Battery module end voltage regulating circuit and device

Abstract

The application relates to a battery module terminal voltage regulating circuit and relates to the field of power supplies, which comprises an alternating current rectifying unit, an input end of which is connected with an alternating current, and an output end of which is connected with a direct current bus, and which is used for converting the alternating current into a direct current bus voltage; a battery charging and discharging unit, a first end of which is connected with the direct current bus, and a second end of which is connected with a battery module, and which is used for converting the direct current bus voltage at the first end into a direct current voltage at the second end to charge the battery module, or converting the direct current voltage at the second end into the direct current bus voltage at the first end; and a power consumption discharging unit, which is connected with the direct current bus, and the battery module is discharged through the battery charging and discharging unit and the power consumption discharging unit, so that the design is simple, and the standardization is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power supply, in particular to a battery module terminal voltage regulating circuit. BACKGROUND

[0002] Large-scale series-parallel battery module is a necessary system component in many electrical fields, such as an energy supply unit of an electric vehicle or an energy storage unit of a photovoltaic inverter system. Generally, a battery module is composed of a plurality of cells in series and parallel, and a battery package is composed of a plurality of battery modules in series and parallel, to serve as an energy storage unit or an energy supply unit.

[0003] When a battery module in a battery package needs to be replaced, the new battery module needs to be adjusted to a suitable value before replacement to ensure the capacity balance of the entire battery package. Since the capacity of the battery module is highly related to the terminal voltage of the battery module, in actual operation, adjusting the terminal voltage of the battery module can be regarded as adjusting its capacity. The industry usually uses an alternating current rectifier unit to convert alternating current (AC) into direct current (DC) to charge the battery module, and uses a discharge unit to discharge the battery module to achieve the adjustment of the terminal voltage of the battery module.

[0004] Specifically, please refer to Figure 1 , Figure 1 The battery module terminal voltage regulating circuit of an embodiment of the prior art is shown in FIG. 1. As shown in FIG. 1, the battery module terminal voltage regulating circuit includes an alternating current rectifier unit 110 that converts alternating current (AC) into direct current (DC) to charge a battery module 130, and includes an inverter discharge unit 120 that converts direct current (DC) into alternating current (AC) to discharge the battery module 130, to achieve the adjustment of the terminal voltage of the battery module 130. However, since inverter discharge is strictly limited in some countries and regions in the world, its application is limited. The low-cost resistance load discharge mode becomes a common choice in the industry, especially in high-power and high-current discharge applications, resistance discharge is the most effective and low-cost implementation scheme. However, using the resistance discharge scheme has many disadvantages in control. Specifically, please refer to Figure 1 , Figure 2 The battery module terminal voltage regulating circuit of another embodiment of the prior art is shown in FIG. 2. It connects a resistor R and a switch S1 in series to form a discharge circuit 121, and controls the switch S1 to be on or off to realize the connection or disconnection of the discharge circuit 121, to achieve the constant resistance discharge of the battery module 130. However, during the discharge process, due to the change of the voltage of the battery module 130, it is impossible to achieve the constant current discharge condition required by general capacity detection or balance. Figure 2 Figure 3 , Figure 3 ​Fig. 1 is a schematic diagram of a battery module terminal voltage regulating circuit according to an embodiment of the present application. Figure 3 Fig. 2 is a schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application. Figure 2 Fig. 3 is a schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application. Figure 4 Fig. 4 is a schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application. Figure 4 Fig. 5 is a schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application. Figure 5 Fig. 6 is a schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application. SUMMARY

[0005] The present application provides a battery module terminal voltage regulating circuit, comprising: an AC rectifying unit, having an input end receiving AC power and an output end connected to a DC bus, for converting the AC power into a DC bus voltage; a battery charging and discharging unit, having a first end connected to the DC bus and a second end connected to a battery module, for converting the DC bus voltage at the first end into a DC voltage at the second end to charge the battery module, or converting the DC voltage at the second end into the DC bus voltage at the first end; and a power consumption discharging unit connected to the DC bus, the battery module being discharged through the battery charging and discharging unit and the power consumption discharging unit.

