Load Drive Apparatus Anomaly Detection for Resistive Loads
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Solution Overview
Problem
Conventional load drive apparatuses for resistive loads, such as oxygen sensors, can only detect short circuits to ground and not short circuits to power, and fail to detect wire breakages and short-to-power anomalies simultaneously with normal operation, limiting their ability to identify connection anomalies effectively.
Innovation Solution
A load drive apparatus with a pulse drive circuit, current detection means, and level detection means that turns on and off to detect wire breakage, short-to-power, and short-to-ground anomalies by analyzing output terminal voltage and current levels, allowing for simultaneous detection during normal operation without interrupting energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage difference measurement is used to detect heater failures, then short-to-ground anomalies can be detected, but short-to-power anomalies and wire breakages cannot be detected
Solution Approach 1:
The anomaly detection function is segmented into three independent detection paths: voltage difference measurement for short-to-ground detection, output terminal voltage level detection for short-to-power detection, and current measurement for wire breakage detection. Each path independently monitors a specific anomaly type, enabling comprehensive coverage of all three anomaly types simultaneously during normal operation.
Solution Approach 2:
The pulse drive circuit is enhanced with multi-functionality by integrating three detection functions (voltage difference measurement, output terminal voltage level detection, and current measurement) into a single system. This allows the circuit to perform both normal heater control and comprehensive anomaly detection (short-to-ground, short-to-power, and wire breakage) using the same hardware infrastructure.
2Measurement precision
If separate diagnosis procedures are performed for anomaly detection, then detection accuracy may be improved, but operational continuity is interrupted
Solution Approach 1:
The detection functions operate continuously during normal heater operation without interrupting the energization cycle. The pulse drive circuit simultaneously performs heater control and anomaly detection during each pulse cycle, ensuring both operational continuity and continuous monitoring capability for all three anomaly types.
Solution Approach 2:
The anomaly detection functions are merged with the normal operation control functions. The voltage difference measurement, output terminal voltage level detection, and current measurement are all performed during the same operational cycles used for heater control, combining diagnostic and operational functions into a unified process that maintains continuous operation.
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 accurate detection of three types of connection anomalies (wire breakage, short-to-power, and short-to-ground) during regular operation, preventing further damage by stopping current supply when anomalies are detected, thus ensuring proper sensor function and preventing anomalies like blackening in gas sensors.
Implementation Method 1
a pulse drive circuit which repeatedly applies a pulse voltage to a resistive load
Implementation Method 2
current detection means for detecting a current flowing from the power supply to the resistive load through the pulse drive circuit
Implementation Method 3
level detection means for determining whether an output terminal voltage at the output terminal of the pulse drive circuit is at a high potential level or a low potential level
Data Source
AI summary
A load drive apparatus (1) includes a pulse drive circuit (51) which applies a pulse voltage PS to a resistive load (4); current detection means (S14) for detecting the current flowing to the resistive load (4) through the pulse drive circuit (51); level detection means (S1, S7) for determining whether an output terminal voltage VD of the pulse drive circuit (51) is a high potential level or a low potential level; anomaly detection means (S8, S9, S18) for detecting a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly based on the level of the output terminal voltage VD detected by the level detection means (S1, S7) and the current detected by the current detection means (S14), when the pulse drive circuit 51 is turned on and off.