The development of components like the inverter play a key role in making EVs more efficient, affordable and attractive to the consumer. By Benjamin DeLand
In 2035, the European automotive and electric vehicle (EV) markets will effectively become the same entity, as legislation passed by the European Parliament prohibiting the sale of new CO2-producing cars and vans comes into force. A considerable challenge facing the EV market from now until 2035 and beyond is to ensure consumers are offered the products and infrastructure necessary to make switching from conventional gasoline and diesel vehicles appealing, practical and affordable. The market faces significantly slower growth if this challenge is not adequately met.
There are two main obstacles to overcome from a vehicle development point. The first is the cost of EVs; a 2022 report by automotive research specialists Jato Dynamics put the average price of a battery electric vehicle (BEV) in Europe at €55,821 (US$60,780) after tax, pricing many potential buyers out of the market. The second relates to range anxiety, which is no longer solely about how far the car can travel on a charge but also how efficiently it uses its power and how quickly it can be charged during a journey. Range anxiety is now regularly replaced by ‘charging anxiety’ to reflect this change.
Efficient power conversion from the battery to the driven wheels is arguably the most important area of focus for GKN Automotive. A Tier 1 supplier to the automotive industry, GKN Automotive has become one of the leading manufacturers in electric powertrain technology. Early on, the company identified the fundamental role efficiency has in improving the performance of EVs and lowering their prices.
The development of EVs, particularly in the early phases, was focused on increasing battery size in order to allay consumer anxiety around range but today, it’s an approach that’s no longer optimal. Dirk Kesselgruber, President of ePowertrain at GKN Automotive, explains: “The battery is the most expensive component in an EV and using a large battery incurs significant cost while adding weight, which negatively affects the vehicle’s efficiency. We believe the biggest range improvements in the short to medium term, before the advent of new battery technology, will come from focusing on the optimisation of components, rather than on larger batteries.”
The company was quick to recognise inverter technology as a key area of development thanks to the scale of potential benefits for vehicle performance. GKN Automotive has heavily invested in this area and launched an 800-volt (V) inverter last year, which delivers 20% more power, a power-density increase of 50% and a power-to-weight improvement of 60% over the previous model. Engineers were also able to reduce the amount of copper used in the inverter by around 60%.
The step up from 400V to the 800V standard is indicative of the significant impact inverter technology can have on future EVs, allowing manufacturers to produce vehicles that are more efficient and cheaper to buy. The next-gen inverter unlocks many of the most important benefits, including reduced vehicle weight, power losses and charging times.
The inverter is a crucial component in an electric powertrain, switching DC charge from the battery to AC charge to drive the motor and the reverse when the system captures energy from braking. It delivers this power by controlling the switching of coils inside the electric motor, creating the magnetic field that spins the rotor. Increasing the voltage of the system enables a reduction in the current required to deliver the same amount of power, which improves the inverter’s efficiency by reducing heat losses. This, in turn, creates weight savings via lighter cabling and lower inverter mass, as well as the opportunity to use a smaller battery without losing range.
One of the most obvious and important benefits to the consumer is that the higher voltage inverter also means less time spent waiting for the car to recharge. Charging anxiety remains a key concern for prospective EV owners. Kesselgruber comments: “Customers want to know that they can easily find a charger and that when they do, they will be able to give their car enough charge to complete a journey without waiting around for hours. A key benefit of the 800V system is that it increases the amount of power a charger can deliver to the battery in any given time period, reducing charging times by more than 50%.”
As development progresses, increased integration of the inverter into the electric drive unit (EDU) will allow further improvements in power density and thermal management. Not only will this boost efficiency, but it will also reduce the amount of materials used in manufacture and lower the cost of production.
The biggest range improvements in the short to medium term, before the advent of new battery technology, will come from focusing on the optimisation of components, rather than on larger batteries
Silicon carbide is also key for the next generation of inverters. Silicon carbide power modules can operate at higher frequencies and lower losses than silicon, which makes the inverter more efficient and enables mass reduction through downsizing of bulky capacitors. Perhaps the biggest advantage of the high frequency operation is the ability to control high-speed motors; the ability to use motors that run at higher speeds allows overall motor size to be smaller, which creates major savings in packaging and cost.
GKN Automotive has many ongoing R&D projects that encompass a broad spectrum of the components it produces in its ePowertrain division, focusing on innovation that will improve sustainability and efficiency. The future of the EV market depends on advances and improvements in technology, and the development of components such as the inverter play a fundamental role in making EVs more efficient, sustainable, affordable and attractive to the consumer.
About the author: Benjamin DeLand is Director of Electrical Hardware at GKN Automotive