CN109116903B - Bipolar high-precision constant-current driving system and method suitable for inductive load - Google Patents
Bipolar high-precision constant-current driving system and method suitable for inductive load Download PDFInfo
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Abstract
A bipolar high-precision constant current driving system and method suitable for inductive loads comprises the following steps: the device comprises a precision error amplification module, a bipolar power driving module and an inductive load frequency network compensation module; the input signal control module obtains a current analog signal through a current type digital-to-analog converter, and then performs current-to-voltage conversion and differential amplification to obtain a voltage analog signal; sending the amplified voltage analog signal to an error amplification module; meanwhile, the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module is amplified to obtain an error amplification signal, and the error amplification signal is sent to the bipolar power driving module to obtain an amplified bipolar driving current; and the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module. The constant current source product of the invention can improve the precision to 0.1 thousandth FSR, and the dynamic range of the current can reach ampere level.
Description
Technical Field
The invention relates to a bipolar high-precision constant-current driving system and method suitable for an inductive load, and belongs to the technical field of power drivers.
Background
In the aerospace and industrial fields, the stability and the precision of the driving constant current source realize the basis of high-performance indexes of aerospace precision equipment, the requirements on the dynamic range and the precision of the constant current source are higher and higher, and the high-performance program-controlled constant current source can be more and more widely applied.
As shown in fig. 5, most of the current constant current source circuits are developed and formed on the basis of the circuits of the basic constant current source through continuous improvement and improvement. The program-controlled constant current source generally adopts a voltage-controlled mode, namely, control voltage is generated firstly, and then the control voltage is converted into output current through a voltage-current circuit, so that the output current is adjusted through the size of the control voltage. However, the constant current sources have large differences in output range and accuracy due to differences in ways of controlling voltage generation, voltage-current conversion implementation and controlling output current.
In applications requiring a large current, such as motor driving and servo system driving, power devices, such as field effect transistors and darlington transistors, are commonly used to implement voltage-current conversion, and a single-loop control mode is mostly adopted, because the current amplifying capability of a power consumption device can reach hundreds of times or even thousands of times, the output range of the constant current source can be above ampere level, as shown in fig. 5, the constant current source schematic diagram of the conventional power operational amplifier is adopted. The method adopts the power operational amplifier to perform feedback adjustment, thereby realizing the constant current function. However, the regulation precision of the power operational amplifier is low, and the shunt channel of the feedback loop has influence on the output precision, so that the constant current output precision of the circuit is limited, and the maximum constant current output precision can only reach about 1 per thousand.
In the application environments of a test system and the medical field, such as calibration equipment, implantable technology and the like, a current output type D/A converter or an operational amplifier is mostly directly adopted to generate output current, although the precision can be in a mu A level or even an nA level, the precision is limited by factors such as the precision, the output range and the like of the D/A converter and the operational amplifier, the output current range is small, and therefore the dynamic output range of the constant current source can not reach dozens of mA or dozens of mA; in addition, in order to ensure the current output precision and stability, most of the devices adopt a constant temperature device or a heat dissipation device, so that the devices become complex in structure and large in size and are not suitable for embedded application.
In addition, most of precise constant current sources in the market cannot be perfectly adapted to inductive loads. When carrying an inductive load, the accuracy level cannot reach the nominal value. Because the current source output is adjustable, if the load is an inductive load, the load can induce a large reverse instantaneous electromotive force when the current changes. A freewheeling diode connected in parallel across the load may solve this problem. Normally, the diode is in a reverse cut-off state, and when the current changes and the two ends of the inductive load generate reverse induced electromotive force, the diode is conducted to release the reverse electromotive force. Besides generating a large back electromotive force, the inductive load may also cause the stability of the system, mainly because the current passing through the inductive load generates a lag, and the voltage at the inverting input terminal of the operational amplifier also has a lag, thereby increasing the high-frequency phase shift of the feedback loop, resulting in self-oscillation.
In summary, the prior constant current source technology mainly has the following disadvantages:
(1) the current driving capability and precision of the constant current source cannot be taken into consideration, the ampere-level driving capability and the 0.01% FSR precision cannot be guaranteed simultaneously, and the requirement of high-precision large-current driving occasions cannot be met.
(2) The driving inductive load capacity is poor, and oscillation is easy to occur.
