Motor Driving Controller Switching Waveforms to Reduce Starting Noise
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Solution Overview
Problem
Conventional motor driving controllers for brushless motors generate uncomfortable starting noises due to rectangular wave driving, which are not effectively mitigated by existing methods that increase mass and cost, such as enhancing motor rigidity or using vibration-absorbing components.
Innovation Solution
A motor driving controller that includes a rotary position detection device and a control circuit capable of switching between rectangular wave driving and sine wave driving based on the detected rotary position, shortening the duration of rectangular wave driving to reduce starting noise discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rectangular wave driving is used at the time of starting, then the motor can be started reliably with large output torque, but large vibrations and driving sounds are generated causing uncomfortableness
Solution Approach 1:
The patent dynamically switches between rectangular wave driving and sine wave driving based on the motor's rotational state. During starting, rectangular wave driving is used for reliable torque generation. Once the motor reaches a stable rotational state (detected when the rotor rotates by a predetermined angle), the system transitions to sine wave driving to eliminate noise and vibrations. This dynamic adaptation resolves the contradiction between starting reliability and noise reduction.
Solution Approach 2:
The patent implements periodic switching between two driving modes: rectangular wave driving for starting and sine wave driving for steady operation. The switching is triggered by periodic detection of rotor position changes. This periodic action allows the system to enjoy the benefits of both driving methods at appropriate times, achieving both reliable starting and noise reduction during operation.
2Reliability
If the duration of rectangular wave driving is extended to ensure stable starting, then starting reliability is improved, but the duration of noise generation is increased
Solution Approach 1:
The patent uses feedback from rotor position detection to determine when to switch from rectangular wave driving to sine wave driving. The detection device monitors the rotor's rotational position, and when a predetermined angle is reached (indicating stable rotation), the control circuit switches to sine wave driving. This feedback mechanism ensures that rectangular wave driving is used only for the minimum necessary duration to achieve stable starting, thereby minimizing noise duration while maintaining starting reliability.
3Object-affected harmful factors
If conventional methods such as enhancing motor rigidity or providing vibration-absorbing components are used, then vibration and noise are reduced, but the mass and cost of the motor driving controller increase
Solution Approach 1:
The patent replaces mechanical vibration reduction methods (such as rubber mounts or rigidening structures) with an electrical control solution. By switching the driving waveform from rectangular to sine wave based on rotor position feedback, the system achieves vibration and noise reduction through electrical means rather than mechanical modifications. This substitution maintains the original mass and cost of the controller while effectively reducing unwanted vibrations and noises.
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 attenuates the uncomfortableness of starting noises by shortening the duration of rectangular wave driving, thereby reducing noise levels and duration, without increasing the mass or cost of the motor driving controller.
Implementation Method 1
a rotary position detection device generating a position detection signal corresponding to a rotary position of a rotor
Implementation Method 2
a motor driver outputting a driving signal to a stator coil of the motor based on the driving control signal
Data Source
AI summary
A motor driving controller, comprising a rotary position detection device generating a position detection signal corresponding to a rotary position of a rotor of a motor; a control circuit selecting a first driving control signal for performing rectangular wave driving or a second driving control signal for performing driving with an overlapped energization period longer than an overlapped energization period in the rectangular wave driving, based on the position detection signal, thereby to output a driving control signal; and a motor driver outputting a driving signal to a stator coil of the motor based on the driving control signal, wherein the control circuit outputs the first driving control signal at time of starting, and the control circuit outputs the second driving control signal when a rotary state is detected on the basis of the position detection signal.