Parallel Inductive Load Drive Control Under Temporary Reverse Current
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Solution Overview
Problem
In vehicle automatic transmission systems, the conventional load drive device experiences stability issues and ride comfort problems due to the detection of reverse currents when multiple inductive loads are connected in parallel, leading to potential false determination of common wiring abnormalities and resulting in speed change shocks.
Innovation Solution
A load drive device with first and second switch elements, current and direction detection units, and a control unit that calculates an average current and drives the switches based on deviations from a target current, allowing continuous operation even when a reverse current is detected, with monitoring and feedback control to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse current detection is implemented to detect common wiring disconnection, then reliability of abnormality detection is improved, but false determination occurs when temporary reverse current flows in normal operation, causing unnecessary shutdown
Solution Approach 1:
The system changes the parameter being monitored from simple current direction to average current direction over multiple cycles. By calculating the average current across multiple PWM cycles, the system can distinguish between temporary reverse currents (which average out) and genuine abnormalities (which persist), thus maintaining continuous operation while ensuring reliable detection.
Solution Approach 2:
The system implements feedback by continuously monitoring current direction and magnitude across multiple cycles, comparing against target current values, and adjusting the determination logic based on accumulated data. This feedback mechanism prevents false shutdowns while maintaining accurate abnormality detection.
2Reliability
If load drive device stops operation upon reverse current detection, then abnormality response is improved, but control stability and linearity are deteriorated due to temporary shutdowns
Solution Approach 1:
The system changes from binary stop/go operation to a more nuanced approach where operation continues unless average current direction indicates genuine abnormality. This parameter change in the control logic maintains stability by avoiding unnecessary shutdowns while preserving the ability to respond to real abnormalities.
Solution Approach 2:
The system performs preliminary averaging of current values over multiple cycles before making a shutdown determination. This preliminary action filters out temporary fluctuations and ensures that shutdown decisions are based on sustained abnormalities, thereby maintaining control stability.
3Device complexity
If common wiring is used to reduce connector terminals and wiring size, then device complexity is reduced, but reverse current influence between parallel inductive loads occurs
Solution Approach 1:
The system uses feedback monitoring of current direction and magnitude to detect and compensate for reverse current influences. By continuously measuring actual current flow and comparing it with expected values, the system can identify when reverse current is affecting load operation and adjust control accordingly, maintaining performance despite the shared wiring arrangement.
Solution Approach 2:
The system monitors and responds to changes in current parameters (direction, magnitude, duration) to distinguish between normal reverse current effects and genuine abnormalities. This parameter-based approach allows the system to tolerate the reverse current influence inherent in common wiring while still detecting real problems.
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
This solution ensures high stability and linearity of the load drive device, reducing speed change shocks and improving ride comfort by distinguishing between normal and abnormal reverse currents, thus preventing unnecessary shutdowns.
Implementation Method 1
a current and direction detection unit that detects a current flowing through the first switch element in a forward direction and a reverse direction; a current and direction detection unit that detects a current flowing through the second switch element in the forward direction and the reverse direction
Data Source
AI summary
Provided is a load drive device with high stability (linearity) and a control method thereof capable of continuing a normal operation without stopping the load drive device even when a reverse current is temporarily detected with a specific inductive load in the load drive device in which a plurality of inductive loads are connected in parallel.