Motor Inverter Switch Timing for Battery Warming Heat Control
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Solution Overview
Problem
Existing motor system control devices struggle to efficiently generate heat for thermal demands such as battery warming and cabin heating in vehicles, particularly when the battery is cold, leading to inefficiencies and potential overheating risks.
Innovation Solution
A control device that adjusts the transition times for turning on and off semiconductor switches in an inverter to increase switching-loss, combined with d-axis energization to flow d-axis current when the vehicle is stationary, thereby promoting heat generation in the motor system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the transition time for turning on/off switches is increased to generate heat, then heat generation efficiency is improved, but switching loss increases and may cause overheating
Solution Approach 1:
The control device dynamically adjusts the transition time of switch operations based on real-time temperature conditions. When temperature is low, transition time is extended to generate heat; when temperature approaches safe limits, transition time is reduced to minimize switching loss and prevent overheating. This dynamic adjustment resolves the contradiction between heat generation efficiency and switching loss.
Solution Approach 2:
The invention changes the operational parameters of the semiconductor switches by varying the transition time (turn-on and turn-off durations) according to temperature conditions. This parameter modification allows the system to optimize between heat generation and energy loss, converting a fixed parameter system into a variable one that adapts to thermal conditions.
2Temperature
If d-axis current is flowed to generate heat when battery is cold, then battery warming efficiency is improved, but energy consumption increases
Solution Approach 1:
The control device implements periodic alternation between discharge control (flowing d-axis current to generate heat) and charge control (lowering d-axis voltage to return energy to battery). This periodic action allows the system to generate heat when needed while recovering energy during charge phases, improving overall energy efficiency and reducing net energy consumption for battery warming.
Solution Approach 2:
The system uses feedback from temperature monitoring to control the d-axis current flow. When battery temperature is low, d-axis current is applied to generate heat; when temperature reaches the target range, the current is reduced or stopped. This feedback mechanism ensures energy is consumed only when necessary for heating, optimizing the balance between warming efficiency and energy consumption.
3Temperature
If switch transition time is extended to meet thermal demands, then heat generation is improved, but system reliability decreases due to overheating risks
Solution Approach 1:
The control device continuously monitors temperature conditions and uses this feedback to adjust switch transition times. When temperature is within safe ranges, transition time is extended to generate heat; when temperature approaches critical thresholds, transition time is reduced to prevent overheating. This closed-loop feedback control maintains system reliability while achieving thermal demands.
Solution Approach 2:
The system takes preliminary anti-action by reducing switch transition time before overheating occurs. The control device monitors temperature trends and proactively adjusts switching parameters to prevent thermal runaway, thereby maintaining system reliability while still meeting heat generation 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
This approach enables efficient heat generation in the motor system, effectively warming the battery and meeting thermal demands while minimizing overheating risks and ensuring safe operation.
Implementation Method 1
This causes the control device to generate Joule heat in the battery, thereby warming it
Implementation Method 2
the switch control unit causes at least one of a transition time for turning on each of the plurality of switches, and 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
Data Source
AI summary
A control device is applied to a motor system including a motor having polyphase windings and an inverter that adjusts a phase-current in a winding of each phase by turning on and off a plurality of switches. Each switch 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 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 heat generation request, 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.