CN202189087U - Device for detecting direct current components in alternating current - Google Patents
Device for detecting direct current components in alternating current Download PDFInfo
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- CN202189087U CN202189087U CN2011203448825U CN201120344882U CN202189087U CN 202189087 U CN202189087 U CN 202189087U CN 2011203448825 U CN2011203448825 U CN 2011203448825U CN 201120344882 U CN201120344882 U CN 201120344882U CN 202189087 U CN202189087 U CN 202189087U
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Abstract
The utility model relates to the electricity field, in particular to a device for detecting direct current components in alternating current. A polarity separation circuit enables electrical signals output by an alternating current power supply to be detected to be divided into electrical signals of a positive semi-cycle and a negative semi-cycle, a polarity bucking circuit enables the electrical signals of the positive semi-cycle and the electrical signals of the negative semi-cycle output by the polarity separation circuit to be offset, and a direct current detection circuit detects the direct current components output by the polarity bucking circuit. By means of the embodiment, alternating current and direct current mixed signals are divided into signals of the positive semi-cycle and the negative semi-cycle and offset to obtain the direct current components, so that simple circuit structures can achieve high integration, and the device is reliable and stable in working and applicable to various severe environments.
Description
Technical field
The utility model relates to electricity field, detects the device of DC component in especially a kind of alternating current.
Background technology
DC component in power generation and the transmission network or DC magnetic biasing will cause directly that the network transformer noise increases, the vibration aggravation, even cause that transformer is local overheated and damage; If the DC component that adds when being incorporated into the power networks is a lot, total direct current is excessive, will cause the transformer core half-wave saturated in severe case; Cause that exciting curent sharply increases and waveform seriously distorts; The a large amount of higher hamonic waves that produce constitute serious the interference not only for the electrical equipment that is connected on the electrical network, also might make a large amount of reactive powers of transformer consumption cause voltage ripple of power network; Safe operation of power system is constituted a serious threat, must in addition strict monitoring.
Yet the direct current in DC magnetic biasing or the alternating current disturbs and but is prevalent in the various application systems at electric transmission network and terminal thereof.Such as; AC network nearby D.C. high voltage transmission disturbs down with strong magnetic storm, has the direct current of bigger flow through the transformer neutral line, Transformer Winding and transmission line of electricity, causes the DC magnetic biasing of main-transformer in the AC network; Be illustrated in figure 1 as the structural representation of alternating current converting system in the prior art; Transformer triangular form winding connects sinusoidal power frequency supply, and star winding connects load through electrical network, and direct offset current was through the star winding inflow transformer when electrical network was disturbed.In various electricity generation systems such as wind-force, sun power; Usually need to adopt single-phase or three-phase SPWM inverter changes unsettled interchange or direct current energy into meet the requirement that networks AC energy; Because the difference of semiconductor power device (like IGBT) switching characteristic; And the factors such as different delay of line signal, cause that DC component is difficult to avoid in the output AC voltage, promptly there is the magnetic bias problem.
Direct current disturbs AC network and the power-generation inversion system of not existing only in; In a lot of high-power using electricity systems; Particularly, also there is same DC component interference problem to handle in fields such as VFC, switch power amplifier and uninterrupted power source and alternating current steady voltage plugs.Such as, widely used submersible electric pump in the exploitation of oil-gas field process (Electrical Submers ible Pump, ESP are called for short electric submersible pump or oil-immersed pump) control is exactly very typical example.
In sum; Because DC component or DC magnetic biasing in the alternating current can cause very perturbation and destruction to electric power transfer and various application system under many circumstances; And thereby the existence of DC voltage is the basic reason that causes the asymmetric initiation of the voltage waveform of both forward and reverse directions magnetic bias, and how detecting DC voltage and electric current and proofreading and correct through appropriate circuit is the key problem in technology that suppresses magnetic bias.Therefore, how all can to face under all situations DC component less in the strong alternating current is carried out easy, problems of measurement accurately and reliably.
To the monitoring of DC component in the strong alternating current, all generally adopt various Hall elements, current transformer to measure indirectly at present, or the method for taking resistance parallel connection dividing potential drop or series connection sampling directly to measure.The characteristics of these methods are that the principle simple technique is ripe, but use a lot of limitation are arranged: current transformer and the big cost of Hall element volume are higher, are difficult to carry out integrated application.Electric resistance partial pressure or resistance sampling mode; For adapting to follow-up light current device level (such as circuit such as operational amplifier, comparer and A/D conversions; Withstand voltage usually in 5V-25V) designing requirement; When measuring being included in DC component in exchanging up to hundreds of High Voltages of going up kilovolt, the withstand voltage and reliability requirement of circuit will improve greatly; In addition; In the open air under the industrial and mineral measurement environment of extreme condition such as ESP down-hole; Measurement module also requirement can adapt to designing requirements such as high temperature, high voltage and strong jamming, and common operational amplifier is difficult to directly reply up to 150 degree high temperature and the high voltages more than hundreds of volt; Therefore, must carry out the high pressure isolation or whole input signal is done very significantly decay input AC during detection, this unavoidably exerts an influence to precision, the linearity and sensitivity of metering circuit again.
