This chapter summarizes the application of Model Predictive Control (MPC) technique to a two-level inverter driven induction motor (IM) drive. There are two types of MPC: continuous control set MPC (CCS-MPC) and finite control set MPC (FCS-MPC). In CCS-MPC, the controller generates a continuous output for a modulator, and the modulator generates the switching signals for the inverter to generate the required voltage. Conversely, in FCS-MPC, the finite number of control actions available in the system - inverter switching states for motor drives - is evaluated against the desired control objectives. The outputs of the controller are discrete and are directly used to switch the power switches on/off in the inverter. The finite-state predictive torque control (FS-PTC) of motor drives is an FCS-MPC strategy. In FS-PTC, torque and stator flux are predicted for the finite number of admissible switching states of a voltage source inverter (VSI). In this study, a two-level VSI (2L-VSI) is considered to produce the necessary voltage vectors. Experimental results illustrate that FS-PTC algorithm yields good performance in terms of torque and flux ripple, stator current THD, robustness against load torque disturbance, step torque response and step speed response.

Chapter Contents:

• 15.1 Introduction
• 15.2 Comparison between the PTC and classical control strategies (FOC and DTC)
• 15.3 PTC System modelling
• 15.3.1 State-space representation of three-phase systems
• 15.3.2 Modelling of the IM
• 15.3.3 Modelling of the inverter
• 15.4 Basic structure and working principle of PTC
• 15.4.1 Estimation
• 15.4.2 Prediction
• 15.4.3 Cost function optimisation
• 15.4.4 Limitations of the FS-PTC
• 15.5 SPVs-based FS-PTC
• 15.5.1 Selecting prediction vectors
• 15.5.2 Optimum voltage vector selection
• 15.5.3 Average switching frequency reduction
• 15.5.4 Overall control structure of SPVs-based FS-PTC
• 15.5.5 SPVs-based FS-PTC algorithm
• 15.6 Computational efficiency improvement in the SPVs-based FS-PTC
• 15.7 Performance of an IM drive under FS-PTC
• 15.7.1 Steady-state behaviour
• 15.7.2 Transient capability under rated-speed reversal
• 15.7.3 The average switching frequency
• 15.7.4 Investigation of robustness against rated-load torque disturbance
• 15.7.5 Step rated-torque-transient characteristics
• 15.7.6 Step rated-speed-transient characteristics
• 15.8 Summary
• List of symbols
• Glossary of terms
• References

Inspec keywords: voltage control; torque control; induction motor drives; machine control; predictive control; invertors; voltage-source convertors

Other keywords: stator current THD; flux ripple; step torque response; continuous control set MPC; model predictive control technique; finite-state predictive torque control; CCS-MPC; switching signals; step speed response; voltage vectors; load torque disturbance; IM drive; finite control set MPC; 2L-VSI; voltage source inverter; two-level inverter driven induction motor drive; FCS-MPC

Subjects: Drives; Optimal control; Asynchronous machines; Mechanical variables control; Voltage control; Control of electric power systems; DC-AC power convertors (invertors)