CN103267891A - Lossless current detecting circuit based on digital correction - Google Patents

Lossless current detecting circuit based on digital correction Download PDF

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Publication number
CN103267891A
CN103267891A CN2013102131775A CN201310213177A CN103267891A CN 103267891 A CN103267891 A CN 103267891A CN 2013102131775 A CN2013102131775 A CN 2013102131775A CN 201310213177 A CN201310213177 A CN 201310213177A CN 103267891 A CN103267891 A CN 103267891A
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main power
tube
integrator
circuit
detecting
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CN103267891B (en
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王斌
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Chongqing University
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Chongqing University
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Abstract

The invention discloses a lossless current detecting circuit based on digital correction. The lossless current detecting circuit comprises a main power tube VT1, a detecting tube VT2 used for detecting a working current, a PWA driving circuit, a direct current driving circuit and a digital correction circuit. The main power tube VT1 is connected with a drain electrode of the detecting tube VT2, a source electrode of the detecting tube VT2 is connected with the ground, the PWA driving circuit is connected with a grid electrode of the main power tube VT1, and the direct current driving circuit is connected with a grid electrode of the detecting tube VT2. The lossless current detecting circuit based on digital correction introduces variable gain adjustment of digital control on the basis of connecting an impedance RDS detecting current and carries out real-time on-line correction on deflection of a detected voltage value under different temperatures so as to complete high precision lossless detection of the current. The lossless current detecting circuit based on digital correction has the advantages that the digital correction circuit of gain continuous adjustment is provided, real-time correction of deflection of a connected impedance RDS detecting voltage value under different temperatures is carried out, and high precision lossless detection of the current is ensured.

