The SAE J1772 standard, commonly referred to as the Type 1 connector, is a cornerstone of electric vehicle charging in North America. It supports single-phase AC charging up to 19.2 kW and is widely used
in the United States, Canada, and South Korea. This article delves into the technical specifications and signaling protocols that make SAE J1772 a reliable and efficient standard for electric vehicle charging.
Signaling Protocol and Charging Sequence
The signaling protocol of the SAE J1772 standard is designed to facilitate a seamless charging sequence. It involves the use of a control pilot (CP) and a proximity pilot (PP), which are essential for communication between the vehicle and the charging station. The CP sends a 1 kHz square wave, which is connected back to the protective earth on the vehicle side through a resistor and a diode.
This setup ensures that the live wires of public charging stations remain inactive if the CP-PE (Protective Earth) circuit is open. The vehicle can request specific charging functions by adjusting the resistance between the CP and PE pins. For instance, a resistance of 2.7 kΩ indicates a Mode 3 compatible vehicle, while 880 Ω signals that the vehicle is ready to charge.
Pulse-Width Modulation and Current Limitations
A key feature of the SAE J1772 standard is its use of pulse-width modulation (PWM) to communicate the maximum current available from the charging station. The PWM duty cycle of the 1 kHz CP signal indicates the maximum allowed mains current. For example, a 16% PWM corresponds to a 10 A maximum, while a 90% PWM flags a fast charge option.
This method allows the charging station to describe the maximum current available, ensuring that the vehicle charges safely and efficiently. The SAE defines the ampacity value based on a formula that considers the full cycle of the 1 kHz signal, with specific calculations for continuous and short-term operation.
Robustness and Temperature Range
One of the standout features of the SAE J1772 standard is its robustness and ability to operate across a wide temperature range. The protocol does not require integrated circuits, making it simple yet effective. It can function efficiently in temperatures ranging from -40 °C to +85 °C, ensuring reliability in various environmental conditions.
This robustness is a significant advantage for electric vehicle owners and charging station providers, as it ensures consistent performance regardless of the weather. The simplicity and reliability of the SAE J1772 protocol have contributed to its widespread adoption and continued relevance in the evolving landscape of electric vehicle charging.
