SAE nears completion of standard for charging connector

  • 20-Apr-2009 09:12 EDT

SAE International's J1772 will standardize charging couplers.  General Motors

SAE International soon will put out for ballot a standard relating to vehicle electrification, helping to lay the foundation for greater sales of plug-in hybrid and pure-electric vehicles. The efforts behind that standard, J1772, will be highlighted during an SAE World Congress information session at 11:45 a.m. Tuesday in the FEV Powertrain Innovation Forum, Cobo Center, Detroit.

J1772 spells out the specifications for the coupler (consisting of a connector and vehicle inlet) through which current will flow into the vehicle from an outside source.

The standard as currently written specifies five pins for the connector, a Yazaki design of which was undergoing testing at Underwriters Laboratories as of late March, according to Gery Kissel, Engineering Specialist, RESS Charging Systems, Charging Codes, Standards, & Infrastructure, General Motors Corp. He is serving as Chair of the SAE Hybrid J1772 Task Force and is a member of the SAE Hybrid Technical Committee.

“The tricky parts of UL testing were done first—things like the connector must live through 10,000 insertions, it must be able to be driven over by a vehicle,” said Kissel in an AEI interview March 27. “We know those typical tests have already passed. So we’re into the more mundane tests now. And the supplier that tooled the connector has done internal testing. They’ve done the same testing as UL, but they did it internally so it can’t be certified. But they’ve passed all the tests. UL has done the difficult tests, and they look good.”

UL has committed to finish testing this month, Kissel noted.

“My goal is to have [J1772 standard] document ready before the UL testing is done so all we have to do in committee is take the finalized drawing, drop into the document, then go through the balloting process,” he said.

The purpose of the standard is to minimize costs and maximize simplicity for owners of electrified vehicles by avoiding the proliferation of different connectors and interfaces. “You don’t want 10 different connectors. By standardizing, you’re reducing costs and everyone is using the same thing. All the charging equipment you would pull up to in public would have the same identical connectors so any vehicle could use it. It will be a consistent, reliable interface,” Kissel explained.

The standard as now written addresses ac level 1 and ac level 2 charging; dc charging will be addressed at some point in the future, according to Kissel.

The coupler consists of:

• Two pins for power (ac line 1 and ac line 2/neutral)

• One pin for ground

• One pin for signals related to the amount of current allowed for the particular vehicle model being charged

• One pin for preventing the car from being moved while charging is under way.

In addition to electrical aspects such as the size and location of the various pins (there are three pin sizes), the standard addresses mechanical aspects such as the coupler’s outer shell and the latching function. It defines the space the handle may occupy, but not the design of the handle.

The coupler can be used for charging from 110- or 220-V outlets, both from home and from public charging stations.

The standard references the National Electrical Code for the cord and UL for shock protection, according to Kissel.

Kissel said “charging stations” is a misnomer in that they are mere suppliers of ac current to the vehicle. The actual charging devices are located on the vehicle and convert the stations’ ac current into dc current for the battery. The stations constitute what is called the EVSE (electric vehicle supply equipment), which provides shock protection, as well as a signal that is sent to the car that tells it how much current can be drawn. “That’s done so the circuit breakers upstream do not trip,” said Kissel. “You could plug a car in and if it’s a big, strong electric vehicle it wants to draw a lot of current; it wants to charge quickly. But a plug-in wants to draw a little less. So the [EVSE] equipment tells the vehicle, hey, you can have 12 A or you can have 50 A out of me. So, there’s that type of communication that occurs. The standard defines how that’s done.”

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