Menu 5 − Motor Control

Mode: Open‑Loop

The drive controls asynchronous machines in open loop control with respect to frequency and current. The open loop asynchronous control is further broken down into vector and fixed boost modes.

 


Parameter05.001  Output Frequency
Short descriptionDisplays the output frequency of the drive
ModeOpen‑Loop
Minimum−VM_SPEED_FREQ_REFMaximumVM_SPEED_FREQ_REF
Default UnitsHz
Type32 Bit VolatileUpdate Rate16ms
Display FormatStandardDecimal Places2
CodingRO, FI, VM, ND, NC, PT

The Output Frequency (05.001) is the sum of Final Demand Reference (03.001) and the motor slip compensation frequency.


Parameter05.002  Output Voltage
Short descriptionDisplays the r.m.s. line to line voltage at the a.c. terminals of the drive
ModeOpen‑Loop
Minimum−VM_AC_VOLTAGEMaximumVM_AC_VOLTAGE
Default UnitsV
Type16 Bit VolatileUpdate Rate16ms
Display FormatStandardDecimal Places0
CodingRO, FI, VM, ND, NC, PT

The Output Voltage (05.002) is the r.m.s line to line voltage at the a.c. terminals of the drive.


Parameter05.003  Output Power
Short descriptionDisplays the power flowing via the a.c. terminals of the drive
ModeOpen‑Loop
Minimum−VM_POWERMaximumVM_POWER
Default UnitskW
Type32 Bit VolatileUpdate Rate16ms
Display FormatStandardDecimal Places2
CodingRO, FI, VM, ND, NC, PT

The Output Power (05.003) is the power flowing via the a.c. terminals of the drive. The power is derived as the dot product of the output voltage and current vectors, and so this is correct even if the motor parameters are incorrect and the motor model does not align the reference frame with the flux axis of the motor. A positive value of power indicates power flowing from the drive to the motor.

The maximum power is VM_POWER[MAX] = √3 x VM_AC_VOLTAGE[MAX] x Full Scale Current Kc (11.061) / 1000


Parameter05.004  Motor Rpm
Short descriptionDisplays the Final Demand Reference in units of rpm
ModeOpen‑Loop
Minimum-33000Maximum33000
Default Unitsrpm
Type32 Bit VolatileUpdate RateBackground write
Display FormatStandardDecimal Places0
CodingRO, FI, ND, NC, PT

Motor Rpm (05.004) = 60 x Frequency / Pole pairs

where
Pole pairs = the numeric value of Number Of Motor Poles (i.e. 3 for a 6 pole motor)

The frequency used to derive the Motor Rpm (05.004) is the Final Demand Reference (03.001). The maximum and minimum values allow for a 10% over-shoot of the speed.


Parameter05.005  D.c. Bus Voltage
Short descriptionDisplays the voltage across the d.c. link of the drive
ModeOpen‑Loop
Minimum−VM_DC_VOLTAGEMaximumVM_DC_VOLTAGE
Default UnitsV
Type16 Bit VolatileUpdate Rate16ms
Display FormatStandardDecimal Places0
CodingRO, FI, VM, ND, NC, PT

D.c. Bus Voltage (05.005) gives the voltage across the d.c. link of the drive.


Parameter05.006  Motor Rated Frequency
Short descriptionSet to the rated frequency of the motor
ModeOpen‑Loop
Minimum0.00Maximum550.00
DefaultSee exceptions belowUnitsHz
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places2
CodingRW

RegionDefault Value
50Hz50.00
60Hz60.00

Motor Rated Frequency (05.006) and Motor Rated Voltage (05.009) define the frequency to voltage characteristic applied to the motor. See Open-loop Voltage Mode (05.014) for more details. Motor Rated Frequency (05.006), Motor Rated Speed (05.008) and Number Of Motor Poles (05.011) are used to calculate the rated slip of the motor for slip compensation.

Rated slip (Hz) = Motor Rated Frequency (05.006) - (Pole pairs x Motor Rated Speed (05.008) / 60)

where
Pole pairs = the numeric value of Number Of Motor Poles (05.011) (i.e. 3 for a 6 pole motor)

If slip compensation is required Motor Rated Speed (05.008) should be set to the motor nameplate value, which should give the correct compensation for a hot motor providing the nameplate value is correct. Slip compensation can be used throughout the speed range of the motor, i.e. below base speed and in the flux weakening region, to correct the motor speed to minimise the change of speed with load. Slip Compensation Gain (05.027) is provided for the user to be able to set the amount of compensation applied. At its default value of 100.0% Rated slip is applied and reducing it below 100.0% will reduce the amount of slip compensation, which may be required if some instability is experienced. Setting Slip Compensation Gain (05.027) negative causes the motor frequency to reduce as load is applied introducing speed droop, which can be used to aid load sharing with mechanically coupled motors.

