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OwnVerter Board Datasheet v1.1.0

Overview

The OwnVerter Board is a reprogrammable, 1.3kW three-phase power converter designed primarily for motor control applications. It can interface with Sin-Cos encoders, optical speed sensors, and Hall effect sensors, providing precise feedback control.

The OwnVerter Board is fully open-source, compatible with either the SPIN board or other programming systems. It supports communication via CAN-bus or RS-485.

At a Glance

  • Rated Power: 1.3kW
  • Number of Low-Side Channels:
    • Three Low side
    • Single High side
  • Current ratings:
    • Selectable 20Apk or 50Apk per channel
  • Voltage Ratings:
    • 12V to 100V high-side

Special Features

  • 3-phase design
  • Triple, Dual or Single power channel configuration
  • Up to 97% efficiency
  • Standard size: 100mm x 160mm x 35mm
  • Wide voltage operating range
  • Motor control optimized
  • CAN-bus and RS-485 communication compatible
  • Fully open-source
  • BLDC and FOC examples and control library available
  • Github source files

Connectivity

Hall Effect or incremental Encoders

This interface is galvanically isolated from the microcontroller.
Matching connector is JST EHR 5.
Color code of the provided cable is

  • +5V Red
  • H1/A Yellow
  • H2/B Brown
  • H3/Z Green
  • GND Black

Max current delivered by the board internal feeder through the +5V/GND is XXXmA

Encoder interface
Figure 1: Encoder interface

SIN/COS Encoders

This interface is not galvanically isolated from the microcontroller.
Matching connector is JST EHR 4.
Color code of the provided cable is

  • +5V Red
  • SIN Green
  • COS Yellow
  • GND Black

Max current delivered by the board internal feeder through the +5V/GND is XXXmA
SIN and COS signal should range from 0v to 2.048V.

Encoder sin/cos interface
Figure 2: Encoder sin/cos interface

Max current selection

Max current sensed can be selected through solder jumpers.
Solder jumpers are marked SJ on the PCB.

  • If the solder jumps are bridged, max current is +/- 50 Amps
  • If the solder jumps are not bridged, max current is +/- 20 Amps

20/50A current selector
Figure 3: 20/50A current selector

External voltage measurements

User can select if voltage measurement is taken at the switching node or externally after a custom filter.

External measurement selector

External measurement are cabled through a dedicated connector labeled L1 Ext, L2 Ext, L3 Ext
These cables are meant to be tied after a custom filter.

  • Min sensed voltage is 0V.
  • Max sensed voltage is 100V.

Matching connector is JST EHR 3.
Color code of the provided cable is

  • L1 Ext Yellow
  • L2 Ext Brown
  • L3 Ext Green

External voltage measurements connector
Figure 4: External voltage measurements connector

Fuses

Two fuses ratings are provided with the Ownverter board.

  • 15A fuses are meant to be equipped when max current is +/- 20 Amps
  • 30A fuses are meant to be equipped when max current is +/- 50 Amps

Fuse series is Littelfuse MINI 997

Fuse holders
Figure 5: Fuse holders

RJ45 connectors

Recommended cables are S / FTP RJ45 cables.
S / FTP means that the shielding is double:

  • Overall copper braid shielding
  • and shielding on each pair.

Unlike the RJ45 F/FTP computer cable, the S/FTP cable has a drain conductor. This allows any interference to be moved to ground, reducing potential interferences.

RJ45 Terminals
Figure 6: RJ45 Terminals

Termination resistors

Headers marked CAN and RS485 are 120 Ohm termination resistance jumpers.
They should be set for first and last modules when power modules are daisy chained.

Termination resistors jumpers
Figure 7: Termination resistors jumpers

External heatsink

Power dissipation can be mounted on the bottom side on the board.
Pads should be covered by an electrically isolating thermal interface material.
Advised method is to use thermal interface double side duct tape.
Mounting holes can be used to fasten any heatsink in place. Refer to the mechanical drawing for drill map.

Heatsink pads
Figure 8: Heatsink pads

Converter Pinout

The OWNVERTER converter pinout is shown in the image below.

