Load Profiles With List Function
The electronic load is able to simulate load profiles using the list function and to record current and voltage simultaneously at different intervals. This is possible in all four operating modes current (CC), power (CP), resistance (CR) and voltage (CV).
The list function can also be integrated in the discharge function. In this way, an energy storage device can be discharged not only statically but also in a pulsed manner.
Terminology
Load profile
A load profile consists of a consecutively chained set of setting values building a continuous function (current, resistance, power, voltage). The title picture above shows a constant current load profile.
Setting list
This list is used to define a load profile and contains the settings for the corresponding operating mode. A value in the list represents the setting that is controlled in LIST mode during the dwell time (see below).
List mode
The list mode defines the basic operating mode that is active when the list is executed and selects the corresponding setting list.
List of ramp times
This list belongs to the definition of a load profile. A value in the list represents the time taken for the increase/decrease to the corresponding next setting.
List of dwell times
This list also belongs to the definition of a load profile. A value in the list represents the time period for which the corresponding setting is kept constant.
List of sample times in ramps
This list defines the measuring intervals for the corresponding ramps. If you do not need the measurement data acquisition, this list is not required.
List of sample times in dwells
This list defines the measuring intervals for the corresponding retention times. If you do not need the measurement data recording, this list is not required.
List set
A list set consists of the lists for the load profile (settings, ramp times, dwell times) and the lists for the sample times. The elements with identical index in the individual lists (of a list set) define a single section of the load profile.
List count
The number of passes determines how often the complete list set is executed after starting.
Measurement data set, measurement data point
A measured data point is a set of three measured values consisting of timestamp, voltage value and current value. When a measurement dataset is read out, these three values are separated from each other by a comma followed by a space.
A valid list set consists of at least three lists of equal length:
1. level list
2. ramp time list
3. dwell time list
When changing the operating mode (CC, CP, CR, CV), the user must update the lists for ramp times, dwell times and, if necessary, sampling times of the new list mode.
Execution of the List Function
The list function can be activated with the corresponding SCPI command, locally via the user interface or by a trigger event. The execution of the list starts as soon as the load input is active or a trigger event occurs. The device automatically switches to the list mode.
If the load input is switched off during list execution, the load interrupts the list execution and continues it when the load input is switched on again. After a list has been executed or aborted, the device switches back to the previously set basic operating mode with the associated setting.
Data Acquisition with the List Function
Synchronously to the execution of a list, the electronic load can store measurement data records with a variable sampling rate in the internal memory. There is an associated sampling rate for each list section. When data recording is activated, voltage and current are measured synchronously and stored with an associated time stamp.
The internal device memory has series-related different capacities. A data set consists of time stamp, voltage value and current value. When the end of the available data memory is reached, the new data overwrites the older data according to the ring buffer principle.
The stored data sets can be read from the electronic load one by one or in blocks.
Static measurement data acquisition cannot be performed during a running list if the data acquisition of the list function is active. It is not possible to execute a list simultaneously with the MPPT function or with the internal resistance measurement. However, the discharge function and list function can be combined.