Slip Compensation = Rated Slip x Torque Producing Current (04.002) / ITrated    x    Slip Compensation Gain (05.027) / 100

where   ITrated = Torque Rated Current (see Torque Producing Current (04.002) )

The amount of slip compensation applied can be limited by Slip Compensation Limit (05.033)

In Ur modes of operation the amount of slip can be increased at low output frequecies to boost torque capability at these frequencies. Also when Open-loop Voltage Mode (05.014) is set to mode 6 (Fixed Tapered) the slip can be tapered to 0 at very low frequencies to prevent creep at standstill,see Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) .

Slip compensation is disabled under the following conditions:

  1. Motor Rated Speed (05.008) = 0
  2. Motor Rated Speed (05.008) = Motor Rated Frequency (05.006) x 60 / Pole pairs, i.e. synchronous speed.
  3. Slip Compensation Gain (05.027) = 0.0%
  4. Slip Compensation Limit (05.033) = 0.00Hz

It should be noted that Motor Rated Speed (05.008) is used to calculate the rotor time constant of the motor which is then used to determine the flux build-up time at the start of the catch a spinning motor algorithm. If spinning start is required (i.e. Catch A Spinning Motor (06.009) ≥ 1) then Motor Rated Speed (05.008) should be set up correctly for the motor. If slip compensation is not required, it can be disabled by setting Slip Compensation Gain (05.027) to 0.0%.


Parameter05.007  Motor Rated Current
Short descriptionSet to the rated current rated of the motor
ModeOpen‑Loop
Minimum0.00MaximumVM_RATED_CURRENT
Default0.00UnitsA
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places2
CodingRW, VM, RA

Motor Rated Current is used as follows:

  1. To define the rated operating conditions for motor thermal protection. See Thermal Protection Mode (04.016).
  2. To define the range of the current limits.
  3. In the motor control algorithm for Open-loop and Closed Loop asynchronous modes.


Parameter05.008  Motor Rated Speed
Short descriptionSet to the rated speed of the motor
ModeOpen‑Loop
Minimum0.0Maximum33000.0
DefaultSee exceptions belowUnitsrpm
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

RegionDefault Value
50Hz1500.0
60Hz1800.0

See Motor Rated Frequency (05.006).

 


Parameter05.009  Motor Rated Voltage
Short descriptionSet to the rated voltage of the motor
ModeOpen‑Loop
Minimum0MaximumVM_AC_VOLTAGE_SET
DefaultSee exceptions belowUnitsV
Type16 Bit User SaveUpdate Rate16ms
Display FormatStandardDecimal Places0
CodingRW, VM, RA

VoltageRegionDefault Value
110VAll230
200VAll230
400V50Hz400
400V60Hz460
575VAll575
690VAll690

Motor Rated Frequency (05.006) and Motor Rated Voltage (05.009) define the frequency to voltage characteristic applied to the motor. See Open-loop Voltage Mode (05.014) for more details.


Parameter05.010  Motor Rated Power Factor
Short descriptionSet to the rated power factor of the motor. This value can be measured by the drive during a rotating autotune
ModeOpen‑Loop
Minimum0.00Maximum1.00
Default0.85Units 
Type16 Bit User SaveUpdate RateBackground read/write
Display FormatStandardDecimal Places2
CodingRW, RA

Motor Rated Power Factor (05.010) is the true power factor of the motor under rated conditions, i.e. the cosine of the angle between the motor voltage and current. If Stator Inductance (05.025) is set to a non-zero value then the stator inductance is used to calculate the rated magnetising current for the motor and the rated power factor can be calculated by the drive. Therefore if Stator Inductance (05.025) is non-zero Motor Rated Power Factor (05.010) is continuously set to the calculated value of rated power factor by the drive. If Stator Inductance (05.025) is set to zero then Motor Rated Power Factor (05.010) is used to estimate the rated magnetising current which is an approximation and not as accurate. Stator Inductance (05.025) can be measured by the drive during auto-tuning and this is the preferred option, however, if it is not possible to obtain the value for Stator Inductance (05.025) then Motor Rated Power Factor (05.010) should be set to the motor nameplate value.


Parameter05.011  Number Of Motor Poles
Short descriptionSet to the number of poles of the motor
ModeOpen‑Loop
Minimum0Maximum16
Default0UnitsPolePairs
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, BU

If Number Of Motor Poles (05.011) = 0 the number of motor poles are calculated automatically as given below.

Pole pairs = 60 x Motor Rated Frequency (05.006) / Motor Rated Speed (05.008) rounded down to the nearest integer.

If Number Of Motor Poles (05.011) > 0 the value is taken as the number of pole pairs.

When viewed with a keypad, the value of 0 is displayed as Automatic and any non 0 value is displayed is the twice the parameter value representing number of motor poles rather than pole pairs.


