Does anyone know how to set a maximum current that the ACX1 controller can draw from the pack? My pack is fused at 600A, and I want to make sure that cannot be exceeded.

There is a 'motor limit current map' in the SME software, might this be it?

A current limit in a controller would normally be motor current, not DC link current, and I agree with this conclusion:

The Tau software has a Motor Current Limit Map, example attached. It shows that 100% of the maximum current can be drawn for any motor speed (the red line), whereas the green line shows the percentage of maximum current that the controller can supply to the pack under regen.

The units imply that 750 A RMS is the maximum current that can be drawn (I’m using the low voltage Hyper 9 system).

I am assuming that because it refers to A RMS, it’s likely to be referring to AC motor current, not DC pack current.

There is no need for a motor controller to even be aware of the DC link current, except to protect itself; in a rational integrated system, the BMS would tell the motor controller when power demand needs to be reduced to protect the battery, regardless of the current from the battery (depending instead on a more sophisticated combination of temperature, and trends over time of current).

Netgain’s webpage refers to “750A Peak”, which is not the same as 750 A RMS in the Tau software, and also not the same as the 850 Amps that the performance charts (such as the one from Negain) above shows.

The way it is given on the NetGain motor page

for the HyPer 9 IS, the 750 A looks like a battery current peak, because it is given with battery voltages. That is not the same as motor current, and it is not apparent where NetGain got this value.

The HyPer 9 and HyPer 9HV specs show about the same maximum power from the battery - with about 1.5 as much voltage as the regular model, the HV uses about 2/3 of the maximum current, which makes sense.

If you look at the peak performance data published by NetGain for various voltages, calculate the DC link for corresponding to peak power based on mechanical output power and efficiency, and divide by the (approximate) DC link voltage you get the peak DC link current in that test.

For example:

at 72 V DC link, peak power is 60.3 kW and efficiency is 91.7% so electrical input power must have been 60.3*1000 W / .917 = 65,758 W, and so current was 65,758 W / 72 V = 913 A.

Here are all of these values for the published peak performance charts for the regular HyPer 9 and HyPer 9HV systems:

System | DC Link test voltage
V | peak mechanical power
kW | efficiency at peak power
% | calculated input power
kW | calculated DC link current
A |

HyPer 9 | 72 | 60.3 | 91.7% | 65.8 | 913 |

HyPer 9 | 84 | 71.4 | 93.0% | 76.8 | 914 |

HyPer 9 | 96 | 81.3 | 93.9% | 86.6 | 902 |

HyPer 9 | 108 | 93.9 | 93.5% | 100.4 | 930 |

HyPer 9 | 120 | 102.8 | 94.3% | 109.0 | 908 |

HyPer 9 | 132 | 112.8 | 93.7% | 120.4 | 912 |

HyPer 9HV | 120 | 73.0 | 93.8% | 77.8 | 649 |

HyPer 9HV | 132 | 80.3 | 93.2% | 86.2 | 653 |

HyPer 9HV | 144 | 88.0 | 93.8% | 93.8 | 652 |

HyPer 9HV | 156 | 95.5 | 94.4% | 101.2 | 648 |

The current can be much more than 750 A for the regular (not HV) version, even at the highest voltages. It isn't a constant value, but it's close enough (given that the DC link voltage is only an approximation) for a given system (regular or HV), that I suspect that the controller has an internal input (DC link) current limit.

So I am confused … all I want to do is limit the max DC current draw from my pack to 600A. I did try reducing the Drive % limits to about 450A RMS, but the car was undriveable, I could barely get to 20mph. Any help in interpreting these various current units gratefully received ...

Various information tracked by the controller could be used in logic to set a limit, if the current is not directly available, but the obvious solution is to use the input power (or even just output power... whatever is available) and divide that by battery voltage (or even just a constant nominal voltage is actual battery voltage isn't available) to calculate what the battery current must be... and limit that if you can.

Alternatively, if there is a configurable power limit, just set that to the value corresponding to the maximum battery current that you can tolerate multiplied by the lowest battery voltage that you will be using... and be unnecessarily limited in power when battery voltage is higher.

The best solution is obviously to find the actual input current limit parameter in the software, but of course that's exactly what you're asking for.