Menu 23 − Active Input Rectifier

Mode: RFC‑A

Although these parameters are described in this guide for all drives that could have a built-in active front-end and provide 4-quadrant operation, Menu 23 only appears automatically to provide the parameters for set up and monitoring if the hardware is present in the drive.

The values of Rectifier Enable (23.001) controls when the active input rectifier is enabled and when the drive enable is active to allow the motor to be controlled.

Disabled:
The active input rectifier is never enabled. Bit 12 of Enable Conditions (06.010) is always 1 so that the drive can be enabled and control the motor while the input active rectifier is not active.

Enabled:
The active input rectifier can be enabled whether the drive is enabled or not (Rectifier Wait For Drive Enable (23.002) = 0), or it can be enabled when the drive is enabled (Rectifier Wait For Drive Enable (23.002) = 1). Bit 12 of Enable Conditions (06.010) is set to 1 when Rectifier Synchronised (23.004) = 1 so that the drive can be enabled and control a motor only when the active input rectifier is synchronised. 

Enabled Latched:
The active input rectifier can be enabled whether the drive is enabled or not (Rectifier Wait For Drive Enable (23.002) = 0), or it can be enabled when the drive is enabled (Rectifier Wait For Drive Enable (23.002) = 1). If the final drive enable excluding this control logic is 0 (e.g. the drive enable input is not active) Bit 12 of Enable Conditions (06.010) follows the state of Rectifier Synchronised (23.004), and so the drive can only be enabled if the active input rectifier is synchronised. Once the active input rectifier is synchronised and the drive is enabled and controlling a motor (i.e. the final drive enable excluding this control logic is 1) Bit 12 of Enable Conditions (06.010) is latched to 1 until the final drive enable excluding this control logic is returned to 0. This allows the drive to continue to run even though the active input rectifier is no longer synchronised. The active input rectifier will not try to resynchronise until the final drive enable excluding this control logic is returned to 0.

 To prevent the active input rectifier from being enabled when the supply voltage is too low, it cannot be enabled in any of the above modes if Under Voltage Active (10.016) = 1.

See Rectifier Enable (23.001).

See Rectifier Enable (23.001).

Once the active input rectifier has been enabled it can attempt to synchronise to the supply provided the d.c. link voltage is high enough so that the drive is not in the under-voltage state (Under Voltage Active (10.016) = 0), and supply-loss detection is not active (Supply Loss (10.015) = 0) . Whilst the active input rectifier is disabled the d.c. link voltage is used to estimate the supply voltage which is used to detect supply loss. The supply loss threshold is fixed for each voltage rating of drive as given below.

The d.c. link voltage level required to leave the under-voltage state is defined by Standard Under Voltage Threshold (06.065). The minimum for this parameter will ensure that when the system changes from the under-voltage state supply loss detection is not active. Once the active input rectifier has synchronised to the supply, Rectifier Synchronised (23.004) is set to one and the drive can be enabled to control a motor.

Whilst the active input rectifier is synchronised the supply voltage is measured directly, and if this falls below the input a.c. supply loss level the active input rectifier state is automatically changed from the synchronised state. This change of state can also occur if a supply transient occurs or the d.c. link voltage falls below the under-voltage threshold. If the the active input rectifier is no longer synchronised the drive output converter is disabled. If a supply transient causes synchronisation to be lost temporarily, the active input rectifier should automatically resynchronise and allow the drive to run normally again after the transient. If Catch A Spinning Motor (06.009) is set to one or more to enable the drive to catch a spinning motor the motor will continue to run after the temporary supply loss. 

The active input rectifier will operate within the frequency range from 40Hz to 70Hz. If the supply frequency is outside this range the rectifier becomes unsynchronised and will not successfully synchronise again until the supply frequency is once again within the allowed range. It is recommended that the supply frequency should remain between 45Hz and 65Hz.

If Adaptive d.c. Link Control (23.011) = 0, then User d.c. Link Voltage Set Point (23.010) is used as the set-point for the d.c. link voltage controller. This must always be higher than the peak of the line to line supply voltage if the drive is to operate correctly, i.e. greater than or equal to (Vllrms x √2) + 50V, where Vllrms is the r.m.s. line supply voltage. The default values can be used with most supplies giving a reasonable level of control headroom. However, with higher voltage supplies the set-point may need to be increased.

