Abstract: A closed-loop control system for a DC motor includes a DC motor 12, a current sensor 14 for determining a current of the motor, a voltage sensor 32 for measuring a voltage of the motor 12, and a micro-controller 33. The micro-controller is constructed and arranged to (1) compare the determined current with a set point and output a pulse width modulated (PWM) duty cycle to control the motor, and (2) calculate a PWM duty cycle limit based on the measured voltage and compare the outputted PWM duty cycle to the PWM duty cycle limit such that when the outputted PWM duty cycle greater than the PWM duty cycle limit, the outputted PWM duty cycle is set to the PWM duty cycle limit. A method, in a DC motor, of preventing a current surge during severe voltage changes is also disclosed.

Abstract: An air induction system for an internal combustion engine utilizes localized heat generation to produce a desired acoustic profile that attenuates noise propagated through the air induction system. The noise propagated through the air induction system varies over time to form a variable noise profile. A heat generating mechanism, such as a laser array or electric spark generator, produces a predetermined amount of heat within a localized area adjacent to an inlet to the air duct housing. The predetermined amount of heat is an amount of heat sufficient to produce a desired acoustic energy as a result of rapid air expansion at the localized area. A controller varies the predetermined amount of heat over time to produce a desired acoustic profile that cancels the variable noise profile.