Twist board pinout overview
Figure 9: Twist board pinout overview

Converter pins

Power Pins

  • Vhigh is the high side voltage
  • A+/B+/C+ are the low side voltages. They are connected to the motor phases.
  • GND is the power GND
  • Feeder 6V is the 6V output of the embedded feeder
  • D6V is the input of the digital 6V. You can feed it from an outside source.
  • DGND is the digital ground

Data Pins

  • CAN1 and CAN2 the two pins of the CANBus
  • RS485 +/- the two pins of the RS485 bus.
  • Analog +/- the two pins of the analog bus.
  • Sync I/0 the pin through which boards synchronize. It is the same pin for both master and slave operation.
  • DGND is the digital ground

Electrical Specifications

Absolute Maximum Ratings

Absolute Maximum Ratings

Parameter Min Typ Max Unit
Low-Side peak Voltage - - 92 VDC
Low-Side RMS Voltage - - 65 VDC
High-Side Voltage 8 - 100 VDC
Low-Side Peak Current per Channel - - 20 A
Low-Side RMS Current per Channel - - 14.14 A
Power Output - - 1.3 kW

Low-Side Ratings

Parameter Min Typ Max Unit
Number of Power Channels - - 3 -
Voltage Range 12 - 92 VDC
(Max Low-Side Peak Current per Channel) - - 20 A

High-Side Ratings

Parameter Min Typ Max Unit
Number of Power Channels - - 1 -
Voltage Range 12 - 100 VDC

Switching Characteristics

Parameter Min Typ Max Unit
Switching Frequency - 200 - kHz
Selectable Deadtime (20kΩ resistor) - 200 - ns
Maximum Gate Current - 4 - A

Temperature and Dimensions

Parameter Min Typ Max Unit
Operating Temperature -20 - +60 °C
Cooling Principle - Natural Convection - -
Dimensions (L x W x H) 100 x 100 x 35 - - mm

Protection Features

Parameter Min Typ Max Unit
High-Side Fuse (Tamb = 25°C) - 25 - A
Low-Side Fuse (Tamb = 25°C) - 25 - A

Communication Specifications

CAN-FD

Type Parameter Min Typ Max Unit
CAN-FD Baudrate 500 500 - kBauds
Halh Duplex RS485 Baudrate 10 20 - MBauds
SPI Baudrate 0.5 - 20 MBauds
USART Baudrate - 115200 - Bauds

Synchronization

Two OWNVERTER Boards can be synchronized via PWM sinc IN/OUT. Using a 15cm RJ45 cable, the delay and jitter between the server and the client PWM are measured as follows:

Parameter Symbol Min Typ Max Unit
PWM Slew Rate - 660 - - mV/ns
Delay Between Server and Client td - 24.2 - ns
Jitter of PWM Client tj - 4.8 - ns

Synchronization experiment results
Figure 10: Synchronization experiment results

Analog Communication

Analog communication between boards allows voltage and current measurement with high accuracy.

Example Measurement: - A 16-bit value of 2000 is transmitted by a server board. - Step response from 1V to 1.25V measured with a 500 MHz oscilloscope.

Parameter Symbol Min Typ Max Unit
Step Response Time to ±5% Δt5% - 1.7 - µs
Steady-State Value Vfinal - 1.25 - V
±5% Steady-State Interval ΔV - 0.125 - V
Bandwidth \(\(fc = \dfrac{3}{2\cdot \pi \cdot \Delta t_{5\%}}\)\) - 281 - kHz

Measurement resolution results
Figure 11: Measurement resolution results

Statistical Distribution of 10235 data samples

Parameter Symbol Min Typ Max Unit
Mean \(\mu\) - 2032.65 -
Variance \(\sigma^2\) 0.795 -

Measurement resolution results
Figure 12: Measurement resolution results

Measurement Chains

The Twist Board implements full observability on all low-side and high-side power channels using isolated measurements.

