Current Source Rectifier Switching for Low Loss and Low Distortion
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Solution Overview
Problem
Current source rectifiers (CSRs) face a trade-off between high efficiency and low current distortion, with methods to reduce switching losses often introducing undesirable input current distortion, and existing solutions like increasing input filter capacitance or switching frequency are not practical due to cost and performance concerns.
Innovation Solution
A three-phase current source rectifier system with a controller that switches between high-efficiency and high-quality sequences based on input voltage ranges, using hysteresis to determine the appropriate sequence and minimize switching losses while reducing current distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If switching frequency is increased to reduce current distortion, then current distortion is reduced, but switching losses increase and efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the switching sequence adaptive rather than fixed. The controller dynamically selects between first and second switching sequences based on real-time detection of input voltage conditions. This dynamic adaptation allows the system to optimize performance across varying operating conditions without being constrained to a single switching frequency or sequence, thereby reducing current distortion while managing switching losses effectively.
2Manufacturing precision
If input filter capacitance is increased to reduce current distortion, then current distortion is reduced, but device complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by modifying the switching sequence parameters based on input voltage conditions rather than changing physical filter parameters. The controller detects input voltage levels and adjusts the switching sequence accordingly, effectively changing the electrical parameters of the rectifier system to minimize current distortion. This approach achieves distortion reduction through control strategy optimization rather than increasing filter capacitance, thereby avoiding increased device complexity and cost.
3Device complexity
If a fixed switching sequence is used to simplify control, then device complexity is reduced, but performance deteriorates under varying voltage conditions
Solution Approach 1:
The patent applies segmentation by dividing the control strategy into distinct switching sequences (first and second sequences) that are selected based on specific voltage conditions. Rather than using a single complex adaptive algorithm, the control is segmented into multiple predefined sequences, each optimized for particular operating conditions. The controller segments the operating range and selects the appropriate sequence, maintaining relatively simple control logic while achieving consistent performance across varying voltage conditions.
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 adaptive switching sequence effectively reduces switching losses and current distortion, maintaining high power factor and efficiency by selecting the optimal switching strategy based on input voltage conditions.
Implementation Method 1
define a predetermined voltage range in a memory of the controller by hysteresis
Data Source
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AI summary
Current source rectifiers (CSR) and methods for a power source including three phase lines are provided herein. The CSR includes a rectifier having a plurality of switches, each switch of the plurality of switches coupled to an associated phase line of the three phase lines. The rectifier is operable to receive an alternating current (AC) input voltage and provide a direct current (DC) output voltage. The CSR also includes a controller configured to control operation of the switches in accordance with a first switching sequence (400) when measured input voltages on at least two phase lines of the three phase lines are outside of a predetermined voltage range and to control operation of the switches in accordance with a second switching sequence (300) when the measured input voltages on the at least two phase lines are within the predetermined voltage range.