A test method for the static and dynamic characteristics of servo-motor-pumps

A test method for dynamic and static performances of Servo-Motor-Pumps (SMP) was proposed. As a new and high performance component for both power conversion and control, a SMP is critical for an Electro-Hydrostatic Actuator (EHA). However, there is still no accepted standard test method. An approach to measure both the flow curves and frequency responses was suggested, by testing a no-load EHA system where the SMP is installed. With a set of speed limits in position loop controller, the EHA step responses are tested, whose maximum output speeds can be derived by differentiating the output displacements and further the SMP flow outputs can be calculated that correlate the speed limits. A "speed command—flow output" curve is ultimately plotted. As the closed loop frequency response of a no-load EHA is implemented as conventionally, the open loop frequency response of the EHA system can be calculated and further the SMP frequency response can be deduced by eliminating the integration and the static gain in the control loop. The method and experimental data were given, demonstrating a simple and practical methodology to measure the dynamic and static performances of a SMP.