Virtual Resistance Control for Stable CV and CC Power Loops
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Solution Overview
Problem
Existing measurement and control systems face challenges in maintaining dynamic performance in constant voltage (CV) mode, which is invariant to source type and operating points, and in reducing resonance caused by cable inductance in constant current (CC) mode without using snubber elements or altering control elements.
Innovation Solution
The system and method introduce a voltage-controlled resistance (VCR) approach, replacing traditional voltage-controlled current sources, to maintain dynamic performance in CV mode independently of source type and operating points. Additionally, a virtual snubber arrangement is implemented to reduce or eliminate resonance caused by cable inductance in CC mode without additional physical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional voltage-controlled current sources are used in CV mode, then the control system can operate in both CC and CV modes with a single control element, but the dynamic performance in CV mode becomes dependent on source type and operating points
Solution Approach 1:
The patent implements a dynamic control element that can switch between voltage-controlled current source and voltage-controlled voltage source modes. This dynamic adaptability allows the system to optimize performance for each mode independently, resolving the contradiction between mode compatibility and performance consistency by making the control characteristics changeable rather than fixed
Solution Approach 2:
The patent changes the control parameter from current to voltage in CV mode, transforming the control element's characteristics. By adjusting the control parameter based on operating mode, the system achieves consistent dynamic performance across different modes and source types while maintaining versatility
2Productivity
If cable inductance is present in CC mode, then the system can operate with standard cabling, but resonance occurs that limits bandwidth and response speed
Solution Approach 1:
The patent converts the harmful resonant effect of cable inductance into a beneficial damping effect by introducing a virtual resistance that dissipates the resonant energy. This transforms the problematic inductance-c capacitance resonance into a controlled energy dissipation mechanism, eliminating the harmful oscillations while maintaining the necessary bandwidth and response speed
3Object-generated harmful factors
If snubber elements are added to reduce cable inductance resonance, then resonance is reduced, but the system complexity and component count increase
Solution Approach 1:
The patent introduces a virtual resistance as an intermediary element that mediates between the cable inductance and the control circuit. This virtual resistance, implemented through control algorithms rather than physical components, provides the necessary damping effect without adding physical snubber elements, thus reducing system complexity while effectively suppressing resonance
Solution Approach 2:
The patent replaces the mechanical/electrical snubber circuit with a software-based virtual resistance implementation. By substituting physical damping components with a control algorithm, the system achieves resonance suppression without increasing hardware complexity, maintaining simplicity while improving performance
Data Source
AI summary
A control system exhibits improved dynamic performance in a constant voltage (CV) control mode that is also invariant of the source type and operating points. The improvements may be achieved with minimal or potentially no additional parts to the control circuit by replacing a voltage-controlled current source with a voltage-controlled resistance as the control element in the system feedback loop. An input voltage from a device under test (DUT) is measured, a feedback control voltage is determined based at least in part on the input voltage to provide a CV mode control loop for the DUT, and the feedback control voltage added to the input voltage is applied to the DUT to operate the DUT in the CV mode.