Part 3 Introduction to Medium Frequency Power Supplies
1、Mid-frequency power supply electric cabinet: adopt the upper in and lower out line.
The arrangement of the cabinet is simple and reasonable, the main circuit is isolated from
the control circuit, the wearing parts are easy to replace, and there are necessary safety
protection measures.
2, the main circuit: the power supply uses silicon controlled parallel resonant circuit,
which has high reliability, easy protection, and the inverter bridge has a certain fault
tolerance for the trigger pulse, compared to the series resonant circuit and IGBT power
supply is easy to achieve short-circuit protection, is the preferred power supply structure of
large foreign companies.
The inverter SCR is made of national brand, the reserve number of current and
voltage is ≥2.5 times, the rectifier element is made of national brand, all SCRs are
subjected to severe 72 hours continuous high temperature blocking and full dynamic
testing, so that the installed components have high reliability; the external absorption
parameters of the components are instantaneously and dynamically optimized for
screening, so that the irreversible deterioration caused by the phase change spike voltage
on the components is reduced to a minimum. fundamentally improves the service life of
the equipment.
3、Compensation capacitor: large-capacity electric heating capacitor, so that the complete
set of equipment covers an area as small as possible.
(1) Adopt all-digital ultra-large-scale integrated circuit, single-board structure, and all
devices are screened by high-temperature aging. The control circuit adopts digital control
and has strong anti-interference ability. In addition to the conventional control functions of
rectifier, inverter, overvoltage, short circuit, current limit and voltage limit, it also has fault
self-diagnosis function and fault delay function.
(2) Adopt zero-voltage intelligent scanning starting circuit to ensure the reliability of
starting with crucible pot mode and starting with full and freezing furnace; meanwhile, it
has conventional automatic repeat starting function.
(3) The output power is continuously adjustable to meet the needs of oven, melting,
heating and keeping warm.
(4) The specially designed inverter angle control loop can adjust the equivalent load
impedance in real time by controlling the inverter angle according to the working
condition of the load, so that the power supply and the load are in the best match, so that
the power supply is always in the maximum possible output state, and the power factor can
reach above 0.95, which maximizes the output of the equipment. In this way, the
equipment can reach constant power output within the whole range of working conditions
allowed by the process, which speeds up the melting speed; after reaching the rated
temperature, it can realize automatic heat preservation and save power.
(5) Only one potentiometer is needed to adjust the output power, which realizes
"foolproof" operation and avoids damage to the equipment due to misoperation. In the
production process, there is no need to manned the power status and other operations
except power setting.
(6) The voltage and current are controlled by double closed-loop non-differential control,
which not only can overcome the fluctuation of the power grid and the disturbance of the
load change, but also is non-differential regulation in the voltage and current limiting
condition, without the loss of equipment output caused by the traditional voltage and
current cut-off conditions.
5.anti-interference 6 pulse control board manual
KGPS-6D IF power supply control board is a new type of six pulse wave control
board developed by our company for IF power supply with 3-phase rectification in the
main circuit.
KGPS-6D IF power supply control board mainly consists of power supply, regulator,
phase shifting control circuit, protection circuit, start-up algorithm circuit, inverter
frequency tracking, inverter pulse formation, pulse amplification and rectifier pulse
transformer. The circuit is digitalized except for the regulator, so it has the characteristics
of high reliability, high pulse symmetry, strong anti-interference ability and fast response
time.
Medium frequency power supply control board
KGPS-6D IF power supply control board and the previous control board have made a
lot of improvements in protection, after all the protection actions, it needs to be manually
reset to start, which can avoid the power supply starting by itself after the fault disappears;
such as water failure, phase loss. At the same time, it is convenient for maintenance
personnel to find faults.
This control board has a function to detect whether the power
potentiometer back to zero, after the power supply to power and reset automatically detect
the potential of the potentiometer ADJ end, if the ADJ end is not zero potential will start a
forced reset, RST indicator light, blocking the rectifier pulse, the potentiometer back to
zero, RST automatically extinguished, rectifier pulse open, you can start normally. This
function can avoid the damage to the equipment and the impact to the power grid caused
by the wrong operation of high power start, thus reducing the failure rate of the power
supply and the danger to the staff