ADC Specifications

Parameter Value
ADC Technology Successive Approximation (SAR)
Independent ADC Peripherals 5
Number of Channels per ADC 1 to 6
Sampling Time 530 ns
Hardware ADC Trigger Programmable trigger instant on PWM period
Number of PWM synchronized ADCs 2
Software ADC Trigger All ADC peripherals
Trigger Event Typical Frequency 200 kHz

Measurement Points

Measurement Description Sensor Technology Bandwidth (kHz) Signal Side Amplitude Full Scale Range Unit
VILow1 Phase A Low-side voltage Voltage divider & isolation amplifier 60 ±250 mV ±80 V
iILow1 Phase A Low-side current Isolated Hall effect sensor 1000 ±20 A ±20 A
VILow2 Phase B Low-side voltage Voltage divider & isolation amplifier 60 ±250 mV ±80 V
iILow2 Phase B Low-side current Isolated Hall effect sensor 1000 ±20 A ±20 A
VILow2 Phase C Low-side voltage Voltage divider & isolation amplifier 60 ±250 mV ±80 V
iILow2 Phase C Low-side current Isolated Hall effect sensor 1000 ±20 A ±20 A
VIHigh High-side voltage Voltage divider & isolation amplifier 100 +2 V 120 V
iIHigh High-side current Isolated Hall effect sensor 1000 ±20 A ±20 A
Temp1 LEG1 Temperature NTC Thermistor -40 to +110 \(\degree C\)
Temp2 LEG2 Temperature NTC Thermistor -40 to +110 \(\degree C\)
Temp3 LEG2 Temperature NTC Thermistor -40 to +110 \(\degree C\)

Schematic showing where the measurements are performed on the circuit.

Schematic with measurement instruments
Figure 13: Schematic with measurement instruments

Measurements location and convention

  • Voltage sensors - they measure phase voltage of the motor.
  • Low-side Current sensors - they measure phase current of the motor. Their output is positive when the inverter is in Source mode (current going OUT of the low side).
  • High-side Current sensor - it is connected right after the high-side connector. Its output is negative when the converter is in BUCK mode (current going IN the high side).

Image showing where the measurements can be accessed on the board.

Board with measurement points
Figure 14: Board with measurement points

Measurement pins

All measurements have pins which can be easily accessed with a probe (oscilloscope or multimeter) as shown below.

Use ground springs for noise reduction

Board with measurement points
Figure 15: Board with measurement points

Standard Deviation of Measurements

Parameter Not Averaged Avg of 2 Measures Avg of 3 Measures Avg of 5 Measures Avg of 10 Measures
VILow1 85 mV 61 mV 50 mV 39 mV 28 mV
VILow2 82 mV 58 mV 47 mV 37 mV 27 mV
VILow2 82 mV 58 mV 47 mV 37 mV 27 mV
VIHigh 150 mV 108 mV 88 mV 68 mV 48 mV
IILow1 34 mA 24 mA 20 mA 16 mA 11 mA
IILow2 34 mA 24 mA 20 mA 15 mA 11 mA
IILow2 34 mA 24 mA 20 mA 15 mA 11 mA
IIHigh 14 mA 10 mA 8 mA 6 mA 4 mA

Relative accuracy of voltage and current measurements

The following graphs give the accuracy of the voltage and current measurements for different levels of current and voltage for the TWIST board for reference only. Measurements for the OWNVERTER board are ongoing.

Accurary graphs
Figure 16: Accurary graphs

Theoretical Calibration Parameters

By default all OWNVERTER boards can be calibrated using the following parameters.

Variable Name Gain Offset Unit
VLow1 0.05134 -97.868 V
VLow2 0.05134 -97.868 V
VLow3 0.05134 -97.868 V
VHigh 0.029964 0 V
ILow1 0.01 -20 A
ILow2 0.01 -20 A
ILow3 0.01 -20 A
IHigh 0.01 20 A

Typical Applications

Mode Name High Side Low Side Sensor type Typical Application
3 phase inverter Input Output HAL BLDC Motor

Example wiring diagram and schematic of the Twist board in Buck mode

TWIST converter in Buck Mode
Figure 17: TWIST converter in Buck Mode

Revision History

Date Revision Changes
07-Fev-2025 1 Initial Release

License: Documentation licensed under Creative Commons SA-BY