Electric Drive Current Control for In-Motion Battery Heating
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Solution Overview
Problem
The charging and discharging capacity of power batteries in vehicles is limited in cold areas due to low temperatures, and existing methods for heating using electric motor waste heat are not effectively controllable, limiting their application to stationary vehicles.
Innovation Solution
A control method for an electric drive system that adjusts the direct and quadrature axis currents of an electric motor to generate heat, allowing dynamic heat generation during vehicle operation, using a software-based approach without hardware changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If electric motor waste heat is used to heat the power battery, then the heating effect is improved, but the controllability of heat generation is poor
Solution Approach 1:
The patent changes the operating parameters of the electric motor (direct axis current and quadrature axis current) to control the heat generation rate. By adjusting these current parameters, the system can precisely control how much heat is generated during motor operation, directly resolving the controllability issue while maintaining improved battery temperature.
2Temperature
If the electric motor is controlled to generate heat during vehicle operation, then the heating effectiveness is improved, but the shaft torque output may affect vehicle stability
Solution Approach 1:
The patent dynamically adjusts the direct axis and quadrature axis currents based on real-time operating conditions. This dynamic control allows the system to optimize heat generation while maintaining stable shaft torque output, preventing vehicle jitter and ensuring stability during operation.
Solution Approach 2:
The system uses feedback control by monitoring the operating point and adjusting the current parameters accordingly. This ensures that the shaft torque remains stable for vehicle operation while the heat generation rate is optimized for battery heating, resolving the contradiction between heating effectiveness and vehicle stability.
3Temperature
If existing heating methods are used, then the power battery heating is improved, but the application is limited to stationary vehicles
Solution Approach 1:
The patent makes the electric motor serve multiple functions: it can operate as a drive motor during vehicle motion and as a heat generation device during braking or idle periods. This multi-functionality allows the heating system to work effectively in both stationary and moving vehicle scenarios, greatly expanding the application range.
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
Enables effective thermal management of vehicles in cold conditions by accelerating heat generation in the power battery and electric drive system, maintaining vehicle functionality and reducing the need for hardware modifications.
Implementation Method 1
the heat generation rates of the electric drive system and the power battery itself are accelerated by adjusting a direct axis current value and a quadrature axis current value of an electric motor
Data Source
AI summary
A control method for an electric drive system of a vehicle, includes: acquiring a shaft torque of the electric motor and a present operating point of the vehicle in response to a vehicle heating demand signal; acquiring a present heat generation power of the electric drive system accordingly; determining a current adjustment amplitude accordingly; acquiring a three-phase current value and a position value of the electric motor, and a present direct axis current value and a present quadrature axis current value of the electric motor at the present operating point accordingly; controlling the present direct axis current value to oscillate at a change frequency and the current adjustment amplitude to obtain a target direct axis current value; acquiring a target quadrature axis current value accordingly; acquiring an electric motor drive signal accordingly.