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Started implementing real charge control

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Everything untested so far…
This commit is contained in:
Thomas Kolb 2021-06-07 22:45:17 +02:00
parent 0982f8d7c9
commit 6b070bbf86
4 changed files with 463 additions and 32 deletions
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307
src/charge_control.c Normal file
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#include <stdbool.h>
#include <fxp.h>
#include "power_switch.h"
#include "measurement.h"
#include "charge_pump.h"
#include "config.h"
#include "charge_control.h"
static enum ChargeState charge_state;
static enum DischargeState discharge_state;
static bool charge_state_entered;
static bool discharge_state_entered;
static uint64_t charge_state_entered_timestamp;
static uint64_t discharge_state_entered_timestamp;
static fxp_t u_bat_regulation_corridor;
static fxp_t u_bat_initial_full;
static fxp_t u_bat_initial_low;
static fxp_t u_bat_float_full;
static fxp_t u_bat_float_low;
static fxp_t min_charge_pump_excess_voltage;
static fxp_t u_bat_load_on;
static fxp_t u_bat_load_off;
static fxp_t load_current_limit;
static fxp_t internal_temperature_limit;
static fxp_t internal_temperature_recovery;
static fxp_t sleep_solar_current;
static fxp_t sleep_solar_excess_voltage;
static void control_solar_switch(fxp_t u_bat, fxp_t corridor_high, fxp_t corridor_low)
{
if(u_bat >= corridor_high) {
power_switch_solar_off();
} else if(u_bat <= corridor_low) {
power_switch_solar_on();
}
}
void charge_control_init(void)
{
charge_state = CHARGE_WAIT_CHARGEPUMP;
discharge_state = DISCHARGE_WAIT_CHARGEPUMP;
charge_state_entered = true;
discharge_state_entered = true;
/* calculate thresholds */
u_bat_regulation_corridor = fxp_div(FXP_FROM_INT(U_BAT_REGULATION_CORRIDOR),
FXP_FROM_INT(1000));
u_bat_initial_full = fxp_div(FXP_FROM_INT(U_BAT_INITAL_FULL), FXP_FROM_INT(1000));
u_bat_initial_low = fxp_sub(u_bat_initial_full, u_bat_regulation_corridor);
u_bat_float_full = fxp_div(FXP_FROM_INT(U_BAT_FLOAT_FULL), FXP_FROM_INT(1000));
u_bat_float_low = fxp_sub(u_bat_float_full, u_bat_regulation_corridor);
min_charge_pump_excess_voltage = fxp_div(FXP_FROM_INT(MIN_CHARGE_PUMP_EXCESS_VOLTAGE),
FXP_FROM_INT(1000));
u_bat_load_on = fxp_div(FXP_FROM_INT(U_BAT_LOAD_ON), FXP_FROM_INT(1000));
u_bat_load_off = fxp_div(FXP_FROM_INT(U_BAT_LOAD_OFF), FXP_FROM_INT(1000));
load_current_limit = fxp_div(FXP_FROM_INT(LOAD_CURRENT_LIMIT_MA), FXP_FROM_INT(1000));
internal_temperature_limit = fxp_div(FXP_FROM_INT(INTERNAL_TEMPERATURE_LIMIT), FXP_FROM_INT(10));
internal_temperature_recovery = fxp_div(FXP_FROM_INT(INTERNAL_TEMPERATURE_RECOVERY), FXP_FROM_INT(10));
sleep_solar_current = fxp_div(FXP_FROM_INT(SLEEP_SOLAR_CURRENT), FXP_FROM_INT(1000));
sleep_solar_excess_voltage = fxp_div(FXP_FROM_INT(SLEEP_SOLAR_EXCESS_VOLTAGE), FXP_FROM_INT(1000));
}
void charge_control_update(uint64_t uptime_ms, struct MeasurementResult *meas)
{
/* state change tracking for efficient transistions. */
enum ChargeState last_charge_state = charge_state;
enum DischargeState last_discharge_state = discharge_state;
if(charge_state_entered) {
charge_state_entered_timestamp = uptime_ms;
}
if(discharge_state_entered) {
discharge_state_entered_timestamp = uptime_ms;
}
uint64_t charge_time_in_state = uptime_ms - charge_state_entered_timestamp;
uint64_t discharge_time_in_state = uptime_ms - discharge_state_entered_timestamp;
/* calculate charge pump excess voltage above battery voltage. */
fxp_t charge_pump_voltage_delta = fxp_sub(meas->u_sw, meas->u_bat);
/* generalized charge pump control */
if(charge_state_entered || discharge_state_entered) {
if(charge_state == CHARGE_WAIT_CHARGEPUMP
|| discharge_state == DISCHARGE_WAIT_CHARGEPUMP) {
// either charge or discharge control is waiting for the charge
// pump, so power it up!
