CN210123455U - Battery voltage sampling circuit and battery management system - Google Patents
Battery voltage sampling circuit and battery management system Download PDFInfo
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- CN210123455U CN210123455U CN201920337421.1U CN201920337421U CN210123455U CN 210123455 U CN210123455 U CN 210123455U CN 201920337421 U CN201920337421 U CN 201920337421U CN 210123455 U CN210123455 U CN 210123455U
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Abstract
The utility model discloses a battery voltage sampling circuit and battery management system, sampling circuit includes bleeder circuit, first inverting amplifier, diode, second inverting amplifier and sampling chip, first inverting amplifier includes the bias voltage unit, bleeder circuit is connected with first inverting amplifier's input, the negative pole of diode is connected with second inverting amplifier's output, the positive pole of diode is connected at the input of second inverting amplifier, the output and the sampling chip of second inverting amplifier are connected. The utility model discloses a bias voltage unit of first inverting amplifier falls into two intervals with the voltage of bleeder circuit output, therefore, the utility model discloses can shield 0V to the sampling range between the minimum voltage of battery for the utilization ratio of the AD sampling resource of sampling chip more increases, thereby makes the precision of voltage sampling promote. The utility model discloses can the wide application in battery voltage detection technical field.
Description
Technical Field
The utility model belongs to the technical field of battery voltage detection technique and specifically relates to a battery voltage sampling circuit and battery management system.
Background
The power battery is used as an energy storage medium of the new energy pure electric vehicle, and can provide energy for the driving motor system and also receive regenerative braking energy from the driving motor system. The driving motor system needs to detect the voltage value of the current power battery at all times as the input of the control system for finishing power output and energy recovery, the current commonly adopted method is to perform AD sampling after resistor voltage division, and the voltage range acquired by the scheme is from 0 to the highest voltage of the battery or from 0 to the highest voltage required to be acquired by the system on the whole.
The battery has an obvious characteristic that the battery can only work within a certain voltage range, for example, the lowest discharge voltage of a single lithium battery is 2.4V, and the highest charge voltage is 4.2V. However, the electric vehicle usually requires a plurality of batteries connected in series or in parallel to achieve the required voltage and current output capability, so the voltage grade of the power battery is generally higher. For example, if 100 batteries are connected in series, the voltage output range between two ends of the power battery is 240-420V. Assuming that the AD sampling voltage range of the main control chip is 0-3.3V, the 420V voltage needs to be reduced to 3.3V by means of resistance voltage division. Therefore, the voltage range of 0-3.3V corresponds to the voltage range of 0-420V, wherein 0-240V is not actually required to be acquired, but occupies 0-1.8857V of the 0-3.3V sampling voltage resource. Therefore, the effective AD sampling range is 1.8857-3.3V, the corresponding battery voltage is 240-420V, and the voltage difference is 180V. Therefore, the actual AD sampling range is only 1.857-3.3V, and the sampling range of 0-1.857V is completely wasted. This may result in a reduction in the accuracy of the voltage sampling.
In summary, the prior art has a problem that the utilization rate of the AD sampling resource is low, which results in low voltage sampling precision.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model aims to provide a: the utility model provides a battery voltage sampling circuit and battery management system to promote the utilization ratio of AD sampling resource, and under the condition of the same AD sampling resource, promote the precision of voltage sampling.
The utility model discloses the first technical scheme who takes is:
the utility model provides a battery voltage sampling circuit, includes bleeder circuit, first inverting amplifier, diode, second inverting amplifier and sampling chip, first inverting amplifier includes sixth resistance, seventh resistance, bias voltage unit, first operational amplifier, the first end of sixth resistance and the first end of seventh resistance all are connected with first operational amplifier's inverting input, the second end of seventh resistance and the negative pole of diode all are connected with first operational amplifier's output, the bias voltage unit is connected with first operational amplifier's normal phase input, bleeder circuit's output and sixth resistance's second end are connected, the anodal of diode is connected at the input of second inverting amplifier, the output of second inverting amplifier is connected with the AD input of sampling chip.
And the output end of the voltage division circuit is connected with the second end of the sixth resistor through the voltage follower.
