Variable Speed Generator with Single-Phase Stator
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Solution Overview
Problem
Off-grid generator sets typically operate at fixed engine speeds to maintain constant frequency output, leading to inefficient fuel use and noise when electrical loads are below rated capacity, as they lack the ability to adjust engine speed and maintain constant frequency and voltage.
Innovation Solution
An off-grid power generating apparatus with a single phase stator winding and multiple symmetric phase windings in the rotor, utilizing an excitation control device to regulate the rotating magnetic field and engine speed, allowing for variable engine speed while maintaining constant frequency and voltage output without the need for frequency conversion devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine operates at fixed speed to maintain constant frequency output, then the output electrical power frequency is stable, but fuel efficiency deteriorates and noise increases when electrical load is below rated capacity
Solution Approach 1:
The patent applies dynamics by enabling the engine speed to vary dynamically according to load conditions. The controller adjusts the engine operating speed within a range while maintaining constant frequency output through coordinated control of the alternator and power conversion system, allowing the system to adapt to changing electrical loads without sacrificing frequency stability or fuel efficiency
Solution Approach 2:
The patent changes the operating parameters of the engine-speed relationship. Instead of maintaining a fixed engine speed for constant frequency, the system allows engine speed to change while using power electronic conversion and control to maintain the output frequency at the desired value, thus decoupling the direct relationship between engine speed and output frequency
2Reliability
If the engine operates at fixed speed to maintain constant frequency output, then the output electrical power frequency is stable, but noise increases when electrical load is below rated capacity
Solution Approach 1:
The system dynamically adjusts engine speed based on actual load requirements. When electrical load is below rated capacity, the engine operates at lower speeds reducing noise, while the power conversion system maintains stable frequency output. This dynamic adaptation eliminates the need for continuous high-speed operation that generates unnecessary noise
Solution Approach 2:
The patent converts what would traditionally be a harmful deviation (variable engine speed) into a beneficial feature. By allowing engine speed to vary and using power electronic conversion to maintain frequency stability, the system transforms the potential harm of speed variation into the benefit of reduced noise and improved fuel efficiency while preserving output quality
3Use of energy by moving object
If frequency conversion devices are used to enable variable engine speed, then fuel efficiency improves, but device complexity and cost increase
Solution Approach 1:
The patent makes the power conversion system multi-functional. The same power conversion apparatus that converts electrical power also performs frequency regulation and engine speed control functions. This universal approach allows variable engine speed operation with improved fuel efficiency while avoiding the need for separate, complex frequency conversion devices
Solution Approach 2:
The system uses its own power conversion infrastructure to achieve frequency stability without external frequency conversion devices. The controller leverages the existing power conversion apparatus to regulate output frequency while enabling variable engine speed, making the system self-sufficient and avoiding additional complexity
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 solution enables efficient operation across varying loads by optimizing engine speed, reducing noise and fuel consumption, and allowing for direct voltage delivery to loads without costly frequency conversion, thus enhancing fuel efficiency and reducing emissions.
Implementation Method 1
The rotor includes a plurality of symmetric phase windings while the stator has a single phase winding configured to generate an induced voltage
Data Source
AI summary
A power generating apparatus is provided. The alternator includes a rotor, a stator, one or more sensors and an electrical circuit. The rotor includes a plurality of symmetric phase windings while the stator has a single phase winding. The excitation control device is configured to control the induced voltage generated in the stator by regulating the rotating magnetic field generated in the phase windings of the rotor. The excitation control device is also configured to regulate the engine speed responsive to calculated load power. The electrical circuit connects the single phase winding of the stator and the load and is configured in a way that the induced voltage generated in the single phase winding and the output voltage applied to the load are at the same frequency. This arrangement reduces costs of the apparatus.