Bi-directional Converter Voltage Control for Bus Stability
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Solution Overview
Problem
Voltage converter systems face challenges in stabilizing electrical bus impedance and reducing voltage ripple due to mode transitions and limited amplitude oscillations, particularly in applications like spacecraft where power flows bidirectionally, leading to complex control loop stabilization.
Innovation Solution
A bi-directional converter voltage controlled current system with a variable duty-cycle controller and current sensor that provides a proportional sensor voltage signal, simplifying the transfer function to equivalent a voltage controlled current source, allowing for stable power management across multiple sources and loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If basic units are individually stabilized with staggered set-points and mode transitions are used, then voltage conversion between different levels is achieved, but bus transients and large low frequency ripple occur on the electrical bus
Solution Approach 1:
The patent implements a feedback control mechanism where the central amplifier continuously monitors the electrical bus voltage and adjusts the duty cycle of connected voltage converters to maintain stable bus voltage. The feedback loop detects voltage deviations and automatically corrects them by modulating the converter operation, preventing bus transients and ripple while maintaining voltage conversion capability.
Solution Approach 2:
The patent employs dynamic duty cycle adjustment where the central amplifier varies the duty cycle in real-time based on operating conditions and load requirements. This dynamic control allows smooth transitions between operating modes without causing bus transients, as the duty cycle is continuously optimized to maintain stability during voltage conversion operations.
2Stability of the object's composition
If filters made of capacitors and inductors are added to reduce voltage ripple, then voltage ripple is reduced, but device complexity increases
Solution Approach 1:
The patent enables voltage converters to self-regulate and contribute to bus stabilization without requiring external passive filters. Each converter operates under control of the central amplifier, automatically adjusting its output to compensate for voltage variations. This self-service approach achieves voltage ripple reduction through active control rather than passive filtering, avoiding the added complexity of filter circuits.
3Adaptability or versatility
If a central amplifier varies across a full operating range with mode transitions, then voltage regulation flexibility is improved, but bus impedance becomes very high during transitions
Solution Approach 1:
The patent implements preliminary action by pre-coordinating mode transitions through the central amplifier before actual switching occurs. The controller prepares the system for upcoming transitions by gradually adjusting duty cycles and anticipating load changes, ensuring smooth handovers between operating modes. This preliminary preparation prevents sudden impedance changes and maintains bus stability during transitions across the full operating range.
Data Source
AI summary
A bi-directional converter voltage controlled current system and methods are disclosed. A bi-directional converter provides a bi-directional current to an electrical bus according to a variable duty-cycle control signal. Also, a bi-directional current sensing sensor senses the bi-directional current to provide a sensor voltage signal proportional to the converter current. Further, a variable duty-cycle controller controls a duty-cycle of the variable duty-cycle control signal to control a voltage of the electrical bus based on an error signal.