TWI515997B - Battery voltage balancing regulator and method thereof - Google Patents

Description

Battery voltage equalization regulator and method thereof

The present invention relates to a battery voltage equalization regulator and a method thereof, and more particularly to a battery voltage equalization regulator and a method thereof for improving voltage balancing efficiency.

In general, in different environmental applications, the battery needs to be connected in series in order to achieve the required operating voltage. In addition, when the series battery is used for a period of time, the series battery needs to be charged. However, the characteristics of the battery may be inconsistent during the manufacturing process, so that when the series charging is performed, a part of the battery voltage in the series battery may exceed a prescribed voltage, and another part of the battery may have a insufficient charging voltage. In order to improve the aforementioned problem, a battery voltage equalization regulator can be added to control the charging voltage of each battery to equalize the voltage of each battery in the series battery pack.

Conventional battery equalization techniques, such as the US Patent No. 6,801,014, Battery equalizer using total string current, discloses a battery voltage equalizer 1. Referring to FIG. 1, the battery voltage equalizer 1 includes a DC-DC converter 11 and a capacitor bank 12, and the connection is applied to a battery pack 13. The battery voltage equalizer 1 is a structure using a flyback transformer. The primary side of the DC-DC converter 11 is a single winding, and the secondary side of the DC-DC converter 11 is a multiple winding, and is for a different number of batteries. The battery pack 13 connected in series corresponds to the number of multiple windings on the secondary side of the DC-DC converter 11.

Referring again to FIG. 1, the entire set of voltages of the battery pack 13 connected in series is used as a reference, and the battery of the lowest voltage in the battery pack 13 is charged. Therefore, when the voltage of any one of the batteries of the battery pack 13 is the lowest, the diode connected to the battery pack 13 of the lowest voltage is preferentially turned on, so that the voltage of the secondary side winding Ns corresponding to the battery pack 13 is clamped at The battery voltage of the battery pack 13 (i.e., the lowest voltage), and the remaining secondary winding Ns voltages are also clamped at the lowest voltage. Theoretically, in the battery pack 13, only the battery of the battery pack 13 having the lowest voltage can be charged, and the remaining secondary winding Ns voltages are lower than the battery voltage of the corresponding battery pack 13, so A current flows through the remaining secondary side windings Ns , so that the remaining batteries of the battery pack 13 are not charged.

However, in practical applications, the DC-DC converter 11 has a factor of inductive magnetic flux unevenness, internal resistance of each battery of the battery pack 13, and its diode conduction voltage drop, so that the DC-DC conversion The secondary side winding Ns voltage of the device 11 may be higher than the battery voltage of the battery pack 13 corresponding thereto , so that each battery of the battery unit 13 connected in series has a current to charge the battery regardless of the voltage is high or low. . Therefore, charging a battery that does not require charging for a long time has the disadvantage of wasting power. In addition, each battery needs to correspond to a set of secondary side windings Ns having the disadvantage of increasing the volume of the battery voltage equalizer 1.

Another conventional battery equalization technique, such as the US Patent No. 8120322, the Charge equalization apparatus, discloses a charge equalization device 2. Referring to FIG. 2, the charge equalization device 2 includes a plurality of flyback transformers 211 to 21n and a plurality of DC-DC converters 221 to 22n connected to a plurality of battery packs 231 to 23n connected in series, and Each of the battery packs 231 to 23n includes a plurality of batteries. The flyback transformers 211 to 21n are flyback transformers having a turns ratio of 1:1, and each of the DC-DC converters 221 to 22n includes a flyback transformer, and each of the battery packs 231 to 23n The battery is connected to the flyback transformer.

Please refer to FIG. 2 again, each of the battery packs 231 to 23n Correspondingly connected to a set of flyback transformers 211 to 21n having a turns ratio of 1:1, the voltage equalization mode is to detect the voltage of each of the battery packs 231 to 23n connected in series. The switches of the DC-DC converters 221 to 22n to which the lowest voltage batteries of the battery packs 231 to 23n are connected are turned on, so as to utilize the energy of the remaining batteries in each of the battery packs 231 to 23n to the battery with the lowest voltage. Charging is performed to achieve a function of voltage equalization for each of the battery packs 231 to 23n. At the same time, the voltage is compared between the plurality of battery packs 231 to 23n to find the battery pack of the lowest voltage, and the rest of the battery packs 231 to 23n are reused by the flyback type transformers 211 to 21n having a turns ratio of 1:1. The energy charges the battery pack of the lowest voltage to achieve a function of generating a battery pack voltage balance between the plurality of battery packs 231 to 23n.

