CN116318137A - High-precision current/frequency conversion circuit - Google Patents
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- CN116318137A CN116318137A CN202310186925.9A CN202310186925A CN116318137A CN 116318137 A CN116318137 A CN 116318137A CN 202310186925 A CN202310186925 A CN 202310186925A CN 116318137 A CN116318137 A CN 116318137A
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- H—ELECTRICITY
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- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/06—Continuously compensating for, or preventing, undesired influence of physical parameters
- H03M1/08—Continuously compensating for, or preventing, undesired influence of physical parameters of noise
- H03M1/089—Continuously compensating for, or preventing, undesired influence of physical parameters of noise of temperature variations
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- H—ELECTRICITY
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- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
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Abstract
The invention relates to a high-precision current/frequency conversion circuit, which comprises: the device comprises an integrating circuit, a voltage threshold detection circuit A, a voltage threshold detection circuit B, a voltage reference source A, a voltage reference source B, a clock and reset circuit, a main control circuit, an analog switch, a constant current source A, a constant current source B, A/D conversion circuit and a temperature acquisition circuit. The invention realizes real-time detection of the output voltage of the integrating circuit and the working condition environment temperature by adding the A/D conversion circuit and the temperature acquisition circuit, realizes real-time accurate compensation of output pulse by the algorithm processing of the compensation processing unit, and improves the nonlinearity performance index of the current/frequency conversion circuit in the input-output full temperature range (-35 ℃ to 65 ℃) to within 50 ppm.
Description
Technical Field
The invention belongs to the analog-digital hybrid circuit technology, and particularly relates to a high-precision current/frequency conversion circuit.
Technical Field
Improving the accuracy and nonlinearity index of the inertial sensing unit is a key to improving the inertial navigation accuracy of the carrier. The requirement of a common high-precision inertial sensitive system on the precision index of the accelerometer is that10 -5 g, so the accuracy of the digital-to-analog converter needs to reach 10 -6 And g, the accuracy requirement of the system can be guaranteed. For the current signal output by the quartz accelerometer, the common detection modes mainly include an A/D conversion mode and an I/F conversion mode, wherein the A/D conversion mode needs to convert the current signal into a voltage signal, then the A/D converter is used for realizing the measurement of the voltage signal so as to further calculate the size of the input current signal, and in order to meet the high-precision detection requirement, a sigma-delta type high-precision A/D converter with more than 24 bits is generally needed. The I/F conversion scheme is implemented by controlling the bi-directional integration of the integrator capacitance based on the principle of capacitive charge balance. Different from the sampling detection mode of the A/D converter, the I/F converter can realize continuous detection of an input signal, the problem of original information loss is avoided, meanwhile, through continuous integration, the input noise signal can be subjected to smooth filtering to a certain extent, and the I/F conversion scheme has better anti-interference capability, so that the I/F conversion scheme is widely used in the aspect of accelerometer signal acquisition and conversion.
Because various performance parameters of the electronic components are easily influenced by the temperature of the working environment to change (commonly called temperature drift), the factor can greatly influence the input-output nonlinearity index of the current/frequency conversion circuit, and the environment adaptability of the circuit is reduced.
Disclosure of Invention
The invention solves the technical problems that: the high-precision current/frequency conversion circuit overcomes the defects of the prior art, can realize synchronous pulse output compensation, reduces response delay and improves the nonlinearity of input current and output frequency in a full temperature range.
