MindMap Gallery Chapter 4 Inverter Circuit emmx Mind Map
This is an article about the emmx mind map of Chapter 4 Inverter Circuit, current-type inverter circuit, voltage-type inverter circuit, commutation method, etc.
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Inverter circuit
Commutation method
Basic working principle of inverter circuit
When switches S1 and S4 are closed and S2 and S3 are open, the load voltage u0 is positive; when switches S2 and S3 are closed and S1 and S4 are open, the load voltage u0 is negative;
Changing the switching frequency of the two sets of switches can change the frequency of the output alternating current.
Classification
Grid commutation
The commutation voltage is provided by the grid
Load commutation
The load provides commutation voltage
Whenever the phase of the load current leads the load voltage, load commutation can be achieved.
External commutation
Device commutation
Utilizing the self-shutoff capability of fully controlled devices for commutation
forced commutation
Set up an additional commutation circuit to apply reverse voltage or reverse current to the thyristor to be turned off.
self-commutating
Device commutation is only suitable for fully controlled devices, and the other three methods are mainly for thyristors.
Voltage type inverter circuit
The DC side is a voltage source
Single-phase voltage inverter circuit
Half bridge inverter circuit
0~t1: Midpoint—R—L—VD1—
t1~t2: —V1—L—R—midpoint
t2~t3:- —VD2—L—R—midpoint
t3~t4: Midpoint—R—L—V2— -
The output voltage is a rectangular wave; amplitude Um=Ud/2
Full bridge inverter circuit
There are four bridge arms in total, which can be regarded as a combination of two half-bridge circuits.
The two pairs of bridge arms conduct 180° alternately. The output voltage and current waveforms have the same shape as the half-bridge circuit but twice the amplitude.
Changing the effective value of the output AC voltage can only be achieved by changing the DC voltage U.
phase shift voltage regulation
For resistive-inductive loads, phase shifting can also be used to adjust the output voltage.
Fundamental amplitude
Fundamental effective value
The output voltage is a rectangular wave; amplitude Um=Ud
Inverter circuit with tap
Alternately drive two IGBTs, and add a rectangular wave alternating current to the load through transformer coupling. current voltage.
The function of the two diodes is also to provide feedback channels for reactive energy.
Comparison with full bridge circuit
Uses half less switching devices than a full-bridge circuit
The voltage the device can withstand is 2U, which is twice as high as the full-bridge circuit.
There must be a transformer
The output voltage is a rectangular wave; amplitude Um=Ud
Three-phase voltage inverter circuit
Basic working method
180° conductive mode; that is, each bridge arm conducts 180° The upper and lower arms of the same phase conduct electricity alternately, and the angle at which each phase begins to conduct electricity is 120 degrees different.
At any moment, there are three bridge arms conducting at the same time.
Longitudinal commutation
Each commutation is performed between the upper and lower arms of the same phase.
Output line voltage
Valid values
Fundamental amplitude
Fundamental effective value
Load phase voltage
Valid values
Fundamental amplitude
Fundamental effective value
Current type inverter circuit
The DC side is a current source
Single-phase current type inverter circuit
Fundamental current effective value
The relationship between the load voltage effective value Uo and the DC voltage Ud
Self-motivation mode
In the actual working process, the parameters of the induction coil change with time, and the operating frequency must be automatically adjusted to adapt to the changes in the load. This control method
Other incentives
Fixed operating frequency control method
Three-phase current type inverter circuit
The relationship between the fundamental wave effective value Iu1 and the DC current Id
waveform
subtopic
application
Used for small power inverter power supplies below a few kW. Both single-phase full-bridge and three-phase bridge can be regarded as a combination of several half-bridge inverter circuits.
shortcoming
The output AC voltage amplitude is U/2, and two capacitors need to be connected in series on the DC side to control the voltage balance between the two. Large empty volume
advantage
The circuit is simple, uses fewer components, and has low cost.