Electric Work Machine Torque Mapping for Low-Speed Power Saving
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Solution Overview
Problem
Existing electric working machines, such as backhoes, fail to effectively reduce electric power consumption in energy-saving modes when the electric motor operates at low rotational speeds.
Innovation Solution
Implementing a controller that switches between two modes: a first mode prioritizing work efficiency and a second mode reducing power consumption by defining a second map with lower output torque limits, allowing the controller to adjust the electric motor's rotational speed and torque based on predefined maps stored in memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric motor is controlled at a relatively low rotational speed to reduce power consumption, then energy-saving mode is activated, but the effect of reducing electric power consumption cannot be obtained
Solution Approach 1:
The patent implements dynamic switching between two control modes (first mode and second mode) based on operational conditions. The controller dynamically adjusts the upper limit value of output torque according to the actual rotational speed and the selected mode, allowing the system to adapt between energy-saving operation and high-performance operation as needed
Solution Approach 2:
The patent changes the control parameters by defining two different maps (first map and second map) with different upper limit values for output torque. The second map has lower upper limit values than the first map, enabling the system to operate with reduced torque limits in energy-saving mode while maintaining stable control through parameter adjustment
2Productivity
If a first map with higher output torque limits is used to maintain work efficiency, then productivity is improved, but electric power consumption increases
Solution Approach 1:
The system dynamically switches between using the first map (for high productivity) and the second map (for energy saving) based on operational requirements. The controller can select which map to apply, enabling flexible adjustment between work efficiency priority and energy consumption priority
Solution Approach 2:
The patent defines two distinct maps with different parameter sets for upper limit values of output torque. By selecting between these predefined parameter sets (first map vs. second map), the system can change its operational characteristics to match the desired balance between productivity and energy consumption
Data Source
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AI summary
To reduce electric power consumption more. An electric working machine (1) includes an electric motor (46) to be driven by electric power, a rotational speed detector (35a) to detect an actual rotational speed (Ra) of the electric motor, and a controller (30) to control a rotational speed and an output torque (T) of the electric motor. The controller is switchable between (i) a first mode in which the controller controls the electric motor such that a relationship between the actual rotational speed and a first upper limit value (Tr) of the output torque satisfies a first map and (ii) a second mode in which the controller controls the electric motor such that the relationship between the actual rotational speed and the first upper limit value of the output torque satisfies a second map. The first map and the second map are defined such that the first upper limit value of the output torque at a certain actual rotational speed on the second map is smaller than the first upper limit value of the output torque at the same certain actual rotational speed on the first map, and that a difference between the first upper limit value on the first map and the first upper limit value on the second map increases as the actual rotational speed increases.