LED Load Control Circuit for AC/DC Input Loss Reduction
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Solution Overview
Problem
The transition to DC power distribution from renewable energy sources, such as photovoltaic solar power, introduces efficiency losses due to the need for rectification and active power factor correction when converting AC power to DC for use in electrical loads.
Innovation Solution
A load control device that includes a power converter, load regulation circuit, and control circuit capable of operating in both AC and DC modes, with a controllable switching circuit and rectifier circuit that adjusts bus voltage based on power requirements, disabling the power converter in DC mode when power is below a threshold to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rectification and active power factor correction are used to convert AC power to DC for electrical loads, then DC power can be provided to electrical loads, but efficiency losses occur
Solution Approach 1:
The power converter dynamically adapts its operation based on input voltage type (AC or DC) and load power requirements. The control circuit adjusts the duty cycle and switching frequency to optimize efficiency for each operating condition, eliminating the need for fixed rectification and PFC circuits that cause energy losses.
Solution Approach 2:
The system changes operating parameters (switching frequency, duty cycle, bus voltage level) based on input voltage type and load conditions. When DC input is detected, the rectification and PFC operations are bypassed, and the power converter operates in a more efficient mode with adjusted parameters to match the DC input characteristics.
2Reliability
If the power converter operates continuously in DC mode, then power delivery is maintained, but power losses increase when power requirements are low
Solution Approach 1:
The power converter operates at partial capacity only when necessary. The control circuit monitors load power requirements and adjusts the converter operation accordingly, reducing or disabling conversion operations when load power is below a threshold, thereby eliminating unnecessary energy losses during low-power conditions.
Solution Approach 2:
The system uses periodic monitoring of load power requirements to determine when to activate or deactivate the power converter. This on-demand operation pattern ensures the converter runs only when power delivery is needed, reducing continuous operation losses while maintaining reliable power supply when required.
3Power
If the bus voltage is maintained at a high level, then power delivery capability is sufficient for high-power loads, but efficiency decreases when load power requirements are low
Solution Approach 1:
The bus voltage is dynamically adjusted based on real-time load power requirements. The control circuit modulates the power converter to maintain an optimal bus voltage level that matches the current load demands, preventing the energy losses associated with maintaining high bus voltage when low power is required.
Solution Approach 2:
The system changes the bus voltage parameter according to load conditions. During low-power operation, the bus voltage is reduced to minimize losses, while during high-power operation, the bus voltage is increased to provide sufficient power delivery capability. This adaptive parameter adjustment optimizes efficiency across different operating conditions.
Data Source
AI summary
A load control device for controlling power delivered from a power source to an electrical load may comprise a control circuit configured to control the load regulation circuit to control the power delivered to the electrical load. The control circuit may be configured to operate in an AC mode when an input voltage is an AC voltage and in a DC mode when the input voltage is a DC voltage. The control circuit may be configured to disable the power converter in the DC mode. The control circuit may be configured to render a controllable switching circuit conductive in the AC mode, and non-conductive in the DC mode. The rectifier circuit may be configured to rectify the input voltage to generate a rectified voltage when the input voltage is an AC voltage, and to pass through the input voltage when the input voltage is a DC voltage.