CN108459275B - Battery cell voltage sampling circuit - Google Patents
Battery cell voltage sampling circuit Download PDFInfo
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- CN108459275B CN108459275B CN201810301847.1A CN201810301847A CN108459275B CN 108459275 B CN108459275 B CN 108459275B CN 201810301847 A CN201810301847 A CN 201810301847A CN 108459275 B CN108459275 B CN 108459275B
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- 238000005070 sampling Methods 0.000 title claims abstract description 118
- 238000006243 chemical reaction Methods 0.000 claims abstract description 57
- 238000002955 isolation Methods 0.000 claims abstract description 31
- 230000003750 conditioning effect Effects 0.000 claims abstract description 20
- 238000004891 communication Methods 0.000 claims description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims description 2
- 238000003491 array Methods 0.000 claims 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 4
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 description 11
- 238000000034 method Methods 0.000 description 10
- 238000001914 filtration Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
- G01R31/3835—Arrangements for monitoring battery or accumulator variables, e.g. SoC involving only voltage measurements
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Abstract
The invention discloses a battery cell voltage sampling circuit. Belonging to the technical field of battery management systems. The battery cell voltage sampling circuit mainly solves the problems that the existing battery cell voltage sampling circuit is poor in anti-interference performance and poor in stability and affects the consistency and the service life of a battery cell due to the fact that the battery is not isolated and the voltage division sampling resistor causes continuous leakage current. The main characteristics of the device are as follows: the device comprises a battery pack, a gating switch unit, a decoder unit, a main controller, a sampling conversion unit, a voltage conditioning unit, an analog-to-digital conversion unit and a data isolation unit; the gating switch unit and the sampling conversion unit are connected through Va and Vb buses; the voltage conditioning unit consists of a filter circuit and a negative feedback amplifying circuit, the negative feedback amplifying circuit is powered by an isolated power supply, and the power supply ground is connected with a signal with low sampling output voltage of the sampling conversion unit. The invention has the characteristics of good anti-interference performance, high safety, strong expandability and lower cost, and is mainly used for sampling and detecting a plurality of single battery cells of the lithium ion battery pack.
Description
Technical Field
The invention belongs to the technical field of battery management systems. And particularly relates to a lithium ion battery cell voltage sampling circuit.
Background
The lithium ion battery pack is formed by connecting a plurality of single battery cells in series and parallel, and the single battery cells can cause the performance reduction and the service life attenuation of the battery and even cause serious safety hazards such as smoke, fire, explosion and the like under the conditions of short circuit, overcharging, overdischarge, poor voltage consistency and the like. Therefore, the lithium ion battery pack must detect the voltage of each single cell in real time in the use process, so as to accurately control and protect the charge and discharge process of the battery pack.
The battery cell voltage sampling method of the battery pack commonly used in the market at present comprises two methods, wherein the first method adopts a common mode voltage division method to sample the battery cell voltage of the battery pack, the MCU of the battery main control chip can be grounded together without communication isolation, the sampling method has a simple circuit, but the voltage division sampling resistor causes continuous leakage current to the battery, and has adverse effects on the consistency and the service life of the battery cell, and meanwhile, the sampling circuit is not isolated, so that the anti-interference performance and the stability of the circuit are poor.
The second method is the most common method in the market today, and special sampling chips such as LTC6803 and LTC6804 are adopted, so that the integration level is high. However, the chips only support 12 strings of battery voltage collection at maximum, and more than 12 strings of chips are needed to be realized in cascade, however, the cost of the chips is high, and meanwhile, the expandability is poor.
Disclosure of Invention
The invention provides a battery cell voltage sampling circuit for solving the defects. By adopting the floating differential signal sampling circuit with isolation, each cell voltage in the battery pack is independently collected.