Referring to FIG. 2 again, the battery voltage equalization technique requires a set of the flyback transformers 211 to 21n for each of the DC-DC converters 221 to 22n. In addition, each of the battery packs 231 to 23n needs to be connected to a set of flyback type transformers 211 to 21n having a turns ratio of 1:1, so that the provision of the flyback type transformer has the disadvantage of greatly increasing the manufacturing cost, and It has the disadvantage of being bulky.

However, the battery voltage equalizer of the aforementioned U.S. Patent No. 6,801,014 and the charge equalization apparatus of U.S. Patent No. 8,120,322 have various technical disadvantages. Therefore, the conventional battery voltage equalization technology necessarily has the need to further reduce energy loss, reduce manufacturing costs, and reduce product volume. The above-mentioned patents and patent applications are merely for the purpose of the technical background of the present invention and are not intended to limit the scope of the present invention.

In view of the above, in order to meet the above technical problems and needs, the present invention provides a battery voltage equalization regulator and a method thereof, which use only a set of transformers of one-to-one winding, and the energy is formed by the turn-on of a plurality of switches. It is passed to the battery to be charged, and its switching mode is controlled to improve the voltage equalization efficiency. Therefore, it has the advantage of improving the equalizing efficiency compared with the conventional battery equalizing technology.

The main object of the preferred embodiment of the present invention is to provide a battery voltage equalization regulator and a method thereof, which use a structure consisting of a flyback transformer and a power electronic switching component. The primary winding of the Chi-type transformer feeds back the energy of the secondary winding of the flyback transformer to voltage-balance the battery of the lowest voltage in a series of battery packs, and detects the voltage of each battery during the entire charging process. Finding a battery with a minimum voltage and turning on a switch of a charging path of the lowest voltage battery, so that the entire battery energy of the series battery pack performs voltage equalization charging on the lowest voltage battery to achieve battery voltage balance adjustment. .

In order to achieve the above object, a battery voltage equalization regulator according to a preferred embodiment of the present invention includes: a DC-DC power converter including a transformer and a power switch; and a first conduction contact circuit including a first two a pole body and a plurality of first switch groups, connecting an anode end of the first diode body to a first end (common contact end) of the first switch group, and then connecting an anode end of the first diode body with The first end of the secondary winding of the transformer of the DC-DC power converter is connected, the cathode end of the first diode is connected to the highest voltage end of a series battery, and the switches of the first switch group are connected The second end is connected to the two series cells of the series battery pack; a second conductive contact circuit includes a second diode and a plurality of second switch groups, the second diode The cathode end is connected to the first end [common contact end] of the second switch group, and the cathode end of the second diode body and the second side winding of the transformer of the DC-DC power converter are second End connection, connecting the anode end of the second diode End of the lowest voltage of the series battery group, the second terminal of each switch of the second switch group are connected in series to the battery of the series between the two battery packs, the DC - DC The first end of the primary winding of the transformer of the flow energy converter is connected to the highest voltage end of the series battery, the second end of the primary winding of the transformer of the DC-DC power converter and the DC-DC power converter a first end of the power switch is connected, and a second end of the power switch of the DC-DC power converter is connected to a lowest voltage end of the series battery pack; and a controller detects each of the series battery packs a battery voltage, and the controller determines a minimum voltage battery and a highest voltage battery, the controller determines whether the voltage difference between the highest voltage battery of the series battery and the lowest voltage battery is greater than a set value, Determining whether to drive the power switch; wherein when the voltage difference between the battery of the lowest voltage of the series battery and the battery of the highest voltage is greater than the set value, the battery of the lowest voltage needs to be voltage-balanced, so that the first The conduction contact circuit and the second conduction contact circuit need to drive the switch of the first switch group of the circuit through which the battery needs to be charged via the controller and Switch the second switch group.

The transformer of the preferred embodiment of the invention is selected from a flyback transformer.

In the preferred embodiment of the invention, the transformer employs a one-to-one winding transformer.

In a preferred embodiment of the present invention, the anode end of the first diode is connected to the first end (common contact end) of the first switch group, and then the anode end of the first diode is connected to the transformer The first end of the secondary winding is connected, the cathode end of the first diode is connected to the positive terminal (the highest voltage end) of the uppermost end of the series battery, and the second end of each switch of the first switch group is Connected to the two series cells of the series battery pack.

