Perform More Tests and Increase Throughput with High-Power, 3-Channel Bidirectional Power Supplies

They are common challenges every test engineer is likely to face at some point: production demand is outpacing the capability of your test system, or you need to test more parameters simultaneously. Until now, you have needed to build more test systems requiring more test equipment. That has been true for high power applications in which multiple DC power supplies are required.

Applications include:

• Testing a solar panel set with multiple inverters and with battery backup
• Simultaneous powering and testing multiple electric vehicle (EV) propulsion and sensing/control subsystems
• Necessity for multiple power instruments to test power DC-DC converters

Sound familiar? Advanced technology is increasing the demand for high power DC power supplies for so many applications.

Now, EA Elektro-Automatik has a solution for these challenges. The EA-PSB 20000 Triple series of 15 kW and 30 kW, 3-channel Programmable Bidirectional DC Power Supplies provide three independent, isolated, 2-quadrant instruments that can either source or sink power (Figure 1). Instead of two independent instruments to provide input power and a load to a device-under-test (DUT), a single EA-PSB 20000 channel can act as the source, and a second channel can act as the load. The 3-channel EA-PSB series eliminates the need for multiple power supplies and loads and saves costs and test rack space.

Figure 1. Front and rear panels of an EA-PSB 20000 Programmable Bidirectional Power Supply. The rear panel shows the connections for the three independent power supplies. 

No compromise on DC programmable power testing

Even though the EA-PSB 20000 power supplies consist of three channels in one instrument enclosure, each channel possesses abundant power. The EA-PSB 20000 3U models have three 5kW channels. Six models offer outputs (inputs) ranging from 0 – 60 V with 170 A/channel to 0 – 920 V with 0 to 20 A/channel. The EA-PSB 20000 4U models have double the power with 10 kW/channel. The channels of the 4U models have similar voltage ranges with double the current capacity. Maximum current capacity ranges from 340 A/channel for the 60 V supply to 40 A/channel with the 920 V supply. Output capacity is not limited to the maximum power of a channel; paralleling the channels can increase capacity up to 15 kW for the 3U supply and 30 kW for the 4U supply.  

When a test system requires higher power capacity, test designers can parallel as many as eight EA-PSB 20000 series supplies to generate up to 240 kW. A system of 15 kW supplies creates a maximum of 120 kW, with a maximum current capacity of 1360 A/channel or a total of 4080 A if all 24 individual channels are connected in parallel. Eight 30 kW supplies in parallel can create 240 kW with up to 2720 A/channel. Combining all 24 channels in parallel creates up to 8160 A. Furthermore, the models of both the 15 kW and the 30 kW series power supplies can be assembled in any combination to create a power capacity between 30 kW (two 15 kW supplies) and 240 kW (all eight 30 kW supplies).

The EA-PSB 20000 series models can output 920 V to test automotive circuits powered by 800 V batteries. If a test system requires higher voltage, the insulation resistance of the supplies allows the connection of two units in series. A series connection creates an output voltage that is high as 1840 V.

The industry’s most comprehensive range of power supplies

Compared with a conventional power supply with a rectangular output characteristic and can deliver maximum power only at one point, V_Max and I_Max, true autoranging power supplies deliver full power all along their constant power output characteristic. Figure 2 shows an EA bidirectional power supply's characteristic output (input) curve. EA supplies can output (absorb) full power from the maximum rated voltage down to 1/3 of the rated voltage. This true autoranging characteristic allows the supplies to have the broadest current range of comparable wattage power supplies. A conventional, rectangular output power supply would need three times the power capacity to supply as much current as an EA supply. Figure 3 illustrates the limitations of the conventional power supply. With their ability to output (absorb) a wide current range, the EA bidirectional supplies can provide substantial cost savings for a test system.

Figure 2.  True autoranging characteristic of an EA-PSB 20000 Bidirectional Power Supply

Figure 3. A power supply with a rectangular output characteristic must have 3 times as much power to have the same current capacity as a comparably powered EA-PSB 20000 power supply

Beyond simplified testing

The EA-PSB 20000 series power supplies have a built-in function generator to allow more thorough testing of DUTs. The function generator can create I-V curves to emulate batteries, fuel cells and solar panels. The function generator produces standard waveforms such as sine, triangle, square and trapezoid signals. In addition, the function generator can create ramps, pulses and arbitrary waveforms. The supplies can test DUT response to dynamic changes with these waveform generation functions. Figure 4 illustrates the voltage and time parameters that create a ramp waveform. Another application for the arbitrary waveform function entails modulating the power supply output to emulate a noisy source to test how well a DUT can reject noise.

