Motor Winding Switching Frequency Control to Prevent Inverter Burnout
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Solution Overview
Problem
Existing air conditioners require mechanical or electrical switches for switching motor windings, which can degrade over time and risk burnout due to repeated use.
Innovation Solution
A motor driving apparatus with an inverter and a switching device that switches motor windings between Y-connection and A-connection, controlled by a controller to manage operating frequencies and regenerative currents to prevent burnout, and includes a brake chopper circuit to manage DC terminal voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical switch or electrical switch is used to switch motor windings between Y-connection and A-connection, then the switching function is achieved, but the switch may be damaged or its life degraded due to repeated use
Solution Approach 1:
The patent replaces mechanical switches with a solid-state switching device that uses electronic components (MOSFETs or IGBTs) to switch motor windings between Y-connection and A-connection. This eliminates mechanical contact wear and significantly extends the switching device life while maintaining reliable switching functionality.
Solution Approach 2:
The patent changes the operating parameters by controlling the switching device to operate only within specific frequency ranges (first frequency range for Y-connection, second frequency range for A-connection). This parameter control prevents operation under conditions that would cause overheating or excessive stress, thereby preventing burnout and extending device life.
2Adaptability or versatility
If the switching device is used to switch motor windings repeatedly, then the connection switching function is achieved, but burnout risk increases
Solution Approach 1:
The patent implements dynamic switching control where the switching device adapts its operation based on the motor's operating frequency. The controller dynamically selects between Y-connection and A-connection modes and adjusts the operating frequency ranges accordingly, allowing the system to handle varying load conditions while preventing burnout through frequency-based protection.
Solution Approach 2:
The patent incorporates feedback control where the controller monitors the motor's operating frequency and automatically adjusts the connection mode (Y or A) and frequency range. This feedback mechanism ensures the switching device operates within safe parameters, preventing burnout while maintaining adaptability to different operating conditions.
3Ease of operation
If the operating frequency is not controlled during switching, then the switching operation is simple, but the DC terminal voltage may exceed allowable levels causing burnout
Solution Approach 1:
The patent implements preliminary action by pre-defining safe operating frequency ranges for each connection mode (Y-connection first frequency range, A-connection second frequency range). Before switching occurs, the controller ensures the motor frequency is within the appropriate range, preventing DC terminal voltage from exceeding allowable levels and avoiding burnout conditions.
Solution Approach 2:
The patent uses a controlled switching approach where the controller rapidly transitions the motor between Y-connection and A-connection modes by adjusting the operating frequency within predefined ranges. This controlled 'rushing through' of frequency transitions prevents prolonged operation in unsafe states that could cause burnout, while maintaining operational simplicity.
Data Source
AI summary
The present disclosure relates to a motor driving apparatus and an air conditioner including the same. The motor driving apparatus and the air conditioner including the same according to an embodiment of the present disclosure include: a switching device disposed between an inverter and a motor; and a controller, which in response to windings of the motor being switched from a first connection to a second connection, controls an operating frequency of the motor to be less than or equal to a first frequency, and in response to the windings of the motor being switched from the second connection to the first connection, controls an operating frequency of the motor to be less than or equal to a second frequency which is less than the first frequency. Accordingly, burnout of the switching device for switching connection of the motor windings may be prevented.