This invention provides, in various embodiments, a variable frequency drive system for controlling a pump driven by a variable frequency electric motor, with the pump in fluid communication with a fluid system. The drive system of this invention improves the efficiency of the prior variable frequency drive systems by inserting into the memory of the variable frequency drive the maximum flow required for the particular flow system in which the pump is operating and adding an initial pump starting module that limits the initial starting flow rate from the pump to the desired maximum flow rate for the system, which is separately calculated.