[0006] Further, the power consumption discharging unit comprises at least one discharging branch formed by connecting a resistor and a switch in series, and at least one DC / DC converter, the first end of the discharging branch and the first end of the DC / DC converter being connected to the DC bus, and the second end of the discharging branch and the second end of the DC / DC converter being grounded.

[0007] The application also provides a battery module terminal voltage regulating device, comprising: an AC rectifier unit, which receives AC power at an input end and is connected to a DC bus at an output end, and is used to convert the AC power into a DC bus voltage; a battery charging and discharging unit, which is connected to the DC bus at a first end and is connected to a battery module at a second end, and is used to convert the DC bus voltage at the first end into a DC voltage at the second end to charge the battery module, or convert the DC voltage at the second end into the DC bus voltage at the first end; a power consumption discharging unit, which comprises at least one discharging branch formed by connecting a resistor and a switch in series and at least one DC / DC converter, and the first end of the discharging branch and the first end of the DC / DC converter are both connected to the DC bus, and the second end of the discharging branch and the second end of the DC / DC converter are both grounded; and a control and sampling unit, which is connected to each discharging branch and DC / DC converter in the power consumption discharging unit, the AC rectifier unit and the battery charging and discharging unit, and is used to output control signals to the switch in each discharging branch and the switch in the DC / DC converter, the switch in the AC rectifier unit and the switch in the battery charging and discharging unit, so as to control the battery module terminal voltage regulating circuit to work in a charging mode or a discharging mode, in the charging mode, the switch in the AC rectifier unit and the switch in the battery charging and discharging unit work to charge the battery module, and in the discharging mode, the switch in the battery charging and discharging unit, the switch in each discharging branch and the switch in the DC / DC converter work to discharge the battery module.

[0008] Furthermore, the control and sampling unit is also connected to the battery module, and is used to sample the terminal voltage of the battery module, when the terminal voltage of the battery module is lower than a charging threshold, the control and sampling unit controls the battery module terminal voltage regulating circuit to work in the charging mode, and when the terminal voltage of the battery module is higher than a discharging threshold, the control and sampling unit controls the battery module terminal voltage regulating circuit to work in the discharging mode so that the battery module is discharged through the battery charging and discharging unit and the power consumption discharging unit.

[0009] Furthermore, the design power of one discharging branch is 1 / n of the design power of other discharging branches, where n is an integer greater than 1.

[0010] Furthermore, the design power of the discharging branch and the DC / DC converter is equal.

[0011] Furthermore, the control and sampling unit controls the number of the discharging branches turned on in the power consumption discharging unit to decrease successively until only the DC / DC converter works alone to discharge to the end of discharging.

[0012] Furthermore, the control and sampling unit controls the discharging branches in the power consumption discharging unit to be turned on or turned off so that the discharging power realized by all the discharging branches gradually decreases until only the DC / DC converter works alone to discharge to the end of discharging.

[0013] Further, the switch in the discharging branch is a power device.

[0014] Further, the power device in the discharging branch is controlled to operate in the linear region during the process of turning off the discharging branch. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A schematic diagram of a battery module terminal voltage regulating circuit according to an embodiment of the prior art.

[0016] Figure 2 A schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the prior art.

[0017] Figure 3 A schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the prior art.

[0018] Figure 4 A schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the prior art.

[0019] Figure 5 A schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the prior art.

[0020] Figure 6 A schematic diagram of a battery module terminal voltage regulating circuit according to an embodiment of the present application.

[0021] Figure 7 A schematic diagram of a battery module terminal voltage regulating circuit according to another embodiment of the present application.

[0022] Figure 8 A schematic diagram of a battery module terminal voltage regulating device according to an embodiment of the present application.

[0023] Figure 9 A schematic diagram of a battery module terminal voltage regulating device according to another embodiment of the present application. Figure 8 A schematic diagram of a control principle of a battery module terminal voltage regulating device according to an embodiment of the present application.

