A load balancing control method and power battery module balancing device

Abstract

The present invention discloses a load balancing control method and a power battery module balancing device, which relate to the technical field of power battery module balancing devices. The load balancing control method includes: when charging the power battery module, using a combination of multiple small-capacity power modules, and using a unified charging control signal between each power module to achieve load balancing of the power battery module; when discharging the power battery module, using a two-stage discharge strategy to adjust the discharge current to form multiple discharge channels, and multiple discharge channels use a unified discharge control signal to achieve consistent discharge currents in each discharge channel. Through the embodiments of the present invention, the loads of each power module in the power battery module can be reasonably balanced, and the balanced distribution of current on each power module can be achieved. The balanced load distribution can maximize the working efficiency of the power battery module, while improving the safety of the power battery system and the life of the power battery module balancing device.

Description

Technical Field

[0001] The present invention relates to the field of power battery balancing equipment, and in particular to a load balancing control method and a power battery module balancing equipment. Background Art

[0002] With the increasing global awareness of environmental protection, more and more people choose electric vehicles (EV) when buying cars, which makes electric vehicles more and more popular.

[0003] The core component of electric vehicles is the power battery module. In order to ensure that the current of the power battery module can be output evenly, balancing equipment is generally used to control the load balancing of each battery in the power battery module to eliminate the impact of power supply differences in the power battery module and improve the system safety of electric vehicles.

[0004] Currently, in the implementation of power battery module balancing equipment, the charging portion is basically composed of multiple small power modules. Due to individual differences between the power modules, load imbalance will occur. The discharge portion uses multiple resistors or MOS tubes (MOS tubes are MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors, abbreviated as MOSFETs) for natural discharge, which cannot achieve precise control of the discharge current. As a result, the power battery module balancing equipment cannot reasonably balance the load of each power module, reducing the operating efficiency of the power battery module and the safety of the power battery system. Summary of the Invention

[0005] The embodiments of the present invention aim to provide a load balancing control method and a power battery module balancing device, which can solve the problem that the existing power battery module balancing device cannot reasonably balance the loads of each power module, thereby reducing the working efficiency of the power battery module and the safety of the power battery system.

[0006] To solve the above technical problems, a first embodiment of the present invention provides a load balancing control method for a power battery module balancing device, the load balancing control method comprising:

[0007] When charging the power battery module, a combination of multiple small-capacity power modules is used, and a unified charging control signal is used between each power module to achieve load balancing of the power battery module;

[0008] When the power battery module is discharging, a two-stage discharge strategy is used to adjust the discharge current to form multiple discharge channels. Multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

[0009] Optionally, when charging the power battery module, the step of using a combination of multiple small-capacity power modules and using a unified charging control signal between the power modules to achieve load balancing of the power battery module includes:

[0010] When charging the power battery module, multiple small-capacity power modules are connected in parallel. The output current of each power module is consistent, achieving load balancing of the power battery module.

[0011] When charging the power battery module, multiple small-capacity power modules are connected in series, and a unified charging control signal is used between each power module to achieve consistent output current of each power module.

[0012] Optionally, the power battery module balancing device includes a first operational amplifier, a second operational amplifier, a first power module, a second power module, a two-to-one selector, a first isolated power supply, a first current sampling resistor, and a second current sampling resistor;

[0013] The steps of using a combination of multiple small-capacity power modules and using a unified charging control signal between the power modules to achieve load balancing of the power battery modules when charging the power battery module include:

[0014] After determining the operating mode of each power module in the power battery module balancing device, when charging the power battery module, the input PWM duty cycle signal is converted into a reference voltage, the first operational amplifier and the second operational amplifier use the same reference voltage, the feedback output of the first current sampling resistor is output to the negative input of the first operational amplifier, and the feedback output of the second current sampling resistor is output to the negative input of the second operational amplifier;

[0015] The first operational amplifier outputs a charging control signal to control the first power supply module;

[0016] The output of the second operational amplifier and the first isolated power supply select the charging control signal from the output of the first operational amplifier and output it to the second power supply module after being selected by the two-to-one selector, so that the second power supply module has the same charging control signal as the first power supply module.

[0017] Optionally, when the power battery module is discharging, the discharge current is adjusted using a two-stage discharge strategy, including:

[0018] The first-level discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor;

[0019] The second-stage discharge strategy includes adjusting the specific size of the discharge current through the MOS tube combined with the operational amplifier to achieve precise control of the discharge current.

[0020] Optionally, the first-level discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor, including:

[0021] Four discharge channels are configured, namely the first discharge channel, the second discharge channel, the third discharge channel and the fourth discharge channel. Each discharge channel is symmetrically distributed. Each discharge channel is configured with several discharge resistors and several switches. Each discharge resistor is connected in parallel with a switch, and the switch controls whether the discharge resistor connected in parallel with it is added to the discharge circuit.

[0022] Optionally, the first-level discharge strategy includes adjusting a discharge current range by dynamically configuring a discharge resistor, and further includes:

[0023] A first MOS transistor is configured, wherein the third discharge channel and the first discharge channel are connected in series and then connected to the drain of the first MOS transistor, and the source of the first MOS transistor is electrically connected to the first shunt;

[0024] A second MOS transistor is configured, the fourth discharge channel and the second discharge channel are connected in series and then connected to the drain of the second MOS transistor, and the source of the second MOS transistor is electrically connected to the second shunt.

