Brushless DC Motor Sinusoidal Control via Hall Sensor Estimation
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Solution Overview
Problem
Brushless direct current electric motors used in gear motors for motor vehicle wiping systems face challenges in achieving high torque and high speed while minimizing noise and cost, particularly due to complex control requirements and the need for accurate encoders.
Innovation Solution
A brushless direct current electric motor design incorporating a rotor with a control magnet, a stator with electromagnetic excitation coils, and at least one Hall effect sensor, along with a control unit that estimates the angular position of the rotor and generates sinusoidal control signals, allowing for cost-effective sinusoidal control without a costly encoder, and switches between blockwise and sinusoidal control based on rotation speed and torque thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If sinusoidal control is used to reduce noise and improve torque, then noise level decreases and torque increases, but an accurate encoder is required which increases cost
Solution Approach 1:
The patent uses a simplified angular position estimation that copies the essential functionality of an encoder by calculating rotor position from Hall effect sensor signals and current measurements, avoiding the need for expensive accurate encoders while enabling sinusoidal control
Solution Approach 2:
The patent replaces the mechanical encoder system with an electronic estimation system using Hall effect sensors and computational methods to determine angular position, thereby reducing cost while maintaining sinusoidal control capability
2Device complexity
If blockwise control is used to simplify control, then cost decreases, but torque and speed performance are limited
Solution Approach 1:
The patent dynamically adapts the control method based on operating conditions, using blockwise control at low speeds and sinusoidal control at high speeds, thereby optimizing torque performance across the entire operating range while managing complexity
Solution Approach 2:
The patent changes the control parameter approach by switching between blockwise and sinusoidal control strategies based on rotation speed thresholds, allowing high torque at low speeds and optimized performance at high speeds without maintaining complex sinusoidal control throughout
3Measurement precision
If accurate angular position measurement is implemented to enable sinusoidal control, then torque constant increases and noise reduces, but device cost increases due to encoder requirements
Solution Approach 1:
The patent creates a virtual angular position measurement system that copies the functionality of physical encoders by estimating rotor position from Hall effect sensor data and current measurements, achieving accurate position information without expensive hardware
Solution Approach 2:
The patent introduces computational algorithms as an intermediary between the Hall effect sensors and the control system, transforming limited sensor data into accurate angular position information needed for sinusoidal control
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
Enables high torque and high speed operation with reduced noise and cost, effectively controlling the motor for wiping systems without the need for expensive encoders, improving operational efficiency and passenger comfort.
Implementation Method 1
at least one Hall effect sensor configured to detect an angular position of the control magnet
Implementation Method 2
a stator having electromagnetic excitation coils of the rotor
Data Source
AI summary
A brushless direct current electric motor for a wiping system. The brushless direct current electric motor includes a rotor, a stator, a Hall effect sensor to detect control magnet angular position of the rotor, and a control unit to determine rotor angular positions in relation to the stator from the signals Hall effect sensor signals and to generate control signals to electromagnetic excitation coils of the rotor as a function of the determined angular position of the rotor. The control unit includes a clock configured to: estimate the angular position of the rotor at predetermined instants lying between two changes of state of the Hall effect sensor, determine values of the control voltages associated with the angular positions of the rotor estimated for the predetermined instants, and generate a substantially sinusoidal control signal from the determined voltage values.