There are currently two lines of development: purely electrified vehicles, known by its acronym EV, and hybrids with electric propulsion, both conventional self-recharging (HEV) and plug-in, PHEVs. The principle of operation of the former is characterized by its simplicity, and is practically the same as in its beginnings.
This consists of a primary source of energy, batteries or fuel cells, and a rotary engine: the propeller itself. Also, a converter has been added for the energy transformation from the source, and the vehicle speed control. But then what are their voltages focused on?
In this sense, this is defined as the magnitude in charge of establishing the differentiation of electric potential that exists between two points. This is why it is also known as electrical voltage, or electrical potential difference. In its most technical definition, voltage consists of the work done by a unit of electric charge in a particle of an electric field determined, so that said unit is able to move through two points. This is where another very differentiating point comes in.
Its role in electric cars
In this regard, that’s where the electric current comes in. This, basically, is produced by when two points of different electric potential they present themselves with a driver. This current will be responsible for carrying a part of the electric charge from the point of greatest potential, to the point of lowest potential.
With a more than important work in this type of vehicle, the truth is that conventional cars, since the mid-1950s, had electrical systems that worked (and much still do) with 12 volts, except for exceptions. Among these exceptions are vehicles with longer-distance electrical systems, although it is true that a good majority of them correspond to military vehicles that require redundant systems and a greater electrical capacity to operate extra accessories and special devices.
More recently we find automobiles with high demands for electrical energy, especially luxury cars, which already use 400 V electrical systems, even 800, like the Porsche Taycan does. In fact, and although today these voltages are timidly seen in electric cars, this seems the direction in the not too distant future, in which the charging infrastructures will be increased above these figures.
Certainly, this new concept of voltage increase in cars has come from a need for security. You probably remember it, but a few years ago, in 2016, the controversy arose over the death of a driver of a Tesla S in Amsterdam. Then, the firefighters who attended the accident took longer than normal to release the man for the precautions they had to take to make sure you don’t get electrocuted.
Types and characteristics
Once you understand how they are today and what electrical systems they equip, it is worth delving into an aspect that directly relates it. We are talking about the two types of electric current that exist today, and which will lead to the different types and techniques of voltages that these electric cars comprise.
Why not; regardless of whether they are 24 or 48 V, not all shapes are the same. And it is that these can vary depending on their characteristics, which gives rise to the existence of different measurements. But before entering into this matter, we must distance the aforementioned concepts: direct current (DC) and alternating current (AC). The difference between the two is how electrons move within the compound.
While most household appliances are powered by alternating current (AC), the battery of any device, such as a mobile phone or laptop, can only be charged with direct current (DC). In the case of the battery of an electric car too, so it is important to know how that voltage works.
Direct current voltage
The direct current voltage, or VCC, is that in which the current is pure, so that does not present alterations. They are commonly found in larger car batteries, as they require a constant voltage in order to function properly.
Flowing in only one direction, the direct current (DC) voltage of electric cars is the only one that can be stored in a battery. Therefore, to charge the vehicle to the alternating current (AC) of the network, it must be converted to direct current (DC). It is what is popularly known as current transformation. Typically, this conversion can be done by the car’s on-board charger or can be done externally with a Wall charger or at public charging points. These are able to provide up to 100 kW AC.
AC voltage
In turn, we find what is known as alternating current voltage, VAC. This is the one used by a system like rotating magnetic field. It’s the most obvious way to distance it from the VCC, where you forget to apply magnetism evenly and consistently. Thus, when the position of the poles changes, the direction of the electron flow also changes.
On the other hand, this makes it somewhat more complex than the first one, so that, as regards electric cars, this voltage makes the load depend on the connector. In general, it is done from a domestic socket and without communication between the vehicle and the charging point. The charging time will depend on the capacity of the battery.
The vehicle is charged in a standard plug-in device. In the single phase network, uses the electrical intensity and voltage of the same level as a home, that is, 16 amps and up to 250 volts. This implies that the electrical power that the point can deliver is approximately 3.7 kW. In the three-phase network, the voltage is 480 V and 11 kW of maximum power, cutting the time in half.
Single phase current
It is the one that we usually find in the power outlets of our homes. Identified as AC, its power can revolve around the 220 or 230 volts, whose maximum powers would be between 13.86 kW and 14.49 kW.
It is likely that owning an electric car will lead to having to notify the supplier to increase the contracted power. Why? Well, because it would not be very comfortable to have to continuously disconnect most of our appliances and devices to charge car batteries. This is why, although it is well used, it is not so frequent like three-phase current.
Triphasic current
Much more effective and recommended to charge the electricity and voltage of our electric cars, it is especially recommended for those who have contracted more than 10 kW. It is required, where appropriate, for those who may need more power for its operation, which do require this type of mode.
This is where the well-known Wallboxes, or charging stations, come in. These are the ones that usually admit both options (single-phase and three-phase), although the second has the advantage that it is capable of perform with higher powers and, therefore, it will ensure that the recharging of our cars is done in much less time.