CN109445501B - High-precision high-voltage current source circuit - Google Patents
High-precision high-voltage current source circuit Download PDFInfo
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- CN109445501B CN109445501B CN201811571566.4A CN201811571566A CN109445501B CN 109445501 B CN109445501 B CN 109445501B CN 201811571566 A CN201811571566 A CN 201811571566A CN 109445501 B CN109445501 B CN 109445501B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/461—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using an operational amplifier as final control device
Abstract
The invention discloses a high-precision high-voltage current source circuit which comprises a logic control unit, a high-voltage Boost circuit, a negative voltage generating circuit, a DAC circuit, a high-voltage floating ground operational amplifier circuit, a constant current source circuit, an H-bridge chopper circuit and an overcurrent and overload protection circuit. The invention solves the problems that the traditional Howland current source has poor stability, the circuit is easy to be in a saturation state, the output current is low, the efficiency is low, the bias influence of the Ibias of the operational amplifier is large, four peripheral matching resistors are difficult to be consistent, and the like. The circuit can realize fine current stepping adjustment, has a large current output range and strong loading capacity, and has flexible and variable circuit parameters and lower requirement on the consistency of peripheral parameters.
Description
Technical Field
The invention belongs to the field of electronic circuits, and relates to a high-precision high-voltage current source circuit.
Background
Current source, a huge area. The most basic current source circuit is a simple current source or a current mirror current source formed by triodes, see fig. 1; after the integrated operational amplifier circuit is popularized and applied, a constant current source circuit formed by an operational amplifier unit and a resistor, namely a Howland current source appears, and referring to fig. 2, the circuit model provides guidance for a subsequent constant current source circuit based on an operational amplifier topological structure.
In the Howland current source, Rh3 and Rh4 form a negative feedback network, the output of the negative feedback network is fed back to an inverting input end, the feedback coefficient is Rh4/(Rh3+ Rh4), Rh1, Rh2 and Rh L in the non-inverting input end form a positive feedback loop, and the feedback coefficient is (Rh1// Rh L)/(Rh 2+ (Rh1// Rh L)).
Rh1, Rh2, Rh3 and Rh4 were set equal and calculated to obtain
Uout＝(2Ui*RhL)/Rh1；
Iout＝Uin/Rh1；
The Howland current source has the main problems that the stability is poor, if the operational amplifier enters a saturation state after the Rh L end is removed, the originally designed circuit function cannot be realized, the output current is low, the efficiency is low, the bias influence of the Ibias of the operational amplifier is large, and the four peripheral matching resistors are difficult to be completely consistent.
The current mirror current source maintains the stability of the Ib current of the right Qm2 by relying on the Ib current of the left Qm1, when the base current Ib of a triode is constant, Rm3 is load impedance, when the load resistance changes, such as increases, Rm3 Im2 becomes large, the collector potential Uc of a Qm2 tube is increased, and the Uce of a Qm2 triode is VCC-Uc, so that the Uce inter-electrode potential is reduced, the working point of the circuit is changed, the Ic current is changed, and the output stability of the constant current source circuit is influenced. Meanwhile, the temperature stability of the current mirror constant current source is poor, and the single-tube temperature rise of the Qm1 and Qm2 triodes easily causes the distortion of the output characteristic.
Disclosure of Invention
The constant current source adopts high-voltage floating ground to supply power to the operational amplifier unit, and the current of the output end is closer to a set value through a negative feedback loop, so that the accuracy of the current source output is improved; meanwhile, a feedback end of the operational amplifier is connected with a capacitor at a pF level, so that the stability is improved, and the phase is balanced; the high-voltage ground constant current source has strong signal loading capacity, high output stability and flexible and changeable whole circuit structure, can easily change the floating ground potential to the target potential level, and does not worry about the replacement problem of the operational amplifier after the voltage level is changed.
