A battery parallel discharge control circuit system
By using a bidirectional DC-DC converter and an ideal diode unit in the parallel control circuit of the electric bicycle battery, the problem of reverse current caused by inconsistent battery pack voltage is solved, unidirectional current flow is achieved, heat loss and cost are reduced, and the battery pack's range and power supply capacity are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 人民出行(南宁)科技有限公司
- Filing Date
- 2025-08-25
- Publication Date
- 2026-07-31
AI Technical Summary
When multiple batteries are connected in parallel in existing electric bicycles, the inconsistent battery voltages can cause reverse current, posing a safety risk and damaging the batteries. Traditional diode parallel connection methods suffer from high losses and severe heat generation under high current, increasing cost and size.
The discharge control circuit employs a bidirectional DC-DC converter and an ideal diode unit. The control unit controls the current direction according to the battery pack voltage to achieve unidirectional current flow. The power MOSFET controls the current on and off to avoid reverse current flow, and the ideal diode unit controls the current path to reduce voltage drop and heat loss.
It achieves safe and efficient discharge when multiple battery packs are connected in parallel, avoids current backflow, reduces heat loss and energy conversion efficiency loss, has a simple structure and low cost, and improves the battery pack's range and power supply capacity.
Smart Images
Figure CN224582877U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of battery control technology, and specifically relates to a battery parallel discharge control circuit system. Background Technology
[0002] Electric bicycles are compact, flexible, and convenient, unaffected by traffic congestion. Their zero-emission nature also effectively reduces urban pollution, making them an important mode of transportation. Electric bicycles perfectly solve the problem of short-distance travel, becoming a preferred choice for many. However, most electric bicycles only have one battery, resulting in limited range. For long distances, the battery's range becomes insufficient, causing concern for riders. To address this insufficient range, most electric bicycles use two or more battery packs as backups to improve range. Connecting another battery pack in parallel with the existing one can further increase range. However, directly connecting two or more battery packs in parallel can lead to voltage differences due to variations in capacity or charge. Direct parallel connection can cause a large reverse current from the higher-voltage battery to the lower-voltage battery, triggering the battery pack's protection mechanism, rendering it unusable, and potentially damaging the battery, posing a safety risk.
[0003] The traditional method of connecting multiple battery packs in parallel involves connecting a diode in series between the positive terminal of each battery pack and the load. That is, the positive terminal of the diode is connected to the positive terminal of the battery pack, and the negative terminal of the diode is connected to the positive terminal of the load. Then, the negative terminals of multiple diodes are connected in parallel to the load to improve the range or increase the output power. However, this configuration has a drawback. When the load draws a large current, there is a certain voltage drop in the diode. The current flowing through the diode is relatively large, which will generate a large loss in the diode, causing it to overheat and reducing the stability of the diode. It will also reduce the energy conversion efficiency of the battery. In order to reduce the temperature of the diode, a large heat sink must be used to dissipate heat from the diode, which increases the cost and increases the size of the product. Utility Model Content
[0004] The purpose of this invention is to provide a battery parallel discharge control circuit system, thereby overcoming the shortcomings of the prior art. The specific technical solution is as follows: A battery parallel discharge control circuit system includes at least one set of discharge control circuits; the discharge control circuit includes a control unit, a first battery pack, a second battery pack, a bidirectional DC-DC converter, and an ideal diode unit; The bidirectional DC-DC converter is connected to the control unit, the first battery pack, the second battery pack, and the ideal diode unit, respectively. The control unit is connected to the first battery pack and the second battery pack respectively; The ideal diode unit is connected to the load; A bidirectional DC-DC converter is used to achieve bidirectional power transmission; The ideal diode unit is used to control the on / off state of the current flowing to the load; The control unit is used to control the direction of the operating current of the bidirectional DC-DC converter according to the output voltage of the first battery pack and the second battery pack.
[0005] Preferably, the first battery pack and the second battery pack each include a BMS unit and a communication interface; The control unit is connected to the communication interface of the first battery pack via a first communication interface and a communication bus, and the control unit is connected to the communication interface of the second battery pack via a second communication interface and a communication bus.
[0006] Preferably, the communication bus is any one of the following: IIC communication bus, UART communication bus, RS232 communication bus, RS485 communication bus, and CAN communication bus.
