05/12/2025
How-to | ctrlX Configurator | PDC_cont calculation

ctrlX Configurator - Continuous DCbus power (PDCcont) calculation in drive lines

In a drive line a power supply XVE2/XVR2 or Converter XCS2/XCD2 needs to supply sufficient power to run all connected drives (DCbus connection).

The DC bus continuous power of a drive PDCcont_axis depends on

  • The DC bus voltage

  • Possible connection to a motor (rotative motor, linear motor, without)

  • Type of usage (motor or generator use)

  • Application type (typical servo application or typical continuous power application)
    Typical Servo Application

    No longer lasting movements with constant torque and speed

    Often acceleration and deceleration
    High overload
    Reversing movements
    High dynamics

    Usage in both speed ranges: close to standstill in working mode; high speed for movement to positions
    Typical continuous power application
    Longer lasting movements with constant torque and speed
    No high dynamics


PDC_cont (supply) >= fG * PDCcont_sum (drive line sum)

PDCcont_sum = sum PDCcont_axis

Following formulas are used for the PDCcont_axis calculation in the ctrlX configurator:

Motor-Drive combination

Drive with rotative motor

Application type

Typical servo application

Type of usage rive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
(0,5 * M0 * 2 * PI * 0,25 * nmax) / (60 * 1000 * 0,8) =
0,00001636 * M0 * nmax

The reference value is based on a load which results from the effective power calculated with 50% continuous power at an average speed of 25% from max rpm and an average efficiency of 80%.

Speed-Torque Diagram Drive with rotative motor Typical servo application

Motor-Drive combination

Drive with linear motor

Application type

Typical servo application

Type of usage drive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
(0,5 * F0 * 0,25 * vmax) / (60 * 1000 * 0,7) =
0,00000298 * F0 * vmax

The reference value is based on a load which results from the effective force with 50% continuous standstill force at an average speed of 25% from max speed and an average efficiency of 70%.

Speed-Torque-Diagram Typical servo application Type of usage drive

Motor-Drive combination

Drive w/o motor

Application type

Typical servo application

Type of usage drive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
(0,5 * Icont * 0,25 * U_DC * (root 3)) / ((root 2) * 1000 * 0,97) =
0,0001578 * Icont * U_DC

The reference value is based on a load which results from the effective current of 50% continuous output current at an average voltage of 25% from max output voltage and an average efficiency of 97%.

Motor-Drive combination

Drive with rotative motor

Application type

Typical continuous power application

Type of usage drive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
Maximum(P_Result_cont = f(n)) / 0,85

The reference value is based on the max of the resulting continuous power curve of the motor-drive-combination with an average efficiency (motor and inverter) of 85%.

Speed-Power-Diagram Drive with rotative motor Motor use with power from DC bus

Motor-Drive combination

Drive with linear motor

Application type

Typical continuous power application

Type of usage drive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
Maximum(P_Result_cont = f(v)) / 0,75

The reference value is based on the max of the resulting continuous power curve of the motor-drive-combination with an average efficiency (motor and inverter) of 75%.

Speed-Power-Diagram Typical continuous power application Motor use with power from DC bus

Motor-Drive combination

Drive w/o motor

Application type

Typical continuous power application

Type of usage drive

Motor use with power from DC bus

Calculation formula

PDCcont_axis =
(Icont * U_DC * (root 3)) / ((root 2) * 1000 * 0,98) =
0,0012497 * Icont * U_DC

The reference value is based on a load which results from the continuous output current at a max output voltage and an average efficiency of 98%. 
In single motor-drive combinations (converter) the PDCcont_axis is limited to PDC_cont (supply) of the converter.

Typical DC/DC converter application

Product

DC/DC converter

Calculation formula

PDCcont_axis =
(0,9 * Icont * 0,66 * U_DC) / (1000 * 0,98) =

0.00060612244898 * Icont * U_DC


General

When type of usage drive = generator use with power feeding into DC bus, the PDCcont_axis is a negative value.
 

Characteristics from formulas

PDC_cont: Continuous DC power with/without choke in kW
PDCcont_sum: DC bus rated power - sum from drive line in kW
PDCcont_axis: DC bus continuous power drive in kW
(in a double axes drive it is the sum of both drive integrated axis)
fG: Simultaneity factor of all connected drives (0..1)
M0: Continuous stand still torque of the motor-drive combination in Nm
F0: Maximum standstill force of the motor-drive combination in N
nmax: Max rpm of the motor-drive combination in rpm
vmax: Maximum speed at Fmax of the motor-drive combination in m/min
U_DC: DC bus voltage in V
Icont: Continuous output current drive when fs = 4 kHz in A
P_Result_cont: Maximum continuous stand still torque of the motor-drive combination in kW

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