AC Direct LED Driver with Capacitor and Current Controller
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Solution Overview
Problem
AC-direct linear LED driving methods face issues with current deviation, flicker, high inrush current, low power factor, and high total harmonic distortion, limiting their applicability and compliance with stringent flicker regulations, especially when using capacitors for power storage.
Innovation Solution
An AC-direct LED driving apparatus incorporating a rectifier, an LED, a capacitor for alternating charging and discharging, and MOSFET-based current drivers with diodes and operational amplifiers to manage current paths and voltage levels, ensuring efficient power delivery and minimizing flicker while maintaining high power factor and low harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capacitor is connected to the input terminal to decrease flicker, then flicker characteristics are improved, but inrush current increases and power factor decreases
Solution Approach 1:
The patent introduces a current controller as an intermediary device between the capacitor and the LED. This controller actively manages the charging current of the capacitor, preventing excessive inrush current while maintaining the capacitor's ability to reduce flicker. The current controller mediates between the power source, capacitor, and LED, optimizing both flicker reduction and power factor performance.
Solution Approach 2:
The patent dynamically adjusts the charging parameters of the capacitor through the current controller. By changing the charging current limits and timing parameters, the system optimizes the capacitor's operation to reduce flicker while minimizing the impact on power factor and inrush current characteristics.
2Object-affected harmful factors
If a capacitor is connected to the input terminal to decrease flicker, then flicker characteristics are improved, but device complexity increases
Solution Approach 1:
The current controller performs multiple functions: it limits inrush current, controls capacitor charging, and works with the rectifier to maintain power factor. By making the current controller a multi-functional component, the patent reduces the need for separate dedicated circuits for each function, thereby managing device complexity while achieving flicker reduction.
3Device complexity
If AC voltage is directly used without converter or capacitor, then system simplicity is maintained, but flicker characteristics worsen with 100% percentage flicker
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during specific phases of the AC cycle and using the stored energy to maintain LED current during voltage dips. The current controller prepares the capacitor in advance to counteract upcoming voltage variations, thereby reducing flicker while maintaining a relatively simple system architecture.
4Device complexity
If sequential driving method is used, then circuit simplicity is maintained, but current deviation between channels increases
Solution Approach 1:
The current controller implements feedback mechanisms to monitor and adjust the current distribution across multiple LED channels. By detecting current deviations and dynamically adjusting the charging/discharging of the capacitor, the system maintains uniform current across channels while preserving the simplicity of the sequential driving architecture.
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 solution effectively reduces flicker, decreases overcharged currents, and achieves high efficiency and power factor, while simplifying the system and reducing production costs, making it compliant with future flicker regulations without using inductors or transformers.
Implementation Method 1
a capacitor (C) connected to a first terminal of the LED, and configured to drive the LED while alternating between charging and discharging sections according to a preset cycle
Implementation Method 2
a rectifier configured to receive and rectify an alternating current (AC) voltage
Implementation Method 3
an LED configured to emit light based on a rectified voltage received from the rectifier
Data Source
AI summary
Disclosed herein is a AC direct LED driving apparatus. The light emitting diode (LED) driving apparatus includes: a rectifier configured to receive and rectify an alternating current (AC) voltage; an LED configured to emit light based on a rectified voltage received from the rectifier; a capacitor connected to a first terminal of the LED, and configured to drive the LED while alternating between charging and discharging sections according to a preset cycle; a first current driver connected to a second terminal of the LED and configured to control a path of current flowing in the LED and the capacitor based on different input voltage levels; a second current driver configured to control charging and discharging of the capacitor; and a first diode connected onto a current path of the capacitor and the second current driver, and configured to form a discharging path for driving the LED based on a charged voltage of the capacitor.