In order to achieve the purpose, the technical scheme of the invention is as follows: a high-precision high-voltage current source circuit comprises a logic control unit, a high-voltage Boost circuit, a negative voltage generating circuit, a DAC circuit, a high-voltage floating ground operational amplifier circuit, a constant current source circuit, an H-bridge chopper circuit and an overcurrent and overload protection circuit,
the logic control unit controls the DAC circuit to generate specific analog voltage, controls the high-voltage Boost circuit to be started or closed, controls the constant-current source circuit to be started or closed, and indirectly controls the H-bridge chopper circuit timing sequence and the overcurrent and overload protection circuit to recognize;
the DAC circuit converts the voltage output instruction of the logic control unit into a specific analog voltage signal and provides the specific analog voltage signal to the constant current source circuit as a voltage input signal;
the high-voltage BOOST circuit BOOSTs the 15V input voltage to 100V or more and is used for supplying the high-voltage floating ground operational amplifier circuit;
the negative pressure generating circuit reduces the high voltage of 100V to 95V and is used for supplying the operational amplifier unit;
the high-voltage floating ground operational amplifier circuit uses 100V and 95V high-voltage power supply to enable the operational amplifier to work in a floating ground power supply state;
the constant current source circuit adopts the operational amplifier and the two-stage triode to form a current source, improves the stability of an operational amplifier loop through strong negative feedback, balances the phase and has high output current regulation precision;
the H-bridge chopper circuit chops the output of the constant current source circuit into specific waveforms such as unidirectional pulse current or positive and negative bidirectional pulse current;
the overcurrent and overload protection circuit samples and monitors the constant current source circuit signal in real time and feeds the constant current source circuit signal back to the logic control unit.
Preferably, the logic control unit adopts an MCU or CP L D or FPGA logic control device.
Preferably, the DAC circuit generates a specific analog voltage, the accuracy range of the analog voltage depends on the resolution of the DAC element used, and the error of the analog quantity of the DAC circuit is optimized by the logic control unit by using a table look-up method or a linear function calibration method, and the analog voltage is supplied to the constant current source circuit to be used as the voltage input signal.
Preferably, the high-voltage BOOST circuit BOOSTs the input 15V to 100V or more, and includes a fast turn-off module and an overload protection module.
Preferably, the negative voltage generating circuit reduces the voltage of 100V high voltage or above to the required potential, including T L V431.
Preferably, the high-voltage floating ground operational amplifier circuit uses a potential of 100V or more as the positive end of the operational amplifier for power supply, uses a potential of 95V or more as the negative end of the operational amplifier for power supply, and has a positive-negative end potential difference meeting the power supply requirement of the operational amplifier.
Preferably, the constant current source circuit adopts a rail-to-rail operational amplifier and a two-stage triode to form a current source.
Preferably, the H-bridge chopper circuit is controlled by the logic control unit to generate a forward pulse or positive and negative bidirectional pulse current signal or other current signals with specific time sequence.
Preferably, the overcurrent and overload protection circuit samples low-end current, samples and monitors the output of the constant current source circuit in real time, and feeds the output back to the logic control unit, and when an overcurrent and overload phenomenon occurs, the logic control unit turns off the high-voltage BOOST circuit.
Compared with the prior art, the invention has the beneficial effects that:
(1) the current source is grounded instead of floating, so that the safety is higher;
(2) the control reference voltage is relative to the ground, so that the control is convenient;
(3) in the whole current source, only individual separating devices bear 100V or higher voltage, all operational amplifiers and other control devices are conventional low-voltage devices, and the circuit structure is convenient to realize. Meanwhile, only a higher voltage-resistant separation device needs to be selected, so that the output voltage level can be improved, and the voltage-resistant limitation of devices such as an operational amplifier and the like is avoided. When selecting the transistor, the requirement of the maximum output current range needs to be considered, and a certain margin is left.
