AC to DC Power Conversion Without Diode Bridge Rectification
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Solution Overview
Problem
Conventional power conversion apparatuses incur power loss due to full-wave rectification and are limited to accepting only positive input voltage and current, as they require a diode bridge circuit for full-wave rectification, which is inefficient and restricts the use of alternating current without rectification.
Innovation Solution
A power conversion apparatus that uses a converter with first and second switching elements, controlled by a controller to alternately turn on and off, allowing direct conversion of AC to DC without full-wave rectification, utilizing input voltage and current detectors to determine pulse widths for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-wave rectification is applied using a diode bridge circuit, then the converter can accept only positive input voltage and current, but power loss occurs due to current flowing through two diodes in series
Solution Approach 1:
The patent removes the diode bridge circuit from the power conversion system, extracting the full-wave rectification function and replacing it with a converter that can directly process AC input. This eliminates the energy loss associated with diode forward voltage drops while maintaining the ability to handle both positive and negative input voltage cycles.
Solution Approach 2:
Instead of rectifying AC to DC before the converter (conventional approach), the patent inverts the approach by allowing the converter to directly process AC input voltage and current, converting them to DC output. This reversal eliminates the need for diode bridge rectification and its associated power losses.
2Loss of energy
If alternating current is applied to a converter without full-wave rectification, then power loss is prevented, but the converter cannot accept negative input voltage and current
Solution Approach 1:
The patent employs dynamic control of switching elements that adapt their operation based on the instantaneous polarity of the AC input voltage. The control unit dynamically adjusts the switching timing and duration to ensure proper current flow through the converter regardless of whether the input voltage is positive or negative, enabling the converter to accept full AC waveforms without rectification.
3Reliability
If a diode bridge circuit is used for full-wave rectification, then the converter can operate with positive input, but the component count and circuit complexity increase
Solution Approach 1:
The patent removes the entire diode bridge circuit from the system, eliminating four diodes and their associated circuitry. This extraction simplifies the overall circuit topology while the converter's switching elements and control unit assume the functionality previously performed by the rectification circuit.
Solution Approach 2:
The converter and its control unit are designed to perform multiple functions: they directly process AC input voltage, control current flow during both positive and negative half-cycles, and generate DC output voltage. This multi-functionality replaces the specialized rectification function of the diode bridge, reducing overall circuit complexity.
Data Source
AI summary
According to one embodiment, power conversion apparatus includes a converter and a controller. A converter receives an AC power as an input, and outputs a DC voltage by turning on and off a first switching element which operates when the AC power is positive, and a second switching element which operates when the AC power is negative. A controller receives an AC input voltage and alternating input current to the converter, and a DC output voltage from the converter, as an input, determines a pulse width of a first pulse signal to turn on the first switching element and a pulse width of a second pulse signal to turn on the second switching element, and outputs the first pulse signal and second pulse signal to the converter.