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Large Voltage Range Conversion Technique

IP.com Disclosure Number: IPCOM000088309D
Publication Date: 2005-Mar-04
Document File: 4 page(s) / 543K

Publishing Venue

The IP.com Prior Art Database

Abstract

For traditional DC-DC converter, the efficiency of the converter has limitation, the efficiency of the converter with step-up ratio larger than 50 will be very low. For instance, the step-up ratio of a boost converter, because of the effect of parasitic elements loss at inductors, switch and diodes, usually cannot get higher than 4. For a forward converter, it is difficult to build a transformer, which can handle high step-up ratio in high efficiency. This paper presents a technique to improve the efficiency of step-up the voltage in a low voltage level to high level. This technique is particularly useful in the burn-in test of multiple outputs (low voltage such as 3.3V and 5V) converters with common ground. It is because only one of the outputs needs to be connected in series to obtain a high voltage.

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LARGE

VOLTAGE

RANGE

CONVERSION TECHNIQUE

CHAN, Tony Kee-Ming; LEUNG, Andrew Siu-Wai; LI, River Tin-Ho

March 2005

ABSTRACT

For traditional DC-DC converter, the efficiency of the converter has limitation, the efficiency of the converter with step-up ratio larger than 50 will be very low. For instance, the step-up ratio of a boost converter, because of the effect of parasitic elements loss at inductors, switch and diodes, usually cannot get higher than 4. For a forward converter, it is difficult to build a transformer, which can handle high step-up ratio in high efficiency.

This paper presents a technique to improve the efficiency of step-up the voltage in a low voltage level to high level. This technique is particularly useful in the burn-in test of multiple outputs (low voltage such as 3.3V and 5V) converters with common ground. It is because only one of the outputs needs to be connected in series to obtain a high voltage.

Figure 1: Large

Voltage

Range

Conversion Technique

For the efficiency of stage A and B be 80%, the overall efficiency of this technique is 64%.

 


NEW INVENTIONS DESCRIPTION

The invention consists of a forward converter and a boost converter with lossless snubber.

Following is the circuitry of the large voltage range conversion technique. Three forward converters are connected in series and then a boost converter is used to boost up the output voltage.

The turn ratio, Np:Ns, of the forward converter’s transformer is 1:4. The duty ratio of the forward converter is 0.5.

Vout of 1:2 isolated converter = (Ns/Np) * Vin of 1:2 isolated converter * D

Vout of 1:2 isolated converter = (4/1) * Vin of 1:2 isolated converter * 0.5

Vout of 1:2 isolated converter  = 2 Vin of 1:2 isolated converter

The duty ratio of boost converter is defined by the desired output voltage under the equation:

Vin of boost converter / (1 – D) = Vout of boost converter

Following table is some experimental results of the 1:2 isolation converter:

Vin / V

Iin / A

Vout / V

Iout / A

Efficiency / %

2.0

3.04

3.33

1.15

63.0

3.0

3.03

6.02

1.10

73.3

4.0

3.03

8.7

1.03

73.9

5.0

3.03

11.10

0.98

71.8

6.0

3.02

11.84

1.08

70.6

Following table is some experiment results of the boost converter:

Vin / V

Iin / A

Vout / V

Iout / A

Efficiency / %

50

1.36

87.4

0.89

95.4

49.8

2.46

87.6

1.3

92.9

49.4

2.89

87.4

1.54

94.2

49.4

3.22

88.2

1.72

95.3

49.3

3.43

88.9

1.82

95.6

49.2

3.79

88.7

1.96

93.2

49.4

4.29

91.2

2.18

93.8

49.1

4.56

91.7

2.3

94.1

49.1

4.77

92.4

2.38

93.8

Efficiency of the 1:2 isolation converters and the boost converter are...