The technical scheme of the invention is as follows:
a high precision current/frequency conversion circuit comprising: the device comprises an integrating circuit, a voltage threshold detection circuit A, a voltage threshold detection circuit B, a voltage reference source A, a voltage reference source B, a clock and reset circuit, a main control circuit, an analog switch, a constant current source A, a constant current source B, A/D conversion circuit and a temperature acquisition circuit;
the integrating circuit receives an external input current I in And analog switch feedbackConstant current, integrating circuit U1 to input current I in Integrating the difference value of the balance current, and outputting an integrated voltage Vout (t) to a voltage threshold detection circuit A, a voltage threshold detection circuit B and an A/D conversion circuit respectively; input current I in A positive current input or a negative current input;
under positive current input, the voltage threshold detection circuit A receives a first reference voltage output by the voltage reference source A, compares the output voltage of the integrating circuit under the positive current input with the first reference voltage to obtain a first square wave signal, and outputs the first square wave signal to the main control circuit;
under negative current input, the voltage threshold detection circuit B receives a second reference voltage output by the voltage reference source B, compares the output voltage of the integrating circuit under the negative input current with the second reference voltage to obtain a second square wave signal, and outputs the second square wave signal to the main control circuit;
the temperature acquisition circuit acquires the ambient temperature and outputs a temperature signal to the main control circuit;
the A/D conversion circuit receives the integral voltage for digital processing and outputs the integral voltage to the main control circuit;
the clock and reset circuit is used for outputting a clock signal and a reset signal to the master control circuit;
the main control circuit receives square wave signals output by the voltage threshold detection circuit A or the voltage threshold detection circuit B, and receives digital signals corresponding to the integral voltage output by the A/D conversion circuit and temperature signals output by the temperature acquisition circuit; compensating the frequency in the square wave signal to obtain a real-time pulse compensation quantity; according to the digital signal, temperature signal and real-time pulse compensation quantity corresponding to the integral voltage, using clock signal to obtain input current I in The corresponding ideal pulse signals are output outwards; the square wave signal includes: a first square wave signal and a second square wave signal;
the analog switch is controlled by the main control circuit, and selects the constant current source A or the constant current source B to output balance current and feed the balance current back to the integrating circuit;
the reset signal is used for controlling the main control circuit to output an ideal pulse signal outwards after the current/frequency conversion circuit is electrified and stably starts to work.
Preferably, the clock signal is a square wave signal, and the reset signal is a one-shot enable signal.
Preferably, the master circuit includes: a frequency extraction unit;
the frequency extraction unit outputs an enabling signal to the analog switch by utilizing the characteristic quantity of the square wave signal; the enabling signal is used for controlling the analog switch to output negative constant current as balance current to be fed back to the integrating circuit under positive current input; under negative current input, the control analog switch outputs a positive constant current as a balance current to be fed back to the integrating circuit.
Preferably, the current/frequency conversion circuit further includes: a constant current source B;
the negative constant current controlling the analog switch output is provided by a constant current source B.
Preferably, the current/frequency conversion circuit further includes: a constant current source A;
the positive constant current controlling the analog switch output is provided by a constant current source a.
Preferably, the master circuit further comprises: positive and negative pulse output unit and compensation control processing unit;
the frequency extraction unit obtains the actual output pulse quantity n before compensation by using the square wave signal f And output to the positive and negative pulse output unit and the compensation control processing unit;
the compensation control processing unit receives the digital signal and the temperature signal corresponding to the integrated voltage output by the A/D conversion circuit and the actual output pulse quantity n before compensation output by the frequency extraction unit f The method comprises the steps of carrying out a first treatment on the surface of the Generating a compensation enabling signal Enble according to the digital signal and the temperature signal corresponding to the integrated voltage and outputting the compensation enabling signal Enble to the positive and negative pulse output unit; and according to the actual output pulse quantity n before compensation f Generating a real-time pulse compensation quantity delta N fout (t) outputting to a positive and negative pulse output unit;
the positive and negative pulse output unit receives the real-time pulse compensation quantity delta N output by the compensation control processing unit fout (t) and a compensation enable signal Enble, receiving an actual output pulse quantity n before compensation output from the frequency extraction unit f The method comprises the steps of carrying out a first treatment on the surface of the Real-time pulse is generated by using a compensation enable signal EnbleCompensation quantity delta N of punching fout (t) the actual output pulse quantity n before compensation synchronously superimposed on the output of the frequency extraction unit f In (1) obtaining an input current I in The corresponding ideal pulse signal is output outwards.
Preferably, the reset signal and the clock signal are respectively output to the frequency extraction unit, the positive and negative pulse output unit, and the compensation control processing unit.
Preferably, the compensation control processing unit generates a real-time pulse compensation amount Δn fout The method of (t) is specifically as follows:
ΔN fout (t)＝N fout (t)-N f
N fout (t)＝λ·i(t)+ν 0
wherein [ n ] f1 … n fm ] T For the actual output pulse quantity, K, output by the frequency extraction unit 1 ～K m Is a discrete scale factor; b 1 ～b m Compensating longitudinal intercept for the fitted curve; lambda and v 0 Lambda is greater than K as the calibration coefficient of an ideal curve 1 ～K m Is v 0 Greater than b 1 ～b m Is the maximum value of (2); i (t) is a real-time current value estimated by the compensation control processing unit by utilizing a digital signal corresponding to the integral voltage output by the A/D conversion circuit; i in Is an input current value.
