What is a power electronic system?

Introduction

Power electronic systems are often overlooked in the field of electrical engineering, yet they are essential for operating and regulating the devices we rely on every day. These systems are vital for improving the efficiency, dependability, and eco-friendliness of modern technological progress. This blog examines the details of power electronic systems, including their uses, development, and influence on various industries.

Understanding Power Electronic Systems

Power electronic systems are devices and circuits that use semiconductor-based switches to regulate electrical power. These switches manage the flow of electrical energy, allowing for the conversion of voltage levels, frequencies, and forms. The versatility of power electronic systems comes from their efficient power management capabilities, which make them suitable for various applications, from household appliances to industrial equipment.

Block diagram of the generalized power electronics system is shown in Fig 1.Power source may be an ac supply system or a dc supply system. In India,1-phase and 3-phase 50 Hz ac supplies are readily available in most locations.

Very low power drives (systems employed for motion control are called drives) are generally fed from 1-phase source. Rest of the drives are powered from 3-phase source. Low and medium power motors (tens of kilowatts) are generally fed from 400 V supply; for high ratings, motors may be rated at 3.3 kV, 6.6 kV,11 kV and higher. In case of aircraft and space applications, 400 Hz ac supply is generally used to achieve high power to weight ratio for motors. In main line traction, a high voltage supply is preferred because of economy. In India, 25 kV,50 Hz supply is employed.

Some loads are powered from a battery, e.g. fork lift trucks and milk vans.Depending on size, battery voltage may have typical values of 6 V, 12 V, 24 V,48 V and 110 V dc. Solar powered drives which are used in space and water pumping applications are fed from a low voltage dc supply. Presently, though these drives are very expensive but have a great future for rural water pumping and low power transport applications.

Figure 1: Block diagram of power electronic system

Power modulator performs one or more of the following four functions.

Converts electrical energy of the source as per the requirement of the load.For example if the load is a dc motor the modulator output must be adjustable direct voltage.In case the load is a 3-phase induction motor the modulator may have adjustable voltage and frequency at its output terminals.When power modulator performs this function it is known as converter.
Selects the mode of operation of the motor, i.e. motoring or braking.
Modulates flow of power from the source to the motor in such a manner that motor is imparted speed-torque characteristics required by the load.
During transient operations, such as starting, braking and speed reversal,it restricts source and motor currents within permissible values; excessive current drawn from source may overload it or may cause a voltage dip.

Motors commonly used in power electronic systems are:

DC motors (shunt, series, compound and permanent magnet)
Induction motors (squirrel-cage, wound rotor and linear)
Synchronous motors (wound field and permanent magnet)
Brushless dc motors
Stepper motors
Switched reluctance motors

Power modulators are controlled by a control unit. Nature of the control unit for a particular system depends on the power modulator that is used. Control unit operates at much lower voltage and power levels. Sensing unit measures the load parameters, say speed in case of a rotating machine and compares it with the command. The difference of the two parameters processed by the control unit components now controls the turn-on of power semiconductor devices which are used in power modulators. As desired, the behavior of the load circuit can be controlled over a wide range with the adjustment of the command.

Advantages of power electronic system

1.Energy Efficiency

Modern power electronics systems have proven their ability to provide mass power conversion with higher efficiency as compared to conventional systems. This is altogether crucially important in systems like renewable energy generation and electric vehicles.

2.Flexible Control

Power electronics systems enable for better power conversion process control over power quality, therefore leading to most efficient systems in various power electric applications.

3.Compact Size

Power electronic components are usually more compact and less cumbersome than their mechanical counterparts, and thus contribute to an overall reduced physical volume of the system.

4.High Reliability

Power electronic equipment competent with well-designed reliability and robustness may survive longer time span and have reduced necessity for maintenance.

5.Fast Response

Power electronics offer fast response times which would allow rapid shifting power and corrections in power output if and when necessary because a dynamic process needs such adjustments.

6.Integration with Digital Systems

These types of electronic systems can be easily integrated with digital control systems, bringing such benefits as remote monitoring, diagnostics, and automation.

7.Reduced Environmental Impact

Efficiency of energy improving and waste reduction, which enable a more sustainable world fit for people.

8.Cost Savings

In the long term, embedded power electronic systems not only provide savings of energy consumption, maintenance, and downtime, which tend to make this solution economically attractive.

Conclusion

Power electronic systems play a crucial role in advancing our energy landscape and increasing the use of electronic devices, as technology progresses. Their influence is growing as they shape a future focused on efficient and sustainable energy utilization.