Brushless DC Wiper Motor Dynamic Commutation Control
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Solution Overview
Problem
Brushless DC motors used in wiper devices face challenges in varying torque efficiently, leading to increased motor current and heat generation, which can result in overheating and damage when dealing with high load conditions such as snow accumulation, making it difficult to control rotation speed and torque effectively.
Innovation Solution
A wiper device with a controller that adjusts the timing of current switch-on in the coil based on the rotor's rotation position, allowing for appropriate motor current control and load suppression, enabling the rotation speed to be controlled from low to high speeds while maintaining low power consumption and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the voltage applied to the coil is increased to increase the revs of the output shaft, then the rotation speed is improved, but the torque of the output shaft decreases
Solution Approach 1:
The patent applies dynamics by making the current switch-on timing variable based on rotor position rather than fixed. The drive section dynamically adjusts the commutation timing of the coil currents according to the detected rotor position, enabling the motor to maintain optimal torque production across varying speeds. This dynamic timing adjustment resolves the contradiction between speed and torque by adapting the electrical characteristics to the mechanical state.
Solution Approach 2:
The patent changes the parameter of current switch-on timing based on rotor position to optimize both speed and torque performance. By detecting rotor position and adjusting the commutation timing accordingly, the system modifies the electrical parameters (current timing and duration) to maintain efficient operation across different operating conditions, resolving the speed-torque tradeoff.
2Force
If the torque of the output shaft is increased to handle high load conditions, then the load capacity is improved, but the motor current increases causing heat generation and potential overload
Solution Approach 1:
The patent uses dynamic current timing adjustment based on rotor position to improve torque efficiency. By optimizing when current is applied to each coil phase according to the rotor's actual position, the motor generates required torque with minimized current consumption. This reduces heat generation and prevents overload while maintaining the ability to handle high load conditions.
Solution Approach 2:
The patent implements feedback by detecting rotor position and using this information to adjust current switch-on timing. The drive section continuously monitors rotor position and adapts the commutation timing accordingly, creating a closed-loop control system that optimizes current usage for torque production, thereby reducing unnecessary current draw and heat generation under high load conditions.
3Speed
If the current switch-on timing is adjusted to control rotation speed, then the speed control is improved, but the torque fluctuation increases
Solution Approach 1:
The patent changes the current switch-on timing parameter based on detected rotor position to achieve smooth speed control. By synchronizing the commutation timing with the rotor's actual position rather than using fixed timing, the system maintains consistent torque production across the rotation cycle, eliminating torque ripple while enabling effective speed control through PWM and timing adjustment.
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 controls the wiper motor's rotation speed and torque, reducing power consumption and preventing overheating, thus preventing motor overload and damage, even under high torque conditions like snow-clearing operations.
Implementation Method 1
a wiper motor that includes a rotor and a coil to generate a rotating magnetic field, and that causes a wiper blade to perform a wiping operation by rotating the rotor according to the rotating magnetic field
Data Source
AI summary
A wiper device including a wiper motor that includes a rotor and a coil to generate a rotating magnetic field, and that causes a wiper blade to perform a wiping operation by rotating the rotor according to the rotating magnetic field, a drive section that drives rotation of the wiper motor by performing current switch-on in the coil so as to generate the rotating magnetic field, and a controller that controls the drive section by a timing for current switch-on in the coil based on at least a rotation position of the rotor.