Current control device for fast switching of high magnetic fields

Abstract

The application discloses a kind of strong magnetic field fast conversion current control device, including first PID regulating circuit, second PID regulating circuit, first insulated gate bipolar transistor, second insulated gate bipolar transistor, coil, signal amplifier, hall element, DC power supply, PWM control circuit, voltage sampling module and impedance calculation module, first PID regulating circuit is used to combine current control signal and second voltage signal, and first control voltage signal is obtained;First insulated gate bipolar transistor is used to adjust the loop impedance of coil, and then regulate coil current;Second PID regulating circuit is used to combine third control voltage signal and sampling voltage signal, and second control voltage signal is obtained;Second insulated gate bipolar transistor is used to regulate supply voltage signal.The application can speed up the current change speed of inductive load, while considering current output capacity and output efficiency.The application can be widely applied to current source control technical field.

Description

Technical Field

[0001] This invention relates to the field of current source control technology, and in particular to a current control device for rapid transformation of a strong magnetic field. Background Technology

[0002] In superconducting cold atom systems, the coupling between atoms and the superconducting chip is crucial. Controlling the magnetic field at the position of the atomic cluster requires a highly stable and fast-responding current source. However, since multi-turn coils are generally inductive, achieving microsecond-level response times remains challenging. Many research groups, both domestically and internationally, have employed additional current control devices to manage the coil current in cold atom systems, but these methods have limitations in terms of power and speed. While many commercially available high-power power supplies offer significant current output capabilities, few current sources are optimized for response speeds to inductive loads.

[0003] For most commonly used digital devices, a slower response time doesn't have a significant impact; the switching speed doesn't affect the device's operation. However, in cold atom systems, this requirement becomes much more stringent. Atoms have very limited lifetimes, and without sufficiently fast manipulation of their magnetic fields, it's practically impossible to observe the desired results. Furthermore, due to system stability requirements, the power supply often needs to use an uninterruptible power supply (UPS) or battery power, which places certain demands on output efficiency. Summary of the Invention

[0004] To address the aforementioned technical problems, the objective of this invention is to provide a current control device with a strong magnetic field that rapidly changes, which can accelerate the current change rate of inductive loads while simultaneously considering current output capability and output efficiency.

[0005] The technical solution adopted in this invention is: a current control device for rapid change of strong magnetic field, comprising a first PID adjustment circuit, a second PID adjustment circuit, a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a coil, a signal amplifier, a Hall element, a DC power supply, a PWM control circuit, a voltage sampling module, and an impedance calculation module, wherein:

[0006] The coil is used to generate coil current;

[0007] The Hall element is used to convert the coil current into a first voltage signal;

[0008] The signal amplifier is used to scale the first voltage signal to obtain the second voltage signal;

[0009] The first PID control circuit is used to combine the current control signal and the second voltage signal to obtain the first control voltage signal;

[0010] The first insulated gate bipolar transistor is used to adjust the coil circuit impedance in conjunction with the first control voltage signal, thereby regulating the coil current;

[0011] The DC power supply is used to generate the output voltage;

[0012] The voltage sampling module is used to sample the power supply voltage signal to obtain the sampled voltage signal;

[0013] The impedance calculation module is used to calculate the loop impedance and output a third control voltage signal;

[0014] The second PID control circuit is used to combine the third control voltage signal and the sampled voltage signal to obtain the second control voltage signal;

[0015] The PWM control circuit is used to convert the second control voltage signal into a PWM control signal.

[0016] The second insulated gate bipolar transistor is used to regulate the supply voltage signal by combining the PWM control signal and the output voltage.

[0017] Furthermore, the PID control circuit includes a PI control circuit and a shutdown acceleration circuit, wherein:

[0018] The PI control circuit includes a first operational amplifier, a first capacitor, a first potentiometer, and a second potentiometer.

[0019] The shutdown acceleration circuit includes a first resistor, a second transistor, and a first diode;

[0020] One end of the first resistor is connected to the gate of the first insulated-gate bipolar transistor and the cathode of the first diode; the other end of the first resistor is connected to the emitter of the second transistor; the collector of the second transistor is grounded; the base of the second transistor is connected to the anode of the first diode, the output of the first operational amplifier, and the first fixed terminal of the first potentiometer; the second fixed terminal of the first potentiometer is connected to one end of the first capacitor; the other end of the first capacitor is connected to the inverting input of the first operational amplifier and the first fixed terminal of the second potentiometer; the second fixed terminal of the second potentiometer is connected to the output of the signal amplifier; the non-inverting input of the first operational amplifier is connected to the current control signal input.