One Chinese patent application 99115990.x; The utility model name is called the method for eliminating DC component and the filter that utilizes this method to obtain; This utility model scheme has proposed a kind of method of how eliminating DC component, and it also is to use above-mentioned direct current detection mode of the prior art.One Chinese patent application numbers 200810060532.9, the utility model name is called a kind of circuit for eliminating DC component, and this utility model just discloses a kind of direct current and has eliminated circuit, does not do too much description for how measuring DC component.
The utility model content
The utility model embodiment provides the device that detects DC component in a kind of alternating current, and it is high to be used for solving prior art dc component detection circuit cost, and integrated level is low, the problem that reliability is not high.
The utility model embodiment provides the device that detects DC component in a kind of alternating current, comprises,
AC power to be measured, polarity separation circuit, polarity bucking circuit, dc detection circuit;
Said polarity separation circuit is separated into the electric signal of said AC power output to be measured the electric signal of positive half cycle and negative half period;
Said polarity bucking circuit is offset the electric signal of the positive half cycle of said polarity separation circuit output and the electric signal of negative half period;
Said dc detection circuit detects the DC component of said polarity bucking circuit output.
According to a further aspect that detects the DC component device in the described a kind of alternating current of the utility model embodiment; Said polarity separation circuit further comprises positive half cycle peak value acquisition cuicuit and negative half period peak value acquisition cuicuit; Said positive half cycle peak value acquisition cuicuit is used to obtain the peak value of said positive half cycle electric signal, and said negative half period peak value acquisition cuicuit is used to obtain the peak value of said negative half period electric signal.
According to another the further aspect that detects the DC component device in the described a kind of alternating current of the utility model embodiment; Said polarity separation circuit further comprises positive half cycle valley acquisition cuicuit and negative half period valley acquisition cuicuit; Said positive half cycle valley acquisition cuicuit is used to obtain the valley of said positive half cycle electric signal, and said negative half period valley acquisition cuicuit is used to obtain the valley of said negative half period electric signal.
According to another the further aspect that detects the DC component device in the described a kind of alternating current of the utility model embodiment; Said polarity separation circuit further comprises positive half cycle peak value acquisition cuicuit, positive half cycle valley acquisition cuicuit, negative half period peak value acquisition cuicuit, negative half period valley acquisition cuicuit, the circuit of averaging; According to said positive half cycle peak value acquisition cuicuit, positive half cycle valley acquisition cuicuit; The output of negative half period peak value acquisition cuicuit and negative half period valley acquisition cuicuit; Obtain the mean value of said positive half cycle electrical signal peak and valley sum respectively, and obtain the mean value of said negative half period electrical signal peak and valley sum.
Another further aspect according to detecting the DC component device in the described a kind of alternating current of the utility model embodiment also comprises operational amplifier, is connected between AC power to be measured and the polarity separation circuit, amplifies said ac signal to be measured.
Through the utility model embodiment, through the alternating current-direct current mixed signal being separated into the signal of positive half cycle and negative half period, and after offsetting; Obtain DC component; Can realize Highgrade integration with simple circuit configuration, and reliable operation, stable, be applicable under the multiple rugged surroundings.
Description of drawings
In order to be illustrated more clearly in the utility model embodiment or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiment of the utility model, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Shown in Figure 1 is the structural representation of alternating current converting system in the prior art;
Shown in Figure 2 is the method flow diagram that detects DC component in a kind of alternating current of the utility model embodiment;
Shown in Figure 3 is the structural representation that detects the DC component device in a kind of alternating current of the utility model embodiment;
Shown in Figure 4 is the circuit diagram of a kind of direct current offset bipolarity of the utility model embodiment testing circuit;
Shown in Figure 5 is the positive half cycle treatment circuit figure of the utility model embodiment alternating current-direct current mixed signal;
Fig. 6 a is depicted as the positive half cycle input of Fig. 5 oscillogram when Vdc＞Vm;
Fig. 6 b is depicted as the positive half cycle output waveform figure of Fig. 5 when Vdc＞Vm;
Fig. 7 a is depicted as the positive half cycle input of Fig. 5 oscillogram when Vdc＜Vm;
Fig. 7 b is depicted as the positive half cycle output waveform figure of Fig. 5 when Vdc＜Vm;
Fig. 7 c is depicted as the positive half cycle input of Fig. 5 oscillogram when Vdc=0;
Fig. 7 d is depicted as the positive half cycle output waveform figure of Fig. 5 when Vdc=0;
Fig. 8 a is depicted as the structural circuit figure of the utility model embodiment linear light lotus root;
Fig. 8 b is depicted as the utility model embodiment linear light lotus root inner structure circuit diagram;
The circuit diagram that exchanges the unipolarity testing circuit under disturbing for the utility model embodiment by force shown in Figure 9;
The circuit diagram that exchanges the bipolarity testing circuit under disturbing for the utility model embodiment by force shown in Figure 10;
Figure 11 a is depicted as the accurate half-wave rectifying circuit figure of the utility model embodiment;
Figure 11 b is depicted as the accurate peak value of the utility model embodiment, valley acquisition cuicuit figure;
Figure 11 c is depicted as the circuit diagram of the accurate emitter follower of the utility model embodiment;
Figure 11 d is depicted as the circuit diagram of the utility model embodiment totalizer;
Figure 11 e, Figure 11 f and Figure 11 g are depicted as the various subtraction circuit figure among the utility model embodiment;
Figure 12 a is the waveform input signal figure of Fig. 4 embodiment;
Figure 12 b is depicted as the output waveform figure of Fig. 4 embodiment.