Description

No loss current testing circuit based on figure adjustment
Technical field
The present invention relates to the improvement of electric current detecting method, particularly a kind of no loss current testing circuit based on figure adjustment.
Background technology
The DC/DC high frequency switch power progressively develops to the direction of low pressure, big electric current, high power density at present.Current detection circuit is key components of DC/DC transducer loop.All transducers all need to detect the input or output current, to realize overcurrent protection function.For the DC/DC transducer of Controlled in Current Mode and Based, current detection value and output feedback voltage value relatively produce the drive control signal of power tube, and the precision of current detecting directly influences the conducting dutycycle of power tube.No loss current detection method commonly used mainly contains two kinds.A kind of structure that adopts SENSEFET, being about to power MOSFET and SENSEFET parallel connection is integrated in the same chip, its channel width-over-length ratio is fixed value, the weak current that flows through SENSEFET is proportionate relationship with the heavy current that flows through MOSFET, namely can derive the current value of main power tube by detecting weak current.This method power consumption is little, the accuracy of detection height, but power tube must be selected specific SENSEFET, can not adapt to the demand of different voltage stresss and strength of current.Another kind method adopts the conduction impedance R of power MOSFET DSAs current sense resistor, derive current value by the drain-source voltage that detects MOSFET.Because R DSValue be generally m Ω level, very little by the power consumption of big electric current, realized the no loss current detection substantially.The shortcoming of this method maximum is that the accuracy of detection of electric current is low, because conduction impedance R DSValue along with the change of temperature bigger variation is arranged, constant conducting electric current can detect different drain-source voltage values under different temperature.In order to improve R DSThe precision that detects must be carried out temperature compensation to detecting magnitude of voltage, thereby be realized the high precision Non-Destructive Testing of electric current.
Summary of the invention
The objective of the invention is to design a kind of high precision Non-Destructive Testing circuit of electric current.This circuit is at power tube conduction impedance R DSIntroduce numerically controlled variable gain on the basis of detecting and regulate, carry out the real-time online correction to detecting the skew of magnitude of voltage under different temperatures, thereby finish the high precision Non-Destructive Testing of electric current.
The object of the present invention is achieved like this:
The no loss current testing circuit based on figure adjustment of the present invention's design comprises main power tube VT1, detector tube VT2, PWM driving circuit, dc drive circuit and digital correction circuit; Described main power tube VT1 is for the turn-on and turn-off of the main power circuit of control; Described detector tube VT2 is for detection of the working current of main power circuit; Described PWM driving circuit is used to main power tube VT1 that the driving signal is provided; Described dc drive circuit is used to detector tube VT2 that the direct voltage drive signal is provided; Described digital correction circuit is used for the detection magnitude of voltage of detector tube VT2 output is carried out the real-time online correction; The source electrode of described main power tube VT1 is connected with the drain electrode of detector tube VT2, the source ground of described detector tube VT2; Described PWM driving circuit is connected with the grid of main power tube VT1, and described dc drive circuit is connected with the grid of detector tube VT2.
Further, described digital correction circuit comprises integrator, DSP control chip and A/D converter; Described integrator is used for carrying out integration to detecting magnitude of voltage; Described DSP control chip is for the integral time of adjusting integrator; Described A/D converter is used for integrator output voltage is carried out analog to digital conversion; Described integrator is connected with the drain electrode of detector tube VT2, and described integrator is connected with the DSP control chip respectively with A/D converter.
Further, described integrator is for resetting integrator, and the described integrator of resetting comprises amplifier U1, resistance R 1, capacitor C 1 and trigger switch S1; Described trigger switch S1 is connected with the output port of DSP control chip, and the state that is used for the control integrator is reset; Be connected capacitor C 1 between the reverse input end series resistor R1 of described amplifier U1, the reverse input end of described amplifier U1 and output terminal; Described trigger switch S1 is connected between the reverse input end and output terminal of amplifier U1; The positive input of described amplifier U1 is connected with ground.
Further, described main power tube VT1, detector tube VT2 are the N-channel MOS FET of low conduction impedance.
Further, described main power tube VT1 works in high frequency turn-on and turn-off state; Described detector tube VT2 works in normally open by the 10V direct voltage drive; Described detector tube VT2 is equivalent to Low ESR resistance.
Further, described trigger switch S1 is by pulse signal f cDrive.
Further, described DSP control chip is 32 bit DSP chips.
The invention has the advantages that: the present invention proposes a kind of high precision Non-Destructive Testing circuit of electric current.This circuit is at conduction impedance R DSIntroduce numerically controlled variable gain on the basis of detecting and regulate, carry out the real-time online correction to detecting the skew of magnitude of voltage under different temperatures, thereby finish the high precision Non-Destructive Testing of electric current; Main power tube VT1 is driven by pwm signal, works in high frequency turn-on and turn-off state.The detector tube VT2 of low conduction impedance is connected in series as detecting MOSFET pipe and main power tube VT1, and detector tube VT2 is in normally open by the 10V direct voltage drive, is equivalent to a low-impedance resistance in series.Connect the integrator of to reset by the test side at the MOSFET pipe, carry out the variable gain adjusting to detecting voltage, compensated temperature variation to conduction impedance R DSInfluence.Namely along with the variation of temperature T, calculating can be reset working time of integrator; The startup of adjusting A/D converter in real time by software constantly arranges the length of integral time arbitrarily, and gain and being directly proportional integral time, thereby temperature compensation is finished in the continuous adjusting of realization voltage gain.Under constant working current, guarantee to detect output voltage and remain unchanged, be not subjected to the influence of variation of ambient temperature, finished the high precision Non-Destructive Testing to electric current.
Description of drawings
In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing, wherein:
Fig. 1 is the no loss current detection block diagram based on figure adjustment;
Fig. 2 is for resetting integrator;
Fig. 3 is the signal working timing figure.
Embodiment
Below with reference to accompanying drawing, the preferred embodiments of the present invention are described in detail; Should be appreciated that preferred embodiment only for the present invention is described, rather than in order to limit protection scope of the present invention.
Fig. 1 is the no loss current detection block diagram based on figure adjustment, Fig. 2 is for resetting integrator, Fig. 3 is the signal working timing figure, as shown in the figure: the no loss current testing circuit based on figure adjustment provided by the invention comprises main power tube VT1, detector tube VT2, PWM driving circuit, dc drive circuit and digital correction circuit; Described main power tube VT1 is for the turn-on and turn-off of the main power circuit of control; Described detector tube VT2 is for detection of the working current of main power circuit; Described PWM driving circuit is used to main power tube VT1 that the driving signal is provided; Described dc drive circuit is used to detector tube VT2 that the direct voltage drive signal is provided; Described digital correction circuit is used for the detection magnitude of voltage of detector tube VT2 output is carried out the real-time online correction; The source electrode of described main power tube VT1 is connected with the drain electrode of detector tube VT2, the source ground of described detector tube VT2; Described PWM driving circuit is connected with the grid of main power tube VT1, and described dc drive circuit is connected with the grid of detector tube VT2.Described digital correction circuit comprises integrator, DSP control chip and A/D converter; Described integrator is used for carrying out integration to detecting magnitude of voltage; Described DSP control chip is for the integral time of adjusting integrator; Described A/D converter is used for integrator output voltage is carried out analog to digital conversion; Described integrator is connected with the drain electrode of detector tube VT2, and described integrator is connected with the DSP control chip respectively with A/D converter.Described integrator is for resetting integrator, and the described integrator of resetting comprises amplifier U1, resistance R 1, capacitor C 1 and trigger switch S1; Described trigger switch S1 is connected with the output port of DSP control chip, and the state that is used for the control integrator is reset; Be connected capacitor C 1 between the reverse input end series resistor R1 of described amplifier U1, the reverse input end of described amplifier U1 and output terminal; Described trigger switch S1 is connected between the reverse input end and output terminal of amplifier U1; The positive input of described amplifier U1 is connected with ground.Described main power tube VT1, detector tube VT2 are the N-channel MOS FET of low conduction impedance.Described main power tube VT1 works in high frequency turn-on and turn-off state; Described detector tube VT2 works in normally open by the 10V direct voltage drive; Described detector tube VT2 is equivalent to Low ESR resistance.Described trigger switch S1 is by pulse signal f cDrive.Described DSP control chip is 32 bit DSP chips.
Principle of work and process based on the no loss current pick-up unit of figure adjustment that present embodiment provides are as follows:
Main power tube VT1 is driven by pwm signal, works in high frequency turn-on and turn-off state.The detector tube VT2 of low conduction impedance is connected in series as detecting MOSFET and main power tube VT1, and detector tube VT2 is in normally open by the 10V direct voltage drive, is equivalent to a low-impedance resistance in series.The conduction impedance of detector tube VT2 is m Ω level, and the power that consumes during conducting is very little, is similar to Non-Destructive Testing.But conduction impedance R DSTemperature influence is bigger, when temperature changes to 100 ℃ from 20 ℃, and R DSResistance variation about 50% is arranged usually, cause detecting voltage V cFluctuating range bigger, current detection accuracy is low.For compensates to conduction impedance R DSInfluence, the MOSFET test side need connect outside programmable gain amplifier, to detecting voltage V cCarrying out variable gain regulates.Existing chip generally provides the solution of fixed gain, can not realize the continuous adjusting that gains.Present embodiment has proposed the continuously adjustable solution of a kind of gain, and circuit is made of can reset integrator and A/D converter.The circuit of integrator as shown in Figure 2.
Integrator is by the signal f of DSP control chip output cReset, the startup of A/D converter is triggered by the control software of dsp chip.Detect voltage V cAfter being integrated to certain hour, A/D converter starts, the sample conversion of beginning integral voltage.An interior signal timing diagram of A/D sampling period is seen Fig. 3.
Fig. 3 has shown the work schedule of an interior signal of A/D change-over period, is divided into integrator replacement, integration and A/D conversion three phases.At reset phase integrator output V CtBe zero; After reset signal discharged, integrator began detecting voltage V cIntegration, voltage V CtLinear growth; Control software triggers A/D converter and starts working, and integration phase finishes, and obtains voltage V after A/D converts AdAs seen from Figure 3, integral time t length directly determined voltage V cGain amplifier, got by the circuit working principle:
V ct = - 1 R 1 · C 1 ∫ 0 t V c dτ + V C 1 ( 0 ) - - - ( 1 )
V in the formula C1(0) is the value of the terminal voltage of integration initial time capacitor C 1.
Initial time capacitor C 1 is in Reset Status:
V ct = - 1 R 1 · C 1 ∫ 0 t V c dτ = - V c · t R 1 · C 1 - - - ( 2 )
Voltage V then cGain amplifier be:
G = V ad V c = - t R 1 · C 1 - - - ( 3 )
I.e. gain and being directly proportional integral time arranges starting working constantly of A/D converter by software, can change the length of integral time arbitrarily, thereby temperature compensation is carried out in the continuous adjusting of realization voltage gain.
If T 0Be reference temperature, be generally 25 ℃ of normal temperature.When temperature raise to T, the gain coefficient of temperature compensation was:
G = 1 a ( T - T 0 ) - - - ( 4 )
A is constant in the formula, and is relevant with the concrete model of MOSFET.
By formula (3) and (4), get the integral time that DSP control software need set and be:
t = R 1 · C 1 a ( T - T 0 ) - - - ( 5 )
Namely along with the variation of temperature T, the working time that control software calculates integrator by formula (5), adjust the startup of A/D conversion in real time constantly.Under constant working current, guarantee to detect output voltage V like this AdRemain unchanged, be not acted upon by temperature changes, the high precision of having finished electric current detects.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (7)

