Resonant AC-DC Converter With Charge Pump PFC and Soft Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional AC-DC power converters face issues with high conducted electromagnetic interference (EMI), severe switching losses, low energy efficiency, and low power factor due to hard-switching operations and rectangular switching waveforms, which are not effectively addressed by prior art converter topologies.
Innovation Solution
The AC-DC power converter employs a resonant DC-DC converter with a charge pump circuit that draws current pulses at a switching frequency proportional to the AC line voltage, enabling zero-voltage-switching (ZVS) or zero-current-switching (ZCS) and achieving high power conversion efficiencies, while the charge pump circuit performs power factor correction without a separate regulation loop, allowing for a single feedback loop for DC output voltage or current adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hard-switching operation is used in conventional AC-DC power converters, then the converter can operate at lower switching frequencies with simpler control, but it results in severe switching losses, low energy efficiency, and high conducted electromagnetic interference
Solution Approach 1:
The patent implements dynamic switching by transitioning from hard-switching to resonant soft-switching operation. The resonant inverter circuit dynamically adjusts the switching characteristics to achieve zero-voltage-switching (ZVS) or zero-current-switching (ZCS), thereby reducing switching losses while enabling operation at higher switching frequencies (above 750 kHz or 1 MHz).
Solution Approach 2:
The patent utilizes resonant oscillation principles by incorporating a resonant inverter circuit that operates at or near the resonant frequency of the tank circuit. This resonant operation creates a vibratory current waveform that naturally facilitates soft-switching, reducing electromagnetic interference and switching losses while maintaining high switching frequencies.
2Object-generated harmful factors
If conventional PWM converter topologies are used, then the converter can provide high power factor, but it suffers from high conducted electromagnetic interference and severe switching losses
Solution Approach 1:
The patent converts the harmful effect of rectangular switching waveforms into a beneficial resonant waveform. By using a resonant inverter with a tank circuit, the abrupt switching edges are transformed into smooth sinusoidal or near-sinusoidal current waveforms, eliminating electromagnetic interference while maintaining high energy efficiency through soft-switching operation.
Solution Approach 2:
The patent replaces the conventional PWM switching mechanism with a resonant oscillation mechanism. Instead of using pulse-width modulation with rectangular waves, the system uses resonant frequency oscillation to achieve power conversion, thereby eliminating the electromagnetic interference associated with rectangular waveforms while maintaining high efficiency.
3Weight of stationary object
If miniaturization is pursued in offline power converters, then the size and weight are reduced, but it requires higher switching frequencies that increase switching losses in conventional topologies
Solution Approach 1:
The patent enables dynamic soft-switching operation that adapts to higher switching frequencies required for miniaturization. The resonant inverter circuit maintains ZVS or ZCS conditions even at frequencies above 750 kHz or 1 MHz, allowing the converter to be miniaturized without incurring increased switching losses.
Solution Approach 2:
The patent changes the fundamental operating parameters by transitioning from hard-switching to soft-switching mode. This parameter change allows the converter to operate efficiently at the high switching frequencies (above 750 kHz or 1 MHz) necessary for miniaturization, thereby reducing size and weight without increasing energy losses.
4Object-generated harmful factors
If separate power factor correction circuitry is added to achieve high power factor, then the power factor improves, but the device complexity and size increase
Solution Approach 1:
The patent merges the power factor correction function with the main power conversion function by using the resonant inverter circuit to perform both tasks simultaneously. The resonant current waveform naturally provides sinusoidal input current with unity power factor, eliminating the need for separate PFC circuitry and reducing overall device complexity.
Solution Approach 2:
The resonant inverter circuit serves multiple functions: it performs power conversion, provides soft-switching for high efficiency, generates sinusoidal current for high power factor, and enables miniaturization through high-frequency operation. This multi-functionality eliminates the need for separate dedicated circuits for each function, reducing overall system complexity.
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 results in reduced switching losses, higher power densities, and improved power factor correction, achieving efficiencies above 0.95 and minimizing size and weight of passive components, with the power factor exceeding 0.99 as demonstrated by experimental results.
Implementation Method 1
a resonant inverter configured to convert the DC supply voltage into a resonant inverter voltage at a fixed or controllable switching frequency
Implementation Method 2
a charge pump circuit configured to perform power factor correction of the converter by drawing current pulses at a switching frequency of the converter from an AC line voltage
Data Source
AI summary
The present invention relates to an AC-DC power converter which includes a resonant DC-DC converter and a charge pump circuit. The charge pump circuit is configured to perform power factor correction of the AC-DC power converter by drawing current pulses at a switching frequency of the converter from an AC line voltage such that electrical charges of the current pulses vary substantially proportionally with instantaneous amplitude of the AC line voltage.