This paper presents a backstepping control method for speed sensorless permanent magnet synchronous motor based on slide model observer. First, a comprehensive dynamical model of the permanent magnet synchronous motor...This paper presents a backstepping control method for speed sensorless permanent magnet synchronous motor based on slide model observer. First, a comprehensive dynamical model of the permanent magnet synchronous motor(PMSM) in d-q frame and its space-state equation are established. The slide model control method is used to estimate the electromotive force of PMSM under static frame, while the position of rotor and its actual speed are estimated by using phase loop lock(PLL) method. Next,using Lyapunov stability theorem, the asymptotical stability condition of the slide model observer is presented. Furthermore, based on the backstepping control theory, the PMSM rotor speed and current tracking backstepping controllers are designed, because such controllers display excellent speed tracking and anti-disturbance performance. Finally, Matlab simulation results show that the slide model observer can not only estimate the rotor position and speed of the PMSM accurately, but also ensure the asymptotical stability of the system and effective adjustment of rotor speed and current.展开更多
A possible alternative to the accelerating universe is proposed, which shows that the diminished brightness of the high red shift Type Ia supernovae can be explained by assuming light travels with reduced speed throug...A possible alternative to the accelerating universe is proposed, which shows that the diminished brightness of the high red shift Type Ia supernovae can be explained by assuming light travels with reduced speed through the dark energy of intergalactic space. It is also shown that support for the?model from baryon acoustic oscillations (BAO) studies can also be accommodated by the model. Two tables are given that compare the model with apparent magnitude differences and length differences between the?universe and the Einstein-de Sitter universe, and they show that the model yields these differences quite accurately. A third table comparing the apparent magnitude difference between?and a universe with is also given. It exhibits poor agreement with the model, and hence the model favors the need for dark energy, albeit without negative pressure. As a new approach to the “why now?” problem, and its apparent challenge to the Copernican principle, it is proposed that dark energy is a condensed form of dark matter caused by expansion cooling, rather than a different substance. A motivation for an alternative to?is presented based on a principle that rules out the cosmological term.展开更多
为进一步提高电动车辆队列行驶的经济性、降低车用动力电池的容量衰减,对某电动货车队列开展了行驶速度规划研究.首先建立了电动货车的单车能耗模型;然后基于此单车能耗模型、固定车头间距的跟车间距策略,以及拟合得到的不同间距下队列...为进一步提高电动车辆队列行驶的经济性、降低车用动力电池的容量衰减,对某电动货车队列开展了行驶速度规划研究.首先建立了电动货车的单车能耗模型;然后基于此单车能耗模型、固定车头间距的跟车间距策略,以及拟合得到的不同间距下队列中各车的气动阻力系数,建立了队列的能耗模型;接着以队列能量消耗最低为优化目标,以行程时间和道路限速为约束,采用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)对队列进行了行驶速度规划;最后仿真研究了规划速度对队列行驶能耗和车辆动力电池容量衰减的影响.研究结果表明:相比于队列按定速巡航与基于坡度加速度的二次规划车速行驶,队列按ADMM规划车速行驶可分别使电动汽车节能9.29%和7.75%,且随着行驶里程的增加,以ADMM规划车速行驶的节能效果愈加明显;车辆队列运行1年后,ADMM规划车速行驶的电池容量衰减相比其他2种规划行驶分别下降9.69%和2.54%,即采用ADMM规划车速行驶可以减缓电池的老化速度,且随着时间的推移,在这3种行驶速度下的电池容量衰减差异越来越大.展开更多
基金supported by National Natural Science Foundation of China(Nos.61104072 and 11271309)
文摘This paper presents a backstepping control method for speed sensorless permanent magnet synchronous motor based on slide model observer. First, a comprehensive dynamical model of the permanent magnet synchronous motor(PMSM) in d-q frame and its space-state equation are established. The slide model control method is used to estimate the electromotive force of PMSM under static frame, while the position of rotor and its actual speed are estimated by using phase loop lock(PLL) method. Next,using Lyapunov stability theorem, the asymptotical stability condition of the slide model observer is presented. Furthermore, based on the backstepping control theory, the PMSM rotor speed and current tracking backstepping controllers are designed, because such controllers display excellent speed tracking and anti-disturbance performance. Finally, Matlab simulation results show that the slide model observer can not only estimate the rotor position and speed of the PMSM accurately, but also ensure the asymptotical stability of the system and effective adjustment of rotor speed and current.
文摘A possible alternative to the accelerating universe is proposed, which shows that the diminished brightness of the high red shift Type Ia supernovae can be explained by assuming light travels with reduced speed through the dark energy of intergalactic space. It is also shown that support for the?model from baryon acoustic oscillations (BAO) studies can also be accommodated by the model. Two tables are given that compare the model with apparent magnitude differences and length differences between the?universe and the Einstein-de Sitter universe, and they show that the model yields these differences quite accurately. A third table comparing the apparent magnitude difference between?and a universe with is also given. It exhibits poor agreement with the model, and hence the model favors the need for dark energy, albeit without negative pressure. As a new approach to the “why now?” problem, and its apparent challenge to the Copernican principle, it is proposed that dark energy is a condensed form of dark matter caused by expansion cooling, rather than a different substance. A motivation for an alternative to?is presented based on a principle that rules out the cosmological term.
文摘为进一步提高电动车辆队列行驶的经济性、降低车用动力电池的容量衰减,对某电动货车队列开展了行驶速度规划研究.首先建立了电动货车的单车能耗模型;然后基于此单车能耗模型、固定车头间距的跟车间距策略,以及拟合得到的不同间距下队列中各车的气动阻力系数,建立了队列的能耗模型;接着以队列能量消耗最低为优化目标,以行程时间和道路限速为约束,采用交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)对队列进行了行驶速度规划;最后仿真研究了规划速度对队列行驶能耗和车辆动力电池容量衰减的影响.研究结果表明:相比于队列按定速巡航与基于坡度加速度的二次规划车速行驶,队列按ADMM规划车速行驶可分别使电动汽车节能9.29%和7.75%,且随着行驶里程的增加,以ADMM规划车速行驶的节能效果愈加明显;车辆队列运行1年后,ADMM规划车速行驶的电池容量衰减相比其他2种规划行驶分别下降9.69%和2.54%,即采用ADMM规划车速行驶可以减缓电池的老化速度,且随着时间的推移,在这3种行驶速度下的电池容量衰减差异越来越大.
