The six-phase permanent magnet synchronous motor (PMSM) exhibits significant advantages in underwater propulsion applications due to its high output power and reliability. This paper investigates the application of a six-phase PMSM-based redundant system for underwater propulsion. It introduces an integrated redundancy control scheme, with a focused analysis on the control strategies for communication redundancy, drive redundancy, and motor winding redundancy. The impact of randomized switching frequency PWM modulation on the harmonic power spectrum is discussed. Simulations validate the effectiveness of lead angle flux-weakening control in achieving speed and torque enhancement under heavy loads. Additionally, methods to mitigate inter-winding current imbalance caused by manufacturing parameter variations are explored. In conclusion, an outlook on potential research directions is presented.