What Difference between ac servo driver and VFD
VFD:
Simple VFD can only adjust the speed of the AC motor, then you can be open-loop control and closed-loop depending on the drive may be, this is the V / F control mode in the traditional sense.Now many have passed frequency mathematical model. The stator field UVW three-phase AC motor is converted to control the motor speed and torque of the two components of the current. Torque control can be performed most famous brands are now using this drive torque control mode. UVW Output to Jia Moer effect of each phase current detection device. PID closed loop feedback to adjust after sampling a current negative feedback loop. ABB inverter also proposed different ways and this direct torque control technology. This can not only control the speed of the motor can also control the motor torque. And speed control accuracy is better than the v / f control. Encoder feedback can also be added or not.When added. Control accuracy and response is much better
the servo drive in the
development of inverter technology premise, inside the drive current loop,
velocity loop and position loop (The VFD is not the loop) have carried out more
precise than the general frequency control techniques and arithmetic operations
in the functional is also a lot stronger than conventional servo, the main
thing is precise position control.Pulse sequence sent by the host
controller to control the speed and position (of course, some internal
integration of the servo control unit or directly to the position and speed
parameters set in the drive via the bus communication mode), drive internal algorithm
and faster more accurate calculations and better performance of electronic
devices make it superior to the VFD
Servo driver:
the material, structure and process
of the servo motor is much better than the inverter-driven AC motor (AC motor
or constant torque, constant power and other types of variable frequency
motor), that is when the driver output current, voltage, frequency power is
changing rapidly, the servo motor can react according to changes in motion in
response, the response characteristics and overload resistance is much better
than the inverter-driven AC motor, the motor aspect is a serious difference
between the two fundamentally different properties . That is not the output
frequency can not change so fast power signal, but the motor itself is not
reaction, when the frequency of the internal algorithm is set to protect the
motor overload to do the appropriate settings. Of course, even without setting
the inverter output capacity is still limited, some of the excellent
performance of the drive can directly drive servo motor!
The VFD can work without encoder, servo
must have an encoder for electronic commutation, AC servo technology itself is
the draw and the application of frequency conversion technology, on the basis
of servo-controlled DC motor imitate DC motor through the frequency of the PWM
method control method to achieve, that is to say AC servo motor must have this
part of the frequency: the frequency is the frequency of the alternating
current is rectified into DC 50,60HZ the first, and then through the gate to
control the types of transistors (IGBT, IGCT, etc.) by adjusting the carrier
frequency and the PWM inverter frequency pulsating electrical adjustable
waveform similar to the sine and cosine, since the frequency is adjustable, so
adjustable speed AC motors on the (n = 60f / 2p, n speed, f frequency, p number
of pole pairs).
Currently, industrial applications, speed control and torque control of
the situation in general is not very high frequency converter, the strict
requirements of the position control can only be used in case of AC servo drive
to achieve, there is the servo response speed far greater than the frequency,
some of accuracy and response speed requirements of the occasion is also useful
for AC servo drive control, that is, use VFD control motion of the occasion can
almost replace AC servo drive
One of the supporting technology AC servo drive as a modern industrial
automation and motion control, because of its high-speed control precision,
wide speed range, high efficiency and dynamic characteristics, widely used in
machine tools, printing equipment, packaging equipment, textile equipment,
rubber and plastics new energy equipment, semiconductor, wind / solar and
robotics, automated production lines and other fields.
Motor:
An important difference between the
servo and inverter
Servo drives and drive contest