Resolver Offset Calibration Using Algebraic Power Calculations
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Solution Overview
Problem
Conventional methods for calibrating the offset of a resolver in motors, especially in mass-produced eco-friendly vehicles, are inadequate due to manufacturing defects that cause the d-axis and q-axis to be non-perpendicular, leading to errors in offset calibration.
Innovation Solution
A method that applies current to the -d-axis of the motor, measures and calculates Vq, Vd, and Id, and adjusts the resolver offset to positive or negative values based on input power calculations, ensuring the power input is within a predetermined range, while maintaining constant rpm, using algebraic calculations to correct for geometrical distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional geometric calibration method is used, then the process is simple, but calibration accuracy deteriorates due to manufacturing defects causing non-perpendicular d-axis and q-axis
Solution Approach 1:
The patent replaces the conventional geometric calibration method with an algebraic calculation method. Instead of relying on geometric relationships that assume perpendicular d-axis and q-axis, the new method uses algebraic equations to calculate the resolver offset based on measured voltage and current values, thereby eliminating the dependency on mechanical perpendicularity assumptions and improving calibration accuracy despite manufacturing defects
Solution Approach 2:
The patent changes the calibration approach from geometric parameters (angles, positions) to electrical parameters (voltage, current measurements). By measuring Vd, Vq, Id, and Iq and using algebraic relationships between these electrical quantities, the method determines the resolver offset without being affected by mechanical manufacturing tolerances that cause axis non-perpendicularity
2Measurement precision
If DYNAMO equipment with torque sensor is used, then offset calibration accuracy is improved, but device availability deteriorates because garages do not have such equipment
Solution Approach 1:
The patent enables the motor control system to perform its own offset calibration using only the components already present in the motor (resolvers, voltage sensors, current sensors). The system uses its own electrical measurements (Vd, Vq, Id, Iq) during normal operation to calculate and correct the offset, eliminating the need for external DYNAMO equipment or torque sensors that are unavailable in typical garage settings
Solution Approach 2:
The patent introduces algebraic calculation as an intermediary method that bridges the gap between electrical measurements and mechanical offset calibration. Instead of directly measuring torque or mechanical position with specialized equipment, the method uses algebraic relationships to derive the offset from readily available electrical quantities, making calibration accessible without specialized equipment
Data Source
AI summary
Provided is a system and method for calibrating an offset of a resolver in a motor of a vehicle. More specifically, a current is applied to the −d-axis of the motor, the Vq, Vd, Iq, and Id of the motor is measured and a power input to the motor is calculated by a controller, and when the input power is not within a predetermined range, the controller adjusts the offset of the resolver to a positive or negative value accordingly.