Further, the voltage follower comprises a second operational amplifier and a third resistor, the third resistor is connected between a positive phase input end of the second operational amplifier and an output end of the voltage division circuit, and an output end of the second operational amplifier is connected with an inverted phase input end of the second operational amplifier.
Further, the voltage division circuit comprises a first resistor and a second resistor, the first resistor and the second resistor are connected with the battery pack in parallel when being installed, and the connection point of the first resistor and the second resistor forms the output end of the voltage division circuit.
Further, the second inverting amplifier comprises a third operational amplifier, an eighth resistor, a ninth resistor and a tenth resistor, wherein a first end of the eighth resistor is connected with the anode of the diode, a second end of the eighth resistor is respectively connected with a first end of the ninth resistor and an inverting input end of the third operational amplifier, a second end of the ninth resistor is connected with an output end of the third operational amplifier, and a non-inverting input end of the third operational amplifier is grounded through the tenth resistor.
Further, the bias voltage unit includes a fourth resistor and a fifth resistor, the fourth resistor and the fifth resistor are connected in series between the positive electrode of the first operating power supply and the ground, and a connection point of the fourth resistor and the fifth resistor is connected to the non-inverting input terminal of the first operational amplifier.
Further, the sampling circuit further comprises an isolation circuit, and the isolation circuit is arranged between the output end of the second inverting amplifier and the AD input end of the sampling chip.
Further, the isolation circuit is an optical coupling isolation circuit.
Further, the isolation circuit comprises an optical coupler, an eleventh resistor and a twelfth resistor, wherein the eleventh resistor is connected between the output end of the second inverting amplifier and the first input end of the optical coupler, the second input end of the optical coupler is grounded, the first output end of the optical coupler is connected to the positive pole of the second working power supply, the second output end of the optical coupler is grounded through the twelfth resistor, and the second output end of the optical coupler is connected with the AD input end of the sampling chip.
The utility model discloses the second technical scheme who takes is:
a battery management system comprises the battery voltage sampling circuit.
The utility model has the advantages that: the utility model discloses a set up the bias voltage unit and set up the diode between first inverting amplifier and second inverting amplifier in first inverting amplifier, segment the voltage of bleeder circuit input, the utility model discloses can shield 0V to the range between the minimum voltage of battery for the utilization ratio of the AD sampling resource of sampling chip more increases, thereby makes the precision of voltage sampling promote.
Drawings
Fig. 1 is a schematic diagram of a battery voltage sampling circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an isolation circuit according to an embodiment of the present invention.
Detailed Description
The invention is further described with reference to the drawings and the specific embodiments.
Referring to fig. 1, the present embodiment discloses a battery voltage sampling circuit, which includes a voltage dividing circuit 100, a first inverting amplifier 300, a diode D1, a second inverting amplifier 400 and a sampling chip 500, the first inverting amplifier 300 includes a sixth resistor R6, a seventh resistor R7, a bias voltage unit 301, a first operational amplifier U1B, a first end of the sixth resistor R6 and a first end of the seventh resistor R7 are both connected to the inverting input terminal of the first operational amplifier U1B, the second end of the seventh resistor R7 and the cathode of the diode D1 are both connected to the output terminal of the first operational amplifier U1B, the bias voltage unit 301 is connected to the non-inverting input of the first operational amplifier U1B, the output end of the voltage dividing circuit 100 is connected to the second end of the sixth resistor R6, the anode of the diode D1 is connected to the input end of the second inverting amplifier 400, and the output end of the second inverting amplifier 400 is connected to the sampling chip 500.
The voltage dividing circuit can be realized by adopting a common resistance voltage dividing circuit. As shown in fig. 1, the voltage divider circuit 100 includes a first resistor R1 and a second resistor R2, the first resistor R1 and the second resistor R2 are connected in parallel with the battery pack BAT when mounted, and a connection point of the first resistor R1 and the second resistor R2 constitutes an output terminal of the voltage divider circuit 100. The voltage division circuit is used for dividing the voltage of the battery pack, so that the sampling chip can process the divided voltage.