The technical scheme of the invention is as follows: the utility model provides a group battery electricity core voltage sampling circuit which characterized in that: the device comprises a battery pack, a gating switch unit, a decoder unit, a main controller, a sampling conversion unit, a voltage conditioning unit, an analog-to-digital conversion unit and a data isolation unit, wherein the battery pack is formed by connecting a plurality of battery cells in series; the gating switch unit and the sampling conversion unit are composed of an isolating switch array and a common anode diode array, and are connected through Va and Vb buses; the decoder unit is composed of a decoder array; the voltage conditioning unit consists of a filter circuit and a negative feedback amplifying circuit, wherein the negative feedback amplifying circuit is powered by an isolated power supply, and the power supply ground is connected with a signal with low sampling output voltage of the sampling conversion unit. The gating switch unit is used for realizing independent cell voltage sampling, wherein the isolating switch array is used for electric isolation, the positive and negative voltage sampling of each path of cell is gated, and the common anode diode array is used for controlling and selecting the conduction of the corresponding isolating switch. The sampling conversion unit controls the on and off of the isolating switch array through the high and low level of the control signal, and converts floating cell voltage sampling signals Va and Vb into differential signal pairs. The voltage conditioning unit is used for filtering signals, so that the collected voltage of the single battery cell is converted into a measurable voltage value, meanwhile, impedance matching is increased, zero drift and signal noise are suppressed, and the anti-interference capability of the sampling circuit is enhanced.
The positive electrode and the negative electrode of each battery core in the battery pack are respectively connected with the collector electrode of the output end of each corresponding isolating switch in the gating switch unit through sampling resistors respectively connected in series, and the emitter electrode of the other output end of each isolating switch is respectively connected with Va and Vb buses after being sorted according to odd numbers and even numbers; the anode of the input end of the isolating switch is connected with a power supply through a series current limiting resistor, and the cathode of the input end of the isolating switch is respectively connected with the anode end of the corresponding common anode diode array.
The decoder array in the decoder unit comprises two or more decoders; and an input signal of the decoder is connected with a GPIO port of the main controller, and an output signal end of the decoder is connected with a cathode of a diode in the gating switch unit to control the conduction of the diode. The decoder chip can easily realize parallel expansion, 2 pieces of the decoder chips can be cascaded to form a 16-channel decoder, and 1-16-channel battery core gating switches are controlled, so that up to 16-channel battery core voltage sampling is realized.
The battery pack in the technical solution of the invention consists of a plurality of monomer battery cells which are connected in series, and the battery pack comprises, but is not limited to, a lithium iron phosphate battery pack, a ternary NCM lithium battery pack or a ternary NCA lithium battery pack.
The isolating switches in the gating switch unit and the sampling conversion unit in the technical solution of the invention are optocouplers or optocoupler relays.
The decoder of the decoder unit described in the technical solution of the present invention is a 74-series decoder.
The main controller in the technical solution of the invention is MCU. The control signal output by the MCU is connected with the decoder unit and is used for selecting the decoder by a chip and sending the gating control signal, so that the independent control of the gating switch of the battery cell is realized. The sampling conversion signal output by the MCU is connected with the cathode of the input end of the sampling conversion unit and is used for controlling the on and off of the sampling conversion switch, so that the battery cell sampling signals Va and Vb are converted into differential signals. The MCU input signal is connected with the output of the digital isolation unit and is used for receiving the cell voltage sampling data.
The filter circuit in the voltage conditioning unit is an RC parallel circuit, and the negative feedback amplifying circuit is composed of a negative feedback operational amplifier.
The analog-to-digital conversion unit in the technical solution of the invention consists of a high-precision analog-to-digital converter, and comprises a high-speed SPI communication ADC, and outputs a data signal for high-speed SPI communication. The analog-to-digital conversion unit is used for converting the analog voltage signal into a high-speed digital signal.
The data isolation unit in the technical solution of the invention is composed of a data isolator, and an isolation output port of the data isolator is connected with a main controller. The digital isolation unit is used for communication isolation, and the isolated voltage data is sent to the main controller, so that the safety of the sampling circuit is enhanced, and the communication anti-interference capability of the main controller is improved.
