Power: Current Limiter
Description
A current limiter is a power component that is able to limit the amount of current flowing through a particular wire in a network. This component will perfectly dissipate the power from the overflown current away and prevent the current from being above the limit. It can be placed in both series and parallel networks for controlling the current.
Example Use Cases
- Current Limiting: Limiting power output to particular nodes.
- Spike Prevention: Ensuring that components that are current sensitive are not damaged with spikes of current coming from the battery.
Module Implementation
The current limiter is a subclass of the Power Component and can exist in any part of the network. It contains a Current Limit, which is the maximum current that can flow through the component on the network, measured in Amps and stores a record of the Previous Current, for keeping track of the difference. The model, if the current is limited, will close the circuit and configure the current such that the current passing through is equal to the current limit, and sets the Is Limited flag to be true.
Internal Components
The current limiter contains a number of internal components to represent the functionality of a true current limiter. The resistor has its resistance set and updated every frame to the desired resistance of the component or of the power model. The minimum resistance is 1pΩ (\(10^{-12} \Omega\)).
When the current is limiting, the current limiter adds three nodes to the network. First, it connects the resistor to a current limiter current source, which is set to a constant current of the current limiting value \(I_\mathrm{limit}\). A second current source is connected to the resistor, from the same terminal, and is set to a variable value of \(I_\mathrm{shunt}\), where:
resulting in the total overflow of the current being passed through the second current source. Finally, a voltage source is connected from the resistor to the ground, which results in the original passthrough current being removed and the ‘simulated’ current being controlled by the current sources added. This voltage source will have a fixed DC voltage of 0 volts.
Once the current is no longer limiting, these components are disabled from the network and the original functionality of the pure resistor is returned.
Assumptions/Limitations
- The limiter will update the current on the next update call and currently does not work on the same frame as the power bus’s update call.
- The current limiter works by manipulating the components when the current is limited. This results in a simulated affect of a ‘grounded’ voltage source to remove the excess current from the network.