Battery_modelling Simulink

Battery - Implement generic battery model Library Electrical Sources, Electric Drives/Extra Sources Description The Battery block implements a generic dynamic model parameterized to represent most popular types of rechargeable batteries. The equivalent circuit of the battery is shown below: Lead-Acid Model Discharge model (i* > 0) Charge Model (i* < 0) Lithium-Ion Model Discharge Model (i* > 0) Charge Model (i* < 0) Nickel-Cadmium and Nickel-Metal-Hydride Model Discharge Model (i* > 0) Charge Model (i*< 0) where, EBatt= Nonlinear voltage (V) E0= Constant voltage (V) Exp(s) = Exponential zone dynamics (V) Sel(s) = Represents the battery mode. Sel(s) = 0 during battery discharge, Sel(s) = 1 during battery charging. K = Polarization constant (Ah-1) or Polarization resistance (Ohms) i* = Low frequency current dynamics (A) i = Battery current (A) it = Extracted capacity (Ah) Q = Maximum battery capacity (Ah) A = Exponential voltage (V) B = Exponential capacity (Ah)-1 The parameters of the equivalent circuit can be modified to represent a particular battery type, based on its discharge characteristics. A typical discharge curve is composed of three sections, as shown in the next figure: The first section represents the exponential voltage drop when the battery is charged. Depending on the battery type, this area is more or less wide. The second section represents the charge that can be extracted from the battery until the voltage drops below the battery nominal voltage. Finally, the third section represents the total discharge of the battery, when the voltage drops rapidly. When the battery current is negative, the battery will recharge following a charge characteristic as shown below: Note that the parameters of the model are deduced from discharge characteristics and assumed to be the same for charging. The Exp(s) transfer function represents the hysteresis phenomenon for the Lead-Acid, NiCD and NiMH batteries during charge and discharge cycles. The exponential voltage increases when battery is charging, no matter the SOC of the battery. When the battery is discharging, the exponential voltage decreases immediately: Dialog Box and Parameters Parameters Tab Battery type Provides a set of predetermined charge behavior for four types of battery: Lead-Acid Lithium-Ion Nickel-Cadmium Nickel-Metal-Hydride Nominal Voltage (V) The nominal voltage (Vnom) of the battery (volts). The nominal voltage represents the end of the linear zone of the discharge characteristics. Rated Capacity (Ah) The rated capacity (Qrated) of the battery in ampere-hour. The rated capacity is the minimum effective capacity of the battery. Initial State-Of-Charge (%) The initial State-Of-Charge (SOC) of the battery. 100% indicates a fully charged battery and 0% indicates an empty battery. This parameter is used as an initial condition for the simulation and does not affect the discharge curve (when the option Plot Discharge Characteristics is used). Use parameters based on Battery type and nominal values Load the corresponding parameters in the entries of the dialog box, depending on the selected Battery type, the Nominal Voltage and the Rated Capacity. When a preset model is used, the detailed parameters cannot be modified. If you want to modify the discharge curve, select the desired battery type to load the default parameters, and then uncheck the Use parameters based on Battery type and nominal values checkbox to access the detailed parameters. Maximum Capacity (Ah) The maximum theoretical capacity (Q), when a discontinuity occurs in the battery voltage. This value is generally equal to 105% of the rated capacity. Fully charged Voltage (V) The fully charged voltage (Vfull), for a given discharge current. Note that the fully charged voltage is not the no-load voltage. Nominal Discharge Current (A) The nominal discharge current, for which the discharge curve has been measured. For example, a typical discharge current for a 1.5 Ah NiMH battery is 20% of the rated capacity: (0.2 * 1.5 Ah / 1h = 0.3A). Internal Resistance The internal resistance of the battery (ohms). When a preset model is used, a generic value is loaded, corresponding to 1% of the nominal power (nominal voltage * rated capacity of the battery). The resistance is supposed to be constant during the charge and the discharge cycles and does not vary with the amplitude of the current.