VOLTAGE BALANCING SYSTEM

Abstract

The invention provides a voltage balancing system for balancing controlling of voltage of battery cells including a first set of battery cells and a second set of battery cells connected in series. The system includes a high-side analog front end (AFE) connected to the first set of battery cells, a low-side analog front end (AFE) connected to the second set of battery cells, a microcontroller communicating with the high-side AFE and the low-side AFE, and a communication isolating module interconnecting between the high-side AFE and the microcontroller. The system further includes a balancing module arranged at a back end of the low-side AFE or the high-side AFE to equalize voltages output by the low-side AFE and the high-side AFE. Compared with the prior arts, the system employs a balancing module to balance the voltages of the two sets of battery cells, which can shorten the voltage difference therebetween.

Claims

1. A voltage balancing method for controlling voltage balance in a battery pack system comprising a first set of battery cells and a second set of battery cells connected in series, the method comprising: collecting, by a high-side analog front end (AFE) connected in parallel with the first set of battery cells, a first analog voltage output from the first set of battery cells; collecting, by a low-side AFE connected in parallel with the second set of battery cells, a second analog voltage output from the second set of battery cells; transmitting, by the high-side AFE, the first analog voltage to a control module, and transmitting, by the low-side AFE, the second analog voltage to the control module; determining, by the control module, a voltage difference between the first analog voltage and the second analog voltage; generating, by the control module, a control instruction based on the voltage difference; responding, by a balancing module comprising a first balancing circuit connected between the high-side AFE and the control module and a second balancing circuit connected between the low-side AFE and the control module, to the control instruction to balance the voltage difference, the first balancing circuit comprising a first balancing switch and a first balancing resistor connected to the first balancing switch, and the second balancing circuit comprising a second balancing switch and a second balancing resistor connected to the second balancing switch; and the responding comprising: receiving, by the first balancing switch, a first drive signal from the control module; and receiving, by the second balancing switch, a second drive signal from the control module.

2. The method according to claim 1, wherein in response to a voltage sum of the first set of battery cells being greater than a voltage sum of the second set of battery cells, triggering the first balancing circuit.

3. The method according to claim 2, wherein triggering the first balancing circuit comprises: turning on, by the control module, the first balancing switch to start the first balancing circuit.

4. The method according to claim 1, wherein in response to a voltage sum of the first set of battery cells is less than a voltage sum of the second set of battery cells, triggering the second balancing circuit.

5. The method according to claim 4, wherein triggering the second balancing circuit comprises: turning on, by the control module, the second balancing switch to start the second balancing circuit.

6. The method according to claim 1, further comprising: configuring a communication isolating module between the high-side AFE and the control module to facilitate communication therebetween.

7. The method according to claim 6, wherein the communication isolating module is powered by two separate isolated power supplies which are respectively provided by the high-side AFE and the low-side AFE.

8. The method according to claim 1, wherein in response to the voltage difference being greater than 100 mV, triggering the balancing module.

9. The method according to claim 1, wherein in response to the voltage difference being less than 20mV, turning off the balancing module.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a schematic diagram showing a conventional voltage management system of battery cells.

[0018] FIG. 2 is a schematic structural diagram of a voltage balancing system in accordance with a first embodiment of the present invention.

[0019] FIG. 3 is a schematic structural diagram of one of the schemes shown in FIG. 1.

[0020] FIG. 4 a schematic structural diagram of a voltage balancing system in accordance with a second embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

[0021] The exemplary embodiment will be described in detail herein, and the embodiment is illustrated in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements. The embodiment described in the following exemplary embodiment does not represent all embodiments consistent with present invention. On the contrary, they are only examples of devices, systems, machines, and methods consistent with some aspects of the invention as detailed in the appended claims.

[0022] Reference will now be made to the drawing figures to describe the embodiments of the present disclosure in detail. In the following description, the same drawing reference numerals are used for the same elements in different drawings.

[0023] The present invention discloses a voltage balancing system, adapted for balancing controlling of voltage of battery cells in a battery pack. For the convenience and clarity of description, the following will take the battery cells including two sets of battery cells as an example for detailed description, but it should not be limited to this.

[0024] As shown in FIG. 2, the voltage balancing system comprises analog front end (AFE), microcontroller (MCU) U3, communication isolating module, low dropout regulator (LDO) U4 and balancing module 30. The LDO U4 connects between the battery cells and the microcontroller U3.

