Model-based phase tracking and angle-synchronous disturbance compensation for a direct-drive mud-pulse telemetry actuator

High-speed mud-pulse telemetry requires a rotary actuator that can follow prescribed phase trajectories under structured hydraulic and magnetic load torque. This paper presents a direct-drive rotary siren pulser controlled by a nested vector-control architecture augmented with a virtual-model reference channel and an angle-synchronous feedforward compensation block. The prototype uses a three-blade siren, a permanent-magnet synchronous motor (PMSM), a 4096-count encoder, and an automatically calibrated disturbance map over the full rotor angle. In the steady-state quadrature phase-shift keying (QPSK) 20 Hz carrier/20 baud regime, the virtual-model channel reduced peak absolute angular error from 120 counts (10.55 deg) to 32 counts (2.81 deg) and reduced root-mean-square (RMS) error from 45.0 to 9.0 counts. With the parking disturbance engaged, the angle-synchronous compensation reduced peak/RMS error from 340/168.1 to 44/9.73 counts at 1 Hz and from 181/66.3 to 67/23.8 counts at 20 Hz. In a one-well dataset, the proposed system demodulated in differential smooth quadrature phase-shift keying (DSQPSK) mode retained 84.3% of received bits above a 90% confidence threshold, compared with 23.3% for the comparator QPSK system. The results show that deterministic angle-dependent load torque can be compensated directly in the control architecture, improving high-speed phase tracking and receive quality without a mechanical transmission stage.