Low noise 100-ampere current source

Abstract

The embodiment of the present invention provides a low-noise 100-ampere current source, which can be applied to the field of current source technology. The current source includes: a loop compensation module, a voltage drive circuit, and a current detection feedback module connected in series in sequence. The current source also includes an energy storage module connected to the voltage drive circuit and the current detection feedback module, wherein the energy storage module is used to provide electric energy to the load coil; the loop compensation module is used to perform compensation operations on the connected analog control signal and the voltage feedback signal, and output a compensation signal; the voltage drive circuit is used to obtain electric energy from the energy storage module through the load coil based on the compensation signal output by the loop compensation module, so as to provide output current to the current detection feedback module; the current detection feedback module is used to sample the output current, and convert the output current into a voltage feedback signal and output it to the loop compensation module, so as to form a feedback loop and adjust the output current.

Description

Technical Field

[0001] The present invention relates to the technical field of current sources, and more specifically, to a low-noise hundred-ampere-level current source. Background Art

[0002] The development of modern quantum control technology has enabled ultracold atoms to be used in a variety of disciplines, including atomic and molecular physics, condensed matter physics, and other fields. They are an important experimental system for modern quantum simulation and quantum computing. In the experimental research of ultracold atoms, it is necessary to control the on and off of the magnetic field current and the size change according to the timing. Therefore, the current source needs to have the ability of analog control.

[0003] However, existing analog controlled current sources with outputs of 100 amperes often use the circuit structure of a switching power supply, which has problems such as large output current ripple noise, large size, and inability to meet the requirements of current dynamic response in experiments. At the same time, existing low-noise large current sources usually use a single insulated gate bipolar transistor (IGBT) as a power adjustment tube, a current sensor and sampling resistor using fluxgate technology as current sensing feedback, and a PI structure as a loop stability adjustment compensator. However, the thermal stability and scalability of this design are difficult to guarantee. Summary of the invention

[0004] In view of this, the present invention provides a low-noise hundred-ampere-level current source, wherein the current source includes a loop compensation module, a voltage drive circuit, and a current detection feedback module connected in series in sequence, and the current source also includes an energy storage module connected to the voltage drive circuit and the current detection feedback module, wherein the energy storage module is used to provide electric energy to the load coil; the loop compensation module is used to perform compensation operations on the connected analog control signal and the voltage feedback signal, and output a compensation signal; the voltage drive circuit is used to obtain electric energy from the energy storage module through the load coil based on the compensation signal output by the loop compensation module, so as to provide an output current to the current detection feedback module; the current detection feedback module is used to sample the output current, and convert the output current into the voltage feedback signal and output it to the loop compensation module, so as to form a feedback loop to adjust the output current.

[0005] According to an embodiment of the present invention, the voltage driving circuit includes a driving module and a power output module, wherein the driving module is used to perform buffering and amplifying processing on the compensation signal to generate a driving signal; the power output module is used to obtain electrical energy from the energy storage module via the load coil based on the driving signal to provide the output current to the current detection feedback module.

[0006] According to an embodiment of the present invention, the current source further includes a charge and discharge control module, which is used to control the on and off states of each of the plurality of contactors in response to a charge and discharge control signal, so that the energy storage module switches between a charge mode and a discharge mode.

[0007] According to an embodiment of the present invention, the charge and discharge control module includes a first contactor and a second contactor, and the charge and discharge control signal includes a charge control signal and a discharge control signal, wherein the charge and discharge control module is configured to control the first contactor to be attracted and the second contactor to be disconnected in response to the discharge control signal, so that the positive electrode of the energy storage module forms a path with the load coil, the power output module, the current detection feedback module and the negative electrode of the energy storage module, and the energy storage module discharges to the load coil; the charge and discharge control module is configured to respond to the charge control signal, the second contactor is attracted, and the first contactor is disconnected, so that the positive electrode of the energy storage module forms a path with the positive electrode of the power supply, the negative electrode of the power supply and the negative electrode of the energy storage module, and the power supply charges the energy storage module.

[0008] According to an embodiment of the present invention, the current detection feedback module includes a sampling resistor and a plurality of low-noise voltage amplifying units connected in parallel, wherein the input end of the sampling resistor is connected to the output end of the power output module, the output end of the sampling resistor is respectively connected to the negative electrode of the energy storage module and the input end of the plurality of low-noise voltage amplifying units, and the output end of the low-noise voltage amplifying circuit is connected to the input end of the loop compensation module; wherein the sampling resistor is used to convert the output current flowing through the load coil into the voltage feedback signal, and the plurality of low-noise voltage amplifying units are respectively used to amplify the voltage feedback signal and output the amplified voltage feedback signal to the loop compensation module to reduce the equivalent output voltage noise of the current detection feedback module.

[0009] According to an embodiment of the present invention, the equivalent output voltage noise is calculated as follows:

[0010] ;

[0011] in, represents the equivalent output noise of each of the above low-noise voltage amplification units, represents the equivalent output voltage noise of the above-mentioned current detection feedback module, and n represents the number of the above-mentioned low-noise voltage amplification units.

[0012] According to an embodiment of the present invention, the above-mentioned loop compensation module includes an operational amplifier unit and multiple resistor-capacitor units, and the above-mentioned multiple resistor-capacitor units are respectively connected to the reverse input terminal of the above-mentioned operational amplifier unit, the output terminal of the above-mentioned operational amplifier unit and the output terminal of the above-mentioned current detection feedback module, and the non-inverting input terminal of the above-mentioned operational amplifier unit is connected to the above-mentioned analog control signal; wherein the above-mentioned multiple resistor-capacitor units are used to change the distribution of zeros and poles of the above-mentioned loop compensation module.

