Controller and Battery Voltage Detection Method

Abstract

The present invention provides a controller and a battery voltage detection method. The controller is used to detect the voltages of multiple single cells in a battery pack. The controller includes multiple converters coupled to the multiple single cells. Among them, the positive electrode of each single cell in the multiple single cells is connected to the corresponding converter through a corresponding first path, and the negative electrode of each single cell is connected to the corresponding converter through a corresponding second path; and multiple switch units coupled between the multiple single cells and the multiple converters. Among them, the multiple converters are connected to the positive electrodes of the multiple single cells through the multiple switch units. When the switch unit corresponding to a single cell is turned on, the positive electrode of the single cell provides a working current and a sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the working current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a controller and a battery voltage detection method. Background Art

[0002] In recent years, batteries have been widely used in many fields such as power tools, electric bicycles, electric vehicles, military equipment, aerospace, etc. The battery voltage represents the potential difference between the positive and negative electrodes of the battery under a certain state, and is also one of the important indicators for measuring the charge and discharge performance of the battery. Based on this, a detection circuit for detecting the battery voltage has emerged.

[0003] Figure 1 Fig. 1 is a circuit diagram of a traditional battery voltage detection system 100. This detection system 100 uses the compensation current I generated by the current mirror 340 to MP1 compensate for the sampling current I flowing from the resistor RF3 to the resistor 308_3, 322_3 uses the working current I of the operational amplifier 304_4 to 304_4 compensate for the sampling current I flowing from the resistor RF2 to the resistor 308_2, 322_2 uses the working current I of the operational amplifier 304_3 to 304_3 compensate for the sampling current I flowing from the resistor RF1 to the resistor 308_1. 322_1 Then, in an ideal state, through compensation, the currents flowing through the resistors RF3, RF2, and RF1 are all 0. However, since the current flowing through the resistor RF4 is relatively large, the voltage drop generated on the resistor RF4 is also relatively large, resulting in a lower accuracy of the measured battery voltage V 322_4 indicated by the sampling current I of the single battery 302_4. 302_4 Summary of the Invention

[0004] The present invention provides a battery voltage detection method. This method is used to detect the voltages of multiple single batteries in a battery pack. The multiple single batteries respectively correspond to multiple converters. The positive electrode of each single battery is connected to the corresponding converter through a corresponding first path, and the negative electrode of each single battery is connected to the corresponding converter through a corresponding second path. The multiple converters are coupled to the positive electrodes of the multiple single batteries via multiple switch units. The method includes: turning on the switch unit corresponding to a single battery, so that the positive electrode of the single battery provides a working current and a sampling current for the converter corresponding to the single battery through the first path corresponding to the single battery, and the working current flows from the positive electrode of the single battery through the converter corresponding to the single battery to the ground; and using the converter corresponding to the single battery to detect the voltage of the single battery.

[0005] The present invention also provides a controller. The controller is used to detect the voltages of a plurality of individual cells in a battery pack. The controller includes a plurality of converters coupled to the plurality of individual cells, wherein the positive electrode of each individual cell in the plurality of individual cells is connected to the corresponding converter through a corresponding first path, and the negative electrode of each individual cell is connected to the corresponding converter through a corresponding second path; and a plurality of switch units coupled between the plurality of individual cells and the plurality of converters, wherein the plurality of converters are connected to the positive electrodes of the plurality of individual cells through the plurality of switch units. When the switch unit corresponding to an individual cell is turned on, the positive electrode of the individual cell provides a working current and a sampling current to the converter corresponding to the individual cell through the first path corresponding to the individual cell, and the working current flows from the positive electrode of the individual cell through the converter corresponding to the individual cell to the ground.

[0006] The present invention reduces the difference between the current on the first path between the converter and the positive electrode of its corresponding individual cell and the current on the second path between the converter and the negative electrode of its corresponding individual cell, so that each converter can accurately detect the voltage of each individual cell. Description of the Drawings

[0007] The following description by combining some embodiments of the present invention and their accompanying drawings can further understand the purpose, specific structural features and advantages of the present invention.

[0008] Figure 1 Shown is a circuit diagram of a conventional battery voltage detection system;

[0009] Figure 2 Shown is a circuit diagram of a controller according to an embodiment of the present invention;

[0010] Figure 3 Shown as Figure 2 the timing diagram of each switch unit of the controller in

[0011] Figure 4 Shown is a circuit diagram of a controller according to an embodiment of the present invention;

[0012] Figure 5 Shown as Figure 4 the timing diagram of each switch unit of the controller in

[0013] Figure 6 Shown is a circuit diagram of a controller according to an embodiment of the present invention;

[0014] Figure 7 Shown as Figure 6 the timing diagram of each switch unit of the controller in

[0015] Figure 8 Shown asFigure 6 Another timing diagram of the switches of the controller in

[0016] Figure 9 The figure shows a flowchart of a battery voltage detection method according to an embodiment of the present invention. Detailed implementation manners

[0017] The embodiments of the present invention will be described in detail below. Although the present invention is illustrated and described by these embodiments, it should be noted that the present invention is not limited to these embodiments only. On the contrary, the present invention covers all alternatives, variations, and equivalents within the spirit and scope of the invention defined by the appended claims.

[0018] In addition, for better illustration of the present invention, numerous specific details are given in the following detailed implementation manners. Those skilled in the art will understand that the present invention can be implemented without these specific details. In other instances, well-known methods, procedures, components, and circuits are not described in detail to highlight the gist of the present invention.

[0019] Figure 2 The figure shows a circuit diagram 200 of a controller 210A for detecting the voltages of a plurality of battery cells in a battery pack according to an embodiment of the present invention. Figure 2 The battery pack in the example includes single cells CELL1, CELL2, CELL3, and CELL4, and the controller 210A includes converters 211_1 - 211_4 corresponding to the single cells CELL1 - CELL4 respectively. In this embodiment, the single cell CELL1 is referred to as the top single cell (i.e., the cell farthest from the reference ground GND), and the single cell CELL4 is referred to as the bottom single cell (i.e., the cell closest to the reference ground GND).

