Yaskawa 4.4KW Servopack Industrial Servo Drives 0-230v-ac 3ph 3.89hp SGDB-30ADG-P

 

 

 

PWM drive technology is still considered new and is continuously being refined with new power switching devices and smart 32-bit microprocessors. AC drives have always been limited to "normal torque" applications while high torque, low rpm applications have been the domain of DC drives. This has changed recently with the introduction of a new breed of PWM drive, the flux vector drive.
Flux vector drives use a method of controlling torque similar to that of DC drive systems, including wide speed control range with quick response. Flux vector drives have the same power section as all PWM drives, but use a sophisticated closed loop control from the motor to the drive's microprocessor. The motor's rotor position and speed is monitored in real time via a resolver or digital encoder to determine and control the motor's actual speed, torque, and power produced.
By controlling the inverter section in response to actual load conditions at the motor in a real time mode, superior torque control can be obtained. The personality of the motor must be programmed into or learned by the drive in order for it to run the vector control algorithms. In most
cases, special motors are required due to the torque demands expected of the motor.
The following are advantages of this new drive technology.
* Excellent control of motor speed, torque, and power.
* Quick response to changes in load, speed, and torque commands.
* Ability to provide 100% rated torque at 0 speed.
* Lower maintenance cost as compared to DC motors and drives.
As usual, there are disadvantages.
* Higher initial cost as compared to standard PWM drives.
* Requires special motor in most cases.
* Drive setup parameters are complex.
While flux vector technology offers superior performance for certain special applications, it would be considered "over-kill" for most applications well served by standard PWM drives. Solomon S. Turkel is Senior Instructor and Course Author for ATMS (Advanced Technologies Marketing and Service), Inc., Baltimore, Md.

 

 

 

 

Development in the world of electrical machines tends to be steady rather than spectacular, which means that updating the second edition has called for only modest revision of the material covering the how and
why of motors, though in most areas explanations have been extended, especially where feedback indicated that more clarity was called for.
After much weighing the pros and cons I decided to add a chapter on the equivalent circuit of the induction motor, because familiarity with the terminology of the equivalent circuit is necessary in order to engage in
serious dialogue with induction motor suppliers or experts. However those who find the circuit emphasis not to their liking can be reassured that they can skip Chapter 7 without prejudicing their ability to tackle the subsequent chapter on induction motor drives.
The power electronics area has matured since the 1993 edition of the book, but although voltage and current ratings of individual switching devices continue to improve, and there is greater integration of drive
electronics and power devices, there has been no strategic shift that would call for a radical revision of the material in the second edition.
The majority of drive converters now use IGBT or MOSFET devices, but the old-fashioned bipolar transistor symbol has been retained in most of the diagrams because it has the virtue of showing the
direction of current flow, and is therefore helpful in understanding circuit operation.
The style of the book reflects my own preference for an informal approach, in which the difficulty of coming to grips with new ideas is not disguised. Deciding on the level at which to pitch the material was originally a headache, but experience suggested that a mainly descriptive approach with physical explanations would be most appropriate, with
mathematics kept to a minimum to assist digestion. The most important concepts (such as the inherent e.m.f. feedback in motors, or the need for a switching strategy in converters) are deliberately reiterated to reinforce understanding, but should not prove too tiresome for readers who have already ‘got the message’. I had hoped to continue without numbered headings, as this always seems to me to make the material seem lighter, but cross referencing is so cumbersome without numbering that in the end I had to give in.

 

 

 

 

 

OTHER SUPERIOR PRODUCTS