Current Control Config Attributes

These are the current control configuration attributes associated with a Motion Control Axis.

Current Vector Limit

Current Vector Limit value applied to the current vector limiter to provide a configurable limit to the magnitude of the current vector.

Kqp

The Kqp attribute determines the Iq Proportional Gain value that multiplies the Iq Current Error signal. This value directly determines the bandwidth of the torque producing current loop. Iq Proportional Gain value that multiplies the Iq Current Error signal before applying it to the Iq decoupling summing junction as part of the torque producing current loop. In cases where the torque producing current loop is controlled by something other than the traditional PI regulator, the Torque Loop Bandwidth is used by the drive to provide single parametric control of the current loop bandwidth. If the Flux Loop Bandwidth is not supported, the drive will use the Torque Loop Bandwidth for tuning both the torque producing and flux producing current loops.

Kqi

Iq Integral Gain value that, together with Kqp, multiplies the Iq Current Error signal before applying it to the Iq Integrator Error accumulator. The reciprocal of this value, 1/Kqi, represents the integrator time constant for the torque current loop. A value of 0 for this attribute disables the integrator.

Kdp

The Kdp attribute determines the Id Proportional Gain value that multiplies the Id Current Error signal. This value directly determines the bandwidth of the flux producing current loop.

Kdi

The Kdi attribute determines the Id Integral Gain value that, together with Kdp, multiplies the Id Current Error signal before applying it to the Id Integrator Error accumulator. The reciprocal of this value, 1/Kdi, represents the integrator time constant for the flux current loop. A value of 0 for this attribute disables the integrator.

Flux Loop Bandwidth

The Flux Loop Bandwidth attribute determines the Id Proportional Gain value that multiplies the Id Current Error signal before applying it to the Iq decoupling summing junction as part of the flux producing current loop. In cases where the flux producing current loop is controlled by something other than the traditional PI regulator, the Flux Loop Bandwidth is used by the drive to provide single parametric control of the current loop bandwidth. If the Flux Loop Bandwidth is not supported, the drive shall use the Torque Loop Bandwidth for tuning both the torque producing and flux producing current loops.

Flux Integral Time Constant

The Flux Integral Time Constant value determines the response time of the flux producing current loop integrator. When used for Pole-Zero cancelation, this value is set to the electrical time constant of the motor. A value of 0 for the Flux Integral Time Constant disables the integrator.

Flux Up Control

When the motion axis is enabled, DC current is applied to an induction motor to build stator flux before transitioning to the Running state. This attribute controls how an induction motor is to be fluxed in the Starting state before transitioning to the Running state. If No Delay is selected, the axis transitions immediately to the Running state while the motor flux is building. With Manual Delay, the axis remains in the Starting state for the Flux Up Time to allow time for the motor to be fully fluxed. With Automatic Delay, the drive device determines the amount of time to delay to fully flux the motor based on motor configuration attribute data or measurements.

If this attribute is not supported in the implementation, it is recommended that the drive establish induction motor flux using alternative means before transitioning to the Running state.

Flux Up Time

The Flux Up Time attribute sets the amount of time the drive device allows to build full motor flux before transitioning to the Running state.

Feedback Commutation Aligned

This enumerated parameter is set to Controller Offset (1) when the motor mounted absolute feedback device is to be aligned with the stator windings of the PM motor according to the Commutation Offset value. In some cases, the Commutation Offset can be preset to a value established by factory alignment of the motor feedback device relative to the motor stator windings.

A setting of Not Aligned (0) indicates that the motor is not aligned, and that the Commutation Offset value is not valid. If the Commutation Offset is not valid, it cannot be used by the drive to determine the commutation angle. Any attempt to enable the drive with an invalid commutation angle will result in a Start Inhibit condition.

Alignment can be achieved using a Commutation Test that measures and sets the Commutation Offset for the motor or by direct user entry. If this attribute is set to Motor Offset (2), the drive derives the commutation offset directly from the motor. If set to Self-Sense (3), the drive automatically measures the commutation offset when it transitions to the Starting state for the first time after a power cycle. This generally applies to a PM motor equipped with a simple incremental feedback device.