According to the invention, by adopting the floating differential signal sampling circuit with isolation, the anti-interference performance and the safety of the circuit are enhanced, the leakage current problem is prevented, and meanwhile, the detection error is reduced and the voltage detection precision is improved by adopting the differential sampling signal. Furthermore, the circuit can flexibly collect each cell voltage in the battery pack independently, can configure corresponding sampling channel numbers according to different cell serial numbers, supports various battery packs with different cell serial numbers, and has strong expandability and lower cost.
Drawings
Fig. 1 is a circuit diagram of a battery cell voltage sampling circuit of the present invention.
Fig. 2 is a circuit diagram of battery cell voltage sampling according to embodiment 1 of the present invention.
Fig. 3 is a circuit diagram of battery cell voltage sampling according to embodiment 2 of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
As shown in fig. 1, the invention is a battery cell voltage sampling circuit, which comprises a battery cell U1, a gating switch unit U2, a decoder unit U3, a main controller U4, a sampling conversion unit U5, a voltage conditioning unit U6, an analog-to-digital conversion unit U7 and a data isolation unit U8, wherein the battery cell is formed by connecting a plurality of battery cells in series.
Example 1 is shown in fig. 2. The battery unit U1 is composed of n single battery cells connected in series, including but not limited to a lithium iron phosphate battery, a ternary (NCM, NCA) lithium battery. The positive electrode and the negative electrode of each battery cell in the battery pack U1 are connected with the collector electrode (c electrode) at the output end of the gating switch after passing through a sampling resistor connected in series, and the positive and negative ends of n battery cells in the battery pack U1 are in one-to-one correspondence with n+1 isolating switches in the gating switch unit U2.
The gating switch unit U2 is composed of an isolating switch array of K0-Kn and a common anode diode array, and the isolating switch comprises an optical coupler and an optical coupler relay. The collector (c pole) of the output end of each isolating switch array K0-Kn is connected with the positive electrode and the negative electrode of the battery cell in the battery pack U1 in a one-to-one correspondence manner, the emitter (e pole) of the output end is connected with a Va bus and a Vb bus respectively, the e pole of an even-bit isolating switch K2n (n is more than or equal to 0) is connected with the Va bus, and the e pole of an odd-bit isolating switch K2n+1 (n is more than or equal to 0) is connected with the Vb bus. Meanwhile, va and Vb buses are connected with the collector (c pole) of the output end of the switch array of the sampling conversion unit U5. The anode (+) of the input end at the other side of the isolating switches K0-Kn is connected with a resistor in series and then is connected with the VCC3V3 power supply end, the cathode (-) of the input end is connected with the anode end of the common anode diode array, and the on and off of the isolating switches are controlled by the high and low levels of the cathode (-). The gating switch unit U2 is used for realizing independent cell voltage sampling, wherein the isolating switch array is used for electric isolation, the positive and negative voltage sampling of each path of cells is gated, and the common anode diode array is used for controlling and selecting the conduction of the corresponding isolating switch.
The decoder unit U3 is composed of an array of decoders, including, but not limited to, 74 series decoders. An input signal of the decoder is connected with an MCU port of the main controller, and an output signal of the decoder is connected with a cathode of a common anode diode of the gating switch unit U2. The decoder chip can easily realize parallel expansion, 2 pieces of the decoder chips can be cascaded to form a 16-channel decoder, and 1-16-channel battery core gating switches are controlled, so that up to 16-channel battery core voltage sampling is realized.
The sampling conversion unit U5 is composed of an array of isolating switches, and the isolating switches comprise, but are not limited to, optocouplers and optocoupler relays. The switch control signals of the input ends of isolating switches KC 1-KC 4 in the sampling conversion unit U5 are connected with pins K1 and K2 of the main controller MCU, the collectors (C poles) of the output ends of KC1 and KC3 are connected with a switch array output Vb bus of the gating switch unit U2, and the emitter (e pole) of the output end is connected with a filter circuit positive pole VDD bus of the voltage conditioning unit U6. The collectors (C poles) of the KC2 and KC4 output ends are connected with a switch array output Va bus of the gating switch unit U2, and the emitter (e pole) of the output end is connected with a filter circuit cathode VSS bus of the voltage conditioning unit U6. The sampling conversion unit U5 controls the on and off of the isolating switch array through the high and low level of the control signal K1K2, and converts floating cell voltage sampling signals Va and Vb into VDD and VSS differential signal pairs.
