STUDENT PROJECT: Evaluate and Extract Fundamental From PWM for Compressor Protection Device
BITZER Electronics A/S
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Screw and scroll compressors only work when they turn in the right direction. Making them turn in the wrong direction for example by wrong phase sequence to the motor will destroy the compressor. The destruction of the compressor can be avoided by mounting a compressor protection device that monitor the voltage phase sequence and disconnects the compressor from supply if the phase sequence is wrong. Increasingly the compressors are driven by frequency converters to obtain variable speed and thus save energy. Using a frequency converter means the motor voltage is a PWM signal and not a sinusoidal waveform.
This poses a challenge for the protection device since obtaining the phase sequence by measuring the motor voltage is no longer possible. At the same time the processing power in µprocessor have increased so it might be feasible to sample the motor voltage very fast and extract the fundamental voltage waveform by signal processing.
Methodology
Select suitable signal evaluation algorithms.
The signal evaluation algorithms can be tested using the simulation software PLECS since it contains PWM generators that can generate different PWM patterns used in frequency converter (i.e., SpaceVector, 60 deg PWM). Requirements regarding sampling rate and processing power should also be investigated.
Primary objectives
// Evaluate a few signal processing algorithms by simulation.
// Estimate the required sampling rate and processing power.
Secondary objectives
// Implement and test the selected signal processing algorithm using our prototype PCB.
Prerequisite skills
// Understanding of signal processing.
// C-code knowledge is required for testing the algorithm on the prototype PCB.
Supervisors
Hans Jørgen Nørgaard
Software Engineer, Control Team
[email protected]
Kresten Sørensen
Head of Control Team, BITZER Electronics
[email protected]
Department: Control Team
Location: Kærvej 77, 6400, Sønderborg, Denmark
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