Vehicle Battery Heating via Transverse Current Without Torque Disturbance
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Solution Overview
Problem
Existing methods for heating vehicle batteries are inefficient due to heat losses during warming of the cell casing, leading to insufficient heating of the internal active material, especially at low temperatures, and can cause stress on the rotor components.
Innovation Solution
A method using a pulse inverter and a separately excited synchronous machine to generate a periodic transverse current with a high frequency, modulated in the iq-id machine field, which heats the battery without affecting the rotational speed or torque, minimizing feedback effects on the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If additional current is applied to heat the battery, then heating effectiveness improves, but feedback effects on the rotor cause component stress
Solution Approach 1:
The patent applies periodic pulsed current to the electric machine windings rather than continuous current. This periodic action generates heat effectively while allowing the rotor to maintain its rotational speed through inertia during the pulse intervals, thereby avoiding feedback effects and component stress.
Solution Approach 2:
The control unit preliminarily determines the optimal pulse duration and amplitude based on battery temperature requirements before applying the heating current. This preliminary assessment ensures that the heating current is applied in a controlled manner that achieves heating effectiveness without causing excessive rotor stress.
2Loss of energy
If the electric machine is used for heating, then heating efficiency improves, but the rotational speed and torque are affected
Solution Approach 1:
The patent employs periodic pulsed current application to the electric machine windings. During each pulse, heat is generated efficiently in the windings, while between pulses the rotor maintains its rotational speed through inertia. This periodic action decouples the heating process from continuous torque generation, preventing speed fluctuations.
Solution Approach 2:
The control unit dynamically adjusts the pulse current parameters (amplitude, duration, frequency) based on real-time monitoring of rotational speed and temperature. By changing these parameters adaptively, the system optimizes heating efficiency while maintaining rotational speed within acceptable ranges.
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 internal active material of the battery without causing thermal stress on the rotor, ensuring efficient heating and maintaining consistent torque and speed.
Implementation Method 1
A further method is known from DE 10 2022 207 314 A1. The additional current is designed and applied in such a way that it does not impair the vehicle's drive; that is, the additional current does not cause any change in the speed of an electric machine powered by the drive current, nor does it produce any additional torque, but is instead converted into heat.
Data Source
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AI summary
The invention relates to a method for heating a vehicle battery (51) of a motor vehicle (50), wherein the motor vehicle (50) has a pulse inverter (2) and an electric machine (52), wherein the electric machine (52) is designed as a separately excited synchronous machine (53), wherein a magnetic flux (ψ) is assigned to a rotational speed (n) of the electric machine (52) by means of an assignment rule (4), wherein a longitudinal current (id) and a transverse current (iq) are assigned to the magnetic flux (ψ) and a torque (T) by means of assignment rules (5, 6), wherein a periodic additional flux (Δz) is generated which is supplied only to the assignment rule (6) for the transverse current (iq), wherein the modulation of the periodic additional flux (ψz) takes place in a region (S) of an iq-id machine characteristic map in which the lines of constant torque (T) run almost vertically, and an arrangement (1).