EC Motor Commutation Using Dual Magnetic Sensor Switching
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Solution Overview
Problem
Existing electronically commutated electric motors require complex and costly electronics to achieve efficient motor start and nominal operation, which increases the overall cost and complexity.
Innovation Solution
A compact and cost-efficient design using a single stator coil with two static magnetic field sensors and a switch unit with an analog operation mode control element, allowing for efficient motor start and nominal operation without the need for complex electronics or microcontrollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If complex electronics are used to determine motor working point and provide optimal trigger point, then motor control efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the control function by using two separate magnetic field sensors positioned at different circumferential positions to detect different aspects of the rotor magnetic field. This segmentation allows the system to determine both the working point and optimal trigger point through simple signal comparison rather than complex electronics, resolving the contradiction between control efficiency and device complexity
Solution Approach 2:
The magnetic field sensors and switch unit constitute a self-service system that automatically determines the motor working point and provides the optimal trigger point without external complex control electronics. The system uses the inherent magnetic field information detected by the sensors to self-regulate the commutation timing, eliminating the need for costly microcontrollers or complex evaluation units
2Measurement precision
If multiple magnetic field sensors are used to detect rotor position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The switch unit acts as an intermediary that receives signals from two magnetic field sensors and processes them to generate the optimal trigger signal. Instead of using complex evaluation electronics to process multiple sensor signals, the switch unit simply compares the sensor outputs and generates commutation signals, achieving precise rotor position detection while maintaining simple device architecture
Solution Approach 2:
The two magnetic field sensors serve multiple functions: they detect the rotor magnetic field strength, determine the working point (starting or nominal operation), and provide timing information for optimal commutation. This multi-functionality allows the sensor system to achieve high measurement precision without increasing device complexity, as the same sensors perform multiple detection tasks
3Productivity
If trigger signal phase is adjusted for optimal motor start, then motor starting efficiency is improved, but control system complexity increases
Solution Approach 1:
The switch unit is pre-configured with the logic to determine the optimal trigger point based on the motor working point before commutation occurs. By preliminarily analyzing the sensor signals and determining the appropriate trigger phase, the system ensures efficient motor starting without requiring complex real-time control electronics during the actual commutation process
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 enables reliable and efficient motor start and operation by using two magnetic field sensors with different signal phases to generate trigger signals for the switch unit, reducing the need for additional electronics and achieving efficient motor control.
Implementation Method 1
the motor is provided with at least one magnetic field sensor detecting the revolving magnetic rotor excitation field
Implementation Method 2
analyzing the counter-electromotive force (CEMF) generated in the stator coil by the revolving magnetic rotor excitation field
Data Source
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AI summary
An electronically commutated electric motor (10) comprising a stator (12) with at least one stator coil (42), a permanent magnet rotor (14) rota table relative to the stator (14) about an axis of rotation (A) thereby generating an revolving excitation field, a static starting-operation magnetic field sensor (16) and a static nominal-operation magnetic field sensor (18) both being arranged spaced to each other, the magnetic field sensors (16, 18) locally detecting the revolving excitation field and generating corresponding trigger signals (TSO,TNO), a motor control unit (20) energizing the stator coll (42) for driving the motor rotor (14), the motor control unit (20) being triggered by a trigger signal (TSO,TNO) provided by one of the magnetic field sensors (16,18) to generate a revolving stator field, and a switch unit (22) with an analog operation mode control element (44,44'), the switch unit (22) being electrically connected with the two magnetic field sensors (16,18) and with the motor control unit (20), wherein the switch unit (22) provides either the trigger signal (TSO) of the starting-operation magnetic field sensor (16) or the trigger signal (TNO) of the nominal-operation magnetic field sensor (18) to the motor control unit (20), and wherein the switching state (SSO,SNO) of the switch unit (22) is controlled by the analog operation mode control element (44,44').