The voltage conditioning unit U6 mainly comprises a filter circuit and a negative feedback amplifying circuit, wherein the filter circuit is an RC parallel circuit, and the negative feedback amplifying circuit mainly comprises a negative feedback operational amplifier, including but not limited to OP-07, LM358 and the like. The negative feedback amplifying circuit is powered by adopting an isolated 5V power supply VDD5V/VSS, wherein the power supply ground VSS is connected with a signal with low sampling output voltage in the sampling conversion unit U5. The negative feedback amplifying circuit amplifies and converts the floating cell sampling voltage VDD and VSS differential signals 1:1 into analog signals Vbn to be output, and the operational amplifier virtual short and virtual broken theorem indicates that the output Vbn=VDD-VSS. The voltage conditioning unit U6 is used for filtering signals, so that the collected voltage of the single battery cell is converted into a measurable voltage value Vbn, meanwhile, impedance matching is added, zero drift and signal noise are suppressed, and the anti-interference capability of the sampling circuit is enhanced.
The analog-to-digital conversion unit U7 is composed of a 12-bit high-precision analog-to-digital converter, including but not limited to a 12-bit high-speed SPI communication ADC. The input signal end of the analog-to-digital conversion unit U7 is connected with the operational amplifier output Vbn of the voltage conditioning unit U6, and a two-way data signal which is output as high-speed SPI communication is connected with the input of the digital isolation unit U8. The analog-to-digital conversion unit U7 is used for converting the analog voltage signal into a high-speed digital signal.
The digital isolation unit U8 consists of a double-channel data isolator, an input signal end of the digital isolation unit U8 is connected with an output end of the analog-to-digital conversion unit U7, an isolation output port of the digital isolation unit U8 is connected with the main controller MCU, positive and negative power of the input end of the digital isolation unit U8 is supplied with the isolated power supply VDD5V/VSS of the sampling module, and positive and negative power of the output end of the digital isolation unit U8 is supplied with VCC3V3/GND. The digital isolation unit U8 is used for communication isolation, and the isolated voltage data is sent to the main controller MCU, so that the safety of the sampling circuit is enhanced, and the communication anti-interference capability of the MCU is improved.
The main controller U4 is a core control part MCU of the system, and a control signal CS1A2A1A0 output by the MCU is connected with the decoder unit U3 and used for selecting a chip and sending a gating control signal, so that the independent control of the gating switch of the battery core is realized. The sampling conversion signal K1K2 output by the MCU is connected with the cathode of the input end of the sampling conversion unit U5 and is used for controlling the on and off of the sampling conversion switch, so that the battery cell sampling signals Va and Vb are converted into differential signals VDD and VSS. The MCU input signals SDA and CLK are connected with the output of the digital isolation unit U8 and are used for receiving the cell voltage sampling data.
In summary, the detection method of the present invention is summarized as that when the system starts to sample the voltage of the battery cell, the MCU firstly transmits the BTn gating control signal CS1A2A1A0 of the nth battery cell, the chip selects and enables the decoder, the decoder outputs the KBn low-level signal (KBn =0) of the corresponding channel, and the diodes connected with KBn in the diode array are turned on, so that the Kn-1 and Kn optocouplers in the gating switch array are turned on, and the positive and negative sampling voltages of the battery cell are transmitted to Va and Vb. At the same time, the MCU transmits the high and low level of the sampling conversion control signal K1K2 and controls the sampling conversion switch to be turned on and off, so that Va and Vb are converted into VDD and VSS differential signals (VDD-VSS= |Va-vb|). The differential signal is subjected to filtering conditioning, the battery cell voltage value Vbn is output after 1:1 operational amplification, the battery cell voltage value Vbn is converted into a digital voltage signal through an ADC analog-to-digital converter, the digital voltage signal is sent to an MCU through a digital isolator, the MCU reads and stores the voltage value parameter of the BTn, and meanwhile, the MCU clears a gating control signal CS1A2A1A0 and a conversion control signal K1K2 to prepare for the next sampling. And sequentially polling for one time, and sampling to obtain the voltage parameters of n electric cores BT 1-BTn in the battery pack.
