Motor Driving Device Short-Circuit Detection Circuit
Solution Overview
Problem
Conventional motor driving devices require a voltage dividing circuit to determine short-circuit failures in phase opening switches, increasing the physical size of the device and potentially leading to inaccurate open-circuit failure determinations.
Innovation Solution
A short-circuit determination unit that drives all phase opening switches to open and connects the target switch's power supply line to ground, using pull-up resistor units to determine short-circuit failures based on voltage comparisons, eliminating the need for a voltage dividing circuit and ensuring accurate failure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage dividing circuit is used to determine short-circuit failures in phase opening switches, then the determination can be made, but the physical size of the device increases
Solution Approach 1:
The patent extracts the voltage dividing circuit from the system by using an alternative approach: connecting the power supply line to ground through the inverter and using pull-up resistor units. This eliminates the need for the voltage dividing circuit while maintaining the ability to determine short-circuit failures, thereby reducing device physical size.
Solution Approach 2:
The patent introduces pull-up resistor units as intermediary components connected between the power supply lines and the ground. These resistors work in conjunction with the inverter's ground connection to create a voltage detection mechanism that determines short-circuit failures without requiring a voltage dividing circuit, thus reducing device size while maintaining measurement capability.
2Measurement precision
If the inverter connects the power supply line to ground for short-circuit determination, then accurate detection is achieved, but current may flow through parasitic diodes of other phase opening switches
Solution Approach 1:
The patent applies preliminary action by driving all phase opening switches to the open state before performing the ground connection test. This ensures that when the inverter connects the target power supply line to ground, current cannot flow through parasitic diodes of other phase opening switches since they are already open, thereby eliminating the harmful current flow while maintaining accurate voltage detection.
Data Source
AI summary
A control unit determines a presence or absence of a short-circuit failure with respect to a target switch which is a phase-opening switch to be determined. At this time, after opening all the phase opening switches, the control unit drives an inverter to connect a power supply line provided with the target switch among the phase opening switches to ground. The control unit determines that the target switch has a short-circuit failure when a voltage of the power supply line in which the target switch is not provided is smaller than a predetermined voltage.