This paper presents robustness evaluation of deadbeat-direct torque and flux control (DB-DTFC) of interior permanent-magnet synchronous machine (IPMSM) drives with respect to machine parameter ...variation. For performance comparison, current vector control (CVC), one of the most widely used control methods, is also implemented under identical operating conditions as DB-DTFC. As the metrics to evaluate dynamic performance of DB-DTFC and CVC IPMSM drives, command tracking is used to investigate torque command tracking performance and dynamics stiffness is used to evaluate disturbance rejection performance. In addition, the torque estimation accuracy of DB-DTFC and CVC is investigated with respect to parameter variation. Simulation and experimental results of robustness evaluation of DB-DTFC and CVC are presented in this paper.
This paper presents a design approach for interior permanent-magnet (IPM) machines with variable-flux characteristics using low-coercive-force magnets for improved efficiency and extended operating ...speed range. A flux-intensifying IPM type with is used in the design due to positive Id operation and reduced loaded Iq effects. Design considerations of machine structures and variable-flux machine attributes are discussed. In addition, leakage flux in a rotor is particularly designed to also obtain another flux-varying capability. Evaluation of the designed machine is provided by finite-element analysis simulations and experiments on a proof-of-principle machine. The designed machine shows benefits in increasing efficiency and speed range in a low-torque region when variable magnetization control of the low-coercive-force magnets or the design of the leakage flux proposed in this paper is implemented.
This paper proposes an alternative strategy of finite-control-set model-predictive torque control (MPTC) to reduce the computational burden and the torque ripple and decouple the switching frequency ...from the controller sampling time. An improved discrete space-vector modulation (DSVM) technique is utilized to synthesize a large number of virtual voltage vectors. The deadbeat (DB) technique is used to optimize the voltage vector selection process, avoiding enumerating all the feasible voltage vectors. With this proposed method, only three voltage vectors are tested in each predictive step. Based on the improved DSVM method, the three candidate voltage vectors are calculated by using a novel algebraic way. This new strategy has the benefits of both the MPTC method and the DB method. The effectiveness of the proposed strategy is validated based on a test bench.
Junction temperature sensing for high-bandwidth power MOSFET junction temperature protection is usually achieved on the power converter's high power side, by directly monitoring the power switches ...with additional temperature detectors. This requires special considerations for high voltage, high current, high temperature, and EMI protection. This paper presents a new method applied on the power converter's low power side (MOSFET gate drive) so that junction temperature sensing can be integrated into MOSFET gate drive. For the purpose of demonstrating MOSFET junction temperature sensing, a push-pull gate drive is applied to a switching current divider circuit. The gate drive turn-on current transient waveform is used for MOSFET junction temperature estimation. A "gate drive-MOSFET" switching dynamic model is implemented indicating the mechanisms of MOSFET gate drive output dynamics. Modeling includes gate-drive push-pull output, gate drive output parasitics, power MOSFET intrinsic parameters, PCB parasitics, and load parasitics. LTSpice simulation of this model is studied and compared with experimental results.
High reliability is important in motor driving system for electric vehicle applications. In this paper, a fault-tolerant direct torque control for a five-phase fault-tolerant fractional-slot ...concentrated-winding interior-permanent-magnet (FTFSCW-IPM) motor under the open-circuit condition of a single phase is proposed, in which an analogous three-phase space vector pulse width modulation (SVPWM) control strategy is adopted. The DTC system for the five-phase PM motor based on healthy SVPWM has several advantages of improved currents and low torque and flux ripples. To achieve the fault-tolerant operation of the SVPWM-DTC system, an analogous three-phase SVPWM strategy is proposed. The proposed SVPWM fault-tolerant control scheme is achieved by the division of six sectors and the reconfiguration of six equal nonzero voltage vectors, which is quickly computed and easily realized. In addition, based on a 2-kW FTFSCW-IPM motor prototype, the good performances of the proposed fault-tolerant drive are validated by both simulations and experiments, in which the average torque and low torque ripple during fault can be maintained. Finally, the dynamic performances under healthy and fault-tolerant conditions are measured. The results show that the proposed analogous three-phase SVPWM control can offer good dynamic performance, which is comparable to the healthy SVPWM.
