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CubeSats are a class of nano-satellites primarily built using commercial off-the-shelf components for electronics and structure, aimed at space and atmospheric research. The Electrical Power System (EPS) of the CubeSat is responsible for extracting power from solar panels to provide regulated power to all the satellite subsystems and using the surplus power to charge the satellite’s batteries in order to sustain the satellite’s operations during eclipses. The battery charger integrated circuit, with the photovoltaic (PV) input, should be able to charge the batteries of the satellite while extracting maximum power from the solar panels. Since there are multiple solar panels for a given satellite, the chosen charging scheme should be able to operate in parallel from different PV inputs and common battery output terminals. This manuscript describes parallel operation of a PV battery charger, which is capable of interfacing PV panels of different incident solar radiation with a common battery. Experimental results are presented to validate the circuit operation.

In this paper we introduce a novel benchmark problem to study the control of magnetic needle with two degrees of rotational freedom in a uniform magnetic field. Magnetic needle in an external magnetic field has stable and unstable equilibrium points, which depends on it's orientation. Our idea is to control the magnetic needle near it's unstable equilibrium point. Dynamics of the system is derived using Lagrangian energy based technique. The nonlinear system dynamics are linearized at unstable equilibrium point and the controllers are designed for this linear system, and the same controllers are applied to nonlinear system. The difference in tracking performance for linear and nonlinear system is observed using PD, PID, lead, lead lag compensators and state feedback, feed forward integral controller and H ∞ , quantitative feedback controllers. Further, control effort for all the above controllers are computed.

In this paper, we study the detailed modeling of the magnetic needle in a nonuniform external magnetic field. Center of the magnetic needle is pivoted so that it is allowed to rotate about one axis. A magnetic needle placed in an external magnetic field has two equilibrium points, one is stable and the other is unstable. A passivity based non-linear controller is designed for nonuniform external magnetic field system, and its tracking performance is studied at the unstable equilibrium point. The transient and steady state performance are compared between different control strategies in terms of settling time, peak overshoot, the steady state amplitude of oscillations. Further, the control strategies designed for uniform external magnetic field system are applied to the nonuniform external magnetic field system, to study the change in performance when compared to the designed controller for nonuniform external magnetic field system. The conclusions are made based on the simulation results.

In this paper, we study the design of energy based controller to control the magnetic needle at desired location. The magnetic needle is allowed rotate about one axis, in the external magnetic field by pivoting its center. Due to attraction and repulsive forces between the magnetic needle and external magnetic field, the magnetic needle will have two equilibrium points, one is stable and the other is an unstable equilibrium point. The magnetic needle dynamics are derived by considering uniform and non-uniform external magnetic field. The controller is designed to control the magnetic needle at the desired location. Different control strategies are derived based on the Lyapunov's function. Different control strategies steady state and transient performance are compared based on the simulation results.

In this paper we consider the control of inverted magnetic needle with one degree of freedom in an uniform external magnetic field. A magnetic needle placed in an external magnetic field will have two equilibrium points, one of which is stable and, the other unstable. The tracking control performance of the magnetic needle in the unstable equilibrium point is studied in this paper. Design and tracking performance of lead, lead lag compensators, feed forward integral controller, H∞ and quantitative feedback controller are studied for linear and nonlinear system. The effect of system parameter uncertainty and output disturbance on the system tracking response for all the above controllers is also discussed.