Rotating Electric Machine Control Device Torque Ripple Reduction
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Solution Overview
Problem
Existing rotating electric machine control devices face challenges in effectively coordinating the control of multiple systems, particularly in IPM motors, due to differences in d-axis and q-axis inductance, leading to inefficiencies in torque control and increased noise and vibration.
Innovation Solution
A rotating electric machine control device with a machine-electronics integrated configuration, utilizing two control units that communicate to optimize current supply phase differences between motor windings, reducing torque ripple and heat generation, and distributing electric current evenly between systems to improve output torque and reduce temperature-dependent errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If d-axis current control is performed in the same manner as q-axis in a multi-system control configuration, then control simplicity is maintained, but torque ripple increases and control accuracy deteriorates due to unaccounted reluctance torque effects
Solution Approach 1:
The patent applies different control strategies to different axes: the q-axis uses conventional feedback control while the d-axis incorporates additional reluctance torque compensation. This local differentiation allows each axis to be controlled according to its specific characteristics, improving overall torque control accuracy without unnecessarily complicating the entire control system.
Solution Approach 2:
The patent modifies the d-axis current control by introducing a compensation term that accounts for reluctance torque effects. This parameter change in the control law (adding the reluctance torque compensation component) enables more accurate torque control while maintaining a relatively simple control architecture.
2Reliability
If instruction values are transmitted from master control unit to slave control unit, then coordinated control is achieved, but communication overhead increases and control response time is delayed
Solution Approach 1:
The master control unit pre-calculates and transmits instruction values to the slave control unit before they are needed for execution. This preliminary action allows the slave unit to have the instruction values ready, reducing the actual control response time while maintaining coordinated control through the pre-established communication framework.
3Device complexity
If current supply phase difference between motor windings is not optimized, then control simplicity is maintained, but torque ripple increases and noise and vibration are generated
Solution Approach 1:
The patent dynamically adjusts the current supply phase difference between motor windings based on operating conditions. By making the phase difference a variable parameter rather than a fixed value, the system can optimize torque output and minimize torque ripple and noise across different operating ranges without requiring a fundamentally complex control algorithm.
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 improved torque output, reduced noise and vibration, and enhanced control accuracy by optimizing current distribution and communication between control units, effectively addressing the inefficiencies in IPM motor control.
Implementation Method 1
a rotating electric machine control device with a machine-electronics integrated configuration, utilizing two control units that communicate to optimize current supply phase differences between motor windings
Implementation Method 2
distributing electric current evenly between systems to improve output torque and reduce temperature-dependent errors
Data Source
AI summary
A rotating electric machine control device has an electronic control unit, or an ECU that controls driving of a motor having motor windings, and includes mutually-communicable plural control units. The control unit includes a basic instruction calculation unit, a field-weakening calculation unit, and a current control calculation unit and a PWM (pulse width modulation) output unit. The current control calculation unit and the PWM output unit generate a PWM signal based on d-axis current instruction values and q-axis current instruction values that are calculated based on basic current instruction values and field-weakening d-axis current instruction value. At least a part of the instruction values used for generation of the PWM signal is shared by the plural control units.