Veronte MC25KW

This document describes the main functionalities of the MC25KW Speed Controller.

_images/isometric.png

MC25KW Main view

Veronte MC25KW speed controller is capable of driving any type of 3-phase PMSM motor. It can be used with a wide variety of UAVs such as eVTOL vehicles and also in automotive applications (Bikes, Karts, Cars).The MC25KW uses FOC algorithm for engine control together with IGBT (Insulated Gate Bipolar Transistor) technology.

MC25KW Speed Controller offers IP68 protection, allowing the operation under rain and extrem humidity environments.

MC25KW Speed Controller working voltage range is 75-550V with a maximum continuous current of 200A (up to 100kW).

The system has a temperature range of -40 to 65ºC. For higher temperature, a power limitation will be applied.

System Layout

Main Scheme

The speed controller is divided in two main items.

  • Capacitance board.

  • Controller System.

These items must be as close as possible. The maximum distance between both is indicated in the following image.

_images/assembly.png

Hardware Installation

When installing the MC25KW speed controller in the vehicle, the following limitation shall be considered:

  • The maximum distance between battery/power supply and the Capacitance Board is 0.5m

  • The maximum distance between the Controller System and the motor is 2m

  • The wire connections type between the power items must be crimped not soldered.

  • The system must be placed in a ventilated place with proper air flow. If this is not possible, it is necessary to install an external fan.

  • The vehicle must have an inrush current limiter when powering MC25KW for the first time.

Note

When working voltage is higher than 60V, use of insulating gloves is mandatory and the system must have a chassis fault detection system.

Warning

logo_alert Careful! The system does not discharge the voltage on the input terminals when the battery is disconnected. Capacitors remain charged.

MC25KW Capacitance Board

Description

This equipment integrates the capacitors needed to store enough energy for a proper performance.

Embention offers 3 different versions, dependent on the working voltage.

  • 200VDC

  • 400VDC

  • 550VDC

The selected battery voltage must be always lower than the nominal Capacitance Board voltage.

Mounting Instruction

The Capacitor Board has the following dimensions:

_images/capacitor_mounting.PNG

Operational Characteristics

Veronte eVTOL MC25K-C 200V.

Type

Specification

Allowable Voltage

0-200VDC

Reccommended Voltage

75 - 110VDC

Ripple Current (20Khz)

220Apk

Note

Motor phase inductance shall be higher than 5uH.

Veronte eVTOL MC25K-C 400V

Type

Specification

Allowable Voltage

0-400VDC

Reccommended Voltage

40 - 200VDC

Ripple Current (20Khz)

100Apk”

Note

Motor phase inductance shall be higher than 40uH.

Veronte eVTOL MC25K-C 550V

Type

Specification

Allowable Voltage

0-600VDC

Reccommended Voltage

400 - 550VDC

Ripple Current (20Khz)

60Apk

Note

Motor phase inductance shall be higher than 90uH.

Cable Mounting

The polarity and connection is indicated in the following image.

_images/capacitor_wiring.PNG

The section of the input cable must be 25mm2.

Warning

The polarity must be respected. Otherwise a short circuit will occur.

MC25KW Controller

Description

This section includes the driver and control systems. The block diagram of the system is shown below.

_images/system_diagram.png

Peripheral used for motor control:

  • Opto Isolated PWM

  • CAN bus

Peripheral use for ESC telemetry:

  • Serial RS-232

  • Serial RS-485

  • USB

Any of the serial interfaces can be used to configure the internal variables of the MC25KW.

The ESC includes an internal flash memory which is used to record operating logs. The variables to store can be selected through the corresponding interface.

Note

The selected configuration interface cannot be used to send telemetry.