[0013] According to an embodiment of the present invention, the operational amplifier unit and the plurality of resistor-capacitor units constitute a circuit for performing compensation operation on the analog control signal and the voltage feedback signal. Type compensator, wherein the above The compensation operation methods of the type compensator include:

[0014] ;

[0015] ;

[0016] in, represents the above compensation signal, represents the above analog control signal, Represents the above voltage feedback signal, Indicates the above The operational structure of the type compensator, where , Indicates the above The zero point of the compensator, , , Indicates the above The poles of the type compensator, the values ​​of the zero point and the values ​​of the poles are determined by the values ​​of the multiple resistor-capacitor units.

[0017] According to an embodiment of the present invention, the power output module includes a plurality of power output units connected in parallel, each of the power output units includes a gate resistor, a field effect transistor and a power resistor, wherein the first end of the gate resistor is connected to the drive signal, the second end of the gate resistor is connected to the gate of the field effect transistor, the drain of the field effect transistor is connected to the output end of the load coil, the source of the field effect transistor is connected to the first end of the power resistor, and the second end of the power resistor is connected to the input end of the current detection feedback module; wherein, when the field effect transistor is turned on, current is allowed to flow from the drain to the source, thereby driving the load coil to work.

[0018] According to an embodiment of the present invention, the energy storage module comprises a plurality of lead-acid batteries connected in parallel, and each of the lead-acid batteries is configured to be isolated from the mains.

[0019] According to the low-noise 100-ampere current source provided by the embodiment of the present invention, through the synergistic effect of the loop compensation module and the current detection feedback module, the output current is sampled by the current detection feedback module to be converted into a voltage feedback signal, and fed back to the loop compensation module, thereby forming a closed-loop system to detect and adjust the output current in real time, effectively reducing the system error and improving the stability and accuracy of the current source output current; the current detection feedback module adopts a low-noise sampling resistor and a low-noise amplifier circuit, which can reduce noise interference in the current detection process, reduce the ripple noise of the output current, and improve the output quality of the current source. In addition, the present application can use a metal oxide semiconductor field effect transistor (MOSFET) as a power output module, which has better thermal management performance and higher power density than IGBT as a power adjustment tube, thereby improving the thermal stability and scalability of the current source. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0021] Figure 1 A schematic structural diagram of a low-noise 100-ampere current source according to an embodiment of the present invention is shown.

[0022] Figure 2 A circuit structure diagram of a loop compensation module according to a specific embodiment of the present invention is shown.

[0023] Figure 3 A circuit structure diagram of a current detection feedback module according to a specific embodiment of the present invention is shown.

[0024] Figure 4 A schematic diagram of the circuit structure of a power output module according to a specific embodiment of the present invention is shown.

[0025] Figure 5 A schematic diagram of the circuit structure of a driving module according to a specific embodiment of the present invention is shown.

[0026] Figure 6 A circuit structure diagram of a charge and discharge control module according to a specific embodiment of the present invention is shown.

[0027] Figure 7 The diagram shows the response of the measured output current of the low-noise 100-ampere current source to the input signal according to a specific embodiment of the present invention.

[0028] Figure 8 A noise analysis schematic diagram of a low-noise 100-ampere current source according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0031] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0032] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0033] The development of modern quantum control technology has enabled ultracold atoms to be deeply applied in many disciplines such as atomic and molecular physics and condensed matter physics. They are an important experimental system for modern quantum simulation and quantum computing. Among them, in the experimental research of ultracold atoms, precise control of the external magnetic field is crucial. Laboratories usually use Helmholtz coils to pass current to generate a uniform magnetic field to meet the requirements of magnetic field uniformity in some experiments; at the same time, anti-Helmholtz configuration coils are also used to generate gradient magnetic fields to meet the requirements of other experiments for magnetic field gradients. Since the on-off and size changes of the magnetic field current need to be controlled according to the timing in the experiment, the current source needs to have the ability of analog control.

[0034] For example, experiments such as the preparation of two-dimensional quantum gas and the use of Fechbach resonance to regulate atomic interactions have extremely high requirements for the performance of the current source. In the two-dimensional quantum gas preparation experiment, which is one of the core technologies of the ultracold atom high-resolution optical lattice platform, a current of 100A is required to generate a strong gradient field of 100G / cm, and the fluctuation of the gradient magnetic field is required to be less than 1mA to ensure the accuracy of the experiment. In the experiment of using Fechbach resonance to regulate the interaction of 87Rb atoms, a current of more than 200A is required to generate a uniform magnetic field of 1066.92G, and the magnetic field noise is required to be less than 13mG to accurately control the interaction strength between atoms.

[0035] However, the existing analog controlled current sources with 100-ampere output often use the circuit structure of switching power supply, which has problems such as large output current ripple noise, large volume, and failure to meet the requirements of current dynamic response in experiments. For example, although the N8945A power supply can output 340A current, its current programming accuracy, output current ripple noise, and command response time cannot meet the high requirements of the above experiments. Although the DH17832A power supply can output 510A current, its current ripple noise and dynamic response time cannot meet the experimental requirements.