[0020] The positive electrode of the single cell CELLj (j = 1, 2, or 3) is connected to the converter 211_j through a first path, and the negative electrode of the single cell CELLj is connected to the converter 211_j through a second path. The controller 210A further includes a plurality of switch units 212_1 - 212_4 respectively coupled between the plurality of single cells CELL1 - CELL4 and the plurality of converters 211_1 - 211_4. The plurality of converters 211_1 - 211_4 are respectively coupled to the positive electrodes of the single cells CELL1 - CELL4 through the plurality of switch units 212_1 - 212_4. When the switch unit corresponding to each single cell is turned on, the working current I OPj and the sampling current I 1_j flow through the first path corresponding to the converter 211_j. The working current I OPjFlows to the ground from the positive electrode of the single battery CELLj through the first path and the corresponding converter 211_j. The working current I provided by the positive electrode of the single battery CELL(j + 1) OP(j+1) And the sampling current I 1_(j+1) Flows through the second path corresponding to the converter 211_j. In one embodiment, the first path corresponding to the converter 211_j includes a connection resistor RFj. The second path corresponding to the converter 211_j includes a connection resistor RF(j + 1). For the single battery CELL4, the positive electrode of the single battery CELL4 is connected to the converter 211_4 via the connection resistor RF4 and the switch unit 212_4, and the negative electrode of the single battery CELL4 is connected to the converter 211_4 via the switch unit 212_5. In one embodiment, the resistance values of the connection resistors RF1, RF2, RF3, and RF4 are equal.

[0021] The converter 211_j can be started or shut down by turning on or off the switch unit 212_j (j = 1, 2, or 3). For example, by turning on the switch unit 212_1 (such as switches S1, K1), the converter 211_1 is started, and by turning off the switch unit 212_1, the converter 211_1 is shut down. In one embodiment, the switch unit 212_j (j = 1, 2, or 3) includes a switch Sj and a switch Kj. By turning on the switch Kj, the positive electrode of the single battery CELLj provides the working current I for the converter 211_j through the first path corresponding to the converter 211_j OPj . The function of setting the switch Kj is to start or shut down the operational amplifier OPj in the converter 211_j separately to save electric energy. By turning on the switch Sj, the positive electrode of the single battery CELLj provides the sampling current I for the converter 211_j through the first path corresponding to the converter 211_j 1_j .

[0022] In addition, when the switch units 212_4 and 212_5 are turned on simultaneously, the converter 211_4 is started, and by turning off any one of the switch units 212_4 and 212_5, the converter 211_4 is shut down. When the switch units 212_4 and 212_5 are turned on simultaneously, the sampling current I 1_4 (not marked in the figure) and the working current I OP4 (not marked in the figure) flowing through the converter 211_4 are both currents provided by the positive electrode of the single battery CELL4.

[0023] The converter 211_j detects the voltage of the single battery CELLj and generates a sampling signal SAMj (j = 1, 2, 3, or 4). In one embodiment, the sampling signal SAMj can be the sampling current I 1_jSpecifically, the converter 211_j converts the voltage of the single battery CELLj into a sampling current I indicating the voltage of the single battery CELLj. 1_j In another embodiment, the sampling signal SAMj may be a sampling voltage V. SAMj Specifically, the sampling current I 1_j (j = 1, 2, 3 or 4) flows through the sampling resistor Rsj and is detected as a sampling voltage V. SAMj In one embodiment, the sampling voltages V SAMj (j = 1, 2, 3 or 4) all use the same reference voltage (such as ground) as the reference point.

[0024] In one embodiment, the converter 211_j (j = 1, 2 or 3) includes an operational amplifier OPj, a resistor Raj, a transistor MPSj, and a sampling resistor Rsj. The operational amplifier OPj (j = 1, 2 or 3) is coupled to the positive electrode of the single battery CELLj through a switch Kj, and the working current I OPj flows from the positive electrode of the single battery CELLj through the connection resistor RFj and the operational amplifier OPj to ground. The resistor Raj is coupled to the positive electrode of the single battery CELLj through a switch Sj, and the sampling current I 1_j flows from the positive electrode of the single battery CELLj through the connection resistor RFj, the resistor Raj, and the sampling resistor Rsj to ground. Additionally, the converter 211_4 includes a sampling resistor Rs4. Figure 2 The working modes of the controller 210A in Figure 2 may include the following two types.

[0025] In the first working mode, the controller 210A simultaneously turns on Figure 2 all the switch units 212_1 - 212_4 in Figure 2 , so that the converters 211_1 - 211_4 are all activated. The converter 211_j (j = 1, 2 or 3) receives the working current I provided by the single battery CELLj through the first path corresponding to the converter 211_j OPj and the sampling current I 1_j . The working current I OP(j+1) and the sampling current I 1_(j+1) provided by the lower adjacent single battery CELL(j + 1) of the single battery CELLj flow through the second path corresponding to the converter 211_j. In one embodiment, in an ideal state, by reasonably setting the parameters of relevant components, the sum of the working current and the sampling current provided by each single battery can be made approximately equal. The converter 211_j detects the voltage of the single battery CELLj and generates a sampling signal SAMj indicating the voltage of the single battery CELLj (such as the sampling voltage V SAMj or the sampling current I 1_j ).

[0026] In addition, when detecting the voltage of the single battery CELL4, the single battery CELL4, the connection resistor RF4, and the converter 211_4 form a closed loop. The converter 211_4 detects the voltage of the single battery CELL4 and generates a sampling signal SAM4 indicating the voltage of the single battery CELL4 (for example, the current flowing through the converter 211_4 or the voltage across the converter 211_4).

[0027] Relative to Figure 1 In terms of Figure 2 In [reference], the controller 210A in [reference] changes the power supply mode of the operational amplifiers in each converter, so that the currents flowing through the first path and the second path corresponding to each converter are the sum of the working current and the sampling current provided by the positive electrodes of two adjacent single batteries. In an ideal state, by reasonably setting the parameters of relevant components, the working currents of each operational amplifier can be approximately equal, and the sampling currents of each can be approximately equal. In an embodiment, since the resistance values of the connection resistors have been set to be equal, under the above conditions, the voltage drops across each connection resistor are also approximately equal. Therefore, relative to Figure 1 In the system in [reference], the controller 210A can detect the voltages of each single battery more accurately. However, since the positive electrode of each single battery provides the working current and the sampling current for the corresponding converter, the currents flowing through the single batteries CELL1, CELL2, CELL3, and CELL4 increase in sequence. After the controller 210A performs long-term detection work, the balance between the voltages of each single battery (the balance means that the differences between the voltages of each single battery are within the balance threshold range) may be lost, thereby reducing the accuracy of the detected voltages of each single battery indicated by each sampling signal. To solve this problem, the second working mode of the controller 210A is disclosed in the present invention.

