Motor Controller Sound Injection Voltage for Acoustic Signal Generation
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Solution Overview
Problem
Electric machines used in vehicles and mobile devices often generate inaudible or undesirable acoustic sounds, which can be a concern for safety and perception, especially in situations where audible notification or masking of motor noise is required.
Innovation Solution
A motor drive system incorporating an inverter and a motor controller that combines torque control with acoustic signal generation, using a sound injection voltage to produce audible sounds coincident with torque and speed control, ensuring the acoustic signals are within frequency ranges that do not interfere with the motor's primary operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric machine operates to generate torque, then the motor produces audible acoustic sound, but the sound may not be readily perceptible under certain circumstances
Solution Approach 1:
The control system segments the voltage control into two independent components: initial output voltage for torque control and sound injection voltage for acoustic signal generation. This segmentation allows each component to be optimized independently - the torque control maintains force generation while the sound injection adds audible signals without disrupting the primary function.
Solution Approach 2:
The patent merges the torque control function and acoustic signal generation function into a single integrated control system. The motor controller combines the initial output voltage and sound injection voltage to generate PWM commands, allowing both torque production and audible sound generation to occur simultaneously through the same power electronics infrastructure.
2Reliability
If the motor controller generates audible acoustic signals, then pedestrian notification or noise masking is achieved, but the acoustic signals must not interfere with the motor's primary torque and speed control
Solution Approach 1:
The sound injection voltage is designed as a partial action that adds only the necessary acoustic signal component without attempting to control the full motor output. By injecting only the minimal voltage required for audible signal generation into the existing torque control framework, the system achieves acoustic notification while leaving the primary torque and speed control unaffected.
Solution Approach 2:
The PWM generation process acts as an intermediary that reconciles the torque control requirements and sound injection requirements. The motor controller uses PWM modulation to combine the initial output voltage and sound injection voltage, allowing both control objectives to be achieved through the same power electronics without direct interference between the two functions.
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 system effectively generates audible acoustic sounds that can notify pedestrians or mask motor noise without disrupting the electric machine's torque and speed control, enhancing safety and operational flexibility.
Implementation Method 1
The inverter includes a plurality of paired power transistors that are electrically connected to the electric machine, wherein the inverter is electrically connected to a DC power source via a high-voltage electrical power bus. The motor controller is disposed to generate pulsewidth-modulated (PWM) commands to control the paired power transistors of the inverter
Data Source
AI summary
A motor drive system for controlling operation of an electric machine is described. An inverter includes paired power transistors that are electrically connected to the electric machine, wherein the inverter is electrically connected to a DC power source via a high-voltage electrical power bus. A motor controller includes a first controller and an acoustic signal generator, wherein the first controller is disposed to control the paired power transistors of the inverter. The first controller determines an initial output voltage based upon a torque command and the acoustic signal generator is disposed to generate a sound injection voltage. The motor controller combines the initial output voltage and the sound injection voltage. The motor controller generates PWM commands to control the paired power transistors of the inverter, wherein the PWM commands are determined based upon the initial output voltage and the sound injection voltage.