Stepping Motor Control Device Torque Stabilization
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Solution Overview
Problem
Stepping motors face limitations in controlling torque stably across a wide range of rotational speeds, from low to high, due to induced voltage issues proportional to magnetic flux, current, speed, and inductance, leading to a cap on rotational speed when induced voltage equals or exceeds motor power supply voltage.
Innovation Solution
A motor control device comprising a first signal generator, a second signal generator, and a main controller, which generate control signals to manage excitation current polarity and amount, and control excitation current to reduce rotor phase deviation, allowing for micro-step and vector control to stabilize torque across varying speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotational speed of the stepping motor is increased, then the productivity is improved, but the induced voltage increases proportionally causing the rotational speed to be limited when induced voltage equals or exceeds motor power supply voltage
Solution Approach 1:
The patent applies dynamics by switching from traditional pulse control to a dynamic control method that adjusts excitation current based on rotational speed. The controller dynamically changes the excitation current amount and polarity timing to compensate for induced voltage effects at different speeds, enabling stable torque control across a wide speed range from low-speed to high-speed rotation.
Solution Approach 2:
The patent changes the parameter of excitation current (both amount and polarity timing) based on rotational speed. By adjusting these parameters dynamically, the system compensates for the induced voltage that increases with speed, allowing the motor to maintain stable torque control even when induced voltage approaches or exceeds the power supply voltage.
2Stability of the object's composition
If the excitation current is increased to maintain torque at high speeds, then the torque stability is improved, but the induced voltage increases further limiting the rotational speed
Solution Approach 1:
The patent applies periodic action by controlling the polarity switching of excitation current in synchronization with the rotor's rotational position. The controller generates polarity signals that periodically reverse the excitation current direction at appropriate timing, which helps maintain stable torque while managing induced voltage effects through rhythmic, position-synchronized current reversal.
Solution Approach 2:
The patent implements feedback control by detecting the rotational speed and using this information to adjust the excitation current amount and polarity timing. The controller continuously monitors speed and modifies control parameters accordingly, creating a closed-loop system that maintains torque stability while compensating for speed-dependent induced voltage.
3Productivity
If the polarity switching timing of excitation current is delayed to compensate for induced voltage, then the high-speed torque is improved, but the low-speed positioning accuracy may be affected
Solution Approach 1:
The patent applies dynamics by making the polarity switching timing variable rather than fixed. The controller dynamically adjusts the polarity switching timing based on detected rotational speed, delaying it at high speeds to compensate for induced voltage effects while maintaining appropriate timing at low speeds to preserve positioning accuracy. This dynamic adjustment allows the system to optimize performance across the entire speed range.
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 stable torque control from low to high rotational speeds by effectively managing excitation currents and phase deviations, preventing torque decrease at high speeds and maintaining high accuracy in rotational control.
Implementation Method 1
an induced voltage caused by rotation of the stepping motor is proportional to a magnetic flux generated by a rotor, a current that flows in a stator, a rotational speed of the rotor, the inductance of a winding wire, and the number of magnetic poles
Data Source
AI summary
A motor control device according to an embodiment comprises a first signal generator, a second signal generator, a main controller, and a driver. The first signal generator is configured to generate, based on a clock signal indicating a stepping drive cycle of a motor, a first control signal. The second signal generator is configured to generate, based on a command phase indicating a target phase of a rotor of the motor, a second control signal. The main controller is configured to control the first signal generator and the second signal generator to output at least one of the first control signal and the second control signal. The driver is configured to drive the motor based on at least one of the first control signal and the second control signal.