Energy regenerative method for hydraulic system by using PWM control

(utilizing anti-resonance phenomenon)

Abstract

Energy efficiency is low with the control of the hydraulic system using the pressure loss of throttle valves widely used in current construction machinery but if energy regeneration by PWM control switching high pressure source and low pressure source high speed is used, improvement in efficiency can be expected. We proposed response analysis method considering elasticity of oil, influence of cylinder and load on hydraulic system, and improvement method in efficiency for PWM control using anti-resonance. First, we show the possibilities of reducing in efficiency for PWM control due to the influence system resonance with harmonic of switching frequency in straight pipe. Next, we show piping shape that 2 ^nd and 3 ^rd harmonics of the switching frequency of the valve also become anti-resonance and the possibilities of improvement in efficiency for PWM control.