Motor drive system and air conditioner
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Solution Overview
Problem
Conventional motor drive systems cannot detect misconnection states, leading to potential operation in abnormal conditions that may cause overcurrent and failure in the inverter or motor.
Innovation Solution
A motor drive system comprising an inverter, a connection switching device, and a controller that determines the abnormality of the connection state based on current values flowing in the stator windings, allowing for detection of misconnections and preventing secondary failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a connection switching device is used to switch stator winding connection states, then the motor can operate at higher rotational speeds and save power consumption, but the system cannot detect misconnection states leading to potential failures
Solution Approach 1:
The controller performs abnormality determination on the connection state before the motor operates, by measuring current values flowing in each stator winding and comparing them against expected values for the instructed connection state. This preliminary detection prevents misconnection-related failures before they can cause damage.
Solution Approach 2:
The system continuously monitors the actual connection state by measuring current values in stator windings and feeds this information back to the controller. The controller compares the measured current values with expected values for the instructed connection state, enabling real-time detection of misconnections and allowing the system to respond appropriately.
2Device complexity
If the system operates without connection state detection, then the device complexity is reduced, but overcurrent and potential failures in the inverter or motor may occur
Solution Approach 1:
The system uses the existing current measurement infrastructure and the motor's own operational characteristics to detect connection abnormalities. By measuring current values that naturally flow during motor operation and comparing them against expected values, the system performs self-diagnosis without requiring external testing equipment or additional sensors.
Solution Approach 2:
The system detects misconnections by monitoring changes in current values flowing in stator windings. When a misconnection occurs, the actual current values deviate from the expected values calculated based on the instructed connection state. The controller identifies abnormalities by detecting these parameter changes in the current measurements.
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
Enables the detection of misconnection states, preventing overcurrent and potential failures in the inverter or motor by determining the actual connection state against the instructed state, thereby ensuring safe and reliable operation.
Implementation Method 1
an inverter to convert a DC voltage supplied from a DC voltage source into an AC voltage and apply the AC voltage to the motor
Implementation Method 2
a connection switching device disposed between the inverter and the motor and capable of switching a connection state of the stator windings; When the connection state is changed by the connection switching device, an induced voltage constant of the motor changes
Implementation Method 3
a controller to perform abnormality determination on a connection state of the connection switching device on the basis of a current value of a current flowing in each of the stator windings
Data Source
AI summary
A motor drive system can detect a misconnection. A motor drive system for driving a motor including a plurality of stator windings includes: an inverter that converts a DC voltage supplied from a DC voltage source into an AC voltage and applies the AC voltage to the motor; a connection switching device that is disposed between the inverter and the motor and can switch a connection state of the stator windings; and a controller that performs abnormality determination on a connection state of the connection switching device on the basis of a current value of a current flowing in each of the stator windings.