Motor Control Device Floating Image Signal Rotor Position
Solution Overview
Problem
Conventional methods for determining the position of a rotor in electronically controlled motors, such as BLDC motors, face challenges including increased costs and complexity due to the use of sensors or low signal/noise ratios when measuring counter-electromotive force, particularly at low motor speeds.
Innovation Solution
A motor control device that includes a transformation module to generate a floating image signal representative of the counter-electromotive force, with a time constant determined by motor and control module characteristics, allowing continuous signal acquisition without amplitude deterioration and improved signal/noise ratio, enabling accurate rotor position deduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect sensors are used to detect rotor position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the rotor position information from the counter-electromotive force signal itself, eliminating the need for external sensors. The transformation module processes the existing voltage signal to generate an image signal that contains the position information, thereby removing the sensors from the system while maintaining measurement capability.
Solution Approach 2:
The transformation module creates a floating image signal that is representative of the counter-electromotive force. This image signal is a transformed copy of the original voltage signal that makes the rotor position information more accessible and easier to process, especially at low speeds.
2Measurement precision
If counter-electromotive force signal is measured at disconnected terminals, then measurement precision is improved, but reliability deteriorates at low speeds due to low signal amplitude
Solution Approach 1:
The transformation module changes the parameters of the measured signal by applying a transformation with a specific time constant. This transformation modifies the signal characteristics to produce an image signal with improved amplitude and signal-to-noise ratio, making it reliable for position detection even at low motor speeds where the original counter-electromotive force signal would be too weak.
3Device complexity
If actual counter-electromotive force signal is used directly, then device complexity is reduced, but measurement precision deteriorates due to low signal/noise ratio
Solution Approach 1:
The transformation module acts as an intermediary between the raw voltage signal and the position detection process. It transforms the original signal into a floating image signal that preserves the essential position information while improving the signal-to-noise ratio and amplitude, thereby enhancing measurement precision without significantly increasing system complexity.
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 provides a continuous and reliable floating image signal with improved signal/noise ratio, allowing accurate rotor position determination even at low speeds without significant calculation power, and ensures stable motor operation by eliminating parasitic frequencies.
Implementation Method 1
a transformation module enabling to transform a source signal taken off at least at one of the terminals of the winding into a floating image signal representative of a counter-electromotive force induced in the winding
Data Source
AI summary
A device for controlling a motor having a stator and a rotor, the stator being provided with at least one winding, the motor being controlled by a control module, the control device including: at least one transformation module for transforming a source signal taken from at least one of the terminals of the winding into a floating image signal representative of a counter-electromotive force induced in the winding. The transformation module has: a time constant determined from characteristics of the motor and/or characteristics of the control module; at least one first terminal connected to at least one of the terminals of the winding, and a second terminal, the first and second terminals being likely to have floating potential relative to the fixed reference terminal.