Motor Controller for Current-Stable Magnet Flux Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating the temperature of a magnet in electric motors require changing the current, leading to a drop in motor efficiency due to increased temperature, as they necessitate altering current instruction values to estimate magnetic flux.
Innovation Solution
A motor controller and method that detect and stabilize the current, allowing for magnetic flux calculation using voltage equations in a rotating coordinate system without altering the current instruction, thereby estimating magnetic flux and temperature without efficiency loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current instruction value is changed to estimate magnetic flux, then measurement precision of magnetic flux is improved, but motor efficiency deteriorates due to temperature rise
Solution Approach 1:
The patent introduces an observer as an intermediary system that estimates magnetic flux indirectly through mathematical models and sensor measurements, rather than directly through current changes. The observer uses the voltage equation in rotating coordinate system to calculate magnetic flux from measured voltages and currents, acting as a mediator between the motor system and the control system.
Solution Approach 2:
The patent replaces the mechanical/current-based method of magnetic flux estimation with a mathematical/electrical approach. Instead of physically changing current to measure magnetic flux characteristics, the system uses voltage equations and coordinate transformations to calculate magnetic flux from electrical measurements, substituting a mathematical model for a physical measurement method.
2Measurement precision
If current is changed to determine current response characteristics, then temperature estimation accuracy is improved, but motor efficiency deteriorates
Solution Approach 1:
The observer serves as an intermediary that estimates temperature indirectly through magnetic flux calculation, eliminating the need for direct current changes. The system uses the relationship between voltage, current, and magnetic flux in the voltage equation to derive temperature information without physically altering the operating current.
Solution Approach 2:
The patent enables continuous temperature and magnetic flux estimation during normal motor operation without interrupting or altering the current flow. The observer continuously calculates magnetic flux and temperature based on real-time voltage and current measurements, maintaining continuous useful action rather than requiring periodic current changes for measurement.
3Measurement precision
If current stability is ensured for magnetic flux calculation, then measurement precision is improved, but response speed may deteriorate
Solution Approach 1:
The patent implements a dynamic estimation approach where the observer continuously updates magnetic flux and temperature estimates based on real-time voltage and current measurements. The system adapts to changing operating conditions dynamically, adjusting the estimation calculations as the motor operates under varying loads and speeds, rather than requiring static or stable conditions for measurement.
Data Source
AI summary
Provided is a motor controller that can estimate the magnetic flux of a magnet without changing a current of an electric motor. A motor controller 1 includes a current detecting unit 15 that detects a current of an electric motor 5, a current stability determining unit 10 that determines whether or not a current detected by the current detecting unit 15 is stable, and a magnetic flux calculating unit (filters 8a to 8e, a current conversion unit 4b, a resistance calculating unit 9, a magnet magnetic flux estimating unit 11) that based on a determination made by the current stability determining unit 10 as to current stability, calculates the magnetic flux of a magnet of the electric motor 5, according to a voltage equation in a rotating coordinate system, to output the calculated magnet flux. The motor controller 1 further includes a control voltage output unit (a map 2, voltage instruction units 3a and 3b, a first three-phase conversion unit 4a) that outputs a control voltage to the electric motor 5, based on the magnetic flux of the magnet calculated by the magnetic flux calculating unit and on a torque instruction value.