Component 158: Battery

In This Topic

Component 158: Battery

Specifications

Line Connections
1	Power Inlet (optional, for series connection of batteries)
2	Power connection (> 0 for discharge, < 0 for charge)
3	Power Loss
4	Connection to aging module
5	Control inlet (to control the operating mode

General User Input Values Physics Used Characteristic Lines Results Display Example

General

This component represents a battery consisting of individual cells with a nominal capacity CCELLN and a nominal voltage UCELLN. The actually available capacity decreases according to a factor SOH (state of health) that is specified to the battery by the aging module via Logic Pin 4. The prevailing state of charge of the cell SOC must remain between the limits SOCMIN and SOCMAX.

The component Battery consists of NBANK banks connected in parallel that consist of NRACK racks connected in parallel in each case. Each rack consists of NMOD modules connected in series. Each module consists of NPAR * NSER modules (connected per NPAR in parallel and NSER in series).

When discharging the battery, the terminal voltage decreases under its nominal value down to a minimum value UCOCELL (cut-off voltage). Here the current can rise up to the short circuit current ISCCELL.

The terminal voltage as a function of the discharge current and of the state of charge (SOC) is defined by a characteristic field CUACT that consists of 20 characteristic lines with the prevailing state of charge as parameter. Instead of the characteristic field, it is also possible to calculate with a constant internal resistance of the cell, which can optionally be specified directly or can be calculated from the short circuit current.

The component can be applied both in electric circuits, where it calculates the current based on the resistances in the electric circuit, and in control loops that require the current to be specified externally. It is also possible to define the current by specifying the desired power on Logic Inlet 5.

To display the aging of the battery, an external aging module has to be connected to Logic Inlet 4. Via this logic inlet, the battery receives its respective prevailing SOH (”state of health“) from the aging module. It is defined as the ratio of the current to the original capacity of the battery. The aging module, in turn, can access the the data of the battery via this logic pin and calculate the aging.

Pins

In most Ebsilon components, the fluid flows into the component via Pin 1 and out of the component via Pin 2. In the case of the component Battery, however, the same pin (namely Pin 2) is used for charging and for discharging.

As, topologically, it is an outlet, positive values are displayed for the power when discharging. The charging process is displayed by means of negative values. On the one hand, this is closer to reality (as in reality the same cables are used for charging and discharging) and on the other hand it facilitates the modeling.

Nevertheless, there is also an electric inlet (Pin 1) in this component, which, however, is optional and not used for charging but for connecting another battery. This way, several Components 158 can be connected in series. In doing so, the voltages will add up while the current remains the same through all batteries. With the exception of the last one, all batteries must be operated in the mode FOP=-1 (“Current given externally“) as the last battery carries out the calculation for the overall package and writes the current onto the line.

Pin 3 is a logic outlet for the losses. These are calculated by the battery. Here both the losses occurring in the battery and the power required for the cooling can be considered (see Chapter FLOSS-Loss Calculation).

Pin 4 is the logic inlet for the connection of the aging module: via this connection, the aging module receives the required data of the battery. The aging module calculates the new SOH (state of health) at the end of the respective time step and communicates it to the battery via the logic line at the beginning of the next time step.

Pin 5 is the logic inlet for the control. The desired power is specified on this line. When the battery is to be charged, a negative value has to be specified. Whether the desired power can be achieved depends both on the state of charge of the battery and on the current:

If the level of the battery drops below SOCMIN, the discharge current will be set to 0 in steady state. In transient state, either the power can be reduced or the time interval can be shortened (see FTIMELIM - behaviour when Reaching the Limits).
If the level of the battery exceeds SOCMAX, the charging current will be set to 0 in steady state. In transient state, either the power can be reduced or the time interval can be shortened (see FTIMELIM - behaviour when Reaching the Limits).
If the charge rate CRATE is exceeded by the required current, the current is reduced so far that a charge rate of CRATE is adhered to (see Specification Values for the
Operation).
If the discharge rate DCRATE is exceeded by the required current, the current is reduced so far that a discharge rate of DCRATE is adhered to (see Specification Values for the Operation).

