Rotary Machine Control Device for Sensorless Position Estimation
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Solution Overview
Problem
Existing rotary machine control devices face complexity in estimating rotor position, especially when the current flow direction is not aligned with the rotor position, leading to inaccurate position estimation and increased complexity in control design and processing.
Innovation Solution
A rotary machine control device that includes a current detector, a speed estimator to compute rotational speed from motional electromotive force, and a position computing unit to estimate rotor position, allowing for voltage instruction-based operation without relying on position sensors, thereby simplifying the configuration and enabling position estimation irrespective of current flow direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high frequency voltage is applied to estimate rotor position, then accurate rotor position estimation is achieved even at zero or low velocity, but torque pulsation or noise is caused and maximum torque or rotational speed is reduced
Solution Approach 1:
The patent extracts the rotor position estimation function from the main drive voltage by applying a separate high frequency voltage specifically for position detection. This separates the position measurement function from the torque production function, allowing accurate position estimation without the harmful effects of superimposing high frequency voltage on the drive voltage.
Solution Approach 2:
The patent introduces an intermediary high frequency voltage signal that serves as a probe for position detection without directly affecting the main drive operation. This intermediary signal allows position measurement while minimizing interference with the primary torque production function.
2Measurement precision
If position sensor is provided to obtain rotor position information, then accurate rotor position detection is achieved, but manufacturing cost and size of rotary machine increase
Solution Approach 1:
The patent enables the rotary machine to self-detect its rotor position using electrical measurements from the existing windings and circuitry. The system uses the machine's own electrical characteristics (current, voltage, inductance) to determine position, eliminating the need for external position sensors and reducing complexity.
Solution Approach 2:
The patent replaces mechanical position sensing systems with an electrical field-based detection method. By using electrical measurements and signal processing to determine rotor position, the system eliminates mechanical sensors and their associated complexity while maintaining detection accuracy.
3Object-generated harmful factors
If active flux or extended electromotive force is used to estimate rotor position without high frequency voltage, then torque pulsation is avoided, but rotor position estimation fails when rotary machine current has no d-axis or q-axis component
Solution Approach 1:
The patent segments the position detection function into separate phases: first obtaining flux linkage information, then deriving active flux components, and finally determining rotor position. This segmented approach allows the system to handle different current conditions by processing flux information through multiple stages, ensuring reliable position estimation regardless of current flow direction.
Solution Approach 2:
The patent performs preliminary calculation of flux linkage before deriving active flux components. By first obtaining the total flux linkage and then extracting the active flux portions, the system prepares the necessary information in advance to handle various current conditions, ensuring position estimation reliability even when d-axis or q-axis current components are zero.
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
The solution allows for accurate and responsive rotor position estimation regardless of current flow direction, reducing complexity and improving control processing, while maintaining high responsivity and stability in rotary machine operation.
Implementation Method 1
compute an estimated rotational speed that is an estimated value of a rotational speed of the rotor, on a basis of motional electromotive force that is induced voltage generated due to a change in the inductance with a position of the rotor
Data Source
AI summary
A rotary machine control device for controlling a rotary machine whose inductance has an inductance variable component that changes with a rotor position includes a current detector detecting rotary machine current flowing through the rotary machine; and a speed estimator computing estimated rotational speed that is an estimated value of rotational speed of a rotor, based on motional electromotive force that is induced voltage generated due to change in the inductance with a rotor position. The rotary machine control device includes a position computing unit computing an estimated position that is an estimated value of the rotor position, using the estimated rotational speed; and a controller outputting a rotary machine voltage instruction to drive the rotary machine, based on the rotary machine current and the estimated position. The rotary machine control device includes a voltage applicator applying voltage to the rotary machine based on the rotary machine voltage instruction.