Compared with the prior art, the invention has the advantages that:
the invention realizes real-time detection of the output voltage of the integrating circuit and the working condition environment temperature by adding the A/D conversion circuit and the temperature acquisition circuit, realizes real-time accurate compensation of output pulse by the algorithm processing of the compensation processing unit, and improves the nonlinearity performance index of the current/frequency conversion circuit in the input-output full temperature range (-35 ℃ to 65 ℃) to within 50 ppm.
Drawings
FIG. 1 is a block diagram of a high precision current/frequency conversion circuit;
FIG. 2 is a timing diagram of a control waveform for the current/frequency conversion circuit;
fig. 3 is a schematic diagram of the pulse compensation method.
Detailed Description
The invention relates to a high-precision current/frequency conversion circuit, which can improve the output precision of the current/frequency conversion circuit. As shown in fig. 1, includes: the device comprises an integrating circuit, a voltage threshold detection circuit A, a voltage threshold detection circuit B, a voltage reference source A, a voltage reference source B, a clock and reset circuit, a main control circuit, an analog switch, a constant current source A, a constant current source B, A/D conversion circuit and a temperature acquisition circuit.
The integrating circuit receives an external input current I in And the balance current fed back by the analog switch, and the integrating circuit U1 inputs the current I in Integrating the difference value of the balance current, and outputting an integrated voltage Vout (t) to a voltage threshold detection circuit A, a voltage threshold detection circuit B and an A/D conversion circuit respectively; input current I in A positive current input or a negative current input;
under positive current input, the voltage threshold detection circuit A receives a first reference voltage output by the voltage reference source A, compares the output voltage of the integrating circuit under the positive current input with the first reference voltage to obtain a first square wave signal, and outputs the first square wave signal to the main control circuit;
under negative current input, the voltage threshold detection circuit B receives a second reference voltage output by the voltage reference source B, compares the output voltage of the integrating circuit under the negative input current with the second reference voltage to obtain a second square wave signal, and outputs the second square wave signal to the main control circuit; the first reference voltage output by the voltage reference source a and the second reference voltage output by the voltage reference source B are not equal.
The temperature acquisition circuit acquires the ambient temperature and outputs a temperature signal to the main control circuit;
the A/D conversion circuit receives the integral voltage for digital processing and outputs the integral voltage to the main control circuit;
the clock and reset circuit is used for outputting a clock signal and a reset signal to the master control circuit; the clock signal is a square wave signal, and the reset signal is a one-shot enabling signal.
The main control circuit receives square wave signals output by the voltage threshold detection circuit A or the voltage threshold detection circuit B, and the square wave signals comprise: a first square wave signal and a second square wave signal; receiving a digital signal corresponding to the integrated voltage output by the A/D conversion circuit and a temperature signal output by the temperature acquisition circuit; compensating the frequency in the square wave signal to obtain a real-time pulse compensation quantity; according to the digital signal, temperature signal and real-time pulse compensation quantity corresponding to the integral voltage, using clock signal to obtain input current I in The corresponding ideal pulse signals are output outwards;
the analog switch is controlled by the main control circuit, and selects the constant current source A or the constant current source B to output balance current and feed the balance current back to the integrating circuit;
the reset signal is used for controlling the main control circuit to output an ideal pulse signal outwards after the current/frequency conversion circuit is electrified and stably starts to work.
The main control circuit comprises: a frequency extraction unit;
the frequency extraction unit outputs an enabling signal to the analog switch by utilizing the characteristic quantity of the square wave signal; the enabling signal is used for controlling the analog switch to output negative constant current (provided by the constant current source B) as balance current to be fed back to the integrating circuit under positive current input; at negative current input, the control analog switch outputs a positive constant current (provided by constant current source a) as a balance current feedback to the integrating circuit.
The master control circuit further includes: positive and negative pulse output unit and compensation control processing unit;
the frequency extraction unit obtains the actual output pulse quantity n before compensation by using the square wave signal f And output to the positive and negative pulse output unit and the compensation control processing unit;
the reset signal and the clock signal are respectively output to the frequency extraction unit, the positive and negative pulse output unit and the compensation control processing unit.
