Generally, the HPPC test is used to calculate the battery peak charge/discharge power. However, I wanted to calculate the battery peak charge/discharge power under drive cycle test condition such as UDDS, US06 and FUDS.
Thanks in advance.
Hi Prashant,
as you know, emissions drivecycles are intended for whole-vehicle use and are usually intended for emissions/efficiency evaluation on combustion engined vehicles. The drivecycles represent in-traffic operation of the vehicle and so don't usually involve continuous full power operation of the powertrain.
The HPPC test for battery testing as you say aims to find the full power limit of a battery or cell, which is usually defined by the voltage drop or temperature rise reaching the manufacturer's limits, although other effects are sometimes also seen.
If you have a datalog of an EV battery voltage, current, SOC and temperature from a real or simulated drivecycle run then you will be able to estimate the internal resistance/ voltage drop under transient conditions and at variable temperatures and varying SOC. What you won't be able to see is the relationship between internal resistance and temperature, and the temperature rise resulting from continuous operation (although the SFTP probably comes closest to this condition). Can you run your drivecycle tests at different temperatures? and with different starting SOCs? This would help.
So- yes, you can use drivecycle behaviour to estimate HPPC results, but it won't be very accurate.
Hope this helps,
Robert
Dear Robert,
Thanks for your response.
Sure, I will run the test on your suggested operating conditions.
Can you please suggest that which drive cycle can give more accurate or close SOP value to HPPC?
Currently, I am using drive cycles (FUDS, US06, UDDS and WLTP ) for my experimental study.
Best Regard
Prashant
If you want to get the real SOP of a certain discharge or charge point, you have to use different powers to discharge or charge the battery untill the cut-off voltage. For example, you want to get the real discharge SOP of 10s, you can use 2 different powers to discharge battery to the cut-off voltage within 10s and another 2 different powers to discharge battery to the cut-off voltage more than 10s. And through fitting the above four data points, you can get the real discharge SOP of 10s.
Dear Dr,
Thanks for your response.
I have one doubt about the experimental setting.
We need to complete discharge e.g. (100% SOC to 0% SOC) the cell within 10s?
It will not damage the cell?
Best Regards
Prashant
Hi Prashant,
The 10s discharges would each only take out a small amount of charge (depending on the discharge power and the capacity of the cell). The objective is usually to measure the available power at a particular SOC and temperature.
On your drivecycles, do you have to use a standard. legislative drivecycle (like the FTP, etc that you mentioned) or can you make up a drivecycle yourself?
If you can make up a drivecycle, then building in a 10s acceleration phase at constant vehicle power, or a 10s constant speed phase (which will also be at a constant power) would make things easier.
As Zhongwei says, doing these at different power levels is useful (also different starting SOC levels and temperatures).
Regards,
Robert
Dear Robert,
Thanks for the valuable explanation.
It will help me in experiment.
Regards,
Prashant
