Temperature control of multi-stage cryocooler with load shifting capabilities
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Solution Overview
Problem
Multi-stage cryocoolers lack independent control over each stage's temperature, leading to increased temperature settling time during heat load changes, as existing control inputs like compressor stroke and pressure-volume phase do not adjust heat lift independently.
Innovation Solution
A temperature control system that receives temperature setpoints and information from multiple stages, calculates compressor stroke and pressure-volume phase errors, and adjusts compressor settings and displacement phases independently to regulate each stage's temperature, decoupling control variables and enabling independent heat lift control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control system is used for multi-stage cryocooler, then the device complexity is reduced, but the temperature control precision of each stage deteriorates
Solution Approach 1:
The control system is segmented into multiple independent controllers, each responsible for controlling the temperature of a specific stage. Each controller independently adjusts its stage's temperature by modifying compressor stroke and pressure-volume phase parameters, enabling precise temperature control for each stage without requiring a single complex centralized controller.
2Loss of time
If compressor stroke and pressure-volume phase are adjusted simultaneously, then the temperature settling time is reduced, but the control complexity increases
Solution Approach 1:
The control system dynamically adjusts both compressor stroke and pressure-volume phase parameters simultaneously based on real-time temperature feedback from each stage. This dynamic coordinated adjustment allows the system to rapidly respond to temperature deviations and reduce settling time, while the decentralized controller structure manages the control complexity by handling parameter coordination locally at each stage.
Solution Approach 2:
The system changes multiple operational parameters (compressor stroke and pressure-volume phase) simultaneously to achieve rapid temperature adjustment. By coordinating changes in both parameters together rather than sequentially, the system reduces the temperature settling time while managing control complexity through integrated parameter adjustment strategies in each decentralized controller.
Data Source
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AI summary
A system includes a multi-stage cryocooler (100, 210) having multiple stages and a temperature control system (205) configured to regulate temperatures of the multiple stages of the multi-stage cryocooler. The temperature control system includes an input interface configured to receive (i) temperature setpoints (335-340) for the stages of the multi-stage cryocooler and (ii) temperature information corresponding to temperatures measured at the stages of the multi-stage cryocooler. The temperature control system also includes processing circuitry (345, 350, 305) configured to determine temperature errors and calculate at least one of a compressor stroke error and a pressure-volume phase error. The temperature control system further includes at least one controller (325, 330) configured to adjust at least one of a compressor setting and a pressure-volume phase of the multi- stage cryocooler.