In a preferred embodiment of the present invention, the cathode end of the second diode is connected to the first end [common contact end] of the second switch group, and then the cathode end of the second diode is connected to the transformer The second end of the secondary winding is connected, and the anode end of the second diode is connected to the lowermost of the series battery The negative end of the terminal (the lowest voltage end), the second end of each switch of the second switch group is respectively connected between the two series batteries of the series battery pack, and the transformer of the DC-DC power converter is once a first end of the side winding is connected to a positive terminal (a highest voltage end) of the uppermost end of the series battery pack, and a second end of the primary winding of the transformer of the DC-DC power converter is connected to the DC-DC power conversion The first end of the power switch of the device, and the second end of the power switch of the DC-DC power converter is connected to the lower end (lowest voltage end) of the lowermost end of the series battery pack.

In order to achieve the above object, a battery voltage equalization adjustment method according to a preferred embodiment of the present invention includes: detecting, by a controller, a battery voltage of a series battery pack, and determining, by the controller, a minimum voltage battery; Comparing the lowest voltage battery of the series battery pack, the controller determines the highest voltage battery of the series battery pack; determining whether the voltage difference between the highest voltage battery and the lowest voltage battery is greater than a set value to determine whether to drive A power switch of a DC-DC power converter; and when the voltage difference between the lowest voltage battery and the highest voltage battery of the series battery pack is greater than the set value, the battery of the lowest voltage needs to be voltage-balancedly charged.

In a preferred embodiment of the present invention, when it is determined that the voltage difference between the highest voltage battery and the lowest voltage battery is less than the set value, the power switch of the DC-DC power converter does not need to be switched.

In the preferred embodiment of the present invention, when the battery of the lowest voltage is charged, a first conductive contact circuit and a second conductive contact circuit are required to drive the first circuit of the battery to be charged via the controller. The switch of the switch group and the switch of the second switch group.

In a preferred embodiment of the present invention, when the power switch of the DC-DC power converter is turned on, the energy of the series battery pack is stored in the DC The primary winding of the transformer of the DC power converter.

In a preferred embodiment of the present invention, when the power switch of the DC-DC power converter is turned off, the primary winding energy of the transformer of the DC-DC power converter is fed back to the secondary winding of the transformer of the DC-DC power converter. .

1‧‧‧ battery voltage equalizer

11‧‧‧DC-DC converter

12‧‧‧Capacitor group

13‧‧‧Battery Pack

2‧‧‧Charging equalization equipment

211‧‧‧Return-type transformer

21n‧‧‧Return-type transformer

221‧‧‧DC-DC converter

22n‧‧‧DC-DC Converter

231‧‧‧Battery Pack

23n‧‧‧Battery Pack

3‧‧‧Battery voltage equalization regulator

31‧‧‧DC-DC Power Converter

311‧‧‧Transformer

312‧‧‧Power switch

32‧‧‧First conduction contact circuit

321‧‧‧First Diode

322‧‧‧First switch group

33‧‧‧Second conduction contact circuit

331‧‧‧Secondary

332‧‧‧Second switch group

34‧‧‧ Controller

Fig. 1 is a schematic view showing the structure of a battery voltage equalizer of U.S. Patent No. 6,801,014.

Figure 2: Schematic diagram of the structure of the charging equalization device of U.S. Patent No. 8120322.

Figure 3 is a block diagram showing the structure of a battery voltage equalization regulator in accordance with a preferred embodiment of the present invention.

Figure 4 is a schematic diagram of a battery voltage equalization adjustment method in accordance with a preferred embodiment of the present invention.

FIG. 5A is a schematic diagram of a path for storing energy by a battery voltage equalization regulator according to a preferred embodiment of the present invention.

FIG. 5B is a schematic diagram of a path for charging a battery voltage equalization regulator according to a preferred embodiment of the present invention.

In order to fully understand the present invention, the preferred embodiments of the present invention are described in detail below, and are not intended to limit the invention.

The battery voltage equalization regulator of the preferred embodiment of the present invention is applicable to various power systems requiring battery charging equipment, such as: Uninterruptible Power Supply (UPS), backup power supply and electric vehicle, but it is not used to limit The scope of the invention. The battery voltage equalization adjustment method of the preferred embodiment of the present invention is applicable to charging technologies of various rechargeable batteries, but it is not intended to limit the scope of the present invention.

Figure 3 is a diagram showing battery voltage equalization in accordance with a preferred embodiment of the present invention. Schematic diagram of the regulator, which contains four main blocks. 4 is a schematic diagram showing a battery voltage equalization adjustment method according to a preferred embodiment of the present invention, which merely illustrates a battery voltage equalization regulator suitable for use in the present invention, which corresponds to FIG.

