rus
Issue #1/2021
Z. S. Geisser (Pavlova), A. V. Prilutsky, A. V. Fedorov
Diode Pumped Laser Power Supply for On-Board Application
Diode Pumped Laser Power Supply for On-Board Application
DOI: 10.22184/1993-7296.FRos.2021.15.1.46.50
Laser rangefinders and altimeters are increasingly being used in aeronautical engineering. Their high accuracy of range or altitude measurements, small dimensions and ease of integration into other on-board systems provide great potential for their use. However, the market is in need of commercially available laser power supplies operating stably from the on-board electrical mains, providing power up to 200 A and voltage up to 140 V in a pulsed mode. A power source for diode-pumped lasers for on-board use, operating from 27V mains, is proposed.
Laser rangefinders and altimeters are increasingly being used in aeronautical engineering. Their high accuracy of range or altitude measurements, small dimensions and ease of integration into other on-board systems provide great potential for their use. However, the market is in need of commercially available laser power supplies operating stably from the on-board electrical mains, providing power up to 200 A and voltage up to 140 V in a pulsed mode. A power source for diode-pumped lasers for on-board use, operating from 27V mains, is proposed.
Теги: aeronautical engineering laser laser power supplies on-board laser systems? laser rangefinders авиационная техника бортовые лазерные системы источники питания лазеров лазерные дальномеры лазеры
Diode Pumped Laser Power Supply for On-Board Application
Z. S. Geisser (Pavlova), A. V. Prilutsky, A. V. Fedorov
FEDAL LLC, St. Petersburg, Russia
Laser rangefinders and altimeters are increasingly being used in aeronautical engineering. Their high accuracy of range or altitude measurements, small dimensions and ease of integration into other on-board systems provide great potential for their use. However, the market is in need of commercially available laser power supplies operating stably from the on-board electrical mains, providing power up to 200 A and voltage up to 140 V in a pulsed mode. A power source for diode-pumped lasers for on-board use, operating from 27V mains, is proposed.
Keywords: Laser, Laser power supplies, On-board laser systems? Laser rangefinders, Aeronautical engineering
Received on: 05.02.2021
Accepted on: 24.02.2021
INTRODUCTION
The actual tasks of on-board laser systems are guidance and target designation. Laser guidance and targeting systems are used on military helicopters, aircraft and unmanned aerial vehicles of domestic and foreign production [1–4]. However, when developing laser radar systems for on-board use, the problem arises of choosing the appropriate laser sources and components. Its appearance is associated with the peculiarities of the use of laser measuring instruments in on-board equipment. The limited range of domestic and foreign manufacturers only exacerbates this problem.
An analysis of the Russian market of manufacturers, carried out by FEDAL, showed that there is no production of power supplies in Russia that work stably and without interference from the on-board mains and provide power up to 200 A and voltage up to 140 V in a pulse mode, with a frequency and pulse duration similar to similar products foreign production.
A wide scatter of parameters of products from different manufacturers in terms of currents and voltages was found. This is due to the production standards of diode matrices of each manufacturer: diode matrices manufactured by BWT, DILAS, Focuslight or matrices of domestic production by NPP «Inject» [5–8]. Imported matrices are most often designed to work with low voltage and high currents, while domestic ones, on the contrary, work with high voltages and low currents.
Thus, the FEDAL company faced the task of developing a universal power supply unit for onboard use with similar frequency and duration characteristics and extended pump current and voltage ranges. The application also determines the emergence of such requirements as small weight and size characteristics, closed design and operation in an extended operating temperature range from –40 to 50 °C.
LASER POWER SUPPLY:
ON-BOARD MODIFICATION
Note that one of the main differences between the onboard power supply circuitry and the standard 220 V power supplies (by FEDAL) is the supply voltage used in aircraft. If the standard mains for laboratory and industrial sources is 220–240 V mains or a three-phase 380 V, 50 / 60 Hz mains, then on board the aircraft the sources must be powered from a 27 V +3 / -4V DC mains. This radically changes the approach to constructing the charging part of the power supply, while leaving its discharge part practically unchanged [9].
Such a low supply voltage and, in connection with this, large switching currents do not allow efficient use of chargers based on resonant or quasi-resonant converters, built on a half-bridge or bridge circuit, which have proven themselves in sources powered by conventional mains [10].
In this regard, the most promising direction in our opinion is the use of charging topologies based on flyback or push-pull converters. The former have an indisputable advantage with an average power supply of <100 W, and the latter for an average power of up to 500 W. A further increase in power requires rejection of the aircraft’s power supply and switching to power supplies powered by external high-voltage lithium-ion or LiFePO4 batteries with a voltage of 310–320 V, which removes all power restrictions and allows lasers to be powered with laser output power up to 20–50 kW with a short operating mode.
