MEAN WELL Product Manager, Kai Li, and Sager Electronics Technical Support Manager for Power, Don Baldwin
A growing number of industrial systems require direct current (dc) voltages greater than 60 volts (V) and use power supplies with outputs of 115, 230, and even 380 Vdc to support applications like charging green energy storage systems and electric vehicles, powering communications and computing systems, UV curing, electrolysis, laser, and burn-in applications, and DC microgrids in commercial and industrial buildings and greenhouses. These applications often need power systems that can deliver 10 kilowatts (kW) or more and have communications options that can speed system integration and support high levels of reliability and flexible operation. They can also benefit from using three-wire, three-phase delta, and wye ac power inputs, a choice of forced air or liquid cooling, plus they need to be compact and highly efficient.
Designing custom and purpose-built power supplies with outputs of 115, 230, and 380 Vdc from scratch is a time-consuming and risky endeavor that can extend time to deployment and increase system costs. A faster, lower risk, and highly cost-effective option for designers of automation systems, industrial processes, and infrastructure installations are off-the-shelf high-wattage three-phase input digital power supplies with high output voltages.
This article presents some of the communications and control protocols used with high-wattage HVDC power supplies and briefly reviews exemplary applications. It then details specific 3-phase 10 kW high voltage power supplies from MEAN WELL that support compact, efficient, and reliable solutions, and closes with a brief look at 3-wire delta and wye 3-phase AC connections and how they can be implemented with those power supplies.
Depending on the application, communication protocols like control area network bus (CANBus), Modicon bus remote terminal unit protocol (MODBus-RTU), or the power management bus (PMBus) can be required. All three are based on serial bus structures. CANBus and MODBus-RTU are general-purpose industrial communications protocols that can be integrated into power supplies, and PMBus is specifically designed to support power management functions.
CANBus is a multi-master message-based protocol, while MODBus-RTU and PMBus are master-slave request-response protocols. CANBus is used in a variety of automotive and industrial control systems, the MODBus-RTU protocol is found in industrial control and building automation systems, and PMBus is widely used for power management and includes monitoring and control functions aimed at data centers, communications systems, and other applications.
Another important consideration when selecting a communications bus is transmission distance versus data rate. MEAN WELL's CAN bus products meet ISO 11898, and the maximum bus rate is 250 kilobits per second (kbps) with a connection distance of at least 150 meters (m). MODBus-RTU can operate over connections up to 1,200 m with transmission speeds up to 19.2 kbps. PMBus is limited to 10 m connections and supports up to 400 kbps.
The SHP-10K 10 kW power supplies have CANBUs as a standard feature, with MODBus and PMBus available as options (Figure 1). CANBus is often preferred for a wide range of industrial control applications like production lines for several reasons, including:
Latency– message arbitration rules ensure that the highest priority CANBus message will be sent first when multiple messages are sent simultaneously.
Reliability– the use of twisted pair wiring and differential signaling make CANBus installations relatively insensitive to electromagnetic interference (EMI). In addition, CANBus networks use fewer cables and connectors, further enhancing reliability.
Cost – The combination of twisted pair wiring, fewer cables and connectors, and inherent EMI resistance lead to lower costs for CANBus installations in industrial control applications.
Digital HVDC power
Designers of systems that need 10 kW or more can benefit from the SHP-10K series of HVDC power supplies from MEAN WELL. Up to four of these AC/DC power supplies can be operated in parallel to deliver up to 40 kW with efficiencies of up to 97%. They work with three-phase input voltages from 340 to 530 Vac and have active power factor correction that delivers a typical power factor of 0.98. Models are available with output voltages of 55, 115, 230, and 380 Vdc to suit various application requirements.
These power supplies include an array of standard functions to speed system integration, including output programming, active current sharing for paralleled units, and remote ON-OFF control. They also have over voltage, overload, short circuit protections, and an auxiliary power output that delivers 12 Vdc at up to 1 A, plus monitoring signals including over temperature alarm, DC-OK signal, fan fail alarm, and AC fail alarm.
The fully digital design combined with CANBus, or the optional MODBus or PMBus, enables output voltage and current programming. These power supplies meet the safety requirements of EN/UL62368-1, are only 2U high, and can be installed in a standard 19-inch rack. For added flexibility, they are available in forced air and liquid-cooled versions (Figure 2). The liquid-cooled models can be mounted on an optional liquid-cooled cold plate or a cold plate included in the equipment design. All models are rated to deliver full power from -30 to +50 °C and can be operated up to 70 °C with derating.
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Examples of available models with standard CANBus communications include:
When three phases are better than one
Three-phase AC power is often found in commercial and industrial facilities, data centers and communications installations that house high-power equipment. Three-phase AC can deliver more power with higher efficiency than single-phase AC. The three wires used for three-phase power can be a smaller gauge and use less copper compared with the two wires needed for single-phase power. And three-phase power sources tend to have higher voltages than most single-phase power sources. Those attributes combined enable more power delivery with higher efficiency when using a three-phase power distribution system.
Three-phase power is commonly available in delta and wye configurations. MEAN WELL's SHP-10K digital HVDC power supplies can be connected to either configuration with equal efficiency (Figure 3).
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The SHP-10K family of digital HVDC power supplies from MEAN WELL is a good match for a wide range of industrial, commercial, communications, and data center power applications. It provides designers with a highly flexible power platform, including a selection of communications buses, a choice of cooling options, and a wide range of built-in monitoring, protection, and control functions. Its wide-range, three-phase AC input, extended operating temperature capabilities, and low-profile 2U design further enhance the utility and flexibility of these high-efficiency AC/DC power supplies.