Closed Loop Modality

Closed Loop Modality is working if the bit Drive_Working_Settings.Motor Feedback_Check = 1.

In this modality, the stepper motor works using control loops and the drive supply only the current required at the motor shaft. The motor can be controlled in position, velocity, and torque loops.

For this modality it’s necessary to use a stepper motor with incremental encoder feedback installed on the rear shaft. It is also necessary to set other parameters, such as the encoder resolution and tuning of the GAIN objects that are dependent on shaft loading.

In Closed Loop Modality, the Motor Feedback Check (enables Closed Loop modality) feature and Enable Motor Stall Detection(enables Open Loop Stall Detect) feature cannot both be active at the same time.

If you try to enable the Motor Feedback Check feature with the Enable Motor Stall Detection feature already enabled, or vice versa, the system will issue an Feedback_Error alarm (bit 5 of Error_Register object and bit 14 of Feedback_Status object are set to 1).

See Motor Stall Detection for more details about the Enable Motor Stall Detection feature.

Below is the list of Objects necessary for the configuration of the drive to work in Closed Loop.

Object name	Note
Motor_Poles	Mandatory
Motor_Step_Angle	Mandatory
Min_Current	Should be set to nominal Motor Winding Current according to the catalog specification to keep the motor energized with full torque when the closed loop is disabled. For example, at power up or when the Feedback Error Alarm occurs.
Nominal_Current	Mandatory
Min_Profile_Velocity	Mandatory
Max_Profile_Velocity	Mandatory
Profile_Velocity	Mandatory
Motor_R	Typically set to the motor catalog data for Resistance (Motor_R) and Inductance (Motor_L). If Resistance is in Ohms and Inductance is in mH, then be sure to multiply by 1000 when entering values into this parameter. Alternatively and more simply, the values can be omitted if Motor RL Detection is enabled in the Working Setting tab in the Global Parameters window. (bit Drive_Working_Settings.Motor_RL_Detection =1).
Motor_L
Motor_Start_Delay	Optional, typically set to 0. Defines a delayed start based on a set amount of time. If set to 50,000, the delay is 50,000 micro-seconds. The motor will start after a 0.5 seconds delay.
Motor_Start_Delay_Pulses	Optional, typically set to 0. Defines a delayed start based on input pulses. Ex. If set to 5, the motor will start on the 6^th pulse input.
Drive_Working_Settings	This Object allows the user to set some working features and enable Closed Loop Modality by checking the Motor Feedback Check feature.
Drive_Working_Settings_Extended	This Object allows the user to set some working features.

The following objects can be found in the Feedback Settings tab in the Global Parameters window.

Object Name	Note
Feedback_Source_PPR	Mandatory
Feedback_Calibration_Current	Mandatory
Feedback_Calibration_Speed	Mandatory. Generally a default value of 5 rpm works well
Feedback_Settings	Mandatory
Feedback_Limit_Speed	Mandatory. Default value is set to 3000 rpm
Feedback_Position_Error_Limit	Must be defined in Mode 0,1 and 2
Feedback_Iq_Min	Mandatory
Feedback_Kp	Mandatory. GAIN to tuning depending by application
Feedback_Kv	Mandatory. GAIN to tuning depending by application
Feedback_Ki	Mandatory. GAIN to tuning depending by application
Feedback_Kffw_Acc	Mandatory. In the first test, this can be left equal to 0
Feedback_Kffw_Dec	Mandatory. In the first test, this can be left equal to 0
Feedback_Kfbw_Acc	Mandatory. In the first test, this can be left equal to 0
Feedback_Kfbw_Dec	Mandatory. In the first test, this can be left equal to 0

Closed Loop Modality

Diagram of the motor’s current reference in close loop