Patent ID: 7444070

Claim:
In a method for monitoring a fan, driven by an electronically commutated motor, against a malfunction causing a power need of said motor that is different from the power need under normal operating conditions, said motor having associated therewith a rotation speed controller for controlling the rotation speed thereof to a specified rotation speed value, and a current controller for setting the motor current to a specified target value, said method comprising: using an output signal of the rotation speed controller to generate a target value signal (PWM 1 +) for said current controller, said target value signal representing a value of the motor current at the presently specified rotation speed; comparing said target value signal (PWM 1 +) to a specified value; if the set target value signal (PWM 1 +) differs from the specified value, generating a signal indicating malfunction; and subsequent to the foregoing steps, terminating regulation of rotation speed to the specified rotation speed.