Active magnetic compensation driving system based on forward converter

Abstract

The invention relates to the technical field of active magnetic compensation, and discloses an active magnetic compensation driving system based on a forward converter, and the system comprises a power module which comprises an AC-DC circuit, a double-end forward circuit and an auxiliary power supply; the constant current source module is connected with the output end of the power supply module, and the constant current source module comprises a coil load interface, a constant current structure and a current signal acquisition circuit, and the constant current structure is formed by four parallel MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) and an operational amplifier; one end of the constant current structure is connected with the coil load interface, and the other end of the constant current structure is connected with the current signal acquisition circuit; the digital control module comprises a control unit and a lower computer; the invention discloses a uniaxial Helmholtz coil and a fluxgate sensor. According to the invention, the output power and the precision can be improved, and the requirements of high-precision applications such as active magnetic compensation are met.

Description

Technical Field

[0001] This invention relates to the field of active magnetic compensation technology, and more specifically, to an active magnetic compensation drive system based on a forward converter. Background Technology

[0002] Near-zero magnetic field environments have unique applications in quantum precision measurement, magnetometer calibration and testing, and biomagnetic field measurement. A strictly defined zero magnetic field environment requires a spatial magnetic field strength of exactly zero. However, in engineering practice, due to physical limitations such as geomagnetic field shielding technology and material permeability, only extremely low magnetic field environments can be practically achieved. As research progresses, the requirements for near-zero magnetic fields are constantly increasing, placing higher demands on the devices providing these environments and their driving components. This places higher demands on the driving components of the devices, specifically the need for active magnetic field compensation to achieve a near-zero magnetic field environment.

[0003] Helmholtz coils are the most commonly used active magnetic compensation devices for generating a uniform magnetic field within a certain spatial range. Therefore, the Helmholtz coil in the drive system of a magnetic compensation device is a crucial link in achieving precise magnetic compensation. To obtain a high-precision and stable adjustable magnetic field, a high-performance drive system is required, including a high-precision power supply circuit and a stable and reliable current source circuit. Therefore, high-precision and highly stable current source circuits and power supply circuits are essential for generating a high-quality magnetic field. Currently, commonly used magnetic field drive systems are built from various commercially available devices, resulting in large size and fixed functions. Furthermore, to meet the requirements for near-zero magnetic fields, expensive specialized equipment is needed, such as providing a clock signal through an additional highly stable clock reference. This introduces many inconveniences to the practical implementation of high-precision active magnetic compensation.

[0004] Therefore, it is necessary to provide an active magnetic compensation drive system based on a forward converter to solve the problems of large size, fixed function, and the need for expensive special equipment to achieve near-zero magnetic field and inconvenience in achieving high-precision active magnetic compensation in current magnetic field drive systems. Summary of the Invention

[0005] In view of this, the present invention proposes an active magnetic compensation drive system based on a forward converter, which aims to solve the problems of large size, fixed function and the need for expensive special equipment to achieve near-zero magnetic field in current magnetic field drive systems, as well as the inconvenience of achieving high-precision active magnetic compensation.

[0006] This invention proposes an active magnetic compensation drive system based on a forward converter, comprising:

[0007] The power module includes an AC-DC circuit, a two-terminal forward converter circuit, and an auxiliary power supply, wherein the output terminal of the AC-DC circuit is connected to the two-terminal forward converter circuit and the auxiliary power supply respectively.

[0008] A constant current source module is connected to the output terminal of the power supply module. The constant current source module includes a coil load interface, a constant current structure built by four parallel MOSFETs and operational amplifiers, and a current signal acquisition circuit. The coil load interface is connected to the power supply module and is used to output current. One end of the constant current structure is connected to the coil load interface, and the other end is connected to the current signal acquisition circuit.

[0009] The digital control module includes a control unit and a lower-level machine. One end of the control unit is connected to the current signal acquisition circuit, and the other end is connected to the lower-level machine.

[0010] A single-axis Helmholtz coil and a fluxgate sensor are provided. The input terminal of the single-axis Helmholtz coil is connected to the coil load interface. The fluxgate sensor is disposed inside the single-axis Helmholtz coil and is connected to the control unit.

