Inverter Drive Diagnostics Using Phase Currents and DC Bus Voltage
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Solution Overview
Problem
Inverter-fed machine systems in electric and hybrid vehicles face challenges in real-time failure detection, particularly in identifying faults in power and control components such as IGBTs, diodes, motor windings, and DC bus capacitors, which can lead to system inefficiencies and potential breakdowns.
Innovation Solution
A drive system with a controller that uses phase current measurements and DC bus voltage signals to determine failures by setting over-current values and monitoring switching system operations, allowing for real-time diagnosis and classification of failures in the inverter and other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sensor-based fault detection methods are used, then sensor faults can be detected, but real-time failure detection in power components (IGBTs, diodes, capacitors) cannot be achieved
Solution Approach 1:
The patent replaces traditional mechanical/electrical sensor-based fault detection with a model-based diagnostic approach. The controller uses mathematical models to calculate expected phase currents and compares them with actual measurements, enabling detection of failures in power components (IGBTs, diodes, capacitors) without additional hardware sensors.
Solution Approach 2:
The patent introduces an intermediate diagnostic layer between the sensors and the control system. The controller acts as an intermediary that processes phase current measurements and DC bus voltage signals through diagnostic algorithms to infer the status of power components, bridging the gap between available measurements and component health assessment.
2Reliability
If comprehensive fault detection is implemented, then system reliability improves, but system complexity increases
Solution Approach 1:
The patent makes the existing controller multi-functional by integrating fault detection capabilities into the existing control architecture. The same controller that manages motor control also performs diagnostic functions using existing sensors (phase current sensors and DC bus voltage sensor), eliminating the need for separate diagnostic hardware and reducing overall system complexity.
Solution Approach 2:
The diagnostic system is self-sufficient, using only the phase current measurements and DC bus voltage signals already available from the system's operational sensors. The controller independently performs all diagnostic calculations and failure detections without requiring external diagnostic equipment or additional measurement systems.
3Productivity
If real-time diagnostics are performed during operation, then system availability is maintained, but measurement precision requirements increase
Solution Approach 1:
The patent performs preliminary diagnostic calculations by continuously computing expected phase currents based on the motor model and control inputs before actual failures occur. This allows the system to establish baseline behavior and detect deviations in real-time, maintaining system availability while using standard measurement precision.
Data Source
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AI summary
Example embodiments disclose a drive system including a machine including a plurality of phases and configured to generate power based on a plurality of phase currents, each respectively associated with the plurality of phases and a direct current (DC) bus, operatively connected to the machine. The DC bus includes a high-sideline, a low-side line and an inverter including a plurality of switching systems operatively connected between the high-side and the low-side lines the plurality of switching systems, each configured to output a respective one of the plurality of phase currents. The drive system also includes a controller operatively connected to the DC bus and the machine, the controller configured to determine if a failure exists in the drive system based on the plurality of phase currents and a DC bus voltage the DC bus voltage being a voltage across the high-side and low-side lines.