And the first inverting amplifier is used for inverting and amplifying the voltage output by the voltage dividing circuit, and simultaneously dividing the voltage of the point VC into two sections by the bias voltage provided by the bias voltage unit. It cooperates with diode D1 (which is a diode with a turn-on voltage of 0.7V) to make the voltage at point VC lower than the design value, and the voltage at point VE higher than-0.7V, so that diode D1 is turned off. Therefore, when the voltage at the point VC is lower than the design value, the voltage collected by the sampling chip is 0. Of course, the on-state voltage of the diode may be different according to the actual design, so the performance parameters of the components need to be considered during the design. In this embodiment, the voltage at the point refers to the voltage to ground at the point.
And a second inverting amplifier which functions to convert the voltage at the point VE into a positive voltage and output the positive voltage to the sampling chip, because a general sampling chip can only sample a positive voltage.
The sampling chip may be a dedicated analog-to-digital conversion chip, or may be a processor with an analog-to-digital conversion function, such as an FPGA, an ARM, or other chips. The AD sampling interface of the sampling chip generally adopts an input range of 0-3.3V. Certainly, the input range of some chips can be wider, such as 0-5V; the sampling range is narrower, such as 0-1.8V.
Referring to fig. 1, as a preferred embodiment, the voltage divider circuit 100 further includes a voltage follower 200, and the output terminal of the voltage divider circuit 100 is connected to the second terminal of the sixth resistor R6 through the voltage follower 200. The voltage follower 200 is connected to the positive VCC + and negative VCC-of the first operating power supply, respectively.
The voltage follower is additionally arranged, so that the input impedance of the point VB is infinite, the point VC is the same as the voltage of the point VB, the voltage of the point VB cannot be influenced by the sampling circuit, and the sampling precision is ensured.
Referring to fig. 1, as a preferred embodiment, the voltage follower 200 includes a second operational amplifier U1A and a third resistor R3, the third resistor R3 is connected between the non-inverting input terminal of the second operational amplifier U1A and the output terminal of the voltage dividing circuit 100, and the output terminal of the second operational amplifier U1A is connected to the inverting input terminal thereof. In the present embodiment, the first operational amplifier U1B and the second operational amplifier U1A can be implemented by using dual-channel operational amplifiers.
Referring to fig. 1, as a preferred embodiment, the second inverting amplifier 400 includes a third operational amplifier U2A, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10, a first end of the eighth resistor R8 is connected to the anode of the diode D1, a second end of the eighth resistor R8 is connected to a first end of the ninth resistor R9 and the inverting input terminal of the third operational amplifier U2A, respectively, a second end of the ninth resistor R9 is connected to the output terminal of the third operational amplifier U2A, and the non-inverting input terminal of the third operational amplifier U2A is connected to GND through the tenth resistor R10.
Referring to fig. 1, as a preferred embodiment, the bias voltage unit 301 includes a fourth resistor R4 and a fifth resistor R5, the fourth resistor R4 and the fifth resistor R5 are connected in series between the positive electrode VCC + of the first operating power supply and the ground GND, and a connection point of the fourth resistor R4 and the fifth resistor R5 is connected to the non-inverting input terminal of the first operational amplifier U1A.
As a preferred embodiment, the sampling circuit further comprises an isolation circuit, and the isolation circuit is arranged between the output end of the second inverting amplifier and the AD input end of the sampling chip.
The isolation circuit is additionally arranged, so that the high-voltage circuit and the low-voltage circuit can be isolated, and the high-voltage is prevented from entering the control part to damage the MCU of the automobile.
The isolation circuit may be an opto-coupler isolation circuit or a transformer isolation circuit.
As a preferred embodiment, the isolation circuit is an optical coupling isolation circuit. The optical coupling isolation circuit is small in size and low in cost.
Referring to fig. 2, as a preferred embodiment, the isolation circuit includes an optical coupler U3, an eleventh resistor R11 and a twelfth resistor R12, the eleventh resistor R11 is connected between the output end of the second inverting amplifier and the first input end of the optical coupler U3, the second input end of the optical coupler U3 is grounded to GND, the first output end of the optical coupler U3 is connected to the positive electrode VDD + of the second operating power supply, the second output end of the optical coupler U3 is grounded through the twelfth resistor R12, and the second output end of the optical coupler U3 is connected to the AD input end of the sampling chip.
The operation of the battery voltage sampling circuit will be described with reference to fig. 1.
The operating voltage range of the battery pack BAT is assumed to be 240-420V. In practical designs, the sampling voltage range may be slightly increased to account for some anomalies. For example, the range of the sampling voltage is designed to be 200-500V.
