Lixin Tang

A novel direct torque controlled interior permanent magnet synchronous machine drive with low ripple in flux and torque and fixed switching frequency

A modified direct torque control (DTC) scheme for interior permanent magnet synchronous machine (IPMSM) is investigated in this paper, which features in very low flux and torque ripple and almost fixed switching frequency. It is based on the compensation of the error flux linkage vector by means of space vector modulation. Modeling and experimental results show that the flux and torque ripples are greatly reduced when compared with those of the basic DTC. With the new scheme, very short sampling time is not essential. All the advantages of the basic DTC are still retained. In addition, fixed switching frequency at different operating conditions becomes possible. The field-weakening control of this drive is also studied; an IPM DTC drive with a wider operation range and lower flux and torque ripple has been achieved experimentally.

A novel direct torque control for interior permanent-magnet synchronous machine drive with low ripple in torque and flux-a speed-sensorless approach

A novel direct torque control (DTC) scheme for interior permanent magnet synchronous machine is proposed in this paper, which features low torque and flux ripple and almost fixed switching frequency. The torque and flux ripples have been significantly reduced if compared with those of the basic DTC reported in the literature. A speed estimation scheme is integrated with the proposed DTC scheme.

Problems associated with the direct torque control of an interior permanent-magnet synchronous motor drive and their remedies

This paper investigates problems associated with the implementation of a direct torque control (DTC) strategy for an interior permanent-magnet synchronous motor drive. The DTC technique is increasingly drawing attention because of elimination of current controllers and, hence, their inherent delays, and elimination of the rotor position sensor. The latter advantage perhaps is the main impetus for considering this new approach of torque control. Problems associated with this controller, namely, the offset in the current measurements, the stator resistance variation, and the requirement of initial rotor position are addressed in this paper. Ways of mitigating of these problems are also investigated in this paper. These are evaluated with modeling and experimental studies, results of which are also presented.

A Multiphase, Modular, Bidirectional, Triple-Voltage DC–DC Converter for Hybrid and Fuel Cell Vehicle Power Systems

Electrical power systems in future hybrid and fuel cell vehicles may employ three voltage [14 V, 42 V, and high voltage (HV)] nets. These will be necessary to accommodate existing 14-V loads as well as efficiently handle new heavy loads at the 42-V net and a traction drive on the HV bus. A low-cost DC-DC converter was proposed for connecting the three voltage nets. It minimizes the number of switches and their associated gate driver components by using two half-bridges and a high-frequency transformer. Another salient feature is that the half bridge on the 42-V bus is also utilized to provide the 14-V bus by operating at duty ratios around an atypical value of 1/3. Moreover, it makes use of the parasitic capacitance of the switches and the transformer leakage inductance for soft switching. The use of half bridges makes the topology well suited for interleaved multiphase modular configurations as a means to increase the power level because the capacitor legs can be shared. This paper presents simulation and experimental results on an interleaved two-phase arrangement rated at 4.5 kW. Also discussed are the benefits of operating with an atypical duty ratio on the transformer and a preferred multiphase configuration to minimize capacitor ripple currents.

A Reduced-Part, Triple-Voltage DC–DC Converter for EV/HEV Power Management

Electrical power systems in future hybrid and fuel cell vehicles may consist of three voltage nets: 14 V, 42 V, and high voltage (>200 V) buses. A soft-switched, bidirectional dc-dc converter that uses only four switches was proposed for interconnecting the three nets. This paper presents a reduced-part dc-dc converter, which decreases the converter cost while retaining all the favorable features of the original topology. Experimental data are included to verify a simple power flow control scheme.

A Single Cell Maximum Power Point Tracking Converter without a Current Sensor for High Performance Vehicle Solar Arrays

A maximum power tracker is developed for a single high performance GaAs solar cell to reduce the impact of variations in cell illumination for highly curved arrays as required for vehicle applications. This solution also finds applications in concentrating photovoltaic systems where the incident energy may vary due to optical imperfections. On a curved array, each cell has a directly connected tracker that operates autonomously. An examination of the switching ripple performance of a large number of series connected asynchronous converters is made. The tracker uses a highly efficient 600 mW buck converter operating at 20 kHz with a synchronous rectifier. A dedicated MSP340 processor is capable of the total converter control task. Operating at 1.8 V the controller can be directly powered by the cell. A charge pump is used to develop gate drive voltages for the converter MOSFETs. A maximum power tracking algorithm based on observations of cell voltage and converter duty cycle is demonstrated. The load power may be maximized by maximizing the converter average output voltage. An interior voltage loop is used to control cell voltage and assists in securing a 1.5 mS response to illumination changes

A low-cost, digitally-controlled charger for plug-in hybrid electric vehicles

In this paper, a low-cost onboard charger for plug-in hybrid electric vehicles (HEVs) is presented and verified experimentally. The idea is to utilize the already available main traction and auxiliary motors and associated power electronics systems of an HEV to construct the charger circuit instead of building a standalone charger. Compared to the latter, it enables significant cost, weight, and volume reductions. The topology was verified by modeling and experimental results on a 14 kW prototype.

A new direct torque control strategy for flux and torque ripple reduction for induction motors drive by using space vector modulation

A new DTC control scheme for induction motor is proposed in this paper, which features in low torque ripple and low flux ripple by means of space vector modulation (SVM). Simulation shows the flux and torque ripples are greatly reduced.

An investigation of a modified direct torque control strategy for flux and torque ripple reduction for induction machine drive system with fixed switching frequency

A novel direct torque control (DTC) control scheme for induction motor drives is proposed in this paper, which features low torque ripple, low flux ripple and almost fixed switching frequency. Simulation and preliminary experiment comparisons show the flux and torque ripples are greatly reduced if compared with the basic DTC scheme, while the switching frequency is fixed, all the advantages of the basic DTC are still retained with the new scheme.

In-depth research on direct torque control of permanent magnet synchronous motor

The direct torque control theory has achieved great success in the control of induction motor. However, in the DTC drive system of permanent magnet synchronous machine (PMSM) proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation about the effect of the zero voltage space vectors in the DTC system of PMSM and points out that if using the zero voltage space vectors rationally, not only the DTC system can be driven successfully but torque ripple is reduced and performance of the system is improved. This paper also studies the sensorless technique in the DTC system of PMSM and configures the DTC system of PMSM with sensorless technique including zero voltage space vectors. Numerical simulations and experimental tests have proved the theory correct. In the sensorless condition, the DTC system of PMSM is wide-ranged speed adjusting, and the ratio of speed adjustment is 1:100.