**4.1. Control and gate signal generating circuit for controlled AC voltage regulator**

Figure 29 shows the circuit of the proposed automatic controlled AC voltage regulator including the control and gate signal generating circuit. A fraction of the output voltage after capacitor voltage dividing and rectifying is passed through an OPAMP buffer. Buffer is used to remove the loading effect. Output voltage of the buffer is same as its input voltage. The output voltage of the buffer is further reduces using resistive voltage divider and taken as the negative input of the error amplifier of the PWM voltage regulating IC SG1524B.

The positive input of the error amplifier is taken from the reference voltage of the chip, after voltage dividing using 50K and 1 ohm resistance. The positive input of the error amplifier is fixed and the negative input is error signal which will vary according to the output voltage. Since the error signal is applied to the negative input of the error amplifier, the duty cycle will be increased if the error signal is decreased and vice versa.

When the output voltage increases above the set value which is 300V either due to change in input voltage or load, the error signal will be increased, therefore the duty cycle will decrease. As a result less power will be transferred from the input to output, and output voltage start to decrease until it reaches to the set value.

When the output voltage decreases below the set value either due to change in input voltage or load then error signal will be decreased which will increase the duty cycle. As a result, more power will be transferred from the input to output, and output voltage start to increase until it reaches to the set value.

Power Quality Improvement Using Switch Mode Regulator 143

waveforms of the input current and output currents corresponding to the waveforms of Fig.

**Figure 30.** Input and output voltage waveforms for input 250V and output 300V. V1(V5): Input voltage-

Time

0s 100ms 200ms 300ms 400ms 500ms 600ms

**Figure 31.** Input and output voltage waveforms for input 350V and output 300V. V1(V5): Input voltage-

Time

0s 100ms 200ms 300ms 400ms 500ms 600ms

Table 1 summarizes the result of the proposed regulator to regulate output voltage to 300V for variation of input voltage from 200V to 350V and load from 100 ohm to 200 ohm. In this

30 and Fig. 31 for a load of 100 Ω.

bottom figure, V(R14:2): Output voltage – top figure.

V(R14:2)

V1(V5)

V(R14:2)



0V

400V


SEL>>

0V

500V

SEL>>

0V

400V


0V

400V

bottom figure, V(R14:2): Output voltage – top figure.

V1(V5)

When the output voltage is same as the set value than the negative and positive input of the error amplifier will be same as a result the duty cycle will remain same and output voltage will remain unchanged. In this way the proposed regulator will maintain output voltage constant, irrespective of the variation of input voltage and load.

**Figure 29.** Automatic controlled AC voltage regulator circuit with practical switches.

#### **4.2. Results of automatic controlled AC voltage regulator**

Figure 30 shows the input and output voltage waveforms of the proposed automatic controlled AC voltage regulator when the input voltage is 250V and output voltage is 300V. Figure 31 shows the input and output voltage waveforms of the proposed regulator when the input voltage is 350V and output voltage is 300V. Figure 32 and Fig. 33 shows the waveforms of the input current and output currents corresponding to the waveforms of Fig. 30 and Fig. 31 for a load of 100 Ω.

142 An Update on Power Quality

R14 50k

R4 1

0

0

0

V5

L1 30mH

FREQ = 50 VAMPL = 300

> C3 5u

increase until it reaches to the set value.

U1

16

VIN

CT RT

ERR-ERR+ CL+ CL-

3

VREF

15

C1

V1 20Vdc

4000pf

7 6

constant, irrespective of the variation of input voltage and load.

R1

0

0

0

10

R2 50k

C2 .001u

SHUT

C\_A E\_A E\_B C\_B

OSC

V2 10Vdc

0

R5

0

8

GND

9

COMP

SG1524B

0

0

D3

D4

C6 0.1u

D1

D2

G1

S1

**Figure 29.** Automatic controlled AC voltage regulator circuit with practical switches.

D5

R11 0.001

D7

G2

Figure 30 shows the input and output voltage waveforms of the proposed automatic controlled AC voltage regulator when the input voltage is 250V and output voltage is 300V. Figure 31 shows the input and output voltage waveforms of the proposed regulator when the input voltage is 350V and output voltage is 300V. Figure 32 and Fig. 33 shows the

