M-Press Systems (M) Sdn. Bhd.
Industrial Microwave-, Plasma-, RF- and Control-Systems

Power Supplies

We offer a broad range of high-tension and filament power supplies, enabling you to choose the optimum technology for your application, based on cost efficiency, energy efficiency and output ripple. All our power supplies are designed for maximum possible efficiency, reliability and a long service life, available designs / technologies include:

LC power supplies

LC power supply These constant output power supplies are based on a resonant half wave voltage doubler circuit and are still the most cost efficient power supplies, as they basically only consist of a single-phase transformer, a high-tension diode and a capacitor. They are suitable for smaller Magnetrons with an output power of up to approximately 3 kW and are till now the most commonly used power supplies in household microwaves, even though their overall energy efficiency is somehow limited. Because of their design they are only suitable for applications where the pulsed operation of the Magnetron is acceptable, e.g. for microwave drying and heating.

Thyristor controlled power supplies

Thyristor controlled power supply In comparison to LC power supplies these power supplies are using a thyristor or TRIAC based phase control circuit, which enables them to adjust the high-voltage supplied to the Magnetrons and therefore control the microwave power emitted by the Magnetrons. Disadvantages, especially when compared to switch-mode power supplies, are a limited energy efficiency and a high ripple due to their pulsed operation, which makes them unsuitable for certain applications. Due to the limited energy efficiency thyristor controlled power supplies are also mainly used for Magnetrons with an output power of up to approximately 3 kW.

Linear power supplies

Linear power supply Linear power supplies, also known as conventional (transformer based) power supplies, are based on 3-phase line frequency high-voltage transformers, suitable rectifier circuits as well as choke coils to further reduce the output ripples of these power supplies. The output power of the Magnetrons is usually controlled respectively adjusted via the magnetic field of the Magnetron, which makes these power supplies suitable for applications where an adjustable microwave power source is required. Advantages of these power supplies are their simple and rugged design, which also ensures easy troubleshooting and maintenance, as well as their relatively low cost. Disadvantages, especially when compared to switch-mode power supplies, are a relatively high output ripple and a high weight as well as a big footprint. Depending on the required output power there are two basic designs:

6-pulse power supplies

6-pulse power supplies (designation: 3Ph2W6P) are consisting of a transformer with 3-phase primary and secondary connections and a 3-phase bridge rectifier circuit for the generation of the high-voltage DC output. With a properly sized anode current choke coil the output ripple of these power supplies is typically around 10 %. They are suitable for Magnetrons with an output power of up to approximately 30 kW and applications which can accept the remaining output ripple, e.g. microwave drying and heating and less demanding plasma applications.

12-pulse power supplies

12-pulse power supplies (designation: 3Ph2W12P) are consisting of a transformer with a 3-phase primary and two 3-phase secondaries connected in a special arragement, as well as a 6-phase bridge rectifier circuit for the generation of the high-voltage DC output. Due to their higher output frequency they offer lower ripple with a smaller choke coil even at higher loads, typically around 5 %. This makes them particularly suitable for high-power microwave generators of up to 100 kW. Advantages and disadvantages as well as typical applications are basically the same as for the 6-pulse power supplies.

Switch-mode power supplies

Switch-mode power supply Switch-mode power supplies offer the best performance of all power supplies, they can reduce the output ripple of the Magnetrons to values below 5 % and permit optimum control of output power, anode current limitation etc. They are available with an output power ranging from below 3 kW up to 100 kW, depending on the total output power they require either a single-phase or 3-phase mains connection. Due to their higher cost they are mainly used for more demanding plasma applications, e.g. in the semiconductor industry.

Low ripple power supplies

Low ripple power supply Low ripple power supplies are also based on the highly energy efficient switch-mode technology, however due to the special design of their switch-mode circuit they are capable of delivering a DC output with a ripple smaller than 1 %. This makes them not only suitable for very demanding plasma applications, but also for special applications where the spectral bandwidth of the Magnetrons must be narrowed down as far as possible, i.e. where the Magnetrons produce most of their output power within a very small frequency band. Another valuable feature for special applications is that these power supplies can be operated in pulsed mode, with an output frequency ranging from 500 Hz up to 20 kHz.

Filament power supplies

We also manufacture and supply a wide range of filament power supplies for Magnetrons with an output power ranging from a few 100 W to 100 kW. Our filament power supplies offer soft start for reduced filament surge current and precise control of filament current reduction, also known as "Filament schedule". This ensures maximum lifetime of the Magnetrons and stable operation at varying output power.

Should you require further information about the power supplies available from us please contact us.