Example
l
Running the pump, e.g. at a low speed “against” the built-up pressure. Scope
plot (Moog D
RIVE
A
DMINISTRATOR
5) for Scope ID 11 – m_act yields a mean
value of M = 15.9 [Nm]. The built-up pressure at the pressure sensor is p =
100 [bar] => c_M = 0.159 [Nm/bar] => V_g = 10 [ccm/rev]
Accordingly, both parameters (P 2851[0; 1] - HYD_Pump) can be set. However, only
one of the two values should be set. The other one will be automatically calculated
afterwards and will be shown accordingly.
P 2851[2] - HYD_Pump is used to set the nominal pressure. P 2851[3] - HYD_Pump
specifies the volumetric efficiency at this rating point. This information will then be
used to calculate the leakage volumetric flow rate, which is used internally to control
the volumetric flow rate.
For pumps with variable-displacement volume, a second pump data set can be
created P 2873 HYD_Pump2. This can be selected via P 2863 HYD_TabCtrl bit 8 for
the respective motion block (7.11.6 Hydraulic Motion profile). Alternatively, the
displacement volume can also be adjusted online via a pump scaling using P 2879
[2] Pump1_DisplScalePDO and P 2879[3] Pump2_DisplScalePDO. This allows the
displacement volume to be changed variably during the process.
7.11.2.1 Speed limits
The pump’s minimum and maximum speeds can be set in P 2851[4; 5] - HYD_
Pump. The control system will not exceed or fall below
the values set there.
MOOG
ID No.: CB40859-001 Date: 11/2020
MSD Servo Drive - Device Help
176
7 Control
Example
l
Maximum speed: 3000 [rpm], Minimum speed: 0 [rpm] (pump is not allowed
to rotate “backwards”)
l
Maximum speed: 3000 [rpm], Minimum speed: -200 [rpm] (pump is only
allowed to rotate backwards “slowly”)
l
Maximum speed: 3000 [rpm], Minimum speed: -3000 [rpm] (no restriction for
negative speeds)
In contrast, the pump protection functions, among other functions, are used to protect
the pump against thermal or mechanical destruction at low speeds. As per the
corresponding explanations, the configured “critical speed” can definitely be fallen
below.
In addition to the pump speed, the pump acceleration and deceleration can also be
limited. Parameters P 2855 HYD_PumpAcc and P 2856 HYD_PumpDec can be
used to set the maximum permissible ramp of the pump. (see 7.11.6.2 Servo pump