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In the rapidly evolving landscape of electric vehicle (EV) charging, Charging Point Operators (CPOs) play a pivotal role in overseeing the availability of charging infrastructure and managing operational costs. As reported by the International Energy Agency (IEA), the worldwide count of public charging stations surged by 40% in 2023 compared to the previous year, with fast chargers leading the growth. As the number of charging stations increases, CPOs must adopt a software architecture that meets their expanding business requirements. This blog will delve into effective implementation strategies that have proven successful at scale, examining their advantages and disadvantages. Our goal is to equip Chief Information Officers (CIOs), Solutions Architects, and pivotal stakeholders within CPOs with insights as they contemplate various approaches to construct their Charging Station Management System utilizing AWS.

Charging Station Management Systems

A Charging Station Management System (CSMS) is the software interface that links various charging points through different communication protocols, facilitating the operation of charging services while monitoring them in real-time to enhance availability. One critical protocol that CPOs often need to support is the Open Charge Point Protocol (OCPP), which standardizes communication for managing EV charging sessions between the CSMS and the EV Supply Equipment (EVSE).

When deploying a CSMS that incorporates OCPP, CPOs make decisions based on their unique business objectives and positioning within the EV charging value chain. Pure-play CPOs leverage OCPP to augment the range of chargers they can manage and optimize their network operations. Utility companies emphasize OCPP’s smart charging features to better integrate EV charging with grid management. Automotive manufacturers aim to utilize OCPP to enhance plug-and-charge experiences for their customers. Additionally, some manufacturers of charging hardware adopt OCPP as their primary protocol for consistent management across both private and public charging infrastructures.

Regardless of their specific roles, CPOs can capitalize on AWS’s fully managed services when implementing their CSMS, which helps minimize IT expenditures and reduces operational burdens.

The following sections will introduce two implementation patterns based on serverless technology that facilitate the strategy of transferring infrastructure management to AWS’s managed services: the Container-based and API Gateway-based approaches. We will also explore how AWS IoT services can enhance both designs to better align with the evolving requirements of CPOs as their networks expand.

Container-based Charging Station Management Systems

The Container-based pattern focuses on alleviating the complexities of infrastructure management and scaling operations while providing essential components for managing EV chargers, transaction processes, and smart charging capabilities. The custom logic responsible for monitoring and controlling charging sessions can be hosted on AWS Fargate, which simplifies the management of infrastructure for running containerized workloads while allowing CPOs to scale compute and memory resources dynamically based on demand.

One challenge CPOs face is the necessity to implement various charging protocols beyond OCPP, as not all public charging points support it. Additionally, they may need to accommodate multiple OCPP versions concurrently, as charging points within their network might operate on different OCPP versions. To mitigate the effects of protocol changes or additions, a best practice is to decouple protocol-specific logic from the backend of the CSMS. This decoupling can be achieved through the use of connection handlers, which manage all protocol-specific communications and emit protocol-agnostic events to a unified backend logic. In the case of OCPP, these handlers manage WebSocket connections with chargers, oversee OCPP sessions, and handle both incoming and outgoing OCPP messages with the agnostic backend.

The reference architecture for this implementation pattern is illustrated in a diagram showcasing these guidelines. Each functional block utilizes fully managed services to enhance the functional aspects of a CSMS.

The primary benefits of this implementation pattern include:

1. The potential for code reuse when transitioning to container-based solutions;
2. The option for CPOs to choose between an event-driven or service-driven architecture utilizing the same technology.

However, when embarking on a new project using this pattern, the requirement to develop and maintain custom components can delay time to market. For instance, custom code must be created to manage WebSocket connections and establish necessary security measures around them.

API Gateway-based Charging Management System

In the aforementioned pattern, WebSockets are managed by custom logic housed in a container. An enhancement to this method is to assign the management of WebSockets to AWS using Amazon API Gateway. This can lessen the operational overhead associated with maintaining and securing custom logic. Unlike standard WebSockets, the OCPP WebSockets specification necessitates that the WebSocket URLs include the ID of the EV charger in the path (OCPP-j-spec:3.1.1). Currently, this type of path manipulation is not supported by Amazon API Gateway.

To utilize Amazon API Gateway for OCPP WebSockets, CPOs can modify the request, transferring the EV charger ID from the URL to the header. This responsibility can be delegated to Amazon CloudFront, particularly by employing an Amazon CloudFront function. However, this pattern is applicable only to chargers connected to the CSMS via the public internet, as some CPOs prefer to ensure a private connection between the charger and the CSMS, even when encrypted; thus, this pattern may not be suitable in those instances.

Another factor to consider is that chargers will reconnect every 2 hours due to the connection duration limit for Amazon API Gateway WebSockets; while this is not inherently problematic, it must be factored into reporting and alerting configurations. In conclusion, there are numerous advantages to adopting this pattern:

1. WebSocket management is entirely delegated to API Gateway;
2. AWS Lambdas can process OCPP messages;
3. Amazon CloudFront minimizes connection latency by using the nearest point of presence;
4. Any additional custom request manipulation can be handled by the Amazon CloudFront function.

AWS IoT in Charging Station Management Systems

In an EV charging station environment, various devices accompany the charging points, including Local Controllers, Point of Sale systems, and Smart Cameras. These devices necessitate centralized monitoring and control. Moreover, if a CPO also manufactures chargers, they must manage telemetry for each charger and assess their statuses in real-time. Since telemetry streaming for charging points is outside the OCPP’s scope, a separate communication channel becomes essential.

In both situations, the CPO must not only manage charging sessions but also ensure comprehensive oversight of their entire ecosystem. For additional insights on optimizing your hiring process, check out this engaging blog post featuring fun interview questions. Furthermore, for HR professionals navigating compliance with the GDPR in the UK, you can refer to the authoritative insights provided here. Lastly, an excellent resource for understanding these concepts is available on YouTube.