Disclosure of Invention
The technical problem solved by the invention is as follows: the constant current control technology based on the composite negative feedback of precise error amplification and bipolar power drive solves the problem that the current drive capability and the precision can not be considered simultaneously by enabling the constant current source to reach 2.5A and simultaneously the output precision to reach 0.01 percent FSR, improves the output precision by one order of magnitude while improving the output dynamic range of the constant current source, and solves the problem that the inductive load is driven to easily generate oscillation by designing a reasonable inductive load frequency network compensation loop, thereby improving the phase margin of a constant current source system, the stability of the system is improved.
The technical scheme of the invention is as follows: a bipolar high-precision constant current driving system suitable for inductive loads comprises: the system comprises an input signal control module, a precision error amplification module, a sampling feedback module, a bipolar power driving module and an inductive load frequency network compensation module;
the input signal control module receives an external current digital signal, performs digital-to-analog conversion to obtain a current analog signal, and performs current-to-voltage conversion to obtain a voltage analog signal; amplifying the voltage analog signal, and sending the amplified voltage analog signal to a precision error amplification module;
the precision error amplification module receives the fed-back voltage analog signal from the sampling feedback module, amplifies the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module to obtain an error amplification signal, and sends the error amplification signal to the bipolar power driving module;
the bipolar power driving module is used for carrying out power amplification on the error amplification signal to obtain a current signal and transmitting the current signal to an external load;
the sampling feedback module converts a current signal input by an external load into a voltage signal, and then performs differential amplification on the voltage signal and a ground signal generated by the sampling feedback module to obtain a feedback voltage analog signal
And the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module.
And the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module, namely compensating the phase of a current signal output by the bipolar power driving module.
An input signal control module comprising: DA current control module, differential amplifier 1, resistor RaResistance Rb；
The input of the DA current control module is an external current digital signal, the output two paths of current signals with complementary amplitudes of the DA current control module are Ia and Ib respectively, and the current signals are transmitted through a resistor RaResistance RbThe voltage signals are respectively converted into voltage signals and are sent to two signal input ends of a differential amplifier, and the signal output end of the differential amplifier is output to a precision error amplification module through a resistor R1.
One signal output end of the DA current control module is connected with the signal positive input end of the differential amplifier and is connected with the signal positive input end of the differential amplifier through a resistor RaGrounding; another signal output terminal of the DA current control moduleIs connected with the signal negative input end of the differential amplifier and passes through a resistor RbGrounding; the signal output end of the differential amplifier is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the precision error amplification module.
A precision error amplification module comprising: an error amplifier, a capacitor C2 and a resistor Rb 2;
the signal positive input end of the error amplifier is connected with the input signal control module, and the signal negative input end of the error amplifier is connected with one end of the capacitor C2, the sampling feedback module and the inductive load frequency network compensation module; the other end of the capacitor C2 is connected to the output end of the error amplifier and the bipolar power driving module through a resistor Rb 2.
A bipolar power driver module comprising: the power amplifier, the resistor R3, the resistor R4, the resistors R11 and Cf;
one end of the resistor R3 is connected with the precision error amplification module, and the other end of the resistor R3 is connected with the signal positive input end of the power amplifier; the output end of the power amplifier is connected with one end of the resistor R11; the negative signal input end of the power amplifier is grounded through a resistor R4, the other end of the resistor R11 and the positive end of an external load are connected through a resistor Rf, and the two ends of a capacitor Cf are respectively connected with the two ends of Rf.
An inductive load frequency network compensation module comprising: capacitor C1, resistor Rb1 and buffer resistor RsnubberBuffer capacitor Csnubber；
One end of a capacitor C1 is connected with the precision error amplification module and the sampling feedback module, and the other end of the capacitor C1 is connected with the output end of the bipolar power drive module, the positive end of an external load and the buffer resistor R through a resistor Rb1snubberOne end of (1), a buffer resistor RsnubberThe other end of the capacitor is connected with a buffer capacitor CsnubberAnd (4) grounding.