Embodiment
To combine the accompanying drawing among the utility model embodiment below, the technical scheme among the utility model embodiment is carried out clear, intactly description, obviously, described embodiment only is the utility model part embodiment, rather than whole embodiment.Based on the embodiment in the utility model, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the utility model protection.
Be illustrated in figure 2 as the method flow diagram that detects DC component in a kind of alternating current of the utility model embodiment.
Comprise that step 201 is carried out polarity with ac signal to be measured and separated, and is divided into the electric signal of positive half cycle and negative half period.
In said step 201, ac signal to be measured is carried out polarity separate, the electric signal that is divided into positive half cycle and negative half period comprises, obtains the peak value of said positive half cycle electric signal and negative half period electric signal; In said step 202, also comprise, obtain the difference between positive half cycle electric signal of said peak value and the negative half period electrical signal peak.
In said step 201, ac signal to be measured is carried out polarity separate, the electric signal that is divided into positive half cycle and negative half period also comprises, obtains the valley of said positive half cycle electric signal and negative half period electric signal; In said step 202, also comprise, obtain the difference between positive half cycle electric signal of said peak value and the negative half period electric signal valley;
In said step 201; Ac signal to be measured is carried out polarity to be separated; The electric signal that is divided into positive half cycle and negative half period also comprises, obtains the peak value and the valley of said positive half cycle electric signal respectively, obtains the peak value and the valley of negative half period electric signal; Obtain the mean value of said positive half cycle electrical signal peak and valley sum, obtain the mean value of said negative half period electrical signal peak and valley sum; In said step 202, also comprise, calculate the difference between the mean value of mean value and negative half period electric signal of said positive half cycle electric signal.
In above-mentioned steps; Can be provided with to alternating current-direct current mixed signal bipolarity and handle respectively; One the tunnel just squints to direct current, and another road is moved to the direct current negative bias, and so no matter input signal is that which kind of skew all can the output DC component signal; And, just can judge that DC component is just to squint or negative bias moves according to the DC component signal of which output.
In the said step 203, can isolate the method for exporting through linear optical coupling and detect said DC component, perhaps can also adopt Hall element, current transformer to detect said DC component.
In above-mentioned steps 201, can also comprise that using operational amplifier to treat test cross stream electric signal amplifies, and can realize measurement and detection to feeble signal like this.
Pass through the foregoing description; Can realize the DC component in the ac signal is detected with simple structure, microminiaturized volume; Carry out subsequent processes according to this detected DC component then; Wherein these subsequent processes can be used processing mode of the prior art, and for example the subsequent processes in the background technology is not done any restriction for subsequent processes the utility model certainly; And need not to adopt in the prior art electric resistance partial pressure to decay, avoided of the influence of dividing potential drop attenuator circuit precision, the linearity and the sensitivity of measuring; Because the employed parts of the utility model are the parts of high stability, therefore more can adapt to abominable applied environments such as the above high voltage of high temperature and hundreds of volt, for example ESP down-hole industrial and mineral is measured; The circuit of the utility model is easy to make microminiaturized special integrated chip, substitutes the anti-interference isolation measurement that the part passive device is applied to realize under the strong communication environment DC component.
Be illustrated in figure 3 as the structural representation that detects the DC component device in a kind of alternating current of the utility model embodiment.
Said polarity separation circuit 302 is separated into the electric signal of said AC power output to be measured the electric signal of positive half cycle and negative half period;
Said polarity bucking circuit 303 is offset the electric signal of the positive half cycle of said polarity separation circuit 302 outputs and the electric signal of negative half period;
Said dc detection circuit 304 detects the DC component of said polarity bucking circuit 303 outputs.
Said polarity separation circuit 302 further comprises positive half cycle peak value acquisition cuicuit 3021 and negative half period peak value acquisition cuicuit 3022; Said positive half cycle peak value acquisition cuicuit 3021 is used to obtain the peak value of said positive half cycle electric signal, and said negative half period peak value acquisition cuicuit 3022 is used to obtain the peak value of said negative half period electric signal.
Said polarity separation circuit 302 further comprises positive half cycle valley acquisition cuicuit 3023 and negative half period valley acquisition cuicuit 3024; Said positive half cycle valley acquisition cuicuit 3023 is used to obtain the valley of said positive half cycle electric signal, and said negative half period valley acquisition cuicuit 3024 is used to obtain the valley of said negative half period electric signal.
Said polarity separation circuit 302 further comprises positive half cycle peak value acquisition cuicuit 3021; Positive half cycle valley acquisition cuicuit 3023; Negative half period peak value acquisition cuicuit 3022, negative half period valley acquisition cuicuit 3024, the circuit 3025 of averaging; According to said positive half cycle peak value acquisition cuicuit 3021, positive half cycle valley acquisition cuicuit 3023; The output of negative half period peak value acquisition cuicuit 3022 and negative half period valley acquisition cuicuit 3024 obtains the mean value of said positive half cycle electrical signal peak and valley sum respectively, and obtains the mean value of said negative half period electrical signal peak and valley sum.
