GB1588303A - Power conversion apparatus for aircraft - Google Patents
Power conversion apparatus for aircraft Download PDFInfo
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- GB1588303A GB1588303A GB8730/78A GB873078A GB1588303A GB 1588303 A GB1588303 A GB 1588303A GB 8730/78 A GB8730/78 A GB 8730/78A GB 873078 A GB873078 A GB 873078A GB 1588303 A GB1588303 A GB 1588303A
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- phase
- power
- aircraft
- amplifier
- output
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- 238000006243 chemical reaction Methods 0.000 title claims description 14
- 238000004804 winding Methods 0.000 claims description 31
- 230000008878 coupling Effects 0.000 claims description 17
- 238000010168 coupling process Methods 0.000 claims description 17
- 238000005859 coupling reaction Methods 0.000 claims description 17
- 230000001681 protective effect Effects 0.000 claims description 12
- 230000007935 neutral effect Effects 0.000 claims description 9
- 230000000903 blocking effect Effects 0.000 claims description 6
- 238000002955 isolation Methods 0.000 claims description 6
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 4
- 230000003068 static effect Effects 0.000 claims description 4
- 238000009434 installation Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 230000002829 reductive effect Effects 0.000 claims description 3
- 230000003190 augmentative effect Effects 0.000 claims description 2
- 230000007547 defect Effects 0.000 claims description 2
- 238000004806 packaging method and process Methods 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims 2
- 239000003990 capacitor Substances 0.000 description 18
- 230000001105 regulatory effect Effects 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/337—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration
- H02M3/3376—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current
- H02M3/3378—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current in a push-pull configuration of the parallel type
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/538—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration
- H02M7/53803—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration with automatic control of output voltage or current
- H02M7/53806—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration with automatic control of output voltage or current in a push-pull configuration of the parallel type
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Rectifiers (AREA)
- Inverter Devices (AREA)
- Amplifiers (AREA)
Description
(54) POWER CONVERSION APPARATUS FOR AIRCRAFT
(71) We, SPERRY RAND CORPORATION, a Corporation organised and existing under the laws of the State of Delaware, United States of
America, of 1290 Avenue of the Americas,
New York, New York 10019, United States of
America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to power conversion apparatus and is particularly, but not exclusively, concerned with compact and inexpensive power conversion apparatus for employing the single-phase and direct current outputs of a conventional airborne power supply to generate stable, regulated three-phase power signals on wie-connected grounded neutral, distribution lines.
Generally, airborne power supplies for aircraft navigation instrumentation and control systems have fallen mainly into two categories.
For example, a first kind of voltage regulated supply furnishes only limited amplitude singlephase power, no three-phase power being generated. Relatively high levels of direct current power, such as at 28 volts, are also provided.
For direct use in aircraft so equipped, instruments and controls for the aircraft are designed primarily for the use of direct current and secondarily for operation with single-phase alternating current.
On the other hand, many types of aircraft instruments and controls are purposely designed to operate primarily from a second class of power supply providing a relatively high power, three-phase output. Such supplies normally provide regulated 115 and 200 volt levels of alternating current on four-wire, grounded neutral, power distribution lines. A secondary provision of relatively lower power level direct current at, say 28 volts, is also often made by the second class of power supply.
It is often desired to operate equipment designed for use with one such class of power supply with the other class of power supply, a situation requiring interconnecting power adaption or converting elements. By recourse to the present invention apparatus originally designed to operate with the foregoing second class of power supply can be converted, enabling it to operate safely and efficiently with the first class of power supply. For this purpose, inverters yielding three-phase energy have been employed in the past with some success; however, such inverters are expensive and heavy and occupy valuable space within the aircraft fuselage. Because of these and other disadvantageous factors, inverter systems do not represent an attractive solution to the problem.
