the summation node 62 in response to receipt of the zero frequency stator current i 2 and the command frequency signal u03c9 1 the current command calculator 50 generates a command current i i e the current at which the motor 14 should be energized for a given blower output as stated above the relationship used for this determination is shown in fig2 the command current i is fed to the comparator 54 and compared against the actual phase current i 1 as measured by the current sensor 74 the current comparator 54 outputs a current error value u03b4i that represents the difference between the actual stator phase current i 1 and the desired stator phase current i 2 for the desired air flow rate cfm d the current error u03b4i is transmitted to current regulator 58 which integrates the current error signal u03b4i to generate a manipulation output u03b4 u03c9 the manipulation output u03b4 u03c9 is added to the previous command frequency u03c9 1 to generate an updated command frequency u03c9 2 the updated command frequency 107 2 represents an updated frequency signal which is required at existing motor current i 1 to maintain the desired blower air flow rate output cfm d the command frequency u03c9 2 is transmitted to the frequency to voltage calculator 70 which generates an updated command voltage the frequency to voltage calculator 70 uses the relationship shown in fig3 to generate the command voltage and this voltage is input to the pulse width modulator 72 along with the updated command frequency while the voltage to frequency relationship shown in u s pat no 5 656 912 was non linear the voltage to frequency relationship of the preferred embodiment is linear for a given cfm d the function performed by the.