Parallel Starter Generator Subsystems Low Voltage Torque
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Solution Overview
Problem
Starter/generator systems face challenges in delivering high starting torque with low input voltage, particularly in aircraft applications, where high current requirements complicate electrical distribution and safety, and there is a need for a fault-tolerant system that can operate efficiently in both engine starting and generator modes.
Innovation Solution
The system employs multiple starter/generator subsystems connected in parallel to a voltage distribution bus, each equipped with a starter/generator unit and a power conversion unit that includes an inverter and converter section, allowing for voltage upconversion during engine starting and downconversion during generator operation, enabling high torque production even with low input voltage and supporting fault-tolerant architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the input voltage to the starter/generator is increased to produce high starting torque, then the torque output is improved, but the electrical distribution system complexity and safety risks increase due to high current requirements
Solution Approach 1:
The system divides the single high-power starter/generator into multiple parallel starter/generator subsystems. Each subsystem operates at lower voltage and current levels, simplifying the electrical distribution system while collectively delivering the required high starting torque through parallel operation.
2Force
If multiple batteries are connected in series to provide higher input voltage for high torque, then the torque output is improved, but the system complexity increases due to different voltage configurations for starting and generating modes
Solution Approach 1:
The power conversion unit dynamically adjusts voltage levels based on operating mode. During engine starting, it upconverts low battery voltage to high voltage for the starter/generator. During generating mode, it downconverts the generated voltage to match battery charging requirements, eliminating the need for fixed high-voltage configurations.
Solution Approach 2:
The same low-voltage battery power source serves dual purposes: directly powering the starter/generator through upconversion during starting mode, and receiving charged power during generating mode. This universal low-voltage architecture simplifies the distribution system compared to dedicated high-voltage and low-voltage systems.
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 simplifies the electrical distribution system design by allowing high torque production with low input voltage, reduces the complexity of configuring power sources for different operating modes, and ensures reliable operation in both engine starting and generator modes, while maintaining aircraft safety standards.
Implementation Method 1
each PCU includes an inverter section for rectifying voltage generated by the SGU when the apparatus is operated in the generator mode
Implementation Method 2
the converter section is configured to upconvert the voltage of the input power supply to a voltage suitable to support engine starting when the apparatus is operated in the engine start mode
Data Source
AI summary
An apparatus includes a plurality of starter/generator subsystems connected in parallel to a voltage distribution bus and to an input power supply. Each of the subsystems includes a starter/generator unit (SGU) for providing torque for starting an engine when the apparatus is operated in an engine start mode, and for generating power when the apparatus is operated in a generator mode. In an embodiment, each subsystem includes a power conversion unit (PCU) connected to the respective SGU, and each PCU includes an inverter section for rectifying voltage generated by the SGU when the apparatus is operated in the generator mode and may provide AC excitation voltage to operate the SGU as a motor to support the engine start mode.