Big round machine application-2015-03-20

一、the situation

Commissioning machines and equipment: knitting circular machine

V&T Inverter Model: V5−H−4T−5.5G/7.5L

二、the industry introduction

Knitting large circular machines are now widely used in the textile industry. In this industry of big circular machine, the market potential of frequency drive was still quite large.

三、the system program and system wiring

At present, Dayuan has a relatively mature control system, which was basically controlled by single-chip microcomputer or PLC+ human-machine interface. Its function requirements for the inverter are very simple, only the terminal control starts and stops, the analog given frequency or the multi-segment frequency was given.

In terms of control performance, the inverter was required to provide a large low-frequency torque, because the load was heavy when weaving, and the jog response was required to be rapid. Here, our inverter adopts the speed sensorless vector control mode to improve the motor's steady speed accuracy and low frequency torque output.

The large circular machine requires the motor to absolutely prohibit reverse rotation and rotation, otherwwase the needle of the needle bed will be bent or even broken. For large circular machine systems with one-way bearings, this effect can be ignored. If the system was completely reversed depending on the motor control, then the DC braking function should be properly used.

In terms of speed control, the system was required to operate at least at three speeds. First, the jog operation, the frequency was about 5−6Hz; the second was the normal high-speed weaving operation, the highest frequency can reach 80Hz; the third was the low-speed collection operation, when the cloth was woven to a certain length, it needs to be slowly collected at a low speed of about 20Hz. cloth. For multi-speed control, there are basically two control schemes. One solution was to use the analog given frequency, whether it was jog or high speed and low speed operation, the analog signal and the running command are given by the control system; the other scheme was to use the multi-stage frequency given by the inverter, the control system The multi-segment frequency switching signal was given, and the jog was also provided by the inverter's own jog function. The set frequency at high-speed weaving was given by the analog quantity or the inverter open-loop frequency number.

Control terminal wiring method:

四、the Commissioning steps

◆ According to the motor nameplate, set the motor parameters and perform the rotation self-learning of the parameters.

P0.03=4; P0.04=1; P0.06=1; P5.00=2; P0.08=5; P0.09=0.8; P0.11=65; P0.13=65, P0. 10=0.5; P3.03=0.2; Pd.09=50; Pd.14=0.1; PA.09=1; Pd.01=0.8; Pd.03=1; Pd.05=50; Pd.17= 10; Pd. 33 = 0.

P0.11 and P0.13 65Hz, the maximum frequency can be gradually increased to 80Hz after the large circular machine was worn for a period of time.

The settings of P3.03, Pd.09 and Pd.14 are to improve the dynamic performance of the start and stop of the round machine. The large circular machine requires fast response at start-up, low-frequency and large torque output, and smooth and soft when stopping, to protect the equipment needle bed. Therefore, the starting frequency was reduced to 0.2 Hz, the vector control pre-excitation time was reduced to 0.1 S, and the S-segment curve time was added to 0.5 to ensure the smoothness of the frequency adjustment at the start and stop time, and then the braking torque was reduced by 50%. After repeated experiments, the parameters of this group achieved good control performance.

The function codes Pd.01, Pd.03 and Pd.05 are used to improve the vibration problem of the large circular machine at high speed. The ASR switching frequency was increased and the speed loop proportional gain was reduced to reduce the torque of the inverter at high speed. Output, reducing motor jitter, thereby improving the violent vibration of the entire machine at high speeds.

Pd.33 was to reduce the output current during balanced power operation.

五、the solution to the problem of on-site Commissioning

◆ Should the control mode be vector control 1 or vector control 2?

The large circular machine has half of the control performance requirements for the inverter. The vector control 1 should meet the requirements. The V&T speed sensorless vector control inverter can better improve the low frequency and large torque output of the large circular machine. Stable speed performance, especially low frequency and large torque output characterwastics, works well.

However, during the on-site Commissioning process, it was found that the rotation phenomenon can be eliminated or improved after the DC braking function was started in the vector control 2 mode. Therefore, the large circular machine for on-site Commissioning adopts the vector control 2 mode.

◆ The motor shaft has a slight rotation at the start and stop moment

For machines equipped with one-way bearings in the large circular machine system, the effect of this slight rotation can be completely ignored. However, some large circular machines do not prohibit reverse rotation on the machine. When it was completely controlled by the motor, this problem needs to be taken seriously. A slight reversal may damage the dial.

Here, it was necessary to set the DC braking parameter of the stop to ensure that the inertia on the motor shaft was completely stopped by DC braking during the stop, and also ensure that the angle of the motor shaft was conswastent with the angle of the PWM wave when starting, and the starting was solved. The problem of instantaneous motor shaft rotation.

P3.05=2, P3.06=2, P3.07=120, P3.08=0.5, 120% inverter rated current during shutdown, DC braking at 0.5Hz, continuous braking time 2s.

After setting the DC braking function, the problem of the motor shaft rotation at the start and stop can be basically reduced to a minimum, and the final effect was better than the actual effect of other foreign brand inverters.

六、summary:

At present, V&T vector control type V5−H frequency drive was obviously more than enough in terms of functional performance on the large circular machine. The competitive price/performance advantage was obvious.

In addition, V&T can also help customers reduce costs through customization. For example, the big circular machine has a complete set of mature control systems. At present, the more advanced control systems basically use touch screen + PLC control. The cost of the PLC controller was relatively high. V&T Inverter can be combined with human-machine interface such as touch screen, and utilizes 485 communication control to develop a customized control system for the large circular machine industry, namely the human-machine interface + large-circle machine industry-specific inverter, thus completely eliminating the intermediate PLC link. , can greatly reduce the cost of the circular machine system.