Synchronous Machine Starting Device with Dynamic Rotor Position Detection
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Solution Overview
Problem
Synchronous machine starting devices face challenges in stabilizing the startup of synchronous machines, particularly when the machine has not returned to the standby rotational speed after stopping, leading to delayed restart capabilities.
Innovation Solution
A synchronous machine starting device incorporating a power conversion unit, AC voltage and current detectors, a rotor position detection unit with a timing detection unit, feedback operation unit, frequency detection unit, and a selector circuit to accurately determine and adjust the rotor position signal, allowing for stable startup even when the machine has not reached the standby rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the synchronous machine is used in standby state with low rotational speed, then the starting stability is improved, but the machine cannot be restarted immediately after stopping due to inertia rotation
Solution Approach 1:
The invention dynamically adapts the initial frequency of the position signal to match the actual rotational speed of the rotor. Instead of using a fixed frequency, the system detects the actual rotational speed and adjusts the initial frequency accordingly, enabling stable operation whether the rotor is stationary, rotating at standby speed, or rotating at higher speeds due to inertia after stopping.
Solution Approach 2:
The invention changes the parameter of initial frequency based on the detected rotational speed. By detecting the actual rotational speed of the rotor and setting the initial frequency of the position signal to match this speed, the system can handle various operational states including immediate restart after stopping, without requiring the machine to return to standby speed first.
2Ease of operation
If a fixed initial frequency is used for the position signal, then the system is simple to control, but it cannot accurately track the rotor position when rotational speed varies
Solution Approach 1:
The invention implements a feedback mechanism where the actual rotational speed is detected and used to adjust the initial frequency of the position signal. This feedback loop ensures that the position signal accurately tracks the rotor position even when rotational speed varies, maintaining measurement precision while keeping the control system relatively simple.
Solution Approach 2:
The system transitions from a static fixed frequency approach to a dynamic frequency adjustment approach. The initial frequency of the position signal is no longer fixed but is dynamically adjusted based on the detected rotational speed, allowing accurate tracking across varying speeds while maintaining ease of operation through automated detection and adjustment.
Data Source
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AI summary
A rotor position detection unit (11) provided in a synchronous machine starting device includes a timing detection unit (21) for outputting a first position signal indicating a timing at which a value of an armature voltage of a synchronous machine passes a prescribed reference level, a feedback operation unit (23) for calculating an error of an estimated phase based on the estimated phase indicating a rotor position, an estimated rotational speed of a rotor, an armature voltage, and an armature current, updating the estimated phase and the estimated rotational speed based on the calculated phase error, and outputting a second position signal indicating the updated estimated phase, a frequency detection unit (24) for detecting a first frequency indicating a current rotational speed of the rotor of the synchronous machine based on the first position signal, as an initial frequency corresponding to an initial value of the estimated rotational speed, and a selector circuit (SEL) for selecting the first position signal or a position signal obtained based on the first position signal, and the second position signal in this order, and outputting a selected position signal to the power conversion control unit (19).