Power Conversion Device Discharge Control
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Solution Overview
Problem
In power conversion devices for vehicles, when an auxiliary device is connected between the battery and the step-up/down converter, it can be difficult to execute discharge control of the second capacitor due to the loss of operation power from the first capacitor before a discharge instruction signal is received, especially during vehicle collisions.
Innovation Solution
A power conversion device configuration that includes a voltage sensor to measure the inter-terminal voltage of the first capacitor, a control device with an abnormality determination unit and a control unit to initiate discharge control when the control voltage is below a threshold and the inter-terminal voltage is also below a second threshold, ensuring the second capacitor is discharged even when the auxiliary device is connected between the battery and the step-up/down converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an auxiliary device is connected between the battery and the step-up/down converter, then the auxiliary device can operate during collision, but the operation power from the first capacitor to the motor ECU is consumed before the discharge instruction signal is received
Solution Approach 1:
The control device executes discharge control of the second capacitor in advance when voltage drops are detected, before receiving the discharge instruction signal from the external ECU. This preliminary action ensures that residual charge is discharged even when the auxiliary device consumes power from the first capacitor, preventing the power loss issue during collision.
2Extent of automation
If the control device waits for the discharge instruction signal from external ECU, then normal control procedure is followed, but power from the first capacitor may be consumed before the signal is received
Solution Approach 1:
The control device monitors the voltage of the first capacitor in real-time and executes discharge control when voltage drops below a predetermined threshold. This feedback mechanism allows the system to respond proactively to power consumption conditions, eliminating the delay of waiting for the discharge instruction signal while maintaining automated control.
3Speed
If discharge control is executed immediately upon collision, then residual charge is discharged quickly, but the control device may not have received the discharge instruction signal yet
Solution Approach 1:
The control device performs discharge control as a preliminary action when voltage drops are detected, without waiting for the discharge instruction signal. This approach achieves quick discharge of residual charge while the system independently determines the appropriate timing based on voltage conditions, eliminating the need to wait for external signals during emergency situations.
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 configuration allows for reliable execution of discharge control of the second capacitor, preventing power loss and ensuring continuous operation by initiating discharge control proactively when abnormal conditions are detected, such as during vehicle collisions.
Implementation Method 1
a first capacitor that is provided between the first DC power supply and the step-up/down converter
Implementation Method 2
a voltage sensor configured to measure an inter-terminal voltage of the first capacitor
Implementation Method 3
a second capacitor that is provided between the step-up/down converter and the inverter
Data Source
AI summary
The present power conversion device includes an inverter, a step-up/down converter, a first capacitor, a second capacitor, a voltage sensor, a control device, and a backup power supply. The auxiliary device is connected between the first DC power supply and the step-up/down converter, and the control device includes an abnormality determination unit configured to determine that an abnormality has occurred when a control voltage is equal to or lower than a first threshold value, and a control unit configured to execute discharge control when the abnormality determination unit determines that the abnormality has occurred and an inter-terminal voltage measured by the voltage sensor is equal to or lower than a second threshold value.