R.A.C.E. Project Urbino March 2012 ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

Some Features of DC motors ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

Different type of servomotor DC brushed motors AC brushless motors Step motors ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

DC Brushed motors Benefits: 1.max torque at 0 r.p.m. 2.Easy to control shaft speed 3.Easy and economical to produce Disadvantages 1.Brushes consumption 2.Collector consumption ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

AC Brushless motors Benefits: 1.Brushes non present 2.Greater Electrically efficiency than DC motor 3.Low weight Disadvantages 1.Complex speed control 2.More expensive than a DC motor of same power. ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

STEP motors Benefits: 1.Very fine adjustment of position also without feedback 2.Higher torque also at 0 r.p.m. 3.No gear box needed Disadvantages 1.Low number of r.p.m. ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

A model for DC motor We can define a set of differential equations ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri Equivalent circuit of rotor Equivalent circuit of stator Magnetic stator flux Electromotive force Torque

A model for DC motor (2) V e = R e I e + L e di e (t)/dt V a = R a I a + L a di a (t)/dt + f.e.m. If i e = const => f.e.m. = K e I e K a  AND V a = R a I a + L a di a (t)/dt + K e I e K a  Appling Laplace transform we obtain: Let K e I e K a = K m and the mechanical equation to the shaft ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

A model for DC motor (3) We obtain a model with 2 poles in a feedback configuration If i e = const => f.e.m. = K e I e K a  AND V a = R a I a + L a di a (t)/dt + K e I e K a  Appling Laplace transform we obtain: Let K e I e K a = K m and the mechanical equation to the shaft ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri

Thank you! ITIS “E. Mattei” to R.A.C.E. Leonardo Project – 03_29_2012 Urbino – IT - Massimo Zandri