Cascaded Rectifier Active Power Decoupling for Ripple Suppression
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Solution Overview
Problem
Conventional single-phase high-power factor rectifiers in power electronic traction transformers face challenges with secondary ripple voltage fluctuations, which affect power transmission and voltage withstand, and existing solutions like large capacitors or LC resonators are inefficient and unreliable, limiting power density.
Innovation Solution
A multi-module single-phase device-multiplexing active power decoupling H-bridge cascaded rectifier is introduced, incorporating an active power decoupling branch that transfers ripple power to an energy storage unit, reducing the capacity of the DC-side bus voltage supported capacitor, and a control method that uses proportional resonance controllers to manage voltage balance and ripple suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capacitor with large capacitance is connected in parallel to the DC bus to suppress secondary ripple voltage, then the ripple voltage is suppressed, but the capacitor has low withstand voltage and short service life
Solution Approach 1:
The patent merges the functions of the DC bus capacitor and the secondary ripple suppression capacitor into a single integrated capacitor structure. The same capacitor serves dual purposes: maintaining DC bus voltage and suppressing secondary ripple voltage, thereby avoiding the reliability issues of large-capacitance capacitors while achieving ripple suppression.
Solution Approach 2:
The patent makes the DC bus capacitor perform multiple functions simultaneously - it acts as both the DC link capacitor for voltage stabilization and the secondary ripple suppression capacitor. This multi-functional design eliminates the need for separate large-capacitance capacitors, improving both reliability and power density.
2Loss of energy
If a film capacitor is connected in parallel to the DC bus to suppress secondary ripple voltage, then the loss is small, but the size is large and costs are higher
Solution Approach 1:
The patent combines the DC bus capacitor and secondary ripple suppression capacitor into one integrated component, eliminating the need for separate film capacitors. This reduces overall capacitor size and cost while maintaining low energy loss through optimized capacitance selection and topology design.
Solution Approach 2:
The integrated capacitor performs both DC bus voltage stabilization and secondary ripple suppression functions, replacing what would traditionally require separate capacitors. This multi-functionality reduces total capacitor volume and cost while maintaining low energy losses.
3Object-affected harmful factors
If an LC resonator is connected in parallel to the DC bus to suppress secondary ripple voltage, then the ripple voltage is suppressed, but the mass and size are large and the system is sensitive to parameters
Solution Approach 1:
The patent extracts the secondary ripple suppression function from the complex LC resonator structure and integrates it into the DC bus capacitor itself. This eliminates the need for separate inductors and capacitors forming an LC resonator, thereby reducing parameter sensitivity and device complexity while maintaining effective ripple suppression.
Solution Approach 2:
The patent merges the DC bus capacitor and secondary ripple suppression elements into a single integrated capacitor system, eliminating the LC resonator structure. This simplifies the circuit, reduces the number of components, and decreases sensitivity to parameter variations while effectively suppressing secondary ripple voltage.
4Object-affected harmful factors
If conventional solutions are used to suppress secondary ripple voltage, then the ripple is suppressed, but the power density of the power electronic transformer cannot increase
Solution Approach 1:
The patent makes the DC bus capacitor perform dual functions - maintaining DC bus voltage and suppressing secondary ripple voltage. This eliminates the need for additional large-capacitance or LC resonator components that would occupy space, thereby maintaining high power density while achieving effective ripple suppression.
Solution Approach 2:
The patent combines the DC bus capacitor and secondary ripple suppression functionality into a single integrated system, eliminating the need for separate large-volume components. This integration maintains compact design and high power density while effectively suppressing secondary ripple voltage pulsation.
Data Source
AI summary
A single-phase device-multiplexing active power decoupling cascaded rectifier and control method thereof. The rectifier includes: n device-multiplexing active power decoupling H-bridge units that are cascaded, n≥2; each unit including: a bridge arm H1 and a bridge arm H2 connected in parallel, a decoupling capacitor branch formed by two capacitors connected in series, and a resistive load; a decoupling inductor being connected in series between a midpoint of the decoupling capacitor branch and a midpoint of bridge arm H2; and a bridge arm H1 of a first unit being sequentially connected in series to an inductor, resistor, and power supply, and then connected to a bridge arm H2 of a last unit. A power switch module of an H-bridge rectification unit is multiplexed, which not only realizes unit power factor rectification of the unit, but also provides a loop for secondary ripple power to achieve secondary ripple power decoupling control.