Electric Machine Control Using PWM for Speed Stabilization
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Solution Overview
Problem
Rotary machines experience overspeed and premature failure due to varying fluid flow rates and loads, leading to uneven electric current generation and heat dissipation issues, which are not effectively managed by existing control systems.
Innovation Solution
Implementing a control system that uses pulse width modulation signals to monitor and adjust the output voltage of electric machines, creating additional magnetic fields to oppose forces and short or increase current in coils, thereby managing rotational speed and load demand dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If resistors are used to increase opposing torque in the generator, then the turbine overspeed problem is mitigated, but heat generation increases requiring additional heat dissipation management
Solution Approach 1:
The patent converts the harmful heat energy that would normally be dissipated by resistors into useful electrical energy. By using power electronic converters to rectify and regulate the generator output, the system transforms the energy that would become waste heat into controllable electrical power, eliminating the heat dissipation problem while maintaining speed control.
Solution Approach 2:
The patent replaces the mechanical/resistive torque control method with an electrical control system. Instead of using resistors to create opposing torque, the system uses power electronic converters to electrically regulate the generator's output, thereby controlling turbine speed without generating excessive heat.
2Reliability
If the generator provides opposing torque to control turbine speed, then overspeed is prevented, but the torque may be insufficient when load demand changes, causing speed instability
Solution Approach 1:
The patent implements a feedback control system using power electronic converters that continuously monitor the turbine speed and load demand, then adjust the generator's electrical output accordingly. This closed-loop control ensures the generator provides the appropriate opposing torque to maintain stable speed while adapting to changing load conditions.
Solution Approach 2:
The patent makes the generator's opposing torque dynamic and adjustable through power electronic control. The system can rapidly modulate the electrical load on the generator to match changing turbine output, providing adaptive speed control that responds to both increasing and decreasing load demands in real-time.
3Ease of operation
If pulse width modulation is used to control output voltage, then voltage magnitude can be adjusted independently of force and load, but system complexity increases
Solution Approach 1:
The patent makes the power electronic converter system multi-functional, enabling it to perform voltage regulation, current control, and speed stabilization through a single integrated control platform. This universal approach allows independent voltage control while avoiding the need for separate control systems for each function.
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 approach stabilizes the rotational speed of rotary machines, reduces heat generation, and extends their lifespan by matching current output with varying fluid flow and load conditions, preventing overspeed and ensuring consistent power delivery.
Implementation Method 1
controlling operation of the electric machine includes creating an additional magnetic field in the electric machine using the pulse width modulation signals that opposes a force applied to the electric machine
Implementation Method 2
the flow of air through a turbine can rotate turbine blades, which rotate a rotor of the turbine relative to a stator of the turbine. This rotation can be used to inductively transform electric current by converting the rotation or the rotor relative to the stator into the electric current
Data Source
AI summary
A system and method include monitoring an operating condition of an electric machine that converts rotational movement into an output voltage that is conducted into a circuit coupled with the electric machine, controlling operation of the electric machine using pulse width modulation signals, and changing a magnitude of the output voltage that is conducted into the circuit from the electric machine as a result of the pulse width modulation signals.