S2

Z3

D10

C5 0.1u R13 1

D6

D8

2 6 0

U2A

C8 10u

0

R3 100 S2

V3 15V

> V7 20V

+


U5A LM324

3

2

G1

V4 15V

G2

S1

C7 0.1u

C9 0.3u

R17 4000k

0

1

R9

11

4

0

V+

 V-OUT

L2 30mH

R19

R18

TX1

0

R6

U4 A4N25A

0

C4 5u

R7

R8

U3 A4N25A

R16

0

R15

**4.2. Results of automatic controlled AC voltage regulator** 

0

D9

R10 1

Z1

R12 0.001

more power will be transferred from the input to output, and output voltage start to

When the output voltage is same as the set value than the negative and positive input of the error amplifier will be same as a result the duty cycle will remain same and output voltage will remain unchanged. In this way the proposed regulator will maintain output voltage

> 2 6 0

CD4009A

3 2

**Figure 30.** Input and output voltage waveforms for input 250V and output 300V. V1(V5): Input voltagebottom figure, V(R14:2): Output voltage – top figure.

**Figure 31.** Input and output voltage waveforms for input 350V and output 300V. V1(V5): Input voltagebottom figure, V(R14:2): Output voltage – top figure.

Table 1 summarizes the result of the proposed regulator to regulate output voltage to 300V for variation of input voltage from 200V to 350V and load from 100 ohm to 200 ohm. In this table input current, output current, input power factor, and efficiency of the regulator are also provided. The proposed regulator can regulate the output voltage effectively, for a wide variation of input voltage and load with efficiency of more than 90% and input power factor more than 0.9.

Power Quality Improvement Using Switch Mode Regulator 145

Pout (W) Efficiency (%)

Iout (A)

Vin (V) I in (A)

**5. Conclusion** 

Input pf Pin

\*All voltages and currents values in this table are in peak values.

conventional linear power supplies.

maintenance are reduced.

(W)

Vout (V) Load

200 4.81 1.00 481 295 100 2.95 435.13 90.46 225 4.30 1.00 483.09 298 100 2.98 444.02 91.91 250 3.92 1.00 489.70 300 100 3.00 450.00 91.89 275 3.60 1.00 495.00 300 100 3.00 450.00 90.91 300 3.30 1.00 493.79 300 100 3.00 450.00 91.13 325 3.10 0.99 498.85 302 100 3.02 456.02 91.41 350 2.95 0.98 508.41 305 100 3.05 465.13 91.49 250 2.07 0.96 248.73 300 200 1.50 225.00 90.46 275 1.90 0.95 248.46 300 200 1.50 225.00 90.56 300 1.75 0.95 248.20 300 200 1.50 225.00 90.65 325 1.68 0.93 253.12 302 200 1.51 228.01 90.08 350 1.60 0.91 253.77 305 200 1.53 232.56 91.64

**Table 1.** Results of proposed automatic controlled AC voltage regulator for maintaining output 300 V.

An essential feature of efficient electronic power processing is the use of semiconductors devices in switch mode to control the transfer of energy from source to load through the use of pulse width modulation techniques. Inductive and capacitive energy storage elements are used to smooth the flow of energy while keeping losses at a lower level. As the frequency of the switching increases, the size of the capacitive and inductive elements decreases in a direct proportion. Because of the superior performance, the SMPS are replacing

In this chapter the design and analysis of an AC voltage regulator operated in switch mode is described in details. AC voltage regulator is used to maintain output voltage constant either for an input voltage variation or load variation to improve the power quality. If the output voltage remains constant, equipment life time increases and outages and

At first the regulator is analyzed using ideal switches, then the ideal switches is replaced by practical switches which required isolated gate signal. The procedure of smoothing the input current and output voltage, and suppressing the surge voltage across the switches is described. A manually controlled AC voltage regulator is analyzed then the concept of operation of an automatic controlled AC voltage regulator is described. Finally an automatic

The proposed regulator can maintain the output voltage constant to 300V, when input voltage is vary from 200V to 350V also for variation of load. To maintain constant output voltage PWM control is used. By varying the duty cycle of the control circuit have achieved the goal of maintaining the constant output voltage across load. For generation of gate

controlled AC voltage regulator is designed and its performance is analyzed.

(Ω)

**Figure 32.** Input and output current waveforms for input 250V output 300V. -I(V5): Input current – bottom figure, -I(R14): Output current – top figure.

**Figure 33.** Input and output current waveforms for input 350V output 300V. -I(V5): Input current – bottom figure, -I(R14): Output current – top figure.


\*All voltages and currents values in this table are in peak values.

**Table 1.** Results of proposed automatic controlled AC voltage regulator for maintaining output 300 V.

### **5. Conclusion**

144 An Update on Power Quality

factor more than 0.9.



