HK1115640B - Apparatus and method for detecting battery pack voltage - Google Patents

Description

Apparatus and method for detecting voltage of battery pack

Technical Field

The present invention relates to voltage detection, and more particularly, to an apparatus and method for detecting a voltage of a battery pack.

Background

A battery pack is generally composed of a plurality of batteries connected in series for supplying electric power to electronic devices such as electric cars, portable computers, electronic cameras, and the like. The battery pack is generally provided with a voltage detection device that detects the voltage of each battery for the capacity calculation and protection of each battery.

Fig. 1 shows a voltage detection device 100 for a battery pack in which a plurality of batteries are connected in series in the related art. The battery voltage detection apparatus 100 is composed of a first input selector 101, a second input selector 103, a detector buffer 105, a data processing circuit 110, and a voltage source 111. Generally, the external display unit 113 is connected to the voltage detection device 100 to receive and display the measured battery voltage.

In order to detect the voltage of each cell in the battery pack, for example, the cell 120, the first input selector 101 selects the positive electrode of the cell 120, and the second input selector 103 selects the negative electrode of the cell 120. The voltage of the battery 120 is supplied to the detector buffer 105 through the first input selector 101 and the second input selector 103. In the detector buffer 105, a predetermined calculation is performed on the voltage of the battery 120, thereby supplying an intermediate voltage to the data processing circuit 110. The data processing circuit 110 processes the intermediate voltage to obtain a voltage value representing the battery voltage of the battery 120. The data processing circuit 110 may comprise an analog-to-digital (a/D) converter 107 and an arithmetic unit 109 as shown in fig. 1, or simply a plurality of comparators to determine the voltage values. In fig. 1, the a/D converter 107 converts the analog intermediate voltage into digital and supplies the digital value of the intermediate voltage to the arithmetic unit 109. The arithmetic unit 109, such as a microprocessor, processes the supplied digital values in a predetermined manner to obtain voltage values representing the battery voltage of the battery 120. Finally, the display unit 113 can indicate the voltage value on a display screen, such as an LCD display panel, a plasma display panel, a Cathode Ray Tube (CRT), a fluorescent character display tube, or the like.

However, the first and second input selectors 101 and 103 are generally composed of semiconductor switching elements produced using a conventional high voltage Complementary Metal Oxide Semiconductor (CMOS) process. Such a switching element imposes a limitation on the application of the voltage detection apparatus 100. This limitation is caused by the fact that: a plurality of cells connected in series in the battery pack, a higher breakdown voltage required for the switching elements in the first and second input selectors 101 and 103, which have a low breakdown voltage. Therefore, in view of the low breakdown voltage of the switching element, there has to be a limit to the number of batteries to ensure the proper operation of the switching element. In particular, when the switching element is constructed with MOSFETs, in order to ensure normal operation of the MOSFETs, the gate-source voltage of each MOSFET must always be within a safe range, and further, the source-substrate voltage of each MOSFET must also always be within a safe range, and the body diode of each MOSFET must always be reverse-biased.

As mentioned before, for switching elements with high breakdown voltages, the above mentioned limitations will no longer be present. However, these switching elements with high breakdown voltages have to be produced using more complex and more expensive CMOS processing. As a result, the overall cost of the voltage detection device 100 increases. Moreover, the die size of the switching element with a high breakdown voltage generally has to be increased much more than the switching element with a low breakdown voltage to meet the same on-resistance requirement, which also adds more cost to the voltage detection device 100. Thus, it is not an ideal solution to overcome the above-mentioned drawbacks with switching elements produced using more complex and more expensive CMOS processing, considering the increased cost and die size.

Accuracy is another aspect that must be considered when evaluating voltage detection devices. Inaccuracies are typically caused by certain elements in the voltage detection device. For example, in the exemplary voltage detection apparatus 100, there is typically a common mode error in the detector buffer 105 and this common mode error may reduce the accuracy of the voltage detection. In order to increase accuracy, it is common to add some auxiliary components or lines, but this approach inevitably complicates the circuitry.

