feature: high inlet temperature derates the charge current

ccs/hardwareInterface.cpp

@@ -97,7 +97,21 @@ int16_t hardwareInterface_getChargingTargetCurrent(void)
  only important thing is that configured current can drive the load. Let's say 10A is good. */
  Param::SetInt(Param::ChargeCurrent, 10);
  }
- return Param::GetInt(Param::ChargeCurrent);
+ int16_t iOriginalDemand = Param::GetInt(Param::ChargeCurrent); /* the current demand from BMS */
+ int16_t iLimit = Param::GetInt(Param::TempLimitedCurrent); /* the limit due to inlet temperature */
+ int16_t iEVTarget;
+ if (iOriginalDemand>iLimit) {
+ /* We are limiting. Set a spot value "LimitationReason=LimitedDueToHighInletTemperature" so that the
+ user has a chance to understand what happens. */
+ Param::SetInt(Param::LimitationReason, LIMITATIONREASON_INLET_HOT);
+ iEVTarget = iLimit;
+ } else {
+ /* no limitation */
+ Param::SetInt(Param::LimitationReason, LIMITATIONREASON_NONE);
+ iEVTarget = iOriginalDemand;
+ }
+ Param::SetInt(Param::EVTargetCurrent, iEVTarget);
+ return iEVTarget;
 }
 
 uint8_t hardwareInterface_getSoc(void)
@@ -205,14 +219,22 @@ bool hardwareInterface_stopChargeRequested()
  if (pushbutton_isPressed500ms()) {
  stopReason = STOP_REASON_BUTTON;
  Param::SetInt(Param::StopReason, stopReason);
+ addToTrace(MOD_HWIF, "User pressed the stop button.");
  }
  if (!Param::GetBool(Param::enable)) {
  stopReason = STOP_REASON_MISSING_ENABLE;
  Param::SetInt(Param::StopReason, stopReason);
+ addToTrace(MOD_HWIF, "Got enable=false.");
  }
  if ((Param::GetInt(Param::CanWatchdog) >= CAN_TIMEOUT) && (Param::GetInt(Param::DemoControl) != DEMOCONTROL_STANDALONE)) {
  stopReason = STOP_REASON_CAN_TIMEOUT;
  Param::SetInt(Param::StopReason, stopReason);
+ addToTrace(MOD_HWIF, "Timeout of CanWatchdog.");
+ }
+ if (Param::GetFloat(Param::TempLimitedCurrent)<0.1) { /* overheat of the inlet shall stop the session */
+ stopReason = STOP_REASON_INLET_OVERHEAT;
+ Param::SetInt(Param::StopReason, stopReason);
+ addToTrace(MOD_HWIF, "Inlet overheated.");
  }
  return (stopReason!=STOP_REASON_NONE);
 }

ccs/temperatures.cpp

@@ -61,5 +61,34 @@ void temperatures_calculateTemperatures(void) {
  Param::SetFloat(Param::temp3, temp);
  tempMax = MAX(tempMax, temp);
  Param::SetFloat(Param::MaxTemp, tempMax);
+
+ /* Calculate the pin-temperature-dependent derating of the charge current.
+ Goal: Prevent overheating of the inlet and cables.
+ Strategy: Three cases.
+ 1. If the maximum of the three sensors is below the configured threshold,
+ the allowed charge current shall be proportional to the gap.
+ At the moment hardcoded AMPS_PER_KELVIN = 5, this means with a gap of 20K we allow 100A.
+ 2. If the maximum of the three temperature sensors reaches the
+ parametrized MaxAllowedPinTemperature, the allowed charge current
+ shall reach nearly zero (let's say allow just 2A).
+ 3. If nothing helps and the temperature further increases, terminate the
+ session ("emergency stop") */
+ float diffTemp_K = tempMax - Param::GetFloat(Param::MaxAllowedPinTemperature); /* good case is negative diffTemp */
+ float maxAllowedCurrent_A;
+ #define AMPS_PER_KELVIN 5 /* proportional gain: five amperes per Kelvin */
+ #define MINIMUM_SENSEFUL_CURRENT_A 2 /* charging below this amperage makes no sense */
+ if (diffTemp_K > 10) {
+ /* very high temperature (much above the configured limit) --> stop charging completely */
+ maxAllowedCurrent_A = 0; /* this will stop the session, evaluated in hardwareInterface_stopChargeRequested() */
+ } else if (diffTemp_K >= 0) {
+ /* temperature limit is reached. Try to stabilize, using a minimum charging current. */
+ maxAllowedCurrent_A = MINIMUM_SENSEFUL_CURRENT_A;
+ } else {
+ /* normal temperature, linear derating */
+ maxAllowedCurrent_A = -diffTemp_K * AMPS_PER_KELVIN;
+ /* but not below the minimum current: */
+ if (maxAllowedCurrent_A < MINIMUM_SENSEFUL_CURRENT_A) maxAllowedCurrent_A = MINIMUM_SENSEFUL_CURRENT_A;
+ }
+ Param::SetFloat(Param::TempLimitedCurrent, maxAllowedCurrent_A);
 }
 

include/param_prj.h

@@ -43,8 +43,8 @@
 
 #include "myLogging.h"
 