A sampling feedback module comprising: resistor R2, resistor R10, resistor R7, follower 1, follower 2, resistor R5, differential amplifier 2, resistor R8, resistor R9, resistor R6 and sampling resistor RsA capacitor C3 and a resistor Rb 3;
one end of the resistor R5 is connected with an external load and the sampling resistor RsAnd the other end of the resistor R5 is connected with a follower1 signal input positive terminal, sampling resistor RsThe other end of the resistor is connected with the signal input positive terminal of the follower 2 through a resistor R6; the signal input negative end of the follower 1 is connected with the signal output end and one end of a resistor R7, the other end of a resistor R7 is connected with one end of a resistor R10 and the input positive end of a differential amplifier, and the other end of a resistor R10 is connected with the output end of the differential amplifier and one end of a resistor R2; the signal input negative terminal of the follower 2 is connected with the signal output terminal and one end of a resistor R8, and the other end of the resistor R8 is grounded through a resistor R9 and connected with the input negative terminal of the differential amplifier; the other end of the resistor R2 is connected with the precision error amplification module and the inductive load frequency network compensation module, the capacitor C3 is connected with one end of the R10, the other end of the capacitor C3 is connected with one end of the resistor Rb3, and the other end of the Rb3 is connected with the output end of the follower 1.
The external load is an inductive load of the motor, and comprises: linear motor, voice coil motor.
A bipolar high-precision constant current driving method suitable for inductive loads comprises the following steps:
(1) the input signal control module receives an external current digital signal, performs digital-to-analog conversion to obtain a current analog signal, and performs current-to-voltage conversion to obtain a voltage analog signal;
(2) amplifying the voltage analog signal, and sending the amplified voltage analog signal to a precision error amplification module;
(3) the precision error amplification module receives the fed-back voltage analog signal from the sampling feedback module, amplifies the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module to obtain an error amplification signal, and sends the error amplification signal to the bipolar power driving module;
(4) the bipolar power driving module is used for carrying out power amplification on the error amplification signal to obtain a current signal and transmitting the current signal to an external load;
(5) the sampling feedback module converts a current signal input by an external load into a voltage signal, and then performs differential amplification on the voltage signal and a ground signal generated by the sampling feedback module to obtain a feedback voltage analog signal
(6) And (5) compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module by the inductive load frequency network compensation module at the same time.
Compared with the prior art, the invention has the advantages that:
(1) aiming at the problem that the precision is generally lower than 1 per thousand due to the restriction of the precision of a power device and a control method in the application of larger current (ampere level), the invention provides a constant current drive control technology based on composite negative feedback, which can enable the driving capability of a constant current source to reach 2.5A, simultaneously enable the output precision to reach 0.01 percent FSR, improve the output dynamic range of the constant current source and simultaneously improve the output precision by one order of magnitude.
(2) The constant current source product designed by the method can improve the precision to 0.1 thousandth FSR, and meanwhile, the dynamic range of the current can reach ampere level, so the constant current source product can be applied to high-precision driving occasions, particularly application occasions requiring large current range and high precision, such as motor driving and servo system driving, and has very wide market application prospect.
(3) The invention adopts a composite negative feedback amplification technology based on a precision error operational amplifier and a power operational amplifier, so that the precision of the constant current source is greatly improved while the dynamic range is improved.
(4) The invention adopts a feedback amplification mode of a precision instrument, improves the input impedance of the output current sampling circuit, and avoids the problem of reduced constant current control precision caused by the shunt of the sampling feedback loop.
(5) The invention introduces a phase compensation feedback network, increases the phase margin of the constant current source and improves the control stability of the inductive load of the constant current source.
(6) The invention reduces or eliminates the current oscillation problem caused by output parasitic parameters by introducing a snubber damping filter.
(7) The invention avoids the crosstalk problem between multi-path constant current drive output by respectively distributing the power ground and the signal ground and sharing the power ground and the signal ground nearby.
Drawings
FIG. 1 is a block diagram of the system architecture of the present invention;
FIG. 2 is a circuit diagram of an implementation of the present invention;
FIG. 3 is a graph of constant current source stability test results;
fig. 4(a) shows the step response (inductive load) of the high-precision constant current source before compensation, and (b) shows the step response (inductive load) of the high-precision constant current source after compensation;
FIG. 5 is a schematic diagram of a conventional power operational amplifier;
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
The invention discloses a bipolar high-precision constant current driving system and method suitable for an inductive load, which comprises the following steps: the system comprises an input signal control module, a precision error amplification module, a sampling feedback module, a bipolar power driving module and an inductive load frequency network compensation module; the input signal control module obtains a current analog signal through a current type digital-to-analog converter, and then performs current-to-voltage conversion and differential amplification to obtain a voltage analog signal; sending the amplified voltage analog signal to an error amplification module; meanwhile, the difference value between the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module is amplified to obtain an error amplification signal, and the error amplification signal is sent to the bipolar power driving module to obtain an amplified bipolar driving current; and the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module. The constant current source product of the invention can improve the precision to 0.1 thousandth FSR, and the dynamic range of the current can reach ampere level.
