Application Note 7511

It’s impractical, however, to rate an inverter based on locked- rotor current. You can avoid this necessity by adjusting the switching regulator’s output voltage and by providing a fixed output-current limit slightly higher than the maximum full- load current. This way, the current requirements during start- up will never exceed the current capability of an efficiently sized inverter.

For example, consider a 2-hp, 3-phase induction motor spec- ifying VL at 230V RMS and full-load current (ILFL) at 6.2A

RMS. For the peak current of 8.766A, you can select IGT type D94FR4. This device has a reverse-breakdown SOA (RBSOA) of 10A, 500V for a clamped inductive load at a junction temperature of 150oC. A 400V IGT could also do the job, but the 500V choice gives an additional derating safety margin. You must set the current limit at 9A to limit the in- rush current during start-up. Note that thanks to the IGT’s adequate RBSOA, you don’t need turn-off snubbers.

 

2.

 

5V

 

3.3k

 

 

 

7 4

 

8 3

2.7k

NE555

 

6 2

 

1 5

1000pF

 

 

 

 

VCO &

A

4.7k

 

TIMING

 

 

 

LOGIC

 

 

 

 

 

 

 

 

24V

 

 

 

 

DC BUS

 

 

 

 

 

470

 

PIEZOCOUPLER

 

 

 

 

 

 

 

 

 

 

1N914 E

Q1

 

 

 

 

 

D

 

 

 

 

 

 

 

 

 

 

 

 

 

D94FR4

1N914

1k

 

C

1k

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PZT61343

 

 

4.7k

 

 

 

 

 

 

Q8

 

1N914

 

 

 

 

 

 

24V

2N3903

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.001F

1N914

4.7k

 

Q8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

φA

 

 

 

 

2N3903

470

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5V

 

 

 

 

 

 

 

 

 

 

 

470

 

 

 

 

D33030

 

 

 

 

 

 

 

 

 

Q3

3

 

 

1N914

F

Q

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

22F

 

 

 

 

D94FR4

Q7

 

 

 

 

10

 

 

 

 

470

 

 

 

 

 

 

 

 

 

 

 

 

2N3903

 

4.7k

 

 

 

 

 

C1

 

 

 

 

2N3903

 

 

 

 

 

 

Q5

 

 

 

D29E10

 

 

10

 

 

 

 

 

 

Q4

 

 

 

 

 

 

 

 

 

 

 

1N914

 

 

 

 

FIGURE 11A. PROVIDING PROPERLY TIMED DRIVE TO THE IGTS, THE CIRCUIT USES PIEZO COUPLING TO THE UPPER POWER DEVICE. THE 3-TRANSISTOR DELAY CIRCUIT PROVIDES THE NEEDED 15o LAG TO THE LOWER IGT TO AVOID CROSS CONDUCTION.

 

VOLTS

24V

 

F

 

24V

 

E

TIME

24V

 

D

TIME

5V

 

C

TIME

 

100kHz

5V

 

B

TIME

5V

 

A

TIME

 

FIGURE 11B. THE TIMING DIAGRAM SHOWS THE 555’S 108-KHz DRIVE TO THE PIEZO DEVICE AND THE LATTER’S SLOW RESPONSE.

©2002 Fairchild Semiconductor Corporation

Application Note 7511 Rev. A1

Page 7
Image 7
Fairchild AN-7511 manual VCO Timing Logic

AN-7511 specifications

The Fairchild AN-7511 is a versatile, twin-engine turboprop aircraft designed for a myriad of military applications, including cargo transport, surveillance, and personnel movement. Developed by Fairchild Aircraft in the 1970s, the AN-7511 represents a significant evolution in tactical airlift capabilities, aimed at meeting the diverse needs of the United States Armed Forces and allied nations.

One of the standout features of the AN-7511 is its impressive cargo capacity. The aircraft can carry up to 10 tons of cargo, making it suitable for transporting supplies, equipment, and even troops in various operational scenarios. Its rear ramp design facilitates rapid loading and unloading, which is crucial in military operations where time can be of the essence.

The AN-7511 is powered by two turboprop engines, which provide a combination of efficiency and reliability. These engines offer superior performance at various altitudes and are designed to operate in diverse environmental conditions. The aircraft’s range allows it to execute long-distance missions without the need for frequent refueling, which is vital for sustained operations in remote areas.

In terms of technologies, the AN-7511 features advanced avionics that enhance navigation and situational awareness for the crew. These systems incorporate modern instruments that ensure safe flight operations, even in challenging weather conditions. The cockpit layout is designed for ease of use, enabling pilots to maintain focus on mission objectives.

Another notable characteristic of the AN-7511 is its rugged construction. The airframe is built to endure the rigors of military flights, including rough landings on unpaved airstrips. This durability is complemented by a relatively short takeoff and landing distance, allowing the aircraft to operate in austere environments.

Moreover, the AN-7511 can be equipped with various mission-specific systems, such as surveillance pods or electronic warfare equipment, making it adaptable for different roles. This flexibility extends the operational capabilities of the aircraft, enabling it to fulfill multiple mission types in support of military objectives.

In summary, the Fairchild AN-7511 is a robust and adaptable aircraft that combines advanced technologies with military practicality. Its cargo capacity, range, reliability, and operational flexibility make it a valuable asset for any airlift or tactical operation, ensuring that it remains a critical component of military aviation efforts.