| The hydraulic power supply that the quantitative pump was driven by permanent magnet synchronous motor has a simple structure,high reliability,a wide range of speed,low noise,and was easy to realize closed loop control,so which has broad application prospects under the working condition with a high power and a large inertia.Because of the strong coupling characteristic of flow and pressure,the hydraulic power supply has the greater instantaneous volatility of the output flow,the slow response,and was not easy to adjust in case of disturbances,at the same time,which can also appear the problem such as tracking time was too long when the target flow comes to change.The simple PID feedback control was still widely used in the control strategy in now days.The feedback control mainly focused on offsetting correction,eliminating the system response error caused by the disturbance and uncertainty,but the drawback was that the feedback control was not sensitive to the change of element characteristic;The feedforward control was to compensate the particular interference,the control appeared instantly without having to wait until later in case of disturbances,and was more timely and effective than feedback control.This paper studied the theories and the advantages and disadvantages of the feedforward control and feedback control,on the basis of the closed-loop control,it was proposed to realize the constant flow control of the hydraulic power supply under the typical conditions on the composite compensation control strategy.The experiment results showed that when the system existed the load disturbance,load feedforward and feedback composite compensation control can effectively reduce the flow fluctuation,shorten the adjusting time,input feedforward and feedback composite compensation control is greatly improving the system flow tracking performance.This thesis’ s research substance was as follows:(1)This section firstly described the construction and theories of the variable speed hydraulic power source,then calculated the mathematical relationship among the motor speed,system pressure and flow on the basis of the mathematical model of the hydraulic power source.(2)The feedback controller and feedforward controller were designed firstly,the load feedforward and feedback composite compensation control and input feedforward and feedback composite compensation were respectively came true based on the simulation model of hydraulic power supply,the simulation results prove that it was feasibility to the compensate the disturbance under the feedforward control.(3)This section introduced the hardware structure and software program of the variable speed hydraulic supply test bench,and then completed the programming and debugging in the Lab VIEW program environment.(4)This paragraph primarily calculate the initial parameters of the two feedforward controller.In those typical load conditions,flow control experiments of the variable speed hydraulic power were tested.When the target flow input was changing,this paper continue to do the flow track control experiment of of hydraulic power supply.In the next,the author introduced several method of parameter setting of the feedforward controller,then studied the different parameters’ influence of the feedforward controller on the system response on trial,and determined the parameters optimization method of the feedforward controller.This paper finally made simple comparative analysis on the different control strategies.The results proved that the composite compensation control strategy was feasibility and validity on improving load disturbance resistance and flow tracking performance of the variable speed hydraulic power system. |
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