A New PWM Modifying Technique for Reconstructing Three-phase Currents from DC Bus Current

Estimation of multiphase currents using DC bus current and switching state

“…This problem can be approached by using choppers with as many phases as there are strings; in this case, however, maximum power point tracking is required for each chopper, which means more current sensors for each phase, and therefore, higher cost. There are a number of methods to reduce the current sensors and to cut the cost using pulse currents in DC bus, for example, a reconstruction technique using the condition of a zero sum of phase currents in a three‐phase inverter and reconstruction techniques for multiphase choppers …”

“…This problem can be approached by using choppers with as many phases as there are strings; in this case, however, maximum power point tracking is required for each chopper, which means more current sensors for each phase, and therefore, higher cost. There are a number of methods to reduce the current sensors and to cut the cost using pulse currents in DC bus, for example, a reconstruction technique using the condition of a zero sum of phase currents in a three-phase inverter 1 and reconstruction techniques for multiphase choppers. 2,3 This paper proposes, first, a method for phase current reconstruction to estimate phase currents using a matrix of switching states in every leg and common DC bus current, and, second, an extended method in which a part of the said matrix is replaced with photovoltaic string's voltage (PV) voltage and inverter output.…”

Three‐Phase Current Control by Dynamic Reconstruction of Undetected Currents for AC Motor Drives

“…There are a number of reports on motor's stator current control, in which current on DC bus of power converter is detected twice during a control cycle and the detected values are used together with PWM patterns of the power converter to reconstruct three-phase AC current flowing into the motor (referred to as DC-based three-phase reconstruction control method) [1][2][3]. This control method involves some problems such as generation of two different PWM patterns including minimum ON period, two-time DC current detection during ON period (application period of nonzero space voltage vector voltage), current estimation during OFF period (application period of zero space voltage vector voltage) through averaging of ON-period current, and various attempts have been made to improve the method [1][2][3].…”

“…However, there is still no awareness of this notion [1][2][3][4][5][6][7]. In other words, control is based on two-phase conversion of stator current.…”

“…From this viewpoint, in current control of three-phase AC motors, there is no need to reconstruct two undetected phase currents, and direct reconstruction of two-phase current on a two-axis orthogonal reference frame would be sufficient. However, there is still no awareness of this notion [1][2][3][4][5][6][7]. In this paper, we propose three new methods for AC-based two-phase reconstruction control to detect one of three phase currents during OFF period of power converter and directly reconstruct two-phase current on a twoaxis orthogonal reference frame for three-phase AC current control.…”