Permanent magnet synchronous generator based direct current power generating system

Abstract

A method of compensating for rotor position error of a rotor of a permanent magnet synchronous generator (PMG) that provides electrical power to a direct current (DC) power generating system, the method including obtaining PMG phase voltages and resolver processed angular position output when the PMG is driven by a prime mover. Once obtained, a PMG fundamental phase voltage waveform is selected by eliminating higher order harmonics. A mechanical angle of the rotor is then converted into an electrical angle, then the electrical angle is aligned within the mechanical angle with a corresponding PMG fundamental phase voltage angle by adjusting offset to the electrical angle. After alignment, a plurality of resolver error offset values associated with the electrical angle are stored and additional values to the compensation table are added by interpolating data between two corresponding resolver error offset values of the plurality of resolver error offset values.

What is claimed is: 
     
         1 . A method of compensating for rotor position error of a rotor of a permanent magnet synchronous generator (PMG) that provides electrical power to a direct current (DC) power generating system, the method comprising:
 obtaining PMG phase voltages and resolver processed angular position output signals by a resolver-to-digital (R/D) converter of the DC power generating system when the PMG is driven by a prime mover;   selecting a PMG fundamental phase voltage waveform by eliminating higher order harmonics;   converting a mechanical angle of a rotor into an electrical angle by an electrical angle and frequency derivation component of the DC power generating system;   aligning the electrical angle within the mechanical angle with a corresponding PMG fundamental phase voltage angle by adjusting offset to the electrical angle;   storing a plurality of resolver error offset values associated with the electrical angle into a computer readable storage medium of a digital signal processor (DSP) component; and   adding additional values to the compensation table by interpolating data between two corresponding resolver error offset values of the plurality of resolver error offset values by a computer processor of the DSP component.   
     
     
         2 . The method set forth in  claim 1  further comprising:
 running the prime mover at a pre-determined speed before obtaining the PMG phase voltages. 
 
     
     
         3 . The method set forth in  claim 2  further comprising:
 feeding an excitation signal to a resolver rotor coil; 
 feeding sinusoidal and cosine-shaped signals from respective coils of a resolver associated with a rotor of the PMG; 
 deriving angular and speed values by the R/D converter; and 
 feeding the angular and speed values to the DSP component before running the prime mover. 
 
     
     
         4 . The method set forth in  claim 3 , wherein the resolver comprises a two-pole resolver. 
     
     
         5 . The method set forth in  claim 4 , wherein the resolver is frameless. 
     
     
         6 . The method set forth in  claim 3 , wherein the PMG includes about twenty-eight poles. 
     
     
         7 . A vehicle comprising:
 a prime mover;   a PMG including a rotor coupled to the prime mover for rotation;   a resolver including an excitation coil, a first coil and a second coil positioned approximately ninety degrees from the first coil, and wherein the excitation coil and the first and second coils are associated with the rotor;   a resolver processing and compensation system configured to receive sinusoidal and cosine-shaped analog signals from the respective first and second coils, convert the analog signals to a digital signal corresponding to an absolute angular position of the rotor, and compensate for angular position error;   a DC electrical load configured to receive DC power from the resolver processing and compensation system; and   a vehicle supervisory controller configured to manage DC power distribution.   
     
     
         8 . The vehicle set forth in  claim 7 , wherein the DC electrical load comprises an electric traction drive. 
     
     
         9 . The vehicle set forth in  claim 7 , wherein the vehicle is an electric automobile. 
     
     
         10 . The vehicle set forth in  claim 7 , wherein the vehicle is a hybrid automobile. 
     
     
         11 . The vehicle set forth in  claim 7 , wherein the prime mover is an internal combustion engine. 
     
     
         12 . The vehicle set forth in  claim 7 , wherein the resolver processing and compensation system includes a computer readable storage medium configured to store a speed compensation table and a position compensation table for storing offset data associated with the angular position error and used by a computer processor of the resolver processing and compensation system to expand the respective speed and position compensation tables by interpolating the stored offset data. 
     
     
         13 . A DC power generating system comprising:
 a PMG including a rotor;   a resolver including an excitation coil, a first coil and a second coil positioned approximately ninety degrees from the first coil, and wherein the excitation coil and the first and second coils are associated with the rotor;   an excitation component configured to electrically excite the excitation coil;   a resolver-to-digital converter configured to receive first and second analog signals from the respective first and second coils and convert the first and second analog signals to respective digital rotor angle and digital rotor speed signals; and   a digital signal processor component configured to receive the digital rotor angle signal and the digital rotor speed signal, convert to an electrical angle and compensate for angular position error of the rotor.   
     
     
         14 . The DC power generating system set forth in  claim 13 , wherein the digital signal processor component includes a computer processor, and a computer readable storage medium configured to store a speed compensation table and a position compensation table for storing offset data associated with the angular position error and used by the computer processor to expand the respective speed and position compensation tables by interpolating the stored offset data. 
     
     
         15 . The DC power generating system set forth in  claim 14  wherein the angular position error includes a position angle error and a speed angle error.