Power Node Model

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Description

The Power Node Model can be added to any Physical Object on an entity, and it can be used as part of the Power Bus. It allows for current and voltage to be calculated for the node and serves as the foundation for all power-related components in the simulation system.

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Example Use Cases

• Power Component Integration: Add power functionality to any physical component, allowing it to participate in the power network.
• Circuit Analysis: Calculate voltage, current, and power values across components in an electrical circuit.
• Power System Design: Create complex power networks with various components interacting through a shared power bus.

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Module Implementation

The Power Node Model implements the core functionality needed for power calculations within a network. It tracks voltage and current values at both input and output terminals, and calculates power consumption.

Voltage Calculation

When connected to a Power Bus, the bus solver computes the node voltages and currents. When operating standalone with SelfSolve enabled, the model calculates the voltage drop across the node using Ohm’s law:

$$V_{\text{node}}=I_{\text{in}}\cdot R$$

The output voltage is then:

$$V_{\text{out}}=V_{\text{in}}-V_{\text{node}}$$

By default, current is conserved through the node ($I_{\text{out}}=I_{\text{in}}$) unless the parent component implements custom current behavior.

Power Calculation

The power dissipated by the node is calculated using:

$$P=R\cdot I_{\text{eff}}^2$$

where $I_{\text{eff}}$ is the effective series current through the element. This calculation method provides more accurate results than using voltage multiplied by current, especially for power sources with resistance.

The NetPower property calculates the power delivered to or from the bus:

$$P_{\text{net}}=V_{\text{out}}\cdot I_{\text{out}}-V_{\text{in}}\cdot I_{\text{in}}$$

A positive net power indicates the node is supplying power to the bus (e.g., a discharging battery or solar panel), while a negative value indicates the node is consuming power from the bus.

Parameters

The model includes the following key parameters:

• SelfSolve: A flag that determines if the Power Node Model should update output parameters itself when not connected to a Power Bus. This is an advanced setting that enables standalone operation.
• IsOpenCircuit: A flag that indicates whether the power node is currently open, preventing power transfer to the next component.
• VoltageIn: The input voltage of the node in Volts.
• VoltageOut: The output voltage of the node in Volts.
• VoltageNode: The voltage drop across the node in Volts.
• CurrentIn: The input current of the node in Amperes.
• CurrentOut: The output current of the node in Amperes.
• Resistance: The resistance of the node in Ohms. A minimum value of $10^{-12}\Omega$ is enforced to prevent numerical issues.
• Power: The power dissipated by this node in Watts.
• NetPower: The net power contribution to the bus in Watts (positive = supplying, negative = consuming).

NOTE

The Power Node Model is the foundational model for all power components in the system. More specialized models like the Camera Power Model, Computer Power Model, and Sensor Power Model all build upon this base model by adding specific functionality while retaining the core power calculations.

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Assumptions/Limitations

• The model assumes that all components follow standard electrical circuit principles.
• When not connected to a power bus, the SelfSolve flag must be set to true for the model to update its output parameters.
• The model uses a simplified representation of electrical behavior when self solving that may not capture all aspects of real-world power systems.
• A minimum resistance value of $10^{-12}\Omega$ is enforced to prevent numerical instabilities.
• When the circuit is open, all voltage and current values are cleared to zero.