Osram Sylvania Inc.

University of Texas System

Ranjit Jayabalan

Nitin Kumar

Andrew Johnsen

Jinsheng Wei

Christian Breuer

Babak Fahimi

Nagaraja Chikkegowda

An active damping circuit is disclosed, which includes a peak current limiter, a drain source voltage limiter, a turn-on driver, a resistor shunt circuit, and a peak current sensor. The peak current sensor detects a rising edge of an input voltage from a phase cut dimmer by detecting a higher peak current. This drives a collector voltage of a second transistor of the peak current limiter low, which lowers a gate voltage of a first transistor of the peak current sensor, and forces it into a linear operating region, so it functions as a damping resistor. When the peak current sensor detects a decreased peak current, such that the turn-on edge of the input voltage is passed, the second transistor turns off, and the turn-on driver turns the first transistor on, such that the active damping circuit is waiting for a next edge of the input voltage.

Active damping circuit

An active damping circuit and system including the same are disclosed. The active damping circuit includes a first resistor, a second resistor, a third resistor, a first transistor, a second transistor, a capacitor, and a microcontroller. The first resistor is connected to a base of the first transistor, and to the microcontroller output. The second resistor is connected to a positive voltage, and to a collector of the first transistor and a gate of the second transistor. The third resistor is connected to a logic ground, and to a source of the second transistor. The capacitor is connected to the collector of the first transistor, the second resistor, and the gate of the second transistor. A drain of the second transistor, and the first capacitor, and the second capacitor, and the microcontroller output, are also connected to the logic ground. An emitter of the first transistor is connected to ground.

Systems and methods to change a light output level using adaptive frequency control are provided. A switched mode power converter is configured to switch output current to a light emitting diode (LED) module, which includes an LED lighting element, at a switching frequency. Control circuitry is configured to receive a dimming control input that corresponding to a desired light output level of the LED module. The control circuitry is also configured to provide a pulse width modulation (PWM) output configured to pulse width modulate the output current, the PWM output having a pulse width, a PWM frequency, and a PWM period corresponding to the PWM frequency. The control circuitry is also configured to adjust at least one of the PWM period and the switching period in response to a change in the dimming control input, such that a light output level of the LED module is appropriately changed.

Adaptive frequency control to change a light output level

As described herein is a vehicle, system, method and device for monitoring, detecting and diagnosis of one or more faults in single- or multi-converter power system. Through use of existing devices within the power system, particularly semiconductor devices, output parameters may be monitored for deviations from normal operation. In addition, faults may be detected and/or diagnosed within the failure withstand time of the existing device.

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Danvers, MA, United States of America

Ranjit Jayabalan