Lighting Power Converter Timing Control for Efficiency and EMI
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Solution Overview
Problem
Existing LED illumination devices struggle to efficiently regulate power and adjust operating periods to optimize performance across varying output powers, leading to inefficiencies and potential electromagnetic interference.
Innovation Solution
A lighting device with a power converter circuit and load regulation circuit that adjusts the minimum operating period of a semiconductor switch based on output power levels, using a control circuit to generate a drive signal and limit the operating period, while also operating in a standby mode to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the operating period of the semiconductor switch is reduced to increase switching frequency, then power conversion efficiency improves, but electromagnetic interference increases
Solution Approach 1:
The patent implements dynamic adjustment of the minimum operating period based on output power levels. The control circuit modifies the operating period parameter in real-time according to the actual power output requirements, allowing the system to optimize between efficiency and EMI characteristics under different operating conditions rather than using a fixed parameter
Solution Approach 2:
The patent changes the operating period parameter dynamically based on output power thresholds. When output power exceeds a first threshold, the minimum operating period is set to a first value; when output power is below a second threshold, it is set to a second value. This parameter adaptation resolves the contradiction by selecting appropriate operating period values for different power levels
2Stability of the object's composition
If the semiconductor switch operates continuously to maintain stable power output, then power stability improves, but power consumption during standby increases
Solution Approach 1:
The patent implements periodic operation of the semiconductor switch by defining a minimum operating period that creates intentional off-time intervals. This periodic action allows the switch to remain stable when needed while consuming less power during standby periods, resolving the contradiction between continuous operation stability and standby power consumption
Solution Approach 2:
The system dynamically adjusts the operating period based on power demands. During high power output, the minimum operating period ensures stable power delivery; during low power or standby conditions, the operating period allows for reduced activity and lower power consumption, adapting to real-time requirements
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 enables efficient power regulation and reduced electromagnetic interference by dynamically adjusting the minimum operating period in response to output power changes, while also minimizing power consumption in standby mode.
Implementation Method 1
a bus capacitor configured to store the bus voltage
Implementation Method 2
a semiconductor switch configured to be rendered conductive and non-conductive to charge the bus capacitor
Implementation Method 3
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.