DALI Power Supply Dynamic Current Limiting
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Solution Overview
Problem
DALI bus power supplies face significant dynamic load changes due to varying numbers of connected devices, leading to voltage drops and potential light flicker, especially when only one device is connected, as the power supply must rapidly adjust between idle and communication currents.
Innovation Solution
A DALI device with an integrated power supply that includes a current controller, power source, and current limiter, allowing for adjustable communication current settings, either through user input or adaptive monitoring, to limit dynamic load shifts and maintain stable bus voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DALI power supply delivers maximum output current (e.g., 60mA) continuously, then sufficient current is available during communication times when the bus is short circuited, but the power supply experiences heavy dynamic load changes causing voltage drops and potential light flicker
Solution Approach 1:
The patent implements dynamic current limitation by adjusting the power supply output based on operational state. During idle times, the power supply delivers only the necessary idle current (e.g., 2mA per device) rather than maximum current, and during communication times, it dynamically increases to meet the short circuit current requirement. This dynamic adjustment prevents heavy load changes and maintains voltage stability while ensuring sufficient current availability when needed.
2Stability of the object's composition
If the DALI power supply delivers only idle current (e.g., 2mA) during idle times, then dynamic load changes are minimized, but insufficient current is available when a single device short circuits the bus during communication
Solution Approach 1:
The patent applies preliminary action by pre-configuring the power supply with current limitation circuitry that can rapidly respond to communication events. The system prepares by monitoring bus conditions and detecting when a device enters communication mode, then immediately adjusts the current output from idle level to the required communication level. This preliminary preparation ensures smooth transitions without voltage drops or flicker.
3Stability of the object's composition
If controller settings are adjusted very quickly to compensate for voltage drops, then light flicker is avoided, but the system becomes more complicated requiring different controller settings depending on output current and working point
Solution Approach 1:
The patent implements self-service through automatic current limitation and adaptive control mechanisms. The power supply system automatically detects its operating conditions (number of connected devices, communication state) and self-adjusts the output current accordingly without requiring manual controller reconfiguration. The system monitors bus voltage and current draw, then dynamically adjusts parameters to maintain stable operation, eliminating the need for complex manual tuning or multiple controller settings.
Data Source
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AI summary
A DALI device (2) comprises a DALI power supply (11). The DALI device (2) is adapted to be connected to a DALI bus (3), which is connected to a plurality of further DALI devices. The DALI power supply (11) is adapted to provide a DALI bus idle current to the DALI bus (3) during DALI bus idle times, and provide a communication current dependent upon a communication current input signal to the DALI bus (3), during DALI communication times.