Variable Speed Generator Synchronization via Inverter Control
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Solution Overview
Problem
Existing engine-driven electrical generators operate at a fixed speed, leading to suboptimal fuel efficiency and noise, and when connected in parallel, synchronization of AC output voltages is challenging, requiring mechanical coupling which increases complexity and cost.
Innovation Solution
A method for controlling a variable speed, constant frequency generator system that includes an inverter with a processor and memory to adjust engine speed based on load, using position signals to synchronize output voltage with other generators, and maintaining frequency and voltage within specified limits by calculating the necessary slip power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates at a fixed predetermined speed, then the generator produces consistent frequency and voltage output, but fuel efficiency decreases and noise increases when the load is less than rated capacity
Solution Approach 1:
The engine speed is made variable rather than fixed, allowing it to adapt dynamically to different load conditions. The controller adjusts engine speed based on actual load requirements, improving fuel efficiency while maintaining reliable frequency and voltage output through coordinated control of the inverter and generator.
Solution Approach 2:
The operating parameters of the engine (speed) are changed dynamically to optimize fuel efficiency. The controller modifies engine speed as a variable parameter in response to load conditions, while compensating mechanisms maintain the electrical output parameters (frequency and voltage) within acceptable ranges.
2Reliability
If multiple generators are mechanically coupled to ensure synchronous voltage supply, then frequency synchronization is achieved, but device complexity and expense increase
Solution Approach 1:
The mechanical coupling system is replaced with an electrical control system. Instead of physically linking generator shafts to enforce synchronization, the patent uses electronic controllers and inverters to independently regulate each generator's output, achieving frequency and phase synchronization through electrical signals rather than mechanical constraints.
Solution Approach 2:
An intermediary control system is introduced between the generators and the load. The controller acts as a mediator that receives feedback from the generators and adjusts their operation to maintain synchronization, eliminating the need for direct mechanical coupling between generator units.
3Use of energy by moving object
If the engine speed is reduced to optimize fuel efficiency, then fuel consumption and noise decrease, but the generated frequency deviates from the predetermined frequency
Solution Approach 1:
A feedback control mechanism is implemented where the controller continuously monitors the actual frequency and phase of the generator output and adjusts engine speed accordingly. This closed-loop control allows the system to operate at optimized speeds for fuel efficiency while automatically correcting frequency deviations to maintain reliable output.
Solution Approach 2:
The inverter serves multiple functions: it converts the variable frequency output from the generator and simultaneously acts as a frequency regulator. This multi-functionality allows the system to benefit from variable speed operation for fuel efficiency while the inverter compensates to deliver stable frequency to the load.
Data Source
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AI summary
A generator system configured to be connected in parallel with other generators is disclosed. The generator system includes an alternator having a stator with an output winding and a quadrature winding and a rotor with a three-phase winding. The rotor of the alternator is rotatably driven by an engine having a controller to regulate the engine speed. An inverter receives power from the quadrature winding and generates an AC voltage for the rotor winding, The inverter receives an input corresponding to the voltage on the output winding of the stator and also receives an input corresponding to the phase angle of a second AC voltage produced by another power source. The inverter controls the frequency of the AC voltage for the rotor winding such that the phase angle of the voltage on the output winding of the stator is synchronized to the phase angle of the second AC voltage.