The load-controllable transformer-type adjustable reactor can quickly and continuously adjust its inductance, ensuring excellent linearity and minimal harmonic generation, making it applicable across various fields. However, the DC voltage on the inverter bridge's DC side significantly impacts its performance. Using DC power on the DC side enhances the reactor's performance but increases system costs and limits its application scope. Conversely, utilizing capacitors as the DC power supply reduces costs and broadens applicability, but maintaining stable capacitor voltage becomes critical for normal operation. During startup, designing a charging circuit is essential, yet existing solutions do not address dynamic voltage control during operation.
A particular challenge lies in the primary equivalent reactance's high dependence on the transformer's body parameters. Accurately controlling the inductance requires precise knowledge of these parameters, which vary due to manufacturing tolerances and operational conditions. This variability complicates control system development and reactor promotion, hindering precise control.
To address these issues, a novel control system has been developed. This system operates independently of transformer body parameters and stabilizes the DC-side capacitor voltage without requiring a specialized charging circuit, ensuring the reactor operates effectively.
For real-time reactance value monitoring, the system employs an on-line detection principle. When the transformer functions as a reactor, the ratio of the primary fundamental voltage to the current amplitude gives the equivalent reactance. Extracting the fundamental component of voltage or current, which may contain harmonic components, is crucial. The system uses resonant, inertial, and proportional links to extract the fundamental component, with the subsystem Gb demonstrating effective frequency response, particularly suppressing second and higher-order harmonics.
In terms of DC-side capacitor voltage control, the system utilizes a current-source inverter bridge. By precisely managing the inverter’s output, the system ensures the capacitor voltage remains stable, which is vital for the reactor's performance. The control strategy involves separating the current into in-phase and quadrature components, allowing independent regulation of each component to control inductance dynamically.
Simulations validate the effectiveness of the control system. When the input signal is a square wave, the output accurately reflects the fundamental frequency, demonstrating the system's capability to filter out harmonics. Additionally, experiments using a voltage-type three-phase inverter with a 120W AC motor confirm the practical applicability of the proposed SVPWM subdivision optimization algorithm. Compared to conventional methods, this approach is simpler, resource-efficient, and highly responsive, proving its efficacy in motor speed control systems.
In conclusion, this innovative control system overcomes previous limitations by eliminating dependency on transformer parameters and providing robust, adaptable control. Its successful implementation in motor control demonstrates significant potential for broader industrial applications. Future research could explore further enhancements to expand its versatility and efficiency.
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