Said polarity bucking circuit 303 can adopt transistor; The peak value of said positive half cycle electric signal and negative half period electric signal is connected respectively to transistorized emitter and base stage, when said transistor turns, exports the difference between positive half cycle electric signal of said peak value and the negative half period electrical signal peak;
The valley of said positive half cycle electric signal and negative half period electric signal is connected respectively to transistorized emitter and base stage, when said transistor turns, exports the difference between positive half cycle electric signal of said peak value and the negative half period electric signal valley;
The mean value of said positive half cycle electric signal and the mean value of negative half period electric signal are connected respectively to transistorized emitter and base stage, when said transistor turns, export the difference between the mean value of mean value and negative half period electric signal of said positive half cycle electric signal.
Above-mentioned transistor also can be realized by chip or parts that subtracter replacement etc. has a logical calculated ability.
Above-mentioned dc detection circuit 304 can be made up of the linear optical coupling spacing output circuit, perhaps can also adopt the Hall element, current transformer, isolation operational amplifier etc. of isolation to realize isolation measurement indirectly.When constituting by the linear optical coupling spacing output circuit; For the design of simplifying buffer circuit and improve its voltage endurance; Usually direct current output is split up into two-way output according to positive-negative polarity again, the one tunnel is positive polarity and another road is a negative polarity, and promptly output format is represented with the mode of " output amplitude (absolute value) " and " output polarity (positive and negative number) "; So that adopt diode to carry out high voltage protective, the unidirectional on state characteristic of simultaneous adaptation diode or triode; It is lower to isolate the general requirement of withstand voltage in output back; Follow-up circuit can synthesize the one-channel signal form that obtains having positive negative output with the two-way direct current offset that separates again; Export signal such as adopting subtracter to merge two-way, or negative bias is moved the output anti-phase, and then addition is merged into one tunnel output.
Said device can be handled respectively to alternating current-direct current mixed signal bipolarity in circuit 303 and 304; One the tunnel is directed against direct current just squints; Another road is moved to the direct current negative bias; So no matter input signal is that which kind of skew all can the output DC component signal; And according to being the DC component signal which has output, just can judge that DC component is just to squint or negative bias moves, promptly output format is represented with the mode of " output amplitude (absolute value) " and " output polarity (positive and negative number) ".General requirement of withstand voltage was lower after detection was accomplished, and can remerge two paths of signals, export signal such as adopting subtracter to merge two-way, or negative bias is moved the output anti-phase, and then addition is merged into one tunnel output.
Said device also comprises operational amplifier 305, is connected between AC power 301 to be measured and the polarity separation circuit 302, amplifies said ac signal to be measured, can realize measurement and detection to feeble signal like this.
Pass through the foregoing description; Can realize the DC component in the ac signal is detected with simple structure, microminiaturized volume; Utilize device of the prior art or parts that detected DC component is carried out subsequent processes then; For example the transformer in the background technology or electric submersible pump or oil-immersed pump etc. are not done any restriction for subsequent processes the utility model certainly; And need not to adopt in the prior art electric resistance partial pressure to decay, avoided of the influence of dividing potential drop attenuator circuit precision, the linearity and the sensitivity of measuring; Because the employed parts of the utility model are the parts of high stability, therefore more can adapt to abominable applied environments such as the above high voltage of high temperature and hundreds of volt, for example ESP down-hole industrial and mineral is measured; The circuit of the utility model is easy to make microminiaturized special integrated chip, substitutes the anti-interference isolation measurement that the part passive device is applied to realize under the strong communication environment DC component.
Be illustrated in figure 4 as the circuit diagram of a kind of direct current offset bipolarity of the utility model embodiment testing circuit.
The rectification circuit 401, peak value acquisition cuicuit 402, the valley acquisition cuicuit 403 that comprise the positive half cycle of alternating current-direct current mixed signal among the figure; The rectification circuit 404 of negative half period, peak value acquisition cuicuit 405, valley acquisition cuicuit 406; Penetrate with buffering output circuit 407, and the polarity bucking circuit of accomplishing by PNP transistor T A2, TB2 408, wherein; Pull-up resistor RA and RB get 100k, and the transistorized collector current-limiting resistance of PNP Rs is 0; The input AC amplitude is certain, but the direct current offset of stack is for changing at a slow speed and positive and negative symmetrical triangular ripple, to test under the relative situation about changing of AC and DC amplitude the linearity of electric circuit inspection and tracking effect.Wherein, The rectification circuit 401 of positive half cycle and the rectification circuit 404 of negative half period can but be not limited to unit such as adopting diode, various transistor or transwitch circuit, integrated operational amplifier or device is accomplished; Polarity bucking circuit 408 can but be not limited to unit such as adopting resistance sampling, various PNP or NPN transistor or transwitch circuit, integrated operational amplifier or device is accomplished, but its most preferred embodiment is implemented for the subtracter that adopts the PNP transistor and/or adopt operational amplifier to form.
