Application of V220 Frequency Converter on Circular Knitting Machine


This Article summarizes the commissioning and application of Sunfar V220 frequency converter on circular knitting machine in a textile machine factory based in Quanzhou. With application of circular knitting machine becomes wider and wider, market of frequency converter will be larger and larger. With V220 High Performance Close-loop Low Power Vector frequency converter, intelligent control algorithm is good enough to meet requirements of fast response, stable operation and immediate shutdown for circular knitting machine.

Keywords: V350 frequency converter, circular knitting machine

I. Introduction of process used in circular knitting machine
1.1  Introduction of circular knitting machine
       Circular knitting machine (as shown in Figure 1) is a device designed to knitting cotton yarn into circular cloth, mainly used to knit various kinds of interlock fabric, T shirt fabric, various kinds of pattern fabric with holes. From perspective of structure, it can be divided into single circular knitting machine and double circular knitting machine. It is widely used in textile industry.

            Figure 1 Circular knitting machine


1.2  Process requirements
1.The frequency converter is required to be strongly environment resistant because working temperature is high, and cotton fibre is liable to block and damage radiator fan and block radiating hole.
2.Flexible jogging function is required. Multiple jog buttons are installed on the equipment and frequency converter is required to be fast responsive.
3.Three levels of speed are required. One is jogging speed, at about 6Hz. The second is normal weaving speed, at up to 70Hz and the third is slow collection speed, at about 20Hz.
4.When circular knitting machine is running, motor reversing and swing is absolutely prohibited, otherwise, needle on needle bed will bend or broken. If single phase bearing circular knitting machine is used, above situation could be neglected. If forward/reversal rotation of the system totally depends on forward/reversal rotation of motor, then, on one hand, reversal rotation is prohibited, and one the other hand, direct current brake is needed to eliminate swing.


II. Onsite requirements and commissioning option1. Onsite requirements
       Circular knitting machine imposes simple requirements on control functions of frequency converter. In general, terminal is used to control startup and stop, and frequency is given through analogy quantity or multi-stage speed. Switching to jogging or slow running should be fast. Therefore, frequency converter is required to be able to control the large low frequency torque produced at low motor frequency. In general, regarding application of circular knitting machine, V/F mode on frequency converter is enough.
2.  Commissioning option
The option we adopt is: V220 High Performance Close-loop Low Power Vector Inverter (Power: 3.7 – 5.5 Kw)


III. Commissioning parameters and instruction

3.1  Wiring diagram

3.2  Setting of commissioning parameters
  (1) F0.0=0         VF mode     
  (2)F0.1=6        External current signal of frequency input channel 
  (3)F0.4=0001     External terminal control
  (4)F0.6=0010     Effective reversing prevention
  (5)F0.10=5       Acceleration time 5s
  (6)F0.11=0.8      Deceleration time 0.8s
  (7)F0.16=6       Carrier frequency 6K
  (8)F1.1=4        Torque magnification 4
  (9)F3.0=6        Setting X1 as normal inching turning
  (10)F4.10=6      Setting jogging frequency as 6Hz
  (11)F4.21=3.5     Setting jogging acceleration time as 3.5s
  (12)F4.22=1.5     Setting jogging deceleration time as 1.5s

3.3  Instructions to commissioning
1.First jog to determine motor direction
2.Vibration at jogging and slow response needs to be solved by regulating jogging acceleration and deceleration time.
3.Low frequency torque could be improved through regulating carrier wave and torque magnification.
4.Cotton fibre blocks fan duct and fan blockage results in bad radiation of frequency converter. This is frequent because common frequency converter skips heat warning and continues to run after cotton fibre is cleared manually.


1. Instructions on V220 High Performance Close-loop Low Power Vector frequency converter, Shenzhen Sunfar Electric Technology Co., Ltd