High-power, high-voltage DC/DC converter combined with DC/AC inverter, Zekatex

The YellowBee AC/DC/AC is a cabinet mountable device for multi-purpose applications. Providing various modes of operation, programmable limitations and additional logic integration possibilities, it can easily turn into the heart of your power solution. It consists of the following components:

  • 3 x DC/DC Converters that can work independently or can be combined into one for higher current rate
  • 1 x 3-phase DC/AC Inverter
  • 1 x 3-phase Diode Bridge Rectifier
  • 2 x Choppers (one of them for internal protection)

Having numerous communication interfaces including Ethernet, RS485 and CANBus and utilizing Modbus, makes the integration with your industrial network an easy task. Profibus interface is also available using the Zekatex GreenBee Modbus-to-PROFIBUS GatewayThe integrated Modbus master allows different Modbus slaves to be attached to extend IO and functionality.

Several digital and analog inputs and outputs are available for additional programming and logic allowing extra flexibility during the system design or an ongoing project.

Powered by the ZekaStream™ technology you will be able to display the electrical characteristics and diagnose the health of the system with an unprecedented resolution for the industry. Only one such device in your design is enough to change the way you commission the whole power plant.

Having a design with fully integrated control, power units and filter bank balances the size and the weight of the installed components. Mounting and servicing of these usually heavy components within the cabinet becomes a much more comprehensive task.

The YellowBee AC/DC/AC Converter can easily fit in systems such as UPS, transformer pre-magnetization, battery charging and many other multi-functional applications. Or you have an idea how to use it in your design - just drop us a note!

It has already been integrated in some very complex Megawatt power plants like the latest Transocean drillships of type Ultradeep Water including the ones with the first hybrid drill-floor in the world.


Technical specification



Diode Bridge Rectifier nominal current

25 A rms

DC-Link voltage

450 - 700 Vdc

DC-Link capacitance

640 uF / 800 Vdc

DC-Link capacitors discharge time

< 7 min

DC/DC: Minimum input voltage

89 Vdc

DC/DC: Nominal input voltage

120 Vdc

DC/DC: Maximum input voltage

150 Vdc

DC/DC: Nominal current

20 Adc

DC/DC: Maximum current (95Vdc input voltage)

40 Adc (for 20s)

DC/DC: Input current ripple

13A rms

DC/DC: Switching frequency

10 kHz step up

20kHz step down

DC/AC: Nominal output voltage

480 Vac

DC/AC: Maximum output current

38 Aac (cos phi = 0.15, for 20s )

DC/AC: Maximum active power

20 kW

DC/AC: Nominal output current

30 Aac

DC/AC: Frequency range

1 - 70 Hz

DC/AC: Switching frequency

10 kHz

Internal Protection Brake chopper: Hardware ON level

900 V

Internal Protection Brake chopper: Hardware OFF level

850 V

Internal Protection Brake chopper: Maximum energy

2000 J

External Break chopper: ON Level

Software settable

External Break chopper: OFF Level

Software settable

External Break chopper: Nominal current



~ 93 % (without external transformer)

Mechanical Dimensions (W x L x H)

365 x 470 x 180 mm


35 kg


Forced air – internal fans, monitored

Ambient temperature

5 °C to 55 °C

Humidity class

F to DIN 40040

Degree of protection


Insulation test voltage

2550 Vdc / 1min


Communication interfaces



1x Modbus RTU slave


1x Modbus RTU master


1x Modbus TCP slave


1x CAN

CAN (proprietary)





IEC 61000-4-4:2004

Electrical fast transient (Burst) ( 2 kV power , 1 kV signal )

IEC 61000-4-5:2006

Surge voltage ( 0.5 kV L-L , 1 kV L-GND )

BDS EN 61000-4-6:2009

Conducted radio frequency interference ( 3 Vrms / 150 kHz – 80 MHz )

IEC 61000-4-2:2009

Electrostatic discharge ( 6 kV contact , 6 kV air )


Mechanical vibration of shipboard equipment

BDS EN 60068-2-1:2007

Environmental testing – Test A: Cold ( 5 °C)

BDS EN 60068-2-2:2008

Environmental testing – Test B: Dry heat ( 55 °C)

BDS EN 60068-2-78:2013

Environmental testing – Test Cab: Damp heat ( 40 °C)


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