Wherein, the positive half cycle treatment circuit of alternating current-direct current mixed signal is as shown in Figure 5, and diode DA1 is the half-wave rectification of positive half cycle, and DA1 and capacitor C A1 form positive half cycle peak value acquisition cuicuit, and it follows the tracks of the maximal value VAmax of the positive half cycle of input Vin; And the positive half cycle valley acquisition cuicuit of the common composition of diode D3, capacitor C A2, resistance R A1 and RA2; It gives CA2 slowly charging and equal to import the minimum value of the positive half cycle of Vin up to voltage VAmin through the D3 rapid discharge through RA1 and RA2, so this part follows the tracks of the valley VAmin of the positive half cycle of input Vin; The voltage difference at capacitor C A1 and CA2 two ends is VAmax-VAmin, passes through the weighting dividing potential drop of resistance R A1 and RA2, obtains VA to the voltage with reference to ground GND to do
VA=VAmin+ (VAmax-VAmin) * RA2/ (RA1+RA2) formula (1)
When RA1=RA2, with obtaining the weighted mean value that VA is VAmax and VAmin, promptly
VA=(VAmax+VAmin)/2 formula (2)
Because the symmetry of circuit also has similar result to handling the negative half period embodiment of circuit among Fig. 4, during RB1=RB2, be the weighted mean value of VBmax and VBmin to voltage promptly with reference to ground GND with obtaining VB:
VB=(VBmax+VBmin)/2 formula (3)
The hypothesis direct current offset is Vdc earlier, AC portion Vac=Vm*sin (wt), and then total is input as
Vin=Vdc+Vac=Vdc+Vm*sin (wt) formula (4)
Then the positive half cycle of Vin varies in size according to the amplitude of Vdc and Vm, can be divided into following two kinds of situation:
(1) the amplitude Vdc of direct current offset be on the occasion of and greater than exchanging amplitude Vm; Shown in Fig. 6 a, if the PN junction pressure drop of commutation diode DA1 and DA3 all is Vpn, then after positive half cycle rectification, peak value and the valley detection through Fig. 5; The waveform such as Fig. 6 b that detect output (annotate: for outstanding AC ripple disturbs; Here specially amplify output pulsation, and load RA is the very high input equivalent resistance of buffer circuit during practical application that the electric current that RA needs is very little; Fluctuation also can be little a lot), so we obtain:
Positive half cycle peak detection output VAmax=Vdc+Vm-Vpn formula (5)
Positive half cycle valley detection output VAmin=Vdc-Vm+Vpn formula (6)
Positive half cycle weighted mean output VA=(VAmax+VAmin)/2=Vdc formula (7)
And Vdc＞0, during Vdc＞Vm, not output of negative half period, that is:
Negative half period peak detection output VBmax=0 formula (8)
Negative half period valley detection output VBmin=0 formula (9)
Negative half period weighted mean output VB=(VBmax+VBmin)/2=0 formula (10)
(2) the amplitude Vdc of direct current offset be on the occasion of but Vdc＜Vm, shown in Fig. 7 a, then positive half cycle detects the waveform of output such as the VA among Fig. 7 b after detecting through rectification, peak value and the valley of Fig. 5, therefore obtains:
Positive half cycle peak detection output VAmax=Vdc+Vm-Vpn formula (11)
Positive half cycle valley detection output VAmin=Vpn formula (12)
Positive half cycle weighted mean output VA=(VAmax+VAmin)/2=(Vdc+Vm)/2 formula (13)
And during Vdc＜Vm, negative half period has output, for:
Negative half period peak detection output VBmax=Vm-Vdc-Vpn formula (14)
Negative half period valley detection output VBmin=Vpn formula (15)
Negative half period weighted mean output VB=(VBmax+VBmin)/2=(Vm-Vdc)/2 formula (16)
By top formula (7) and (10), and (13) and (16) be not difficult to find out, as long as input alternating current-direct current mixed signal Vin amplitude is enough big, makes that the PN junction of commutation diode can forward conduction, and then its pressure drop Vpn is to the not influence of direct current testing result; And, under two kinds of situation of Vdc＞0,,, be exactly direct current offset Vdc, that is: promptly through exchanging the output that obtains after the bucking circuit if the weighted mean value VA of positive half cycle is deducted the weighted mean value VB of negative half period
When Vdc＞0, Vdc=VA-VB formula (17)
In order to reduce of the influence of Fig. 4 subsequent process circuit to output VA, increase TA1 and TB1 conduct usually and penetrate, and the subtraction (bucking circuit) of Vdc＞0 o'clock formula (17) is realized by PNP transistor T B2 with buffer circuit, so have:
Vdc＞0 o'clock, VOA=VA1-VB2=VA-VB-2*Vbe ≈ VA-VB||=Vdc|| formula (18), wherein || and ..|| is for asking absolute value, and Vbe is the voltage of transistor BE knot, the about 0.6-0.7V of silicone tube usually, and germanium is 0.2-0.3V.
