Small Thyristor Frequency Converters for Induction Heating

Small Thyristor Frequency Converters for Induction Heating

Series-TMK-R Frequency converters are designed for supplying power to smaller induction heaters, melting furnaces and other technological devices with an output of up 60 kW and a working frequency of up to 10 kHz.


Series TMK-R converters consist of a main switch (1), main circuit-breaker (2), anti-jamming module (3), three-phase rectifier (4), intercircuit filter (5), voltage converter with reserve diodes (6), and capacitors (7), making an oscillating circuit together with a medium-frequency transformer (8), and finally an inductor (9) designed such, that an oscillating circuit is created.

Operational tasks and fault monitoring are handled by a PLC coupled with a controller (10). The output requirement is set via the LCD display interface. System failures are also detailed on the display.

Electronic and power circuit components are cooled by an open-loop water system.

Conclusion of EMC Test Protocol

Model TMK-R Frequency converters comply with resistance test standards set by ČSN EN 50082-2, ČSN EN 61000-4-2, ČSN EN 61000-4-4, ČSN EN 61000-4-6 and ČSN EN 61000-4-11.

TMK-R Parameters  

Output [kW] 60
Frequency Range [kHz] 5 - 10
Output voltage [V] max. 500
Supply voltage 3N~50Hz, 230/400V/TN-S
Energy input [kVA] 72
Cooling water:
- Consumption1) [m3/hr]
- Input pressure [MPa]
- Input temperature [°C]

max. 0,4
max. 32
Weight [kg] 325
Ratio of MF transformer 2) 1:1 až 1:9


  1. The listed water requirements include the inductor loop.
  2. The unit is provided with one transformer ratio.  A suitable supply is set according to the required load.  Optimal settings are recommended to be carried out by the connected equipment's manufacturer. The mid-frequency transformer can be built into the converter, or it can be located externally.

Advantages of TMK-R

  • high efficiency
  • range of output setting 2% - 100% of nominal value
  • high value of inlet power factor - compensation in the mains is not necessary
  • matching transformer on converter input is not necessary - lower installation costs
  • load matching by parallel or serial oscillating circuit, or a particular inductor.

Optional accessories:

  1. Cooling unit CH 30 (water-to-air heat exchanger).
  2. Interconnection cables between transformer load and converter input if the transformer is placed externally.

Dimensional sketch

The composition and design of our TMK-R frequency converter allows for the further design of other variations of this technology. Please don't hesitate to contact us. Our engineering team welcomes the opportunity to discuss any technical implementation scenarios with you.



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