Projects by Mattias

I began prototyping the VFD circuit discussed in the previous post, specifically the inverter stage. I modified it to be a single-phase full bridge inverter instead of the three-phase simulated. This is due to me using a single-phase shaded pole induction motor for testing down the line - 120 V, 60 Hz on the nameplate. Here is an image of the circuit: Full-bridge inverter circuited Before making the circuit, I simulated the inverter in LTSpice. Similar to the PSIM simulation, a bipolar switching scheme is being generated for the SPWM signal. Inverter legs and gate driver ICs Bipolar PWM generation and output filter For the spice simulation, LTC7061 half-bridge MOSFET drivers are being used. In the actual circuit I sourced IR2104 gate drivers however they both do the same thing so I opted to use the default Analog Devices IC in LTSpice.  Picking Bootstrap Capacitors The gate driver ICs require a bootstrap capacitor and diode. For the diode I picked a standard 1N4148/1N4007. However, to

I began a new project to design and construct a Variable Frequency Drive (VFD) for AC induction motors. The purpose of this project is for me to apply some of my power electronics knowledge of inverter design and also aid me in my FOC project since the power stage of this drive is similar (FOC just has more complex control algorithms). This post will cover some the high level design considerations and some preliminary simulation of the VFD. Background - Induction Motors To me motor drives are super interesting as AC motors are used everywhere and they are the basis of many machines. More specifically, AC induction motors (invented by Nikola Tesla) are the most popular motor kind - 90% of motors used in industrial and commercial applications are induction type.  To see how a VFD works it is important to know how an induction motor works. At a high level, the induction motor, like many AC motors, is made up of a stator and a rotor. The stator is made up of windings - for a three-phase mo