[0024] Figure 10 A schematic diagram of a control principle of a battery module terminal voltage regulating device according to another embodiment of the present application. Figure 8 A schematic diagram of a control principle of a battery module terminal voltage regulating device according to another embodiment of the present application.

[0025] Figure 11 A schematic diagram of a control principle of a battery module terminal voltage regulating device according to another embodiment of the present application. Figure 8 A schematic diagram of a control waveform of a battery module terminal voltage regulating device according to an embodiment of the present application.

[0026] Figure 12 A schematic diagram of a control waveform of a battery module terminal voltage regulating device according to another embodiment of the present application. Figure 8 A schematic diagram of a control waveform of a battery module terminal voltage regulating device according to another embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of protection of the present application.

[0028] It should be understood that the present application can be carried out in various forms without being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the disclosure will be complete and full, and will fully convey the scope of the application to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions can be exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element or layer is referred to as being "on" or "adjacent" another element or layer, it can be directly on the other element or layer or intervening elements or layers can also be present. In contrast, when an element is referred to as being "directly on" or "directly adjacent" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0029] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] The technical solutions in the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0032] In an embodiment of the present application, a battery module terminal voltage regulating circuit is provided. Please refer to Figure 6 The battery module terminal voltage regulating circuit in an embodiment of the present application is shown in FIG. 1. The battery module terminal voltage regulating circuit comprises an AC rectifying unit 210, a battery charging and discharging unit 250, and a power consumption discharging unit 220. The AC rectifying unit 210 has an input end receiving an AC power and an output end connected to a DC bus for converting the AC power into a DC bus voltage Vbus. The battery charging and discharging unit 250 has a first end connected to the DC bus and a second end connected to a battery module 230 for converting the DC bus voltage Vbus at the first end into a DC voltage (DC out) at the second end to charge the battery module 230, or converting the DC voltage (DC out) at the second end into the DC bus voltage Vbus at the first end. The power consumption discharging unit 220 is connected to the DC bus, and the battery module 230 is discharged through the battery charging and discharging unit 250 and the power consumption discharging unit 220.

[0033] In this way, the constant current and constant voltage control of the charging and discharging of the battery module terminal is undertaken by the battery charging and discharging unit 250, and since the DC bus voltage Vbus on the DC bus is basically constant or only varies within a very small range (e.g. 3V), the power consumption discharging unit 220 only needs to undertake the function of adjusting the required discharging power, and does not need to consider the different voltage levels of different battery modules, so the design is simple and can be standardized.

[0034] In an embodiment, the AC rectifying unit 210 can be any AC / DC converter as long as it can convert AC power into DC power, and the specific structure thereof is not limited in the present application.

[0035] In one embodiment, the battery charging and discharging unit 250 is a bidirectional DC / DC converter used to realize the mutual conversion between the DC bus voltage Vbus and the DC voltage (DC out). It can be a bidirectional full-bridge converter, a buck-boost converter, or other converters that can realize bidirectional DC-DC conversion.

[0036] For further details, please refer to Figure 7 , Figure 7 This is a schematic diagram of a battery module terminal voltage regulation circuit according to another embodiment of the present invention. Compared to Figure 6 The battery module terminal voltage adjustment circuit shown is as follows. Figure 7 The energy-consuming discharge unit 220 in the battery module terminal voltage regulation circuit shown includes: at least one discharge branch 222 formed by a resistor R and a switch S connected in series, and at least one DC / DC converter 221. The first end of the discharge branch 222 and the first end of the DC / DC converter 221 are both connected to the DC bus (DC BUS), and the second ends of the discharge branch 222 and the DC / DC converter are both grounded, forming a parallel discharge structure. Control causes the switch in the discharge branch 222 to be turned on or off, causing the DC / DC converter 221 to work in conjunction with the discharge branch 222 to discharge the battery module 230. During the discharge process, the DC / DC converter 221 operates, maintaining the DC bus voltage Vbus at a constant value, or varying only within a very small range (e.g., within 3V), which is generally slightly higher than the constant voltage output value of the AC rectifier unit 210. The DC / DC converter 221, working in conjunction with the discharge branch 222, can achieve linear regulation of the discharge power across the entire system range. Furthermore, since the DC bus voltage Vbus is basically constant, the resistance value in the discharge branch 222 can be easily determined based on its own power configuration, allowing for mass production without having to consider the different voltage levels of different battery modules.

