Stepping Motor Driving Circuit Optimizes Startup Current
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Solution Overview
Problem
Stepping motors experience out-of-step issues during startup, particularly due to drastic changes in load or speed, leading to inefficiencies and increased power consumption, as existing feedback control methods are ineffective during this phase and require a high torque margin, which prolongs stabilization time.
Innovation Solution
A driving circuit with a current value setting circuit, constant current chopper circuit, and logic circuit that initially sets the current to a maximum value and then reduces it to an optimized value through feedback control, allowing for a short stabilization time by predicting the convergence value based on the load and switching to a high-efficiency mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high torque margin is configured to avoid out-of-step during startup, then reliability is improved, but power consumption increases and stabilization time is prolonged
Solution Approach 1:
The system performs preliminary action by detecting load torque before startup and pre-calculating the optimal current setting value. This allows the motor to start with an optimized current level rather than a conservative high margin, preventing out-of-step conditions while reducing power consumption from the outset.
Solution Approach 2:
The system implements feedback control by continuously monitoring the motor's operational state and adjusting the current setting value dynamically. The load torque detection and stabilization detection mechanisms provide feedback that enables real-time optimization of current levels, maintaining reliability while minimizing power consumption.
2Reliability
If a high torque margin is configured to avoid out-of-step during startup, then reliability is improved, but stabilization time is prolonged
Solution Approach 1:
The system performs preliminary load torque detection and optimal current value calculation before the motor starts rotating. This pre-computation of the precise current setting value eliminates the need for prolonged stabilization periods, as the motor begins operation with the optimal current level already established.
Solution Approach 2:
The system transitions from static conservative current settings to dynamic optimization. By continuously detecting load torque and stabilzation state, the system adapts the current setting value in real-time, allowing rapid stabilization while maintaining reliability throughout the startup process.
3Use of energy by moving object
If feedback control of output torque is used to optimize current amount, then power consumption is reduced, but effectiveness is lost during initial startup phase
Solution Approach 1:
The system performs preliminary load torque detection and optimal current value calculation during the startup phase itself, rather than waiting for feedback control to become effective. This ensures that power optimization is achieved from the very beginning while maintaining out-of-step prevention capability through active monitoring.
Solution Approach 2:
The system implements enhanced feedback control that operates throughout the entire startup process. By detecting load torque and stabilization state in real-time, the feedback mechanism maintains effectiveness during the initial startup phase while continuously optimizing power consumption.
4Use of energy by moving object
If the current setting value is reduced to an optimized value, then power consumption is reduced, but the motor may become vulnerable to out-of-step conditions
Solution Approach 1:
The system dynamically adjusts the current setting value based on real-time detection of load torque and stabilization state. Rather than using a fixed reduced current level, the system maintains out-of-step resistance by adapting current levels to actual operational conditions, ensuring reliability while minimizing power consumption.
Solution Approach 2:
The system uses feedback control to monitor the motor's operational state and adjust the current setting value accordingly. This ensures that when the current is reduced to optimized levels, the system can immediately respond to changing conditions and increase current if out-of-step conditions are detected, maintaining reliability throughout operation.
Data Source
AI summary
The present invention relates to a driving circuit and a driving method for a stepping motor, and an electronic machine using the same. A current value setting circuit generates a current setting value. A constant current chopper circuit generates a pulse modulation signal, which pulse-width modulates by having a detection value of a coil current flowing through a coil approach close to the current setting value. A logic circuit controls a bridge circuit connected to the coil of the stepping motor according to the pulse modulation signal. The current value setting circuit sets the current setting value to a predetermined full-torque setting value in a first period after rotation starts, reduces the current setting value to a predetermined second setting value less than the first setting value in the following second period, and switches to a high-efficiency mode and adjusts the current setting value by means of feedback control.