[0025] Optionally, the power battery module balancing device includes a third operational amplifier, a seventh MOS transistor, an eighth MOS transistor, a third current sampling resistor, a fourth current sampling resistor, a first load resistor, a second load resistor and a second isolated power supply;

[0026] The second-stage discharge strategy includes adjusting the specific size of the discharge current through a MOS tube combined with an operational amplifier, including:

[0027] After determining the discharge operation mode of the power battery module balancing device, the power battery module balancing device converts the input PWM duty cycle signal into a reference voltage during discharge. The output of the third operational amplifier controls the seventh MOS transistor and controls the eighth MOS transistor through the second isolated power supply. The feedback of the third current sampling resistor is input to the negative input terminal of the third operational amplifier.

[0028] Using the second isolated power supply, the reference ground of the eighth MOS transistor is made consistent with the reference ground of the seventh MOS transistor;

[0029] The first load resistor and the second load resistor are equal in size and symmetrically distributed, so that the discharge currents passing through the first load resistor and the second load resistor are equal.

[0030] Optionally, the load balancing control method further includes: when the power battery module is discharging, distributing the heat generated by the discharge on a discharge resistor that is easy to dissipate heat and is selected according to a preset resistor combination selection algorithm based on the discharge current and the dynamically configured discharge resistor.

[0031] Optionally, the preset resistor combination selection algorithm includes:

[0032] a1. Measure the current voltage of the power battery module and calculate the expected discharge resistance based on the expected discharge current;

[0033] a2. Among the discharge resistor combinations, find the largest discharge resistor combination with a smaller resistance than the expected discharge resistor.

[0034] a3. Calculate the power distributed on the maximum discharge resistor and the power distributed on the MOS tube. If the maximum discharge current is greater than the expected discharge current, the expected discharge current is used for calculation; if the maximum discharge current is less than the expected discharge current, the maximum discharge current is used for calculation;

[0035] a4. If the power distributed on the MOS tube is less than the maximum power allowed, the maximum discharge resistor combination is selected for discharge; otherwise, go to step a5;

[0036] a5. Find a discharge resistor combination with a larger discharge resistance than the expected discharge resistance from the discharge resistor combination, and repeat steps a3 and a4 until a discharge power distribution on the MOS tube is found that is within the maximum allowable discharge power.

[0037] Accordingly, a second embodiment of the present invention provides a power battery module balancing device, which is applied to the load balancing control method of the power battery module balancing device described in the first embodiment of the present invention. The power battery module balancing device includes a charge balancing component and a discharge balancing component; wherein:

[0038] The charging balancing component is used to use a combination of multiple small-capacity power modules when charging the power battery module, and a unified charging control signal is used between each power module to achieve load balancing of the power battery module;

[0039] The discharge balancing component is used to adjust the discharge current using a two-stage discharge strategy when the power battery module is discharged, forming multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

[0040] Compared to the prior art, the load balancing control method and power battery module balancing device provided in the embodiments of the present invention achieve load balancing of the power battery module by combining multiple small-capacity power modules during charging, with each power module using a unified charging control signal. During discharge, a two-stage discharge strategy is used to adjust the discharge current, forming multiple discharge channels. These multiple discharge channels use a unified discharge control signal to ensure consistent discharge current across each channel. This method can reasonably balance the loads of each power module in the power battery module and achieve balanced current distribution across each power module. This balanced load distribution can maximize the operating efficiency of the power battery module, while also improving the safety of the power battery system and the lifespan of the power battery module balancing device. This method can address the problem of existing power battery module balancing devices failing to reasonably distribute the loads of each power module, resulting in unbalanced loads and reduced power battery module operating efficiency and the safety of the power battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0042] Figure 1 This is a flow chart of a load balancing control method provided by an embodiment of the present invention;

[0043] Figure 2 This is a structural diagram of a power battery module balancing device provided by an embodiment of the present invention;

[0044] Figure 3 Schematic diagram of a power battery module balancing device performing balanced charging control according to an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of a power battery module balancing device provided by an embodiment of the present invention in a parallel discharge working mode;

[0046] Figure 5 This is a schematic diagram of a power battery module balancing device provided by an embodiment of the present invention in a series discharge working mode;

[0047] Figure 6 Schematic diagram of a power battery module balancing device performing balanced discharge control according to an embodiment of the present invention;

[0048] Figure 7 This is another flow chart of a load balancing control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] For ease of understanding of the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0050] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this invention belongs. The terms used in this specification and in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0051] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] In one embodiment, please refer to Figure 1 The present invention provides a load balancing control method for a power battery module balancing device, the load balancing control method comprising:

[0053] S1. When charging the power battery module, use a combination of multiple small-capacity power modules, and use a unified charging control signal between each power module to achieve load balancing of the power battery module;

[0054] S2. When the power battery module is discharging, a two-stage discharge strategy is used to adjust the discharge current to form multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

[0055] In this embodiment, when charging the power battery module, multiple small-capacity power modules are combined, and a unified charging control signal is used between each power module to achieve load balancing of the power battery module. When discharging the power battery module, a two-stage discharge strategy is used to adjust the discharge current, forming multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel. This can reasonably balance the load of each power module in the power battery module and achieve a balanced current distribution across each power module. This balanced load distribution can maximize the operating efficiency of the power battery module, while also improving the safety of the power battery system and the life of the power battery module balancing device. This can solve the problem that existing power battery module balancing devices cannot reasonably distribute the load of each power module, resulting in unbalanced load, reduced power battery module operating efficiency, and reduced power battery system safety.