[0037] In one embodiment, the specific structure of the DC / DC converter 221 is not limited by the present invention, as long as it can realize the conversion of DC power to DC power.

[0038] This invention also provides a battery module terminal voltage regulation device. For details, please refer to [link / reference]. Figure 8 The schematic diagram shown is of a battery module terminal voltage regulation device according to an embodiment of the present invention. Figure 7The battery module terminal voltage regulating circuit shown further comprises a control and sampling unit 260 connected to each discharging branch 222 and the DC / DC converter 221, the AC rectifier unit 210 and the battery charging and discharging unit 250 in the energy-consuming discharging unit 220, for outputting control signals to the switches S in each discharging branch 222 and the switches in the DC / DC converter 221, the AC rectifier unit 210 and the battery charging and discharging unit 250, so as to control the battery module terminal voltage regulating circuit to work in a charging mode or a discharging mode. In the charging mode, the switches in the AC rectifier unit 210 and the battery charging and discharging unit 250 work to charge the battery module 230. In the discharging mode, the switches in the battery charging and discharging unit 250, the switches S in each discharging branch 222 and the switches in the DC / DC converter 221 work to discharge the battery module 230.

[0039] In an embodiment, as shown, the control and sampling unit 260 is further connected to the battery module 230, for sampling the terminal voltage of the battery module 230. When the terminal voltage of the battery module 230 is lower than a charging threshold, the control and sampling unit 260 controls the battery module terminal voltage regulating circuit to work in the charging mode. When the terminal voltage of the battery module 230 is higher than a discharging threshold, the control and sampling unit 260 controls the battery module terminal voltage regulating circuit to work in the discharging mode, so as to discharge the battery module 230 through the battery charging and discharging unit 250 and the energy-consuming discharging unit 220. Figure 8

[0040] The power levels of the discharging branches 222 and the DC / DC converters 221 can use different configuration methods. Taking the number of discharging branches 222 as 3 as an example, in an embodiment, the discharging branches 222 and the DC / DC converters 221 are evenly distributed, i.e. using Pmax / 4 as the design power of the discharging branches 222 and the DC / DC converters 221, wherein Pmax is the system design power. At this time, the design power of the DC / DC converters 221 is only 25% of the system power, which can reduce the design difficulty and cost of the DC / DC converters 221. Since the DC bus voltage Vbus on the DC bus is basically constant, or only changes within a very small range (such as 3V), the discharging branches 222 only bear the function of adjusting the required discharging power, and do not need to care about the voltage levels of different battery modules, so the design is simple and can be standardized. Of course, the above-mentioned "evenly distributed" is not absolute "evenly distributed", i.e. the design power of the discharging branches 222 and the DC / DC converters 221 is not completely equal, which can have a deviation within 10%. More preferably, it can have a deviation within 5%.

[0041] ​In an embodiment, the design power of the DC / DC converter 221 is designed to be between 103% and 105% of the minimum design power of the discharge branches 222, so as to reduce the fluctuation when the discharge power is switched, to realize continuous adjustment of the discharge power, and to reduce the influence on the load end when the discharge power is switched.

[0042] In another embodiment, the discharge branches 222 and the DC / DC converter 221 can also be unevenly allocated, such as P1:P2:P3:PDC / DC=1:2:4:1, P1, P2, P3 and PDC / DC are the design powers of the first discharge branch, the second discharge branch, the third discharge branch and the DC / DC converter 221 respectively. The design can further reduce the design power of the DC / DC converter 221 to 12.5% of the system power, further reduce the design difficulty and system cost, and the discharge branches 222 still only bear the function of adjusting the required discharge power, without considering the different voltage levels of different battery modules, so the design is simple and can be standardized.