Flags

FOP - Operation Mode:

FOP=-1: Current given externally
Here the voltage results from the internal resistance of the battery cells and the characteristic field respectively (see 1.1.1.3.2). When discharging (I>0), the voltage decreases with increasing current. When charging (I<0), increasing the voltage is required for increasing the current.
FOP= 0: Out of order
Current and voltage are set to 0 in this case.
FOP= 1: Charging: the voltage is specified externally, the current is calculated via the internal resistance or via the characteristic field (see 1.1.1.3.2). Here the applied voltage must be greater than the nominal voltage of the battery.
FOP=2: Discharging: voltage and current are calculated from the resistance in the electric circuit.
FOP=3: Power control according to power demand on Pin 5

FUTHERM - Method for Calculating the Terminal Voltage:

This flag serves to define the correlation between terminal voltage and current. By default, the calculation is effected with a constant internal resistance. However, it is also possible to store a characteristic field.

FUTERM=0: the internal resistance of the cell is specified directly in RINTCELL.
FUTERM=1: the internal resistance of the cell is calculated from the short circuit current ISCCELL.
FUTERM=2: the internal resistance of the cell is calculated from the maximum power QMAX.
FUTERM=3: the terminal power is determined from the characteristic field FCUTERM as a function of the current and the state of charge of the battery.

FLOSS - Loss Calculation:

Losses are calculated by the component itself and are written as heat on Logic Outlet 3. There are the following variants for calculating the losses that occur during the operation of the battery:

FLOSS=0: Heat loss calculated from voltage and current:

QLOSSOP = (UTOTN – U2) * I2

Please note that the loss becomes positive at all times because while charging I2 < 0 and U2 > UTOTN.

FLOSS=1: Heat loss proportional to the power: QLOSSOP = LOSS * |Q2|
FLOSS=2: Heat loss proportional to the current: QLOSSOP = LOSS * |I2|

Here U2, I2 and Q2 are voltage, current and power at the outlet and the proportionality factor LOSS is a specification value.

Moreover, for the losses it is also possible to consider the auxiliary power QLOSSC of the air conditioner required for cooling the batteries. As it depends on the ambient temperatures, there is a characteristic line CQLOSSC for this purpose. This characteristic line is used both in the design case and in off-design. Therefore the design temperature of the air conditioner (i.e. the temperature where the characteristic line has the value 1) does not have to be consistent with the design case of the overall model.

It is assumed that the air conditioner can be operated independently of the battery. Therefore the auxiliary power is also calculated when the battery is turned off.

FTIMELIM - behaviour when Reaching the Limits:

This flag allows to set the behaviour for a transient calculation, e.g. in the context of a time series.

Within the time step, the component carries out a steady-state calculation as a rule, i.e. no time dependencies are considered. Only when calculating the result values SOCNEW (new state of charge at the end of the time step) and DCHARGE (change of charge in the time step) does a time dependency come into play.

As long as SOCNEW is within the valid range between SOCMIN and SOCMAX, FTIMELIM has no effect. However, if SOCNEW exceeds a limit, there are the following options:

FTIMELIM=0: the power is reduced so far that the limit is only reached at the end of the time step.
FTIMELIM=1: the power is left unchanged but the time interval is shortened, i.e. in the time series table an additional line is inserted with the point in time when the limit is reached.

In both cases, SOCNEW is then set to the respective limit value (SOCMIN or SOCMAX).

When carrying out a time series calculation, after calculating a time step the result value SOCNEW is then copied onto the specification value SOC for the next time step.

Note: No FMODE

A flag FMODE for switching over between design and off-design mode does not exist in this component as there are no nominal values for this component that might be calculated by Ebsilon in the context of a design calculation.

Notes for Specification Values

Specification Values for the Operation

These specification values are only relevant for the operation with power demand (FOP=3).

CRATEN: nominal value for the charge rate (CRATE)

The charge rate indicates the proportion of the capacity per time unit that is charged and discharged respectively. For instance: at a CRATE of 0.5 A/Ah, the SOC (state of charge) of the battery is increased and decreased respectively by 0.5 in one hour.

The charge rate results from the nominal value CRATEN and the characteristic line CCRATE as a function of the state of charge. By default, this characteristic line is designed is such a way that the charge rate is already reduced when approaching SOC=1.

