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1. (WO2015174939) PROTECTION D'ENTRÉE DE PUISSANCE COMPATIBLE AVEC LES NORMES MIL-STD-1275 MIL-STD-704
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

POWER INPUT PROTECTION COMPATIBLE WITH MIL-STD-1275 MIL-STD-704 STANDARDS

Field of the Invention

The present invention relates to an input protection, which enables to eliminate the problems resulting from voltage changes.

Background of the Invention

Momentary voltage rises and drops occurring in power input lines may cause permanent damages in the devices connected to these input lines. Various protection circuits are developed to prevent these damages. These circuits operate by using parallel connected passive elements without interruption, by using series-connected active elements without interruption and by using series-connected active elements with interruption in the operation.

The passive elements' level of limiting voltage varies in direct proportion with the coming power. This in turn increases voltage range of the protection level. Therefore the output voltage cannot be determined precisely. At the input voltages over the operating voltage of the passive elements, the said passive elements may be temporarily or permanently damaged. Furthermore the said passive elements dissipate overvoltage as heat. This causes the said material to get old. The said passive element values should be determined for each output voltage that is required, and this destroys application flexibility of the said power protection circuit.

If the input voltage rises above a determined level, the active elements hinder receiving output from the protection circuit. This means interruption of the operation of the device connected to the said output.

United States Patent document no. US6922322, an application known in the state of the art, discloses about reverse voltage and overvoHage protection for circuits.

Chinese utility model no. CN2757400 Y, an application known in the state of the art discloses a power module for automobiles.

Japanese patent document no. JP2003070150, an application known in the state of the ait, discloses a protective circuit for protecting a circuit from a lightning.

European Patent document no. EPl 142280 Bl, an application known in the state of the art, discloses a protection arrangement for a telephone subscriber line interface circuit

United States Patent document no. US2005007711, an application known in the state of the art, discloses an integrated circuit which has logic and timing circuits that provide protection when an AC adapter has improper voltage levels or polarity.

Summary of the Invention

An objective of the present invention is to provide an input protection, which enables to eliminate the problems resulting from voltage changes.

Another objective of the present invention is to provide an input protection which has a flexible operating voltage range.

Detailed Description of the Invention

An input protection developed to fulfill the objectives of the present invention is illustrated in the accompanying figures, in which:

Figure 1 is a schematic view of the input protection.

Figure 2 is a schematic view of the preferred embodiment of the reverse input protection.

Figure 3 is a schematic view of the preferred embodiment of the transient input protection.

Figure 4 is a schematic view of the preferred embodiment of the 24V limiter. Figure 5 is a schematic view of the preferred embodiment of the high voltage converter.

Figure 6 is a schematic view of the preferred embodiment of the low voltage converter.

Figure 7 is a schematic view of the preferred embodiment of the low voltage sensor.

Figure 8 is a schematic view of the preferred embodiment of the high voltage sensor.

Figure 9 is a schematic view of the preferred embodiment of the control unit.

Figure 10 is a schematic view of the preferred embodiment of the square wave generator.

Figure 1 1 is a schematic view of the preferred embodiment of the mosfet group.

The components shown in the figures are given reference numbers as follows:

1. Input protection

2. Reverse input protection

3. Transient voltage protection

4. Low voltage sensor

5. High voltage sensor

6. 24 V limiter

7. Wave generator

8. High voltage converter

9. Control unit

10. Low voltage converter

11. Mosfet group

A, B, C, D\ E, F, G, H, J, , L. Reference points

R. Resistor

C. Capacitor

D. Diode

ZD. Zener diode

TR. Transistor

TD. Integrated circuit

IC. Voltage reference

The input protection (1) of the present invention basically comprises

- at least one reverse input protection (2) which provides protection if supply voltage is provided with reverse polarity,

- at least one transient voltage protection (3) which compensates transient voltage fluctuations,

- at least one low voltage sensor (4) which detects low supply voltages,

- at least one high voltage sensor (5) which detects high supply voltages,

- at least one 24 V limiter (6) which enables to provide 24 V output by decreasing the input voltage,