In precision machining, precision measurement, motion control and drive control, a motor constant-current drive system is used as a drive control core component, the drive capability and precision of the constant-current drive system have direct influence on the requirements of precision machining, measurement precision and motion control precision, and the constant-current drive system provides important basis and guarantee for the motor constant-current drive system. Taking an active directional hyperstatic platform as an example, active damping is realized through a high-performance damper actuator assembly to isolate the vibration of a load and a star body, a constant-current driving system has the function of outputting certain current to control the actuator assembly, the movement direction of the actuator assembly is opposite to the movement of the star body, and the amplitude is equal, so that the aim of inhibiting the vibration is fulfilled, and the size and the precision of the current output by the constant-current driving system have important influence on the damping performance of the platform.
Aiming at the problems that the traditional constant current driving system cannot simultaneously consider the driving output capacity and the precision and cannot well adapt to inductive load, the invention provides a bipolar high-precision constant current driving system suitable for inductive load, as shown in figure 1, and the bipolar high-precision constant current driving system is characterized by comprising the following components: the system comprises an input signal control module, a precision error amplification module, a sampling feedback module, a bipolar power driving module and an inductive load frequency network compensation module;
the input signal control module receives an external current digital signal (the range is 0-65535), and performs digital-to-analog conversion to obtain a complementary current analog signal IaAnd IbThen the current is converted into voltage through a high-precision low-temperature drift resistor (V)i＝(Ia-Ib) Xr) to obtain a voltage analog signal; amplifying the voltage analog signal, and amplifying (preferably by a magnification factor K)1And the amplification factor K of the sampling feedback signal2Equal to each other) to a precision error amplifying module;
the precision error amplification module receives the fed-back voltage analog signal from the sampling feedback module, amplifies the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module to obtain an error amplification signal, and sends the error amplification signal to the bipolar power driving module;
the bipolar power driving module is used for carrying out power amplification (preferably, the amplification factor is 3 times) on the error amplification signal to obtain a current signal and sending the current signal to an external load;
the sampling feedback module converts a current signal input by an external load into a voltage signal, and then performs difference on the voltage signal and a ground signal (a sampling point is preferably near a sampling resistor) generated by the sampling feedback module through an operational amplifier followerAmplification (preferably magnification K)2Preferred and input signal control module amplification factor K1Equal), to obtain a feedback voltage analog signal
And the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module.
An input signal control module comprising: DA current control module, differential amplifier 1, resistor RaResistance Rb；
The input of the DA current control module is an external current digital signal, the output two paths of current signals with complementary amplitudes of the DA current control module are Ia and Ib respectively, and the current signals are transmitted through a resistor RaResistance RbThe voltage signals are respectively converted into voltage signals and are sent to two signal input ends of a differential amplifier, and the signal output end of the differential amplifier is output to a precision error amplification module through a resistor R1.
One signal output end of the DA current control module is connected with the signal positive input end of the differential amplifier and is connected with the signal positive input end of the differential amplifier through a resistor RaGrounding; the other signal output end of the DA current control module is connected with the signal negative input end of the differential amplifier and is connected with the signal negative input end of the differential amplifier through a resistor RbGrounding; the signal output end of the differential amplifier is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the precision error amplification module.
A precision error amplification module comprising: an error amplifier, a capacitor C2 and a resistor Rb 2;
the signal positive input end of the error amplifier is connected with the input signal control module, and the signal negative input end of the error amplifier is connected with one end of the capacitor C2, the sampling feedback module and the inductive load frequency network compensation module; the other end of the capacitor C2 is connected to the output end of the error amplifier and the bipolar power driving module through a resistor Rb 2.
As shown in fig. 2, the bipolar power driver module includes: the power amplifier, the resistor R3, the resistor R4, the resistors R11 and Cf;
one end of the resistor R3 is connected with the precision error amplification module, and the other end of the resistor R3 is connected with the signal positive input end of the power amplifier; the output end of the power amplifier is connected with one end of the resistor R11; the negative signal input end of the power amplifier is grounded through a resistor R4, the other end of the resistor R11 and the positive end of an external load are connected through a resistor Rf, and the two ends of a capacitor Cf are respectively connected with the two ends of Rf.
