Phoenix Contact’s industry manager for e-mobility, Gary Chater, offers a plethora of purchasing advice for buyers tasked with sourcing electric vehicle charging systems
Connectors, components and electronic modules for e-mobility products can be divided into two main groups: infrastructure (charging equipment) and vehicular (inlets and battery management). Design and procurement can be simplified by using ready-certified modules offering a quicker route to market.
Electric vehicle supply equipment (EVSE) describes the vehicle charger and is commonly applied to commercial infrastructure rather than domestic wall boxes. A domestic charger supplies AC current to charge a car relatively slowly which is applicable to long parking periods. Smart functions, such as smartphone integration, are not necessary but increasingly popular. Workplace chargers are often similar, again taking advantage of long parking periods. However, they are more likely to require metering and payment systems. More advanced chargers can benefit from a modular approach to design and purchasing.
High speed charging is provided by high current DC equipment. Again, design is simplified by using certified modules capable of interfacing with the back-office system and other charger components. This simplicity is reflected during purchasing, particularly regarding manufacturers like Phoenix Contact who can provide every item from one source.
It is useful to understand naming conventions when specifying and purchasing components. In the UK the two main standards are AC Type 2 and CCS Type 2. CCS stands for ‘combined charging system’ because it combines the Type 2 AC connector with DC contacts for high power charging. Most new electric vehicles use a CCS Type 2 inlet for AC or DC charging. AC chargers may feature a cable or AC outlet socket, the latter requiring a separate AC cable. CCS chargers always feature a tethered cable.
CCS cables and AC charging cables, tethered or otherwise, are available in a bewildering variety. Purchasing is simplified by appreciating the parameters. Firstly, cables are manufactured in different lengths, with a typical maximum of ten metres. Cable handling is eased by specifying the correct length and there is also a cost benefit, given copper’s high cost. Purchasing the correct cable type is important: AC cables may be single or three-phase, with typical current ratings from 16A to 63A. Typical current ratings for DC cables on CCS chargers are between 40A and 500A. These are matched to the CCS charger’s power rating, usually between 50kW and 350kW. The trend is increasing power to reduce charging time.
Similar observations apply to vehicle inlets. The huge variety is caused by variation in a relatively small number of parameters, making purchasing easier than it initially appears. For example, AC inlets are manufactured as well as CCS, both of which are available in a variety of current ratings and cable lengths. Outside automotive, there are many examples of specialist vehicles requiring inlets including boats, aircraft, earth moving vehicles, trucks and buses.
The heart of a charger system is the controller with interfaces for the system’s functional areas’ including: the vehicle itself; optional operator display; RFID reader for charge card payments; and communication technology for back-office billing system and energy metering. Other components include: power supplies; surge protection; current monitoring; terminal blocks; DIN rails; heavy-duty connectors; and marking material. High power DC chargers also require power conversion, usually AC to DC or DC to DC. Some suppliers manufacture all these parts, thus simplifying purchasing.
Design and procurement can be further simplified by a single-source manufacturer providing examples with associated bills-of-materials. It is helpful to err on the side of complexity, specifying all the parts which could conceivably be used. For example, an RFID reader may be part of an example bill-of-materials for cases when a charge card reader is required; it is then trivial to delete it for simpler designs.