EHPV Technology Advanced Control Techniques for ElectroHydraulic Flow

® EHPV Technology Advanced Control Techniques for Electro-Hydraulic Flow Control Valve by Patrick Opdenbosch Abstract Controller Accumulator Hi-press. filter The current trend in construction machinery is to use electrically controlled valves (solenoid valves) instead of manually operated hydraulic valves. One of the benefits is that these solenoid valves need not be located in the operator cab. In addition, the employment of these electrically driven valves facilitates computerized control of various machine functions. The Electro-Hydraulic Poppet Valves (EHPV™), a kind of solenoid valves, are used herein for flow control in hydraulic machinery. The flow control through the valve is achieved by changing the valve restriction coefficient via a poppet type orifice with pressure compensation via a Pulse-Width-Modulated current. This project will explore new algorithms and applications via theory, simulation and operation of the valve in Hardware In the Loop (HIL) simulation facility currently under construction Flow meter Pressure transmitters B A M M EHPV Pressure relief valve Main Pump Crossover relief valve Lo-press. filter Load Tank Proportional-Integral Controller with anti-windup Hydraulic Circuit Employed for Motor Speed Control PWM Driver, Single EHPV® Model, and Gear Motor Model Feedback Control Scheme Closed-loop Response’s Duty Cycle Profile Closed-loop Response Electromagnetic Rsol Pilot Pin Vsol isol Solenoid Mechanical gapmax Hydraulic C 1 C 2 Pilot Head Chamber A C C 2 C 1 [3] Actuator Displacement ® Control Using EHPV Wheatstone Bridge Configuration [1] Reservoir Tank [2] Pump [3] EHPV™ supply [4] Check valve [5] EHPV™ return [6] Actuator [6 a] Lower cavity [6 b] Upper cavity [6 c] Piston [7] Controller Hydraulic Oil Supply Hydraulic Oil Return PWM Signal Pressure Signal C A B A single EHPV ® is used to control the speed of a gear motor. The speed is set as a sine wave with zero phase, 0. 64 Hz, 500 RPM amplitude, and 2000 RPM offset. Piston mass Control Pressure Chamber Main Poppet Pressure Compensation Spring Pilot pin mass Pressure compensating spring Main poppet mass Piston Connection Ports Armature mass Bias spring Armature Control Pressure Chamber Motor Speed Control with a Single EHPV® Modulating spring B EHPV Mathematical Model Schematic Non-Linear Model The non-linear mathematical model developed for the EHPV® is based on the interaction among the Mechanical, Hydraulic, and Electromagnetic subsystems. It also includes a model for a Pulse-Width-Modulation driver, which regulates and modulates the input current to the EHPV®. 4 are used to control the displacement of a passive actuator. The controller receives a desire performance criterion (not shown) along with pressure data from the upstream and downstream portions of each valve. The controller in turn sends PWM signals to the EHPV®’sare used in an adaptive and trainable algorithm to manipulate [6 c] [6 b] [5] [7] [4] [2] [3] [5] [1] Step Response A simulated step response (10 -90% capacity) was obtained for a single EHPV®. This response is for constant pressure drop across the valve, and varying (by PWM action) the input current. Sponsors: HUSCO International and FPMC Center Email: gte 608 g@prism. gatech. edu website: http: //www. imdl. gatech. edu/opdenbosch Fall 2003 [1] Wheatstone Arrangement to Control Actuator Displacement (UNDER DEVELOPMENT) EHPV® Modeled 10 -90% Step Response [6 a] [6] EHPV®‘s EHPV Cross-Section View [4] Advisors: • Dr. Nader Sadegh, Dr. Wayne Book