The compensation control processing unit receives the digital signal and the temperature signal corresponding to the integrated voltage output by the A/D conversion circuit and the pre-compensation signal output by the frequency extraction unitActual output pulse quantity n f The method comprises the steps of carrying out a first treatment on the surface of the Generating a compensation enabling signal Enble according to the digital signal and the temperature signal corresponding to the integrated voltage and outputting the compensation enabling signal Enble to the positive and negative pulse output unit; and according to the actual output pulse quantity n before compensation f Generating a real-time pulse compensation quantity delta N fout (t) outputting to a positive and negative pulse output unit;
the positive and negative pulse output unit receives the real-time pulse compensation quantity delta N output by the compensation control processing unit fout (t) and a compensation enable signal Enble, receiving an actual output pulse quantity n before compensation output from the frequency extraction unit f The method comprises the steps of carrying out a first treatment on the surface of the The real-time pulse compensation quantity delta N is compensated by using the compensation enabling signal Enble fout (t) the actual output pulse quantity n before compensation synchronously superimposed on the output of the frequency extraction unit f In (1) obtaining an input current I in The corresponding ideal pulse signal is output outwards.
The master control circuit is an integrated IC chip with logic and time sequence control functions, such as FPGA, CPLD, DSP, an ARM-based microprocessor and the like. The main control circuit completes judgment and calculation processing on the output voltage data of the integrating circuit acquired by the A/D converter and the temperature data acquired by the temperature sensor through a compensation control processing unit realized by an internal program to obtain an output pulse compensation result. The positive and negative pulse output unit in the main control circuit is a functional module realized by a program and has the function of obtaining the output result delta N of the compensation control processing unit fout (t) effecting compensation of the output pulse quantity.
The compensation control processing unit generates a real-time pulse compensation quantity delta N fout The method of (t) is specifically as follows:
ΔN fout (t)＝N fout (t)-N f
N fout (t)＝λ·i(t)+ν 0
wherein [ n ] f1 … n fm ] T For the actual output pulse quantity, K, output by the frequency extraction unit 1 ～K m Is a discrete scale factor; b 1 ～b m Compensating longitudinal intercept for the fitted curve; lambda and v 0 Lambda is greater than K as the calibration coefficient of an ideal curve 1 ～K m Is v 0 Greater than b 1 ～b m Is the maximum value of (2); i (t) is a real-time current value estimated by the compensation control processing unit by utilizing a digital signal corresponding to the integral voltage output by the A/D conversion circuit; i in Is an input current value.
The integrating circuit realizes integration of input current; the main control circuit controls the access states of the constant current source A and the constant current source B through the analog switch, so that the dynamic balance control of the stored charge quantity in the integrating capacitor is realized; the clock and reset circuit provides clock and complex signals for the master control circuit; the power reference source A and the voltage reference source B respectively provide corresponding voltage references for the voltage threshold detection circuit A and the voltage threshold detection circuit B and provide state judgment level signals for the control implementation of the main control circuit; the invention realizes real-time detection of the output voltage of the integrating circuit and the working condition environment temperature by adding the A/D conversion circuit and the temperature acquisition circuit, realizes real-time accurate compensation of output pulse by the algorithm processing of the compensation processing unit, and improves the nonlinearity performance index of the current/frequency conversion circuit in the input-output full temperature range (-35 ℃ to 65 ℃) to within 50 ppm. In the system, the ratio of the output pulse quantity to the input current in unit time is generally called a scale factor K, the curves of the input current and the output pulse quantity are discretized, a plurality of groups of K coefficients can be obtained, and the nonlinearity index of the input current and the output frequency can be obtained by calculating the stability of the K coefficients.
The specific steps for output pulse compensation are as follows:
(1) The first step:
the principle of fitting the input and output data of the current/frequency conversion circuit by using a least square method at a constant temperature can be referred to as fig. 3, wherein a solid line is the actual measurement data (the current output by the quartz accelerometer) and a multi-section function curve can be obtained after fitting, and the fitted result can be represented by a function matrix as shown in formula (1).
Wherein n is f ＝[n f1 … n fm ] T The actual output pulse quantity (determined by the first square wave signal or the second square wave signal) obtained after the frequency extraction unit passes through the sampling window; k (K) 1 ～K m Fitting coefficients for a multi-segment curve, namely discrete scale factors; b 1 ～b m The compensated longitudinal intercept for the fitted curve.
