Modulation and current sensing technique an integrated part for low-cost motor-drive

This paper discusses different ways to reduce the number of current sensors and costs in motor drives by a combination of a proper modulation techniques and a current sensing technique. Both a traditional B6-inverter topology and a component-minimized B4-inverter topology are discussed. Modulation techniques for the two inverters are described and current sensing techniques topologies are shown when only one current sensor is used. In order to ensure full current information in a switching period, small corrections in the duty-cycle generation have to be done and this is also described. Implementation and tests of the techniques are given. It is concluded that a properly chosen modulation technique and a current sensing technique give full information about the current for all operation points as well as protecting the inverter against overload and any other faults.