Voltage output ripple

Ultimately, the designer must try-out the final design and check the output ripple voltage and the temperature rise of each capacitor. 

Maximum output current Output ripple voltage Output regulation ... 

Once again, high and low frequency limiting must be introduced on the control IC in order to minimize output ripple voltage and zero switching loss conditions. 

The results of the breadboard waveforms and the IsSpice waveforms are compared side by side in Figs. 4.15 and 4.16. Figure 4.15 shows the output ripple voltage at the top, with the inductor voltage at the bottom. Figure 4.16 shows the oscillator frequency at the top, with the... 

The transient domain model shown in Fig. 4.33 was used to measure output ripple voltage, transient response, gate voltage, and inductor current. This model properly predicts the cycle-by-cycle switching effects of the regulator. 

Figure 4.40 shows the simulated output ripple voltage, while Fig. 4.41 shows the simulated output voltage ripple. The measured transient response is shown in Fig. 4.42, while the simulated transient response is shown in Fig. 4.43. 

The advantages of forward-mode eonverters are they exhibit lower output peak-to-peak ripple voltages than do boost-mode eonverters, and they ean provide mueh higher levels of output power. Forward-mode eonverters ean provide up to kilowatts of power. 

Within multiple-output forward converters, it is possible to easily combine the filter chokes of complementary outputs (i.e., +/- 5V, etc.) together on the same core (see Figure 3-2f). This offers several advantages it saves space, vastly improves cross-regulation of those outputs, and exliibits superior ripple voltage levels on both outputs. 

The DC filter choke is used for ripple voltage and current reduction on the output of the switching power supply immediately following the existing filters. It is also used as an EMI filter on switching power supplies that have a single power line on the input, such as battery and distributed power systems. 

It appears that the circuit still functions properly since the output of the regulator is constant at 15 V. When you look at the input to the regulator, the ripple voltage across the capacitor is about twice the magnitude of the ripple voltage of the full-wave rectifier. This is the expected result. ... 

Figure 4.15a IsSpice LM78S40 waveforms (top, output ripple bottom, inductor voltage).

The input pulse and the output DC voltage were measured using an oscilloscope. The result picture is shown in Fig. 10.3a. Unfortunately, the ripple on the breadboard was small enough to be swamped by the noise in the lab, and we were not able to make an accurate measurement. The IsSpice model result is shown in Fig. 10.3b. The top waveform is the output voltage and the bottom waveform is the input pulse. 

The six-pulse rectifier bridges can be connected in such a manner as to produce a 12-pulse DC output voltage. The average value of DC ripple voltage is thereby reduced. From the AC power system point of view the magnitude of the harmonic components is reduced and some harmonics are eliminated. Figure 15.6 shows a typical circuit of a 12-pulse bridge. 

C1 is chosen to provide a maximum ripple voltage at the output node at the maximum load current. This ripple voltage is calculated from the average current per cycle that enters and leaves the capacitor. From... 

The low-pass filter shown in Fig. 3.117 does, however, increase the output resistance, which encourages the voltage to fall as the load current increases. This can be reduced if the resistor is replaced by a choke, which has a high impedance to the ripple voltage but a low resistance, which reduces the output ripple without increasing the output resistance. 

Smoothing circuit To obtain a near-constant voltage source for the inverter circuit a smoothing capacitance across the d.c. link is used to smooth the a.c. ripples present in the d.c. link after cotiversion. The capacitor retains the charge and provides a near-constant d.c. voltage output. 

In single-phase bridge circuits for ac connections and for very low ac output voltages below 5 V, single-phase center tap circuits are used as rectifier circuits for CP transformer-rectifiers. They have an efficiency of 60 to 15% and a residual ripple of 48% with a frequency of 100 Hz. A three-phase bridge circuit for three-phase alternating current is more economical for outputs of about 2 kW. It has an efficiency of about 80 to 90% and a residual ripple of 4% with a frequency of 300 Hz. The residual ripple is not significant in the electrochemical effect of the protection current so that both circuits are equally valid. 

Reducing the residual ripple from single-phase rectifiers for currents up to about 20 A and voltages of up to about 20 V can be achieved by filter circuits of choke coils and condensers. For greater output and constant residual ripple independent of load, the only possibility is the three-phase bridge circuit. It is always more satisfactory than a filter circuit. 

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