Table1: Parameters of the motor

The details of the controller shown in Figure 3 are:

1. The maximum stator current limit (I_mn(max)) is given to the maximum torque block. In this block the Torque versus Current characteristic of the motor is implemented as lookup table or as a polynomial expression. The Torque versus Current characteristic of the PM machine parameters given in Table I is shown in Figure 4. The output of this block is the maximum possible torque (T_en(max)) that the motor can produce for the given value of I_mn(max).
2. The measured speed of the motor (ω_rn) is required to determine whether the motor operates is clockwise or anticlockwise direction.
3. In the comparator block the torques T_en(max) and T_ereq are compared and output of this block is the minimum of the two values. This torque is referred to as T^*_ereq and it is equal to min(T_ereq,T_en(max)).
4. The value of T^*_ereq goes to the current block and angle block. In these blocks the equations 17 and 18 are implemented as polynomials or lookup tables. The output of these blocks are I^*_mn and δ^*.
5. The values of I^*_mn and δ^* go to the transformation block and the further operation of the control strategy is already explained in the previous section.

Once the PM machine reaches the base speed, the flux weakening controller comes into action. The next section deals with the flux weakening controller.