What are drives?

A machine is used to control the movement of electrical equipment. This system is called a drive. In other words, a drive that uses an electric motor is called an electric drive. Electric drives use any prime mover, such as diesel or gasoline engines, fuel or steam turbines, steam engines, hydraulic cars, and electric cars as the main energy source. This prime mover supplies the mechanical energy to the pressure for motion control.

Types of drives

Different types of variable speed drives are used in the industry. The kinds of drives consider are mechanical, hydraulic, and electric/electronic (eddy-current coupling, rotating DC, DC motor converters, and variable-frequency AC).

Mechanical variable speed drives

Mechanical variable speed drives were probably the first type of drive to enter an industrial area. The mechanical drive still finds its source of AC power — usually a three-phase AC. The three-phase AC is then supplied with an AC engine with constant speed. The ability to change the width of one or both pulleys gives this driving unit the ability to change its output speed. The variable speed system is the same as 15-speed bicycle gears. Switching gears cause the chain to slide into a sprocket with a wide or narrow width. When that happens, a faster or slower speed is achieved with the same input power.

Figure shows a basic mechanical variable speed drive.  the mechanical drive operates on the principle of variable-pitch pulleys.
Mechanical drives

Hydraulic drive

Hydraulic drives lead position in many metal processing and production applications. The small size of the hydraulic motor makes it ideal for situations where high power is required in the densest areas. The size of the hydraulic motor is 1/4-1/3 of the size of the same electric car. The pump generates the required working pressure inside the system to enable the hydraulic motor to increase its rated power. Speed control comes from the control valve. This valve works like a water pump; when the valve is wide open, too much fluid passes through the device and the speed of the hydraulic motor increases. Observe that this electric machine uses a coupler to connect the AC motor to the pump.

The figure indicates a hydraulic drive. A constant-speed AC motor operates a hydraulic pump.
Hydraulic drive

Eddy current drives

The eddy current drive originates in the heavy machinery part of the industry. Grinding wheels are the prime candidates for eddy-current drivers. This system uses the DC-to-DC power conversion process, allowing the shaft speed to vary depending on the power converter. The function of the DC motor is to convert alternating current into direct current. This power is then fed to the coupling field. The coupling field generates a magnetic object based on the DC power generated by the DC motor. The greater the energy generated, the greater the magnetic field generated, and the stronger the attractive force of the coupling element to the input drum. The DC motor's power is determined by using the speed reference potentiometer (speed potentiometer).

The image indicates a simple eddy-current drive system. An AC motor operates at a fixed speed.
Eddy current drive

Rotating DC drives

The system dates back to the mid-1940s. The machine also got the name M-G set, which stands for motor-generator set. A constant-motor AC motor causes a DC generator to generate a direct current. The amount of energy produced in the form of a generator depends on the magnetic field-oriented of the wild exciter of the generator. The shape of the governor determines the excitation voltage. As shown later, the DC motor needs circuits to work properly. In this example, a DC generator supplies power to a large DC motor car circuit (known as an armature). A DC motor car also needs another cycle known as a stadium. Field magnetism interacts with magnetism within an important circuit (armature) to produce a motor shaft rotation. The magnetic field of a field depends on the amount of energy produced by the motor field exciter. The sphere exciter power is determined by the shape of the DC motor speed pot.

Advantages of drives

  • The electric drive has a very large range of torque, speed, and power.
  • Their overall performance depends on the environment.
  • The electric drive is free of contaminants.
  • electric drives work on all field-quadrants of high-speed torque aircraft.
  • The drive may be started without difficulty and does no longer need to be refilled.
  • The efficiency of the drive is high because there's little loss in it.

Uses of drives

It is used in a large number of industrial and household applications, such as transportation systems, factories, paper machines, textile engines, machinery, fans, pumps, robots, and washing machines. A variable frequency drive helps to control the speed of the motor. Not only does it control the speed but it also helps ensure the best performance of the compatible engine installed. It provides cost as well as energy efficiency. Ensuring better safety of motor and maintenance.

Common mistakes

The drive is that sometimes the machine power generated by the main conductor is first converted into electrical power and then the machine work with the help of the engine. This can be done with the help of an electric connector connected to the prime mover and the load.

Context and Applications

In each of the expert exams for undergraduate and graduate publications, this topic is huge and is mainly used for:

  • Bachelor of technology in the electrical and electronic department
  • Bachelor of Science in physics
  • Master of Science in physics
  • Electrical power transmission
  • Electrical power distribution

Practice Problems

Q1. Which of the following is used to build an electric drive?

a) Source

b) Motor

c) Control unit

d) All of the mentioned

Correct option: (d)

Explanation: Power supplies, power modules, motors, loads, sensor devices, control units, and installation commands can all be used to build electric drives.

Q2. What is the unit of apparent or complex power?

a) VA

b) ohm

c) Volt

d) VAR

Correct option: (d)

Explanation: The apparent power in the AC circuit is VI. It is expressed in volt-amperes (VA). It contains both active and active energy. It is a vector of real power and active force.

Q3. Type-A chopper is used for obtaining which type of mode?

a) Reverse motoring mode

b) Motoring mode

c) Reverse regenerative braking mode

d) Regenerative braking mode

Correct option: (b)

Explanation: Only driving mode is available in the case of a stair chopper (Type-A chopper). In the case of a step-down chopper, the output voltage is less than the input voltage.

Q4. The frame of an induction motor is made of _________.

a) silicon steel

b) aluminum

c) stainless steel

d) cast iron

Correct option: (d)

Explanation: The frame of the induction motor is made of stainless steel. The power factor of an induction motor depends on the air gap between the stator and the rotor.

Q5. Which of the following core has linear characteristics?

a) CRGO core

b) Iron core

c) Air core

d) Steel core

Correct option: (c)

Explanation: The air-conditioning coil has a specific magnetic property that does not degrade. In the case of a synchronous machine, the graph of the open circuit indicator is a line.

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