[0025] The battery cells 10 is defined to include a first set of battery cells 11 and a second set of battery cells 12, and the first set of battery cells 11 and the second set of battery cells 12 connected in series. The analog front end (AFE) is arranged in parallel with the battery cells 10, and comprises a high-side analog front end U1 connected in parallel with the first set of battery cells 11 and a low-side analog front end U2 connected in parallel with the second set of battery cells 12. The high-side analog front end U1 is used to collect the analog voltage output by the first set of battery cells 11 and transmit the collected voltage to the microcontroller U3, and the low-side analog front end U2 is used to collect the analog voltage output by the second set of battery cells 12 and transmit the collected voltage to the microcontroller U3.

[0026] Preferably, the low-side analog front end U2 communicates with the microcontroller U3 through a second communication channel 22, so that when the microcontroller U3 needs to collect the analog voltage of any battery in the second set of battery cells 12, the second communication channel 22 may be used for the transmission of instructions, and the low-side analog front end U2 will quickly detect and extract the analog value of the corresponding battery after receiving such instructions. At the same time, the low-side analog front end U2 integrates therein an ADC module, so that after the low-side analog front end U2 detects the analog voltage value of the second set of battery cells 12, it could be directly converted to the digital quantity and sent to the microcontroller U3 through the second communication channel 22.

[0027] The high-side analog front end U1 communicates with the microcontroller U3 via the communication isolating module. Specifically, the communication isolating module connects between the high-side analog front end U1 and the microcontroller U3, and connects the communicating interface of the high-side analog front end U1 with the communicating interface of the microcontroller U3, so as to realize the communication between the high-side analog front end U1 and the microcontroller U3. Preferably, the high-side analog front end U1, the communication isolating module and the microcontroller U3 communicates with each other through a first communication channel 21, and the specific communicating process thereof could refer to the communicating process between the low-side analog front end U2 and the microcontroller U3. No detailed description is given here now.

[0028] The communication isolating module is powered by two separate isolated power supplies (VCC1, VCC2), and the isolated power supply VCC1 is provided by the high-side analog front end U1, the isolated power supply VCC2 is provided by the low-side analog front end U2. The balancing module 30 is arranged at a back end of the low-side analog front end U2 or the high-side analog front end U1, which is used to balance the voltage difference between the isolated power supply VCC 1 and VCC2.

[0029] The isolated power supply VCC1 can also be understood as the voltage of the first set of battery cells 11, since the high-side analog front end U1 collects the voltage value of a single battery of the first set of battery cells 11; while the isolated power supply VCC2 can also be understood as the voltage of the second set of battery cells 12, since the low-side analog front end U2 collects the voltage value of a single battery of the second set of battery cells. Therefore, the balancing module 30 can be understood as: be used to balance the voltage of the first set of battery cells 11 and the second set of battery cells 12.

[0030] As shown in FIG. 2, it is the first embodiment of the present invention. In this embodiment, the voltage output by the high-side analog front end U1 is defined as a first voltage (ie, the isolated power supply VCC1), and the voltage output by the low- side analog front end U2 is defined as a second voltage (ie, the isolated power supply VCC2). When the voltage difference between the first voltage and the second voltage is a constant value, the balancing module 30 is a constant value balancing resistor R connected to the high-side analog front end U1 or the low-side analog front end U2.

[0031] As shown in FIG. 3, a working current of the high-side analog front end U1 is defined as a first current I1, a working current of the low-side analog front end U2 is defined as second current I2, and the first current Il and the second current I2 remain unchanged within the normal working voltage scope of corresponding analog front end. When the second current I2 is greater than the first current Il, the constant value balancing resistor R is connected to the low-side analog front end U2, at this time, the resistance R of the constant value balancing resistor=the second voltage/ (the second current-the first current), ie. VCC2/(I2-I1); while when the first current Il is greater than the second current I2, the constant value balancing resistor R is connected to the high-side analog front end U1, at this time, the resistance R of the constant value balancing resistor=the first voltage/(the first current-the second current), ie. VCC1/(I1- I2). In this way, a purpose of balancing the operating power consumption of the isolated power supply VCC1 and VCC2 is achieved, so that the voltage of the two sets of battery cells managed by the high-side analog front end U1 and the low-side analog front end U2 are not different.

