Vehicle Lamp Current Driver Circuit With Ripple Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing automotive lighting systems with adaptive driving beam (ADB) techniques face inefficiencies in power consumption due to unnecessary power loss from feedback control methods that maintain output voltage above the required level, leading to increased heat generation, especially in vehicles with large current demands.
Innovation Solution
A lighting circuit design that includes multiple current sources, a switching converter, and a converter controller using a ripple control method to turn on the switching transistor when the voltage across any current source reaches a bottom limit, reducing power consumption by maintaining voltages at the minimum necessary level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to maintain output voltage above the required level, then reliability is improved, but power consumption increases and heat generation occurs
Solution Approach 1:
The patent implements periodic switching action by turning the switching transistor on and off in cycles. The transistor is turned on when the voltage across the current source decreases to a bottom limit voltage, and turned off when the voltage reaches a top limit voltage. This periodic switching maintains the voltage within acceptable bounds while minimizing the time the transistor conducts, thereby reducing power consumption and heat generation compared to continuous feedback control.
Solution Approach 2:
The patent changes the control parameter from continuous voltage regulation to threshold-based switching. Instead of maintaining voltage continuously above a required level through active feedback, the system allows voltage to fluctuate between a bottom limit voltage and a top limit voltage. This parameter change from continuous to discrete control reduces the energy dissipation in the current source and switching transistor.
2Reliability
If output voltage is maintained at a higher level with margin, then reliability is improved, but unnecessary power loss increases
Solution Approach 1:
The patent uses periodic switching to maintain voltage within bounds rather than continuously maintaining it at a high level. The switching transistor operates in pulses, turning on only when voltage drops to the bottom limit and turning off when it reaches the top limit. This periodic action ensures reliability by keeping voltage within acceptable ranges while minimizing the duration of high-voltage states that cause power loss.
Solution Approach 2:
The patent applies partial action by not continuously maintaining voltage at the maximum safe level. Instead, it allows voltage to fluctuate within a range, applying full control only when necessary (at the threshold points). This partial control approach reduces the average power loss compared to continuously maintaining voltage at the highest safe level with margin.
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
This approach reduces power consumption and heat generation in automotive lamps by optimizing the switching converter operation, ensuring efficient power usage even in high-current scenarios.
Implementation Method 1
a switching converter structured to supply a driving voltage across each of multiple series connection circuits each formed of the semiconductor light source and the current source
Implementation Method 2
The multiple light-emitting units 1008_1 through 1008_N are each configured as a semiconductor light source such as an LED (light-emitting diode)
Implementation Method 3
When a given driving current I LEDi flows through the light-emitting unit 1008_i, a voltage drop (forward voltage) V Fi occurs in the light-emitting unit 1008_i
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A lighting circuit 200 turns on a plurality of semiconductor light sources 102. Multiple current sources 210_1 through 210_N are each coupled to a corresponding semiconductor light source 102. A switching converter 220 supplies a driving voltage VOUT across each of multiple series connection circuits each formed of the semiconductor light source 102 and the current source 210. A converter controller 230 employing a ripple control method turns on a switching transistor M1 of the switching converter 220 in response to a voltage VLED across any one of the multiple current sources 210 decreasing to a bottom limit voltage VBOTTOM.