Gemini 125H Bidirectional DC/DC Convertor

Gemini 125H Bidirectional DC/DC Convertor

Boco Electronics’ Gemini 125H Bi-directional DC-DC Converter is built on a next-generation SiC technology platform, delivering high efficiency, high power density, and superior reliability for advanced energy storage and PV applications.

It supports a wide DC voltage range of 600V–1500V, with a rated power of 125kW and 1.1× overload capability, enabling stable operation under dynamic load conditions.

With peak efficiency up to 99.2%, the Gemini 125H minimizes energy loss while maximizing system performance. Its advanced SiC-based design achieves a power density of up to 7.1 kW/L, supporting compact and high-performance system integration.

The converter adopts a bi-directional buck-boost topology, allowing seamless switching between buck and boost modes in both charge and discharge directions, enabling flexible adaptation to wide battery voltage ranges and diverse system architectures.

Designed for compatibility with high-capacity battery systems (280Ah, 314Ah, 320Ah), the Gemini 125H ensures optimized battery utilization and system efficiency.

For scalable deployment, it features built-in parallel operation capability, enabling flexible system expansion and higher power configurations.

An integrated MPPT algorithm further enhances its functionality, making the Gemini 125H ideal for PV-coupled and hybrid energy systems.

Introduction

Applications:

It can play a key role in energy storage system, DC coupling system, hybrid energy system, etc. The Gemini 125H can help the LPF, Sodium-ion battery, fuel cell system and PV to connect to DC bus easily and flexibly for power and energy extension.

Specifications:

Item	Value	Description
DC Bus Side ( Port A )
Nominal Voltage (VANOM)	1250V
Voltage Range (VAMIN~VAMAX)	600V~1500V
Overvoltage Protection (VAOVP)	1560+-20V (default)	1. Protection threshold can be programmed by communication; 2. Fault state is latched，it can be cleared by communication.
Undervoltage Protection (VAUVP)	550+-20V (default)
Nominal Current (IANOM)	100A
Current Measurement Accuracy	1.5% F.S.
Voltage Measurement Accuracy	0.5%	Nominal operation condition
Voltage Control Accuracy	0.5%	If droop control is adopted, the accuracy base refers to drooped voltage.
Battery Side ( Port B )
Nominal Voltage (VBNOM)	1250V
Voltage Range (VBMIN~VBMAX)	600V~1500V
MPPT Voltage Range (VMpptMIN~VMpptMAX)	600V~1400V
Overvoltage Protection (VAOVP)	1560+-20V (default)	1. Protection threshold can be programmed by communication; 2. Fault state is latched，it can be cleared by communication.
Undervoltage Protection (VAUVP)	550+-20V (default)
Nominal Current (IBNOM)	100A
Overcurrent Protection（IBOCP）	105%~120%，Protect after 20s >120%，Protect in 0.1s	1. Default protection threshold is 100A，it can be programmed by communication. 2. Fault state is latched，it can be cleared by communication.
Max. Continuous Power (PMAX)	125kW
Current Ripple (RMS value)	≤5% IBNOM	Nominal operation condition
Voltage Measurement Accuracy	0.5%	Nominal operation condition
Voltage Control Accuracy	0.5%	If droop control is adopted, the accuracy base refers to drooped voltage.
Current Measurement Accuracy	0.4%	Nominal operation condition
Current Control Accuracy	0.5%	Nominal operation condition
Efficiency
Peak Efficiency	≥ 99.2%
CEC Efficiency	≥ 99%	Nominal operation condition
Auxiliary Power
Auxiliary Power	Voltage：24V±2V Power Consumption：<65W
Protection
Fuses	Integrated	>=100kA, >=1500Vdc, L/R >=3ms
Short Circuit Protection	Integrated	Available for both input and output
Over Temperature Protection	Integrated	Protection threshold can be programmed by communication
Communication Failure Protection	Integrated	Default over time threshold is 0.5s，it can be programmed by communication
Mechanical
Dimension（W×H×L）	350×85×585mm	Excluded mounting ears
Weight	< 17kg
Cooling Type	Forced Air Cooling	>150CFM
Ingress Degree	IP10
Mounting	Screw
General
Operational Temperature	-25 ~ 45℃	Derating between 45~55℃, no condensing
Storage Temperature	-40~70℃	No condensing
Relative Humidity	5%~85%
Altitude	4000m	Derating above 3000m
Acoustic Noise	≤75dB，Tair<30°C ≤80dB，Max.	STC
Pollution Degree	PD2
Vibration and Shock	operation：IEC 60721-3-3, 3M12 Transportation：IEC 60721-3-2，2M5
Communication	RS-485，CAN，Ethernet
Safety
Withstand Voltage	Basic Insulation: 3.2kV, 50 / 60Hz, 60s Reinforced Insulation: 4.4kV, 50 / 60Hz, 60s	Basic Insulation: Input vs output, input/output vs enclosure. Reinforced Insulation: input/output vs communication ports
Overvoltage Category	OVC II
Standard	IEC 62477, IEC/EN 62109, UL 1741
EMC
EMI	IEC 61000-4, FCC Part15
EMS	IEC 61000-2
Function
Operation Mode	CC、CV、CP、MPPT
Power Response	<5ms	10%~90%
Black Start Up	Integrated
Parallel Operation	Up to 40 units in parallel in CV mode	Current unbalance < 7%
Life
Life Time	20 years	The fans may need periodic maintenance due to the environment
MTBF	400 000 Hours	Telcordia SR332 Issue 3

Competitive Advantage:

Flexible Setup

- Bi-directional Buckboost Power Conversion

- Wide Operation Range in 6:00–15:00VDC

- Compatible with V1, V2F, Sodium ion battery, etc.

- Up to 40 units in parallel with CV mode, easy for power balance between battery cluster

Multiple Function

- Multiple Operation Mode including CC, CV, CP

- Block Start-up Function available

- Integrated MPPT Algorithm

- 250kW Virtualized Module with 2 units

High Efficiency and Power Density

- SC: Integrated, Peak Efficiency >99.2%

- Control Unit, Power Relay and Fuse Built-in

- High Power Density up to 7.1kW/L

High Reliability

- Integrated OV/UV, OC, OT, OP Protection

- Short Circuit Protection with Fault Current Cut-off in µs

- Short Circuit Capacity R < 1500A/S

- IEC 62477, EC 62040, UL 1741 Certification

FAQ

Q: What is the rated voltage of Gemini 125H’s DC Bus Side (Port A)?

A: The nominal voltage of the DC Bus Side (Port A) is 1250 V.

Q: What cooling method does this converter use?

A: It adopts forced air cooling (fan cooling) with an ingress protection rating of IP10.

Q: What is the maximum number of units that can be paralleled?

A: Up to 40 units can be paralleled in CV mode, with a current imbalance of ≤ 7 %.

Q: What communication protocols does the Gemini 125H support?

A: It supports RS485, CAN, and Ethernet communication protocols.

Q: What is the efficiency performance of this converter?

A: Its peak efficiency reaches 99.2 %, and the CEC efficiency is 99 %.

Q: What application scenarios is the Gemini 125H suitable for?

A: It is suitable for energy storage systems, DC coupled architectures, and hybrid energy systems, enabling flexible integration with LiFePO₄ batteries, sodiumion batteries, fuel cells, and PV sources via a DC bus.

Q: What protection functions does this product have?

A: It integrates comprehensive protection functions, including short circuit protection, over temperature protection, over/under voltage protection, over current protection, and communication failure protection. Most protection thresholds are configurable via communication interfaces.

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