livello / phobia

Phobia Motor Controller

Phobia Motor Controller

PMC is an open project that aims to build the quality permanent magnet synchronous motor (PMSM) controller for use in a variety of scopes like RC or electrotransport.

There are several typical situations where PMC can be used.

• Light electric transport as scooter or bicycle. The use of current control is preferred. Start with discrete Hall sensors or use freewheeling. Control knobs are connected to analog inputs.
• Aerial propeller drive for RC drones. The use of speed control is preferred. Start with forced control or HFI. Control through CAN network or RC servo pulse.
• Servo drive and machine tools. Only servo control is applicable. The use of ABI incremental encoder is preferred. Control through CAN network or STEP/DIR pulse.

Of course you can make unusual configuration by combining the features of the PMC. Also is is possible to design custom features e.g. start-stop button control.

Software features

• Sensorless vector control of PMSM based on two inline current measurements.

• Fast and robust FLUX observer with gain scheduling.

• Two phase machine support (e.g. bipolar stepper).

• Self adjust of onboard measurements along symmetrical channels.

• Flux weakening control.

• Advanced command line interface (CLI) with autocompletion and history.

• Hardware abstraction layer (HAL) over STM32F4 and STM32F7.

• Flash storage for all of configurable parameters.

• Non time-critical tasks are managed by FreeRTOS.

• Least Squares estimate using library libLSE.

• Advanced PWM scheme provides:

  • Reduced switching losses (clamp to GND) and fully utilised DC link voltage.
  • Hopping to get accurate ADC measurements near PWM-edges.
  • Prevents bootstrap circuit undervoltage condition.
  • Optional reduced ripple mode (clamp to middle) for precise control.

• Terminal voltage measurements (TVM):

  • In operation it is used to reduce the effect of Dead-Time distortion.
  • BEMF tracking to get smooth start when motor is already running.
  • Self test of power stages integrity.
  • Self test of bootstrap retention time.

• Automated motor parameters identification with no additional tools:

  • Stator DC resistance (R).
  • Stator AC impedance in DQ frame (L1, L2, R).
  • Motor back EMF constant (E).
  • Moment of inertia (Ja).
  • Discrete Hall signals recognition.

• Advanced CAN networking:

  • Up to 30 nodes in peer network.
  • Network survey on request (no heartbeat messages).
  • Automated node address assignment.
  • Flash update across network.
  • IO forwarding to get CLI of remote node.
  • Flexible configurable data pipes.

• Operation at low or zero speed:

  • Forced control that applies a current vector without feedback to force rotor turn.
  • Freewheeling.
  • High frequency injection (HFI) based on magnetic saliency.
  • Discrete Hall sensors or ABI incremental encoder.

• Control loops:

  • Current control is always enabled.
  • Speed control loop.
  • Servo operation.
  • Boost loop (battery charger) (TODO).

• Adjustable limits:

  • Phase current with adjustable derate on PCB overheat.
  • Motor voltage applied from VSI.
  • Battery current (power) consumption and regeneration.
  • DC link overvoltage and undervoltage.
  • Maximal speed and acceleration.

• Control inputs:

  • CAN bus flexible configurable data pipes.
  • RC servo pulse width.
  • STEP/DIR interface (EXPERIMENTAL).
  • Analog input with brake signal.
  • Manual control through CLI.
  • Custom embedded application can implement any control strategy.

• Available information:

  • Total distance traveled.
  • Battery energy (Wh) and charge (Ah) consumed (reverted).
  • Fuel gauge percentage.

Hardware specification (REV5A)

• Dimension: 82mm x 55mm x 35mm.

• Weight: 40g (PCB) or about 400g (with wires and heatsink).

• Wires: 10 AWG.

• Connector: XT90-S and bullet 5.5mm.

• Battery voltage from 5v to 50v.

• Phase current up to 120A (with IPT007N06N, 60v, 0.75 mOhm).

• Light capacitor bank (4 x 4.7uF + 2 x 330uF).

• PWM frequency from 20 to 60 kHz.

• STM32F405RG microcontroller (Cortex-M4F at 168 MHz).

• Onboard sensors:

  • Two current shunts (0.5 mOhm) with amplifiers (AD8418) give a measuring range of 165A.
  • Battery voltage from 0 to 60v.
  • Three terminal voltages from 0 to 60v.
  • Temperature of PCB with NTC resistor.

• Motor interfaces:

  • Discrete Hall sensors or ABI incremental encoder (5v pull-up).
  • External NTC resistor (e.g. motor temperature sensing).

• Control interfaces:

  • CAN transceiver with optional termination resistor on PCB (5v).
  • USART to bootload and configure (3.3v).
  • Pulse input: RC servo, STEP/DIR, backup ABI (5v pull-up).
  • Two analog input channels (from 0 to 6v).

• Auxiliary interfaces:

  • Combined port: SPI, ADC, DAC, GPIO (3.3v).
  • BOOT pin combined with SWDIO to use embedded bootloader.
  • SWD to get hardware debug.
  • External FAN control (5v, 0.5A).

• Power conversion:

  • Battery voltage to 5v buck (up to 1A).
  • 5v to 12v boost (up to 100 mA).
  • 5v to 3.3v linear (up to 400 mA).

Look into phobia-pcb repository for PCB design source files. Also view photos of the assembled PCBs in doc/imgs/.

Current Status

Now we can declare that PMC is ready to use in most applications. But there are still some unresolved issues. It may be difficult to configure the PMC for a specific motor.

There are a few videos about PMC on youtube.

Read further in doc/GettingStarted.

TODO

• Make a detailed documentation.
• Consider to add SRUKF sensorless observer (for SRM).
• Introduce MTPA control.
• Add pulse output signal.
• Make a drawing of the heatsink case for rev5a.
• Design the new hardware for 120v battery voltage.
• Add text-based user interface (TUI).