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Master of Science Thesis in Electric Power Engineering - page 75 / 114

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VOLTAGE ORIENTED CONTROL – IMPLEMENTATION

Figure 4.5 : Matlab Help from dSpace, PWM interruption [33]

The interrupt is generated that can be shifted nearly over the whole PWM period by specifying the interrupt alignment (Source : dSpace Help in Matlab [33] ).

In Simulink, a block “DS1103SLAVE_PWMINT” is available. To trigger the whole Simulink model, we have to link this block to another block called “Timer Task Assignment” as shown in the top level model Figure 4.2. Finally, every interruption signal, ONE sample will be acquired.

Nevertheless, the “overrun” condition should be checked. We need to be sure that the calculation (in the controller) is finished before a new sample is acquired.

CONTROL SIGNAL “GO”

The “GO” signal (Figure 4.2) is used to activate the integrator part of the controller (see section 3.9.1 Simulation steps, Simulink block diagram” for explanation). It is also used to enable or disable PWM block.

HOW TO FORCE IGBTS OFF

It’s possible to force IGBTs OFF disabling the block “Control system and PLL” since the output will be zero when disable (if set correctly…). A zero value will be sent to the PWM block and the switches will be open. Another solution in presented in Figure 4.6 and is present in the main block diagram in APPENDIX G. Figure 0.43.

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