Parameter05.012  Auto-tune
Short descriptionDefines the auto-tune test to be performed
ModeOpen‑Loop
Minimum0Maximum2
Default0Units 
Type8 Bit VolatileUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, NC

The following describes how an auto-tune test can be initiated and normal operation can be resumed after the test:

  1. An auto-tune test cannot be initiated if the drive is tripped or the drive inverter is active, i.e. Drive Healthy (10.001) = 0 or Drive Active (10.002) = 1. The inverter can be made inactive by ensuring that the Final drive enable is inactive (see Menu 06), or the Final drive run (see Menu 06) is inactive and Hold Zero Frequency (06.008) = 0.
  2. An auto-tune test is initiated by setting Auto-tune (05.012) to a non-zero value and making the Final drive enable and the Final drive run active.
  3. All tests that move the motor will move the motor in the forward direction if Reverse Select (01.012) = 0 or the reverse direction if Reverse Select (01.012) = 1.
  4. If the auto-tune sequence is completed successfully the Final drive enable is set to the inactive state and Auto-tune (05.012) is set to zero. The Final drive enable can only be set to the active state again by removing the enable and reapplying it. The enable can be removed by setting Drive Enable (06.015) = 0, or by setting bit 0 of the Control Word (06.042) to 0 provided Control Word Enable (06.043) = 1, or by making Hardware Enable = 0.
  5. If a trip occurs during the auto-tune sequence the drive will go into the trip state and Auto-tune (05.012) is set to zero. As in 4. above, the enable must be removed and re-applied before the drive can be restarted after the trip has been reset. However, care should be taken because if the auto-tune was not completed the drive parameters that should have been measured and set up will still have their original values.

The following describes the effects of the auto-tune test on the drive :

  1. All auto-tune tests rely on the motor being stationary when the test is initiated to give accurate results.
  2. If Select Motor 2 Parameters (11.045) = 0 then the parameters associated with motor map 1 are updated as a result of the test, and if Select Motor 2 Parameters (11.045) = 1 the parameters associated with motor map 2 are updated.
  3. Only when the whole test is completed, are the results written to the appropriate parameters and these parameters saved in the drive non-volatile memory. If Parameter Cloning (11.042) is set to 3 or 4 the parameters are also written to a non-volatile media card fitted on the drive.

The table below shows the parameters required for motor control indicating which should be set by the user and which can be measured with an auto-tune test.

Parameter Required for Measured in test
Motor Rated Frequency (05.006) Basic control
Motor Rated Current (05.007) Basic control
Motor Rated Speed (05.008) Slip compensation
Catch a spinning motor

Motor Rated Voltage (05.009) Basic control
Motor Rated Power Factor (05.010) Basic control 2
Number Of Motor Poles (05.011) Basic control
Stator Resistance (05.017) Ur, Ur I, Ur S and Ur Auto modes
Catch a spinning motor
1, 2
Transient Inductance (05.024) Improved performance 1, 2
Stator Inductance (05.025) Improved performance 2
Maximum Deadtime Compensation (05.059) Basic control 1, 2

Current At Maximum Deadtime Compensation (05.060)

Basic control 1, 2

Auto-tune test 1: Basic control parameters
This test measures the basic control parameters without moving the motor.

  1. A stationary test is performed to measure Stator Resistance (05.017), Transient Inductance (05.024), Maximum Deadtime Compensation (05.059) and Current At Maximum Deadtime Compensation (05.060).

Auto-tune test 2: Basic control and improved performance parameters
This test measures the parameters for improved performance by rotating the motor.

  1. Auto-tune test 1 is performed.
  2. A rotating test is performed in which the motor is accelerated with the currently selected ramps up to a frequency of Motor Rated Frequency (05.006) x 2/3, and the frequency is maintained at that level for 4 seconds. Stator Inductance (05.025) is measured and this value is used in conjunction with other motor parameters to calculate Motor Rated Power Factor (05.010). The motor should be unloaded for this test.

The table below shows the trips that can occur during an auto-tune test:

Trip Reason Trip can occure in test
Autotune Stopped The final drive enable or the final drive run were removed before the test was completed. All
Resistance The measured value of Stator Resistance (05.017) exceeded the range of the parameter. All


Parameter05.013  Dynamic V To F Select
Short descriptionSet to 1 to enable Dynamic V to F mode
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

Dynamic V to F mode is intended for applications where power loss should be kept to a minimum under low load conditions, but dynamic performance is not important. The reduction in power loss under low load conditions is achieved by increasing the rated frequency used to derive the frequency to voltage characteristic of the drive with reduced load. If Flux Optimisation Select, Dynamic V To F Select (05.013) = 0 then Motor Rated Frequency (05.006) is used directly to define the output voltage characteristic. If Flux Optimisation Select, Dynamic V To F Select (05.013) = 1 then a modified value of motor rated frequency is used:

Motor rated frequency = Motor Rated Frequency (05.006) x [2 - |Percentage Load (04.020)| / 70.0%]

For loads > 70% Motor Rated Frequency (05.006) is used directly.


