DC-DC Converter Phase Shift Control for Satellite Power
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Solution Overview
Problem
Existing DC-DC converters for satellite power supply require complex transformer designs and active components like 'freewheel' diodes, which introduce energy dissipation and operational insecurity due to the risk of component failures.
Innovation Solution
A DC-DC converter design that eliminates active components and transformers with divided secondaries by using a series reactive circuit with a transformer to phase-shift voltage and current, allowing for controlled rectification and regulation without 'freewheel' diodes, utilizing a transformer with significant leakage inductance or an inductor and capacitor in series.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer with divided secondary and freewheel diode is used, then the converter can achieve current switching and regulated output, but the device complexity increases and energy dissipation occurs due to parasitic capacitance
Solution Approach 1:
The patent removes the freewheel diode from the circuit by redesigning the transformer secondary configuration. The divided secondary windings are connected directly to the saturable chokes, eliminating the need for the separate freewheel diode component and its associated parasitic capacitance, thereby reducing device complexity while maintaining output regulation through magnetic control
Solution Approach 2:
The patent combines the functions of the freewheel diode and current switching into the saturable chokes themselves. The chokes perform both the rectification function and the freewheeling function through their magnetic saturation characteristics, eliminating the need for separate active components and simplifying the overall device structure
2Reliability
If active components and control circuits are used for switching, then the converter can achieve soft switching and current doubling, but the device complexity increases and reliability decreases due to component failure risks
Solution Approach 1:
The patent employs saturable chokes that automatically perform soft switching through their inherent magnetic saturation characteristics. The chokes self-regulate the current flow and provide soft commutation without requiring external active components or control circuits, thereby eliminating failure points while maintaining the soft switching benefit
Solution Approach 2:
The patent replaces electronic active components (transistors, control circuits) with passive magnetic components (saturable chokes). The magnetic saturation effect provides the switching function that would otherwise require active electronic components, improving reliability by eliminating semiconductor failure modes while achieving the same soft switching effect
3Reliability
If a center tap transformer with half-windings is used, then the converter can achieve proper current switching, but the manufacturing complexity increases
Solution Approach 1:
The patent divides the transformer secondary into separate windings for each saturable choke, with each winding independently connected to its corresponding choke. This segmentation allows for simpler individual winding constructions and easier assembly compared to a single center-tapped winding, while still achieving the required current switching function through the magnetic characteristics of the chokes
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 design achieves stable and fault-tolerant operation by naturally switching power diodes without 'freewheel' diodes, reducing switching losses and parasitic emissions, and regulating output voltage through phase shift variations, enhancing reliability for satellite power supply.
Implementation Method 1
a series reactive circuit associated with said transformer and cooperating with said controlled rectifier to phase-shift said third voltage with respect to said third current
Implementation Method 2
said saturable chokes magnetically controlling, during each cycle of the third voltage delivered by said inverter, the instants of turning on and off of said power diodes
Implementation Method 3
utilizing a transformer with significant leakage inductance
Implementation Method 4
a transformer with significant leakage inductance or an inductor and capacitor in series
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The converter comprises an inverter (2) and a conversion unit (UCa) in which a transformer (3) powers a controlled rectifier formed by saturable inductors (Lsat1 and Lsat2) and power diodes (D1, D2). According to the invention, a series reactive circuit (Lr) associated with the transformer (3) co-operates with the controlled rectifier for the phase displacement of the voltage (Ve) applied at the primary of the transformer (3) in relation to the current (le) flowing therethrough. The phase displacement is regulated by a control voltage (Vc) as a function of the variations in the output voltage (Vs) of the converter.