Motor Inductance Calibration for Accurate PMSM Current Control
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Solution Overview
Problem
Current HVAC systems inaccurately model motor inductance values, leading to inefficient motor operation due to incorrect current control and overestimated power requirements.
Innovation Solution
A system that calibrates the inductance model of interior permanent magnet synchronous motors (PMSMs) by updating inductance values based on operating currents, providing more accurate motor parameter determination and improved current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant inductance values are used for motor modeling, then the model is simple to implement, but the motor parameters become inaccurate leading to inefficient operation
Solution Approach 1:
The patent applies the dynamics principle by transitioning from static constant inductance values to dynamic inductance values that vary with operating conditions. The inductance values are continuously updated based on real-time current measurements and lookup tables, allowing the motor model to adapt to changing operating states while maintaining computational efficiency through pre-calibrated data structures.
Solution Approach 2:
The patent implements parameter changes by modifying the inductance values (Ld and Lq) based on operating current levels. Lookup tables store pre-calculated inductance values corresponding to different current magnitudes, and the system selects appropriate values based on real-time current measurements, thereby adjusting model parameters to match actual motor behavior at different operating points.
2Loss of energy
If inaccurate inductance values are used, then the system requires less computational resources, but the current control becomes inaccurate reducing motor efficiency
Solution Approach 1:
The patent applies feedback by continuously monitoring actual motor current and using this information to select appropriate inductance values from lookup tables. The system measures phase currents, determines their magnitudes, and uses these measurements to index into pre-calibrated lookup tables, thereby feedback-driven adjustment of model parameters improves current control accuracy and motor efficiency without excessive computational burden.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing inductance values in lookup tables before runtime. During motor operation, the system only needs to perform simple table lookups based on current measurements rather than calculating inductance values in real-time, which reduces computational resources while maintaining high accuracy. The computationally intensive calibration work is performed beforehand.
3Reliability
If inductance values are updated based on operating current, then the motor parameters become more accurate, but the system complexity increases
Solution Approach 1:
The patent applies copying by creating lookup tables that contain pre-stored copies of inductance values for various operating conditions. Instead of performing complex real-time calculations, the system copies appropriate values from these pre-prepared tables based on current measurements. This approach maintains high reliability through accurate parameter selection while minimizing system complexity by replacing complex computations with simple data retrieval operations.
Data Source
AI summary
A system for calibrating inductance at a motor comprises the motor, a motor drive circuit, and a processor operably coupled to the motor. The processor determines inductance map data that comprises a set of inductance values associated with a set of current values. The processor determines that the motor is in operation. In response, the processor determines current values with which the motor is being operated. The processor determines inductance values associated with the determined current values. The processor determines reference current values at the motor based on the determined inductance values. The processor also determines a speed, angle, flux, and torque associated with the motor based at least on the determined inductance values. The processor then controls the operation of the motor based on the determined reference currents, the speed, and the torque.