[0056] In one embodiment, in step S1, when charging the power battery module, a combination of multiple small-capacity power modules is used, and a unified charging control signal is used between the power modules to achieve load balancing of the power battery module, specifically including:

[0057] When charging the power battery module, multiple small-capacity power modules are connected in parallel. The output control of each power module is independent, but the output current of each power module is consistent, achieving load balancing of the power battery module to solve the load imbalance caused by individual differences between the power modules.

[0058] When charging the power battery module, multiple small-capacity power modules are connected in series. A unified charging control signal is used between each power module to achieve consistent output current of each power module, thereby solving the load imbalance caused by individual differences between each power module.

[0059] Please refer to Figure 2 and Figure 3 . Figure 2 It is a structural schematic diagram of the power battery module balancing device provided by the present invention. Figure 3 This is a schematic diagram of the balanced charging control of the power battery module balancing device provided by the present invention. Figure 2 and Figure 3 In the embodiment, the power battery module balancing device 100 includes a charge balancing component 1, which is used to use a combination of multiple small-capacity power modules when charging the power battery module, and use a unified charging control signal between the power modules to achieve load balancing of the power battery module.

[0060] The charge equalization component 1 includes a first operational amplifier 11, a second operational amplifier 12, a first power supply module P1, a second power supply module P2, a two-to-one selector 13, a first isolated power supply 14, a first current sampling resistor Re1 and a second current sampling resistor Re2; wherein:

[0061] The positive input terminal of the first operational amplifier 11 is electrically connected to the reference voltage Vref, and the output terminal of the first operational amplifier 11 is electrically connected to the first power module P1. The first power module P1 is controlled by the charging control signal output by the first operational amplifier 11. The first current sampling resistor Re1 is electrically connected to the first power module P1, and the feedback output of the first current sampling resistor Re1 is connected to the negative input terminal of the first operational amplifier 11. The output terminal of the first operational amplifier 11 is electrically connected to the first isolated power supply 14, and the charging control signal output by the first operational amplifier 11 is provided to the first isolated power supply 14.

[0062] The positive input terminal of the second operational amplifier 12 is electrically connected to the control reference voltage Vref, the output terminal of the second operational amplifier 12 is electrically connected to the two-to-one selector 13, the two-to-one selector 13 is electrically connected to the second power module P2, the output of the second operational amplifier 12 controls the second power module P2 through the two-to-one selector 13, the second current sampling resistor Re2 is electrically connected to the second power module P2, and the feedback output of the second current sampling resistor Re2 is connected to the negative input terminal of the second operational amplifier 12.

[0063] The input end of the first isolated power supply 14 is electrically connected to the output end of the first operational amplifier 11 and the negative output end of the first power module P1, respectively. The output end of the first isolated power supply 14 is electrically connected to the selector 13 and the negative output end of the second power module P2, respectively. The first isolated power supply 14 transmits the charging control signal output from the first operational amplifier 11 to the second power module P2 through the selector 13, so that the second power module P2 has the same charging control signal as the first power module P1. This allows the same charging control signal to be transmitted to different power modules using the first isolated power supply 14, thereby resolving the problem of inconsistent base voltages between different power modules when connected in series. In addition, the gain of the first isolated power supply 14 is 1:1 voltage conversion. The output end of the first isolated power supply 14 is electrically connected to the negative output end of the second power module P2, so that the negative voltage of the second power module P2 is consistent with the negative voltage of the first power module P1, thereby resolving the problem of inconsistent negative voltages between different power modules.

[0064] like Figure 3 As shown, the charge balancing component 1 includes a first RC circuit 15. The reference voltage Vref controls the magnitude of the output current. The reference voltage Vref is obtained by converting a PWM (Pulse Width Modulation) duty cycle signal through the first RC circuit 15. The reference voltage Vref changes linearly with the PWM duty cycle. When the PWM duty cycle changes, the reference voltage Vref also changes synchronously.

[0065] In addition, the reference voltage Vref can also be controlled by an on-signal. When the on-signal is off, the reference voltage VRef output is turned off, turning off the output of the first operational amplifier 11. The output control of the first operational amplifier 11 can also be directly controlled by a DAC (digital to analog converter) output, facilitating circuit debugging and fault location.

[0066] exist Figure 3 In the embodiment, after determining the series-parallel working mode of each power module in the charging equalization component 1 in the power battery module equalization device 100.