[0036] At the same time, existing low-noise large current sources usually use a single IGBT as a power adjustment tube, a current sensor and sampling resistor of fluxgate technology as current detection feedback, and a PI structure as a loop stability adjustment compensator. However, this design has the problem that thermal stability and scalability cannot be guaranteed. Since the IGBT is in the linear region when the current source is working, a single IGBT will bear thousands of watts of thermal power dissipation, which is easy to cause thermal damage, so its maximum output current is limited. At the same time, the internal structure of the IGBT is complex and the parasitic capacitance parameters are large, which limits the loop bandwidth and makes the current source unable to achieve the response time required for the experiment.

[0037] In addition, as the most critical current sensing feedback method in low-noise design, it uses a current sensor and a sampling resistor. The current sensor has a fixed output current noise floor, which makes it impossible to further reduce the final current noise. In a complex magnetic field environment, the external magnetic field is also prone to cause uncontrollable interference to the current sensor. The high inductance load often encountered in the experiment together with the parasitic capacitance of the power device may also cause resonance, resulting in a rapid decrease in the phase margin of the closed-loop control system. If only the PI compensator is used to adjust the loop, its single-pole single-zero structure cannot compensate for the loop phase, and the current response is prone to overshoot and difficult or even impossible to adjust, thereby affecting the stability and response speed of the current source.

[0038] Based on the above problems, an embodiment of the present invention provides a low-noise 100-ampere current source. Through the synergistic effect of the loop compensation module and the current detection feedback module, the output current is sampled through the current detection feedback module to be converted into a voltage feedback signal, and fed back to the loop compensation module, thereby forming a closed-loop system to detect and adjust the output current in real time, effectively reducing the system error and improving the stability and accuracy of the current source output current; the current detection feedback module adopts a low-noise sampling resistor and a low-noise amplifier circuit, which can reduce noise interference in the current detection process, reduce the ripple noise of the output current, and improve the output quality of the current source. In addition, the present application can use MOSFET as a power output module, which has better thermal management performance and higher power density than IGBT as a power adjustment tube, thereby improving the thermal stability and scalability of the current source.

[0039] Specifically, an embodiment of the present invention provides a low-noise hundred-ampere level current source, wherein the current source includes a loop compensation module, a voltage drive circuit, and a current detection feedback module connected in series in sequence, and the current source also includes an energy storage module connected to the voltage drive circuit and the current detection feedback module, wherein the energy storage module is used to provide electrical energy to the load coil; the loop compensation module is used to perform compensation operations on the connected analog control signal and the voltage feedback signal, and output a compensation signal; the voltage drive circuit is used to obtain electrical energy from the energy storage module via the load coil based on the compensation signal output by the loop compensation module, so as to provide an output current to the current detection feedback module; the current detection feedback module is used to sample the output current, and convert the output current into a voltage feedback signal and output it to the loop compensation module, so as to form a feedback loop to regulate the output current.

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0041] Figure 1 A schematic structural diagram of a low-noise 100-ampere current source according to an embodiment of the present invention is shown.

[0042] like Figure 1 As shown, the current source may include a loop compensation module 110 , a voltage driving circuit 120 , a current detection feedback module 130 , and an energy storage module 140 .

[0043] like Figure 1 As shown, the loop compensation module 110, the voltage driving circuit 120, and the current detection feedback module 130 are connected in series in sequence to form a closed loop.

[0044] Specifically, the input end of the loop compensation module 110 is respectively connected to the analog control signal and the voltage feedback signal output from the current detection feedback module 130, the output end of the loop compensation module 110 is connected to the input end of the voltage driving circuit 120, the output end of the voltage driving circuit 120 is connected to the input end of the current detection feedback module 130, and the output end of the current detection feedback module 130 is connected to the input end of the loop compensation module 110.

[0045] like Figure 1 As shown, the input end of the voltage driving circuit 120 is also configured to be connected to the output end of the load coil 150 , the input end of the load coil 150 is connected to the positive pole of the energy storage module 140 , and the output end of the current detection feedback module 130 is connected to the negative pole of the energy storage module 140 .

[0046] According to an embodiment of the present invention, the loop compensation module 110 is configured to perform compensation operations on the connected analog control signal and the voltage feedback signal to provide loop gain and phase compensation, eliminate system errors, thereby improving the stability and accuracy of the output current, and output a compensation signal after the compensation operation. The analog control signal can be used to characterize the desired output current value.

[0047] According to an embodiment of the present invention, the voltage driving circuit 120 is configured to obtain electric energy from the energy storage module 140 via the load coil 150 based on the compensation signal output by the loop compensation module 110, so as to provide an output current to the current detection feedback module 130. The voltage driving circuit 120 includes a driving module 121 and a power output module 122. The driving module 121 is used to perform buffering and amplification processing on the compensation signal to generate a driving signal, thereby driving the power output module 122 to output a constant output current. The power output module 122 can use a power MOS field effect transistor (MOSFET).

[0048] According to an embodiment of the present invention, the current detection feedback module 130 is used to sample the output current and convert the output current into a voltage feedback signal and output it to the loop compensation module 110, so as to adjust the output current based on the compensation signal of the loop compensation module 110, wherein the current detection feedback module 130 can be constructed using a low-noise sampling resistor and a low-noise amplifier circuit.

[0049] According to an embodiment of the present invention, the energy storage module 140 may be a large-capacity lead-acid battery.

[0050] Based on this, the embodiment of the present invention samples the output current through the current detection feedback module through the synergistic effect of the loop compensation module and the current detection feedback module, so as to convert it into a voltage feedback signal and feed it back to the loop compensation module, thereby forming a closed-loop system to detect and adjust the output current in real time, effectively reducing the system error and improving the stability and accuracy of the current source output current; the current detection feedback module adopts a low-noise sampling resistor and a low-noise amplifier circuit, which can reduce the noise interference in the current detection process, reduce the ripple noise of the output current, and improve the output quality of the current source. In addition, the present application can use MOSFET as a power output module, which has better thermal management performance and higher power density than IGBT as a power adjustment tube, thereby improving the thermal stability and scalability of the current source.

