Battery Cycler - Testing of High-Voltage Batteries
Safe and efficient measuring of high-performance batteries
The test equipment specially developed for this purpose, known as a battery cycler, analyzes the battery function. The performance of the battery during the charging and discharging cycles are measured over time.
Energy Storage/Electric Vehicle
Sector
Analyzing of charging and discharging process or checking the correct state of charge of an electric vehicle before delivery
Application
Voltages up to 2000 V DC (and above)
Measured Parameter/Signal converted/isolated
Key requirements
- Selectable DC measurement settings ( to 2000 VDC)
- DC current measurement (by way of shunt voltage)
- Accurate conversion to standard control signals
- Safety through full isolation of dangerous voltages seen between battery and testing hardware
- Configurable frequency response (10 Hz to 10 kHz)
Application Description
During battery testing, charge and discharge processes, (the battery cycles), are continuously simulated on the battery in a HIL (hardware in the loop) configuration, corresponding to typical usage profiles during operation of the electric vehicle. A number of parameters are measured, including capacity, battery efficiency and self-discharge.
The schematic shows that there are three main areas for Knick products:
- “Equalization voltage” – this ensures that the battery is at the same voltage as what is seen in the cycler. Once equalization occurs, the switch is closed between battery and cycler so that charging/discharging processes can be run.
- Communication of battery cycler voltage and current to DAQ (data acquisition) or PLC. This is for additional visibility for the end user.
- Internal to the battery cycler equipment is a DC drive. This is shown in the schematic by way of a breakout box. Here, transducers help with the very important “voltage and current feedback” applications. These products feed control signals back into the DC drive, representing the voltage and current that is actually being delivered.
This helps to ensure that there is a match between what the drive thinks it is producing and what is actually being produced and additionally, that a short-circuit is not present.
Requirements of Application
Precise and fast DC voltage and current measurements at the battery cyclers are essential for effective function. Safety function for the operating personnel and the measuring equipment must always be ensured, as the voltages seen in these applications are ever increasing; currently to 2000 V DC.
If, in addition, the installation space in the control cabinet is limited – which is often the case with testing equipment in production environments – and if many battery cells are to be tested simultaneously, the form factor of the high-voltage transducer also comes into play. Small overall width and easy mounting on the DIN rail are the decisive factors here.
Solution - Product Highlight
The Knick P42000 high-voltage transducer is designed for measurements on circuits in power electronics and safely converts voltages up to 2000 V DC into standard output signals of ±20 mA, ±10 V or 4 … 20 mA. The device has performance features that have been proven in many other high-voltage applications from the field of power generation, making it suitable for demanding energy storage and e-mobility applications.
The Knick P41000 high-voltage transducer measures DC currents up to 20 kA in conjunction with a shunt. Continuous isolation is provided up to 3.6 kV. Shunt voltages, (i.e. +/- 50 mV, 60 mV, 100 mV) are converted into standard output signals of +/- 20 mA, +/- 10 V or 4 … 20 mA. It’s high performance specifications makes it a perfect fit for critical energy storage and e-mobility applications.