Variable speed transmission with auxiliary driver and system using same
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Solution Overview
Problem
Existing systems require complex and costly variable frequency drivers to modulate the rotational speed of variable-speed loads driven by constant-speed drivers, such as electric motors, which are inefficient and cumbersome for large industrial applications like compressors.
Innovation Solution
A system utilizing an auxiliary turbomachine, such as a turboexpander or steam turbine, mechanically coupled to a speed summing gear arrangement, allowing the main driver to operate at a constant speed while modulating the load's rotational speed by controlling the auxiliary driver, thereby eliminating the need for a variable frequency driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a variable frequency driver is used to modulate the rotational speed of the load, then the rotational speed can be controlled, but the system becomes complex and costly
Solution Approach 1:
The system divides the speed control function into two independent parts: the main driver operates at constant speed while the auxiliary driver provides variable speed contribution. This segmentation eliminates the need for a complex variable frequency driver on the main driver, reducing overall system complexity while maintaining speed control capability.
Solution Approach 2:
An auxiliary driver is introduced as an intermediary component between the power source and the load. This auxiliary driver handles the variable speed modulation function, allowing the main driver to operate simply at constant speed, thereby reducing the complexity of the overall speed control system.
2Ease of operation
If a variable frequency driver is used to modulate the rotational speed of the load, then the rotational speed can be controlled, but the cost increases
Solution Approach 1:
By segmenting the speed control function between a constant-speed main driver and a variable-speed auxiliary driver, the system avoids the high cost of equipping the main driver with an expensive variable frequency driver, thereby reducing overall system cost while maintaining speed control capability.
Solution Approach 2:
The auxiliary driver serves as a cost-effective solution for variable speed control, replacing the need for expensive variable frequency driver equipment on the main driver, thus reducing the overall manufacturing cost of the system.
3Ease of operation
If the main driver operates at variable speed, then the load speed can be modulated, but power conversion losses increase
Solution Approach 1:
The system segments the speed modulation function from the main power conversion system. The main driver operates at constant speed with efficient direct power conversion, while the auxiliary driver handles variable speed contributions, thereby minimizing power conversion losses in the main power 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
This configuration reduces the complexity and cost of speed modulation, enhances efficiency by leveraging waste heat, and minimizes power conversion losses, making it more economical and efficient for driving large compressors and other rotating loads.
Implementation Method 1
The variable speed transmission comprises a speed summing gear arrangement having a first input shaft, a second input shaft and an output shaft
Implementation Method 2
Waste heat, for instance from a gas turbine engine or other low temperature heat source, is usefully exploited to drive the auxiliary driver
Data Source
Figure 1~2
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AI summary
The system (1) comprises: a main driver (3) configured for rotating at a substantially constant rotational speed; a rotating load (5) configured to be driven into rotation by the main driver (3); a controller (12), for contrallably adjusting a load rotational speed; a variable speed transmission (11), arranged between the main driver (3) and the load (5) and comprised of a speed summing gear arrangement (21) having a first input shaft (23), a second input shaft (25) and an output shaft (27); an auxiliary driver (43; 143), mechanically coupled to the second input shaft (25) of the speed summing gear arrangement (21). The first input shaft (23) of the speed summing gear arrangement (21) is drivingly coupled to the main driver (3). The output shaft (27) of the speed summing gear arrangement (21) is drivingly coupled to the rotating load (5). The speed of the output shaft (27) is a combination of a speed of the main driver (3) and of a speed of the auxiliary driver (43; 143).