US Patent 7588422 Pump driving method and device therefor

A pump driving apparatus has a characteristic changing section which receives a set pressure, a set flowing amount, a set horse power, and a DC voltage of the converter section as input, outputs modified values of pressure, flowing amount, and horse power, and supplies the modified values to the horse power command generation section. Therefore, the motor can be driven to suit the change in power voltage so that the motor capacity can be utilized sufficiently.