Electric Motor Torque Map Switching for Low-Speed Power Saving
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Solution Overview
Problem
Existing energy-saving modes in electric working machines, such as backhoes, fail to effectively reduce battery power consumption 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 electric power consumption by defining different torque limits based on two maps, with the second mode having lower torque limits at each rotational speed compared to the first mode.
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 of the battery unit cannot be obtained
Solution Approach 1:
The controller dynamically switches between a first map for normal operation and a second map for energy-saving mode based on operational conditions. The second map dynamically adjusts torque limits to be lower than the first map at corresponding rotational speeds, enabling adaptive power consumption reduction while maintaining operational efficiency through conditional map selection.
Solution Approach 2:
The system changes the torque limit parameters by selecting different maps. The second map defines torque limits that are lower than the first map at the same rotational speeds, effectively changing the operational parameters to reduce power consumption from the battery unit while maintaining acceptable performance levels.
2Use of energy by moving object
If the upper limit of rotational speed of the electric motor is lowered compared with normal mode, then energy-saving mode is activated, but the reduction in electric power consumption is insufficient
Solution Approach 1:
The system implements parameter changes by defining a second map with lower torque limits compared to the first map. This parameter adjustment allows the motor to operate with reduced power output in energy-saving mode, achieving effective reduction in battery power consumption while maintaining operational capability through the alternative map.
Solution Approach 2:
The controller dynamically selects between the first map (normal power mode) and the second map (reduced power mode) based on operational requirements. This dynamic switching enables the system to adapt power output levels, achieving effective battery power consumption reduction when energy-saving mode is activated.
3Use of energy by moving object
If a single map is used for torque control, then control simplicity is maintained, but the ability to reduce power consumption is limited
Solution Approach 1:
The torque control is segmented into multiple maps: a first map for normal operation and a second map for energy-saving mode. Each map serves a specific operational purpose, allowing the system to reduce power consumption by selecting the appropriate map while maintaining relatively simple control logic through conditional map selection based on operational state.
Data Source
AI summary
An electric working machine includes an electric motor, a rotational speed detector to detect an actual rotational speed of the electric motor, and a controller to control a rotational speed and an output torque of the electric motor. The controller is switchable between a first mode in which the electric motor is controlled such that a relationship between the actual rotational speed and a first upper limit value of the output torque satisfies a first map and a second mode in which the control is performed such that the relationship satisfies a second map. The maps 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 that of the first map, and that a difference between the first upper limit values on the first and second maps increases as the actual rotational speed increases.