According to one aspect of the invention there is provided power conversion apparatus intended to be responsive jointly to aircraft single-phase alternating current power supply means and to aircraft direct current power supply means for generating three-phase alternating current aboard an aircraft of sub stan- tially greater power level than the power level of said aircraft single-phase power supply means, comprising network means for shifting the phase of said single phase alternating current by substantially ninety degrees, first amplifier means having an input responsive to said network means, push-pull power amplifier means responsive to said first amplifier means, first transformer means having first primary and first secondary means, said first primary means being responsive to said push-pull power amplifier means, said first secondary means having first tap means which are at the centre of the first secondary means, second transformer means having second primary and second secondary means, said second primary means being responsive to said single phase alternating current, said first tap means being coupled to a first end of said second secondary means, said second transformer means providing neutral output coupling means and a first phase output signal, a first end of said first secondary means providing a second phase output signal, and a second end of said first secondary means providing a third phase output signal.
According to another aspect of the invention there is provided power conversion apparatus intended to be responsive jointly to aircraft single phase alternating current power supply means and to aircraft direct current power supply means for generating three-phase alternating current aboard an aircraft of substantially greater power level than the maximum power level of said aircraft single phase power supply means, the apparatus comprising network means for shifting the phase of the single phase alternating current by substantially ninety degrees, first amplifier means having signal input means responsive to the network means, push-pull power amplifier means responsive to the first amplifier means, output transformer means having two secondary winding means for providing discrete threephase output currents, the output transformer means having first and second primary winding means, the first primary winding means having centre tap means, the first primary winding means being responsive to the push-pull power amplifier means, and the second primary winding means being responsive to the single phase alternating current, impedance means coupled to the centre tap means for sensing the level of the three-phase output currents and comparing the latter with a predetermined safe value, and limiter means responsive to the impedance means for generating a control signal only when the predetermined safe value is exceeded, the signal input means thereupon being responsive to the limiter means control signal by reducing the output of the first amplifier means substantially to zero.
In a preferred embodiment of the invention, the single-phase output of the aircraft power supply is phase shifted to form quadrature voltages which are then subjected to power amplification before use to excite certain inputs of an output transformer system. The latter system combines the quadrature signals with the single-phase output of the supply as a reference to yield the phase power on wieconnected, grounded neutral, distribution lines.
Automatic feedback for gain control is provided so that the voltage stability of the threephase output depends almost exclusively upon the regulation inherently provided by the single-phase alternating current supply. Additionally, protection output current limiting means provides overload protection for the output stages of the power converter against faults which may appear in the load causing it to demand excessive current levels.
Power conversion apparatus forming a preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is an electrical circuit diagram of the apparatus, and
Figure 2 is an electrical circuit diagram of a protective current limiter of the apparatus of
Figure 1.
The power conversion apparatus is illustrated in Figure 1 wherein the single phase alternating power to be converted is applied to terminals 1 and 150 (which may be a common terminal) and three-phase alternating power is produced on output terminals 126, 127, 155 and 156. Single phase alternating power is coupled to the terminal 1 , where it acts mainly to supply a phase and frequency reference signal for the apparatus, the terminal 1 being connected serially through a capacitor 2, a resistor 3, a junction 4, a resistor 5 and thence to ground. The junction 4 is connected by a coupling capacitor 6 to a junction 9 which is in turn coupled to ground through a diode 7 poled as indicated in the drawing. The junction 9 is also coupled by a parallel circuit made up of capacitor 8 and resistor 10 through ajunction 11 and a capacitor 12 to ground.. The circuit involving these elements forms a conventional 90" phase shifter for the input operating alternating signal, which in many installations will be 4001it, and serves to pass only a narrow band of frequencies about the desired centre operating frequency. The several circuit elements are selected for good stability in a severe environment so that the phase shift will be substantially constant particularly over the expected wide range of temperatures. The capacitor 12 serves to provide an a.c. ground path for all a.c. frequencies. The diode 7 limits the voltage at the junction 9 and protects an amplifier 39 during the transitory condition immediately following applicayion of power to the system where capacitors 2,6,8, 12, 33, and 37 draw large currents before reaching their steady state conditions.