- at least one wave generator (7) which preferably generates squaie waves in order to enable pulse width modulation (PWM),

- at least one high voltage converter (8) which decreases the voltage it receives from the 24 V limiter (6) in order to meet the power requirement of the low voltage sensor (4), high voltage sensor (5) and the wave generator (7),

- at least one control unit (9) which controls the wave generator (7) according to the voltage information it receives from the high voltage sensor (5),

- at least one low voltage converter (10) which decreases the voltage it receives from the high voltage converter (8) in order to meet the power requirement of the control unit (9),

- at least one mosfet group (1 1 ) which enables gradual voltage decrease if the supply voltage is higher than a predetermined level and which is driven by the wave generator (7).

The input protection (1 ) of the present invention comprises at least one reverse input protection (2) which provides protection if supply voltage is provided with reverse polarity (reverse supply). Thus, reverse supply is prevented from damaging the input protection (1) and a device connected to the input protection (1).

The present invention comprises at least one transient voltage protection (3) which compensates transient voltage fluctuations.

The input protection (1) of the present invention comprises at least one low voltage sensor (4) which detects whether the supply voltage is lower than a predetermined level. If the supply voltage is lower than a predetermined level, supplying power to a device connected to the input voltage (1) is prevented.

The input protection (1 ) of the present invention comprises at least one high voltage sensor (5) which detects whether the supply voltage is higher than a predetermined level.

The invention comprises at least one 24 V limiter (6) which enables to supply 24 V output by decreasing the supply voltage in order to enable supplying power to the elements having operating voltage lower than the supply voltage.

The input protection (1) of the present invention comprises at least one wave generator (7) which preferably generates square waves in order to enable pulse width modulation (PWM).

The said input protection (1) includes at least one high voltage converter (8) which decreases the voltage it receives from the 24 V limiter (6) in order to meet the power requirement of the low voltage sensor (4), high voltage sensor (5) and the wave generator (7).

The present invention comprises at least one control unit (9) which controls the wave generator (7) according to the voltage information it receives from the high voltage sensor (5), and at least one low voltage converter (10) which decreases the voltage it receives from the high voltage converter (8) in order to meet the power requirement of the said control unit (9).

The present invention further comprises at least one mosfet group (1 1 ) which enables gradual voltage decrease if the supply voltage is higher than a predetermine level and which is driven by the wave generator (7).

In the preferred embodiment of the invention, the high voltage converter (8) decreases the voltage it receives from the 24 V limiter to 10 V. However, when the supply voltage requirement of the low voltage sensor (4), high voltage sensor (5) and the wave generator (7) are different from each other, this voltage can be changed, for example to 12 V.

In the preferred embodiment of the invention, the low voltage converter (10) decreases the voltage that it receives from the high voltage converter (8) to 5V. However, in the case that the supply voltage requirement of the control unit (9) is different, this voltage can be changed, for example to 3.3 V.

In the preferred embodiment of the invention, the high voltage sensor (5) detects whether the supply voltage is higher than a predetermined level. Maximum voltage level that may be formed at the output of the protection region is at a level of 36 V. Then, the control unit (9) will enable to turn on the wave generator (7) such that it will provide the required voltage reduction or to turn it off for protection purposes. The mosfet group (1 1 ) is driven by the said wave and thus output voltage is enabled to be lower than the supply voltage.

In the preferred embodiment of the invention, the reverse input protection (2) basically comprises 4 P-channel mosfets. Use of P-channel mosfet enables the current to flow one way. Use of 4 mosfets enables to increase load current. Preferred embodiment of the reverse input protection (2) is given in Figure 2.

In the preferred embodiment of the invention, transient voltage protection (3) is provided by using two zener diodes which are connected in series in opposite polarities to each other. Preferred embodiment of the transient voltage protection (3) is given in Figure 3.

in the preferred embodiment of the invention, the 24 V limiter (6) limits the voltage by means of zener diodes. Preferred embodiment of the 24 V limiter (6) is given in Figure 4.

In the preferred embodiment of the invention, the high voltage converter (8) comprises at least one linear voltage regulator. Preferred embodiment of the high voltage converter (8) is given in Figure 5.

