Sine amplitude low in test mode

[Bena]

I was testing my inverter today, and got confused. I was following the guide on the wiki (https://openinverter.org/wiki/Schematic ... structions) which went smoothly until i connected the motor:
It wouldn't spin and with input of 50v DC i was only seeing around 2v AC on the inverter outputs. The pwm signals were almost constant 50% on all phases, quite like in the previous step when testing the gate drivers.

It turned out setting boost to a high value (20000) changed this. After this the motor spun (at 10hz) and the AC voltage was around 30v. This is not mentioned in the guide, is it intended to work like this? I found the amp value was only around 5000 with default boost (1700). It was around 23000 after changing boost. Ampnom was set to 100, and decreasing it did also decrease the amp value. Fweak did not seem to have any effect.

I am using the mainboard v3, firmware 5.27, and the rest is an inverter from a chinese EV. PWM is active low, running at 4,4kHz. Testing was done with a small 370w 230/400V induction motor.

[johu]

It's all normal so far, just surprised you needed so much boost to get spinning. What value did you enter for fslipspnt? Setting fweak=10 as stated would mean you have full amplitude at 10 Hz

[Bena]

Good to hear it is working normally. I was using fslipspnt=10. I suppose the small motor has a large winding resistance and needs more voltage to spin unloaded, compared to a bigger motor.