Different Types of Inverters | Sine Wave Inverter & Square Wave Inverter

What is an Inverter?

  • In our modern world, electricity plays a crucial function in our everyday activities, including the industrial use of electricity to perform activities.
  • Inverters supply continuous 220 V AC energy to any device attached to its outlet socket. It ensures an uninterrupted AC supply to its output socket even when the AC mains power supply isn’t available.
  • Many variables influence our choice of the ideal Inverter to use in our project.

Block Diagram for an Inverter:

  • The Power inverter device converts electrical energy from DC shape to AC form using electronic circuits. Its most popular use is to convert the battery voltage to standard household AC voltage for use in types of equipment when an AC power source is not available.
  • Two ways to get the lower voltage DC power is integrated into AC Power.
  • The first method is the conversion of lower voltage DC power into a high voltage DC source, then converting that high DC source into an AC waveform by using Pulse width modulation.
  • The second method will be to change the DC power voltage into AC, which is then used as an amplifier to increase it to 220 voltages.
  • The most popular method used for the present residential Inverter can be described as the 2nd.
  • An Inverter not only converts the battery’s DC Voltage to AC signals of 220V V but also charges the battery in the event AC mains power is available.
Block diagram of DC-AC inverter.
  • The block diagram shown above is an essential representation of how An Inverter Works.

If you are using the AC mains power supply

  • If the Utility Company’s AC mains power supply is in place.
  • The AC sensor detects C Main Sensor, and the 230V A.C feeds it to the battery charger and relay.
  • A relay activates the relay or Change Over Switch AC primary sensor. This relay will be able to directly connect through the power of the 230V AC Mains power source to the load.
  • Battery Charger: The Battery Charger converts the line A.C Voltage into DC Voltage and charges the battery even when A.C power is available.
  • Battery: The battery is charged and shut down when filled.

If it is determined that the AC primary power source isn’t available.

  • If it is, the AC Mains Power Supply is not in operation.
  • Relay or Change Over switch: AC principal sensor will activate a relay. This relay will be connected to batteries without an AC mains power supply.
  • Battery: Battery provides DC Power to the Oscillator circuit via relay.
  • Oscillator Circuit: A oscillator circuit in the Inverter uses a pulse width modulator to produce the frequency of 50Hz required for generating AC from the Inverter.
  • The DC power supply for the battery connects to an oscillator. The flip-flop converts the inbound signal into signals that change the polarity, such as in the case of a two-signal that changes direction.
  • The first signal is positive, the second is negative, and the reverse is true. The process repeats 50 times per second, resulting in an alternate signal of 50Hz frequency. The name also knows the alternating signal of “MOS Drive Signal “.
  • Driver Circuit: MOS drive signals are sent to the driver’s base transistor, split into two distinct channels.
  • Amplifier Circuit These transistors amplify the MOS 50Hz driving signal they receive at the base to a suitable amount and output them to the emitter.
  • An Inverter Transformer used to create this Inverter is a centre-tapping that divides into two equally sized sections.
  • This centre-tapping connects directly to the battery’s positive side. The two ends are linked to the opposing end of the battery using switches S1 and S2.
  • MOSFETs, also known as Transistors, are utilized to switch the operation. They are MOSFETs, and Transistors connect to the primary windings of an inverter transformer.
  • When these devices receive a MOS signal for a drive from the circuit, they begin switching between ON and Off states at a frequency of 50Hz. The switching process of MOSFETs or Transistors produces a 50Hz current to the primary inverter transformer. 
  • This creates a voltage of two-volt AC and 2300V AC (depending on the winding ratio of the inverter transformer) at the secondary or that of the transformer inverter. The secondary voltage is available through the outlet socket on the Inverter via the switchover relay.

Types of Inverter

Inverters are classified according to their output.

  • Sine wave Inverter
  • Modified sine wave inverter
  • Square wave Inverter.

(1) Sine Wave Inverter:

  • In the utility company, sine waves generated by the rotating AC equipment and sine wave are the natural result of spinning AC machines.
  • Pure sine wave converters produce the same output as the sine wave, which is comparable to grid power that utility supply; thus, the Pure Sine Wave inverter has a more efficient and clean current.
  • Every commercial instrument is designed to run on a pure sine wave. Specific characteristics of these instruments depend significantly on the shape of the input waves. Any change in the form of the wave can affect the efficiency and performance of the device.
  • Sine Wave assures that the Sine method of Inverter is entirely pure and the equipment will function to its full specifications according to the design. Appliances like refrigerators, motors, Ovens etc., will generate the total power from a pure sine wave signal.
  • Some appliances, like Toaster or light dimmers, as well as some battery chargers, need a sine wave to operate propeller-like. Operating these appliances using Square or stepped waves can significantly impact the lifespan of the equipment because of the creation of heat.
  • A distortion in the sine wave can cause the sound of humming in transformers and audio devices.
  • We have discovered that audio amplifiers, televisions, fluorescent lamps and so on create noises when using inverter power. This suggests that the output of an inverter does not come from a pure sine wave.
  • Choosing an inverter with a pure sine wave is highly advised to ensure your appliance’s safety and efficient performance.
2: Principal of Pulse Width Modulation

Advantages of Sine Wave Inverter:

  • The output voltage waveform can be described as pure sine waves with extremely low harmonic distortion and pure power, similar to utility-supplied electricity.
  • Inductive loads such as microwave ovens and motors operate faster, quieter, and more excellent.
  • Sine Wave Inverters Reduces electrical and audible noise in fluorescent lighting, fans, Audio amplifiers, Game consoles, TVs, and answering machines.
  • These inverters reduce your monthly bill compared to inverters that use square waves.
  • It Helps prevent computer crashes and printers, strange printouts, as well as noise, glitches, and glitches on monitors.
  • The time to back up will be much longer than inverters that use square waves.

