Variable Frequency Power Distribution Bus for Ship Propulsion
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Solution Overview
Problem
Conventional power distribution systems for ships require separate prime movers and expensive variable frequency drives to supply power to both main propulsion and auxiliary loads, leading to inefficiencies and increased costs due to the need for single frequency and voltage power distribution busses.
Innovation Solution
A power distribution system with a variable speed prime mover generating A/C output at frequencies corresponding to its speed, using a power switch and variable frequency drive to disconnect and reconnect the motor from the bus, allowing for efficient speed control of variable speed motors and simultaneous power supply to auxiliary loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate prime movers and variable frequency drives are used for main propulsion and auxiliary loads, then reliable power supply is achieved, but system complexity and cost increase
Solution Approach 1:
The patent merges the power supply for both main propulsion motors and auxiliary loads into a single common AC power distribution bus, eliminating the need for separate prime movers and power distribution systems. The variable speed prime mover directly generates variable frequency AC power that simultaneously serves both propulsion and auxiliary loads, reducing system complexity while maintaining reliability through unified power management.
Solution Approach 2:
The common AC power bus serves multiple functions simultaneously: it provides power to main propulsion motors with variable frequency requirements and supplies auxiliary loads with standard frequency requirements. The system achieves multi-functionality by using a single prime mover and power distribution infrastructure to serve diverse power needs across the vessel.
2Ease of operation
If variable frequency drives are used to control motor speed, then speed control precision is improved, but energy consumption and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for expensive variable frequency drive equipment by directly connecting the variable speed prime mover to the common AC power bus. The prime mover itself generates the variable frequency AC power needed, removing the intermediary VFD equipment that consumes additional energy and increases system cost.
Solution Approach 2:
The variable speed prime mover serves itself by generating the variable frequency AC power it needs to operate, while simultaneously providing power to auxiliary loads. The system achieves self-service by using the prime mover's own variable speed capability to generate appropriate frequencies directly, eliminating the need for external frequency conversion equipment.
3Ease of manufacture
If a common power bus is used for both propulsion and auxiliary loads, then system cost is reduced, but power distribution complexity increases
Solution Approach 1:
The patent segments power distribution control by using separate controllable connections: one path for propulsion motors that requires variable frequency control and another path for auxiliary loads that uses standard frequency distribution. This segmentation allows the common bus to serve multiple purposes while maintaining simple, dedicated control paths for each load type.
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 system eliminates the need for transformers and variable frequency drives, reducing costs and improving energy efficiency by enabling direct power distribution to variable speed motors and auxiliary loads through a common power bus.
Implementation Method 1
a variable speed prime mover adapted to generate an A/C output having a variable frequency corresponding to the speed of the prime mover
Implementation Method 2
a power switch adapted to disconnect the variable speed motor from the bus when the speed of the prime mover is equal to or within a predetermined range of the predetermined speed limit
Implementation Method 3
a variable frequency drive operatively connected to the A/C output of the prime mover via the power distribution bus and operatively configured to provide an alternate A/C output to the motor after the variable speed motor is disconnected from the power distribution bus
Data Source
AI summary
A system and method for supplying power to a variable speed motor for rotating a shaft may include generating an A/C output having a variable frequency corresponding to speed of a prime mover, where the speed of the prime mover is equal to or greater than a predetermined speed limit. The A/C output of the prime mover may be distributed to the variable speed motor such that the speed of the variable speed motor is varied relative to the frequency of the A/C output. The variable speed motor may be electrically disconnected from the A/C power when the speed of the prime mover being used to drive the variable speed motor is equal to or within a predetermined range of the predetermined speed limit. An alternate A/C output may be distributed to the variable speed motor after the A/C power is electrically disconnected from the variable speed motor.