Bidirectional Battery Cell Simulators

Bidirectional battery cell simulators replace real battery cells with precisely controlled electronic channels that can both source and absorb current. This allows the electrical behavior of individual cells and complete battery packs to be reproduced under safe and defined conditions. Bidirectional operation is particularly important when testing active cell balancing, charging and discharging behavior, dynamic current profiles, and battery management systems that return energy to the simulated cells.

The ET System portfolio ranges from compact 2-channel battery cell simulators and 8-channel systems to the 24-channel N83524 and the modular N9000 platform with up to 36 isolated channels. The N8361 provides higher voltage and current for battery and consumer-electronics testing. This enables configurations for individual development tasks as well as high-density BMS, ATE, and hardware-in-the-loop (HIL) systems.

Typical applications include validating cell-voltage measurement, active balancing, state-of-charge simulation, charge and discharge behavior, AFE circuits, diagnostic functions, and dynamic BMS responses. The appropriate bidirectional battery cell simulator is selected according to channel count, voltage, source and sink current, power per channel, isolation, accuracy, dynamic response, synchronization, fault simulation, interfaces, and mechanical integration.

How to Select a Bidirectional Battery Cell Simulator

Selecting a suitable bidirectional battery cell simulator starts with the electrical architecture of the battery management system and the number of cells that must be simulated. Because every channel can source and absorb current, the requirements for both current directions, active balancing, dynamic response, isolation, accuracy, and synchronization must be evaluated.

• Number of channels: Define how many cells must be simulated simultaneously. Compact systems such as the 2-channel N8352 or 8-channel N83580 are suitable for module development and laboratory testing. The 24-channel N83524 and modular N9000 platform support complete BMS, CMS, HIL, and production test systems.
• Voltage, current, and power per channel: Define the required cell-voltage range, source current, sink current, and power for every channel. Source and sink ratings may differ. Consider normal cell operation as well as balancing currents, charging and discharging profiles, overvoltage, and undervoltage conditions.
• Active balancing and current reversal: Verify that the simulator can absorb the balancing current generated by the BMS. Check the transition between source and sink operation, current-control accuracy around zero, response time, and the maximum continuous and peak balancing current.
• Channel isolation and series connection: Check whether every channel is galvanically isolated and whether the outputs can be connected in series. Also verify the permissible channel-to-channel voltage, channel-to-ground voltage, and maximum voltage of the complete simulated battery stack.
• Accuracy, resolution, and stability: Verify programming and measurement accuracy, voltage and current resolution, temperature drift, long-term stability, ripple, and noise. The simulator should be sufficiently more accurate than the BMS measurement and diagnostic thresholds being tested.
• Dynamic response and synchronization: Check voltage and current response times, settling behavior, update rate, sequence execution, and synchronization between channels. Fast synchronized changes are particularly important for HIL tests, dynamic SOC profiles, and the simulation of sudden cell-voltage changes.
• SOC and battery-model simulation: Determine whether state-of-charge (SOC), open-circuit-voltage curves, programmable internal resistance, charge and discharge profiles, or custom voltage sequences must be simulated.
• Fault and auxiliary simulation: For BMS safety testing, define the required fault conditions. Depending on the system, relevant functions may include open-wire simulation, short circuits, overvoltage, undervoltage, connection faults, temperature-sensor simulation, insulation simulation, or complete pack-voltage simulation.
• Measurement functions: Depending on the application, integrated voltage and current measurement, leakage-current measurement, DVM channels, temperature acquisition, or external measurement modules may be required.
• Interfaces and HIL integration: Verify remote-control commands, API and driver support, software compatibility, trigger inputs, synchronization, data logging, and the available communication interfaces. For HIL applications, also check the required update rate and deterministic control behavior.
• Mechanical integration and scalability: Choose between a benchtop unit, compact multi-channel chassis, or modular 19-inch platform. Check whether additional channels, measurement modules, fault-insertion modules, temperature simulation, or pack-voltage simulation can be added later.
• Safety and cabling: Consider channel isolation, maximum system voltage, protected connectors, interlocks, emergency shutdown, reverse-polarity protection, and suitable wiring for the required source and sink currents.

If the BMS only measures cell voltages and does not return current to the simulator, an unidirectional battery cell simulator may be sufficient. You can also view the complete range of battery cell simulators.

For application-specific BMS, CMS, HIL, and end-of-line test systems, ET System can combine battery cell simulators, measurement equipment, communication modules, fault insertion, safety technology, and control software through test system integration. For support with selecting a suitable configuration, contact our technical sales team.