Switching Power Supply with Input Voltage Detection for LED Lighting
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Solution Overview
Problem
Switching power supply devices face instability when AC input voltage varies widely, leading to increased design, manufacturing, and maintenance costs due to the need for separate devices for different voltage systems, as they struggle to maintain constant current and voltage regulation across varying input voltages.
Innovation Solution
A switching power supply device with a rectifier unit, power converting unit, current detecting unit, and input voltage detecting unit that regulates load current and line voltage through a drive control unit, using an insulation transformer and duty ratio adjustment to maintain constant current supply and improve power supply stability across a wide range of AC input voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switching power supply devices are used without input voltage detection and correction, then the device complexity is low, but the power supply stability deteriorates when AC input voltage varies widely
Solution Approach 1:
The input voltage detecting unit detects AC input voltage variations in advance before they affect the output current stability. The detected voltage information is used proactively to adjust the duty ratio of the switching element, preventing output current deviation before it occurs. This preliminary detection and correction mechanism maintains power supply stability without requiring complex feedback loops.
Solution Approach 2:
The patent implements a feedback mechanism where the input voltage detecting unit continuously monitors AC input voltage and feeds this information to the drive control unit. The drive control unit adjusts the duty ratio based on this feedback to compensate for voltage variations. This closed-loop feedback system ensures power supply stability while keeping the overall device complexity manageable through efficient control logic.
2Adaptability or versatility
If separate power supply devices are designed for different voltage systems (100V, 200V), then the power supply stability for each specific voltage is high, but the manufacturing cost and device complexity increase
Solution Approach 1:
The switching power supply device is designed with universal adaptability to operate across multiple AC input voltage systems (100V, 200V, and intermediate voltages). The input voltage detecting unit identifies the actual input voltage level, and the drive control unit automatically adjusts the duty ratio accordingly. This single device design eliminates the need for separate power supply units for different voltage systems, reducing manufacturing costs and inventory complexity while maintaining high power supply stability across all supported voltages.
3Reliability
If the duty ratio is fixed without input voltage compensation, then the device complexity is low, but the load current variation increases when AC voltage varies
Solution Approach 1:
The patent transforms the fixed duty ratio into a dynamic, adjustable parameter. The drive control unit continuously modifies the duty ratio based on real-time AC input voltage detection. When input voltage increases, the duty ratio is reduced; when input voltage decreases, the duty ratio is increased. This dynamic adjustment mechanism maintains stable load current despite voltage variations, achieving high reliability without requiring complex control algorithms.
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
The solution reduces the variation of load current by up to 2.5% when AC voltage varies by 187%, achieving improved power supply stability and allowing for a single design to accommodate different commercial power line voltages, thereby reducing costs and increasing market competitiveness.
Implementation Method 1
a rectifier unit which rectifies AC voltage received from an AC power line and outputs pulsating-current voltage
Implementation Method 2
a switching element performs switching of current flowing in a primary coil of an insulation transformer to which the pulsating-current voltage is supplied, whereby current induced across a secondary coil of the insulation transformer
Data Source
AI summary
Implemented are a switching power supply device and a light-emitting diode lighting device in which a variation in load current can be suppressed against a wide range of variation in AC voltage. The configuration of the switching power supply device and the light-emitting diode lighting device includes: a rectifier unit which rectifies AC input voltage and outputs pulsating-current voltage; a power converting unit which receives the pulsating-current voltage and supplies a predetermined load current to a load; a current detecting unit which detects the load current; a drive control unit which controls the power converting unit to regulate the load current to a constant level; and an input voltage detecting unit which detects a variation in the AC input voltage. The drive control unit controls the power converting unit depending on the variation in the AC input voltage detected by the input voltage detecting unit.