The method comprises the following steps:
1. powering up the system, initializing an MCU, and starting up the voltage sampling of the battery cell after the startup self-test is completed;
2. firstly, the MCU transmits A1 st battery cell BT1 strobe control signal CS1A2A1 a0=0000, and a sampling transition control signal (odd-numbered circuit) k1k2=10;
3. decoder D1 in U3 is selected (CS 1 is the decoder chip select signal) and 74HC138 decoder translates a2a1a0=0000 to kb1=0, i.e., KB1 is pulled low to 0;
4. the diode connected with KB1 in the gating switch unit U2 is conducted, and then the isolating gating switches K0 and K1 are conducted, the negative voltage sample of BT1 is sent to Va, and the positive voltage sample of BT1 is sent to Vb;
5. k1k2=10, when KC1 and KC2 in the sampling conversion unit U5 are immediately turned on, vb is converted to VDD, va is converted to VSS, and vbt1=vb-va=vdd-VSS is the 1 st cell actual detection voltage value. Considering that VDD/VSS and Vb/Va are differential signal pairs with similar circuits, the circuit errors can be eliminated in the formula, and the detection precision of the VBT1 value is greatly improved;
6. the filtering circuit in the voltage conditioning unit U6 filters noise interference through RC parallel filtering, smoothes VDD and VSS differential signals, and outputs voltage signals Vb1=VDD-VSS after the differential signals VDD and VSS are amplified by the OP-07 operational amplifier 1:1, namely, vb1 is the 1 st battery cell sampling detection voltage value;
7. the analog-to-digital conversion unit U7 carries out A/D conversion on an input signal Vb1 through an ADS7886S analog-to-digital converter, and simultaneously, the ADS7886S calibrates the input signal through a reference voltage VREF, thereby improving the A/D conversion precision and outputting high-speed SPI signals ADC_CLK and ADC_SDO;
8. the data isolation unit U8 isolates the analog ground VSS of the battery cell sampling circuit from the digital ground GND of the MCU module, converts the high-speed SPI signals ADC_CLK and ADC_SDO into CLK and SDO, and sends the CLK and the SDO to the main control MCU;
9. the MCU reads the voltage value of the 1 st battery cell in the SDO through SPI communication, and data is stored. Simultaneously resetting the control signal and preparing for the next sampling;
10. the MCU sends A2 nd battery cell BT2 gating control signal CS1A2A1A 0=0000, a sampling conversion control signal (even number path) K1K2=01, a decoder D1 in U3 is selected, and a decoder translation output KB2=0, namely KB2 is pulled down to be 0;
11. the diode connected with KB2 in the gating switch unit U2 is conducted, and then the isolating gating switches K1 and K2 are conducted, the negative voltage sample of BT2 is sent to Vb, and the positive voltage sample of BT1 is sent to Va;
12. k1k2=01, KC3 and KC4 in the sampling conversion unit U5 are immediately turned on, va is converted into VDD, vb is converted into VSS, and the 1 st cell actual detection voltage vbt2=va-vb=vdd-VSS;
13. repeating the steps 6-9, the MCU obtains the voltage value of the 2 nd battery cell, and data is stored;
14. according to the MCU sending the corresponding gating control signal CS1A2A1A0, the odd circuit cell sampling reference step 2-9 and the even circuit cell sampling reference step 10-13, obtaining the cell voltage sampling detection value;
15. according to the steps, the MCU polls the battery cells in the battery pack sequentially, and then voltage detection values of 16 battery cells BT 1-BT 16 in the battery pack can be obtained.
