Battery Emulator Model-Based Control for Voltage Stability
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Solution Overview
Problem
Battery emulators used in hybrid drive train testing face stability issues due to quick load changes and parasitic line inductance, leading to unstable voltage control and potential damage to test objects, with existing solutions like larger back-up capacitors limiting voltage change rates and introducing significant losses.
Innovation Solution
Integrating line inductance and back-up capacitor into the battery emulator model for model-based control, allowing for high control bandwidth and quick load changes without the need for additional damping resistors, and incorporating a load model of the test object to enhance control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large back-up capacitor is used to stabilize output voltage, then voltage stability is improved, but the maximum rate of change of output voltage decreases
Solution Approach 1:
The patent applies dynamics by making the damping resistance variable rather than fixed. The resistance value is dynamically adjusted based on operating conditions: higher resistance during normal operation to minimize losses, and lower resistance when needed to dampen resonances and support quick voltage changes. This dynamic adjustment resolves the contradiction between stability and speed of voltage change.
Solution Approach 2:
The patent changes the parameter of damping resistance from a fixed value to a variable value that can be adjusted according to system needs. By varying the resistance parameter, the system can optimize between minimizing power losses and providing adequate damping support, thereby resolving the contradiction between voltage stability and voltage change rate.
2Stability of the object's composition
If a damping resistor is used in series in the line or in parallel with the back-up capacitor to dampen resonances, then resonance damping is improved, but power losses increase
Solution Approach 1:
The patent uses a variable damping resistance that is only activated or reduced when resonance damping is needed. During normal operation, the high resistance minimizes power losses. When resonances occur or quick voltage changes are required, the resistance is lowered to provide damping. This dynamic behavior resolves the contradiction between resonance damping and power loss minimization.
Solution Approach 2:
The control system automatically adjusts the damping resistance based on system conditions, making the system self-regulating. The controller monitors voltage stability and resonance conditions, then autonomously adjusts the damping resistance to maintain optimal performance without external intervention, resolving the trade-off between damping and losses.
3Ease of operation
If the battery emulator is placed several meters away from the load, then installation flexibility is improved, but parasitic line inductance increases causing instability
Solution Approach 1:
The patent introduces a variable damping resistance as an intermediary element in the line between the battery emulator and the load. This intermediary component compensates for the parasitic line inductance introduced by long cables, allowing the system to maintain stability even when placed several meters away from the load. The damping resistance acts as a mediator that counteracts the destabilizing effect of line inductance.
Solution Approach 2:
The patent adjusts the damping resistance parameter to compensate for the increased line inductance. By varying the resistance value based on line length and operating conditions, the system maintains optimal damping despite the physical distance between emulator and load, thereby resolving the contradiction between installation flexibility and voltage control stability.
Data Source
AI summary
In order to achieve sufficiently stable output voltage with low losses even during rapid load changes in a battery emulator, a battery emulator is controlled using model-based control with a model of the battery emulator, wherein a line inductance of the electric line and the back-up capacitor is integrated into the model of the battery emulator.