Single Speed Motor Voltage Ramping for Irrigation Torque Control
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Solution Overview
Problem
Irrigation systems with single speed drive motors experience rapid acceleration and deceleration, leading to high torques and oscillations that cause structural fatigue and alignment issues, which are not effectively addressed by conventional technologies due to the high cost and limitations of variable speed motors.
Innovation Solution
A center pivot irrigation system with a control system that operates single speed drive motors in three modes: start-up, full speed, and wind-down, gradually ramping voltage to minimize motor acceleration and deceleration, reducing structural fatigue and oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single speed drive motors are used to drive irrigation spans, then device complexity and cost are reduced, but rapid acceleration and deceleration cause high torques and oscillations leading to structural fatigue and alignment issues
Solution Approach 1:
The control system performs preliminary actions by gradually ramping up voltage during motor startup and ramping down voltage during motor shutdown. This prevents sudden torque spikes and oscillations before they can occur, protecting the irrigation spans and drive trains from structural fatigue while maintaining simple single-speed motor hardware.
Solution Approach 2:
The invention changes the voltage parameter applied to the single-speed motor over time. During startup, voltage increases gradually from zero to full level; during shutdown, voltage decreases gradually from full to zero. This parameter change smooths torque output and eliminates harmful oscillations without requiring variable speed motors.
2Productivity
If single speed motors are switched on and off frequently to move irrigation spans at different rates, then productivity and operational flexibility are improved, but high torques cause oscillations that propagate across spans forming standing waves
Solution Approach 1:
Before full motor operation begins, the control system applies a preliminary gradual voltage ramp-up that prevents sudden torque application. This preliminary action eliminates the initial oscillation that would otherwise propagate across irrigation spans and form standing waves, while still allowing frequent on/off cycling for operational flexibility.
Solution Approach 2:
The control system converts the inherently abrupt torque characteristics of single-speed motors into a beneficial smooth torque profile by using controlled voltage ramping. The harmful sudden start/stop behavior is transformed into a controlled gradual acceleration/deceleration process that eliminates oscillations while maintaining productivity.
3Reliability
If variable speed motors are used to eliminate rapid acceleration and deceleration, then structural fatigue and oscillations are reduced, but device complexity and cost increase significantly
Solution Approach 1:
The control system acts as an intermediary between the simple single-speed motor and the irrigation span drive train. By inserting voltage ramping control logic, it mediates the harsh torque characteristics of the motor to produce smooth acceleration and deceleration, achieving variable-speed benefits without the complexity of variable-speed motors.
Solution Approach 2:
The invention replaces the mechanical complexity of variable-speed motor systems with an electrical control solution. Instead of using mechanically complex variable-speed motors, it uses simple voltage ramping control to achieve smooth torque delivery, substituting mechanical complexity with electrical control simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces structural fatigue and oscillations, extends component lifespan, and prevents motor misalignment, offering a cost-effective solution compared to variable speed motors by optimizing motor torque and alignment.
Implementation Method 1
The single speed drive motor is configured to run at 50 Hz, 60 Hz, or any other suitable frequency. The motor controller activates the drive motor according to instructions received from the system controller
Data Source
AI summary
An irrigation system broadly comprising a number of irrigation spans and a control system configured to operate single speed drive motors of the irrigation spans in a start-up mode, full speed mode, and wind-down mode. In the start-up mode, the motor controller gradually increases the drive motor speed from 0 rpms to a full speed by ramping a voltage applied to the drive motor from a starting voltage to a full speed voltage according to a start-up voltage profile over a start-up time interval. In the full speed mode, the motor controller operates the drive motor at a full speed voltage. In the wind-down mode, the motor controller gradually decreases the drive motor speed from full speed to 0 rpms by ramping the voltage applied to the drive motor from the full speed voltage to an ending voltage according to a wind-down voltage profile over a wind-down time interval.