A Method for Band Width Determination of Multiband Hysteresis Modulation, for any Given Switching Frequency Maximum of Inverter A. Raddanipour P. Naderi M.R.Alizadeh Pahlavani Electrical Engineering Department of Islamic Azad University, Borujerd Branch, Iran. Shahid Rajaee Teacher Training University, Tehran, Iran Malek-E-Ashtar University of Technology (MUT), Shabanlo St., Lavizan, Tehran, Iran. ali.raddani@gmail.com p.naderi@srttu.edu mr.alizadeh@iust.ac.ir Abstract Now day, the inveters used in many electrical applications such as UPS, motors driver, compensators, and so on. One of the best topologies of inverters is the Cascaded H-bridge. In this paper the Cascaded H-bridge seven-level inverter topology and six-band hysteresis modulation for distribution static compensator (DSTATCOM) are briefly studied. Comparing with the Tsypkin's method, a Sliding-Mode controller for a DSTATCOM has been considered as a new method for bandwidth determination of a multiband hysteresis modulation, which has been used for desired maximum switching frequency of the inverter. Moreover, controlling of the dc-link voltage, a series of simulation results for a seven-level inverter used in DSTATCOM, has been shows the effectiveness of proposed method for system operation for unbalanced and variable loads. Keywords: Cascaded H-bridge inverter, Distribution static compensator (DSTATCOM), Multiband hysteresis modulation, Sliding-mode control, Tsypkin's method. 1-Introduction The first multilevel inverters were introduced around 30 years ago. Regarding to lower switching losses, higher performance and also electromagnetic compatibility of mentioned inverters these can used for various high voltage systems via the optimal tuning of their performance. Recently, various multilevel topologies have been introduced and the most important are considered by diode clamping, flying capacitor and also the H-bridge cascaded multilevel inverters. However, due to modular implementation of the cascaded structure, this has more usage as the inverter. On the other hands, a well known modulation method used in the inverters called hysteresis modulation. In this method the parameters design is most important for band width determination which is relative to switching losses with the specified given limit. Now, in this paper, a new method for the bandwidth calculating of a multiband hysteresis modulation has been introduced. In this way, the inverter used in a distribution static compensator (DSTATCOM) is considered as a voltage source inverter (VSI) which the desired voltage should be produced by the hysteresis modulation via the Sliding-Mode controller. In the second part, a seven-level cascaded inverter has been illustrated and the model of DSTATCOM with sliding mode controller has been illustrated in the third part. Moreover, a novel method for hysteresis bandwidth determination has been studied in forth. The fifth section