[0067] The input PWM duty cycle signal is converted into a reference voltage VRef. The first operational amplifier 11 outputs a charging control signal to control the output of the first power module P1, and the second operational amplifier 12 outputs a signal to control the output of the second power module P2. The first operational amplifier 11 and the second operational amplifier 12 use the same reference voltage Vref to ensure that the output current settings of the first power module P1 and the second power module P2 are consistent. The feedback output of the first current sampling resistor Re1 is output to the negative input of the first operational amplifier 11, and the feedback output of the second current sampling resistor Re2 is output to the negative input of the second operational amplifier 12. According to the principle of the operational amplifier, when balanced, the sampling voltages across the first current sampling resistor Re1 and the second current sampling resistor Re2 are consistent with the reference voltage Vref. Within the operating capacity of the operational amplifier, the operational amplifier automatically adjusts the output voltage to control the power supply so that the power supply output current is consistent with the set target current, thereby achieving control of the output current.

[0068] When it is determined that the operating mode of the power modules in the charge balancing assembly 1 of the power battery module balancing device is parallel (i.e., the first power module P1 and the second power module P2 are connected in parallel), the output of the first power module P1 is controlled by the charging control signal output by the first operational amplifier 11, and the second power module P2 is controlled by the charging control signal output by the second operational amplifier 12 selected by the two-to-one selector 13. The positive input terminals of the first operational amplifier 11 and the second operational amplifier 12 are input with the same reference voltage Vref to ensure that the output currents of the first power module P1 and the second power module P2 are consistent. The negative input terminal of the first operational amplifier 11 is connected to the feedback voltage of the first current sampling resistor Re1, and the negative input terminal of the second operational amplifier 12 is connected to the feedback voltage of the second current sampling resistor Re2 to ensure that the first power module P1 and the second power module P2 output the same output current.

[0069] When it is determined that the operating mode of each power module in the charge balancing assembly 1 in the power battery module balancing device is series connection (i.e., the first power module P1 and the second power module P2 are connected in series), the currents passing through the first power module P1 and the second power module P2 are consistent, and the first power module P1 and the second power module P2 are uniformly controlled by the charging control signal output by the first operational amplifier 11. This can avoid the problem that the input control of the first power module P1 and the second power module P2 are not independently controlled, which may cause competition between the operational amplifiers and may cause one power supply output to clamp the output of the other power supply, resulting in the expected output current not being output. The second power module P2 is controlled by the charging control signal output from the first operational amplifier P1 and output through the first isolated power supply 14 selected by the two-to-one selector 13, that is, the charging control signal output by the first operational amplifier 11 is isolated and transformed by the first isolated power supply 14 before being transmitted to the second power module P2. The negative pole output by the first isolated power supply 14 is the negative pole of the second power module P2. The voltage output by the first isolated power supply 14 is consistent with the input voltage (because the gain of the isolated power supply is 1:1 voltage conversion), so that the negative pole voltage of the second power module P2 is consistent with the negative pole voltage of the first power module P1, thereby avoiding the problem of inconsistency between the negative pole voltage of the second power module P2 and the negative pole voltage of the first power module P1.

[0070] In this embodiment, during charging, multiple small power modules can be connected in parallel or series, depending on application requirements. Parallel connection improves current output capability, while series connection improves voltage output capability. This allows each power module to output the same output current using a single reference voltage, Vref. This reference voltage can be used to adjust power output capability during charging of the power battery module. Furthermore, the multiple power modules are symmetrically designed during charging, ensuring consistent output current along the symmetrical paths.

[0071] In one embodiment, in step S2, when the power battery module is discharged, a two-stage discharge strategy is used to adjust the discharge current to form multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge currents in each discharge channel. Specifically, the first-stage discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor; the second-stage discharge strategy includes adjusting the specific size of the discharge current by combining a MOS tube with an operational amplifier to achieve precise control of the discharge current.

[0072] Furthermore, if Figure 4 and Figure 5 As shown, the first-level discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor, specifically including:

[0073] Four discharge channels are configured, namely the first discharge channel CH1, the second discharge channel CH2, the third discharge channel CH3 and the fourth discharge channel CH4. Each discharge channel is symmetrically distributed and configured with several discharge resistors and several switches. Each discharge resistor is connected in parallel with a switch. The switch controls whether the discharge resistor connected in parallel with it is added to the discharge circuit, thereby dynamically changing the resistance size to achieve dynamic adjustment of the discharge current range.

[0074] like Figure 4 and Figure 5 As shown, the first discharge channel CH1 is configured with a first discharge resistor R1, a second discharge resistor R2, a third discharge resistor R3 and a first switch K1, a second switch K2, and a third switch K3. The first discharge resistor R1 is connected in parallel with the first switch K1, the second discharge resistor R2 is connected in parallel with the second switch K2, and the third discharge resistor R3 is connected in parallel with the third switch K3.

[0075] The second discharge channel CH2 is configured with a fourth discharge resistor R4, a fifth discharge resistor R5, a sixth discharge resistor R6 and a fourth switch K4, a fifth switch K5, and a sixth switch K6. The fourth discharge resistor R4 is connected in parallel with the fourth switch K4, the fifth discharge resistor R5 is connected in parallel with the fifth switch K5, and the sixth discharge resistor R6 is connected in parallel with the sixth switch K6.