Pinout

The communications connector pinout is shown in the following table:

_images/hew.png

Main Connector

Signal Connector

Pin

Signal

Type

Comment

1

HALL 1

Digital Input

2

HALL 2

Digital Input

3

HALL 3

Digital Input

4

OPTO+

Optocoupled Input (positive)

5

GND

Digital Ground

6

OPTO-

Optocoupled Input (return)

7

GND

Digital Ground

8

SYS ERROR

System status signal

High: OK, Low: NO OK

9

COS Signal

Cosine input signal

Sensored mode

10

SIN Signal

Sine input signal

Sensored mode

11

Analog 0

Multipurpose analog

12

Analog 1

Multipurpose analog

13

GND

Digital Ground

14

GND

Digital Ground

15

IN 485 +

RS-485 Communication

16

IN 485 -

RS-485 Communication

17

OUT 485 -

RS-485 Communication

18

OUT 485 +

RS-485 Communication

19

RS-232 TX

RS-232 Communication

20

RS-232 RX

RS-232 Communication

21

GND

Digital Ground

22

GND

Digital Ground

23

12V

No fuse protected 12V output

1A

24

5V

Fuse protected ouput

100mA

25

3.3V

Fuse protected output”

100mA

26

GND

Digital Ground

27

USB-

USB Communication

34

USB VBUS

USB Supply

35

USB +

USB Communication

36

USB GND,USB Ground

37

GND,Digital Ground

For AUX Input

38

GND,Digital Ground

For AUX Input

39

AUX INPUT

Digital supply,8-20V

40

AUX INPUT

Digital supply,8-20V

41

CAN GND

CAN Ground

42

CAN GND

CAN Ground

49

CAN B -

CAN Communications

50

CAN B +

CAN Communications

58

CAN A +

CAN Communications

59

CAN A -

CAN Communications

64

1.8V Out

Motor Thermistor

65

GND Out

Motor Thermistor

68

NTC Signal

Motor Thermistor

Max: 2V

Peripheral Specification

AUX Supply

This is the main power input for the secondary part of the driver. It must be powered with a voltage of 8 to 20V.

The consumption of this pin also depends on the loads connected to the 3.3V, 5V and 12V pins.

Status

Value

Standby

6.6W

Active

13.2

Note

No load on 3.3V ,5V and 12V outputs.

HALL Inputs

These inputs are used to add to the system a feedback in sensored mode (incremental type, usually magnetic).

PPM Inputs

This input is an optocoupled control digital signal.

The input is interpreted as 0-100% of the maximum RPM. An initial dead band can be configured to prevent the engine from starting.

Electrical Characteristics

Type

Specification

Input voltage range

0-5V

Minimum input current

2.5mA

Maximum frequency

250Hz

External Temperature Sensing

A PTC or NTC sensor can be integrated. The maximum voltage on this pin is 2V.

The PTC/NTC should be connected on the low side of an external resistor divider. This is the configuration by default. A high side connection can be used too, but a custom modification is needed.

The isolated 1.8V output should be floating in default mode. The isolated ground is the return path of the NTC/PTC sensor.

System output signal

This signal indicates if there is an error within the MC25KW. A positive voltage of 3.3V means that there is no problem.

Analog Inputs

These signals are non-isolated. Then, they shall not be in contact with the sensitive parts of the installation. The maximum voltage for these inputs is 3V.

The signals in pins 9 and 10 are those dedicated to the SIN / COS type analog sensor.

USB

This is the interface normally used to configure the MC25KW internal parameters.

The connection and disconnection of the USB related signals should always be done when the power supply (via the AUX_INPUT inputs) is on.

Note

Not recommended for sending telemetry by default.