If Adaptive d.c. Link Control (23.011) = 1 the system attempts to reduce the d.c. link voltage to the minimum possible for the supply voltage and rated motor voltage. It will attempt to reduce the d.c. link voltage to (√2 x Input Voltage (23.051)) + 50V or (√2 x Rated Voltage) + 50V, whichever is highest. If Select Motor 2 Parameters (11.045) = 0, then Rated Voltage = Rated Voltage (05.009) otherwise Rated Voltage = M2 Rated Voltage (21.009). The voltage controller set-point maximum is defined by User d.c. Link Voltage Set Point (23.010). Reducing the d.c. link voltage reduces the losses in both the active input rectifier and output converter.

The actual d.c. link voltage set-point is shown in D.c. link Voltage Set-point (23.012).

See User d.c. Link Voltage Set Point (23.010).

This parameter shows the actual d.c. link voltage set-point being used. See User d.c. Link Voltage Set Point (23.010).

When the active input rectifier is enabled and has synchronised to the supply, the d.c. link voltage is at a level equal to the peak line to line voltage. The voltage controller is then enabled and attempts to raise the d.c. link voltage to the set-point defined by User d.c. Link Voltage Set Point (23.010).The voltage reference is ramped up to the required level at a rate defined by D.c. Link Voltage Controller Ramp Rate (23.013) in V/ms. The default value of 1.0V/ms ensures limited over-shoot when the d.c. link voltage reaches the required level. If a shorter synchronisation time is required, then the ramp time can be increased, however care must be taken to avoid over-voltage trips particularly if a high level is used for the d.c. link voltage set-point. If a faster ramp rate and high set-point are required it may be necessary to increase D.c. Link Voltage Controller Proportional Gain Kp (23.014) to minimise over-shoot.

The d.c. link voltage is controlled by a PI controller, which provides the reference for the real component of current at the supply terminals. The default value for D.c. Link Voltage Controller Proportional Gain Kp (23.014) is suitable provided the current controller gains (Rectifier Current Controller Kp Gain (23.043) and Rectifier Current Controller Ki Gain (23.044)) are not adjusted from their default values. If these gains need to be reduced to give stable input current control then D.c. Link Voltage Controller Proportional Gain Kp (23.014) may also need to be reduced.

If a rapid increase in drive motoring output power occurs the d.c. link voltage will fall. The d.c. link controller will attempt to hold the d.c. link voltage at the level defined by the set point but there will be a dip in the voltage depending on the level of power transient. If a rapid increase in braking output power occurs the d.c. link voltage will rise. Again the d.c. link controller will attempt to hold the d.c. link voltage at the set point, however if the rise makes the voltage exceed the over-voltage level the drive will trip. A similar rise in d.c. link voltage link voltage occurs if the drive enable is removed when operating with a motoring load because there is a delay between removing the drive enable and the input converter being disabled.

One way to reduce the transient changes in the d.c. link voltage is to increase D.c. Link Voltage Controller Proportional Gain Kp (23.014) but this may lead to instability in the input converter. See D.c. Voltage Controller Proportional Gain Kp for analysis of the d.c. link transients produced.

Even with the optimum d.c. link voltage and current controller set-up, it is possible for supply voltage distortion to cause harmonic distortion in the a.c. input currents. The active input rectifier includes an additional system to reduce imbalance, 5th harmonics and 7th harmonics currents. Input Harmonic Reduction Enable (23.016) defines the type of distortion reduction required. It should be noted that an input filter formed with passive components will absorb 5th and 7th harmonic currents if there is 5th or 7th harmonic supply voltage distortion. The input converter cannot reduce this current, but it can minimise the 5th and 7th harmonic current into the input converter itself. 

If Input Harmonic Reduction Enable (23.016) > 0 then Phase Loss (10.081) is set if the negative phase sequence voltage component measured at the input converter terminals is greater than half the positive phase sequence voltage component for more than 100ms.

The active input rectifier only operates when the input frequency is between Minimum Input Frequency (23.020) and Maximum Input Frequency (23.021). If the input frequency is outside these limits then the system will not synchronise to the supply, or if it is already synchronised and the frequency changes to outside these limits the system will become unsynchronised. To avoid unwanted loss of synchronisation the actual input frequency should remain within these limits with 5Hz margin. The frequency limits can be used to detect an uncontrolled input converter frequency if the supply is removed and the system remains active because energy is being fed into the d.c. link from the output converter.

