Electric Motor Control Apparatus for Torque Ripple Reduction
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Solution Overview
Problem
The control apparatus for electric motors experiences a loss due to response delay, particularly during 1 PLS control, which results in slow torque output and increased noise and vibration due to limited commutation timings and the need to balance applied voltage, induction voltage, and impedance.
Innovation Solution
A control apparatus that includes a rectangular wave inverter and a voltage converting section, where the output voltage is synchronized with the electrical angle of the rotator, allowing for multi-phase rectangular wave voltages with specific ripple patterns to reduce torque ripple and improve response efficiency, even during 1 PLS control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If 1 PLS control is used in the inverter, then switching loss is reduced, but torque response becomes slow and loss increases due to limited commutation timings
Solution Approach 1:
The patent applies dynamics by making the DC voltage from the power supply dynamic rather than fixed. The voltage is adjusted in real-time based on the electrical angle of the motor, allowing the system to adapt its characteristics to optimize both switching loss and torque response speed under different operating conditions
Solution Approach 2:
The patent changes the parameter of DC voltage level dynamically. By varying the voltage magnitude according to the electrical angle, the system can maintain optimal performance across different commutation phases, resolving the contradiction between low switching loss and fast torque response
2Device complexity
If the DC voltage is fixed, then control is simplified, but torque ripple increases and noise and vibration are enhanced
Solution Approach 1:
The patent transforms the fixed DC voltage into a dynamic voltage that changes with the electrical angle. This dynamic adjustment compensates for torque ripple without requiring complex control algorithms, achieving a balance between control simplicity and torque smoothness
Solution Approach 2:
The patent applies preliminary action by pre-adjusting the DC voltage level before commutation based on the electrical angle. This anticipatory voltage adjustment prevents torque ripple from occurring in the first place, rather than attempting to correct it afterward
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
This approach reduces torque ripple and associated losses, minimizing noise and vibration by ensuring the inverter can respond effectively to changes in the electrical angle, enhancing the motor's efficiency and performance.
Implementation Method 1
a voltage converting section that raises or lowers an output voltage of a direct-current power supply and applies the voltage onto the rectangular wave inverter
Implementation Method 2
Here, the inverter 117 is a rectangular wave inverter, and performs PWM (Pulse Width Modulation) control or alternatively one pulse (1 PLS) control depending on a switching flag inputted from the inverter control method determining section 127
Implementation Method 3
with a stator for generating a rotating magnetic field by the applied three-phase voltages and thereby revolving the rotator
Implementation Method 4
with a stator for generating a rotating magnetic field by the applied three-phase voltages and thereby revolving the rotator
Implementation Method 5
The resolver 101 detects a mechanical angle of the rotator of the electric motor 10, and outputs an electrical angle θm corresponding to the detected mechanical angle
Data Source
AI summary
A control apparatus for an electric motor provided with a rotator having a permanent magnet and with a stator for generating a rotating magnetic field by an applied voltage and revolving the rotator includes: a rectangular wave inverter that applies a rectangular wave voltage onto the stator of the electric motor to drive the electric motor; a voltage converting section that raises or lowers an output voltage of a direct-current power supply and applies the voltage onto the rectangular wave inverter; an electrical angle acquiring section that acquires an electrical angle of the rotator of the electric motor; and an output voltage command generating section that generates a command for instructing the voltage converting section to output an electrical-angle synchronized voltage whose amplitude ripples in synchronization with a change of the electrical angle of the rotator acquired by the electrical angle acquiring section. In response to the command generated by the output voltage command generating section, the voltage converting section raises or lowers the output voltage of the direct-current power supply to a voltage indicated by the command and applies the voltage onto the rectangular wave inverter. This reduces a loss caused by a response delay of the electric motor.