Automotive Education

This video is an overview of the new 1-PWM Mode for the DRV8305 Brushless DC Motor Driver

This section presents the different ways of architecting the dc-dc stage for automotive frond end. Two stage approaches such as pre-boost + buck, buck + post-boost, as well as single stage approach using a buck-boost converter are presented. The advantages and limitation of these approaches are compared.

Brushless DC motors were developed from conventional brushed DC motors with the availability of solid state power semiconductors. So, why do we discuss brushless DC motors in a chapter on AC motors? Brushless DC motors are similar to AC synchronous motors. The major difference is that synchronous motors develop a sinusoidal back EMF, as compared to a rectangular, or trapezoidal, back EMF for brushless DC motors. Both have stator created

At first it may seem pointless to have the four buffer gates following the shift register output lines, since the power transistors should be able to drive adequate current to the stepper motor windings without any help. However, the buffers are not in place for the benefit of the transistors, but rather for the benefit of the shift register. If the buffers were not there, and the shift register had

Electromechanical watt-hour meters use an aluminum disk that is spun by an electric motor. To generate a constant “drag” on the disk necessary to limit its rotational speed, a strong magnet is placed in such a way that its lines of magnetic flux pass perpendicularly through the disk’s thickness: The disk itself need not be made of a ferromagnetic material in order for the magnet to create a “drag”

The interlock contacts installed in the previous section’s motor control circuit work fine, but the motor will run only as long as each push button switch is held down. If we wanted to keep the motor running even after the operator takes his or her hand off the control switch(es), we could change the circuit in a couple of different ways: we could replace the push button switches

Perhaps the most challenging aspect of interpreting ladder diagrams, for people more familiar with electronic schematic diagrams, is how electromechanical relays are represented. Compare these two equivalent diagrams: First, the ladder diagram: Next, the schematic diagram: Based on your observations of these two diagrams, explain how electromechanical relays are represented differently between ladder and schematic diagrams.

Shaded pole induction motor An easy way to provide starting torque to a single phase motor is to embed a shorted turn in each pole at 30o to 60o to the main winding. (Figure below) Typically 1/3 of the pole is enclosed by a bare copper strap. These shading coils produce a time lagging damped flux spaced 30o to 60o from the main field. This lagging flux with the undamped main

PARTS AND MATERIALS Automotive alternator (one required, but two recommended) Old alternators may be obtained for low prices at automobile wrecking yards. Many yards have alternators already removed from the automobile, for your convenience. I do not recommend paying full price for a new alternator, as used units cost far less money and function just as well for the purposes of this experiment. I highly recommend using a Delco-Remy brand

Don’t just sit there! Build something!! Learning to analyze digital circuits requires much study and practice. Typically, students practice by working through lots of sample problems and checking their answers against those provided by the textbook or the instructor. While this is good, there is a much better way. You will learn much more by actually building and analyzing real circuits, letting your test equipment provide the “answers” instead

How is it possible to electrically measure the torque output by a permanent-magnet DC motor? Hint: it is very simple, and for large electric motors it involves the use of a shunt resistor. Modify this circuit diagram to include a meter that provides indirect indication of motor torque:

Perhaps the most important benefit of polyphase AC power over single-phase is the design and operation of AC motors. As we studied in the first chapter of this book, some types of AC motors are virtually identical in construction to their alternator (generator) counterparts, consisting of stationary wire windings and a rotating magnet assembly. (Other AC motor designs are not quite this simple, but we will leave those details to

The armature windings of your DC motor will have very low resistance. Too low, in fact, to accurately measure with an ohmmeter connected directly to the commutator terminals, because the contact resistance between the meter probes and terminals will be a large percentage of the resistance read by the meter. One way to avoid this contact resistance problem and measure very low resistances using normal meters is to employ what

A wound rotor induction motor has a stator like the squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes. However, no power is applied to the slip rings. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting. (Figure below) This resistance is shorted out once the motor is started to make the rotor

A three phase motor may be run from a single phase power source. (Figure below) However, it will not self-start. It may be hand started in either direction, coming up to speed in a few seconds. It will only develop 2/3 of the 3-φ power rating because one winding is not used. 3-φmotor runs from 1-φ power, but does not start. The single coil of a single phase induction motor

Normally, the rotor windings of a wound rotor induction motor are shorted out after starting. During starting, resistance may be placed in series with the rotor windings to limit starting current. If these windings are connected to a common starting resistance, the two rotors will remain synchronized during starting. (Figure below) This is useful for printing presses and draw bridges, where two motors need to be synchronized during starting. Once

If the ends of a wire loop are attached to two half-circular metal strips, arranged so that the two strips almost form a complete circle, and those strips are contacted by two “brushes” which connect to opposite poles of a battery, which way will the wire loop rotate?

PARTS AND MATERIALS AC power source: 120VAC Capacitor, 3.3 µF 120VAC or 350VDC, non-polarized #33 AWG magnet wire, 2 pounds wooden board approx. 6 to 12 in. square. AC line cord with plug 5.1-inch dia. plastic 3-liter soda bottle discarded ballpoint pen misc. small wood blocks CROSS-REFERENCES Lessons In Electric Circuits, Volume 2, chapter 13: “AC motors”, “Single Phase induction motors”,“Permanent split-capacitor motor”. LEARNING OBJECTIVES To build a large exhibit size AC permanent split-capacitor induction motor.

Most AC motors are induction motors. Induction motors are favored due to their ruggedness and simplicity. In fact, 90% of industrial motors are induction motors. Nikola Tesla conceived the basic principals of the polyphase induction motor in 1883, and had a half horsepower (400 watt) model by 1888. Tesla sold the manufacturing rights to George Westinghouse for $65,000. Most large ( > 1 hp or 1 kW) industrial motors are poly-phase induction motors. By poly-phase, we mean that

The variable reluctance motor is based on the principle that an unrestrained piece of iron will move to complete a magnetic flux path with minimum reluctance, the magnetic analog of electrical resistance. (Figure below) Synchronous reluctance If the rotating field of a large synchronous motor with salient poles is de-energized, it will still develop 10 or 15% of synchronous torque. This is due to variable reluctance throughout a rotor revolution. There is

A stepper motor is a “digital” version of the electric motor. The rotor moves in discrete steps as commanded, rather than rotating continuously like a conventional motor. When stopped but energized, a stepper (short for stepper motor) holds its load steady with a holding torque. Wide spread acceptance of the stepper motor within the last two decades was driven by the ascendancy of digital electronics. Modern solid state driver electronics

PARTS AND MATERIALS AC power source: 120VAC Capacitor, 3.3 µF (or 2.2 µF) 120VAC or 350VDC, non-polarized 15 to 25 watt incandescent lamp or 820Ω 25 watt resistors #32 AWG magnet wire wooden board approx. 5 in. square. AC line cord with plug 1.75 inch dia. cardboard tubing (toilet paper roll) lamp socket AC power source: 220VAC Capacitor, 1.5 µF 240VAC or 680VDC, non-polarized 25 to 40 watt incandescent lamp or 820Ω 25 watt resistors #32 AWG magnet wire wooden board approx. 15 cm. square. AC