How to calculate the LC of a high power three phase bridge rectifier circuit

This question is answered in detail in P110 of the book "Fundamentals of Modern Power Electronics Technology" by Zhang Li, a higher education press, and the waveform is very complex because it is three-phase, not DC.

Both the inductance and capacitance values are calculated using the principle of volt-second balance and ampere-second balance, which is the principle of all converters, and the capacitance is calculated by the slope relationship of the ripple current, and the inductance is calculated by the slope relationship of the ripple voltage.

DV=DI*T 8C DV is the ripple voltage, which is given by the design requirements.

di=(1-d)t2 t is 1 50 d is the duty cycle. This equation can be used to find the capacitance.

di=vg *d*t 2l vg is the input voltage, from which l di is also the ripple current provided.

The resistance depends on how much gain you need.

The figure shows a typical isolated three-phase bridge test rectifier.

This formula is too old-fashioned, you may not understand it, I suggest you go to the next book, it is easy to figure it out.

All converter parameters are calculated based on the principle of ampere-second balance of the capacitor and volt-second balance of the inductor!

1: The output voltage waveform is pulsating DC.

2: l is a flat wave reactor, l =, this circuit should be a DC motor drive circuit. where:

L: reactor inductance, E: transformer pay-side voltage.

i: Minimum load current.

ld: the amount of armature inductance of the motor.

3: Because the drawings are not clear, the resistor capacitor is selected as appropriate, and its function is resistance and capacitance absorption.

The waveform is close to DC where the standard is not high.

Can be used for DC.

The bridge rectifier circuit can also be regarded as a kind of full-wave rectifier circuit, and the transformer winding is connected to four diodes according to the method shown in the above figure. D 1 D 4 is four identical rectifier diodes, connected into a bridge form, so it is called a bridge rectifier circuit. The diode is used to guide the secondary output to the load even in the negative half cycle.

As can be seen from the figure, the current guided by D1 and D3 passes through RL from top to bottom during the positive half cycle, and the current guided by D2 and D4 also passes through RL from top to bottom during the negative half cycle, so as to achieve full-wave rectification. In this structure, if the same DC voltage is output, the secondary winding of the transformer only needs half the winding compared to full-wave rectification, but the wire diameter of the winding should be thickened accordingly if the current is to be output of the same magnitude. As for the pulsation, it is exactly the same as the full-wave rectifier circuit mentioned earlier.

The advantages of the bridge rectifier circuit are that the output voltage is high, the ripple voltage is small, the maximum reverse voltage borne by the tube is low, and at the same time, because the power transformer has a current supply load in the positive and negative half a week, the power transformer is fully utilized, and the efficiency is high.

Because the output voltage of the rectifier circuit contains a large pulsation component. In order to keep the pulsation component as low as possible, and on the other hand, to keep the DC component as much as possible, so that the output voltage is close to the ideal DC, this measure is filtering. Filtering is usually achieved using the energy storage of capacitors or inductors.

Schematic. Please click on the ** description.

1.Bridge rectifier circuits The average current flowing through each diode is: times the average load current. (The average is the average current that passes through a cycle). Each diode works only in half a cycle.

2.If the output of the single-phase bridge rectifier electrosensitive silver circuit does not have electrolytic capacitor filtering, the output voltage is several times of the transformer's secondary voltage (RMS). The DC voltage output after rectification has a poor degree of smoothness (the waveform is pulsating DC), and the stability is relatively poor.

3.If the output of the single-phase bridge rectifier circuit is filtered with electrolytic capacitors, the output voltage is multiple of the secondary voltage (RMS) of the transformer. The output DC voltage after rectification filtering has a good degree of smoothness (the waveform is close to a straight line), but its stability is still relatively poor.

4.If the output of the single-phase bridge rectifier circuit is equipped with an electrolytic capacitor filter and a voltage regulator circuit, the output voltage is determined by the voltage regulator circuit. After rectification, filtering, voltage stabilization (the voltage regulator tube plays a role in voltage stabilization in the circuit), the output DC voltage, the smoothness is good (the waveform is a straight line), and its stability is relatively good.

The output DC voltage is about 100 after direct 3*100V bridge rectification (unfiltered), and the output DC voltage is slightly lower than the peak phase voltage of 100 after half-wave finishing (unfiltered) by 3 diodes.

V AC voltage after rectification is 510V DC voltage.

2. Rectification is a physical phenomenon, and slow guessing refers to the difference in the amplitude of the forward and reverse currents under the same driving force

3. In terms of power electronics: the conversion of alternating current to direct current is called ACDC conversion, and the power flow direction of this transformation is transmitted from the power supply to the load, which is called rectification.

4. The rectifier circuit is a circuit that uses the unidirectional conductivity of the diode to change the positive and negative alternating AC voltage into a unidirectional pulsating voltage. Under the action of AC power supply, the rectifier limb return diode is periodically turned on and off, so that the load receives pulsating direct current.

5. In the positive half circumference of the power supply disturbance type, the diode is turned on, so that the current on the load is exactly the same as the voltage waveform shape; In the negative half cycle of the power supply voltage, the diode is in the reverse cut-off state, and the load voltage is almost zero when subjected to the negative half cycle voltage of the power supply.