[0028] In the second working mode, the controller 210A selectively turns on two switch units (for example, the switch units 212_j and 212_(j + 1)) respectively corresponding to two adjacent single batteries (for example, the single batteries CELLj and CELL(j + 1), j = 1, 2, 3), so that two adjacent converters (for example, the converters 211_j and 211_(j + 1)) respectively corresponding to two adjacent single batteries (for example, the single batteries CELLj and CELL(j + 1)) are activated while other converters remain off.

[0029] The upper converter (e.g., converter 211_j) in two adjacent converters (e.g., converters 211_j, 211_(j + 1), j = 1, 2, 3) receives the working current I provided by the positive electrode of the upper single cell (e.g., single cell CELLj) in two adjacent single cells (e.g., single cells CELLj, CELL(j + 1)) through the first path corresponding to the upper converter (e.g., converter 211_j). OPj and the sampling current I 1_j . The working current I OP(j+1) and the sampling current I 1_(j+1) provided by the positive electrode of the lower single cell (e.g., single cell CELL(j + 1)) in two adjacent single cells (e.g., single cells CELLj, CELL(j + 1)) flow through the second path corresponding to the upper converter (e.g., converter 211_j). The upper converter (e.g., converter 211_j) detects the voltage of the upper single cell (e.g., single cell CELLj).

[0030] When detecting the voltage of single cell CELL4, the voltage of single cell CELL4 can be detected by turning on switch units 212_4, 212_5 or by turning on switch unit 212_4 and turning off switch unit 212_5. Both of these methods can accurately detect the voltage of single cell CELL4.

[0031] In the second working mode, by controlling the duty cycle of the conduction time t of the switch units respectively corresponding to two adjacent single cells, the average value of the difference between the currents flowing through each single cell can be reduced, thereby maintaining the balance of each single cell. Among them, the duty cycle refers to the ratio of the conduction time t of the switch units respectively corresponding to two adjacent single cells to the detection period T. The detection period T refers to the total time required to complete the detection of the voltages of all single cells CELL1, CELL2, CELL3 and CELL4. The specific content will be described in Figure 3 .

[0032] Figure 3 Shown is the timing diagram of each switch unit of the controller in Figure 2 in the second working mode. In Figure 3In the illustrated embodiment, during the time period from t0 to t1, only switch units 212_1 and 212_2 are turned on, and converter 211_1 detects the voltage of single cell CELL1. During the time period from t2 to t3, only switch units 212_2 and 212_3 are turned on, and converter 211_2 detects the voltage of single cell CELL2. During the time period from t4 to t5, only switch units 212_3, 212_4, and 212_5 are turned on, and converter 211_3 detects the voltage of single cell CELL3. During the time period from t6 to t7, only switch unit 212_4 is turned on, and converter 211_4 detects the voltage of single cell CELL4. In this embodiment, t1–t0 = t3–t2 = t5–t4 = t7–t6. In other embodiments, t1–t0, t3–t2, t5–t4, and t7–t6 may not be equal.

[0033] Assume Figure 3 If the detection period T in is 100 ms and the conduction time t of the switch units corresponding to two adjacent single cells is 100 μs each, then the duty cycle is 100 μs / 100 ms. Assume that the current received by each converter through its corresponding first path is 10 μA. In this example, when controller 210A operates in the first operating mode, the difference between the current flowing through single cell CELL1 and the current flowing through single cell CELL3 is 20 μA. And when controller 210A operates in the Figure 3 shown manner (second operating mode), within the detection period T, the average value of the difference between the current flowing through single cell CELL1 and the current flowing through single cell CELL3 drops to 20 nA. It can be seen that in the second operating mode, by controlling (such as reducing) the duty cycle of the conduction time t of the switch units corresponding to two adjacent single cells, the average value of the difference between the currents flowing through each single cell can be reduced, thereby maintaining the balance of each single cell.

[0034] Figure 4 Shown is the circuit diagram of controller 210B according to another embodiment of the present invention.

[0035] Controller 210B further includes a plurality of mirror units on the basis of controller 210A in Figure 2 . In the embodiment shown in Figure 4 , this controller 210B includes mirror units 410_1, 410_2, and 410_3.

[0036] Mirror unit 410_j (j = 1, 2, or 3) copies the working current I of converter 211_j corresponding to single cell CELLj OPj and the sampling current I 1_j, to reduce the difference between the current flowing through the first path corresponding to the converter 211_j and the current flowing through the second path corresponding to the converter 211_j, wherein the mirror unit 410_j is coupled to the second path corresponding to the converter 211_j.

[0037] Specifically, the mirror unit 410_j (j = 1, 2 or 3) generates a first copy current proportional to the working current I. OPj In one embodiment, in an ideal state, by reasonably setting the parameters of relevant components, the first copy current can be approximately equal to the working current I. OPj Using the mirror unit 410_j (j = 1, 2 or 3), a second copy current proportional to the sampling current I is generated. 1_j In one embodiment, in an ideal state, by reasonably setting the parameters of relevant components, the second copy current can be approximately equal to the sampling current I. 1_j Wherein, the working current I OPj and the sampling current I 1_j flow through the first path corresponding to the converter 211_j, and the first copy current and the second copy current flow through the second path corresponding to the converter 211_j.

[0038] In one embodiment, each mirror unit includes a first branch, a second branch and a third branch. The sampling current I 1_j flows through the first branch coupled to the converter 211_j (j = 1, 2 or 3). The second branch coupled to the first branch generates a first copy current proportional to the sampling current I. 1_j This first copy current flows from the second path corresponding to the converter 211_j to the second branch. The third branch coupled to the converter 211_j generates a second copy current proportional to the working current I. OPj This second copy current flows from the second path corresponding to the converter 211_j to the third branch.

[0039] In Figure 4 the illustrated embodiment, the mirror unit 410_1 includes a first branch, a second branch and a third branch. The first branch includes the transistor M1, the second branch includes the transistor M2, and the third branch includes the transistor M3. The gate of the transistor M1 is coupled to the gate of the transistor M2 to form a current mirror structure, and the gate of the transistor M3 is coupled to the component related to the working current I OP1 inside the operational amplifier OP1 to form a current mirror structure. The sampling current I 1_1 flows to the ground via the transistor M1. The transistor M2 copies the sampling current I flowing through the transistor M1 1_1A first copy current is generated. Among them, the first copy current flows to the transistor M2 through the second path corresponding to the converter 211_1. The transistor M3 copies the operating current I of the converter 211_1 OP1 to generate a second copy current. Among them, the second copy current flows through the transistor M3 through the second path corresponding to the converter 211_1. In Figure 4 the embodiment, the structures of the mirror units 410_2 and 410_3 are the same as that of the mirror unit 410_1.