(2) And a second step of:
the ideal current-pulse quantity function relation after fitting is set as shown in the formula (2).
N fout (t)＝λ·i(t)+ν 0 (2)
Wherein λ and ν 0 Lambda is greater than K as the calibration coefficient of an ideal curve 1 ～K m Is v 0 Greater than b 1 ～b m Is a maximum value of (a). At the same input current level, the ideal fit curve is always higher than the actual fit curve, as shown in fig. 3.
(3) And a third step of:
the voltage Vout (t) of the triangular wave output by the integrating circuit is acquired by the A/D acquisition module and converted into a digital signal to be sent to the compensation control processing unit. The compensation control processing unit detects the characteristic of a specific level voltage value of the triangular wave by utilizing a digital signal corresponding to the output voltage Vout (t) of the integrating circuit, and preliminarily estimates the size of an input current to obtain an estimated real-time current value i (t); substituting the real-time current value i (t) estimated by the A/D conversion circuit into the formula (2) to obtain the real-time pulse compensation quantity delta N fout (t)。
ΔN fout (t)＝N fout (t)-N f ＝[λ·i(t)+ν 0 )]-[K n ×i(t)+b n ]n∈[1,m]
(4) Fourth step:
the compensation control processing unit compensates the real-time pulse compensation quantity delta N obtained in the previous step fout (t) input to positive and negative pulse output unit, using clock signal and compensation amountThe ideal pulse signal is generated and output to the outside, and the specific implementation manner is that the pulse adjustment control is performed through the compensation enable signal Enble generated internally, and the adjustment manner is shown in fig. 2. Wherein I is in For the actual input current received by the integrating circuit, vout (t) is the output voltage value of the integrating circuit, the Enable signal is a compensation enable signal automatically generated in the positive and negative pulse output unit according to the compensation amount, and the compensation pulse delta N is generated in the signal fout (t) and the actual output pulse quantity n before compensation f Adjusted to accurately compensate pulse N fout (t) completing compensation control of the output pulse of the current-frequency conversion circuit. N (N) fout (t) is Fout+ or Fout-.
Although the present invention has been described in terms of the preferred embodiments, it is not intended to be limited to the embodiments, and any person skilled in the art can make any possible variations and modifications to the technical solution of the present invention by using the methods and technical matters disclosed above without departing from the spirit and scope of the present invention, so any simple modifications, equivalent variations and modifications to the embodiments described above according to the technical matters of the present invention are within the scope of the technical matters of the present invention. The embodiments of the present application and the technical features in the embodiments may be combined with each other without conflict.
What is not described in detail in the present specification is a well known technology to those skilled in the art.
Claims (8)
1. A high precision current/frequency conversion circuit, comprising: the device comprises an integrating circuit, a voltage threshold detection circuit A, a voltage threshold detection circuit B, a voltage reference source A, a voltage reference source B, a clock and reset circuit, a main control circuit, an analog switch, a constant current source A, a constant current source B, A/D conversion circuit and a temperature acquisition circuit;
the integrating circuit receives an external input current I in And the balance current fed back by the analog switch, and the integrating circuit U1 inputs the current I in Integrating the difference value between the voltage threshold detection circuit A and the balance current to output an integrated voltage Vout (t) to the voltage threshold detection circuit A and the voltage gateA limit detection circuit B and an A/D conversion circuit; input current I in A positive current input or a negative current input;
under positive current input, the voltage threshold detection circuit A receives a first reference voltage output by the voltage reference source A, compares the output voltage of the integrating circuit under the positive current input with the first reference voltage to obtain a first square wave signal, and outputs the first square wave signal to the main control circuit;
under negative current input, the voltage threshold detection circuit B receives a second reference voltage output by the voltage reference source B, compares the output voltage of the integrating circuit under the negative input current with the second reference voltage to obtain a second square wave signal, and outputs the second square wave signal to the main control circuit;
the temperature acquisition circuit acquires the ambient temperature and outputs a temperature signal to the main control circuit;
the A/D conversion circuit receives the integral voltage for digital processing and outputs the integral voltage to the main control circuit;
the clock and reset circuit is used for outputting a clock signal and a reset signal to the master control circuit;
the main control circuit receives square wave signals output by the voltage threshold detection circuit A or the voltage threshold detection circuit B, and receives digital signals corresponding to the integral voltage output by the A/D conversion circuit and temperature signals output by the temperature acquisition circuit; compensating the frequency in the square wave signal to obtain a real-time pulse compensation quantity; according to the digital signal, temperature signal and real-time pulse compensation quantity corresponding to the integral voltage, using clock signal to obtain input current I in The corresponding ideal pulse signals are output outwards; the square wave signal includes: a first square wave signal and a second square wave signal;
the analog switch is controlled by the main control circuit, and selects the constant current source A or the constant current source B to output balance current and feed the balance current back to the integrating circuit;
the reset signal is used for controlling the main control circuit to output an ideal pulse signal outwards after the current/frequency conversion circuit is electrified and stably starts to work.
