Indirect field-oriented control (IFOC) is widely used for induction machines, such as motors of vehicles. For example, IFOC is utilized in some vehicles for three-phase induction machine control in traction application. IFOC can be a valuable tool, for example in using rotor resistance values in estimating torque values for an induction machine, for example of a vehicle. IFOC is commonly used control method for a three-phase induction machine. For example, if induction machine parameters of the IFOC are know, the IFOC reduces the complex dynamics of an induction machine to the dynamics of a separately excited direct current machine. Using this approach allows the flux and torque of the induction machine to be controlled independently.
However, if the parameters used in IFOC are not identical to the actual parameters in the induction machine, the desired machine flux level may not be properly maintained. In addition, because the desired torque is estimated based on the actual parameters, torque linearity may also be lost. For example, it may be difficult to properly maintain decoupling between the flux and torque if less than ideal rotor resistance values are used in the calculation. Thus, rotor resistance values, which are functions of rotor temperature, can have a significant impact on the performance of IFOC. Torque accuracy, response and efficiency can similarly be affected by the accuracy of the values of rotor resistance that are used in the calculations.
Accordingly, it is desirable to provide improved methods for controlling an induction machine, such as for a vehicle, for example that provide improved estimates of rotor resistance that may then be utilized in obtaining improved estimates for motor torque. It is also desirable to provide improved systems for controlling an induction machine, such as for a vehicle, for example that provide improved estimates of rotor resistance that may then be utilized in obtaining improved estimates for motor torque. Furthermore, other desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.