[0007] Preferably, the ideal diode unit includes an ideal diode controller, a first power MOSFET, and a second power MOSFET; The ideal diode controller is connected to the source, gate, and drain of the first power MOSFET, the source, gate, and drain of the second power MOSFET, respectively. The source of the first power MOSFET is connected to the first battery pack and the bidirectional DC-DC converter, respectively. The source of the second power MOSFET is connected to the second battery pack and the bidirectional DC-DC converter, respectively. The drains of the first power MOSFET and the second power MOSFET are connected to the load, respectively.
[0008] Preferably, the first power MOSFET and the second power MOSFET are both NMOS transistors.
[0009] Compared with existing technologies, this utility model has the following beneficial effects: This utility model's parallel battery discharge control system incorporates at least one set of discharge control circuits. Each set includes an ideal diode unit, corresponding to two battery packs. The control unit controls the current flow of the bidirectional DC-DC converter based on a comparison of the output voltages of the first and second battery packs. Furthermore, by controlling the on / off state of the current transmitted to the load through the ideal diode unit, unidirectional current flow is ensured. This maintains a consistent depth of discharge for each battery. While ensuring unidirectional current flow, the voltage drop between the input and output terminals of the ideal diode is reduced. This allows for parallel connection of multiple batteries while avoiding backflow caused by voltage drops between parallel battery packs, thus improving safety performance.
[0010] In addition, the ideal diode controller ensures unidirectional current flow by controlling the switching on and off of the power MOSFET. At the same time, the power MOSFET in the discharge path has low on-resistance, which can reduce the voltage drop in the power supply circuit, reduce heat loss, avoid overheating problems, avoid wasting battery energy conversion efficiency, and has a simple structure and low cost. Attached Figure Description
[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0012] Figure 1 This is a circuit diagram of a discharge control circuit according to the present invention.
[0013] Figure 2 This is a circuit diagram of the present invention with multiple sets of discharge control circuits. Detailed Implementation
[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0015] In the description of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.
[0016] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If the terms "first," "second," and "third" are used in the description, they are for descriptive purposes and to distinguish technical features, and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.
[0017] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. The embodiments of this utility model will now be described based on its overall structure.
[0018] like Figure 1 As shown, the present invention provides a battery parallel discharge control circuit system, including at least one set of discharge control circuits; if multiple sets of discharge control circuits are provided, the multiple sets of discharge control circuits are connected in parallel and then connected to the load.
[0019] The discharge control circuit includes a control unit, a first battery pack, a second battery pack, a bidirectional DC-DC converter, and an ideal diode unit. The bidirectional DC-DC converter is connected to the control unit, the first battery pack, the second battery pack, and the ideal diode unit, respectively.
[0020] The control unit is connected to the first battery pack and the second battery pack, respectively. The ideal diode unit is connected to the load. In this embodiment, the control unit can be a single-chip microcontroller GD32F103C8T6.
[0021] A bidirectional DC-DC converter is used to achieve bidirectional power transfer. An ideal diode unit is used to control the on / off state of the current flowing to the load. A control unit controls the direction of the operating current of the bidirectional DC-DC converter based on the output voltages of the first and second battery packs. The bidirectional DC-DC converter includes two input and output terminals, connected to the first and second battery packs respectively.
[0022] In a preferred embodiment of this invention, the first battery pack and the second battery pack each include a BMS unit and a communication interface; the control unit is connected to the communication interface of the first battery pack through a first communication interface and a communication bus, and the control unit is connected to the communication interface of the second battery pack through a second communication interface and a communication bus. The communication bus is any one of IIC communication bus, UART communication bus, RS232 communication bus, RS485 communication bus, and CAN communication bus.
[0023] In a preferred embodiment of this invention, the ideal diode unit includes an ideal diode controller U1, a first power MOSFET Q1, and a second power MOSFET Q2. The ideal diode controller U1 includes two input terminals, two control terminals, and one output terminal.
