Rotary Machine Controller Winding Switching Stability
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Solution Overview
Problem
Existing rotary machine controllers face challenges in quickly and stably switching the connection state of windings during a rotating operation, especially in devices with large loads, leading to potential motor stoppage or incorrect phase estimation.
Innovation Solution
A rotary machine controller comprising a connection switch, current detector, position/speed estimator, and control circuitry that generates a voltage command to bring the motor current close to zero before switching, and outputs an initial restoration speed to ensure stable switching and continued operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output of the inverter is turned off when switching the winding connection state, then the phase estimation can be performed after resuming the output, but the switching process takes too much time and the motor may stop or step out in devices with large load
Solution Approach 1:
The patent applies preliminary action by bringing the motor current close to zero before switching the winding connection state. This is achieved by controlling the inverter output to reduce current to near-zero levels prior to the switching operation, thereby preparing the system in advance to avoid large current disruptions during switching. This preliminary current reduction enables faster switching without causing motor stoppage or step-out, resolving the contradiction between switching speed and operational reliability.
2Speed
If the motor current is brought to zero before switching the winding state, then the switching can be performed quickly, but the motor decelerates rapidly and may stop in devices with large load
Solution Approach 1:
The patent applies parameter changes by controlling the motor current to a specific near-zero range before switching, rather than completely stopping the current. This parameter adjustment allows the switching operation to proceed quickly while maintaining enough current to prevent rapid deceleration and motor stoppage. The current is reduced to a controlled level that enables fast switching without causing the motor to stop, thus resolving the contradiction between switching speed and continuous operation reliability.
3Loss of time
If the inverter output is resumed immediately after switching the winding state, then the phase estimation can start quickly, but the phase may not be estimated correctly due to motor deceleration or stoppage
Solution Approach 1:
The patent applies preliminary action by preparing the motor current to be close to zero before switching, which creates optimal conditions for immediate phase estimation after switching. This preliminary current control ensures that when the inverter output is resumed, the motor is in a stable state conducive to accurate phase estimation, eliminating the need for extended estimation periods while maintaining high measurement precision.
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 quick and stable switching of winding states during rotation, preventing motor stoppage and ensuring accurate phase estimation even in devices with large loads, thereby improving operational reliability.
Implementation Method 1
a position/speed estimator that estimates a magnetic pole position and speed of a rotor of the rotary machine on the basis of the rotary machine current
Implementation Method 2
a voltage applicator that applies a voltage to the rotary machine; and a control circuitry that generates a voltage command given to the voltage applicator
Data Source
AI summary
A controller includes: a connection switch that switches a connection state of a winding of a synchronous motor during a rotating operation of the synchronous motor; a current detector that detects a rotary machine current flowing in the synchronous motor; a position/speed estimator that estimates a magnetic pole position and speed of a rotor; a voltage applicator that applies a voltage to the synchronous motor; and a control circuitry that generates a voltage command given to the voltage applicator on the basis of the magnetic pole position and the speed, and outputs a switching operation command for switching the connection state to the connection switch. The control circuitry generates the voltage command to bring the rotary machine current close to zero before the connection state of the winding is switched.