Universal Lighting Technologies, Inc.

Other

Panasonic Corporation

Universal Douglas Lighting America

Wei Xiong

Christopher Radzinski

Candice Ungacta

Danny Pugh

Keith Davis

Travis L Berry

Donald Folker

Dane Sutherland

John Jay Dernovsek

Scott Price

Mike LeBlanc

Stephen D Mays, Ii

Thomas Lunn

Thomas M Poehlman

Rohan Dayal

John Cavacuiti

Rob Mahaffey

John Helms

Theodore E Kluska

Haiqing (Paul) Yang

Takeshi Goriki

Brandon Dyer

Haiqing Yang

Levi Shareck

Mark Arias

John J Dernovsek, Ii

A two-stage driver supplies current to an LED load. A first stage of the driver generates a bulk voltage. A second stage has a flyback transformer with a primary winding and a secondary winding. The second stage generates an output voltage to cause LED load current. The primary winding is turned on and off by a gating signal. Control logic within the second stage is responsive to initially turning on the driver to perform a startup short circuit test of the output circuit by applying a gating signal with a short on-time and a low switching frequency. If the output circuit is not shorted, the control logic increases the on-time and the switching frequency to detect if an output current is excessive. If the output current is not excessive, the control logic adjusts the on-time and the frequency to provide sufficient current to illuminate the LED load.

Startup current control method for flyback converter

A two-stage driver supplies current to a light emitting diode (LED) load. The driver includes a first stage and a second stage. The first stage has a first flyback converter. The first stage is configured to receive a non-regulated voltage input and to generate a substantially constant bulk voltage across a first-stage output filter capacitor. The second stage has a second flyback converter. The second stage is configured to receive the bulk voltage from the first stage. The second stage is further configured to generate a desired current through the LED load. The second stage is electrically isolated from the first stage such that the LED load does not share a common ground reference with the non-regulated voltage input to the first stage. The driver further includes an auxiliary power supply coupled to an auxiliary winding of a transformer of the first flyback converter to generate an auxiliary voltage.

LED driver with auxiliary output and low standby power

A two-stage driver supplies current to a light emitting diode (LED) load. The two-stage driver includes a first stage and a second stage. The first stage has a first flyback converter. The first stage is configured to receive a non-regulated voltage input and to generate a substantially constant bulk voltage across a first-stage output filter capacitor. The second stage has a second flyback converter. The second stage is configured to receive the bulk voltage from the first stage. The second stage is further configured to generate a desired current through the LED load. The second stage is electrically isolated from the first stage such that the LED load does not share a common ground reference with the non-regulated voltage input to the first stage.

LED driver with double flyback technology

An edge mount magnetic component includes a bobbin and two E-core halves. The bobbin is configured to receive the two E-core halves when body portions of the two E-core halves are positioned vertically. The bobbin includes a first outer flange, a second outer flange, and a passageway spanning therebetween. The bobbin further includes first, second, third, and fourth pin supports. The first and second pin supports are connected to an outer surface of the first end flange and are spaced apart by at least a width of the passageway. The third and fourth pin supports are connected to an outer surface of the second end flange and are spaced apart by at least the width of the passageway. The bobbin further includes slots for routing a winding to a pin and includes walls to ensure the winding is electrically separated from the E-core halves.

Bobbin for edge-mounted magnetic core

A two-stage driver supplies current to a light emitting diode (LED) load. The driver includes a first stage and a second stage. The second stage is configured to generate a desired current through the LED load. The second stage has a flyback converter having a flyback transformer with a primary winding and a secondary winding. The primary winding is turned on and off by a gating signal. An induced voltage in the secondary winding rings when a current in the secondary winding is discharged. The flyback converter is configured to turn on the primary winding only during a detected valley in the ringing of the secondary winding. If the primary winding is turned on during a detected valley different from the previous detected valley, a valley jump is detected and the switching frequency is adjusted.

Dynamic valley sensing method for double flyback LED driver

A power converter and method for improving the current control stability of power converter by balancing the secondary winding currents is provided herein. The power converter includes a primary circuit having switches controllably driven at an operating frequency to produce an AC output through a primary transformer winding, and a secondary circuit having first and second secondary windings having respective leakage inductances. The secondary circuit provides power at an output node based on a power transfer between the primary winding and the first and second secondary windings. At least one balance inductor is coupled in series with the first and second secondary windings, and configured to reduce a difference between the first leakage inductance and the second leakage inductance. The at least one balance inductor may further be configured to reduce a difference between first and second AC current peaks associated with the first and second secondary windings, respectively.

Method to balance the secondary winding current to improve the current control stability

An LED driver for light modulation control includes a power converter circuit having a controller, a buffer circuit, and an energy recovery circuit. The controller is configured to selectively enable and disable both buffer control signals and gate drive signals depending on a sensed modulation control signal corresponding to a modulation-on stage and a modulation-off stage. In the modulation-on stage, the buffer control signals are enabled and the gate drive signals are disabled. In the modulation-off stage, the buffer control signals are disabled and the gate drive signals are enabled. The buffer circuit is configured for quick turn off of an LED load and for temporary storage of power from an output capacitor. The energy recovery circuit is configured to reuse the power stored in the buffer circuit before relying on an external power source to power the controller.

