# Menu 4 − Current Control

Mode: Regeneration

The system can have a heavy duty rating intended for applications where high overload current may be required under transient conditions, or it can have a normal duty rating where a lower level of overload current is required, or it can have a no-overload rating. The duty rating is selected automatically by the drive based on the setting of Rated Current (05.007). See Maximum Heavy Duty Rating (11.032) for more details. The different duty ratings modify the inductor protection characteristic (see Inductor Thermal Time Constant (04.015)), and also change the maximum settings for the current limits. In a drive that contains multiple power modules Full Scale Current Kc (11.061) is the full scale current of an individual module multiplied by the number of modules. Maximum Heavy Duty Rating (11.032) and Maximum Rated Current (11.060) are the value for an individual module multiplied by the number of modules.

Separate current control is provided for the active and reactive currents which are defined in Menu 3 for grid-connected mode or Menu 1 for other grid modes. Alternatively the active current reference can be defined with Active Current Reference (04.009). Current limits are applied to the active current reference. For more details of the current limit system and the calculation of the variable maximum that limits the current limit user parameter (VM_MOTOR1_CURRENT_LIMIT) see the "Drive Limits" document included in this parameter reference guide.

Parameter | 04.001 Current Magnitude
--- | ---
Short description | Shows the instantaneous drive output current
Mode | Regeneration
Minimum | −VM_DRIVE_CURRENT_UNIPOLAR | Maximum | VM_DRIVE_CURRENT_UNIPOLAR
Default |  | Units | A
Type | 32 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 3
Coding | RO, FI, VM, ND, NC, PT

Instantaneous level of fundamental current at the converter terminals in r.m.s. Amps.

Parameter | 04.002 Active Current
--- | ---
Short description | Shows the instantaneous level of active current
Mode | Regeneration
Minimum | −VM_DRIVE_CURRENT | Maximum | VM_DRIVE_CURRENT
Default |  | Units | A
Type | 32 Bit Volatile | Update Rate | 250µs write
Display Format | Standard | Decimal Places | 3
Coding | RO, FI, VM, ND, NC, PT

Instantaneous level of fundamental active current at the converter terminals in r.m.s. amps. See Regen Sub-mode (01.003) for the polarity of this parameter.

Parameter | 04.004 Final Active Current Reference
--- | ---
Short description | Shows the final current reference after the current limits
Mode | Regeneration
Minimum | −VM_TORQUE_CURRENT | Maximum | VM_TORQUE_CURRENT
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 250µs write
Display Format | Standard | Decimal Places | 1
Coding | RO, FI, VM, ND, NC, PT

The Final Active Current Reference (04.004) is the final active current reference with the current limits applied. See Regen Sub-mode (01.003) for the polarity of this parameter.

Parameter | 04.005 Power From Supply Current Limit
--- | ---
Short description | Defines the current limit used when power is being taken from the supply
Mode | Regeneration
Minimum | −VM_MOTOR1_CURRENT_LIMIT | Maximum | VM_MOTOR1_CURRENT_LIMIT
Default | Default Regen Current Limit | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

The Power From Supply Current Limit (04.005) limits the active current when power is being taken from the supply. The Power To Supply Current Limit (04.006) limits the active current when power is being fed back into the supply. If the Symmetrical Current Limit (04.007) is below the Power From Supply Current Limit (04.005) then it is used instead of the Power From Supply Current Limit (04.005). If the Symmetrical Current Limit (04.007) is below the Power To Supply Current Limit (04.006) then it is used instead of the Power To Supply Current Limit (04.006). It should be noted that if the current limits become active it is no longer possible for the d.c. bus voltage to be controlled.

The maximum possible current limit (VM_MOTOR1_CURRENT_LIMIT [MAX]) varies between drive sizes with default parameters loaded. For some drive sizes the default value may be reduced below the value given by the parameter range limiting.

Parameter | 04.006 Power To Supply Current Limit
--- | ---
Short description | Defines the current limit used when power is being fed back into the supply
Mode | Regeneration
Minimum | −VM_MOTOR1_CURRENT_LIMIT | Maximum | VM_MOTOR1_CURRENT_LIMIT
Default | Default Regen Current Limit | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

See Power From Supply Current Limit (04.005).

Parameter | 04.007 Symmetrical Current Limit
--- | ---
Short description | Defines the symmetrical current limit.
Mode | Regeneration
Minimum | −VM_MOTOR1_CURRENT_LIMIT | Maximum | VM_MOTOR1_CURRENT_LIMIT
Default | Default Regen Current Limit | Units | %
Type | 16 Bit User Save | Update Rate | 4ms Read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

See Power From Supply Current Limit (04.005).

