The Filière Energie et Techniques environnementales (FET) has the digital systems course and labs in the 3rd (autumn) semester. The semester counts 15 weeks and ends with a little project. The aim of the inverter project is to generate a 50 Hz AC power supply from a DC input.
The reference signal and the generator output are digitized to 1 bit with the help of two comparators. The digital circuit receives these signals and controls a DC motor coupled to the generator.
The circuit works as follows:
- the difference between the mains period and the generator period is calculated
- if the generator is too slow, the DC motor voltage is raised; if the generator is too fast, the DC motor voltage is diminished
The system consists of
- an assembly of a DC motor and an AC generator
- an FPGA prototyping board
- an I/O board with 2 sinewave inputs and a PWM output
The DC motor is controlled via a 12 V PWM signal. It is mechanically coupled to the DC generator. With a mean voltage of 6 V, the assembly turns at a frequency close to 50 Hz.
Synchro I/O board
The HEB-synchro I/O board receives 2 sinewaves: one from a 50 Hz function generator and one from the AC generator. These signals are triggered at 0 V in order to deliver logic-levels signals to the FPGA.
The FPGA delivers a PWM output which controls a power switch. The switch then drives the DC motor.
In order to start the projects you should do the following:
- Read carefully the specifications above
- Draw the architecture of the circuit in the form of a block diagram
- Consult the guides for the first steps into the design software
Additional informations for teachers.