It is therefore an object of the present invention to provide a voltage detection apparatus and method which can be implemented using a switching element based on a conventional high-voltage CMOS process and at the same time avoid the limitation of its process without complicating the circuit and increase the accuracy without introducing a burden of process cost. The present invention is directed to such voltage sensing devices and methods.

Disclosure of Invention

In one embodiment, a voltage detection apparatus for a battery pack having a plurality of battery modules, and each battery module including a plurality of batteries connected in series is provided. The voltage detection device includes a plurality of selectors, a detector buffer and a data processing unit, each selector coupled to one of the plurality of battery modules for determining a predetermined battery and receiving a first voltage signal and a second voltage signal from the coupled battery module, the detector buffer coupled to the plurality of selectors for receiving a battery voltage of the predetermined battery and providing an intermediate voltage, and the data processing circuit coupled to the detector buffer for processing the intermediate voltage to obtain a voltage value representing the battery voltage of the predetermined battery.

In another embodiment, a method is provided for detecting the voltage of each cell in a battery pack having a plurality of cells connected in series. The method comprises the following steps: generating a plurality of control signals, each control signal having an adjustable amplitude; the method includes selecting a predetermined battery under control of the plurality of control signals, the predetermined battery having a battery voltage, obtaining an intermediate voltage based on the battery voltage of the predetermined battery, and obtaining a voltage value representing the battery voltage of the predetermined battery according to the intermediate voltage.

In yet another embodiment, an electronic system is provided. The electronic system includes a battery pack having a plurality of batteries connected in series, the plurality of batteries being divided into a plurality of battery modules, an electronic device connected to and powered by the battery pack, a digital device capable of predetermining one of the plurality of batteries and providing a selection signal, and a battery voltage detection device, the battery voltage detection device is coupled to the digital equipment for receiving a selection signal and coupled to the battery pack for selecting a predetermined battery and detecting the voltage of the predetermined battery according to the selection signal, the battery voltage detection apparatus further includes a plurality of switch boxes, each of which is coupled to one of the plurality of battery modules, and each switch controller is coupled to one of the plurality of battery modules for receiving the voltage signal and to one of the plurality of switch boxes for providing the control signal.

Drawings

The benefits of the present invention will become apparent as the following detailed description of exemplary embodiments proceeds, and this description should be considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a prior art voltage detection device;

FIG. 2 is a block diagram of a voltage detection device according to one embodiment of the present invention;

FIG. 3 is a schematic diagram of one of the selectors of FIG. 2;

FIG. 4 is a schematic diagram of the level shifter circuit of FIG. 3;

fig. 5 is a flowchart showing the operation of the battery voltage detection apparatus of fig. 2; and

FIG. 6 is an electronic system according to one embodiment of the invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention. While the invention will be described in conjunction with these embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.

Fig. 2 shows a voltage detection device 200 according to an embodiment of the present invention. The voltage detection apparatus 200 includes a plurality of selectors 210, a detector buffer 220, and a data processing circuit 230 including an a/D converter 217 and an arithmetic unit 219. The voltage detection device 200 detects the cell voltages of the cells 1A-1 to 3A-N connected in series. Referring to the battery connections in FIG. 2, battery 1A-1 has the lowest voltage, and batteries 3A-N have the highest voltage Vc 1.

The batteries 1A-1 to 3A-N are divided into a plurality of battery modules, for example, three battery modules 1A, 2A, and 3A. Each battery module is coupled to one of a plurality of selectors. As shown in fig. 2, battery module 1A is coupled to selector 210-1, battery module 2A is coupled to selector 210-2, and battery module 3A is coupled to selector 210-3. Each selector has similar electrical circuitry and electrical characteristics, and thus a representative selector 210-2 is described in detail below.