[0051] like Figure 1 As shown, the current source also includes a power supply 160 and a charge and discharge control module 170, wherein the charge and discharge control module 170 includes a discharge control unit 171 and a charge control unit 172, the positive electrode of the energy storage module 140 is connected to the input end of the load coil 150 via the discharge control unit 171, the output end of the load coil 150 is connected to the input end of the power output module 122, the output end of the power output module 122 is connected to the input end of the current detection feedback module 130, and the output end of the current detection feedback module 130 is connected to the negative electrode of the energy storage module 140 via the discharge control unit 171.

[0052] like Figure 1 As shown, the positive electrode and the negative electrode of the energy storage module 140 are respectively connected to the positive electrode and the negative electrode of the power source 160 via the charging control unit 172 .

[0053] According to an embodiment of the present invention, the charge and discharge control module 170 is configured to control the on and off states of each of the plurality of contactors in response to the charge and discharge control signal, so that the energy storage module switches between the charge mode and the discharge mode. The charge and discharge control signals can all be 5V-TTL logic level signals. The charge and discharge control module 170 is another independently powered control circuit.

[0054] Specifically, the discharge control unit 171 includes a first contactor, and the charge control unit 172 includes a second contactor. The charge and discharge control module 170 is configured to control the first contactor to be attracted and the second contactor to be disconnected in response to the discharge control signal, so that the positive electrode of the energy storage module 140 forms a path with the load coil 150, the power output module 122, the current detection feedback module 130 and the negative electrode of the energy storage module 140. In this case, the energy storage module 140 discharges to the load coil 150.

[0055] Specifically, the charge and discharge control module 170 is also configured to control the first contactor to disconnect and the second contactor to close in response to the charging control signal, so that the positive electrode of the energy storage module 140 forms a path with the positive electrode of the power supply 160, the negative electrode of the power supply 160 and the negative electrode of the energy storage module 140. In this case, the power supply 160 charges the energy storage module 140.

[0056] According to an embodiment of the present invention, the loop compensation module 110 includes an operational amplifier unit and multiple resistor-capacitor units, the multiple resistor-capacitor units are respectively connected to the reverse input terminal of the operational amplifier unit, the output terminal of the operational amplifier unit and the output terminal of the current detection feedback module 120, and the non-inverting input terminal of the operational amplifier unit is connected to the analog control signal.

[0057] The operational amplifier unit can use a precision operational amplifier with low temperature drift and low noise. The resistor-capacitor unit can use a resistor-capacitor network composed of resistors and capacitors. The resistor can use an adjustable potentiometer, and the configuration of the zero and pole of the compensation module can be achieved by adjusting the resistance value of the potentiometer connected to the circuit and replacing capacitors of different sizes.

[0058] According to a specific embodiment of the present invention, the precision operational amplifier may be an OPA227U model, or other low temperature drift and low noise models, such as ADA4522 or AD797BR.

[0059] Figure 2 A circuit structure diagram of a loop compensation module according to a specific embodiment of the present invention is shown.

[0060] like Figure 2 As shown, the loop compensation module includes an operational amplifier and three groups of resistor-capacitor networks, the three groups of resistor-capacitor networks include resistors R1, R2, R3, and capacitors C1, C2, and C3, wherein the in-phase input terminal of the operational amplifier is connected to the analog control signal V in , the series structure of resistor R1 and capacitor C2 is connected in series with the reverse input terminal of the operational amplifier, capacitor C3 is connected in parallel with the series structure of resistor R1 and capacitor C2, and the input terminal of resistor R1 and capacitor C3 are respectively connected to the output terminal of the operational amplifier. Capacitor C1 and resistor R3 are connected in series with the reverse input terminal of the operational amplifier, resistor R2 is connected in parallel with the series structure of capacitor C1 and resistor R3, and the input terminals of capacitor C1 and resistor R2 are respectively connected to the voltage feedback signal V FB The output of the operational amplifier outputs the compensation signal V Cout .

[0061] Figure 2 The operational amplifier and three sets of resistor-capacitor networks shown in the figure form a three-pole and two-zero Type compensator, the The compensation operation methods of the type compensator include:

[0062] (1);

[0063] (2);

[0064] In the formula, represents the compensation signal, represents the analog control signal, Represents the voltage feedback signal, express The operational structure of the type compensator is, for example, the system function in the loop, where , express The zero point of the type compensator, where , , express The poles, zeros and poles of the type compensator are determined by the values ​​of multiple resistors and capacitors.

[0065] According to a specific embodiment of the present invention, without adding a loop compensation module, a loop analyzer can be used to measure the open-loop transfer function of the system between the input end of the driving module and the output end of the current detection feedback module. According to the required current simulation bandwidth, the expected system open-loop crossover frequency is determined. The crossover frequency is the frequency when the system gain is 1 (0dB), which determines the response speed of the system to the input signal. Generally, the selection of the crossover frequency requires a trade-off between system stability and response speed. Once the crossover frequency is determined, the amplitude compensation value required at the crossover frequency can be calculated based on the open-loop transfer function of the system. The purpose of amplitude compensation is to ensure that the system has sufficient gain margin at the crossover frequency to avoid oscillation. In addition to amplitude compensation, phase compensation also needs to be considered. The required phase compensation value is determined using the transfer function phase value measured by the loop analyzer, combined with the expected loop system phase margin (usually selected between 45° and 60°). The purpose of phase compensation is to ensure that the system has sufficient phase margin near the crossover frequency to maintain stability. According to the calculated amplitude compensation value and phase compensation value, the loop compensation module is designed. According to the system function of the loop compensation module, the resistor and capacitor network parameter values ​​used to set the compensation parameters are determined.