charge_pump_start();
} else if((charge_state == CHARGE_SLEEP)
&& (discharge_state == DISCHARGE_VOLTAGE_LOW)) {
// no power from the solar panel and the battery voltage is too
// low, so both switches are off and we can safely stop the charge
// pump
charge_pump_stop();
}
}
/* Charging FSM */
switch(charge_state) {
case CHARGE_WAIT_CHARGEPUMP:
// force the solar switch off until the charge pump voltage reaches a safe level.
if(charge_state_entered) {
power_switch_solar_off();
}
if(charge_pump_voltage_delta > min_charge_pump_excess_voltage) {
charge_state = CHARGE_INITIAL;
}
break;
case CHARGE_INITIAL:
control_solar_switch(meas->u_bat, u_bat_initial_full, u_bat_initial_low);
// temperature limit
if(meas->temperature > internal_temperature_limit) {
charge_state = CHARGE_HIGH_TEMPERATURE;
}
// time limit for initial charging
if(charge_time_in_state > INITIAL_CHARGE_HOLD_TIME) {
charge_state = CHARGE_TRANSITION;
}
// low-current limit (go to sleep at night)
if(meas->i_solar < sleep_solar_current) {
charge_state = CHARGE_SLEEP;
}
break;
case CHARGE_TRANSITION:
// FIXME: dynamically adjust thresholds
control_solar_switch(meas->u_bat, u_bat_float_full, u_bat_float_low);
// temperature limit
if(meas->temperature > internal_temperature_limit) {
charge_state = CHARGE_HIGH_TEMPERATURE;
}
// time limit for transition to float charging
if(charge_time_in_state > INITIAL_TO_FLOAT_TRANSITION_TIME) {
charge_state = CHARGE_FLOAT;
}
// low-current limit (go to sleep at night)
if(meas->i_solar < sleep_solar_current) {
charge_state = CHARGE_SLEEP;
}
break;
case CHARGE_FLOAT:
control_solar_switch(meas->u_bat, u_bat_float_full, u_bat_float_low);
// temperature limit
if(meas->temperature > internal_temperature_limit) {
charge_state = CHARGE_HIGH_TEMPERATURE;
}
// low-current limit (go to sleep at night)
if(meas->i_solar < sleep_solar_current) {
charge_state = CHARGE_SLEEP;
}
break;
case CHARGE_SLEEP:
if(charge_state_entered) {
power_switch_solar_off();
}
{
fxp_t solar_excess_voltage = fxp_sub(meas->u_solar, meas->u_bat);
if(solar_excess_voltage > sleep_solar_excess_voltage) {
// resume operation
charge_state = CHARGE_WAIT_CHARGEPUMP;
}
}
break;
case CHARGE_HIGH_TEMPERATURE:
if(charge_state_entered) {
power_switch_solar_off();
}
if(meas->temperature < internal_temperature_recovery) {
charge_state = CHARGE_WAIT_CHARGEPUMP;
}
break;
default:
// unknown state
break;
}
/* Load control FSM */
switch(discharge_state) {
case DISCHARGE_WAIT_CHARGEPUMP:
// force the load off until the charge pump voltage reaches a safe level.
if(discharge_state_entered) {
power_switch_load_off();
}
if(charge_pump_voltage_delta > min_charge_pump_excess_voltage) {
discharge_state = DISCHARGE_VOLTAGE_LOW;
}
break;
case DISCHARGE_OK:
// Battery voltage is in a safe range, so keep the load switched on
if(discharge_state_entered) {
power_switch_load_on();
}
if(meas->i_load > load_current_limit) {
// TODO: maybe only check this 10 ms after load is switched on
// to allow for inrush current?
