Motor PWM Control With Dynamic Modulation for Target Speed Tracking
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Solution Overview
Problem
Conventional PWM control methods for motor drive control may not reliably achieve the target rotation speed of a motor, especially when the motor is under load.
Innovation Solution
A motor drive control device that includes a drive circuit and a control circuit. The control circuit performs PWM control to generate a PWM signal, increasing the modulation degree when the motor's rotation speed has not reached the target speed, to ensure the rotation speed matches the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM control is performed with a fixed modulation degree, then the control method is simple, but the rotation speed cannot reliably reach the target speed under varying load conditions
Solution Approach 1:
The modulation degree is changed from a fixed value to a dynamic variable that adjusts based on the motor's actual rotation speed. The control circuit increases the modulation degree when the rotation speed is below the target speed, allowing the system to adapt to varying load conditions and reliably achieve the target rotation speed.
Solution Approach 2:
The patent changes the modulation degree parameter during operation to improve rotation speed accuracy. By adjusting this key parameter based on speed feedback, the system can compensate for load variations without requiring a completely complex control architecture.
2Speed
If the modulation degree is increased to reach target rotation speed, then the rotation speed accuracy improves, but the control system becomes more complex
Solution Approach 1:
The control circuit uses feedback from the motor's actual rotation speed to determine whether to adjust the modulation degree. When the detected speed is below the target speed, the circuit increases the modulation degree; when the target is reached, it maintains or reduces it. This feedback mechanism achieves speed control without excessive system complexity.
Data Source
AI summary
The rotation speed of a motor is made to more reliably approach a target rotation speed. A motor drive control device includes: a drive circuit configured to apply an AC voltage converted by switching a DC voltage (VDD) to a coil of a motor based on a drive control signal (Sd) for controlling drive of the motor; and a control circuit configured to perform PWM control for generating a PWM signal as the drive control signal (Sd) in a manner that a rotation speed (Sr) of the motor matches a target rotation speed (Stg) and a sinusoidal current flows through the coil. The control circuit generates the PWM signal by increasing a modulation degree indicating a ratio of a command value of the AC voltage relative to the DC voltage (VDD) when the rotation speed (Sr) has not reached the target rotation speed (Stg).