[0076] The third discharge channel CH3 is configured with a seventh discharge resistor R7, an eighth discharge resistor R8, a ninth discharge resistor R9 and a seventh switch K7, an eighth switch K8, and a ninth switch K9. The seventh discharge resistor R7 is connected in parallel to the seventh switch K7, the eighth discharge resistor R8 is connected in parallel to the eighth switch K8, and the ninth discharge resistor R9 is connected in parallel to the ninth switch K9.

[0077] The fourth discharge channel CH4 is configured with a tenth discharge resistor R10, an eleventh discharge resistor R11, a twelfth discharge resistor R12 and a tenth switch K10, an eleventh switch K11, and a twelfth switch K12. The tenth discharge resistor R10 is connected in parallel with the tenth switch K10, the eleventh discharge resistor R11 is connected in parallel with the eleventh switch K11, and the twelfth discharge resistor R12 is connected in parallel with the twelfth switch K12.

[0078] Among the four configured discharge channels, the third discharge channel CH3 and the fourth discharge channel CH4 are configured identically, the first discharge channel CH1 and the second discharge channel CH2 are configured identically, the third discharge channel CH3 and the first discharge channel CH1 are connected in series, and the fourth discharge channel CH4 and the second discharge channel CH2 are connected in series.

[0079] A first MOS transistor Q1 is configured, the third discharge channel CH3 and the first discharge channel CH1 are connected in series and then connected to the drain of the first MOS transistor Q1 , and the source of the first MOS transistor Q1 is electrically connected to the first shunt Rf1 .

[0080] A second MOS transistor Q2 is configured, the fourth discharge channel CH4 and the second discharge channel CH2 are connected in series and then connected to the drain of the second MOS transistor Q2, and the source of the second MOS transistor Q2 is electrically connected to the second shunt Rf2.

[0081] In the discharge working mode of the power battery module balancing equipment, there are generally two working modes: parallel discharge and series discharge. Specifically:

[0082] like Figure 4 FIG. 1 is a schematic diagram of a power battery module balancing device provided by an embodiment of the present invention in a parallel discharge working mode. Figure 4In the embodiment, the first discharge channel CH1 and the third discharge channel CH3 are connected in parallel with the second discharge channel CH2 and the fourth discharge channel CH4, that is, the third discharge channel CH3 and the first discharge channel CH1 are connected in series, the fourth discharge channel CH4 and the second discharge channel CH2 are connected in series, the third discharge channel CH3 is connected to the fourth discharge channel CH4, the first discharge channel CH1 is connected to the drain of the first MOS transistor Q1, the source of the first MOS transistor Q1 is electrically connected to the first shunt Rf1, the source of the second MOS transistor Q2 is electrically connected to the second shunt Rf2, and the first shunt Rf1 is electrically connected to the second shunt Rf2.

[0083] like Figure 5 The figure shows a schematic diagram of a power battery module balancing device provided by an embodiment of the present invention in a series discharge working mode. Figure 5 In the example, after the third discharge channel CH3 and the first discharge channel CH1 are connected in series for discharge, they are then connected in series to the fourth discharge channel CH4 and the second discharge channel CH2. That is, after the third discharge channel CH3 and the first discharge channel CH1 are connected in series for discharge, the first discharge channel CH1 is connected to the drain of the first MOS transistor Q1. The source of the first MOS transistor Q1 is electrically connected to the first shunt Rf1 and then to the fourth discharge channel CH4. The fourth discharge channel CH4 then discharges in series with the second discharge channel CH2. Due to the symmetrical distribution, as long as the first MOS transistor Q1 of the first discharge channel CH1 and the second MOS transistor Q2 of the second discharge channel CH2 are properly controlled, the discharge current in all discharge paths is consistent.

[0084] As an optional embodiment, a third MOS transistor Q3 and a fourth MOS transistor Q4 are configured, the gate of the third MOS transistor Q3 is electrically connected to the gate of the fourth MOS transistor Q4, the source of the third MOS transistor Q3 is electrically connected to the source of the fourth MOS transistor Q4 and then electrically connected to the first shunt Rf1, the drain of the third MOS transistor Q3 is electrically connected to the drain of the fourth MOS transistor Q4, and the third channel CH3 and the first channel CH1 are connected in series and then connected to the drain of the third MOS transistor Q3.

[0085] A fifth MOS transistor Q5 and a sixth MOS transistor Q6 are configured. The gate of the fifth MOS transistor Q5 is electrically connected to the gate of the sixth MOS transistor Q6. The source of the fifth MOS transistor Q5 is electrically connected to the source of the sixth MOS transistor Q6 and then electrically connected to the second shunt Rf2. The drain of the fifth MOS transistor Q5 is electrically connected to the drain of the sixth MOS transistor Q6. The third channel CH3 and the first channel CH1 are connected in series and then connected to the drain of the fifth MOS transistor Q5.

[0086] As another optional embodiment, a first IGBT (Insulated Gate Bipolar Transistor) T1 is configured, the third discharge channel CH3 and the first discharge channel CH1 are connected in series and connected to the collector of the first IGBT T1, and the emitter of the first IGBT T1 is electrically connected to the first shunt Rf1.

