Table of Contents

1. Introduction
2. Torque mode ramp rates
3. Speed mode ramp rates
4. Configuration parameters
5. Troubleshooting

1 – Introduction

The fundamental factors affecting acceleration are available torque-producing current and the imposed power limits. Following this, acceleration can be tuned using the following acceleration ramp limits.

Secondary factors including the current regulation control loop and for speed limited modes only, the speed regulation control loop will affect the acceleration of the system.

At a certain point, if acceleration is insufficient, the application may need a motor with a better torque constant, Kt [N-m/A] or more current than the controller can output.

Note:

• Torque mode ramp rates apply when Speed regulator mode is set to 1 / Torque mode (default) or 2 / Torque with speed limiting.
• Speed mode ramp rates apply when Speed regulator mode is set to 0 / Speed.

Torque mode ramp rates

Torque mode ramp rates apply when Speed regulator mode is set to 1 / Torque mode (default) or 2 / Torque with speed limiting.

Acceleration ramp rates

The current output to the motor is ramped up according to the Positive motoring torque ramp when commanding current (e.g.: on the throttle) and ramped down according to the Negative motoring torque ramp when reducing commanded current (e.g.: off the throttle).

Pedal sensor ramps are controlled separately, but similarly, as above via the Pedalec positive motoring torque ramp and the Pedalec negative motoring torque ramp.

Setting these ramps too low can cause acceleration to be jarring, possibly damaging mechanical components. Setting these ramps too long can make the acceleration seem very slow (positive ramp) or continue to accelerate for too long (negative ramp). Care must be taken when adjusting these parameters, adverse riding can occur if set improperly.

The ramp dictates that peak output current, Rated motor current, will not be achieved faster than its set value relative to no current output when positive. Vice-versa for the negative ramp, 0 current will not be achieved faster than its set value from peak current output. This value, time, is in milliseconds [ms]. The ramp is linear. To effectively eliminate these ramps, set the values to 1.

Speed limit ramp time

In Speed regulator mode torque with speed limiting, the Speed limit ramp time can be used to limit the acceleration of the system relative to the speed limit, by limiting current output. This can be used to improve engagement and reduce clutch wear in geared hub drives or take up slack in chain drive systems, for example.

Some people have found setting this parameter helps reduce instantaneous overcurrents in applications prone to faulting when accelerating with slack in the drive train.

The ramp rate is linear and only takes effect from 0 rpm.

Setting this parameter to 0 disables it.

Braking ramp rates

The current input from the motor to the battery (e.g.: regen braking), is ramped up according to the Positive braking torque ramp and ramped down according to the Negative braking torque ramp.

Setting the Positive braking torque ramp too low can cause the regen to ramp too quickly and possibly lock up the wheel, we recommend 200ms or longer ramp rates.

The ramp dictates that peak input current from the motor will not be achieved faster than its set value relative to no current input when positive. Vice-versa for the negative ramp, 0 current will not be achieved faster than its set value from peak current input. This value, time, is in milliseconds [ms]. The ramp is linear. To effectively eliminate these ramps, set the values to 1.

Speed mode ramp rates

Speed mode ramp rates apply when Speed regulator mode set to 0 / Speed.

Acceleration and regen (braking) ramp rates

Acceleration is controlled primarily by the Speed mode positive acceleration and deceleration by Speed mode Regen ramp. These parameters adjust the target ramp rate from 0 to the speed limit. Possibly a little confusing to set: a value of 16 is 1x rated rpm in 1 second, 32 is 0.5x rated rpm in 1 second and 8 is 2x rated rpm in 1s.

It is not recommended to set the Speed mode Regen ramp slower than Speed mode positive acceleration, meaning the Speed mode positive acceleration value in BACDoor™ should be less than the Speed mode Regen ramp value. 48 is a good default value for Speed mode Regen ramp. 4 / 8 / 16 are good values to start with for Speed mode positive acceleration.

Regeneration battery current limit > 0% is required for Speed mode Regen ramp to work/do anything. Features bit 13, engine braking, must be enabled as well when the Control command source is >0.

Configuration parameters

Torque mode acceleration tuning parameters

Speed mode acceleration tuning parameters