This entry presents a Towed DC Electrical System (TDES) that enables fully electrified agricultural machinery to achieve zero on-site emissions and virtually unlimited operating duration. Traditional diesel machinery emits large amounts of CO₂, while battery-electric and hybrid solutions suffer from limited range, long charging times, or residual emissions. TDES overcomes these limitations by delivering grid power directly to the moving machine through an overhead towed DC bus.

The system consists of three main parts: a stationary DC power station at the field edge, a towing mechanism suspending the DC bus, and a compact on-board power unit. Grid AC power is rectified, boosted by DC-DC converters, and transmitted via the towed cable. On the implement, a DC-DC converter and inverter supply variable-frequency AC to electric traction and PTO motors. Multiple operating modes – including pre-deployment charging, deployment, field operation, and emergency handling for grid or bus outages – ensure coordinated, safe power delivery. In operation mode, the machine is electrically tethered but mechanically decoupled from the power station, completely eliminating on-board propulsion batteries and achieving significant weight reduction.

The core innovation lies in the system architecture and a rigorous large-signal stability solution. Unlike conventional towed power systems that use loosely regulated DC buses, TDES employs cascaded tightly controlled converters to maintain a high-quality bus voltage. However, such converters exhibit negative impedance behavior, which can cause instability under the severe load transients typical of agricultural tasks. We resolve this by applying mixed potential theory to derive an explicit large-signal stability criterion. The criterion defines boundary conditions for stable operation and provides direct engineering guidelines: increasing DC-link capacitance, decreasing filter inductance, or reducing voltage-loop gain expands the stable operating region. This is the first application of large-signal stability analysis to a towed agricultural DC system, going beyond traditional small-signal methods and offering global stability margins.

TDES is highly manufacturable. It is built from mature power electronic modules (three-phase VSCs, IGBT-based DC-DC converters, Li-ion battery buffers) and a custom cable management system. Control uses standard DSP/microcontrollers with classical PI loops. Manufacturing requires only established PCB assembly, enclosure fabrication, and system integration. For lower-power implements, a simplified topology omits some converter stages, reducing component count and cost. The modular design allows scaling the power station, cable length, and on-board unit to match different tractor sizes and field dimensions, making it adaptable to existing agricultural equipment.

The primary application is field operations – tillage, planting, spraying, harvesting, and straw crushing – on farms with grid access. TDES is especially suited to fragmented farmland where battery-swapping infrastructure is uneconomical. By replacing diesel with grid electricity, it eliminates direct exhaust emissions, reduces machine weight (thereby decreasing soil compaction), and lowers long-term operating costs.