Vehicle Door Actuator PWM Frequency Control
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Solution Overview
Problem
Door opening/closing devices with motor-controlled PWM systems often generate louder sounds than expected due to resonance between the motor and its installation body during operation.
Innovation Solution
The door opening/closing device performs PWM control at a frequency that deviates from the resonance point of the motor and its installation body, reducing sound generation by setting the PWM frequency higher than the natural resonance frequency of the installation body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PWM control is performed at a standard frequency to operate the motor for door opening/closing, then the motor can effectively drive the door, but resonance occurs between the motor and installation body generating louder than expected sound
Solution Approach 1:
The patent applies parameter changes by adjusting the PWM frequency from a standard value to a value that deviates from the resonance frequency of the installation body. The control unit changes the frequency parameter of the PWM signal to avoid exciting resonant vibrations, thereby reducing sound noise while maintaining motor operation effectiveness.
Solution Approach 2:
The patent addresses mechanical vibration by identifying and avoiding the resonance frequency of the installation body. By setting the PWM frequency away from this resonance point, the patent prevents amplified vibrations that would generate excessive sound, thus solving the noise problem while maintaining effective motor control.
2Object-generated harmful factors
If PWM frequency is increased to avoid resonance and reduce sound, then sound pressure is minimized, but energy consumption and control complexity may increase
Solution Approach 1:
The patent optimizes the PWM frequency parameter to balance sound reduction with energy efficiency. Rather than simply increasing frequency, the control unit selects a frequency that deviates from resonance while considering energy consumption implications, achieving sound minimization without excessive energy cost.
Solution Approach 2:
The patent employs feedback mechanisms where the control unit monitors operational conditions and adjusts PWM frequency accordingly. This feedback approach allows the system to maintain optimal frequency settings that reduce sound pressure while adapting to varying operational requirements and minimizing unnecessary energy consumption.
3Object-generated harmful factors
If PWM frequency is adjusted to deviate from resonance point, then sound noise is reduced, but control complexity increases
Solution Approach 1:
The patent manages control complexity by implementing parameter changes through a control unit that adjusts PWM frequency. While this adds some control complexity, the patent integrates this functionality into existing motor control architecture, using standard PWM control mechanisms with modified frequency selection to avoid resonance.
Solution Approach 2:
The patent applies self-service by enabling the control unit to automatically determine and adjust the PWM frequency based on predetermined frequency ranges that avoid resonance. This automated frequency selection reduces the need for complex manual control and minimizes sound noise without requiring excessive intervention or complexity.
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 minimizes the sound pressure during door opening and closing operations, making the device quieter by avoiding resonance-related noise.
Implementation Method 1
a sound louder than expected may possibly be generated... resonance point between a motor and an installation body... performs PWM control at a PWM frequency set so as to deviate the resonance point
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A door opening/closing device includes a motor and a control unit that controls the rotation rate of the motor by pulse-width modulation (PWM) control. The door opening/closing device opens and closes a door of a vehicle with power of the motor. The control unit performs the PWM control on the motor at a PWM frequency set so as to deviate from a resonance point of an installation body on which the motor is installed. The installation body includes a housing unit that houses the motor, a fixing unit that fixes the door opening/closing device to the vehicle, and the vehicle. Thus, it is possible to provide the door opening/closing device that generates a small sound in an opening and closing operation.