Stepping Motor Back-EMF Threshold Adaptation
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Solution Overview
Problem
Stepping motors face challenges in maintaining precision step-out determination across a wide temperature and input voltage range, as existing motor control devices fail to adjust the back electromotive force threshold value effectively, leading to deteriorated precision under varying conditions.
Innovation Solution
A motor control circuit that measures input voltage and temperature, sets a determination threshold value for back electromotive force based on preset reference values in a matrix-form sectioned by voltage and temperature ranges, allowing for precise step-out determination across a wide range of conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the threshold value of back electromotive force is set to a low value to secure torque under low voltage conditions, then the torque is secured, but the determination precision of step-out determination deteriorates under high voltage conditions
Solution Approach 1:
The threshold value for back electromotive force is made dynamic by adjusting it according to the detected input voltage level. The control unit selects different threshold values from a predetermined set based on the input voltage, allowing the threshold to adapt to changing voltage conditions rather than remaining fixed. This resolves the contradiction by enabling the system to maintain appropriate sensitivity across different voltage ranges.
Solution Approach 2:
The invention changes the parameter of the threshold value based on the input voltage parameter. When input voltage is detected to be in a lower range, a corresponding threshold value is selected that is appropriate for low-voltage operation. This parameter adaptation allows the system to optimize both torque and determination precision for each voltage condition.
2Measurement precision
If the threshold value of back electromotive force is set to a high value to secure determination precision under high voltage conditions, then the determination precision is improved, but it becomes impossible to secure the torque of the stepping motor under low voltage conditions
Solution Approach 1:
The threshold value is made dynamic and adaptive to input voltage conditions. The control unit detects the input voltage level and automatically selects the appropriate threshold value from a predetermined set, ensuring that the threshold adapts to both high and low voltage conditions rather than remaining fixed at a single value.
Solution Approach 2:
The threshold parameter is changed according to the input voltage parameter. For high voltage conditions, a higher threshold value is selected to maintain determination precision, while for low voltage conditions, a lower threshold value is selected to maintain torque. This parameter adaptation resolves the contradiction between precision and torque across different voltage ranges.
3Device complexity
If a fixed threshold value is used for back electromotive force, then the device complexity is reduced, but the precision of step-out determination deteriorates when temperature or input voltage varies
Solution Approach 1:
The threshold value is made dynamic by implementing voltage-dependent adjustment. The control unit detects input voltage and automatically selects from a predetermined set of threshold values, providing adaptability without requiring complex real-time calculation or multiple sensors. This balances complexity and precision effectively.
Solution Approach 2:
The threshold parameter is changed based on the input voltage parameter through a lookup approach. A predetermined set of threshold values is stored, and the control unit selects the appropriate value based on detected voltage conditions. This approach provides precision adaptation while maintaining relatively simple device complexity.
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
Enables high-precision step-out determination of stepping motors under varying temperature and input voltage conditions, ensuring appropriate operation of actuators by finely adjusting threshold values according to the influence of both factors.
Implementation Method 1
a back electromotive force measuring unit for measuring back electromotive force induced in a coil for which energization is stopped
Data Source
AI summary
A motor control circuit (12) capable of performing a high-precision step-out determination under a wide range of conditions. The motor control circuit (12) includes an input voltage measuring unit (125), a temperature measuring unit (128), a back electromotive force measuring unit (126), a determination threshold value setting unit, and a determination unit. The input voltage measuring unit (125) measures an input voltage input to a motor control device (10). The temperature measuring unit (128) measures temperature. The back electromotive force measuring unit (126) measures back electromotive force induced in a coil for which energization is stopped out of the coils of plural phases. The determination threshold value setting unit sets a determination threshold value of back electromotive force based on a measurement result of the input voltage measuring unit (125) and a measurement result of the temperature measuring unit (128), and based on a determination reference value that is preset for each of plural partial areas sectioned in a matrix form with a threshold value relating to the input voltage and a threshold value relating to the temperature. The determination unit makes a determination on step-out of a stepping motor (20) based on a measurement result of the back electromotive force measuring unit (126) and the set determination threshold value of the back electromotive force.