There’s a new inverter in town, EV fans, and that’s big news, even though you may not realize it. Most of us know very little about what makes an electric car go, just as most of us can’t explain how all those pistons pumping up and down inside an internal combustion engine make the wheels turn. Our knowledge is limited to ‘a push on the pedal on the right makes the car go, while a push on the pedal on the left makes it stop.’
Oh, sure, we understand at some basic level that there is a battery and it stores electricity that makes an electric motor turn, but there’s a bit more to it than that. There are battery management systems that monitor the individual cells and modules to make sure they stay at the correct temperature, systems to heat and cool the battery pack, and systems that harvest electricity and put it back into the battery when an electric vehicle slows down.
One of the components that is vital to the operation of an electric car is called an inverter. What does it do? For the answer, we turn to eVehicle Technology for the answer.
“An inverter converts DC charge from the battery to AC to drive the electric motor, and also times switching changes to adjust the frequency of the AC charge to control the speed of the motor, much like a fuel injection and ignition system does in a combustion engine. The faster and more efficient the inverter is, the more efficient the vehicle is as a whole and the greater the amount of driving range that can be extracted from the battery.”
Most of us wouldn’t know an inverter if it bit us, but as it turns out, it’s a pretty important part of an EV powertrain. Equipmake, based in the UK, has just announced an all new, next generation inverter that uses silicon carbide technology it says can make an EV more efficient. The new inverter was developed at its headquarters in Norfolk, England, where the company manufactures EV components for automotive OEMs and specialist supercar makers. It produces everything from industry leading electric motors, to power electronic systems, to complete EV drivetrains.
Traditionally, EVs have used insulated gate bipolar transistor (IGBT) inverters that can switch current at up to 20 kHz. Silicon carbide (SiC) inverters deliver significant improvements, with higher power levels, lower power losses, and improved overall efficiency. Equipmake’s new HPI-800 inverter can switch current at up to 40 kHz.
Along with delivering significant gains in power and efficiency, SiC inverters are smaller and lighter, enabling engineers and designers to take advantage of aerodynamic and packaging improvements and reducing the amount of cooling a vehicle requires. Their lightweight construction transforms power-to-weight ratio, too, from 40 kW/kg for contemporary IGBT technology to 100 kW/kg with SiC. Ian Foley, managing director of Equipmake tells eVehicle Technology:
“The upfront cost of a SiC inverter is more than recuped by the benefits in additional performance. In a typical high performance EV sports saloon, the associated efficiencies can reduce the size of the battery by at least 10 per cent – or around 40-50kg. While they can be twice as expensive as IGBT versions, they can reduce battery size by such a large amount that the cost saving more than pays for the inverter itself. At the same time, the increase in efficiency and performance the technology can bring to an EV will enhance its natural appeal to customers.
“HPI-800 offers huge potential benefits for all types of EV powertrain, just in terms of reducing the size of the battery required. Factor in its compactness and light weight, and OEMs have even more reason to choose SiC for their next inverter.
The HPI-800 inverter weighs 12.7 kg and delivers a maximum continuous output power of up to 400 KW, depending on the motor it is powering. It is available now and can be ordered in production runs of up to thousands of units.
In past years, gearheads would pop the hood to ogle the dual carburetors on the new Belchfire 5000. Soon, they will be popping the hood on the new Electrica 5000 and exclaiming, “Dude, check it out. This things got an HPI-800!” Sic transit gloria.
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