[0040] Figure 4 In the controller 210B in, the switch unit 212_j corresponding to the single battery CELLj (j = 1, 2 or 3) is selectively turned on, and the converter 211_j corresponding to the single battery CELLj is started while other converters are turned off. The mirror unit 410_j corresponding to the single battery CELLj is started to copy the current flowing on the first path corresponding to the converter 211_j. The converter 211_j is used to detect the voltage of the single battery CELLj.

[0041] For example, when detecting the voltage of the single battery CELL1, the switches S1 and K1 are turned on, and both the converter 211_1 and the mirror unit 410_1 are started. The mirror unit 410_1 copies the current on the first path corresponding to the converter 211_1 to the second path corresponding to the converter 211_1. In an ideal state, after being copied by the mirror unit 410_1, the current on the first path corresponding to the converter 211_1 is approximately equal to the current on its corresponding second path. The converter 211_1 detects the voltage of the single battery CELL1 and generates a sampling signal SAM1 indicating the voltage of the single battery CELL1.

[0042] The process of detecting the voltages of the single batteries CELL2 and CELL3 is similar to the process of detecting the voltage of the single battery CELL1. The process of detecting the voltage of the single battery CELL4 is similar to Figure 2 the relevant description of.

[0043] According to the above content, by using the copying function of the mirror unit, the current on the first path corresponding to the converters 211_1 - 211_3 can be approximately equal to the current on its corresponding second path, so that each sampling signal can accurately indicate the voltage of the corresponding single battery. Further, by controlling (such as reducing) the duty cycle of the on-time t of the switch unit corresponding to each single battery, the average value of the difference between the currents flowing through each single battery can be reduced, so as to maintain the balance of each single battery. Among them, the duty cycle is the ratio of the on-time t of the switch unit corresponding to each single battery to the detection period T.

[0044] Figure 5 As shown in Figure 4The timing diagram of each switching unit of the controller 210B in. In Figure 5 In the illustrated embodiment, during the time period from t0 to t1, only the switching unit 212_1 is turned on, and the converter 211_1 detects the voltage of the single cell CELL1. During the time period from t2 to t3, only the switching unit 212_2 is turned on, and the converter 211_2 detects the voltage of the single cell CELL2. During the time period from t4 to t5, only the switching unit 212_3 is turned on, and the converter 211_3 detects the voltage of the single cell CELL3. During the time period from t6 to t7, only the switching unit 212_4 is turned on, and the converter 211_4 detects the voltage of the single cell CELL4. In this embodiment, t1–t0 = t3–t2 = t5–t4 = t7–t6. In other embodiments, t1–t0, t3–t2, t5–t4, and t7–t6 may not be equal.

[0045] By controlling (such as reducing) the duty cycle of the conduction time t of the switching unit corresponding to each single cell, the average value of the difference between the currents flowing through each single cell can be reduced, thereby maintaining the balance of each single cell.

[0046] Figure 6 The figure shows the circuit diagram of the controller 210C according to another embodiment of the present invention.

[0047] In Figure 6 In the illustrated embodiment, the controller 210C further includes a mirror unit 610 and a compensation circuit 620 on the basis of the Figure 2 controller 210A in.

[0048] The mirror unit 610 is coupled to the second path corresponding to the top single cell (single cell CELL1) for replicating the working current I of the converter 211_1 corresponding to the top single cell OP1 and the sampling current I 1_1 to reduce the difference between the current flowing through the first path corresponding to the converter 211_1 and the current flowing through the second path corresponding to the converter 211_1.

[0049] Specifically, when detecting the voltage of the single cell CELL1, the switching unit 212_1 and the switch SW1 are turned on, and the converter 211_1 and the mirror unit 610 are activated. The working current I provided by the positive electrode of the single cell CELL1 OP1 and the sampling current I 1_1Flows through the first path corresponding to converter 211_1. The mirror unit 610 copies the current flowing through the first path corresponding to converter 211_1 to the second path corresponding to converter 211_1, thereby reducing the difference between the current flowing through the first path corresponding to converter 211_1 and the current flowing through the second path corresponding to converter 211_1. In one embodiment, in an ideal state, by reasonably setting the parameters of relevant components, after being copied by the mirror unit 610, the magnitude of the current flowing through the first path corresponding to converter 211_1 is approximately equal to the current flowing through the second path corresponding to converter 211_1. Therefore, converter 211_1 can accurately detect the voltage of the single battery CELL1.

[0050] The compensation circuit 620 is coupled to a plurality of converters 211_1–211_4 and is configured to generate a compensation current to compensate for the current flowing through the first path corresponding to one or more of the plurality of single batteries. The one or more single batteries may be single batteries other than the top single battery (e.g., single batteries CELL2, CELL3).

[0051] Specifically, when detecting the voltage of the single battery CELLj (j = 2 or 3), the switch unit 212_j and the switch SWj are turned on, and the converter 211_j and the compensation circuit 620 are activated. The converter 211_j receives the working current I provided by the single battery CELLj through the first path corresponding to the converter 211_j OPj and the sampling current I 1_j . The compensation circuit 620 generates a compensation current I OPj and the sampling current I 1_j based on the working current I COMj to compensate for the current flowing through the first path corresponding to the single battery CELLj.

[0052] In one embodiment, the compensation circuit 620 includes a detection unit 621 coupled to a plurality of converters and a compensation unit 622 coupled to the detection unit 621. The detection unit 621 samples the working current and the sampling current of the plurality of converters and respectively generates corresponding reference currents proportional to the sum of the working current and the sampling current.

[0053] Specifically, when detecting the voltage of the single battery CELLj (j = 2 or 3), the switch unit 212_j is turned on, and the converter 211_j is activated. The positive electrode of the single battery CELLj supplies the working current I OPj and the sampling current I 1_j to the converter 211_j through the first path corresponding to it. The switch SWj is turned on, and the detection unit 621 samples the working current I OPj and the sampling current I 1_j and generates a corresponding one proportional to the working current IOPj and the sampling current I 1_j is a reference current I proportional to the sum of REFj .

