Compressor Field Weakening Control Delay for Voltage-Based Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Permanent magnet synchronous compressors easily enter a field weakening control area during high-speed operation, leading to reduced efficiency and system instability due to increases in Id current, which affects position estimation and overall system stability.
Innovation Solution
A device and method that set a rotational speed threshold for the compressor, controlling the output voltage to prevent temporary entry into field weakening control until necessary, thereby delaying the compressor's entry into this control area and improving stability by managing the rotational speed and voltage accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the compressor operates in high-speed area, then the rotational speed increases, but the compressor easily enters field weakening control area causing efficiency reduction and system instability
Solution Approach 1:
The control device performs preliminary action by detecting the rotational speed and proactively adjusting the output voltage before the compressor enters the field weakening control area. When the rotational speed reaches a preset threshold, the control device increases the output voltage in advance, which prevents the Id current from increasing and avoids entry into the field weakening control area, thereby maintaining system stability and efficiency.
2Speed
If the compressor enters field weakening control, then the rotational speed can be maintained, but the efficiency of the whole machine becomes lower
Solution Approach 1:
The control device implements feedback control by continuously detecting the rotational speed of the compressor and adjusting the output voltage based on the detected speed. When the rotational speed reaches the preset threshold, the control device increases the output voltage, which feeds back to prevent the compressor from entering the field weakening control area, thereby maintaining higher whole machine efficiency while still achieving the desired rotational speed.
3Speed
If the Id current increases during field weakening control, then the rotational speed can be controlled, but the position estimation becomes inaccurate and system stability deteriorates
Solution Approach 1:
The control device applies preliminary anti-action by increasing the output voltage before the Id current has a chance to increase significantly. By detecting when the rotational speed reaches the preset threshold, the control device proactively adjusts the voltage to counteract the tendency toward field weakening control, thereby preventing position estimation errors and maintaining system stability before they can occur.
Data Source
AI summary
Devices are provided for field weakening control of a compressor, including the compressor and a main circuit unit providing power for the compressor. The devices include a compressor rotational speed obtaining unit, and a control unit that compares the rotational speed ω of the compressor with a rotational speed threshold ω1 of the compressor, and controls the main circuit unit according to comparison results. When the rotational speed ω is less than ω1, an output voltage of the main circuit unit is controlled at a fixed value. When the rotational speed ω is greater than or equal to ω1, the compressor is controlled not to enter the field weakening control temporarily and the output voltage of the main circuit unit is controlled to rise, the compressor is controlled to enter the field weakening control when the output voltage of the main circuit unit cannot continue to rise.