1 Overview

Hardware Concept

The hardware for the multi-motor control demonstration is modularized. It consists of one control board and several driver boards. The control board and the driver boards must be connected together.

The control board contains an MCU and regulating circuits for feedback signals. It may also contain HALL and quadrature encoder interfaces, over-current detection circuits, user-defined buttons, LEDs, potentiometers, and some communication interfaces.

Each driver board contains a three-phase half bridge (inverter) and its driver circuits, and provide current/BEMF feedback signals.

A control board is dedicated to a particular MCU, while a driver board is independent from any MCU. One control board supports at least two driver boards. Each driver board is designed to control one motor.

Taking the PIC32MKMCM control board as an example, the concept of the hardware is illustrated in the following figure. The PIC32MKMCM control board is shown in orange, and the driver board is shown in green.

Figure 1-1. Hardware Concept

Each driver board has an input interface to receive a (main) power supply and an output interface to transmit the power supply. Therefore, each driver board can receive its power supply separately, or several driver boards can share one power supply by being connected into a loop. The topologies of the separate power supply and the shared power supply are shown in the following figures:

Figure 1-2. Separate Power Supply
Note: The negative inputs of power supplies 1, 2, and 3 would be shorted on the control board.
Figure 1-3. Shared Power Supply
Important: All the GNDs for the power supplies are shorted on the control board. Therefore, all power supplies should share the same GND even if the driver boards receive power supplies separately.

A DC/DC converter is on the control board to transform the DC bus voltage to DC 12V. The input DC bus voltage of the DC/DC is obtained from one driver board. Such a driver board, which provides its DC bus voltage to the DC/DC, is called as the mandatory driver board. To power the control circuits, the mandatory driver board must be connected to the control board.

Main Features of the Driver Board

The following are key features of the Driver Board:

  • Separate power supply or shared power supply
  • Power supply voltage: DC 24V ~ 48V
  • Rated phase current: 30A (peak value) and 15A (RMS)
  • Three phase current feedbacks and DC bus current feedbacks
  • Three phase back EMF feedbacks
Figure 1-4. The Driver Board

Main Features of the PIC32MK MCM Control Board

The following are key features of the PIC32MK MCH Control Board:

  • Supports up to three driver boards
  • One quadrature encoder interface, one HALL interface, and one over-current detection circuit for each motor
  • Three user-defined buttons, three user-defined LEDs, three user-defined potentiometers
  • One reset button
  • Two-shunts current sampling or single-shunt current sampling
  • Up to two UART interfaces; one SPI interface; one CAN interface
Figure 1-5. PIC32MK MCM Control Board
Figure 1-6. PIC32MK MCM Multi-Motor Control Platform with One Driver Board
Figure 1-7. PIC32MK MCM Multi-Motor Control Platform with Two Driver Boards
Figure 1-8. PIC32 MK MCM Multi-Motor Control Platform with Three Driver Boards