Design Decisions

Component Selection

All parts were selected with the goal of securing a low cut-in speed for the turbine while maintaining within a $500.00 budget. To do this, mainly components of low forward-voltage were used.

Off-the-shelf, packaged components were avoided (besides the three-phase rectifier) to ensure optimal low forward voltage.

A MAD 5012 generator was selected for its high Kv rating and low torque.

The system PCB was confined to a 6" x 6" space to minimize cost.

Breaking Control Modules

Our team designed 6 modules to assist in the 3 forms of breaking required and to run the two boost converter systems:

Module 1 - Dump-Load Circuit: when an overspeed event occurs, route the rectified signal through an external resistor to ground via the “Chopper Circuit”.

Module 2 - Phase 1-2 Voltage Measurement: calculate the turbine rpm via phase 1 and 2 x-axis crossing point difference.

Module 3 - PI Controller: utilizes proportional integral calculation to control second stage boost converter duty cycle.

Module 4 - Current Sensor Measurement: used to detect and signal if load is disconnected.

Module 5 - Stage 2, 3, & 4 Voltage Measurements: voltage divider circuits used to detect electrical potential at each key stage; trigger LEDs to provide visual feedback.

Module 6 - Actuator Signal: provides PWM signal for mechanical braking control.

P.I. Design

A comparator references VREF and system output to generate a PWM for the converters. This was decided to be the optimal way to maintain a voltage within competition criteria and component spec. ranges.

The ADC limits the Arduino Mega to this 5V reference.

Planned but not implemented: A digital switch for passing the first boost convertor upon reaching a steady state at wind speeds above 11m/s.