Motor Drives

• The importance of Motor Drives

  Modern machines are increasingly embedded in integrated systems with power electronic converters and control electronics to form what is termed a motor drive. Recent developments in microprocessor technology have enabled advanced motor drive control strategies to be implemented. These new control strategies together with other developments in power switching devices, converter circuits, motor design and transducers have considerably enhanced the efficiency, quality, reliability and the performance of motor drives. Motor drives are becoming a main part of whole system, and the motion control technology is developing rapidly with motor drive.

   

• Design Induction Motor for Vector Drive

  Conventional induction motor design is commonly aimed at the standard sinusoidal ac application. Recent developments in "vector control" provide the opportunity for rapid response servo drives. However, the standard motors do not provide the best performance as a servo machine. This research aims to design induction motor with characteristics more directly in tune with the vector drive "machine model" and with superior servo motor performance.

  

   

• Implementation of MC68HC16 based Vector Controller for AC Induction Motors

  High performance induction motor drives using the technique of vector control are now commercially available as a direct substitution for the DC drive. The increasing popularity of this drive results from the low cost and durability of the motor itself. My controller employs MC68HC16 chip with FPGA logic and yields speed resolution up to 0.1 RPM even at 1024PPR encoder. The possible control range of speed is between 1 to 3600 RPM. Motion control algorithm and RS232C serial communication function are also programmed to monitor and control with PC.

  

   

• Estimation Method of Rotor Temperature in Vector Controlled Induction Motor

  To carry out vector control with keeping good performance, we should know all the parameter values of induction motor. Among them, a rotor time constant which is a function of temperature is quite important to succeed vector control. A rotor resistance has a great temperature coefficient, so it is a main changing factor of rotor time constant. Generally, a temperature sensor is installed on stator winding in order to protect motor from overheating and measuring of rotor temperature is difficult at running state. This research proposes the real time estimator of rotor temperature that uses stator temperature and torque current of vector controller. The mathematical model of thermal behavior of induction motor is made up of the thermal capacitance of rotor and the resistance of air-gap. The rotor loss as a function of torque current in vector controller is defined.

   

     CNC Controllers 

• RS232C linked CNC Motion System for CNC Milling

  1) This is a PC-based solution controlling CNC milling machines. The CNC can simultaneously coordinate the motions of up to 4 axes(X, Y, Z and C) of a machine to achieve a desired 3-dimensional profile. The desired profile is defined in a program written in an industry-standard language. PC program is compiled into motion commands which are fed to Vector drives by means of RS232C in real time base. It also has a full-screen text editor and a graphical simulation module (to perform dry-runs of the execution). The system is made up of Vector drives and PC. There is no need to install add-on specific motion cards.

  

   2) This system is being improved with STEP motors.  Actually, The induction motor shown above is too big to install an milling machine. The microprocessor AT89C52 is employed for motor drives and pendant. My milling machine is retrofitted for the CNC system.

   

• Step motor Drives for SuperCam  

  The SuperCam CAD/CAM program is a graphical three axis universal operating system for XYZ mechanisms, using stepper motors to create linear motion. It is a direct approach to running three axis machines. The drawing objects are converted directly into "direction" and "step" pulse steams or signals that directly control the "phase" states for three electronic stepper motor drivers, attached to the parallel printer port of a DOS compatible desktop PC. It also can be used to create CNC g-code files.  I made a motor drive for this program which has 3 axes step motor controllers, DB-25 connector for printer port and connector for limit switches. It's very small. It can drive up to 1.5A (good for NEMA#23 size). If you need the board, let me know.

  www.pwm.pe.kr