Sensorless Electric Water Pump Coil Diagnosis
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Solution Overview
Problem
Existing methods for diagnosing faults in electric water pumps with sensorless 3-phase motors fail to promptly detect open coils, leading to potential engine overheating due to insufficient coolant pumping.
Innovation Solution
A method that determines whether any coil of a sensorless 3-phase motor is open by analyzing changes in phase currents, motor torque, and average phase current, using specific conditions and reference values to accurately diagnose coil-open states during motor acceleration or constant velocity states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing diagnostic methods are used for sensorless 3-phase motors, then the system structure remains simple, but the diagnosis of open coils is delayed and unreliable
Solution Approach 1:
The patent applies preliminary action by performing open coil diagnosis during the motor acceleration phase before the motor reaches its operating state. The controller monitors phase currents during acceleration and detects open coils before they can cause engine overheating, thus preventing the problem rather than reacting to it after occurrence.
Solution Approach 2:
The patent implements feedback by continuously monitoring phase currents during motor acceleration and comparing them against expected values. When an anomaly is detected indicating an open coil condition, the system provides immediate feedback to the controller to take corrective action, ensuring reliable and timely diagnosis.
2Measurement precision
If existing diagnostic methods are used, then the control system remains simple, but the detection precision of open coils is insufficient
Solution Approach 1:
The patent applies self-service by utilizing the existing phase current sensors and controller resources already present in the motor control system. No additional diagnostic hardware is needed; the system uses its own operational data during acceleration to diagnose open coils, thereby improving detection precision without increasing device complexity.
Data Source
Figure 1
AI summary
A method for diagnosing an electric water pump of an internal combustion engine includes determining whether a present condition is a coil-open diagnosis condition that enables diagnosis of whether any coil of a sensorless 3-phase motor used in the electric water pump is open. When the coil-open diagnosis condition is satisfied, whether a coil of one phase is open is determined by using a change in phase currents. When the coil-open diagnosis condition is satisfied, whether coils of two phases are open is determined by using a magnitude of a motor torque or a magnitude of an average phase current. When the coil-open diagnosis condition is satisfied, whether any coil of the motor is open during driving of the motor is determined by using a variation in the motor torque.