Stepping Motor Controller Pulse Frequency Adjustment
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Solution Overview
Problem
Stepping motors in gaming machines experience step-out phenomena at high-speed rotations due to excessive load torque, leading to reduced motor torque and difficulty in proper rotation control, as existing software-based control methods are limited in generating intermediate pulse frequencies.
Innovation Solution
A stepping motor controller with a pulse frequency adjustment circuit that receives command pulses from an external controller and generates alternative pulses at a lower frequency to prevent step-out, allowing the motor driving circuit to control the stepping motor effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the command pulse frequency is increased to achieve high-speed rotation, then the rotation speed is improved, but step-out occurs due to excessive load torque exceeding the through torque characteristic
Solution Approach 1:
The system dynamically adjusts the command pulse frequency based on real-time motor state. When step-out is detected or predicted, the frequency is automatically reduced to prevent further step-out, and then gradually increased again once stability is restored. This dynamic adjustment resolves the contradiction by allowing high-speed operation when conditions permit while preventing step-out when load torque becomes excessive.
Solution Approach 2:
The control system incorporates feedback mechanisms to detect step-out conditions by monitoring the relationship between command pulses and actual motor rotation. When step-out is detected, the system feeds back this information to adjust the pulse frequency downward, preventing the contradiction from persisting. The feedback loop enables the system to maintain reliable operation at high speeds by continuously adapting to changing load conditions.
2Reliability
If the command pulse frequency is lowered to prevent step-out, then step-out is avoided, but the rotation speed drastically reduces making proper rotation control difficult
Solution Approach 1:
Rather than maintaining a fixed low frequency to prevent step-out, the system dynamically adjusts frequency based on actual motor performance. The frequency is lowered only when and where step-out occurs, and raised again when the motor stabilizes. This allows the system to maintain high rotation speed overall while preventing step-out locally when necessary, resolving the contradiction between reliability and speed.
Solution Approach 2:
The system changes the command pulse frequency parameter adaptively based on motor state. Instead of using a static low frequency to prevent step-out, the frequency parameter is continuously adjusted within a range that prevents step-out while maintaining as high a rotation speed as possible. This parameter change strategy resolves the contradiction by finding the optimal frequency at each moment rather than using a conservative fixed value.
3Ease of manufacture
If software-based control is used to generate command pulses, then the control is simple to implement, but the control is limited to interrupt execution intervals and cannot generate intermediate pulse frequencies
Solution Approach 1:
A dedicated pulse generation circuit acts as an intermediary between the software control and the motor drive. This hardware intermediary receives software-generated control signals and generates the actual command pulses with precise frequency control. The intermediary enables intermediate frequency values that software alone cannot produce, while keeping the software implementation simple. This resolves the contradiction by adding hardware capability without complicating the software.
Solution Approach 2:
The patent replaces pure software-based pulse generation with a hybrid approach using dedicated hardware circuitry for pulse generation. This substitution allows continuous frequency adjustment beyond what software interrupt intervals permit, while maintaining the simplicity of software control logic. The hardware pulse generator provides the versatility needed for intermediate frequencies without requiring complex software implementation.
Data Source
AI summary
A stepping motor controller includes: a pulse frequency adjustment circuit that receives a command pulse having a first frequency from an external controller that outputs the command pulse in accordance with an interrupt process performed periodically by the external controller, and generates an alternative command pulse having a second frequency that is lower than the first frequency; and a motor driving circuit that receives the command pulse through the pulse frequency adjustment circuit, and controls a stepping motor to rotate on the basis of the command pulse. The pulse frequency adjustment circuit outputs the alternative command pulse to the motor driving circuit instead of the command pulse received from the external controller, when the first frequency exceeds a predetermined level.