Motor Drive Controller Flux Adjustment for Torque Ripple
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Solution Overview
Problem
Electric motor drive controllers with reduced capacitance face challenges in maintaining constant average torque and efficiency due to the absence of high capacitance electrolytic capacitors, leading to torque and efficiency losses, and difficulties in envelope control.
Innovation Solution
An electric motor drive controller with a rectifier, inverter, and an adjustment control module that measures instantaneous motor current to determine flux and torque component values, adjusting operations to maintain average flux and torque values similar to demand values, even with low capacitance capacitors, using PWM voltage and advanced control algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high capacitance electrolytic capacitors are used in motor drive controllers, then the capacitors can maintain constant average torque and efficiency, but the motor drive controller becomes large and expensive
Solution Approach 1:
The patent removes the large electrolytic capacitors from the motor drive controller, extracting the energy storage function to a minimal capacitance capacitor while using the control algorithm to compensate for the resulting torque and efficiency variations
Solution Approach 2:
The patent changes the control parameters by implementing a new control algorithm that adjusts the inverter switching patterns and motor phase currents in real-time to compensate for the reduced capacitance, thereby maintaining constant average torque and efficiency without requiring large capacitors
2Reliability
If high capacitance electrolytic capacitors are used in motor drive controllers, then the capacitors can maintain constant average torque and efficiency, but the motor drive controller becomes expensive
Solution Approach 1:
The patent removes the expensive high-capacitance electrolytic capacitors from the system, replacing them with a low-capacitance capacitor and a control algorithm that compensates for the performance degradation, thereby reducing material costs
Solution Approach 2:
The patent substitutes the passive electrical component (large capacitor) with an active control system that uses sensors, processors, and algorithms to achieve the same torque and efficiency regulation, replacing hardware-based energy storage with software-based control
3Weight of stationary object
If capacitance is reduced in motor drive controllers, then the size and expense of the controller is reduced, but torque production has ripple and efficiency is lost
Solution Approach 1:
The patent implements a feedback control algorithm that continuously monitors motor phase currents, torque production, and efficiency metrics, then adjusts the inverter switching patterns in real-time to compensate for the ripple and efficiency losses caused by reduced capacitance
Solution Approach 2:
The patent employs periodic control actions by synchronizing the compensation algorithm with the AC input voltage frequency (twice the frequency), applying corrective switching patterns at regular intervals to cancel out the torque ripple and efficiency variations caused by the low-capacitance design
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
The solution enables constant average torque and increased efficiency in electric motors, while reducing the size and cost of motor drive controllers, and providing accurate envelope control without the need for bulky high-capacitance capacitors.
Implementation Method 1
a rectifier configured to convert an AC input voltage having a frequency to a DC voltage
Implementation Method 2
an inverter electrically coupled to the DC link and configured to generate a three phase pulse width modulated (PWM) voltage to drive the electric motor
Implementation Method 3
The motor drive controller then supplies a chopped DC voltage to the electric motor through an inverter, which uses the power to drive a load
Data Source
AI summary
An air moving system including an electric motor, a load coupled to the electric motor, and a motor drive controller coupled to the electric motor is provided. A DC voltage generated from an AC input voltage provided to the electric motor tends towards zero at about twice a frequency of the AC input voltage. The motor drive controller includes an adjustment control module configured to receive a measurement of an instantaneous motor current value for the electric motor, determine a flux component value based on the instantaneous motor current value, and determine, based at least in part on the flux component value and a flux component demand value, an adjusted flux component demand value that causes the motor drive controller to adjust an operation such that an average flux component value based on the flux component value is substantially similar to the flux component demand value.