I am designing a Propeller test bed where BLDC motor with 80A maximum continous current and voltage range of 44V to 52V is being used with its corressponding ESC. I want to make use of SMPS instead of bench power supply. Will the SMPS affect the motor operation as the throttle will move from minimum PWM(30% throttle) to Max PWM(100% throttle)?

 

The Motor's PEAK-CURRENT is what You need to pay attention to.
This is why a large-Battery with a very strong Battery-Charger is a better plan.

A Battery can supply the short Peak-Currents without a problem,
but the SMPS may go into "Current-Limiting-Mode",
or possibly oscillate on-and-off, or even shut-down completely,
when hit with a excessive amount of Peak-Current.
This will depend upon the specific design of the SMPS that You would like to use.

Peak-Currents can easily be ~2 to ~4 times the max-Continuous-Current.
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For a power supply of that size, I would much prefer a linear supply,