(2) High failure ratio.

(3) Low efficiency, the power factor is less than 0.8.

(4) The safety performance is bad.

(2) Big overload capacity.

(3) Less failure ratio, run stably.

(4) Braking unit and braking resistor should be added.

3,  Real application (Tower crane)
   3.1 system introduction

   The hoist motor in the system is 55kW/380V, the load type is constant torque, to consider its heavy duty characteristic,
   the frequency inverter should be selected two sizes higher as below:

   3.2 system diagram





 3.3 control logic

   (1) The tower crane control system provide the forward and reverse signals, while MI1 and DCM closed, the tower
         crane runs forwardly, and while MI2 and DCM closed, the tower crane runs reversely:

   (2) The  running speed of crane is controlled by ON/OFF conditions of MI3, MI4 and MI5, details as below:

MI5	MI4	MI3	Speed
OFF	OFF	OFF	Speed 0 (FD-00)
OFF	OFF	ON	Speed 1 (FD-01)
OFF	ON	OFF	Speed 2 (FD-02)
OFF	ON	ON	Speed 3 (FD-03)
ON	OFF	OFF	Speed 4 (FD-04)
ON	OFF	ON	Speed 5 (FD-05)

  (3) The inverter output a fault signal to the crane control system, while fault happen, the system will brake and stop
        immediately.

  (4) There is an output FDT1 (controlled by F8-19 and F8-20) ON/OFF signal, while the inverter  runs to the setting
        frequency, this signal will control the brake to open, to avoid the reverse run happen.

 3.4 autotuning

    For this kind of heavy duty system, it is better to use Sensorless Vector Control (SVC) mode, it will get better output
    torque performance.
    Before using SVC mode, please perform motor autotunning, do it as below steps:

   1) Set F0-02=0 (keypad), set correct value of F2-01 ~ F2-05 (based on motor nameplate);
   2) If the load can be removed from motor, please set F2-11=2 (Rotation autotuning, get better performance), if the
        load cannot be removed from motor, please set F2-11=1 (Static autotuning). The keypad will display “TUNE”.
   3) Press the RUN button, wait until the autotuning finish automatically.
   4) Change the value of F0-01=0 (Sensorless vector control)

 3.5 Parameters setting

No.	Function codes	Default	Setting value	Explanation
1	F0-01	2	0	Sensorless Vector Control
2	F0-02	0	1	External singal start / stop
3	F0-03	1	6	Multi-step speed
4	F0-17	Model depend	5s	Acceleration time (adjustable)
5	F0-18	Model depend	0.5s	Deceleration time (adjustable)
6	F3-10	150%	200%	Torque uppee limit
7	F5-00	1	1	Forward
8	F5-01	2	2	Reverse
9	F5-02	0	12	Multi-step speed termnial 1
10	F5-03	0	13	Multi-step speed termnial 2
11	F5-04	0	14	Multi-step speed termnial 3
12	F6-02	2	2	Fault output
13	F6-05	0	3	FDT1 output
14	F8-19	50.00Hz	3.00Hz	Setting FDT1 output frequency
15	FD-00	0.0%	16%	Multi-step speed 0 (adjustable)
16	FD-01	0.0%	16%	Multi-step speed 1 (adjustable)
17	FD-02	0.0%	30%	Multi-step speed 2 (adjustable)
18	FD-03	0.0%	50%	Multi-step speed 3 (adjustable)
19	FD-04	0.0%	70%	Multi-step speed 4 (adjustable)
20	FD-05	0.0%	82%	Multi-step speed 5 (adjustable)

 

3.6 Problems faced during commissioning

(1)  For KD330-09000T4, it needs connect additional braking unit and braking resistor to consume the regenerated
       energy. The parameter of  FA-04 is the braking threshold, the default value is 135%. The stand DC bus voltage is
       540V, 540*135%=729V, that means while the DC bus voltage reach to 729V, the Braking unit will start work.
       Sometimes, the fault of over voltage will happen, please reduce the value of FA-04 to avoid it.

(2)  Cause the tower working distance is too long, during down running, the inverter works at regenerated status for
       long time, so the braking resistor should be selected bigger, to get better performance. In this system, it is
       select as 4ohm, 10kW.