Lighting Power Converter Circuit With AC-Tracking Standby Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED illumination devices face challenges in efficiently managing power conversion and minimizing electromagnetic interference (EMI) while maintaining optimal performance across varying output powers and AC line voltages.
Innovation Solution
The implementation of a power converter circuit with a semiconductor switch, a bus capacitor, and a control circuit that adjusts the minimum operating period of the drive signal based on output power levels and time, along with a comparator to generate a sinusoidal input current during standby mode, helps in optimizing power factor correction and reducing EMI by varying the threshold voltage in response to AC line voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the power converter circuit operates with a fixed minimum operating period, then the control is simple, but the electromagnetic interference increases and power factor correction is suboptimal at varying output powers
Solution Approach 1:
The patent applies dynamics by making the minimum operating period variable rather than fixed. The control circuit adjusts the minimum operating period based on output power levels and temporal patterns, transforming a static parameter into a dynamic one that adapts to operating conditions. This resolves the contradiction by enabling EMI reduction through frequency spreading without requiring overly complex control mechanisms.
Solution Approach 2:
The patent changes the parameter of minimum operating period from a constant value to a variable parameter that changes with output power and time. By modifying this key parameter dynamically, the system achieves better power factor correction and reduced EMI while maintaining reasonable control complexity through structured adjustment rules.
2Stability of the object's composition
If the power converter circuit uses a fixed threshold voltage, then the circuit operation is stable, but the input current is not sinusoidal and power factor is suboptimal during standby mode
Solution Approach 1:
The patent makes the threshold voltage dynamic by adjusting it according to the instantaneous AC line voltage during standby mode. This transforms a static threshold into a dynamic one that tracks the AC voltage waveform, enabling sinusoidal input current and improved power factor while maintaining operational stability through controlled adaptation.
Solution Approach 2:
The control circuit uses feedback from the AC line voltage to dynamically adjust the threshold voltage. By continuously monitoring the instantaneous AC voltage and responding with appropriate threshold adjustments, the system achieves sinusoidal input current and optimal power factor during standby operation while preserving stability.
3Reliability
If the power converter circuit operates continuously in standby mode, then the bus voltage is maintained, but the power consumption increases
Solution Approach 1:
The patent implements periodic action by enabling the power converter circuit to operate in intermittent cycles during standby mode rather than continuously. The control circuit activates the converter periodically to recharge the bus capacitor, then allows it to discharge, creating a cyclic operation pattern that maintains bus voltage within acceptable ranges while significantly reducing average power consumption.
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 enhances the efficiency of LED illumination devices by optimizing power conversion, reducing EMI, and minimizing power consumption during standby mode, ensuring consistent performance and reduced electromagnetic interference across different operating conditions.
Implementation Method 1
a bus capacitor configured to store the bus voltage, a semiconductor switch configured to be rendered conductive and non-conductive to charge the bus capacitor
Implementation Method 2
a sense resistor coupled in series with the semiconductor switch and configured to generate a sense voltage having a magnitude that indicates a magnitude of current conducted through the semiconductor switch
Data Source
AI summary
A power converter circuit may include a control circuit configured to generate a drive signal for rendering a semiconductor switch conductive and non-conductive to generate a bus voltage across a bus capacitor. The control circuit may adjust a minimum operating period of the drive signal to a first value when an output power of the power converter circuit is greater than a first threshold and to a second value when the output power is less than a second threshold. The control circuit may comprise a comparator that generates the drive signal in response to a sense voltage and a threshold voltage. When operating in a standby mode, the control circuit may adjust a magnitude of the threshold voltage based on an instantaneous magnitude of an alternating-current line voltage received by the power converter circuit, such that an input current drawn by the power converter circuit is sinusoidal.