Parameter05.014  Open-loop Voltage Mode
Short descriptionDefines the mode used to set the output voltage
ModeOpen‑Loop
Minimum0Maximum6
Default2Units 
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, TE

ValueTextDescription
0Ur.SStator resistance and voltage offset measured at each start
1UrNo measurements
2FDFixed boost mode.
3Ur.AutoStator resistance and voltage offset measured at first drive enable
4Ur.IStator resistance and voltage offset measured at each power-up
5SrESquare law characteristic
6Fd.tapFixed boost with zero slip at zero reference

The Open-loop Voltage Mode (05.014) defines the voltage output mode, as given below. It should be noted that the maximum output voltage of the drive is limited to a level just below D.c. Bus Voltage (05.005) / √2. Therefore, if the drive is being supplied via its own rectifier input stage the output voltage is limited to a level just below that of the supply voltage. If the drive is operating in voltage mode the output voltage is limited to Motor Rated Voltage (05.009) or the maximum possible output voltage whichever is the lowest (also refer to Over Modulation Enable (05.020)).

0: Ur S (Resistance compensation, stator resistance measured at each start)
Resistance compensation is a form of stator flux oriented sensorless motor control. A linear frequency to voltage characteristic is used where the drive output voltage is increased from 0V to Motor Rated Voltage (05.009). as the |Output Frequency (05.001)| increases from 0Hz to Motor Rated Frequency (05.006). When the |Output Frequency (05.001)| is above Motor Rated Frequency (05.006) the output voltage is limited to Motor Rated Voltage (05.009). Vector based stator resistance compensation is applied below Motor Rated Frequency (05.006) / 4 and then this is tapered off from Motor Rated Frequency (05.006) / 4 to Motor Rated Frequency (05.006) / 2. This method controls the flux level correctly in the motor in the steady state provided the correct value of Stator Resistance (05.017) is used.

If slip compensation is not being used (see Motor Rated Frequency (05.006) ) then additional voltage compensation can be applied below Motor Rated Frequency (05.006) / 10 to have an additional torque boost at very low frequencies, see Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084).

The Stator Resistance (05.017) is measured each time the drive is started. This test can only be done with a stationary motor where the flux has decayed to zero. Therefore this mode should only be used if the motor is guaranteed to be stationary each time the drive is enabled. To ensure that the measurement is not carried out before the flux has decayed, there is a period of one second after the inverter has been disabled during which the test is not carried out if the drive is re-started. The Stator Resistance (05.017) is not automatically saved in non-volatile memory after each test.

1: Ur (Resistance compensation with no stator resistance measurement)
Resistance compensation is used as in Ur S mode, but the Stator Resistance (05.017) is not measured.

2: Fixed (Fixed boost with linear characteristic)

A fixed frequency to voltage characteristic is used as shown above where the voltage at 0Hz is defined by Low Frequency Voltage Boost (05.015). The voltage characteristic moves linearly with output frequency passing through four points determined by [Boost End Voltage (05.074) and Boost End Frequency (05.075)], [Second Point Voltage (05.076) and Second Point Frequency (05.077)], Third point voltage (05.078) and Second Point Frequency (05.077), and [Motor Rated Voltage (05.009) and Motor Rated Frequency (05.006)].

By default Boost End Frequency (05.075) is set to half the Motor Rated Frequency (05.006), Second Point Frequency (05.077) is set 55% and Third point frequency (05.079) is set to 75%. Similarly by default Boost End Voltage (05.074) is set at half the Motor Rated Voltage (05.009), Second Point Voltage (05.076) 55% and Third point voltage (05.078) is set to 75%. This is to produce the same characteristic as SK by default.

3: Ur Auto (Resistance compensation, stator resistance measured on first start)
Resistance compensation is used as in Ur S mode, but the Stator Resistance (05.017) is only measured once when the drive is first enabled. After the test has been completed successfully the mode is changed to Ur mode and Stator Resistance (05.017) is saved to non-volatile memory. If Parameter Cloning (11.042) is set to 3 or 4 the Stator Resistance (05.017) is also written to a non-volatile media card fitted in the drive. If the test fails the mode is changed to Ur mode, but Stator Resistance (05.017) is not updated.

4: Ur I (Resistance compensation, stator resistance measured at power-up)
Resistance compensation is used as in Ur S mode, but the Stator Resistance (05.017) is only measured when the drive is enabled for the first time after each power-up.

5: Square (Fixed boost with square characteristic)
A fixed square frequency to voltage characteristic is used as shown below. When the |Output Frequency (05.001)| is below Motor Rated Frequency (05.006) the Output Voltage (05.002) is given by:

Output Voltage (05.002) = Low Frequency Voltage Boost (05.015) + [(Motor Rated Voltage (05.009) - Low Frequency Voltage Boost (05.015)) x ( | Output Frequency (05.001) | / Motor Rated Frequency (05.006))2]

6: Fixed boost with tapered slip limit
Normally, slip compensation calculations do not allow the final output frequency to be opposite in sign to the final frequency reference. This can be an issue in some applications where good torque control is required close to zero speed. In this mode of operation this limitation is removed.

