AC to DC Converters are one of the most important in power electronics because there are lot of real applications are based on this conversions. The AC current to dc current conversion process is known as rectification. This rectifier converts AC supply into the DC supply at load end connection. Normally Transformers are used to adjust the AC source to get step down transformer to reduce the voltage level to have better operation range for DC supply. Normally this AC to DC converter converts low voltage values.
In most of the countries, the electrical power generation and transmission are purely based on alternating current. Different types of electrical power stations use alternators (Synchronous generators) to generate electricity. Most of the electrical appliance which we use in our home for our day to day activities use alternating current. Examples like the water heater, fans, vacuum cleaner.. etc. There are several applications which use dc current for their operation such as Television, computers, mobiles..etc. There are several different dc voltage levels apply according to applications.
Uncontrolled AC to DC Converters
Uncontrolled converter converts fixed DC voltage, it means the value of output for a given value of AC voltage. Fully controlled converter convert adjustable DC voltage when the adjustable range can adjust in both positive and negative side. Semi-controlled converter also produce an adjustable DC voltage which positive side power.
All three converter have unidirectional power flow on AC side to DC side. PWN converter can produce adjustable both positive importantly it allows power flow in either direction. Making it ideal application motor drives and power system interconnection with the power system.
All three converter have unidirectional power flow on AC side to DC side. PWN converter can produce adjustable both positive importantly it allows power flow in either direction. Making it ideal application motor drives and power system interconnection with the power system.
In here we are first going to explain more about the uncontrolled rectifiers. Uncontrolled rectifiers can also subdivide into several subcategories such as
- Single phase half wave rectifier
- Single phase full wave bridge rectifier
- Single phase center tapped full wave rectifier
- Three phase half wave diode rectifier
1.Single Phase Half wave Controlled Rectifier
Single phase half wave rectifier is simplest controlled rectifier which uses for single devices. To produce variable dc voltage from fixed current thyristors are use. Following are the circuit arrangement of Single phase half wave rectifier.
In here diode or thyristors are used. Where the application needs fix d.c. Voltage, the diode is used as switching element. When the application need variable voltage thyristors are used.
Single phase converters can mainly classify as Bridge Converter and Center Tapped Converter. This type of uncontrolled converters is mainly used for building supply only in Patrice. In power supply by applying a capacitor filter on the output in other cases which inductive load causes we use this directly or inductive filters.
2.Single phase full wave bridge rectifier
In the above half wave controlled rectifier is only used to transfer the positive half cycle only. In full wave bridge rectifier, the entire positive and negative half cycle can transfer.
There are so many different types of configurations are use to create this full bridge rectifiers and following are one type of full wave bridge rectifier.
Factors got affected with Supply Current (Is)
In any uncontrolled converters, there are several important parameters to consider with respect to the current brought from LC source. Those parameters are indicated in following.
- Supply Current (Is) Total RMS Value
- Input displacement angle
- Displacement factor
- Supply Current (Is) fundamental RMS Value
- Supply Current (Is) Harmonics
- Total Harmonic distortion
- Distortion factor
- Power Factor (P.F)
- Order of Harmonics
3.Single phase center tapped full wave rectifier
DC Power Supply, built with a center tapped rectifier with capacitor filter and regulator. Assuming regulator input current to be approximately same as I0
4.Three phase half wave diode rectifier
Diode D1, D2, D3 Take the positive rectangular block of current where Io is constant. The current are transformer secondary current and the net dc component of the same act to curve a DC magnetization of the transformer core.
This is decremental because the transformer input current can then be heavily distorted due to excessive distorted and peachy measuring current. Therefore this arrangement of conversion is not suitable and not use in practice.
However, if we are using a half bridge converter the direct term 3 phase supply (ie. without a transformer) the resulting DC current on the AC side, which is only small value for the upside distribution transformer there may not be the serious issue.
If we insist one a half bridge converter with it own transformer we must go to DZ transformer (Delta Zero) then the problem can solve. Most of three-phase AC to DC converters are much popular for industrial applications. These converters are used widely for power generation from DC side.
If we insist one a half bridge converter with it own transformer we must go to DZ transformer (Delta Zero) then the problem can solve. Most of three-phase AC to DC converters are much popular for industrial applications. These converters are used widely for power generation from DC side.
