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Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors

This article reviews basic EV charging levels and modes, then discusses the requirements for CCS connectors, including a comparison of CCS Type 1, CCS Type 2, and Chinese GB/T connectors. Finally, CCS connectors from Phoenix Contact, TE Connectivity and Adam Tech are used as examples to evaluate the extended features offered by these suppliers, such as a wider operating temperature range and higher intrusion protection (IP) rating.

Author: Jeff Shepard

The use of electric vehicles (EVs) is growing in a variety of application areas, from agriculture and municipalities to consumers, thanks in large part to a reduction in “range anxiety.” While advanced battery technology allows higher battery capacity per volume and thus longer driving range, the utility of this advancement is limited if the battery is charged for too long. This puts the onus on car companies and their component suppliers to quickly adopt fast charging methods.

One of the key components in charging is the connector. They must now be able to handle up to 500 kilowatts (kW) of power at up to 1,000 volts of direct current, while also accepting AC power. They must also meet the requirements of the IEC 62196 and SAE J1772 standards for safe and intelligent fast charging. To meet the needs of all automotive and non-automotive systems, designers of BEV systems can turn to connectors that are compliant with the Combined Charging System (CCS) specification.

This article reviews basic EV charging levels and modes, then discusses the requirements for CCS connectors, including a comparison of CCS Type 1, CCS Type 2, and Chinese GB/T connectors. Finally, CCS connectors from Phoenix Contact, TE Connectivity and Adam Tech are used as examples to evaluate the extended features offered by these suppliers, such as a wider operating temperature range and higher intrusion protection (IP) rating.

Electric vehicle combined charging system

CSS vehicle charging ports are designed to accept both AC and DC power connectors. AC fast charging is convenient when parked for long periods of time in garages or parking lots, while fast DC charging is used for short-term parking in shops, service areas and dedicated charging stations (Figure 1).

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 1: A single CCS vehicle charging port can support both AC and DC fast charging. (Image credit: Phoenix Contact)

Electric Vehicle Charging Levels and Modes

Electric vehicle charging classification includes: charging level, charging mode, wiring condition, and charging connector type when using CCS. In the US, SAE J1772 recognizes three charging levels:

Class 1 uses residential 120 VAC, limiting power to approximately 1.9 kW. Level 1 charging is slow.
Level 2 charging uses 208/240 VAC single-phase power. It can provide up to about 19 kW of charging capacity from a 240 VAC power supply. Level 2 is “Fast AC Charge” and charges three to seven times faster than Level 1. Levels 1 and 2 power on-board EV chargers.
Level 3 is DC fast charging, using an external DC charger, providing 600 VDC, 400 Ampere (A) charging capability for a total power of 240 kW. Advanced DC fast chargers can provide 500 kW (1,000 VDC, 500 A) charging power.

In Europe, IEC 61851-1 defines four electric vehicle charging modes.

Mode 1 charging uses a simple cable that plugs directly into an AC outlet. It has low power and is not used very often.
Mode 2 also plugs directly into an AC outlet, but adds integrated protection called an on-cable control and protection device (IC-CPD). Mode 2 is safer than Mode 1, but only supports three-phase power charging, up to about 15 kW.

Modes 3 and 4 are fast charging:

Mode 3 uses a dedicated charging station (also known as Electric Vehicle Supply Equipment, or EVSE), providing up to 120 kW of AC power. Modes 1, 2 and 3 all use the EV’s on-board charger to control battery charging.
Mode 4 refers to fast DC charging. The EV’s on-board charger is bypassed and the EV system feeds power directly to the battery through a DC connector. Mode 4 charging power can reach several hundred kilowatts. While in Mode 3 it is possible to use High Level Communication Protocol (HLC) and charge control for energy feedback, in Mode 4 this is mandatory.

Connection Types, Modes and Scenarios

In North America, CCS is standardized in SAE J1772 with type 1 connectors; in Europe, CCS is standardized in IEC 62196 with type 2 connectors. The HCL interface between EV and EVSE is based on ISO/IEC 15118 and DIN SPEC 70121. There are three possible EV-to-power connections; scenarios A, B, and C.

In Scenario A, the cable is permanently attached to the electric vehicle and plugged in as needed. Scenario A is not used in CCS. Cases B and C are used with CCS and the corresponding Chinese standard is called GB/T (Figure 2). Case B occurs when both ends of the power cord are detachable. Case C is when the power cord is permanently connected to the EV system. Charge Mode 3 can use either the B-case or the C-case. Charge Mode 4 uses C-case only.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 2: Comparison of CCS Type 1 (North America), Type 2 (Europe) and GB/T (China) connector types, patterns and situations. (Image credit: Phoenix Contact)

Temperature monitoring and active cooling

Monitoring contact temperature is important in fast charging systems. According to IEC 62196, the temperature rise of the contacts must not exceed 50°C. The HCL interface between the EV and EVSE is used for temperature data communication. If the temperature rises too much, the EVSE will slow down or stop charging. For CCS connectors for AC charging, a positive temperature coefficient (PTC) thermistor is used to monitor the temperature according to DIN 60738. If the connector gets too hot, charging stops (Figure 3). For fast DC charging, DIN 60751 requires two Pt1000 sensors, one on each contact. The resistance value of Pt1000 increases linearly with increasing temperature.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 3: The PTC temperature sensor shuts down AC charging to keep the temperature below a safe level (left). For fast DC charging, the Pt1000 sensor continuously monitors the temperature (right). (Image credit: Phoenix Contact)