DCRATEN: nominal value for the discharge rate (DCRATE) (optional)

Only enter a value here if another rate is to be used for discharging than for charging. Otherwise the discharge rate is equated with the charge rate.

STHR: threshold value for charging

Here you can enter a threshold value that has to be exceeded for the battery to switch over to “Charge” mode.

Specification Values for the Geometry

NPAR: number of parallel cells per module

NSER: number of serial cells per module

NMOD: number of modules per rack

NRACK: number of racks per bank

NBANKS: number of banks in the component

Specification Values for Capacity and Voltage

UCELLN: nominal voltage of a cell

CCELLN: nominal capacity (maximum charge) of a cell

RINTCELL: internal resistance of a cell

ISCCELL: short circuit current (max. possible current) of a cell

QMAX: maximum power of the total battery

Specification Values for the State

SOC: current state of charge

SOCMIN: min. admissible state of charge

SOCMAX: max. admissible state of charge

The “state of health“ (SOH) is not managed in the battery but in the aging module. The battery only shows in the result values which SOH the calculation
was carried out with.

Specification Values for the Loss Calculation

LOSS: loss factor (proportionality factor at FLOSS=1 or 2)

QLOSSCN: nominal value for the power of the air conditioner
This value is multiplied by the value of the characteristic line CQLOSS which depends on the ambient temperature.

TAMB: ambient temperature (for FSTAMB=0)

ISUN: link to Component 117 (for FSTAMB=1)

Notes for Result Values

Result Values for the Operation:

RCRATE: applied charge and discharge rate respectively

UCELL: present voltage of a cell

UTOT: present total voltage

ICELL: present current through a cell

ITOT: present total current

QTOT: total battery power

Result Values for the State:

SOCNEW: new state of charge at the end of the time step

SOH: state of health used for the calculation

CTOT: total capacity at the current state of health

DCHARGE: change of charge during the time step

DCHARGECTOT: Charge change relative to total capacity

Result Values for the Loss Calculation:

RTAMB: applied ambient temperature

QLOSSOP: loss due to the operation of the battery

QLOSSC: loss due to the air conditioner

QLOSSTOT: total loss

Other Result Values :

UTOTN: nominal voltage of the total battery

UUN: ratio of present to nominal voltage

IISC: ratio of present to short circuit current

RRINTCELL: used internal resistance, one cell

RRINTTOT: used internal resistance of the total battery

RQMAX: calculated maximum power of the battery
This result value is calculated from the internal resistance assuming that it is constant. If this is not the case (possible at FUTERM=3), this value is
only an approximation.

QQMAX: Ratio actual power / maximum power

Characteristic Lines and Characteristic Fields

CRATE: relative charge rate as a function of the state of charge

CQLOSSC: Relative power of the air-conditioning system as a function of the ambient temperature

FCUTERM: Characteristic diagram consisting of characteristic curves CUTERM_n for the relative terminal voltage as a function of the relative cell current intensity (referred to the short-circuit current ISCCELL) with the state of charge SOC as parameter.

User Input Values

FOP	Flag: Operation mode Like in Parent Profile (Sub profile option only) Expression = -1: current given externally = 0: out of order = 1: charge (voltage given externally, current calculated from resistance) = 2: discharge (voltage and current calculated from resistance) = 3: according to power demand on pin 5
CRATEN	Charge rate (nominal)
DCRATEN	Discharge rate (nominal) (optional, if different from CRATE)
STHR	Switching threshold for charging
NPAR	Number of parallel cells per module
NSER	Number of serial cells per module
NMOD	Number of modules per rack
NRACK	Number of racks per bank
NBANK	Number of banks
UCELLN	Nominal voltage of cell
CCELLN	Nominal capacity (maximum charge) per cell
FUTERM	Flag: Method for calculation of terminal voltage Like in Parent Profile (Sub profile option only) Expression = 0: use constant internal resistance RINTCELL = 1: use constant internal resistance calculated from ISCCELL = 2: use constant internal resistance calculated from QMAX = 3: by characteristic field FCUTERM
RINTCELL	Internal resistance of cell
ISCCELL	Short circuit current per cell
QMAX	Maximum power of total battery
SOC	Present state of charge
SOCMIN	Minimum state of charge
SOCMAX	Maximum state of charge
FTIMELIM	Flag: Handling of limit achievement in time interval Like in Parent Profile (Sub profile option only) Expression = 0: Reducer power to avoid exceeding limit = 1: Split time interval
FLOSS	Flag: Switch for heat losses Like in Parent Profile (Sub profile option only) Expression = 0: heat loss calculated from voltage and current = 1: heat loss proportional to power (Q3=LOSSQ) = 2: heat loss proportional to current (Q3=LOSSI)
LOSS	Factor for heat losses
QLOSSCN	Flag: Handling of limit achievement in time interval Like in Parent Profile (Sub profile option only) Expression = 0: reduce power to avoid exceeding limit = 1: split time interval
FSTAMB	Definition of ambient temperature Like in Parent Profile (Sub profile option only) Expression =0: Given by parameter TAMB =1: Given by component 117 with index ISUN
TAMB	Ambient temperature
ISUN	Index for solar and ambient Parameters

