Compressor Drive Device Low Speed Pickup Sensor Control
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Solution Overview
Problem
Existing multi-shaft gas turbine systems face challenges in efficiently turning the low pressure side shaft during compressor operation, especially when the rotation speed is low, as conventional rotation speed detection methods like electromagnetic speed pickups are ineffective at speeds below 100 rpm, leading to inadequate motor control.
Innovation Solution
A compressor driving device is introduced, featuring a motor and control section that generates a turning rotation speed and provides assist torque when the gas turbine's output is insufficient, utilizing a low speed pickup sensor and high speed pickup to detect rotation speeds independently for the high and low pressure side shafts, allowing independent rotation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic speed pickup is used for rotation speed detection, then detection is effective at normal operation speeds, but detection becomes ineffective at low speeds below 100 rpm
Solution Approach 1:
The patent applies parameter changes by switching between two different detection methods based on rotation speed: using an electromagnetic speed pickup for normal operation speeds and a low-speed pickup for turning speeds below 100 rpm. This allows the system to adapt its detection parameters to match the operational regime, ensuring accurate measurement across the full speed range.
2Reliability
If low pressure side shaft is not turned during stop condition, then thermal deformation is suppressed, but inadequate motor control occurs at low rotation speeds
Solution Approach 1:
The patent introduces a low-speed pickup as an intermediary detection device that enables reliable motor control during the turning operation at low speeds. This intermediary component bridges the gap between the motor control system and the low-speed rotational movement, allowing precise control while maintaining the shaft in a turned position to prevent thermal deformation.
3Power
If helper motor provides assist torque when turbine output is insufficient, then compressor driving capability is improved, but system complexity increases
Solution Approach 1:
The patent applies universality by designing the motor to perform multiple functions: it acts as a turning motor during stop conditions to rotate the low pressure side shaft, and as a helper motor during operation to provide assist torque when turbine output is insufficient. This multi-functional design avoids the need for separate dedicated devices for each function, thereby limiting the increase in system complexity.
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 effective turning of the compressor driven by a multi-shaft gas turbine, even at low rotation speeds, by providing accurate rotation speed detection and control, thereby addressing the limitations of existing systems in maintaining desired driving conditions.
Implementation Method 1
a low speed pickup sensor (28) that detects a rotation speed of the low pressure side shaft (12) during the turning and outputs a detection signal for turning indicating the detected rotation speed, wherein the low speed pickup (28) generates the detection signal for turning in time series by detecting a periodic variation of a distance between a head of the low speed pickup (28) and a periodic convex and concave pattern formed on the rotation speed detection member
Implementation Method 2
a high speed pickup that detects a rotation speed of the low pressure side shaft and outputs the detected rotation speed as a helper motor rotation speed signal, wherein the high speed pickup includes a coil and generates the helper motor rotation speed detection signal based on a periodic variation of a current flowing the coil generated by a moving of a periodic convex and concave pattern of a rotation speed detection member
Data Source
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AI summary
It is desired to obtain a technique which enables turning of a compressor driven by a multi-shaft gas turbine. The multi-shaft gas turbine has a high-pressure side shaft and a low-pressure side shaft. A compressor drive device applies a drive force to a compressor connected to the low-pressure side shaft of the multi-shaft gas turbine. The compressor drive device includes: a motor which generates a drive force; and a control unit which controls the motor so as to generate an rpm when turning the compressor. If the torque generated by the gas turbine is insufficient, the control unit controls the motor so as to carry out a helper motor operation for increasing the torque.