Power to Win
KB1037 - DC Motor Control
Many of the EFI Technology ECU products are capable of controlling a DC motor. The most common use for this type of output is for Drive by Wire throttle systems. The sensor on the drivers pedal provides the command signal to the ECU which in turn controls the engine throttle mechanically by driving the DC motor. A second sensor on the engine or motor itself provides feedback information to the ECU regarding the actual position.
Another common use of the DC motor output is for variable geometry inlet systems. The user can program a 3D map of the target position against two axes such as engine rpm and throttle. An additional sensor on the actual inlet position provides the feedback information to the ECU for the PID control loop.
If you have selected drive by wire mode under the configuration constants the target value is the current value of the pedal position sensor. Be sure to calibrate this sensor before tuning your system.
Increasing the gain will speed up the overall response of the DC Motor control. Using an excessive amount of gain may lead to overshoot and can induce oscillation. A general rule is to increment the proportional gain by a quarter of the previous value until the output becomes unstable and then back down the gain a small amount.
The safety controls are designed to detect an error in the drive by wire throttle system. If the engine throttle position fails to match the demand pedal by more than 7.5 degs in a 0.5 sec time period the motor is automatically disabled. To assist with initial tuning the safety controls can be disabled by checking the option under dc motor constants but it is recommended to leave active during normal operation.
Note: The safety control feature is only available when using the ECU internal DC motor driver. The optional high output external motor driver has no input to provide this function.
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