Solar MPPT Power System

/*
 * plant.h -- a physical model of the panel, the LM5175 converter and the
 * battery, good enough to exercise charge_control.c on a host PC.
 *
 * This is not a circuit simulator. It exists to answer control questions:
 * does the state machine reach the right states, does the arbitrator ever
 * let a current exceed its limit, does P&O converge on the maximum power
 * point and stay there. For that, what matters is that the plant reproduces
 * the one relationship the controller actually steers by -- charge current
 * as a function of commanded battery-bus voltage, with a genuine maximum in
 * the middle of the range, which is what makes P&O a non-trivial problem.
 */
#ifndef PLANT_H
#define PLANT_H

#include <stdint.h>

typedef struct {
    /* panel */
    float voc;              /* open-circuit voltage at present irradiance */
    float isc;              /* short-circuit current at present irradiance */

    /* battery */
    float batt_ocv;         /* open-circuit (rest) voltage, rises with charge */
    float batt_rint;        /* internal resistance, ohms */
    float batt_capacity_ah;

    /* converter */
    float efficiency;

    /* externally applied load current drawn from the battery bus */
    float load_a;

    /* power-good inputs the controller reads */
    uint8_t mppt_pgood;
    uint8_t bias_pgood;

    /* --- outputs, updated by plant_step() --- */
    float vbus;             /* actual battery-bus voltage achieved */
    float ichg;             /* actual current into the battery */
    float iin;              /* actual panel current */
    float ppanel;           /* actual power drawn from the panel */
    float panel_v;          /* panel operating voltage */
} plant_t;

void  plant_init(plant_t *p);

/* Panel power available at a given operating voltage. */
float plant_panel_power_at(const plant_t *p, float v);

/* The panel's true maximum power point, found by sweep -- the value P&O is
 * supposed to discover on its own, used only by the tests to grade it. */
float plant_panel_pmax(const plant_t *p, float *v_at_max);

/* Advance the plant by dt_ms with the converter commanded to vbatt_cmd. */
void  plant_step(plant_t *p, float vbatt_cmd, uint32_t dt_ms);

#endif /* PLANT_H */