OICA response on discussion points on GTR draft _ September20 2013-09-20

Clause / Items / Summary of discussion at the 3rd EVS meeting
[not fully discussed comments in red] / Comments
General issue / SOC for REESS testing / Currently proposed by OICA at 50% SOC, Japan made a counterproposal to perform tests at 95% SOC (Reference document - EVS-03-16e.doc). Japan made a presentation summarizing the SOC applied in battery tests in various standards which indicated that 80-100% SOC is commonplace. China and US agreed that 50% SOC is not sufficient. OICA will reconsider this proposal. Japan indicated their presentation would be made available on the IG website(Reference document - EVS-03-22e.xls). / Rather than a single “one size fits all” SOC, there are nominated values in existing standards, depending on test in question BEV or HEV application.
A SOC of 95 % will not be achieved in HEV applications. Thus, for HEV applications a lower SOC limit should be sufficient. The exact number needs to be discussed.
3. / Definitions
3.3.
3.31. / Cell
Rupture / Clarification is required for the definition of (fuel) cell and rupture. OICA will look how terms are used in document and will modify definitions if appropriate. / 3.3. “Cell”
This term is taken from UN R100-02 which is based on UN38.3. and consistently used throughout the document. The technical description of this definition is not relevant for use as “fuel cell.”
3.31 “rupture”
The term “rupture” in OICA proposal is taken from UN R100-02 describing one of the criteria for the safety requirement of REESS, which is to prevent the direct contact to high voltage live parts in the REESS after the test. This term is used in consistent manner in OICA proposal (as well as in R100-02). ISO/DIS 12405-3 also contains the technically same definition for “rupture”.
Since OICA draft does not contain cell level testing, the term “rupture” is not intended to describe any events at cell level.
On the other hand, “rupture” in GTR No.13 (HFCV) describes totally different phenomenon which is also called as “burst” (which is similar phenomenon as “explosion” in R100-02).
3.9. / Electric power train / Korea Comment [Need for a definition of a traction motor?] / The term 'traction motor' is used in the definition for clause 3.9 only.
Conclusion:
A new definition is not necessary, but it makes sense to substitute 'traction motor' by 'electric traction motor' to clarify the description for the component meant.
5.1.1.2.4. / Isolation resistance
5.1.1.2.4.1. / Electric power train consisting of separate Direct Current or Alternating Current buses. / UL comment [How is the use of a wiring harness proof of meeting the criteria in a) below?
How is it determined that the protections are robust enough to last over the vehicle service life as noted in item b) below? How are motor housings electronic converter cases or connections determined to meet this criteria?]
UL comment [How is it determined whether or not isolation resistance requirements can be maintained over time? This statement seems a bit ambiguous. There should always be two levels of protection from electric shock and they should be still functional after testing.] / We assume this question is related to paragraph 5.1.1.2.4.2
Regarding subparagraph (a), we believe that "two or more layers of solid insulators, electrical protection barriers or enclosures" provides greater protection than a single layer. This principle is widely used in standards and regulations for electrical equipment. The example of wiring harness does not provide additional information (agree to delete).
Regarding subparagraph (b), we believe the intent is clear even though a completely objective evaluation methodology is difficult to define. Experience shows that a rigid, cast motor housing is providing a reliable physical barrier from exposure to high voltage.
We assume this question is related to paragraph 5.1.1.2.4.3
Regarding isolation resistance over time, it is noted that FMVSS 305 requires isolation monitoring as a condition for using less than 500 ohms/volt isolation on DC buses. However, this requirement is specified in consideration of deterioration of coolant used for FC stack.
5.1.1.2.4.2. / Electric power train consisting of combined DC- and AC-buses / Korea Comment [Note: FMVSS 305 requires the isolation monitoring system in the case there the lower level of isolation resistance is used.] / Regarding requirement of isolation monitoring system in FMVSS 305, it is specified to address potential deterioration of coolant used for FC stack. Requirement of isolation monitoring system has been specified in paragraph 5.1.1.2.4.3. of OICA EVS GTR draft as requirement for Fuel cell vehicles.