[0054] In one embodiment, the detection unit 621 includes a selector 668, an operational amplifier OPC, a transistor MC1, a resistor Ra5, and a transistor MC2. The selector 668 is configured to select one sampling signal V from multiple sampling signals SAMi . In one embodiment, the sampling signal V selected by the selector 668 SAMi is the sampling voltage corresponding to the single cell CELLj. The transistor MC1 is respectively coupled to the components related to the working current I OPj inside the operational amplifier OPj (j = 1, 2, or 3) to form a current mirror structure to copy the working current I of the operational amplifier OPj OPj . The sampling voltage V selected by the selector 668 SAMi is applied to the resistor Ra5 to generate a current I SR . Wherein the working current I OPj and the current I SR sum to the reference current I REFi . The reference current I REFi flows through the transistor MC2 to the ground. In an ideal state, by reasonably setting the parameters of the relevant components, the magnitude of the current I SR can be approximately equal to the sampling current I 1_i , and the reference current I REFi can also be made proportional to the sum of the working current I OPj and the current I SR .

[0055] The compensation unit 622 generates a compensation current I REFj (j = 2 or 3) proportional to the reference current I COMj . Wherein, the compensation current I COMj compensates the current flowing through the first path corresponding to the single cell CELLj

[0056] Specifically, the compensation unit 622 copies the reference current I REFj (j = 2 or 3) to generate a compensation current I COMj . When the switch SWj is turned on, the compensation current I COMj flows from the compensation unit 622 to the first path corresponding to the single cell CELLj. In an ideal state, by reasonably setting the parameters of the relevant components, the magnitude of the compensation current I COMj (j = 2 or 3) is approximately equal to the working current I OPj and the sampling current I 1_jThe sum is such that the total current flowing through the first path corresponding to the converter 211_j is equal to zero. At the same time, since the switching unit 212_(j + 1) is open, the current flowing through the second path corresponding to the converter 211_j is also 0. Because the current flowing through the first path corresponding to the converter 211_j and the current flowing through the second path corresponding to the converter 211_j are both 0, the converter 211_j can accurately detect the voltage of the single battery CELLj.

[0057] In one embodiment, the compensation unit 622 includes transistors MP1, MP2, and MP3. The transistor MP1 and the transistors MP2, MP3 form a current mirror structure to copy the reference current I flowing through the transistor MP1 REFj to generate a corresponding compensation current I COMj . When the switch SWj (j = 2 or 3) is turned on, the compensation current I COMj flows from the compensation unit 622 to the first path corresponding to the converter 211_j, so that the total current flowing through the first path corresponding to the converter 211_j is approximately equal to zero.

[0058] According to the above, each converter can accurately detect the voltage of each single battery. However, when detecting the voltage of the single battery CELL1, the current copied by the mirror unit 610 flows through the resistor RF2 from the node between the negative electrode of the single battery CELL1 and the positive electrode of the single battery CELL2, resulting in a current flowing through the single battery CELL1 being less than the current flowing through other single batteries, thus causing the battery pack to lose balance. To solve this problem, the compensation circuit 620 in the controller 210C provided by the embodiment of the present invention is further configured to generate a balancing current I BL . When the switch SW2 is turned on, the balancing current I BL flows from the compensation unit 622 through the second path corresponding to the converter 211_1 to the negative electrode of the top single battery CELL1, and further flows to the positive electrode of the top single battery CELL1, so as to reduce the difference between the current flowing through the top single battery and the current flowing through other single batteries, thereby maintaining the balance of each single battery.

[0059] Figure 7 and Figure 8 respectively show the relevant timing diagrams of the controller 210. In one embodiment, as Figure 7 shown, within a detection period T, the controller 210C first detects the voltage of each single battery separately (for example, from CELL1 to CELL4), and then starts the converter 211_1 corresponding to the top single battery CELL1 again. The compensation circuit 620 generates a balancing current I proportional to the sum of the working current I OP1 and the sampling current I 1_1 of the converter 211_1BL 。In another embodiment, as Figure 8 shown, when detecting the voltage of the single cell CELLi, the compensation circuit 620 generates the operating current I of the converter 211_i corresponding to the single cell CELLi OPi and the sampling current I 1-i and generates a balancing current I proportional to the sum BL of them. In Figure 8 the example of CELLi is CELL4, and in other examples, CELLi can be any single cell other than the top single cell CELL1 and the lower single cell adjacent to the top single cell (i.e., CELL2). The specific description is as follows.

[0060] Figure 7 As shown in Figure 6 is the timing diagram of each switching unit of the controller 210C in

[0061] During the time period from t0 to t1, the controller 210C detects the voltage of the single cell CELL1. The switching unit 212_1 and the switch SW1 are turned on, and the converter 211_1 and the mirror unit 610 are activated. The mirror unit 610 copies the current flowing through the first path corresponding to the converter 211_1 to the second path corresponding to the converter 211_1. The converter 211_1 detects the voltage of the single cell CELL1 and generates a sampling signal SAM1 indicating the voltage of the single cell CELL1. During this time period, since there is current on the second path corresponding to the converter 211_1, the current flowing through the single cell CELL1 is less than the current flowing through other single cells.

[0062] During the time period from t2 to t3, the controller 210C detects the voltage of the single cell CELL2, and during the time period from t4 to t5, the controller 210C detects the voltage of the single cell CELL3. When detecting the voltage of the single cell CELLj (j = 2 or 3), only the switching unit 212_j and the switch SWj are turned on, and the converter 211_j and the compensation circuit 620 are activated. The positive electrode of the single cell CELLj provides the operating current I OPj and the sampling current I 1_j to the converter 211_j through its corresponding first path. The detection unit 621 samples the operating current I OPj and the sampling current I 1_j and generates a reference current I proportional to the sum of the operating current I OPj and the sampling current I 1_j . The compensation unit 622 generates a compensation current I REFj according to the reference current I REFj . The compensation current I COMj . The compensation current I COMjCompensate the current on the first path corresponding to the single battery CELLj. Due to the compensating current I COMj , the current flowing through the first path corresponding to the single battery CELLj is reduced. In an ideal state, by reasonably setting the parameters of relevant components, the compensating current I COMj (j = 2 or 3) is approximately equal to the sum of the working current I OPj and the sampling current I 1_j , so that the total current flowing through the first path corresponding to the converter 211_j is approximately zero. During this period, since the switching unit 212_(j + 1) is in the off state, the current flowing through the second path corresponding to the converter 211_j is also zero. Therefore, the converter 211_j can accurately detect the voltage of the single battery CELLj.

[0063] During the time period from t6 to t7, the controller 210C detects the voltage of the single battery CELL4. The process of detecting the voltage of the single battery CELL4 is similar to that in Figure 2 .

