Which products are affected?
All 9400 HighLine devices in combination with synchronous machines as of firmware version 2.0
Function description
It is possible now to operate synchronous motors in the field weakening range.
When a motor is selected from the motor list, a maximum speed, which protects the motor and drive from impermissible high speed, is entered under C00596.
Protection of the drive controller
In case of a pulse inhibit of a synchronous machine a voltage is induced. This voltage is proportional to the speed. In the field weakening range this voltage may damage the drive controller if a max. permissible speed or voltage is exceeded.
C00596 =< a speed which generates a voltage of 800 V.
Protection of the motor:
C00596 =< max. mechanical speed
The maximum speed (or voltage) is calculated as follows:
kEphase_to_phase = Voltage constant (phase-to-phase) [V/XXXrpm]
Information about the voltage can be found in the manufacturer's specifications for the motor. The voltage constant is typically indicated in V/1000 rpm. However, dependent on the motor applied, different reference speed values may be used. Therefore, special attention is paid to the reference speed in the formulas mentioned below.
If kEphase_to_phase_hot is indicated only, the following general rule applies: kEphase_to_phase_cold ~ kEphase_to_phase_hot * 1.15
nmax = 800 V * kEphase_to_phase_reference (1.41 * kEphase_to_phase_cold) or nmax = 800 V * kEphase_to_phase_reference (1.41 * kEphase_to_phase_hot * 1.15)
Calculation example for MCS12L20:
nmax = 800 V * 1000 rpm / (1.41 * 149.2 * 1.15) = 3296 rpm
MCS motor examples:
nrated [rpm] nmax mech. [rpm] C00596 [rpm] Limitation
MCS09F38 3750 7000 6230 by voltage
MCS12L20 1950 6000 3330 by voltage
MCS14H32 3225 6000 6000 mechanical
MCS19P30 3000 4000 4000 mechanical
Information about which speed and torque can be reached will be provided on the Internet (www.Lenze.com) in the course of the 3rd quarter of 2007.
Moreover, it must be considered that the current consumption in the field weakening range increases more strongly than in the basic setting range. As a result, the motor temperature in the field weakening range increases more strongly, too.
The function is documented in the SW_9400_Parameter_setting_HighLine_v2.0.
Chapter: Motor interface\Servo controller\Extended commissioning\Field weakening for synchronous machines.
Applications
The function is only suitable when the torque required in case of high speed is lower than in case of low speed.
It is to be observed that synchronous machines often only reach a lower field weakening factor than asynchronous machines.
The function is not suited for highly-dynamic applications in case of which the field weakening range is to be used (clock time < 40 ms within the field weakening).
