This paper presents a novel dual-mode step-up （boost） DC/DC converter. Pulse-frequency modulation （PFM） is used to improve the efficiency at light load. This converter can operate between pulse-width modulation （...This paper presents a novel dual-mode step-up （boost） DC/DC converter. Pulse-frequency modulation （PFM） is used to improve the efficiency at light load. This converter can operate between pulse-width modulation （PWM） and pulse-frequency modulation. The converter will operate in PFM mode at light load and in PWM mode at heavy load. The maximum conversion efficiency of this converter is 96%. The conversion efficiency is greatly improved when load current is below 100 mA. Additionally, a soft-start circuit and a variable-sawtooth frequency circuit are proposed in this paper. The former is used to avoid the large switching current at the start up of the converter and the latter is utilized to reduce the EMI of the converter.展开更多
Eigenaxis rotation is generally regarded as a near-minimum time strategy for rapid attitude maneuver due to its constitution of the shortest angular path between two orientations. In this paper, the robust control pro...Eigenaxis rotation is generally regarded as a near-minimum time strategy for rapid attitude maneuver due to its constitution of the shortest angular path between two orientations. In this paper, the robust control problem of rigid spacecraft eigenaxis rotation is investigated via time-varying sliding mode control （TVSMC） technique. Both external disturbance and parameter variation are taken into account. Major features of this robust eigenaxis rotation strategy are first demonstrated by a TVSMC algorithm. Global sliding phase is proved as well as the closed-loop system stability. Additionally, the necessary condition for eigenaxis rotation is provided. Subsequently, to suppress the global chattering and improve the control accuracy, a disturbance observer-based time-varying sliding mode control （DOTVSMC） algorithm is presented, where the boundary layer approach is used to soften the chattering and a disturbance observer is designed to attenuate undesired effect. The spacecraft attitude is represented by modified Rodrigues parameter （MRP） for the non-redundancy. Finally, a numerical simulation is employed to illustrate the effectiveness of the proposed strategy, where the pulse-width pulse-frequency （PWPF） technique is utilized to modulate the on-off thrusters.展开更多
基金the National Science Council of Taiwan, China, under Grant No. NSC 95-2221-E-305010.
文摘This paper presents a novel dual-mode step-up （boost） DC/DC converter. Pulse-frequency modulation （PFM） is used to improve the efficiency at light load. This converter can operate between pulse-width modulation （PWM） and pulse-frequency modulation. The converter will operate in PFM mode at light load and in PWM mode at heavy load. The maximum conversion efficiency of this converter is 96%. The conversion efficiency is greatly improved when load current is below 100 mA. Additionally, a soft-start circuit and a variable-sawtooth frequency circuit are proposed in this paper. The former is used to avoid the large switching current at the start up of the converter and the latter is utilized to reduce the EMI of the converter.
基金National Natural Science Foundation of China （108072030） Technology Innovation Program of Beijing Institute of Technology （CX0428）
文摘Eigenaxis rotation is generally regarded as a near-minimum time strategy for rapid attitude maneuver due to its constitution of the shortest angular path between two orientations. In this paper, the robust control problem of rigid spacecraft eigenaxis rotation is investigated via time-varying sliding mode control （TVSMC） technique. Both external disturbance and parameter variation are taken into account. Major features of this robust eigenaxis rotation strategy are first demonstrated by a TVSMC algorithm. Global sliding phase is proved as well as the closed-loop system stability. Additionally, the necessary condition for eigenaxis rotation is provided. Subsequently, to suppress the global chattering and improve the control accuracy, a disturbance observer-based time-varying sliding mode control （DOTVSMC） algorithm is presented, where the boundary layer approach is used to soften the chattering and a disturbance observer is designed to attenuate undesired effect. The spacecraft attitude is represented by modified Rodrigues parameter （MRP） for the non-redundancy. Finally, a numerical simulation is employed to illustrate the effectiveness of the proposed strategy, where the pulse-width pulse-frequency （PWPF） technique is utilized to modulate the on-off thrusters.
