EV Charger HVAC Coordination Preventing Transformer Overload
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Solution Overview
Problem
The heavy power draw from electric vehicle charging can overload transformers and lead to their degradation or failure, especially when multiple vehicles charge simultaneously, causing potential electricity outages and exacerbated by variable pricing scenarios.
Innovation Solution
A system that integrates home heating, ventilation, and air conditioning control with electric vehicle charging, using a thermostat to coordinate the operation of air conditioners and electric vehicle chargers, ensuring they do not run simultaneously by adjusting the air conditioner compressor duty cycle and temperature dead band, thereby reducing peak power demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electric vehicle chargers operate at high power draw (30 Amps at 240 Volts), then charging speed and convenience are improved, but transformer overload and power grid infrastructure stress worsen
Solution Approach 1:
The system implements periodic action by scheduling EV charging to occur only during periods when the air conditioner compressor is not operating. The controller monitors compressor status and enables charging during off-periods, creating a periodic charging pattern that avoids peak load conditions and prevents transformer overload while still achieving complete battery charging over time.
2Loss of energy
If multiple electric vehicles charge simultaneously to take advantage of reduced electricity prices, then energy cost is reduced, but power grid load and risk of transformer failure worsen
Solution Approach 1:
The system employs feedback mechanisms where the controller continuously monitors both the air conditioner compressor operating status and the EV battery charge state. This feedback loop enables dynamic scheduling decisions - the controller adjusts charging timing based on real-time compressor operation patterns, ensuring charging occurs during low-load periods when the compressor is off, thereby avoiding transformer stress while capturing off-peak pricing benefits.
Solution Approach 2:
The system applies dynamics by making the charging schedule adaptive rather than fixed. The controller dynamically adjusts charging timing based on varying compressor operation patterns, outdoor temperature conditions, and battery state of charge. This dynamic approach allows the system to flexibly exploit off-peak pricing opportunities while always preventing transformer overload, regardless of changing environmental and operational conditions.
3Power
If the air conditioner compressor duty cycle is reduced to enable EV charging, then power draw management is improved, but household cooling comfort may worsen
Solution Approach 1:
The system applies preliminary action by pre-cooling the household environment before EV charging periods begin. The controller schedules charging to occur during times when the compressor is naturally off, and may advance cooling operations beforehand to establish comfortable temperatures that can be maintained during charging periods without requiring continuous compressor operation, thereby preserving comfort while enabling power management.
Data Source
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AI summary
A system (100) and method (200) include receiving a temperature signal (135) from a temperature sensor, controlling (110) operation of an air conditioner condenser (125), and controlling an electric vehicle charger (115) to operate to charge an electric vehicle battery (130) only when the air conditioner condenser (125) is not running.