[0021] Furthermore, the second transistor is used to accelerate the turn-off process of the first insulated-gate bipolar transistor. When the output voltage signal of the first operational amplifier reaches the gate of the first insulated-gate bipolar transistor through the first diode, the first insulated-gate bipolar transistor is turned on. When the output voltage signal of the first operational amplifier becomes low, the voltage between the BE of the second transistor is less than the turn-on voltage, the second transistor is turned on, providing a low-impedance path for the first insulated-gate bipolar transistor, and the gate charge of the first insulated-gate bipolar transistor is rapidly released along the first resistor, the emitter of the second transistor, and the base of the second transistor.

[0022] Furthermore, the first diode is used to protect the base and emitter of the second transistor from reverse breakdown when conduction begins.

[0023] Furthermore, the calculation expression for the control voltage of the PI control circuit is as follows:

[0024]

[0025] Wherein, Uc represents the voltage value of the output control signal of the PI control circuit, Ur represents the voltage value of the input current control signal, Uh represents the voltage value of the output signal of the signal amplifier, RV1 represents the resistance value of the first potentiometer, RV2 represents the resistance value of the second potentiometer, C1 represents the capacitance value of the first capacitor, and t represents the timing control time.

[0026] Furthermore, the current control device for rapid transformation of a strong magnetic field according to the present invention includes the following steps in its control method:

[0027] The system parameters are determined based on the gain of the system transfer function, and the maximum operating current is set.

[0028] Measure the voltage value of the current control signal, the coil internal resistance, and the coil current;

[0029] Based on system parameters, maximum operating current, voltage value of current control signal, and voltage required by coil current calculation device;

[0030] The voltage required by the device is compared with the voltage of the coil, and the voltage required by the device is amplified based on the comparison result to obtain the final control voltage;

[0031] The voltage value of the current control signal is modulated into the final control voltage using a PWM control circuit.

[0032] Furthermore, the voltage required by the device is calculated using the following expression:

[0033] Us = K * (1 + Is / Im) * Ur

[0034] Where Us represents the voltage required by the device, K represents the system parameters, Is represents the coil current, Im represents the maximum operating current, and Ur represents the voltage value of the current control signal.

[0035] The beneficial effects of this invention are as follows: This invention dissipates residual energy in the coil by using an insulated-gate bipolar transistor (IGBT), thereby shortening the duration of residual current; it accelerates the turn-off process of the IGBT by using a transistor; it prevents transistor breakdown and residual current from flowing into the drive circuit while using a diode for conduction; it achieves timing control of the current by using a PI control circuit; and it optimizes the working efficiency of the main circuit by regulating the battery output voltage through a systematic regulation method, thereby reducing heat loss in the IGBT; ultimately, it accelerates the current change rate of inductive loads while balancing current output capability and output efficiency. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the current control device for rapid conversion of a strong magnetic field according to the present invention.

[0037] Figure 2 This is an equivalent circuit diagram of the insulated gate bipolar transistor turn-off process of a current control device for rapid switching of a strong magnetic field according to the present invention.

[0038] Figure 3 This is a response curve of the insulated gate bipolar transistor turn-off process of a current control device for rapid switching of a strong magnetic field according to the present invention.

[0039] Figure 4 This is a schematic diagram of the PID regulation circuit of a current control device for rapid change of strong magnetic field according to the present invention.

[0040] Figure 5 This is a timing control schematic diagram of a current control device for rapid transformation of a strong magnetic field according to the present invention;

[0041] Figure 6 This is a flowchart of the control method of a current control device for rapid transformation of a strong magnetic field according to the present invention;

[0042] Figure description: U1A, first operational amplifier; U2A, signal amplifier; C1, first capacitor; RV1, first potentiometer; RV2, second potentiometer; D1, first diode; R1, first resistor; Q2, second transistor; Q1, first insulated gate bipolar transistor; L1, equivalent inductance of coil; R2, internal resistance of coil; C2, equivalent capacitance of coil; Hall element; Vc, third control voltage signal; Vf, sampling voltage signal. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0044] Reference Figure 1 A current control device for rapid switching of a strong magnetic field includes a first PID control circuit, a second PID control circuit, a first insulated gate bipolar transistor (IGBT), a second insulated gate bipolar transistor, a coil, a signal amplifier, a Hall element, a DC power supply, a PWM control circuit, a voltage sampling module, and an impedance calculation module, wherein:

[0045] The coil is used to generate coil current;

[0046] The Hall element is used to convert the coil current into a first voltage signal;

[0047] The signal amplifier, which is composed of an instrumentation amplifier, is used to scale the first voltage signal to obtain the second voltage signal;

[0048] The first PID control circuit is used to combine the current control signal and the second voltage signal to obtain the first control voltage signal;

[0049] The first insulated gate bipolar transistor is used to adjust the coil circuit impedance in conjunction with the first control voltage signal, thereby regulating the coil current;

[0050] The DC power supply is used to generate the output voltage;

[0051] The voltage sampling module is used to sample the power supply voltage signal to obtain the sampled voltage signal;

[0052] The impedance calculation module is composed of a single-chip microcomputer STM32F407, which is used to collect the power supply voltage and coil current, calculate the circuit impedance, and output a third control voltage signal.

