Rotor Sensor Offset Estimation for Motor Torque Accuracy
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Solution Overview
Problem
Existing electric motor systems face inaccuracies in torque generation due to sensor offset misalignment between the rotor and stator, leading to incorrect energization of stator windings and subsequent torque production.
Innovation Solution
A motor control system that includes a rotor position estimation module capable of estimating sensor offset using motor current, voltage, and parameter signals, generating an adjustment signal to correct the desired torque signal, and utilizing a power inverter to provide AC power to the stator windings for precise rotor rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor offset is not compensated, then the system structure remains simple, but torque generation accuracy deteriorates
Solution Approach 1:
The system performs offset estimation and compensation in advance during motor operation. The rotor position estimation module continuously estimates the offset between rotor and stator positions and generates compensation signals before torque generation errors occur, ensuring accurate torque generation without requiring complex mechanical alignment procedures
Solution Approach 2:
The patent replaces mechanical alignment and calibration procedures with an electronic estimation and compensation system. Instead of physically aligning sensors during assembly, the system uses electrical signals to estimate offset and generate compensation signals, simplifying the mechanical structure while improving measurement precision
2Measurement precision
If Hall-effect sensors are used on the rotor, then rotor position can be detected, but sensor offset misalignment occurs between rotor and stator
Solution Approach 1:
The system uses feedback from the Hall-effect sensors to continuously monitor rotor position and detect offset misalignment. The rotor position estimation module processes sensor signals and generates feedback compensation signals that correct for alignment errors, maintaining accurate position detection despite manufacturing tolerances
Solution Approach 2:
The system changes the operational parameters of the Hall-effect sensors by applying compensation signals that adjust the sensed position data. The rotor position estimation module modifies the sensor output parameters to account for offset misalignment, effectively correcting manufacturing precision errors through parameter adjustment
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 system effectively compensates for sensor offset by adjusting torque signals, ensuring accurate torque generation and rotor positioning, thereby improving motor efficiency and performance.
Implementation Method 1
the power inverter converts the DC voltage to a corresponding alternating current (AC) voltage and provides the AC voltage to the motor and the rotor position estimation module
Implementation Method 2
The rotor typically includes one or more position sensors, such as Hall-effect sensors, disposed about the rotor. The position sense a position of the rotor with respect to the stator
Implementation Method 3
Electric motors include a stator having stator windings and a rotor that rotates based on current flowing within the stator windings
Data Source
AI summary
In an example, a system is disclosed. The system includes a rotor position estimation module configured to generate an adjustment signal to adjust a desired torque signal for a motor. The rotor position estimation module includes a sensor offset estimation module configured to estimate an offset position of a sensor based on (1) a motor current signal indicative of a current to rotate a rotor within the motor, (2) a motor voltage signal indicative of a voltage applied to a power inverter that provides the current to the motor, and (3) a motor parameter. The sensor can be disposed on the rotor. The rotor position estimation module also includes a speed adjustment module configured to generate the adjustment signal based on the estimated offset position.