Battery Voltage Stabilization via Dynamic Motor Torque Control
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Solution Overview
Problem
Electric vehicle batteries experience significant voltage drops at low state of charge (SOC) and low temperatures, leading to reduced system efficiency and power output, which existing methods attempt to mitigate by increasing reference voltage but at the cost of disturbing efficiency and weight reduction.
Innovation Solution
An apparatus and method that calculate an expected voltage of the battery cell using sensing information, including SOC, temperature, and motor torque, to control motor torque quantity, thereby stabilizing battery voltage by adjusting torque based on the comparison between expected and reference voltages, using the Equation Expected Voltage=Current Voltage−dV/d (RPM)×Change Quantity Of RPM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference voltage of PE-based parts is increased to prevent voltage drop, then the minimum voltage of the battery is improved, but the system efficiency deteriorates and weight reduction is compromised
Solution Approach 1:
The patent applies dynamics by making the reference voltage adjustable rather than fixed. The reference voltage is dynamically changed based on battery temperature and state of charge (SOC) conditions, allowing the system to optimize between minimum voltage requirements and system efficiency/weight reduction goals under different operating conditions
Solution Approach 2:
The patent changes the parameter of reference voltage based on temperature and SOC conditions. By adjusting the reference voltage parameter according to actual battery state, the system prevents voltage drop when needed while maintaining efficiency and weight reduction benefits under normal conditions
2Reliability
If the reference voltage is increased to stabilize battery voltage, then the voltage drop is reduced, but the power output is reduced at low temperature
Solution Approach 1:
The patent changes the reference voltage parameter based on temperature and SOC conditions. At low temperatures, the reference voltage is adjusted to prevent voltage drop while accounting for the reduced power output capability, thereby stabilizing voltage without excessively limiting power
3Reliability
If the maximum output quantity is reduced to prevent voltage drop, then the voltage stability is improved, but the system efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the reference voltage based on real-time battery conditions (temperature and SOC) rather than using a fixed conservative output limit. This allows the system to maintain voltage stability while maximizing efficiency under varying operating conditions
Data Source
AI summary
An apparatus for alleviating a voltage drop of a battery cell includes a battery having a plurality of battery cells, a sensor configured to sense the battery to generate sensing information, a calculator configured to calculate an allowable torque of a motor using the sensing information and calculate an expected voltage of the battery using the allowable torque and the sensing information, and a determinator configured to control a torque quantity of the motor using the expected voltage and a reference voltage.