CN107037760B - A kind of input current type artifical resistance device and resistance control method - Google Patents
A kind of input current type artifical resistance device and resistance control method Download PDFInfo
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- G—PHYSICS
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
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Abstract
The purpose of the present invention is to provide a kind of input current type artifical resistance device and resistance control methods, it includes the current source being sequentially connected in series, current-voltage converter, converter, processor, D/A converter and Voltage-voltage converter, during artifical resistance, it can cause the mainly current-voltage converter of error in above each circuit, converter, D/A converter and Voltage-voltage converter, by the error analysis of final artifical resistance and by eliminate and calibration fitting is combined to realize eliminating its error to error in embeded processor, to improve final output artifical resistance precision and resistance value stability.
Description
Technical field
The present invention relates to servo electrical component fields, are specifically related to a kind of input current type artifical resistance device.
Background technique
It is manual that existing variable resistance, which has these traditional resistor casees of resistance box, mechanical potentiometer, digital regulation resistance,
Variable resistance is difficult to automatically adjust.In order to program-controlled adjust, also there is some program-controlled artifical resistances, most common way
For digital synthesis technology, (passing through given input stimulus electric current) adjusts output voltage to realize the control of combined resistance resistance value.
Wherein output voltage is equal to exciting current multiplied by combined resistance, i.e. output voltage is directly proportional to exciting current, the synthesis with setting
Resistance is directly proportional, specific as shown in Figure 1, measuring exciting current I by current measuring membersiSize, further according to combined resistance
Setting value Rx, the DC voltage U of setting program-controlled voltage source outputo, wherein Uo=Ii×Rx。
The central principle of the program-controlled scheme is to be changed by will fix input current to be sent to the reference of DAC after voltage
End, as the reference voltage of output DAC, the deficiency of the program is the reference voltage by adjusting DAC, so that DAC itself exists
The error generated under different resistance values is there are non-linear, by correcting the error for being difficult to solve thus to introduce, causes final
The stability of the artifical resistance arrived is not satisfactory.
Because the precision of any DAC and ADC depends critically upon the performance of benchmark.If regarding input as DAC reference data
So that entirely the precision of output DAC cannot be guaranteed.
Summary of the invention
The problem of based on above method, technical solution of the present invention acquire the fixed input current in front end by ADC,
According to resistance setting value, output end provides relevant voltage value by DAC, reaches artifical resistance purpose, by selecting appropriate reference
Voltage makes front-end A/D C and rear end DAC work in optimum state, to evade caused by de-regulation ADC and DAC reference voltage
Nonlinearity erron, although front end introduces an ADC again, by reasonably designing, the error that front-end A/D C is introduced is linear misses
Difference is easier to be modified to achieve the purpose that output artifical resistance is stable.In addition, the original that can be also generated in conjunction with error
Cause is targetedly analyzed and is removed, and the difficulty and workload of fitting are reduced.
And due to realizing in numeric field than at higher precision in analog domain, more highly reliable and more low price various signals
Function is managed, number inhibits the ability of noise to be much larger than analog signal, in analog signal during storing and transmitting, noise and mistake
It can very be accumulated, so that the processing to signal generates undesirable effect, and in numeric field, digital signal can be stored nondestructively
And transmission, this is also another advantage of technical solution of the present invention.
Specially a kind of input current type artifical resistance device, it is characterised in that: including current source, the electricity being sequentially connected in series
Stream-electric pressure converter, converter, processor, D/A converter and Voltage-voltage converter, wherein processor receives AD conversion
The voltage value of device input makes it export corresponding voltage signal logical further according to the output of target resistance resistance value control D/A converter
Voltage required for overvoltage-electric pressure converter control generates.
Further, it is characterised in that: the current-voltage converter includes an operational amplifier, positive input
It is connected with current source, while being also connected with high-precision fixed value resistance Rref, reverse input end is connected to the string connecting with output end
Join the tie point between sampling resistor R1 and R2.
Further, it is characterised in that: mode is calculated as follows for the amendment of artifical resistance value and is carried out:Wherein RxFor the resistor resistance value of required simulation, wherein UaIndicate input terminal voltage value, Ub
Indicate output end voltage value, input current Ii, RrefFor company, operational amplifier positive input institute in current-voltage converter
The sample resistance resistance value connect.
