Load control is an alternative to PID control. It can be used when you want to sweep through the RPM register of the engine. In this mode Brake = (RPM – Reference RPM) * Gain.
You don’t need to understand the maths behind this regulator. You should know the following:
Load control is useful for non linear systems, slow brake control, very fast torque increases and in general any time PID is difficult to make stable. In particular it works well for water brakes.
The main benefit over the PID is that Load Control does not have an integrator component. The integrator in the PID regulator is the component that works to keep the RPM error low. While this may sound like a good thing, it is actually one of the main causes of PID regulators getting into instabilities. If the engine has a steep torque curve, it may accelerate faster than the brake can react, but the integrator component will bring the RPM back into where it should be. This however needs careful tuning since it must not react too much, or you risk oscillations. For Eddy brakes this typically is no problem. But for water brakes and some other brakes it is a problem.
With Load Control you set an acceleration (RPM/second) and the regulator will keep the acceleration roughly that. In RPM areas of large torque increase (where the turbo kicks in for example), the RPM will increase a bit more than the set rate, but that is completely normal and ok. Power/Torque is anyway measured at the actual RPM, not the set RPM. By allowing the engine to accelerate more naturally (i.e. not a completely straight line), it makes controlling the RPM without oscillations much easier.