CN203465341U - High-common-mode-rejection battery pack voltage sampling circuit - Google Patents
High-common-mode-rejection battery pack voltage sampling circuit Download PDFInfo
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- CN203465341U CN203465341U CN201320385618.5U CN201320385618U CN203465341U CN 203465341 U CN203465341 U CN 203465341U CN 201320385618 U CN201320385618 U CN 201320385618U CN 203465341 U CN203465341 U CN 203465341U
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- voltage sampling
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Abstract
The utility model discloses a high-common-mode-rejection battery pack voltage sampling circuit which is used for collecting the voltage of any battery of a plurality of battery packs. The voltage sampling circuit comprises an operational amplifier (U1) and is characterized by further comprising a first resistor (RA1), an MOS tube (M1) and a second resistor (RA2), wherein one path of an in-phase input end of the operational amplifier (U1) is connected to the positive electrode of a collected battery through the first resistor (RA1), the other path of the in-phase input end of the operational amplifier (U1) is connected with the drain of the MOS tube (M1), a reverse-phase input end of the operational amplifier (U1) is connected to the negative electrode of the collected battery, an output end of the operational amplifier (U1) is connected with the gate of the MOS tube (M1), the source of the MOS tube (M1) is connected to the ground through the second resistor (RA2), and a connecting point of the source of the MOS tube (M1)and the second resistor (RA2) is used as an output end of the voltage sampling circuit. The voltage sampling circuit is high in voltage sampling accuracy.
Description
Technical field
The utility model relates to a kind of voltage sampling circuit for battery of high common mode inhibition, and it is mainly used in high-precision analog signals collecting, the application that especially multi-string battery management system and so on needs on a large scale, high-accuracy voltage gathers.
Background technology
Heavy-duty battery management system need to gather, process the single battery voltage in multi-string battery group, but along with every batteries position is different, the common mode voltage of every batteries both positive and negative polarity has very big difference, and along with battery charge state is different, even same batteries, the common mode voltage of its both positive and negative polarity can be great changes have taken place in the same time yet.And battery management system is very high to the voltage acquisition accuracy requirement of every batteries, therefore, need the voltage sampling circuit of high cmrr to meet application requirements.
As shown in Figure 1, the voltage sampling circuit that is applied to multi-string battery group in prior art is realized by electric resistance partial pressure, and the two ends that it is connected on tested battery B1 in multi-string battery group comprise resistance R 1A, R1B, R1C, R2A, R2B and R2C, operational amplifier U1, and reference voltage Vref; Wherein, the output end vo that the output terminal of operational amplifier U1 is voltage sampling circuit, there is following relation: R1A=R2A=24R in the resistance of each resistance, R1C=R2C=24R, R1B=R2B=R, R is unit resistance.If the equal perfect match of each resistance in circuit, when the common mode voltage of battery B1 has Δ V to change, operational amplifier U1 output remains the voltage sum of the tested battery B1 of Vbat+Vref(and reference voltage Vref) constant, only at the input end of operational amplifier U1, there is the variation of a Δ V/25, with this, realize the voltage acquisition to tested battery B1.If but while having any resistance not mate in circuit, such as resistance R 2A has 1% mismatch, can derive when battery B1 has common-mode voltage variation Δ V, the output voltage of operational amplifier U1 also has the variation of Δ V*0.96%, and common-mode rejection ratio is 40.35dB.And in actual applications, if the common mode voltage of two batteries differs 50V, due to resistance mismatch, will cause the measuring error of 480mV.
In sum, the voltage sampling circuit that is applied to multi-string battery group in above-mentioned prior art has the following disadvantages:
The first, be subject to the impact of resistor matching precision, the common-mode rejection ratio of above-mentioned voltage sampling circuit is difficult to improve, and great changes have taken place with common-mode voltage variation to cause voltage measurement error;
The second, the measuring error of above-mentioned voltage sampling circuit with tested battery the position in battery different and different, cannot guarantee the consistance to tested battery measurement, reduced the performance of battery management system;
The 3rd, in order to make performance reach requirement, the resistance in above-mentioned voltage sampling circuit usually needs adopt the calibration of very high degree of precision or trim, and this has increased production cost and chip area greatly.
Utility model content
Technical problem to be solved in the utility model, is just to provide the voltage sampling circuit of a kind of high acquisition precision, high common mode inhibition.
Solve the problems of the technologies described above, the technical method that the utility model adopts is as follows:
A kind of voltage sampling circuit for battery of high common mode inhibition, this voltage sampling circuit is for gathering the voltage of any one battery of multi-string battery group, it comprises operational amplifier, it is characterized in that: described voltage sampling circuit also comprises the first resistance, metal-oxide-semiconductor and the second resistance; The in-phase input end of described operational amplifier is leaded up to the first resistance and is connected to the positive pole that is gathered battery, another road is connected with the drain electrode of described metal-oxide-semiconductor, the inverting input of operational amplifier is connected to the negative pole that is gathered battery, output terminal is connected to the grid of metal-oxide-semiconductor, the source electrode of described metal-oxide-semiconductor is by the second resistance eutral grounding, and the tie point of itself and the second resistance is as the output terminal of voltage sampling circuit.
