{
  "node": {
    "id": "term:coil-economiser",
    "type": "Term",
    "label": "Contactor coil economiser",
    "properties": {
      "id": "coil-economiser",
      "name": "Contactor coil economiser",
      "aka": [
        "coil economizer",
        "economiser",
        "PWM coil drive"
      ],
      "section": "topic-hvsafety",
      "definition": "A circuit that drives a contactor coil hard to close it, then cuts the power to the much lower level needed to hold it shut, often by pulse-width modulation. A typical 500 A contactor holds on under 2 W at 12 V; the saving matters for heat and for the low-voltage supply when several contactors stay closed for hours.",
      "related": [
        "contactor",
        "pulse-width-modulation",
        "auxiliary-battery",
        "battery-disconnect-unit"
      ],
      "url": "https://lemonergy.com/learn/glossary/coil-economiser/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:5101",
      "source": "term:coil-economiser",
      "target": "topic:topic-hvsafety",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:5102",
      "source": "term:coil-economiser",
      "target": "term:contactor",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5103",
      "source": "term:coil-economiser",
      "target": "term:pulse-width-modulation",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5104",
      "source": "term:coil-economiser",
      "target": "term:auxiliary-battery",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:5105",
      "source": "term:coil-economiser",
      "target": "term:battery-disconnect-unit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-hvsafety",
      "type": "Topic",
      "label": "High-voltage and functional safety",
      "properties": {
        "id": "topic-hvsafety",
        "name": "High-voltage and functional safety",
        "lede": "Keeping people safe from the pack’s voltage and keeping its electronics safe when they fail: insulation, switching, fusing and the functional-safety process.",
        "context": "Relate protection to faults, detection and response.",
        "example": "Normal-operation current limits do not demonstrate correct contactor behavior under a welded-contact or sensor fault.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:contactor",
      "type": "Term",
      "label": "Contactor",
      "properties": {
        "id": "contactor",
        "name": "Contactor",
        "section": "topic-hvsafety",
        "definition": "A heavy-duty electrically operated switch that connects the pack to the vehicle or inverter and opens it on fault or shutdown. Packs use at least two, one per pole, plus a pre-charge path to avoid welding them on the first connection.",
        "related": [
          "pre-charge",
          "battery-disconnect-unit",
          "pyrofuse",
          "bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/contactor/",
        "mentions": [
          "inverter"
        ]
      }
    },
    {
      "id": "term:pulse-width-modulation",
      "type": "Term",
      "label": "Pulse-width modulation",
      "properties": {
        "id": "pulse-width-modulation",
        "name": "Pulse-width modulation",
        "abbr": "PWM",
        "section": "topic-data",
        "definition": "Controlling average power by switching fully on and off at a fixed frequency and varying the fraction of each period spent on, the duty ratio. It drives fans, pumps and contactor coils, sets the output of DC/DC converters and inverters, and signals available current on the 1 kHz control pilot of an AC charger.",
        "formula": "V_avg = D·V_supply",
        "related": [
          "mosfet",
          "buck-boost-converter",
          "control-pilot",
          "coil-economiser",
          "inverter"
        ],
        "example": {
          "title": "Convert duty cycle to an ideal average",
          "text": "An ideal switch applying 12 V for 25% of each period produces a 3 V time average at the switching node. The instantaneous signal remains a 0/12 V waveform; a real converter also depends on topology and filtering."
        },
        "url": "https://lemonergy.com/learn/glossary/pulse-width-modulation/",
        "mentions": [
          "charger",
          "contactor"
        ]
      }
    },
    {
      "id": "term:auxiliary-battery",
      "type": "Term",
      "label": "Auxiliary battery",
      "properties": {
        "id": "auxiliary-battery",
        "name": "Auxiliary battery",
        "aka": [
          "12 V battery",
          "low-voltage battery"
        ],
        "section": "topic-pack",
        "definition": "The small 12 V or 48 V battery in an electric vehicle that powers the controllers, lights and locks and wakes the BMS, kept charged from the high-voltage pack through a DC/DC converter. A flat auxiliary battery immobilises the car however full the main pack is.",
        "related": [
          "dc-dc-converter",
          "lead-acid",
          "pack",
          "lin-bus"
        ],
        "url": "https://lemonergy.com/learn/glossary/auxiliary-battery/",
        "mentions": [
          "bms",
          "electric-vehicle"
        ]
      }
    },
    {
      "id": "term:battery-disconnect-unit",
      "type": "Term",
      "label": "Battery disconnect unit",
      "properties": {
        "id": "battery-disconnect-unit",
        "name": "Battery disconnect unit",
        "abbr": "BDU",
        "aka": [
          "battery junction box"
        ],
        "section": "topic-hvsafety",
        "definition": "The box inside the pack that holds the contactors, pre-charge circuit, main fuse or pyrofuse and current sensor, where the pack’s high-voltage connections are made and broken.",
        "related": [
          "contactor",
          "pre-charge",
          "fuse",
          "pyrofuse",
          "current-sensor"
        ],
        "url": "https://lemonergy.com/learn/glossary/battery-disconnect-unit/",
        "mentions": []
      }
    }
  ]
}