Though the embodiment of front o'clock obtains for the Vdc that just squints＞0 at the hypothesis direct current, when Vdc≤0,, the embodiment of VOB among Fig. 4 also there is similar result, that is: owing to the symmetry of signal waveform and circuit structure
Vdc≤0 o'clock, VOB=VB1-VA2=VB-VA-2*Vbe ≈ VB-VA=-Vdc=||Vdc|| formula (19)
And the subtraction (bucking circuit) of Vdc≤0 o'clock formula (20) is to be realized by the PNP transistor T A2 among Fig. 4.Be not difficult to find out, Vdc=0 when not having direct current offset, because the symmetry of waveform shown in Fig. 7 c and d, detects output VA=VB, so VOA=VOB=0, this obviously is top result's a special case.
Can know by above-mentioned discussion; It is only relevant with the size of DC component Vdc that direct current offset after interchange is offset detects the amplitude of exporting VOA and VOB; It doesn't matter with exchanging the amplitude Vm that disturbs; And the amplitude of Vdc is little more a lot of than Vm under a lot of situation, so will reduce greatly the requirement of withstand voltage of isolating output.The most simply be exactly to adopt linear light lotus root (such as HCNR200 or IL300) to isolate output in this case, shown in Fig. 8 a, its input/output relation is (wherein, CTR is the current delivery rate of light lotus root, and IF is the forward direction input current of light lotus root device):
Io=IF*CTR formula (20)
Vo=Ro/RF*CTR* (Via-Vib) formula (21)
A kind of high linearity light lotus root buffer circuit that we will adopt transistor and HCNR200 to realize in this patent is realized the output isolation, isolates the requirement of exporting with the input of simultaneous adaptation great dynamic range, high input equivalent resistance and high precision.Its internal circuit such as Fig. 8 b, the power Vcc 1 of its input end need not the additional isolation power supply, and is just passable as long as Vcc1 is not less than Vin, can directly link on the VAmax or VBmax that the peak value acquisition cuicuit exports; Wherein LED, PD1, PD2 all are integrated in HCNR200 inside, and photoelectric tube PD1 is consistent with the PD2 performance and power consumption is very little (uA rank), so the input end equivalent resistance is very big; As long as other circuit parameters are symmetrical, i.e. Rb1=Rb2, Re1=Re2, transistor T 1 and T2 get the pipe of same type, and then its input/output relation is in very big input range:
Vo ≈ Vin formula (22)
What particularly point out is; Though circuit that is proposed and measuring method are example in an embodiment with the large-signal; I.e. hypothesis input mixed signal Vin amplitude is enough big; Make that the PN junction of commutation diode can forward conduction, and all ignore the influence of commutator tube and emitter follower PN junction pressure drop Vbe (being about 0.3-0.7V), but its thinking is equally applicable to the situation of small-signal in a lot of places.As long as the withstand voltage and power supply power supply mode of suitable selector; The method that the circuit of the utility model can take much to improve precision for example can adopt various precision measurements based on operational amplifier, testing circuit, isolation amplifier etc.; Substitute the elements such as diode, triode and light lotus root isolating device of accomplishing corresponding operating in the foregoing circuit; Realize that high-accuracy half-wave rectification, peak detection, valley detection, totalizer, subtracter and the output of emitter follower buffering and isolation amplifier detect functions such as output, can improve the precision that tiny signal is measured greatly.Except these alternative circuit modules as shown in the figure; Only otherwise depart from the core concept of the utility model; Other alternative diode, triode realize that low-power consumption, high input impedance and high withstand voltage components and parts comprise metal-oxide half field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor; MOSFET), and field effect transistor (Junction FET, JFET); Insulated gate bipolar transistor (Insulated Gate Bipolar Transistor; Circuit component such as IGBT), and comprise alternative triode, operational amplifier or resistor network structure accomplish add, the various adc circuits of functions such as subtraction and measurement and CPU (single-chip microcomputer) circuit etc., list no longer one by one here.
Be illustrated in figure 9 as the circuit diagram that the utility model embodiment exchanges the unipolarity testing circuit under disturbing by force.
In this example, when strong interchange Vm＞Vdc, VAmin=0 and VBmin=0 are so valley value detection circuit CA2, DA3 and CB2 among Fig. 4, DB3 can save;
By formula (1): VA=VAmin+ (VAmax-VAmin) * RA2/ (RA1+RA2), make RA1=0 (short circuit) again, RA2=RA, and RB1=0 (short circuit), RB2=RB obtains VA=VAmax=Vdc+Vm-Vpn, and VB=VBmax=Vdc-Vm-Vpn is so have
VOA=VAmax-VBmax=2*Vdc formula (23)
Isolate output because the linear light lotus root circuit that adopts the utility model to provide is done, its equivalent resistance is very big, so penetrating with buffering of TA1 and TB1 also there is no need, omits in the present embodiment;
Direct current Vdc only need detect VOA when keeping the A end to be positive voltage, so transistor T A2 also can omit, only stays TB2 (being TB in this example);
DA1 wherein, DA2 realize that positive polarity separates rectification circuit, and CA realizes positive signal filtering, and the RA two ends obtain positive half cycle signal (output of can opening a way, thereby can save RA) here; In like manner, DB1, DB2 realize negative polarity separation rectification circuit, and CB realizes the negative polarity signal filtering, and the RB two ends obtain negative half-cycle signal;
RB and PNP transistor T B realize the polarity bucking circuit of alternating component jointly; Wherein thereby RB provides the very little desirable very big resistance of base bias current to TB; Obtain the amplitude of direct-flow shifted signal at the RL two ends, can obtain exporting signal through linear light lotus root isolation detection again.The circuit that the linear light lotus root can adopt Fig. 8 b to provide, the Vcc1 of its input end are connected to the A point and get final product, and need not extra insulating power supply power supply.Because the unidirectional on state characteristic of the be of triode TB knot and light lotus root input end diode just has the output signal when having only the skew monitoring to be output as positive polarity.