(4) In order to ensure the stability of the operational amplifier and avoid entering a saturation state, a capacitor at a pF level is added at the follower end of the operational amplifier, and the compensation capacitor has the function of keeping the stability of the operational amplifier, so that a strong negative feedback path for a high-frequency signal is formed, and the phenomenon of instability of a circuit is avoided;
(5) the resistor is used for limiting current, and larger current is prevented from flowing through the triode or the power tube at the moment of electrifying.
(6) The constant current output signal can be used for controlling an H-bridge chopper circuit by a logic control unit to realize specific pulse current or constant signal output.
(7) The low-end current real-time sampling ensures the output reliability of the circuit and protects the load safety.
Drawings
FIG. 1 is a schematic diagram of a prior art basic current source circuit;
FIG. 2 is a schematic diagram of a prior art Howland current source circuit;
FIG. 3 is a block diagram of a high-precision high-voltage current source circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a high voltage BOOST circuit in the high precision high voltage current source circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a negative voltage generating circuit in the high-precision high-voltage current source circuit according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a high-voltage floating ground operational amplifier and constant current source circuit in a high-precision high-voltage current source circuit according to an embodiment of the present invention;
fig. 7 is a schematic diagram of an H-bridge chopper circuit in a high-precision high-voltage current source circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
Referring to fig. 3, a block diagram of a high-precision high-voltage current source circuit according to an embodiment of the present invention includes a logic control unit 10, a high-voltage BOOST circuit 11, a negative voltage generating circuit 12, a DAC circuit 14, a high-voltage floating-ground operational amplifier circuit 13, a constant current source circuit 15, an H-bridge chopper circuit 16, and an overcurrent and overload protection circuit 17, where,
the logic control unit 10 controls the DAC circuit 14 to generate a specific analog voltage, controls the high-voltage BOOST circuit 11 to be turned on or turned off, controls the constant current source circuit 15 to be turned on or turned off, and indirectly controls the timing sequence of the H-bridge chopper circuit 16 and the overcurrent and overload protection circuit 17 to recognize;
the DAC circuit 14 converts the voltage output instruction of the logic control unit 10 into a specific analog voltage signal, and provides the specific analog voltage signal to the constant current source circuit 15 as a voltage input signal;
a high-voltage BOOST circuit 11 for boosting a 15V input voltage to 100V or more and supplying the boosted voltage to a high-voltage floating ground operational amplifier circuit 13;
a negative voltage generating circuit 12 for reducing the 100V high voltage to 95V for supplying to the operational amplifier unit;
the high-voltage floating ground operational amplifier circuit 13 uses 100V and 95V high-voltage power supply to enable the operational amplifier to work in a floating ground power supply state;
the constant current source circuit 15 adopts an operational amplifier and a two-stage triode to form a current source, improves the stability of an operational amplifier loop through strong negative feedback, balances the phase and has high output current regulation precision;
an H-bridge chopper circuit 16 for chopping the output of the constant current source circuit 15 into a specific waveform such as a unidirectional pulse current or a positive-negative bidirectional pulse current;
and the overcurrent and overload protection circuit 17 samples and monitors signals of the constant current source circuit 15 in real time and feeds the signals back to the logic control unit 10.
In a specific embodiment, the logic control unit 10 adopts an MCU or CP L D or FPGA logic control device.
The DAC circuit 14 generates a specific analog voltage whose accuracy range depends on the resolution of the DAC element used, and the error of the analog quantity of the DAC circuit 14 is optimized by the logic control unit 10 using a table lookup method or a linear function calibration method, and the analog voltage is supplied to the constant current source circuit 15 as a voltage input signal.
Referring to fig. 4, the high-voltage BOOST circuit 11 BOOSTs the input 15V to 100V or more, and includes a fast turn-off module and an overload protection module, which are composed of a power tube Q, an input capacitor Cin, an inductor L, a freewheeling diode D, and an output capacitor Cout.
Referring to fig. 5, the negative voltage generating circuit 12 generates voltages VH1 and VH2 by reducing a voltage of 100V high voltage or more to a desired potential, including T L V431.
