Description of the Software Modules and Parameters
Parameter manual b maXX BM5800
Document No.: 5.16029.03
493
of 814
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142.2 Field weakening factor
The field weakening factor represents the current level of the field weakening.
The field weakening factor is without units. The range of values extends from 0 to 1.
The field weakening factor accords to the minimum value between field weakening output
Z142.13– and the field weakening factor after the speed Z142.12–.
Furthermore, the field weakening factor of the parameter Z142.5– "Minimum field weak
factor" is limited:
Field weakening factor [Z142.2–] Minimum field weak factor [Z142.5–].
Further details see chapter ZField weakening controller– from page 484.
142.3 Kp field weakening controller
Proportional gain of field weakening controller.
With a SM, the field weakening controller can be set more finely than with an ASM, as no
delay in the reduction of the field due to the rotor time constant occurs.
A P-gain of 0 switches off the field weakening controller.
NOTE!
During the continuous operation of the field weakening controller the PWM control is
limited to the linear range (i.e. no overmodulation) (factor field weakening threshold
Z142.15– less than or equal to 1). In contrast, during the transient response the
range of the overmodulation can be reached.
The breakdown torque controller (from FW version 1.14 on) however can allow the
continuous operation in the overmodulation range (factor breakdown torque thresh
-
old Z142.21– greater than1).
In the linear range of the PWM control the set voltage (before the PWM module) ac-
cords to the actually modulated voltages (after the PWM). In contrast and due to tech-
nical reasons, in the overmodulation the set voltages becomes disproportionately
greater with increasing modulation level than the actually modulated voltage (after
the PWM).
The PWM voltage (Z142.7–), to be limited by the field weakening controller or break-
down torque controller is calculated up to FW version 1.14 with the set voltage before
the PWM. This way, values are presented in the overmodulation range, which are too
high. From FW version 1.15 the voltage can be calculated via the actually modulated
voltage. The use of the corrected voltage values is optional and in general not active
(parameter Field weakening mode
Z142.1– bit 2). When using the corrected voltage
it could be that the parameterization of the breakdown torque controller must be
adapted.
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