RS-232

Single ended serial type protocol:

Electrical Characteristics

Type

Specification

ESD Protection

±15 kV (HBM)

Requirements

TIA/EIA-232-F and ITU v.28

Speed

Max. 250 kbit/s

Input Voltage

-25 to 25V

Output Voltage

-13.2 to 13.2V

RS-485

Differential serial type protocol:

Electrical Characteristics

Type

Specification

ESD Protection

±15 kV (HBM)

Requirements

TIA/EIA-485-A

Speed

Max. 25 Mbit/s

Input Voltage(D)

-0.5 to 7V

Output Voltage (D)

1.5 to 2.4V

CAN

Differential communication protocol:

Electrical Characteristics

Type

Specification

ESD Protection

±4 kV (HBM)

Requirements

ISO11898-2

Speed

Max. 5 Mbit/s

Input Voltage(D)

-12 to 12V

Output Voltage (D)

2.9 to 4.5V

Mounting Instruction

The MC25KW system has the following dimensions:

_images/assembly_mc25kW.PNG

Main Connector

Operational Characteristics

Electrical Characteristics

Type

Specification

Voltage

75-550VDC

Cont. Current

5 - 200A

Peak Current (<5s)

400A

Maximum speed (2 pole)

100000

Motor PWM Frequency

20Khz

Weigth

N/A

ESC-Motor Wiring

The polarity and connection is indicated in the following image.

_images/mc25kw_wiring.PNG

The section of the input cable must be 10mm2

Note

The connection of the phases can be done freely. However, it will affect the direction of rotation of the motor

Software Setup

To properly connect to a MC25KW unit you must previously install Veronte Link and MC25KW PDI Builder.

  1. Veronte Link: This tool is the HUB that manages all Veronte and Embention devices that use a COM port. Here the user can check, configure and list the devices that are currently connected.

  2. MC25KW PDI Builder: This tool is used to set all the configurable parameters. Here the user can set, tune and define the motor, control and sensors that are going to be used alongside the ESC.

MC25KW PDI Builder

After installing, MC25KW PDI Builder the main menu will show as follows:

_images/main.PNG
  1. MC25KW PDI Builder: Create a new PDI set of files to be saved and exported.

  2. Update MC25KW: Update motor controller firmware version to a later one. Ask Embention support (support@embention.com) for firmware updates, future features or suggestions.

  3. Upload PDI: Upload a previously created set of files to the current motor controller flash memory.

  4. Open MC25KW: Edit the current MC25KW settings.

At this point, the user can either create its own configuration offline by clicking on “MC25KW PDI Builder” or start editing the one that is already loaded to the controller by clicking on “Open MC25KW”. The same menu will pop up:

_images/openloop.PNG

Open Loop Ramp

This menu sets the start ramp before engaging the closed loop control. There basically three parameters:

  1. Speed fraction: Fraction of maximum speed (third field) to be reached before changing to closed loop.

  2. Startup Accelaration: angular ancceleration to reach maximum speed. In rad/s^2.

  3. Maximum Speed: Final speed to be reached before closing the control loop. In rad/s.

  4. Invert: Change spining direction of the rotor. This is the main way to invert the motor direction and will also affect the control and closed loop functionalities.

Motor

This tab sets all the physical parameters of the motor that will be used with Veronte MC25KW. These are:

_images/motor.PNG
  1. Stator internal resistance: This is the resistance that is usually specified in datasheets. Expressed in Ohms.

  2. Quadrature Inductance: Usually called “Lq”. Expressed in Henries (H).

  3. Direct Inductance: Usually called “Ld”. Expressed in Henries (H).

  4. Pole pairs: Number of poles divided by two. For instance, if your motor has 42 poles, you must input 21 here.

  5. Maximum RPMs: The maximmum RPMs the motor can reach in combination with your propeller. This parameter is only used to determine the equivalence between the maximum command (PWM or CAN) and the commanded RPM in speed closed loop mode.

  6. Startup Iq: The current used to start the motor.

  7. Maximum Iq: Maximum current the speed control loop can command to the quadrature current control loop. Please refer to FOC background section for further reference.

  8. Time to hold Max Iq: Maximum time to hold the previous value before going to off.

Warning

All the current are expressed in amperes/1000. So if in order to input 35 Apk, 0.035 must be typed.

