Presented herein are systems and methods for attenuating flow ripple generated by a hydraulic pump. In certain aspects, a method and system for operating a hydraulic positive displacement pump according to a stabilized command profile are disclosed, such that flow ripple generated by operation of the pump according to the stabilized command profile is attenuated as compared to operation of the pump according to a corresponding nominal command profile. In other aspects, a pressure-balanced active buffer is disclosed that allow for at least partially cancelling flow ripple in a hydraulic circuit comprising a pump. In another aspect, a method for generating ripple maps for a pump is disclosed. Such ripple maps may be used, for example, to determine the stabilized command profile used to operate the pump, or may be used by the pressure-balanced active buffer to counteract ripple in the hydraulic circuit.

In a hydraulic control device, when it is detected that a pressure of first oil (output pressure) detected by an output pressure sensor pulsates, a transmission control unit as a TCU stops driving of a second pump or decreases a rotation number of the second pump as a first operation. Alternatively, when it is detected that the output pressure pulsates, the TCU increases the rotation number of the second pump to a rotation number (for example, maximum rotation number) that is higher than a target rotation number as a second operation.

A control system and method of a VFD-based pump are disclosed. The control system controls an electric motor via a VFD, and the electric motor drives the pump. The control system comprises: an anti-ripple injection module for injecting an anti-ripple signal into a control path, the anti-ripple signal causing pressure ripples in the pump output to he at least partially cancelled. Further disclosed is a pump system, comprising: a VFD, an electric motor, and a pump, wherein the VFD comprises the control system stated above.

A pumping system for compressible fluids comprises a first pump (20) having a first pump outlet (21) and a second pump (30) having a second pump outlet (31), wherein the first pump outlet (21) and the second pump outlet (31) merge in a junction (40) which is in fluid communication with a main outlet (48). The pumping system further comprises a control (50) to regulate the output pressure (p2) of the second pump (30) on the basis of a measurement of the output pressure (p1) of the first pump (20). The corresponding method of operating a pumping system is also disclosed.