For electric vehicles, efficiency is money.

Even an efficiency gain of just 2% to 3% could save automakers hundreds of dollars for an electric vehicle. In this way, the cost of electric vehicles can gradually approach that of fuel vehicles, and their profitability will become stronger and stronger.

When the entire automotive industry turns its product development guns on a single component, that component ends up being smaller, lighter, simpler, stronger, and more efficient. Typically, the component will cost less as engineers find ways to reduce the amount of precious metals and other raw materials and make manufacturing more efficient.

That's exactly what's going on with one of the core components of electric vehicles -- the electric motor, which has just embarked on a long journey of transformation.

▍What does it mean to increase efficiency by 3%

GM President Mark Reuss said in an interview with Automotive News: "It's mainly a matter of losses. Right now, we're just starting to optimize the losses and manage the motors."

Like other automakers and most suppliers, GM is pouring money into electric motors. The goal is not only to make the motor run more efficiently using less electricity, rare-earth magnets and copper, but also to reduce manufacturing costs.

"As an industry, we can learn from each other, and we have been doing a good job in this regard." In October this year, Reese said at the event introducing the battery-powered Cadillac Celestiq.

Modern cylinder deactivation technology created by Silicon Valley startup Tula Technologies is now used in General Motors large pickups and SUVs.

In the future, the company will perfect an energy-saving strategy - the Dynamic Motor Drive for electric vehicles. The system controls the motor with pulses of current, turning the motor off and on thousands of times per second.

John Fuerst, vice president of Tula Technologies, who is in charge of the project, explained what a 3% efficiency improvement means for the Chevrolet Bolt. Tula Technologies is using a fleet of Bolts to test a dynamic motor drive system.

“The way the industry really measures the percentage of benefit is the cost of the battery per kilowatt-hour. How big is the battery? Take the Bolt, for example, it’s a $7,200 battery. If you shrink it by 3%, you’re saving $216.”

Saving a few hundred dollars is hard to come by at a time when automakers are already struggling to save money, which is why there's a race to improve electric motors and control power electronics.

The truth is, the motor is nearly 200 years old. In transportation, electric motors power everything from scooters to locomotives.

But because of the energy contained in gasoline and its low cost compared to other fuels, electric motors have been present in cars only intermittently for the past 120 years, with the exception of hybrid models such as the Toyota Prius and Chevrolet Volt.

Until now, the minimal use of electric motors has hindered the optimization process to suit the unique needs of passenger vehicles. That's changing, of course, as automakers race to replace gas-powered vehicles with electric ones.

Dirk Kesselgruber, president of British supplier GKN Electric Power, believes electric motors are developing far faster than internal combustion engines, which have been in constant development for more than a century. "I don't think the motor needs such a long journey to be at its best," he said.

Like Bosch, American Axle, Dana and other drivetrain suppliers, GKN has a range of electric drives, most of which are already in high volume production.

Electric machines (motors) are very old and there is a lot of research and learning about them, Kesselgruber said. In the automotive industry, they focus on two aspects: one is the efficiency of the motor, how much energy is needed to convert it into torque?

The second is the cost factor, which covers everything—the size of the motor, the degree of contact with critical materials, cooling and thermal management, and the high speed of the motor.

▍Improvements are everywhere

According to the U.S. Department of Energy, a typical electric vehicle drive system usually results in a 15% to 20% energy loss. In comparison, a gasoline engine loses 64 to 75 percent of its energy, some due to friction and some to heat.

Currently, engineers at automakers and suppliers are making rapid progress, reducing costs while increasing overall efficiency. Improving efficiency is not just about reducing the internal friction of the motor and gearbox, but also reducing the weight and size of the motor, controlling heat, and optimizing motor speed for vehicle needs.

The compact motors in the Lucid Air are the lightest and most powerful motors currently on the market. In a video demonstration, Lucid executives explain how it works and show how to reduce weight and increase power.

In the motor, the stator 72 slots are larger than other competitors' motors, and a strand of thick copper wire forms a continuous wave. The slots of most other motors are filled with lots of insulated copper wire, and the air gap between each wire leads to inefficiency.

"I put efficiency above anything else," Lucid CEO Peter Rawlinson said at the launch.

The addition of micro-cooling slots in the stator punching allows high-voltage transmission flow to pass through, thereby removing heat from the source, which is a major breakthrough for Lucid. Doing so greatly increases the power and efficiency of the motor, especially at higher speeds. The motor is rated at 670 horsepower, yet weighs only 67 pounds.