Can know by formula (23),, detect that DC component is depended in output and the influence that do not exchanged interference magnitude as long as when exchanging Vm＞Vdc; Exchange Interference Cancellation owing to adopt; This testing circuit has the amplification of twice to importing direct current offset, therefore exchanges to disturb to exist and has amplified flip-flop to be detected on the contrary, and this is very favourable to the applied environment as the measurement of ESP down-hole industrial and mineral; Still keep the ratio output in 1: 1 of Vo=Vin if need not amplify; Can come current limliting and dividing potential drop with resistance RS and RL in this case, thus play regulate or the function of compensation output (such as, to compensation or the rectification of ESP survey sensor resistance R s).
The circuit diagram that exchanges the bipolarity testing circuit under disturbing for the utility model embodiment by force shown in figure 10.
With above-mentioned embodiment illustrated in fig. 9 similar, except needs keep two-way interchange offset loop, when exchanging Vm＞Vdc by force, VAmin=0 and VBmin=0 so can do similar simplification and optimization, save valley value detection circuit CA2, DA3 and CB2, DB3.
Because TA1 and TA2 conducting is simultaneously got up the VA1 among Fig. 4 and VA2 short circuit here, and increased a pull-up resistor Ra3, so that it is more reliable to let TA2 o'clock end in VAB＞0, power consumption is lower.In like manner, can do same optimization, obtain another public output B TB2 and RB3.
Being connected between public output A, the B is that two-way linear light lotus root isolates output, obtains the monitoring result of positive and negative skew respectively, so that follow-up processing (compensation, amplification, A/D conversion, demonstration etc.) to be provided.The circuit that the linear light lotus root can adopt Fig. 8 b to provide, the Vcc1 of its input end are connected to the A point or the B point gets final product, and need not extra insulating power supply power supply.The introducing of diode DA and DB can improve the oppositely withstand voltage of circuit; Because the unidirectional on state characteristic of diode DA and DB; Need not to consider in this section to export the positive and negative polarity problem of signal, maybe should be used for accomplishing, such as adopting subtracter to merge two-way output signal but give follow-up circuit with the processing of polarity; Or negative bias moved the output anti-phase, and then addition is merged into one tunnel output.
The DC component that the utility model embodiment can also be applied to feeble signal detects; For example can adopt various precision measurements, testing circuit based on operational amplifier; Substitute the circuit components such as diode, triode and light lotus root isolating device of accomplishing corresponding operating in the foregoing circuit, realize the amplification and the detection of millivolt level (mV) tiny signal.
Accurate half-wave rectifying circuit figure shown in Figure 11 a, if commutation diode conduction voltage drop D1, D2 are Vpn=0.7V, the open loop differential mode enlargement factor of integrated transporting discharging is 500,000 times, for making diode D1 conducting, the clean input voltage of integrated transporting discharging should be so:
In like manner can estimate to making the D2 conducting, the required clean input voltage of integrated transporting discharging also has the equivalent amount level.Thus it is clear that,, just can change D1 and D2 duty, thereby reach the purpose of precision rectifying, alternative half-wave rectification diode as long as input voltage Ui makes the clean input voltage of integrated transporting discharging produce very small variation;
Accurate peak value shown in Figure 11 b, valley acquisition cuicuit figure; Can accomplish VAmax among the embodiment, VAmin and VBmax, VBmin obtains; With situation that foregoing circuit combines under, can obtain VAmax, VAmin and VBmax, the VBmin of positive half cycle of alternating current-direct current mixed signal and negative half period through this circuit;
The circuit diagram of the accurate emitter follower shown in Figure 11 c can be realized the output of U0=Ui buffering;
Be depicted as the circuit diagram of totalizer like Figure 11 d, totalizer Uo=-(U1+U2) can realize sum-average arithmetic (VAmax+VAmin)/2, (VBmax+VBmin)/2;
Various subtracters shown in Figure 11 e, Figure 11 f and Figure 11 g, Vo=Vi2-Vi1 can realize additive operation VOA=(VA-VB) or VOB=(VB-VA) when polarity is offset.
Can realize the purpose of the utility model except logic units such as above-mentioned totalizer, subtracters; Can also be through ADC sampling and digitizing; And realize through the algorithm that this patent proposes by microprocessor (MCU) and various digital signal processor (DSP) chip; Comprise and ask the amplitude of input peak value (maximal value), valley (minimum value), weighted mean value (smothing filtering), input signal to subtract each other (polarity counteracting) or the like; Wherein also comprise soft, the hardware realization code that possibly comprise, repeat no more at this.
