All appliances need power supplies to perform to their required functionality. Letís take the example of a wall-plugged system, which is an AC source. The first part of the system is an AC-to-DC conversion followed by DC-to-DC conversion to reach the required output voltage to be delivered to the load. Some examples of load output voltage are 12V to 48V for telecommunication systems, 48V for automotive loads, and as low as 3.3V or 5V for powering up a laptop.
One segment of efficiency improvement is to have an active power factor correction (PFC) power electronic chipset in the AC/DC system. PFC is needed to prevent recirculation of unused power (power not utilized by the load). Typically, this is seen in compressors, air conditioners, or any system that involves inductive or capacitive loads. Prevention of power recirculation by the PFC chipset can be seen as efficiency improvement. Also, such a requirement has become mandatory for appliance makers.
Another part of efficiency improvement is the choice of a power topology depending on the systemís power level. Making the right choice helps to deliver an efficient transfer of power.
Solar inverter block diagram highlights building blocks and IC components.
(Source: Texas Instruments)
Solar inverter systems require high-voltage and high-current handling for efficient signal conditioning that converts DC power from solar to AC power; feeding it to the grid or directly to the home. Efficiency improvement of these inverters has seen a rapid development over the last few years through picking the right topology. Examples include appropriate semiconductor integrated circuit (IC) components and the type of semiconductor switches such as power MOSFETs and IGBTs using silicon, and also emerging wide bandgap semiconductor switches such as GaN and SiC.
Making the right choices results in significant improvement in efficiency as well as in overall system cost. These choices could impact other devices in the system, such as the size of passive elements like transformers, capacitors, and inductors. These, in turn, lower the upfront cost of a green energy system, which then lowers the payback period.
As we enter the era of green energy, automotive manufacturers, in parallel, are making significant efforts globally to cut energy costs and vehicle emissions with the manufacture of hybrid electric vehicles (HEVs). This is due primarily to mandated fuel efficiency standards that need to be met over the next few years. This includes pure electric vehicles (EVs) to HEVs, where the vehicle owner does not have to depend whatsoever on gas and its price volatility. Instead, the vehicle has a plug-in feature that can be charged at home or a charging station.
Even though current EVs and HEVs are pricier than gasoline models, it is expected that with the aggressive government mandates, the price of these vehicles will come down -- especially with economy of scale over time.
A combination of green energy sources at home with EVs and HEVs charged directly from them, or through a battery source, is a classic example of total energy independence. With smart energy utilization of high-efficiency appliances, the energy demand response can be tracked and intelligently managed by the user either locally or remotely. This lends more to energy savings significantly through what is called active or dynamic pricing of electricity. One example is to send the locally-generated electricity (from renewable sources) back to the grid, charge the vehicle, and start the dishwasher during off-peak time. These could be scheduled all at the same time or staggered. Managing such a concept is called "energy demand response," and is done through bi-directional communication. This is made possible through a smart meter. Smart meters are also called time-of-use meters.
Role of the consumer
Finally, all this can be accelerated from the consumer side. Consumers play a big role and stand to benefit the most from this transition, so they need to buy into this concept of energy independence and savings.
– Nagarajan Sridhar is a product marketing manager focusing on the industrial, automotive, and renewable energy market segments in TIís Power Management group.