DSP-based AC pm synchronous linear motor with vector control system design (1)

Summary: in a comparison of rotating electrical machines and linear motor difference based on the analysis of the AC pm synchronous linear motor structure characteristics.

And particularities of the linear motor for AC pm synchronous linear motor speed control of vector control methods, made based on DSP control system hardware and software design.

1 Introduction

Manufacturing industry in need of linear driving force, the traditional method is to use rotating electrical machines and ball screw.

Practice has shown that in many high-precision, high speed, the driver has revealed deficiencies. In this case linear motors came into being. Linear motor directly produce linear motion, without intermediate conversion points, the power is in the air-gap magnetic fields directly, you can get higher than traditional drive mechanism for several times the positioning accuracy and fast response speed [1]. Currently, the United States, Japan, Germany, Switzerland, is a straight line direct drive system level relatively high SIEMENS countries, companies such as Kollmorgen has the commercialization of the product [2]. Domestic research and development of the linear motor attaches great importance, many institutes have conducted experiments, but did not achieve industrialization. This article is in my Department to develop AC pm synchronous linear motor basis based on vector control drive system design applications.

2. AC pm synchronous linear motor works

Linear motor works like along radial expansion of rotating electrical machines.

AC flux permanent magnet synchronous linear motor into three-phase AC current, in the air gap in magnetic field, regardless of the end-effect, the magnetic field in a straight line direction is sinusoidal distribution. Traveling-wave field and secondary interaction produce electromagnetic force, the primary and secondary production relative motion. Figure 1 shows the development of the design of the AC pm synchronous linear motor.

3. linear synchronous motor with vector control principle

Because vector control fast dynamic response, compare scalar control, fast time to reach steady state.

After 30 years of industrial practice tests and improvement and enhance, the current has reached a mature stage [3], become AC servo motor control of the preferred method. Therefore, Exchange uses a linear motor with vector control drive.

Linear motor Junior's three-phase voltage (U, V, W-phase) form the coordinate system of the three primary (a, b, c axis), one of the three-phase winding phase angle difference of 120?, i.e. horizontally mutual difference 1/3-pole distance.

Reference vector transformation theory of rotating electrical machines, set two phase primary coordinate system (α-β axis lines), from the initial coordinate system into three rectangular coordinate system transformations known as Clark transform, see (1).

　

From stationary coordinate system to the rotation of the coordinate transformation called Park transforms, see (2).

On the contrary that the inverse Park.

　　

Θ is d axis and angle of the shaft.

According to the rotation of the motor Park transform theory and comparison of two motor structure. As part of different motor sport, the linear motor rotor stator equivalent to rotate, linear motor stator corresponds to the rotation of the motor rotor. So in the coordinate system rotation motor rotation rotor fixed in rotating coordinate system, with the motor rotor with synchronous rotation. In linear motor, the relativity principle by campaign, of rotor of linear motion, can be interpreted as relative to the rotor in the stator for linear motion in the opposite direction, so the "rotate coordinate system" (actually this coordinate system is a linear motion, called the linear motion coordinates) are fixed at the stator, and stator together relative to the rotor for linear motion, as shown in Figure 3. At this point, linear motor rotor for linear motion to the right, the stator, rotor relative to linear motion to the left, seated in a coordinate system is also on the stator and stator together relative to the rotor relative to the rotor to the left. Rotor internal row wave field relative to the rotor itself is moving to the left, so stop in fixed coordinate system on the stator on the observation of the synchronous motor line wave field is static. So let d axis is located on the secondary axis N pole permanent magnet, q-axis you advance d axis 90?, which is the very edge of the 1/4. Θ from linear motor movement of rotor position.

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