[0011] Furthermore, the AC-DC circuit includes:

[0012] The filter and rectifier circuit has its input terminal connected to the AC power grid.

[0013] The power factor correction circuit has its input terminal connected to the filter and rectifier circuit, and its output terminal connected to the double-ended forward converter circuit and the auxiliary power supply, respectively.

[0014] Furthermore, the dual-terminal forward converter circuit includes:

[0015] The gate driver, bootstrap circuit, and transformer are connected to the output of the power factor correction circuit.

[0016] The output rectifier and filter circuit is connected to the output terminals of the gate driver, bootstrap circuit, and transformer.

[0017] The PCM control chip has its input terminal connected to the output terminal of the output rectifier and filter circuit, and its output terminal connected to the gate driver, bootstrap circuit, and transformer.

[0018] Furthermore, the auxiliary power supply includes:

[0019] The Flyback circuit is connected to the output of the power factor correction circuit, and the Flyback circuit is used to output three different isolation voltages;

[0020] The DC-DC converter has its input terminal connected to the output terminal of the Flyback circuit. The DC-DC converter includes a Cuk circuit and a Buck circuit. The DC-DC converter is used to convert the output voltage of the Flyback circuit.

[0021] A low-dropout linear regulator circuit is used to convert the output voltage of the DC-DC converter.

[0022] Furthermore, the Cuk circuit is used to convert one of the output voltages of the Flyback circuit to -15V;

[0023] The Buck circuit is used to convert another output voltage of the Flyback circuit to 15V;

[0024] The low-dropout linear regulator circuit is used to convert the output voltages of the Cuk circuit and the Buck circuit to ±12V and 3.3V, respectively.

[0025] Furthermore, the current signal acquisition circuit includes:

[0026] A sampling resistor is connected to the output terminal of the constant current structure;

[0027] An instrumentation amplifier has its input terminal connected to the output terminal of the sampling resistor, and its output terminal is connected to the digital control module.

[0028] Furthermore, the control unit includes:

[0029] An ARM microcontroller is connected to the lower-level device via the IIC protocol, and the ARM microcontroller is used to obtain the set current of the lower-level device;

[0030] The ADC is connected to the output of the constant current source module and is also connected to the fluxgate sensor. The ADC is connected to the ARM microcontroller via the SPI protocol.

[0031] The DAC connects to the ARM microcontroller via the SPI protocol.

[0032] Furthermore, in the four parallel MOSFETs, each circuit has an operational amplifier and a precision sampling resistor to construct an independent feedback control loop, resulting in a total output current instability of 13ppm and short-term fluctuations of less than 300μA.

[0033] The digital control module is based on an ARM microcontroller and integrates a 16-bit precision digital-to-analog converter, a 16-bit precision analog-to-digital converter, and a reference chip. It adjusts the current setpoint in real time through a PID algorithm to form a closed-loop control. The lower-level computer communicates with the digital control module through the IIC protocol and displays the system's operating status and output current parameters in real time on its OLED screen. It can also set and read the current setpoint and actual value in real time.

[0034] Furthermore, the constant current structure also includes:

[0035] The compensation circuit is constructed by resistors in each constant current structure;

[0036] Active cooling structure, including heat sink and fan.

[0037] Furthermore, the AC-DC circuit takes in 220V AC power and outputs 42V / 7A DC power with a ripple of less than 0.5%.

[0038] The auxiliary power supply is used to output ±12V / 1A, 15V / 0.1A and 3.3V / 1A;

[0039] The dual-terminal forward converter is used to provide a 42V voltage and a maximum current of 7A. It adopts a peak current mode loop control method and controls the loop stability through a compensation network.