Further, it is characterised in that: the amendment for artifical resistance value, in the imbalance electricity for considering the operational amplifier
In the case where stream and offset voltage, the actual output voltage of operational amplifier and the error of desired output voltage are as follows:
Wherein, UIOFor the offset voltage of the operational amplifier, offset current IB1And IB2Just for the operational amplifier
To the offset current of, negative input,
Summarize in processor and is compensated by its error.
Further, it is characterised in that: the amendment for artifical resistance value, it is also contemplated that first operational amplifier
In the case where temperature drift, the error of the first operational amplifier, and its error is compensated in the processor, the error calculation is public
Formula are as follows:
Input offset current IB1、IB2Temperature drift be respectively TCIB1And TCIB2, input offset voltage UIOTemperature drift
For TCV.
Further, it is characterised in that:
It is also contemplated that the transformed error of converter and D/A converter, formula are respectively as follows:
ΔUADC=NADC ULSBADC；
ΔUDAC=NDAC ULSBDAC；
Wherein, ULSBADC、ULSBDACRespectively referring to ADC, DAC input digital quantity lowest order is 1, remaining corresponding conversion when being 0
Voltage, i.e.,
Wherein n1, n2 respectively indicate ADC, DAC change data most
Big digit
NADCIt is determined according to actual measurement ADC error, NDACIt is determined according to actual measurement DAC error.
Further, it is characterised in that: the resistance simulation device it is also contemplated that second operational amplifier offset current with
Error caused by offset voltage, calculation are as follows:
Wherein, R1' be output par, c operational amplifier negative input and ground between sampling resistor
R2' input resistance that is connected by the positive input of output par, c operational amplifier
Rf' be output par, c operational amplifier positive input and output end between sampling resistor
UIO' be output par, c operational amplifier offset voltage
IB1' be output par, c operational amplifier positive input offset current
IB2' be output par, c operational amplifier negative input offset current
Further, it is characterised in that: the resistance simulation device is also contemplated that the second operation amplifier of output driving part
The error that device temperature drift generates
Wherein, TCV ' is the offset voltage temperature drift of output par, c operational amplifier
TCIB1’For the offset current temperature drift of output par, c operational amplifier positive input
TCIB2’For the offset current temperature drift of output par, c operational amplifier negative input
T is temperature drift amount
Further, it is characterised in that: the calculation formula of artifical resistance value is as follows:
Wherein, current-voltage transformation ratio is K1, Voltage-voltage transformation ratio is K2。
The present invention also provides a kind of resistance control methods of input current type artifical resistance device, it is characterised in that: in use
State current mode artifical resistance device described in either a program, to its resistance control using fitting and error concealment combine method into
Row.
Detailed description of the invention
Fig. 1 artifical resistance device schematic diagram in the prior art
The functional block diagram of input current type artifical resistance device Fig. 2 of the invention
The circuit structure diagram of input current type artifical resistance device Fig. 3 (a) of the invention
The equivalent circuit diagram of input current type artifical resistance device Fig. 3 (b) of the invention
The error separation of Fig. 4 current-voltage conversion portion
The error separation of Fig. 5 Voltage-voltage convenor section
Specific embodiment
The present invention is specifically described in conjunction with specific embodiments as follows:
Block diagram of the invention is as shown in Fig. 2, firstly, current-to-voltage convertor acquires input current IiAnd it is converted into electricity
Signal is pressed, is allowed to meet the input requirements of converter；High-precision AD converter acquires the voltage and is input to embedded processing
In device, embeded processor handles voltage using filtering, error correction scheduling algorithm, synthesizes further according to set target
Resistance RxThe output for controlling D/A converter makes its export corresponding voltage signal, at the same by output equipment display voltage,
Electric current and resistance value；Finally, the voltage that D/A converter exports is converted to voltage output U by Voltage-voltage converterb。
For electric current-electricity in the circuit of current excitation breadboardin resistance value of the invention, in current-to-voltage converter
Pressure transformation ratio is K1, front-end A/D C digit N1, the reference voltage of ADC is U1, the current-voltage transformation of embeded processor reading
The voltage exported afterwards is D by the transformed numerical value of converter1；Rear end DAC digit is N2, the reference voltage of DAC is U2, electricity
The correspondence digital value of output voltage needed for piezo-electric pressure converter is D2, Voltage-voltage transformation ratio is K2, calculating simulation resistance Rx
Method it is as follows:
The digital value D obtained according to front-end A/D C1It exports with processor to the digital value D of rear end DAC2And the electricity of input
Flow valuve IiCarry out calculating simulation resistance value.Fig. 5 is that the output voltage of embeded processor connection in technical solution of the present invention drives electricity
Road, it comprises DAC and Voltage-voltage converter, the voltage of output voltage driving circuit final output is Ub, exporting electric current is
Ii, after being acquired by front-end A/D C, rear end controls output DAC digital signal value by setting resistance value, using embeded processor
D2, by exporting buffering drive circuit, to realize artifical resistance.
