BI-LEVEL FLOW GENERATOR

An apparatus and method for treating sleep apnea includes a bilevel flow generator having an alternating current (AC) synchronous motor coupled to a low inertia centrifugal rotor/impeller. The process of acceleration and deceleration of the rotor involves moving from frequency A, amplitude A to frequency B, amplitude B in an optimal linear fashion using the so-called Bresenham algorithm. This is coupled with a tuned increase of the amplitude during the acceleration process which will produce the acceleration using minimum current allowing the use of smaller power supplies. During deceleration the process is accomplished in reverse fashion using a tuned decrease of the amplitude coupled with a special shunt circuit to prevent power supply voltage changes. These changes in amplitude overlay a current feedback mechanism used to prevent loss of synchronization of the motor by changing amplitude. Speed changes can also be timed so as to prevent desynchronization.