[0066] Based on this, the embodiments of the present invention ensure the high accuracy and stability of the compensation signal by using a precision operational amplifier with low temperature drift and low noise; The two-zero-three-pole structure of the type compensator adjusts the zero-pole distribution and provides positive phase compensation for the system at the open-loop crossover frequency through precise compensation calculation, thereby improving the system's phase margin. In addition, by adjusting the parameters of the resistor-capacitor network, the system's open-loop crossover frequency and bandwidth can be adjusted to optimize the system's dynamic response, so as to achieve stable current output under different loads, adjustable bandwidth, and current output response without overshoot and ringing.

[0067] According to an embodiment of the present invention, the current detection feedback module includes a sampling resistor and a plurality of low-noise voltage amplifying units connected in parallel, wherein the input end of the sampling resistor is connected to the output end of the power output module, the output end of the sampling resistor is respectively connected to the negative electrode of the energy storage module and the input ends of the plurality of low-noise voltage amplifying units, and the output end of the low-noise voltage amplifying circuit is connected to the input end of the loop compensation module.

[0068] According to a specific embodiment of the present invention, the resistance of the sampling resistor is usually selected to be very low to reduce its own power consumption and heat generation, while ensuring sufficient voltage drop to be accurately detected by subsequent circuits. Therefore, a current sampling resistor with low temperature drift, high precision and low resistance can be used to ensure high accuracy and stability of current-to-voltage conversion.

[0069] For example, you can use the low temperature drift and high precision CSM3637Z series four-wire alloy current sense resistor. You can also use five parallel 4 The resistors have an average heat dissipation power of 1.6W per resistor when the total current is 100A, ensuring their thermal stability.

[0070] In addition, different combinations of current-sense resistors and magnifications can be selected for different usage scenarios. You can use current-sense resistors with higher resistance and higher rated power, such as the UNR4-3425 series with a rated power of 50W to further reduce current noise. You can also use the FNPZ series with a rated power of 500W and a TCR coefficient of 1 A single FNPZR0010A resistor.

[0071] According to a specific embodiment of the present invention, each low-noise voltage amplification unit can use a precision operational amplifier group with low equivalent input noise. For example, an ultra-low noise and low temperature drift precision operational amplifier of the AD797BR model can be used to help achieve ultra-low noise current detection. The amplification gain resistor can use an ultra-low temperature drift VSMP series resistor to ensure the stability and accuracy of the gain. Among them, the gain resistor can use 10 and 1000 resistance combination to achieve 101 times voltage amplification.

[0072] According to another embodiment of the present invention, the current detection feedback module may further include a parallel structure of a low-noise transimpedance amplifier circuit composed of a high-precision current sensor and a sampling resistor.

[0073] According to an embodiment of the present invention, a sampling resistor is used to convert the output current flowing through the load coil into a voltage feedback signal, and a plurality of low-noise voltage amplification units are respectively used to amplify the voltage feedback signal and output the amplified voltage feedback signal to a loop compensation module to reduce the equivalent output voltage noise of the current detection feedback module.

[0074] Specifically, when the power output module receives the current flowing through the load coil, the current passes through the sampling resistor and generates a corresponding voltage drop, which is the voltage feedback signal. The voltage feedback signal is input into the low-noise voltage amplifier unit in parallel, and each amplifier unit amplifies it. Due to the use of a precision operational amplifier with low equivalent input noise, the amplified signal has an extremely low noise level. The amplified voltage feedback signal is output to the loop compensation module for subsequent current regulation and control.

[0075] According to a specific embodiment of the present invention, the sampling resistor may be a low temperature drift and high precision four-wire alloy current sensing resistor of the CSM3637Z series.

[0076] Figure 3 A circuit structure diagram of a current detection feedback module according to a specific embodiment of the present invention is shown.

[0077] like Figure 3 As shown, the current detection feedback module includes a low temperature drift four-wire alloy current sensing resistor R sense and the current sensing resistor R sense The parallel structure of four low-noise voltage amplifier units connected in series, where the current sensing resistor R sense The first end is connected to the output current of the Mosfet power output module, and the current sensing resistor R sense The second end is connected to the negative electrode of the energy storage module, and the current sensing resistor R sense The fourth terminal is grounded.

[0078] like Figure 3 As shown, each low-noise voltage amplification unit includes a low-noise precision operational amplifier, a resistor r, a gain resistor R gain1 , gain resistor R gain2 Among them, the non-inverting input terminal of the low-noise precision operational amplifier is connected to the current sensing resistor R sense The third end of the low noise precision operational amplifier is connected to the inverting input end of the gain resistor R gain1 The second end of the gain resistor R gain2 The second end of the gain resistor R gain1The first end of the low noise precision operational amplifier is connected to the ground, and the output end of the low noise precision operational amplifier is connected to the gain resistor R gain2 The first end of is connected to the first end of the resistor r, and the second end of the resistor r is connected to the output end of the current detection feedback module respectively.

