Electric Motor Hydraulic Load Control Under Limited Power
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Solution Overview
Problem
Electric motor-driven hydraulic systems face instability and potential shutdowns due to under-voltage conditions when power demands exceed the available power supply, particularly in scenarios where the power source is below capacity, leading to component damage and system inefficiencies.
Innovation Solution
Implement a controller that determines actual electric power stored in the power source, compares it to a threshold, and adjusts the available power to match the system's requirements, ensuring the electric motor operates within the available capacity to prevent power bus collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the controller operates the electric motor at the commanded power level when power supply is below capacity, then the commanded function can be performed, but it causes under-voltage condition and power bus collapse
Solution Approach 1:
The system dynamically adjusts the motor operating parameters (speed, torque, power) based on real-time power source capacity assessment. The controller continuously monitors power availability and adapts the motor operation to match available power, transitioning between different operating modes to prevent power bus collapse while maintaining essential functionality.
Solution Approach 2:
The controller changes operational parameters of the electric motor based on power source capacity. When power is insufficient, the system modifies speed, torque, or power level parameters to operate within available capacity constraints, preventing under-voltage conditions while still enabling reduced-capacity operation of hydraulic actuators.
2Reliability
If the controller limits the motor power to available power capacity, then power bus collapse is prevented, but the commanded function cannot be fully performed
Solution Approach 1:
When full commanded power is unavailable, the system performs partial action by operating the motor at reduced power levels that are still sufficient to perform essential hydraulic functions. Rather than complete shutdown, the system delivers reduced but meaningful work output, enabling critical operations to continue at diminished capacity.
Solution Approach 2:
The system converts the harmful condition of power shortage into a beneficial operational mode by detecting power capacity limitations and automatically adjusting operation accordingly. The power constraint becomes a trigger for intelligent power management that prevents system failure while maintaining essential functionality, turning a potential shutdown scenario into a controlled reduced-power operation.
3Power
If the system operates without power management, then full power performance is achieved, but component damage and system shutdowns occur
Solution Approach 1:
The controller performs preliminary assessment of power source capacity before commanding full motor power operation. By evaluating available power in advance and setting appropriate power limits beforehand, the system prevents under-voltage conditions and subsequent component damage before they can occur, rather than reacting after damage has begun.
Solution Approach 2:
The system implements continuous feedback monitoring of power source capacity and power bus voltage conditions. The controller uses this feedback to dynamically adjust motor power demand, creating a closed-loop control system that automatically reduces power consumption when voltage drops are detected, preventing the harmful cascade that leads to component damage and system shutdowns.
Data Source
AI summary
Hydraulic load management for electric motor driven systems, such as hydraulic systems in a work machine, is disclosed. The hydraulic system may include an electric motor coupled to a hydraulic pump to provide hydraulic fluid to a hydraulic actuator, and a power bus may connect an electric power source to the electric motor. Hydraulic load management may include determining an actual electric power available at the electric power source, comparing the actual electric power to a threshold electric power for operating the electric motor at a full capacity, and setting a value for an available electric power and a current power curve for the electric motor corresponding to the available electric power. When hydraulic system input is detected, electric power is provided via the power bus, and the electric motor is operated at a motor speed based on the current power curve and a commanded speed from the hydraulic system input.