Disadvantages of Sine Wave Inverter:

  • Sine wave inverters can be two to three times costlier than square waves and modified sine inverters.

Application of Sine Wave Inverter :

  • More sensitive electronic or electrical products
  • Desktop computers, laptops, Laser printers, photocopiers,
  • Battery chargers for cameras Cell phone chargers
  • Mixer,
  • LED bulbs with electronic ballasts,
  • Digital clocks,
  • Sewing machines equipped with microprocessors and speed control
  • Medical equipment,
  • Small-sized household drive motors for water pumps, etc.

(2) Modified Sine Wave Inverter

  • An inverter modified by a sine wave is a form of one of the square waves but with an additional step.
  • Modified sine waves are a model of the sine wave’s pure output when the Inverter dramatically decreases or increases the voltage to change polarity. This results in the output is very similar to a pure sine wave. However, it suffers from much higher distortions.
  • Modified sine wave converters can work with all equipment, but the efficiency or power may be decreased with particular.
  • The devices are generally around 70% effective, meaning we should expect to experience significant power loss if you use an altered sine wave Inverter inside your system.
  • Motors like refrigerators, pump fans, etc., will draw more energy from the Inverter due to lower efficiency. Most engines require around 20% more power.
  • Certain fluorescent lamps won’t perform as well. Some may even be noisy or buzzing noises.
  • Since the modified sine waves are louder and rougher than the pure sine wave, clocks and timers can perform faster or no function. Additionally, portions of the wave do not have 50 Hz. This can make clocks operate more quickly. Things like lighting dimmers or breadmakers might not function in many instances, and appliances which use electronic temperature controls won’t regulate. Something like variable speed drills is usually limited to two speeds, on and off.
  • The price significantly differs between Sine Wave and Modified Sine wave inverters. A sine wave is considerably more costly. It is possible to find a practical way to use it. We can put in a tiny Pure Sine Wave inverter for any “special requirements” and a bigger Modified Sine Wave Inverter to suit all our other applications.

Advantages of Modified Sine Wave Inverter:

  • More affordable than sine wave pure inverters
  • Output correction waveform; relatively stable; suitable for ordinary individuals with a lamp, TV, fans, computer, hot pot, etc.
  • Output waveforms have an extremely low harmonic distortion compared to the Square Inverter for Waves.

Disadvantages of Modified Sine Wave Inverter:

  • Lower efficiency than inverters that use pure sine waves.
  • Power Loss is a lot more compared with the sine wave.
  • Modified Sine Wave outputs are not suitable for continuous operation of some appliances equipped with electromagnetic and capacitive devices like refrigerators, microwave ovens, microwave and many types of motors, printers, fluorescent capacitive lighting, etc.
  • When an altered sine wave inverter powers, fans with synchronous motors can slightly increase their speed (RPM). It isn’t detrimental to the fan or the Inverter.
  • Certain rechargers designed for nickel-cadmium batteries may be damaged if they are plugged into an inverter modified to convert sine waves.

Applications Of Modified Sine Wave Inverter :

  • A few household appliances and power tools.
  • Inductive loads, such as motors and micro ovens.
  • Lights and fans,
  • Televisions, audio amplifiers, games consoles, fax machines and answering devices.

(3) Square Wave Inverter:

  • The output waveform of an Inverter is similar to a square.
  • It’s old-fashioned and one of the lowest-priced inverters, yet it is the most difficult to operate.
  • Inverters with square waves can operate simple tools with universal motors without an issue, but they will not do much other than that.
  • The current we receive from the grid isn’t a pure sine wave but close to a sine wave. Also, electronic devices, like fans and tube lights, emit noise when operating in a square wave. Inverters for square waves have reduced the speed at which we control dimmers for ceiling fans.
  • As a square wave, the load voltage has to be switched extensively in a high to lower voltage polarity without the need for an intermediate voltage of 0 Volt.
  • The most important reason behind this problem is the excessive voltage. The typical voltage output of square wave inverters ranges between 230-290 volts which is why it’s not recommended for electronic devices such as computers.
  • They change the voltage between plus and minus, creating a square waveform. They’re inefficient as the square wave contains plenty of power and higher harmonics that all appliances cannot utilize. Synchronous motors, for instance, operate the 50Hz component and convert the remaining frequencies into heat.
  • Inverters of square waves aren’t often observed anymore.

Advantages of Square Wave Inverter:

  • It’s extremely affordable

Disadvantages of Square Wave Inverter:

  • The life of the application is less.
  • The control of speed for some equipment isn’t possible.
  • The voltage variation is very high.
  • Massive 3rd harmonic and 5th harmonic parts consume power and drastically reduce the effectiveness of devices.

Application Square Wave Inverter:

  • Cost-effective AC motor drives
  • A ballast with an electronic circuit for fluorescent lamps.