Inverter Switch Timing for Motor System Heat Generation Control
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Solution Overview
Problem
Existing motor system control devices inefficiently generate heat for thermal demands beyond battery warming, such as cabin heating, and risk overheating due to uncontrolled switching-loss in inverters.
Innovation Solution
A control device that adjusts the transition times of semiconductor switches in an inverter to increase switching-loss for heat generation, combined with d-axis energization to distribute heat generation across phases, and includes feedback control to manage temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the inverter performs heat generation by extending switch transition times, then heat generation efficiency is improved, but switching-loss increases uncontrollably causing overheating risk
Solution Approach 1:
The control device monitors the actual temperature of the inverter and adjusts the switch transition times dynamically. When temperature exceeds a threshold, the control device reduces the transition time extension to prevent overheating, creating a closed-loop feedback control system that balances heat generation efficiency with safety.
Solution Approach 2:
The switch transition times are made dynamic rather than fixed. The control device continuously adjusts the transition time extension based on real-time temperature conditions, allowing the system to adapt between efficient heat generation mode and safe operation mode as thermal conditions change.
2Adaptability or versatility
If d-axis energization is used to distribute heat generation across phases, then thermal demand coverage is improved, but system complexity increases
Solution Approach 1:
The d-axis energization mechanism serves multiple functions: it distributes heat generation across different phases to meet various thermal demands (cabin heating, battery warming) while maintaining a unified control approach through the existing dq-axis transformation framework, avoiding the need for separate control systems for different thermal requirements.
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
Efficient heat generation is achieved across the motor system, addressing thermal demands while preventing overheating and ensuring safe operation.
Implementation Method 1
This causes the control device to generate Joule heat in the battery, thereby warming it... enables heat generation due to an increase in a switching-loss at each switch of the inverter
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A control device (40) is applied to a motor system including a motor (10) having polyphase windings (11) and an inverter (20) that adjusts a phase-current in a winding of each phase by turning on and off a plurality of switches (21, 22). Each of the switches being a semiconductor switching device. The control device controls each of the plurality of switches. The control device includes: a determination unit configured to determine whether there is a heat generation request in the motor system, and a switch control unit configured to turn on and off the plurality of switches respectively. When it is determined that there is the heat generation request, the switch control unit causes at least one of: (1) a transition time for turning on each of the plurality of switches; and (2) a transition time for turning off each of the plurality of switches, to be longer than when it is determined that there is no heat generation request.