DC Motor Control Apparatus for Rotor Magnetizing Error
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Solution Overview
Problem
Conventional DC motors experience vibration noise and reduced rotational speed due to unstable coil currents during semiconductor switching, caused by motor resonance and variations in magnetic pole position sizes.
Innovation Solution
A control apparatus comprising a phase detector, counter, PWM signal generator, control circuit, and full-bridge driving circuit that detects magnetic pole position changes, counts associated values, and adjusts PWM signals to stabilize semiconductor switching, thereby reducing vibration noise and increasing rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If semiconductor switching devices are used to implement electronic phase-switching in a conventional DC motor, then the motor can be controlled to rotate effectively, but unstable coil current occurs during switching which induces vibration noise due to motor resonance
Solution Approach 1:
The patent applies preliminary action by detecting the magnetic pole position in advance and pre-adjusting the PWM signal duty cycle before the switching event occurs. The control circuit calculates the optimal duty cycle based on the detected rotor position and applies it proactively, preventing the unstable current and vibration noise before they occur during the switching process.
Solution Approach 2:
The patent implements feedback by continuously monitoring the magnetic pole position through Hall sensors and using this information to dynamically adjust the PWM signal duty cycle. The control circuit receives position feedback, processes it to determine the appropriate duty cycle, and applies real-time adjustments to maintain stable coil current and eliminate vibration noise during switching operations.
2Device complexity
If the rotor is made of permanent magnets with varying magnetic pole position sizes, then the motor structure is simplified, but the variation in magnetic pole positions causes unstable coil current and reduced rotational speed
Solution Approach 1:
The patent applies dynamics by making the PWM duty cycle adjustable and adaptive rather than fixed. The control circuit dynamically modifies the duty cycle based on the detected magnetic pole position variations, allowing the system to accommodate the varying sizes of magnetic poles in the permanent magnet rotor while maintaining stable rotational speed and eliminating the need for complex mechanical adjustments.
3Device complexity
If conventional PWM signals are used without adjustment based on magnetic pole position, then the control circuit is simple, but vibration noise occurs and rotational speed is reduced
Solution Approach 1:
The patent implements parameter changes by varying the PWM signal duty cycle parameter based on the detected magnetic pole position. The control circuit modifies the duty cycle parameter dynamically according to the rotor position and magnetic pole characteristics, which stabilizes the coil current and eliminates vibration noise while maintaining a relatively simple control circuit architecture.
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
The solution effectively lowers vibration noise and enhances the rotational speed of the DC motor by accurately adjusting PWM signals based on magnetic pole position sizes, ensuring stable operation.
Implementation Method 1
The phase detector detects changes of states of the magnetic pole positions of the rotor in the DC motor to generate a periodical phase-switching signal
Implementation Method 2
The PWM signal generator is coupled to the counter and the phase detector and periodically outputs 2N PWM signals. The PWM signal generator adjusts each of the PWM signals outputted in order in a next cycle according to the count value, related to each of the magnetic pole positions, received in a current cycle
Implementation Method 3
The full-bridge driving circuit includes two output terminals coupled to the DC motor, and alternately outputs a first output signal and a second output signal to the DC motor according to the first direction driving signal, the second direction driving signal, the third logic signal and the fourth logic signal so that the magnetic pole positions of the rotor in the DC motor change to drive the DC motor to rotate
Data Source
AI summary
A control apparatus for eliminating a magnetizing error of a rotor in a DC motor and a method thereof. The rotor in the DC motor is provided with 2N magnetic pole positions disposed therein for phase switching, where N is a positive integer no less than 1. The control apparatus includes a phase detector, at least one counter, a PWM signal generator, control circuit and a full-bridge driving circuit. The phase detector detects changes of states of the magnetic pole positions of the rotor to generate a periodic phase-switching signal. The counter counts a count value associated with each of the magnetic pole positions, respectively. The PWM signal generator periodically outputs 2N PWM signals and adjusts each of the PWM signals issued in a next cycle, respectively, according to the count value associated with each of the magnetic pole positions received in a current cycle.