Power Conversion System Motor Speed Reduction for Capacitor Discharge
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Solution Overview
Problem
Existing hybrid automobile power conversion systems face challenges in swiftly releasing high voltage charges from secondary smoothing capacitors after a collision or power stop without losing the power supply for the inverter control circuit, and existing methods either risk losing the inverter control circuit power supply or fail to consider the voltage's ability to drive the inverter control circuit.
Innovation Solution
A power conversion system that includes a direct current power supply, step-up converter, inverter, secondary smoothing capacitor, inter-terminal voltage detecting means, motor rotation speed detecting means, and a discharge determination indicator, which controls motor rotation speed reduction to release the charge accumulated in the capacitor without losing the power supply for the inverter control unit, ensuring the inter-terminal voltage remains within a safe threshold to prevent electrocution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If motor rotation speed is reduced to restrict voltage rise from induction voltage, then discharge time of secondary smoothing capacitor is reduced, but power supply for inverter control circuit may be lost
Solution Approach 1:
The system performs preliminary action by detecting inter-terminal voltage before discharge operations and establishing voltage thresholds in advance. The control unit prepares to stop motor rotation speed reduction control when voltage drops below the threshold, ensuring power supply stability is maintained before critical failure occurs.
Solution Approach 2:
The system implements feedback by continuously detecting inter-terminal voltage during discharge operations and using this information to control the motor rotation speed reduction. When voltage drops below the threshold, the system automatically adjusts motor rotation speed to prevent power supply loss, creating a closed-loop control system that balances discharge speed with power supply stability.
2Productivity
If motor rotation speed is reduced to release high voltage charge swiftly, then discharge operation efficiency is improved, but inter-terminal voltage may drop below threshold needed to drive inverter control circuit
Solution Approach 1:
The control unit continuously monitors inter-terminal voltage and uses this feedback to dynamically adjust motor rotation speed. When voltage approaches or drops below the threshold, the system automatically reduces or stops motor rotation speed reduction control, ensuring the inverter control circuit maintains adequate power supply while still achieving efficient discharge when voltage is sufficient.
Solution Approach 2:
The system applies dynamic control by adjusting motor rotation speed based on real-time inter-terminal voltage conditions. Rather than maintaining a fixed rotation speed, the system adaptively modifies rotation speed to match voltage levels, enabling efficient discharge operations when voltage is high while preventing voltage drop below operational thresholds.
3Speed
If discharge operation is performed without considering inter-terminal voltage threshold, then charge release speed is maximized, but inverter control circuit may malfunction due to insufficient power supply
Solution Approach 1:
The system performs preliminary detection of inter-terminal voltage and comparison with predetermined thresholds before initiating or continuing discharge operations. This preliminary action ensures that discharge operations only proceed when voltage is sufficient to maintain inverter control circuit functionality, preventing malfunction while still enabling rapid charge release when conditions are favorable.
Solution Approach 2:
The system implements beforehand cushioning by establishing a safety margin through the predetermined voltage threshold. This threshold acts as a cushion that prevents voltage from dropping too low during discharge operations, ensuring the inverter control circuit maintains adequate power supply headroom and avoids malfunction even during rapid charge release.
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 system effectively releases high voltage charges from the secondary smoothing capacitor after motor rotation speed reduction, maintaining the power supply for the inverter control unit and ensuring safety by controlling the inter-terminal voltage, thus preventing electrocution and enabling swift discharge operations.
Implementation Method 1
a secondary smoothing capacitor that smooths voltage between the step-up converter and inverter
Implementation Method 2
the voltage of the secondary smoothing capacitor rises due to induction voltage from the motor
Data Source
AI summary
When a motor rotation speed is equal to or greater than a predetermined rotation speed when an automobile collision is detected or when power stops, a motor rotation speed reduction control is carried out by an inverter control unit, and when an inter-terminal voltage of a secondary smoothing capacitor drops below a predetermined voltage during the motor rotation speed reduction control, the motor rotation speed reduction control is stopped, whereby induction voltage caused by motor rotation is applied to the secondary smoothing capacitor, the inter-terminal voltage of the secondary smoothing capacitor is raised, and the motor rotation speed reduction control is carried out while keeping the inter-terminal voltage of the secondary smoothing capacitor within an operating voltage range of the inverter control unit.