Motor Control Circuit Reducing Speed Jitter via Synchronized PWM
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Solution Overview
Problem
Conventional motor control circuits for brushless DC electric motors experience speed jitter due to misalignment of function signals with motor rotations, leading to reduced printing clarity in applications like inkjet printers.
Innovation Solution
A motor control circuit that generates position signals, pattern signals, and pulse width modulated signals to accurately control motor speed, synchronized with an external clock signal, using multiple modulation waveform generators and comparators to ensure consistent PWM signal phases and reduced jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional motor control circuit uses a single function signal to generate motor drive signals, then the circuit complexity is low, but the motor speed accuracy deteriorates causing jitter
Solution Approach 1:
The patent divides the single function signal generation into multiple independent function signals (first function signal, second function signal, third function signal) that are generated separately and then combined. Each function signal is processed through its own modulation waveform generator and comparator, allowing independent optimization of each signal path to achieve better overall motor speed accuracy and reduced jitter.
2Ease of operation
If the function signal does not align with motor rotations, then the circuit operation is simple, but the printing clarity deteriorates due to speed jitter
Solution Approach 1:
The patent introduces feedback mechanisms where the position signals from Hall effect sensors are used to generate function signals that are synchronized with motor rotation. The modulation waveform generators and comparators continuously adjust the PWM signals based on the motor's actual position and speed, ensuring the function signals remain aligned with motor rotations to eliminate speed jitter and maintain printing clarity.
3Reliability
If conventional motor control is used without synchronization, then the system is simpler to implement, but the rotational speed stability deteriorates
Solution Approach 1:
The patent implements preliminary synchronization by using Hall effect sensors to detect motor position before generating drive signals. The function signals are pre-aligned with motor rotation phases through the pattern generator and modulation waveform generators, ensuring that PWM signals are applied at the correct moments in the rotation cycle. This preliminary action establishes stable rotational speed from the start of operation.
Data Source
AI summary
Motor control circuits and associated methods to control an electric motor provide a plurality of drive signal channels at the same phase, resulting in reduced jitter in the rotational speed of the electric motor.