Charging cable for electric vehicle
Which different charging cables are available ?
What charging methods are there for the charging cables ?
How is a charging cable constructed ?
How does the electric car and the charging station communicate via the charging cable ?
How is it ensured that the charging cable for the charging current is not too thin ?
First of all I would like to explain to you something about the construction of a charging cable for electric cars and then come the further explanations. The charging cable for electric cars is internationally standardised and has a maximum of 6 wires when the electric car is supplied with alternating voltage. The charging cables themselves differ only in color, composition of the material and thus the resistance to light from the sun or chemicals etc.. Some cables are spiraled so that they can be stowed away in a space-saving way.
The following and most common AC charging cables are available:
- 3 x 2,5 mm² + 1 x 0,5 mm² for 1-phase charging up to a maximum current of 20 A
- 3 x 6 mm² + 1 x 0.5 mm² for 1-phase charging up to a maximum current of 32 A
- 5 x 2.5 mm² + 1 x 0.5 mm² for 3-phase charging up to a maximum current of 20 A
- 5 x 6 mm² + 1 x 0.5 mm² for 5-phase charging up to a maximum current of 32 A
The 1-phase charging is e.g. at the normal household socket (Schuko up to a maximum of 10 A - country-specific) via a mobile charging station (Mode2). First there is L1, the live phase, then the neutral conductor N and the protective conductor PE (Protective Earth). Between L1 and N or PE there is 230 Volt (voltage).
Depending on the wire cross-section, i.e. 2.5 mm² or 6 mm², higher or lower currents are possible. For a 2.5 mm² core cross-section, the power calculation formula P (power) = U (voltage) x I (amperage) is used to calculate a maximum available power of
P = 230 Volt x 10 Ampere = 2300 Watt = 2,3 kW possible.
For 6 mm² a maximum of 230 V x 32 A = 7360 W is possible. The 3-phase charging is e.g. charged at the red CEE socket in the garage via the mobile charging station (Mode 2). With the 3-phase mains, 3 phases - L1 , L2 and L3 - are available to me as live wires. Here we have 400 V under the phases and thus a higher power than with the 1-phase charge. (for more information on the formula, see the Charging Times Guide - click HERE).
Here we have in the line L1 , L2 , L3 , N and PE + the control line. With a cross-section of 2.5 mm², a maximum charging power of 11 kW is possible and with a cross-section of 6 mm², a maximum charging power of 22 kW is possible. The control cable has a cross section of 0.5 mm² as it is used to establish communication from the electric car to the charging station. The wire may be loaded with a maximum of 30 V and 2 A. The cable must not be connected to the charging station. For communication, the electric car only needs one control line / control wire because it is used to send a DC voltage to the charging station. The ground is then the PE wire. In the vehicle, the ground is always placed over the body of the vehicle. A voltage is sent to this control line depending on the state of the load. The voltage is adapted as PWM (pulse width modulation) signal according to IEC 61851 - 1 according to the state of the electric vehicle. This control line is called CP - Control Pilot. The charging process must proceed as follows:
1. A - No charging plug connected - 12 V
2. B - charging plug connected - voltage at Control Pilot signal CP drops to 9 V - resistance coding in plug (R2) in vehicle is detected. The voltage level at CP is determined from the series connection of resistor R1 in the charge control, diode D (in the vehicle) and resistor R2 in the vehicle at 12 V. The voltage at CP is determined by the voltage of the resistor R1 in the charge control. Here the PWM (pulse width modulation) is now switched on by an oscillator and the permissible charging current is coded, which the electric car from the charging station limits to a maximum.
3 C - Charging process - If the electric car detects the PWM signal, the voltage is reduced to 6 V by a further connection of a resistor. The charging control in the charging station now switches a load contactor and this passes the 1-phase or 3-phase network on to the electric car and current can flow. The electric car now starts charging.
4 B - Charging complete - Either the electric car tells the charging station that it has finished charging (by switching off the resistors) or the charging station switches off the PWM signal and the contactor. The connector is now voltage free and the CP now has 9 V.
5 A - charging plug removed - If the charging plug is now removed from the vehicle, the voltage now rises to the output voltage of 12 V again.
So that the charging station and the electric vehicle know which maximum power can flow via the charging cable, there is a coding resistor in the plug. This coding resistor is connected between PE and PP (Proximity Plug) in the plug for the vehicle and in Mode 3 charging in the plug for the charging station. The following resistors are available for the following maximum currents : - 1500 Ω (1000 - 2200 Ω) for maximum 13 A - 680 Ω (330 - 1000 Ω) for maximum 20 A - 220 Ω (150 - 330 Ω) for maximum 32 A - 100 Ω (75 - 150 Ω) for maximum 63 A - 2200 Ω will not be charged or an error will occur So that the electric car can charge, one must now build up a system that ensures a safe charging cycle. There are only 4 charging modes for electric mobility that make this possible. This is also described in the international standard IEC 61851-1. You will find a detailed description of the charging modes in electromobility in the charging options guide (click HERE).
If you are missing information or would like to know more about the basics or further information about electromobility, please contact us and we will be happy to help you. Click HERE to contact us !
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