Patent ID: 8133033

Claim:
An apparatus for maintaining pneumatic pressure for a pneumatic system, the apparatus comprising: a compressor ( 16 ) which provides compressed air to the pneumatic system; a motor ( 14 ) which drives the compressor; a speed controller ( 12 ) which controls a speed of the motor; and at least one precharge circuit ( 20 , 20 ′, 20 ″) for charging at least one capacitor ( 22 , 22 ′, 22 ″) associated with the motor ( 14 ) and the speed controller ( 12 ) with current from a high voltage bus ( 10 ), the precharge circuit including: at least one charge limiting resistor ( 24 , 24 ′, 24 ″) disposed between the at least one capacitor and a low reference node, and a switch ( 26 , 26 ′, 26 ″) for selectively bypassing the at least one charge limiting resistor ( 24 , 24 ′, 24 ″).