0A

5.0A


SEL>>

0A

5.0A

0A

5.0A


SEL>>

0A

4.0A

table input current, output current, input power factor, and efficiency of the regulator are also provided. The proposed regulator can regulate the output voltage effectively, for a wide variation of input voltage and load with efficiency of more than 90% and input power

**Figure 32.** Input and output current waveforms for input 250V output 300V. -I(V5): Input current –

Time

0s 100ms 200ms 300ms 400ms 500ms 600ms

**Figure 33.** Input and output current waveforms for input 350V output 300V. -I(V5): Input current –

Time

0s 100ms 200ms 300ms 400ms 500ms 600ms

bottom figure, -I(R14): Output current – top figure.




bottom figure, -I(R14): Output current – top figure.


An essential feature of efficient electronic power processing is the use of semiconductors devices in switch mode to control the transfer of energy from source to load through the use of pulse width modulation techniques. Inductive and capacitive energy storage elements are used to smooth the flow of energy while keeping losses at a lower level. As the frequency of the switching increases, the size of the capacitive and inductive elements decreases in a direct proportion. Because of the superior performance, the SMPS are replacing conventional linear power supplies.

In this chapter the design and analysis of an AC voltage regulator operated in switch mode is described in details. AC voltage regulator is used to maintain output voltage constant either for an input voltage variation or load variation to improve the power quality. If the output voltage remains constant, equipment life time increases and outages and maintenance are reduced.

At first the regulator is analyzed using ideal switches, then the ideal switches is replaced by practical switches which required isolated gate signal. The procedure of smoothing the input current and output voltage, and suppressing the surge voltage across the switches is described. A manually controlled AC voltage regulator is analyzed then the concept of operation of an automatic controlled AC voltage regulator is described. Finally an automatic controlled AC voltage regulator is designed and its performance is analyzed.

The proposed regulator can maintain the output voltage constant to 300V, when input voltage is vary from 200V to 350V also for variation of load. To maintain constant output voltage PWM control is used. By varying the duty cycle of the control circuit have achieved the goal of maintaining the constant output voltage across load. For generation of gate

signal of the switches an IC chip SG1524B is used which is compact and commercially available at a very low cost. The input current of the proposed regulator is sinusoidal and the input power factor is above 0.9. From simulation results it is seen that the efficiency of the proposed regulator is more than 90%.

Power Quality Improvement Using Switch Mode Regulator 147

[12] G. Venkataramanan. B. K. Johnson, and A. Sundaram, "An AC-AC power converter for custom power applications," IEEE Transactions on Power Delivery, vol. 11, pp. 1666-

[13] V. Nazquez, A. Velazquez, C. Hernandez, E. Rodríguez and R. Orosco, "A Fast AC Voltage Regulator,", CIEP 2008. 11th IEEE International Power Electronics Congress, pp.

[14] J. Nan, T. Hou-jun, L. Wei and Y. Peng-sheng, "Analysis and control of Buck-Boost Chopper type AC voltage regulator,", IPEC'09. IEEE 6th International Power Electronics

[15] N. A. Ahmed, M. Miyatake, H. W. Lee and M. Nakaoka, "A Novel Circuit Topology of Three-Phase Direct AC-AC PWM Voltage Regulator" Industry Applications Conference, 2006. 41st IAS Annual Meeting. Conference Record of the 2006 IEEE, pp.

[16] V. Nazquez, A. Velazquez and C. Hernandez, "AC Voltage Regulator Based on the AC-AC Buck-Boost Converter," ISIE 2007. IEEE International Symposium on Industrial

[17] P. K. Banerjee, "Power line voltage regulation by PWM AC Buck-Boost voltage

[18] A. Hossain, "AC voltage regulation by Cûk switch mode power supply," A M.Sc.

[19] Li B. H., Choi S.S., Vilathgamuwa D. M., Design considerations on the line-side filter used in the dynamic voltage restorer, IEE Proceedings - Generation, Transmission, and

[20] Wang Jing, Xu Aiqin, Shen Yueyue., A Survey on Control Strategies of Dynamic Voltage Restorer, 13th International Conference on Harmonics and Quality of Power

[21] Nielsen J.G., Blaabjerg F., A Detailed Comparison of System Topologies for Dynamic Voltage Restorers, IEEE Transactions on Industry Applications, vol, 41, no. 5, pp. 1272-

[23] Slobodan Cûk, "Basics of Switched Mode Power Conversion Topologies, Magnetics, and Control," Modern Power Electronics: Evaluation, Technology, and applications,

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[26] R. Thompson, "A Thyristor Alternating Voltage Regulator," IEEE Trans. on Ind. and

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