Composite Wedge Q-Axis Damper Circuit for High-Speed Rotors
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Solution Overview
Problem
Conventional synchronous machines lack effective Q-axis damping, especially at high speeds, due to the use of non-conductive materials like Inconel or titanium for wedges, which are inadequate for strength and conductivity, and braze joints that are not strong enough for high-speed applications.
Innovation Solution
A rotor design with wedges composed of a high-strength first material (like titanium or Inconel) and a high-conductivity second material (like copper or beryllium copper) for Q-axis damping, where the second material forms a damper bar extending through the wedge, and end plates electrically connected to complete a Q-axis winding circuit, providing full 360° damping with D-axis damper bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-conductive materials like Inconel or titanium are used for wedges, then mechanical strength is sufficient for high-speed applications, but electrical conductivity is poor and Q-axis damping is ineffective
Solution Approach 1:
The wedge is constructed as a composite structure with a non-conductive body (Inconel or titanium) for mechanical strength and embedded conductive elements (copper or beryllium copper bars) for electrical conductivity. This composite approach allows the wedge to simultaneously provide structural support and Q-axis damping functionality.
Solution Approach 2:
The wedge has non-uniform material distribution: the body is made of strong non-conductive material while specific regions contain embedded conductive bars. This local differentiation allows different parts of the wedge to serve different functions - structural integrity from the body and electrical conductivity from the embedded bars.
2Reliability
If electrically conductive materials like aluminum or copper are used for wedges, then Q-axis damping is improved, but mechanical strength is insufficient for high-speed applications
Solution Approach 1:
Instead of using purely conductive material, the invention combines conductive material (copper or beryllium copper bars) with non-conductive strong material (Inconel or titanium body) to create a composite wedge that achieves both electrical conductivity for damping and mechanical strength for high-speed operation.
3Reliability
If braze joints are used to connect conductive wedge materials, then electrical conductivity is achieved, but joint strength is not sufficient for high-speed applications
Solution Approach 1:
The invention replaces the mechanical braze joint connection system with an embedded system where conductive bars are enclosed within the wedge body. This eliminates the weak braze joints while maintaining electrical conductivity through the embedded conductive path.
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 achieves superior Q-axis damping with enhanced mechanical strength and electrical conductivity, improving transient performance and efficiency in high-speed electrical machines, particularly in high voltage DC and variable speed constant frequency systems.
Implementation Method 1
at least one second member made of a second material, the second material having a higher electrical conductivity than the first material
Implementation Method 2
A respective wedge secures the windings in each gap configured to supply Q-axis damping
Data Source
AI summary
A rotor for an electrical machine includes a rotor core having a plurality of circumferentially spaced apart rotor poles. A plurality of windings are seated in gaps between circumferentially adjacent pairs of the rotor poles. A respective wedge secures the windings in each gap configured to supply Q-axis damping. A pair of end plates are connected electrically to the wedges at opposing longitudinal ends thereof thereby completing a Q-axis winding circuit for each wedge.