A Wide-Voltage Active Balancing Circuit for On-Vehicle Battery Management System

Abstract

The present invention relates to the technical field of vehicle-mounted batteries, and in particular to a wide-voltage active equalization circuit for a vehicle-mounted battery management system, which includes a battery input terminal, a battery output terminal, a boost circuit, an absorption circuit, a transformer, a synchronous rectification control circuit, and a voltage stabilization circuit. The battery input terminal is externally connected to a battery, the battery input terminal is connected to the voltage stabilization circuit, the voltage stabilization circuit is connected to the synchronous rectification control circuit, the synchronous rectification control circuit is connected to the transformer, the transformer is connected to the boost circuit and the absorption circuit, and the absorption circuit and the boost circuit are both connected to the battery output terminal. The present invention adjusts the equalization main topology, innovates the output control circuit, and greatly optimizes the performance. Through the present invention, the active equalization type battery management system can be made more efficient and high-performance. The present invention has the advantages of high efficiency, high safety factor, low interference, and synchronous control.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-mounted batteries, and in particular to a wide-voltage active equalization circuit for a vehicle-mounted battery management system. Background Art

[0002] With the rapid development of the electric vehicle industry, the requirements for the service life and cruising range of electric vehicle batteries are getting higher and higher. Due to the production consistency problem of lithium batteries, there will be differences in the voltages of individual cells in the battery pack during operation. In order to extend the service life and safety of the battery, it is necessary to detect the voltages of individual cells in the battery pack and perform balanced charging and discharging on the inconsistent individual cells to keep the voltage values of individual cells consistent. Since passive equalization belongs to the energy consumption type and has limitations such as low equalization ability and few functions, the active equalization technology is introduced. This technology belongs to the energy transfer type and has advantages such as high efficiency and strong equalization ability. At the same time, this technology also introduces new problems, such as large EMI interference. With the rapid development of the electric vehicle industry, the requirements for the battery management system (BMS) are also getting higher and higher. Since the active equalization battery management system (BMS) generally uses a double flyback topology to manage the charging and discharging of individual cells, the current topology has low equalization efficiency, large EMI interference, and a small equalization range, and cannot perform good discharge equalization on low-voltage batteries such as lithium titanate. Summary of the Invention

[0003] The present invention provides a wide-voltage active equalization circuit for a vehicle-mounted battery management system to solve the problems of the prior art.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A wide-voltage active equalization circuit for a vehicle-mounted battery management system provided by the present invention includes a battery input terminal, a battery output terminal, a boost circuit, an absorption circuit, a transformer, a synchronous rectification control circuit, and a voltage stabilization circuit. The battery input terminal is externally connected to a battery. The battery input terminal is connected to the voltage stabilization circuit. The voltage stabilization circuit is connected to the synchronous rectification control circuit. The synchronous rectification control circuit is connected to the transformer. The transformer is connected to the boost circuit and the absorption circuit. The absorption circuit and the boost circuit are both connected to the battery output terminal.

[0006] Preferably, the boost circuit includes a capacitor C1, a capacitor C2, and an inductor L2. The boost circuit further includes an inductor L1, a capacitor C3, a triode Q1, and a triode Q2. The transformer includes a first winding N1, a second winding N2, a third winding N3, and a fourth winding N4. One end of the capacitor C1 and one end of the capacitor C2 are connected to the negative electrode of the battery. The other end of the capacitor C1 is connected to one end of the third winding N3. The other end of the capacitor C2 is connected to the inductor L2. One end of the inductor L1 is connected to the positive electrode of the battery. The other end of the inductor L1 is connected to the C electrode of the triode Q1. The E electrode of the triode Q1 is connected to the E electrode of the triode Q2. The C electrode of the triode Q2 is connected to one end of the first winding N1. One end of the capacitor C3 is connected to one end of the inductor L1. The other end of the capacitor C3 is connected to the negative electrode of the battery.

[0007] Preferably, the synchronous rectification control circuit includes a resistor R1, a capacitor C4, a diode D2, a resistor R2, and a triode Q3. The voltage regulation circuit includes a triode Q4, a resistor R3, and a capacitor C5. One end of the resistor R1, one end of the capacitor C4, and the input end of the diode D2 are connected to one end of the fourth winding N4. The other end of the resistor R1 and the other end of the capacitor C4 are both connected to the B electrode of the triode. The output end of the diode D2 is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the C electrode of the triode Q3. The E electrode of the triode Q3 is connected to the B electrode of the triode Q3. The C electrode of the triode Q3 is connected to one end of the second winding N2. The E electrode of the triode Q3 is connected to the negative electrode of the battery input end. One end of the resistor R3 is connected to the E electrode of the triode Q3. The other end of the resistor R3 is connected to the E electrode of the triode Q4. The capacitor C5 is respectively connected to the positive and negative electrodes of the battery input end.

