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R&S®Essentials | Power supplies fundamentals

How to increase output current of power supply

Author: Elizabeth McKenna, R&S Essentials Product Manager

Do you want to learn how to increase output current of your power supply? You’re in the right place. You can connect a power supply’s outputs in parallel to increase the current. You can even connect multiple power supplies in parallel for an even greater boost! This parallel configuration offers scalability, allowing the addition of more channels or power supplies to accommodate changing power requirements.

You’re working on a test setup, and suddenly you realize that you need more current than a single channel on your power supply can provide. Don’t sweat it! First, check whether the channels of your power supply are floating and galvanically isolated. Yes? Then you can connect the channels together to boost your overall current capacity. This is a nifty way to tackle those power-hungry challenges without jumping through hoops or splurging on fancy equipment.

R&S®NGA100 Power supply series

Key facts

• Max. output power: 80 W
• Max. voltage per channel: 35 V or 100 V
• Max. current per channel: 2 A or 6 A
• Up to 200 V in serial or 12 A in parallel mode with channel fusion

How to connect a power supply in parallel

Now that you’ve confirmed the independence of your power supply channels, it’s time to bring them together for some parallel connection magic. First, connect the negative terminals of the channels to create a common negative connection. Then, connect the positive terminals of the channels to form a common positive connection.

The voltage remains steady across all channels, but the currents from each channel add up! By combining the currents from individual channels, you can achieve a higher total output current. You don’t even have to worry about consistent current values for each channel. Feel free to connect two channels that each supply 5 A, and voila! You’ve got a combined total of 10 A.

All four channels of the R&S®NGP800 power supply connected in parallel

Parallel power supplies and load sharing

If you find yourself in need of even more current, you can connect multiple power supplies in parallel. Let’s take the example of two R&S®NGE102B power supplies. Each of these power supplies has two isolated and independent channels, with a maximum current rating of 3 A per channel. But what if you need more than 3 A? No worries! By connecting two power supplies in parallel, you can create a combined current capacity of 12 A.

To begin, place the two power supplies side by side on your workbench, and make sure that you have enough identical cables to connect all the channels together.

Start by connecting the output of the first channel of the first power supply to the DUT. Next, you'll need to connect the output of this channel to the output of the second channel on the same power supply. Repeat this process for the second power supply, connecting its channels in the same parallel manner. In the end, all four power supply channels will be interconnected.

Load sharing ensures that the current is distributed evenly across the power supplies, preventing any power supply from becoming overloaded while the other remains underutilized.

For a visual representation and clearer understanding of the set-up, refer to the diagram provided below.

Four channels of two R&S®NGE102B power supplies connected in parallel to the DUT

Looking at the setup shown above, you’ll notice that the voltage across all four channels and the load remains constant at 10 V. However, a whopping 12 A of current is supplied. This parallel configuration allows us to leverage the cumulative current capacity of the two power supplies, providing a substantial power boost.

Based on the equipment available in your lab, you also have the possibility of expanding further. You can connect additional channels from the same power supplies or even introduce more power supplies. This scalability gives you the freedom to adapt your setup to changing power needs.

Summary

• Connecting the outputs of a power supply in parallel increases the power supply current.
• The power supply channels must be galvanically isolated and floating to be connected in parallel.
• You can connect multiple power supplies in parallel.
• Power supply in series vs. parallel: connecting a power supply in series results in higher voltage, while connecting a power supply in parallel results in higher current.

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