[0064] During the time period from t8 to t9, the controller 210C compensates for the current that the single battery CELL1 consumes less than other single batteries. The switching unit 212_1 and the switch SW2 are turned on again, and the converter 211_1 and the compensation circuit 620 are activated. The positive electrode of the single battery CELL1 provides the working current I OP1 and the sampling current I 1_1 for the converter 211_1. The compensation circuit 620 samples the working current I OP1 and the sampling current I 1_1 , and generates a balancing current I OP1 proportional to the sum of the working current I 1_1 and the sampling current I BL . This balancing current I BL flows from the negative electrode of the single battery CELL1 to the positive electrode of the single battery CELL1. In this example, this balancing current I BL only increases the current flowing through the single battery CELL1. In an ideal state, by reasonably setting the parameters of relevant components, this balancing current I BL is approximately equal to the sum of the working current I OP1 and the sampling current I 1_1 . This method can accurately compensate for the current that the single battery CELL1 consumes less.

[0065] In this embodiment, t1–t0 = t3–t2 = t5–t4 = t7–t6 = t9–t8. In other embodiments, t1–t0, t3–t2, t5–t4, t7–t6, and t9–t8 may not be equal.

[0066] Figure 8 Another timing diagram showing the conduction of each switch of the controller 210C in Figure 6 is as follows. During the time period from t0 to t6, the process of detecting the voltages of the individual single cells CELL1, CELL2, and CELL3 is similar to that in Figure 7 .

[0067] During the time period from t6 to t7, the controller 210C detects the voltage of the individual battery CELL4. The switch unit 212_4 is turned on and the switch unit 212_5 is turned off. The converter 211_4 detects the voltage of the individual battery CELL4 and generates a sampled voltage V SAM4 indicating the voltage of the individual battery CELL4. The compensation circuit 620 turns on any one of the switch units 212_1 - 212_3 and samples the operating current of the operational amplifier corresponding to the switch unit and the sampled voltage V SAM4 to generate an equalization current I BL . Among them, the equalization current I BL flows from the negative electrode of the individual battery CELL1 to the positive electrode of the individual battery CELL1. In this example, the equalization current I BL only increases the current flowing through the individual battery CELL1. This method can compensate for the current less consumed by the individual battery CELL1 while detecting the voltage of the individual battery CELL4, saving time and reducing additional power consumption.

[0068] In this embodiment, t1–t0 = t3–t2 = t5–t4 = t7–t6. In other embodiments, t1–t0, t3–t2, t5–t4, and t7–t6 may not be equal. Figure 8 In the example of BL , when detecting the voltage of the individual battery CELL4, the compensation circuit 620 generates an equalization current I BL . In other examples, when detecting other individual batteries (such as CELL3), the compensation circuit 620 generates an equalization current I

[0069] based on the operating current of the operational amplifier corresponding to the detected individual battery and the sampled voltage. Figure 7 and Figure 8 In the embodiments shown, the compensation current generated by the compensation circuit 620 is used to make the total current on the first path corresponding to the converters 211_2 and 211_3 approximately equal to zero, and the equalization current generated by the compensation circuit 620 is used to make the current flowing through the individual battery CELL1 approximately equal to the current flowing through other individual batteries during the detection period T. Therefore, while enabling each converter to accurately detect the voltage of each individual battery, it also solves the problem of shortening the service life of the battery pack due to unequal currents flowing through each individual battery.

[0070] Figure 9 Shown is a flowchart 900 of a battery voltage detection method according to an embodiment of the present invention.

[0071] Step 901: Connect a plurality of converters to the positive electrodes of a plurality of single cells respectively via a plurality of switch units.

[0072] Step 902: Turn on the switch unit corresponding to a single cell, so that the positive electrode of this single cell provides a working current and a sampling current to the corresponding converter through a corresponding first path, and the working current flows from the positive electrode of this single cell through the corresponding converter to the ground.

[0073] Step 903: Detect the voltage of this single cell by using the corresponding converter.

[0074] As described above, the present invention discloses a controller and a battery voltage detection method. The present invention reduces the difference between the current on the first path between the converter and the positive electrode of its corresponding single cell and the current on the second path between the converter and the negative electrode of its corresponding single cell, so that each converter can accurately detect the voltage of each single cell.

[0075] The above specific embodiments and the drawings are only common embodiments of the present invention. Obviously, various additions, modifications, and substitutions can be made without departing from the spirit and scope of the present invention defined by the claims. Those skilled in the art should understand that the present invention can vary in form, structure, layout, proportion, material, element, component, and other aspects according to the specific environment and working requirements in actual applications without departing from the invention criteria. Therefore, the embodiments disclosed herein are for illustrative purposes only and not for limitation, and the scope of the present invention is defined by the appended claims and their legal equivalents, rather than being limited to the previous description.

Claims

1. A battery voltage detection method for detecting the voltages of a plurality of individual batteries in a battery pack, each of the plurality of individual batteries being respectively coupled to a corresponding one of a plurality of converters, the plurality of converters being coupled to the positive electrodes of the plurality of individual batteries via a plurality of switching units, the positive electrode of each individual battery being connected to the corresponding converter through a corresponding one of a plurality of first paths, and the negative electrode of each individual battery being connected to the corresponding converter through a corresponding one of a plurality of second paths, characterized in that The method includes: Turn on one of the multiple switch units, where the switch unit corresponds to one of the multiple single cells, so that the positive electrode of the single cell supplies working current and sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the working current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground; and Use the converter corresponding to the single cell to detect the voltage of the single cell. Wherein, selectively turn on two switch units respectively corresponding to two adjacent single cells among the multiple single cells, so that two adjacent converters corresponding to the two adjacent single cells are activated and other converters are turned off. Among them, the upper converter among the two adjacent converters receives the working current and the sampling current provided by the positive electrode of the upper single cell among the two adjacent single cells through the first path corresponding to the upper single cell among the multiple first paths, and the working current and sampling current provided by the positive electrode of the lower single cell among the two adjacent single cells flow through the second path corresponding to the upper single cell among the multiple second paths; and Use the upper converter to detect the voltage of the upper single cell.

2. The method according to claim 1, wherein The method further includes: Control the duty cycle of the on-time of the switch units respectively corresponding to the two adjacent single cells to reduce the average value of the difference between the currents flowing through each of the multiple single cells.