1. based on the no loss current testing circuit of figure adjustment, it is characterized in that: comprise main power tube VT1, detector tube VT2, PWM driving circuit, dc drive circuit and digital correction circuit; Described main power tube VT1 is for the turn-on and turn-off of the main power circuit of control; Described detector tube VT2 is for detection of the working current of main power circuit; Described PWM driving circuit is used to main power tube VT1 that the driving signal is provided; Described dc drive circuit is used to detector tube VT2 that the direct voltage drive signal is provided; Described digital correction circuit is used for the detection magnitude of voltage of detector tube VT2 output is carried out the real-time online correction; The source electrode of described main power tube VT1 is connected with the drain electrode of detector tube VT2, the source ground of described detector tube VT2; Described PWM driving circuit is connected with the grid of main power tube VT1, and described dc drive circuit is connected with the grid of detector tube VT2.
2. the no loss current testing circuit based on figure adjustment according to claim 1, it is characterized in that: described digital correction circuit comprises integrator, DSP control chip and A/D converter; Described integrator is used for carrying out integration to detecting magnitude of voltage; Described DSP control chip is for the integral time of adjusting integrator; Described A/D converter is used for integrator output voltage is carried out analog to digital conversion; Described integrator is connected with the drain electrode of detector tube VT2, and described integrator is connected with the DSP control chip respectively with A/D converter.
3. the no loss current testing circuit based on figure adjustment according to claim 2 is characterized in that: described integrator is for resetting integrator, and the described integrator of resetting comprises amplifier U1, resistance R 1, capacitor C 1 and trigger switch S1; Described trigger switch S1 is connected with the output port of DSP control chip, and the state that is used for the control integrator is reset; Be connected capacitor C 1 between the reverse input end series resistor R1 of described amplifier U1, the reverse input end of described amplifier U1 and output terminal; Described trigger switch S1 is connected between the reverse input end and output terminal of amplifier U1; The positive input of described amplifier U1 is connected with ground.
4. the no loss current testing circuit based on figure adjustment according to claim 1 is characterized in that: described main power tube VT1, detector tube VT2 are the N-channel MOS FET of low conduction impedance.
5. the no loss current testing circuit based on figure adjustment according to claim 1, it is characterized in that: described main power tube VT1 works in high frequency turn-on and turn-off state; Described detector tube VT2 works in normally open by the 10V direct voltage drive; Described detector tube VT2 is equivalent to Low ESR resistance.
6. the no loss current testing circuit based on figure adjustment according to claim 3, it is characterized in that: described trigger switch S1 is by pulse signal f cDrive.
7. the no loss current testing circuit based on figure adjustment according to claim 2, it is characterized in that: described DSP control chip is 32 bit DSP chips.
CN201310213177.5A 2013-05-31 2013-05-31 Lossless current detecting circuit based on digital correction Expired - Fee Related CN103267891B (en)

