Electricity: motor control systems – Closed loop speed control system for dc motor with commutator
Reexamination Certificate
2006-07-11
2006-07-11
Duda, Rina (Department: 2837)
Electricity: motor control systems
Closed loop speed control system for dc motor with commutator
C388S804000, C388S811000, C318S599000, C318S811000, C318S432000
Reexamination Certificate
active
07076159
ABSTRACT:
A system and method for measuring the speed of a fan in an electrical system is presented. The duty cycle of a pulse width modulated (PWM) signal provided by a signal generator may control the speed of the fan. The fan may generate tachometer pulses that may be used by a tachometer reading-unit to monitor the RPM of the fan. Very low frequency test (VLFT) pulses may be generated and provided through a sampling signal multiplexed with the PWM signal to sample the fan generated tachometer pulses even when the PWM signal is low. The frequency of the sampling signal may be determined based on the duty cycle of the PWM signal and may be dynamically updated when the duty cycle of the PWM signal is updated. The sampling signal may be used as the clock input to a flip-flop with the tachometer pulses as the data input, and the output of the flip-flop providing an input to a pulse counter that counts the number of pulses within a determined period of time, providing as its output the measured RPM of the fan.
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Duda Rina
Hood Jeffrey C.
Meyertons Hood Kivlin Kowert & Goetzel P.C.
Standard Microsystems Corporation
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