Rotary Machine Winding Switching Detection During Motor Rotation
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Solution Overview
Problem
Existing rotary-machine control devices inaccurately determine the successful switching of stator windings due to impedance imbalances and varying operation times, leading to erroneous conclusions about the completion of switching operations.
Innovation Solution
A rotary-machine control device that includes a connection switching device, current detection unit, voltage application unit, control unit, and open-phase determination unit, which outputs switching commands and determines the presence of disconnections during rotation by applying pulse voltages and measuring current responses across phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the ratio between induced voltage and rotational speed is used to determine switching completion, then switching status can be determined during rotation, but erroneous determination occurs due to impedance imbalances and varying operation times
Solution Approach 1:
The patent applies preliminary action by detecting the connection state of stator windings before and after switching operation using injection voltages and current detection. By performing detection in advance and comparing the connection states before and after switching, the system can accurately determine whether switching was successful, preventing erroneous determination that would occur if only post-switching detection were performed.
Solution Approach 2:
The patent implements feedback by continuously monitoring the connection state of stator windings through current detection during motor operation. The control device compares the detected connection state with the expected state after switching, and uses this feedback information to determine whether switching was successfully completed, thereby improving measurement precision while maintaining ease of operation during rotation.
2Power
If stator windings are switched during motor rotation to extend operation frequency range and increase output torque, then motor performance is improved, but impedance imbalance occurs due to varying relay operation times
Solution Approach 1:
The patent replaces mechanical relay switching with electronic switching control. By using electronic switches controlled by a microcontroller, the system achieves precise and synchronized switching of all three phases simultaneously, eliminating the impedance imbalance caused by varying mechanical relay operation times while maintaining the ability to extend operation frequency range and increase output torque.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the connection configuration of stator windings between star and delta connections during motor operation. This allows the system to change electrical parameters (connection state) to extend the operation frequency range and increase output torque while using controlled switching to maintain impedance balance.
3Ease of manufacture
If mechanical relays are used to switch stator windings, then switching operation is simple, but operation time varies between relays causing detection errors
Solution Approach 1:
The patent replaces mechanical relays with electronic switching devices controlled by a microcontroller. This substitution maintains the simplicity of the switching mechanism while eliminating the synchronization errors inherent in mechanical relays, as electronic switches can be controlled simultaneously and precisely for all three phases, thereby improving reliability without sacrificing ease of manufacture.
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 accurate determination of successful switching operations even with impedance imbalances and varying operation times, ensuring reliable connection state changes during rotary machine rotation.
Implementation Method 1
a voltage application unit to apply voltage to the rotary machine; a current detection unit to detect a rotary machine current flowing in the rotary machine
Data Source
AI summary
A rotary-machine control device includes: a connection switching device switching a connection state of stator windings of a rotary machine; a current detection unit detecting a rotary machine current flowing in the rotary machine; a voltage application unit applying voltage to the rotary machine; a control unit generating a voltage command provided to the voltage application unit and outputting a switching command to switch the connection state to the connection switching device; and an open-phase determination unit determining presence or absence of disconnection in the rotary machine or presence or absence of disconnection of a power distribution line to the rotary machine. During rotation of the rotary machine, the control unit outputs the switching command and the open-phase determination unit determines presence or absence of disconnection.