Multilevel dodecagonal space-vector generation for induction motor drives by cascading three-level and two-level inverters

This study presents the hybrid direct torque control (HDTC) method for medium voltage-range induction motor (IM) drive. The control method comprising the torque control by rotor-reference frame quadrature-axis current instead-of conventional DTC and speed control similar as in space-vector-modulation (SVM)-DTC is proposed. Hence the scheme is referred as HDTC. A carrier-based space-vector-modulation controlled five-level diode-clamped multilevel inverter with proposed control scheme is providing promising-step towards performance enhancement of IM drive in respect of torque ripple contents and steady-state performance over wide speed-range. The effectiveness of the proposed control scheme is confirmed by comparison with DTC in matlab-simulink. A prototype is fabricated for three-phase, 3-HP IM. A 32-bit fixed-point DSP-based control algorithm is developed for DTC and the proposed control scheme. Experimental results show qualitative improvement in performance in terms of reduction in torque ripple by 30%, fast dynamic response even at low speed and improvement in steady state characteristics.

Section: Im Modelling and Working Principle Of Dtcmentioning

confidence: 99%

Closed‐loop hybrid direct torque control for medium voltage induction motor drive for performance improvement

Patil¹,

Suryawanshi²,

Renge³

2014

“…Other popular schemes were proposed soon after such as neutral point clamped and flying capacitor (FC). A number of topologies based on these three topologies [2][3][4][5][6][7] have been proposed since then. Open-end induction motor drives make it possible to achieve multilevel operations due to the effective cascading of two inverters [8].…”

Section: Introductionmentioning

confidence: 99%

17‐level inverter with low component count for open‐end induction motor drives

Kshirsagar

Kaarthik

Rahul

et al. 2018

Self Cite

This study presents a 17-level inverter-based induction motor drive for high-resolution multilevel voltage space-vector (SV) generation. The proposed topology consists of a three-level inverter and a seven-level inverter connected to an open-end winding induction machine. The two inverters are powered by two unequal DC supplies, resulting in a low component count, with just 12 switches and three floating capacitors per phase. The voltage SVs applied by the two inverters are chosen to eliminate circulating power flow and prevent DC bus overcharging. In addition, the switching states of both inverters are chosen in order to keep voltages of all floating capacitors well-controlled. Since the capacitors voltages are controlled using the phase currents, additional pre-charging circuitry is not required. A modulation scheme using level-shifted carriers has also been developed, which can be used with both V/f control and d-q control. The high-voltage inverter has a low effective switching frequency and the low-voltage inverter has a high effective switching frequency, reducing the switching loss. The included results of steady-state and transient testing of an experimental prototype demonstrate that the proposed scheme is suited for industrial drives and traction applications.

“…Towards this end, a new three-level cascaded inverter based on 2 two-level inverters was proposed in [22]. In the past few years, many varieties of cascaded inverter topologies are introduced and extensively researched as reported in [23][24][25][26][27][28][29]. Initially, vector control of induction motor using cascaded inverter was reported in [25].…”

Section: Introductionmentioning

confidence: 99%

Five‐level torque controller‐based DTC method for a cascaded three‐level inverter fed induction motor drive

Naganathan¹,

Srinivas²,

Ittamveettil³

2017

Two cascaded two-level inverters can synthesise three-level voltage space vector. For the cascaded three-level inverter controlled induction motor, this study proposes a five-level torque controller (FLTC)-based direct torque control (DTC) method especially for improving steady-state motor torque performance and retaining the high dynamic performance. The proposed FLTC method employs hysteresis controllers, uses look-up tables and ends up with variable switching frequency of the cascaded three-level inverter. Computationally, the envisaged FLTC method is quite comparable to that of the basic DTC method. The FLTC method ensures reduced switching commutations in the inverter switching devices during low speeds of operation and simultaneously achieves reduced dv/dt switching stresses. An inherent drawback of FLTC method at higher speeds of operation is identified, theoretically analysed and a pseudo error-based correction is also suggested in this study to overcome the drawback. The steady-state and transient motor torque performance of the induction motor with the use of the envisaged FLTC-based DTC method is thoroughly analysed, simulated using Matlab/Simulink and then experimentally validated on a laboratory prototype for starting, speed reversal and load change conditions with the use of the cascaded three-level inverter.