Motor Controller Resonant Control for Harmonic Current Distortion
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Solution Overview
Problem
Existing motor control systems face challenges in accurately controlling three-phase motors due to non-sinusoidal back electromotive forces (EMFs) and distortions caused by dead time in inverter switching, leading to harmonic distortions in motor phase currents.
Innovation Solution
A motor controller integrated circuit (IC) with a processor core and three-phase inverter that converts sense current signals into a rotating reference frame, implements a resonant controller to attenuate harmonic components, particularly at the motor's speed harmonic, and generates control signals to produce sinusoidal motor phase currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional motor control is used without resonant controllers, then the control system is simpler, but harmonic distortions in motor phase currents increase
Solution Approach 1:
The control system is segmented by adding separate resonant controllers for each phase (resonant controller 272 for phase R, resonant controller 274 for phase S, resonant controller 276 for phase T). Each resonant controller independently processes its phase current to attenuate specific harmonic frequencies, allowing targeted correction of waveform distortions without requiring complete system redesign
Solution Approach 2:
Resonant controllers serve as intermediary components between the inverter and motor phases. These controllers act as mediators that detect harmonic distortions in phase currents and generate compensating signals to cancel out the distortions, thereby improving current waveform precision without directly modifying the motor or inverter hardware
2Manufacturing precision
If resonant controllers are added to attenuate harmonics, then current waveform precision improves, but device complexity increases
Solution Approach 1:
Each resonant controller is configured with specific tuning parameters targeted at dominant harmonic frequencies (such as 5th and 7th harmonics) affecting its respective phase. This localized optimization allows each controller to focus computational resources on eliminating specific harmful harmonics rather than attempting to address all frequency components across the entire system
Solution Approach 2:
The resonant controllers dynamically adjust their transfer function parameters based on operating conditions. By changing parameters such as resonant frequency tuning and gain values according to motor speed and load conditions, the system maintains high current waveform precision across varying operational ranges without requiring a complete increase in hardware complexity
3Reliability
If dead time is used in inverter switching, then switching reliability improves, but harmonic distortions increase
Solution Approach 1:
The resonant controllers implement feedback mechanisms that continuously monitor phase currents for harmonic distortions generated by inverter dead time. By detecting these distortions in real-time and generating compensating control signals, the system eliminates the harmful effects of dead time-induced harmonics while maintaining the necessary dead time for reliable switching operation
Solution Approach 2:
The system converts the harmful effect of dead time-induced harmonic distortions into a controllable parameter. By deliberately designing resonant controllers that target and cancel these specific harmonics, the patent transforms what would be an unwanted side effect into a manageable aspect of the control strategy, allowing dead time to be used for switching reliability without sacrificing current waveform quality
Data Source
AI summary
A motor controller integrated circuit (IC) includes a storage device containing software. The IC also includes a processor core coupled to the storage device. The processor core has an output adapted to be coupled to a motor. The processor core is configured to execute the software to implement a resonant controller at a frequency that is a harmonic of a speed of a motor.