[0040] Compared with existing technologies, the advantages of this invention are as follows: A high-precision, low-ripple power supply design, through the integration of AC-DC circuits and dual-terminal forward converters, provides a dedicated power supply for the current source of traditional magnetic compensation drive systems, with ripple voltage as low as 0.5%, overshoot less than 0.5%, and conversion efficiency increased to 89.08%; Multiple current-sharing constant current sources and low-temperature drift compensation, with a constant current structure built from four parallel MOSFETs and operational amplifiers combined with a current signal acquisition circuit, achieve a long-term output current drift of less than or equal to 300μA and an instability of 13ppm, which improves output power and accuracy compared to traditional single-channel solutions; The digital control circuit, based on an ARM microcontroller's digital PID algorithm, combined with a 16-bit high-precision analog-to-digital converter and digital-to-analog converter chip, achieves closed-loop control of the output current, suppressing magnetic field fluctuations to 40nT and noise power spectral density less than 5nT² / Hz, providing a significant accuracy improvement compared to traditional open-loop control schemes, meeting the requirements of high-precision applications such as active magnetic compensation. Simultaneously, the lower-level computer interacts with the system via IIC, displaying system status and current parameters in real time. Attached Figure Description

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0042] Figure 1 A functional block diagram of an active magnetic compensation drive system based on a forward converter provided in an embodiment of the present invention;

[0043] Figure 2 This is a circuit schematic diagram of AC / DC conversion in a power module provided in an embodiment of the present invention;

[0044] Figure 3This is a circuit diagram of a dual-terminal forward converter in a power module provided in an embodiment of the present invention;

[0045] Figure 4 The circuit diagram of the auxiliary power supply in the power module provided in the embodiment of the present invention;

[0046] Figure 5 The current schematic diagram of the constant current source module provided in the embodiment of the present invention;

[0047] Figure 6 The output voltage ripple diagram of the forward converter in the power module provided in the embodiment of the present invention;

[0048] Figure 7 Output current diagram provided for embodiments of the present invention;

[0049] Figure 8 This is a diagram illustrating the overshoot effect of the output voltage of the dual-terminal forward converter circuit in the power module provided in an embodiment of the present invention.

[0050] Figure 9 A magnetic field fluctuation suppression diagram provided in an embodiment of the present invention;

[0051] Figure 10 The noise power spectral density diagram provided for an embodiment of the present invention. Detailed Implementation

[0052] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] In some embodiments of this application, see Figure 1-10 As shown, this embodiment provides an active magnetic compensation drive system based on a forward converter, including:

[0054] The power module includes an AC-DC circuit, a two-terminal forward converter circuit, and an auxiliary power supply, wherein the output terminal of the AC-DC circuit is connected to the two-terminal forward converter circuit and the auxiliary power supply respectively.

[0055] A constant current source module is connected to the output terminal of the power supply module. The constant current source module includes a coil load interface, a constant current structure built by four parallel MOSFETs and operational amplifiers, and a current signal acquisition circuit. The coil load interface is connected to the power supply module and is used to output current. One end of the constant current structure is connected to the coil load interface, and the other end is connected to the current signal acquisition circuit.

[0056] The digital control module includes a control unit and a lower-level machine. One end of the control unit is connected to the current signal acquisition circuit, and the other end is connected to the lower-level machine.

[0057] A single-axis Helmholtz coil and a fluxgate sensor are provided. The input terminal of the single-axis Helmholtz coil is connected to the coil load interface. The fluxgate sensor is disposed inside the single-axis Helmholtz coil and is connected to the control unit.

[0058] Understandably, the high-precision, low-ripple power supply design, through the integration of AC-DC circuitry and a dual-terminal forward converter, provides a dedicated power supply for the current source of traditional magnetic compensation drive systems, achieving a ripple voltage as low as 0.5%, overshoot less than 0.5%, and conversion efficiency up to 89.08%. Multiple current-sharing constant current sources and low-temperature drift compensation, with a constant current structure built from four parallel MOSFETs and operational amplifiers combined with a current signal acquisition circuit, achieve a long-term output current drift of less than or equal to 300μA and an instability of 13ppm. Compared to traditional single-channel solutions, this improves output power and accuracy. The digital control circuit, based on an ARM microcontroller's digital PID algorithm and combined with a 16-bit high-precision analog-to-digital converter and digital-to-analog converter chip, achieves closed-loop control of the output current, suppressing magnetic field fluctuations to 40nT and achieving a noise power spectral density of less than 5nT. 2 / Hz, offering a significant accuracy improvement over traditional open-loop control schemes, meeting the requirements of high-precision applications such as active magnetic compensation. Simultaneously, the lower-level computer interacts with the system via IIC, displaying system status and current parameters in real time.

