Due to the depletion of fossil reserves and increasing energy demand, the modern world is facing an energy crisis. Moreover, depletion of conventional sources of energy, such as fossil reserves, and rising carbon footprint have created a need to look for alternative energy sources that are both cost-effective and eco-friendly.
The automotive industry has also seen a significant technological shift, opening the path for widespread acceptance of electric transportation and automotive inverters.
The global automotive inverter market is growing at a rapid pace owing to various innovations and technological advancements taking place within the automotive industry, which is paving the way for alternative energy vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs).
With the development of modern techniques, the efficiency to increase the storage systems and converters with a minimum requirement of equipment ensures maximum power generation. As far as power electronics are concerned, multilevel inverters provide high assistance in managing their application.
Introduction to Multilevel Inverters in Power Electronics
Power electronics deal with the conversion and control of electric power. In simpler words, if there is a need to run an alternating current (AC)-powered gadget from a direct current (DC) car battery, a device is required that can convert DC into AC, and this marks the entry of inverters.
Multilevel inverters are mostly preferred in high voltage and high-power applications. As an alternative in the area of high-power medium-voltage energy control, multilevel inverter technology has emerged recently. A multilevel converter consists of several switches that give high output power from a medium voltage source.
With the emerging advancements of multilevel inverters, the growth in the global automotive inverter market is expected to be driven by increasing demand for electric vehicles to ensure sustainability and lower ownership costs.
According to a report by BIS Research, the global automotive inverter market was estimated to be at $8.3 billion in 2020, which is expected to grow at a CAGR of 17.09% and reach $50.1 billion by 2031.
There are three types of multilevel inverters:
• Diode Clamped Multilevel Inverter: This inverter provides multiple voltage levels arranged in series through the different phases of the capacitor banks. A limited amount of voltage is transferred by diode-clamped multilevel inverters to reduce the stress on other electrical devices. The maximum output voltage received is half of the input DC voltage. This multilevel inverter is used in static var compensation, variable speed motor drives, high voltage system interconnections, high voltage DC and AC transmission lines, etc.
• Flying Capacitor Multilevel Inverter: This inverter uses a series connection of capacitor-clamped switching cells. In this type of inverter, capacitors transfer a limited amount of voltage to electrical devices in the same way as in the diode-clamped inverter. The output gain is half of the input DC voltage with a flying capacitor multilevel inverter. Induction motor control using direct torque control (DTC) circuit, static var generation, both AC-DC and DC-AC conversion applications, converters with harmonic distortion capability, and sinusoidal current rectifiers are some of the common applications of flying capacitor multilevel inverters.
• Cascaded H-Bridge Multilevel Inverter: This inverter requires capacitors and switches with a smaller number of components on each level. A lesser number of components is required as compared to diode clamped and flying capacitor multilevel inverters. Bulky transformers are eliminated in cascaded H-bridge multilevel inverters, but they are required in the case of conventional multi-phase inverters. Some common applications of cascaded H-bridge multilevel inverters are motor drives, active filters, electric vehicle drives, DC power source utilization, power factor compensators, back-to-back frequency link systems, interfacing with renewable energy resources, etc.
Advancements in Multilevel Inverters
A multilevel inverter (MLI) is a modification of a two-level inverter where two different voltages for the load are created. More than two voltage levels are combined in a multilevel inverter in order to create a smoother stepped output waveform. The smoothness of the waveform changes according to the voltage levels. With the increment in the voltage level, the complexity is increased, but the waveform becomes smoother.
The demand for automotive inverters has increased drastically in recent years with the fast adoption of battery electric vehicles, plug-in hybrid electric vehicles, and hybrid electric vehicles, which are essential components of alternative energy vehicles.
The automotive industry has seen a significant technological shift after opening the path for widespread acceptance of electric transportation. Various countries are implementing measures such as fuel economy standards, deploying support infrastructure for alternative propulsion vehicles, and providing consumer incentives to help bridge the ownership cost gap between alternative energy vehicles and conventional vehicles in order to reduce carbon emissions and increase the adoption of alternative energy vehicles.
Conclusion
Multilevel inverters can manage high power and currents, as well as the related electromagnetic compatibility (EMC) difficulties, and enable fail-safe operation to ensure reliability and safety for the users.
With the emerging technologies and advancements in multilevel inverters, the global automotive inverter market is expected to grow at a fast pace owing to the continuous shift toward electric mobility.
As already known, a multilevel inverter plays a vital role in the powertrain of an electric vehicle by converting DC current coming from the battery into AC current for the AC motor in the drivetrain to function, and it provides an impetus to the electric vehicle industry as well.