As the preferred implementation of the first resistance and the second resistance, the resistance of described the first resistance and the second resistance equates.
As a kind of improvement of the present utility model, described voltage sampling circuit also comprises the first switch, second switch and the 3rd resistance; The described positive pole that is gathered battery is connected with described the first resistance by the first switch, the tie point of this first switch and the first resistance is connected to the negative pole that is gathered battery by described second switch, the switch of described the first switch and second switch cycle alternation, and this switching frequency is higher than voltage sampling circuit to being gathered the sample frequency of cell voltage, and the in-phase input end of described operational amplifier is connected to by the 3rd resistance the positive pole that is gathered battery.
As a kind of embodiment of the present utility model, described the first switch and second switch are transistor, and they are subject to respectively the switching signal control work of single spin-echo.
Compared with prior art, the utlity model has following beneficial effect:
First, the utility model arranges operational amplifier and metal-oxide-semiconductor etc., it does not adopt resistance series connection dividing potential drop mode of the prior art, but adopted the mode of current delivery sampled signal, pass through operational amplification circuit, on a resistance, realize voltage to the conversion of electric current, on the second resistance, realize again electric current to the conversion of voltage, make the variation of common mode voltage on any resistance, not produce change in pressure drop, therefore can not exert an influence to the output voltage of circuit yet, it has solved the problem that resistance mismatch in traditional resistor dividing potential drop scheme affects common-mode rejection ratio, without extra cost, high precision and more high-tension voltage acquisition have just been realized.
Second, the utility model is provided with the offset cancellation circuit being comprised of the first switch and second switch, utilize in-phase input end that the switching of switch makes operational amplifier by the first resistance be alternately connected with the positive and negative electrode that is gathered battery, realize the elimination to the skew of operational amplifier and low-frequency noise, further improved the voltage acquisition precision of voltage sampling circuit.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail:
Fig. 1 is the circuit theory diagrams of voltage sampling circuit of the prior art;
Fig. 2 is the circuit theory diagrams of voltage sampling circuit of the present utility model.
Embodiment
As shown in Figure 2, the voltage sampling circuit for battery of high common mode inhibition of the present utility model is for gathering the voltage of any one battery of multi-string battery group, it comprises operational amplifier U1, the first resistance R A1, metal-oxide-semiconductor M1, the second resistance R A2, the first interrupteur SW 1, second switch SW2 and the 3rd resistance R B, wherein, the resistance of the first resistance R A1 and the second resistance R A2 equates, the first interrupteur SW 1 and second switch SW2 are transistor, and they are subject to respectively the switching signal control work of single spin-echo, the i.e. switch of the first interrupteur SW 1 and second switch SW2 cycle alternation, and this switching frequency higher than voltage sampling circuit to being gathered the sample frequency of cell voltage.The in-phase input end of operational amplifier U1 is divided into three tunnels, the first via of in-phase input end is connected to one end of the first resistance R A1, the other end of the first resistance R A1 is connected to by the first interrupteur SW 1 positive pole that is gathered battery, and by second switch SW2, be connected to the negative pole that is gathered battery, the second tunnel of in-phase input end is connected to by the 3rd resistance R B the positive pole that is gathered battery, the Third Road of in-phase input end is connected with the drain electrode of metal-oxide-semiconductor M1, the inverting input of operational amplifier U1 is connected to the negative pole that is gathered battery, output terminal is connected to the grid of metal-oxide-semiconductor M1, the source electrode of metal-oxide-semiconductor M1 is by the second resistance R A2 ground connection, and the tie point of itself and the second resistance R A2 is as the output terminal of voltage sampling circuit.
Principle of work of the present utility model is as follows:
The switch of above-mentioned the first interrupteur SW 1 and second switch SW2 cycle alternation, the in-phase input end that makes operational amplifier U1 by the first resistance R A1 be alternately connected with the positive and negative electrode that is gathered battery.At each voltage sampling circuit to being gathered in the sampling period of cell voltage: first, the first interrupteur SW 1 conducting, second switch SW2 disconnects, the first resistance R A1 is connected with the positive pole that is gathered battery, pressure drop on the second resistance R A2 is that in Vbat* (RA1+RB)/RA2(formula, Vbat represents to be gathered the voltage of battery, and RA1 represents the resistance of the first resistance R A1, RB represents the resistance of the 3rd resistance R B, and RA2 represents the resistance of the second resistance R A2); Then, second switch SW2 conducting, the first interrupteur SW 1 disconnects, and the pressure drop on the second resistance R A2 is Vbat*RB/RA2.The difference of the voltage in two cycles is Vbat*RA1/RA2=Vbat.Therefore, the variation of battery common mode voltage can't cause on the second resistance R A2 any change in pressure drop, therefore there is no the common mode inhibition problem in traditional structure.And by the switching in two cycles, the skew that amplifier causes or low-frequency noise (flicker noise) can be eliminated when voltage subtracts each other.