Like Figure 12 a is the waveform input signal figure of Fig. 4 embodiment; Figure 12 b is depicted as the output waveform figure of Fig. 4 embodiment; Can find out that the detection output waveform is the same basically with the DC component of input stack; Also be to change at a slow speed and positive and negative symmetrical triangular ripple, explain that this patent circuit has the excellent precision and the linearity to the detection of direct current offset.The polarity of output is hypothesis A road for just, and the B road is for negative, gives follow-up circuit with the processing of polarity here and maybe should be used for accomplishing (such as adopting subtracter to merge two-way output signal, or negative bias is moved the output anti-phase, and then addition being merged into one the tunnel and exporting).
Through the utility model embodiment, through the alternating current-direct current mixed signal is divided into positive half cycle and negative half-cycle signal, carry out the counteracting of positive and negative half cycle signal then, just can in the signal of offsetting, obtain DC component so that the later stage with operations such as electric control; And just can realize above-mentioned purpose through device simple in structure, with low cost, advantages of small volume is convenient to be integrated in various device; The apparatus and method of the utility model are stable, reliability is high, are applicable to the work under the various extreme natural conditions.
Above-described embodiment; Purpose, technical scheme and beneficial effect to the utility model have carried out further explain, it should be understood that the above is merely the embodiment of the utility model; And be not used in the protection domain that limits the utility model; All within the spirit and principle of the utility model, any modification of being made, be equal to replacement, improvement etc., all should be included within the protection domain of the utility model.
Claims (5)
1. detect the device of DC component in the alternating current, it is characterized in that comprising,
AC power to be measured, polarity separation circuit, polarity bucking circuit, dc detection circuit;
Said polarity separation circuit is separated into the electric signal of said AC power output to be measured the electric signal of positive half cycle and negative half period;
Said polarity bucking circuit is offset the electric signal of the positive half cycle of said polarity separation circuit output and the electric signal of negative half period;
Said dc detection circuit detects the DC component of said polarity bucking circuit output.
2. detect the device of DC component in a kind of alternating current according to claim 1, it is characterized in that said polarity separation circuit further comprises positive half cycle peak value acquisition cuicuit and negative half period peak value acquisition cuicuit.
3. detect the device of DC component in a kind of alternating current according to claim 1, it is characterized in that said polarity separation circuit further comprises positive half cycle valley acquisition cuicuit and negative half period valley acquisition cuicuit.
4. detect the device of DC component in a kind of alternating current according to claim 1; It is characterized in that; Said polarity separation circuit further comprises positive half cycle peak value acquisition cuicuit, positive half cycle valley acquisition cuicuit, negative half period peak value acquisition cuicuit, negative half period valley acquisition cuicuit, the circuit of averaging; The said circuit of averaging is according to said positive half cycle peak value acquisition cuicuit, positive half cycle valley acquisition cuicuit; The output of negative half period peak value acquisition cuicuit and negative half period valley acquisition cuicuit obtains the mean value of said positive half cycle electrical signal peak and valley sum respectively, and obtains the mean value of said negative half period electrical signal peak and valley sum.
5. detect the device of DC component in a kind of alternating current according to claim 1, it is characterized in that, also comprise operational amplifier, be connected and amplify said ac signal to be measured between AC power to be measured and the polarity separation circuit.
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| CN2011203448825U CN202189087U (en) | 2011-09-14 | 2011-09-14 | Device for detecting direct current components in alternating current |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102435810A (en) * | 2011-09-14 | 2012-05-02 | 北京国基科技股份有限公司 | Method and device for detecting direct-current component in alternating current |
| CN104407208A (en) * | 2013-11-27 | 2015-03-11 | 南京世都科技有限公司 | System for relatively accurately measuring resistive current on basis of positive and negative transform of FFT (fast Fourier transform) by circuit energy |
| CN108024031A (en) * | 2016-10-28 | 2018-05-11 | 福州瑞芯微电子股份有限公司 | The direct current restoration methods and device of a kind of AC signal |
| CN113252965A (en) * | 2021-07-08 | 2021-08-13 | 深圳市海创光学有限公司 | Detection circuit, device and method |
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2011
- 2011-09-14 CN CN2011203448825U patent/CN202189087U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102435810A (en) * | 2011-09-14 | 2012-05-02 | 北京国基科技股份有限公司 | Method and device for detecting direct-current component in alternating current |
| CN104407208A (en) * | 2013-11-27 | 2015-03-11 | 南京世都科技有限公司 | System for relatively accurately measuring resistive current on basis of positive and negative transform of FFT (fast Fourier transform) by circuit energy |
| CN104407208B (en) * | 2013-11-27 | 2017-07-21 | 南京世都科技有限公司 | A kind of system of utilization circuit energy based on the relatively quasi- current in resistance property measurement of the positive inverse transformations of Fourier FFT |
| CN108024031A (en) * | 2016-10-28 | 2018-05-11 | 福州瑞芯微电子股份有限公司 | The direct current restoration methods and device of a kind of AC signal |
| CN108024031B (en) * | 2016-10-28 | 2019-10-29 | 福州瑞芯微电子股份有限公司 | A kind of the direct current restoration methods and device of AC signal |
| CN113252965A (en) * | 2021-07-08 | 2021-08-13 | 深圳市海创光学有限公司 | Detection circuit, device and method |
| CN113252965B (en) * | 2021-07-08 | 2021-09-21 | 深圳市海创光学有限公司 | Detection circuit, device and method |
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