Working principle and application of rotary transformer

1. The working principle of a rotating transformer. The magnetic flux distribution between the stator and the rotor of a rotating transformer conforms to the law of sine. Therefore, when the exciting voltage is applied to the stator windings, through electromagnetic coupling, the rotor windings generate electromotive force, as shown in figure 4-9. The output voltage depends on the angular position of the rotor, that is, it changes sine with the displacement of the rotor. According to the principle of transformer, the number of turns of primary side winding is n 1, the number of turns of Secondary Side Winding is n 2, k = N 1N 2 is transformer ratio, when the primary side input alternating voltage u 1 = Umsin t, the secondary side produces electromotive force e 2 = K 1 = Kumsin T. When the magnetic axis of Rotor windings and stator windings are at any angle, the electromotive force produced in the windings should be E2 = Ku1sin = Kumsin Tsin the form of: K Florida ratio; Maximum instantaneous voltage of a stator. When the rotor rotates parallel to the two magnetic axes, that is = 90 ° , the output voltage amplitude of the rotor winding of the rotating transformer varies strictly according to the Sinusoidal Law of the Rotor deflection angle, and the output voltage of the rotor winding of the rotating transformer is the maximum, that is, E2 = Kumsin t, when the rotor rotates parallel to the two magnetic axes, that is, = 90 ° , the frequency is the same as the amplitude of the excitation voltage. (2) application of resolver. As a position detection device, resolver can be used in two ways: phase detection and amplitude detection. 1. In phase discrimination mode, the input amplitudes of two-phase quadrature windings of rotating transformer stator (sine is represented by s and cosine by C) are equal to those of sine windings and cosine windings, respectively, the sine and cosine excitation voltage of the same frequency us = Umsin t = umcos t two phase excitation voltage will produce electromotive force in the rotor winding. According to the linear superposition principle, the induced voltage in the rotor winding is u = Kussin machine + Kuccos machine = Kumcos (t-machine) , where K is the ratio of variable voltage. So as long as the phase angle of the output voltage of the rotor is detected, the rotor angle of the rotor is known, and the rotor of the rotating transformer is connected with the servo motor or the drive shaft, thus, the linear or angular displacement of the actuator can be obtained. 2. Amplitude discrimination works by connecting stator's two windings to the same frequency and phase, but with different amplitudes, that is, the amplitude-modulated excitation voltage us = UMSIN SIN T UC = umcos t on the Rotor windings is u = Kussin machine + Kuccos machine = Kumsin t (sin machine + cos machine) = Kumcos (machine) sin T in practical application, the Mechanical Angular displacement machine can be obtained by continuously modifying the electric angle of the exciting magnetic amplitude modulation voltage, making the change of the tracking machine and measuring the amplitude of the induced voltage.