High Voltage Explosion-Proof VFD | FGI Permanent Magnet Drive Solution for Coal Mine Belt Conveyors

Introduction

Intelligent coal mine construction demands advanced drive and control technologies for high-voltage, high-power underground equipment such as main belt conveyors, shearers, fans, and pumps. Among these, the main underground belt conveyor plays a critical role in coal transportation. It operates with heavy loads, large capacity, and continuous duty cycles. Traditional hydraulic couplers, though offering limited speed regulation, suffer from high slip losses, low efficiency, heavy dependence on oil quality, and high maintenance requirements.

High voltage explosion-proof VFDs (variable frequency drives) provide a superior solution. With wide speed range, precise control, fast response, and soft start capabilities, they are now essential for coal mine conveyor drive systems. Replacing hydraulic couplers with FGI explosion-proof VFDs enables adjustable speed, high starting torque at low current, balanced load distribution, and robust protection functions—meeting the demands of modern intelligent coal mine solutions.

Case Study: Yingpanhhao Coal Mine Application

System Overview

Yingpanhhao Coal Mine in Ordos, Inner Mongolia, has a production capacity of 12 million tons per year. Its north wing main belt conveyor system uses an FGI high voltage explosion-proof VFD (Model BPBJV2-1250/10) with the following specifications:

• Input/Output Voltage: 10kV

• Rated Power: 1250kW

• Topology: Cascaded structure with 8 power cells per phase

The conveyor drive system integrates permanent magnet direct-drive synchronous motors (Model TBVF-900YC, 10kV, 900kW, 60 rpm). The configuration includes 4 motors at the head and 2 at the tail, managed through a master-slave control architecture with optical fiber communication. This ensures precise coordination, reliable operation, and long-distance driving capacity of up to 5,000 meters.

System Structure & Control

The system is powered through a phase-shifting transformer, providing three key functions:

1. Step-down to 690V for isolated power supply to power cells.

2. Phase-shifting for multi-pulse rectification, reducing harmonic distortion.

3. Isolated supply for cascaded cell operation.

The cascaded power cell design, combined with carrier phase-shifting technology, produces an almost sinusoidal output without the need for filters. This minimizes harmonic interference on both motors and grid, earning FGI the recognition as a “harmonic-free drive system”.

Master-slave fiber optic communication ensures reliable high-speed data transfer, while vector control with speed droop algorithms dynamically balances motor loads. This addresses the common issue of load imbalance in multi-motor conveyor systems.

Key Application Benefits

1. Soft Start Capability
   Provides up to 2.2× rated torque at low frequency with adjustable acceleration (1–3600s), meeting heavy-load soft start requirements.

2. Precise Power Balancing
   Achieves torque balance across head and tail drives, with motor imbalance rate below 2%, even over 5 km cable length.

3. Online Switching & Redundancy
   Operates in “5 running + 1 standby” mode. If one VFD fails, the standby unit activates immediately, ensuring continuous conveyor operation.

4. Automatic Speed Adjustment
   With coal flow sensors, belt speed adapts to load conditions: “faster with more coal, slower with less.” Transport efficiency is significantly improved.

5. Energy Saving & Reduced Wear
   Permanent magnet direct-drive motors eliminate gear reducers, increasing efficiency and reducing mechanical wear. Soft start lowers system impact, while variable speed reduces high-speed operation time. This leads to:

   • Reduced maintenance costs

   • Extended equipment lifespan

   • Lower energy consumption

Advantages of FGI Explosion-Proof VFD Solutions

• Compact Footprint & Easy Maintenance
  Integrated transformer + VFD design saves space and reduces cabling. Modular design simplifies on-site maintenance.

​

• Multiple Reliability Safeguards
  Built-in redundancy with automatic power cell bypass ensures uninterrupted production.

• Adaptive Load Balancing
  Self-adjusting load sharing supports up to 10 coordinated VFDs.

• Smart Mine Communication Interfaces
  Supports fiber, Ethernet, and wireless access. Enables remote monitoring, fault diagnosis, and predictive maintenance via PC or mobile app.

Conclusion

The mining industry is rapidly shifting toward large-scale intelligent coal mine operations. The Guidelines for Intelligent Coal Mine Construction highlight the urgent need for high voltage explosion-proof VFDs to power conveyors, shearers, and other critical systems.

The successful deployment of FGI’s harmonic-free explosion-proof VFD at Yingpanhhao Mine demonstrates breakthrough performance:

• Input THD < 3%

• Output Voltage Harmonics < 2%

• +15% Drive Efficiency Improvement

• +20% Overall System Energy Efficiency

• 18–25% Energy Savings

• 500+ tons CO₂ reduction per unit annually

By enabling long-distance power transmission, precise load balancing, and smart diagnostics, FGI solutions support the coal industry’s dual-carbon goals while driving operational safety and efficiency.

Call to Action

Discover how FGI high voltage explosion-proof VFD solutions can enhance your coal mine conveyor systems with energy-saving drive technology, soft start functions, and intelligent automation.