Sensorless Motor Position Detection Using Clarke Flux Linkage
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Solution Overview
Problem
Existing suspension systems in vehicles rely on hydraulic or pneumatic shock absorbers, which are costly and require position sensors for accurate operation, while sensorless control methods are lacking for electromagnetic shock absorbers.
Innovation Solution
A sensorless control method for electromagnetic shock absorbers using a permanent-magnet synchronous motor, where a controller determines the position of the translator relative to the stator without a position sensor by calculating flux linkage in Clarke coordinates and compensating for measurement offsets, enabling efficient regenerative shock absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder is used to detect the position of the rotor, then position detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the position detection function from the mechanical encoder and implements it through electrical measurements of phase currents and voltages. The microcontroller calculates rotor position based on electrical signals rather than mechanical sensing elements, thereby eliminating the encoder component while maintaining position detection capability.
Solution Approach 2:
The patent replaces the mechanical encoder system with an electrical measurement and calculation system. Instead of using mechanical sensors to detect rotor position, the system uses electrical measurements of phase currents and voltages combined with computational algorithms to determine position, substituting mechanical detection with electrical and computational methods.
2Measurement precision
If an encoder is used to detect the position of the rotor, then position detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the encoder component from the motor system, eliminating its associated manufacturing costs. The position detection functionality is extracted and implemented through software algorithms that process electrical measurements, thereby reducing bill of materials costs and simplifying the manufacturing process.
Solution Approach 2:
The patent uses readily available, low-cost microcontrollers and standard current/voltage sensors to implement position detection, replacing expensive precision encoders. The solution leverages inexpensive computational resources to achieve functionality that would otherwise require costly mechanical sensing components.
3Device complexity
If sensorless control is implemented, then device complexity is reduced, but position detection accuracy deteriorates at low speeds
Solution Approach 1:
The patent implements dynamic adaptation of the position detection algorithm based on motor operating conditions. The microcontroller adjusts calculation parameters and methods according to speed and load conditions, optimizing detection accuracy across different operating ranges while maintaining the simplicity of sensorless control.
Solution Approach 2:
The patent changes the parameters and methods used in position calculation based on operating conditions. Different calculation algorithms or parameter sets are applied depending on speed, current, and voltage levels, allowing accurate position detection across the full operating range without requiring additional hardware sensors.
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 method simplifies the design, reduces costs, and provides reliable position sensing across a wide frequency range, allowing for efficient energy recovery and accurate control without filters, while also offering a check on the functionality of any present position sensors.
Implementation Method 1
a three-phase electric motor includes a stator and a rotor. The stator has three-phase windings in which phase currents flow in response to application of three-phase voltages having a phase difference of 120 degrees thereamong.
Implementation Method 2
a microcontroller calculates back electromotive forces (back-EMFs) on the basis of the phase currents measured by the current sensor and the three-phase voltages applied to the three-phase windings
Data Source
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Figure 3~4
AI summary
An apparatus includes an electric motor including a stator and a translator; a three-phase inverter electrically coupled to the electric motor; a power source electrically coupled to the three- phase inverter; and a controller communicatively coupled to the three-phase inverter. The controller is programmed to determine at least three measurements at different times of flux linkage from the electric motor, represent the measurements in Clarke coordinates, determine Clarke coordinates of a center of a circle defined by the Clarke coordinates of the measurements, and determine a position of the translator relative to the stator based on the Clarke coordinates of the center of the circle.