Without the built-in function generator, test system designers must add an external waveform generator into the test system. Controlling another instrument adds complexity to the test system, adds cost, and consumes precious test rack space. 

Figure 4. Voltage and time settings to create a ramp waveform

One instrument for simultaneous sourcing and loading

The EA-PSB 20000 series power supplies with three independent channels can simultaneously be both a source and a load. To test a DC-DC converter, one channel can act as a power supply to allow testing a DC-DC converter over its range of specified operating voltages. A second channel can be an electronic load to verify the DUT’s output specifications. The EA-PSB 20000 eliminates the need for a second instrument, as shown in Figure 5.

Figure 5. One channel of an EA-PSB 20000 is the source for the DC-DC converter. The second channel acts as the load. The rear panel of the EA-PSB 20000 shows the load connection. To avoid confusion, the source wiring is not shown on the rear panel; it is shown connecting to the front panel.

Efficient bidirectional power supply

As shown in Figure 6, the EA-PSB 20000 power supplies are regenerative instruments. Models can return 96.5% of absorbed energy to the AC grid. The annual utility cost savings can be substantial at power capacity levels of 5 kW and 10 kW/channel. Also, the highly efficient regenerative energy recovery reduces the amount of heat the instrument generates from the absorbed energy. Thus, a test rack needs less cooling or smaller cooling equipment to dissipate the smaller amount of heat emitted by the power supply. Lower cooling requirements yield additional cost savings.

Figure 6. EA-PSB 20000 bidirectional supplies return absorbed power to the grid with efficiencies as high as 96.5%.

Save test time, rack space and test system costs

A single power supply reduces test system capital costs, and the high regenerative efficiency of these supplies reduces utility costs. The cash savings are significant. A three-channel, bidirectional power supply saves test time, reduces rack space and test costs.

Three independent EA-PSB 20000 channels enable simultaneous testing that increases throughput by as much as a factor of three. The use of only one power instrument can reduce rack space for power supplies by as much as 67%.  Innovative use of SiC power MOSFETs enables EA to compress three independent channels totaling 15 kW and 30 kW into 3U and 4U, full rack enclosures. High wattage/square inch allows substantial space savings. 

High power with superior safety

At kW power levels, protecting the instrument from hazardous conditions avoids damaging the power supply, the load, and the test system. Each channel of the EA-PSB 20000 has limits to prevent an overcurrent, an overvoltage, an overpower and an overtemperature condition.

When paralleling the supplies and the individual channels, a Master-Auxiliary-Bus allows one channel to control all others and verify that all channels are properly connected. Its display shows the total current and power delivered or absorbed. For greater safety, a second bus, the Share-Bus, monitors all channels to ensure that all channels share an equal portion of the load. The Share-Bus prevents a channel from getting overloaded due to having to manage more power than its power rating.

Fast communication through multiple control ports

EA-PSB 20000 power supplies have fast communication speeds of 1 ms. Each channel operates at that speed to minimize latency. The power supplies have four built-in interfaces. They include USB, 1 Gb Ethernet, 5 Mb CAN FD and 100 Mb EtherCAT. With these interfaces, the EA-PSB 20000 supplies can easily interface with automotive vehicles and other industrial systems. The interfaces are galvanically isolated from the AC and DC outputs to minimize interference from noise sources.

Three high power channels - more test capacity in less space with lower costs

Not only do the EA-PSB 20000 series bidirectional power supplies provide 5 and 10 kW/channel, but true autoranging allows them to provide the broadest current range relative to comparable output power supplies. Include waveform generator performance, and one EA-PSB 20000 can replace four - six instruments, three power supplies and three waveform generators; and it can supply high power of either 15 kW or 30 kW. The throughput can increase by as much as a factor of three. However, the cost savings and test rack space savings multiples can be even higher. In addition, the high regenerative efficiency adds to the cost savings.

The new three-channel bidirectional power supplies, the EA-PSB 20000 series, offer more power and functionality with less hardware and greater efficiency in less space. When multiple power supplies or power supplies and a load are required, The EA-PSB 20000 is the most cost-effective solution for testing power devices. Learn more about the EA-PSB 20000 series.