In fig. 1, the voltage dividing circuit 100 divides the voltage of the battery pack, wherein the voltage at the point VB is related to the voltages of the first resistor R1, the second resistor R2, and the point VA. As can be seen from the view of figure 1,in this embodiment, the designer can adjust the resistance values of the first resistor R1 and the second resistor R2 to make the maximum value of VB
Not greater than the first operating voltage. Thus, the device is provided withThe purpose of this is to ensure that the first inverting amplifier can operate properly. In this embodiment, the voltage at point VB is equal to the voltage at point VC under the action of the voltage follower. The first inverting amplifier is analyzed according to the virtual short and virtual break rules, and it can be known that the voltage at the point VE can be calculated by the voltage at the point VD, the voltage at the point VC, the sixth resistor R6 and the seventh resistor R7. Wherein the content of the first and second substances,
here, the bias voltage is provided at the point VD, and the voltage at the point VD is divided by the fourth resistor R4 and the fifth resistor R5. The voltage at point VC is divided into two intervals. During the design, when the voltage of a point VA is 0-200V, the voltage corresponding to a point VE is
When the voltage of the point VA is 200-500V, the voltage corresponding to the point VE is
Due to the unidirectional conductivity of the diode D1, when the voltage at the point VA is 0-200V, VD1 is turned off, and the voltage at the point VG is equal to the voltage at the point VF and equal to 0. When the voltage at the point VA is 200-500V, the voltage of the cathode of the diode D1 is less than-0.7V, therefore, the diode D1 is conducted, at this time,
assuming that the AD sampling input impedance of the sampling chip is infinite, the voltage at the point VG is equal to the voltage at the point VAD. Namely, through the selection of parameters of each component, when the voltage of the point VA is 200-500V, the corresponding value input to the sampling chip is 0-3.3V.
In the present embodiment, an exemplary design parameter is provided, where R1 ═ 62.5k Ω, R2 ═ 1k Ω, R3 ═ 3k Ω, R4 ═ 7k Ω, R5 ═ 1k Ω, R6 ═ 3k Ω, R7 ═ 3k Ω, R8 ═ 4.8k Ω, R9 ═ 3.3k Ω, R10 ═ 4.8k Ω, and VCC + ═ 10V, VCC ═ 10V.
The relationship between point VA and point VAD is shown in Table 1:
TABLE 1
| VA(V) | 0 | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 450 | 500 |
| VAD(V) | 0 | 0 | 0 | 0 | 0 | 0.55 | 1.1 | 1.65 | 2.2 | 2.75 | 3.3 |
As can be seen from table 1, the sampling voltage per 50V is 0.55V; in the conventional art, the sampling voltage is only 0.33V per 50V. Therefore, the embodiment meets the linearity, and utilizes the AD sampling resource of the sampling chip to the maximum extent, namely the effective voltage range of the sampling chip is improved, and the sampling precision is greatly improved compared with the prior art under the same chip condition.
It is to above mainly to the utility model discloses a resistance component structure, specific circuit parameter is selected like voltage sampling range parameter, resistance parameter, operational amplifier parameter, diode parameter according to actual design.
The embodiment discloses a battery management system, which comprises the battery voltage sampling circuit in the embodiment. The battery management system is used for managing the battery, and generally has a function of measuring the voltage of the battery, so as to prevent or avoid abnormal conditions such as overdischarge, overcharge and over-temperature of the battery. The battery management system generally includes a processor, a communication module, a voltage sampling circuit, a relay, and various sensors, such as a temperature sensor or a current sensor, and the like. The processor collects the voltage of the battery through the voltage sampling circuit; the processor is communicated with the automobile control system through a communication module, and the communication module CAN be a CAN communication module and the like; the processor collects relevant parameters of the automobile battery, such as temperature, current and the like, through the sensor.
While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined by the appended claims.
Claims (10)
1. A battery voltage sampling circuit, characterized by: including bleeder circuit, first inverting amplifier, diode, second inverting amplifier and sampling chip, first inverting amplifier includes sixth resistance, seventh resistance, bias voltage unit, first operational amplifier, the first end of sixth resistance and seventh resistance all is connected with first operational amplifier's inverting input, the second end of seventh resistance and the negative pole of diode all are connected with first operational amplifier's output, the bias voltage unit is connected with first operational amplifier's normal phase input, bleeder circuit's output and sixth resistance's second end are connected, the positive pole of diode is connected at the input of second inverting amplifier, the output of second inverting amplifier is connected with the AD input of sampling chip.
