Load Drive Apparatus Short Circuit Side Determination
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Solution Overview
Problem
General-purpose IC driver units in load drive apparatuses cannot determine the side of a short circuit between the load apparatus and the power supply or ground, requiring custom-designed ICs to identify the short-circuit side, increasing production costs.
Innovation Solution
A load drive apparatus with a driver unit that includes a control section for modulating drive signals, a short circuit detecting section using signal levels, and a notification section, where the control unit determines the short-circuit side by fixing the duty ratio of the PWM signal and analyzing notifications, allowing the apparatus to function with a general-purpose IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a general-purpose IC driver unit is used, then production costs are reduced, but the capability to determine the short-circuit side is lost
Solution Approach 1:
The patent introduces a notification section as an intermediary component that outputs distinct signals based on the short-circuit detection results. This notification section works with the control unit to enable side determination using a general-purpose IC, eliminating the need for custom-designed ICs while maintaining the diagnostic capability.
Solution Approach 2:
The control unit changes the duty ratio parameter of the PWM signal to extreme values (0% or 100%) when a short circuit is detected. By fixing the duty ratio and observing the notification output, the system can determine which side the short circuit occurs on, enabling precise diagnosis without requiring custom IC design.
2Measurement precision
If a custom-designed IC is used, then the short-circuit side can be determined, but production costs increase
Solution Approach 1:
The notification section serves as an intermediary that provides the short-circuit side determination capability through software-controlled logic rather than hardwired custom IC design. This allows standard ICs to be used while achieving the same diagnostic precision as custom-designed solutions.
Solution Approach 2:
The control unit is designed with universal functionality to handle both normal PWM control and short-circuit diagnosis. By integrating the determination logic in the control unit that can work with standard ICs, the system achieves multi-functionality without requiring custom IC design for each application.
3Measurement precision
If the duty ratio is fixed at 0% or 100%, then the short-circuit side can be determined, but the drive signal modulation is interrupted
Solution Approach 1:
The system performs preliminary detection of short circuits during normal operation. When a short circuit is detected, the duty ratio is then fixed for determination purposes. This preliminary detection approach minimizes the interruption of drive signal modulation by only fixing the duty ratio when necessary for diagnosis.
Solution Approach 2:
The determination process using fixed duty ratio is designed to be rapid, allowing the system to quickly identify the short-circuit side and return to normal modulation. The control unit efficiently processes the notification signals to determine the fault side, minimizing the time the drive signal modulation is interrupted.
Data Source
AI summary
The load drive apparatus has a driver unit and a control unit. The driver unit includes a control section modulating, in accordance with a PWM signal supplied from the control unit, a drive signal to be applied to a load apparatus between a high level and a low level, and a short circuit detecting section detecting, on the basis of a signal level of the PWM signal and a signal level of the modulated drive signal, short circuit on a path through which the modulated drive signal is applied to the load apparatus. The control unit includes a function of fixing a duty ratio of the PWM signal upon occurrence of short circuit to determine to which of a high-level side and a low-level side the path is short-circuited.