[0053] The second PID control circuit is used to combine the third control voltage signal and the sampled voltage signal to obtain the second control voltage signal;

[0054] The PWM control circuit consists of a general-purpose PWM control chip and its corresponding peripheral circuits, and is used to convert the second control voltage signal into a PWM control signal.

[0055] The second insulated gate bipolar transistor is used to regulate the supply voltage signal by combining the PWM control signal and the output voltage.

[0056] The specific control flow of this invention is as follows: A waveform generator generates a current control signal, which is then processed by a first PID control circuit to perform a proportional-integral operation on the input current control signal and the second voltage signal generated by the actual current. The resulting first control voltage signal is transmitted to the base of a first insulated-gate bipolar transistor (IGBT) to drive and control the IGBT. Under the action of the first control voltage signal, the IGBT adjusts the coil circuit impedance, thereby regulating the coil current. A Hall element converts the coil current of the coil circuit into a first voltage signal, which is then amplified or reduced by a signal amplifier to obtain a second voltage signal. The first PID control circuit receives the second voltage signal and performs real-time adjustments to form a closed-loop control. On the other hand, the impedance calculation module calculates the circuit impedance based on the power supply voltage and coil current collected in the coil circuit, and outputs a third control voltage signal Vc. This third control voltage signal is added to the sampling voltage Vf of the power supply voltage collected by the voltage sampling module and input to the second PID control circuit to obtain the second control voltage signal. The second control voltage signal is converted into a PWM control signal by a PWM control circuit, which then controls the power supply voltage Vo through the second IGBT to form a closed-loop control. This allows the supply voltage Vo to be adjusted according to the circuit impedance, thereby reducing the losses in the main circuit.

[0057] For inductive loads like coils, when the power input changes from a large current to zero, the energy within the coil will still exist as current for a period of time. To shorten this current's duration, this invention uses an insulated-gate bipolar transistor (IGBT) to dissipate this energy as quickly as possible. In this part of the circuit, the IGBT can be equivalent to a variable resistor, its resistance determined by the voltage input to the gate of the IGBT. Therefore, at the instant the power input voltage becomes zero, the equivalent circuit diagram can be obtained using... Figure 2 This indicates that the response time of the circuit is as follows: Figure 3 As shown, the transient current response of the equivalent inductor at this time is expressed as follows:

[0058]

[0059]

[0060] Where L represents the equivalent inductance of the insulated-gate bipolar transistor (IGBT), R represents the equivalent resistance of the IGBT, I0 represents the initial current, t represents time, and i L This represents the transient current response of the equivalent inductance.

[0061] Therefore, as long as the insulated gate bipolar transistor can reach the high impedance state quickly, the turn-off time can be reduced. In this specific embodiment of the invention, the PID control circuit has been optimized.

[0062] Reference Figure 4 The PID control circuit includes a PI control circuit and a shutdown acceleration circuit, wherein:

[0063] The PI control circuit includes a first operational amplifier U1A, a first capacitor C1, a first potentiometer RV1, and a second potentiometer RV2;

[0064] The shutdown acceleration circuit includes a first resistor R1, a second transistor Q2, and a first diode D1;

[0065] One end of the first resistor R1 is connected to the gate of the first insulated-gate bipolar transistor Q1 and the cathode of the first diode D1; the other end of the first resistor R1 is connected to the emitter of the second transistor Q2; the collector of the second transistor Q2 is grounded; the base of the second transistor Q2 is connected to the anode of the first diode D1, the output terminal of the first operational amplifier U1A, and the first fixed terminal of the first potentiometer RV1; the second fixed terminal of the first potentiometer RV1 is connected to one end of the first capacitor C1; the other end of the first capacitor C1 is connected to the inverting input terminal of the first operational amplifier U1A and the first fixed terminal of the second potentiometer RV2; the second fixed terminal of the second potentiometer RV2 is connected to the output terminal of the signal amplifier U2A; the non-inverting input terminal of the first operational amplifier U1A is connected to the current control signal input terminal.