It mainly include input current-voltage conversion circuit offset voltage and imbalance by further analyzing circuit error
The influence of electric current and temperature drift, the influence of ADC and DAC transformed error, output voltage-voltage conversion circuit offset voltage and
The influence of offset current and temperature drift.The above error is mainly linearity error, it may be considered that is fitted by final calibration
To eliminate.Specific method is that processor receives the voltage value of converter input, further according to the control DA conversion of target resistance resistance value
The output of device makes it export voltage required for corresponding voltage signal control generates.By repeatedly inputting and multiple output valve
Adjustment, it is final to determine adjustment formula be fitted to adjusted value (for example, by using least square method).
But, even if being linearity error, but it is more due to error, and the error curve of integration is also very multiple
Miscellaneous, to accurately be fitted, data volume needs are very big, in consideration of it, the present invention also provides a kind of analysis of source of error and removal and intending
The method for closing the mode that combines to realize precise resistance value.
Wherein, input terminal includes the error of a sample resistance method current measurement circuit, establishes error separation such as Fig. 4
It is shown, if two input terminal offset currents are IB1And IB2, so-called offset current refers to the both ends of operational amplifier in perfect condition
For " void disconnected ", but in actual circuit, the positive-negative input end of operational amplifier has a small amount of electric current to flow into, this electric current is exactly to lack of proper care
Electric current, input offset voltage UIO, so-called offset voltage refers in the ideal situation herein, the positive negative input of operational amplifier
When the voltage at end is identical, output voltage is equal to 0, but in practice, operational amplifier must additionally be applied in an input terminal
Adding a small voltage just can make output voltage be equal to 0V, which is offset voltage, it should be pointed out that offset current
With offset voltage can by measuring acquisition in advance, so, lost being inputted using the preceding operational amplifier passed through to the ADC stage
The measured in advance for adjusting electric current and input offset voltage, can obtain IB1、IB2And UIO, from fig. 4, it can be seen that setting amplifier input
Holding voltage is respectively U+And U-, flow through resistance R1And R2Electric current be respectively I1And I2.By analyzing available following equation:
U+=(Ii-IB1)·Rref+UIO
U-=I1R1
I2=I1+IB2
U+=U-
It is available by above formula
Wherein U+For the voltage value at the first operational amplifier positive input terminal of current-voltage conversion portion, U-For electric current-
Voltage value at first operational amplifier negative input end of voltage conversion portion, the input current of input current type artifical resistance device
For Ii, resistance R1For the sampling resistor between the reverse input end and ground of the first operational amplifier of current-voltage conversion portion,
Resistance R2For the sampling resistor between the reverse input end and output end of the first operational amplifier of current-voltage conversion portion,
Resistance RrefThe high-precision fixed value electricity connected by the positive input of the first operational amplifier of current-voltage conversion portion
Resistance, voltage Uo' be current-voltage conversion portion the first operational amplifier output end voltage.
And if the first operational amplifier of current-voltage conversion portion handled as ideal operational amplifier,
The case where not considering offset voltage and offset current, then this luck first calculate amplifier output voltage values be
For output voltage values ideally.
So, there is the presence of operational amplifier offset voltage and offset current, lead to the first of current-voltage conversion portion
The actual output voltage of operational amplifier and the error of desired output voltage are
It can be obtained by being modified in embeded processor to the error to input current-voltage conversion circuit amendment
Cross to obtain artifical resistance value.