[0079] The non-inverting input of the low-noise precision operational amplifier is used to receive the converted voltage signal, and the inverting input forms a negative feedback loop to stabilize the output of the amplifier. gain1 It forms a voltage divider circuit with the inverting input terminal of the low-noise precision operational amplifier to adjust the gain of the low-noise precision operational amplifier. gain2 It is used to further participate in the gain adjustment and signal output. The resistor r is used to output the amplified voltage signal to the loop compensation module.

[0080] According to an embodiment of the present invention, when multiple identical low-noise voltage amplification units are connected in parallel, since the noises they generate are independent, the total noise can be obtained by summing the root mean square (RMS) of the noise of each unit. However, since these noise signals are added at the output, but because they are independent random variables, the amplitude of the total noise will decrease in proportion to the square root of the number of units. The equivalent output voltage noise is calculated as follows:

[0081] (3);

[0082] In the formula, represents the equivalent output noise of each low-noise voltage amplifier unit, represents the equivalent output voltage noise of the current detection feedback module, and n represents the number of low-noise voltage amplification units.

[0083] According to the embodiment of the present invention, by increasing the number of low-noise voltage amplification units connected in parallel, the equivalent output voltage noise of the current detection feedback module can be significantly reduced.

[0084] Based on this, the embodiment of the present invention effectively reduces the error caused by temperature change and the equivalent output voltage noise through the synergistic effect of low-temperature drift current-sense resistors and multiple parallel ultra-low noise operational amplifier units, ensuring the high accuracy and stability of current-to-voltage conversion. In the laboratory, the RMS current noise is only 70 at 100A current output and within the effective test frequency range of 0.1Hz-200kHz. , effectively reducing the interference of external stray magnetic fields on the electric current, thereby meeting the needs of two-dimensional quantum gas preparation experiments and control experiments on the magnetic Feshbach resonance of Li and Rb atoms.

[0085] According to an embodiment of the present invention, the power output module includes a plurality of power output units connected in parallel, and each power output unit includes a gate resistor, a field effect transistor and a power resistor.

[0086] According to the embodiment of the present invention, the gate resistor can be used to limit the gate current and protect the gate from being damaged by an excessively large driving signal. At the same time, the gate resistor can also play a certain filtering role to reduce the fluctuation of the gate voltage.

[0087] According to an embodiment of the present invention, a field effect transistor (Mosfet) is used as a power switching device. When the Mosfet is turned on, current is allowed to flow from the drain to the source, thereby driving the load coil to work.

[0088] According to an embodiment of the present invention, the source of each Mosfet is connected in series with a low-resistance power resistor, which reduces the imbalance of static current distribution and prevents thermal imbalance of the device caused by uneven current distribution due to differences in factory parameters of the device; it can also be used as a static negative feedback resistor to stabilize the output current at the required operating point when the Mosfet power output module is tested separately in an open loop of the system. However, since the parasitic capacitance and load inductance of the power Mosfet device itself are prone to resonance, the phase at the resonant frequency is extremely reduced to -180°, making the system phase margin close to 0°, and the system is prone to oscillation. Therefore, the system gain and phase can be compensated by the loop compensation module.

[0089] Figure 4 A schematic diagram of the circuit structure of a power output module according to a specific embodiment of the present invention is shown.

[0090] like Figure 4 As shown, the power output module includes a plurality of power output units connected in parallel, each of which includes a gate resistor R G , field effect transistor Mosfet, each Mosfet source is connected in series with a low resistance power current sharing resistor R C .

[0091] Where, each gate resistor R G The first end of the gate resistor R G The second end is connected to the gate of the field effect transistor Mosfet, the drain of the field effect transistor Mosfet is connected to the output end of the load coil, and the source of the field effect transistor Mosfet is connected to the power current sharing resistor R C The first end of the power current sharing resistor R C The second end is connected to the input end of the current detection feedback module.

[0092] In a specific embodiment of the present invention, since the Mosfet power output module needs to adjust a large current of 100 amperes when the circuit is running, the Mosfet therein works in a linear region, the total heat dissipation is close to kilowatts, and the experiment often needs to quickly shut down a large current, and the induced electromotive force of the load coil reaches hundreds of volts, so a high breakdown voltage, a small internal thermal resistance, and a Mosfet that can withstand high power are required. Therefore, a SOT-227 packaged IXFN150N65X2 field effect transistor can be used, which has a rated breakdown voltage of 650V and a continuous current bearing capacity of 145A, and 3 Mosfet of this model are connected in parallel to meet the demand of the laboratory 100A output current. At the same time, a power resistor TGHGCR0500FE can be used as a current sharing resistor with a rated power of 100W. The Mosfet power output module can be configured as a base-mounted type, and the connection mode between modules is a mechanical structure, with low manufacturing cost and easy batch production and installation. The parallel Mosfet and the power current sharing resistor can be installed on an aluminum water-cooled heat sink. There is a 15mm diameter water tank inside the heat sink for cooling circulating water to pass through, to ensure effective heat dissipation of the device during high power output.

[0093] Based on this, the embodiments of the present invention can adjust large currents of hundreds of amperes because the Mosfet works in the linear region, meeting the high power output requirements in laboratory and industrial applications; in addition, through the parallel structure of multiple Mosfets, the current load is dispersed, and the thermal stress of a single Mosfet is reduced, thereby improving the life and stability of the entire system; at the same time, by changing the number of parallel Mosfets and the resistance value of the current balancing resistor, the output current range of the current source can be easily expanded to achieve a current output of more than 300A.

[0094] Figure 5 A schematic diagram of the circuit structure of a driving module according to a specific embodiment of the present invention is shown.

