Capacitor Nonlinear Equivalent Circuit Model Simulation
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Solution Overview
Problem
Existing capacitor simulation methods fail to accurately simulate nonlinear characteristics under direct-current voltage due to complex configurations and polarity issues, leading to difficulties in estimating circuit operations and precision in high-frequency bands.
Innovation Solution
A capacitor simulation method and nonlinear equivalent circuit model that represent capacitors using passive circuit elements, express characteristic changes as approximate functions based on measured values, and utilize control current sources to generate difference currents, enabling dynamic and precise simulation of nonlinear characteristics under direct-current voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing capacitor simulation methods are used, then circuit simulation can be performed, but the nonlinear characteristics under direct-current voltage cannot be accurately simulated due to complex configurations and polarity issues
Solution Approach 1:
The capacitor model is segmented into two independent parts: a linear time-invariant equivalent circuit model and a separate nonlinear characteristic model. The nonlinear characteristics under direct-current voltage are extracted and represented as a function of the applied voltage, which is then integrated with the linear model. This segmentation allows the complex nonlinear behavior to be handled separately from the linear circuit analysis, improving simulation precision without significantly increasing overall model complexity.
Solution Approach 2:
The invention changes the parameter representation by expressing the capacitance value as a function of the applied direct-current voltage: C(Vdc) = C0 + α·Vdc + β·Vdc². This parameter change allows the nonlinear characteristics to be captured through voltage-dependent coefficients (α and β) that are determined from measurements, enabling accurate simulation of nonlinear behavior while maintaining a relatively simple model structure that avoids polarity issues.
2Measurement precision
If complex equivalent circuit models are used to simulate nonlinear characteristics, then simulation accuracy improves, but ease of operation deteriorates due to difficulties in estimating circuit operations
Solution Approach 1:
The nonlinear characteristic component is extracted from the overall capacitor behavior and represented separately as a voltage-dependent capacitance function. By taking out the nonlinear aspects and representing them through simple polynomial coefficients (α and β) that are determined from measurements, the model maintains high simulation accuracy while significantly improving ease of operation. Users can easily estimate circuit operations because the nonlinear effects are captured through simple parameter adjustments rather than complex circuit topologies.
3Ease of operation
If simple equivalent circuit models are used, then ease of operation improves, but simulation precision deteriorates in high-frequency bands
Solution Approach 1:
The invention creates a composite model that combines the linear time-invariant equivalent circuit model with the nonlinear voltage-dependent capacitance model. This composite approach integrates the simplicity of linear models with the accuracy of nonlinear characterization. The linear model handles the high-frequency behavior and basic circuit operations, while the nonlinear model (C(Vdc) = C0 + α·Vdc + β·Vdc²) accurately captures the voltage-dependent effects. Together, they provide both ease of operation and high simulation precision across wide frequency bands.
Data Source
AI summary
A capacitor simulation method and nonlinear equivalent circuit model enabling dynamic simulation of nonlinear characteristics when direct-current voltage is applied with high precesion are easily provided using a simple configuration. An equivalent circuit of a capacitor is represented using a series circuit of passive circuit elements. Characteristic change ratios of the passive circuit elements when a direct-current voltage is applied are expressed as an approximate function on the basis of an actually measured value. A reference voltage is referred to by control current sources connected in parallel to the passive circuit elements. The characteristic change ratios are calculated in accordance with the reference voltage Vref. Difference currents are generated on the basis of the characteristic change ratios and currents flowing when no direct-current voltage is applied, they are caused to flow concurrently with the currents flowing when no direct-current voltage is applied, and thus the nonlinear characteristics are simulated.