| Abstract |
A low-cost, high reliability drive without mechanical sensor is described. The application concerns a
wash machine system that, in spite of the simple, but effective solution, implemented in a fixed point
DSP, presents a good dynamic performance and good steady-state speed accuracy in a very wide
operating speed range.
Motor phase current reconstruction is performed suitably sampling the voltage across three shunt
resistances put in series to the IGBT emitters while, as far as phases voltage measurement is
concerned, bus voltage is sampled and then motor phase voltages are reconstructed inside the DSP
using PWM duty cycle and dead-time correction strategy.
Drive performances, as far as torque production is concerned, have been tested using a dynamometer
in a speed range up to 12000 rpm and compared with the torque produced with the usual constant Volt
per Hertz (V/f) method. The proposed sensorless control in spite of hardware simplicity that,
obviously, translates in low cost, comparable with the open loop solution, presents superior dynamical
performances, higher torque per ampere, and then efficiency. |
