Листовка для Hitachi AN070827-1

SJ300 

 

Vector Control (V2 mode) 

 

General applications where operation at low speed or zero speed 
operation is required. 
 

Actual rotation of the motor does not match the target speed, or the 
rotation becomes unstable in the low frequency range (roughly less than 
1 Hz). Or the motor shaft creeps even with a 0 Hz speed reference. 

 

V2 (closed-loop vector) control is a speed control method based on 
calculating shaft speed from the pulse train input from the motor encoder. 
In the case of low speed, the number of input pulses decrease and it 
becomes difficult to count them within the pulse counting period. 
Therefore on SJ300 V2 mode, in the absence of encoder pulses, the 
process of motor speed estimation (speed observing) is done by using 
information like motor current, motor parameters, etc. This process is an 
estimation, and will have some errors. It sometimes results in instability 
as described above in item 4. 
 

 

Speed observer 

Speed detection when there 
are pulses from the encoder 

 

Encoder pulse 

 
 
 
 
 

 
 

Speed data for 
speed control  

Motor constants  

Motor current 

(1) Adjust motor parameters, inertia parameter (J) in particular, and try to 

obtain optimal motor performance. 

(2) Disable the speed-observing function by the following method: 

c  Set debug mode ON ([C091] = “01” and STR) using the standard 

keypad (cannot be changed via ProDrive) 

d  Configure a value of “4000” into [C193] and STR (default is “0000”) 

This change disables the speed observer function. 

e  Set debug mode OFF ([C091] = “00” and STR 

(3) This phenomenon occurs at low speed. Therefore using an encoder 

having a higher PPR (pulse per revolution) will improve performance at 
lower speeds. 

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