Dimmer Load Detection via Asymmetric Phase Drive
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Solution Overview
Problem
Existing dimmer technologies face challenges in automatically detecting load types without adding excessive circuit components and subjecting the dimmer to overvoltage spikes, which can cause damage.
Innovation Solution
A dimmer circuit with a controller and current sensor that generates asymmetric forward phase transistor drive signals to incrementally adjust dimming levels, allowing the controller to determine load type based on current parameters without forcing overvoltage events, thereby selecting the appropriate dimming mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If traditional voltage peak detection circuitry is added to automatically detect load type, then load detection capability is improved, but device complexity and size increase due to additional large components
Solution Approach 1:
The patent combines the load detection function with the existing current sensor already present in the dimmer circuit. Instead of adding separate voltage peak detection circuitry, the system uses the existing current sensor to measure current levels during dimming operation, thereby integrating detection functionality into existing components and avoiding additional hardware.
Solution Approach 2:
The dimmer system performs self-detection of load type by monitoring its own current consumption patterns during dimming operation. The controller analyzes current levels drawn by the connected load to automatically determine whether it is inductive or non-inductive, eliminating the need for external detection devices.
2Measurement precision
If overvoltage events are forced to detect inductive loads, then detection accuracy is improved, but reliability decreases due to potential dimmer circuit damage
Solution Approach 1:
Instead of forcing harmful overvoltage events to detect inductive loads, the patent converts the naturally occurring current draw characteristics of inductive loads into a beneficial detection mechanism. By monitoring current levels during normal dimming operation, the system identifies inductive loads through their inherent current patterns without subjecting the circuit to damaging voltage spikes.
Solution Approach 2:
The system performs preliminary detection of load type by monitoring current levels during the dimming-up phase before full power is applied. This allows the controller to identify inductive loads early in the operation and switch to appropriate dimming mode, preventing potential damage that could occur with reverse-phase dimming of inductive loads.
Data Source
AI summary
A dimmer circuit for detecting a connected load type comprising a controller, a plurality of dimming transistors adapted to provide a dimmed hot output signal to a load, and a current sensor adapted to sense current levels of the dimmed hot output signal. The controller is adapted to store at least one load type current parameter associated with a dimming mode. The controller is further adapted to generate an asymmetric forward phase transistor drive signal with half cycles of one polarity having incrementally increasing dimming levels to drive the plurality of dimming transistors. The controller receives current levels from the current sensor and determines whether at least one of the received current levels satisfies at least one stored current parameter. When at least one current level satisfies at least one current parameter, the controller sets the dimmer to operate in a dimming mode associated with the satisfied current parameter. When the received current levels do not satisfy the stored at least one load type current parameter, the controller sets the dimmer to operate in a default dimming mode. The at least one current parameter may define one or more current events associated with a load type, such as an inrushing current event, double peaked current event, a lagging current event, or a substantially non-ratiometric current rise.