Single-Stage Boost LED Driver Circuit for Mains Voltage Conversion
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Solution Overview
Problem
Conventional LED driver circuits for high power lighting applications suffer from inefficiencies and high costs due to the need for multiple converters and high output currents when powering arrays of LEDs, leading to increased system losses and complex wiring.
Innovation Solution
A single-stage multi-level boost converter is used to directly convert mains voltage into an output voltage suitable for LEDs, eliminating the need for expensive high-voltage semiconductor devices and enabling efficient current balance control, which reduces system losses and costs by operating in critical discontinuous mode and simplifying cycle-by-cycle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple converters are used for each LED string, then current regulation is achieved, but device complexity and cost increase
Solution Approach 1:
The patent merges the power factor correction function and LED current regulation function into a single converter stage. The converter simultaneously performs AC-DC conversion with PFC and regulates current for multiple LED strings, eliminating the need for separate PFC converter and individual string regulators. This is achieved through a unified control strategy that manages the single converter to serve multiple functions.
Solution Approach 2:
The single converter is designed to perform multiple functions: power factor correction, AC-DC conversion, and current regulation for multiple LED strings. The control system universally manages the converter to provide both grid compliance (PFC) and LED driver functions, making the converter a multi-functional device that replaces what would traditionally require multiple separate components.
2Reliability
If multiple converters are used for each LED string, then current regulation is achieved, but system costs increase
Solution Approach 1:
The patent merges the power factor correction function and LED current regulation function into a single converter stage. The converter simultaneously performs AC-DC conversion with PFC and regulates current for multiple LED strings, eliminating the need for separate PFC converter and individual string regulators. This is achieved through a unified control strategy that manages the single converter to serve multiple functions.
Solution Approach 2:
The single converter is designed to perform multiple functions: power factor correction, AC-DC conversion, and current regulation for multiple LED strings. The control system universally manages the converter to provide both grid compliance (PFC) and LED driver functions, making the converter a multi-functional device that replaces what would traditionally require multiple separate components.
3Reliability
If LEDs are connected in parallel strings, then current distribution is improved, but output current increases leading to higher losses
Solution Approach 1:
The control system implements feedback mechanisms to monitor and regulate the current distribution among parallel LED strings. By measuring the actual current in each string and adjusting the converter switching patterns accordingly, the system maintains balanced current distribution without requiring excessive total output current, thereby reducing resistive losses in the wiring and components.
Solution Approach 2:
The converter operates with dynamic switching patterns that adapt to the specific requirements of each LED string. The control system dynamically adjusts the duty cycles and switching sequences to optimize current distribution, allowing the system to maintain efficient operation across varying load conditions while minimizing energy losses.
4Device complexity
If output voltage exceeds peak mains voltage, then galvanic insulation can be eliminated, but insulation requirements increase
Solution Approach 1:
The patent extracts the galvanic insulation requirement from the converter design by operating the converter in a manner that generates an output voltage exceeding the peak mains voltage. This voltage level strategy eliminates the need for galvanic isolation transformers or other insulation barriers, as the high voltage output inherently provides the necessary electrical separation. The design accepts increased insulation requirements in the high voltage path as a trade-off for eliminating complex galvanic isolation 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
This solution enhances system efficiency, reduces electronic component requirements, and eliminates the need for galvanic insulation, achieving higher output voltage levels while minimizing losses and costs, and providing effective current balance control.
Implementation Method 1
a single-stage boost converter adapted to directly convert the mains voltage into the output voltage
Data Source
Figure 1~2
Figure 3(A)~3(E)
Figure 4
AI summary
An LED driver circuit comprising at least one string (10) of LEDs (12) connected in series, and a power supply for converting a mains voltage (AC) into an output voltage (Uout ) to be applied to said at least one string (10) of LEDs, characterised in that the power supply includes a single-stage boost converter (14) adapted to directly convert the mains voltage (AC) into the output voltage (Uout).