[0032] As shown in FIG. 4, it is the second embodiment of the present invention. In this embodiment, the voltage output by the high-side analog front end U1 is defined as the first voltage (ie. isolating power supply VCC1), the voltage output by the low- side analog front end U2 is defined as the second voltage (ie. isolating power supply VCC 2). When the voltage difference between the first voltage and the second voltage is a non-constant value, the balancing module 30 is connected to the microcontroller 3 and composed by the balancing switch transistor and the balancing resistor.

[0033] Specifically, the balancing module 30 comprises a first balancing circuit A connected with the high-side analog front end U1 and a second balancing circuit B connected with the low-side analog front end U2. The first balancing circuit A is composed by a first balancing switch transistor 31 and a first balancing resistor 32 connected with the first balancing switch transistor 31, and the second balancing circuit B is composed by a second balancing switch transistor 33 and a second balancing resistor 34 connected with the second balancing switch transistor 33.

[0034] The first balancing switch transistor 31 also connects to output ends of the microcontroller U3 and the high-side analog front end U1, respectively, and the switch signal of the first balancing switch transistor 31 is sent from the microcontroller U3; the first balancing resistor 32 has one end thereof connected to the first balancing switch transistor 31 and the other end grounded; the second balancing switch transistor 33 also connects to the output ends of the microcontroller U3 and the low-side analog front end U2, and the switch signal of the second balancing switch transistor 33 is sent from the microcontroller U3; the second balancing resistor 34 has one end thereof connected to the second balancing switch transistor 33 and the other end grounded.

[0035] When the balancing module 30 of this embodiment is working, firstly, the microcontroller U3 collects the single battery voltage data of the first set of battery cells 11 emitted by the high-side analog front end U1, and the single battery voltage data of the second set of battery cells 12 emitted by the low-side analog front end U2; then, calculating and obtaining the voltage sum of the added-up voltage of the first set of battery cells 11 and the voltage sum of the added-up voltage of the second set of battery cells 12, respectively, and comparing the voltage sums of the two sets of battery cells; finally, when the voltage sum of the first set of battery cells 11 is greater than the voltage sum of the second set of battery cells 12, the microcontroller U3 judges and controls corresponding first balancing switch transistor 31 to turn on (ie. sending switch signals), the first balancing circuit A then starts to operate; when the voltage sum of the second set of battery cells 12 is greater than the voltage sum of the first set of battery cells 11, the microcontroller U3 judges and controls corresponding second balancing switch transistor 33 to turn on (ie. sending switch signals), the second balancing circuit B then starts to operate. In this way, the voltage difference between the two sets of battery cells managed respectively by the high-side analog front end U1 and the low-side analog front end U2 is reduced.

[0036] Of course, it is not that when the sum of the voltages of the first set of battery cells 11 must be equal to the sum of the voltages of the second set of battery cells 12, the balancing module 30 does not work. Those skilled in the art can also set a preset value in advance. When the voltage difference between the two voltage sums exceeds the preset value, the microcontroller U3 will control the corresponding balancing circuit to turn on, otherwise the microcontroller U3 can always control the corresponding balancing circuit to close. For example, the microcontroller U3 controls the corresponding balancing circuit (A or B) to start when the voltage difference between the voltage sum of the first set of battery cells 11 and the voltage sum of the second set of battery cells 12 is greater than 100mv; the microcontroller U3 controls the corresponding balancing circuit (A or B) to turn off when the voltage difference between the voltage sum of the first set of battery cells 11 and the voltage sum of the second set of battery cells 12 is less than 20mv.

[0037] In summary, the voltage equalization system of the present invention is provided with a balancing module 30 at the back end of the low-side analog front end U2 or the high-side analog front end U1, so that the balancing module 30 can be used to balance the voltages of the first set of battery cells 11 and the second set of battery cells 12 according to actual situation, so as to shorten the voltage difference between the two sets of battery cells.

[0038] The above embodiment is only used to illustrate present invention and not to limits the technical solutions described in present invention. The understanding of this specification should be based on those skilled in the art, although present invention has been described in detail with reference to the above embodiment. However, those skilled in the art should understand that those skilled in the art can still modify or equivalently replace present invention, and all technical solutions and improvements that do not depart from the spirit and scope of present invention should be within the scope of the claims of the invention.