DC Servo Drive 1.5kW
High-performance brushed DC servo drive with embedded WiFi tuning and PLd/SIL2 safety contribution — designed for CNC machines and industrial servo axes.
Overview
The T&C Technology DC Servo Drive is a high-performance, safety-aware motor drive for brushed DC servo motors up to 1.5 kW (48V, 31A continuous). Built on the Raspberry Pi Pico 2W (RP2350 with integrated WiFi), it supports position, velocity, and torque control modes via the industry-standard STEP/DIR interface — a direct drop-in for stepper-based axes in CNC machines and industrial equipment.
The drive features RS-422 differential encoder feedback (quadrature + index) for precise position tracking, and an H-bridge power stage using Infineon IPP041N04NG MOSFETs with TI gate drivers and dual current-sensing shunts. The 20–30 kHz switching frequency produces low audible noise and smooth low-speed operation.
A unique embedded WiFi access point and web interface allow tuning of PID gains, motion limits, and operating mode from any phone or laptop — no USB cable or PC software required on the shop floor. A hardware enable switch must be in the safe state before any parameter change is accepted, preventing accidental motion during tuning.
The daisy-chainable ERRin/ERRout fault chain enables coordinated, near-instantaneous shutdown of all drives in a multi-axis system on any single fault, contributing to PLd (ISO 13849) / SIL2 (IEC 62061) machine safety ratings when integrated per the design guidelines.
Key Features
- 1.5 kW continuous power — suitable for machine tool and industrial servo axes
- STEP/DIR compatible — drop-in for any CNC controller or motion card
- WiFi-based tuning — no laptop software, tune from any phone browser
- Hardware safety interlock — prevents parameter changes with drive enabled
- Daisy-chained ERRin/ERRout — coordinated multi-axis e-stop
- PLd / SIL2 safety contribution when integrated per specification
- RS-422 differential encoder — immune to industrial EMI
- Infineon MOSFETs — 40V, 120A rated, 0.95 mΩ Rds(on)
Specifications
| Microcontroller | RP2350 + CYW43439 WiFi (Pi Pico 2W) |
|---|---|
| Motor Type | Brushed DC |
| Supply Voltage | 24–48V DC |
| Continuous Power | 1.5 kW (48V / 31A) |
| Peak Current | 60–80A (≤5 sec duty) |
| Switching Frequency | 20–30 kHz (centre-aligned PWM) |
| Encoder Interface | RS-422 differential, quadrature + index (Z) |
| Command Interface | STEP/DIR, 5V-tolerant, opto-isolated |
| Tuning Interface | Embedded WiFi AP + web UI (no PC software) |
| Safety Interface | ERRin / ERRout daisy-chain (active-low) |
| Control Modes | Position, Velocity, Torque (dual-loop) |
| Safety Rating | PLd / SIL2 contribution (with host system) |
| MOSFETs | Infineon IPP041N04NG (40V, 120A, 0.95 mΩ) |
| Gate Drivers | TI UCC27282, programmable dead time ≥500 ns |
Safety Architecture
The ERRin/ERRout daisy-chain allows multiple drives to share a single fault propagation signal. Any drive that detects a fault (overcurrent, overtemperature, encoder dropout) drives ERRout low, which propagates immediately to the ERRin of every upstream controller.
CNC Controller ──► ERRin │ DRIVE 1 │ ERRout ──► ERRin │ DRIVE 2 │ ERRout ──► ERRin │ DRIVE N │ ERRout ──► E-Stop Relay Any drive fault → ERRout goes LOW → all upstream controllers see fault within microseconds
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