Variable flux permanent magnet synchronous machines (VF-PMSMs) have recently been proposed to reduce driving cycle losses in electric vehicle traction motors via magnetization state (MS) ...manipulation. This paper presents a closed-loop MS control method to enable reliable loss minimization control of VF-PMSMs. The MS is estimated at every sample instant and is used as a feedback for closed-loop control. Under most circumstances, the proposed method maintains precise torque control even during the MS manipulation transient by using a deadbeat-direct torque and flux control (DB-DTFC) framework. The state-of-the-art high-speed flux trajectory generation method for MS manipulation is integrated in the new closed-loop method to allow MS manipulation up to the maximum speed within the inverter voltage limit. The effectiveness of the proposed methods, in terms of driving cycle loss reduction capability and its thermal impact, is evaluated experimentally by emulating the road load using the dynamometer load motor.
Although 60-W wireless power transfer (WPT) was demonstrated in 2007, still there is no equivalent circuit model for a submeter air-gap, hundreds of watts, and high-efficiency wireless system. A ...design-oriented circuit model is needed for this technology to evolve. This paper proposes an equivalent circuit model for the wireless system and analyzes the system based on the proposed model. The proposed model and its analysis are validated by means of finite-element analysis (FEA) and experimental results. Furthermore, as a viable solution for high-power (multikilowatt) applications, losses in the WPT system are investigated in the following section. Because of the high operating frequency (in megahertz), skin and proximity effects were shown to be dominant. A new spatial layout of a coil is proposed that significantly reduces losses caused by skin and proximity effects. With the new spatial layout, i.e., the surface spiral layout, the efficiency and size of WPT system can be improved significantly in high-power applications. The proposed coil design is evaluated by means of FEA.
The switching transient properties from the switching power semiconductor gate side are sensitive to the device's junction temperature (<inline-formula><tex-math ...notation="LaTeX">T_{j}</tex-math></inline-formula>). Real-time <inline-formula><tex-math notation="LaTeX">T_{j}</tex-math></inline-formula> sensing methods based on gate drive switching transient properties have been investigated on silicon MOSFET and silicon IGBT, with a conventional push-pull-type gate drive, under fixed dc-bus voltage. In this paper, this method is applied to silicon-carbide (SiC) MOSFET. The <inline-formula><tex-math notation="LaTeX">T_{j}</tex-math></inline-formula> sensing methods are evaluated with different types of gate drive topologies. By implementing the SiC MOSFETs into an H-bridge inverter, the effect of dc-bus voltage for the <inline-formula><tex-math notation="LaTeX">T_{j}</tex-math></inline-formula> sensing method is investigated. Different "gate drive−semiconductor" dynamic models are built, including gate drive output power stage, gate drive parasitics, SiC MOSFET intrinsic parameters, and PCB parasitics. Experimental results are compared with circuit LTSpice model simulation. The device vertical temperature contours are evaluated. Suitable circuitry for <inline-formula><tex-math notation="LaTeX">T_{j}</tex-math></inline-formula> sensitivity extraction is provided.
Deadbeat-direct torque and flux control (DB-DTFC) is a direct torque control method that provides the fastest possible torque control, low ripple, easily integrated dynamic loss minimization control, ...and one control law that uses the inherent volt-second source properties of power electronics to enable operation over all operating conditions, including voltage limits. DB-DTFC is a model-based discrete time controller that relies on precise machine parameter, flux, and torque estimation to provide fast dynamic torque control. In this paper, a new method for high-frequency injection (HFI)-based self- and mutual incremental inductance estimation is proposed and evaluated in both simulations and experiments. In this new method, the estimated incremental inductances including cross-coupling inductance due to cross saturation are curve fitted offline and then used to calculate the apparent inductances. With the apparent inductances, the stator resistance and permanent-magnet flux linkage are estimated using recursive least squares method online. The stator flux linkage observer using the identified machine parameters yields improved stator flux linkage estimates that enable precise torque calculation. Experimental evaluation of the HFI-based flux estimates on torque estimation and control accuracy is performed at an interior permanent-magnet synchronous machine drive test bench with a torque transducer mounted.
This paper proposes a control strategy of finite-control-set model predictive torque control (FCS-MPTC) with a deadbeat (DB) solution for permanent-magnet synchronous motor drives. By using a DB ...solution, the process of selection of the best switching vector is optimized. The predicted DB voltage sector consisting of the desired voltage vector (VV) avoids the complete enumeration for testing all feasible VVs, which relieves the big calculation effort of the traditional FCS-MPTC method. The proposed system is experimentally carried out both in the steady state and in the transient state.
