You are asked to design a controller for the sun-seeker system as shown in the b

Question

You are asked to design a controller for the sun-seeker system as shown in the block diagram. The system may be a mounted on a space vehicle so that it will track the sun with high accuracy. The variable theta_r represents the reference angle of the solar ray, denotes the vehicle axis. The objective of the sun-seeker system is to maintain the error between theta_r, theta_o, alpha, near zero. The parameters of the system is as follows: R_F = 10,000 ohm, K_b = 0.0125a V/rad/sec, K_i = 0.0125 N-m/A, R_a = 0.625 ohm, J = 10^-6 kg-m^2, K_s = 0.3 A/rad, k = 1, B = 0, n = 800, L_a = 10^-3 c H The parameters a, b and c are listed according to your name at the end. The desired performance specifications of the system are as follows: The steady-state error due to a unit-ramp input should be less than 1/300 rad/(rad/s). The maximum overshoot of the step response should be less than 5%, or as small as possible. Rise time should be less than 0.004 sec. Settling time should be less than 0.02 sec.

Explanation / Answer

SunSeeker is a controller which keeps solar photovoltaic (PV) arrays facing directly into the sun at all times. It is generally accepted that tracking the sun results in an annual increase in power production of about 30%. The major challenge is dealing with the infinite variety of weather and sky conditions. My design philosophy is to do as much in software as possible and keep the hardware simple. In spite of that, the circuit board is more than twice the size of the Max32, mostly due to the power electronics and surge protection devices. This contest submission is a design platform for developing the software algorithms to produce a high performance array tracker. This project is a third generation prototype, each with a more powerful processor, more complex software, and more data logging. The Max32 will enable me to develop the Ethernet and Internet communication software, and to switch between different tracking algorithms depending on sky conditions. My objective for this contest was to replicate the functionality of the previous assembly language software in C++ using MPIDE. A few enhancements have been added but most of the additional features will be developed over the next two to three years. Prototypes using this chipKIT design will be evaluated on a 1.8kw and a 2.2kw array, both located at 53° north latitude. SunSeeker is a full featured “bells-and-whistles” model that tracks the sun, deals with natural events such as snow, ice, high winds, and eclipses. It identifies sky conditions, compiles statistics, and communicates with computers or file servers. It measures motor current in milliamps, pulse widths in microseconds, PV module temperature, air temperature and the daily minimum and maximum temperatures with the times that those temperatures were first reached. These data collection capabilities enable SunSeeker to be used as a research tool to establish local climate data for PV system design and to facilitate software algorithm development and refinement. Diagnostic software watches the motors to detect any hardware fault that may occur. The H-bridges have internal fault detection, the current drawn by the motors is monitored, and the pulses from the motor drive assemblies are counted to show both movement and position. SunSeeker is designed to operate at any voltage between 12 and 48 volts nominal battery voltage The SunSeeker board contains two switching mode power supplies. The 5 volt supply provides 5 volts to both the Max32 board and the shield. The optional 24 volt power supply is enabled by the processor only when needed to run the motors from a 48 volt power system. The following small sample of code is the heart of tracking the sun using light sensors. This critical code provides the basic tracking function and sets up the conditions that are used for other decision making

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.