Mechanical Constant Speed Unit for Wind Turbine Grid Compatibility
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Solution Overview
Problem
Existing wind power systems require complex and costly apparatuses, such as power inverters, to stabilize varying rotation speeds for grid-tie compatibility, which increases hardware costs and control complexity.
Innovation Solution
A power generating device incorporating a constant speed unit comprising two differential gear sets, a continuously variable transmission (CVT) mechanism, and a hydraulic torque converter or hydraulic static transmission device, allowing for adjustable output rotation speed to maintain a constant generator speed without the need for a power inverter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power inverters are used to convert varying rotation speeds into constant frequencies for grid-tie compatibility, then grid compatibility is improved, but hardware costs and control complexity increase
Solution Approach 1:
The patent replaces the electrical power inverter system with a mechanical constant speed unit comprising differential gear sets and a continuously variable transmission mechanism. This mechanical substitution directly converts varying rotor rotation speeds into constant generator rotation speeds through gear differential mechanisms, eliminating the need for complex electrical frequency conversion and reducing both hardware costs and control complexity while maintaining grid compatibility
Solution Approach 2:
The patent introduces a constant speed unit as an intermediary mechanical device between the variable speed rotor and the generator. This intermediary mechanism, consisting of differential gear sets and CVT, mediates the speed conversion process mechanically, avoiding the need for complex electrical power electronic conversion and simplifying the overall system while ensuring constant frequency output for grid connection
2Stability of the object's composition
If hydraulic torque converters are used to control torque and rotation speed, then rotation speed stability is improved, but sensitivity to temperature variation increases and efficiency at low rotation speed decreases
Solution Approach 1:
The patent segments the constant speed control function into two independent transmission paths: one path uses a continuously variable transmission mechanism for primary speed control, while the other path uses differential gear sets for speed stabilization. This segmentation allows the system to achieve rotation speed stability without relying solely on hydraulic torque converters, thereby reducing temperature sensitivity and improving reliability at low rotation speeds
3Speed
If hydraulic static transmission is used to perform speed control, then speed control capability is improved, but efficiency at low rotation speed decreases and nonlinear characteristics increase
Solution Approach 1:
The patent merges a continuously variable transmission mechanism with differential gear sets in a hybrid constant speed unit. The CVT mechanism provides efficient low-speed operation and variable ratio control, while the differential gear sets provide precise speed stabilization. This combination merges the advantages of both mechanisms, achieving excellent speed control capability across the entire operating range while maintaining high efficiency at low rotation speeds and reducing nonlinear characteristics
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
This configuration reduces hardware costs and simplifies control by stabilizing the electric generator's rotation speed, enhancing compatibility with the grid while minimizing the impact of temperature variations and low rotation speed inefficiencies.
Implementation Method 1
the torque and rotation speed are controlled by a hydraulic torque converter
Implementation Method 2
a continuously variable transmission (CVT) mechanism
Implementation Method 3
a first differential gear set comprising two input ends and an output end
Data Source
AI summary
A power generating device capable of outputting at a constant rotation speed is configured with a constant speed unit for transforming a varying input rotation speed into a constant output rotation speed, which comprises: a power source, an electric generator and a constant speed unit; wherein the constant speed unit further comprises: a first differential gear set, having two input ends and an output end being configured in a manner that one of the two input ends is connected with the power source and the output end is connected to a load; a continuously variable transmission (CVT) mechanism, configured with an input end and an output end in a manner that the input end is connected to the power source; a hydraulic torque converter, configured with an input end and an output end in a manner that the input end is connected to the load; a second differential gear set, configured with two input ends and an output end in a manner that the two input ends are connected respectively to the output end of the CVT mechanism and the hydraulic torque converter so as to perform a power composition process in the second differential gear set and then transmit the composite power from its output end to the other input end of the first differential gear set that is not connected to the power source.