[0059] Specifically, such as Figure 1As shown, this invention provides a high-precision magnetic compensation drive system based on a forward converter, comprising three modules: a power supply module, a constant current source module, and a digital control module. The power supply module includes an AC-DC circuit, a two-terminal forward converter (TTF), and an auxiliary power supply. Specifically, the input terminal of the AC-DC circuit of the power supply module is connected to an external 220V single-phase AC power supply. After rectification, filtering, and power factor correction circuits, the AC-DC conversion is completed. The output terminal of the AC-DC circuit is connected to the TTF and the auxiliary power supply, providing its input operating voltage. The input terminal of the TTF of the power supply module is connected to the output voltage of the AC-DC module. After peak current mode loop control and gate drive, it is converted into a high-precision 42 / 7A voltage source required by the subsequent current source circuit. The input terminal of the auxiliary power supply circuit of the power supply module is connected to the output voltage of the AC-DC module, outputting multiple isolated DC voltages. After passing through a Cuk circuit and a Buck circuit, the output voltage is supplied to different parts of the system for normal operation. The input terminal of the constant current source module is connected to the output voltage of the TTF, and the output current is controlled by a loop control method.

[0060] The digital control module uses a 16-bit precision digital-to-analog converter, a 16-bit precision analog-to-digital converter, and a 2.5V reference chip. It adjusts the current setpoint in real time through a PID algorithm, forming a closed-loop control with the constant current source module. It communicates with the digital control module through the IIC protocol and displays the system's operating status and output current parameters in real time on an OLED screen. It supports real-time setting and reading of the current setpoint and actual value.

[0061] In some embodiments of this application, the AC-DC circuit includes:

[0062] The filter and rectifier circuit has its input terminal connected to the AC power grid.

[0063] The power factor correction circuit has its input terminal connected to the filter and rectifier circuit, and its output terminal connected to the double-ended forward converter circuit and the auxiliary power supply, respectively.

[0064] Specifically, such as Figure 2 The AC-DC circuit structure of the power module shown includes a rectifier and filter circuit with a fast-blow fuse, a varistor, and a negative temperature coefficient (NTC) to prevent inrush current. The common-mode inductor, X capacitor, Y capacitor, rectifier bridge, and power factor correction circuit utilize a fixed-frequency CCM control algorithm provided by the control chip. The output inductor current is determined by setting it to 20% of the maximum output current, and the output capacitor is designed based on the required hold time. Low-gate-charge, low-switching-energy switching transistors and small SiC diodes are used to reduce power consumption and interference.

[0065] In some embodiments of this application, the dual-terminal forward converter includes:

[0066] The gate driver, bootstrap circuit, and transformer are connected to the output of the power factor correction circuit.

[0067] The output rectifier and filter circuit is connected to the output terminals of the gate driver, bootstrap circuit, and transformer.

[0068] The PCM control chip has its input terminal connected to the output terminal of the output rectifier and filter circuit, and its output terminal connected to the gate driver, bootstrap circuit, and transformer.

[0069] Specifically, such as Figure 3 The dual-terminal forward converter circuit of the power module shown is designed with key components based on its specific operating conditions. The transformer uses an ETD49 core selected according to the set input / output power, operating frequency, flux density change, and current density. The operating frequency is chosen to be 130kHz, and the final power consumption is determined by selecting a specific number of primary and secondary turns and wires. MOSFETs with a withstand voltage of 600V or higher are selected, along with a specific dual-output gate driver chip without interlocking. A suitable bootstrap circuit is designed to ensure simultaneous switching of the upper and lower transistors. The output LC filter is designed based on the output voltage ripple, using a peak current control chip to stabilize the output voltage. A compensation network is designed in the feedback section of the voltage loop to improve loop stability.

[0070] In some embodiments of this application, the auxiliary power supply includes:

[0071] The Flyback circuit is connected to the output of the power factor correction circuit, and the Flyback circuit is used to output three different isolation voltages;

[0072] The DC-DC converter has its input terminal connected to the output terminal of the Flyback circuit. The DC-DC converter includes a Cuk circuit and a Buck circuit. The DC-DC converter is used to convert the output voltage of the Flyback circuit.