FEDAL took the SF303M switching power supply as a basic model for testing circuit solutions of the charger from the 27 V on-board mains. The source has small dimensions with an average power of 150 W, a completely closed case without a fan and ventilation holes and has modifications for both low-voltage diode arrays with a voltage of up to 25 V and a current of up to 100 A with a pulse duration of up to 5 ms (erbium laser), and for powering several (from 1 to 3 connected in series) high-voltage matrices of the SLM‑2 type with a total voltage of 120–360 V and a current of up to 50 A with a pulse duration of up to 250 μs. In this case, the maximum frequency is limited by the power of the charger and does not exceed 20–30 Hz.
When building the charger, an original push-pull circuit was proposed, which combined the advantages of push-pull and resonant converters (Fig. 1.) Its distinguishing feature from the usual circuits is the series connection of a transformer with a resonant LC circuit. In this case, the current flowing through the primary winding of the transformer, and therefore the charge current of the storage capacitor, has a sinusoidal shape and is limited by the characteristic impedance of the LC circuit. In fact, an ideal current source is obtained, charging the storage capacitor according to a linear law in the entire range of output voltages (Fig. 2).
The maximum value of the output voltage is determined only by the transformation ratio of the transformer. In this case, as can be seen from Fig. 3, the transistors switching on and off occurs at zero current, which significantly reduces switching losses, and the sinusoidal form of current and voltage – the spectrum of radiated electromagnetic interference and simplifies the construction of the input line filter. Also, the advantages of the circuit include the time law of controlling the transistors of the converter, which does not require the use of feedbacks and PWM controllers, which increases the reliability of the power supply as a whole.
As a result of the changes, a new model of the SF303MB power supply was developed, designed to operate from the on-board 27V mains of aircraft in the temperature range of –40 to 50 °C in the overall dimensions of the standard SF303 block. The main technical characteristics of the new power supply are presented in the table.
Standard circuitry, while maintaining the condition F ∙ V ∙ I ∙ τ ≤ P and with a duty cycle of less than 20%, makes it possible to make various modifications of such parameters as current, voltage, duration and pulse repetition rate, slightly differing from those indicated in the table up or down c (provided that the maximum average power is maintained no more than 150 W).
CONCLUSION
As a result of market research, FEDAL faced the problem of lack of data on commercially available power supplies for lasers operating from 27 V mains. The proposed power supply for laser measuring instruments in aviation technology is a response to current market demands. The single diode drivers available on the market do not fully solve the assigned tasks due to the lack of galvanic isolation and low operating voltages up to 20 V. Also, the driver is not a complete product, but only an element of a more complex design, in contrast to power supplies.
Thus, this power supply is a versatile complete solution with a wide range of applications.
AUTHORS
Z. S. Geisser (Pavlova), A. V. Prilutsky, A. V. Fedorov, FEDAL LLC, St. Petersburg, Russia.
CORRESPONDING AUTHOR
Zoia (Pavlova) Geisser, Chief Operating Officer FEDAL LLC,
e-mail: z.pavlova@fedalel.com, St-Petersburg. Russia.
Z. S. Geisser (Pavlova), A. V. Prilutsky, A. V. Fedorov
FEDAL LLC, St. Petersburg, Russia
Laser rangefinders and altimeters are increasingly being used in aeronautical engineering. Their high accuracy of range or altitude measurements, small dimensions and ease of integration into other on-board systems provide great potential for their use. However, the market is in need of commercially available laser power supplies operating stably from the on-board electrical mains, providing power up to 200 A and voltage up to 140 V in a pulsed mode. A power source for diode-pumped lasers for on-board use, operating from 27V mains, is proposed.
Keywords: Laser, Laser power supplies, On-board laser systems? Laser rangefinders, Aeronautical engineering
Received on: 05.02.2021
Accepted on: 24.02.2021
INTRODUCTION
The actual tasks of on-board laser systems are guidance and target designation. Laser guidance and targeting systems are used on military helicopters, aircraft and unmanned aerial vehicles of domestic and foreign production [1–4]. However, when developing laser radar systems for on-board use, the problem arises of choosing the appropriate laser sources and components. Its appearance is associated with the peculiarities of the use of laser measuring instruments in on-board equipment. The limited range of domestic and foreign manufacturers only exacerbates this problem.
An analysis of the Russian market of manufacturers, carried out by FEDAL, showed that there is no production of power supplies in Russia that work stably and without interference from the on-board mains and provide power up to 200 A and voltage up to 140 V in a pulse mode, with a frequency and pulse duration similar to similar products foreign production.