Referring to fig. 6, the high-voltage floating operational amplifier circuit 13 and the constant current source circuit 15 use a potential of 100V or more as the positive terminal of the operational amplifier for power supply, use a potential of 95V or more as the negative terminal of the operational amplifier for power supply, and the potential difference between the positive terminal and the negative terminal meets the power supply requirement of the operational amplifier. The constant current source circuit 15 uses a rail-to-rail operational amplifier and two-stage triodes to form a current source. U2, Q3, Q4, R14 constitute a reference current source that converts the input current control reference voltage I _ REF into the required reference current source. The reference current source is converted to a reference voltage with respect to VH1(VH1 is 100V or higher) by R15. U3, Q5 and R18 form a main current source, current is sampled by R18, and the voltage at the lower end of R18 is equal to the voltage at the lower end of R15, so that a current source to the ground is formed through closed-loop control. Since U3 is a floating ground power supply system, the power supply is special. The positive power supply of U3 adopts VH1, the negative power supply adopts VH2 voltage, VH2 is from VH1 through the negative voltage converting circuit and Q2 controls the switch of I _ REF, the input signal waveform of the controllable constant current source.
Referring to fig. 7, the H-bridge chopper circuit 16 is controlled by the logic control unit 10 to generate a forward pulse or positive and negative bidirectional pulse current signal or other current signals with specific timing, and mainly comprises power tubes Q5, Q6, Q7 and Q8.
In the specific embodiment, the overcurrent and overload protection circuit 17 samples low-end current, samples and monitors the output of the constant current source circuit 15 in real time, and feeds the output back to the logic control unit 10, and when an overcurrent and overload phenomenon occurs, the logic control unit 10 turns off the high-voltage BOOST circuit 11.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A high-precision high-voltage current source circuit is characterized by comprising a logic control unit, a high-voltage Boost circuit, a negative voltage generating circuit, a DAC circuit, a high-voltage floating ground operational amplifier circuit, a constant current source circuit, an H-bridge chopper circuit and an overcurrent and overload protection circuit, wherein,
the logic control unit controls the DAC circuit to generate specific analog voltage, controls the high-voltage Boost circuit to be started or closed, controls the constant-current source circuit to be started or closed, and indirectly controls the H-bridge chopper circuit timing sequence and the overcurrent and overload protection circuit to recognize;
the DAC circuit converts the voltage output instruction of the logic control unit into a specific analog voltage signal and provides the specific analog voltage signal to the constant current source circuit as a voltage input signal;
the high-voltage BOOST circuit BOOSTs the 15V input voltage to a VH1 potential and is used for supplying the high-voltage floating ground operational amplifier circuit, and the high-voltage BOOST circuit comprises a quick turn-off module and an overload protection module;
the negative voltage generating circuit reduces the potential of VH1 to the potential of VH2 and is used for supplying the operational amplifier unit, and the negative voltage generating circuit comprises a shunt regulator T L V431;
the constant current source circuit adopts the operational amplifier and the two-stage triode to form a current source, improves the stability of an operational amplifier loop through strong negative feedback, balances the phase and has high output current regulation precision;
the H-bridge chopper circuit controls a chopping timing sequence by a logic control unit to generate a forward pulse current or a positive and negative bidirectional pulse current signal; the overcurrent and overload protection circuit samples and monitors the constant current source circuit signal in real time and feeds the constant current source circuit signal back to the logic control unit;
the high-voltage floating ground operational amplifier circuit uses a VH1 potential as the positive end of the operational amplifier for power supply, uses a VH2 potential as the negative end of the operational amplifier for power supply, the potential difference of the positive end and the negative end meets the power supply requirement of the operational amplifier, and the whole high-voltage operational amplifier works in a floating ground power supply mode and presents high voltage to the ground;
the constant current source circuit adopts a rail-to-rail operational amplifier and two stages of triodes to form a current source, the operational amplifier U2, the triodes Q3 and Q4 and a resistor R14 form a reference current source, the input current control reference voltage is converted into a required reference current source I _ REF, and the reference current source is converted into a reference voltage relative to VH1 through the resistor R15; the operational amplifier U3, the triode Q5 and the resistor R18 form a main current source, current is sampled through the resistor R18, and the voltage at the lower end of the resistor R18 is equal to the voltage at the lower end of the resistor R15, so that a current source to the ground is formed through closed-loop control; the operational amplifier U3 is in a floating ground power supply mode, the positive power supply of U3 adopts VH1, the negative power supply adopts VH2 voltage, VH2 is obtained from VH1 through a negative voltage conversion circuit, and a triode Q2 controls the switch of I _ REF and the input signal waveform of a constant current source.