 

Another innovation includes - placing the differential inside the rotor, making the whole drive unit very compact and light.

 

Emad Dlala, vice president of powertrain at Lucid, explained to Automotive News that such breakthrough power density and efficiency is possible because of a holistic approach.

 

“You can’t just focus on one area, you have to look everywhere for improvement, where can you improve further? The short answer is everywhere. We see potential for improvement in inverters, motors and transmissions.”

 

Della added: "We have broken new ground in motor cooling, but we believe that there is room for further improvement. Copper winding technology will continue to develop and improve, as will electromechanical architecture. There is more to come in power electronics It can be done, such as chips, capacitors, etc.”

 

"Each field has different degrees of improvement in terms of power density and efficiency. Taken together, the improvement potential of the entire power system is huge. We must not rest on the laurels of the past." He emphasized.

▍Efficiency is money

Electric motors spin much faster than internal combustion engines, and as technology improves, the rpm will likely increase even more. Some car motors can spin at 20,000 rpm or more, which means the rotor, stator and magnets have to be very strong to keep them from flying apart.

Tim Grewe is GM's general manager of electrification strategy and battery engineering. He thinks there's a lot of tweaking and engineering involved in how you control those magnets, and how you get those high speeds going, like tuning the intake manifold.

Gray has worked on every electric and hybrid vehicle GM has produced -- from the EV1 in the late 1990s to the Cadillac Celestiq, the newest of which will go on sale in the fourth quarter of next year.

Currently, GM has invested a lot of resources in electric vehicle research and development, learning how to optimize the magnets in the motor. The improvements GM has made in this area since it introduced the Chevrolet Volt hybrid in 2011 are just some of the ways engineers have increased efficiency and lowered costs.

“From a design perspective, we make better motors by using less rare earths. Terbium, neodymium and dysprosium are like catalysts inside the magnets, and in the first generation Volt we used terbium and dysprosium everywhere in the magnets . In the second-generation Volt, we basically halved the amount of terbium and dysprosium, and only put them where they are needed. ”

Gray added that Ultium motors have been taken to a new level. "We perfected the magnetic model and three-dimensional magnetic field calculation capabilities, and directly coated the key rare earths on the magnets only where needed."

 

In just three years, engineers at German supplier Bosch reduced the size of one of these electric drives by almost 50 percent. They integrated the motor, inverter and transmission into a stamped housing unit, a strategy that reduces manufacturing and material costs and weight.

Bosch is also looking for ways to reduce the use of rare-earth magnets -- the most expensive components in electric motors. Its motor product manager Arturo Maya (ArturoMaya) said that the motor has great potential for improvement, rare earth materials are very important, and we hope to obtain magnets in a more affordable way.

Magnets cost half as much as a motor. Bosch engineers are also investigating the copper windings in the electric motors and the metals used in the construction of the components.

Aisin, a Japanese supplier of gearbox and drivetrain components, does not make electric motors, but it is researching the efficiency of electric vehicle powertrains in the form of thermal management. Keeping the battery and motor at an optimal temperature increases driving range and battery life.

 

At the Detroit auto show in September, Aisin showed off a complete electric vehicle powertrain that integrates the car's HVAC system. If the motor needs cooling, the car air conditioner compressor can do the job. The HVAC system also keeps the battery at an optimal temperature.

Direct cooling of the motors themselves keeps them at a level of thermal management suitable for driving, said Edward Perosky, Aisin's vice president of powertrain engineering.

Since the battery pack is the most expensive part of an EV, higher motor efficiency allows automakers to reduce size without compromising range or performance.

Rapid improvements to electric powertrains are possible in part because electric motors and their associated drives are much simpler than traditional gasoline engines and transmissions. A typical front-wheel-drive four-cylinder car has about 200 moving parts in its powertrain. By comparison, the Chevrolet Bolt has only 13 moving parts.

These efforts to improve electric vehicles touch all areas of the auto industry.

Even suppliers that make the small electric motors used throughout vehicles -- like Germany's Brose -- are working hard to improve theirs. The motors produced by Brose are involved in the fields of power sliding doors, windows, tailgates, fans and sunroofs. The less power the motor consumes, the lighter it is, which directly affects the mileage of an electric vehicle on a single charge.

Brose recently introduced a lightweight cooling module that integrates the cooling fan, shroud and motor of the heat sink. The less energy consumed by the motor used to power the car, the better the range.

As Lucid Rawlinson said, achieving higher efficiency will drive the reduction of battery size and cost, which in turn will promote the widespread adoption of electric vehicles.