[0066] In the turn-off acceleration circuit, this invention specifically uses a second transistor (PNP transistor) to accelerate the turn-off process of the insulated-gate bipolar transistor (IGBT). When the output voltage signal of the first operational amplifier reaches the gate of the first IGBT through the first diode, the first IGBT is turned on. When the output voltage signal of the first operational amplifier becomes low, the voltage between the base and emitter of the second transistor is less than the turn-on voltage, and the second transistor is turned on, providing a low-impedance path for the first IGBT. The gate charge of the first IGBT is rapidly released along the first resistor, the emitter of the second transistor, and the base of the second transistor, thereby rapidly pulling down the gate voltage of the IGBT.

[0067] Preferably, the first diode, while serving as the conduction point, protects the base and emitter of the second transistor from reverse breakdown at the start of conduction, preventing discharge current from flowing into the drive circuit. The smaller discharge loop can greatly reduce the impact on other circuits.

[0068] In a PI control circuit, to achieve timing control of the current, a waveform generator produces a current control signal, which is then input to the positive input of the first operational amplifier U1A. The coil current in the coil circuit is converted into a first voltage signal by a Hall element. This first voltage signal is then amplified or reduced by a signal amplifier U2A to obtain a second voltage signal. The second voltage signal is then input to the inverting input of the first operational amplifier U1A via a second potentiometer RV2. The current control signal and the second voltage signal undergo proportional-integral operations to obtain the control voltage output by the PI control circuit. The calculation expression is as follows:

[0069]

[0070] Wherein, Uc represents the voltage value of the output control signal of the PI control circuit, Ur represents the voltage value of the input current control signal, Uh represents the voltage value of the output signal of the signal amplifier, RV1 represents the resistance value of the first potentiometer, RV2 represents the resistance value of the second potentiometer, C1 represents the capacitance value of the first capacitor, and t represents the timing control time.

[0071] The control voltage output from the PI control circuit, after passing through the turn-off acceleration circuit, is transmitted to the gate of the insulated gate bipolar transistor (IGBT) to drive and control the IGBT, thereby adjusting the output current. Then, a Hall element converts the adjusted output current value into a voltage signal, which is transmitted back to the inverting input of the PI control circuit, forming a closed-loop system.

[0072] After completing the current control circuit, it is also necessary to optimize the operating efficiency of the main circuit. If only the above circuit is used to control a constant voltage source such as a battery or UPS, a large portion of the energy will be lost as heat in the insulated-gate bipolar transistor. (Refer to...) Figure 5 When adopting Figure 5 When using timing sequences to control the current in a circuit, assuming the coil's internal resistance is 0.1Ω and the battery voltage is 10V, at t=0, the insulated-gate bipolar transistor (IGBT) is fully on, its equivalent resistance is close to zero, and the power output from the battery is entirely borne by the coil. At t=2, the IGBT is not fully on, its equivalent internal resistance is close to the coil's internal resistance, and the power borne by the IGBT is Pt = 50 * 50 * 0.1 = 250W. At this time, the coil requires a current of 50A, and a supply voltage of only 5V is sufficient. To maximize circuit efficiency, energy loss on the IGBT needs to be minimized; that is, the IGBT must be close to fully on at all times.

[0073] To ensure that the gate-side bipolar transistor is always close to fully conductive, this invention uses a systematic control method to regulate the battery's output voltage, referring to... Figure 6The control method includes the following steps:

[0074] The system parameters are determined based on the gain of the system transfer function, and the maximum operating current is set.

[0075] Measure the voltage value of the current control signal, the coil internal resistance, and the coil current;

[0076] Based on system parameters, maximum operating current, voltage value of current control signal, and voltage required by coil current calculation device;

[0077] The voltage required by the device is compared with the voltage of the coil, and the voltage required by the device is amplified based on the comparison result to obtain the final control voltage;

[0078] The voltage value of the current control signal is modulated into the final control voltage using a PWM control circuit.

[0079] The voltage required by the device is calculated using the following expression:

[0080] Us = K * (1 + Is / Im) * Ur

[0081] Where Us represents the voltage required by the device, K represents the system parameters, Is represents the coil current, Im represents the maximum operating current, and Ur represents the voltage value of the current control signal.

[0082] The voltage of the coil is calculated using the following expression:

[0083] Ux=Is·r

[0084] Where Ux represents the voltage across the coil, Is represents the current through the coil, and r represents the internal resistance of the coil.

[0085] When the voltage Us required by the device is lower than the voltage Ux of the coil, the current cannot operate at the normal value. In this case, the voltage Us required by the device needs to be amplified by a certain proportion. When the voltage Us required by the device is higher than the voltage Ux of the coil, the voltage Us required by the current device is used directly.

