Speed Regulator Modes
The Speed regulator mode parameter sets the primary control mode for motor operation. ASI BAC controllers support three regulation modes that determine how the motor responds to input commands.
Mode Overview
| Mode | Value | Control Type | Speed Limiting | Best For |
|---|---|---|---|---|
| Speed Mode | 0 | Speed-based | Yes | Applications requiring consistent speed |
| Torque Mode | 1 | Current-based | No | Maximum performance |
| Torque with Speed Limiting | 2 | Current-based | Yes | E-bikes (recommended) |
Speed Mode (Mode 0)
In Speed mode, the controller targets the commanded speed and manages torque accordingly.
Characteristics
- Controller maintains target speed under varying conditions
- Output torque adjusts automatically to maintain speed
- Speed is actively limited to the configured maximum
- Suitable for applications requiring speed consistency
Not Recommended for E-Bikes
Speed mode is not recommended for e-bike applications. Use Torque mode with speed limiting (Mode 2) instead.
Configuration Requirements
Switching Frequency
If Control command source is set to any source other than 0 (Serial stream), you must change switching frequency to 10000 Hz for Speed mode to function. The default 13000 Hz is incompatible.
Get Access Level
Enter Parameter access code 15350 to get user access level 1.
Change Switching Frequency
Set Switching frequency to 10000 Hz.
Bluetooth Impact
You will lose Bluetooth connectivity at 10000 Hz. Use TTL or CAN for communication.
Save and Reboot
Save to flash and reboot the controller.
Verify Frequency
Confirm Switching frequency is now 10000 Hz.
Set Speed Mode
Change Speed regulator mode to 0 (Speed).
Configure Speed Limits
Set appropriate speed limits (see Speed Limits section below).
Save Configuration
Save to flash.
If Control command source is set to 0 (Serial stream), simply change Speed regulator mode to 0 without switching frequency changes.
Torque Mode (Mode 1)
In Torque mode, the controller targets the commanded current output using the current control loop.
Characteristics
- Direct current/torque control
- Motor spins as fast as possible given available torque and system load
- No speed limiting - motor speed limited only by back-EMF and load
- Maximum performance and responsiveness
Danger - No Speed Limit
Torque mode does not limit speed. Depending on ramp rate and tuning parameters, this could damage your setup. Exercise caution when testing.
Configuration
Simply change Speed regulator mode to 1 (Torque). This is the default configuration value.
Torque Mode with Speed Limiting (Mode 2)
This mode combines torque-based control with active speed limiting - the recommended mode for most e-bike applications.
Characteristics
- Targets commanded torque (same as Torque mode)
- Active speed limiting prevents exceeding configured maximums
- Best balance of performance and safety for e-bikes
- Optional variable speed limit based on throttle position
Configuration
Set Mode
Change Speed regulator mode to 2 (Torque mode with speed limiting).
Configure Speed Limits
Set appropriate speed limits for your application (see below).
Optional: Variable Speed Limit
Enable Features2 bit 11 (Throttle mapping on speed for torque mode) to enable variable speed limit based on throttle position.
Speed Limit Configuration
Speed limits are configured based on the active mode and command source.
Speed Limit Parameters
| Parameter | Address | Description | Units |
|---|---|---|---|
| Vehicle maximum speed (Street mode PAS max speed) | 123 | PAS speed limit in Street mode | km/h |
| Vehicle maximum speed (Race mode PAS max speed) | 124 | PAS speed limit in Race mode | km/h |
| Vehicle maximum speed (Street mode Throttle max speed) | 229 | Throttle speed limit in Street mode | km/h |
| Vehicle maximum speed (Race mode Throttle max speed) | 236 | Throttle speed limit in Race mode | km/h |
| Vehicle jog speed | 230 | Walk mode and reverse speed limit | km/h |
| Vehicle jog speed2 | 252 | Boost mode limit, anti-theft inhibit speed | km/h |
Speed Limit Behavior
| Input Source | Applicable Limits |
|---|---|
| Throttle | Throttle max speed parameters |
| Pedal/PAS | PAS max speed parameters |
| Walk mode | Vehicle jog speed |
| Reverse | Vehicle jog speed |
PAS vs Throttle Limits
"PAS" limits apply to pedal assist and all other power limits except throttle. Consider it the default power source limit.