[0043] In the discharge mode, the discharge branches 222 work with the DC / DC converter 221 to discharge the battery module 230. The specific working principle is as follows:

[0044] In an embodiment, the design power of the DC / DC converter 221 can be left with a margin of not more than 10%, so that the DC / DC will not work in a load state of more than 90% or less than 10% when the power is switched, thereby improving its stability. In order to leave a margin of not more than 10% for the design power of the DC / DC converter 221, each discharge branch 222 needs to be switched. Generally, as the discharge power decreases, the output power of the DC / DC converter 221 will decrease, and when the switching threshold point (generally set to 10% of the design power of the DC / DC converter 221) is reached, the discharge power borne by the discharge branch 222 is reduced. In this way, until the battery module 230 reaches the discharge threshold. Taking the number of discharge branches 222 as 3 and the system design power as 3000W as an example, in the first embodiment, the design power of the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 is designed to be 750W, the design power of the DC / DC converter 221 is 800W, the DC bus voltage Vbus on the DC bus is 48V, and the resistance value in the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 is about 3 ohms. The DC / DC converter 221 can also use a resistance load, and the load resistance value is about 2.9 ohms. At the initial discharge, the control signal output by the control and sampling unit 260 controls the switches built in the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 to be turned on. For details, please refer to the schematic diagram of the control and sampling unit 260 shown in FIG. 4. Figure 9 Figure 8 ​The control principle schematic diagram of the shown battery module end voltage regulating device one embodiment. Before T1 time, the switch built-in in the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 are all turned on to discharge, the end voltage of the battery module 230 gradually reduces, then the discharge power reduces, the DC / DC converter 221 reduces the discharge power gradually by adjusting the duty cycle, when the discharge power of the DC / DC converter 221 reduces to below 10% at T1 time, the switch in the first discharge branch P1 is turned off, only the switch built-in in the second discharge branch P2 and the third discharge branch P3 is turned on to discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to keep the DC bus voltage Vbus on the DC bus stable. By analogy, when the discharge power of the DC / DC converter 221 reduces to below 10% again at T2 time, the switch in the second discharge branch P2 is turned off, only the switch built-in in the third discharge branch P3 is turned on to discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to keep the DC bus voltage Vbus on the DC bus stable. When the discharge power of the DC / DC converter 221 reduces to below 10% again at T3 time, the switch in the third discharge branch P3 is turned off, only the DC / DC converter 221 discharges, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to keep the DC bus voltage Vbus on the DC bus stable, and along with the discharge power reducing, the DC / DC converter 221 adjusts the duty cycle until the discharge ends. In this way, the DC bus voltage Vbus on the DC bus is basically constant, or only changes in a very small range (such as 3V), the energy consumption discharge unit 220 only bears the function of adjusting the required discharge power, and does not need to care about the different voltage levels of different battery modules, so the design is simple and can be standardized, and does not need to care about the different voltage levels of different battery modules. That is, the control and sampling unit 260 controls the number of discharge branches 222 connected in the energy consumption discharge unit 220 to gradually reduce until only the DC / DC converter 221 works alone to discharge to the end of discharge. And avoids the DC bus voltage Vbus on the DC bus transient. In the second embodiment, the design power of the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 is 375W, 750W and 1500W respectively, the resistance value of the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 