[0086] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A current control device for rapid transformation of a strong magnetic field, characterized in that, It includes a first PID control circuit, a second PID control circuit, a first insulated-gate bipolar transistor (IGBT), a second IGBT, a coil, a signal amplifier, a Hall element, a DC power supply, a PWM control circuit, a voltage sampling module, and an impedance calculation module, wherein: The coil is used to generate coil current; The Hall element is used to convert the coil current into a first voltage signal; The signal amplifier is used to scale the first voltage signal to obtain the second voltage signal; The first PID control circuit is used to combine the current control signal and the second voltage signal to obtain the first control voltage signal; The first insulated gate bipolar transistor is used to adjust the coil circuit impedance in conjunction with the first control voltage signal, thereby regulating the coil current; The DC power supply is used to generate the output voltage; The voltage sampling module is used to sample the power supply voltage signal to obtain the sampled voltage signal; The impedance calculation module is used to calculate the loop impedance and output a third control voltage signal; The second PID control circuit is used to combine the third control voltage signal and the sampled voltage signal to obtain the second control voltage signal; The PWM control circuit is used to convert the second control voltage signal into a PWM control signal. The second insulated gate bipolar transistor is used to regulate the supply voltage signal by combining the PWM control signal and the output voltage.

2. The current control device for rapid conversion of a strong magnetic field according to claim 1, characterized in that, The first PID control circuit includes a PI control circuit and a turn-off acceleration circuit, wherein: The PI control circuit includes a first operational amplifier, a first capacitor, a first potentiometer, and a second potentiometer. The shutdown acceleration circuit includes a first resistor, a second transistor, and a first diode; One end of the first resistor is connected to the gate of the first insulated-gate bipolar transistor and the cathode of the first diode; the other end of the first resistor is connected to the emitter of the second transistor; the collector of the second transistor is grounded; the base of the second transistor is connected to the anode of the first diode, the output of the first operational amplifier, and the first fixed terminal of the first potentiometer; the second fixed terminal of the first potentiometer is connected to one end of the first capacitor; the other end of the first capacitor is connected to the inverting input of the first operational amplifier and the first fixed terminal of the second potentiometer; the second fixed terminal of the second potentiometer is connected to the output of the signal amplifier; the non-inverting input of the first operational amplifier is connected to the current control signal input.

3. The current control device for rapid transformation of a strong magnetic field according to claim 2, characterized in that, The second transistor is used to accelerate the turn-off process of the first insulated-gate bipolar transistor. When the output voltage signal of the first operational amplifier reaches the gate of the first insulated-gate bipolar transistor through the first diode, the first insulated-gate bipolar transistor is turned on. When the output voltage signal of the first operational amplifier becomes low, the voltage between the BE of the second transistor is less than the turn-on voltage, and the second transistor is turned on, providing a low-impedance path for the first insulated-gate bipolar transistor. The gate charge of the first insulated-gate bipolar transistor is rapidly released along the first resistor, the emitter of the second transistor, and the base of the second transistor.

4. The current control device for rapid transformation of a strong magnetic field according to claim 2, characterized in that, The first diode is used to protect the base and emitter of the second transistor from reverse breakdown when conduction begins.

5. The current control device for rapid conversion of a strong magnetic field according to claim 2, characterized in that, The PI control circuit has the following expression for calculating the control voltage: in, This represents the voltage value of the control signal output by the PI control circuit. This represents the voltage value of the input current control signal. This represents the voltage value of the output signal of the signal amplifier. This indicates the resistance value of the first potentiometer. This indicates the resistance value of the second potentiometer. This indicates the capacitance value of the first capacitor. Indicates the timing control period.

6. A current control device for rapid transformation of a strong magnetic field according to any one of claims 1-5, characterized in that, Its regulation methods include the following steps: The system parameters are determined based on the gain of the system transfer function, and the maximum operating current is set. Measure the voltage value of the current control signal, the coil internal resistance, and the coil current; Based on system parameters, maximum operating current, voltage value of current control signal, and voltage required by coil current calculation device; The voltage required by the device is compared with the voltage of the coil, and the voltage required by the device is amplified based on the comparison result to obtain the final control voltage; The voltage value of the current control signal is modulated into the final control voltage using a PWM control circuit.

7. The current control device for rapid transformation of a strong magnetic field according to claim 6, characterized in that, The voltage required by the device is calculated using the following expression: in, Indicates the voltage required by the device. Indicates system parameters, Indicates the coil current. Indicates the maximum operating current. This indicates the voltage value of the current control signal.

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