Energy is essential for most modern lifestyles and it can come in many forms. Electric power supplies have long been produced by the flow of water through hydroelectric plants and more recently by photoelectric cells in solar panels. But electrical energy is also produced by burning coal, natural gas, and other fossil fuels. Such fuels can unleash large amounts of electrical energy known as green house gases, (GHGs) which are harmful by-products. Carbon-based GHGs such as methane (CH4) and carbon dioxide (CO2) are added to the atmosphere in large amounts, which are commonly believed to impact environmental conditions.
The increase in GHG emissions is not an overnight phenomenon but has been taking place for about 150 years, as mankind has become more industrialized. Carbon moves between the atmosphere and the Earth’s land masses and oceans to be absorbed by them as part of the normal global carbon cycle. But generating energy by burning fossil fuels adds GHGs at an accelerated rate. Natural environmental processes, such as plant photosynthesis converting CO2 to oxygen, can contribute towards carbon neutrality, prompting increased planting of trees to help avert climate change from the GHG effect. But increased GHG emissions exceed the planet’s natural capabilities to absorb the excess carbon, with the excess GHGs affecting the atmosphere and causing changes in atmospheric conditions, such as temperature and humidity, that are generally accepted as climate change. Increases in GHGs started with the industrial revolution and it is within the capabilities of the world’s industries to reduce their own contributions to GHG emissions.
Many major companies, such as Amazon, Apple, and General Motors, have pledged to be “carbon-neutral” within one or two decades, no matter your viewpoint, it is important to note that industry trends are moving in this direction. One of the more obvious industries striving for carbon neutrality is the automotive industry with many manufacturers developing non-fossil-fuel automobiles, such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) with motors capable of running for hundreds of miles on electricity or a combination of electricity and back-up generators fired by small amounts of fossil fuels such as gasoline. Advances in rechargeable battery technologies have made EVs and HEVs more practical and with increased range and many countries are embracing electric-powered transportation. For example, in London, electric charging stations are being installed regularly in light towers so that EVs and HEVs can stop and recharge when necessary.
Test applications can strive for low carbon footprints by characterizing the quality of a device under test (DUT) that supports carbon neutrality, such as regenerative energy in an EV’s charging system. Efficient use of energy is possible by feeding power generated by a DUT during the measurements back to the power grid, rather than dissipating the energy as heat lost to the environment. Test equipment designed to assist efforts for carbon neutrality include power supplies and loads as well as analyzers capable of measuring power quality and conversion of energy from one form to another, such as from AC voltage to DC voltage. As power grids rely more on electricity, the electrical power must be stored and distributed, resulting in increased test requirements for grid components such as rechargeable batteries and fuel cells. Test solutions must be capable of measuring bidirectional power, with energy flowing to and from a DUT.
As an example, the Chroma 61815 regenerative grid simulator is capable of voltage charge and discharge testing, with 15 kVA maximum output power, operating at a voltage range of 0 to 350 V. As many as three of the rack-mount equipment can be connected in parallel when higher power levels are needed. It works in single-phase and three-phase modes and is very efficient, with typical efficiency of 87%. Any energy generated by a DUT during testing can be fed back to the power grid for true “green” testing of such energy-saving devices as on-board chargers (OBCs), energy storage systems (ESSs), power conditioning systems (PCSs), power hardware-in-the-loop (PHIL) systems, and EV power supply equipment. As OBCs quickly move to bidirectional charge and discharge applications, such as vehicle-to-grid (V2G), vehicle-to-load (V2L), and vehicle-to-home (V2H) use for charging EVs and HEVs, the demand for bidirectional OBCs (BOBCs) is quickly growing.
Another option is the Chroma 62180D-600 programmable bidirectional power supply which can function as a load, allowing feedback of power from a DUT. It provides a DC power supply output and regenerative DC load, saving energy by feeding power back to the grid. It is well suited for power conversion testing, characterizing all the bidirectional electric power components in HEVs and EVs, and evaluating renewable energy sources. It features a wide source/sink voltage range from 0 to 600 V, maximum source/sink current of ±80 A, and maximum source/sink power of ±1200 W. The voltage and current measurement resolutions are 10 mV and 10 mA, respectively. Its bidirectional switched power-supply configuration provides two-quadrant operation capable of positive-current/positive-voltage operation as well as negative-current/positive-voltage use. The model 62180D-600 programmable bidirectional power supply can operate in constant-voltage, constant-current, and constant-power modes and it is easy to control, either locally or remotely via a host of computer interfaces including CAN, GPIB, and USB ports. Perhaps most impressive is its capability to return power to the grid, with typical efficiency of 91% or better.
The Keysight Technologies RP7953A is one member of a bidirectional regenerative power supply family designed for testing high-power and high-voltage components and systems in EVs and HEVs. The simple, rack-mount equipment boasts integrated safety features to protect both testers and the equipment under test when exposed to such high energy levels. When a fault is detected during a measurement, power is automatically disconnected in 15 ms or less. The eco-friendly bidirectional regenerative power supply provides voltages from 0 to 950 V, current from 0 to ±20 A, and output power from 0 to ±10 kW. Loads can be regulated with voltage resolution of 60 mV and current resolution of 9 mA and the bidirectional power supply features typical voltage programming and measurement accuracy of 0.03%. As with lower-power members of the test equipment family, the power supply is ideal for characterizing and maintaining the electric power components in EVs and HEVs. With efficiency of 86.3% at full power, it minimizes cooling requirements in a relatively compact equipment enclosure.
Another high-efficiency test equipment is the Kikusui PLZ6000R regenerative DC load, which achieves power regeneration efficiency of better than 90% to avoid the need for additional cooling even when handling high power levels. Capable of 6 kW maximum power, the electronic load provides a high-current (400 A) voltage range of 0 to 30 V and a lower-current (to 200 A) voltage range of 0 to 600 V. Local operation is very straightforward thanks to a large on-board liquid-crystal-display (LCD) screen. The electronic load also provides ease of remote operation with GPIB, RS-232C, and USB control interfaces. This test equipment is well suited for testing DC-to-DC converters and serving as a dummy load for equipment powered by natural energy sources, such as solar power and wind turbines.
The NH Research 9430-24 regenerative four-quadrant current-regulated AC load is also easy to use via its large 9-in. touch panel user interface. It is capable of single-, split-, or three-phase operation and has several operating modes, including constant-current, constant-voltage, constant-resistance, and constant-power operation. The regenerative AC load has an AC voltage range of 10 to 350 VAC from 30 to 880 Hz and a DC voltage range of 10 to 400 VDC, with maximum power rating of 24 kW. With a maximum current rating of 180 A and programmable crest factors, it can emulate different types of loads, such as switching power supplies, and return energy to the grid with better than 90% efficiency.