Main PDB

Humanoid Robot Power Distribution Board

This repository contains the power distribution board design for the Wiscohumanoids humanoid robot. The board distributes the main battery power to the robot’s high-current actuator system and generates regulated lower-voltage rails for compute, servos, sensors, and control electronics.

The PDB is designed around a 48 V main power system with onboard regulation for the robot’s auxiliary electronics.

Project Overview

The power distribution board is responsible for taking the main battery input and safely distributing power throughout the robot. It includes high-current 48 V distribution, onboard buck converters, current sensing, precharge circuitry, and protection/disconnect circuitry.

The main goals of this board are:

• Distribute 48 V battery power to actuator rails
• Generate a 24 V compute rail
• Generate a 6 V servo rail for the robot hands
• Generate a 3.3 V rail for sensors and control electronics
• Monitor current on important power paths
• Limit inrush current during startup using precharge circuitry
• Separate actuator/servo power from compute/control power through protection and disconnect circuitry
• Protect the electrical system from voltage transients and fault conditions

System Power Architecture

Battery Input
    |
    |-- Precharge Circuit
    |
    |-- Main 48 V Power Rail
            |
            |-- Protection / Disconnect Circuitry
                    |
                    |-- Actuator / Servo Power Group
                    |       |
                    |       |-- 48 V Actuator Distribution
                    |       |
                    |       |-- 48 V to 6 V Buck Converter
                    |               |
                    |               |-- Hand Servos
                    |
                    |-- Compute / Control Power Group
                            |
                            |-- 48 V to 24 V Buck Converter
                            |       |
                            |       |-- Compute / Embedded Electronics
                            |
                            |-- 48 V to 3.3 V Buck Converter
                                    |
                                    |-- Sensors / Current Sensors / Control Logic

Power Rails

Major Board Features

48 V Actuator Distribution

The main power path distributes 48 V battery power to the robot’s actuator system. Because this rail carries the highest current on the board, the layout uses large copper pours, short current paths, and high-current connectors.

This section of the board is designed to minimize voltage drop and reduce heating under actuator load.

Precharge Circuit

The board includes a precharge circuit to limit inrush current when the battery is connected. This is important because the board contains large bulk capacitance on the main 48 V rail.

During startup, the precharge path slowly charges the bulk capacitors before the main power path is fully enabled. This reduces stress on connectors, switches, relays, and other power components.

Protection and Disconnect Circuitry

The PDB includes protection and disconnect circuitry that separates the main power system into two groups: the actuator/servo power group and the compute/control power group.

The actuator/servo group contains the 48 V actuator distribution and the 6 V hand servo rail. This group can be disconnected from the rest of the system so high-power motion components can be shut down independently.

The compute/control group contains the 12 V and 3.3 V rails. This allows the robot’s control electronics, sensors, and compute hardware to remain separated from the high-power actuator section.

This separation is important because it allows actuator power to be disabled while keeping control electronics available for monitoring, communication, and safe shutdown behavior.

Protection features include:

• Input transient voltage protection
• Precharge/inrush-current limiting
• Separation between actuator/servo power and compute/control power
• Reverse-current blocking where needed
• Current sensing for fault monitoring
• Support for external E-stop or main disconnect circuitry
• Bulk capacitance for load transients

Current Sensing

Current sensors are included on important power paths so the robot can monitor how much current different parts of the system are drawing.

Current measurement is useful for:

• Detecting abnormal load conditions
• Debugging actuator behavior
• Estimating power usage
• Monitoring system health
• Adding future fault-detection logic

Buck Converters

The PDB generates the lower-voltage rails from the main 48 V battery input using buck converters.

The onboard regulated rails are:

• 12 V for compute and embedded electronics
• 6 V for hand servos
• 3.3 V for sensors and control electronics

Each buck converter section includes the switching regulator circuit, input capacitance, output capacitance, feedback network, and supporting passives.

Grounding

The board uses separate ground naming to keep high-current power paths and sensitive measurement/control paths organized.

Typical ground nets include:

These grounds are not meant to be completely isolated systems. Instead, the separate names help control where large return currents flow and help keep sensor and feedback references cleaner.

Design Status

This project is currently in development.