In the simplest sense, boost is an offset voltage applied to the output motor voltage and is applied under certain operating conditions, depending on the specific boost feature.
This offset voltage helps increase available motor torque at low operating frequencies since the normal output voltage levels are low in this frequency range. This may be required in higher friction applications or for motors with high rotor inertia or loads with high inertia in order to get the system moving or better track the desired motion profile.
There are several types of boost settings available in the Parker VFD drives, some that apply under no-load conditions, some under load conditions, and some specific to acceleration ramps,
The basic boost parameters are configurable when operating in V/Hz (Volts/Hz) mode. SV (Sensorless Vector) and CL (Closed Loop) modes typically have their own internally calculated boost values that are applied relative to what the control loop is seeing and not user adjustable directly.
Some example boost types (see individual product software manuals or help files in the programming software for more details - terminology may vary slightly from product to product).
FIXED BOOST = This parameter allows for no-load stator resistance voltage drop compensation. This correctly fluxes the motor (under no-load conditions) at low output frequencies, thereby increasing available motor torque.
AUTO BOOST = This parameter allows for load dependent stator resistance voltage drop compensation. This correctly fluxes the motor (under load conditions) at low output frequencies, thereby increasing available motor torque.
ACCELERATION BOOST = This parameter provides an additional amount of fixed boost when the drive is accelerating. This can help when starting heavy/high stiction loads.
SEARCH BOOST = The level of search boost applied to the motor during the speed search phase of the flycatching sequence.