FOC (Field Oriented Control) Background

In order to achieve better dynamic performance, a more complex control scheme needs to be applied, to control the PM motor. With the mathematical processing power offered by the microcontrollers, we can implement advanced control strategies, which use mathematical transformations in order to decouple the torque generation and the magnetization functions in PM motors. Such de-coupled torque and magnetization control is commonly called rotor flux oriented control, or simply Field Oriented Control (FOC).

The Field Orientated Control consists of controlling the stator currents represented by a vector. This control is based on projections which transform a three phase time and speed dependent system into a two co-ordinate (d and q co-ordinates) time invariant system. These projections lead to a structure similar to that of a DC machine control. Field orientated controlled machines need two constants as input references: the torque component (aligned with the q co-ordinate) and the flux component (aligned with d co-ordinate). As Field Orientated Control is simply based on projections the control structure handles instantaneous electrical quantities. This makes the control accurate in every working operation (steady state and transient) and independent of the limited bandwidth mathematical model.

A basic scheme for the FOC is represented as follows:

_images/foc_sch.PNG

As it can seen, there some key pieces in this algorithm:

  1. Park/Clark transform: These output a two co-ordinate time invariant system and a outputs a two co-ordinate time variant system respectively. As mentioned before, this is part of the process of getting two scalar values from a three phase time dependent system.

  2. PI Controllers: There are three of them: two to control quadrature current and direct curent (torque and flux) and one to control speed. This last one is placed as the one that controls Iq PI (cascade control) which means that in order to get more speed the system will command more torque (or Iq).

  3. Speed estimator: This block is able to estimate mechanical speed from current and voltage using the so-called “Sliding Mode Observer” algorithm.

The main dificulty of this control proposal is to tune these three PI controller although in most cases both current PI are exactly the same due to PMSM properties. In addition, there is an extra gain that needs to be tuned as part of the angular speed estimator algorithm.

This list las part is optional but highly recommended in case an external sensor is used such as a hall effect sensor or a SIN/COS sensor.

Sensorless RPM Observer/ Estimator

Once the basis of the FOC are covered, the rest of the features of this MC25KW can be explained. This tab covers the observer parameters, which in this case is only one. The observer that is implemented has an ON/OFF controller that gets the estimated electrical angle. This electrical angle is later derived to find the angular speed. As it can be seen, here only this gain must be selected:

_images/observer.PNG

After this gain is properly tuned, the electrical angle should look like this:

_images/eangle.png

Note

The algorithm includes an adaptive filter that automatically moves its cutoff frequency with the current mechanical angular speed, so the signal the user is monitoring is already filtered.

Warning

It is recommended to tune this estimator even if an external sensor is used for feedback (sensored control). As it will be described in the next section, the control will automatically jump in case the primary source of feedback fails to a sensorless control.

FOC Control

This is the main control menu, here all parameters regarding closed loop control are set. As mentioned before, the basic blocks that define the FOC control are three PI (Proportional, Integral controllers). First, both current PI are defined.

_images/foc_1.PNG _images/foc_currents.PNG

The form of the PI is the classical parallel form:

_images/pi.gif

Where integral gain refers to the quotient 1/Ti. Lower and upper saturation gain are the limits at which the PI limit its output. In this case, as it is illustrated in FOC background, these outputs are Vq and Vd.

Note

All limits quantities are normalized, which means that are values between 0 and 1.

Equally, the speed controller can be set here as shown below. In this example this PI controller is limited to be output 95 A.

_images/foc_speed.PNG

In addition, there is a rate limiter that could be used in case the slope needs to be limited with the input comand. Please note that is expressed in rad/s.

Control input allows the user to select the input source and several extra parameters such as:

  1. CAN Timeout: Whenever this timeout is met, the control input will be changed to the next option if available. If none of them is available, it will end up in failsafe mode.

