For RPM starting at zero, you cannot inject much _power_ to the BLDC motor. The load that controlled "sees" at motor coils is of very low impedance. Meaning that immediately when the "switches" open, the current rises very fast, and controller needs to turn off the switches fast also. The phase voltage will not be very high, typically around a volt or two. So the P = U*I is left pretty low. In other words, for low RPM, you must be able to provide as much current as possible in order to get more power. The way you achieve this is from WB, is that you must specify the "nominal current" to equal the maximum current that your phase control electronics is able to provide. It probably is more than your power source's rated 10A (which is probably the RMS current it supplies). Phase current may be lot higher if your wiring etc allows for it.
Second, you can (should) play a little with the PWM frequency. For low impedance motors, typically you prefer to use higher control frequency. I have STM32G431 running full speed (170 MHz if I remember correctly), and it can operate up to 24 kHz without errors, but laving some headroom, I use 20kHz control frequency.
Third; for these very quick PWM control sequences, make sure that you minimize the voltage ripple at the power supply. Your 10A power supply must be bypassed with lots of low-impedance capacitance. Low-ESL electrolytes or lots of at least 2*over-rated ceramic capacitors.
