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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.

Inverter boards.JPG



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.

Synchro system.svg


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

Motor-generator assembly

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.

FPGA board

The main board is the school's FPGA-EBS lab development board. It hosts a Xilinx Spartan xc3s500e FPGA and features many different interfaces.

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.

Getting started

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 Information

Additional informations for teachers.

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