Multi-Phase PM Rotor Angle Estimation for Coil Parameter Imbalance
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Solution Overview
Problem
Existing multi-phase permanent magnet rotor motors face inefficiencies due to variations in coil parameters such as resistance and inductance, leading to imbalances and losses in motor operation, as the assumption of identical coils is often flawed.
Innovation Solution
A method is introduced to estimate rotor angle and flux magnitude by measuring and estimating resistance and inductance for each phase coil using pulse width modulated voltage waveforms, allowing for accurate parameter determination in various coil configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the assumption that all phase coils are identical is used to simplify control, then device complexity is reduced, but manufacturing precision deteriorates due to coil parameter variations
Solution Approach 1:
The patent applies parameter changes by transitioning from assuming fixed identical coil parameters to dynamically estimating and adapting to actual varying resistance and inductance values of each phase coil through measurement and calculation, thereby resolving the contradiction between control simplicity and manufacturing precision
Solution Approach 2:
The patent implements feedback by measuring phase coil currents, calculating actual resistance and inductance values, and using these measured parameters to adjust control strategies, creating a closed-loop system that compensates for manufacturing variations without significantly increasing control complexity
2Manufacturing precision
If individual coil parameter measurement and estimation is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the motor control system to automatically measure and estimate its own coil parameters through existing current measurements and calculations, without requiring external measurement equipment or complex additional sensors, thus improving manufacturing precision while minimizing the increase in device complexity
Solution Approach 2:
The patent implements universality by using the existing current measurement infrastructure for multiple purposes: both for standard motor control and for estimating coil resistance and inductance parameters, thereby improving manufacturing precision without proportionally increasing device complexity
3Device complexity
If coil parameter variations are not accounted for, then device complexity remains low, but loss of energy increases due to operating inefficiencies
Solution Approach 1:
The patent applies partial action by implementing parameter estimation only when necessary for optimizing efficiency, rather than continuously monitoring all parameters at all times, thus reducing energy losses due to coil variations while keeping the control system relatively simple through selective activation of the estimation function
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
This approach enhances motor efficiency by accounting for individual coil variations, improving rotor angle estimation and flux magnitude accuracy, thereby optimizing motor performance.
Implementation Method 1
The controller is configured to apply a stepped direct current pulse wave modulated (PWM) voltage waveform with a predetermined duty ratio simultaneously to all of the three of the phase coils
Implementation Method 2
If a permanent magnet or electromagnet is present in this rotating magnetic field, the magnet is magnetically locked with the rotating magnetic field and consequently rotates at the same speed as the rotating field which results in a synchronous motor
Implementation Method 3
The stator carries windings which are connected to a controller having a power stage including a voltage supply, typically an alternating current (AC) voltage supply, to produce the rotating magnetic field
Data Source
AI summary
A method of rotor angle estimation for a multi-phase permanent magnet rotor motor having a plurality of phase coils. The method comprises applying a voltage to one or more of the phase coils and measuring respective phase coil currents. The method includes obtaining measured or estimated values of resistance and inductance for each phase coil from the measured phase coil currents and estimating rotor angle θ based on the measured or estimated values of resistance and inductance for each phase coil.