Rotary Machine Rotor Position Detection via Magnetic Saturation
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Solution Overview
Problem
Existing rotor position detection methods for rotary machines, such as those using magnetic saturation, require manual adjustment and are prone to inaccurate evaluations of magnetic saturation, leading to potential excessive current flow and reduced detection accuracy.
Innovation Solution
A control device that calculates an adjustment evaluation value based on the ratio of voltage amplitude to current values, allowing for automatic adjustment of voltage vector application time to ensure proper magnetic saturation and accurate rotor position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual adjustment method is used to ensure magnetic saturation, then magnetic saturation can be achieved, but adjustment complexity and manual labor increase
Solution Approach 1:
The system automatically evaluates magnetic saturation status and adjusts voltage vector application time without manual intervention. The control device monitors current values, calculates adjustment evaluation values, and self-adjusts parameters to maintain proper magnetic saturation, eliminating the need for manual adjustment while ensuring reliable saturation achievement.
Solution Approach 2:
The control device continuously monitors current values during voltage vector application, calculates adjustment evaluation values based on these measurements, and uses this feedback to automatically adjust the application time. This closed-loop feedback mechanism ensures magnetic saturation is achieved and maintained without manual intervention.
2Reliability
If voltage vector application time is extended to ensure magnetic saturation, then magnetic saturation is achieved, but excessive current flow occurs
Solution Approach 1:
The control device dynamically adjusts the voltage vector application time based on real-time current measurements and calculated adjustment evaluation values. Rather than using a fixed extended time, the system optimizes the application duration continuously, ensuring magnetic saturation is achieved with the minimum necessary time, thereby preventing excessive current flow.
Solution Approach 2:
The system changes the voltage vector application time parameter dynamically based on the adjustment evaluation value calculated from current measurements. This parameter adjustment ensures that the application time is optimized for each operating condition, achieving magnetic saturation while avoiding excessive current that would occur with fixed extended timing.
3Measurement precision
If position sensor is attached to obtain rotor position information, then detection accuracy is improved, but cost and space increase
Solution Approach 1:
The control device replaces mechanical position sensors with an electronic estimation system that calculates rotor position based on current measurements and voltage vector application. This substitution eliminates the need for physical sensors, reducing cost and space while maintaining detection accuracy through mathematical estimation based on magnetic saturation characteristics.
Solution Approach 2:
The system uses current measurements and adjustment evaluation values as intermediaries to indirectly determine rotor position. Instead of directly measuring position with a sensor, the control device uses electrical parameters (current values during voltage vector application) as intermediaries to estimate the rotor position, achieving accurate detection without physical sensors.
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 stable and accurate rotor position detection by properly evaluating magnetic saturation and setting the minimum necessary application time, reducing manual labor and preventing excessive current flow.
Implementation Method 1
a method using magnetic saturation of the rotary machine as shown in Patent Document 3 is known. In this method, 2n (n is a phase number and is a natural number equal to or greater than 3) voltage vectors having the same amplitude and having phases separated at equal intervals are applied to a rotary machine, and then a rotor position is detected from a summed current value obtained by summing detected values of currents flowing when a pair of such voltage vectors having phases different by 180° from each other are applied.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A storage section (5) stores, as stored current values, currents flowing when a voltage application section (3) applies voltage vectors to a three-phase rotary machine (1). A position estimation section (6) estimates the rotor position of the rotary machine (1) in a stopped state based on the stored current values. An adjustment section (7) adjusts a minimum necessary application time Ta that allows the rotary machine (1) to be magnetically saturated by voltage vector application, so as to enable rotor position estimation. Further, the adjustment section (7) uses, as an adjustment evaluation value, the magnitude |Δ Y| of differential admittance obtained by dividing a summed current value calculated from the stored current values by the voltage amplitude value of the voltage vector instruction when the voltage vector based on the voltage vector instruction is applied with the application time being set at an arbitrary application time Tm, and adjusts the application time based on |Δ Y|. Thus, evaluation of the degree of magnetic saturation can be more properly performed, and the minimum necessary application time setting value that allows estimation of the rotor position can be detected and set simply and reliably.