Referring to FIG. 3, the battery voltage equalization regulator 3 of the preferred embodiment of the present invention includes a DC-DC power converter 31, a first conduction contact circuit (upper conduction contact circuit) 32, and a first A two-conductor contact circuit [lower-end conduction contact circuit] 33 and a controller 34. The DC-DC power converter 31 includes a transformer 311 and a power switch 312, and the transformer 311 is selected from a flyback transformer, and the transformer 311 employs a transformer of a pair of windings.

Referring to FIG. 3 again, the first conductive contact circuit 32 includes a first diode 321 and a plurality of first switch groups 322. Connecting the anode end of the first diode 321 of the first conductive contact circuit 32 to the first end (common contact end) of the first switch group 322, and then the first conductive contact circuit 32 The anode end of the diode 321 is connected to the first end (non-tapping end) of the secondary winding Ns of the transformer 311 of the DC-DC power converter 31. In addition, the cathode end of the first diode 321 of the first conduction contact circuit 32 is connected to the positive terminal (the highest voltage terminal) of the uppermost end of the series battery packs B1 to Bn, and the first conduction contact circuit is The second ends of the respective switches of the first switch group 322 of 32 are connected between the two series cells of the series battery packs B1 to Bn.

Referring to FIG. 3 again, the second conductive contact circuit 33 includes a second diode 331 and a plurality of second switch groups 332. Connecting the cathode end of the second diode 331 of the second conductive contact circuit 33 to the first end (common contact end) of the second switch group 332, and then the second conductive contact circuit 33 The cathode end of the diode 331 is connected to the second end [punch end] of the secondary winding Ns of the transformer 311 of the DC-DC power converter 31. In addition, the anode terminal of the second diode 331 of the second conduction contact circuit 33 is connected to the negative terminal (the lowest voltage terminal) of the lowermost end of the series battery packs B1 to Bn, and the second conduction contact circuit is The second ends of the respective switches of the second switch group 332 of 33 are connected between the two series cells of the series battery packs B1 to Bn. In addition, the first end (the dot end) of the primary winding Np of the transformer 311 of the DC-DC power converter 31 is connected to the positive terminal (the highest voltage terminal) of the uppermost end of the series battery packs B1 to Bn, and the A second end [non-tapping end] of the primary side winding Np of the transformer 311 of the DC-DC power converter 31 is connected to the first end of the power switch 312, and the second end of the power switch 312 is connected to the series battery pack The lower end of the lower end of B1 to Bn (lowest voltage end).

Referring to FIG. 3 and FIG. 4 again, the battery voltage equalization adjustment method according to the preferred embodiment of the present invention includes the step S1: the battery voltage equalization regulator 3 can use the controller 34 to detect the serial battery packs B1 to Bn. Each battery voltage is determined by the controller 34 to determine the lowest voltage battery. The battery voltage equalization adjustment method of the preferred embodiment of the present invention includes the step S2: when comparing the lowest voltage battery of one of the series battery packs B1 to Bn, the controller 34 determines the highest voltage of one of the series battery packs B1 to Bn. battery. The battery voltage equalization adjustment method of the preferred embodiment of the present invention includes the step S3: the controller 34 determines whether the voltage difference between the battery of the highest voltage of the series battery packs B1 to Bn and the battery of the lowest voltage is greater than a set value to determine Whether to drive the power switch 312 of the DC-DC power converter 31.

Referring to FIGS. 3 and 4, the battery voltage equalization adjustment method according to the preferred embodiment of the present invention includes the step S4: when the difference between the lowest voltage and the highest voltage of the series battery packs B1 to Bn is greater than the set value, The battery of the lowest voltage needs to be charged.

Referring to FIGS. 3 and 4 again, when the battery voltages of the series battery packs B1 to Bn are substantially the same, the power switch 312 does not need to be switched, that is, the highest among the series battery packs B1 to Bn is determined. Voltage When the voltage difference between the battery and the lowest voltage battery is less than the set value, the power switch 312 does not need to be switched. Because in the voltage equalization process, some energy is inevitably consumed in the switching loss of the transformer 311 and the power switch 312. Conversely, when the voltage difference between the battery of the lowest voltage of the series battery packs B1 to Bn and the highest voltage battery is greater than the set value, the battery of the lowest voltage needs to be charged, so that the first conductive contact circuit 32 The switch of the first switch group 322 and the switch of the second switch group 332 for driving the battery to be charged by the controller 34 are required to be driven by the controller 34.

