Rotary Electric Machine Current Control for Uniform Stop-State Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotary electric machine systems face challenges in efficiently generating heat when the battery is at low temperature and the machine is stopped, as current concentrates on certain phases, limiting heat generation and potentially failing to meet thermal demands.
Innovation Solution
A control device that controls phase currents in a rotary electric machine system by alternating d-axis current flow on both positive and negative sides in all phases, distributing heat generation across all switches in the inverter, thereby enhancing heat production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If d-axis voltage is applied via inverter switching control to supply d-axis current to the rotary electric machine, then Joule heat is generated in the battery raising the temperature, but current concentrates on certain phases limiting heat generation efficiency
Solution Approach 1:
The patent applies local quality by making the d-axis current alternate between positive and negative sides in each phase, creating different current flow patterns in different phases. This causes different switches in the inverter to operate, distributing heat generation across multiple switches rather than concentrating current in specific phases, thereby improving overall heat generation efficiency while raising battery temperature.
Solution Approach 2:
The patent employs dynamics by alternating the d-axis current between positive and negative sides in each phase based on the electrical angle of the rotary electric machine. This dynamic current reversal ensures that different switches in the inverter are activated at different times, distributing the heat generation load across all switches and improving the overall heat generation efficiency.
2Temperature
If d-axis current is supplied to generate heat in the battery, then the battery temperature rises, but the current flow pattern may cause uneven heat distribution
Solution Approach 1:
The patent applies local quality by making the d-axis current alternate between positive and negative sides in each phase, creating different current flow patterns in different phases. This causes different switches in the inverter to operate, distributing heat generation across multiple switches rather than concentrating current in specific phases, thereby improving overall heat generation efficiency while raising battery temperature.
3Manufacturing precision
If phase current is controlled to alternate on both positive and negative sides in all phases, then heat is generated uniformly across all switches, but the control complexity increases
Solution Approach 1:
The patent employs periodic action by alternating the d-axis current between positive and negative sides in each phase based on the electrical angle of the rotary electric machine. This periodic current reversal ensures that different switches in the inverter are activated at different times in a systematic manner, distributing the heat generation load across all switches uniformly while managing control complexity through regular periodic patterns.
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 allows for efficient heat generation in the rotary electric machine system by ensuring heat is generated uniformly across all phases, preventing overheating and ensuring sufficient heat production meets thermal demands.
Implementation Method 1
This causes Joule heat to be generated in the battery, raising the temperature of the battery
Implementation Method 2
the current control unit controls the phase current so that the d-axis current becomes an AC d-axis current and the phase current that alternates on both positive and negative sides flows in each phase of the winding
Data Source
AI summary
A control device is applied to a rotary electric machine system including a rotary electric machine having polyphase winding and an inverter that adjusts the phase current of each phase in the winding, and performs power control of the rotary electric machine using the inverter. The control device includes a current setting unit that sets phase current command values for each phase of the winding based on an electrical angle of the rotary electric machine and a d-axis current command value and a q-axis current command value of the rotary electric machine, a current control unit that controls the phase current flowing through each phase based on the phase current command values set by the current setting unit, and a determination unit that determines whether a heat generation request is present in the rotary electric machine system. When it is determined that a heat generation request is present and the rotary electric machine is in a rotational stop state, the current setting unit sets an AC d-axis current as the d-axis current command value in order to pass a phase current that alternates on both positive and negative sides through each phase of the winding, and sets a phase current command value based on the AC d-axis current.