Sensorless Electric Machine Rotor Circuit Design
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Solution Overview
Problem
Current electric machine technologies face challenges in achieving full torque control without position sensors, leading to reduced performance and reliability due to loss of small signal saliency at high-load levels.
Innovation Solution
A rotor circuit structure comprising conductive, non-magnetic materials is introduced, aligning with the d-axis of the electric machine, allowing for sensorless operation by measuring high-frequency carrier voltage responses and maintaining small signal saliency across loading levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors (encoder, tachometer, or resolver) are used with electric machines, then torque control capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the position sensor (encoder, tachometer, or resolver) from the motor drive system, extracting the sensing function and replacing it with sensorless control methodology that uses existing machine components and electrical measurements to determine rotor position and speed without additional hardware
Solution Approach 2:
The patent makes the existing motor drive electronics perform multiple functions: they not only control motor operation but also sense rotor position and speed through electrical measurements (current, voltage, frequency) without requiring dedicated position sensing hardware, thereby reducing overall system complexity
2Measurement precision
If position sensors are used with electric machines, then torque control capability is improved, but reliability deteriorates
Solution Approach 1:
The patent removes the position sensor (encoder, tachometer, or resolver) from the motor drive system, extracting the sensing function and replacing it with sensorless control methodology that uses existing machine components and electrical measurements to determine rotor position and speed without additional hardware
Solution Approach 2:
The patent enables the motor drive system to sense its own state ( rotor position and speed) through electrical measurements of current, voltage, and frequency that are already present during motor operation, eliminating the need for separate position sensing hardware and improving reliability
3Measurement precision
If high frequency injection method is used for zero frequency encoderless control, then position sensing capability is improved, but torque capability deteriorates due to loss of small signal saliency at high-load levels
Solution Approach 1:
The patent changes the operating parameters and control methodology by using fundamental frequency current injection instead of high frequency injection, and by dynamically adapting the control strategy based on load conditions to maintain both position sensing accuracy and full torque capability across the entire operating range
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 full torque control and improved reliability by maintaining small signal saliency without the need for position sensors, enhancing efficiency and performance across various load conditions.
Implementation Method 1
measuring high-frequency carrier voltage responses
Data Source
AI summary
A rotor component that comprises a rotor circuit configured for use with either an interior permanent magnet (IPM) machine or a synchronous reluctance machine (SRM) that includes a pole circuit made of a conductive, non-magnetic material and has a midpoint that substantially aligns with a d-axis of the IPM or SRM. An electric machine with a similar rotor component therein or having a loop or ring of a conductive, non-magnetic material that is substantially concentric about a d-axis of the electric machine.