[0087] A second IGBT tube T2 is configured, the fourth discharge channel CH4 and the second discharge channel CH2 are connected in series and then connected to the collector of the second IGBT tube T2, and the emitter of the second IGBT tube T2 is electrically connected to the second shunt Rf2.

[0088] In one embodiment, the second-stage discharge strategy includes adjusting the specific magnitude of the discharge current through a MOS transistor in combination with an operational amplifier to achieve precise control of the discharge current.

[0089] Specifically, please refer to Figure 6 , Figure 6 This is a schematic diagram of the balanced discharge control of the power battery module equalization device of the present invention. Figure 2 and Figure 6 In the embodiment, the power battery module balancing device 100 includes a discharge balancing component 2, which is used to adjust the discharge current using a two-stage discharge strategy when the power battery module is discharged to form multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

[0090] The discharge balancing component 2 includes a third operational amplifier 23, a seventh MOS transistor Q7, an eighth MOS transistor Q8, a third current sampling resistor Re3, a fourth current sampling resistor Re4, a first load resistor RL1, a second load resistor RL2, and a second isolated power supply 24; wherein:

[0091] The positive input terminal of the third operational amplifier 23 is electrically connected to the reference voltage Vref, the output terminal of the third operational amplifier 23 is electrically connected to the gate of the seventh MOS transistor Q7, the third current sampling resistor Re3 is electrically connected to the source of the seventh MOS transistor Q7, the drain of the seventh MOS transistor Q7 is electrically connected to the first load resistor RL1, and the source of the seventh MOS transistor Q7 is connected to the negative input terminal of the third operational amplifier 23. The feedback output of the third current sampling resistor Re3 is connected to the output terminal of the second RC circuit 25.

[0092] The input end of the second isolated power supply 24 is electrically connected to the output end of the third operational amplifier 23 and the feedback output of the third current sampling resistor Re3 respectively, and the output section of the second isolated power supply 24 is electrically connected to the gate of the eighth MOS transistor Q8.

[0093] The gate of the eighth MOS transistor Q8 is electrically connected to the output end of the second isolated power supply 24 , the drain of the eighth MOS transistor Q8 is electrically connected to the second load resistor RL2 , and the source of the eighth MOS transistor Q8 is electrically connected to the fourth current sampling resistor Re4 .

[0094] The feedback output of the fourth current sampling resistor Re4 is connected to the output end of the second isolated power supply 24 .

[0095] The discharge equalization component 2 further includes a second RC circuit 25. The reference voltage Vref controls the magnitude of the output current. The reference voltage Vref is generated by converting the PWM duty cycle signal through the second RC circuit 25. The reference voltage Vref changes linearly with the PWM duty cycle. When the PWM duty cycle changes, the reference voltage Vref also changes synchronously.

[0096] In addition, the reference voltage Vref can also be controlled by an on-signal. When the on-signal is off, the reference voltage VRef output is turned off, turning off the output of the third operational amplifier 23. The output control of the third operational amplifier 23 can also be directly controlled by the DAC output, facilitating circuit debugging and fault location.

[0097] exist Figure 6After determining the discharge operating mode of the power battery module balancing device, the discharge current is controlled by a single operational amplifier (both in parallel and series). The reference voltage Vref, which controls the discharge current, is output by a PWM duty cycle control. The output of the third operational amplifier 23 controls the seventh MOS transistor Q7 of the first load resistor RL1 and the eighth MOS transistor Q8 of the second load resistor RL2 via the second isolated power supply. When controlling the seventh MOS transistor Q7 of the second load resistor RL2, the second isolated power supply 24 with a gain of 1 is used to control the seventh MOS transistor Q7. This resolves the issue of inconsistent reference grounds between the eighth MOS transistor Q8 of the second load resistor RL2 and the seventh MOS transistor Q7 of the first load resistor RL1 when connected in series. The feedback from the third current sampling resistor Re3 is fed into the negative input of the third operational amplifier 23. Due to the characteristics of the operational amplifier, when current is balanced, the current sampling voltage of the third current sampling resistor Re3 is consistent with the reference voltage Vref. Therefore, changing the reference voltage Vref can change the discharge current. Since the first load resistor RL1 and the second load resistor RL2 are equal in size and symmetrically distributed, and the seventh MOS transistor Q7 of the first load resistor RL1 and the eighth MOS transistor Q8 of the second load resistor RL2 have the same parameters, during discharge, the discharge currents through the first load resistor RL1 and the second load resistor RL2 are equal, and the discharge currents through the seventh MOS transistor Q7 and the eighth MOS transistor Q8 are also consistent.

[0098] In this embodiment, during discharge, the discharge current is adjusted by using a two-stage discharge strategy. The first-stage discharge strategy includes adjusting the discharge current range by dynamically configuring the resistor, and the second-stage discharge strategy includes adjusting the specific size of the discharge current by combining the MOS tube with the operational amplifier to achieve precise control of the discharge current; and multiple discharge channels are configured, and the multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

[0099] In one embodiment, Figure 7 As shown, the load balancing control method further includes: S3, when the power battery module is discharging, according to the discharge current and the dynamically configured discharge resistor, distributing the heat generated by the discharge on the discharge resistor that is easy to dissipate heat and is selected according to the preset resistor combination selection algorithm.