Meanwhile on the basis of above-mentioned error correction, further consider temperature drift to input current type artifical resistance device
Bring influences.
If input offset current IB1、IB2Temperature drift be respectively TCIB1And TCIB2, input offset voltage UIOTemperature drift
Moving is TCV, available since temperature drift bring error equation is
U+=(Ii-TCIB1ΔT)·Rref+TCVΔT
U-=I1R1
I2=I1+TCIB2ΔT
U+=U-
It is possible thereby to be calculated with temperature drift, the output voltage of the operational amplifier in ADC stage
Are as follows:
The ideally output voltage values of the first operational amplifier of current-voltage conversion portion are as follows:
So with offset voltage and offset current, since temperature drift leads to ADC stage operation amplifier
Error between the actual output voltage and desired output voltage of device are as follows:
The practical collected voltage of ADC is
By in embeded processor to actually measured Uo' be modified, to improve output artifical resistance precision.
Next, analyzing converter and DA transformed error
All there is transformed error in actually converter and D/A converter, be divided into static error and dynamic error.It generates quiet
The reason of state error, has, unstable, the null offset of amplifier of a reference source, internal resistance and pressure drop and electricity when analog switch is connected
Hinder the deviation etc. of resistance value in network.Dynamic error is then the additive error generated in the dynamic process of conversion, it is due to electricity
The influence of distribution parameter in road reaches everybody voltage signal caused by the time difference of decoding network output end.Usually conversion
Error minimum output voltage ULSBMultiple indicate, i.e.,
ΔUo=NULSB
Wherein, ULSBRefer to that ADC and DAC digital quantity lowest order is 1, remaining corresponding conversion voltage value when being 0, i.e.,
The wherein maximum conversion digit that n is ADC or DAC；
Voltage value U after being analyzed by ADC error, into after embeded processor, after actual correctiona' be
Wherein, D1It is exported after the ADC stage operational amplifier progress current-voltage transformation read for embeded processor
Voltage passes through the transformed numerical value of converter, N1For converter digit, U1For the reference voltage of converter.
ΔUOP11Error caused by input offset current and offset voltage；
TC11Error caused by Δ T- importation temperature drift；
NADCULSBADCTransformed error caused by converter；
NADCIt is determined according to actual measurement ADC error.
Further output par, c DAC error is analyzed, analysis principle and error Producing reason are the same as above-mentioned ADC rank
The error analysis of section is consistent.
ΔUDAC=NDAC ULSBDAC
Further to output voltage-voltage conversion portion error analysis, the fractional error illustraton of model is as shown in Figure 5
The error of available Voltage-voltage conversion portion output voltage is
ΔUOPPOutput par, c Voltage-voltage partially due to output voltage error caused by offset current and offset voltage,
I in above-mentioned formulaB1’、IB2’、UIO’、R1’、R2' be all parameter at output par, c second operational amplifier, meaning with it is defeated
It is corresponding to enter the parameter that partial arithmetic amplifier goes out, specially.
R1' be output par, c operational amplifier negative input and ground between sampling resistor
R2' input resistance that is connected by the positive input of output par, c operational amplifier
Rf' be output par, c operational amplifier positive input and output end between sampling resistor
UIO' be output par, c operational amplifier offset voltage
IB1' be output par, c operational amplifier positive input offset current
IB2' be output par, c operational amplifier negative input offset current
Temperature drift generate error expression be
TCPΔ T- output par, c Voltage-voltage conversion portion temperature drift bring output voltage error, it is each in above formula
Parameter is meant that parameter corresponding with importation in the similar expression of output par, c.
So as to obtain the expression formula after output voltage carries out error correction
D2For the correspondence digital value of output voltage needed for DAC stage voltage-electric pressure converter, N2For D/A converter digit, U2
For the reference voltage of D/A converter.
