Multi-level voltage source inverters offer several advantages such as; derivation of a refined output voltage with reduced total harmonic distortion (THD), reduction of voltage ratings of the power semiconductor switching devices and also the reduced electro-magnetic-interference problems etc. In this paper, new carrier-overlapped phase-disposition or sub-harmonic sinusoidal pulse width modulation (CO-PD-SPWM) and also the carrier- overlapped phase-disposition space vector modulation (CO-PD- SVPWM) schemes for a six-level diode-clamped inverter topology are proposed. The principle of the proposed PWM schemes is similar to the conventional PD-PWM with a little deviation from it in the sense that the triangular carriers are all overlapped. The overlapping of the triangular carriers on one hand results in an increased number of switchings, on the other hand this facilitates an improved spectral performance of the output voltage. It is demonstrated through simulation studies that the six-level diode-clamped inverter with the use of CO-PD-SPWM and CO-PD-SVPWM proposed in this paper is capable of generating multiple levels in its output voltage. The advantages of the proposed PWM schemes can be derived to benefit, especially at lower modulation indices of the inverter and hence this aspect of the proposed PWM schemes can be well exploited in high power applications requiring low speeds of operation of the drive. Keywords—Diode clamped inverter, Pulse width modulation, Six level inverter, carrier based PWM. drawbacks, they have their own merits as compared to the others. These circuits are slowly being accepted by the industry in the recent times and are the focus of many researchers now. Several multilevel PWM switching schemes have been proposed in the past and an extensive survey of PWM schemes has also been reported in the literature (7). Improved spectral performance and enhanced DC-bus utilization is also achieved by altogether modifying the sinusoidal modulating signal by either adding appropriate third harmonic component or giving suitable offset voltages (7)-(9). Triangular multi- carriers are uniformly distributed with their phases adjusted to suit the application is reported in the past (10)-(13). Multilevel PWM with modified triangular carriers are also reported in the literature for a multi-level inverter (14)-(15). In this paper, uniform, zero phase shifted, overlapped multi- carrier PWM switching schemes are proposed using the conventional SPWM and also the SVPWM for a six-level diode-clamped inverter circuit topology. It is eloquently demonstrated through simulation studies that the spectral performance of the output voltage using the overlapped carrier PWM proposed in this paper is improved as compared to the use of the conventional PD-PWM especially in the lower modulation range. The main drawback with the use of the proposed PWM is the increased total number of switchings; resulting in an increased switching power loss. However, the improved spectrum of the output voltage with the proposed PWM scheme could offset the increased switching power loss.