LED Current Compensation Circuit for MOSFET Turn-On Delay
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Solution Overview
Problem
Existing LED light apparatuses driven by MOSFETs face a decrease in average driving current due to the time delay between the driving current reaching zero and the MOSFET's turn-on point, leading to inefficiencies in current control across varying input and output voltages.
Innovation Solution
A current compensation circuit that includes a current compensator to charge or discharge a capacitive element based on sensing voltage differences, delaying the turn-off point of the driving switching element until the charging and discharging quantities are equal, and a switching controller to provide control signals for optimal switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a real MOSFET is used to drive LED light apparatus, then the device can operate with practical components, but the turn-on delay causes the average driving current to decrease
Solution Approach 1:
The current compensator performs preliminary charging of the capacitive element during the period when the sensing voltage is below the reference voltage. This stored charge is then discharged during the MOSFET turn-on delay period, providing compensating current that offsets the current decrease caused by the delay, thereby maintaining the average driving current.
Solution Approach 2:
The error amplifier continuously compares the sensing voltage with the reference voltage and adjusts the charging/discharging current of the capacitive element accordingly. This feedback mechanism ensures that the compensation current dynamically adjusts to maintain the average driving current at the desired level despite MOSFET turn-on delays.
2Productivity
If the turn-off point of the driving switching element is delayed to compensate for MOSFET turn-on delay, then the average driving current is maintained, but the switching control becomes more complex
Solution Approach 1:
The capacitive element serves as an intermediary that stores and transfers charge to compensate for the MOSFET turn-on delay. By using this intermediate energy storage element, the system achieves average driving current maintenance without requiring complex real-time switching control adjustments, simplifying the overall control mechanism.
3Measurement precision
If the current compensator charges or discharges the capacitive element based on sensing voltage differences, then the average driving current is accurately controlled, but the circuit complexity increases
Solution Approach 1:
The error amplifier changes its output current parameter based on the voltage difference between the sensing voltage and reference voltage. When the sensing voltage is below the reference, the amplifier outputs a charging current; when above, it outputs a discharging current. This parameter change approach enables precise average driving current control using a relatively simple operational amplifier circuit.
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 solution ensures accurate control of the average driving current, preventing decreases caused by MOSFET turn-on delays and maintaining efficiency across changes in input and output voltages, utilizing an average current mode control method to operate LED light apparatuses effectively.
Implementation Method 1
a current compensator configured to perform a charging or a discharging of a capacitive element according to whether a sensing voltage is less than or greater than a certain voltage
Implementation Method 2
The error amplifier may amplify a difference between the sensing voltage and the certain voltage to charge or discharge the capacitive element based on an output of the error amplifier
Data Source
AI summary
The present disclosure relates to a circuit compensation circuit includes a current compensator configured to perform a charging or a discharging of a capacitive element according to whether a sensing voltage is less than or greater than a certain voltage and to delay a turn-off point of a driving switching element until a corresponding discharging quantity is identical to a corresponding charging quantity and a switching controller configured to provide a switching control signal at the delayed turn-off point of the driving switching element. The present disclosure also relates to a light emitting diode apparatus that includes such a current compensation circuit, and a related method of driving such a current compensation circuit