Battery Heating Inverter Control With Limited Motor Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion systems in vehicles face issues with unintended large motor torque during temperature-increase control of storage batteries, which can cause the vehicle to move despite being parked, due to sudden large currents supplied to the rotary electric machine.
Innovation Solution
A power conversion apparatus with synchronized switching control of upper and lower arm switches to gradually increase current through the rotary electric machine windings within a torque limit, ensuring the torque remains below the parking brake holding torque, thereby preventing unintended vehicle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large current is supplied to the rotary electric machine for temperature-increase control of the battery, then the temperature-increase control is effective, but unintended large motor torque is generated causing the vehicle to move
Solution Approach 1:
The control unit dynamically adjusts the current supplied to the rotary electric machine based on vehicle state. When the vehicle is stopped, the control unit limits the current to prevent excessive torque generation, while still enabling temperature-increase control through controlled current flow via the neutral point connection.
Solution Approach 2:
The patent introduces an intermediary control mechanism that manages current flow through the neutral point connection between the inverter and rotary electric machine. This intermediary control path allows temperature-increase control to be performed without directly supplying large current that would generate harmful torque, thus mediating between the conflicting requirements.
2Reliability
If current control is applied to limit torque during temperature-increase control, then vehicle movement is prevented, but the temperature-increase efficiency is reduced
Solution Approach 1:
The control unit applies partial current control by connecting the neutral point to the inverter output, allowing a controlled amount of current to flow through the rotary electric machine windings. This partial action is sufficient to generate the necessary heat for temperature-increase control while remaining below the threshold that would generate harmful torque, thus achieving both reliability and productivity.
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 effectively controls current flow to prevent unintended torque generation, allowing safe temperature-increase of batteries without moving the vehicle, while reducing noise and enabling a smaller capacitor design.
Implementation Method 1
a power converter having series connections of upper arm switches and lower arm switches and configured to convert DC power supplied from a battery into AC power by switching control
Implementation Method 2
a rotary electric machine having windings, the rotary electric machine being connected to an axle of a vehicle
Implementation Method 3
the control unit performs temperature-increase control of the battery by performing switching control of the upper arm switches and the lower arm switches so that a current flows to the battery via the power converter and the windings
Data Source
AI summary
A power conversion apparatus includes a power converter configured to convert DC power supplied from a battery into AC power by switching control, and is configured to supply the AC power from the power converter to a rotary electric machine having windings. Further, the power conversion apparatus includes a control unit that performs temperature-increase control of the battery by performing switching control of upper arm switches and lower arm switches so that a current flows to the battery via the power converter and the windings. In the temperature-increase control while the vehicle is stopped, the control unit controls the current so that a current value of the rotary electric machine gradually increases within a current control range in which a torque of the rotary electric machine is less than an upper limit torque.