Isolation monitoring systems are not required for vehicles whose isolation resistance protection is unlikely to significantly deteriorate (practically EVs and HEVs.). Thus it is only required for FCVs whose isolation resistance may deteriorate (i.e. deterioration of coolant for FC stack).
IEC 60479 is showing differences of a.c. and d.c. currents regarding their effects on the human body. The different isolation resistance numbers are derived from those different numbers on a.c. and d.c. currents.
5.2.2. / Protection against electric shock / UL comment [Does this mean that Isolation Resistance does not need to be met if there are multiple parts of the high voltage bus exposed? I think that the statement needs to be re-worded to clarify the intent.]
UL comment [The requirements in 5.2.2.1 currently limit the voltage within 1 minute to the values noted in 5.2.2.1. Is there a peak limit value of voltage prior to the 60 seconds?] / For clarification: The isolation resistance does not provide protection in the case of two different accessible HV potentials. In such cases 5.2.2.1 (Absence of high voltage) or 5.2.2.2 (Low electrical energy) shall be met.
What is meant by “peak limit value”? How would voltage peaks differ from the nominal voltage regarding electric shock protection? There will be no voltage measurement prior to the 60 seconds.
5.2.2.2. / Low electrical energy / The US questions the value cited for minimum energy causing a safety concern (i.e. 0.2 J). The IG chairman agreed with OICA to organize a teleconference to address this topic specifically. All member of the IG are welcome to participate. / OICA continues to believe that allowing a low-energy option (of less than 0.2 Joules) to demonstrate post-crash electrical safety is appropriate. At the EVS-GTR meeting in Japan in April 2013, the OICA provided a technical rationale for the safety of 0.2 Joules. During a June 12, 2013 teleconference involving NHTSA, the Alliance and the OICA spokesperson, NHTSA indicated that it is reviewing that document.
OICA recognizes that it may be difficult to demonstrate that 0.2 Joules is precisely safety-equivalent to the specified isolation levels of 100 ohms/volt for DC buses and 500 ohms/volt for AC buses currently specified in MVSS 305. Nevertheless, a low-energy limit of 0.2 Joules surely meets the needs of motor vehicle safety, and has been recognized as a safe level in multiple codes and standards, including the Handbook of Electrical Safety published by the U.S. Department of Energy.
5.2.2.3. / Physical protection / The US requested OICA to quantify the likelihood of occurrence of the direct contact scenarios described by NHTSA. OICA will provide more data for this.
5.2.2.4.2. / Electrical power train consisting of combined DC- and AC buses / UL comment [There should be no evidence of fire or explosion without consideration of time frame. What about safety of first responders?]
Korea comment [Note – comment about measurement of isolation loss in RESS – diagrams in the test section may not cover this adequately] / We assume the UL comment refers to 5.2.3.3.
The 1 hour time limit is a practical number considering the procedure of a vehicle crash test. The purpose of a vehicle crash test is to demonstrate protection of vehicle passengers, also for conventional vehicles.
The described measurement method delivers an isolation resistance for all parts of the electric circuit, which are in contact with the DC voltage derived from the RESS. This includes the conductively AC circuits, if the power electronic IGBT's are in normal operation and perform an AC voltage output to the AC circuit or if a DC potential is switch to the AC circuit due to a malfunction of the power electronics. If after post-crash the power electronics shut down the IGBT's and therefore doesn't deliver any AC or DC potential to the AC circuit, than the AC circuit is excluded automatically from the isolation resistance measurement because of the fact that at this time there is no conductively connection between DC and AC circuit. This is in line with the electrical safety requirements according to 5.2. The safety requirements for the AC circuit part are fulfilled because of the fact that the absence of high voltage requirement is fulfilled. In this case it is not requested to fulfil in addition the isolation resistance requirement for an electrical circuit (neither DC nor AC).
