Three-Phase Induction Motor Parameter Characterization via Constant Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling three-phase induction motors lack precision due to insufficiently accurate data sheet information, necessitating a more reliable method to determine equivalent circuit parameters for efficient control.
Innovation Solution
A method and system that apply a constant current to the stator winding of a three-phase induction motor, varying the voltage to maintain a constant current, and determining equivalent circuit parameters based on the applied voltages and time until a constant voltage is reached, allowing for rapid characterization of motor parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data sheet information is used for motor control, then the control process is simple, but the precision and accuracy of electromagnetic properties are insufficient
Solution Approach 1:
The patent applies preliminary action by performing motor characterization measurements before the motor is installed or used. The equivalent circuit parameters are determined in advance through controlled voltage application and current measurement, so that accurate electromagnetic properties are available for control without requiring complex real-time measurements during operation.
Solution Approach 2:
The motor control system performs self-characterization by automatically applying voltages, measuring currents, and calculating equivalent circuit parameters without external intervention. The system uses its own control hardware to inject test signals and its own sensors to measure responses, enabling autonomous parameter determination.
2Measurement precision
If motor characteristics are measured by signal injection and response monitoring, then parameter accuracy improves, but measurement time increases causing downtime
Solution Approach 1:
The patent applies partial action by measuring only the specific equivalent circuit parameters needed for control (stator resistance, rotor resistance, leakage inductances, magnetizing inductance) rather than performing comprehensive motor testing. The voltage is applied in controlled steps just sufficient to obtain the required parameters without excessive measurement duration.
Solution Approach 2:
The patent changes parameters by applying voltage in controlled steps and varying the frequency or amplitude of injected signals to optimize measurement speed and accuracy. The equivalent circuit parameters are extracted by analyzing current responses at different voltage levels, enabling rapid characterization.
3Measurement precision
If comprehensive motor testing is performed to obtain accurate parameters, then control precision improves, but device complexity and measurement procedures increase
Solution Approach 1:
The patent applies universality by using the existing motor control hardware (inverter, current sensors, controller) for dual purposes: both normal motor control and parameter measurement. The same voltage sources and current measurement circuits used during operation are utilized for characterization, eliminating the need for separate dedicated measurement equipment.
Solution Approach 2:
The control system performs self-characterization by automatically applying voltages, measuring currents, and calculating equivalent circuit parameters without external intervention. The system uses its own control hardware to inject test signals and its own sensors to measure responses, enabling autonomous parameter determination.
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
Enables accurate and rapid determination of equivalent circuit parameters, minimizing downtime during motor replacements and maintaining parameter accuracy over time, even when precise data is not available from data sheets.
Implementation Method 1
the three-phase induction motor 10 comprises a stator winding and a rotor winding
Implementation Method 2
it is necessary for the controller 90 to take into account the electromagnetic properties of the three-phase induction motor 10
Data Source
AI summary
A method (400) of determining equivalent circuit parameters of a three phase induction motor is provided. The method (400) comprises applying (410) a current to a stator winding (362) of an induction motor (360), and varying (420) a voltage applied to the stator winding to regulate the applied current to be a constant current. Application of the current is terminated (430) when the applied voltage has reached a constant voltage. The equivalent circuit parameters are determined (440) from the value of the constant current, the values of the applied voltage, and a time period until the applied voltage attains the constant voltage. The method may provide values for a resistance (210) of the stator winding, a resistance (250) of a rotor winding (364), a magnetizing inductance (230), and a total inductance leakage value (220, 240) for the stator winding and the rotor winding.