A wide scatter of parameters of products from different manufacturers in terms of currents and voltages was found. This is due to the production standards of diode matrices of each manufacturer: diode matrices manufactured by BWT, DILAS, Focuslight or matrices of domestic production by NPP «Inject» [5–8]. Imported matrices are most often designed to work with low voltage and high currents, while domestic ones, on the contrary, work with high voltages and low currents.
Thus, the FEDAL company faced the task of developing a universal power supply unit for onboard use with similar frequency and duration characteristics and extended pump current and voltage ranges. The application also determines the emergence of such requirements as small weight and size characteristics, closed design and operation in an extended operating temperature range from –40 to 50 °C.
LASER POWER SUPPLY:
ON-BOARD MODIFICATION
Note that one of the main differences between the onboard power supply circuitry and the standard 220 V power supplies (by FEDAL) is the supply voltage used in aircraft. If the standard mains for laboratory and industrial sources is 220–240 V mains or a three-phase 380 V, 50 / 60 Hz mains, then on board the aircraft the sources must be powered from a 27 V +3 / -4V DC mains. This radically changes the approach to constructing the charging part of the power supply, while leaving its discharge part practically unchanged [9].
Such a low supply voltage and, in connection with this, large switching currents do not allow efficient use of chargers based on resonant or quasi-resonant converters, built on a half-bridge or bridge circuit, which have proven themselves in sources powered by conventional mains [10].
In this regard, the most promising direction in our opinion is the use of charging topologies based on flyback or push-pull converters. The former have an indisputable advantage with an average power supply of <100 W, and the latter for an average power of up to 500 W. A further increase in power requires rejection of the aircraft’s power supply and switching to power supplies powered by external high-voltage lithium-ion or LiFePO4 batteries with a voltage of 310–320 V, which removes all power restrictions and allows lasers to be powered with laser output power up to 20–50 kW with a short operating mode.
FEDAL took the SF303M switching power supply as a basic model for testing circuit solutions of the charger from the 27 V on-board mains. The source has small dimensions with an average power of 150 W, a completely closed case without a fan and ventilation holes and has modifications for both low-voltage diode arrays with a voltage of up to 25 V and a current of up to 100 A with a pulse duration of up to 5 ms (erbium laser), and for powering several (from 1 to 3 connected in series) high-voltage matrices of the SLM‑2 type with a total voltage of 120–360 V and a current of up to 50 A with a pulse duration of up to 250 μs. In this case, the maximum frequency is limited by the power of the charger and does not exceed 20–30 Hz.
When building the charger, an original push-pull circuit was proposed, which combined the advantages of push-pull and resonant converters (Fig. 1.) Its distinguishing feature from the usual circuits is the series connection of a transformer with a resonant LC circuit. In this case, the current flowing through the primary winding of the transformer, and therefore the charge current of the storage capacitor, has a sinusoidal shape and is limited by the characteristic impedance of the LC circuit. In fact, an ideal current source is obtained, charging the storage capacitor according to a linear law in the entire range of output voltages (Fig. 2).
The maximum value of the output voltage is determined only by the transformation ratio of the transformer. In this case, as can be seen from Fig. 3, the transistors switching on and off occurs at zero current, which significantly reduces switching losses, and the sinusoidal form of current and voltage – the spectrum of radiated electromagnetic interference and simplifies the construction of the input line filter. Also, the advantages of the circuit include the time law of controlling the transistors of the converter, which does not require the use of feedbacks and PWM controllers, which increases the reliability of the power supply as a whole.
As a result of the changes, a new model of the SF303MB power supply was developed, designed to operate from the on-board 27V mains of aircraft in the temperature range of –40 to 50 °C in the overall dimensions of the standard SF303 block. The main technical characteristics of the new power supply are presented in the table.
Standard circuitry, while maintaining the condition F ∙ V ∙ I ∙ τ ≤ P and with a duty cycle of less than 20%, makes it possible to make various modifications of such parameters as current, voltage, duration and pulse repetition rate, slightly differing from those indicated in the table up or down c (provided that the maximum average power is maintained no more than 150 W).
CONCLUSION
As a result of market research, FEDAL faced the problem of lack of data on commercially available power supplies for lasers operating from 27 V mains. The proposed power supply for laser measuring instruments in aviation technology is a response to current market demands. The single diode drivers available on the market do not fully solve the assigned tasks due to the lack of galvanic isolation and low operating voltages up to 20 V. Also, the driver is not a complete product, but only an element of a more complex design, in contrast to power supplies.
Thus, this power supply is a versatile complete solution with a wide range of applications.
AUTHORS
Z. S. Geisser (Pavlova), A. V. Prilutsky, A. V. Fedorov, FEDAL LLC, St. Petersburg, Russia.
CORRESPONDING AUTHOR
Zoia (Pavlova) Geisser, Chief Operating Officer FEDAL LLC,
e-mail: z.pavlova@fedalel.com, St-Petersburg. Russia.
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