Power Conversion Device Bias Switch Control
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Solution Overview
Problem
Power conversion devices between direct current power sources and multi-phase rotating electrical machines face issues with voltage detection errors and response delays due to power supply switches, leading to reduced failure detection accuracy when starting or stopping the power supply.
Innovation Solution
A power conversion device with an internal power supply switch and a bias power supply switch, connected in parallel, that manages the current path based on output voltage levels to prevent malfunctions and reduce dark current during startup and shutdown, using n-channel MOSFETs to regulate the step-up power supply circuit operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power supply switch is provided between a direct current power supply and a power supply device to prevent malfunction during startup or shutdown, then reliability is improved, but measurement precision deteriorates due to voltage drop and response delay causing voltage detection errors
Solution Approach 1:
The patent introduces an intermediary voltage detection circuit that detects voltage at a point before the power supply switch. This intermediary detection mechanism allows the system to monitor voltage conditions without being affected by the switch's voltage drop or response delay, thereby maintaining measurement precision while preserving the reliability benefits of the power supply switch.
Solution Approach 2:
The patent segments the voltage detection function from the power supply switching function. By placing the voltage detection circuit in a separate branch that bypasses the power supply switch, the detection system operates independently from the switching operations, eliminating the interference between these two functions and resolving the contradiction between reliability improvement and measurement precision.
2Device complexity
If no insulation element is provided between a power conversion unit and a control unit in a low voltage system, then device complexity is reduced, but object-generated harmful factors increase due to sneak current and flow-through current risks
Solution Approach 1:
The patent uses the power supply switch as an intermediary element that provides electrical isolation between the power conversion unit and the control unit during critical transitions. This intermediary mechanism prevents harmful sneak currents and flow-through currents from affecting the control unit's minute signal circuits, while maintaining system simplicity by using a single component that serves both switching and isolation functions.
Solution Approach 2:
The patent implements preliminary action by deactivating the power supply switch before the control unit begins operation during startup, and keeping it deactivated after shutdown. This preliminary protective action prevents harmful currents from flowing into the control unit before it is ready to handle signals or after it has stopped operating, thereby eliminating safety risks without adding complex insulation structures.
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 reduces dark current and prevents malfunctions during power supply startup and shutdown, while minimizing voltage errors in the failure detection unit, ensuring accurate voltage input and reliable operation.
Implementation Method 1
an internal power supply switch, connected between the direct current power supply and the step-up power supply circuit, that opens or closes a current path from the direct current power supply to the step-up power supply circuit based on an output voltage of the step-up power supply circuit
Implementation Method 2
a bias power supply switch, connected in parallel with the internal power supply switch, that opens or closes a current path from the direct current power supply to the step-up power supply circuit based on an output voltage of the internal power supply circuit
Implementation Method 3
the step-up power supply circuit steps up and outputs a predetermined voltage based on the step-up power supply circuit start-up signal
Data Source
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AI summary
A power conversion device has an internal power supply switch configured of an n-channel MOSFET and a bias power supply switch connected in parallel with the internal power supply switch, wherein, when an output voltage of an internal power supply circuit is equal to or greater than a predetermined value when a power supply is started up, the bias power supply switch opens a current path, a step-up power supply circuit steps up and outputs a predetermined voltage based on a power supply start-up signal output by the internal power supply circuit, and the internal power supply switch opens a current path, and when the power supply is stopped, the step-up power supply circuit is stopped based on a stop signal output by the internal power supply circuit and the internal power supply switch closes the current path, and when the output voltage of the internal power supply circuit becomes lower than a predetermined value, the bias power supply switch closes the current path.