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DC Machines

Voltage Source Inverters (VSI) Operation | VSI Working Principle

The voltage source inverter is a somewhat older design and less expensive to implement. Various implementations of the VSI are also known as six-step, twelve-step, or even eighteen-step inverters. Voltage Source Inverters Operation  In the VSI, the switches are turned on and off at regular intervals to deliver rectangular pulses …

Variable-Frequency Drive Working Principle | Variable-Speed Induction Motor Drive

The induction motor is basically a constant-speed motor, as it operates within 3% of the synchronous speed, which is determined by the frequency and number of poles in the machine: $\begin{matrix} {{n}_{s}}=\frac{120\times f}{P} & {} & \left( 1 \right) \\\end{matrix}$ Although torque at a given slip is proportional to the …

Pulse Width Modulated Inverter | PWM Inverter

The Pulse Width Modulated (PWM) inverter offers the ability to change both the magnitude of the voltage and the frequency using a fixed DC voltage as the input. This means a diode rectifier can be used as the front end of the drive, which appears as a constant power factor load …

Current Source Inverter Operation

Both the VVI and PWM are voltage-source inverters; i.e., they provide a voltage to the motor similar to what it would normally receive from the power system, except at variable frequency. Current Source Inverter Working A current- source inverter, on the other hand, acts as a constant current source to …

Brushless DC Motor Working

A DC machine actually has an AC current in the armature that is rectified by the commutator and brushes. Brushes eventually wear out, requiring maintenance, and they produce carbon dust and possibly arcing while operating. Nevertheless, the characteristics of DC machines are often desirable. With the advances in power electronics, …

DC Machine Construction and Operation

Figure 1 shows elementary permanent- magnet machine. It is very similar to the AC machine; however, instead of a pair of slip rings to connect to the ends of the coil, there is a single split ring. Each end of the coil is connected to one-half of the ring, and …