An inductive load frequency network compensation module comprising: capacitor C1, resistor Rb1 and buffer resistor RsnubberBuffer capacitor Csnubber；
One end of a capacitor C1 is connected with the precision error amplification module and the sampling feedback module, and the other end of the capacitor C1 is connected with the output end of the bipolar power drive module, the positive end of an external load and the buffer resistor R through a resistor Rb1snubberOne end of (1), a buffer resistor RsnubberThe other end of the capacitor is connected with a buffer capacitor CsnubberAnd (4) grounding.
A sampling feedback module comprising: resistor R2, resistor R10, resistor R7, follower 1, follower 2, resistor R5, differential amplifier 2, resistor R8, resistor R9, resistor R6 and sampling resistor RsA capacitor C3 and a resistor Rb 3;
one end of the resistor R5 is connected with an external load and the sampling resistor RsThe other end of the resistor R5 is connected with the signal input positive terminal of the follower 1, and the resistor R is sampledsThe other end of the resistor is connected with the signal input positive terminal of the follower 2 through a resistor R6; the signal input negative end of the follower 1 is connected with the signal output end and one end of a resistor R7, the other end of a resistor R7 is connected with one end of a resistor R10 and the input positive end of a differential amplifier, and the other end of a resistor R10 is connected with the output end of the differential amplifier and one end of a resistor R2; the signal input negative terminal of the follower 2 is connected with the signal output terminal and one end of a resistor R8, and the other end of the resistor R8 is grounded through a resistor R9 and connected with the input negative terminal of the differential amplifier; the other end of the resistor R2 is connected with the precision error amplification module and the inductive load frequency network compensation module, the capacitor C3 is connected with one end of the R10, the other end of the capacitor C3 is connected with one end of the resistor Rb3, and the other end of the Rb3 is connected with the output end of the follower 1.
As shown in fig. 2, it is a schematic diagram of a constant current driving system according to the present invention, and the design concept of the present invention is explained in the following with reference to the schematic diagram;
the input signal control module adopts the design idea of adopting current type digital-to-analog conversionThe device outputs complementary current to reduce interference in signal transmission via precision resistor Ra、RbConverting the complementary output current signals into voltage signals, and then carrying out differential amplification to convert the complementary output current signals into bipolar voltage control signals;
the design idea of the precise error amplification module is to adopt a high-precision operational amplifier to precisely amplify and regulate input and sampling feedback voltage signals, reduce offset voltage, and simultaneously add proportional-integral links C2 and Rb2 to improve regulation precision, while the design idea of the traditional constant current source system is to directly adopt a power amplifier to carry out error feedback regulation, so that regulation control precision is low.
The design idea of the bipolar power driving module is to adopt a bipolar high-power operational amplifier to amplify power and then use a proportional amplification link (R)fR4) to achieve voltage amplification to meet the voltage regulation required for output.
The design realization thinking of sampling feedback module is for floating sampling resistance Rs through high accuracy low temperature and adopt load current, put follower 1 and follower 2 through fortune and keep apart the signal at sampling resistance both ends, the high input impedance characteristic that mainly utilizes fortune to put realizes the effect that sampling resistance and collection circuit impedance keep apart, avoid reducing the constant current output precision owing to gather the circuit reposition of redundant personnel, should get the sampling point at sampling resistance Rs root in PCB design in addition, reduce because PCB walks the loss of precision that line impedance arouses.
The inductive load frequency network compensation module is designed in the way that phase compensation is carried out on loop phase deviation caused by inductive loads, the problem of output oscillation caused by insufficient loop phase margin is solved, and the constant current driving system can drive the inductive loads well.
In order to ensure the performance of the constant current driving system, the parameter matching relationship of each module preferably meets the following requirements:
the preferred scheme is as follows: ra is Rb, and the error between Ra and Rb is not more than 0.01% R, so that complementary current is converted into bipolar voltage control signals with symmetrical positive and negative after differential amplification, and the accuracy error of the final output current is 0.25 mA.
The further preferred scheme is as follows: K1-K2-R10/R7, R7-R8 and R9-R10, so that the input signal control module and the sampling feedback module are matched in proportionality coefficient, and output current in a full range can be guaranteed.