is about 6 ohms, 3 ohms and 1.5 ohms respectively, the design power of the DC / DC converter 221 is 400W, the DC / DC converter 221 can also use a resistance load, the load resistance value is about 5.9 ohms, the DC bus voltage Vbus on the DC bus is 48V. Initial discharge, the control signal output by the control and sampling unit 260 controls the switch built-in in the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 to be turned on, for details, please refer toFigure 10 as shown Figure 8The control principle schematic diagram of another embodiment of the battery module terminal voltage regulating device is shown. Before T1 moment, the switches built-in the first discharge branch P1, the second discharge branch P2 and the third discharge branch P3 are all turned on to discharge, the terminal voltage of the battery module 230 gradually decreases, then the discharge power decreases, the DC / DC converter 221 gradually reduces the discharge power by adjusting the duty cycle, to T1 moment, when the discharge power of the DC / DC converter 221 reduces to below 10%, the switch in the first discharge branch P1 is turned off, the switches built-in the second discharge branch P2 and the third discharge branch P3 are all turned on to discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable. To T2 moment, when the discharge power of the DC / DC converter 221 again reduces to below 10%, the switch in the second discharge branch P2 is turned off, and at the same time, the switch in the first discharge branch P1 is turned on, the first discharge branch P1 and the third discharge branch P3 discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable. To T3 moment, when the discharge power of the DC / DC converter 221 again reduces to below 10%, the switch in the first discharge branch P1 is turned off, the switch built-in the third discharge branch P3 is turned on to discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable. To T4 moment, when the discharge power of the DC / DC converter 221 again reduces to below 10%, the switch in the third discharge branch P3 is turned off, and at the same time, the switches in the first discharge branch P1 and the second discharge branch P2 are turned on, the first discharge branch P1 and the second discharge branch P2 discharge, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable. To T5 moment, when the discharge power of the DC / DC converter 221 again reduces to below 10%, the switch in the first discharge branch P1 is turned off, the second discharge branch P2 discharges, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable. To T6 moment, when the discharge power of the DC / DC converter 221 again reduces to below 10%, the switch in the second discharge branch P2 is turned off, and at the same time, the switch in the first discharge branch P1 is turned on, the first discharge branch P1 discharges, then at this time, the discharge power of the DC / DC converter 221 will automatically increase to maintain the DC bus voltage Vbus on the DC bus stable.At T7, when the discharging power of the DC / DC converter 221 is reduced to 10% again, the switch in the first discharging branch P1 is turned off. At this time, only the DC / DC converter 221 discharges, and the discharging power of the DC / DC converter 221 is automatically increased to maintain the DC bus voltage Vbus on the DC bus stable. As the discharging power decreases, the DC / DC converter 221 adjusts the duty cycle until the discharging ends. In this way, the DC bus voltage Vbus on the DC bus is basically constant or only changes within a very small range (e.g. 3V), and the energy consumption discharging unit 220 only needs to adjust the discharging power as required, without considering the different voltage levels of different battery modules. Therefore, the design is simple and can be standardized, without considering the different voltage levels of different battery modules. That is, the control and sampling unit 260 controls the discharging branches 222 in the energy consumption discharging unit 220 to be turned on or turned off so that the discharging power gradually decreases until only the DC / DC converter 221 works alone to discharge to the end of discharging. This avoids the transient of the DC bus voltage Vbus on the DC bus.

