Direct Torque Control of Five-leg Dual-PMSM Drive Systems for Fault-tolerant Purposes

Abstract

To enhance the reliability of two-motor drive systems, this paper proposes an improved direct torque control (DTC) scheme (P-DTC) for five-leg dual-PMSM drive systems. First, the topology of a five-leg dual-PMSM drive system is illustrated. To clarify the analysis of the P-DTC, the standard DTC scheme for three-phase drive systems is presented. The operation of a five-leg dual-PMSM drive system is classified into three situations according to the definitions of the switching-vector unions. Compared with the existing DTC scheme (R-DTC), the P-DTC can minimize the replacement of active switching-vectors to zero switching-vectors. When this replacement cannot be avoided, the P-DTC uses a proposed master-slave selection principle to minimize the system error. Comparing with the R-DTC, the P-DTC has lower torque ripples, a wider speed range and a faster torque increasing response. Experiments have been carried out in the coupling and independent modes, and the effectiveness of the P-DTC is verified by the obtained results

Analysis of Model Predictive Current-Controlled Permanent Magnet Synchronous Motor Drives with Inaccurate DC Bus Voltage Measurement

“…According to Equation (17), U n is defined as the (H n ) th optimal SV. Obviously, smaller H n means that U n is better for minimizing the cost function.…”

“…A cost function is designed according to the errors between the reference and predicted values, and the best voltage vector can be selected to minimize the cost function [15]. Compared with conventional direct torque control (DTC) and hysteresis current control (HCC), MPC performs better in multiobjective optimization of complicated drive systems, since a cost function is adopted [16][17][18]. Compared with the conventional proportional integral derivative (PID) control, model predictive current control (MPCC) has faster dynamic response, a lower current ratio, and fewer parameter adjustments, since no PID regulator is adopted [19,20].…”

Direct torque control of two induction motors fed by a Z‐source five‐leg power inverter

“…To reduce the power switches and therefore the cost, both induction motors can be controlled by five power leg inverter. [1][2][3] It is composed of ten (10) bidirectional power switches (Diodes in anti-parallel with transistors), DC-link, and electronic control circuits. In general, the input DC-link voltage of the power inverter requires a DC-DC power converter to obtain adequate voltage, which can lead to a complicated electrical circuit and more cost.…”

“…So, FLI topology can be considered as a degraded version of the classic structure (two 3-leg inverters) when one power leg is in faulty condition. [9][10][11] In terms of control, different control techniques have been widely discussed for the Z-source structure and the FLIs. [12][13][14] Regarding the robustness and the simples implementation, this paper presents an adaptive direct torque control (DTC) of two induction motors fed by a Z-source FLI.…”