Star-Delta Relay Switching for Fault-Tolerant Motor Drives
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Solution Overview
Problem
Conventional motor drive devices face reliability issues due to failure in switching stator winding connections between star and delta configurations, often caused by disconnection of coil wires or contact plate failures, leading to improper connection states and operational inefficiencies.
Innovation Solution
A motor drive device with three relays and a control unit that ensures all relays have the same connection state by detecting current flows through the coils and adjusting the contact plates to maintain consistent switching between star and delta connections, even in the presence of electrical failures or foreign matter interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If three change-over-contact relays are used to switch stator winding connections, then the motor can switch between star and delta connections for improved efficiency, but the reliability of motor operation deteriorates due to coil wire disconnection or contact plate failure
Solution Approach 1:
The control unit monitors the operational state of each relay and detects failures in coil wires or contact plates. Based on this feedback, the control unit automatically adjusts the connection configuration to maintain motor operation, preventing complete system failure and ensuring continuous reliable operation while preserving the efficiency benefits of star-delta switching.
2Adaptability or versatility
If relay contact plates are made movable to enable switching, then connection configuration can be changed, but the reliability deteriorates due to contact plate failure or inability to move
Solution Approach 1:
The control unit continuously monitors whether contact plates are properly positioned and functioning. When a contact plate failure or movement issue is detected, the system receives feedback and automatically adjusts the switching strategy to maintain reliable operation, preserving the adaptability of connection switching while compensating for contact plate reliability issues.
3Ease of operation
If coil current is used to actuate contact plates, then switching can be achieved, but disconnection of coil conductor wire prevents contact plate movement and proper connection configuration
Solution Approach 1:
The control unit monitors the electrical state of each relay coil and detects wire disconnections. When a disconnection is detected, the system receives feedback and automatically adjusts the connection configuration strategy to maintain proper motor operation, preserving the ease of switching operation while compensating for coil wire reliability issues.
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 enhances the reliability of motor operation by ensuring consistent connection configurations, maintaining efficient operation across varying frequencies and preventing unstable conditions, even when some relays fail or are stuck.
Implementation Method 1
uses a coil to switch the contact plate of a relay, and passes a current through the coil to move the contact plate
Data Source
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AI summary
The present invention is directed to a motor drive device (100) capable of switching the connection configuration of the stator windings of a motor (3). The motor drive device (100) includes three relays (11, 12, 13) each including a first contact (41, 42, 43), a second contact (51, 52, 53), and a contact plate (21, 22, 23), where the contact plate has one terminal coupled to a stator winding of one phase among the stator windings and the contact plate has another terminal to be connected to the first contact or to the second contact; and a control unit (5) to control the three relays to cause all the three relays to have a same connection state in a case in which not all the three relays have a same connection state with respect to connections between the another terminal of the contact plate and the first contact and the second contact.