3. A battery voltage detection method for detecting the voltages of a plurality of single cells in a battery pack, each of the plurality of single cells being respectively coupled to a corresponding one of a plurality of converters, the plurality of converters being coupled to the positive electrodes of the plurality of single cells via a plurality of switch units, the positive electrode of each single cell being connected to the corresponding converter through a corresponding one of a plurality of first paths, and the negative electrode of each single cell being connected to the corresponding converter through a corresponding one of a plurality of second paths, characterized in that, The method includes: Turn on one of the multiple switch units, where the switch unit corresponds to one of the multiple single cells, so that the positive electrode of the single cell supplies working current and sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the working current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground; and Use the converter corresponding to the single cell to detect the voltage of the single cell. Wherein, turn on the multiple switch units to activate the multiple converters. Among them, each of the multiple converters receives the working current and sampling current provided by the positive electrode of the corresponding single cell among the multiple single cells through the first path corresponding to the converter among the multiple first paths, and the working current and the sampling current provided by the positive electrode of the lower single cell adjacent to the corresponding single cell flow through the second path corresponding to the converter among the multiple second paths.

4. A battery voltage detection method for detecting the voltages of a plurality of individual batteries in a battery pack, each of the plurality of individual batteries being respectively coupled to a corresponding one of a plurality of converters, the plurality of converters being coupled to the positive electrodes of the plurality of individual batteries via a plurality of switching units, the positive electrode of each individual battery being connected to the corresponding converter through a corresponding one of a plurality of first paths, and the negative electrode of each individual battery being connected to the corresponding converter through a corresponding one of a plurality of second paths, characterized in that, The method includes: Turn on one of the multiple switch units, where the switch unit corresponds to one of the multiple single cells, so that the positive electrode of the single cell supplies working current and sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the working current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground; and Use the converter corresponding to the single cell to detect the voltage of the single cell. Among them, a mirror unit is used to copy the working current and sampling current of the first converter among the multiple converters corresponding to the first single battery in the multiple single batteries, so as to reduce the difference between the current flowing through the first path corresponding to the first converter among the multiple first paths and the current flowing through the second path corresponding to the first converter among the multiple second paths, where the mirror unit is coupled to the second path corresponding to the first converter.

5. The method according to claim 4, wherein The copying step includes: Using the mirror unit to generate a first copy current proportional to the working current according to the working current; and Using the mirror unit to generate a second copy current proportional to the sampling current according to the sampling current, wherein the working current and the sampling current flow through the first path corresponding to the first converter, and the first copy current and the second copy current flow through the second path corresponding to the first converter.

6. The method according to claim 5, wherein The mirror unit includes a first branch, a second branch and a third branch; the sampling current flows through the first branch; the second branch generates the first copy current; the first copy current flows from the second path corresponding to the first converter to the second branch; The third branch generates the second copy current; the second copy current flows from the second path corresponding to the first converter to the third branch.

7. The method according to claim 4, characterized in that, The method further includes: Selectively turning on the switch unit corresponding to the first single battery among the multiple switch units, so that the first converter is started and other converters among the multiple converters are turned off; Starting the mirror unit to copy the current flowing through the first path corresponding to the first converter; and Using the first converter to detect the voltage of the first single battery.

8. The method according to claim 7, wherein The method further includes: Controlling the duty cycle of the conduction time of the multiple switch units to reduce the average value of the difference between the currents flowing through the multiple single batteries.

9. A battery voltage detection method for detecting the voltages of multiple single batteries in a battery pack, each of the multiple single batteries is respectively coupled to a corresponding converter among multiple converters, the multiple converters are coupled to the positive electrodes of the multiple single batteries via multiple switch units, the positive electrode of each single battery is connected to the corresponding converter through the corresponding first path among multiple first paths, and the negative electrode of each single battery is connected to the corresponding converter through the corresponding second path among multiple second paths, characterized in that Turning on one of the multiple switch units, the switch unit corresponding to one of the multiple single batteries, so that the positive electrode of the single battery provides a working current and a sampling current for the converter corresponding to the single battery through the first path corresponding to the single battery, and the working current flows from the positive electrode of the single battery through the converter corresponding to the single battery to the ground; and Using the converter corresponding to the single battery to detect the voltage of the single battery, wherein the multiple single batteries include a top single battery, and the method further includes: Copy the operating current and the sampling current of the converter corresponding to the top single cell among the multiple converters by using a mirror unit, so as to reduce the difference between the current flowing through the first path corresponding to the converter among the multiple first paths and the current flowing through the second path corresponding to the converter among the multiple second paths, wherein the mirror unit is coupled to the second path corresponding to the converter; and Generate a compensation current by using a compensation circuit to compensate the current flowing through the first path corresponding to the first single cell among the multiple single cells.

10. The method according to claim 9, wherein The compensation circuit includes a detection unit and a compensation unit, and the step of generating the compensation current includes:[[]] Sample the operating current and the sampling current of the first converter corresponding to the first single cell by using the detection unit; Generate a reference current proportional to the sum of the operating current and the sampling current of the first converter by using the detection unit; Generate the compensation current proportional to the reference current by using the compensation unit; and Compensate the current flowing through the first path corresponding to the first single cell by using the compensation current.

11. The method according to claim 9, wherein The method further includes:[[]] Generate a balancing current flowing from the negative electrode to the positive electrode of the top single cell by using the compensation circuit to reduce the difference between the current flowing through the top single cell and the current flowing through other single cells among the multiple single cells.

12. The method according to claim 11, wherein The method further includes:[[]] Detect the voltage of each single cell among the multiple single cells once respectively; Start the converter corresponding to the top single cell; Receive the operating current and the sampling current provided by the top single cell by using the converter corresponding to the top single cell; and Generate the balancing current proportional to the sum of the operating current and the sampling current provided by the top single cell by using the compensation circuit.

13. A controller for detecting the voltages of a plurality of individual cells in a battery pack, characterized in that, The controller includes:[[]] Multiple converters coupled to the multiple single cells, wherein the positive electrode of each single cell among the multiple single cells is connected to the corresponding converter among the multiple converters through the corresponding first path among the multiple first paths, and the negative electrode of each single cell is connected to the corresponding converter through the corresponding second path among the multiple second paths; and Multiple switch units coupled between the multiple single cells and the multiple converters, wherein the multiple converters are connected to the positive electrodes of the multiple single cells through the multiple switch units, wherein when the switch unit corresponding to one single cell among the multiple single cells is turned on, the positive electrode of the single cell provides the operating current and the sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the operating current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground, Wherein, the controller selectively turns on two switching units respectively corresponding to two adjacent single cells among the multiple single cells, so that two adjacent converters respectively corresponding to the two adjacent single cells are activated and other converters are turned off. Among them, the upper converter in the two adjacent converters receives the working current and sampling current provided by the positive electrode of the upper single cell through the first path corresponding to the upper single cell among the multiple first paths, and the working current and sampling current provided by the positive electrode of the lower single cell among the two adjacent single cells flow through the second path corresponding to the upper single cell among the multiple second paths.

