Electric Motor Acoustic Controller Torque Modulation
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Solution Overview
Problem
Electric motor vehicles are difficult to notice due to their quiet operation, leading to safety concerns, and existing sound generation methods using loudspeakers are costly and may not meet electromagnetic tolerance requirements, while perceived high-frequency sounds from electric motors are unpleasant.
Innovation Solution
A method where a vehicle dynamics controller transmits a driving-performance-related torque setpoint to an acoustic controller, which modulates the torque pattern based on the phase angle of the electric motor to generate a dynamic torque setpoint that mimics the sound of a combustion engine, allowing the electric motor to produce a driving sound without a loudspeaker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a loudspeaker is installed to generate driving sounds, then the vehicle becomes easier to notice and safety is improved, but the production costs increase and technical effort is required
Solution Approach 1:
The electric motor serves dual purposes: providing propulsion torque and generating acoustic signals. By modulating the torque setpoint, the motor itself produces the required driving sounds without needing separate loudspeaker hardware, thereby reducing production costs while maintaining safety
Solution Approach 2:
The electric motor is made multi-functional by enabling it to perform both its primary function (propulsion) and a secondary function (acoustic signal generation). The acoustic controller modifies the torque command to simultaneously achieve both objectives through a single component
2Device complexity
If high-frequency electrical signals are used to generate sound through magnetostriction, then a loudspeaker is not needed, but the electromagnetic tolerance requirements cannot be met
Solution Approach 1:
Instead of using high-frequency electrical signals that cause magnetostriction, this invention changes the approach by using low-frequency torque modulation. The acoustic controller modifies the torque setpoint at audible frequencies without generating harmful high-frequency electromagnetic signals, thus meeting electromagnetic tolerance requirements
3Object-generated harmful factors
If high-frequency sounds are generated by electric motors, then sound generation is achieved, but humans perceive the sounds as unpleasant
Solution Approach 1:
The invention changes the frequency parameters of the generated sound by modulating torque at audible frequencies rather than using high-frequency magnetostriction. This produces pleasant driving sounds that resemble conventional vehicle noises, improving user acceptance while still achieving the required acoustic signal generation
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 method effectively generates an authentic driving sound that meets regulatory requirements, enhancing vehicle visibility and safety without the need for a sound generation device, while maintaining electromagnetic tolerance and user preference.
Implementation Method 1
A phase angle of a rotor of an electric motor is transmitted to the acoustic controller via power electronics. The acoustic controller modulates onto the torque setpoint at least one torque pattern which depends on the phase angle of the rotor of the electric motor.
Data Source
AI summary
The present disclosure relates to a method for operating an electric motor, wherein a vehicle dynamics controller transmits a driving-performance-related torque setpoint to an acoustic controller configured as a control device. The acoustic controller receives an input value for defining an acoustic signal as well as a phase angle of a rotor of the electric motor from the power electronics as well. To generate a dynamic torque setpoint, the acoustic controller modulates onto the driving-performance-related torque setpoint at least one torque pattern that depends on the phase angle of the rotor of the electric motor, wherein the dynamic torque setpoint is such that a sound according to the input value is generated by the electric motor and/or a drive train. The dynamic torque setpoint is transmitted to power electronics.