FIG. 5A is a schematic diagram showing the path of storing energy by the battery voltage equalization regulator of the preferred embodiment of the present invention. FIG. 5B is a schematic diagram showing the path of charging of the battery voltage equalization regulator according to the preferred embodiment of the present invention, which corresponds to FIG. 5A. Referring to FIGS. 3 and 5A, when the battery B2 forms the lowest voltage and the voltage difference between the batteries of the highest voltage of the series battery packs B1 to Bn is greater than the set value, the controller 34 drives the power switch. The 312 switching, as shown by the dashed line in FIG. 5A, is a schematic diagram of the path of the current after the power switch 312 is turned on.

Referring to FIGS. 3 and 5B, when the power switch 312 is turned on, the energy of the series battery packs B1 to Bn is stored in the primary side winding Np of the transformer 311. At the same time, the controller 34 also drives the switch S11 of the first switch group 322 and the switch S22 of the second switch group 332 through the circuit when the battery B2 is charged. When the power switch 312 is turned off, the primary side winding Np energy of the transformer 311 is fed back to the secondary side winding Ns . As shown by the broken line in FIG. 5B, the path of the current after the power switch 312 is turned off is shown. The side winding Np energy passes through the secondary side winding Ns of the transformer 311 [non-tapping end], the switch S11 of the first switch group 322, the positive polarity of the battery B2, the negative polarity of the battery B2, and the second switch group 332. The switch S22 and the secondary winding Ns [tapping end] of the transformer 311 form a loop, thereby completing charging of the battery B2.

Referring to FIGS. 3, 5A and 5B again, the battery voltage equalization regulator 3 only needs a set of one-to-one windings of the transformer 311, and does not need to use a one-to-many transformer winding to correspond to a plurality of batteries. There is no need for one battery corresponding to a group of transformers, the production cost can be reduced, and the volume of the product can be further miniaturized, and the controller 34 detects each battery voltage of the series battery packs B1 to Bn to determine the startup voltage equalization charging. Whether or not to improve the battery pressure equalization efficiency.

The battery voltage equalization adjustment method of the preferred embodiment of the present invention can make the voltage of each battery tend to be close after execution for a period of time, because the series battery packs B1 to Bn have partial energy consumption during the voltage equalization process. The switching loss of the transformer 311 and the power switch 312 is such that, after charging for a period of time, if the voltages of the respective batteries are relatively close, the control signal of the power switch 312 of the DC-DC power converter 31 is turned off, so that The power switch 312 is turned off to stop voltage equalization charging.

The battery voltage equalization adjustment method of the preferred embodiment of the present invention forms a DC-DC power converter with a flyback transformer and a power electronic switching component as a structure, and the entire battery of the series battery packs B1 to Bn is paired with a single battery. When the voltage is charged, the volume of the transformer 311 is not increased by the number of series connected batteries of the series battery packs B1 to Bn, which can effectively reduce the volume saving cost of the transformer. In addition, each battery voltage is detected to determine the time required to determine the voltage-balanced charging battery and the startup voltage equalization charging to improve the overall voltage equalization efficiency.

The foregoing preferred embodiments are merely illustrative of the invention and the technical features thereof, and the techniques of the embodiments can be carried out with various substantial equivalent modifications and/or alternatives; therefore, the scope of the invention is subject to the appended claims. The scope defined by the scope shall prevail. The copyright limitation of this case is used for the purpose of patent application in the Republic of China.

3‧‧‧Battery voltage equalization regulator

31‧‧‧DC-DC Power Converter

311‧‧‧Transformer

312‧‧‧Power switch

32‧‧‧First conduction contact circuit

321‧‧‧First Diode

322‧‧‧First switch group

33‧‧‧Second conduction contact circuit

331‧‧‧Secondary

332‧‧‧Second switch group

34‧‧‧ Controller

Claims (10)