Ramp Rate Configuration
Each mode uses different ramp rate parameters to control acceleration and deceleration behavior.
Speed Mode Ramp Rates
For Speed regulator mode 0:
| Parameter | Function | Recommended |
|---|---|---|
| Speed mode positive acceleration | Target acceleration rate | 4, 8, or 16 |
| Speed mode Regen ramp | Target deceleration rate | 48 |
Value interpretation:
- 16 = 1× rated RPM in 1 second
- 32 = 0.5× rated RPM in 1 second
- 8 = 2× rated RPM in 1 second
Ramp Relationship
Speed mode positive acceleration should be less than Speed mode Regen ramp for stable operation.
Torque Mode Ramp Rates
For Speed regulator modes 1 and 2:
| Parameter | Function |
|---|---|
| Positive motoring torque ramp | Current ramp-up when commanding (throttle on) |
| Negative motoring torque ramp | Current ramp-down when reducing (throttle off) |
| Positive braking torque ramp | Regen current ramp-up |
| Negative braking torque ramp | Regen current ramp-down |
See System Tuning for detailed ramp rate configuration.
Mode Selection Guidelines
Use Speed Mode (0) When:
- Application requires maintaining exact speed under varying loads
- Industrial applications with consistent speed requirements
- Not recommended for personal electric vehicles
Use Torque Mode (1) When:
- Maximum performance is required
- Speed limiting is handled externally
- Testing or specialized applications
- Operator understands speed is unlimited
Use Torque with Speed Limiting (2) When:
- Building an e-bike or personal electric vehicle
- Need both responsive torque control and safety limits
- Regulatory compliance requires speed limiting
- Want the best balance of performance and safety
Troubleshooting
Motor Doesn't Respond in Speed Mode
| Issue | Solution |
|---|---|
| Wrong switching frequency | Set to 10000 Hz for non-serial control sources |
| Control source conflict | Verify Control command source setting |
| Speed limits too low | Check and increase speed limit parameters |
Speed Limiting Not Working in Mode 2
| Issue | Solution |
|---|---|
| Wrong parameters set | Verify using correct PAS/Throttle limits for input |
| Assist gain too high | Check assist level configuration |
| Speed sensor issue | Verify wheel speed sensor configuration |
Excessive Acceleration/Deceleration
| Issue | Solution |
|---|---|
| Ramp rates too aggressive | Increase ramp time values |
| PI gains too high | Reduce Speed regulator Kp/Ki |
| Wrong mode for application | Consider switching to Mode 2 |
Key Parameters Reference
| Address | Parameter | Function |
|---|---|---|
| 119 | Speed regulator mode | 0=Speed, 1=Torque, 2=Torque+Limit |
| 117 | Speed regulator Kp | Proportional gain for speed control |
| 118 | Speed regulator Ki | Integral gain for speed control |
| 123 | Vehicle maximum speed (Street mode PAS) | Street mode PAS limit (km/h) |
| 124 | Vehicle maximum speed (Race mode PAS) | Race mode PAS limit (km/h) |
| 229 | Vehicle maximum speed (Street mode Throttle) | Street mode throttle limit (km/h) |
| 236 | Vehicle maximum speed (Race mode Throttle) | Race mode throttle limit (km/h) |
| 230 | Vehicle jog speed | Walk/reverse limit (km/h) |
| 125 | Speed mode positive acceleration | Speed mode accel rate |
| 126 | Speed mode Regen ramp | Speed mode decel rate |
Next Steps
- Configure System Tuning for control loop optimization
- Review Features Configuration for assist levels and modes
- Set up Braking Systems for regenerative braking