Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

MPaulHolmes · 11-12-2009, 02:55 AM

First, check this out:
SPACE VECTORS

You use PWM to control the red, green and blue vectors (voltages). The net result is the rotating black vector.

Here's a graphical representation relating to the field oriented control:
Field oriented control

The upper left animation represents the vector sum of the 3 phase voltages. Notice that Xa and Xb change with time. Now, you do a transformation so that you are rotating with the rotor. That is the upper right animation. Now, Xd and Xq do not change with time. You can now use a PI loops with those values since they don't change with time. Then you do an inverse transform and modify the pwm duties accordingly. I'm still trying to understand it. I will soon.

11-12-2009, 02:55 AM	#45 (permalink)
MPaulHolmes PaulH Join Date: Feb 2008 Location: Maricopa, AZ (sort of. Actually outside of town) Posts: 3,832 Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000 Thanks: 1,362 Thanked 1,202 Times in 765 Posts	First, check this out: SPACE VECTORS You use PWM to control the red, green and blue vectors (voltages). The net result is the rotating black vector. Here's a graphical representation relating to the field oriented control: Field oriented control The upper left animation represents the vector sum of the 3 phase voltages. Notice that Xa and Xb change with time. Now, you do a transformation so that you are rotating with the rotor. That is the upper right animation. Now, Xd and Xq do not change with time. You can now use a PI loops with those values since they don't change with time. Then you do an inverse transform and modify the pwm duties accordingly. I'm still trying to understand it. I will soon. __________________ kits and boards