Patent ID: 9035583
Filing Date: 2015-05-19
Classification: H02P

Abstract:
1. A system for controlling the speed of rotation of an electric fan including an impeller driven by an electric motor and associated with one or more heat exchangers, mounted in a motor vehicle in such a way that the forward displacement of the vehicle causes a flow of air which impinges on the impeller causing a rotation thereof in the same direction as the rotation caused by the electric motor, the system comprising: a driving circuit for the electric motor of the electric fan, coupled to an electrical system including a battery of the motor vehicle and comprising a plurality of controlled electronic switches, and an electronic control unit arranged to control said driving circuit such as to cause the flow in the electric motor of a variable average current capable of making the electric motor reach a required speed of rotation, in accordance with a predetermined relationship or function, wherein the control unit is arranged to store a predetermined value of duty cycle and a predetermined threshold of rotation speed, and to control the motor through the associated driving circuit in such a way that when the duty cycle is not greater than the predetermined value and the rotation speed of the powered electric motor exceeds said threshold the driving circuit causes electrical braking of the motor and when the value of the duty cycle is greater than the predetermined value and the rotation speed of the powered electric motor exceeds said threshold the driving circuit does not cause the electrical braking of the powered electric motor of the electric fan.