The junction 9 of the phase shifter is connected by a coupling resistor 13 to one input 14 of the conventional voltage amplifier 39. Its second input 15 is directly coupled to the junction 11 through a junction 16, the junction 16 being connected to ground through a resistor 17 and through a resistor 50 to a source (not shown) of positive bias voltage normally connected to a terminal 51. The voltage at the terminal 51 may be +28 volts supplied directly by the aircraft generator. The conventional amplifier 39 has four additional terminals, one terminal 38 also being supplied with +28 volts, while another terminal 41 is coupled to ground.
A capacitor 40 used to suppress signals of frequency greater than the operating frequency is coupled in a conventional manner across the two remaining terminals of the amplifier 39. It will be understood that the amplifier 39 serves both as a voltage and as a gain controlled amplifier, as will be further described.
The output of the amplifier 39 is connected by a coupling resistor 42 to the input junction 43 of a current buffering amplifier stage employing transistors 44 and 47, these transistors being connected for operation in the conventional complementary Class B push-pull fashion. For this purpose, the junction 43 is coupled to the respective bases of the transistors 44,47. The collector electrode of the transistor 44 is normally coupled via a terminal 45 to a positive source (not shown), which may also be +28 volts d.c. while the collector electrode of the transistor 47 is connected to ground. The two emitter electrodes of the transistors 44,47 are coupled by a lead 46 to a common output junction 49 from which there are two branching electrical leads. For feedback and gain control purposes, the junction 49 is coupled via a lead 48 through a parallel circuit made up of a resistor 36 and a capacitor 37 and through a terminal 35 to the input 14 of the voltage amplifier 39. This is primarily a stabilizing direct current feedback through the resistor 36 and the capacitor 37, tending to cut off the transmission of signals of frequency above the operating frequency (above 400 Hz, for example).
The second branching electrical lead from the junction 49 is connected through an a.c.
coupling capacitor 60 to one end of a primary winding 64 of an isolation transformer 65, the other end of the primary winding 64 being grounded. A capacitor 62, coupled across the terminals 61,63 of the primary winding 64 is used to suppress undesired high frequencies, as before. The transformer 65 is supplied with a split secondary winding 66,68 which is centretapped at 67. The centre tap 67 is coupled between the series connected resistors 81 and 82 forming a voltage divider for biasing the bases of the transistors 93,99. The resistors 81, 82 are coupled between ground and a terminal 80 normally supplied with a bias voltage (say +28 volts d.c.) The transformer 65 acts as an isolating input to supply plus and minus 900 phase shifted a.c. signals to the bases of the transistors 93 and 99; these transistors are in a conventional push-pull power amplifier using stages of the socalled Darlington type. Input of undesired frequencies to the transistors 93, 99 above the operating frequency (say 400 Hz) is suppressed by a capacitor 84 coupled by leads 83,85 across the split secondary winding 66,68 of the transformer 65.
The amplifier stage associated with the transistor 93 and a further transistor 94 supplies an output at one end terminal 120 of the primary winding part 121 of a transformer 123. For this purpose, the secondary winding part 66 of the transformer 65 is coupled directly to the base of the transistor 93 whose collector electrode is normally coupled to a positive voltage source (e.g. +28 volts) at a terminal 91. The collector of the transistor 94 is also coupled to the voltage source at the terminal 91, its base to the emitter of the transistor 93, and its emitter to the end terminal 120 of the primary winding part 121. Additionally, the end terminal 120 is coupled through a diode 92, poled as shown for the purpose of preventing reverse biasing in the transistors 93,94 to the supply at the terminal 91. The secondary winding part 66 is also coupled via the lead 83 and the resistor 95 to the end terminal 120, the resistor 95 overcoming collector-tobase leakage effects in the transistors 93,94.
The power amplifier stage composed of the transistor 99 and a further transistor 100 (feeding the primary winding part 122 of the transformer 123) is analogous to that employing the transistors 93,94 and uses corresponding elements including a resistor 97, a terminal 98, and a diode 101. In this manner, the two quadrature sine wave voltages generated by the transformer 65 are current buffered by the power amplifiers associated with the transistors 93,94 and 99,100 and are applied to the opposite ends of the primary winding of the transformer 123.