2. The high precision current/frequency conversion circuit of claim 1, wherein the clock signal is a square wave signal and the reset signal is a one shot enable signal.
3. The high precision current/frequency conversion circuit according to claim 1, wherein the main control circuit comprises: a frequency extraction unit;
the frequency extraction unit outputs an enabling signal to the analog switch by utilizing the characteristic quantity of the square wave signal; the enabling signal is used for controlling the analog switch to output negative constant current as balance current to be fed back to the integrating circuit under positive current input; under negative current input, the control analog switch outputs a positive constant current as a balance current to be fed back to the integrating circuit.
4. A high precision current/frequency conversion circuit according to claim 3, further comprising: a constant current source B;
the negative constant current controlling the analog switch output is provided by a constant current source B.
5. The high precision current/frequency conversion circuit according to claim 4, further comprising: a constant current source A;
the positive constant current controlling the analog switch output is provided by a constant current source a.
6. A high precision current/frequency conversion circuit according to any one of claims 3 to 5, wherein the main control circuit further comprises: positive and negative pulse output unit and compensation control processing unit;
the frequency extraction unit obtains the actual output pulse quantity n before compensation by using the square wave signal f And output to the positive and negative pulse output unit and the compensation control processing unit;
the compensation control processing unit receives the digital signal and the temperature signal corresponding to the integrated voltage output by the A/D conversion circuit and the actual output pulse quantity n before compensation output by the frequency extraction unit f The method comprises the steps of carrying out a first treatment on the surface of the Generating a compensation enable signal Enble according to the digital signal and the temperature signal corresponding to the integrated voltage and outputting the compensation enable signal Enble to a positive electrodeA negative pulse output unit; and according to the actual output pulse quantity n before compensation f Generating a real-time pulse compensation quantity delta N fout (t) outputting to a positive and negative pulse output unit;
the positive and negative pulse output unit receives the real-time pulse compensation quantity delta N output by the compensation control processing unit fout (t) and a compensation enable signal Enble, receiving an actual output pulse quantity n before compensation output from the frequency extraction unit f The method comprises the steps of carrying out a first treatment on the surface of the The real-time pulse compensation quantity delta N is compensated by using the compensation enabling signal Enble fout (t) the actual output pulse quantity n before compensation synchronously superimposed on the output of the frequency extraction unit f In (1) obtaining an input current I in The corresponding ideal pulse signal is output outwards.
7. The high-precision current/frequency conversion circuit according to claim 6, wherein the reset signal and the clock signal are output to the frequency extraction unit, the positive-negative pulse output unit, and the compensation control processing unit, respectively.
8. The high-precision current/frequency conversion circuit according to claim 6, wherein the compensation control processing unit generates a real-time pulse compensation amount Δn fout The method of (t) is specifically as follows:
ΔN fout (t)＝N fout (t)-N f
N fout (t)＝λ·i(t)+ν 0
wherein [ n ] f1... n fm ] T For the actual output pulse quantity, K, output by the frequency extraction unit 1 ～K m Is a discrete scale factor; b 1 ～b m Compensating longitudinal intercept for the fitted curve; lambda and v 0 Lambda is greater than K as the calibration coefficient of an ideal curve 1 ～K m Is v 0 Greater than b 1 ～b m Is the maximum value of (2); i (t) is compensation controlThe processing unit utilizes the digital signal corresponding to the integral voltage output by the A/D conversion circuit to estimate the real-time current value; i in Is an input current value.
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