**5. Experimental setup**

480 Induction Motors – Modelling and Control

torque(Nm)

Torque (Nm)

<sup>0</sup> 0.5 <sup>1</sup> 1.5 <sup>2</sup> 2.5 <sup>3</sup> -10

t(s)

(a)

<sup>0</sup> 0.5 <sup>1</sup> 1.5 <sup>2</sup> 2.5 <sup>3</sup> -10

t(s)

(b) **Figure 10.** (a) Torque response for proposed inverters (b)Torque response for conventional PWM inverters

> Conventional PWM inverter New three-phase inverter

<sup>0</sup> 0.5 <sup>1</sup> 1.5 <sup>2</sup> 2.5 <sup>3</sup> -10

**Figure 11.** Torque response for proposed and conventional PWM inverters

t(s)

The experimental setup was realized based on the DS1103 TMS320F240 dSPACE kit (dSPACE, 2006a, 2006b, 2006c, 2006d, 2006e). Figure 13 gives the global scheme of the experimental setup. This kit allows real time implementation of inverter and induction motor IM speed drive, it includes several functions such as Analog/Digital converters and digital signal filtering. In order to run the application the control algorithm must be written in C language. Then, we use the RTW and RTI packages to compile and load the algorithm on processor. To visualize and adjust the control parameters in real time we use the software control-desk which allows conducting the process by the computer.

The novel single phase inverter structure for pre-calculated switching is based on the use of IGBT (1000V/25A) with 10 kHz as switching frequency. The switching angles are predetermined off-line using Genetic Algorithms and stored in the card memory in order to speed up the programme running. The non-filtered inverter output voltages are first designed in Simulink/Matlab, then, the Real-Time Workshop is used to automatically generate optimized C code for real time application. Afterward, the interface between Simulink/Matlab and the Digital Signal Processor (DSP) (DS1103 of dSPACE) allows the control algorithm to be run on the hardware.

Minimizing Torque-Ripple in Inverter-Fed Induction Motor Using Harmonic Elimination PWM Technique 483

<sup>0</sup> 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 -50

t(s)

<sup>0</sup> 0.5 <sup>1</sup> 1.5 <sup>2</sup> 2.5 <sup>3</sup> -2

t(s)

**Figure 16.** Experimental torque response for proposed PCPWM inverters

**Figure 14.** Snapshot of the laboratory experimental setup

**Figure 15.** Experimental inverter filtered output voltage.


Torque (N.m)

volts

The master bit I/O is used to generate the required 2 gate signals, and a several Analog-to-Digital converters (ADCs) are used for the sensed line-currents, capacitors voltage, and output voltage. An optical interface board is also designed in order to isolate the entire DSP master bit I/O and ADCs. The block diagram of the experimental plant is given in figure 14

**Figure 13.** Global scheme of the experimental setup
