Implement circuit breaker opening at current zero crossing
The Breaker block implements a circuit breaker where the opening and closing times can be controlled either from an external Simulink® signal (external control mode), or from an internal control timer (internal control mode).
A series Rs-Cs snubber circuit is included in the model. It can be connected to the circuit breaker. If the Breaker block happens to be in series with an inductive circuit, an open circuit or a current source, you must use a snubber.
When the Breaker block is set in external control mode, a Simulink input appears on the block icon. The control signal connected to the Simulink input must be either 0 or 1 (0 to open the breaker, 1 to close it).
When the Breaker block is set in internal control mode, the switching times are specified in the dialog box of the block.
When the breaker is closed, it is represented by a resistance Ron. The Ron value can be set as small as necessary in order to be negligible compared with external components (a typical value is 10 mohms). When the breaker is open, it has an infinite resistance.
The arc extinction process is simulated by opening the breaker device when its current passes through 0 at the first current zero crossing following the transition of the Simulink control input from 1 to 0.
The Breaker closes when
Control signal goes to 1 (for discrete systems, control signal must stay at 1 for at least 3 times the sampling period)
The Breaker opens when
Control signal goes to 0
Breaker current passes through 0
Note The Breaker block may not be the appropriate switching device to use for DC circuits. For such applications, it is recommended that you use the Ideal Switch block as a switching device.
The initial state of the breaker. A closed contact is displayed
in the block icon when the Initial status parameter
is set to
1, and an open contact is displayed when
it is set to
If the breaker initial state is set to 1 (closed), the software automatically initializes all the states of the linear circuit and the Breaker block initial current, so that the simulation starts in steady state.
Specifies the vector of switching times when using the Breaker
block in internal control mode. At each switching time the Breaker
block opens or closes depending on its initial status. For example,
if the Initial status parameter is
the breaker closes at the first switching time, opens at the second
switching time, and so on. The Switching times parameter
is not available if the External check
box is selected.
If selected, adds a Simulink input to the Breaker block
for external control of the switching times of the breaker. The switching
times are defined by a logical signal (
connected to the Simulink input.
The internal breaker resistance, in ohms (Ω). The Breaker resistance Ron parameter cannot be set to 0.
The snubber resistance, in ohms (Ω). Set the Snubber resistance Rs parameter to
eliminate the snubber from the model.
The snubber capacitance, in farads (F). Set the Snubber capacitance Cs parameter to
eliminate the snubber, or to
inf to get a resistive
Branch voltage to measure the voltage
across the Breaker block terminals.
Branch current to measure the current
flowing through the Breaker block. If the snubber device is connected
to the breaker model, the measured current is the one flowing through
the breaker contacts only.
and current to measure the breaker voltage and the breaker
Place a Multimeter block in your model to display the selected measurements during the simulation.
In the Available Measurements list box of the Multimeter block, the measurement is identified by a label followed by the block name:
When the block is connected in series with an inductor or another
current source, you must add the snubber circuit. In most applications
you can use a resistive snubber (Snubber capacitance parameter
inf) with a large resistor value (Snubber resistance parameter set to
so). Because of modeling constraints, the internal breaker inductance
Ron cannot be set to 0.
You must use a stiff integration algorithm to simulate circuits
with the Breaker block.
ode23tb with default parameters
usually gives the best simulation speed.
For discretized models, the control signal must stay at 1 for a minimum of 3 sampling time periods to correctly close the Breaker block, otherwise the device stays open.