CURRENT SENSING ON POWER MOSFET IN ELECTRICAL MOTOR CONTROL DRIVES

V reguliranih elektro-motornih pogonih se pojavlja potreba po meritvah tokov. V praksi se najpogosteje uporabljajo so-upori in Hallovi senzorji. Obravnavani senzor temelji na meritvi padca napetosti med sponkama S in D MOSFET-a. Pred drugimi tipi senzorjev ima številne prednosti, najpomembnejša je, da v pretvorniku ne povzroča dodatnih izgub. Poleg tega v vezju niso potrebni dodatni elementi, ki bi povzročali parazitne induktivnosti ali povečali kompleksnost proizvodnje. V magistrskem delu je predlagano merilno vezje senzorja. Preizkušeno je v simulacijskem programu na osnovi orodja SPICE in praktično izdelano. Opisan je postopek meritve termične upornosti med spojem tranzistorja in hladilnikom ter meritve stikalnih izgub. Merilnik je bil preizkušen in primerjan z rezultati, dobljenimi s Hallovimi senzorji. Predlagani so razni načini kompenzacije za izboljšanje točnosti merilnika. Program za vodenje pretvornika in meritve teče na 32-bitnem ARM procesorju serije STM32F4.In electrical motor control drives exists a demand to sense currents. In practice, shunt resistors and Hall Effect sensors are the most common devices used for that purpose. The presented sensor is based on terminal voltage measurement (between S and D) on power MOSFET. It has many advantages, the most importantly the sensing principle is lossless. There is also no need for additional circuit elements that would cause parasitic inductances or increase production complexity. In this work, the sensor circuit is proposed. It was tested in simulation program based on SPICE tool and practically built. The measurement of thermal resistance between junction and sink was made as well as the switching losses measurement. Sensor was tested and compared to the Hall Effect sensor. For better accuracy, different ways of compensation are proposed. The program for control of inverter and measurements runs on 32-bit ARM processor, STM32F4 series