# Questions tagged [vfd]

Variable frequency drive, a three-phase AC output motor controller. Questions about vacuum fluorescent displays should not receive this tag.

9 questions
Filter by
Sorted by
Tagged with
2k views

### Condition for max torque

My questions are these: If say a 3ph motor connected to a mains supply is rated at 1400 rpm with no load at what rpm approximately does it produce its max torque? If the same motor is run with a VFD ...
1k views

### Can I ground the negative DC bus of a variable frequency drive?

Suppose I have a typical VFD: rectifier, DC bus caps, inverter, feeding a motor. In general it would not be advisable to tie the DC bus to earth ground, because the AC line may also be referenced to ...
11k views

### Tesla Car “maximum torque at 0 RPM” - is this correct?

Tesla Model S Wiki I've been watching youtube videos on this car, and everyone states that the crazy accelleration is due to maximum torque at 0 rpm. Doing further research, this car uses an AC ...
14k views

### What is the relation between the stator current and motor rpm for an AC motor?

A 3 phase AC motor is rated values are: 970 rpm, 50Hz, 380V delta 47A. A VFD drives this motor for obtaining a constant wind-speed which rpm is proportional. The thing is when 885 rpm the stator ...
833 views

### Why this pair of IGBT's died silently?

Before some days I have taken a look at circuit which controls AC current's frequency. That circuit was a VFD which looks like: simulate this circuit – Schematic created using CircuitLab But ...
422 views

### Can I drive a three phase induction motor with this method?

I have an idea to drive induction motors in a new way. I call it Variable Torque Drive (VTD). You are all familiar with VFD which utilize variable frequency and try to keep the torque constant. This ...
802 views

### From PWM Output to Large Motor Control

This question stems from my own curiosity, so forgive any vagueness. Imagine the following scenario: We have a MCU which outputs a PWM signal to control a motor's speed and direction. We ultimately ...