Can I supply a BLDC motor controller with pulses? Or does it necessarily have to be DC?
This is how e-bikes operate with PWM  

Essentially a 1500W SMPS with a pot throttle to control Vref for PWM inside controller and fully protected two-way full-bridge or twin half bridge for braking and  battery charging like in Prius,Tesla etc.

This assumes you know all the design characteristics of the motor losses and dynamic driver losses, torque, SRF, motor impedance", heat mass , inertia for Back EMF and are an expert in controlled SMPS motive power design.

Not any Amazon cheapo 30A PWM board will work. ;) but what the heck, buy one anyways for learning curve and get a big CPU heatsink

Surge current from full acceleration will be up to ~8x max average of 30A= 240A based on motor 52V/DCR.