[0008] Preferably, the negative electrode of the battery is grounded.

[0009] Preferably, the E electrodes of the triode Q1 and the triode Q2 are both connected to the negative electrode of the battery.

[0010] Preferably, the negative electrode of the battery input end is grounded.

[0011] Advantages of the present invention:

[0012] A wide-voltage active equalization circuit for a vehicle-mounted battery management system provided by the present invention includes a battery input terminal, a battery output terminal, a boost circuit, an absorption circuit, a transformer, a synchronous rectification control circuit, and a voltage stabilization circuit. The battery input terminal is externally connected to a battery. The battery input terminal is connected to the voltage stabilization circuit. The voltage stabilization circuit is connected to the synchronous rectification control circuit. The synchronous rectification control circuit is connected to the transformer. The transformer is connected to the boost circuit and the absorption circuit. The absorption circuit and the boost circuit are both connected to the battery output terminal. By adjusting the equalization main topology, innovating the output control circuit, and greatly optimizing the EMC performance, the active equalization type battery management system can be made more efficient and high-performance by the present invention. The present invention has the advantages of high efficiency, high safety factor, low interference, and synchronous control. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the circuit schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] For the convenience of understanding by those skilled in the art, the present invention will be further described below in conjunction with embodiments and the drawings. The content mentioned in the embodiments does not limit the present invention. The present invention will be described in detail below with reference to the drawings.

[0015] As Figure 1 shown, a wide-voltage active equalization circuit for a vehicle-mounted battery management system provided by the present invention includes a battery input terminal, a battery output terminal, a boost circuit, an absorption circuit, a transformer, a synchronous rectification control circuit, and a voltage stabilization circuit. The battery input terminal is externally connected to a battery. The battery input terminal is connected to the voltage stabilization circuit. The voltage stabilization circuit is connected to the synchronous rectification control circuit. The synchronous rectification control circuit is connected to the transformer. The transformer is connected to the boost circuit and the absorption circuit. The absorption circuit and the boost circuit are both connected to the battery output terminal. By adjusting the equalization main topology, innovating the output control circuit, and greatly optimizing the EMC performance, the active equalization type battery management system can be made more efficient and high-performance by the present invention. The present invention has the advantages of high efficiency, high safety factor, low interference, and synchronous control.

[0016] As Figure 1As shown, in this embodiment, the boost circuit includes capacitor C1, capacitor C2, and inductor L2. The boost circuit also includes inductor L1, capacitor C3, transistor Q1, and transistor Q2. The transformer includes first winding N1, second winding N2, third winding N3, and fourth winding N4. One end of capacitor C1 and one end of capacitor C2 are connected to the negative electrode of the battery. The other end of capacitor C1 is connected to one end of the third winding N3. The other end of capacitor C2 is connected to inductor L2. One end of inductor L1 is connected to the positive electrode of the battery. The other end of inductor L1 is connected to the C electrode of transistor Q1. The E electrode of transistor Q1 is connected to the E electrode of transistor Q2. The C electrode of transistor Q2 is connected to one end of the first winding N1. One end of capacitor C3 is connected to one end of inductor L1. The other end of capacitor C3 is connected to the negative electrode of the battery. The synchronous rectification control circuit includes resistor R1, capacitor C4, diode D2, resistor R2, and capacitor Q3. The voltage stabilization circuit includes transistor Q4, resistor R3, and capacitor C5. One end of resistor R1, one end of capacitor C4, and the input terminal of diode D2 are connected to one end of the fourth winding N4. The other end of resistor R1 and the other end of capacitor C4 are both connected to the B electrode of the transistor. The output terminal of diode D2 is connected to one end of resistor R2. The other end of resistor R2 is connected to the C electrode of transistor Q3. The E electrode of transistor Q3 is connected to the B electrode of transistor Q3. The C electrode of transistor Q3 is connected to one end of the second winding N2. The E electrode of transistor Q3 is connected to the negative electrode of the battery input terminal. One end of resistor R3 is connected to the E electrode of transistor Q3. The other end of resistor R3 is connected to the E electrode of transistor Q4. Capacitor C5 is connected to the positive and negative electrodes of the battery input terminal respectively.

[0017] As Figure 1 As shown, in this embodiment, the negative electrode of the battery is grounded. The E electrodes of transistor Q1 and transistor Q2 are both connected to the negative electrode of the battery. The negative electrode of the battery input terminal is grounded.

