Two-channel shaft synchronization of a rotary vane engine with constrained electric drives

Abstract

Electromagnetic synchronization of rotary vane engine shafts requires coordinating the vane motion with a variable gas load within the limited capabilities of electric drives. The aim of the study is to develop a coupled computer model of shaft synchronization that accounts for mechanical and thermodynamic processes and the electrical limitations of permanent magnet synchronous drives with field-oriented control. The objectives are to formulate coupled equations of the shafts, chambers and drives, to develop a two-channel synchronization algorithm, to implement a reproducible simulator and to determine how drive parameters, chamber scale and gas leakage affect the stability of motion. The model combines two-shaft dynamics, chamber gas processes with heat release and seal leakage, and drives with current and voltage limits, winding inductance and resistance, proportional-integral current control, back electromotive force compensation, anti-windup protection, digital control and finite current-loop bandwidth. It is checked against analytical solutions, energy balances, the ideal Otto cycle and independent implementations of individual blocks. A two-channel algorithm is proposed that adaptively controls the relative motion of the shafts and corrects the position of the vane bisector relative to the housing; its local stability conditions are established. The influence of the physical torque reversal and gas leakage on the operability of synchronization is determined. The simulator allows electric machines, controller settings and engine geometry to be assessed before an experimental test bench is built. In the studied regimes the algorithm keeps a small steady-state bisector offset and restores synchronized motion after a misfire and changes in heat release and load. This is also confirmed by numerical tests with random initial conditions and varied electrical parameters of the studied drives. For the selected drive, the admissible chamber volume with combustion is bounded by the current from above and by leakage from below. Synchronization stability is determined by the torque reserve and the rate of torque build-up; current and voltage margins are necessary but not sufficient. Without combustion, the drive suffices for all studied volumes, so this mode suits initial bench tests. The quantitative results are model predictions requiring experimental confirmation.