Gear Motor Power Detection Circuit for Load Abnormality
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Solution Overview
Problem
Existing motor devices, particularly gear motors used in belt conveyors, face challenges in accurately detecting load abnormalities, especially in low-load conditions, due to variations in power supply voltage and the inability of current monitoring to distinguish between normal and abnormal loads, leading to potential interference with driven devices.
Innovation Solution
A motor device with a power detection circuit and control unit housed in a terminal box, utilizing three-phase coils and resistors to calculate power independently of voltage variations, along with vibration and temperature detection, to accurately identify load abnormalities and shut off power supply through a circuit breaker, without requiring additional external circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current monitoring is used for overload detection, then the circuit structure is simple, but load abnormalities cannot be accurately detected in low-load conditions due to small current changes
Solution Approach 1:
The patent changes the detection parameter from current to power. By detecting power instead of current, the system can accurately identify load abnormalities even in low-load conditions where current changes are minimal. Power detection provides larger signal variations that are more suitable for detecting load changes across the full operating range.
Solution Approach 2:
The patent replaces the simple current monitoring approach with a power detection system that incorporates voltage and current measurements. This substitution enables more precise detection of load abnormalities by calculating power (P=UI) rather than merely monitoring current, thereby resolving the detection accuracy issue.
2Reliability
If a high-power motor is selected for belt conveyor with safety margin, then operational safety is improved, but load abnormality detection becomes difficult due to operation in low load factor area
Solution Approach 1:
The patent addresses this contradiction by changing from current-based detection to power-based detection. In the low load factor area typical of high-power motors operating with safety margins, power variations provide more detectable signals than current variations alone, enabling accurate load abnormality detection while maintaining the safety margin operation.
3Measurement precision
If additional circuit devices are disposed outside the terminal box for power detection, then detection accuracy is improved, but interference with driven device occurs and miniaturization is prevented
Solution Approach 1:
The patent merges the power detection circuit with the terminal box structure. By integrating the detection circuitry within the existing terminal box rather than placing it externally, the system achieves accurate load abnormality detection without adding separate circuit devices that could interfere with the driven device or prevent miniaturization.
Solution Approach 2:
The terminal box is designed to serve multiple functions: it houses both the connection terminals and the power detection circuit. This multi-functional design eliminates the need for separate external detection devices, preventing interference with the driven device while enabling accurate load monitoring.
4Device complexity
If current monitoring is used, then the system is simple, but accurate detection of load abnormality independent of power supply voltage variation cannot be achieved
Solution Approach 1:
The patent changes from monitoring only current to detecting power, which incorporates both voltage and current measurements. Since power (P=UI) inherently accounts for voltage variations, this parameter change enables accurate load detection that is independent of power supply voltage fluctuations, while the integrated circuit design keeps system complexity manageable.
Data Source
AI summary
A gear motor (motor device) comprising a three-phase motor and a terminal box housing a power supply connection terminal for connecting the three phase motor to an alternating current power supply, comprises: a power detection circuit that detects power to be supplied to the three-phase motor; a control unit that executes predetermined control if a load abnormality related to the three-phase motor or a driven device is detected based on power detected by the power detection circuit. The power detection circuit and the control unit are housed in the terminal box.