[0100] At present, the heat dissipation of the existing discharge resistor is generally achieved by direct cooling with a fan, and the heat dissipation of the MOS tube is achieved by cooling with a fan heat sink.

[0101] However, in the present invention, since the discharge resistor used has a large heat dissipation area and can withstand high heat, the heat generated by the discharge is distributed on the discharge resistor that is selected according to the preset resistor combination selection algorithm and is easy to dissipate heat, thereby protecting the safety of the MOS tube and reducing the design cost.

[0102] Assuming that the voltage of the power battery is Ubat, the discharge current is I, and the configured discharge resistor is R, the power P distributed on the discharge resistor R is R And the power P distributed on the MOS tube MOS As shown in the following formulas (1) and (2), the heat generated on the discharge resistor R and the power P distributed thereon are R Closely related to the heat generated on the MOS tube and its distribution rate P MOS Closely related, the greater the power, the more heat generated.

[0103] P R =I 2 ·R (1)

[0104] P MOS =U bat II 2 ·R (2)

[0105] The discharge current I is predefined. To minimize the MOS transistor power Pmos, the discharge resistor R must be as large as possible. However, the discharge current I is affected by the discharge resistor R. As shown in formula (3), when the discharge resistor R continues to increase, the maximum discharge current Imax is smaller than the expected discharge current I, so the discharge capacity cannot keep up. Therefore, the discharge resistor R can only take an appropriate value. The discharge resistor R should be as large as possible while meeting the discharge current.

[0106]

[0107] exist Figure 3 and Figure 4 In the discharge circuit, the discharge resistor R is composed of multiple discharge resistors connected in series. A switch is connected in parallel to each discharge resistor. When the switch is disconnected, the discharge resistor is connected in series in the discharge circuit. The resistance values ​​of the individual discharge resistors in series may be different. In the discharge channel composed of the third discharge channel CH3 and the first discharge channel CH1 connected in series, there are a total of 6 discharge resistors (R1-R6), of which 5 discharge resistors can be freely configured (for example, R1-R3, R5-R6), and 1 discharge resistor is fixed (for example, R4) (to ensure that there is a discharge resistor in the discharge circuit under any circumstances, improving the safety of the discharge circuit). Among the 5 configurable discharge resistors, the number of possible discharge resistor combinations f(n) is shown in formula (4), where C is the combination symbol.

[0108]

[0109] The preset resistor combination selection algorithm includes:

[0110] a1. Measure the current voltage Ubat of the power battery module and calculate the expected discharge resistance Ri based on the expected discharge current I;

[0111] a2. Among the discharge resistor combinations f(n), find the largest discharge resistor combination Rr that has a smaller resistance than the desired discharge resistor Ri.

[0112] a3. Use formulas (1), (2) and (3) to calculate the power P distributed on the maximum discharge resistor Rr R And the power P distributed on the MOS tube MOS During the calculation process, if it is found that the maximum discharge current Imax is greater than the expected discharge current I, the expected discharge current I is used to participate in the calculation of the above formula, and the amplified current size is calculated by Figure 5 MOS tube control in; if the maximum discharge current Imax is less than the expected discharge current I, then Figure 5 The MOS tubes in the circuit are fully turned on, and the maximum discharge current Imax is used to calculate the above formula;

[0113] a4. If the power Pmos distributed on the MOS tube is less than the maximum power allowed, the maximum discharge resistor combination Rr is selected for discharge; otherwise, go to step a5;

[0114] a5. Find a discharge resistor combination that is larger than the expected discharge resistance Ri from the discharge resistor combination f(n), and repeat steps a3 and a4 until the power distributed on the MOS tube Pmos is found to be within the maximum allowable discharge power.

[0115] In this embodiment, by dynamically configuring the discharge resistor based on the discharge current, the heat generated by the discharge is distributed on the discharge resistor that is selected according to a preset resistor combination selection algorithm and is easy to dissipate heat. This ensures that most of the discharge power is distributed on the selected discharge resistor that is easy to dissipate heat, thereby ensuring that the MOS transistors Q7 and Q8 are within a safe operating range, thereby protecting the safety of the MOS transistors and reducing design costs.

[0116] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A load balancing control method, applied to a power battery module balancing device, characterized in that: The load balancing control method includes: When charging the power battery module, a combination of multiple small-capacity power modules is used, and a unified charging control signal is used between each power module to achieve load balancing of the power battery module; When the power battery module is discharging, a two-stage discharge strategy is used to adjust the discharge current, forming multiple discharge channels. Multiple discharge channels use a unified discharge control signal to achieve consistent discharge currents in each discharge channel. The first-stage discharge strategy involves dynamically configuring the discharge resistor to adjust the discharge current range. The second-stage discharge strategy involves adjusting the specific size of the discharge current through a MOS tube combined with an operational amplifier to achieve precise control of the discharge current. The load balancing control method further includes: when the power battery module is discharging, distributing the heat generated by the discharge on a discharge resistor that is easy to dissipate heat and is selected according to a preset resistor combination selection algorithm based on the discharge current and the dynamically configured discharge resistor.

