Field oriented control motor controller: is the measured Iq rms or the peak current?
It really comes down to the controller being used and how they expose the "setting" to the user.

Square root is actually annoyingly hard for microcontrollers/FPGA's to implement (no convenient approximations like sin,cos,tan re.CORDIC) but it is relatively trivial todo a final multiplication by 0.707 if end-results or settings are to be exposed as RMS quantities 

The equations associated with park-clark transformation resolve around peak  

$$
I_\alpha = I_a 
$$
$$
I_\beta = \frac{1}{\sqrt{3}}I_a + \frac{2}{\sqrt{3}}I_b
$$
Assuming a,b,c are balanced &amp; of equal amplitude and thus such a reduction is valid

$$
I_q  = I_\alpha sin(\theta) + I_\beta cos(\theta)
$$
Where \$\theta\$ is the present \$\omega\$t 

THUS at the centre of a DQ (or a FOC) controller Iq will be a peak quantity