--- /dev/null
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+ "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+<head>
+ <title>[[!meta title="Raspberry Pi Permanent Magnet Synchronous Motor (PMSM) Control"]]</title>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+ <link><style type="text/css">
+ #main_content {max-width: 70em}
+ </style>
+</head>
+<body>
+
+<div id="main_content" style="max-width: 60em;">
+
+<p>
+[[!rpi_pmsm_motor_control.png size="300x" align=right alt="Simulink connected to RPi running PMSM control model"]]
+<a href="http://en.wikipedia.org/wiki/Raspberry_Pi">Raspberry Pi</a> is often
+used for education and many hobbyists tasks but it is not equipped with hardware
+peripherals required for a quite complex vector electric motor control task.
+This project sumplements bare Raspberry Pi board by two other boards to implement
+complete educational BLDC/PMSM motor control system. One board uses small
+Microsemi IGL00 FPGA to implement missing peripherals and the second board
+implements 3-phase power stage with current sensing, ADC and galvanic
+isolation which can be used in this project or even connected
+to Altera DE2 education kits.
+</p>
+
+<h2 id="psmscontrol">Three-pases PMSM Control Basics</h2>
+<p>
+The differences between Voltages connected to the three stator windings
+terminals cause current flow which forms rotating magnetic field.
+The direction and magnitude of this field drive permanent magnet
+rotor which is to align with the direction of the magnetic field vector.
+North pole is attracted to the south and vice versa. For constant speed
+and torque, the waveforms of the phase Voltages (the same for currents)
+are sinusoidal with an equidistant phase shift of 120 deg. The three phases
+system is in some respect redundant, in the case of Voltages (u<sub>A</sub>,
+u<sub>B</sub>, u<sub>C</sub>) only differences count, i.e. one can be
+fixed to zero. A sum of the three currents (i<sub>A</sub>, i<sub>B</sub>,
+i<sub>C</sub>) has to be zero by the Kirchhoff's current law. As a consequence,
+only two independent quantities/scalars are needed to describe the currents
+or Voltages which are in the fact vector in the 2D space. The polar coordinates
+system can be used but a rectangular system of alpha, beta components is equivalent
+and easier for transformations computation. This transformation of the three phase
+system to the two orthogonal components vector is named according to its
+inventor Clark transformation. The waveforms in this 2D system are sine
+and cosine for steady speed state. Because realization of a controller
+in this altering components system is not feasible, another transformation
+was invented which convert the quantities to the coordinates fixed to
+the revolving rotor. A base formed by direct (D) component aligned to North,
+South pole direction of the rotor and orthogonal quadrature (Q) has been
+introduced by Robert H. Park and the transformation is named according to him.
+The control in the D-Q coordinates is (almost) independent of actual rotor
+position and (in simplified outlook) separates reactive current (i<sub>D</sub>)
+from the active current (i<sub>Q</sub>) resulting in torque affecting rotor
+movement.
+</p>
+[[!img pxmc-pmsm-block.png size="300x" align=right alt="Basic PMSM control setup diagram from PXMC library documentation"]]
+
+</div>
+
+</body>
+
+</html>
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projects / ert_linux_web.git / commitdiff