[0024] The ideal diode controller U1 is connected to the source, gate, and drain of the first power MOSFET Q1, and to the source, gate, and drain of the second power MOSFET Q2. Specifically, the first input terminal IN1 of the ideal diode controller U1 is connected to the source of the first power MOSFET Q1, and the second input terminal IN2 is connected to the source of the second power MOSFET Q2. The first control terminal GATE1 of the ideal diode controller U1 is connected to the gate of the first power MOSFET Q1, and the second control terminal GATE2 is connected to the gate of the second power MOSFET Q2. The output terminal OUT of the ideal diode controller U1 is connected to the drain of the first power MOSFET Q1 and the drain of the second power MOSFET Q2. In this embodiment, the ideal diode controller U1 can be selected as the ideal diode controller CSV2555.
[0025] The source of the first power MOSFET Q1 is connected to the first battery pack and the bidirectional DC-DC converter, respectively. The source of the second power MOSFET Q2 is connected to the second battery pack and the bidirectional DC-DC converter, respectively. The drains of the first power MOSFET Q1 and the second power MOSFET Q2 are connected to the load, respectively.
[0026] In a preferred embodiment of this invention, the first power MOSFET Q1 and the second power MOSFET Q2 are both NMOS transistors.
[0027] The above connection method can be used to construct a control circuit system for parallel discharge of two battery packs.
[0028] When multiple batteries need to be connected in parallel for power supply, multiple sets of discharge control circuits can be set up, such as... Figure 2 As shown, the positive terminals of two battery packs are connected one-to-one with the two input terminals of an ideal diode unit, and the output terminals of multiple sets of ideal diode units of discharge control circuits are connected together to supply power to the load.
[0029] Next, the working principle of this embodiment will be described in detail so that those skilled in the art can better understand this utility model: The control unit obtains the voltage of the first battery pack 1 after communicating with the first battery pack 1 through the first communication interface 1, and obtains the voltage of the second battery pack 2 after communicating with the second battery pack 2 through the second communication interface unit 2.
[0030] The control unit compares the collected voltages of the first battery pack 1 and the second battery pack 2. When the voltage of the first battery pack 1 is greater than the voltage of the second battery pack 2, the control unit controls the bidirectional DC-DC converter to work, making the end of the bidirectional DC-DC converter connected to the first battery pack 1 the input terminal and the end of the bidirectional DC-DC converter connected to the second battery pack 2 the output terminal. The first battery pack 1 charges the second battery pack 2 through the bidirectional DC-DC converter. In this way, the first battery pack 1 not only charges the second battery pack 2, but can also supply power to the load through the ideal diode unit, while the second battery pack 2 does not discharge to the outside.
[0031] When the control unit detects that the voltage of the first battery pack 1 drops to the same level as the voltage of the second battery pack 2, the control unit controls the bidirectional DC-DC converter to stop working, the first battery pack 1 stops charging the second battery pack 2, and the first battery pack 1 and the second battery pack 2 simultaneously supply power to the outside through the ideal diode unit.
[0032] When the control unit detects that the voltage of the second battery pack 2 is greater than the voltage of the first battery pack 1, the control unit controls the bidirectional DC-DC converter to work, so that the end of the bidirectional DC-DC converter connected to the second battery pack 2 is used as the input terminal, and the end of the bidirectional DC-DC converter connected to the first battery pack 1 is used as the output terminal. The second battery pack 2 charges the first battery pack 1 through the bidirectional DC-DC converter. In this way, the second battery pack 2 not only charges the first battery pack 1, but can also supply power to the load through the ideal diode unit, while the first battery pack 1 does not discharge to the outside.
[0033] When the control unit detects that the voltage of the second battery pack 2 drops to the same level as the voltage of the first battery pack 1, the control unit controls the bidirectional DC-DC converter to stop working, and the second battery pack 2 no longer charges the first battery pack 1. The first battery pack 1 and the second battery pack 2 simultaneously supply power to the outside through the ideal diode unit. When the control unit detects the voltage of the newly connected second battery pack 2 and the first battery pack 1 and determines that the voltages are the same, the control unit controls the bidirectional DC-DC converter to stop working, and the first battery pack 1 and the second battery pack 2 can directly supply power to the outside simultaneously through the ideal diode unit. In this way, not only can the batteries be connected in parallel to achieve a long battery life, but the power supply capacity can also be increased after the batteries are connected in parallel.
[0034] In a battery parallel discharge control system, multiple batteries are connected one-to-one and then their output terminals are connected in parallel to form a system that can supply power to the outside through multiple batteries in parallel.
