Testing Small Wind Turbine Generators - Renewable and ...

2.1 OverviewThe purpose of the dynamometer system is to drive the CE&P permanent magnetelectrical generator at various speeds and various resistive loads, while electrical currents,voltages, and rotational speed are measured.To accomplish this, an identical electricalgenerator is operated as a motor, supplying mechanical power to the generator being tested.Several subsystems make this possible, each of which is discussed in detail.• Mounting Structure: A rigid platform holds both electrical machines steady duringtesting. The platform is designed for high static and vibrational loads.• Drivetrain: A chain drive conveys mechanical power from the motor to the generator.• DC Power Supply: To reach adequate voltage, the system is powered by two DCpower supplies. These are connected in series and operated simultaneously.• Power Electronics: A custom power electronics package is required to allow thepermanent magnet generator to operate as a motor.• Control System: Continuous control of the motor is achieved through the use of anoptical encoder and a digital signal processor running Dynamic C code.• Dump Load: The generator output is rectified and loaded with up to five powerresistors. A mounting structure holds the resistors securely in place.• Measurement System: To adequately analyze the system, the system speed, inputand output voltage, and input and output currents must be measured.Figure 2.1 shows these systems and the flow of power and information between them.Electrical power is supplied by the DC power supplies.The power electronics packagecontrols the flow of this power to phases of the motor, where the motor converts it tomechanical power. The drivetrain transfers mechanical power to the generator, where itis turned back into electricity and is dissipated in the dump load.To keep the motorrunning smoothly, an optical encoder tracks the angular position of its shaft. Based on the6