Inductive Rotary Sensor for Compact Motor Control
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Solution Overview
Problem
Existing motor control systems that rely on resolvers for accurate rotor angular position and velocity measurements are costly and physically large, making them inefficient for compact and cost-effective applications.
Innovation Solution
An inductive rotary sensor system comprising a first inductive coil affixed to the rotor shaft and a second inductive coil with a multi-phase winding, coupled with an evaluation circuit to determine rotor shaft angle and velocity, allowing for commutation and feedback control of electric motors without the need for physical connections and providing position and velocity feedback for precise motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resolver with resolver to digital converter is used for accurate rotor position and velocity measurement, then measurement precision is improved, but device complexity and physical size increase
Solution Approach 1:
The patent replaces the mechanical resolver system with an inductive sensor system using coils and magnetic fields. Instead of using a resolver with physical windings and mechanical coupling, the invention uses stationary coils that generate magnetic fields to detect rotor position and velocity through electromagnetic induction, eliminating the need for resolver to digital converters and reducing mechanical complexity
Solution Approach 2:
The patent creates a simplified electromagnetic model that copies the essential measurement function of resolvers. By using inductive coils to generate magnetic fields and detect changes through electromagnetic induction, the system replicates the position and velocity sensing capability of resolvers but with simpler, more compact components that don't require complex conversion circuits
2Measurement precision
If a resolver system is used for motor control, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent employs inexpensive inductive sensor coils and magnetic field generation components instead of costly resolver systems. The stationary coils and simple evaluation circuitry provide the necessary measurement precision at a fraction of the cost of resolver-based systems, making the solution economically viable for mass production
Solution Approach 2:
By replacing the expensive mechanical resolver system with an electromagnetic inductive sensing system, the patent eliminates the need for costly resolver to digital converters and complex mechanical assemblies, significantly reducing manufacturing costs while maintaining measurement accuracy
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 inductive rotary sensor system enables accurate and efficient motor control by determining rotor shaft angle and velocity, allowing for precise commutation and feedback control, reducing size and cost while maintaining high performance, and can be used with various types of electric motors.
Implementation Method 1
Power for exciting the first inductive coil is magnetically induced so that electrical connections to the first inductive coil are not needed
Implementation Method 2
the evaluation circuit is operative to determine the rotor shaft angle for the rotor shaft of the electric motor through measuring voltages in the second inductive coil created by position of the first inductive coil which creates a magnetic field between the first and second inductive coils
Data Source
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AI summary
A sensor system for providing control of an electric motor having an inductive angle sensor system (10) including a first inductive coil (12) configured for affixation to a rotor shaft of the electric motor wherein rotation of the rotor shaft causes corresponding rotation of the first inductive coil. A second inductive coil ((24), (26)) fixedly mounted in spaced relationship to the first inductive coil. An evaluation circuit (50) coupled to the second inductive coil and to the electric motor operative to determine a rotor shaft angle for the rotor shaft of the electric motor through evaluation of an induced magnetic field between the first and second inductive coils.