TPT September 2010

A rticle

This new modular approach to the power supply is a very effective solution to satisfy a wide range of load requirements, from low to high voltage at high frequency, avoiding the use of transformers or reactors between capacitor banks and output coil and thus increasing the overall efficiency.

7 Literature

[1] M K Kazimierczuk and D Czarkowski. “Resonant power converters”, John Wiley & Sons, Inc, New York, 1995 [2] Cesano, Stra, “Resonant loading converter using adaptive controller optimized for thermal treatment having large range of working frequencies”, IHS 98, Padova, pp 11–16 [3] Dede, Jordan, Gonzalez, Linares, Esteve, Maset, “Conception and design of a parallel resonant converter for induction heating” – Applied Power Electronics Conference and Exposition, 1991. APEC 91 Conference Proceedings, 1991, pp 38–44 [4] Dede, Esteve, Garcia, Navarro, Carrasco, “On the design of high frequency series resonant converters for induction heating applications” – Industrial Electronics, Control, and Instrumentation, 1993. Proceedings of the IECON 93, pp 1303–1307 [5] Dawson, Jain, “A comparison of load commutated inverter systems for induction heating and melting applications”, IEEE Transaction on Power Electronics, Vol 6, n°3, July 1991, pp 430–441 [6] Li Jingang, Zhong Yanru, Zhao Miao, “Study on a New Method of Voltage-Source induction Heating Load-Matched”, 2006 International Power Electronics and Motion Control Conference, IPEMC 2006

Figure 12 : Welding output head

The module paralleling has been tried in a high power generator for pipe welding. The production range is from diameter 76mm up to 152mm with thickness from 1 to 5mm. Considering the mill speed, the power requirement is around 450kW and the optimal frequency is 330–370kHz. The output head is presented in figure 12.

Some data read during the welder starting test is proposed in table 2.

Pipe [mm]

Speed [m/min]

% volt

% curr

% pow % freq

102x3

55

72

75

55

74

76x4

53

78

80

62

74

Table 2 : Report of the welding test In both cases, the load is practically matched: the result has been obtained by changing the coil diameter (from 150mm to 115mm). The frequency is constant at 330kHz. 6 Conclusion The main characteristics of a novel modular power supply system have been presented with reference to the topology, the choice of electronic components, the control system and the role of load matching. After a brief presentation of the main advantages and drawbacks of this system, some real experimental data demonstrates the feasibility and reliability of this power supply for two different applications: high frequency induction hardening and induction tube welding.

R&D Department Power Electronics Division SAET Group Via Torino 213 – Leinì (TO), Italy Department of Electrical Engineering, University of Padova Via Gradenigo, 6/a, 35131 – Padova, Italy

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S eptember 2010

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