In systems supplying more than 250 A of charging current, temperature monitoring is required along with active cooling (Figure 4). With an active cooling design, the CCS connector can deliver up to 500 kW (500 A, 1,000 VDC) of charging power. In the event of an unexpected rise in ambient temperature or an overload condition, temperature monitoring enables the system to increase the cooling rate or decrease the charging rate to keep the connector contact temperature rise below the +50°C specification limit.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 4: Active cooling combined with temperature sensing can support a full 500 A charge and keep connector temperature rise below +50°C. (Image source: Phoenix Contact (modified by the author))

Integrated locking mechanism

The CCS connector system incorporates a locking mechanism. The locking mechanism of the Type 1 connector is a manual clamping mechanism. In the Type 2 connector, locking is accomplished by an electromagnetically activated metal bolt (Figure 5). This locking is controlled and its state is passed to the EVSE (charging equipment) via a separate connection.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 5: The CCS vehicle charging port is equipped with an electromechanically controlled locking bolt (next to the red arrow, upper left) designed to withstand high pull-out forces. (Image credit: Phoenix Contact)

Type 1 and 2 charging ports and connectors

Phoenix Contact’s CHARX CCS charging ports use DC wires with cross-sections up to 95 mm² and can support charging rates up to 500 kW. Model 1194398 can provide 125 kW of charging in normal operation and 250 kW in boost mode (Figure 6). This CCS Type 1 charging port is designed for use in charging modes 2, 3 and 4. It includes a PTC chain temperature sensor on the AC contacts and a Pt1000 sensor on the DC contacts.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 6: Model 1194398 CCS Type 1 vehicle charging port for AC or DC charging provides 125 kW in normal operation and up to 250 kW in boost mode. (Image credit: Phoenix Contact)

For higher power needs, Phoenix Contact’s 1162148 vehicle charging port supports charging rates of 500 kW in burst mode and 250 kW in normal operation. According to ISO/IEC 15118 and DIN SPEC 70121, the digital signal transmission function using pulse width modulation (PWM) is realized by power line communication. Its ambient operating temperature range is -40°C to +60°C.

Applications requiring a CCS Type 1 AC plug for Level 2 charging can use model 2267220-3 from TE Connectivity AMP Connectors (Figure 7). The connector is rated for 240 VAC and 32 A and has three power and two signal contacts. It has an extended operating temperature range of -55°C to +105°C and is rated for 10,000 mating cycles.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 7: CCS Type 1 EV charging connector shown with an integrated manual locking system (left side of connector). (Image source: TE Connectivity)

Adam Tech’s Electric Vehicle Charger Cable Assemblies include Type 1 and Type 2 plugs with a 3 meter (m) (9.84 ft) cable length. or 5 meters (16.4 feet) and are available with an IP54 or IP55 intrusion protection (IP) rating. For example, CA #EV03AT-004-5M is a Type 2 connector with a 5-meter cable and provides IP55 protection (Figure 8). It has five power contacts and two signal contacts, is rated at 480 VAC, 16 A, and has an operating temperature range of -30°C to +50°C.

Simplifying Implementation of Safe Electric Vehicle Fast Charging Systems Using CCS Connectors
Figure 8: CA #EV03AT-004-5M CCS Type 2 connector rated at 480 VAC, 16 A. (Image credit: Adam Tech)

CCS Specification Considerations

The overall mechanical and electrical characteristics of CCS vehicle charging ports and connectors have been standardized, but designers need to be aware of several factors when specifying these devices:

IP Ratings: These ratings are available in several ways: when plugged in, when pulled out without cover, and when pulled out with cover. Some capless plugs are rated IP20, which means it’s touch-proof and resistant to dust or objects measuring over 12mm. However, it has no liquid protection and will be easily damaged if exposed to water mist. IP54, IP55 and IP65 ratings are common ratings when CCS plugs are capped or inserted. IP65 is more water resistant than IP54 units and is the same as IP55 units. IP54 and IP55 units are less dust resistant than IP65 units.

Operating Temperature Range: There is no standard for this specification. Ranges such as -30°C to +50°C and -40°C to +60°C are common, but there are extended ranges such as -55°C to +105°C (see TE Connectivity’s 2267220-3 above) ).

Temperature measurement components: This is standardized for AC contacts using PTC devices and DC contacts using Pt1000 sensors. The wording in the specs can get confusing here. AC units sometimes use “PTC” and sometimes “PTC chain”. The correct name would be “PTC Chain” as there is one PTC on each contact. If “PTC” is simply referenced in the specification, the designer should confirm that “PTC chain” is used. In the case of Pt1000 sensors, some data sheets mention Pt100 sensors, which are less sensitive and do not comply with CCS standards. It is a common mistake to refer to a Pt1000 sensor as a Pt100 device because “100” is more widely used than “1000”. The designer should confirm that it is indeed Pt1000 and has one on each contact.

Epilogue

AC and DC fast charging of BEVs supports the growing capacity of EV batteries and the need for extended driving range. AC fast charging is suitable for electric vehicles with relatively short driving distances. In addition, higher-power DC fast charging can charge the electric vehicle battery to 80% in a few minutes, supporting the needs of long-distance driving. CCS provides designers with a safe, smart, and efficient way to combine AC and DC fast charging in automotive and non-automotive applications.

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