The New Generation Solid-State HF Welder

The New Generation Solid-State HF Welder

With the continual hard working of BAODING RONEN SANZHENG ELECTRICS R&D researchers, the new generation solid-state high-frequency welder has been successfully developed, and verified in some welding applications. The new generation solid-state HF welder will be launched on the market widely soon.

Control Technology

1. Digital Display

Multi-function digital meters are installed on the welder cabinet panel, which can display all the necessary parameters, such as three-phase AC voltage, three-phase AC current, power factor of grid, reactive power, active power, DC voltage, DC current and so on. All these parameters not only can be displayed and recorded, but also can be transmitted to the upper monitor by network communication .

2. New Digital Rectifier Control Board

Field programmable gate array (FPGA) master chip is adopted instead of C51, the main frequent is up to 100M; 16-bit A/D conversion chip (the original C51 control board uses 8-bit A/D conversion chip), and has a high data resolution accuracy. And, all adjustment potentiometers (the original C51 control board has 12 adjustment potentiometers) are canceled, color touch screen controlling and parameter setting make a simple and friendly operation interface. All parameters in the rectifier board can be remotely displayed, controlled and recorded by the upper computer. The new digital rectifier controller adopts double-closed PI loop regulator, in which, the inner loop is current adjustment, the outer loop is set as the constant power mode or constant voltage mode (optional touch screen). With high control accuracy, fast adjustment speed, strong flexibility control methods, good interface expansion, the new digital controller can realize the real one-button control function.

3. New Digital Inverter Control Board

By combining with the advanced control ideas and adopting the master chips of FPGA ,some advanced control technologies are realized, such as fixed-angle phase-locking control and lose-locking protection, which make the welder operate more stable and efficient. And, the short-circuit and open-circuit fault protection in the production of welder is more accurate and faster.

The new inverter controller adopts a complete new Load-Matching technique called Pulse-Shielding-Modulation (PSM), which successfully solves the problem of Load- Matching and output power regulation. When welding different type steel pipes or touch/induction welding are switched by the user, it is no need to do any changes for the HF welder ,the load impedance can match the welder automatically. That means  full power output can be guaranteed in any load conditions.

Moreover, when the welder output power is above 20% rated power, the DC voltage reaches the rated value. And when the welder output power within 20% ~ 100% rated power, the DC voltage maintains the rated value, which mean the highest power factor and minimum harmonic current can be guaranteed. Obviously, the new digital control technique is superior to the traditional power regulation methods.

                                                                                                                                         Figure 1 New digital rectifier board

                                                                                                                                              Figure 2 New digital inverter board

4. Speed-Power Closed-loop Technology

The new generation solid-state HF welder is designed with the most advanced Pulse Shielded Modulation technology (PSM), which ensures that the solid-state HF welder has always the highest welding efficiency, highest power factor, and lowest grid-side harmonic current. The speed-power closed-loop control technology can be achieved by combining new digital rectifier controller with new digital inverter controller. The customers only need to input some parameters such as production specifications, wall thickness through the touching screen. The output power of the HF welder can be automatically calculated according to the speed of the mill, reducing the waste of the steel pipe, improving the productivity and lowing the  operator skill.

     5. Ethernet Network Technology

The HF welder and control console are connected as distributed system using Ethernet communications. Compared with the hard-wire connection, it has the advantages of simple connection, lower customer maintenance cost. Compared with MODBUS communication and DP communication, it has faster speed and stronger anti-interference ability.

Welder Structure

1. The New Design of Inverter Power Module

The new cooling plate of power module is made of 12mm copper plate produced by CNC machine. The surface of the plate is tin-plated and the inner water channel is oval. The surface of the water-cooling plate is smooth and the cooling effect is better than before. The temperature of power devices are lower 3 ~ 5 degrees Celsius than that of the original inverter module, improving the safety of power devices.

                                                                                                                                  Figure 3 The new inverter power rmodul

2. High Frequency Absorb Capacitor based on PCB Board Structure

The high-frequency absorb capacitor layout of the inverter module is more reasonable than before, and it is more convenient to assemble and maintain. Moreover, the number of capacitors is three times than the original inverter module, and the effect of absorbing is better, ensuring the safe operation of power devices.

    3. New MOS Driver Board

The function of MOS fault detection, MOS negative voltage detection, MOS positive voltage detection is increased, which can effectively prevent the equipment working in fault state and reduce the secondary damage caused by incomplete maintenance.

    4. The Protection of Matching Transformer and Tank Capacitor

Temperature protection switch is installed on the matching transformer and tank capacitor, in order to prevent overheating and damaging caused by blockage of cooling water.

    5. Touching Screen Display on control console

The welder and the control console are connected by communication cable, and all the parameters such as the resonant frequency, active power, reactive power, DC voltage, DC current, and motor voltage and current are displayed on the touch screen on the console.