[0035] The ideal diode controller U1 collects the voltage difference between the source and gate of the first power MOSFET Q1 and the voltage difference between the source and gate of the second power MOSFET Q2 to determine the current direction. It then sends a signal to the gate of the first power MOSFET Q1 to control the first power MOSFET Q1 and sends a signal to the gate of the second power MOSFET Q2 to control the on / off state of the second power MOSFET Q2, so that the current can only flow from the source to the drain of the first / second MOSFET.
[0036] For example, when the ideal diode controller U1 detects a positive voltage difference between the source (S) and drain (D) terminals of the first power MOSFET Q1, it indicates that the first power MOSFET Q1 has a forward current. At this time, the ideal diode controller U1 controls the gate (G) terminal of the first power MOSFET Q1 to turn it on, thus controlling the forward voltage drop of the first power MOSFET Q1 to the mV level. When a power MOSFET with very low RDSon on-resistance is selected, the loss can be ignored.
[0037] When a negative voltage difference is detected between the source and drain terminals of the first power MOSFET Q1, it indicates that there is a reverse current in the first power MOSFET Q1. At this time, the ideal diode controller U1 controls the gate terminal of the first power MOSFET Q1 to turn off the first power MOSFET Q1, and the reverse current drops to zero.
[0038] Similarly, when the ideal diode controller U1 detects a positive voltage difference between the source (S) and drain (D) terminals of the second power MOSFET Q2, it indicates that a forward current exists in Q2. At this time, the ideal diode controller U1 controls the gate (G) terminal of Q2 to turn on Q2, keeping the forward voltage drop of Q2 within the mV range. When a power MOSFET with a very low on-resistance RDSon is selected, the loss can be ignored. When a negative voltage difference between the drain (D) and source (S) terminals of Q2 is detected, it indicates that a reverse current exists in Q2. At this time, the ideal diode controller U1 controls the gate (G) terminal of Q2 to turn off Q2, reducing the reverse current to zero. The reverse current turn-off time of the ideal diode controller U1 is less than 0.5µs.
[0039] In summary, the battery packs can achieve automatic balancing when discharged in parallel. That is, the higher voltage batteries will be discharged first, and they will be discharged together at the same time after the voltage of the battery packs is consistent. When there is a difference in voltage drop between the two battery packs, the voltage balancing time is shortened, thus improving the external power supply capacity.
[0040] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the present invention and are protected by patent law.
Claims
1. A battery parallel discharge control circuitry characterized by, It includes at least one set of discharge control circuits; the discharge control circuits include a control unit, a first battery pack, a second battery pack, a bidirectional DC-DC converter, and an ideal diode unit; The bidirectional DC-DC converter is connected to the control unit, the first battery pack, the second battery pack, and the ideal diode unit, respectively. The control unit is connected to the first battery pack and the second battery pack respectively; The ideal diode unit is connected to the load; A bidirectional DC-DC converter is used to achieve bidirectional power transmission; The ideal diode unit is used to control the on / off state of the current flowing to the load; The control unit is used to control the direction of the operating current of the bidirectional DC-DC converter according to the output voltage of the first battery pack and the second battery pack.
2. The battery parallel discharge control circuitry of claim 1, wherein, The first battery pack and the second battery pack each include a BMS unit and a communication interface; The control unit is connected to the communication interface of the first battery pack via a first communication interface and a communication bus, and the control unit is connected to the communication interface of the second battery pack via a second communication interface and a communication bus.
3. The battery parallel discharge control circuitry of claim 2, wherein, The communication bus is any one of the following: IIC communication bus, UART communication bus, RS232 communication bus, RS485 communication bus, and CAN communication bus.
4. The battery parallel discharge control circuitry of claim 1, wherein, The ideal diode unit includes an ideal diode controller, a first power MOSFET, and a second power MOSFET; The ideal diode controller is connected to the source, gate, and drain of the first power MOSFET, the source, gate, and drain of the second power MOSFET, respectively. The source of the first power MOSFET is connected to the first battery pack and the bidirectional DC-DC converter, respectively. The source of the second power MOSFET is connected to the second battery pack and the bidirectional DC-DC converter, respectively. The drains of the first power MOSFET and the second power MOSFET are connected to the load, respectively.
5. The battery parallel discharge control circuitry of claim 4, wherein, The first power MOSFET and the second power MOSFET are both NMOS transistors.