From Wiring Harnesses to Neural Networks: The present study explores the evolution and trends of electrical architecture in the context of the electrification of construction machinery.
The objective of global carbon neutrality has prompted a rapid advancement in electrification in the field of construction machinery. This transformation extends far beyond the mere replacement of diesel engines with batteries and motors; it fundamentally reshapes the electrical/electronic architecture (EEA) of construction machinery. This article provides a comprehensive analysis of the evolution of electric construction machinery EEA, encompassing a detailed examination of its driving forces, a comparative analysis with passenger vehicle development, an analysis of the differences between it and fuel systems, and an in-depth analysis of its core challenges and future directions.
I. Driving Forces: The necessity of transformation.
The evolution of construction machinery EEA is not a theoretical concept, but rather an inevitable outcome driven by multiple factors.
1.1 Robust Environmental Policy and Regulatory Framework
On a global scale, there has been a significant tightening of emission regulations (e.g., EU Stage V, China National IV) and carbon reduction targets, resulting in a substantial increase in compliance costs for conventional diesel-powered machinery. Electrification is identified as the most efficacious solution, with an efficient EEA serving as its cornerstone.
1.2 The Total Cost of Ownership (TCO) Model: A Case for Electric Construction Equipment
A preliminary investigation into the financial implications of electric construction equipment reveals several advantages in terms of Total Cost of Ownership (TCO). While the initial financial outlay for the acquisition of such equipment is higher than for diesel-powered counterparts, the operational expenses are significantly lower, with electricity being a more cost-effective option. Furthermore, the maintenance expenses are substantially reduced, thus eliminating the need for oil changes, filter replacements, and other such expenditures. The Advanced EEA optimises energy management, thereby enhancing efficiency and reducing the investment payback period.
1.3 Essential Requirements for the Enhancement of Intelligence and Productivity
Intelligent scenarios, such as automated construction, remote operation and fleet coordination, demand robust capabilities in data acquisition, processing and decision-making. It is evident that traditional distributed architectures are incapable of fulfilling the requirements for high-bandwidth, low-latency communication. Consequently, this renders centralised EEAs the inevitable choice.
1.4 Compulsory Requirements for Functional Safety and Cybersecurity
The implementation of high-voltage systems engenders novel safety hazards, thereby necessitating the adherence to the stipulated functional safety (ISO 26262) and cybersecurity (ISO 21434) standards. New EEA designs must incorporate safety principles from the outset.
2. The following conclusions were reached: The Evolutionary Path of Passenger Vehicle EEA
The evolution of EEA in construction machinery draws heavily from the development experience of passenger vehicles, following a trajectory that is highly similar yet slightly distinct.
2.1 Distributed Architecture (Era 1.0): Each function is controlled by an independent ECU, interconnected via a CAN/LIN bus. The high system coupling present in the design rendered the upgrade process challenging.
2.2 Domain-Centralised Architecture (Era 2.0): The ECUs are consolidated by functional domains (for example, powertrain, body, cockpit, autonomous driving), and are managed by a Domain Controller (DCU). The decoupling of hardware and software components paved the way for the implementation of over-the-air (OTA) updates.
2.3 The Centralized + Zone Control Architecture (Era 3.0) is a system that utilises a combination of both centralized and zone control methodologies. A small number of high-performance central computing units (HPC) function as the core, thereby handling all computationally intensive tasks. Multiple zone controllers (ZCU) are deployed peripherally and are responsible for power distribution, data gateway functions, and I/O interfaces. This forms the hardware foundation for the "software-defined vehicle."
The evolution of construction machinery has been comparatively static, with the mainstream currently transitioning from Era 1.0 to Era 2.0. However, the harsh operating conditions experienced by such vehicles demand far higher reliability and real-time performance than is required of passenger vehicles.
3. Disruptive Transformation: A thoroughgoing comparison of the relative merits of EEA in fuel-powered and electric construction machinery is presented herewith.
