Dear Udayan Banerjee,

probably DC-link voltage is too low? Can you provide this value?

Kind regards.

Dc Link voltage is 335 volts and reference was provided around 300v, whereas the load side AC voltage is being controlled at 40v

Thank You. Can you give me also the motor rated values? What type of controller did you use for the control implementation? In the past I had problem with fixed point implementation of a IM FOC control algorithm.

Ratings of the Machines are as follows

PMSG

1.73 KVA, 415v(L-L), 1.5 A,1500 rpm,6 Pole

DC-Motor (shunt type)

2HP, 220v ,0.5A (armature current), 1500 rpm

We are using PI controller as of now.

Ok. If I understood correctly, your PMSG is connected via PWM inverter to a DC-link at 300. If this is true, your problem is that at rated speed of 1500 rpm the generated voltage (400 V line-to-line) is too high and not compatible with your DC-link voltage. In fact with Vector Space Modulation you can reach a maximum peak ac voltage of about Vdc/sqrt(3)=173 V, which is much lower than sqrt(2/3)*400=326 V. This is, probably, the reason because iq gets out of control.

Thanks Antonnio , So what can be the possible solutions for this? Should I increase my reference speed such that both work at near about 400v ?

No, I think you should lower the reference speed to accommodate the voltages.