Parameter | 04.008 Reactive Current Reference
--- | ---
Short description | Defines the reactive current reference
Mode | Regeneration
Minimum | −VM_REGEN_REACTIVE | Maximum | VM_REGEN_REACTIVE
Default | 0.0 | Units | %
Type | 16 Bit User Save | Update Rate | 250µs read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

This parameter only has any effect in grid-connected mode. If Reactive Power Input Mode (03.019) is set to zero, then this parameter gives the reactive current set-point, so that the system can be made to produce or consume reactive power. This parameter defines the level of reactive current as a percentage of the Rated Current (05.007). See Regen Sub-mode (01.003) for the polarity of this parameter.

The variable maximum applied to Reactive Current Reference (04.008) is used to ensure that the total current does not exceed the maximum allowed. If the current limits are at their maximum values then no reactive current is allowed and VM_REGEN_REACTIVE_REFERENCE[MIN] = 0 and VM_REGEN_REACTIVE_REFERENCE[MAX] = 0. As the Final Current Limit (04.018) is reduced then more reactive current is allowed.

Parameter | 04.009 Active Current Reference
--- | ---
Short description | Defines the active current reference
Mode | Regeneration
Minimum | −VM_USER_CURRENT | Maximum | VM_USER_CURRENT
Default | 0.0 | Units | %
Type | 16 Bit User Save | Update Rate | 250µs read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

This parameter only has any effect in grid-connected mode. If Active Current Reference Selector (04.010) = 1, then this parameter gives the active current set-point, otherwise the active current is controlled by the d.c. bus voltage controller or power reference. See Regen Sub-mode (01.003) for the polarity of this parameter. If this parameter is used to control the active current directly an external source must be used to defined the d.c. bus level.

Parameter | 04.010 Active Current Reference Selector
--- | ---
Short description | Set to enable the user active current reference
Mode | Regeneration
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See Active Current Reference (04.009).

Parameter | 04.013 Current Controller Kp Gain
--- | ---
Short description | Defines the current loop controller proportional gain
Mode | Regeneration
Minimum | 0 | Maximum | 30000
Default | 50 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

Current Controller Kp Gain (04.013) and Current Controller Ki Gain (04.014) are the proportional and integral gains of the current controllers. In most applications the default gains can be used, but under certain supply conditions it is necessary to reduce the Current Controller Kp Gain (04.013) to prevent instability.

Parameter | 04.014 Current Controller Ki Gain
--- | ---
Short description | Defines the current loop controller integral gain
Mode | Regeneration
Minimum | 0 | Maximum | 30000
Default | 500 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See Current Controller Kp Gain (04.013).

Parameter | 04.015 Inductor Thermal Time Constant
--- | ---
Short description | Set to the inductor thermal time constant
Mode | Regeneration
Minimum | 1.0 | Maximum | 3000.0
Default | 89.0 | Units | s
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW

A single time constant thermal model is provided that can be used to estimate the temperature of the regen inductors connected between the regen drive and the supply. The input to the model is the Current Magnitude (04.001). The Inductor Protection Accumulator (04.019) is given by the following equation.

T = 100.0% x [I / (K1 x IRated)]2 x (1 − e-t/τ)

where:
T = Inductor Protection Accumulator (04.019)
I = Current Magnitude (04.001)
IRated = Rated Current (05.007)
τ = Inductor Thermal Time Constant (04.015)

If Rated Current (05.007) ≤ Maximum Heavy Duty Rating (11.032) then K1 = 1.05, otherwise K1 = 1.01.

Inductor Protection Accumulator Reset
The initial value in the Inductor Protection Accumulator (04.019) at power-up is defined by Inductor Protection Accumulator Power-up Value (04.036) as given in the table below.

Inductor Protection Accumulator Power-up Value (04.036) | Inductor Protection Accumulator (04.019) at power-up
Power Down | The value is saved at power-down and is used as the initial value at power-up.
Zero | The value is set to zero.
Real Time | If a real-time clock is present and if Date/Time Selector (06.019) is set up to select the real-time clock then the value saved at power-down is modified to include the effect of the inductor thermal protection time constants over the time between power-down and power-up. This modified value is then used as the initial value at power-up. If no real time clock is present and this option is selected, then the value saved at power-down is used as the initial value.

The Inductor Protection Accumulator (04.019) is reset under the following conditions:

1. Inductor Thermal Time Constant (04.015) is set to 0.0. Note that this is not possible in the standard product as the minimum parameter value is 1.0.
2. Rated Current (05.007) is modified.

Inductor Protection Accumulator Warning
If [I / (K1 x IRated)]2 > 1.0 then eventually the Inductor Protection Accumulator (04.019) will reach 100% causing the regen drive to trip. If this is the case and Inductor Protection Accumulator (04.019) > 75.0% then [Ind Overload] alarm indication is given and Inductor Overload Alarm (10.017) is set to one.

