Using multiple NPN transistors with resistors from base to ground
Your circuit won't work, I'm afraid. The highest voltage delivered to the motor load will be something like 3.3-0.7 V or lower. The 3.3 V is the best voltage out of the MCU I/O pin on a good day, the 0.7 V is the transistor's base-emitter voltage drop).

Use the following circuit for each of your three coils.







simulate this circuit &ndash; Schematic created using CircuitLab

R1 determines the transistor base current and is driven by your MCU's General-Purpose Output (GPO) pin. The base current is something like (3.3-0.7)/2200 or just over 1 mA. Try reducing this resistor if your motor coils are not being driven hard enough when on (Vce is above 0.5 V), maybe 1 K will be more suitable.

R2 drains away GPO's leakage current when GPO is configured as an input after reset and is hi-Z.