To give even better control of the amount of slip being applied close to zero speed Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) can be used to taper the slip compensation limit ( Slip Compensation Limit (05.033) ) down to 0 at zero frequency demand.

If the slip limit taper start point set by Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) is > Slip Compensation Limit (05.033) then there is still no slip compensation applied in the opposite direction to the final frequency demand (see Fig 5.11a), but if the slip limit taper start point set by Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) is < Slip Compensation Limit (05.033) then a controlled amount of slip compensation can be applied in the opposite direction to the final frequency demand (see Fig 5.11b)


Parameter05.015  Low Frequency Voltage Boost
Short descriptionDefines the level of voltage boost at 0Hz when using a fixed V to F relationship
ModeOpen‑Loop
Minimum0.0Maximum25.0
Default3.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW, BU

* 3.0% up to Size D, 2.0% for Size 7 and 8, and 1.0% for larger sizes

See Open-loop Voltage Mode (05.014).

During auto-tune test 2 the drive uses the fixed boost voltage mode. Low Frequency Voltage Boost (05.015) is used to define the level of low voltage boost used during the test. See Open-loop Voltage Mode (05.014) for more details.


Parameter05.017  Stator Resistance
Short descriptionDefines the resistance of the motor stator
ModeOpen‑Loop
Minimum0.0000Maximum99.9999
Default0.0000Units
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places4
CodingRW, RA

The Stator Resistance (05.017), Transient Inductance (05.024) and Stator Inductance (05.025) are derived from the star connected per phase equivalent circuit of an induction motor shown below.

The steady state parameters are converted to equivalent transient model parameters:

Rs = R1

Lm = Lm

Ls = L1 + Lm

Lr = L2 + Lm

σLs = Ls - (Lm2 / Lr)

The equivalent drive parameters are:

Stator Resistance (05.017) = Rs

Transient Inductance (05.024) = σLs

Stator Inductance (05.025) = Ls


Parameter05.018  Maximum Switching Frequency
Short descriptionDefines the maximum switching frequency that can be used by the drive
ModeOpen‑Loop
Minimum0MaximumVM_MAX_SWITCHING_FREQUENCY
Default3UnitskHz
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, TE, VM, RA

ValueTextDescription
00.667667Hz switching frequency
111kHz switching frequency
222kHz switching frequency
333kHz switching frequency
444kHz switching frequency
566kHz switching frequency
688kHz switching frequency
71212kHz switching frequency
81616kHz switching frequency

Maximum Switching Frequency (05.018) should be set to the required PWM switching frequency. The drive inverter will operate at this frequency unless Auto-switching Frequency Change Disable (05.035) = 0 and the inverter temperature exceeds the threshold for automatic switching frequency reduction (see Inverter Temperature (07.034)). The actual switching frequency is shown in Switching Frequency (05.037). The switching frequency has a direct effect on the sample rate for the current controllers (see Current Controller Kp Gain (04.013)). All other control tasks are at a fixed rate of 1ms.

As default Auto-switching Frequency Change Disable (05.035) = 0 and the system described above is always active. If Auto-switching Frequency Change Disable (05.035) = 1 then the automatic switching frequency changing system is disabled.

We recommend that a minimum ratio of 12:1 for the switching frequency compared to the maximum output frequency is used.


Parameter05.019  High Stability Space Vector Modulation
Short descriptionSet to 1 to enable High Stability Space Vector Modulation
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

If High Stability Space Vector Modulation (05.019) = 0 standard space vector modulation is used to derive the inverter control signals. If High Stability Space Vector Modulation (05.019) = 1 a modified form of space vector modulation is selected which can give the following advantages:

  1. With some motors instability can occur when operating below Motor Rated Frequency (05.006) / 2 especially with light loads and high switching frequency. The preferred method to solve this problem is to use RFC-A mode. However, if Open-loop mode is required, the instability can sometimes be reduced by selecting high stability space vector modulation.
  2. As the output voltage approaches the maximum available from the drive pulse deletion occurs. This can cause unstable operation with a lightly or fully loaded motor. High stability space vector modulation will reduce this effect.

The disadvantages of using high stability space vector modulation are:

  1. Increased acoustic noise from the motor.
  2. A reduction in the thermal capability of the drive at low output frequencies.