[0073] A low-dropout linear regulator circuit is used to convert the output voltage of the DC-DC converter.

[0074] In some embodiments of this application, the Cuk circuit is used to convert one of the output voltages of the Flyback circuit to -15V;

[0075] The Buck circuit is used to convert another output voltage of the Flyback circuit to 15V;

[0076] The low-dropout linear regulator circuit is used to convert the output voltages of the Cuk circuit and the Buck circuit to ±12V and 3.3V, respectively.

[0077] Specifically, such as Figure 4 The auxiliary power supply circuit of the power module shown outputs 24V and two 15V voltage rails. These are then converted to isolated ±12V and 3.3V voltages via a Cuk circuit, a Boost circuit, and an LDO (Low Dropout Linear Regulator) circuit to power the chips in the entire system. The AP method is used to select the EFD25 magnetic core as the transformer core for the flyback circuit. The specific turns ratio, wire diameter, and winding method are calculated based on the set input / output power, operating frequency, flux density change, and current density. A DC-DC converter circuit converts the isolated 24V to ±12V. First, a Cuk circuit and a Buck circuit convert it to ±15V, and then an LDO converts it to ±12V and 3.3V.

[0078] In some embodiments of this application, the current signal acquisition circuit includes:

[0079] A sampling resistor is connected to the output terminal of the constant current structure;

[0080] An instrumentation amplifier has its input terminal connected to the output terminal of the sampling resistor, and its output terminal is connected to the digital control module.

[0081] In some embodiments of this application, the control unit includes:

[0082] An ARM microcontroller is connected to the lower-level device via the IIC protocol, and the ARM microcontroller is used to obtain the set current of the lower-level device;

[0083] The ADC is connected to the output of the constant current source module and is also connected to the fluxgate sensor. The ADC is connected to the ARM microcontroller via the SPI protocol.

[0084] The DAC connects to the ARM microcontroller via the SPI protocol.

[0085] In some embodiments of this application, each of the four parallel MOSFETs constructs an independent feedback control loop with an operational amplifier and a precision sampling resistor, resulting in a total output current instability of 13ppm and short-term fluctuations of less than 300μA.

[0086] The digital control module is based on an ARM microcontroller and integrates a 16-bit precision digital-to-analog converter, a 16-bit precision analog-to-digital converter, and a reference chip. It adjusts the current setpoint in real time through a PID algorithm to form a closed-loop control. The lower-level computer communicates with the digital control module through the IIC protocol and displays the system's operating status and output current parameters in real time on its OLED screen. It can also set and read the current setpoint and actual value in real time.

[0087] In some embodiments of this application, the constant current structure further includes:

[0088] A compensation circuit, wherein the compensation circuit is constructed by resistors in each constant current structure, is used to improve the loop stability of the current source;

[0089] An active cooling structure, including a heat sink and a fan, is used to reduce thermal noise.

[0090] Specifically, such as Figure 5 The constant current source module shown consists of an operational amplifier, a MOSFET, and a sampling resistor in each channel. The four channels are connected in parallel and a compensation circuit is added. The output current signal is finally collected by the total sampling resistor. Meanwhile, the digital control module is based on an ARM microcontroller and integrates a 16-bit precision digital-to-analog converter, a 16-bit precision analog-to-digital converter, and a reference chip. It adjusts the current setpoint in real time through a PID algorithm to form a closed-loop control. It communicates with the digital control module through the IIC protocol and displays the system's operating status and output current parameters in real time on an OLED screen. It supports real-time setting and reading of the current setpoint and actual value.

[0091] In some embodiments of this application, the AC-DC circuit inputs 220V alternating current and outputs 42V / 7A direct current with ripple less than 0.5%.

[0092] The auxiliary power supply is used to output ±12V / 1A, 15V / 0.1A and 3.3V / 1A;

[0093] The dual-terminal forward converter is used to provide a 42V voltage and a maximum current of 7A. It adopts a peak current mode loop control method and controls the loop stability through a compensation network.