discharge_state = DISCHARGE_OVERCURRENT;
}
if(meas->u_bat < u_bat_load_off) {
discharge_state = DISCHARGE_VOLTAGE_LOW;
}
break;
case DISCHARGE_VOLTAGE_LOW:
// Battery voltage is too low, so keep the load switched off
if(discharge_state_entered) {
power_switch_load_off();
}
// Can only switch on again after a specific amount of time has passed
if((meas->u_bat > u_bat_load_on)
&& (discharge_time_in_state > LOAD_ON_DELAY)) {
discharge_state = DISCHARGE_OK;
}
break;
case DISCHARGE_OVERCURRENT:
// Battery voltage is too low, so keep the load switched off
if(discharge_state_entered) {
power_switch_load_off();
}
// no way out except reset
break;
default:
// unknown state
break;
}
charge_state_entered = charge_state != last_charge_state;
discharge_state_entered = discharge_state != last_discharge_state;
}
bool charge_control_is_charge_blocked(void)
{
switch(charge_state) {
case CHARGE_HIGH_TEMPERATURE:
case CHARGE_WAIT_CHARGEPUMP:
return true;
default:
return false;
}
}
bool charge_control_is_discharge_blocked(void)
{
switch(discharge_state) {
case DISCHARGE_OVERCURRENT:
case DISCHARGE_WAIT_CHARGEPUMP:
return true;
default:
return false;
}
}

40
src/charge_control.h Normal file
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@ -0,0 +1,40 @@
#ifndef CHARGE_CONTROL_H
#define CHARGE_CONTROL_H
#include <stdint.h>
#include <stdbool.h>
// forward declarations
struct MeasurementResult;
enum ChargeState
{
CHARGE_WAIT_CHARGEPUMP,
CHARGE_INITIAL,
CHARGE_TRANSITION,
CHARGE_FLOAT,
CHARGE_SLEEP,
CHARGE_HIGH_TEMPERATURE
};
enum DischargeState
{
DISCHARGE_WAIT_CHARGEPUMP,
DISCHARGE_OK,
DISCHARGE_VOLTAGE_LOW,
DISCHARGE_OVERCURRENT
};
// Error flags
#define LOAD_OVERCURRENT (1 << 0)
#define CHARGE_PUMP_ERROR (1 << 1)
#define OVER_TEMPERATURE (1 << 2)
void charge_control_init(void);
void charge_control_update(uint64_t uptime_ms, struct MeasurementResult *meas);
bool charge_control_is_charge_blocked(void);
bool charge_control_is_discharge_blocked(void);
#endif // CHARGE_CONTROL_H

55
src/config.h Normal file
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@ -0,0 +1,55 @@
#ifndef CONFIG_H
#define CONFIG_H
/* Thresholds for charging control */
/* Battery regulation corridor width (in mV). */
#define U_BAT_REGULATION_CORRIDOR 100
/* Initial charge battery voltage threshold (in mV). */
#define U_BAT_INITAL_FULL 28800 // stop charging if battery voltage reaches this threshold
/* Transition to floating voltage levels after this time (in ms). */
#define INITIAL_CHARGE_HOLD_TIME 3600000
/* Duration of the transistion from initial charging to float (in ms). */
#define INITIAL_TO_FLOAT_TRANSITION_TIME 600000
/* Float charge battery voltage threshold (in mV). */
#define U_BAT_FLOAT_FULL 27600 // stop charging if battery voltage reaches this threshold
/* Minimum voltage difference to U_bat that the solar panels must produce
* before charging is resumed after it was switched off (in mV). */
#define SLEEP_SOLAR_EXCESS_VOLTAGE 1000
/* Minimum charge current required before charging is stopped to save power at
* the charge pump (in mA). */
#define SLEEP_SOLAR_CURRENT 5
/* Maximum allowed microcontroller temperature (in units of 0.1 °C). If this
* temperature is exceeded, charging is stopped. The load is kept on. Do not
* set this too high as the heat has to propagate from the power MOSFETs. */
#define INTERNAL_TEMPERATURE_LIMIT 500
/* Resume operation below this temperature (in units of 0.1 °C). */
#define INTERNAL_TEMPERATURE_RECOVERY 450
/* Thresholds for load control */
/* Voltage above which the load is turned on (in mV). */
#define U_BAT_LOAD_ON 27000
/* Voltage below which the load is turned off (in mV). */
#define U_BAT_LOAD_OFF 24000
