BD3 fast eddy current brake power supply interface


BD3 interface is an essential device used to power eddy current dyno brake. Is carries out following tasks:

  • Mains AC to DC conversion to power the brake winding.
  • Brake current regulation according to received logic-level PWM signal or CAN bus message


  • Supply: 100-415VAC, 50-60Hz, 1-3 phase
  • Nominal brake current up to 22.5A, up to 30A or up to 45A
  • Fast brake torque control with microcontroller operated closed loop current control and fast discharge (demagnetization).
  • Thermal protection
  • Isolated input
  • Brake energy recovery to capacitor


Torque control demonstration:

Speed control demonstration:


Supply 100-415VAC
1-3 phase
Brake continuous current BD3-22.5A:
22.5A @ 40°C ambientBD3-30A:
30A @ 40°C ambientBD3-45A:
45A @ 25°C ambient
40A @ 40°C ambient
Brake discharge method Fast discharge with storage capacitor
Typical full charge time
(0 to full torque)
Less than 0.2s
Typical full discharge time
(full torque to 0)
Less than 0.02s
Switching frequency Adaptive, up to 4kHz
Brake current control Controlled with microcontroller in closed loop
Current target control Programmable current range
Galvanically isolated PWM input, 15Hz – 4kHz, 4V – 8V, higher input voltage allowed with external resistor
Galvanically isolated CAN bus interface, CAN-BUS 2.0B, 500kBit
Diagnostics CAN bus:
Brake current
Power stage temperature
Switching frequency

Additional information possible in future with firmware updates
Environment temperature range −20°C – 50°C
Power stage thermal protection threshold 90°C
Operating humidity 0%-95% without condensation
Dimensions 22.5A,30A:
14cm x 15.5cm x 12cm
26cm x 23.5cm x 11cm
Mass 22.5A,30A: 1.3kg
45A: 3.3kg

Capacitor dimensions:

  • 250uF: ⌀85×134,5mm
  • 600uF: ⌀116x130mm
  • 1200uF: ⌀116x230mm
  • 1420uF: ⌀136x284mm

Capacitor cables in the picture are for illustration purpose and are not included.

Full specification and instruction manual

BD series brake power supplies comparison

Additional information


22.5A, 30A, 45A


250uF, 600uF, 1200uF+NTC25, 1200uF+NTC35, 1420uF+NTC35