Modelling of Field Orientation Control (FOC) Method in 120 kW Brushless DC Motor (BLDC)

Brushless DC (BLDC) motors have the advantage in high reliability compared with conventional DC motors because of the absent of the brushes. BLDC requires switching with the help of power electronic components which is 6 pulse inverter. One of the methods is field orientation control (FOC) by controlling id and iq. With FOC, it is possible to control the torque of BLDC like convensional DC Motor. Furthermore, by controlling id and iq independently, Maximum Torque Per Ampere ratio (MPTA) to minimize the current can be achieved so that it can improve motor efficiency. In this paper, the FOC method applied in 120kW BLDC motor is investigated. From simulation result, when the torque is higher, then response of the motor is faster to achieve nominal rotational speed. Otherwise, lower torque that applied to the load cause longer transient session. The speed of BLDC motor could be control using control loop from torque control. In this paper, high torque ripple caused by difficulties of PI control setting, high load (100Nm), and trapezoidal back-EMF of the BLDC.