shown in the figure, it can be seen that the magnetic field generated by the device of the present invention when applied to the accelerator power supply is significantly better than the power supply device of traditional design in terms of signal stability and noise.

[0042] 1. The power supply system of the present invention consists of seven parts: a DC voltage input unit, a Buck step-down circuit unit, a microprocessor MCU unit, an adjustable linear circuit unit, a bipolar control circuit unit, a voltage and current sampling circuit unit, and a bipolar current output unit. It is very different from existing switching power supplies or linear power supplies.

[0043] 2. This method first performs constant voltage closed-loop control on the Buck circuit, and then performs current constant current closed-loop control on the adjustable linear circuit. By adjusting the duty cycle of the Buck circuit, the pulse utilization rate of the Buck circuit is determined, thereby adjusting the output voltage of the Buck circuit to achieve accurate, stable and efficient control of the Buck circuit. The output current is then fine-tuned through the adjustable linear circuit to achieve current control with higher accuracy and higher stability.

[0044] 3. The present invention effectively solves the need for seamless switching of current polarity in a particle accelerator power supply by adding a bipolar control circuit and utilizing the switching function of the switch tube.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A low ripple bipolar constant current power supply for particle accelerator, characterized in that: It includes a DC voltage input unit, a Buck step-down circuit unit, a microprocessor, an adjustable linear circuit unit, a bipolar control circuit unit, a voltage and current sampling circuit unit, and a bipolar current output unit which are connected in sequence; The DC voltage input unit is configured as a flyback power supply module; The Buck step-down circuit unit includes a switch tube Q1, a switch tube Q2, an inductor Lr1, a capacitor C1, and a capacitor C2. The drain of the switch tube Q1 is connected to the source of the switch tube Q2 to form a series branch. The series branch is connected in parallel with the capacitor C1 and then connected across the two output ends of the DC voltage input unit. The connection point of the series branch is connected to the inductor Lr1 and the capacitor C2 to access the negative output end of the DC voltage input unit. The two ends of the capacitor C2 serve as the output of the Buck step-down circuit unit. The microprocessor controls the switch tubes Q1 and Q2 to open and close through PWM. The adjustable linear circuit unit includes a transistor Q3, a transistor Q4, and a capacitor C3. The transistor Q3 and the transistor Q4 form a Darlington structure with the base of the transistor Q3 as the control end, which is connected to the positive output end of the Buck buck circuit unit. The base of the transistor Q3 is connected to the negative output end of the Buck buck circuit unit via the capacitor C3. The microprocessor outputs analog quantity to control the base of the transistor Q3 through the DAC chip and the operational amplifier unit. The bipolar control circuit unit forms a bridge circuit through four switch tubes controlled by a microprocessor; The voltage and current sampling circuit unit samples the output voltage and output current of the main circuit to the microprocessor; The bipolar current output unit comprises a capacitor group connected in parallel to the output end of the main loop, and the capacitor group forms a filtering processing system in combination with an external particle accelerator coil load.

2. The low ripple bipolar constant current power supply according to claim 1, characterized in that: The Buck step-down circuit unit adopts a voltage loop control system. The set voltage of the Buck circuit voltage loop is 1 / N of the output voltage of the DC voltage input unit, where N is an integer. The output voltage sampling signal detected by the voltage and current sampling circuit unit and the set voltage are sent to the voltage proportional integral differential PID controller for closed-loop control. The output of the closed-loop control generates a pulse width modulation signal from the microprocessor to control the conduction of the switch tubes Q1 and Q2. The adjustable linear circuit unit adopts a current closed-loop control system, which puts the output current sampling signal detected by the set current and voltage current sampling circuit unit into the current proportional integral differential Pid regulator, calculates the size of the analog output signal DA of the adjustable linear circuit, and then amplifies the analog signal DA through the operational amplifier to control the conduction of transistors Q3 and Q4.

3. The low ripple bipolar constant current power supply according to claim 2, characterized in that: Synchronous control switches Q1 and Q2 are used to form alternating complementary conduction with dead zone control.

4. The low ripple bipolar constant current power supply according to claim 3, characterized in that: The dead time is set between 100 nanoseconds and 500 nanoseconds.

5. The low ripple bipolar constant current power supply according to claim 3, characterized in that: The switching frequency of PWM must be greater than 100kHz.

6. The low ripple bipolar constant current power supply according to claim 3, characterized in that: When the difference between the output current of the power supply and the set current is less than the first threshold, the duty cycle of the pulse width of the Buck buck circuit unit is determined. When the output duty cycle is greater than 80%, the current is fine-tuned through the adjustable linear circuit unit. If the output duty cycle of the Buck buck circuit unit is less than 50%, the value of the set voltage of the Buck buck circuit is reduced. After the output voltage of the Buck buck circuit is stable, the adjustable linear circuit unit is continuously fine-tuned. This control is continuously cyclically performed until the output duty cycle of the Buck buck circuit is greater than 80% and the difference between the output current of the power supply and the set current is less than the first threshold. The set voltage of the Buck buck circuit is fixed, and the current is continuously fine-tuned through the adjustable linear circuit unit. When the output current of the power supply cannot reach a difference less than the first threshold with the set current within the set time, and the duty cycle of the Buck step-down circuit is always greater than 80%, the set voltage of the Buck step-down circuit is increased.

7. The low ripple bipolar constant current power supply according to claim 1, characterized in that: The switch tube in the Buck step-down circuit uses a high-speed MOSFET.

8. The low ripple bipolar constant current power supply according to claim 1, characterized in that: The voltage and current sampling circuit unit performs data conversion through a high-precision ADC chip, and the microprocessor reads the high-precision ADC chip through an SPI or I2C bus.

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