[0095] like Figure 5 As shown in FIG. 1 , the MOSFET driving module can be implemented by a voltage follower composed of a precision operational amplifier ADA4522 with a rail-to-rail output. The non-inverting input of the precision operational amplifier is connected to the compensation signal V Cout The output end outputs the driving signal and feeds it back to the reverse input end at the same time, which not only realizes the isolation between the compensation signal output by the loop compensation module and the gate impedance of the Mosfet, but also provides sufficient gate driving current.

[0096] According to an embodiment of the present invention, the energy storage module includes a plurality of lead-acid batteries connected in parallel, and each lead-acid battery is configured to be isolated from the mains to serve as a floating voltage source, so that a ground loop will not be formed, thereby suppressing the current noise coupled by the ground loop between systems. In the experiment, the continuous discharge of the battery will gradually reduce the discharge voltage, so a large-capacity battery needs to be selected, and if the battery is in a high-discharge rate working state, its capacity will be significantly less than the rated capacity at the nominal discharge rate. Therefore, the design adopts a large-capacity lead-acid battery parallel structure, which helps to disperse the current load, thereby extending the discharge time and reducing the average discharge rate of each battery. For example, three 12V200AH valve-regulated lead-acid batteries DJM12200S can be used. When the total output current is 100A, the output current of each parallel battery is 33A, which is close to the calibrated 10h discharge rate. When in use, the battery capacity will not be greatly attenuated due to excessive discharge rate, and can support stable discharge for several hours at most, thereby ensuring the effective use of the battery capacity.

[0097] Based on this, the embodiment of the present invention adopts a floating large-capacity lead-acid battery to supply power, which is isolated from the laboratory mains, isolates the interference of external circuits and current source ground loop coupling, and does not cause interference to other experimental equipment or instruments.

[0098] According to an embodiment of the present invention, in cold atom experiments, especially in two-dimensional quantum gas preparation experiments, the demand for current is intermittent, which means that the battery does not need to be continuously discharged in most experimental cycles. Therefore, a charge and discharge control module can be used to optimize the use efficiency and life of the battery.

[0099] Figure 6 A circuit structure diagram of a charge and discharge control module according to a specific embodiment of the present invention is shown.

[0100] like Figure 6As shown, the charge and discharge control module includes a charge control unit and a discharge control unit, wherein the charge control unit and the discharge control unit both include a switch, a voltage follower, an isolation gate driver, a Mosfet switch tube and a contactor, wherein when the switch is connected to the charge control signal or the discharge control signal, the input 5V-TTL logic level signal first passes through the voltage follower to enhance the stability and anti-interference ability of the signal. After passing through the voltage follower, the logic level signal is input to the isolation gate driver, and the isolation gate driver converts the logic level signal into a power signal required to drive the Mosfet switch tube. The Mosfet switch tube is connected in series with the contactor coil, and its conduction state is controlled by the isolation gate driver. When the Mosfet switch tube is turned on, the contactor coil is energized, causing the contactor to be attracted, thereby closing the discharge circuit or charging circuit of the battery. When the Mosfet switch tube is turned off, the contactor coil is powered off, the contactor is disconnected, and the circuit is cut off.

[0101] According to a specific embodiment of the present invention, during the experimental cycle, when current output is required, the discharge circuit is closed by the charge and discharge control module, and the battery starts to discharge. During the rest of the experimental cycle, the charge circuit is closed by the charge and discharge control module, and the battery starts to charge to prepare for the next discharge.

[0102] According to a specific embodiment of the present invention, the contactor may be a DCNEV250-M model with a rated current of 250A, and the isolation gate driver may be a UCC23113 model.

[0103] Figure 7 The diagram shows the response of the measured output current of the low-noise 100-ampere current source to the input signal according to a specific embodiment of the present invention.

[0104] like Figure 7 As shown in the figure, when the low-noise 100-ampere current source receives a step-down input signal, for example, when the input signal steps from 8V to 0V, the output current of the current source starts to change from 100A, and the response time to reach the output current stability is about 0.5ms. Its falling speed and stability can reflect the good dynamic performance and noise suppression ability of the low-noise 100-ampere current source.

[0105] Figure 8 A noise analysis schematic diagram of a low-noise 100-ampere current source according to a specific embodiment of the present invention is shown.

[0106] like Figure 8 As shown, Figure 8 From top to bottom, they include the time domain noise waveform, noise power spectrum, and total current noise.

[0107] The time domain noise waveform is a current noise waveform in the time domain obtained by directly sampling the output current. The current noise waveform can intuitively show the fluctuation of the noise.

[0108] The noise power spectrum is obtained by sampling the output current for a long time (such as 10 seconds) through an oscilloscope with a high sampling rate (such as 10 megabits per second) to obtain a large number of sample points, and then performing Fourier transform on these sample points to convert the time domain signal into a frequency domain signal. The noise power spectrum can reveal the distribution of noise at different frequencies.

[0109] The total amount of current noise is obtained by integrating the noise power spectrum in the frequency domain.

[0110] like Figure 8 As shown, a low temperature drift and high precision current sensing resistor is used for sampling, a precision operational amplifier with extremely low equivalent input noise and low input offset voltage temperature drift is used as a sampling voltage amplifier, and a low temperature drift and low noise precision operational amplifier is used as an operational amplifier of the loop compensator, so that the long-term drift of the output current of the ultra-low noise current source is extremely low.

[0111] So far, the embodiments of the present invention have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0112] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in understanding the present invention.

