Motor driving device and cooling cycle device
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Solution Overview
Problem
Existing motor drive apparatuses for open-winding motors face challenges in suppressing potential differences between the opening and closing contacts, which can lead to surge voltages and arcs, affecting the lifespan of switching contacts and potentially damaging inverter switching elements.
Innovation Solution
The proposed motor drive apparatus incorporates a configuration with series circuits of upper and lower switch elements in both inverters, along with semiconductor switch elements in parallel to the switching contacts. A controller executes a pseudo-neutral point operation by alternately turning on and off all upper and lower switch elements in the second inverter and turning on the semiconductor switch elements, while ensuring the third inductance value is smaller than the total value of the first and second inductances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching contact opens and closes in a state with potential difference, then the motor can be driven in star connection mode, but surge voltage or arc is generated between both ends of the switching contact
Solution Approach 1:
The control device executes pseudo-neutral point operation before opening or closing the switching contact. This preliminary action equalizes the potential between both ends of the contact by switching the second inverter, ensuring that the contact opens/closes when potential difference is minimized, thereby preventing surge voltage and arc generation while maintaining reliable motor drive operation
2Productivity
If the switching contact opens and closes in a state with potential difference, then the motor can be driven in star connection mode, but the switching elements of each inverter may be destroyed
Solution Approach 1:
The control device executes pseudo-neutral point operation before opening or closing the switching contact. This preliminary action equalizes the potential between both ends of the contact by switching the second inverter, ensuring that the contact opens/closes when potential difference is minimized, thereby preventing surge voltage and arc generation that could destroy switching elements, while maintaining reliable motor drive operation
3Reliability
If pseudo-neutral point operation is executed by switching the second inverter, then potential difference between switching contacts is reduced, but switching timing synchronization becomes complex
Solution Approach 1:
The control device monitors the switching timing of the second inverter and adjusts the switching contact operation accordingly. By using feedback from the inverter switching state, the control device determines the optimal timing to open/close the contact, ensuring potential equalization while managing control complexity through adaptive timing adjustment
Data Source
AI summary
This motor driving apparatus comprises a first inverter, a second inverter, a plurality of opening and closing connections, a plurality of semiconductor switch elements, and a controller. The controller, at the opening or closing of the opening and closing connections, executes a pseudo neutral point operation and turns on the semiconductor switch elements in advance. First wirings each have a first inductance, second wirings each have a second inductance, and third wirings each have a third inductance. The third inductance value is smaller than the total of the first inductance value and the second inductance value.