Abstract. To study the flow characteristics of a new swashplate
rotary valve distribution double-row axial piston pump, an instantaneous
flow model was developed for the pump, the influences of structural
parameters on the flow pulsation and uneven coefficient of flow were
determined, and the ideal plunger distribution parameters were derived. On
this basis, a valve distribution model was developed for the pump, the flow
superposition process in the plunger cavity was analyzed, and the high-speed
switching valve's control strategy was optimized. Additionally, the effects
of parameters such as the plunger motion frequency, the plunger cavity's
dead zone volume, the spool valve's preloading force, and the spool's equivalent mass on the flow characteristics were studied. The results show that the new
pump had a small flow pulsation when there were five plungers in both the
inner and outer rows and the dislocation angle was 18∘. The
plunger's reverse-suction effect at the moment when the discharge valve
opened and the suction valve closed and the plunger cavity's dead zone
volume size were the primary factors affecting the size of the pump's flow
spike. The discharge valve's opening was delayed by 3 ms to be consistent
with the suction valve's closing time; for this case, the flow peak was
small and the volumetric efficiency was the highest. The discharge valve
began to close 2 ms early and closed completely at the critical point when
the plunger transferred from the discharge stroke to the suction stroke,
which helped the suction valve to open on time and improved the pump's oil
absorption capacity. The active opening and closing control of the discharge
valve improved the coordination of the flow distribution to a large extent,
reduced the hysteresis of the suction valve, and ultimately improved the
pump's volumetric efficiency and flow stability. The results of this study
can provide theoretical guidance for the flow control of balanced double-row
axial piston pumps with valve distribution.
In order to solve the problems of nonlinearity, uncertainty and coupling of multi-hydraulic cylinder group platform of a digging-anchor-support robot, as well as the lack of synchronization control accuracy of hydraulic synchronous motors, an improved Automatic Disturbance Rejection Controller-Improved Particle Swarm Optimization (ADRC-IPSO) position synchronization control method is proposed. The mathematical model of a multi-hydraulic cylinder group platform of a digging-anchor-support robot is established, the compression factor is used to replace the inertia weight, and the traditional Particle Swarm Optimization (PSO) algorithm is improved by using the genetic algorithm theory to improve the optimization range and convergence rate of the algorithm, and the parameters of the Active Disturbance Rejection Controller (ADRC) were adjusted online. The simulation results verify the effectiveness of the improved ADRC-IPSO control method. The experimental results show that, compared with the traditional ADRC, ADRC-PSO and PID controller, the improved ADRC-IPSO has better position tracking performance and shorter adjusting time, and its step signal synchronization error is controlled within 5.0 mm, and the adjusting time is less than 2.55 s, indicating that the designed controller has better synchronization control effect.
To improve the control accuracy and robustness of variable frequency pump-controlled motor systems, a mathematical model was built to depict the system pulsation caused by the non-uniform magnetic field of a permanent magnet synchronous motor (PMSM), the harmonic current of an inverter and the structure of a plunger pump. At the same time, system pulsations were mitigated by a novel control algorithm based on sliding mode control (SMC) and harmonic suppression compensation. In addition, the performance of the system was analysed under variable load and speed. Under low-speed and heavy-load conditions, the electromagnetic torque of the PMSM and the outlet pressure of the plunger pump fluctuated greatly by traditional controlling, with maximum deviations of 11.719 N•m and 4.63 MPa, respectively. By coordinating SMC and harmonic suppression compensation, the control algorithm reduced the electromagnetic torque and the outlet pressure of the plunger pump to 45% and 40% of the traditional pump-controlled motor system driven by variable frequency PMSM values, respectively. Furthermore, the pulsation coefficient of the PMSM output speed and the hydraulic motor output speed were both controlled within 0.2%.
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