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CN106374923A (en) * 2016-08-18 2017-02-01 芯海科技（深圳）股份有限公司 High-precision ADC reference voltage calibration system and calibration method
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CN110007133A (en) * 2019-04-16 2019-07-12 中国科学院上海应用物理研究所 A kind of digital alternating current-direct current flow sensor and electric current detecting method
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US9455631B2 (en) 2013-09-06 2016-09-27 Infineon Technologies Austria Ag Current estimation for a converter
CN104426366A (en) * 2013-09-06 2015-03-18 英飞凌科技奥地利有限公司 Current estimation for a converter
CN104426366B (en) * 2013-09-06 2017-11-21 英飞凌科技奥地利有限公司 current estimation for converter
CN108736867A (en) * 2013-11-14 2018-11-02 三菱电机株式会社 The driving circuit of thyristor
CN106374923B (en) * 2016-08-18 2020-03-17 芯海科技（深圳）股份有限公司 High-precision ADC reference voltage calibration system and calibration method
CN106374923A (en) * 2016-08-18 2017-02-01 芯海科技（深圳）股份有限公司 High-precision ADC reference voltage calibration system and calibration method
CN106685312A (en) * 2016-12-02 2017-05-17 许昌学院 Power drive protection device with negative temperature compensation
CN106685312B (en) * 2016-12-02 2022-12-16 许昌学院 Power driving protection device with negative temperature compensation
CN106645871A (en) * 2016-12-09 2017-05-10 圣邦微电子（北京）股份有限公司 Precision current measuring circuit based on MOSFET sensor
CN106645871B (en) * 2016-12-09 2019-05-21 圣邦微电子（北京）股份有限公司 Precision current measuring circuit based on MOSFET sensor
US10466296B2 (en) 2017-01-09 2019-11-05 Analog Devices Global Devices and methods for smart sensor application
US11119143B2 (en) 2017-01-09 2021-09-14 Analog Devices International Unlimited Company Devices and methods for smart sensor application
US11656269B2 (en) 2017-01-09 2023-05-23 Analog Devices International Unlimited Company Devices and methods for smart sensor application
CN110007133A (en) * 2019-04-16 2019-07-12 中国科学院上海应用物理研究所 A kind of digital alternating current-direct current flow sensor and electric current detecting method
CN110007133B (en) * 2019-04-16 2022-03-22 中国科学院上海应用物理研究所 Digital AC/DC current sensor and current detection method

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