Question 1

Why is the inverter not controlling?

Accepted Answer

The first task is to review the settings of the inverter motor and power source. Let's set these for the current application. 
The motor position sensor must be calibrated using an automatic calibration function.
The software contains many protection functions so that all limiting factors can be monitored. These values can be seen by clicking on the LMIMTS tab within the graphic interface. As long as we see a limiting factor, the system limits performance.

Most common errors:
-Motor Temp Limit: If the motor temperature sensor is not connected.
-DRV error: When the low voltage system of the inverter has a weak or insufficient power supply.
-ABS over current: If the position sensor is not calibrated.
-Under voltage: High voltage power supply is weak or the voltage is configured incorrectly

Question 2

Why does it oscillate during operation?

Accepted Answer

You may need to adjust the current regulator settings to get maximum performance. Also, if the wrong motor parameters are specified, this may be the cause of the oscillation.
If the motor parameters are good, it is possible to set the controller in the "PI Current Control" menu. Only who have experience in setting up such a controller should change the parameters!
It is necessary to achieve that the "FOC iq" meets the "FOC iq target" as close as possible. Trial and error is the fastest way to achieve results. Try to double the "I" and "P" values per attempt for this purpose. It is not realistic to use more than 10 time biger values for the current motor. After each attempt, try to make bug steps in the "iq target".

Question 3

How can I use two inverters for one motor?

Accepted Answer

With the DTI system, it is possible to put two inverters on one motor and increase torque and power. This option is only available for special double winding motors. The motor has one position sensor, but an encoder splitter is needed to divide the signal between the two inverters. The electric schematic does not change.

Question 4

What motors is compatible with the inverter?

Accepted Answer

Our inverters are currently compatible with all Permament Marnet Surface Mount synchronous motors. Compatibility with Internal Magnet is also under development, but it is not currently available.
You will find the parameters of all EMRAX motors as predefined parameters. 
If you use a motor from another manufacturer, the following parameters must be entered on the graphical interface:
-Motor resistance
-Motor inductance
-KV (RPM/Voltage)
-Poles (EMRAX 10 pole pairs means 20 poles)

Question 5

What liquid can I use for liquid-cooled inverters?

Accepted Answer

Glycol – Distillate water mixture that we recommend. The cooling system must include a radiator, water pump and an expansion tank. As an electric water pump, we recommend one of the Pierburg pumps. CWA150 for one or two inverter drives. CWA400 for larger system. 
Choose a medium compatible with the aluminum system.
Connect the water cooling of the individual units in parallel in order to take advantage of the high water flow capacity of the pumps.

Question 6

Is there a possibility for sensorless control?

Accepted Answer

In the current phase, there is no development and there are no plans for it. This would not be beneficial for the majority of customers, so this feature has a very low priority.

Question 7

Can HALL effect sensor position detection be used?

Accepted Answer

Yes, it can be used. Thanks to a special algorithm, we minimized the pulsation of the motor torque caused by the HALL sensor position detection. So it can be used almost problem-free. 
It must be taken into account that this is a much more imprecise detection method than encoder detection. Because of this, a performance reduction of roughly 80% must be expected.

Question 8

As the first step of implementation, I would use the inverter on a labor table. Can I use it without cooling system?

Accepted Answer

The inverter protects itself from overheating. No need to worry about the inverter destroying itself. With the default settings, it can be used safely in the initial phase of development. However, sustained high temperatures reduce the lifetime, so as soon as the inverter receives a load, it is recommended to build a cooling system.

Question 9

Does the inverter comply with the FSAE safety regulations?

Accepted Answer

The rules change from year to year and we try to respond to the new rule changes with our developments.
At the moment, yes, it complies with the regulations.
The inverter supports the connection and processing of the double redundant analog accelerator pedal according to the regulations.
It has the HVIL interlock system, which is mandatory when using the quick connectors.

Question 10

What control modes does the inverter support?

Accepted Answer

At the moment, there are 3 main control modes supported by the inverter. 
-AC current control corresponding to torque control
-Motor speed control mode, which is close to to AC voltage control.
-Position holding. This is mainly used for gliders and VTOLs to minimize air resistance.

Question 11

What is needed to be able to put two inverters on one motor?

Accepted Answer

The DTi system is capable of synchronously operating two inverters even on one motor. Double current / torque is achieved with this solution.
The motor must be a special double winding or insulated two winding. The position encoder signal must be split in two with an encoder splitter unit so that both inverters can process the signal. In addition, everything must be done as if there were two independent systems.

Question 12

Can two motors be controlled with one inverter?

Accepted Answer

This cannot be solved. The two independent motors require two independent inverters.

FAQ