Dimming Apparatus Control Circuit Suppressing Voltage Spikes
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Solution Overview
Problem
Conventional Phase-controlled dimmers experience voltage spikes when used with inductive loads due to self-inductive reactions, potentially damaging light fixtures or other equipment, and existing solutions either increase power consumption or are limited to smaller inductive loads.
Innovation Solution
A control circuit and method for a dimming apparatus that outputs turn-off signals for field effect transistors before current zero-crossing points during AC power supply half-cycles, allowing current to flow through body diodes and suppressing voltage spikes by managing self-inductance energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Phase-controlled dimmers are used with inductive loads, then the dimming function is achieved, but voltage spikes are generated due to self-inductive reactions that may damage light fixtures or equipment
Solution Approach 1:
The control circuit generates turn-off signals for the field effect transistors before the current reaches the zero-crossing point during AC power supply half-cycles. This preliminary action allows the current to naturally decay through body diodes before the switching event, preventing voltage spikes caused by abrupt current interruption in inductive loads.
Solution Approach 2:
The patent utilizes the body diodes of the field effect transistors to provide a safe current path during the turn-off transition. By allowing current to flow through these inherent diodes before complete switch-off, the circuit converts what would be harmful inductive kickback into a controlled current path, eliminating voltage spikes while maintaining dimming functionality.
2Reliability
If existing solutions are implemented to prevent voltage spikes, then system stability is improved, but power consumption increases or the solutions are limited to smaller inductive loads
Solution Approach 1:
The control circuit utilizes the inherent body diodes of the field effect transistors as part of the voltage spike protection mechanism. By designing the control strategy to leverage these built-in components rather than adding external protection circuits, the solution achieves reliable voltage spike prevention without increasing power consumption or requiring additional active components.
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
Effectively prevents damage from peak voltages when connecting the dimming apparatus to inductive loads, ensuring system stability and security while maintaining low power consumption and easy operation.
Implementation Method 1
output a first turn-off signal during a negative half-cycle of a waveform output by a main AC power supply of a load circuit to turn off the first field effect transistor at a predetermined time before a first current zero-crossing point, to cause current to flow from a body diode of the first field effect transistor
Data Source
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AI summary
Embodiments of the disclosure provide a control circuit and method for a dimming apparatus and a dimming apparatus. The control circuit includes: a dimming signal transmission circuit configured to be coupled to gates of a first field effect transistor and a second field effect transistor of the dimming apparatus; a first turn-off signal part coupled to the gate of the first field effect transistor and adapted to output a first turn-off signal to turn off the first field effect transistor at a predetermined time before a first current zero-crossing point; and a second turn-off signal part coupled to the gate of the second field effect transistor and adapted to turn off the second field effect transistor at the predetermined time before a second current zero-crossing point.