Tachometer generator is a micro generator measuring speed, he converts the input mechanical speed into a voltage signal output, and requires the output voltage signal to be proportional to the speed。

Tachometer generator classification: tachometer generator is divided into DC tachometer generator and AC tachometer generator two categories。

Dc tachometer generator: DC tachometer generator is essentially a miniature DC generator, according to the stator pole excitation mode is divided into electromagnetic and permanent magnet。The working principle of DC tachometer generator is the same as that of general DC generator。

Ac tachometer generator: the rotor structure of AC asynchronous tachometer generator has cage type and cup type, and hollow cup rotor asynchronous tachometer generator is used in the control system。There are two windings on the stator of hollow cup rotor asynchronous tachometer generator, one is the excitation winding and the other is the output winding。

The main errors of AC asynchronous tachometer generators are:

Nonlinear error: Due to the change of direct axis magnetic flux, the tachometer generator produces nonlinear error;

Residual voltage: In actual operation, when the rotor is stationary, the tachometer generator outputs a smaller voltage;

Phase error: Due to the leakage reactance of the excitation winding and the leakage reactance of the hollow cup rotor, the output voltage is different from the phase of the excitation voltage。

Ac synchronous tachometer generator is divided into: permanent magnet type, induction type and pulse type。