LaunchXL F28379D V/F Control IM

Hello,

I am simulating a V/F control of induction motor with pwm pulses provided to 3 phase inverter module using ePWM modules in F28379D Launchpad. The simulation diagram is below :

After uploading the code, I have provided potentiometer value as input to ADC and controlled the voltage and frequency of load (for testing purposes I have used bulb loads).

The problems are listed as follows :

1. Less Voltage than required : Here when I provide standard sine pwm pulses at modulation index = 1, I get around 180 V for 300V DC link (when powered by arduino uno, I get around 240V RMS). I have configured the ePWM blocks for 4 kHz carrier frequency (up-down count) and 3 microseconds rising and falling edge deadbands.
2. Voltage Imbalance : When I set the potentiometer to a certain value, I get proper voltage and current waveforms as shown below (recorded from phase A).

But after sometime, the voltage gets imbalanced and the waveform becomes as shown below.

However when increasing the pot value, the problem vanishes but persists again after some time.

Note :

1. The sine waves do have biases to vary between 0 and 1.
2. When V/F control is operated for the induction motor, the motor slows down at some point of time and later stops (due to shoot-through).

Please let me know how the problems persist and the solution for them. In case you require additional information, ask me. Thank you.

Best regards,

Sai Mukul

[G. Sai Mukul]

Please provide your solutions to the earliest as I need to submit my project in one month and I have to execute my main project model if this model functions properly.

[Samar]

Hello @G. Sai Mukul,

Please attach the Simulink model (i.e. the .slx file). It would help me better understand the problem as I can go through the block parameters and other settings.

[G. Sai Mukul]

Hello @Samar,

Thank you for showing your interest. Here is the model requested.

[G. Sai Mukul]

@Samar Any updates ?

Answer 1

[KrishnaKumar]

Check your implementation of the v/f logic. You can refer to VbyF Controller - Implement V/F (open-loop or scalar) control for three-phase motors - Simulink for more information.

Shoot through with induction motor indicates either the PWM channels are not configured correctly or the given dead time might be insufficient. When using sinusoidal modulation, you can expect a max. output of 0.5Vdc (150V in this case) for a dc bus voltage of Vdc and the rms value of the same shall be lower than the above value.

It would be helpful to describe the inputs and outputs in the attached file for easier understanding and debugging.