Thalis: Power Factor Corrector Module |
Description: |
Doing consulting research for the improvement and cost reduction for an industrial power factor corrector with automatic capacitor recognition. |
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Keywords: |
Power factor corrector - regulator, PIC 16F877, LabVIEW, MPLAB, picc, capacitor banks |
Status: |
Complete (January 2003 - March 2004) |
A power factor corrector (regulator) is a device used in industrial enviroments in order to preserve the quality of the power. Utility companies charge extra fees to industries that "pollute" the supply with harmonics or don't retain the power factor within a range for most of their operating time.
This device supervises the power supply and dynamically connects or disconnects capacitor banks to balance loads' reactive power.
"Thalis" was selling a power factor corrector module that used discrete CMOSs to provide basic functionality of power factor correction. The design was working but its features didn't make this product competitive anymore.
The digital part of this power factor corrector was redesigned in order to reduce cost but more importantly improve its features, to turn it to an inexpensive excellent choice. Microchip's PIC16F877 uC was selected because of PICs' good rumor in industrial applications.
A special development strategy was established for this project. In order to reduce overall development cost, the uC was initially used as a terminal providing low level services (drivers' layer) via serial port while higher level logic was implemented in NI's LabVIEW. This way PFC's behaviour was able to change with some clicks of inexpensive visual programming instead of C coding and Flash burning. Gradually modules that were verified to behave correctly (e.g. relay controller, display and keyboard controller, timing controller, EEPROM storage) got C coded and formed the services' layer of the application. At the end top-level application logic including User Interface got C coded and then serveral system-level optimizations took place.
This approach was eventually slower than programming straight in C but reduced the overall development risk. This was essential because PFC's improvement was based on interviews through the development cycle and exact specifications weren't available at any given time.
This modular "3-tier" design protects the competence of the product because it can be easily and safely ported to any uC that happens to be more inexpensive and robust with changes only to the drivers' layer. The transition will be transparent to the end users because services' and application's layers will remain the same. |
Related files |
Size |
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Final tests on the prototype (.jpg) |
46.6 kB |
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Related links |
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Product's web page |
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User manual in Greek |
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