Stepper Motor Current Control for Injection Device Energy Efficiency
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Solution Overview
Problem
Current injection devices using stepper motors are inefficient in energy consumption due to a direct relationship between electrical power and mechanical power, leading to excessive heat conversion and reduced battery durability, especially in battery-driven devices.
Innovation Solution
A method and apparatus that control the current to a stepper motor based on a signal from a force sensor, incrementing the current by a predetermined value or fraction to match the required torque, thereby optimizing energy use and reducing unnecessary heat conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant current is applied to stepper motor coils to ensure reliable torque, then motor reliability is improved, but energy consumption increases and battery durability decreases
Solution Approach 1:
The patent applies dynamics by making the current supplied to motor coils variable rather than constant. The current controller adjusts coil current dynamically based on real-time motor position feedback and predicted torque requirements, allowing the system to provide sufficient torque only when needed while reducing current during periods of lower demand, thus resolving the contradiction between reliability and energy consumption
Solution Approach 2:
The patent implements feedback through a sensor that detects motor position and feeds this information back to the controller. The controller uses this feedback to adjust coil current in real-time, ensuring reliable motor operation only when necessary while minimizing energy consumption during idle or low-demand periods, directly addressing the contradiction between reliability and energy use
2Reliability
If excess power is provided to stepper motor beyond required mechanical power, then motor reliability is improved, but heat conversion increases and energy efficiency deteriorates
Solution Approach 1:
The patent applies partial action by providing just enough current to motor coils to meet the actual torque requirements rather than continuously supplying full rated current. The controller calculates required torque based on motor position and load conditions, applying only the necessary partial current to avoid excessive power conversion to heat while maintaining sufficient motor reliability
Solution Approach 2:
The patent changes the electrical parameter (coil current) dynamically based on operating conditions. By adjusting current magnitude according to real-time motor position and torque requirements, the system prevents excess power from being converted to heat while maintaining reliable motor operation, directly addressing the energy loss problem
3Force
If current is increased to provide higher torque, then motor force capability is improved, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by making coil current variable rather than fixed. The controller dynamically adjusts current magnitude based on real-time motor position feedback and calculated torque requirements, providing high current only when high torque is needed while using lower current during normal operation, thus resolving the contradiction between force capability and energy consumption
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
This approach ensures only the necessary torque is provided, reducing energy consumption and extending battery life by minimizing excess power conversion to heat, while being flexible and adaptable to variations in operating cycles.
Implementation Method 1
receiving a signal from a force sensor, the signal representing a force that is applied by a stepper motor
Implementation Method 2
the current that is required to enable the motor to apply the force represented by the signal
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
In order to improve the energy efficiency of an injection device 100, a current is caused to be applied to a motor 113 of the injection device 100, which is related to a signal from a force sensor 115. The signal represents a force that is applied by the motor 113 to a plunger 122 of a cartridge 121.