See Maximum Input Frequency (23.021).

Synchronisation tests are carried out to measure the frequency, voltage and phase of the supply when the drive is enabled. Synchronisation is lost if the supply is removed or a signifcant transient occurs. This parameter defines the action taken if synchronisation is lost.

0: Re-synchronise
This is the default mode and the system will continuously attempt to synchronise to the supply. If an over-current condition as the result of a supply transient is detected it is reset. 

1: Delayed Trip
The system operates in the same way as "Re-synchronise" mode except that a Line Sync.100 trip is initiated after 30s if either the drive has lost synchronisation while active or if the drive has failed to synchronise to the supply after being enabled.

2: Immediate Trip
The system operates in the same way as "Re-synchronise" mode except that a Line Sync.100 trip is initiated immediately if synchronisation is lost while active, or after 30s if the drive has failed to synchronise to the supply after being enabled.

This is the instantaneous input current scaled so that it represents the r.m.s. phase current in amps under steady state conditions.

Rectifier Current Controller Kp Gain (23.043) and Rectifier Current Controller Ki Gain (23.044) are the proportional and integral gains for the active input converter current controllers. In most applications the default gains can be used, but under certain supply conditions it is necessary to reduce Rectifier Current Controller Kp Gain (23.043) to prevent instability. 

See Rectifier Current Controller Kp Gain (23.043).

The Input Frequency (23.050) is the measured supply frequency. If the frequency shown is positive it indicates that the supply phase sequence is U-V-W. If it is negative it indicates that the supply phase sequence is W-V-U.

The Input Voltage (23.051) is the r.m.s. line to line voltage at the a.c. input terminals.

Input Reactive Power (23.053) shows the VAR's that flow from the supply. When Input Reactive Power (23.053) is positive the phase current flowing from the supply to the drive contains a component that lags the respective phase voltage, and so the regen system appears like an inductance connected to the supply and imports VARs. When Input Reactive Power (23.053) is negative the phase current flowing from the supply contains a component which leads the respective phase voltage, and so the regen system appears like a capacitance connected to the supply and exports VARs.

The active input rectifier control system can initiate a sub-set of the trips defined by Trip 0 (10.020). If any of the trips given in the table below are initiated by the active input rectifier, then the drive will produce the trip shown. If the active input rectifier initiates any other trip then an Active Rectifier trip is initiated with a sub-trip number that is the value of Trip 0 (10.020) related to the reason for the trip. It is unlikely that the active input rectifier will produce any trips other than those in the table unless a hardware problem occurs, and so an Active Rectifier trip is unlikely. A trip caused by the active input rectifier may result in an Over Volts trip which could mask the original reason for the trip, and so the number of the last trip to be initiated by the input converter since power-up in given in Rectifier Trip (23.100). The reason corresponding to the trip number is given in the description of Trip 0 (10.020).

This parameter is used to select a temperature related to the active input rectifier, as given in the table below, to be displayed in Rectifier Monitored Temperature (23.102). If any other value is selected or there is no thermistor at the defined location Rectifier Monitored Temperature (23.102) shows 0^oC.

See Rectifier Temperature Monitor Select (23.101).

Percentage Of Rectifier Thermal Trip Level (23.103) indicates how close a measured temperature in the active input rectifier is to tripping the drive by showing the percentage level of the measured temperature that is closest to tripping the drive. The corresponding location is shown in Rectifier Temperature Nearest To Trip Level (23.104). The percentage to trip level is given as  (Temperature - Base Temperature) / (Trip temperature - Base Temperature) x 100%, where is most cases the base temperature is 40^oC. The following actions relate to the level of this parameter.

This parameter shows the location of the measured temperature that is closest to tripping the drive as given in the table below. If the temperature reaches 100% of the trip level the drive is tripped with the trip and sub-trip also given in the table. 

This is the firmware version for the active input rectifier control board.

This is the firmware version of the processor in the power system related to the active input rectifier. See

This parameter gives the minimum d.c. link voltage that will be used for adaptive d.c. link voltage control based on the rated motor voltage, but excluding the effect of the d.c. link voltage level.

Shows the fan speed required by the input converter. If this is higher than the fan speed defined by the drive thermal model then it defines the fan speed as shown in Cooling Fan Speed (06.046).