The utility model does not limit to and above-mentioned embodiment; according to foregoing; according to ordinary skill knowledge and the customary means of this area; do not departing under the above-mentioned basic fundamental thought of the utility model prerequisite; the utility model can also be made equivalent modifications, replacement or the change of other various ways; for example, the resistance of above-mentioned the first resistance R A1 and the second resistance R A2 also can need to form certain multiplying power relation according to the application of sample circuit, all drops among protection domain of the present utility model.
Claims (3)
1. the voltage sampling circuit for battery of a high common mode inhibition, this voltage sampling circuit is for gathering the voltage of any one battery of multi-string battery group, it comprises operational amplifier (U1), it is characterized in that: described voltage sampling circuit also comprises the first resistance (RA1), metal-oxide-semiconductor (M1) and the second resistance (RA2); The in-phase input end of described operational amplifier (U1) is leaded up to the first resistance (RA1) and is connected to the positive pole that is gathered battery, another road is connected with the drain electrode of described metal-oxide-semiconductor (M1), the inverting input of operational amplifier (U1) is connected to the negative pole that is gathered battery, output terminal is connected to the grid of metal-oxide-semiconductor (M1), the source electrode of described metal-oxide-semiconductor (M1) is by the second resistance (RA2) ground connection, and the tie point of itself and the second resistance (RA2) is as the output terminal of voltage sampling circuit;
Described voltage sampling circuit also comprises the first switch (SW1), second switch (SW2) and the 3rd resistance (RB); The described positive pole that is gathered battery is connected with described the first resistance (RA1) by the first switch (SW1), this first switch (SW1) is connected to by described second switch (SW2) negative pole that is gathered battery with the tie point of the first resistance (RA1), the switch of described the first switch (SW1) and second switch (SW2) cycle alternation, and this switching frequency is higher than voltage sampling circuit to being gathered the sample frequency of cell voltage, and the in-phase input end of described operational amplifier (U1) is connected to by the 3rd resistance (RB) positive pole that is gathered battery.
2. the voltage sampling circuit for battery of high common mode inhibition according to claim 1, is characterized in that: the resistance of described the first resistance (RA1) and the second resistance (RA2) equates.
3. the voltage sampling circuit for battery of high common mode inhibition according to claim 1 and 2, it is characterized in that: described the first switch (SW1) and second switch (SW2) are transistor, and they is subject to respectively the switching signal control work of single spin-echo.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320385618.5U CN203465341U (en) | 2013-06-28 | 2013-06-28 | High-common-mode-rejection battery pack voltage sampling circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320385618.5U CN203465341U (en) | 2013-06-28 | 2013-06-28 | High-common-mode-rejection battery pack voltage sampling circuit |
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| CN203465341U true CN203465341U (en) | 2014-03-05 |
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| CN201320385618.5U Withdrawn - After Issue CN203465341U (en) | 2013-06-28 | 2013-06-28 | High-common-mode-rejection battery pack voltage sampling circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103383407A (en) * | 2013-06-28 | 2013-11-06 | 广东电网公司电力科学研究院 | High-common-mode-rejection battery pack voltage sampling circuit |
| CN105978517A (en) * | 2016-06-16 | 2016-09-28 | 西安航天计量测试研究所 | Direct-current voltage amplifier capable of restraining high common-mode voltage |
-
2013
- 2013-06-28 CN CN201320385618.5U patent/CN203465341U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103383407A (en) * | 2013-06-28 | 2013-11-06 | 广东电网公司电力科学研究院 | High-common-mode-rejection battery pack voltage sampling circuit |
| CN103383407B (en) * | 2013-06-28 | 2015-07-22 | 广东电网公司电力科学研究院 | High-common-mode-rejection battery pack voltage sampling circuit |
| CN105978517A (en) * | 2016-06-16 | 2016-09-28 | 西安航天计量测试研究所 | Direct-current voltage amplifier capable of restraining high common-mode voltage |
| CN105978517B (en) * | 2016-06-16 | 2018-05-25 | 西安航天计量测试研究所 | A kind of DC voltage amplifier that can inhibit high common-mode voltage |
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Granted publication date: 20140305 Effective date of abandoning: 20150722 |
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