Three-phase rectifier bridge principle.

Three-phase rectification circuits are proposed when the power is further increased or multiphase rectification is required for other reasons. Three-phase rectifier bridges are divided into two types: three-phase rectifier full bridge and three-phase rectifier half-bridge.

The rectifier circuit and operating voltage should be considered when selecting a rectifier bridge. Capacitors are required for rectifier circuits with high output voltage requirements, and capacitors for rectifier circuits with low output voltage requirements can be installed or without.

The above content refers to - Encyclopedia three-phase rectifier bridge.

The output of the three-phase rectifier bridge is pulsating DC, not pure DC voltage.

Your DC power is 20V*570A=, multiply it. This can be said to be your minimum power, and it can't be smaller, because this is the apparent power, and the power factor, and the transformer power should be greater than this value.

See the page below. But I think your calculations are single-phase.

Three-phase bridge (full-wave) rectification filtering.

Figure 2 shows the schematic of a three-phase bridge full-wave rectifier circuit. Figure 3 shows their rectifier waveform. Figure 3(a) shows the three-phase AC voltage waveform; Fig. 3(b) is a waveform of the three-phase half-wave rectification voltage; Figure 3(c) is a waveform of the three-phase full-wave rectification voltage.

In the output waveform diagram, the n-thick straight dashed line is the average output voltage value after rectification filtering, and the small pulsating wave below the dashed line and above the intersection point of each sine wave (above the thin dashed line) is the unfiltered output voltage waveform after rectification.

Fig.2. Schematic diagram of three-phase bridge full-wave rectifier circuit.

As can be seen from Figures 1 and 2, there is a difference between the structure of the three-phase half-wave rectifier circuit and the three-phase bridge full-wave rectifier circuit.

1) There are only three rectifier diodes in the three-phase half-wave rectifier circuit, while there are six rectifier diodes in the three-phase full-wave rectifier circuit;

2) The three-phase half-wave rectifier circuit requires the centerline of the input power supply, while the three-phase full-wave rectifier circuit does not require the centerline of the input power supply.

As can be seen from Figure 3, the three-phase half-wave rectifier waveform and the three-phase full-wave rectifier circuit do not require the centerline of the input power supply.

Fig.3. Waveform diagram of three-phase rectification.

The pulsation period of the three-phase half-wave rectifier waveform is 120, while the pulsation period of the three-phase full-wave rectifier waveform is 60.

The average value of the ripple amplitude and output voltage of the three-phase half-wave rectifier waveform:

The amplitude of the ripple of the three-phase half-wave rectifier waveform is: (1) where u is the amplitude voltage of the ripple; up is the sinusoidal half-wave amplitude voltage, such as the line voltage with an effective value of 380V, and its half-wave amplitude voltage is: (2).

Then its pulsating amplitude voltage is:

The average output voltage ud is obtained from 30 150 integrals, and 3) where ud is the average output voltage;

UA – the effective value of the phase voltage.

If the filter is followed by capacitive filtering, the output voltage is close to the amplitude up.

The amplitude of the pulsation of the three-phase full-wave rectifier waveform is:

The average output voltage ud is obtained from 60 120 integrals

uab= ua=514v (4)

where ud is the average output voltage and uab is the line voltage rms.

If the filter is followed by capacitive filtering, the output voltage is close to the amplitude up.

From the above calculations, it can also be seen that the three-phase full-wave rectification is much superior to the three-phase half-wave rectification, and the three-phase full-wave rectification can reach the maximum value up with a capacitor much smaller than the half-wave rectification. Therefore, the input rectifier of UPS adopts a three-phase full-wave rectification circuit.

The average current is it (0 5 0 8)id

id is the maximum current.

There are two main electrical parameters of the rectifier bridge, one is the withstand voltage, that is, the maximum voltage value applied by the rectifier bridge; The other is the current, and the maximum current that flows through the rectifier bridge.

The product of these two parameters, in turn, determines the power of the rectifier bridge.

In practice, neither the voltage nor the current is used at the maximum.

When selecting a finishing bridge, if the voltage is known (e.g., 220V), a component that is one step higher (e.g., 500V) should be selected. The current value is the maximum current value of the load (e.g. 3A), and a 5A rectifier bridge should be selected. Power is generally not considered in the design of rectifier circuits, so the power of the rectifier bridge is not an important parameter.

Of course, the higher the current, the more power it can hold.

Summary. <>

Hello! Dear, glad your question, what is the output voltage of the rectifier bridge? Help you find out: The voltage after bridge rectification is 310V.

What is the output voltage of the rectifier bridge?

Hello! Dear, glad your question, what is the output voltage of the rectifier bridge? Help you find out: The voltage after bridge rectification is 310V.

Dear, the voltage after bridge rectification is 310V.

The voltage after bridge rectification is 310V. The voltage after rectification is determined by the capacity of the transformer, the size of the filter capacitor and the size of the load current: if the load is zero, the output voltage of the 220V AC rectification without passing through the transformer is 220*.