The further expression formula to final artifical resistance after error correction:
Wherein, current-voltage transformation ratio is K1, Voltage-voltage transformation ratio is K2。
Although preferred embodiments of the present invention have been described, it is created once a person skilled in the art knows basic
Property concept, then additional changes and modifications may be made to these embodiments.So it includes excellent that the following claims are intended to be interpreted as
It selects embodiment and falls into all change and modification of the scope of the invention.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (5)
1. a kind of input current type artifical resistance device, it is characterised in that: including current source, the current-voltage being sequentially connected in series
Converter, converter, processor, D/A converter and Voltage-voltage converter, wherein processor receives converter input
Voltage value makes it export corresponding voltage signal and passes through electric piezo-electric further according to the output of target resistance resistance value control D/A converter
Voltage required for pressure converter control generates；
The current-voltage converter includes the first operational amplifier, and positive input is connected with current source, is also connected with simultaneously
There is high-precision fixed value resistance Rref, reverse input end is connected between series connection the sampling resistor R1 and R2 connecting with output end
Tie point；Wherein, mode is calculated as follows for the amendment of artifical resistance value to carry out:
Wherein RxFor the resistor resistance value of required simulation, wherein UaIndicate input terminal voltage value, UbIndicate output end voltage value, input electricity
Stream is Ii, RrefBy the sample resistance resistance value that the first operational amplifier positive input connects in current-voltage converter；
Amendment for artifical resistance value, the case where considering the offset current and offset voltage of first operational amplifier
Under, the actual output voltage of the first operational amplifier and the error of desired output voltage are as follows:
Wherein, UIOFor the offset voltage of first operational amplifier, offset current IB1And IB2For first operation amplifier
The offset current of device forward direction, negative input, R1For the sampling resistor between the reverse input end and ground of the first operational amplifier,
R2For the sampling resistor between the reverse input end and output end of the first operational amplifier, RrefJust for the first operational amplifier
The high-precision fixed value resistance connected to input terminal,
Summarize in processor and is compensated by its error.
2. input current type artifical resistance device as claimed in claim 1, it is characterised in that: the amendment for artifical resistance value is also wanted
In the case where the temperature drift for considering first operational amplifier, the error of the first operational amplifier, and its error is existed
It is compensated in processor, the error calculation formula are as follows:
Input offset current IB1、IB2Temperature drift be respectively TCIB1And TCIB2, input offset voltage UIOTemperature drift is TCV,
TC11Error caused by Δ T- importation temperature drift, Δ T are temperature drift value.
3. input current type artifical resistance device as claimed in claim 2, it is characterised in that:
It is also contemplated that the transformed error of converter and D/A converter, formula are respectively as follows:
ΔUADC=NADCULSBADC；
ΔUDAC=NDACULSBDAC；
Wherein, Δ UADCFor transformed error caused by converter；ΔUDACFor transformed error caused by D/A converter；ULSBADC、
ULSBDACRespectively refer to converter, D/A converter input digital quantity lowest order is 1, corresponding conversion voltage when remaining is 0, i.e.,Wherein n1, n2 respectively indicate converter, D/A converter change data most
Big digit, UrefFor reference voltage；
NADCIt is determined according to actual measurement converter error, NDACIt is determined according to actual measurement D/A converter error.
4. input current type artifical resistance device as claimed in claim 3, it is characterised in that: it is also contemplated that second operational amplifier is lacked of proper care
Error caused by electric current and offset voltage, calculation are as follows:
Wherein, R1' be output par, c operational amplifier negative input and ground between sampling resistor；
R2' input resistance that is connected by the positive input of output par, c operational amplifier；
Rf' be output par, c operational amplifier positive input and output end between sampling resistor；
UIO' be output par, c operational amplifier offset voltage；
IB1' be output par, c operational amplifier positive input offset current；
IB2' be output par, c operational amplifier negative input offset current.
5. a kind of resistance control method of input current type artifical resistance device, it is characterised in that: using any one of claim 1-4
The current mode artifical resistance device is controlled its resistance and is carried out using the method that fitting and error concealment combine.
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| CN109507625A (en) * | 2018-11-09 | 2019-03-22 | 上海科梁信息工程股份有限公司 | The automatic calibrating method and terminal device of battery simulator |
| CN110618300A (en) * | 2019-09-18 | 2019-12-27 | 宿州市泰华仪表有限公司 | Circuit for simulating resistor |
| CN113687125A (en) * | 2020-05-18 | 2021-11-23 | 广州汽车集团股份有限公司 | Offset voltage correction method and system for operational amplifier in current detection circuit |
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