Transformer-less Delta Conversion Rectifier for EMI Reduction
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Solution Overview
Problem
Existing AC-DC rectifiers face inefficiencies due to bulky EMI filters, double conversion, and the need for large line frequency transformers, particularly in buck-boost configurations and transformer-based delta conversion UPS systems.
Innovation Solution
A transformer-less delta conversion rectifier system that includes active power filters and inverters to provide Power Factor Correction (PFC) and convert AC voltage to DC voltage directly, eliminating the need for bulky filters and transformers by operating in buck, boost, or buck-boost modes based on input voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional EMI filters and line frequency transformers are used in AC-DC rectifiers, then electromagnetic interference is filtered and power transformation is achieved, but the system size, weight, and cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the bulky line frequency transformer and traditional EMI filters from the rectifier system. Instead, it uses a high-frequency isolated full-bridge converter topology that achieves electromagnetic isolation and interference filtering through high-frequency switching and galvanic isolation, dramatically reducing system weight and size while maintaining EMI performance
Solution Approach 2:
The patent replaces the mechanical/magnetic transformation system (line frequency transformer) with an electronic switching system (high-frequency full-bridge converter). The high-frequency switching circuitry performs voltage transformation and galvanic isolation without requiring large magnetic components, substituting electronic control for traditional electromagnetic transformation
2Reliability
If double conversion is used in rectifier systems, then voltage regulation and isolation are improved, but system complexity and efficiency are reduced
Solution Approach 1:
The patent merges the rectification, voltage regulation, and galvanic isolation functions into a single integrated high-frequency full-bridge converter stage. This unified topology performs all three functions simultaneously through coordinated switching of the full-bridge circuit, eliminating the need for separate conversion stages and reducing overall system complexity while maintaining reliable voltage regulation
3Reliability
If line frequency transformers are used for voltage transformation, then galvanic isolation and voltage conversion are achieved, but the transformer size and cost increase
Solution Approach 1:
The patent changes the operating frequency parameter from line frequency (50/60 Hz) to high frequency (kHz range). This frequency increase allows the use of much smaller magnetic components while achieving the same galvanic isolation and voltage transformation functions. The high-frequency switching enables compact transformers with significantly reduced volume and weight compared to line frequency designs
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 rectifier systems, improves efficiency by avoiding double conversion, and maintains high power factor while providing a constant DC output without the need for large transformers or EMI filters.
Implementation Method 1
an inverter coupled to the input and configured to convert the input AC voltage waveform into an output AC voltage waveform at a desired magnitude
Implementation Method 2
a rectifier portion coupled between the inverter and the output and configured to convert the output AC voltage waveform into the output DC power
Data Source
AI summary
According to one aspect, embodiments of the invention provide an AC-DC rectifier comprising an input configured to receive input AC power from an AC power source having an input AC voltage waveform, an output configured to provide output DC power to a load, an active power filter coupled to the input, an inverter coupled to the input and configured to convert the input AC voltage waveform into an output AC voltage waveform at a desired magnitude, a rectifier portion coupled between the inverter and the output and configured to convert the output AC voltage waveform into the output DC power, and a controller coupled to the active power filter and the inverter and configured to operate the active power filter to provide Power Factor Correction (PFC) at the input and to operate the inverter to provide the output AC voltage waveform at the desired magnitude to the rectifier portion.