The Krupp-Koppers (K-K) extractive distillation method with N-formylmorpholine (NFM) as the solvent is one of the most important processes for catalytic hydrogen refining of rude benzene. To increase the capacity and selectivity of the solvent and decrease the ratio of solvent to feed in this process, ethylene glycol (EG), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP) were introduced as the cosolvent with NFM. The relative volatility of cyclohexane to benzene (R) at a certain R stf (liquid-phase ratio of solvent to feed) was considered as a criterion of the performance of cosolvent. The vapor-liquid equilibrium (VLE) data for benzene + NFM, EG + NFM, benzene + cyclohexane + NFM, benzene + cyclohexane + NFM + EG, benzene + cyclohexane + NFM + DMF, and benzene + cyclohexane + NFM + NMP were measured at atmospheric pressure. VLE data of benzene + NFM, EG + NFM, benzene + cyclohexane + NFM, and benzene + cyclohexane + NFM + EG were calculated by the nonrandom twoliquid (NRTL) model. The average temperature deviations of benzene + cyclohexane + NFM and benzene + cyclohexane + NFM + EG systems are (1.40 and 3.19) K, respectively. The average deviations of the vapor-phase mole fraction of benzene are 0.030 and 0.066, respectively.
A simple and novel design method for resolverto-digital conversion is presented. The proposed method takes advantage of the auxiliary sinusoidal signals generated by addition and subtraction operations of the demodulated signals of resolver's outputs. A pseudo-linear signal is obtained through appropriate mathematical manipulation between the auxiliary sinusoidal signals and the demodulated ones. A calibration strategy is then provided to achieve the highest possible precision. It is shown that the error between the calibrated angular and the true angular is less than 0.00235 • over 0 • ∼ 360 • . The proposed method enables determination of the angular position without utilizing a look-up table (LUT) or additional reference signals. Furthermore, the presented strategy is implemented using FPGA.Finally, our method is tested on a tracking radar antenna servo system where resolvers are installed on it. Several experiments under different conditions are performed to further verify the effectiveness of the proposed method.Index Terms-Resolver-to-digital conversion (RDC), look-up table (LUT), field-programmable gate array (FPGA).
0278-0046 (c)
Electric vehicles are considered as one of the most popular way to decrease the consumption of petroleum resources and reduce environmental pollutions. Motor control system is one of the most important part of electric vehicles. It includes power supply module, IGBT driver, digital signal processing (DSP) controller, protection adjustment module, and resolver to digital convertor. To implement the control strategies on motor control system, a lot of practical aspects need to be taken into accounts. It includes setup of the initial excitation current, consistency of current between motor and program code, over-modulation, field weakening control, current protection, and so on. In this paper, an induction motor control system for electric vehicles is developed based on DSP. The control strategy is based on the field-oriented control (FOC) and space vector pulse width modulation (SVPWM). Speed calculation, over-modulation, field weakening control, PI controller, and fault diagnosis are also applied in this DSP algorithm. As an industry product running on a real electric bus with a 100kW induction motor, communication with vehicle control unit (VCU) by CAN bus, control system safety and PC software designed for lab experiments are also discussed. This paper focused on how to develop the advanced motor control system for electric vehicles for industrial application. The steady-state and transient performances of this motor control system are analyzed by both test-bench experiments and road experiments. Its performance is satisfactory when applied to the real electric vehicle.
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