Parameter05.020  Over Modulation Enable
Short descriptionSet to 1 to enable over modulation
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

The maximum modulation level of the drive is normally limited to unity giving an output voltage equivalent to the drive input voltage minus voltage drops within the drive. If the motor rated voltage is set at the same level as the supply voltage some pulse deletion will occur as the drive output voltage approaches the motor rated voltage level. If Over Modulation Enable (05.020) is set to 1 the modulator will allow over modulation, so that as the output frequency increases beyond the motor rated frequency the voltage continues to increase above the motor rated voltage. The modulation depth will increase beyond unity producing trapezoidal waveforms. This can be used for example to get slightly better performance above motor rated frequency. The disadvantage is that the machine current will be distorted as the modulation depth increases above unity, and will contain a significant amount of low order odd harmonics of the fundamental output frequency.


Parameter05.024  Transient Inductance
Short descriptionDefines the inducatance of the transient components in the motor stator
ModeOpen‑Loop
Minimum0.000Maximum500.000
Default0.000UnitsmH
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places3
CodingRW, RA

See Stator Resistance (05.017).


Parameter05.025  Stator Inductance
Short descriptionDefines the inductance of the motor stator
ModeOpen‑Loop
Minimum0.00Maximum5000.00
Default0.00UnitsmH
Type32 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places2
CodingRW, RA

See Stator Resistance (05.017).


Parameter05.027  Slip Compensation Gain
Short descriptionDefines the gain of slip compensation
ModeOpen‑Loop
Minimum-150.0Maximum150.0
Default100.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

See Motor Rated Frequency (05.006).

Used to set the level of slip compensation or droop control.

A value of 100.0% gives rated slip compensation as defined in Motor Rated Frequency (05.006).

Negative values can be used to introduce droop control.

A value of 0.0% disables slip compensation.


Parameter05.028  Flux Control Compensation Disable
Short descriptionSet to 1 to disable Flux Control Compensation
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

If Flux Control Compensation Disable (05.028) = 0 the conversion from the Final Torque Reference (04.003) to Final Current Reference (04.004) takes into account the reduction in flux above base speed by increasing the current demand in order to keep the torque in the motor as requested. This is the preferred method of control as it ensures that the gain of the system remains constant in frequency control mode and it gives the correct relationship between torque and current in torque control modes. However, it is possible to get instability in frequency control mode when flux is weak at high speed, which may be caused by the Motor Rated Speed (05.008) being set to an incorrect value. If Flux Control Compensation Disable (05.028) 1 the compensation for flux level is disabled which can sometimes prevent instability under these conditions.


Parameter05.031  Voltage Controller Gain
Short descriptionDefines the proportional gain of the d.c. link voltage controller
ModeOpen‑Loop
Minimum1Maximum30
Default1Units 
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

Voltage Controller Gain (05.031) can be used to modify the proportional gain of the d.c. link voltage controller used for standard ramp and supply loss control.


Parameter05.032  Torque Per Amp
Short descriptionDisplays the calculated value of kt for the attached motor
ModeOpen‑Loop
Minimum0.00Maximum500.00
Default UnitsNm/A
Type16 Bit VolatileUpdate RateBackground write
Display FormatStandardDecimal Places2
CodingRO, ND, NC, PT, BU

Torque Per Amp (05.032) is automatically calculated from the motor parameters assuming a motor efficiency of 90%.

Torque Per Amp (05.032) = Estimated rated shaft power / [((Motor Rated Speed x 2π) / 60) x ITRated]

where

ITrated is the rated torque producing current (see Torque Producing Current (04.002) ) and

Estimated rated shaft power = √3 x Motor Rated Voltage (05.009) x Motor Rated Current (05.007) x Motor Rated Power Factor (05.010) x 0.9

Torque Per Amp (05.032) is used in the automatic calculation of the speed controller gains.


Parameter05.033  Slip Compensation Limit
Short descriptionDefines the limit for slip compensation
ModeOpen‑Loop
Minimum0.00Maximum10.00
Default10.00UnitsHz
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places2
CodingRW

Symmetrical maximum of the slip compensation frequency. This parameter applies a limit to the amount of slip compensation used.


Parameter05.035  Auto-switching Frequency Change Disable
Short descriptionSet to 1 to prevent the drive from changing between switching frequencies
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

See Maximum Switching Frequency (05.018).


Parameter05.036  Slip Compensation Filter
Short descriptionDefines the time constant of the filter used for slip compensation
ModeOpen‑Loop
Minimum0Maximum3
Default1Unitsms
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, TE

ValueText
064
1128
2256
3512

Time constant for the slip compensation filter. A first order filter is applied to the torque producing current when calculating the slip compensation in order to reduce the chance of instability being introduced.


Parameter05.037  Switching Frequency
Short descriptionDisplays the current switching frequency used by the drive
ModeOpen‑Loop
Minimum0MaximumVM_MAX_SWITCHING_FREQUENCY
Default UnitskHz
Type8 Bit VolatileUpdate RateBackground write
Display FormatStandardDecimal Places0
CodingRO, TE, VM, ND, NC, PT

ValueTextDescription
00.667667Hz switching frequency
111kHz switching frequency
222kHz switching frequency
333kHz switching frequency
444kHz switching frequency
566kHz switching frequency
688kHz switching frequency
71212kHz switching frequency
81616kHz switching frequency

See Maximum Switching Frequency (05.018).