Commutation Offset

The Commutation Offset attribute specifies the commutation offset of the PM motor mounted feedback device in units of electrical degrees. This attribute specifies the offset from a commutation reference position defined by applying DC current into the A terminal and out of the shorted B and C terminals of the motor and allowing the rotor to move to its magnetic null position relative to the stator. On an absolute encoder or resolver, the offset is the difference from the device’s zero absolute position and the commutation reference position. On an incremental encoder or Hall sensor with UVW signals, the offset is the difference between the position corresponding to a transition of the commutation device’s W (S3) channel with the U (S1) channel high and the V (S2) channel low, and the commutation reference position. The commutation offset is only applicable to the motor mounted Feedback 1 device.

When the optional Commutation Alignment attribute is supported and set to Controller Offset, the drive shall apply the Commutation Offset value from the controller to determine the electrical angle of the motor. In this case, a valid Commutation Offset value must be established by the controller. In the unusual case where the commutation offset is also stored in the motor and differs significantly from the Commutation Offset value from the controller, the drive shall transition to the Start Inhibited state.

If the Commutation Alignment attribute is not set to Controller Offset, the Commutation Offset value from the controller is ignored by the drive and the drive must determine its internal commutation offset value by other means. Without a valid commutation offset, the drive shall be Start Inhibited.

Commutation Self-Sensing Current

When a PM motor feedback drive device is an incremental encoder without UVW tracks for commutation, a Self-Sensing algorithm is run during the Starting state that determines the Commutation Offset to apply to the position feedback. This algorithm applies a current to the motor stator to orient the rotor to establish the motor commutation phasing.

Commutation Polarity

When a PM motor is using UVW signals for commutation startup, it is critical that the UVW phases of the commutation device follow the phasing of the motor. Normal polarity implies UVW phasing according to factory specification when the commutation device is moving in the factory defined positive direction. Inverted polarity effectively switches the UVW phasing to UWV thus reversing the directional sense of the commutation device. If it is determined through a Commutation Test that the phasing of the motor and the phasing of the commutation device have opposite polarity, this attribute can be used to compensate for the mismatch.

Commutation Offset Compensation

This value specifies the change in the Commutation Offset value in units of electrical degrees as a linear function of current. When the Iq current is +100% of rated continuous current, the Commutation Offset value is decreased by the value of this attribute. When the Iq current is -100%, the Commutation Offset is increased by the value of the attribute. This attribute is used by the drive to compensate for changes in the optimal Commutation Offset angle that can occur as a function of motor current.

Commutation Alignment

This enumerated parameter is set to Controller Offset (1) when the motor mounted absolute feedback device is to be aligned with the stator windings of the PM motor according to the Commutation Offset value. In some cases, the Commutation Offset can be preset to a value established by factory alignment of the motor feedback device relative to the motor stator windings. A setting of Not Aligned (0) indicates that the motor is not aligned, and that the Commutation Offset value is not valid. If the Commutation Offset is not valid, it cannot be used by the drive to determine the commutation angle. Any attempt to enable the drive with an invalid commutation angle shall result in a Start Inhibit condition. Alignment can be achieved via a Commutation Test that measures and sets the Commutation Offset for the motor or by direct user entry. If this attribute is set to Motor Offset (2), the drive derives the commutation offset directly from the motor. If set to Self-Sense (3), the drive automatically measures the commutation offset when it transitions to the Starting state for the first time after a power cycle. This generally applies to a PM motor equipped with a simple incremental feedback device.

The Default Commutation Alignment value used for the Feedback Commutation Aligned and Commutation Alignment attributes depends on the associated Feedback Type and whether the motor commutation device is Factory Aligned. When the Motor Data Source is from Datasheet, it is assumed that the motor is not Factory Aligned. When the Motor Data Source is from Database, the motor data in the database indicates if the motor is Factory Aligned.

The following table correlates the default commutation alignment with the valid commutation alignment selections.