Microprocessor Load Control Device Low-Power Mode
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Solution Overview
Problem
Conventional two-wire dimmers face limitations in controlling the power supply and semiconductor switch conduction time due to the need for a cat-ear power supply that requires significant off-time to ensure charging, constraining maximum light intensity and dimming range, and often necessitate additional components like ADCs for monitoring.
Innovation Solution
A microprocessor-controlled load control device with a cat-ear power supply that draws current through the lighting load, allowing direct control of the power supply and semiconductor switch conduction time without the need for an ADC or complex hardware comparison circuits, using a bridge rectifier and passive/active charging circuits to optimize charging and reduce component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor switch is kept non-conductive for sufficient off-time to allow the cat-ear power supply to charge, then the power supply can maintain stable DC voltage, but the maximum light intensity and dimming range are constrained
Solution Approach 1:
The patent implements dynamic control of the semiconductor switch conduction time based on real-time monitoring of the power supply voltage. The microprocessor adjusts the off-time duration adaptively - extending it when voltage drops below threshold and reducing it when voltage is sufficient - thereby optimizing both power supply stability and dimming range under varying load conditions
Solution Approach 2:
The patent employs a feedback mechanism where the microprocessor continuously monitors the DC voltage output of the cat-ear power supply and uses this information to regulate the semiconductor switch operation. This closed-loop control ensures the power supply receives adequate charging time while maximizing the dimming range by adjusting conduction time based on actual power supply status
2Measurement precision
If additional components like ADCs and complex hardware comparison circuits are added to monitor and control the power supply, then precise control of conduction time is achieved, but device complexity and cost increase
Solution Approach 1:
The patent utilizes the microprocessor's existing analog input capability to directly monitor the power supply voltage without requiring dedicated ADC hardware or complex comparison circuits. The microprocessor itself performs the monitoring and control functions, leveraging its built-in resources to simplify the overall circuit design while maintaining precise control
Solution Approach 2:
The patent employs the microprocessor for multiple functions: user interface control, LED indicator driving, zero-crossing detection, and power supply voltage monitoring. This multi-functional approach eliminates the need for separate dedicated monitoring circuits, reducing component count and system complexity while achieving precise conduction time control
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
Enables increased dimming range and higher light intensity by dynamically controlling the power supply and semiconductor switch operation, reducing component size and cost while maintaining stable power delivery.
Implementation Method 1
a bridge rectifier and passive/active charging circuits to optimize charging
Implementation Method 2
generating a DC voltage across an energy storage capacitor for powering the microprocessor
Data Source
AI summary
A load control device for control of the power delivered from an AC power source to an electrical load comprises a power supply and a microprocessor that is able to operate the load control device in a low-power mode. The load control device may further comprise at least one visual indicator controlled by the microprocessor to provide visual feedback, where the microprocessor illuminates the visual indicator when the load is on and to turns the visual indicator off when the load is off during the low-power mode. The load control device may comprise a communication circuit coupled to the microprocessor for transmitting and/or receiving digital messages the microprocessor cause the communication circuit to draw less current from the power supply during the low-power mode. The microprocessor may operate in the low-power mode if the magnitude of a voltage of the power supply drops below a predetermined threshold.