[0045] For production convenience and to reduce the number of resistance values, the design power of one discharging branch is 1 / n of the design power of other discharging branches, where n is an integer greater than 1. In the second embodiment described above, the design power of the first discharging branch P1 is 1 / 2 of the design power of the second discharging branch P2, and the design power of the first discharging branch P1 is 1 / 4 of the design power of the third discharging branch P2. Therefore, the resistors in the second discharging branch P2 and the third discharging branch P3 are composed of n groups of resistors in the first discharging branch P1. For example, the resistors in the second discharging branch P2 are composed of 2 groups of resistors in the first discharging branch P1, and the resistors in the third discharging branch P3 are composed of 4 groups of resistors in the first discharging branch P1. That is, the internal discharging branches can also be standardized and mass-produced.

[0046] For the embodiments shown in Figure 9 and Figure 10 The switches in the discharging branches only have two working modes: on and off. That is, the switches are quickly turned on or off. Due to the possible insufficient dynamic response capability of the DC / DC converter 221, this may cause a transient of the DC bus voltage Vbus on the DC bus. If the high-frequency fluctuation of the transient exceeds 5% of the DC bus voltage Vbus, it may be coupled to the battery module side through the battery charging and discharging unit 250, which may affect the discharging current collection accuracy and capacity calculation accuracy for a short time. Please refer to Figure 11 shown in Figure 8The diagram shows a control waveform of another embodiment of the battery module voltage regulation device. When the switch in the first discharge branch P1 is turned off, the dynamic response capability of the DC / DC converter 221 is insufficient, causing a momentary decrease in the DC bus voltage Vbus on the DC bus. If the high-frequency fluctuation of this transient exceeds 5% of the DC bus voltage Vbus, it may be coupled to the battery module side through the battery charging and discharging unit 250, affecting the accuracy of discharge current acquisition and capacity calculation for a short time. To avoid this phenomenon, the switch in the discharge branch can be a power device that can operate in the linear region. During the process of turning off the discharge branch, the switch is controlled to operate in the linear region to minimize the transient of the DC bus voltage Vbus on the DC bus. See also... Figure 12 shown Figure 8 The diagram shows a control principle schematic of another embodiment of the battery module voltage regulation device. During the process of shutting off the first discharge branch P1, the switch within the first discharge branch P1 is controlled to operate in the linear region. This causes the operating power of the DC / DC converter 221 to change slowly, resulting in only a very small transient change in the DC bus voltage Vbus. This does not affect the accuracy of the control and sampling unit 260 in acquiring the discharge current or calculating the capacity, and ensures that the current control at the battery module end of the battery charging and discharging unit 250 meets the high-precision requirements throughout the entire process.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery module terminal voltage regulation device, characterized in that, The application relates to a battery charging and discharging system, comprising: an AC rectifier unit, which receives AC power at an input end and connects a DC bus at an output end, and is used for converting the AC power into a DC bus voltage; a battery charging and discharging unit, which connects the DC bus at a first end and connects a battery module at a second end, and is used for converting the DC bus voltage at the first end into a DC voltage at the second end to charge the battery module, or converting the DC voltage at the second end into the DC bus voltage at the first end; a power consumption discharging unit, which comprises at least one discharging branch formed by connecting a resistor and a switch in series and at least one DC / DC converter, and the first end of the discharging branch and the first end of the DC / DC converter are both connected to the DC bus, and the second end of the discharging branch and the second end of the DC / DC converter are both grounded; and a control and sampling unit, which is connected to each discharging branch and DC / DC converter in the power consumption discharging unit, the AC rectifier unit and the battery charging and discharging unit, and is used for outputting control signals to the switches in each discharging branch and the switches in the DC / DC converter, the switches in the AC rectifier unit and the switches in the battery charging and discharging unit, so as to control the battery module terminal voltage regulating circuit to work in a charging mode or a discharging mode, in the charging mode, the switches in the AC rectifier unit and the switches in the battery charging and discharging unit work to charge the battery module, and in the discharging mode, the switches in the battery charging and discharging unit, the switches in each discharging branch and the switches in the DC / DC converter work to discharge the battery module; the control and sampling unit is also connected to the battery module, and is used for sampling the terminal voltage of the battery module, when the terminal voltage of the battery module is lower than a charging threshold, the control and sampling unit controls the battery module terminal voltage regulating circuit to work in the charging mode, and when the terminal voltage of the battery module is higher than a discharging threshold, the control and sampling unit controls the battery module terminal voltage regulating circuit to work in the discharging mode so that the battery module is discharged through the battery charging and discharging unit and the power consumption discharging unit; the design power of one discharging branch is 1 / n times of the design power of other discharging branches, wherein n is an integer greater than 1, or the design power of the discharging branch and the DC / DC converter is equal; the control and sampling unit controls the number of the discharging branches turned on in the power consumption discharging unit to decrease in turn until only the DC / DC converter works to discharge to the end of discharging, or the control and sampling unit controls the discharging branches in the power consumption discharging unit to be turned on or turned off so that the discharging power realized by all the discharging branches gradually decreases until only the DC / DC converter works to discharge to the end of discharging.

2. The battery module terminal voltage adjusting apparatus according to claim 1, wherein The switches in the discharging branch are power devices.

3. The battery module terminal voltage adjusting apparatus according to claim 1, wherein In the process of turning off the discharging branch, the power device in the discharging branch works in a linear region.

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