变速异步电动机比例恒压泵电液动力源特性研究

Research on the Characteristic of the Electro-hydraulic Power Source Composed of Variable Speed Asynchronous Motor and Proportional Constant Pressure Pump

电液动力源是为液压系统提供动力的单元,其能量效率决定整个系统的能效。针对现有变排量电液比例压力流量复合控制动力源,非工作周期电动机仍以额定转速运转,产生较大能耗;变转速异步电动机驱动定量泵动力源,难以直接控制压力的问题,提出采用变转速交流异步电动机驱动比例恒压泵构造新的电液压力流量复合控制动力源,通过改变斜盘摆角实现无节流损失压力连续控制,改变泵转速实现泵输出流量连续控制。进一步针对异步电动机变转速驱动动态响应慢的问题,提出在主回路增设液压蓄能器,并将其高压油液分别引入液压泵吸油口和出油口,辅助驱动液压泵加速起动和制动的解决方案。研究中,构建了基于上述原理的电液动力源试验测试系统,对其压力控制特性、流量控制特性、压力流量复合控制特性及功率控制特性进行研究,结果表明,随负载压力变化流量控制精度误差不超0.5%,采用蓄能器辅助驱动、辅助制动可使变频电动机起、停时间分别由1 s和1.2 s减小到0.2 s和0.5 s;在保压工况、非工作周期压力卸荷工况、恒压工况,通过降低电动机转速,较恒定电动机转速驱动,降低能耗20%以上。

Electro-hydraulic power source is the power unit of hydraulic system, and its energy efficiency decided the whole hydraulic system efficiency. Currently, the variable displacement electric-hydraulic proportional integrated pressure control flow control power source, whose motor still run at rated speed during the non-working period produce lots of extra energy consumption, and the constant displacement pump power source driven by variable speed asynchronous motor hard to control the output pressure directly. Addressing those shortcomings, it is introduced that a method to construct new type electric-hydraulic proportional integrated pressure control flow control power source through using variable speed asynchronous motor driven proportional constant pressure pump. In this new type power source, no throttling loss pressure continuous control can be realized by changing the swinging angle of inclined plate and the output flow continuous control can be reached by changing the revolution speed of pump. Furthermore, for the problem of slow dynamic response in asynchronous electric variant speed driving, a solution is introduced that aided accelerating the launch and braking of the pump through adding hydraulic accumulator in main circle and bringing its high-pressure oil into the hydraulic pump inlet. Based on these theory, the electro-hydraulic power source test system is build, and its control characteristics of power, pressure, flow, compound of flow and pressure are studied. The results show that with the load pressure changes the flow control error of the test system does not exceed 0.5%, aided accelerating the launch and braking through adding hydraulic accumulator can make launch time and braking time of the variable-frequency motor from 1 s and 1.2 s down to 0.2 s and 0.5 s, and through reduced the motor rotation speed, the test system can reduce the energy consumption beyond 20% than use constant speed motor drive in several working situations such as pressure maintaining, pressure unloading, and constant pressure situation.