US Patent:
20060062291, Mar 23, 2006
Inventors:
Joseph Marotta - Boonton NJ, US
Donald Porawski - Cedar Grove NJ, US
International Classification:
H03K 7/08
Abstract:
Embodiments of the present invention provide a closed loop control system that is capable of handling a wide variety of loads. In some embodiments, the control system uses a pulse width modulated (PWM) signal to drive a plant. The PWM signal has a switching frequency. A feedback signal is measured from the plant and provided back to controller. The feedback signal may be converted into a digital feedback signal based on oversampling the feedback signal at a multiple, such as twice, of the switching frequency of the PWM signal. The digital feedback signal may then be filtered to reduce or remove any unwanted components. For example, the digital feedback signal may be passed through a notch filter that suppresses a range of frequencies centered around the switching frequency of the PWM signal. In addition, the digital feedback signal may be passed through a digital low pass filter. Based on the filtered digital feedback signal, the controller may then adjust the PWM signal delivered to the plant.