BLDC actuators tend to be of the coin type, and operate in a similar way as an ERM. BLDC actuators differ from ERM in that instead of having mechanical commutation, the commutation happens electrically, which eliminates the need for brushes. All else being equal, the BLDC actuator is more reliable and power efficient than an ERM. However, the BLDC electronic requirements are more involved than in the case of an ERM. For this reason, BLDC modules are available, which integrate the BLDC driver inside the actuator's enclosure, making the BLDC "look" like an ERM, by requiring only a positive voltage and GND to be driven. A picture of a BLDC module is shown in Figure 2-3.

Figure 2-3 BLDC Module Picture

Existing BLDC modules make electrical braking impossible, since it is not possible to reverse the direction of the driving signal. Keep in mind that the voltage applied to the module goes first to power the driver, which implies that PWM signals cannot be used. It is also important to note that the driver inside consumes power, and has a response time that will impact the overall performance of the module.

Existing BLDC modules have additional restrictions in terms of the voltage requirements; since the voltage applied to the wires is supplying an IC, the actuator will not move for voltages below the power-up voltage of such an IC, which tends to be around 2.9 V. This implies that very soft vibrations, and ramp effects are unattainable.