Power Education

TI is unleashing the power of silicon carbide with a new, verified reference design that provides an overview on how to implement a three-level, three-phase SiC based DC:AC grid-tie inverter stage. In this video you will learn the advantages of a three-level topology; what TI technology is driving the SiC MOSFETs;  how and where are we sensing V & I; what is behind the digital power controller; and what efficiency and power density levels you can achieve with this design. Tune in as TI discusses this innovative technology at the Applied Power Electronics Conference.

PARTS AND MATERIALS Low-voltage AC power supply (6-volt output) Two 1N4001 rectifying diodes (Radio Shack catalog # 276-1101) Small “hobby” motor, permanent-magnet type (Radio Shack catalog # 273-223 or equivalent) Audio detector with headphones 0.1 µF capacitor One toggle switch, SPST (“Single-Pole, Single-Throw”) It is essential for this experiment that the low-voltage AC power supply is equipped with a center tap. A transformer with a non-tapped secondary winding simply will not work for

So far in our discussions on electricity and electric circuits, we have not discussed in any detail how batteries function. Rather, we have simply assumed that they produce constant voltage through some sort of mysterious process. Here, we will explore that process to some degree and cover some of the practical considerations involved with real batteries and their use in power systems. In the first chapter of this book, the

What is Rectification? Now we come to the most popular application of the diode: rectification. Simply defined, rectification is the conversion of alternating current (AC) to direct current (DC). This involves a device that only allows one-way flow of electric charge. As we have seen, this is exactly what a semiconductor diode does. The simplest kind of rectifier circuit is the half-wave rectifier. It only allows one half of an

PARTS AND MATERIALS Four 6-volt batteries 12-volt light bulb, 25 or 50 watt Lamp socket High-wattage 12-volt lamps may be purchased from recreational vehicle (RV) and boating supply stores. Common sizes are 25 watt and 50 watt. This lamp will be used as a “heavy” load for your batteries (heavy load = one that draws substantial current). A regular household (120 volt) lamp socket will work just fine for these low-voltage “RV” lamps. CROSS-REFERENCES Lessons In

Three-phase Wye(Y) Connection Initially, we explored the idea of three-phase power systems by connecting three voltage sources together in what is commonly known as the “Y” (or “star”) configuration. This configuration of voltage sources is characterized by a common connection point joining one side of each source. (Figure below) Three-phase “Y” connection has three voltage sources connected to a common point. If we draw a circuit showing each voltage

As was mentioned before, the angle of this “power triangle” graphically indicates the ratio between the amount of dissipated (or consumed) power and the amount of absorbed/returned power. It also happens to be the same angle as that of the circuit’s impedance in polar form. When expressed as a fraction, this ratio between true power and apparent power is called the power factor for this circuit. Because true

Power measurement in AC circuits can be quite a bit more complex than with DC circuits for the simple reason that phase shift complicates the matter beyond multiplying the voltage by current figures obtained with meters. What is needed is an instrument able to determine the product (multiplication) of instantaneous voltage and current. Fortunately, the common electrodynamometer movement with its stationary and moving coil does a fine job of this.

Explain the difference between a balanced polyphase system and an unbalanced polyphase system. What conditions typically cause a polyphase system to become unbalanced?

A calculator for computing several parameters needed in the design of a flyback switch mode regulator

Three-Phase Alternator Let’s take the three-phase alternator design laid out earlier and watch what happens as the magnet rotates. Three-phase alternator The phase angle shift of 120° is a function of the actual rotational angle shift of the three pairs of windings. If the magnet is rotating clockwise, winding 3 will generate its peak instantaneous voltage exactly 120° (of alternator shaft rotation) after winding 2, which will hit its peak 120° after winding 1. The

PARTS AND MATERIALS Calculator (or pencil and paper for doing arithmetic) 6 volt battery Two 1/4 watt resistors: 10 Ω and 330 Ω. Small thermometer The resistor values need not be exact, but within five percent of the figures specified (+/- 0.5 Ω for the 10 Ω resistor; +/- 16.5 Ω for the 330 Ω resistor). Color codes for 5% tolerance 10 Ω and 330 Ω resistors are as follows: Brown, Black, Black, Gold (10, +/- 5%), and Orange, Orange, Brown, Gold (330, +/- 5%). Do not use any battery size other than 6

A common phrase heard in reference to electrical safety goes something like this: “It’s not the voltage that kills, it’s current!” While there is an element of truth to this, there’s more to understand about shock hazard than this simple adage. If the voltage presented no danger, no one would ever print and display signs saying: DANGER—HIGH VOLTAGE! The principle that “current kills” is essentially correct.

What hazards might be posed by a circuit with excessive current going through its conductors (excessive as defined by the conductors’ ampacity)? In other words, what would be bad about a wire carrying too much current? Also determine which type of component fault, an open or a short, would most likely be the cause of excessive current in a circuit.

Current Source It is possible through the use of electronic amplifiers to design a circuit outputting a constant amount of current rather than a constant amount of voltage. This collection of components is collectively known as a current source, and its symbol looks like this: A current source generates as much or as little voltage as needed across its leads to produce a constant amount of current through it. This

Explain how the microphone in your amplifier works. How, exactly, does it convert waves of air pressure (sound) into electrical signals?

When calculating the power dissipation of resistive components, use any one of the three power equations to derive the answer from values of voltage, current, and/or resistance pertaining to each component: This is easily managed by adding another row to our familiar table of voltages, currents, and resistances: Power for any particular table column can be found by the appropriate Ohm’s Law equation (appropriate based on what figures

The peak voltage calculator calculates peak voltage values from the peak-to-peak voltage, RMS voltage, or average voltage.

Every meter impacts the circuit it is measuring to some extent, just as any tire-pressure gauge changes the measured tire pressure slightly as some air is let out to operate the gauge. While some impact is inevitable, it can be minimized through good meter design. Voltage Divider Circuit Since voltmeters are always connected in parallel with the component or components under test, any current through the voltmeter will contribute to

In many circuit applications, we encounter components connected together in one of two ways to form a three-terminal network: the “Delta,” or Δ (also known as the “Pi,” or π) configuration, and the “Y” (also known as the “T”) configuration. It is possible to calculate the proper values of resistors necessary to form one kind of network (Δ or Y) that behaves identically to the other kind, as analyzed from the terminal connections

If an electric current is passed through this wire, which direction will the wire be pushed (by the interaction of the magnetic fields)? Is this an example of an electric motor or an electric generator?