The EEA in fuel-powered and electric construction machinery exhibits fundamental differences, with the latter evolving from an auxiliary subsystem into the core nervous and muscular systems of the entire machine.
3.1 Evolution in Architectural Philosophy: A transition from an auxiliary role to a core position.
Fuel-Powered Machinery: The EEA functions as an auxiliary system, with hydraulics and mechanical transmission at its core. The electrical systems are responsible for the initiation of the engine, the illumination of the vehicle, and the provision of fundamental controls. This system is referred to as a "12/24V low-voltage central architecture."
Electric Machinery: The EEA is the core power and control system, responsible for energy distribution, conversion, and management. This configuration can be designated a "high-voltage and low-voltage parallel domain control architecture."
3.2 Energy and Power Transformation: The transition from chemical to electrical energy
Fuel-Powered Machinery: The energy that propels the vehicle is derived from diesel fuel, which is then converted by the engine into mechanical energy. A small amount of electrical energy is also generated during this process, which is produced by the generator.
Electric Machinery: The energy supply is derived from high-voltage battery packs (300-800V), which power motors via inverters and facilitate the operation of low-voltage systems through the utilisation of DC-DC converters. The transition of energy management from a linear to a networked model is characterised by the coordination of decision-making processes by the Vehicle Control Unit (VCU) and the Battery Management System (BMS).
3.3 The following section will examine the evolution of communication networks. The progression from simplicity to complexity is a fundamental aspect of this subject.
Vehicles that are equipped with internal combustion engines. The first and second CAN buses under consideration feature a limited number of nodes, ranging from 10 to 20, and are distinguished by a relatively uncomplicated structural design.
Electric Machinery: The system under discussion requires two additional connections: one Power CAN (to connect BMS, MCU, VCU) and one Charging CAN (to connect OBC and charging station). As network topologies become increasingly intricate, the role of gateways becomes paramount. The subsequent progression is anticipated to be towards CAN FD and Ethernet backbone networks.
3.4 The third section of this text is concerned with the evolution of sensors and actuators. This paper sets out the transition from mechanical to electronic control.
Internal Combustion Engines: Sensors are typically oriented towards the measurement of mechanical parameters, such as revolutions per minute (RPM), pressure, and temperature. In contrast, actuators primarily utilise solenoid valves.
Electric Vehicles: The integration of various electrical sensors (e.g. voltage, current, insulation, resolver) is imperative. Furthermore, the incorporation of actuators, which retain hydraulic solenoid valves, is essential for the subsequent addition of drive motors and inverters. This development signifies a paradigm shift from the conventional "hydraulic drive" to the contemporary "electric drive."
4. Evolutionary Path: The present paper sets out the three stages of EEA development in the field of electric construction machinery.
It is proposed that the evolution of EEA can be divided into three stages, drawing on passenger vehicle experience while accounting for construction machinery characteristics.
Phase One: Distributed Architecture (Electrification 1.0)
The primary focus of this phase is to address the challenge of transitioning from a state of absence to one of presence. The integration of the three electric systems with the traditional mechanical architecture is achieved through grafting, a process that preserves the independence of numerous ECUs, including the BMS, MCU, and VCU. The coexistence of high-voltage and low-voltage systems gives rise to increasingly complex network topologies, while maintaining distinct separation of functional domains. This development signifies the present state of affairs for the majority of electric construction machinery.
The second phase of the project is concerned with the Domain-Centralised Architecture (Electrification 2.0), the aim of which is to move from a satisfactory state to a superior one. The subsequent stage of functional integration is marked by the introduction of the concept of domain controllers.
Powertrain Domain: The system integrates functions from VCU, MCU, and BMS into a unified powertrain domain controller, thereby coordinating energy distribution, torque requests, and thermal management strategies.
Chassis Domain: The vehicle under discussion integrates electrically controlled functions, including driving, steering, and braking.
