Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Control</strong> methods <strong>of</strong> PM Synchronous motor<br />
The <strong>DTC</strong> has lesser parameter dependence and fast torque when compare <strong>with</strong> the<br />
torque control via PWM current control.<br />
Among the well-know advantages <strong>of</strong> the <strong>DTC</strong> scheme are the following:<br />
• Simple control,<br />
• Excellent torque dynamics,<br />
• Absence <strong>of</strong> coordinate transformations,<br />
• Absence <strong>of</strong> separate voltage modulation block,<br />
• Absence <strong>of</strong> voltage decoupling circuits,<br />
• There are no current control loops, hence, the current is not regulated directly,<br />
• Stator flux vector and torque estimation is required.<br />
Among the well-know disadvantages <strong>of</strong> the <strong>DTC</strong> scheme are the following:<br />
• variable switching frequency (difficulties <strong>of</strong> LC input EMI filter design),<br />
• high sampling time is required (fast microprocessor and A/D converter ),<br />
• inverter switching frequency depending on: flux and torque hysteresis bands,<br />
machine parameters, sampling frequency,<br />
• violence <strong>of</strong> polarity consistency rules (huge voltage stress for IGBT transistor),<br />
• current and torque distortion caused by sector changes,<br />
• start and low speed operation problems,<br />
• high sampling frequency needed for digital implementation <strong>of</strong> hysteresis<br />
comparators,<br />
• high noisy level,<br />
• high current and torque ripple.<br />
Many modifications <strong>of</strong> the basic switching table based direct torque control (ST-<strong>DTC</strong>)<br />
scheme at improving starting, overload condition, very low speed operation, torque<br />
ripple reduction, variable switching frequency functioning, and noise level attenuation<br />
have been proposed during last decade.<br />
In the last five years, many researcher have been carried out to try solve the above<br />
mentioned problems <strong>of</strong> ST-<strong>DTC</strong> scheme. Therefore, the following solutions have been<br />
developed in order to eliminated mentioned before problems:<br />
62