Electric Vehicle Supply Equipment (EVSE) regulates the transfer of electricity from a source to an electric vehicle (EV), ensuring safe and efficient battery recharging. Although EVSE is the official technical term, it is also known as an EV charger, charging station, charge point, or charging dock. Charging an EV, whether at a public station or a home-mounted unit, can be similar to charging a smartphone but on a much larger scale.
However, delving deeper reveals a more intricate world of EVSE. There’s a plethora of options, each catering to different requirements, forms, and charging levels: Level 1 (120 volts AC), Level 2 (240 volts AC), and DC Fast Charger (480 volts DC and higher).
How does Electric Vehicle Supply Equipment (EVSE) Work?
While often referred to as a charging station, the EVSE doesn’t charge the EV’s battery directly. Instead, the actual charging occurs inside the vehicle. When connected, the EVSE checks for a secure connection and the vehicle’s readiness. If everything checks out, power flows to the vehicle through the cable. Any connection issues lead to an immediate power cut-off for safety.
The method of charging depends on the use of AC or DC. EV batteries essentially use DC power. When using an AC charger, the primary power charges an internal system in the EV which then converts the AC to DC for the battery.
With DC charging, this conversion is skipped, allowing for faster charging, typically seen with advanced level 3 chargers. However, these DC chargers tend to be costlier. Once charged, the vehicle can be unplugged and driven.
Also Read: What are EV Charging Levels?
What are the Components of EVSE?
The components of EVSE are:
1. Housing or Enclosure: Protective casings for EVSE vary, from a simple box-on-a-cable for homes to wall-mounted and pedestal designs for broader applications like workplaces, hotels, and public chargers. Some public stations use tower designs.
Essential components include:
- Main Relay– Controls power flow to the vehicle by turning it on or off.
- Control Module– This module is in charge of the relay and the charging session.
- Power Supply– This provides power to the control module and relay.
- Electrical Circuits– These are present for each charging socket or fixed cable attachment.
- Optional User Interface- Such as an LCD screen.
Firmware is a specialized microcode or software that is integrated within read-only EVSE hardware such as controllers or network cards. It enables operations, communications, and functionalities like charge initiation, safety, and battery status updates. Additionally, firmware updates can introduce new features and improve compatibility.
4. Network Connectivity:
Some EV chargers have network connections via WiFi or cellular networks for communication with apps or cloud systems. This feature offers user control and potential cost savings through time-of-use tariffs.
5. Power Supply:
Home EV chargers use standard 120-volt (Level 1) or 240-volt outlets (Level 2). When direct connections to home or business power lines, this works seamlessly. But for public areas, a dedicated electrical system is vital for reliable grid connectivity.
6. Ports and Cables:
Ports on EVSE are for cable attachments. These flexible cables transfer electric currents and can be fixed to the housing.
Located at cable ends, connectors vary based on charger specs and region. EVSE levels and connectors are as follows:
- Level 1- 120-volt AC, uses no connectors or J1772, up to 20 hours for charge, mainly for home use.
- Level 2- 208-240-volt AC, connectors like J1772, CCS, NACS, CHAdeMO, charges in 5-6 hours, versatile in application.
- Level 3- 400-900-volt DC, connectors such as CCS, NACS, and CHAdeMO, known as Direct Current Fast Charger (DCFC), charge in 15 to 45 minutes, primarily for public use.
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