/* Current at which the overload protection triggers (in mA). */
#define LOAD_CURRENT_LIMIT_MA 10000
/* Minimum voltage that the charge pump must produce above U_bat before any
* power FET is switched on (in mV). */
#define MIN_CHARGE_PUMP_EXCESS_VOLTAGE 10000
/* The minimum time the load must be off before it can be switched on again (in ms). */
#define LOAD_ON_DELAY 10000
#endif // CONFIG_H

93
src/main.c
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@ -17,6 +17,7 @@
#include "led_chplex.h"
#include "rs485.h"
#include "charge_pump.h"
#include "charge_control.h"
#include "power_switch.h"
#include "measurement.h"
@ -98,6 +99,61 @@ static bool ledtest(uint64_t timebase_ms)
}
static void update_leds(uint64_t uptime_ms, struct MeasurementResult *meas_data)
{
static fxp_t charge_in_mAs = 0;
static fxp_t charge_out_mAs = 0;
static uint64_t charge_pulse_until = 0;
static uint64_t discharge_pulse_until = 0;
charge_in_mAs = fxp_add(charge_in_mAs, meas_data->i_solar);
charge_out_mAs = fxp_add(charge_out_mAs, meas_data->i_load);
if(charge_in_mAs > FXP_FROM_INT(1000)) {
led_chplex_on(LED_CHPLEX_IDX_CHARGE_PULSE);
charge_pulse_until = uptime_ms + 12;
charge_in_mAs = fxp_sub(charge_in_mAs, FXP_FROM_INT(1000));
} else if(uptime_ms > charge_pulse_until) {
led_chplex_off(LED_CHPLEX_IDX_CHARGE_PULSE);
}
if(charge_out_mAs > FXP_FROM_INT(1000)) {
led_chplex_on(LED_CHPLEX_IDX_DISCHARGE_PULSE);
discharge_pulse_until = uptime_ms + 12;
charge_out_mAs = fxp_sub(charge_out_mAs, FXP_FROM_INT(1000));
} else if(uptime_ms > discharge_pulse_until) {
led_chplex_off(LED_CHPLEX_IDX_DISCHARGE_PULSE);
}
if(charge_control_is_charge_blocked()) {
led_chplex_on(LED_CHPLEX_IDX_ERR_TEMP);
} else {
led_chplex_off(LED_CHPLEX_IDX_ERR_TEMP);
}
if(charge_control_is_discharge_blocked()) {
led_chplex_on(LED_CHPLEX_IDX_ERR_LOAD);
} else {
led_chplex_off(LED_CHPLEX_IDX_ERR_LOAD);
}
if(power_switch_solar_status()) {
led_chplex_on(LED_CHPLEX_IDX_SOLAR_ON);
} else {
led_chplex_off(LED_CHPLEX_IDX_SOLAR_ON);
}
if(power_switch_load_status()) {
led_chplex_on(LED_CHPLEX_IDX_LOAD_ON);
} else {
led_chplex_off(LED_CHPLEX_IDX_LOAD_ON);
}
}
static void report_status(struct MeasurementResult *meas_data)
{
char number[FXP_STR_MAXLEN];
@ -163,7 +219,6 @@ int main(void)
led_chplex_periodic();
} else if(!startup_done) {
charge_pump_start();
power_switch_load_on(); // FIXME: just for testing!
startup_done = true;
} else {
@ -173,46 +228,20 @@ int main(void)
// completion. This is a good place for tasks that are not critical in
// latency, such as updating the LEDs, sending the state over RS485 etc.
if(timebase_ms % 500 == 0) {
led_chplex_toggle(LED_CHPLEX_IDX_DISCHARGE_PULSE);
}
// FIXME: just for testing
if(timebase_ms % 10000 == 0) {
switchtest++;
if(switchtest & 0x01) {
power_switch_solar_on();
led_chplex_on(LED_CHPLEX_IDX_SOLAR_ON);
} else {
power_switch_solar_off();
led_chplex_off(LED_CHPLEX_IDX_SOLAR_ON);
}
if(switchtest & 0x02) {
power_switch_load_on();
led_chplex_on(LED_CHPLEX_IDX_LOAD_ON);
} else {
power_switch_load_off();
led_chplex_off(LED_CHPLEX_IDX_LOAD_ON);
}
}
update_leds(timebase_ms, &meas_data);
led_chplex_periodic();
// Send the status data from the last cycle.
if(timebase_ms % 1000 == 0) {
if(timebase_ms % 500 == 0) {
report_status(&meas_data);
}
measurement_wait_for_completion();
if(timebase_ms % 1000 == 100) {
measurement_finalize(&meas_data);
}
// Check the protections directly after the measurement finishes. This
// ensures fast reaction time.
// TODO: check_protections(&meas_data);
// Update the charge controller immediately after the measurement.
// This ensures fast reaction time to overcurrent/overvoltage.
charge_control_update(timebase_ms, &meas_data);
}
timebase_ms++;