The split secondary winding 124,125 of the transformer 123 is centre-tapped at 128, the tap 128 being supplied with. an appropriate a.c.
reference signal in view of the desired function of the output transformer system. To aid this operation, the single phase a.c. signal applied to the terminal 1 is also applied via the terminal 150 to one end of the grounded primary winding 151 ofa transformer 152. The transformer 152 has a centre-tapped secondary winding 153,154 and the outer end of the secondary winding portion 153 is coupled via a lead 129 to the centre tap 128 of the secondary winding 124,125 of the transformer 123. In this type of connection, the four output terminals 126, 127, 155, 156 supply the desired three-phase, four wire, grounded-neutral power. With the grounded terminal 155 neutral, 115 volt power signals are found on the remaining three terminals; the phase uA on the terminal 156 is at the same phase as the reference on the terminal 1, the phase uB on the terminal 126 is at 1200 relative to the reference, and the phase C on the terminal 27 is at 2400 relative to the reference. Although the terminal 155 is described and illustrated as a centre tap on the secondary winding of the transformer 152, the terminal 155 will in practice be off-centre in order to provide balance (in either magnitude or phase) between the three output phases cpA, B and cpC. It should also be noted that it is not essential to ground the terminal 155 but if a nongrounded neutral terminal is used, then it may be necessary to replace the components 2, 3 and 5 by means for referring to ground the input signal to the amplifier 39 such as by the use of a transformer or a differential operational amplifier, for example.
Again for stabilizing feedback purposes, the terminal 120 at the power output stage is coupled back to the input terminal 14 of the amplifier 39 via the junction 35. In particular, the a.c. signal at the terminal 120 is coupled via a lead 90 and a resistor 52 to a junction 34 and from that junction through a series circuit formed by a resistor 32 and the blocking capacitor 33 to the terminals 35,14. Thus, an a.c. feedback into the amplifier 39 is provided for gain control and stabilization purposes. A positive bias voltage (say + 28 volts d.c.) may be coupled from a terminal 30 through a resis tor 31, the resistors 31 and 52 beneficially setting up a bias at the junction 34 so that the direct voltage levels on both plates of the capacitor 33 are substantially equal.
As previously noted, the necessary phase stability of the three phase output power is ensured by a selection of temperature stable components for use in the input phase shifter network. Precise voltage tracking of the input a.c. reference signal on the junction 1 is also achieved. The input alternating voltage level is used as a reference, since the voltage regulation of the aircraft power supply is normally a quite adequate standard. To ensure that the voltage stability of the three-phase output depends almost exclusively on alternating voltage input variations at the terminals 1,150 the automatic gain control feedback loops including the components 36,37 and 32,33 are provided, these functioning respectively as d.c. and a.c.
feedback networks, allowing compensation of the output voltage level and its substantial correction by the amplifier 39.
In Figure 1 , protection of the power conversion apparatus against short circuits or other output current overloads is provided by a current limiter 29 whose output is coupled to the junction 35 and thereby to the input junction 14 of the gain controlling amplifier 39. The controlling input at a terminal 28 of the protective current limiter 29 is derived at a terminal 119 at the mid-point of the transformer input winding 121,122. This mid-point is coupled across a sensor resistor 96 to ground. The limiter 29 serves to monitor the voltage developed across the sensor resistor 96, thereby detecting any demand for current at the output of the converter exceeding its safe capability.
Thereupon, the power converter is forced into a safe operating or stand-by mode. As a consequence, the B and uC outputs at the respective terminals 126 and 127 derive energy substantially only from the transformer 152. The converter remains in this stand-by mode until recycled after the excessive load is removed, the energy at the terminals 1 and 150 having been removed and then having been re-supplied.
Referring now to Figure 2, the current limiter 29 will be considered in greater detail.