[0094] In summary, this invention presents a high-precision, low-ripple power supply design: by integrating an AC-DC circuit with a power factor correction circuit and a two-terminal forward converter (TTF), it provides a dedicated power supply for the current source of a traditional magnetically compensated drive system, achieving a ripple voltage as low as 0.5%, an overshoot of less than 0.5%, and a conversion efficiency of 89.08%. The filtering and rectifier circuit suppresses power supply noise, avoiding clock jitter and sampling errors caused by power fluctuations, providing a stable, low-noise power supply for the constant current source module and digital control module, ensuring the system's reliability in complex electromagnetic environments.

[0095] Secondly, the multi-channel current sharing constant current source and low temperature drift compensation: the constant current structure built by four parallel MOSFETs and operational amplifiers combined with the current signal acquisition circuit achieves an output current drift of ≤300μA over 4 hours and an instability of 13ppm. Compared with the traditional single-channel solution, it can improve the output power and improve the accuracy. The compensation circuit is embedded in the independent feedback control loop to improve the loop phase margin, effectively suppress the oscillation risk and improve the system stability. At the same time, the active heat dissipation structure (heat sink + fan) controls the MOSFET temperature rise within a safe range, reducing the impact of thermal noise on current stability.

[0096] Furthermore, the ARM microcontroller in the digital control module is an STM32F412 microcontroller. Based on the STM32F412 microcontroller's digital PID algorithm, combined with a 16-bit high-precision analog-to-digital converter and digital-to-analog converter chip, closed-loop control of the output current is achieved. Magnetic field fluctuations are suppressed to 40 nT, and the noise power spectral density is <5 nT. 2 / Hz, offering a significant accuracy improvement over traditional open-loop control schemes, meeting the requirements of high-precision applications such as active magnetic compensation. Simultaneously, the lower-level computer interacts with the system via IIC, displaying system status and current parameters in real time.

[0097] Specifically, Figure 6 The output voltage ripple diagram of the forward converter in the power module provided in the embodiment of the present invention;

[0098] Figure 7 The output current diagram provided in this embodiment of the invention is shown. Specifically, the experiment included a 1-hour preheating period, followed by a 4-hour continuous stability observation. For the quantitative evaluation of current drift characteristics, an instability index based on N consecutive sampling data was used. The calculation method for this index is as follows:

[0099]

[0100] Where ΔI represents the instability index, ΔI σ The standard deviation of current. The average value of the current is 7.020685A. The arithmetic mean of the system output current is 7.020685A, with peak-to-peak fluctuation controlled within ±150μA and a standard deviation of 46.1μA. Calculations show that the 4-hour instability of the current output reaches 13ppm.

[0101] Figure 8 The diagram showing the overshoot effect of the output voltage of the dual-terminal forward converter circuit in the power module provided in this embodiment of the invention shows that during the falling edge, the maximum voltage deviation is 160mV and the recovery time is 10μs; during the rising edge, the maximum voltage deviation is 160mV and the recovery time is 10μs. The recovery speed of the time-domain waveform is less than 1ms, and no oscillation occurs throughout the process, with the overshoot voltage less than 0.4%.

[0102] Figure 9 The magnetic field fluctuation suppression diagram provided in the embodiment of the present invention shows that the magnetic field fluctuation is suppressed to 40 nT.

[0103] Figure 10 The noise power spectral density diagram provided in the embodiment of the present invention shows that the noise power spectral density of the present invention is <5nT. 2 / Hz.

[0104] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program goods. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program goods embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program goods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0106] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An active magnetic compensation drive system based on a forward converter, characterized in that, include: The power module includes an AC-DC circuit, a two-terminal forward converter circuit, and an auxiliary power supply, wherein the output terminal of the AC-DC circuit is connected to the two-terminal forward converter circuit and the auxiliary power supply respectively. A constant current source module is connected to the output terminal of the power supply module. The constant current source module includes a coil load interface, a constant current structure built by four parallel MOSFETs and operational amplifiers, and a current signal acquisition circuit. The coil load interface is connected to the power supply module and is used to output current. One end of the constant current structure is connected to the coil load interface, and the other end is connected to the current signal acquisition circuit. The digital control module includes a control unit and a lower-level machine. One end of the control unit is connected to the current signal acquisition circuit, and the other end is connected to the lower-level machine. A single-axis Helmholtz coil and a fluxgate sensor are provided. The input terminal of the single-axis Helmholtz coil is connected to the coil load interface. The fluxgate sensor is disposed inside the single-axis Helmholtz coil and is connected to the control unit.

