Inverter Control Device Backup Power Switching for Fail-Safe
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Solution Overview
Problem
Existing rotating electrical machine control devices may fail to perform fail-safe operations when the power supply from the low voltage DC power supply is cut off, especially due to wire disconnection or other issues, leading to inadequate control of the inverter in scenarios like overcurrent or overvoltage.
Innovation Solution
A rotating electrical machine control device with an electronic control unit that includes a backup power supply using the high voltage DC power supply, allowing the inverter to perform fail-safe operations even if the low voltage DC power supply is disrupted, by switching to the backup power source when the low voltage supply falls below a certain threshold and ensuring the inverter can execute switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter control device operates only with the low voltage DC power supply, then the device complexity is reduced, but the reliability deteriorates when wire disconnection or power supply failure occurs
Solution Approach 1:
The patent applies preliminary action by providing a backup power supply that uses the high voltage DC power supply as its source. This backup power supply is prepared in advance and automatically activates when the low voltage DC power supply fails or experiences wire disconnection, ensuring that the inverter control device can perform fail-safe control operations without interruption.
Solution Approach 2:
The patent uses an intermediary approach by introducing a backup power supply as a mediator between the high voltage DC power supply and the inverter control device. This intermediary backup power supply ensures power continuity to the control device even when the primary low voltage DC power supply fails, thereby maintaining system reliability.
2Reliability
If a separate fail-safe circuit is provided to ensure inverter operation during power supply failure, then the reliability of fail-safe control is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by making the inverter control device itself multi-functional. The control device performs both normal control functions when powered by the low voltage DC power supply and fail-safe control functions when powered by the backup power supply. This eliminates the need for a separate dedicated fail-safe circuit, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The patent merges the fail-safe control function into the existing inverter control device rather than providing a separate fail-safe circuit. By combining these functions, the system achieves reliable fail-safe operation without increasing device complexity, as the same control device handles both normal and emergency control tasks.
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
Enables the inverter to perform fail-safe control operations without the need for additional fail-safe circuits, ensuring the rotating electrical machine's safe operation even if the primary power supply is interrupted, thereby preventing damage from excessive currents or voltages.
Implementation Method 1
a DC link capacitor 4 that smoothes a DC link voltage Vdc
Implementation Method 2
the inverter includes freewheeling diodes 5 that are connected in parallel with the respective switching elements 3 so that a direction from a lower stage toward an upper stage is a forward direction
Implementation Method 3
a backup power supply 2B that uses the first DC power supply 2H as its power source
Data Source
AI summary
A rotating electrical machine control device where the changeover control circuit switches the source of electric power for the electronic control unit when the electric power that is supplied from the second DC power supply to the electronic control unit becomes equal to or lower than a predetermined first reference value and electric power that is output from the backup power supply is equal to or higher than a predetermined second reference value, and the electronic control unit uses the electric power supplied from the backup power supply to cause the inverter to perform the switching operation to perform fail-safe control.