Inverter Transistor Control for Collision Energy Dissipation
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Solution Overview
Problem
In vehicles equipped with three-phase alternating-current motors and inverters, there is a risk of transistor damage and permanent magnet demagnetization due to uncontrolled discharge of electric charge from smoothing capacitors during collisions, leading to potential overheating and improper current distribution.
Innovation Solution
The implementation of a control method that turns off all upper arm transistors and turns on all lower arm transistors of the inverter after a collision detection, ensuring that counter electromotive force currents flow through diodes and lower arm transistors, preventing concentration of current through a single transistor and reducing the risk of demagnetization, while applying a lower input voltage to upper arm transistors to manage charge discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the upper and lower arms of the inverter are fixed in a conductive state after collision to discharge capacitor charge, then the capacitor is discharged, but large current flows through the transistors causing potential damage
Solution Approach 1:
The patent applies dynamics by making the transistor states changeable rather than fixed. After collision detection, the control unit dynamically switches transistor states based on the generation status of counter electromotive force: initially fixing arms in conductive state for discharge, then later switching to allow counter electromotive force current flow. This dynamic adaptation resolves the contradiction between needing fixed conductive state for discharge and avoiding large current damage.
Solution Approach 2:
The patent changes the operational parameters of the transistors based on collision stage. It monitors counter electromotive force generation and adjusts transistor conductivity accordingly - maintaining conductive state initially for capacitor discharge, then switching to non-conductive state when counter electromotive force is generated to prevent large current flow. This parameter change resolves the contradiction between discharge efficiency and transistor protection.
2Loss of energy
If current from counter electromotive force flows simultaneously with capacitor discharge current through the inverter, then the capacitor is discharged, but the transistors are adversely influenced
Solution Approach 1:
The patent uses dynamic control to prevent simultaneous flow of capacitor discharge current and counter electromotive force current through the inverter. The control unit monitors counter electromotive force generation and dynamically switches the inverter's conductive state: maintaining initial conductive state for capacitor discharge, then switching to non-conductive state when counter electromotive force is generated. This temporal separation resolves the contradiction between discharge and protection.
3Loss of energy
If half-wave current flows through the motor generator phases during capacitor discharge, then the capacitor is discharged, but the permanent magnet may be demagnetized
Solution Approach 1:
The patent applies dynamic control to prevent half-wave current flow through the motor generator during capacitor discharge. The control unit monitors motor generator rotation and counter electromotive force generation, and dynamically adjusts inverter transistor states: initially allowing discharge current flow, then switching to non-conductive state when counter electromotive force is generated to prevent current flow through the motor generator. This resolves the contradiction between discharge and magnet protection.
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 effectively discharges the smoothing capacitor while protecting the inverter and motor from overheating and demagnetization, ensuring safe and controlled energy dissipation during collisions.
Implementation Method 1
a smoothing capacitor that smoothes voltage between the inverter and the electrical storage unit
Implementation Method 2
a plurality of upper arm transistors, each of which tends to reduce its resistance as an input voltage increases and turns on when an input voltage higher than a predetermined value is applied
Implementation Method 3
when counter electromotive force is generated in the three-phase alternating-current motor, the control unit turns off all the upper arm transistors of the inverter and turns on all the lower arm transistors of the inverter
Data Source
AI summary
After a collision has been detected, all the upper arm transistors of inverters (41, 42) are turned off, and all the lower arm transistors of the inverters are turned on. Then, when no counter electromotive force is generated in any one of motors (MG1, MG2), a gate voltage (V2) lower than a gate voltage (V1) at which each upper arm transistor completely turns on is applied to at least any one of the upper arm transistors of the inverters (41, 42), and at least any one of the lower arm transistors of the inverters (41, 42), which is serially connected to the at least any one of the upper arm transistors to which the gate voltage (V2) is applied, is turned on.