AC to DC Converter Using Single Switch Voltage Gating
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Solution Overview
Problem
Existing high voltage AC to low voltage DC conversion systems require large high voltage filter capacitors and switching transformers, making them bulky, costly, and unsuitable for space-constrained applications, while also being inefficient due to the need for multiple switches and linear regulators.
Innovation Solution
A single electronically actuated switch performs both pre-regulation and switching conversion, regulating output voltage by changing the input voltage threshold instead of using pulse width modulation, eliminating the need for bulky high voltage capacitors and transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switching power supplies use high voltage rated components to withstand peak line voltage, then reliability is improved, but device size and cost increase due to physically large capacitors and transformers
Solution Approach 1:
The power conversion process is segmented into two distinct stages: a pre-regulator stage that clips the input voltage to a maximum threshold below peak line voltage, and a secondary switching power supply stage that performs the actual DC conversion. This segmentation allows each stage to use components rated for lower voltages, reducing overall size and cost while maintaining reliability.
Solution Approach 2:
The pre-regulator circuit performs preliminary voltage clipping action before the main switching power supply stage. By limiting the input voltage to a safe threshold level in advance, the main power supply components only need to handle the reduced voltage level, eliminating the need for oversized high-voltage rated components.
2Volume of stationary object
If switching frequency is increased to reduce transformer size, then device size is reduced, but switching losses and complexity increase
Solution Approach 1:
The power conversion is divided into pre-regulation and main conversion stages operating at different frequencies. The pre-regulator operates at line frequency with simple voltage clipping, while the main switching stage operates at optimized switching frequency. This segmentation allows each stage to use appropriate switching frequencies without excessive complexity.
3Reliability
If isolation transformer is used to provide mains isolation, then safety is improved, but device size and cost increase
Solution Approach 1:
Isolation is provided only in the main switching power supply stage, not in the pre-regulator stage. This segmented approach to isolation allows the use of a smaller isolation transformer since it only needs to handle the reduced power level after pre-regulation, rather than the full input power at line voltage.
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 reduces the size and cost of power supply modules by using low voltage-rated components and preventing high input voltages from damaging them, achieving efficient and compact high current low voltage DC output without the need for large capacitors or multiple switches.
Implementation Method 1
A voltage comparator compares the rectified input voltage to a threshold voltage and generates a control signal
Implementation Method 2
A transformer converts the high voltage pulses to a low voltage output
Implementation Method 3
A filter capacitor smooths the rectified voltage waveform to reduce ripple
Data Source
AI summary
A method and apparatus for conversion of high voltage AC to low voltage high current DC without using high voltage capacitors or transformers. A single switch is used to perform both the functions of pre-regulation and switching conversion. An input voltage detector determines when the input power AC is below a predetermined voltage limit. A threshold voltage generator provides a threshold voltage corresponding to the output voltage. A voltage comparator coupled to the input voltage detector and threshold voltage generator enables a pulse generator to activate the switch to gate a number of pulses of the input power below the predetermined voltage limit at predetermined frequency to a transformer. The converter regulates its output voltage by changing the input voltage threshold at which it starts switching, instead of using PWM or other known regulation technique.