EV Inverter Frequency Modulation for Quiet Battery Heating
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Solution Overview
Problem
Existing methods for heating power batteries in electric vehicles, such as using the internal resistance of the motor, lead to unbalanced magnetic fields and increased noise and vibration due to changes in magnetic field distribution during the heating process.
Innovation Solution
A control method that generates alternating currents with randomly changing frequencies and periodically changing amplitudes to distribute radial electromagnetic forces more evenly across the stator, reducing vibration noises during the heating process by using a first and second control signal to manage the inverter's power supply to the permanent magnet motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If alternating current with fixed frequency is used to heat the power battery through the permanent magnet motor, then the heating efficiency is improved, but the motor generates large vibration noises due to unbalanced magnetic field distribution
Solution Approach 1:
The patent applies dynamics principle by randomly changing the frequency of alternating current supplied to the permanent magnet motor during battery heating. Instead of using fixed frequency, the system dynamically adjusts frequency within a range (e.g., 50Hz±10Hz) to prevent concentrated radial electromagnetic forces from causing vibration and noise, while maintaining heating efficiency through continuous energy delivery to the battery.
Solution Approach 2:
The patent implements parameter changes by modifying the frequency parameter of the alternating current. The control system changes frequency from a fixed value to a variable parameter that fluctuates randomly within specified bounds. This parameter variation redistributes electromagnetic forces in the motor, eliminating the concentration effect that causes noise while preserving the heating function.
2Object-affected harmful factors
If the energization frequency is set to reduce noise, then the magnetic field distribution changes, but the motor generates more noises due to unbalanced internal forces
Solution Approach 1:
The system resolves the contradiction by making the frequency dynamic rather than static. Random frequency changes prevent the magnetic field from settling into an unstable pattern that would cause noise, while the continuous variation maintains overall magnetic field stability. The randomness acts as a stabilizing mechanism by preventing resonant conditions.
Solution Approach 2:
The patent applies periodic action through random frequency modulation. The frequency varies periodically within a defined range, creating a pattern of electromagnetic force distribution that prevents concentration at any single frequency. This periodic variation ensures balanced internal forces while maintaining heating effectiveness.
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
The solution effectively reduces vibration noises during the heating process of power batteries by introducing new frequency components, ensuring efficient and quiet operation of electric vehicles in low-temperature conditions.
Implementation Method 1
the first control signal is configured to control the inverter to convert a current provided by the power battery into an alternating current with a randomly changing frequency
Implementation Method 2
The internal resistance of the power battery is usually used to heat the power battery
Data Source
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AI summary
The present application provides a control method, an apparatus, a power system, and an electric vehicle, relating to the field of electric vehicles. The method includes: obtaining a battery cell temperature of a power battery, and sending a first control signal to an inverter when the battery cell temperature meets a preset power battery heating condition, where the first control signal is configured to control the inverter to convert a current provided by the power battery into an alternating current with a randomly changing frequency, and the alternating current with a randomly changing frequency is configured to supply power to a permanent magnet motor. New frequency components may be introduced to evenly distribute originally concentrated radial electromagnetic forces to an entire stator, thereby reducing vibration noises during the heating process of the power battery.