Smart Cabin Domain: The integration of instrument clusters, central control screens, and telematics processors (T-Box) serves to enhance human-machine interaction.
Area Controllers: The integration of body-side functions, such as lighting, wipers, and I/O interfaces, is a process that is beginning to emerge. The decoupling of hardware and software facilitates the establishment of a foundation for OTA updates.
Phase Three: The objective of the Centralised + Zonal Control (Electrification 3.0) phase is to facilitate a transition from a state of merely adequate performance to one of exceptional quality, thereby achieving the concept of "software-defined hardware."
The Central Computing Unit (HPC) is comprised of one or two high-performance HPCs, which collectively manage all core computing power. These machines operate on a unified operating system, a feature that facilitates flexible function deployment and cross-domain collaboration.
Zone Controllers: It has been demonstrated that multiple ZCUs function as "bridges," thereby establishing a connection between the central computer and physical interfaces, including sensors, actuators, and power distribution systems.
Ethernet Backbone: High-speed Ethernet can be regarded as the central nervous system, connecting HPCs with ZCUs to facilitate the rapid transmission of substantial data volumes.
It is only now that construction machinery is capable of continuous functional iteration and ongoing performance optimisation, paving the way for high-level autonomous driving and fully unmanned operations.
5. Significant Challenges: Obstacles Encountered on the Path to the Future
The evolution of electric construction machinery (EEA) has been far from straightforward, encountering challenges that are even more stringent than those faced by passenger vehicles.
5.1. Extreme Operating Conditions
The reliability of electronic components, connector sealing, and wiring harness durability are all significantly impacted by extreme operating conditions. These include severe vibration and shock, extreme temperature fluctuations, and exposure to multiple contaminants (water, dust, mud, oil). Solutions to this problem include higher IP protection ratings (e.g., IP6K/IP9K), vibration-resistant designs, wide-temperature-range components, and complex thermal management systems.
5.2. Extremely Complex Electromagnetic Compatibility Challenges
High-power inverters (IGBT/MOSFET) are characterised by their operation at elevated switching frequencies, a property that renders them as potent sources of electromagnetic interference. Concurrently, the signals transmitted by analogue sensors dispersed throughout the vehicle body are notably feeble and vulnerable to interference. This necessitates the implementation of rigorous shielding measures, such as dual-layer shielding for high-voltage lines, the installation of filters, the optimisation of routing rules (high/low-voltage isolation), and the design of grounding systems.
5.3. System Layout and Safety Clearance Challenges
The issue of compact spaces must accommodate high-voltage systems, low-voltage systems, hydraulic lines, and mechanical structures while strictly maintaining electrical clearances and creepage distances between high-voltage components to prevent breakdown. This issue is addressed through a multi-faceted approach encompassing "multi-in-one" integrated design, CFD simulation, and strict adherence to safety standards.
5.4. High Real-Time Performance and Functional Safety Challenges
In operational scenarios, it is imperative that control command latency is maintained at a millisecond-level, as communication interruptions have the potential to result in severe accidents. This necessitates networks with high real-time performance (CAN FD), high reliability (redundant design), and compliance with ASIL-D functional safety requirements.
6. Conclusion
The evolution of electronic/electrical architectures in electric construction machinery signifies a profound revolution, transitioning from a "hydraulic backbone" to a "digital neural network." The entity in question is progressing along a trajectory from a 'distributed' to a 'domain-centric' to a 'centralised' model, with the ultimate objective of becoming a software-defined, sustainably evolving intelligent entity.
Despite the challenges that lie ahead, it is inevitable that this transformation will reshape the entire industry, delivering unprecedented efficiency, cleanliness, intelligence, and safety. For Original Equipment Manufacturers (OEMs) and suppliers, it is imperative to comprehensively grasp the fundamental principles of this architectural evolution and to attain mastery over its fundamental technologies if they are to successfully seize the initiative in this transfortive era and assume a leadership role in shaping the future.