The invention has the advantages that:
1. by adopting the floating differential signal sampling circuit with isolation, the anti-interference performance and the safety of the circuit are enhanced, and the leakage current problem is prevented;
2. the differential sampling signal is adopted, so that the detection error is reduced, and the voltage detection precision is improved; 3. each cell voltage in the battery pack can be flexibly and independently collected, the corresponding sampling channel number can be configured according to different cell serial numbers, various battery packs with different cell serial numbers are supported, and the battery pack has strong expandability and lower cost.
Example 2 is shown in fig. 3. The basic design concept of embodiment 1 is to slightly change the circuit to embodiment 2.
The sampling conversion control signal K1K2 of the MCU in embodiment 2 is changed to a circuit composed of the strobe control signal A0, and strobe control of the sampling conversion unit U5 can be also realized. The corresponding change part of the working principle of embodiment 2 is that when a=0 (odd-circuit cell sampling), the MOS transistor Q1 is turned off, KC1 and KC2 in the sampling conversion unit U5 are turned on, KC3 and KC4 are turned off, and the effect is the same as that of k1k2=10; when a=1 (even-circuit cell sampling), the MOS transistor Q1 is turned on, KC1 and KC2 in the sampling conversion unit U5 are turned off, and KC3 and KC4 are turned on, which has the same effect as k1k2=01. The other parts of the working principle of the embodiment 2 are the same as those of the embodiment 1, and will not be described again.
The above is only a preferred embodiment of the present invention, which includes and is not limited to the above examples. It will be appreciated that other modifications and variations, which may be directly derived or contemplated by those skilled in the art, are deemed to be within the scope of the present invention without departing from the essential concept thereof.
Claims (9)
1. The utility model provides a group battery electricity core voltage sampling circuit which characterized in that: the battery pack comprises a battery pack (U1), a gating switch unit (U2), a decoder unit (U3), a main controller (U4), a sampling conversion unit (U5), a voltage conditioning unit (U6), an analog-to-digital conversion unit (U7) and a data isolation unit (U8), wherein the battery pack is formed by connecting a plurality of battery cells in series; the gating switch unit (U2) and the sampling conversion unit (U5) are respectively composed of an isolating switch array and a common anode diode array, and are connected through Va and Vb buses; the decoder unit (U3) is composed of an array of decoders; the voltage conditioning unit (U6) consists of a filter circuit and a negative feedback amplifying circuit, the negative feedback amplifying circuit is powered by an isolated power supply, and the power supply ground is connected with a signal with low sampling output voltage of the sampling conversion unit (U5); the positive and negative electrodes of each battery core in the battery pack (U1) are connected with the collector electrode (c electrode) at the output end of the gating switch after passing through a sampling resistor connected in series, and the positive and negative ends of n battery cores in the battery pack (U1) are in one-to-one correspondence with n+1 isolating switches in the gating switch unit (U2); the gating switch unit (U2) consists of isolating switch arrays of K0-Kn and a common anode diode array, wherein collector electrodes (c poles) at output ends of the isolating switch arrays of K0-Kn are connected with positive and negative poles of electric cores in the battery pack (U1) in a one-to-one correspondence manner, emitter electrodes (e poles) at output ends of the isolating switch arrays are respectively connected with Va and Vb buses, e poles of even-numbered isolating switches of K2n are connected with the Va buses, and e poles of odd-numbered isolating switches of K2n+1 are connected with the Vb buses; the Va and Vb buses are connected with the collector (c pole) of the output end of the switch array of the sampling conversion unit (U5); the anodes (+) of the input ends at the other sides of the isolating switches K0-Kn are connected in series with a resistor and then connected to the VCC3V3 power supply end, the cathode (-) of the input end is connected to the anode end of the common anode diode array, and the on and off of the isolating switches are controlled by the high and low levels of the cathode (-); the gating switch unit (U2) is used for realizing independent cell voltage sampling, wherein the isolating switch array is used