Controlling device for a brushless motor

Claim 1

A controlling device for a brushless motor comprising: a synchronous motor having a rotor; a power source and a plurality of unit converting devices which are coupled to the synchronous motor; means for detecting the rotor position of said synchronous motor and for outputting phase-shifted position signals with respect to the rotation of the synchronous motor, with each one of said outputted phase-shifted position signals being spaced at a pre-determined phase from another one of said outputted phase-shifted position signals; means for controlling the phase of each of said unit converting devices in response to each of said phase-shifted position signals wherein each of said unit converting devices generates a 3-phase alternating current output; a plurality of isolation transformers mounted between each unit converting device and said motor; and combining means for combining the output of each said isolation transformers whereby 3-phase alternating current outputs from each of the unit converting devices shifted at said pre-determined phase are synthesized producing a sine wave approximate staircase current which is supplied to said motor.