10. Blood Pump
The Blood Pump Controller compares the tachometer motor speed
information with the desired speed commanded by the SBC and
corrects the level provided to the Blood Pump Power Board
accordingly. In this way, the Blood Pump Controller guarantees
the accuracy of the pump, and the Blood Pump Power Board does
not require any calibration. In addition, the Blood Pump
Controller monitors for control problems, such as underspeed or
overspeed, which may result from failures in the Blood Pump
Power Board.
The Blood Pump Controller Board also monitors the motor speed
independently of the tachometer signal using the motor's back
electromagnetic force (EMF). Periodically (every 0.5 second), the
motor drive is turned off for approximately 6 milliseconds and the
voltage at the motor terminals is measured. Though this does not
result in as precise an indication as the tachometer signal, gross
failures can be determined, such as when the tachometer signal is
lost or for overspeed detection. The EMF must be calibrated.
Refer to Section 18.5.10 for more information on this calibration.
An identical circuit is provided for an optional second blood pump
which is used for the Double-Pump Single Needle,
Hemodiafiltration (HDF) and On-line HDF options.
157-1278-917 Rev A 10-11
April 2004
To Next Page
Loading...
