Bidirectional DC Sources / Sinks

Bidirectional DC power supplies combine a programmable DC source and an electronic DC load in a single system. They can supply a device under test (DUT) with precisely controlled DC power and absorb energy returned by it. Depending on the series, the absorbed energy is fed back into the AC mains. This enables reproducible source and sink operation without requiring separate power supplies and electronic loads.

The ET System portfolio includes the N8361F for precise bipolar and four-quadrant applications, the N35100 for compact low-voltage and high-current applications, the N35500 for high-voltage and high-power testing, and scalable BSL bidirectional DC systems. The appropriate system is selected according to voltage, current, source and sink power, operating range, dynamic response, regenerative capability, communication interfaces, and mechanical integration.

Typical applications include battery simulation, charging and discharging tests, and the validation of battery packs, onboard chargers, DC/DC converters, inverters, energy storage systems, and other power electronics. If energy flows in only one direction, a conventional programmable DC power supply or an electronic DC load may be sufficient.

How to Select a Bidirectional DC Power Supply

Selecting a suitable bidirectional DC power supply starts with the electrical requirements of the device under test (DUT) in both source and sink operation. In addition to maximum voltage, current, and power, the complete operating range, energy direction, dynamic response, regenerative capability, mains connection, interfaces, and mechanical integration should be considered.

• Voltage, current, and power in both directions: Define the required voltage, current, and power for source and sink operation. The available source and sink ratings may differ, and maximum voltage, maximum current, and maximum power may not always be available simultaneously.
• Operating range: Check the complete voltage-current operating area rather than only the maximum values. This is particularly important for battery simulation, low-voltage high-current testing, and applications with changing operating points.
• Two-quadrant or four-quadrant operation: A two-quadrant DC power supply generally operates with one voltage polarity and bidirectional current flow. A four-quadrant system supports both positive and negative voltage and current. For bipolar applications, the N8361F four-quadrant DC source may be suitable.
• Dynamic response and source-sink transition: Consider response time, current and voltage slew rates, overshoot, settling time, and the transition between source and sink operation. Programmable sequences and voltage or current profiles may be required for dynamic DUT simulation.
• Regenerative operation and mains connection: Regenerative systems return absorbed energy to the AC mains instead of converting it entirely into heat. Check the available mains voltage, frequency, input current, connection type, and the permissible regenerative power.
• Accuracy and measurement: Verify the programming and measurement accuracy for voltage, current, and power as well as resolution, ripple, noise, and data acquisition rate. These parameters are particularly important for precise battery and converter testing.
• Interfaces and automation: For automated test equipment (ATE), check the available communication interfaces, remote-control commands, sequence functions, trigger options, and software compatibility. Depending on the series, relevant interfaces may include LAN, CAN, RS232, RS485, USB, SCPI, analog control, and digital I/O.
• Application-specific functions: Battery simulation may require programmable internal resistance, voltage profiles, charge and discharge sequences, or battery simulation software. Converter and inverter testing may require fast load changes and seamless transitions between source and sink operation.
• Protection, isolation, and output behavior: Consider overvoltage, overcurrent, overpower, and overtemperature protection, interlocks, emergency shutdown, output discharge behavior, isolation between the DC output and protective earth, and suitable protection against accidental contact.
• Parallel and master-slave operation: For higher current or power requirements, verify whether the selected series supports parallel or master-slave operation. Check the maximum number of units, combined operating limits, current sharing, communication, and required DC cabling.
• Mechanical integration and cooling: Check the available rack space, installation depth, weight, airflow, cooling requirements, DC connections, and mains connection. High-power systems may require a complete cabinet solution with safety technology and power distribution.

For application-specific test benches, ET System can combine bidirectional DC power supplies, electronic loads, measurement equipment, safety components, power distribution, and control systems through test system integration. For support with selecting a suitable configuration, contact our technical sales team.