Difference between inverter and servo drive?

The basic concept of servo is accurate, precise and fast positioning. Frequency conversion is a necessary internal link of servo control, servo drive in the same frequency conversion (to carry out stepless speed regulation). But the servo will be current loop speed loop or position loop are closed for control, which is a big difference. In addition, the servo motor construction and ordinary motor is different, to meet the fast response and accurate positioning. Now on the market circulation of AC servo motors are mostly permanent magnet synchronous AC servo, but this motor is limited by the process, it is difficult to do a lot of power, more than a dozen KW synchronous servo price and its expensive, so that in the field application allows the use of more AC asynchronous servo, when many drivers is a high-end frequency converter, with encoder feedback closed-loop control. The so-called servo is to meet the accurate, precise, fast positioning, as long as they meet there is no servo frequency dispute.

The two **** the same point:

AC servo technology itself is to draw on and apply the technology of frequency conversion, in the DC motor servo control on the basis of the PWM mode through the frequency conversion to mimic the control of DC motors to achieve, that is to say, AC servo motors will inevitably have frequency conversion of this link: frequency conversion is the frequency 50, 60HZ AC first rectified into a DC, and then through the controllable control of the AC servo motor. DC power, and then through the various types of transistors can control the gate (IGBT, IGCT, etc.) through the carrier frequency and PWM regulation inverter for frequency adjustable waveforms similar to the sine cosine of the pulsating electric power, due to frequency adjustable, so the speed of the AC motor can be adjusted (n = 60f / p, n speed, f frequency, p pole logarithms)

Frequency inverter:

Simple frequency converter Can only adjust the speed of the AC motor, which can be open loop or closed loop depending on the control mode and frequency converter, which is the traditional sense of the V / F control mode. Now a lot of frequency conversion has been through the establishment of mathematical models, the stator magnetic field of the AC motor UVW 3-phase into the motor can control the speed and torque of the two components of the current, now most of the famous brands of frequency converter for torque control are used in this way to control the torque, the UVW each phase of the output should be added to the Hall effect of the current detection device, sampling feedback constitutes a closed-loop negative feedback current loop PID adjustment; ABB's inverter can only regulate the speed of the motor, which can be open loop or closed loop depending on the control mode and inverter, this is the traditional sense of V/F control. PID regulation; ABB's inverter and such a way to propose a different direct torque control technology, please refer to the relevant information. This can control both the speed of the motor can also control the motor torque, and speed control accuracy is better than v/f control, encoder feedback can be added or not, plus when the control accuracy and response characteristics are much better.

Servo:

Drive: servo drive in the development of inverter technology under the premise of the drive internal current loop, speed loop and position loop (inverter does not have the ring) are more accurate than the general frequency control technology and algorithmic operations, in function than the traditional inverter is also a lot more powerful, the main point of the position can be accurately controlled. The main point can be precise position control. Through the upper controller to send a pulse sequence to control the speed and position (of course, there are some servo internal integrated control unit or through the bus communication directly to the position and speed and other parameters set in the drive), the drive's internal algorithms and faster and more accurate calculations, as well as the performance of the electronic devices to make it better than the frequency converter. Ltd., need to contact at any time!