ST7FMC/AC-Motor 6-step voltage without PWM

Posted on May 17, 2011 at 10:17

Hi,

you will receive an answer as soon as possible.

Regards,

Tanio

Posted on May 17, 2011 at 10:17

Hi,

I'd like to analyse the switching losses in the power circuite (IGBTs). One time with sinusoid (PWM) voltage, the other one only switching the IGBTs on (for 180°) and off, without reducing the voltage by a PWM. The motor gets the whole inverter voltage.

How can I manage this? I changed the look-up table for the 9/10-bit PWM to the maximum Value (127 in the 9Bit table, 79 in the 10Bit table). If I turn the voltage to the maximum, the PWM Duty-cycle is near 90%, but not 100%. How can I reach 100%, meaning no switching if the current flows through the IGBTs?

Best regards,

Micha

Posted on May 17, 2011 at 10:17

Sorry, but with this values the uC stops with malfunction (red LED is blinking). The error occured, if the voltage, which is slowly increasing, reaches 99%. 99% are working well, but if I turn the potentiometer RV2 to the maximum voltage the motor knocks and then it stops.

Regards,

Micha