The selector 210-2 includes a switch box 201, a switch controller 203, a first resistor 205, and a second resistor 207. The switch box 201 is connected to the battery module 2A for selecting a predetermined battery from the batteries 2A-1 to 2A-N. The switch controller 203 is connected to the switch box 201 for controlling the state of the switch box 201, and the switch controller 203 is also connected to the battery module 2A for receiving a voltage signal. When a predetermined battery is selected, the voltages on the positive and negative electrodes of the predetermined battery are sent to lines 204 and 206, respectively, through the switch box 201. These two voltages are then provided to detector buffer 220. In other words, the battery voltage of the predetermined battery is supplied to the detector buffer 220.

The detector buffer 220 includes an operational amplifier 209, a third resistor 211, a fourth resistor 213, and a reference voltage 215. The voltage on line 204 is provided to the non-inverting terminal of operational amplifier 209 through first resistor 205. The voltage on line 206 is provided to the inverting terminal of operational amplifier 209 through second resistor 207. The third resistor 211 is connected between the inverting terminal and the output terminal of the operational amplifier 209. The non-inverting terminal is also connected to ground through a fourth resistor 213 and a reference voltage 215, and the connection point of the fourth resistor 213 and the reference voltage 215 is indicated as reference numeral 214, as shown in fig. 2. The reference voltage 215 is capable of providing a Direct Current (DC) voltage Vref, so the voltage at the connection point 214 is stably fixed at Vref.

The detector buffer 220 receives a battery voltage of a predetermined battery and outputs an intermediate voltage at an output terminal. Assuming that the impedances of the first and second resistors 205 and 207 are equal and the impedances of the third and fourth resistors 211 and 213 are equal, the intermediate voltage can theoretically be calculated according to equation (1):

wherein, V_cellBattery voltage, V, positioned as a predetermined battery_outIs defined as the intermediate voltage, R_cIs defined as the resistance of the third resistor 211 or the fourth resistor 213, and R_aDefined as the impedance of either the first resistor 205 or the second resistor 207. Suppose in R_aAnd R_cThe ratio between is 2, the intermediate voltage V_outCan be calculated according to equation (2):

(2)

then the intermediate voltage V is applied_outIs supplied to the a/D converter 217. At the same time, the DC reference voltage V is applied_refAnd also to a/D converter 217. Intermediate voltage V_outAnd a DC reference voltage V_refForm a pair of differential inputs V (V)_out，V_ref) And are received by the non-inverting and inverting terminals of a/D converter 217, respectively. The A/D converter 217 converts the intermediate voltage V_outConverted from analog to digital and provides the digital value of the intermediate voltage to the arithmetic unit 219. Will DC reference voltage V_refFor calibrating the a/D converter 217. The arithmetic unit 219 then processes the digital value in a predetermined manner to obtain a voltage value representing the voltage of the predetermined battery.

FIG. 3 illustrates a schematic diagram of the selector 210-2 of FIG. 2, according to one embodiment. As shown in fig. 3, the switch box 201 includes a plurality of switches, and the switch controller 203 includes a plurality of level shift circuits. Two switches are assigned to each of the cells 2A-1 to 2A-N in the battery module 2A, respectively connected to the positive and negative electrodes of each cell. Each switch has a first terminal, a second terminal, and a control terminal. The first end of each odd switch is connected to the positive electrode of the connected cell, with the odd switches designated with the reference symbols 1P to NP, respectively. The first terminal of each even-numbered switch is connected to the negative electrode of the connected battery, wherein the even-numbered switches are respectively designated by reference symbols 1N to NN. The second terminals of each of the odd switches are connected together by line 204 to a first resistor 205. The second terminals of each even-numbered switch are connected together to a second resistor 207 via line 206. The control terminal of each switch is connected to one of the plurality of level shifting circuits for receiving a control signal, and the state of each switch is determined by the received control signal.

Furthermore, if the switches in the switch box 201 are constructed from P-channel mosfets (PMOS) to ensure that the source-substrate voltage of the PMOS switches is within a safe range and that the PMOS body diodes are always reverse biased, the substrate of the PMOS switches must be connected to the local highest voltage Vc2 there. If the switches in the switch box are constructed of N-channel mosfets (NMOS), typically the substrate of the NMOS switch must be connected to full ground potential. The local highest voltage is Vc3 for selector 210-1 in fig. 2, and Vc1 for selector 210-3 in fig. 2.

