Multiphase Motor Control for DC Bus Current Ripple
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric motor control systems in hybrid and electric vehicles generate current oscillations on the DC high-voltage bus, leading to negative impacts on electromagnetic compatibility, battery state of charge accuracy, battery lifespan, and acoustic and structure-borne vibrations, which affect the overall performance and reliability of the electric power train.
Innovation Solution
A dynamic control system for multiphase electric motors that includes a rotor voltage chopper and a multiphase voltage inverter, powered via a DC high-voltage bus, which determines dynamic corrections for torque ripple to eliminate current ripples on the bus, thereby improving acoustic performance and reducing motor vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional motor control systems are used, then the motor can deliver required torque, but current oscillations are generated on the DC high-voltage bus
Solution Approach 1:
The control system continuously monitors the actual torque output and current measurements, compares them with reference values, and dynamically adjusts the inverter switching signals to minimize torque ripple and current oscillations. This closed-loop feedback mechanism enables real-time correction of harmful oscillations while maintaining required torque delivery.
Solution Approach 2:
The system dynamically modifies control parameters including PWM duty cycles, switching frequencies, and current references based on operating conditions. By adjusting these parameters in real-time, the system optimizes torque delivery while suppressing current oscillations on the DC bus.
2Object-affected harmful factors
If torque ripple is minimized, then acoustic performance improves, but control system complexity increases
Solution Approach 1:
The control system pre-calculates optimal switching patterns and torque references based on predicted operating conditions and load requirements. By preparing correction signals in advance based on anticipated torque ripple, the system reduces acoustic vibrations without requiring complex real-time computations during operation.
3Reliability
If current oscillations are eliminated, then battery lifespan is improved, but measurement precision of state of charge is affected
Solution Approach 1:
The control system introduces intermediate filtering and compensation stages between the motor drive and battery measurement circuits. These intermediary elements isolate the measurement system from harmful current oscillations while preserving accurate state of charge information, allowing both battery protection and precise measurement.
Data Source
AI summary
A system and method for controlling a multiphase electric motor fitted to a motor vehicle. The motor includes a rotor powered by a voltage chopper or a rotor with permanent magnets and a stator powered by a multiphase voltage inverter. The multiphase voltage inverter is powered via a high-voltage DC bus. The control system receives as an input a torque setpoint of an electric-vehicle computer. The system also includes a system for the dynamic control of the torque setpoint to determine a dynamic correction of torque ripple and a device for determining setpoints for powering the electric motor as a function of the torque setpoint and of the dynamic correction of torque ripple.