一种可扩展串联的安全型锂电池包电路结构
By introducing a fast recovery diode connected in series at the OC/OD pin and an NPN transistor connected at the CS pin in the lithium battery pack circuit, the withstand voltage of the MOSFET is enhanced, and a current sharing circuit is introduced to regulate the current, thus solving the breakdown risk of the lithium battery pack when connected in series and realizing the flexible expansion and cost reduction of the safe lithium battery pack.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CELLTECH (ZHONGSHAN) LTD
- Filing Date
- 2025-07-29
- Publication Date
- 2026-07-17
AI Technical Summary
When existing lithium battery packs have built-in protection circuits with a fixed number of units connected in series, the protection IC or MOSFET is easily damaged due to voltage superposition, which can lead to short circuits and fire risks. Furthermore, they cannot be flexibly combined or expanded.
Design a scalable series-connected safe lithium battery pack circuit structure. A fast recovery diode is connected in series through the OC/OD pin and an NPN transistor is connected through the CS pin to enhance the voltage withstand capability of the MOSFET. A current sharing circuit is introduced to regulate the current, enabling a single pack to work independently or be safely connected in series.
It solves the risk of breakdown when lithium battery packs are connected in series, enables flexible expansion and safety protection, reduces the risk of device damage, and lowers the cost of use.
Smart Images
Figure CN224520692U_ABST
Abstract
Claims
1. A scalable series-connected safe lithium battery pack circuit structure, characterized in that, The circuit structure includes a protection ICU1, a discharge MOSFET Q2, a charging MOSFET Q3, and at least two battery cells B1 and B3 connected in series. The OC pin of the protection IC U1 is connected in series with the first isolation diode D3 and then connected to the gate of the charging MOSFET Q3; The OD pin of the protection IC U1 is connected in series with the second isolation diode D4 and then connected to the gate of the discharge MOSFET Q2; The CS pin of the protection IC U1 is connected to the base of the NPN transistor Q1, the emitter of the NPN transistor Q1 is grounded, and the collector is connected to the negative terminal of the battery cell through the sampling resistor R1.
2. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, The first isolation diode D3 and the second isolation diode D4 are fast recovery diodes, model number 1N4148.
3. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, The circuit structure also includes a current sharing circuit, which is composed of a first operational amplifier U3, a second operational amplifier U4, a first current sharing MOSFET Q7, and a second current sharing MOSFET Q8. The non-inverting input terminal of the first operational amplifier U3 is connected to the positive terminal of the battery cell B1, the inverting input terminal is connected to the positive terminal of the battery cell B3, and the output terminal is connected to the gate of the first current-sharing MOSFET Q7. The non-inverting input of the second operational amplifier U4 is connected to the positive terminal of cell B3, the inverting input is connected to the positive terminal of cell B1, and the output is connected to the gate of the second current-sharing MOSFET Q8.
4. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, The first isolation diode D3 and the second isolation diode D4 are replaced with TVS diodes or Zener diodes.
5. The scalable series-connected safety lithium battery pack circuit structure as described in claim 1, characterized in that, The withstand voltage of both the discharge MOSFET Q2 and the charge MOSFET Q3 is ≥40V.
6. The scalable series-connected safe lithium battery pack circuit structure of claim 5, wherein, The discharge MOSFET Q2 and charge MOSFET Q3 are replaced with IGBTs or SiC MOSFETs with a withstand voltage of ≥40V.
7. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, A current-limiting resistor R2 is connected in series between the collector of the NPN transistor Q1 and the sampling resistor R1, with a resistance value ranging from 1 to 10 kΩ.
8. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, A filter capacitor C1 with a capacitance of 0.1-10μF is provided between the VDD pin of the protection IC U1 and the positive terminal of the battery cell B1.
9. The scalable series-connected safe lithium battery pack circuit structure of claim 3, wherein, The sources of the first current-sharing MOSFET Q7 and the second current-sharing MOSFET Q8 are connected to a common current-sharing resistor R5.
10. The scalable series-connected safe lithium battery pack circuit structure of claim 1, wherein, At least two battery cells are connected in series via a series copper busbar, a positive terminal connector, and a negative terminal connector. The positive terminal of the battery cell is also covered with insulating paper. A circuit board is connected to the series copper busbar. The protection IC U1, the discharge MOSFET Q2, and the charging MOSFET Q3 are mounted on the circuit board. The series-connected battery cells are set on a battery cell support. The battery cell support is also covered with heat shrink tubing and a label is attached to the outside of the heat shrink tubing.