Rotary transformer in rotor position measurement

Introduction In military vehicle AC drive system, due to slip rings shock and vibration and the change of temperature and humidity and other harsh working environment, ordinary detection of rotor position encoder is easy to damage, and the rotary transformer due to its durability and high reliability, it can solve this problem. But a rotary transformer is a simulation of mechanical and electrical components, can not meet the requirements of digital, so it is necessary to realize the interface circuit of analog signal and control system digital signal conversion between, this kind of interface circuit is a kind of special mold / number converter, is what we often say that the resolver / digital converter ( RDC ). RDC circuit design The main device and principle This system uses the Tamagawa Japan produced TS262N21E11brushless resolver. Main circuit adopts the ADI two R/D converter AD2S90and programmable oscillator AD2S99, two to use. AD2S90RDC circuit is the core design. Internal function modules is mainly composed of a phase sensitive detector, a multiplier, a voltage-controlled oscillator VCO), an up-down counter to slipring form a closed loop feedback system. When the rotary transformer two stator winding output signals Esinwtsinq and Esinwtcosq were sent to AD2S90sin and COS input pin, through its internal operational sent to the multiplier, at this time, if the internal or the counter output initial digital angle J is fed to a multiplier, the multiplication is obtained after the output signal is Esinwtcosqsinj and Esinwtsinqcosj, two and then subtract operation will be the output signal Esinwtsin ( q-j ), the errors in the signals section is fed by a phase sensitive detector, a multiplier, a voltage controlled oscillator, an up-down counter to form a closed loop feedback system, so that the sin ( q-j ) =0, q-j=0, when the up-down counter output digital angle J is the rotor displacement angle. AD2S99 is designed for resolver-digital converter provides excitation signal source, signal frequency has 4 choices, namely 2kHz,5kHz,10kHz and 20kHz. It not only provides for AD2S90synchronous reference voltage signal, at the same time also rotating transformer to provide high quality sine wave excitation signal, also has a signal phase compensation and signal loss detection etc.. RDC circuit design Rotary joint transformer two winding output signals SINJ and chose as AD2S90angular position detection of the analog signal input, through a shielded twisted pair, respectively, received AD2S90 corresponding to the input SIN and SINL0. At the same time, COS and COSL0signal as feedback signals are connected to the AD2S99, through the AD2S99the internal processing to produce an output signal ( SYNREF± 3Vp-p square wave output signal and the phase and the SIN and COS input signals to maintain consistent ), connected to AD2S90REF pins, to compensate for the rotary transformer side to the two side of the phase deviation RDC, otherwise it will reduce the accuracy of conversion.