Speed Feedback
Speed feedback is the measurement of the engine's actual speed and its delivery to the controller; the system then targets speed directly rather than throttle position. If speed drops when load comes on, the controller opens the throttle by itself. This is the only way to hold speed constant under load.
It must not be confused with position feedback. Position feedback guarantees that the actuator is at the desired place; speed feedback guarantees that the engine is turning at the desired rate. These are different quantities and one does not substitute for the other.
- The measurement source can be a magnetic pickup reading the flywheel teeth, a Hall sensor, or the alternator W terminal.
- The controller moves the throttle lever to close the error; its target is not position but rpm.
On AXI products the situation is this: the standard GS740 kit and the GS740-3P do not measure speed, so they contain no speed feedback. The GS740-3P's closed loop is on actuator position. The optional active-feedback speed stabilisation module declared for the GS740, however, includes a sensor that reads engine speed, and that module provides the speed feedback. If frequency stability is required on a generator, this distinction directly determines your selection decision.
Context in which this term is used: Electronic speed and throttle control on a diesel engine