Battery Resonant Heating Using D-Axis Current Control
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Solution Overview
Problem
Electric vehicle batteries and fuel cells perform suboptimally in cold winter temperatures due to being outside their nominal operating range, leading to reduced performance and efficiency.
Innovation Solution
A system and method that uses an inverter and electric machine to generate heating power for the battery or fuel cell by adjusting the d-axis and q-axis currents, while maintaining the switching frequency, to increase heating power and maintain performance in low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching frequency of the inverter is increased to generate more heating power for the battery, then the heating power increases, but the switching losses and thermal stress on the inverter components increase
Solution Approach 1:
The patent changes the control parameters from switching frequency to d-axis and q-axis currents. By adjusting the d-axis current to create a virtual flux and coordinating the q-axis current, the system achieves variable heating power without changing the switching frequency, thus avoiding increased switching losses and thermal stress while still meeting heating requirements
Solution Approach 2:
The patent replaces the traditional mechanical/electrical approach of varying switching frequency with a control theory approach using d-q axis current decomposition. This substitution allows precise control of heating power through electromagnetic field control rather than direct switching frequency manipulation, reducing harmful switching effects
2Power
If additional heating components are added to the battery system to provide sufficient heating power in cold conditions, then the heating capability improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the inverter and electric machine perform dual functions: propulsion and heating. By utilizing the existing inverter and electric machine for both driving and heating purposes through d-q axis current control, no additional heating components are needed, maintaining system simplicity while providing sufficient heating capability
Solution Approach 2:
The system uses its own existing components (inverter and electric machine) to provide heating service to the battery. The inverter generates AC current and the electric machine converts it to heating power, making the system self-sufficient for heating without requiring external or additional heating devices
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively heats the battery or fuel cell to optimal operating temperatures, ensuring consistent performance and efficiency even in cold conditions without altering the switching frequency, thus addressing the performance issues in low temperatures.
Implementation Method 1
The controller switches the inverter at a switching frequency selected to generate an AC current to heat the battery
Implementation Method 2
adjusts a d-axis current of the electric machine to increase a battery heating power
Data Source
AI summary
A vehicle includes an electric machine, a battery, an inverter, and a controller. The controller switches the inverter at a switching frequency selected to generate an AC current to heat the battery, adjusts a d-axis current of the electric machine to increase a battery heating power, and adjusts a q-axis current of the electric machine according to the adjusted d-axis current.