Electric Car Architecture and Diagrams

In this electric car architecture guide, we’ll present a set of simple architecture models for each EV variant.

The diagrammatic representations depict the major components and energy flows in an EV system

It’s important to recognize that each major component is a subsystem composed of a variety of smaller components Each of the major architectural components is represented in a signature color

Charging functionality (always shown in orange) is depicted as if it were on-board the vehicle, but often, the battery charger is external to the vehicle

The Battery component (shown in yellow) varies dramatically in capacity and in structure

Control electronics (always shown in grey) encompass a broad array of functions that include power conditioning, motor control, and the control of regenerative braking.

The electric motor (shown in blue) has its own control functionality and can serve as a generator (also shown in blue) during regen.

The Regenerative braking (shown in green) senses when the power stops flowing to the motor and initiates the transformation of kinetic energy into electrical energy to recharge the battery

When an ICE (Internal Combustion Engine) is part of the EV architecture it is shown stylistically as an in-line 4-cyl motor.

Now that we’ve established some basic conventions, it’s time to look at each architecture.

BEV

For a BEV, electric energy is provided from the grid… period. No fossil fuels, no ICE, no emissions. The schematic above illustrates the BEV.

Electricity from the grid passes through a charger (in orange) and charges the battery (in yellow)

Energy stored in the battery is passed to control electronics (called a “power electronic driver” in grey in this schematic) to moderate the energy transfer to an electric motor (in blue) A regenerative braking component (in green) translates kinetic energy from the car’s motion into electricity to return energy back to the battery.

Regen, as it is called, is invoked only when power to the electric motor is discontinued. This occurs when the driver takes his or her foot off the accelerator. The most notable BEVs are the Nissan Leaf, the Tesla Model S, Ford Focus Electric, the BMW i3, the Mitsubishi EV, with others, such as the Volkswagen e-Golf, in their first year on the market, and more on on the way.

PHEV - Series Hybrid

The PHEV-Series architecture uses an ICE, but not to drive the wheels of the car. Rather, an ICE is used to drive a generator that charges the battery.

The battery can also be charged from the grid using a battery charger, shown in orange. Power from the battery is passed through control electronics to an electric motor.

Like its counterpart in a BEV, the regenerative braking component translates the kinetic energy of the car into electricity to recharge the battery

PHEV - Parallel Hybrid

Unlike the PHEV-series hybrid, the PHEV-parallel variant allows the ICE to directly drive the wheels, but also provides an electric motor that can drive the wheels.

Electric motor drive may be implemented at low vehicle speeds. and it will be discontinued when the battery is depleted. At that time, the ICE will take over.

The ICE operates in a manner similar to a conventional vehicle and does not act to recharge the PHEV battery. The electric motor is driven by the battery that is charged from the grid via a charger, allowing the electric motor to share drive responsibilities with the ICE.

A regenerative braking component translates the kinetic energy of the car’s motion into electricity to recharge the battery.

PHEV - Series Parallel Hybrid

The PHEV-Series Parallel architectures use an ICE that can both drive the wheels of the car and also turn a generator to charge the battery.

The key difference is this architecture is that the ICE is involved in:

• charging the battery (in yellow) by driving a generator (the top blue circle)
• transmitting its power directly to the drive wheels through special gearing shown on the middle right of the figure.

Like the series arrangement, the battery (in yellow) is also charged from the grid using a battery charger, shown in orange. Power from the battery is passed through control electronics (shown in grey) to an electric motor, shown in blue.

A regenerative braking component (shown in green) translates the kinetic energy of the car’s motion into electricity to recharge the battery

FCEVs

Unlike PHEV, the fuel cell electric vehicle (FCEV) does not charge its battery from the grid.

Rather, it makes use of a fuel cell that initiates an electro-chemical reaction with a fuel, in this case hydrogen, to create electricity that charges the battery. The fuel cell can also provide direct power for the electric motor.

An FCEV has one or more on-board fuel tanks that contain pressurized liquid hydrogen.

The vehicle must be refueled at a hydrogen refueling station, an infrastructure element that is quite rare today.

We present an entire section of the guide on the FCEV in a later section of the guide.