14. The controller according to claim 13, characterized in that, The controller controls the duty cycle of the conduction time of the two switching units to reduce the average value of the difference between the currents flowing through each single cell among the multiple single cells.

15. A controller for detecting the voltages of a plurality of single cells in a battery pack, characterized in that, The controller includes: Multiple converters coupled to the multiple single cells, wherein the positive electrode of each single cell among the multiple single cells is connected to the corresponding converter among the multiple converters through the corresponding first path among the multiple first paths, and the negative electrode of each single cell is connected to the corresponding converter through the corresponding second path among the multiple second paths; and Multiple switching units coupled between the multiple single cells and the multiple converters, wherein the multiple converters are connected to the positive electrodes of the multiple single cells via the multiple switching units, Wherein, when the switching unit corresponding to a single cell among the multiple single cells is turned on, the positive electrode of the single cell provides the working current and sampling current to the converter corresponding to the single cell through the first path corresponding to the single cell, and the working current flows from the positive electrode of the single cell through the converter corresponding to the single cell to the ground. Wherein, the controller turns on the multiple switching units to activate the multiple converters. Among them, each converter among the multiple converters receives the working current and the sampling current provided by the positive electrode of the corresponding single cell among the multiple single cells through the first path corresponding to the converter among the multiple first paths, and the working current and the sampling current provided by the positive electrode of the lower single cell adjacent to the corresponding single cell flow through the second path corresponding to the converter among the multiple second paths.

16. A controller for detecting the voltages of a plurality of individual cells in a battery pack, characterized in that, The controller includes: Multiple converters coupled to the multiple single cells, wherein the positive electrode of each single cell among the multiple single cells is connected to the corresponding converter among the multiple converters through the corresponding first path among the multiple first paths, and the negative electrode of each single cell is connected to the corresponding converter through the corresponding second path among the multiple second paths; and Multiple switching units coupled between the multiple single cells and the multiple converters, wherein the multiple converters are connected to the positive electrodes of the multiple single cells via the multiple switching units, Wherein, when a switching unit corresponding to one of the plurality of single-cell batteries is turned on, the positive electrode of the single-cell battery supplies a working current and a sampling current to the converter corresponding to the single-cell battery through a first path corresponding to the single-cell battery. The working current flows from the positive electrode of the single-cell battery through the converter corresponding to the single-cell battery to the ground. Wherein, the controller further includes: A mirror unit, coupled to a second path corresponding to a first converter among the plurality of second paths, wherein the first converter corresponds to a first single-cell battery among the plurality of single-cell batteries, and the mirror unit replicates the working current and the sampling current of the first converter to reduce the difference between the current flowing through the first path corresponding to the first converter among the plurality of first paths and the current flowing through the second path corresponding to the first converter among the plurality of second paths.

17. The controller according to claim 16, characterized in that, The mirror unit generates a first replicated current proportional to the working current and a second replicated current proportional to the sampling current. Wherein, the working current and the sampling current flow through the first path corresponding to the first converter, and the first replicated current and the second replicated current flow through the second path corresponding to the first converter.

18. The controller according to claim 17, wherein The mirror unit includes a first branch, a second branch, and a third branch. The sampling current flows through the first branch; the second branch generates the first replicated current; the first replicated current flows from the second path corresponding to the first converter to the second branch; the third branch generates the second replicated current; the second replicated current flows from the second path corresponding to the first converter to the third branch.

19. The controller according to claim 16, wherein The controller selectively turns on the switching unit corresponding to the first single-cell battery among the plurality of switching units, so that the first converter is started and other converters among the plurality of converters are turned off, and the mirror unit replicates the current flowing through the first path corresponding to the first converter.

20. The controller according to claim 19, wherein, The controller controls the duty cycle of the conduction time of the plurality of switching units to reduce the average value of the difference between the currents flowing through the plurality of single-cell batteries.

21. A controller for detecting the voltages of a plurality of individual cells in a battery pack, characterized in that, The controller includes: A plurality of converters coupled to the plurality of single-cell batteries, wherein the positive electrode of each single-cell battery among the plurality of single-cell batteries is connected to the corresponding converter among the plurality of converters through a corresponding first path among the plurality of first paths, and the negative electrode of each single-cell battery is connected to the corresponding converter through a corresponding second path among the plurality of second paths; and A plurality of switching units coupled between the plurality of single-cell batteries and the plurality of converters, wherein the plurality of converters are connected to the positive electrodes of the plurality of single-cell batteries through the plurality of switching units. Wherein, when the switch unit corresponding to one of the plurality of single-cell batteries is turned on, the positive electrode of the single-cell battery supplies operating current and sampling current to the converter corresponding to the single-cell battery through a first path corresponding to the single-cell battery, and the operating current flows from the positive electrode of the single-cell battery through the converter corresponding to the single-cell battery to ground. Wherein, the plurality of single-cell batteries includes a top single-cell battery, and the controller further includes: A mirror unit, coupled to the converter corresponding to the top single-cell battery among the plurality of converters, for replicating the operating current and the sampling current of the converter to reduce the difference between the current flowing through the first path corresponding to the converter among the plurality of first paths and the current flowing through the second path corresponding to the converter among the plurality of second paths; and A compensation circuit, coupled to the plurality of converters, for generating a compensation current to compensate for the current flowing through the first path corresponding to the first single-cell battery among the plurality of single-cell batteries.

22. The controller according to claim 21, wherein The compensation circuit includes: A detection unit, for sampling the operating current and the sampling current of the first converter corresponding to the first single-cell battery, and generating a reference current proportional to the sum of the operating current and the sampling current of the first converter; and A compensation unit, for generating the compensation current proportional to the reference current.

23. The controller according to claim 21, wherein, The compensation circuit is further configured to generate a balancing current flowing from the negative electrode of the top single-cell battery to the positive electrode of the top single-cell battery to reduce the difference between the current flowing through the top single-cell battery and the current flowing through other single-cell batteries among the plurality of single-cell batteries.

24. The controller according to claim 23, wherein The controller respectively detects the voltage of each single-cell battery among the plurality of single-cell batteries once and starts the converter corresponding to the top single-cell battery. The converter receives the operating current and the sampling current provided by the top single-cell battery, and the compensation circuit generates the balancing current proportional to the sum of the operating current and the sampling current provided by the top single-cell battery.

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