Battery Pack Precharge Control for Variable Load Capacitance
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Solution Overview
Problem
Conventional battery packs are limited to precharging with loads of known capacitance, requiring a measurement module for direct capacitance measurement, which is inefficient and incompatible with unknown or varying load capacitances.
Innovation Solution
A battery pack system that includes a communication part to receive capacitance from a connected load, a controller to calculate a duty ratio based on the capacitance, and a precharge relay to perform precharging accordingly, with a storage part to map and update identification and capacitance information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measurement module is added to directly measure capacitance, then capacitance measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a communication part as an intermediary between the load and controller. The load's control unit transmits capacitance information through this communication interface, allowing the controller to obtain capacitance data without requiring direct measurement hardware. This mediator approach resolves the contradiction by enabling measurement capability through information exchange rather than physical measurement components.
2Reliability
If the battery pack is designed to work with loads of known capacitance only, then compatibility is improved for specified loads, but adaptability to various loads deteriorates
Solution Approach 1:
The patent makes the precharge system dynamic by enabling the controller to adaptively adjust precharge parameters based on actual load capacitance values received through communication. Instead of being fixed for specific load types, the system dynamically configures precharge resistance and time according to the connected load's characteristics, thereby achieving both reliability for specified loads and adaptability for various loads.
Solution Approach 2:
The patent changes the operating parameters of the precharge circuit based on received capacitance information. The controller adjusts precharge resistance values and charging time parameters according to the actual load characteristics, allowing the same hardware to reliably serve multiple load types with different capacitance values without requiring fixed design assumptions.
3Measurement precision
If capacitance information is obtained through direct measurement, then measurement accuracy is improved, but loss of time increases due to measurement process
Solution Approach 1:
The patent applies preliminary action by having the load's control unit prepare and transmit capacitance information in advance through the communication interface before the precharge operation begins. This eliminates the need for real-time measurement during the precharge process, as the information is already available from the load side, thus maintaining accuracy while minimizing time loss.
Solution Approach 2:
The patent implements a feedback mechanism where the load's control unit provides capacitance information back to the battery pack's controller through the communication interface. This feedback loop allows the controller to obtain accurate capacitance data without performing measurement, as the load itself supplies the information based on its internal knowledge or pre-measurement, reducing the time burden on the precharge system.
Data Source
AI summary
A battery pack includes a battery cell, a main relay provided on a charging and discharging path of the battery cell, a precharge relay, a precharge resistor, the precharge relay and the precharge resistor being connected in parallel to the main relay on the charging and discharging path, a connector connected to a load including a capacitor; a communication part receiving a capacitance of the capacitor from the load through the connector, when the load is connected to the connector, and a controller obtaining the capacitance from the communication part, calculating a duty ratio corresponding to the capacitance, and precharging the capacitor by controlling an operation state of the precharge relay according to the calculated duty ratio.