Motor Control Apparatus with Integrated Protection Logic
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control apparatuses for three-phase AC motors in hybrid vehicles have complex and expensive circuit configurations, making it difficult to select suitable three-phase short-circuiting control for disconnection or short-circuit abnormalities, and require high withstanding voltages for circuit components to prevent excessive voltage damage.
Innovation Solution
A motor control apparatus with a three-phase bridge circuit using upstream and downstream switching devices, a power-source capacitor, and a microprocessor that generates control signals for switching control, including pulse-width modulation and penetration prevention mechanisms to prevent short-circuits and excessive voltage damage, allowing for simpler circuit configuration and reduced component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-stage preferential protection circuits are utilized with hardware members provided outside the PWM signal generation unit, then excessive-voltage protection is improved, but the whole circuit configuration becomes complicated and expensive
Solution Approach 1:
The patent merges the protection circuit functions with the PWM signal generation unit by integrating the excessive voltage detection unit, excessive current detection unit, and three-phase short-circuiting control logic directly into the microprocessor. This consolidation eliminates the need for separate hardware protection circuits while maintaining comprehensive protection capabilities, thereby simplifying the overall circuit configuration and reducing component count.
Solution Approach 2:
The microprocessor is designed to perform multiple functions: it generates PWM signals for motor control, detects excessive voltage conditions, detects excessive current conditions, and executes three-phase short-circuiting control when abnormalities occur. By making the microprocessor universal and multi-functional, the patent eliminates the need for dedicated separate protection circuits, reducing circuit complexity while maintaining reliability.
2Reliability
If three-phase short-circuiting control is implemented with separate hardware members, then protection capability is improved, but it becomes difficult to select suitable control for different abnormalities
Solution Approach 1:
The patent implements dynamic selection of protection strategies through software logic within the microprocessor. Based on real-time detection of abnormality types (excessive voltage, excessive current, or other abnormalities), the system dynamically chooses the appropriate control response: three-phase short-circuiting control when switching device abnormalities are detected, or six-phase cutoff control when other abnormalities occur. This dynamic adaptability allows the system to optimize protection responses for different failure modes without requiring separate fixed hardware circuits for each scenario.
3Reliability
If six-phase cutoff control is performed for excessive voltage abnormality, then safety is improved, but the control load on microprocessor and circuit component stress increase
Solution Approach 1:
The patent replaces the traditional mechanical/electrical approach of six-phase cutoff control with a software-based three-phase short-circuiting control mechanism. Instead of cutting off all six phases (which creates high stress on components and heavy control load), the system uses the microprocessor to selectively short-circuit the three phases involved in the abnormality, thereby suppressing the excessive voltage with lower component stress and reduced control complexity. This substitution of control strategy reduces both the mechanical/electrical stress on components and the computational burden on the microprocessor.
Data Source
AI summary
An upper switching device and a lower switching device in an electric-power conversion unit are separately driven to close by an upper closing command signal and a lower closing command signal, respectively, generated by a calculation control unit; in response to occurrence of an excessive current abnormality or an excessive voltage abnormality, upper and lower selection circuits and a penetration prevention circuit provided in a signal path select an upper three-phase short-circuiting command signal or a lower three-phase short-circuiting command signal, or an upper-and-lower six-phase cutoff command signal, and a penetration prevention time prohibits upper and lower switching devices from being concurrently closed; when an excessive voltage abnormality occurs, the three-phase short-circuiting command signal is immediately generated, without an advanced cutoff operation being performed. As a result, excessive-voltage breakage of the circuit components is prevented.