for electric isolation, the positive and negative electrode voltage sampling of each circuit of cells is gated, and the common anode diode array is used for controlling and selecting the conduction of the corresponding isolating switch; an input signal of the decoder unit (U3) is connected with a port of the main controller (U4), and an output signal of the decoder unit (U3) is connected with a cathode of a common anode diode of the gating switch unit (U2); the sampling conversion unit (U5) is composed of an isolating switch array, switch control signals of the input ends of isolating switches KC 1-KC 4 in the sampling conversion unit (U5) are connected with pins K1 and K2 of the main controller (U4), collectors (C poles) of the output ends of KC1 and KC3 are connected with a switch array output Vb bus of the gating switch unit (U2), an emitter (e pole) of the output end is connected with a filter circuit positive pole VDD bus of the voltage conditioning unit (U6), collectors (C poles) of the output ends of KC2 and KC4 are connected with a switch array output Va bus of the gating switch unit (U2), and an emitter (e pole) of the output end is connected with a filter circuit negative pole VSS bus of the voltage conditioning unit (U6); the sampling conversion unit (U5) controls the on and off of the isolating switch array through the high and low level of the control signal K1K2, and converts floating cell voltage sampling signals Va and Vb into VDD and VSS differential signal pairs; the output end of the sampling conversion unit (U5) is connected with the input end of the voltage conditioning unit (U6); the input signal end of the data isolation unit (U8) is connected with the output end of the analog-digital conversion unit (U7), and the port of the isolated output is connected with the main controller (U4); the control signal CS1A2A1A0 output by the main controller (U4) is connected with the decoder unit (U3) and is used for selecting the decoder and transmitting the gating control signal; the sampling conversion signal K1K2 output by the main controller (U4) is connected with the cathode of the input end of the sampling conversion unit (U5) and is used for controlling the on and off of the sampling conversion switch, so that the battery cell sampling signals Va and Vb are converted into differential signals VDD and VSS.
2. The battery cell voltage sampling circuit of claim 1, wherein: the decoder array in the decoder unit (U3) comprises two or more decoders.
3. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the battery pack (U1) includes, but is not limited to, a lithium iron phosphate battery pack, a ternary NCM lithium battery pack or a ternary NCA lithium battery pack.
4. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the isolating switches in the gating switch unit (U2) and the sampling conversion unit (U5) are optocouplers or optocoupler relays.
5. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the decoder of the decoder unit (U3) is a 74-series decoder.
6. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the main controller (U4) is an MCU.
7. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the filter circuit in the voltage conditioning unit (U6) is an RC parallel circuit, and the negative feedback amplifying circuit consists of a negative feedback operational amplifier.
8. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the analog-to-digital conversion unit (U7) consists of a high-precision analog-to-digital converter, comprises a high-speed SPI communication ADC, and outputs a data signal for high-speed SPI communication.
9. A battery cell voltage sampling circuit according to claim 1 or 2, wherein: the data isolation unit (U8) consists of a double-channel data isolator, and an isolation output port of the data isolation unit is connected with the main controller (U4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810301847.1A CN108459275B (en) | 2018-04-04 | 2018-04-04 | Battery cell voltage sampling circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201810301847.1A CN108459275B (en) | 2018-04-04 | 2018-04-04 | Battery cell voltage sampling circuit |
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| TWI671987B (en) * | 2018-09-10 | 2019-09-11 | 捷佳科技股份有限公司 | Wireless power transmitting unit |
| CN110441699B (en) * | 2019-07-29 | 2024-02-27 | 广东电网有限责任公司广州供电局 | Battery voltage detection circuit and battery voltage detection device |
| CN111426964A (en) * | 2020-04-29 | 2020-07-17 | 成都极空科技有限公司 | Battery pack voltage acquisition circuit based on MOS (metal oxide semiconductor) tube gating matrix |
| CN112599932A (en) * | 2021-01-08 | 2021-04-02 | 蔚来汽车科技(安徽)有限公司 | Battery pack, method and vehicle |
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