VFD Updates - More Prototyping and PCB Design
Several things have been done since the initial prototype: the prototype has been further tested, the motor has been validated, and the PCB has been designed and sent to the FAB. Here is an image of the rendered board: The PCB render Prototype Validation The prototype has been changed - specifically gate and pull-down resistors were added. A big change is that the inverter generates a 12 V peak to peak signal which is then boosted up to 120 V RMS by a transformer and powers the motor. This was done instead of having a 120 V sine wave be generated as an isolated power supply would be needed for the logic components, however the current being drawn at the inverter stage is significantly higher. Here are some key waveforms generated by the inverter. The switching voltage between inverter legs A and B The filtered output voltage The firmware is running a 100% modulation index, thus showing that the output wave has peaks of $\pm V_{dc}$ or $\pm 12 V$. The frequency can also be modulated to ...