Parameter | 04.017 Reactive Current
--- | ---
Short description | Shows the instantaneous level of reactive current
Mode | Regeneration
Minimum | −VM_DRIVE_CURRENT | Maximum | VM_DRIVE_CURRENT
Default |  | Units | A
Type | 32 Bit Volatile | Update Rate | 250µs write
Display Format | Standard | Decimal Places | 3
Coding | RO, FI, VM, ND, NC, PT

Instantaneous level of fundamental reactive current at the converter terminals in r.m.s. amps. See Regen Sub-mode (01.003) for the polarity of this parameter.

Parameter | 04.018 Final Current Limit
--- | ---
Short description | Shows the final current limit that is applied to the active current
Mode | Regeneration
Minimum | −VM_TORQUE_CURRENT | Maximum | VM_TORQUE_CURRENT
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 1
Coding | RO, VM, ND, NC, PT

Final Current Limit (04.018) is the current limit level that is applied to the active current.

Parameter | 04.019 Inductor Protection Accumulator
--- | ---
Short description | Shows the level of the inductor protection accumulator
Mode | Regeneration
Minimum | 0.0 | Maximum | 100.0
Default |  | Units | %
Type | 16 Bit Power Down Save | Update Rate | Background write
Display Format | Standard | Decimal Places | 1
Coding | RO, ND, NC, PT

See Inductor Thermal Time Constant (04.015).

Parameter | 04.020 Percentage Load
--- | ---
Short description | Shows the level of active current as a percentage of rated current
Mode | Regeneration
Minimum | −VM_USER_CURRENT | Maximum | VM_USER_CURRENT
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | Background write
Display Format | Standard | Decimal Places | 1
Coding | RO, FI, VM, ND, NC, PT

Percentage Load (04.020) gives the Active Current (04.002) as a percentage of the Rated Current (05.007). See Regen Sub-mode (01.003) for the polarity of this parameter.

Parameter | 04.021 Current Feedback Filter Disable
--- | ---
Short description | Disables the 4ms filter applied to current feedback parameters.
Mode | Regeneration
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background Read
Display Format | Standard | Decimal Places | 0
Coding | RW

If Current Feedback Filter Disable (04.021) = 0 a 4ms filter is applied to the current feedback given in Active Current (04.002) and Reactive Current (04.017), otherwise the filter is disabled and the parameters are based on the current components sampled every 250us.

Parameter | 04.024 User Current Maximum Scaling
--- | ---
Short description | Defines the maximum for the active current reference and percentage load parameters
Mode | Regeneration
Minimum | −VM_TORQUE_CURRENT_UNIPOLAR | Maximum | VM_TORQUE_CURRENT_UNIPOLAR
Default | 175.0 | Units | %
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

User Current Maximum Scaling (04.024) defines the variable maximum/minimums VM_USER_CURRENT and VM_USER_CURRENT_HIGH_RES which are applied to Percentage Load (04.020) and Active Current Reference (04.009). This is useful when routing these parameters to an analog output or when using them as the destination for an analog input, as it allows the full scale value to be defined by the user.

The maximum value (VM_TORQUE_CURRENT_UNIPOLAR [MAX]) varies between drive sizes with default parameters loaded. For some drive sizes the default value may be reduced below the value given by the parameter range limiting.

Parameter | 04.036 Inductor Protection Accumulator Power-up Value
--- | ---
Short description | Defines the initial power-up value of the inductor protection accumulator
Mode | Regeneration
Minimum | 0 | Maximum | 2
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Background write
Display Format | Standard | Decimal Places | 0
Coding | RW, TE

Value | Text
0 | Power down
1 | Zero
2 | Real time

See Inductor Thermal Time Constant (04.015).

Parameter | 04.039 Final Reactive Current Limit
--- | ---
Short description | Amount of possible reactive current.
Mode | Regeneration
Minimum | -200.0 | Maximum | 200.0
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms Write
Display Format | Standard | Decimal Places | 1
Coding | RO, ND, NC, PT

Shows the amount of possible reactive current as defined by the VM_REGEN_REACTIVE_REFERENCE variable maximum. The maximum reactive current is allowed is defined by the level set for the active current limit. See Reactive Current Reference (04.008) for more details.

Parameter | 04.040 Final Reactive Current Reference
--- | ---
Short description | Shows the final reactive current reference
Mode | Regeneration
Minimum | -200.0 | Maximum | 200.0
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 250µs write
Display Format | Standard | Decimal Places | 1
Coding | RO, FI, ND, NC, PT

Final Reactive Current Reference (04.040) gives the reactive current reference including current that is injected by the island detection system. See Regen Sub-mode (01.003) for the polarity of this parameter.