How do speed based PAS levels work ?

So I understand that controllers can have speed based PAS levels or power based PAS levels. For the speed based PAS levels are these controllers just applying maximum power at PAS level 1 until you hit the PAS level 1 max assist speed ? I wondered if it was done on Voltage - so PAS level one supplied a reduced voltage to the motor until you approach the "no load" max rpm for that voltage ? I just noticed that on the ebike motor simulator against the controller you have "throttle type" - Voltage, Amps or Torque

Edited August 30, 20232 yr by Peter.Bridge

It depends on programming. Some are crude, some are not so crude. The key difference is you get an acceleration bump at the beginning if it's speed based, you don't if it's current base. After a couple of seconds, the difference more or less disappears. I made two videos to illustrate the difference.

Speed controller:

 

Current controller:

The PAS is just a sensor. Each time a magnet passes the hall sensor/s it switches on or off the 5v coming to it, so the signal wire pulses with 5v.

 

The microprocessor in the controller (CPU) has logic that can check that input as pulsing or not, so it's a yes or no.

 

There are other inputs to the cpu that tell the controller what level you've selected on the control panel. The controller CPU has locic that creates a number from that selection from say 0 to 256. It then uses that number to decide how much speed to allow in proportion to that number, so 256 is maximum speed and 0 is none. With a 5 level control panel, that's 5 numbers and 5 different speeds. The throttle works the same. It gives out a voltage from 1.2 to 3.8v. Those 2.6v are devided up into 256 steps, so whatever voltage it has gives a proportional number that is used to decide how much speed to allow. The logic is therefore fairly simple because you can use the same number for each. Additionally, the CPU can have additional code to shape the power algorithms. they can ramp up and ramp down the power or do anything else the programmer wants.

 

In principle, current control works the same, except it can't use the throttle speed control algorithms, so it needs additional coding.

 

The more sophisticated the control system, the more code you need and the bigger and more expensive the CPU, so cheap controllers have simple control systems that can be a bit unfriendly. Expensive ones tend to be better.