Electric Motor Rotor Initial Position Angle Measurement Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring the initial position angle of a rotor in electric machines are inaccurate and difficult to implement in practical field conditions, requiring specific rotational speeds and measurement durations, which affects the performance and reliability of vector control in electric machines.
Innovation Solution
A method that calculates the initial position angle deviation using the trigonometric function relation between the voltages of the d-axis and q-axis of the stator, allowing for quick and accurate measurement without requiring specific rotational speeds or long measurement durations, and can be easily implemented in the field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measuring method is used to obtain initial position angle by measuring back electromotive force, then measurement can be performed, but the method requires specific devices (oscilloscope or voltage sensor) and has low feasibility for practical field operation
Solution Approach 1:
The system uses its own operational data (voltages and currents) to determine the initial position angle, eliminating the need for external measurement devices. The controller itself performs the measurement function by processing electrical signals already present in the drive system.
Solution Approach 2:
The patent replaces physical measurement devices (oscilloscope, voltage sensor) with an electrical calculation method based on voltage and current relationships, substituting mechanical/electrical measurement instrumentation with computational analysis.
2Measurement precision
If indirect measuring method is used to rotate the electric machine to the position coinciding with A phase axis, then initial position can be obtained, but the method has high requirements on measurement conditions and load magnitude greatly affects measurement precision
Solution Approach 1:
The patent changes the measurement parameters from mechanical position alignment to electrical voltage-current relationships. By using the trigonometric relationship between voltages and currents during motor operation, the system determines initial position without requiring specific mechanical positioning or load conditions.
Solution Approach 2:
The method uses partial operational data (voltages and currents during normal operation) rather than requiring complete system shutdown or specific operational states, allowing measurement to be performed under broader operating conditions.
3Measurement precision
If existing measurement methods are used, then initial position angle can be measured, but the measurement is inaccurate and requires specific rotational speeds and measurement durations which affects system performance
Solution Approach 1:
The system determines the initial position angle before normal operation begins, using the voltage and current relationships present at startup. This preliminary determination eliminates the need for ongoing measurements during operation, improving system performance without sacrificing accuracy.
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 method provides high-speed, accurate, and reliable measurement of the initial position angle, improving system performance, reliability, and safety by enabling online fault diagnosis and error correction without additional hardware costs or complex modifications.
Implementation Method 1
calculating to obtain an initial position angle deviation of the rotor of the electric machine according to a trigonometric function relation between the voltage of the d-axis and the voltage of the q-axis
Data Source
AI summary
The present disclosure discloses a method for measuring an initial position angle of a rotor of an electric machine, which solves the technical problem in the prior art that the requirement on the measurement conditions of the initial position angle of the rotor of the electric machine is high and the actual operation is not easy. The method comprises: Step 1, supplying an electric current i to an electric machine to be measured to cause the electric machine to run; Step 2, when the electric machine is running, reducing the electric current i to be zero; Step 3, measuring voltages of a d-axis and a q-axis of a stator of the electric machine at the moment, respectively as ud and uq; and Step 4, according to a trigonometric function relation between ud and uq, calculating to obtain an initial position angle deviation θerr of the rotor of the electric machine.