In the preferred embodiment of the invention, the low voltage converter (10) comprises at least one linear voltage regulator. Preferred embodiment of the low voltage converter (10) is given in Figure 6.

In the preferred embodiment of the invention, the low voltage sensor (4) comprises an operational amplifier. Preferred embodiment of the low voltage sensor (4) is given in Figure 7. In the said embodiment, supply voltage is applied to the low voltage sensor (4) from point D. This supply voltage is provided by the high voltage generator. The voltage at reference point B indicated on the figure is compared with the voltage generated by a voltage reference generator denoted with IC1. If the voltage value at point B is lower than a voltage corresponding to the reference voltage generated by the voltage reference generator, the signal at reference point F connected to the wave generator (7) is disabled and thus the wave generator (7) is disabled. This way, the mosfet group (11) is not driven and thus no power is supplied to the output.

In the preferred embodiment of the invention, the high voltage sensor (5) comprises an operational amplifier. Preferred embodiment of the high voltage sensor (5) is given in Figure 8. The voltage at reference point B indicated on the figure is compared with the voltage generated by a voltage reference generator denoted with IC1. If the voltage value at point B is higher than a voltage corresponding to the reference voltage generated by the voltage reference generator, the signal at point G is pulled to a high level. This way, the control unit (9) detects that the supply voltage is higher than a predetermined value.

In the preferred embodiment of the invention, the control unit (9) comprises a microcontroller. Preferred embodiment of the control unit (9) is given in Figure 9. In this embodiment, if the signal at point G is at a high level, in other words if the supply voltage is higher than a predetermined value, the microcontroller (TD1802) measures the period of this signal. If the high level signal continues more than 1 second, the microcontroller activates TR 1.801 , thereby disabling the signal that enables operation of the wave generator (7) at point K, and thus the wave generator (7) is disabled. This way, the mosfet group (1 1) is not driven and thus no power is supplied to the output.

Preferred embodiment of the wave generator (7) is given in Figure 10. In this embodiment, the wave at point H enables to drive the mosfet group (1 1 ). The signals coming from the points F and K prevent operation of the wave generator (7). This way, the mosfet group (1 1) is not driven and thus no power is supplied to the output. This in turn enables to prevent problems occurring due to low/high voltage.

In the preferred embodiment of the invention, the mosfet group (1 1) comprises at least three sets of mosfets each one of which comprises at least four mosfets. Preferred embodiment of the mosfet group (1 1 ) is given in Figure 11. In this embodiment, TR6,7,8,9 - TRIO, 1 1 ,12,13 - TR17,18,19,20 are connected parallel with the purpose of decreasing the heat they dissipate and the voltage drop that will occur thereon. These transistors have N-channel configurations. In order for the transistors to conduct, there should be VQS positive voltage between G (Gate) ends and S (Source) ends. The square wave signal coming from point H generates a DC voltage 10V more than the voltage level at points I, .1 and L by the help of the Cl lO, 1 1 1 , 1 13, 1 14, 1 16, 1 17 capacitors, D201 , 202, 203, 204, 205, 206 diodes, R201 , 202, 203, 204, 205, 206 resistors. Working voltage of the IRL2505 transistor is at VGS=2V level. This way the transistors are enabled to conduct. Maximum voltage level that may occur at point 1 by ZD13,14 is limited by 78-2=76V; maximum voltage level that may occur at point J by ZD 10, 11 is limited by 60-2=58V and maximum voltage level that may occur at point L by ZD3,12 is limited by 38-2=36V. Highest voltage supplied in MIL-STD-1275 and 704 standards is defined as 100V, 50 milliseconds.

Replacement of the zener diodes shown with IC reference is sufficient for changing the input operating voltage of the input protection (1) of the present invention. Replacement of these zener diodes changes the lower and upper operating voltage of the input protection (1). Replacement of the zener diodes denoted with ZD3 and ZD 12 references is sufficient for changing the output operating voltage of the input protection (1). Replacement of these zener diodes changes the output voltage level. This provides application flexibility to the protection (1) of the present invention.