Lighting Current Control for Bus-Induced Flicker Suppression
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Solution Overview
Problem
Communication via a digital bus interface in lighting systems causes fluctuations in supply voltage, leading to changes in current provided to lighting means, resulting in visible light emission variations, such as flickering, which affect luminance.
Innovation Solution
A control system that performs feedback and feedforward control of the current source, using different gains based on the presence of communication via the bus interface to adjust the current and mitigate supply voltage changes, thereby reducing or preventing visible light emission fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If communication is performed via the bus interface, then data transmission is enabled, but supply voltage fluctuations cause visible light emission variations
Solution Approach 1:
The control system applies a feedforward control that anticipates supply voltage drops during communication by processing the voltage error with a first gain before the disturbance fully affects the lighting means. This preliminary counter-action compensates for the expected voltage fluctuation, preventing visible light emission variations while maintaining data transmission capability
Solution Approach 2:
The control system dynamically adjusts the gain parameter based on communication state. When communication is detected via the bus interface, the system switches from a second gain to a first gain for processing supply voltage errors. This dynamic adaptation allows the system to maintain stable light emission during communication without sacrificing data transmission functionality
2Device complexity
If a single voltage supply circuit is used for both bus interface and current source, then device complexity is reduced, but light emission stability deteriorates during communication
Solution Approach 1:
The control system implements feedback control that continuously monitors the supply voltage and adjusts the current to the lighting means accordingly. By processing the voltage error with an appropriately selected gain based on communication state, the feedback mechanism compensates for voltage fluctuations caused by bus interface operations, maintaining stable light emission while using a single integrated voltage supply circuit
Solution Approach 2:
The control system changes the parameter (gain value) of the feedforward control based on the detected communication state. When communication is active, the system switches to a first gain that provides stronger compensation for voltage drops. This parameter adaptation allows a single voltage supply circuit to maintain both low complexity and stable light emission by dynamically adjusting control characteristics
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3
AI summary
The invention relates to a control system (1) for controlling a current source (4) of an operating device (10) for lighting means (5). The current source (4) is configured to provide a current (ILM) to the lighting means (5). The operating device (10) comprises a bus interface (8) electrically connectable to a digital bus (7) and a voltage supply circuit (3) for providing a supply voltage (V1) to electrically supply the bus interface (8) and the current source (4). The control system (1) is configured to perform a feedback control of the current (ILM) with regard to a reference current (Iref1, Iref2), and determine whether a communication via the bus interface (8) is present or not. Further the control system (1) is configured to perform a feedforward control of the current (ILM) based on an error (Ev) between the supply voltage (V1) and a reference voltage (Vref) for the supply voltage (V1), by processing the error (Ev) using a first gain (Gi) in case the control system (1) determines that the communication is present and a second gain (G2) in case the control system (1) determines that the communication is not present. The first gain (Gi) is different to the second gain (G2).