Under the Skin: How New Inverters Give Electric Vehicles More Power and Range Car News

Most of the headlines in electric vehicle technology are about advances in battery technology, performance and range.

But one of the most important components of an electric vehicle drivetrain, the inverter, is often overlooked. McLaren Applied Technology, Nio, Equipmake and BorgWarner all recently announced new 800V compact inverter technology capable of dramatically increasing the range and charging speed of electric vehicles.

Inverters convert DC from the EV battery to 3-phase AC to drive the EV’s AC traction motor and back again, from AC to DC, during regenerative braking. Additionally, they control engine speed in response to the accelerator pedal. The new generation of inverters replaces all SiC (silicon carbide) MOSFETs (metal oxide semiconductor field effect transistor) with the traditional silicon IGBT (insulated gate bipolar transistor). These transistors are electronic switches that convert direct current to alternating current in a process called, unsurprisingly, “switching.”

A three-phase power supply is like having three separate power supplies. Each has a waveform, with each of the three phases peaking 120 degrees after the previous one. This is what creates a rotating magnetic field that spins the rotor. By changing the frequency of these waves, the motor changes speed.

SiC MOSFETs can switch current much faster and handle more power. Equipmake claims its HPI-800 can switch at 40kHz (compared to 20kHz for an IGBT inverter) and the lightweight construction boosts its power-to-weight ratio from 54hp per kg to 134hp per kg with SiC.

Nio’s SiC inverter was developed by its motor division, XPT, and it will be launched in the ET7 later this year. Electrical systems can be very efficient, but they still suffer losses. Nio claims that switching losses are reduced by more than 30%, overall power losses are reduced by 4%, and power has increased by 5%.

The IPG5 (Inverter Platform Generation 5) from McLaren Applied can drive engines with a maximum power of 469 hp (335 continuous hp), weigh only 5.5 kg and occupy a space of 3.79 litres. The new inverter makes its debut in the Bak Motors Kincsem HyperGT and SUV hydrogen hybrids.

There are no fancy acronyms for BorgWarner, which simply calls its new device “our SiC inverter.” It’s the same here: less conduction losses, high switching efficiency, according to the company, and 40% to 70% lower power losses compared to silicon-based inverters. Considering the efforts of EV developers to examine every detail of an EV’s electrical and electronic systems to save every milliamp of energy, these numbers seem impressive.

Today, 800V architectures are already in production in the latest electric vehicles and this is what makes ultra-fast charging possible. By doubling the voltage from the previous 400 V, the electrical power is increased but the current (amperes) remains the same. In practical terms, this means that high-voltage cabling can be kept smaller and lighter and power losses are reduced. With potentially lighter and more energy dense silicon anode batteries just around the corner and solid state beyond, combined with these vastly improved and lighter inverters, it looks like there’s a lot to wait.