Constant Current Driver PWM Charging for LED Reliability
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Solution Overview
Problem
LED drivers require constant current to maintain efficiency, but applying constant voltage leads to increased temperature and current draw, potentially damaging the LED, and existing solutions do not efficiently manage current distribution between the LED and energy storage units.
Innovation Solution
A functional device with a constant current driver, electrical energy storage unit, and control unit that uses pulse width modulation (PWM) to charge the energy storage unit during off periods and supply current to the functional unit during on periods, reducing the overall current supply and idle periods of the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If constant voltage is applied to the LED, then the LED can operate continuously, but the temperature increases and forward voltage decreases causing excessive current draw that may destroy the LED
Solution Approach 1:
The patent applies periodic action by switching between charging the energy storage unit during off-periods and supplying current to the functional unit during on-periods of a PWM signal. This periodic alternation allows the constant current driver to rest during charging phases, reducing thermal accumulation and current stress on the LED while maintaining continuous overall operation through the energy storage buffer.
2Duration of action of stationary object
If the constant current driver supplies current continuously to the functional unit, then the functional unit operates continuously, but the driver requires high current supply capacity and has idle periods reducing efficiency
Solution Approach 1:
The patent implements preliminary action by charging the energy storage unit during off-periods before the functional unit needs current. This advance charging allows the driver to supply current during on-periods without requiring peak current capacity, as the energy storage unit acts as a buffer that was prepared in advance. The driver operates at lower average current while maintaining continuous functional unit operation.
3Use of energy by stationary object
If the constant current driver operates during idle periods, then it can charge the energy storage unit, but the driver efficiency decreases during these non-productive periods
Solution Approach 1:
The patent applies dynamics by making the driver's operational state variable rather than static. The driver dynamically switches between two modes: charging the energy storage unit during off-periods and supplying current to the functional unit during on-periods. This dynamic operation eliminates idle periods where the driver would consume power without productive output, as every period is dedicated to a useful function, thereby improving overall efficiency.
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
This configuration allows for a lower current supply and improved efficiency by alternating current distribution between the functional unit and energy storage unit, reducing electromagnetic interference and increasing the mean time between failures while enabling demand response and cost reductions.
Implementation Method 1
an electrical energy storage unit configured for storing electrical energy
Data Source
AI summary
The present invention relates to a functional device (10) powered by a constant current driver (12). The device (10) comprises constant current driver (12), electrical energy storage unit (14), functional unit (16), and control unit (18). The device (10) is controlled by the control unit (18) such that the constant current driver (12) provides a constant current to the functional unit (16) and the storage unit (14) in dependence of a pulse width modulated voltage signal. Current is provided to the storage unit (14) for charging the storage unit (14) during at least part of off periods of the pulse width modulated voltage signal. During on periods of the pulse width modulated voltage signal, current is provided to the functional unit (16) and no current is provided to the storage unit (14). This allows providing the device with a constant current driver with less idle periods and lower current supply.