Kimihisa Furukawa

Optimal pulse pattern determination based on Pulse Harmonic Modulation

The design of optimized modulation schemes at low pulse ratios, e.g. Selective Harmonic Elimination (SHE), has been widely studied. However, most previous work has focused on half-wave symmetry pulse patterns. For variable speed and variable torque applications, non-half-wave symmetry SHE modulators depending on the power factor angle still achieve highly efficient inverters in many power factors. Unfortunately, few papers have studied inverter loss on non-half-wave symmetry SHE modulators. Thus, this paper proposes our original SHE method: Pulse Harmonic Modulation (PHM). Its mechanisms are explained in detail. Additionally, different pulse patterns of PHM are quantitatively compared. On the basis of this comparison, several design criteria are proposed for modulators at low pulse ratios.

Solution for SHE-PWM: Non-iterative computation algorithm based on trigonometric harmonic cancellation rule

The harmonic elimination problem for the PWM is formulated as a set of transcendental equations, and a conventional solution to this problem needs iterative computation. This paper presents a noniterative algorithm based on a trigonometric harmonic cancellation rule among pulses. The effectiveness of the algorithm was confirmed by simulations and experiments.

Complete analytical formulae of inverter power loss under infrequent switching condition

Analytical methods of power semiconductor loss in a two-level inverter conventionally assume a sufficient number of switching pulses per electrical fundamental cycle. This paper presents a complete analytical expression of power loss even under an infrequent switching condition. The proposed formulae are demonstrated with HEPWM patterns.

Analysis of RMS current on DC-link capacitor with single-shunt current sensing system

A single-shunt current sensing technique is widely used in industrial system to reduce the cost and mounting space of current sensors in an inverter. In addition, a pulse shift control technique, which maintains the pulse duration and achieves reliable current detection, is used in a single-shunt current sensing system. In this paper, the RMS current on the DC-link capacitor with a pulse shift control technique was analyzed. The analysis results showed that the RMS current on the DC-link capacitor in the single-shunt current sensing system increases over 50% compared to a conventional three-phase current sensing system, in case of a low modulation factor. In addition, the rise in temperature of the DC-link capacitor with or without the single-shunt current sensing was verified by examination. An advanced single-shunt current sensing technique for a redundant inverter system to reduce the RMS current on the DC-link capacitor and the audible noise is also proposed in this paper.