Sensorless Motor Commutation via Current-Based Rotor Position Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronically commutated electric motors, such as brushless DC motors, face inefficiencies due to angular errors between estimated and actual rotor positions, especially when sensorless commutation is employed, leading to suboptimal torque production and reduced efficiency.
Innovation Solution
A method that trims and adjusts the estimated rotor position using a dither signal to minimize angular errors, determining correction values based on changes in total current, allowing for precise approximation of the actual rotor position through repeated iterations, thereby optimizing commutation without the need for position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless commutation is used to eliminate position sensors, then device complexity is reduced, but measurement precision of rotor position deteriorates due to angular errors between estimated and actual positions
Solution Approach 1:
The patent implements a feedback mechanism where the total current is continuously monitored and used to generate correction values that adjust the estimated rotor position. The current information flows back to the control unit, which modifies the commutation angles based on actual current conditions, thereby compensating for angular errors without adding physical sensors.
Solution Approach 2:
The patent replaces the mechanical/physical sensor-based measurement system with an electronic substitution method. Instead of using Hall sensors or other position detectors that physically measure rotor position, the system uses electrical current measurements and mathematical models to estimate and correct the rotor position, substituting a mechanical measurement approach with an electrical/electronic one.
2Use of energy by moving object
If angular errors are reduced to improve commutation precision, then motor efficiency is improved, but device complexity increases due to additional correction mechanisms
Solution Approach 1:
The system performs self-correction by using its own operational parameters (total current) to identify and correct angular errors. The control unit automatically adjusts the estimated rotor position based on current measurements, enabling the motor to self-optimize its commutation without external intervention or additional complex control systems.
Solution Approach 2:
The existing current sensors, originally intended only for current measurement, are dual-used to also determine angular errors and generate position corrections. This multi-functionality allows the same hardware to serve both protection/control functions and precision commutation optimization, avoiding additional dedicated sensors or measurement devices.
3Measurement precision
If total current is used to determine angular errors, then measurement precision is improved, but use of energy increases due to additional current measurements
Solution Approach 1:
The patent merges the function of current measurement with the function of position detection. The total current measurement, already necessary for motor control and protection, is combined with the rotor position estimation function. By analyzing current harmonics and patterns, the system extracts position information from the same electrical measurements used for basic motor operation, eliminating the need for separate high-power measurement systems.
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 reducing angular errors, enabling higher torque production with the same current magnitude and compensating for any error causes, leading to improved commutation quality and reduced energy consumption.
Implementation Method 1
the rotor position is deduced from a counter-voltage which is generated by the rotor in the stator winding
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The present invention relates to a method for operating an electronically commutated electric motor (1), wherein a sensorless electronic commutation is carried out on the basis of a provided estimated value (︢φ) of an angular position of a rotor (2) of the electronically commutated electric motor (1), said method comprising the steps: trimming the estimated value (︢φ) by applying a superimposed variable (φ d ) to the estimated value (︢φ) so that the sensorless electronic commutation is carried out on the basis of a trimmed estimated value (︢φ + φ d ); determining a change in an electric sum current (I sum ) flowing through a coil of a stator of the electronically commutated electric motor (1) during operation of the electronically commutated electric motor (1) with the commutation on the basis of the trimmed estimated value (︢φ + φ d ); determining a correction value (φ k ) of the estimated value (︢φ) on the basis of the change in current; adjusting the estimated value (︢φ) using the correction value (φ k ).