2. The load balancing control method according to claim 1, characterized in that: The steps of using a combination of multiple small-capacity power modules and using a unified charging control signal between the power modules to achieve load balancing of the power battery modules when charging the power battery module include: When charging the power battery module, multiple small-capacity power modules are connected in parallel. The output current of each power module is consistent, achieving load balancing of the power battery module. When charging the power battery module, multiple small-capacity power modules are connected in series, and a unified charging control signal is used between each power module to achieve consistent output current of each power module.

3. The load balancing control method according to claim 2, characterized in that: The power battery module balancing device includes a first operational amplifier, a second operational amplifier, a first power module, a second power module, a two-to-one selector, a first isolated power supply, a first current sampling resistor and a second current sampling resistor; The steps of using a combination of multiple small-capacity power modules and using a unified charging control signal between the power modules to achieve load balancing of the power battery modules when charging the power battery module include: After determining the operating mode of each power module in the power battery module balancing device, when charging the power battery module, the input PWM duty cycle signal is converted into a reference voltage, the first operational amplifier and the second operational amplifier use the same reference voltage, the feedback output of the first current sampling resistor is output to the negative input of the first operational amplifier, and the feedback output of the second current sampling resistor is output to the negative input of the second operational amplifier; The first operational amplifier outputs a charging control signal to control the first power supply module; The output of the second operational amplifier and the first isolated power supply select the charging control signal from the output of the first operational amplifier and output it to the second power supply module after being selected by the two-to-one selector, so that the second power supply module has the same charging control signal as the first power supply module.

4. The load balancing control method according to claim 1, wherein: The first-level discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor, including: Four discharge channels are configured, namely the first discharge channel, the second discharge channel, the third discharge channel and the fourth discharge channel. Each discharge channel is symmetrically distributed. Each discharge channel is configured with several discharge resistors and several switches. Each discharge resistor is connected in parallel with a switch, and the switch controls whether the discharge resistor connected in parallel with it is added to the discharge circuit.

5. The load balancing control method according to claim 4, characterized in that: The first-level discharge strategy includes adjusting the discharge current range by dynamically configuring the discharge resistor, and also includes: A first MOS transistor is configured, wherein the third discharge channel and the first discharge channel are connected in series and then connected to the drain of the first MOS transistor, and the source of the first MOS transistor is electrically connected to the first shunt; A second MOS transistor is configured, the fourth discharge channel and the second discharge channel are connected in series and then connected to the drain of the second MOS transistor, and the source of the second MOS transistor is electrically connected to the second shunt.

6. The load balancing control method according to claim 1, characterized in that: The power battery module balancing device includes a third operational amplifier, a seventh MOS transistor, an eighth MOS transistor, a third current sampling resistor, a fourth current sampling resistor, a first load resistor, a second load resistor, and a second isolated power supply; The second-stage discharge strategy includes adjusting the specific size of the discharge current through a MOS tube combined with an operational amplifier, including: After determining the discharge operation mode of the power battery module balancing device, the power battery module balancing device converts the input PWM duty cycle signal into a reference voltage during discharge. The output of the third operational amplifier controls the seventh MOS transistor and controls the eighth MOS transistor through the second isolated power supply. The feedback of the third current sampling resistor is input to the negative input terminal of the third operational amplifier. Using the second isolated power supply, the reference ground of the eighth MOS transistor is made consistent with the reference ground of the seventh MOS transistor; The first load resistor and the second load resistor are equal in size and symmetrically distributed, so that the discharge currents passing through the first load resistor and the second load resistor are equal.

7. The load balancing control method according to claim 1, characterized in that: The preset resistor combination selection algorithm includes: a1. Measure the current voltage of the power battery module and calculate the expected discharge resistance based on the expected discharge current; a2. Among the discharge resistor combinations, find the largest discharge resistor combination with a smaller resistance than the expected discharge resistor. a3. Calculate the power distributed on the maximum discharge resistor and the power distributed on the MOS tube. If the maximum discharge current is greater than the expected discharge current, the expected discharge current is used for calculation; if the maximum discharge current is less than the expected discharge current, the maximum discharge current is used for calculation; a4. If the power distributed on the MOS tube is less than the maximum power allowed, the maximum discharge resistor combination is selected for discharge; otherwise, go to step a5; a5. Find a discharge resistor combination with a larger discharge resistance than the expected discharge resistance from the discharge resistor combination, and repeat steps a3 and a4 until a discharge power distribution on the MOS tube is found that is within the maximum allowable discharge power.

8. A power battery module balancing device, applied to a load balancing control method for a power battery module balancing device according to any one of claims 1 to 7, characterized in that: The power battery module balancing device includes a charge balancing component and a discharge balancing component; wherein: The charging balancing component is used to use a combination of multiple small-capacity power modules when charging the power battery module, and a unified charging control signal is used between each power module to achieve load balancing of the power battery module; The discharge balancing component is used to adjust the discharge current using a two-stage discharge strategy when the power battery module is discharged, forming multiple discharge channels. The multiple discharge channels use a unified discharge control signal to achieve consistent discharge current in each discharge channel.

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