The preferred scheme is as follows: preferably, Rf/R4 in the bipolar power amplification module is 3, when the proportionality coefficient is too low, the output current is large, the output voltage is insufficient, the driving capability cannot be guaranteed, and when the proportionality coefficient is too large, the stability of the system is affected. In addition, a further preferred scheme is as follows: r3 Rf// R4, making the symmetry better. The further preferred scheme is as follows: r11 ═ 0.809/| ILIML-0.057, wherein ILIMThe current limit value is used, so that the output short circuit can not damage the power operational amplifier.
The preferred scheme is as follows: in the inductive load frequency network compensation module, RsnubberPreferably not more than 10 Ω, CsnubberPreferably greater than 10nF so that the output current does not oscillate.
Between the multi-path constant current drive output, the ground wires are separately designed, and the common ground point is common to the root of the power supply, so that the influence of crosstalk between the multi-path output on the output current precision is avoided.
The performance of the constant current driving system is tested by a developed constant current driving system prototype, as shown in fig. 3, the stability output measurement result of high-precision constant current for nearly 4h is shown, the abscissa is time, the unit is time/10s, and represents that 1 unit is 10s, the ordinate is output current of the constant current driving system, the unit is ampere, the curve shows that the total maximum deviation of the output after electrification is 0.4mA, the precision is 0.016% FSR, and the output of the constant current source reaches the stable state after electrification for about 15min, at the moment, the stability of the constant current source is better than 40ppm/h, the maximum deviation is 0.1mA, and the precision is 0.004% FSR. Compared with the precision of 0.1% FSR of a traditional high-power constant-current driving system, the precision is improved by more than 6 times, the current driving capability is improved by 5 to 10 times while the precision is improved, and the effect is obvious.
As shown in fig. 4(a) and (b), the curves are step response curves before and after phase compensation when the constant current source is loaded with inductance, the abscissa is time, the unit of each grid is 400 μ s, and the ordinate is sampling voltage, so that before feedback through phase compensation, the constant current source output has oscillation, the oscillation frequency is about 3.3kHz, the oscillation amplitude is about ± 150mA, after compensation is added, the output oscillation disappears, and the system output is stable.
In summary, after the driving capability of the conventional constant current source reaches the ampere level, the constant current precision of the conventional constant current source can only reach 0.1%, and aiming at the problem that the driving capability and the constant current precision of the conventional constant current source cannot be considered at the same time, a precise error amplifier is constructed in the circuit structure and used as a front-stage amplifier to obtain a smaller input offset voltage and a higher bandwidth, and a high-power operational amplifier is adopted in a rear stage, so that a higher output voltage and a continuously output large current are obtained. The constant current control requirements of wide dynamic range and high precision are realized by a two-stage composite feedback amplification method, and meanwhile, a phase compensation feedback network is introduced for better adapting to driving of the inductive load, so that the phase margin of the constant current source is increased, the control stability of the inductive load of the constant current source is improved, and the constant current driving system can well drive the inductive motor load. Through the separate wiring of each power ground and each signal ground, the near common ground and the separate design of the multiple paths of ground wires, the problem of crosstalk between the multiple paths of constant current driving outputs is avoided, and the precision of the constant current driving system is further improved.
Aiming at the problem that the precision is generally lower than 1 per thousand due to the restriction of the precision of a power device and a control method in the application of larger current (ampere level), the invention provides a constant current drive control technology based on composite negative feedback, which can enable the driving capability of a constant current source to reach 2.5A, simultaneously enable the output precision to reach 0.01 percent FSR, improve the output dynamic range of the constant current source and simultaneously improve the output precision by one order of magnitude. The constant current source product designed by the method can improve the precision to 0.1 thousandth FSR, and meanwhile, the dynamic range of the current can reach ampere level, so the constant current source product can be applied to high-precision driving occasions, particularly application occasions requiring large current range and high precision, such as motor driving and servo system driving, and has very wide market application prospect.
The invention adopts a composite negative feedback amplification technology based on a precision error operational amplifier and a power operational amplifier, so that the precision of the constant current source is greatly improved while the dynamic range is improved. The feedback amplification mode of the precision instrument is adopted, the input impedance of the output current sampling circuit is improved, and the problem of reduction of the constant current control precision caused by shunt of the sampling feedback loop is solved. The invention introduces a phase compensation feedback network, increases the phase margin of the constant current source and improves the control stability of the inductive load of the constant current source. By introducing a snubber damping filter, the problem of current oscillation due to output parasitic parameters is reduced or eliminated. The crosstalk problem between the multi-path constant current driving output is avoided by the fact that each power ground and the signal ground are separately arranged and are nearby and common.
