Dual Mode LED Retrofit Circuit for ANSI Ballast Compliance
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Solution Overview
Problem
Existing lamp technologies fail to provide compatibility with market ballasts, particularly when retrofit LED lamps replace fluorescent or HID lamps, leading to increased current and power consumption, and compatibility issues due to differences in power levels and impedance.
Innovation Solution
A dual mode circuit for LED lamps that operates with both low and high frequency current waveforms, utilizing a thevenin equivalent circuit and capacitors to simulate cathode heaters, allowing the LED lamp to function as a constant voltage source and maintain compatibility with ANSI reference ballasts, while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a low voltage LED retrofit lamp is connected to an ANSI reference ballast, then the lamp operates at lower voltage and consumes less power, but the input current increases and violates UL ANSI ballast requirements
Solution Approach 1:
The patent introduces an intermediary compliance circuit between the LED lamp and the ballast. This circuit includes a capacitor connected in series with the LED string, which acts as a mediator to limit the input current drawn from the ballast. The capacitor blocks DC current while allowing AC power to pass, thereby reducing the RMS current to levels that satisfy UL ANSI requirements while still enabling the LED lamp to operate at low voltage and consume reduced power.
2Reliability
If a capacitive coupling is added between the retrofit lamp and ballast to throttle back current, then the reactive component of lamp impedance increases, but this creates compatibility issues with ballasts operating at lower frequencies due to higher impedance
Solution Approach 1:
The patent employs a dynamic circuit configuration where the capacitor's reactance is designed to be frequency-dependent. At typical ballast operating frequencies (50-60 Hz), the capacitor presents sufficient reactance to limit current while maintaining compatibility. The circuit is designed to adapt to different ballast frequencies by utilizing the frequency-dependent impedance of the capacitor, allowing the same circuit to work across a range of ballast types without requiring adjustment.
3Device complexity
If a simple reactive circuit is used to increase compatibility, then the circuit is simple, but it cannot achieve high compatibility with the large variety and age of ballasts
Solution Approach 1:
The patent utilizes parameter changes by selecting specific capacitor values and circuit configurations that optimize performance across different ballast types. The capacitor is designed with specific reactance characteristics that work across a wide frequency range. By carefully choosing component parameters (capacitance value, voltage rating) and circuit topology, the circuit achieves broad compatibility with ballasts from different eras and manufacturers without requiring complex switching or adjustment mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The dual mode circuit enables maximum compatibility with existing ballasts, satisfies UL requirements, and reduces power consumption without compromising illumination, effectively replacing fluorescent and HID lamps.
Implementation Method 1
a capacitor connected in series with the LED string... the capacitor blocks DC current while allowing AC power to pass
Implementation Method 2
LEDs... transformation of electrical energy into visible electromagnetic radiation
Data Source
AI summary
An embodiment of the present invention provides a retrofit LED lamp that is operated by a dual mode circuit, enabling maximum compatibility with the ANSI reference ballasts to satisfy UL requirements to replace HID and fluorescent lamps. The LED lamp operates at two different modes, offered by the dual mode PCB circuit. In one of the mode, namely ANSI ballast testing, a low frequency current from the ballast is throttled through a bypass circuit to LEDs, since a field effect transistor of the circuit is in open circuit mode due to insufficient current. During the second mode, namely field ballast operation, a high frequency current is provided by the ballast, which short circuits the FET, causing it to conduct and thus operating the LEDs. Advantageously, the LED lamp offers maximum compatibility with ballasts using such dual mode circuit and consumes less power.