Three-Phase Motor Controller for Stable Back-EMF Phase Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sensorless driving methods for three-phase motors suffer from switching noise and reduced accuracy due to unstable voltage detection during floating phase intervals, limiting their applicability to high-frequency configurations.
Innovation Solution
A motor controller with a switch circuit and pulse width modulation circuit that modulates transistor resistance and operates in voltage or current lock modes to reduce switching noise and eliminate the need for ON/OFF time detecting modes, allowing for accurate back electromotive force detection without mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor controller detects back electromotive force during floating phase time interval, then phase switching can be achieved, but switching noise is generated which affects detecting accuracy
Solution Approach 1:
The patent applies preliminary action by pre-establishing complementary conduction states for transistor pairs before floating phase detection. Specifically, during floating phase detection, one transistor in each pair is pre-configured to be fully turned on while its complementary transistor is fully turned off, eliminating the need for rapid switching during detection and thereby preventing switching noise that would interfere with back electromotive force measurement accuracy
2Productivity
If the ON time interval of pulse width modulation signal is too small, then switching frequency increases, but voltage of floating phase pin becomes unstable making back electromotive force difficult to detect
Solution Approach 1:
The patent applies dynamics by implementing dynamic control of transistor conduction states based on operational mode. During back electromotive force detection mode, the system dynamically configures transistors to stable conduction states (fully on or fully off) regardless of the pulse width modulation duty cycle, thereby stabilizing the floating phase pin voltage and enabling accurate detection even at high switching frequencies where the ON time interval would normally be too small
3Measurement precision
If the motor controller switches between ON time detecting mode and OFF time detecting mode, then back electromotive force detection can be performed, but zero points detected are different causing inconsistency
Solution Approach 1:
The patent applies universality by creating a unified detection mechanism that functions consistently across different operational modes. The complementary transistor pair structure provides a universal stable conduction state regardless of whether the system is in ON time detection mode or OFF time detection mode, ensuring that zero points are detected at consistent positions and eliminating the need to switch between different detecting modes
4Ease of operation
If transistors are kept turning ON/OFF during floating phase time interval, then phase switching is achieved, but switching noise is generated that decreases success rate of switching phases
Solution Approach 1:
The patent applies preliminary action by pre-establishing stable conduction states for transistor pairs before floating phase detection begins. By configuring one transistor to be fully on and its complementary transistor fully off in advance, the system eliminates rapid switching actions during the critical detection period, thereby preventing switching noise generation and increasing the reliability and success rate of phase switching operations
Data Source
AI summary
A motor controller comprises a switch circuit, a driving circuit, and a pulse width modulation circuit. The switch circuit is coupled to a three-phase motor for driving the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. When the motor controller starts a floating phase for detecting a phase switching time point, the motor controller enables that at least one transistor within the switch circuit is operated in a linear region. The motor controller is configured to reduce switching noise of the three-phase motor and increase a success rate of phase switching.