implement over current protection

firmware/open_evse/CHANGELOG

@@ -9,6 +9,9 @@ Change Log
 	-> don't allow PP to set current capacity higher than EEPROM
 - PP code cleanup
 - don't allow SetCurrentCapacity() to go above PP value
+- implement over current protection. if OVERCURRENT_THRESHOLD is set,
+	then if EV draws >= OVERCURRENT_THRESHOLD amps for >=
+	OVERCURRENT_TIMEOUT ms -> hard fault
 
 20180417 SCL
 - fix compile errors when no GFI and ADVPWR. Must also undef UL_COMPLIANT,

firmware/open_evse/J1772EvseController.cpp

@@ -914,7 +914,10 @@ void J1772EVSEController::Init()
 
   m_AmmeterReading = 0;
   m_ChargingCurrent = 0;
-  //  m_LastAmmeterReadMs = 0;
+#ifdef OVERCURRENT_THRESHOLD
+  m_OverCurrentStartMs = 0;
+#endif //OVERCURRENT_THRESHOLD
+
 #endif // AMMETER
 
 #ifdef VOLTMETER
@@ -1607,6 +1610,27 @@ if (TempChkEnabled()) {
     m_ElapsedChargeTimePrev = m_ElapsedChargeTime;
     m_ElapsedChargeTime = now() - m_ChargeOnTime;
 
+#ifdef OVERCURRENT_THRESHOLD
+    //testing    m_ChargingCurrent = (m_CurrentCapacity+OVERCURRENT_THRESHOLD+12)*1000L;
+    if (m_ChargingCurrent >= ((m_CurrentCapacity+OVERCURRENT_THRESHOLD)*1000L)) {
+      if (m_OverCurrentStartMs) { // already in overcurrent state
+	if ((millis()-m_OverCurrentStartMs) >= OVERCURRENT_TIMEOUT) {
+	  //
+	  // overcurrent for too long. stop charging and hard fault
+	  //
+	  // spin until EV is disconnected
+	  m_EvseState = EVSE_STATE_OVER_CURRENT;
+	  HardFault();
+
+	  m_OverCurrentStartMs = 0; // clear overcurrent
+	}
+      }
+      else {
+	m_OverCurrentStartMs = millis();
+      }
+    }
+#endif // OVERCURRENT_THRESHOLD    
+
 #ifdef TEMPERATURE_MONITORING
   if(TempChkEnabled()) {
     if (m_ElapsedChargeTime != m_ElapsedChargeTimePrev) {

firmware/open_evse/J1772EvseController.h

@@ -32,7 +32,8 @@
 #define EVSE_STATE_STUCK_RELAY 0x08 //stuck relay
 #define EVSE_STATE_GFI_TEST_FAILED 0x09 // GFI self-test failure
 #define EVSE_STATE_OVER_TEMPERATURE 0x0A // over temperature error shutdown
-#define EVSE_FAULT_STATE_END EVSE_STATE_OVER_TEMPERATURE
+#define EVSE_STATE_OVER_CURRENT 0x0B // over current error shutdown
+#define EVSE_FAULT_STATE_END EVSE_STATE_OVER_CURRENT
 
 #define EVSE_STATE_SLEEPING 0xfe // waiting for timer
 #define EVSE_STATE_DISABLED 0xff // disabled
@@ -172,6 +173,9 @@ class J1772EVSEController {
 #ifdef MENNEKES_LOCK
   MennekesLock m_MennekesLock;
 #endif // MENNEKES_LOCK
+#ifdef OVERCURRENT_THRESHOLD
+  unsigned long m_OverCurrentStartMs;
+#endif // OVERCURRENT_THRESHOLD
 
 #ifdef ADVPWR
 // power states for doPost() (active low)

firmware/open_evse/Language_default.h

@@ -78,4 +78,5 @@
 #define STR_LEVEL_2					   "Level 2 (240V)"  
 #define STR_L1						     "L1"  
 #define STR_L2						     "L2"  
+#define STR_OVER_CURRENT "OVERCURRENT"
 //#endif

firmware/open_evse/open_evse.h

@@ -167,6 +167,17 @@ extern AutoCurrentCapacityController g_ACCController;
 // not yet #define TEMPERATURE_MONITORING_NY
 
 #ifdef AMMETER
+
+// if OVERCURRENT_THRESHOLD is defined, then EVSE will hard fault in
+// the event that the EV is pulling more current than it's allowed to
+// declare overcurrent when charging amps > pilot amps + OVERCURRENT_THRESHOLD
+#define OVERCURRENT_THRESHOLD 5 // A
+// go to error state overcurrent by OVERCURRENT_THRESHOLD amps
+// for OVERCURRENT_TIMEOUT ms
+#define OVERCURRENT_TIMEOUT 5000UL // ms
+
+
+
 // kWh Recording feature depends upon #AMMETER support
 // comment out KWH_RECORDING to have the elapsed time and time of day displayed on the second line of the LCD
 #define KWH_RECORDING

firmware/open_evse/open_evse.ino

@@ -686,6 +686,19 @@ void OnboardDisplay::Update(int8_t updmode)
 #endif
       break;
 #endif //TEMPERATURE_MONITORING        
+#ifdef OVERCURRENT_THRESHOLD
+    case EVSE_STATE_OVER_CURRENT:
+      SetGreenLed(0);
+      SetRedLed(1);
+#ifdef LCD16X2 //Adafruit RGB LCD
+      LcdSetBacklightColor(RED);
+      LcdPrint_P(0,g_psSvcReq);
+      strcpy_P(g_sTmp,g_psOverCurrent);
+      sprintf(g_sTmp+strlen(g_sTmp)," %dA",(int)(g_EvseController.GetChargingCurrent()/1000-g_EvseController.GetCurrentCapacity()));
+      LcdPrint(1,g_sTmp);
+#endif
+      break;
+#endif // OVERCURRENT_THRESHOLD   
     case EVSE_STATE_NO_GROUND:
       SetGreenLed(0);
       SetRedLed(1);

firmware/open_evse/strings.cpp

@@ -118,3 +118,7 @@ const char *g_sMaxCurrentFmt = STRF_MAX_CURRENT;
 const char g_psSetDateTime[] PROGMEM = STR_SET_DATE_TIME;
 const char *g_DelayMenuItems[] = STR_YESNO_SETSTART_SETSTOP;
 #endif // DELAYTIMER_MENU
+
+#ifdef OVERCURRENT_THRESHOLD
+const char g_psOverCurrent[] PROGMEM = STR_OVER_CURRENT;
+#endif // OVERCURRENT_THRESHOLD

firmware/open_evse/strings.h

@@ -120,3 +120,7 @@ extern const char *g_sMaxCurrentFmt;
 extern const char g_psSetDateTime[] PROGMEM;
 extern const char *g_DelayMenuItems[];
 #endif // DELAYTIMER_MENU
+
+#ifdef OVERCURRENT_THRESHOLD
+extern const char g_psOverCurrent[] PROGMEM;
+#endif // OVERCURRENT_THRESHOLD