Parameter05.038  Minimum Switching Frequency
Short descriptionDefines the minimum switching frequency that can be used by the drive
ModeOpen‑Loop
Minimum0MaximumVM_MAX_SWITCHING_FREQUENCY
Default0UnitskHz
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW, TE, VM, RA

ValueTextDescription
00.667667Hz switching frequency
111kHz switching frequency
222kHz switching frequency
333kHz switching frequency
444kHz switching frequency
566kHz switching frequency
688kHz switching frequency
71212kHz switching frequency
81616kHz switching frequency

Minimum Switching Frequency (05.038) defines the minimum frequency limit used if the inverter thermal model is actively reducing the switching frequency due to temperature. 
Note that parameter Maximum Switching Frequency (05.018) takes priority over parameter Minimum Switching Frequency (05.038) so is not limited by parameter Minimum Switching Frequency (05.038).  The actual minimum switching frequency limit used is the lower of Maximum Switching Frequency (05.018) and Minimum Switching Frequency (05.038).


Parameter05.040  Spin Start Boost
Short descriptionDefines the level of spin start boost used by the algorithm that detects the speed of a spinning motor
ModeOpen‑Loop
Minimum0.0Maximum10.0
Default1.0Units 
Type8 Bit User SaveUpdate RateBackground write
Display FormatStandardDecimal Places1
CodingRW

Spin Start Boost (05.040) is used by the algorithm that detects the frequency of a spinning motor when the drive is enabled and Catch A Spinning Motor (06.009) ≥ 1. For smaller motors the default value of 1.0 is suitable, but for larger motors Spin Start Boost (05.040) may need to be increased. If Spin Start Boost (05.040) is too small the drive will detect zero speed whatever the frequency of the motor, and if Spin Start Boost (05.040) is too large the motor may accelerate away from standstill when the drive is enabled.


Parameter05.042  Reverse Output Phase Sequence
Short descriptionSet to 1 to reverse the sequence on the output phases
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

If Reverse Output Phase Sequence (05.042) = 0 the output phase sequence is U-V-W when Output Frequency (05.001) is positive and W-V-U when Output Frequency (05.001) is negative. If Reverse Output Phase Sequence (05.042) = 1 the output phase sequence is reversed so that the phase sequence in W-V-U for positive frequencies and U-V-W for negative frequencies.


Parameter05.059  Maximum Deadtime Compensation
Short descriptionMaximum Deadtime Compensation
ModeOpen‑Loop
Minimum0.000Maximum10.000
Default0.000Unitsµs
Type16 Bit User SaveUpdate RateBackground Read
Display FormatStandardDecimal Places3
CodingRO, NC, PT

Maximum Deadtime Compensation (05.059) is the deadtime compensation used to compensate for dead-time effects in the inverter. This level of compensation is used when the drive output current is above Current At Maximum Deadtime Compensation (05.060) Both of these values related to dead-time compensation are measured during auto-tuning and cannot be set by the user. It should be noted that if the auto-tuning test is not performed and Maximum Deadtime Compensation (05.059) = 0 then dead-time compensation is disabled. Although it is not recommended, it is possible to disable dead-time compensation by setting Disable Deadtime Compensation (05.061) = 1.


Parameter05.060  Current At Maximum Deadtime Compensation
Short descriptionCurrent at which maximum deadtime compensation is applied
ModeOpen‑Loop
Minimum0.00Maximum100.00
Default0.00Units%
Type16 Bit User SaveUpdate RateBackground Read
Display FormatStandardDecimal Places2
CodingRO, NC, PT

See Maximum Deadtime Compensation (05.059).


Parameter05.061  Disable Deadtime Compensation
Short descriptionDisable Deadtime Compensation
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground Read
Display FormatStandardDecimal Places0
CodingRW

See Maximum Deadtime Compensation (05.059).


Parameter05.074  Boost End Voltage
Short descriptionDefines the boost end voltage
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default50.0Units%
Type16 Bit User SaveUpdate Rate16ms
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.075  Boost End Frequency
Short descriptionDefines the boost end frequency
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default50.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.076  Second Point Voltage
Short descriptionDefines the second point voltage
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default55.0Units%
Type16 Bit User SaveUpdate Rate16ms
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.077  Second Point Frequency
Short descriptionDefines the second point frequency
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default55.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.078  Third point voltage
Short descriptionDefines the third point voltage
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default75.0Units%
Type16 Bit User SaveUpdate Rate16ms
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.079  Third point frequency
Short descriptionDefines the third point frequency
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default75.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

See Open-loop Voltage Mode (05.014).


