Low Voltage, High Current DC Power Supply: Applications & Features

Key Takeaways

• Low voltage, high current power supplies support a diverse range of applications, including electric vehicle testing, welding, semiconductor manufacturing, and more.

• Features of these power supplies are SCR technology, programmability, and bi-directionality.

• Low voltage, high current setups are less common due to practical limitations, such as the need for thick cables, high transmission losses, and inefficiencies in certain applications.

Close-up shot of a variety of power supplies.

Low voltage, high current power supplies are generally designed to operate anywhere from tens of volts to millivolts, with currents in the tens of amps and upwards. These units are engineered to provide power to resistive evaporation sources, meeting the industry's increasing demands for versatility and reliability. 

Low Voltage, High Current Power Supplies Are Essential for Operational Efficiency and Safety

Low voltage, high current power supplies are suitable for electric vehicles, welding, spot welding, industrial machinery, battery charging, and electromagnetics, where substantial current at lower voltages is essential for operational efficiency, safety, and effective power delivery. Low voltage, high current power supplies are moderately suitable for semiconductor testing and audio systems, where low voltage power is required, but the high current demands can introduce challenges such as noise and voltage stability.

Typical Features of a Low Voltage, High Current Power Supply

Some typical features of a low voltage, high current power supply include SCR (Silicon Controlled Rectifier) technology and current limiting, soft start, and interlock switches to enhance user-friendliness and operational ease. These features make low voltage, high current power supplies highly effective and safe for use in various industrial applications. For high current needs, multiple linear regulators can be used in parallel. 

Other typical features of low voltage, high current power supplies include:

• Voltage and Current Range: These units typically offer voltages below 60V, with current outputs ranging from 60A to over 800A. 

• Power Capacity: These devices' power output, given by the product of voltage and current, can be very high—ranging from a few hundred watts to several kilowatts.

• Programmability and Stability: Many of these units are programmable, which allows precise control over output parameters through software interfaces. This feature is crucial for applications requiring specific power profiles or automated testing sequences.

• Bi-Directionality: Some models are bi-directional, meaning they supply and absorb power. This is particularly useful in battery testing and simulation scenarios where both charging and discharging are necessary.

Topologies

Traditionally, the more common topology of these supplies is a linear power supply. However, these supplies are often bulky, costly, and inefficient, especially at high currents. Recent developments in switching power supply technology allow them to be used instead of linear ones for high-performance needs. 

Switching power supply designs must be affordable, compact, balance low output noise, and rapidly respond to changes. Reducing output noise typically involves extensive filtering or larger filters, which can increase costs, reduce efficiency, and slow response times. For IC testing applications, it's crucial to assess the power supply's voltage transient response and output impedance to ensure it meets performance standards.

Why Are Low Voltage, High Current Power Supplies Uncommon?

Low voltage/high current setups, like powering a 1.5kW water kettle at 20V and 75A, are uncommon due to their inefficiency and impracticality. This configuration requires thick cables to safely handle the high current, increasing costs and reducing manageability. 

Additionally, higher currents significantly raise transmission losses, as cable power loss is proportional to the square of the current (P = I²R). In contrast, operating the same kettle at 230V requires only 6.5A, allowing for thinner, more manageable cables and substantially lower transmission losses. Since our electrical infrastructure typically delivers high voltages, such as 230V directly, utilizing these existing setups is more practical and energy-efficient.

AC/DC and DC/DC Supplies

A low voltage, high current power supply can be AC/DC or DC/DC.

• AC/DC power supplies can be both open-frame and enclosed models or medium to high power units featuring highly configurable modular models and rack-mounting bulk power units. These modular systems may be available as individual power modules that can provide something around 3,000 watts, with the potential to configure systems for total outputs up to 24,000 watts or more. 

• For DC/DC conversion, multiphase buck converters are integral for efficient voltage reduction, such as those commonly utilized in PC motherboard CPU VRMs. These converters distribute the load across multiple phases, thus enhancing efficiency and longevity. Buck converters are an example of highly efficient DC-DC converters that step down voltage while simultaneously increasing current, making them ideal for applications requiring lower operating voltages. 

PSpice for Low Voltage, High Current Supply Designs 

The range of applications for low voltage, high current power supplies—from electric vehicle testing to industrial machinery and semiconductor manufacturing—requires versatile design tools. PSpice is uniquely equipped to address these needs, with extensive component libraries and thermal analysis features. 

Engineers can use PSpice to simulate various scenarios and ensure power supplies are efficient and meet the requirements of each application, preventing potential issues that could delay the project and increase costs. 

How PSpice Features Can Be Used for Power Supply Design

Looking to design your own low voltage, high current power supply? Discover how Cadence PSpice (which is integrated with OrCAD X) provides the essential tools you need for efficient and reliable power supply design. Explore PSpice and OrCAD X now to power up your projects with confidence!