Fig. 4 shows an exemplary schematic diagram of the level shifter circuit 300-MP of fig. 3. The exemplary level shifter circuit 300-MP includes a control unit 310 and a signal generator 320. Powered by the power supply VDD, the control unit 310 receives a selection signal at the selection terminal 303 from a digital device (not shown in fig. 4). The select signal is typically a digital signal, with a value of 0 representing a low voltage level and a value of 1 representing a high voltage level. When a value of 1 is provided on the select terminal 303, the voltage on line 302 will be set high and the voltage on line 304 will be set low. Similarly, when a value of 0 is provided on the select terminal 303, the voltage on line 302 will be set low and the voltage on line 304 will be set high. In fig. 4, the control unit 310 is implemented by a first inverter element and a second inverter element. The first inverter element is connected between the selection terminal 303 and the line 304, and is composed of Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) MP1 and MN 1. The second inverter element is connected between line 304 and line 302 and is comprised of mosfets mp2 and MN 2. However, those skilled in the art will appreciate that the control unit may be implemented by other conventional circuits and that the control unit 310 shown in FIG. 3 is for illustration and not limitation.

The signal generator 320 includes a first current mirror composed of MOSFETs MP1A and MP1B, a second current mirror composed of MOSFETs MP2A and MP2B, a third current mirror composed of MOSFETs MN2A and MN2B, a first switch MNs1, a second switch MNs2, a first current source MN1A, and a second current source MN 2A. Typically, the switches and current sources are formed by MOSFETs as shown in fig. 4, but it should be understood that the MOSFET structure may be replaced by other circuits as long as the necessary functions are achieved.

The gate terminal of the first switch MNS1 receives the voltage on line 302 and the gate terminal of the second switch MNS2 receives the voltage on line 304. The source terminal of the first switch MNS1 is connected to a first current source MN1A and the drain terminal of the first switch MNS1 is connected to a first current mirror. The source terminal of the second switch MNS2 is connected to a second current source MN1B and the drain terminal of the second switch MNS2 is connected to a second current mirror.

The first and second current mirrors are connected to the battery module 2A shown in fig. 3 at the power supply terminal 305. A first voltage signal is received at power terminal 305 from battery module 2A. The first voltage signal provides power to the level shifter circuit 300-MP. For all level shifting circuits in selector 210-2, the power supply terminal is connected to the positive electrode of battery 2A-N, at which the highest voltage Vc2 is present. The first voltage signal has a voltage level equal to Vc 2. The third current mirror is connected to the first current mirror for copying the current flowing through the first current mirror. The third current mirror is also connected to the battery module 2A for receiving the second voltage signal on the level terminal 307. For level shift circuit 300-MP, assuming that level terminal 307 is connected to the positive electrode of the test cell having a voltage of a Vcell1 on the positive electrode, the second voltage signal has a voltage level equal to a Vcell1, where Vcell1 is defined as the calibration voltage of the battery cell (battery cell). The third current mirror is also connected to the second current mirror at output 309, wherein a control signal supplied to the connected switch MP in fig. 3 flows to determine the state of the connected switch MP. The magnitude of the control signal is determined by the first voltage signal and the second voltage signal.

The first and second current sources MN1A and MN1B are also connected to a current terminal 313 through which current control signals are received. The current control signal controls the quiescent current of the level shifter circuit 300-MP.

