Recently, a 6,000 kW induction heating power supply system, tailor-made by Guangzhou Zhiguang Electric Technology Co., Ltd. (“Zhiguang Electric Technology”) for a steel group, has been successfully commissioned. The system consists of multiple single-phase output inverter power units, each with independently adjustable frequency and power, specifically designed for parallel resonance conditions where multiple inductors simultaneously heat shaft components. Equipped with proprietary same-frequency, same-phase control technology, the system enables energy-efficient, intelligent, and precise upgrades to the roll tempering process, injecting new momentum into the green and low-carbon transformation of the steel industry.

Process Requirements: Stringent Demands for Roll Tempering

Roll tempering is a critical process to ensure the stable performance of rolling mill rolls. It requires precise heating to eliminate internal stress, stabilize the microstructure, and adjust hardness, placing extremely high demands on control accuracy and operational stability. Based on on-site conditions, Zhiguang Electric Technology developed this dedicated variable-frequency induction heating power system tailored to the application.

Solution Highlights: Four Key Advantages

Deep Customization, Precise Matching: Unlike conventional high-voltage variable-frequency drives or soft starters, this system is purpose-built for multi-coil parallel resonance induction heating. Multiple inverter power units independently drive several heating coils, enabling zonal temperature control for shaft components.

Same-Frequency, Same-Phase Control for Uniform Heating: Leveraging advanced same-frequency, same-phase control technology and digital algorithms, the system ensures synchronized power output and precise phase alignment across multiple coils, resulting in more uniform circumferential and axial heating of rolls and significantly improved product quality.

Wide-Range Regulation, Flexible Adaptation: Each power unit allows independent power adjustment, easily accommodating rolls of varying specifications. The system operates stably under both inductive and capacitive conditions (power factor ≥ 0.85), and with frequency tracking and load compensation, it effectively handles load variations during the heating process.

High Efficiency, Energy Saving, and Intelligent O&M: Variable-frequency induction heating significantly improves heat penetration efficiency and shortens tempering time, reducing overall energy consumption. Intelligent monitoring and comprehensive protection functions minimize fault risks and ensure continuous high-intensity production.

Performance Outlook: Breakthroughs in Both Capacity and Efficiency

The project integrates Zhiguang Electric Technology’s mature medium-frequency inverter control solutions, with core implementation of same-frequency, same-phase control, complemented by advanced frequency tracking and load compensation. This ensures synchronized multi-coil output and consistently stable power quality. Since commissioning, the system has delivered remarkable results—enhancing heating uniformity and product performance while reducing energy costs and maintenance intensity, achieving dual breakthroughs in production capacity and energy efficiency.

The successful operation of this project further validates Zhiguang Electric Technology’s position as an innovation leader in high-power power electronics and highlights the strong adaptability of its high-voltage variable-frequency technology in metallurgical induction heating applications. Building on this achievement, Zhiguang Electric Technology will continue to drive technological innovation and deepen industry collaboration, helping more metallurgical enterprises achieve green and intelligent upgrades, and contributing to the high-quality development of the steel industry and the realization of carbon neutrality goals.