Permanent Magnet Motor Frequency Control for Battery Self-Heating Noise Reduction
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Solution Overview
Problem
Existing methods for heating power batteries in electric vehicles, such as using the motor's internal resistance, result in excessive noise due to motor vibrations caused by resonance frequencies, affecting the comfort and performance of electric vehicles.
Innovation Solution
A method and apparatus for controlling a permanent magnet motor by determining the resonance frequency band of the motor and setting the power frequency outside this band, using alternating current to heat the battery while avoiding resonance frequencies, thereby reducing noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the motor is used for heating the power battery through internal resistance, then the heating effect is achieved, but excessive noise is generated due to motor vibrations at resonance frequencies
Solution Approach 1:
The patent changes the operating parameters of the motor by adjusting the power frequency to avoid resonance frequencies. Specifically, it sets the power frequency such that even multiples fall outside the resonance frequency band, thereby eliminating vibrations and noise while maintaining the heating function through internal resistance.
2Productivity
If the power frequency is set to achieve effective heating, then heating efficiency is improved, but motor vibrations occur due to resonance frequencies
Solution Approach 1:
The patent modifies the power frequency parameter to avoid resonance conditions. By calculating the resonance frequency band of the motor and setting the power frequency such that its even multiples lie outside this band, the system achieves effective heating without inducing vibrations that would reduce productivity or cause mechanical issues.
3Loss of energy
If alternating current excitation is applied to heat the battery through the motor, then the self-heating condition is met, but noise and vibrations increase due to resonance
Solution Approach 1:
The patent optimizes the power frequency parameter to eliminate resonance vibrations while maintaining the alternating current excitation needed for heating. By carefully selecting the power frequency so that even multiples avoid the resonance frequency band, the system achieves effective energy dissipation through internal resistance without generating excessive noise.
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
This approach effectively reduces noise and vibrations during the self-heating process of power batteries, enhancing the comfort and performance of electric vehicles by eliminating main vibration sources and improving NVH (Noise, Vibration, Harshness) indicators.
Implementation Method 1
the power battery and a stator winding form a closed loop, and the stator winding stores electric energy. Since an internal resistance of the power battery is relatively large in a low-temperature environment, a power battery winding applies alternating current excitation to the power battery, and the power battery uses its own internal resistance for heating
Implementation Method 2
there is too much noise during a process of heating the power battery through the motor
Data Source
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AI summary
A method and an apparatus for controlling a permanent magnet motor (30), a power system (100) and an electric vehicle. A power frequency of the permanent magnet motor (30) is set by obtaining system parameters such as a resonance bandwidth of the permanent magnet motor (30) and a natural frequency of a stator of the permanent magnet motor (30), and the permanent magnet motor (30) is supplied power by using alternating current at the power frequency when a power battery (10) meets a self-heating condition. Noises generated by the motor (30) is reduced during a self-heating process of the power battery (10).