[0113] The shapes and sizes of the components in the figures do not reflect the real size and proportion, but only illustrate the contents of the embodiments of the present invention. In addition, in the embodiments, any reference symbols between brackets should not be construed as limiting the embodiments.

[0114] Unless otherwise indicated, the numerical parameters in this specification and the accompanying examples are approximate values ​​and can be changed according to the desired properties obtained by the content of the present invention. Specifically, all numbers used in the specification and examples to represent the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in the examples. The word "one" or "an" before an element does not exclude the presence of multiple such elements.

[0115] The ordinal numbers used in the specification and the embodiments, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0116] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

[0117] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A low-noise 100-ampere current source, characterized in that: The current source comprises a loop compensation module, a voltage driving circuit, and a current detection feedback module connected in series in sequence, and the current source further comprises an energy storage module connected to the voltage driving circuit and the current detection feedback module, wherein: The energy storage module is used to provide electrical energy to the load coil; The loop compensation module is used to perform compensation operation on the connected analog control signal and voltage feedback signal, and output a compensation signal; The voltage driving circuit is used to obtain electric energy from the energy storage module via the load coil based on the compensation signal output by the loop compensation module, so as to provide an output current to the current detection feedback module; The current detection feedback module is used to sample the output current and convert the output current into the voltage feedback signal and output it to the loop compensation module to form a feedback loop to adjust the output current.

2. The current source according to claim 1, characterized in that The voltage driving circuit comprises a driving module and a power output module, wherein the driving module is used to perform buffering and amplification processing on the compensation signal to generate a driving signal; The power output module is used to obtain electric energy from the energy storage module via the load coil based on the driving signal, so as to provide the output current to the current detection feedback module.

3. The current source according to claim 2, characterized in that The current source further includes a charge and discharge control module, which is used to control the on and off states of each of the plurality of contactors in response to a charge and discharge control signal, so that the energy storage module switches between a charge mode and a discharge mode.

4. The current source according to claim 3, characterized in that The charge and discharge control module includes a first contactor and a second contactor, and the charge and discharge control signal includes a charge control signal and a discharge control signal. The charge and discharge control module is configured to control the first contactor to be attracted and the second contactor to be disconnected in response to the discharge control signal, so that the positive electrode of the energy storage module forms a path with the load coil, the power output module, the current detection feedback module and the negative electrode of the energy storage module, and the energy storage module discharges to the load coil; The charge and discharge control module is configured to respond to the charging control signal, the second contactor is attracted, and the first contactor is disconnected, so that the positive electrode of the energy storage module forms a path with the positive electrode of the power supply, the negative electrode of the power supply and the negative electrode of the energy storage module, and the power supply charges the energy storage module.

5. The current source according to claim 1, characterized in that The current detection feedback module includes a sampling resistor and a plurality of low-noise voltage amplifying units connected in parallel, wherein the input end of the sampling resistor is connected to the output end of the power output module, the output end of the sampling resistor is respectively connected to the negative electrode of the energy storage module and the input ends of the plurality of low-noise voltage amplifying units, and the output end of the low-noise voltage amplifying circuit is connected to the input end of the loop compensation module; Among them, the sampling resistor is used to convert the output current flowing through the load coil into the voltage feedback signal, and the multiple low-noise voltage amplification units are used to amplify the voltage feedback signal respectively, and output the amplified voltage feedback signal to the loop compensation module to reduce the equivalent output voltage noise of the current detection feedback module.

6. The current source according to claim 5, characterized in that The equivalent output voltage noise is calculated as follows: ； in, represents the equivalent output noise of each of the low-noise voltage amplification units, represents the equivalent output voltage noise of the current detection feedback module, and n represents the number of the low-noise voltage amplification units.

7. The current source according to claim 1, characterized in that The loop compensation module includes an operational amplifier unit and two resistor-capacitor units, one end of each of the two resistor-capacitor units is connected to the inverting input end of the operational amplifier unit, the other ends of the two resistor-capacitor units are respectively connected to the output end of the operational amplifier unit and the output end of the current detection feedback module, and the in-phase input end of the operational amplifier unit is connected to the analog control signal; The two resistor-capacitor units are used to change the distribution of the zero and pole points of the loop compensation module.

8. The current source according to claim 7, characterized in that The operational amplifier unit and the two resistor-capacitor units are used to perform compensation operation on the analog control signal and the voltage feedback signal. type compensator, wherein the The compensation operation methods of the type compensator include: ； ； in, represents the compensation signal, represents the analog control signal, represents the voltage feedback signal, Indicates the The operational structure of the type compensator, where , Indicates the The zero point of the compensator, , , Indicates the The pole of the type compensator, the value of the zero point and the value of the pole are determined by the values ​​of the two resistance and capacitance units.

9. The current source according to claim 2, characterized in that: The power output module includes a plurality of power output units connected in parallel, each of which includes a gate resistor, a field effect transistor and a power resistor. Wherein, the first end of the gate resistor is connected to the driving signal, the second end of the gate resistor is connected to the gate of the field effect transistor, the drain of the field effect transistor is connected to the output end of the load coil, the source of the field effect transistor is connected to the first end of the power resistor, and the second end of the power resistor is connected to the input end of the current detection feedback module; Wherein, when the field effect transistor is turned on, current is allowed to flow from the drain to the source of the field effect transistor, thereby driving the load coil to work.

10. The current source according to claim 1, characterized in that The energy storage module includes a plurality of lead-acid batteries connected in parallel, and each of the lead-acid batteries is configured to be isolated from the mains.

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