The paper presents a sensorless control approach for a five-phase induction motor drive with third harmonic injection and inverter output filter. In the case of the third harmonic injection being utilised in the control, the physical machine has to be divided into two virtual machines that are controlled separately and independently. The control system structure is presented in conjunction with speed and rotor flux observers that are required for a speed sensorless implementation of the drive. The last section is dedicated to experimental results of the drive system in sensorless operation, and the uninterrupted drive operation for two open-phase faults