2. The active magnetic compensation drive system based on a forward converter according to claim 1, characterized in that, The AC-DC circuit includes: The filter and rectifier circuit has its input terminal connected to the AC power grid. The power factor correction circuit has its input terminal connected to the filter and rectifier circuit, and its output terminal connected to the double-ended forward converter circuit and the auxiliary power supply, respectively.

3. The active magnetic compensation drive system based on a forward converter according to claim 2, characterized in that, The dual-terminal forward converter circuit includes: The gate driver, bootstrap circuit, and transformer are connected to the output of the power factor correction circuit. The output rectifier and filter circuit is connected to the output terminals of the gate driver, bootstrap circuit, and transformer. The PCM control chip has its input terminal connected to the output terminal of the output rectifier and filter circuit, and its output terminal connected to the gate driver, bootstrap circuit, and transformer.

4. The active magnetic compensation drive system based on a forward converter according to claim 2, characterized in that, The auxiliary power supply includes: The Flyback circuit is connected to the output of the power factor correction circuit, and the Flyback circuit is used to output three different isolation voltages; The DC-DC converter has its input terminal connected to the output terminal of the Flyback circuit. The DC-DC converter includes a Cuk circuit and a Buck circuit. The DC-DC converter is used to convert the output voltage of the Flyback circuit. A low-dropout linear regulator circuit is used to convert the output voltage of the DC-DC converter.

5. The active magnetic compensation drive system based on a forward converter according to claim 4, characterized in that, The Cuk circuit is used to convert one of the output voltages of the Flyback circuit to -15V; The Buck circuit is used to convert another output voltage of the Flyback circuit to 15V; The low-dropout linear regulator circuit is used to convert the output voltages of the Cuk circuit and the Buck circuit to ±12V and 3.3V, respectively.

6. The active magnetic compensation drive system based on a forward converter according to claim 1, characterized in that, The current signal acquisition circuit includes: A sampling resistor is connected to the output terminal of the constant current structure; An instrumentation amplifier has its input terminal connected to the output terminal of the sampling resistor, and its output terminal is connected to the digital control module.

7. The active magnetic compensation drive system based on a forward converter according to claim 6, characterized in that, The control unit includes: An ARM microcontroller is connected to the lower-level device via the IIC protocol, and the ARM microcontroller is used to obtain the set current of the lower-level device; The ADC is connected to the output of the constant current source module and is also connected to the fluxgate sensor. The ADC is connected to the ARM microcontroller via the SPI protocol. The DAC connects to the ARM microcontroller via the SPI protocol.

8. The active magnetic compensation drive system based on a forward converter according to claim 7, characterized in that, In the four parallel MOSFETs, each circuit has an operational amplifier and a precision sampling resistor to form an independent feedback control loop. The total output current instability is 13ppm, and the short-term fluctuation is less than 300μA. The digital control module is based on an ARM microcontroller and integrates a 16-bit precision digital-to-analog converter, a 16-bit precision analog-to-digital converter, and a reference chip. It adjusts the current setpoint in real time through a PID algorithm to form a closed-loop control. The lower-level computer communicates with the digital control module through the IIC protocol and displays the system's operating status and output current parameters in real time on its OLED screen. It can also set and read the current setpoint and actual value in real time.

9. The active magnetic compensation drive system based on a forward converter according to claim 1, characterized in that, The constant current structure also includes: The compensation circuit is constructed by resistors in each constant current structure; Active cooling structure, including heat sink and fan.

10. The active magnetic compensation drive system based on a forward converter according to claim 1, characterized in that, The AC-DC circuit takes in 220V AC power and outputs 42V / 7A DC power with a ripple of less than 0.5%. The auxiliary power supply is used to output ±12V / 1A, 15V / 0.1A and 3.3V / 1A; The dual-terminal forward converter is used to provide a 42V voltage and a maximum current of 7A. It adopts a peak current mode loop control method and controls the loop stability through a compensation network.

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