Conclusion:
No change or corrections in test procedure necessary.
The measurement method using the vehicle's own REESS including the Figures 2 to 4 will deliver an isolation resistance value for the DC electrical circuit and if the AC circuit is conductively connected to the DC circuit a common value for the connected DC and AC circuit.
5.2.3.3. / Fire hazard / UL comment [There is no requirement for RESS exposure to water such as what may occur is located towards the bottom of a vehicle and driven through flooded viaducts. Why hasn’t this been considered, as there is evidence of field problems due to flooding of EVs in the US? Recommend including the immersion test or something similar from SAE J2464. It may be good to consider partial flooding as a potential field incident that could occur to an RESS located in a vehicle in a location that may be subject to flooding exposure such as underbody locations.] / This is not a post-crash issue.
Fire hazards of severely flooded vehicles are not specific to high voltage vehicles. In such case, it is assumed that there will be no occupant in the vehicle and therefore the issue shall be considered separately from EVS-GTR as cautions for the vehicle recovery/repair situation.
Since motor vehicle is a consumer product supposed to be used under various weather conditions, the robustness against usual exposure to water is well considered by the manufacturers. However, the critical scenario may widely vary depending on the design concept and configuration of whole vehicle systems, it will be difficult to define the uniform test procedure.
7.1.5. / Test conditions and test procedure regarding post-crash
7.1.5.2.6. / Electrolyte leakage / Korea comment [note – what is an appropriate coating? – specification needed? Gas sampling to detect electrolyte vapor? Difficult to measure on vehicle. Treat gas emissions in the environmental restrictions on hazardous substances? How is leakage measured?] / An “Appropriate coating” could be a fluid-absorbent material to confirm the electrolyte leakage.
This chapter considers liquid electrolyte leakage. Vapours are not defined as leakage and thus, are not be considered. Vapours could be considered as venting.
7.2.2. / Vibration test
7.2.2.1. / Purpose / US comment [Very much agree – but that is not called out in 7.2.2.3] / See Daimlers presentation on vibration
7.2.2.2. / Installation
-wording “REESS” / US comment [Explain – cells and connectors are not representative nor acceptable in these tests – only exception believed appropriate is where the RESS were divided into more than one unit on the vehicle and in that case both/all units would be tested] / As described in 3.30, a complete REESS includes various ancillary systems which may not be important for certain test configuration. A REESS does not necessarily means a battery pack.
A REESS may be composed of separate battery packs distributed in different location in the vehicle. In such a case, the test may be conducted on each battery pack (= REESS subsystem).
7.2.2.2. / - wording “Test device” / US comment [Call out stiffness requirements in engineering terms – ratios and ranges.] / The question seems to be related to the stiffness of the test rig to install the tested-device on the platform of the vibration machine as “firmly secured.
Note that OICA has not concluded yet if the original mounting positions and holders shall be used or not, as such components may absorb the vibration and the battery components will not subject to the intended vibration pulse, while it is the more realistic configuration on the vehicle. For the time being we would suggest to keep this proposal in square brackets.
7.2.2.3.2.2. / Test procedures / The vibration test procedure from UN 38.3 is used by OICA however different values for the vibration profile are used to make it representative of battery real-life application. The US requested more information on how representative this profile is of application in a vehicle and also why a test duration of 3 hours is chosen. OICA will provide data on this.
US comment [Regarding an observation period of 1h, 10 days or more, latent failures are issue]
US comment [Regarding the test environment, device must be tested for normal functionality via cycle testing] / The 1 hour observation period is sufficient to observe the Tested-device in safe (no fire, no explosion) period before the isolation resistance is carried out. The intention of this test is not to represent a battery life time (durability). The 3 hour test duration is taken from UN 38.3. For the relevance of the profile, please see the attached presentation by Daimler.