Power Switching Circuit for Lighting Device
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Solution Overview
Problem
Existing lighting devices experience instability due to reverse electric current flow from low priority power supplies to high priority power supplies when switching between utility power and battery power, causing operational issues.
Innovation Solution
A power switching circuit with a series of power input circuits and switch control circuits that prioritize power sources, ensuring that when a high priority power supply is connected, the switch control circuit turns off lower priority circuits to prevent reverse current flow, using PMOSFET switch tubes and diodes to manage voltage and current flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power switching circuit allows multiple power supplies to be electrically connected simultaneously, then the lighting device can flexibly switch between different power sources, but reverse electric current flow occurs from low priority power supplies to high priority power supplies causing operational instability
Solution Approach 1:
The control circuit proactively detects the presence of high priority power supplies before allowing low priority power supplies to connect to the light source. When a high priority power supply is detected, the control circuit preemptively disables the output to that light source, preventing reverse current flow before it can occur. This preliminary action ensures that adaptability is maintained while reliability is protected.
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the power switching circuit and the light source. This intermediary component monitors the status of all power supplies and actively manages current flow by enabling or disabling output paths. The control circuit acts as a mediator that resolves the conflict between allowing flexible power source switching and preventing harmful reverse current flow.
2Device complexity
If the power switching circuit uses simple switching mechanisms, then the device complexity is reduced, but it cannot effectively prevent reverse current flow and ensure stable operation
Solution Approach 1:
The control circuit monitors voltage parameters from different power supplies and uses these parameter changes to determine which power sources are present and active. By detecting voltage levels and changes, the control circuit intelligently manages the switching between power sources without requiring complex mechanical switches or additional protective components, thus maintaining simplicity while ensuring reliable reverse current prevention.
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 stabilizes the lighting device by preventing reverse current flow, ensuring reliable operation by maintaining the priority of power sources and optimizing power distribution, thus enhancing the device's stability and efficiency.
Implementation Method 1
the switch assembly comprises two PMOSFET switch tubes (Q4n−1, Q4n) in a conducting state
Implementation Method 2
first diodes (DS((n−1)(n−2)+2)/2 to DSn(n−1)/2) are connected in series between the gates of the PMOSFET switch tubes
Data Source
AI summary
A lighting device includes a light source and a power switching circuit including a plurality of power input circuits. Each of the power input circuits includes a power input terminal and a switch control circuit connected in series between the power input terminal and the light source. A control terminal of Nth switch control circuit controls the Nth switch control circuit to be turned off according to a first electrical signal input by first to (N-1)th power input terminals. The control terminal of the Nth switch control circuit controls the Nth switch control circuit to be turned on according to a second electrical signal being input by Nth power input terminal, and controls the first to (N-1)th switch control circuits to be turned off. The N is a positive integer greater than 1. A power switching circuit is also provided.