EV Charging InfrastructureLesson 2 of 5FOUNDATION LESSON
The complete grid-to-vehicle power path
An EV charger is one component in a power path.
- READING TIME
- 14 minutes
- OBJECTIVES
- 3 learning objectives
- SELF-CHECK
- 3 check questions
- INTENDED FOR
- Fleet, property, utility, engineering and charging-operations teams
Educational lesson. Confirm project-specific requirements before application.
01LEARNING OBJECTIVES
After this lesson, you should be able to:
- 01Trace supply, transformation, protection, distribution and charging
- 02Distinguish AC and DC conversion paths
- 03Identify upstream constraints outside the charger
02EXPLANATION
What is physically and operationally happening?
An EV charger is one component in a power path. Energy may pass from the distribution utility through service conductors, transformer, main protection, switchgear, distribution panels, cables and the charge point before reaching the vehicle. Each section has voltage, current, thermal, fault, protection and physical-installation limits.
In AC charging, the vehicle’s onboard charger converts AC to battery DC. In DC fast charging, external power electronics perform the main conversion and supply controlled DC to the vehicle. This difference affects equipment size, site demand, cable handling, cost and charging speed, but neither type removes the need for upstream electrical design.
- 01
Utility service
Available capacity, service voltage and interconnection conditions establish the supply boundary.
kVA + fault duty - 02
Site distribution
Transformer, switchgear, protection and cables deliver power safely.
A + thermal limit - 03
Charger
Controls access, communication and AC delivery or external AC/DC conversion.
kW output - 04
Vehicle
Battery system requests and accepts power within its limits.
State of charge + acceptance
Simplified EV charging single-line diagram
The vehicle receives energy only when every upstream interface can support the operating demand.
04OPTIONAL ENGINEERING DEPTHEngineering reasoning for this learning pathThe same design relationship, checks and evidence apply across every lesson in this path.
- Separate connected load from controlled demand
- Include existing site peak and reserve margin
- Respect vehicle acceptance, arrival and departure
- 01Build the single-line diagram from utility service to connector
- 02Run vehicle-energy and managed-allocation scenarios
- 03Test controller fallback when communications or site metering fails
Site peak exceeds the enforced cap
Control latency, stale data or unmanaged charger
Compare meter, controller and charger timestamps
Vehicles miss departure targets
Allocation ignores energy deadline
Replay arrivals, initial state of charge (SOC) and priorities
- Vehicle schedule and session traces
- Site interval load and capacity study
- Controller logic and fallback test
05WORKED EXAMPLE
Nameplate subtraction is not headroom
A 500 kVA transformer serves an existing site with a recorded 360 kW peak and proposed 120 kW charging demand.
- Nameplate subtraction suggests 140 kVA of spare capacity, which appears to cover 120 kW. Do not accept that conclusion
- If the power factor were 0.9, the 360 kW peak alone would already load the transformer to about 400 kVA, leaving about 100 kVA, less than the 120 kW charging demand
- Validate interval peak, power factor and transformer loading
- Model coincident charging and managed limits
- Review cables, protection, voltage drop and utility conditions
06COMMON FAILURE OR MISCONCEPTION
“If transformer kVA exceeds charger kW, the site has enough capacity.”
Existing load, power factor, thermal condition, phase balance, protection, cables, voltage and utility limits must also be evaluated.
Check what you can explain without looking back.
Choose an answer and report your confidence. The confidence signal is stored only until you submit this page.
What normally sits upstream of chargers?
Where does main AC/DC conversion occur in DC fast charging?
What proves site headroom?
08SOURCE NOTES
Sources for further study.
International references support further study. They do not replace Philippine laws, regulations, utility requirements or project specifications.
- 01State and Local Planning for EV Charging InfrastructureUS Department of Energy Alternative Fuels Data Center
Charging infrastructure planning framework.
Open source ↗ - 02EVCS Provider Obligations and EVCS Requirements, Specifications and InterconnectivityPhilippine Department of Energy
Primary Philippine EVCS implementation context.
Open source ↗