Parameter05.080  Low acoustic noise enable
Short descriptionSet to 1 to change the modulation to reduce the switching frequency noise
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

If Maximum Switching Frequency (05.018) has been set in the 2kHz to 6kHz range, setting Low acoustic noise enable (05.080) modifies the modulation scheme to reduce the fundamental switching frequency acoustic noise.

When this mode is enabled, the effect of the switching frequency fundamental in the output voltage is reduced by moving the switching points of the output phases in each PWM switching period by the same randomly weighted offset.  This reduces the level of noise from the switching frequency but will introduce noise at lower and higher frequencies at a lower audible level.  The maximum offset reduces as the output voltage increases. 


Parameter05.081  Change to maximum drive switching frequency at low output current
Short descriptionChange to maximum drive switching frequency at low output current
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

If the user has selected a maximum switching frequency in the range 2kHz to 6kHz, setting this parameter will cause the drive to switch to maximum switching frequency at low output currents.

Swaps to 16kHz if the output current magnitude is less than 30% (Frame sizes 1-4) and 20% (Frame sizes 5 and above) of drive OI.AC level for a period longer than 100ms.

Swaps back immediately if the output current magnitude increases above the defined levels by more than 5%.

The original switching frequency may still be under the control of the inverter thermal model.  This feature is disabled if the thermal model or user has changed the switching frequency within the last 10 seconds.


Parameter05.083  Voltage Shelving Disable
Short descriptionSet to 1 to only measure the d.c. link voltage when the inverter is inactive
ModeOpen‑Loop
Minimum0Maximum1
Default0Units 
Type1 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places0
CodingRW

When this parameter is 1, the DC link voltage will only be measured when the inverter is inactive. The DC link voltage readings are filteredusing a 128ms filter and the average value stored for use when the inverter becomes active.

This stored value is used instead of the actual measurement when the output voltage demand is converted to a modulation index. 

This removes the dc bus voltage forward compensation.  It will also remove the effects of “oscillation” experienced when the drive is supplied by an extremely soft supply of through a high inductance filter.


Parameter05.084  Low Frequency Torque Adjustment
Short descriptionControls the boost level of the slip frequency when the output frequency is below one third of the rated frequency.
ModeOpen‑Loop
Minimum0.0Maximum100.0
Default0.0Units%
Type16 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

This parameter can be used to modify torque at low output frequencies in one of three different ways:

1) Slip boost

Used in resistor compensation (Ur) modes, Open-loop Voltage Mode (05.014) set to 0, 1, 3, and 4.

The slip frequency (see Motor Rated Frequency (05.006) is modified when the output frequency is below one third of the motor rated frequency to provide a torque boost.
The modification consists of an addition to the calculated slip frequency controlled by the user parameter Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) . The addition is equal to Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) x calculated slip frequency at zero Hz, falling linearly to 0.0% at one third of the motor rated frequency. e.g. if this parameter is set to 100%, the slip at 0Hz for rated torque producing current would be rated slip + rated slip or 2 x rated slip.

2) Voltage boost

Used in resistor compensation (Ur) modes, Open-loop Voltage Mode (05.014) set to 0, 1, 3, & 4, and slip compensation has been disabled (see Motor Rated Frequency (05.006) ).

The amount of stator resistor compensation is modified when the output frequency is below one tenth of the motor rated frequency to provide a torque boost.  The modification consists of an addition to the calculated stator resistor compensation controlled by the user parameter Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) . The addition is equal to Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) x calculated stator resistor compensation at zero Hz falling linearly to 0 at one tenth of the motor rated frequency. e.g. if this parameter is set to 100%, the stator resistance compensation at 0Hz would be calculated stator resistor compensation + calculated stator resistor compensation  or 2 x calculated stator resistor compensation .


3) Slip taper

This feature is used in fixed boost tapered mode (Open-loop Voltage Mode (05.014) set to 6) to taper the slip limit back to zero at 0Hz. The taper start point is defined as Low Frequency Estimator Threshold, Low Frequency Torque Adjustment (05.084) x Motor Rated Frequency (05.006) / 100. See Open-loop Voltage Mode (05.014) for a detailed explanation.


Parameter05.088  Ur Mode Pre-Flux delay
Short descriptionThe delay begins as the motor starts to run and during the pre-flux delay the torque axis voltage compensation is held at zero.
ModeOpen‑Loop
Minimum0.0Maximum0.7
Default0.1Unitss
Type8 Bit User SaveUpdate RateBackground read
Display FormatStandardDecimal Places1
CodingRW

Setting Ur Mode Pre-Flux delay to a value from 0.0s to 0.7s will configure the Ur mode pre-flux delay. The delay begins as the motor starts to run and during the pre-flux delay the torque axis voltage compensation is held at zero.  The delay provides time for the flux to build up to reduce the risk of unstable behaviour during motor starting. The user configurable delay function has been added for use with the brake macro, where the mechanical brake is holding the shaft while the motor is started.  The delay can be set depending on the motor and the system.