When a value of 1 is supplied to the select terminal 303, the voltage on line 302 is initially set high and the voltage on line 304 is set low, as previously described. Thus, the first switch MNS1 is turned on and the second switch MNS2 is turned off. The static current from the first current source MN1A flows into the MOSFET MP1A through the first switch MNs 1. The first and third current mirrors are then sequentially replicated and the quiescent current is finally sent to MOSFET MN 2B. Since MOSFET MN2B is conductive, the voltage on output terminal 309 pushes to the voltage on level terminal 307, which is a × Vcell 1. As shown in fig. 2, the level shifter circuit 300-MP is connected to a control terminal of a switch MP, which is generally composed of a MOSFET. Assuming that switch MP is PMOS, it is assumed that output terminal 309 is connected to the gate terminal of switch MP, and the source terminal of switch MP is connected to the positive electrode of cells 2A-M, the voltage at which is defined by M × Vcell 1. Therefore, when a value of 1 is supplied to the select terminal 303, the gate-source voltage of the switch MP is calculated according to equation (3):

Vgs(m)＝(a-m)*Vcell1

(3)

wherein the gate-source voltage of the switch MP is defined as vgs (m). Since the gate-source voltage is calculated according to equation (3), the switch MP is turned on, and thus the positive electrode of the cells 2A-M is selected.

When a value of 0 is provided to the select terminal 303, the voltage on line 302 is set low and the voltage on line 304 is set high as previously described. As a result, the first switch MNS1 is turned off, and the second switch MNS2 is turned on. The static current from the second current source MN1B flows into the MOSFET MP2A through the second switch MNs 2. The quiescent current is then copied to the mosfet mp2B through the second current mirror. Since MOSFET MP2B is conductive, the voltage at output terminal 309 approaches the voltage at power supply terminal 305 equal to Vc 2. Similarly, assuming that switch MP is PMOS, it can be concluded that when a value of 0 is provided to the select terminal 303, the gate-source voltage of switch MP is calculated according to equation (4):

Vgs(m)＝Vc2-m*Vcells (4)

due to the gate-source voltage calculated according to equation (4), switch MP is turned off and thus isolates the positive electrodes of cells 2A-M.

For switch MP, the gate-source voltage is easily obtained within a safe range by setting an appropriate "a × Vcell 1" in equation (3). That is, by connecting the level terminal 307 to an appropriate voltage of the battery module 2A, the gate-source voltage will be ensured to be within a safe range. With respect to equation (4), the gate-source voltage is stably within the safety range. Since the gate-source voltage of the switch MP can be adjusted to always be within a safe range, the low gate-source breakdown voltage of the switch produced by the conventional high-voltage CMOS process will not impose a limitation on the application of the voltage detection device. Similarly, equations like equations (3) and (4) may be derived for the other switches in selectors 210-1, 210-2, and 210-3. Also, in the above, the equations (3) and (4) are derived on the assumption that the switch MP is PMOS. However, one skilled in the art will appreciate that NMOS may also be employed, and the calculation formula for the gate-source voltage may be similarly derived therein.

It must be understood that other types of level shifting circuits may also perform the same function. The disclosed embodiments of the level shifting circuit herein are for explanation, not for limitation.

Fig. 5 shows a flow diagram of battery voltage detection according to an embodiment of the invention. How the voltage detection device 200 detects the cell voltages of the cells 1A-1 to 3A-N will be described hereinafter.

First, in step 501, a predetermined battery is selected by the digital device, and the voltage of the predetermined battery will be detected in the subsequent steps. Here, for convenience of description, the predetermined batteries are assumed to be batteries 2A-M.

Steps 503 and 505 then aim to obtain a calibration voltage to eliminate common mode errors in the detector buffer 220. As is well known to those skilled in the art, the accuracy of the operational amplifier 209 is impaired by the common mode error, and thus the accuracy of the voltage detection apparatus 200 is also reduced. To increase accuracy, it is necessary to cancel the common mode error from the output of the operational amplifier 209.