Results

RCRATE	Applied change rate
UCELL	Terminal voltage of cell
UTOT	Total voltage
ICELL	Present current of cell
ITOT	Total current
QTOT	Total battery power
SOCNEW	New state of charge
SOH	Applied state of health
CTOT	Total capacity at current health state
DCHARGE	Charge change during time step
DCHARGETOT	Charge change relative to total capacity
RTAMB	Ambient temperature used in calculation
QLOSSOP	Loss by operation
QLOSSC	Loss by air conditioning
QLOSSTOT	Total loss
UTOTN	Nominal voltage of total battery
UUN	Ratio actual voltage / nominal voltage
IISC	Ratio actual current / short circuit current
RRINTCELL	Used internal resistance off cell
RRINTTOT	Used internal resistance off total battery
NPARTOT	Used total number of parallel units
NSERTOT	Used total number of serial units
RQMAX	from RINTTOT calculated maximum power
QQMAX	Ratio actual power / maximum power

Characteristic Lines / Characteristic Diagrams

Characteristic Lines

Characteristic Line 1 to N: CRATE : Relative charge rate depending on State of charge: CCRATE : CRATE / CRATEN = f (SOC)

     X-axis       1         SOC                             1st point
                      2         SOC                             2st  point
                      .
                      N        SOC                             last point

     Y-axis       1         CRATE/CRATEN           1. point
                      2        CRATE/CRATEN         2. point
                       .
                      N        CRATE/CRATEN          last point

Characteristic Line 1 to N: CQLOSSC: Relative performance of the air conditioning system depending on the ambient temperature:
CQLOSSC: QLOSSC / QLOSSCN = f (TAMB)

     X-axis       1         TAMB                           1st  point
                      2         TAMB                           2st  point
                       .
                      N         TAMB                          last point

     Y-axis       1         QLOSSC/QLOSSCN     1st point
                      2         QLOSSC/QLOSSCN     2st point
                       .
                      N         QLOSSC/QLOSSCN     last point

Characteristic Diagram

Characteristic Diagram 1 to N: FCUTHERM : Characteristic Diagram , consisting of characteristic lines CUTHERM_n for the relative terminal voltage as a function
of the relative cell current (in relation to the short circuit current ISCCELL) with the state of charge SOC as parameter
FCUTHERM : CUTHERM1: UCELL/UCELLN = f( ICELL / ISCELL, param = SOC

CUTHERM_1:

     X-axis       1         ICELL/ ISCCELL                             1. point,  param= SOC 0.05...1,0
                      2         ICELL/ ISCCELL                             2. point, param=...
                                          .
                      N        ICELL/ ISCCELL                             last point , param=...

     Y-axis       1         UCELL/UCELLN                           1. point,  (ICELL/ISCELL)
                      2         UCELL/UCELLN                           2. point, ...
                       .
                      N        UCELL/UCELLN                           last point, ...

Physics Used

Display

	Display Option 1		Display Option 2
	Display Option 3		Display Option 4
	Display Option 5		Display Option 6
	Display Option 7		Display Option 8

Example

Click here>> Component 158 Demo << to load an example.

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