2. The circuit of claim 1, wherein the logic control unit adopts MCU or CP L D or FPGA logic control device.
3. The circuit of claim 1, wherein the DAC circuit generates a specific analog voltage, the accuracy range of the analog voltage depends on the resolution of the DAC element used, and the error of the analog quantity of the DAC circuit is optimized by the logic control unit using a table lookup method or a linear function calibration method, and the analog voltage is supplied to the constant current source circuit as the voltage input signal.
4. The circuit of claim 1, wherein the over-current and over-load protection circuit employs low-side current sampling, real-time sampling to monitor the output of the constant current source circuit, and feeding the output back to the logic control unit, and the logic control unit turns off the high-voltage BOOST circuit when an over-current and over-load phenomenon occurs.
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| CN113156341B (en) * | 2021-03-11 | 2023-08-04 | 南京高速齿轮制造有限公司 | Gear box vibration sensor detection circuit and device |
| CN113644819B (en) * | 2021-06-29 | 2022-02-11 | 国网浙江省电力有限公司 | Ultrahigh voltage direct current generator and voltage adjusting method |
| CN113467563B (en) * | 2021-07-06 | 2022-07-22 | 中国航发北京航科发动机控制系统科技有限公司 | Bidirectional current source circuit |
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| US8294440B2 (en) * | 2009-06-27 | 2012-10-23 | Lowe Jr Brian Albert | Voltage regulator using depletion mode pass driver and boot-strapped, input isolated floating reference |
| CN201926944U (en) * | 2010-12-17 | 2011-08-10 | 天津市盛丹电子技术发展有限公司 | Microampere precise constant flow source circuit |
| CN102393225B (en) * | 2011-11-08 | 2013-09-04 | 合肥工业大学 | High/low voltage switching excitation system of electromagnetic flowmeter with bypass and energy feedback circuit |
| US8823346B2 (en) * | 2011-12-09 | 2014-09-02 | Intersil Americas LLC | System and method of feed forward for boost converters with improved power factor and reduced energy storage |
| CN102946190A (en) * | 2012-10-23 | 2013-02-27 | 深圳市新国都技术股份有限公司 | Positive and negative voltage generating circuit |
| CN103856051B (en) * | 2014-03-26 | 2016-04-27 | 中国科学院光电技术研究所 | A kind of high-voltage square-wave gain drive signal amplitude control device |
| CN104617808B (en) * | 2015-01-30 | 2017-10-24 | 重庆市计量质量检测研究院 | Square wave high-voltage pulse electric source circuit that polarity is adjustable and the control strategy for producing bipolar pulse |
| CN107885268A (en) * | 2016-09-29 | 2018-04-06 | 联芯科技有限公司 | Negative feedback current source circuit and electronic equipment |
| CN106444952A (en) * | 2016-11-16 | 2017-02-22 | 天津市盛丹电子技术发展有限公司 | High voltage constant current source |
| CN106405197B (en) * | 2016-11-25 | 2018-12-11 | 西安微电子技术研究所 | Flouride-resistani acid phesphatase 100V high precision electro current detection circuit |
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