The system and the method can be applied to high-precision driving occasions, particularly application occasions requiring large current range and high precision, the system is applied to an active directional hyperstatic platform at present, good control effect is achieved on vibration suppression of loads, the system and the method can also be applied to motor driving and servo system driving, and the market application prospect is very wide.
Claims (7)
1. A bipolar high-precision constant current driving system suitable for inductive loads is characterized by comprising: the system comprises an input signal control module, a precision error amplification module, a sampling feedback module, a bipolar power driving module and an inductive load frequency network compensation module;
the input signal control module receives an external current digital signal, performs digital-to-analog conversion to obtain a current analog signal, and performs current-to-voltage conversion to obtain a voltage analog signal; amplifying the voltage analog signal, and sending the amplified voltage analog signal to a precision error amplification module;
the precision error amplification module receives the fed-back voltage analog signal from the sampling feedback module, amplifies the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module to obtain an error amplification signal, and sends the error amplification signal to the bipolar power driving module;
the bipolar power driving module is used for carrying out power amplification on the error amplification signal to obtain a current signal and transmitting the current signal to an external load;
the sampling feedback module converts a current signal input by an external load into a voltage signal, and then performs differential amplification on the voltage signal and a ground signal generated by the sampling feedback module to obtain a feedback voltage analog signal;
the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module;
a bipolar power driver module comprising: the power amplifier, the resistor R3, the resistor R4, the resistors R11 and Cf;
one end of the resistor R3 is connected with the precision error amplification module, and the other end of the resistor R3 is connected with the signal positive input end of the power amplifier; the output end of the power amplifier is connected with one end of the resistor R11; the negative signal input end of the power amplifier is grounded through a resistor R4, the other end of the resistor R11 and the positive end of an external load are connected through a resistor Rf, the two ends of a capacitor Cf are respectively connected with the two ends of Rf, Rf/R4 is 3, and R3 is Rf// R4;
an inductive load frequency network compensation module comprising: capacitor C1, resistor Rb1 and buffer resistor RsnubberBuffer capacitor Csnubber；
One end of a capacitor C1 is connected with the precision error amplification module and the sampling feedback module, and the other end of the capacitor C1 is connected with the output end of the bipolar power drive module, the positive end of an external load and the buffer resistor R through a resistor Rb1snubberOne end of (1), a buffer resistor RsnubberThe other end of the capacitor is connected with a buffer capacitor CsnubberGrounding; in the inductive load frequency network compensation module, RsnubberPreferably not more than 10 Ω, CsnubberPreferably greater than 10nF, so that the output current does not oscillate;
a sampling feedback module comprising: resistor R2, resistor R10, resistor R7, follower 1, follower 2, resistor R5, differential amplifier 2, resistor R8, resistor R9, resistor R6 and sampling resistor RsA capacitor C3 and a resistor Rb 3;
one end of the resistor R5 is connected with an external load and the sampling resistor RsThe other end of the resistor R5 is connected with the signal input positive terminal of the follower 1, and the resistor R is sampledsThe other end of the resistor is connected with a resistor R6The signal input positive terminal of the follower 2 is connected; the signal input negative end of the follower 1 is connected with the signal output end and one end of a resistor R7, the other end of a resistor R7 is connected with one end of a resistor R10 and the input positive end of a differential amplifier, and the other end of a resistor R10 is connected with the output end of the differential amplifier and one end of a resistor R2; the signal input negative terminal of the follower 2 is connected with the signal output terminal and one end of a resistor R8, and the other end of the resistor R8 is grounded through a resistor R9 and connected with the input negative terminal of the differential amplifier; the other end of the resistor R2 is connected with the precision error amplification module and the inductive load frequency network compensation module, the capacitor C3 is connected with one end of the R10, the other end of the capacitor C3 is connected with one end of the resistor Rb3, and the other end of the Rb3 is connected with the output end of the follower 1.
2. The bipolar high-precision constant current driving system applicable to an inductive load according to claim 1, wherein: and the inductive load frequency network compensation module is used for compensating the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module, namely compensating the phase of a current signal output by the bipolar power driving module.