In step 503, the common mode voltage is selected when the switches MP and (M +1) N are turned on under the control of the level shift circuits 300-MP and 300- (M +1) N, respectively. The switch (M +1) N here is connected to the negative electrode of the battery 2A- (M +1), which is adjacent to the batteries 2A-M. In this way, the voltage on the positive electrode of the battery 2A-M is provided to the non-inverting terminal of the operational amplifier 209, which in turn passes through the switch MP, the line 204 and the first resistor 205 in sequence. Meanwhile, as shown in FIG. 3, the voltage on the positive electrode of the battery 2A-M or the negative electrode of the battery 2A- (M +1) is also supplied to the inverting terminal of the operational amplifier 209, which in turn sequentially passes through the switch (M +1) N, the line 206, and the second resistor 207. That is, the common mode voltage is provided to the operational amplifier 209 in the detector buffer 220. Similarly, the common mode voltage may also be obtained by simultaneously transmitting the voltage on the negative electrodes of the batteries 2A-M to the non-inverting and inverting terminals of the operational amplifier 209. Then in step 505, when the operational amplifier 209 receives the common mode voltage, a calibration voltage is output on the output of the operational amplifier 209. The calibration voltage represents the common mode error at the output of the operational amplifier 209. The calibration voltage is then received and processed by the data processing unit 230.

After the calibration voltage is obtained, the voltage detection device 200 starts to detect the voltage of the predetermined battery 2A-M. In step 507, the cell voltage of the predetermined cell 2A-M is selected when the switches MP and MN are turned on under the control of the level shift circuits 300-MP and 300-MN, respectively. In this way, the voltage on the positive electrode of the battery 2A-M is provided to the non-inverting terminal of the operational amplifier 209, which in turn passes through the switch MP, the line 204 and the first resistor 205 in sequence. Meanwhile, the voltage on the negative electrodes of the batteries 2A-M is also provided to the inverting terminal of the operational amplifier 209, which in turn passes through the switch MN, line 206 and second resistor 207. Then, at step 509, the operational amplifier 209 outputs an intermediate voltage at the output terminal based on the inputs at the non-inverting terminal and the inverting terminal. However, as previously described, the intermediate voltage includes common mode errors. Step 511 is for eliminating the common mode error and obtaining a voltage value representing the voltage of the predetermined cell 2A-M. After the intermediate voltage is received and processed by the data processing unit 230, a voltage value is calculated by subtracting the processed calibration voltage from the processed intermediate voltage. After acquiring the voltage value, the display unit 113 finally displays the voltage value on the display screen.

The voltage detection apparatus described above can be applied to various electronic systems. Fig. 6 is an exemplary electronic system 600 that includes a battery pack 601, an electronic device 603, a voltage detection apparatus 200, and a digital device 605. The battery pack 601 is composed of a plurality of batteries, and is capable of supplying power to the electronic device 603. The electronic device 603 may be an electric car, a portable computer, an electronic camera, or the like. The battery pack 601 is also coupled to a voltage detection device 200, the voltage detection device 200 being capable of detecting the voltage of each cell in the battery pack 601. The digital device 605 is also connected to the voltage detection means 200 for determining the predetermined battery to be detected. After determining the predetermined battery, the digital device 605 transmits a selection signal to the voltage detection apparatus 200, and in response to the selection signal, the voltage detection apparatus 200 measures the battery voltage of the predetermined battery. According to the present invention, since the gate-source voltage of each switch is guaranteed to be within the safe range under the control of the level shift circuit, the switch in the voltage detection means does not impose a limitation on the application of the voltage detection means.

In operation, the voltage detection device 200 can detect the battery voltages of the batteries 1A-1 to 3A-N used in a portable computer, an electronic camera, or the like. In order to detect the voltage of a predetermined battery, the batteries 1A-1 to 3A-N are first divided into a plurality of battery modules, for example, battery modules 1A, 2A, and 3A. Each battery module is connected to a selector for selecting a predetermined battery.

The selector includes a switch box and a switch controller. The switch controller receives a voltage signal from the connected battery module and a selection signal from the digital device. Based on the voltage signal and the selection signal, the switch controller generates a control signal having a predetermined magnitude. Under the control of the control signal, the switch box selects a predetermined battery. At the same time, the predetermined amplitude of the control signal ensures that the switch box operates normally.