2. The battery voltage sampling circuit of claim 1, wherein: the voltage divider circuit further comprises a voltage follower, and the output end of the voltage divider circuit is connected with the second end of the sixth resistor through the voltage follower.
3. The battery voltage sampling circuit of claim 2, wherein: the voltage follower comprises a second operational amplifier and a third resistor, the third resistor is connected between a positive phase input end of the second operational amplifier and an output end of the voltage division circuit, and an output end of the second operational amplifier is connected with a self negative phase input end.
4. The battery voltage sampling circuit of claim 1, wherein: the voltage division circuit comprises a first resistor and a second resistor, the first resistor and the second resistor are connected with the battery pack in parallel when being installed, and the connection point of the first resistor and the second resistor forms the output end of the voltage division circuit.
5. The battery voltage sampling circuit of claim 1, wherein: the second inverting amplifier comprises a third operational amplifier, an eighth resistor, a ninth resistor and a tenth resistor, wherein the first end of the eighth resistor is connected with the anode of the diode, the second end of the eighth resistor is respectively connected with the first end of the ninth resistor and the inverting input end of the third operational amplifier, the second end of the ninth resistor is connected with the output end of the third operational amplifier, and the non-inverting input end of the third operational amplifier is grounded through the tenth resistor.
6. The battery voltage sampling circuit of claim 1, wherein: the bias voltage unit comprises a fourth resistor and a fifth resistor, the fourth resistor and the fifth resistor are connected between the positive electrode of the first working power supply and the ground in series, and the connection point of the fourth resistor and the fifth resistor is connected with the non-inverting input end of the first operational amplifier.
7. The battery voltage sampling circuit of claim 1, wherein: the sampling circuit further comprises an isolation circuit, and the isolation circuit is arranged between the output end of the second inverting amplifier and the AD input end of the sampling chip.
8. The battery voltage sampling circuit of claim 7, wherein: the isolation circuit is an optical coupling isolation circuit.
9. The battery voltage sampling circuit of claim 8, wherein: the isolation circuit comprises an optical coupler, an eleventh resistor and a twelfth resistor, wherein the eleventh resistor is connected between the output end of the second inverting amplifier and the first input end of the optical coupler, the second input end of the optical coupler is grounded, the first output end of the optical coupler is connected to the positive pole of the second working power supply, the second output end of the optical coupler is grounded through the twelfth resistor, and the second output end of the optical coupler is connected with the AD input end of the sampling chip.
10. A battery management system, characterized by: comprising a battery voltage sampling circuit according to any of claims 1-9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110018340A (en) * | 2019-03-15 | 2019-07-16 | 广州小鹏汽车科技有限公司 | A kind of battery voltage sampling circuit, method and battery management system |
| CN112092633A (en) * | 2020-09-22 | 2020-12-18 | 广州小鹏汽车科技有限公司 | Vehicle braking energy recovery method and device, vehicle and storage medium |
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2019
- 2019-03-15 CN CN201920337421.1U patent/CN210123455U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110018340A (en) * | 2019-03-15 | 2019-07-16 | 广州小鹏汽车科技有限公司 | A kind of battery voltage sampling circuit, method and battery management system |
| CN112092633A (en) * | 2020-09-22 | 2020-12-18 | 广州小鹏汽车科技有限公司 | Vehicle braking energy recovery method and device, vehicle and storage medium |
| CN112092633B (en) * | 2020-09-22 | 2022-07-08 | 广州小鹏汽车科技有限公司 | Vehicle braking energy recovery method and device, vehicle and storage medium |
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Assignee: ZHAOQING XIAOPENG AUTOMOBILE Co.,Ltd. Assignor: GUANGZHOU XPENG AUTOMOBILE TECHNOLOGY Co.,Ltd. Contract record no.: X2020440000168 Denomination of utility model: A battery voltage sampling circuit and battery management system Granted publication date: 20200303 License type: Common License Record date: 20210104 |