-//Next param id (increase when adding new parameter!): 31
-//Next value Id: 2027
+//Next param id (increase when adding new parameter!): 32
+//Next value Id: 2030
 /* category name unit min max default id */
 #define PARAM_LIST \
  PARAM_ENTRY(CAT_HARDWARE,UdcDivider, "dig/V", 0, 100, 10, 1 ) \
@@ -63,6 +63,7 @@
  PARAM_ENTRY(CAT_CHARGE, MaxPower, "kW", 0, 1000, 100, 17 ) \
  PARAM_ENTRY(CAT_CHARGE, MaxVoltage, "V", 0, 1000, 410, 18 ) \
  PARAM_ENTRY(CAT_CHARGE, MaxCurrent, "A", 0, 500, 125, 19 ) \
+ PARAM_ENTRY(CAT_CHARGE, MaxAllowedPinTemperature, "°C", 0, 120, 70, 31 ) \
  TESTP_ENTRY(CAT_CHARGE, TargetVoltage, "V", 0, 1000, 0, 3 ) \
  TESTP_ENTRY(CAT_CHARGE, ChargeCurrent, "A", 0, 500, 0, 4 ) \
  TESTP_ENTRY(CAT_CHARGE, soc, "%", 0, 100, 0, 5 ) \
@@ -78,6 +79,9 @@
  VALUE_ENTRY(lasterr, errorListString, 2002 ) \
  VALUE_ENTRY(EvseVoltage, "V", 2006 ) \
  VALUE_ENTRY(EvseCurrent, "A", 2010 ) \
+ VALUE_ENTRY(TempLimitedCurrent, "A", 2027 ) \
+ VALUE_ENTRY(EVTargetCurrent, "A", 2029 ) \
+ VALUE_ENTRY(LimitationReason, LIMITATIONREASONS, 2028 ) \
  VALUE_ENTRY(InletVoltage, "V", 2007 ) \
  VALUE_ENTRY(EvseMaxCurrent, "A", 2008 ) \
  VALUE_ENTRY(EvseMaxVoltage, "V", 2009 ) \
@@ -110,12 +114,13 @@
 #define CANSPEEDS "0=125k, 1=250k, 2=500k, 3=800k, 4=1M"
 #define OFFON "0=Off, 1=On"
 #define DEMOCTRL "0=CAN, 234=StandAlone"
-#define STOPREASONS "0=None, 1=Button, 2=MissingEnable, 3=CANTimeout, 4=ChargerShutdown, 5=AccuFull, 6=ChargerEmergency"
+#define STOPREASONS "0=None, 1=Button, 2=MissingEnable, 3=CANTimeout, 4=ChargerShutdown, 5=AccuFull, 6=ChargerEmergency, 7=InletOverheat"
 #define WAKEUP "0=Level, 1=Pulse, 2=LevelOnValidCp, 3=PulseOnValidCp, 4=LevelOnValidPP"
 #define CAT_HARDWARE "Hardware Config"
 #define CAT_CHARGE "Charge parameters"
 #define CAT_COMM "Communication"
 #define CAT_TEST "Testing"
+#define LIMITATIONREASONS "0=None, 1=InletHot"
 
 #define PARAM_ID_SUM_START_OFFSET GITHUB_RUN_NUMBER
 
@@ -154,7 +159,14 @@ enum _stopreasons
  STOP_REASON_CAN_TIMEOUT,
  STOP_REASON_CHARGER_SHUTDOWN,
  STOP_REASON_ACCU_FULL,
- STOP_REASON_CHARGER_EMERGENCY_SHUTDOWN
+ STOP_REASON_CHARGER_EMERGENCY_SHUTDOWN,
+ STOP_REASON_INLET_OVERHEAT
+};
+
+enum _limitationreasons
+{
+ LIMITATIONREASON_NONE,
+ LIMITATIONREASON_INLET_HOT
 };
 
 enum _actuatortest