Electric Motor Controller Primary Flux Feedback
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Solution Overview
Problem
Conventional primary magnetic flux control techniques struggle to maintain stable and efficient operation, especially in rotary electric motors with saliency, as they fail to accurately control the primary magnetic flux when the load angle is large, leading to deviations in torque and phase differences.
Innovation Solution
An electric motor controller that employs a feedback mechanism based on the deviation of the primary magnetic flux, using a combination of feedforward and feedback terms to adjust voltage command values, allowing for precise control of the primary magnetic flux regardless of saliency, and includes a primary magnetic flux estimation unit to correct deviations in the load angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional primary magnetic flux control is used, then the control system is simple, but the motor cannot maintain stable operation when load angle is large or saliency is present
Solution Approach 1:
The patent introduces a feedback mechanism that calculates the actual primary magnetic flux from measured voltages and currents, compares it with the commanded flux, and uses the deviation to correct the voltage commands. This feedback loop enables the system to maintain accurate primary magnetic flux control even when load angle is large or saliency is present, resolving the contradiction between reliability and complexity.
2Power
If the primary magnetic flux command value is increased to improve torque, then the torque output increases, but the load angle deviation and control instability increase
Solution Approach 1:
The feedback mechanism continuously monitors the actual primary magnetic flux and compares it with the command value. When torque increases cause load angle deviations, the feedback calculates the flux deviation and generates corrective voltage commands that automatically adjust the control to maintain stability, allowing high torque output without sacrificing load angle stability.
Solution Approach 2:
The patent replaces direct mechanical angle sensing and control with an electrical field-based approach. By using voltage and current measurements to calculate the primary magnetic flux and using this electrical field information for control, the system achieves more accurate and stable load angle control compared to conventional mechanical or direct electrical angle control methods.
3Measurement precision
If the control ignores saliency to simplify the control algorithm, then the control is easier to implement, but the primary magnetic flux control accuracy deteriorates
Solution Approach 1:
The feedback mechanism measures the actual primary magnetic flux by calculating it from measured voltages and currents using the relationship between voltage, current, and magnetic flux in the motor. This measurement-based feedback approach automatically compensates for saliency effects without requiring the control algorithm to explicitly model or ignore them, achieving high accuracy while keeping the control logic relatively simple.
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 solution enables stable and high-efficient operation of rotary electric motors, even at high torque levels, by accurately controlling the primary magnetic flux and correcting load angle deviations, thus improving the motor's performance and reliability.
Implementation Method 1
a first calculation unit (102) that obtains a first term ([F]) as a sum of an inductive voltage (ω* • [Λ1*]) by a primary magnetic flux command value ([Λ1*])
Data Source
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AI summary
In a primary magnetic flux control, performed is a feedback based on a deviation of a primary magnetic flux. An electric motor controller (1) includes a first coordinate conversion unit (101) that converts a three-phase current ([I]) into a current ([i]) in a δc-γc rotating coordinate system, a first calculation unit (102) that obtains a feedforward term ([F]), a second calculation unit (103A) that obtains a voltage command value ([v*]) in the δc-γc rotating coordinate system as a sum of the feedforward term ([F]) and a feedback term ([B]), a second coordinate conversion unit (104) that coordinate-converts the voltage command value ([v*]) into a voltage command value ([V*]) of a voltage to be applied to a rotary electric motor (3) in another coordinate system, and an integrator (106) that calculates a phase (θ) of a δc axis with respect to an α axis on the basis of a command value (ω*) of a rotation angular velocity.