Constant current led driver with light output modulation

An LED driver for light modulation control includes a power converter circuit, a feedback circuit, a buffer circuit, an energy recovery circuit, and a controller. The power converter circuit is configured to provide an output current to an LED load coupled thereto. The feedback circuit is configured to generate an error signal which is fed back to the power converter circuit for maintaining the power converter circuit in a constant current output state. The buffer circuit is coupled to the LED load and configured for quick turn off of the LED load and for temporary storage of power. The energy recovery circuit is configured to reuse the power stored in the buffer circuit before relying on an external power source to power the controller and the feedback circuit. The controller is configured to control at least one aspect of each of the circuits of the LED driver.

Light modulating control method for dimming analog constant current LED driver

A power converter and method for providing surge protection to the power converter is provided herein. An over voltage protection portion of a protection circuit is coupled between the rail voltage and ground reference of the power converter, and senses a first magnitude of the rail voltage. An under voltage protection portion of the protection circuit is coupled to a controller of the power converter and further between the rail voltage and the ground reference, and senses a second magnitude of the rail voltage to be transmitted to the controller. A regulator block is coupled between the over voltage protection portion and the under voltage protection portion, and is configured to compare the first magnitude of the rail voltage to a reference voltage of the regulator block, and to short circuit the under voltage protection portion when the first magnitude of the rail voltage is greater than the reference voltage.

Combined high and low voltage protection circuit for half-bridge converter

A resonant power converter is disclosed with a method of limiting output current therefrom. A switch operating frequency is regulated to provide output current to a load, wherein an error signal corresponds to a difference between the output current and a reference value. The error value is fed back to switch operating frequency control circuit via an optocoupler. A maximum detector diode current for the optocoupler is clamped to a maximum value when the error signal exceeds or equals a clamping threshold value. The clamping threshold value may correspond to a maximum output current at a maximum normal operating temperature, wherein the method utilizes the relationship between ambient temperature and the current transfer ratio (CTR) for the optocoupler. The CTR decreases when the detector diode current is clamped, which decreases output current and output power, reducing power loss in the enclosure and relieving thermal stress at high temperatures.

Power supply and power clamping method at high ambient temperatures

An LED driver circuit includes a DC-to-AC inverter that provides a primary AC voltage to the input node of a resonant tank circuit. The resonant tank circuit includes a resonant tank circuit inductor, a resonant tank circuit capacitor and a primary winding of an output transformer. The resonant tank circuit capacitor and the primary winding are connected in parallel between a resonant tank circuit output node and a DC balance node. The DC balance node is coupled to a first bus by a first DC-blocking capacitor and is coupled to a second bus by a second DC-blocking capacitor. The output transformer has at least one secondary winding. An AC output voltage from the secondary winding is rectified to generate a DC voltage, which is applied to a load having a plurality of LEDs. The resonant tank circuit input node is clamped by first and second clamping diodes.

Clamped resonant tank with constant soft-switching and startup overshoot prevention

Circuitry and methods are provided for dynamically controlling the operating frequency of a resonant power converter. A feedback circuit generates error signals representing a difference between sensed output voltages and a constant target output voltage. A controller comprises a frequency control input terminal, and generates drive signals to half-bridge switching elements at determined operating frequencies. A frequency control circuit is coupled between the feedback circuit and the frequency control input terminal. The frequency control circuit sets minimum and maximum operating frequencies for the controller, and dynamically adjusts the operating frequency with respect to the constant target output voltage. A frequency control power supply circuit may further provide signals to the frequency control circuit representative of voltage across the resonant capacitor, wherein the minimum operating frequency is dependent thereon. The minimum frequency may be reduced with decreasing of the output voltage, and a maximum current may be reduced with increased overloading.

Dynamic overload protection method

A resonant power converter as disclosed herein, e.g., an LED driver, comprises first and second switches in a half-bridge arrangement and responsive at an operating frequency to controlled drive signals. A resonant circuit is coupled between the switch output and an isolation transformer. A negative feedback control loop provides an error signal for regulation of the output current. A reference control circuit is added to the feedback control loop, and configured to sense when the error signal exceeds a threshold value, and further configured in response to control a feedback reference signal wherein the error signal is reset to a value below the threshold value. By resetting the feedback control reference value, loop runaway may be prevented, e.g., for enough time that the LED load may warm up or otherwise stabilize. As a result the LED driver will always maintain negative current closed loop control, and restore normal operating mode.

Power control method during input line voltage fluctuation

A resonant power converter (e.g., LED driver) comprises a switching power stage having an operating frequency to produce output current through an LED load. A current sensor is coupled to the LED load, and a negative control means regulates the operating frequency based on error signals from the sensed current relative to a reference value. A reference control circuit controls the error signal (e.g., by manipulating the reference value) responsive to the error signal exceeding a reference error signal for regaining negative feedback control. The reference control circuit includes a quick discharge circuit for quickly reducing the error signal when it exceeds the reference error signal, and a slow charge circuit for slowly increasing the error signal when it is reduced, for example giving the LED load time to warm up in transition from a cold operational state to a normal operational state.

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Madison, AL, United States of America

Wei Xiong