[0018] When the battery needs to be charged, the triode Q4 is directly controlled by an additional signal, so that the energy at the battery input terminal is directly transferred to the battery through the first winding N1 and the second winding N2. During the charging process, the triode Q1 is not controlled. When the first winding N1 and the second winding N2 are working, the capacitor C1 and the third winding N3 continuously charge and discharge the capacitor C1 at high frequency through the third winding N3, so that the energy of the transformer is slowly discharged through C1, thereby improving the EMI of the flyback power supply. When the battery needs to discharge, the triode Q1 and the inductor L1 are controlled to increase the battery voltage. At the same time, due to the action of the inductor L2 and the capacitor C2, the interference at the node of the triode Q1 and the inductor L1 will be reduced. When the triode Q2 is closed, the energy is stored in the first winding N1. When the triode Q2 is disconnected, the energy of the first winding N1 is respectively transmitted to the second winding N2, the third winding N3 and the fourth winding N4. Among them, the third winding N3 and the capacitor C1 mainly absorb the energy of the capacitor C2 and the inductor L2, and the fourth winding N4 will turn on the triode Q3 through the synchronous rectification control circuit and control the conduction of the triode Q4 to achieve synchronous rectification. The second winding N2 mainly transmits the energy of the battery.

[0019] Through the above management of battery charging and discharging, the active equalization control of the BMS is realized. The main topology is a double flyback topology composed of the triode Q2, the triode Q4, the first winding N1 and the second winding N2. The capacitor C1 and the third winding N3 mainly absorb the transformer EMI interference of the first winding N1, the second winding N2 and the fourth winding N4. The inductor L1 and the triode Q1 mainly boost the battery voltage, which is a BOOST circuit. The present invention can support low-voltage discharge, making the equalization voltage range of the battery wider; adopting isolated DCDC makes the equalization circuit safer and more reliable; adopting active synchronous rectification makes the efficiency higher; adopting magnetic core coupling effectively reduces electromagnetic interference; adopting BOOST + double flyback topology makes it more efficient during low-voltage discharge; the circuit of the present invention is simple and reasonable in design, and can effectively reduce the production cost.

[0020] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention is disclosed above in a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, when making some changes or modifications using the above-disclosed technical content into equivalent embodiments of equivalent changes, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical meaning of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A wide-voltage active equalization circuit for a vehicle-mounted battery management system, characterized in that: It includes a battery input terminal, a battery output terminal, a boost circuit, an absorption circuit, a transformer, a synchronous rectification control circuit, and a voltage stabilization circuit. The battery input terminal is externally connected to a battery. The battery input terminal is connected to the voltage stabilization circuit. The voltage stabilization circuit is connected to the synchronous rectification control circuit. The synchronous rectification control circuit is connected to the transformer. The transformer is connected to the boost circuit and the absorption circuit. The absorption circuit and the boost circuit are both connected to the battery output terminal; The boost circuit includes capacitor C1, capacitor C2, and inductor L2. The boost circuit includes inductor L1, capacitor C3, triode Q1, and triode Q2. The transformer includes a first winding N1, a second winding N2, a third winding N3, and a fourth winding N4. One end of capacitor C1 and one end of capacitor C2 are connected to the negative electrode of the battery. The other end of capacitor C1 is connected to one end of the third winding N3. The other end of capacitor C2 is connected to inductor L2. One end of inductor L1 is connected to the positive electrode of the battery. The other end of inductor L1 is connected to the C pole of triode Q1. The E pole of triode Q1 is connected to the E pole of triode Q2. The C pole of triode Q2 is connected to one end of the first winding N1. One end of capacitor C3 is connected to one end of inductor L1. The other end of capacitor C3 is connected to the negative electrode of the battery; The synchronous rectification control circuit includes resistor R1, capacitor C4, diode D2, resistor R2, and capacitor Q3. The voltage stabilization circuit includes triode Q4, resistor R3, and capacitor C5. One end of resistor R1, one end of capacitor C4, and the input end of diode D2 are connected to one end of the fourth winding N4. The other end of resistor R1 and the other end of capacitor C4 are both connected to the B pole of the triode. The output end of diode D2 is connected to one end of resistor R2. The other end of resistor R2 is connected to the C pole of triode Q3. The E pole of triode Q3 is connected to the B pole of triode Q3. The C pole of triode Q3 is connected to one end of the second winding N2. The E pole of triode Q3 is connected to the negative electrode of the battery input terminal. One end of resistor R3 is connected to the E pole of triode Q3. The other end of resistor R3 is connected to the E pole of triode Q4. Capacitor C5 is respectively connected to the positive and negative electrodes of the battery input terminal; The negative electrode of the battery is grounded. The E poles of triode Q1 and triode Q2 are both connected to the negative electrode of the battery. The negative electrode of the battery input terminal is grounded.

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