When the predetermined battery is selected, the selector supplies the battery voltage of the predetermined battery to the detector buffer and the processing unit to obtain a voltage value representing the battery voltage of the predetermined battery.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Other modifications, variations, and alternatives are also possible. The claims are therefore intended to cover all equivalents of the foregoing.

Claims (11)

1. A voltage detection device for a battery pack having a plurality of battery modules each including a plurality of batteries connected in series, each battery having a positive electrode and a negative electrode, the voltage detection device comprising:

a plurality of selectors, each coupled to one of the plurality of battery modules, for determining a predetermined battery and receiving a first voltage signal and a second voltage signal from the battery module to which it is coupled;

a detector buffer coupled to the plurality of selectors for receiving a battery voltage of a predetermined battery and providing an intermediate voltage, the detector buffer including an operational amplifier having an inverting terminal and a non-inverting terminal; the detector buffer further includes a third resistor, a fourth resistor, and a reference voltage;

a data processing circuit coupled to the detector buffer for processing the intermediate voltage and the reference voltage to obtain a voltage value representing a battery voltage of the predetermined battery,

wherein each selector further comprises;

a switch box for selecting a predetermined cell and providing a cell voltage of the predetermined cell, the switch box having a plurality of switches, each odd-numbered switch being coupled to a positive electrode of one of the plurality of cells in the coupled battery module and each even-numbered switch being coupled to a negative electrode of one of the plurality of cells in the coupled battery module; and

a plurality of level shifting circuits, each level shifting circuit receiving a first voltage signal and a second voltage signal from a coupled battery module, and each level shifting circuit coupled to one of the plurality of switches for providing a control signal to the coupled switch; and wherein

The voltage at the positive electrode of the predetermined battery is sent through the switch box and supplied to the non-inverting terminal of the operational amplifier through a first resistor;

the voltage on the negative electrode of the predetermined battery is sent through the switch box and supplied to the inverting terminal of the operational amplifier through a second resistor;

the third resistor is connected between the inverting terminal and the output terminal of the operational amplifier;

the non-inverting terminal is also connected to the ground through a fourth resistor and a reference voltage; and

the switch is a MOSFET.

2. The voltage detection apparatus according to claim 1, wherein the predetermined cell is selected when odd-numbered and even-numbered switches respectively coupled to positive and negative electrodes of the predetermined cell are turned on.

3. The voltage detection device of claim 1, wherein each level shifter receives a selection signal and generates a control signal according to the selection signal to control the coupled switches.

4. The voltage sensing device of claim 1, wherein the control signal has an amplitude and the amplitude is determined by the first and second voltage signals.

5. The voltage detection device of claim 1, wherein each level shifter circuit further comprises a power terminal coupled to a positive electrode of a first battery in the coupled battery module to receive the first voltage signal and a level terminal coupled to a positive electrode of a second battery in the coupled battery module to receive the second voltage signal.

6. The voltage detection device of claim 5, wherein the first battery has a highest voltage among coupled battery modules.

7. The voltage detection device of claim 1, wherein each switch further comprises a first terminal, a second terminal, and a control terminal, wherein the first terminal of each odd switch is connected to a positive electrode of one of the plurality of cells, the first terminal of each even switch is connected to a negative electrode of the plurality of cells, the second terminal of each odd switch is connected to the first node, the second terminal of each even switch is connected to the second node, and the control terminal of each switch receives the control signal.

8. The voltage detection apparatus of claim 7, wherein the voltage difference between the first node and the second node is a battery voltage of a predetermined battery.

9. The voltage sensing device of claim 1, wherein one of the plurality of switches is a P-MOSFET, and a substrate of the P-MOSFET is connected to a highest voltage among the coupled battery modules.

10. The voltage detection device of claim 1, wherein the switch box further provides a common mode voltage to a detector buffer for calibrating a voltage value representative of a battery voltage of a predetermined battery.

11. The voltage detection apparatus of claim 10, wherein the common mode voltage is obtained when the voltage at the predetermined electrode of the predetermined battery is transmitted to the non-inverting terminal and the inverting terminal of the detector buffer through the switch box.