Battery CC-CV
Libraries:
Simscape /
Battery /
BMS /
Current Management
Description
The Battery CC-CV block implements a constant-current (CC), constant-voltage (CV) charging algorithm for a battery. For a discharging battery, the block uses the value of the CurrentWhenDischarging input port. To implement a simpler version of the CC-CV charging algorithm with proportional control, see the CC-CV Charging (Proportional Control) block.
This block supports single-precision and double-precision floating-point simulation.
Note
To enable inherited single-precision floating-point simulation, the data type of all
inputs and parameters, except for the Sample time (-1 for
inherited) parameter, must be single.
You can switch between continuous and discrete implementations of the block by using
the Sample time (-1 for inherited) parameter. To configure the
block for continuous time, set the Sample time (-1 for
inherited) parameter to 0. To configure the block for
discrete time, set the Sample time (-1 for inherited)
parameter to a positive, nonzero value, or to -1 to inherit the
sample time from an upstream block.
Note
Continuous-time implementation of this block works only in a double-precision floating-point simulation. If you provide single-precision floating-point parameters and inputs, this block casts them to double-precision floating-point values to prevent errors.
This diagram illustrates the overall structure of the block:
Equations
This block implements the CC-CV algorithm in constant-current and constant-voltage modes. This figure shows the operation of these modes:
This equation defines the battery reference current that the block outputs:
where
vmax is the value of the Cell voltage threshold (V) parameter.
vmeas is the voltage of the highest cell.
Kp and Ki are the values of the Controller proportional gain and Controller integral gain parameters.
Examples
Battery Charging and Discharging
Use a constant current and constant voltage algorithm to charge and discharge a battery. The Battery CC-CV block is charging and discharging the battery for 10 hours. The initial state of charge (SOC) is equal to 0.3. When the battery is charging, the current is constant until the battery reaches the maximum voltage and the current decreases to 0. When the battery is discharging, the model uses a constant current.
Battery Passive Cell Balancing
Balance a battery with two cells connected in series by using a passive cell balancing algorithm. The initial state-of-charge (SOC) for the two cells are equal to 0.7 and 0.75. The balancing procedure depends on the cell voltages. Alternatively, you can use the SOC values for balancing. When the balancing is active, a bleeding resistor switches on to bleed the cells with higher charge. You can use the objects and functions in the Battery Pack Model Builder to generate more complex battery packs.
Balance Battery Cells with Switched Capacitor Method
Balance a battery with two cells connected in series by using the switched-capacitor (SC) strategy for active cell balancing. For shuttling the energy between the battery cells, this method uses capacitors as external energy storage elements. To balance N cells, the SC method requires N-1 capacitors and 2*N bidirectional switches. The control strategy has two states only and can work in charging and discharging modes. The initial state of charge (SOC) is 0.7 for one cell and 0.75 for the other. To generate more detailed battery packs, use the objects and functions in the Battery Pack Model Builder.
Charge and Discharge Module Assembly with Coolant Control
Perform a charging and discharging cycle on a battery module assembly while monitoring the cell temperature and enabling cooling.
Perform Controlled Charging and Discharging on Battery Module
Perform a cyclic charge and discharge profile on a battery module by using the Battery CC-CV block. At the start of the simulation, the battery module has a state of charge (SOC) of 10%. The Battery CC-CV block performs a constant-current (CC) charging until it reaches the limit cell voltage of 4.1 V specified in the Maximum cell voltage (V) parameter. The block then charges the battery with a constant-voltage (CV) profile until the module SOC reaches 90%. Finally, the block starts a CC discharging procedure and discharges the module until the SOC reaches the initial value of 10%. The charge and discharge cycle then restarts.
