The IEC61851 is the standard for communication between EV and charge point. While some people have heard about Mode 3 charging, the existence of ‘Mode 3 simplified’ charging is not well known at all. It could be considers as a legacy where automakers didn’t need to implement the full mode 3 protocol. Also it is used by Light Electric Vehicles (LEV) such as electric motor cycles to charge at public charge points. Here we’ll discuss an interesting use case for the Mode 3 Simplified protocol: the use of electrical equipment at charge points.
Charge Point States – Mode 3
Before diving into the Mode 3 Simplified protocol, it is good to have a basic understanding of the Mode 3 protocol. The charge point, when using Mode 3 protocol, will be either in one of 3 states:
- State A – is that there is no connection between EV and charge point;
- State B – is that the EV is connected to the Charger and;
- State C – is that the EV has indicated that it wants power.
To go from state B to state C, the EV needs to perform a switch operation causing the amplitude of the communication signal (PWM Signal) to drop. This voltage drop on the communication signal is an indication for the Charge point to start providing power. (Upto that moment, State C, the charge point didn’t provide any power).
Further, the Charge point communicates to the EV the maximum current the EV is allowed to consume. This maximum current might range between 6 ampere and 80 ampere and can be dynamically adjusted for load balancing or smart charging purposes.
Mode 3 simplified Charging
While the Mode 3 protocol does recognize 3 states, the Mode 3 simplified does only know 2 states: A and C. It does skip the B State all together. As soon as the connection between Charger and EV is created, the voltage is dropped to the level that the charge point will provide power.
The advantage of this is that the circuitry in the (L)EV can be more simple. The disadvantage is that the connection and vehicle continues to be energized, also when the charging of the (L)EV has been completed.
While the (L)EV deploying the Mode 3 Simplified protocol can still observe and react to the maximum current that the charge point indicates, it often will not respond to it. The reason is that it, again, requires more advanced circuitry in the (L)EV and probably much more complex then supporting state B. This is why can be assumed that an connected vehicle using Mode 3 Simplified will not adjust it’s consumption based on the indication of the charge point. This is not a problem as long as the consumption is less then the maximum indicated by the charge point. In case the consumption does exceed the maximum current, the charge point can de-energize the connection and the (L)EV wll not get any power.
Powering other equipment
In cities there is a high demand of electricity. All kind of equipment can be powered or charged using electricity. As the network of charge point grows rapidly, especially in urban area’s, the usage of charge points for other equipment then EV’s can be desired. The power supplied from a charge point can be used to replace (diesel ) generators contributing to cleaner air and less noise in the city too. The charge point infrastructure provides not only power, it also accommodates payment facilities so that the users of the power can be invoiced accordingly.
Non adaptive loads
While EVs have the possibility to change their load [on the grid] based on the PWM signal from the charge point, often equipment don’t have this load change capabilities. Therefore it could be advantageous to use the Mode 3 simplified exclusively for non adaptive loads. By this, the charge point can detect that any load balancing schemes will probably result in either an “on” or “off” situation. But more important, also smart charging protocols can make use of this knowledge. One can think of different energy rates and/or not executing smart charging profiles for the Mode 3 Simplified users.
Summary
While the Mode 3 Simplified protocol seems a legacy method to charge Light Electric Vehicles, it offers an opportunity to power all kind of equipment. As the equipment might not be able to react to smart charging profiles, the charge point is able to recognize these non-adaptive loads and can adapt accordingly. For instance, it can offer stable power, no power or only power during certain time windows. It can also cater for a more dynamic pricing of the consumed energy. And this is not an exhaustive list of option one can think off.
