Vehicle Rotary Electric Machine Ground Terminal Isolation
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Solution Overview
Problem
Conventional rotary electric machines for vehicles face challenges in preventing current flow from power system circuits to control system circuits, detecting disconnection of power ground terminals, and protecting elements connected to power ground terminals, especially when multiple ground terminals are individually grounded, and in accurately determining disconnection of control ground terminals due to limited space and small current flow.
Innovation Solution
A rotary electric machine design with separate power and control ground terminals, where a diode is inserted between the control ground terminal and the ISG frame to ensure a grounding path and prevent current flow, and a configuration that monitors voltage variations to detect disconnection of ground cables, allowing for reliable detection and notification of ground terminal disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ground terminal is used for both power system circuit and control system circuit, then the device complexity is reduced, but current can flow from the power system circuit to the control system circuit through the parasitic diode when the power transistor is turned off
Solution Approach 1:
The ground terminal is segmented into two separate terminals: a power ground terminal for the power system circuit and a control ground terminal for the control system circuit. This segmentation prevents current from flowing between the power transistor and control circuit through the parasitic diode, as each terminal is independently grounded to different points on the ISG frame.
2Reliability
If the power ground terminal and control ground terminal are individually grounded to different points on the ISG frame, then current flow from power system to control system is prevented, but the device complexity increases
Solution Approach 1:
The ISG frame serves as an intermediary structure that provides separate grounding paths for the power ground terminal and control ground terminal. By grounding these terminals to different points on the frame, the patent creates isolated reference potentials that prevent unwanted current flow while maintaining a unified mechanical structure.
3Measurement precision
If a current sensor is added to detect disconnection of the control ground terminal, then the measurement precision of ground terminal status is improved, but the device complexity increases and space requirements are not met
Solution Approach 1:
The patent replaces the proposed current sensor (electrical detection method) with a voltage sensor that detects ground terminal disconnection by measuring voltage variations. This substitution uses electrical potential measurement instead of current measurement, achieving the same detection function without requiring additional current sensing components or increased space.
Solution Approach 2:
The voltage sensor serves multiple functions: it detects ground terminal disconnection, monitors system voltage, and provides fault diagnosis information. This multi-functionality eliminates the need for dedicated current sensors while maintaining comprehensive monitoring capabilities.
4Use of energy by moving object
If the amount of current flowing to the control system circuit is relatively small, then the power consumption is reduced, but it becomes difficult to accurately determine disconnection of the ground terminal based on the relationship between current and voltage
Solution Approach 1:
The patent replaces current-based detection with voltage-based detection. The voltage sensor measures voltage variations at the control ground terminal, which provide a clear signal for disconnection detection even when current flow is minimal. This approach maintains measurement precision while accommodating low power consumption requirements.
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
The solution effectively prevents current flow from power system circuits to control system circuits, allows for reliable detection of power and control ground terminal disconnections, and protects elements connected to the power ground terminal, ensuring stable operation and prompt notification of malfunctions.
Implementation Method 1
a diode is inserted between the control ground terminal and the ISG frame to ensure a grounding path and prevent current flow
Data Source
AI summary
A rotary electric machine for a vehicle is provided. The rotary electric machine includes a power system circuit which has a power element and is grounded via a first ground terminal and a first connecting line and a control system circuit which controls the power system circuit and is grounded via a second ground terminal and a second connecting line.