Thyristor Frequency Converters 0.2 - 10 kHz

TMK Series frequency converters are designed to supply power to equipment that incorporates technology currently used in induction heating, hardening, melting and/or other applications where a parallel resonant circuit is required.

Principle

TMK Converters consist of an input power supply switch (QS), a controlled rectifier (1), suppressor (2), current converter (3), starting circuit (4) and over-voltage protection (5,6). Power supply is provided from LV or HV mains (50 Hz) through a matching transformer (sold separately).

All regulating, monitoring and control functions are handled by a PLC-based system. A filtered closed-loop water cooling system is used to control the temperatures of the various electrical/electronic components of the system.

TMK Design

The frequency converter is built into two connected heavy-duty steel cabinets with an IP-43 protection rating. The left cabinet contains the rectifier, converter, suppressor, input/output terminal boards, voltage sensors and over-voltage protection components, water temperature/flow sensors and a cool-water distributor with its own pressure and temperature sensors. The lower-half of the right cabinet contains the pump and a water-to-water heat exchanger. Control circuits including the controller rack and PLC are mounted in the upper-right half. Forced air circulation is provided for both partitions. Air cooling is assisted by a water-to-air heat exchanger located mid-cabinet.

Water cooling is accomplished through a two-circuit system. The closed inner-loop provides cooling for the thyristors, transistors, and the suppressor. The circuit is designed with non-ferrous (non-conductive) materials and is filled with a low-conductive liquid. The power circuits contains disc-shaped thyristors (dual-cooled) and IGBT transistors (also water-cooled).

System temperatures are constantly monitored and regulated by the central controller. The open (outer-loop) system is fed by the customers external water supply. In addition to its enhanced overall design and construction, the new control circuit system makes the TMK-series frequency converters an outstanding technological achievement in the field of current converters.

Advantages of TMK

high efficiency throughout the entire output range, over 90%
variable range of the output power adjustment from 10% to 100% of the nominal value
variable range of the output frequency (f_min–f_max) 30% - 100% of the nominal value
a closed-loop cooling circuit with a low-conductive water system helps reduce the negative electrochemical effects to the cooling components and provides improved insulation for the power circuits
start and run reliability within a wide range of load impedance
converter design also facilitates installation in a dusty environment
perfect galvanic separation of control and power circuits
clear and simply-interfaced controls provide quick system fault location in order to decrease down-time
high-interference immunity for control circuits

TMK Specifications

Frequency converters for induction heating, hardening and melting furnances requiring a parallel resonant circuit:

Typ	U₂ [V]	f_max [kHz]	f_min - f_max [kHz]	P₂ [kW]						A [mm]
TMK - F1	600 650 680	0.6 1.5 3 4 6 8 1.5	0.2 - 0.6 0.5 - 1.5 1 - 3 1.5 - 4 2 - 6 3 - 8 0.5 - 1.5	100 100 100 100 100 200 630	120 120 120 120 120 250	160 160 160 160 160	200 200 200 200	250 250 250 250	315 315	1430
TMK - F2	600 800	0.6 1.5 3 4 6 1 1.5 3	0.2 - 0.6 0.5 - 1.5 1 - 3 1.5 - 4 2 - 6 0.4 - 1 0.5 - 1.5 1 - 3	400 400 315 315 200 800 800 630	500 500 400 400 250 1000	630 630 500 315				1430 1830
TMK - G1	400 500	10 10	4 - 10 4 - 10	80 100	100 120	120 160				1430
TMK - G2	400 500	10 10	4 - 10 4 - 10	160 200	200 250					1430

Frequency converterss for melting furnances with series-parallel resonant circuit:

Typ	U₂ [V]	f_max [kHz]	f_min - f_max [kHz]	P₂ [kW]	A [mm]
TMK - F1	750	1,5	0,5 - 1,5	do 400	1430
TMK - F2	750	1,5	0,5 - 1,5	do 630	1430

Dimensional sketch

Type marking

Model Number legend for frequency converters:

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

Frequency converter type TMK-F2