3. The bipolar high-precision constant current driving system applicable to an inductive load according to claim 1, wherein: an input signal control module comprising: DA current control module, differential amplifier 1, resistor RaResistance Rb；
The input of the DA current control module is an external current digital signal, the output two paths of current signals with complementary amplitudes of the DA current control module are Ia and Ib respectively, and the current signals are transmitted through a resistor RaResistance RbThe voltage signals are respectively converted into voltage signals and are sent to two signal input ends of a differential amplifier, and the signal output end of the differential amplifier is output to a precision error amplification module through a resistor R1.
4. The bipolar high-precision constant current driving system applicable to an inductive load according to claim 1, wherein: one signal output end of the DA current control module is connected with the signal positive input end of the differential amplifierAnd through a resistor RaGrounding; the other signal output end of the DA current control module is connected with the signal negative input end of the differential amplifier and is connected with the signal negative input end of the differential amplifier through a resistor RbGrounding; the signal output end of the differential amplifier is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the precision error amplification module.
5. The bipolar high-precision constant current driving system applicable to an inductive load according to claim 1, wherein: a precision error amplification module comprising: an error amplifier, a capacitor C2 and a resistor Rb 2;
the signal positive input end of the error amplifier is connected with the input signal control module, and the signal negative input end of the error amplifier is connected with one end of the capacitor C2, the sampling feedback module and the inductive load frequency network compensation module; the other end of the capacitor C2 is connected to the output end of the error amplifier and the bipolar power driving module through a resistor Rb 2.
6. The bipolar high-precision constant current driving system applicable to an inductive load according to claim 1, wherein: the external load is an inductive load of the motor, and comprises: linear motor, voice coil motor.
7. A bipolar high-precision constant current driving method suitable for inductive loads is characterized by comprising the following steps:
(1) the input signal control module receives an external current digital signal, performs digital-to-analog conversion to obtain a current analog signal, and performs current-to-voltage conversion to obtain a voltage analog signal;
(2) amplifying the voltage analog signal, and sending the amplified voltage analog signal to a precision error amplification module;
(3) the precision error amplification module receives the fed-back voltage analog signal from the sampling feedback module, amplifies the difference value of the amplified voltage analog signal sent by the input signal control module and the voltage analog signal sent by the sampling feedback module to obtain an error amplification signal, and sends the error amplification signal to the bipolar power driving module;
(4) the bipolar power driving module is used for carrying out power amplification on the error amplification signal to obtain a current signal and transmitting the current signal to an external load;
a bipolar power driver module comprising: the power amplifier, the resistor R3, the resistor R4, the resistors R11 and Cf;
one end of the resistor R3 is connected with the precision error amplification module, and the other end of the resistor R3 is connected with the signal positive input end of the power amplifier; the output end of the power amplifier is connected with one end of the resistor R11; the negative signal input end of the power amplifier is grounded through a resistor R4, the other end of the resistor R11 and the positive end of an external load are connected through a resistor Rf, the two ends of a capacitor Cf are respectively connected with the two ends of Rf, Rf/R4 is 3, and R3 is Rf// R4;
(5) the sampling feedback module converts a current signal input by an external load into a voltage signal, and then performs differential amplification on the voltage signal and a ground signal generated by the sampling feedback module to obtain a feedback voltage analog signal;
(6) while the step (5) is carried out, the inductive load frequency network compensation module compensates the phase of a loop consisting of the precision error amplification module, the bipolar power driving module and the sampling feedback module;
an inductive load frequency network compensation module comprising: capacitor C1, resistor Rb1 and buffer resistor RsnubberBuffer capacitor Csnubber；
One end of a capacitor C1 is connected with the precision error amplification module and the sampling feedback module, and the other end of the capacitor C1 is connected with the output end of the bipolar power drive module, the positive end of an external load and the buffer resistor R through a resistor Rb1snubberOne end of (1), a buffer resistor RsnubberThe other end of the capacitor is connected with a buffer capacitor CsnubberGrounding; in the inductive load frequency network compensation module, RsnubberPreferably not more than 10 Ω, CsnubberPreferably greater than 10nF so that the output current does not oscillate.
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| CN110989715B (en) * | 2019-11-26 | 2022-03-25 | 山东航天电子技术研究所 | High-stability constant current source generating circuit and temperature measuring circuit |
| CN114006554B (en) * | 2021-11-19 | 2024-06-14 | 北京轩宇空间科技有限公司 | Constant-current driving device of high-precision voice coil actuator |
| CN115236374B (en) * | 2022-09-21 | 2022-12-27 | 广州思林杰科技股份有限公司 | Miniaturized programmable power supply and power supply output method thereof |
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