A battery voltage equalization regulator includes: a DC-DC power converter including a transformer and a power switch; a first conduction contact circuit including a first diode and a first switch group, The first switch group includes a plurality of switches, and the anode end of the first diode is connected to the first end (common contact end) of the first switch group, and then the anode end of the first diode is The first end of the secondary winding of the transformer of the DC-DC power converter is connected, the cathode end of the first diode is connected to the positive terminal of the series battery (the highest voltage end), and the first switch is connected The second end of each switch of the group is connected between two series batteries of the series battery pack; a second conductive contact circuit comprising a second diode and a second switch group, the second switch group The switch includes a plurality of switches, and the cathode end of the second diode is connected to the first end (common contact end) of the second switch group, and the cathode end of the second diode is coupled to the DC-DC power a second end of the secondary winding of the transformer of the converter is connected, The anode end of the second diode is connected to the negative terminal (lowest voltage terminal) of a series battery pack, and the second end of each switch of the second switch group is connected between the two series batteries of the series battery pack a first end of the primary winding of the transformer of the DC-DC power converter is connected to a highest voltage end of the series battery, and a second end of the primary winding of the transformer of the DC-DC power converter is connected to a first end of the power switch of the DC-DC power converter, and a second end of the power switch of the DC-DC power converter is connected to a negative terminal of the series battery pack (lowest voltage terminal); and a controller Detecting each battery voltage of the series battery pack, and determining, by the controller, a minimum voltage battery and a highest voltage battery, the controller determining the highest voltage battery and the lowest voltage battery of the series battery pack Whether the voltage difference is greater than a set value to determine whether to drive the power switch; wherein the battery of the lowest voltage of the series battery pack and the highest voltage When the voltage difference of the battery is greater than the set value, the battery of the lowest voltage needs to be voltage-balanced, so that the first conductive contact circuit and the second conductive contact circuit need to drive the battery to be charged via the controller. a switch of the first switch group of the loop and a switch of the second switch group; wherein the battery of the lowest voltage of the series battery pack is only charged by one switch of the first switch group and the second switch group, or only The charging is performed by one of the first switch group and the second switch group and one of the first diode and the second diode. The battery voltage equalization regulator of claim 1, wherein the transformer is selected from the group consisting of a flyback transformer. The battery voltage equalization regulator according to claim 1, wherein the transformer uses a one-to-one winding transformer. The battery voltage equalization regulator according to claim 1, wherein the anode end of the first diode is connected to the first end (common contact end) of the first switch group, and then the first The anode end of the diode is connected to the first end of the secondary winding of the transformer, and the cathode end of the first diode is connected to the positive terminal (the highest voltage end) of the uppermost end of the series battery, The second ends of the respective switches of the first switch group are connected between the two series cells of the series battery pack. The battery voltage equalization regulator according to claim 1, wherein the cathode end of the second diode is connected to the first end (common contact end) of the second switch group, and then the second a cathode end of the diode is connected to a second end of the secondary winding of the transformer, and an anode end of the second diode is connected to a lower end (lowest voltage end) of the lowermost end of the series battery, The second end of each switch of the second switch group is connected between the two series batteries of the series battery pack, and the first end of the primary winding of the transformer of the DC-DC power converter and the most of the series battery pack The positive terminal (highest voltage terminal) of the upper end is connected, and the second end of the primary winding of the transformer of the DC-DC power converter is connected to the first end of the power switch of the DC-DC power converter, and the DC The second end of the power switch of the DC power converter is connected to the lower end of the lowermost end of the series battery pack [Minimum voltage terminal]. A battery voltage equalization adjustment method includes: detecting, by a controller, a battery voltage of a series battery pack, and determining, by the controller, a minimum voltage battery; comparing the lowest voltage of the series battery pack In the case of a battery, the controller determines a battery having one of the highest voltages of the series battery; determining whether the difference between the highest voltage and the lowest voltage is greater than a set value to determine whether to drive one of the power switches of the DC-DC power converter; And when the difference between the lowest voltage and the highest voltage of the series battery pack is greater than the set value, the battery of the lowest voltage needs to be voltage-balancedly charged; wherein the battery of the lowest voltage of the series battery pack only needs to pass the first switch Charging each of the switches of the group and the second switch group, or charging only one switch of the first switch group and the second switch group and one of the first diode and the second diode . According to the battery voltage equalization adjustment method described in claim 6, wherein the power switch does not need to be switched when it is determined that the voltage difference between the highest voltage battery and the lowest voltage battery is less than the set value. According to the battery voltage equalization adjustment method of claim 6, wherein when the battery of the lowest voltage is charged, a first conductive contact circuit and a second conductive contact circuit are required to pass through the controller. Driving a switch of the first switch group and a switch of the second switch group of the circuit through which the rechargeable battery is to be charged. The battery voltage equalization adjustment method according to claim 6, wherein the energy of the series battery pack is stored in a primary winding of a transformer when the power switch is turned on. The battery voltage equalization adjustment method according to claim 9, wherein when the power switch is turned off, the primary side winding energy of the transformer is fed back to the secondary winding of the transformer.