  2. PPM Timeout: Same as before, but in this case the only option after this one is failsafe.

  3. Value for Fail Safe: Value between 0 and 1. It will be written in case none of the previous options is available.

_images/inputmgr.PNG

The input flow is the following in case the mode m_CAN_PPM is selected:

_images/input_flow.png

There some extra options than can be set under FOC control menu:

  1. Regenerative Braking: Activates regnerative braking feature which is basically consisting of thoughing some current back to battery whenever the motor is loosing speed (it uses the kinetic energy to charge de battery). This not recommended in case the power side is not connected to a battery.

  2. Input deadband: This is the value that defines when to start moving the motor. For example, it might be wanted to be different from zero in case an RC stick outputs around 0.1 of duty cycle by default.

Note

In case CAN Bus is used to command (see CAN I/O section), this deadband can be calculated as (desired deadband RPM)/(maximum RPM).

  1. Speed filter cutoff: Cutoff frequency (in Hz) that will be applied to filter Hall effect sensors and SIN/COS sensors only.

Finally, a state machine diagram is presented to clarify how the control and feeback sources work:

_images/control_flow.png

SIN/COS Sensor

In case an external SIN/COS sensor needs to be used as a source of feedback of electrical angle/velocity the main interface to do it is though ADC inputs. This menu allows the user to customize the main characteristics of its sensor:

  1. Min Voltage: Minimum voltage of the signal. Measured in Volts (V).

  2. Max Voltage: Maximum voltage of the signal. Measured in Volts (V).

  3. ADC factor: A factor multiplying what is read from the ADC port, specially useful if a voltage divider (or any other signal level adaptor) is installed.

  4. Sin ADC input channel: ADC channel at which the SIN signal is connected.

  5. Cos ADC input channel: ADC channel at which the SIN signal is connected.

  6. Invert: Inverts the resulting electrical angle. Useful to correct installation inversions.

_images/foc_sincos.PNG

I/O Setup

This panel is used to stablish the mapping of ports and the duties they are performing. The layout and principles of function of this feature are common in all Veronte products, a complete explanantion can be found here .

_images/io.PNG

CAN I/O

This a common part that is shared with Veronte Autopilot products, please refer to this page for further information.

_images/can_io.PNG

Altough, most of this menu could be familiar to veronte users, there is one new feature : CAN CMD. This is the input ESC expects to command the motor. By default, it uses the ID 1434 (standard) and the message structure is the following:

_images/can_io_cmd.PNG _images/canmsg.PNG

Warning

Note that what is represented as PWM1 is in fact sent as a value between 0 and 2500 as a result of the decoding factor. This last 24 bit value is in fact an RPM value.

SCI

The following fields can be configured:

  1. Baud rate: This field specifies how fast data is sent over a serial line.

  2. Length: This field defines the number of data bits in each character.

  3. Stop: Stop bits sent at the end of every character.

  4. Parity: is a method of detecting errors in transmission. When parity is used with a serial port, an extra data bit is sent with each data character, arranged so that the number of 1 bits in each character, including the parity bit, is always odd or always even.

_images/sci.PNG

CAN High Speed Telemetry

MC25KW is equipped with an special CAN telemetry, which is faster than the regular one. This is meant to monitor all variables that are RPM dependent and can be crucial to tune your ESC during initial stages. For instance, seeing electrical angle can be extremely difficult with a low samplig rate at high RPMs and as a consequence, tuning the observer gain can be tough. Likewise, monitoring the current that is measured in each phase can represent the same issue and make PI tuning really time-consuming.

_images/highcan.PNG

There are only two parameters here:

  1. Base ID: The first ID to be used. The next IDs will be reserved depending on the variable list.

  2. Decimation: The number of clock steps the ESC skips before sending a High Speed CAN telemetry packet.

Note

MC25KW is running at 10kHz.

Note

A separate tool is offered to see MC25KW telemetry, please ask support@embention.com