Its normal input at terminal 119 consists of a direct current component and the full wave rectified signal (derived, say, from 400 Hz) developed across the sensor resistor 96. A d.c.
blocking series capacitor 160 allows only the alternating signals to flow into the voltage divider composed of resistors 161,170, the resistor 170 being coupled to the terminal 16 of
Figure 1. The same terminal 174 is connected through a resistor 173 and a junction 172 to one input terminal of a conventional operational amplifier 166, its second input terminal being coupled at a junction l62 between the resistors 161,170 for receipt of a.c. signals passed by the blocking capacitor 160.
Thus, the voltage developed at the junction 162 is applied to one input of the operational amplifier 166, which amplifier is connected in the usual manner to permit it to operate as a conventional voltage comparator. A second input to the voltage comparator, on junction 172, is derived from positive feedback current components, formed by the action of a resistor 179 and Zener diode 178 and found at an output junction 181. The control output signal of the voltage comparator including the amplifier 166 is coupled through junction 175, diode 176,junction 177, and resistor 180 to the junction 181. A diode 165 is coupled between the junctions 162 and 175. The positive feedback elements 165,176,164 and 163 serve to provide positive rectification and filtering or smoothing of the differential input at the input terminals 162 and 172 of the voltage comparator including the amplifier 166. The consequent positive unidirectional signal at the junction 177 is further filtered by the resistor-capacitor circuit provided by components 180 to 182. The capacitor 171 acts to suppress high frequency signals. In this manner, the low noise unidirectional signal at the junction 181 represents a reliable measure of the current level demanded at the output terminals 126,127 of Figure 1, this signal being coupled through the Zener diode 183 and the resistor 184 to the power converter feedback junction 35.
When an abnormality appears in the load fed by the power converter and an excessive current magnitude is demanded of it, the voltage level at the junction 181 increases accordingly.
When the output current sensed by the monitor resistor 96 becomes excessive, the unidirectional voltage level at the junction 181 rises above a predetermined level (say, of +5.6 volts) and the Zener diode 178 breaks down. As a consequence, there is heavy current flow through the resistor 179 and the diode 178.
This event greatly unbalances the differential input at the terminals 162,172 to the voltage comparator including amplifier 166, causing its output to latch to, say, +28 volts. The amplifier 166 acts as a normal gain amplifier with threshold positive feedback latch-up; the amplifier 166 acts like a normal gain amplifier until its output exceeds a predetermined voltage level, whereupon overwhelming positive feedback by the conduction of the Zener diode 178 causes the output of the amplifier to saturate or to latch up at its positive supply voltage level (+28 volts). The signal at the junction 181 instantaneously increases above a predetermined voltage level (say, +6.2 volts) with the consequent break down of the Zener diode 183. Now, a large current must flow through the Zener diode 183 and the resistor 184 and into the junction 35 to the junction 14 and thence into the amplifier 39 of Figure 1. The output of the amplifier 39 is forced to ground potential because of its hard-over input unbalance; thus, with.no alternating current signals available at the output of the operational
amplifier 39 and with the junction 49 being
placed at ground potential, all succeeding stages
of the power converter are effectively biased
into a non-operating mode. Thus, all transistors
are protected from the disturbance. Only by removal of the source of excessive current demand by the load and by removal and re-supply
of the input direct current to the amplifier 166 will the overload protective circuit be switched
from its dominating protective condition. With
respect to Figures 1 and 2, it will be understood that in the usual aircraft installation, the unidirectional energization voltages applied in
Figures 1 and 2 at the terminals 30,38,45,51, 91,98 and 174 will normally be supplied from the aircraft primary direct current supply. For simplicity, the apparatus does not utilize a negative supply for operational amplifiers 39,
166, but operates with +28 volts and ground connected to the amplified supply terminals.
The terminals 9,11 14,16,34,35,43, 49 and 174 are therefore biased at +14 volts with respect to ground (supplies not shown). However, the circuit may be operated in the more usual manner, as will be understood by those skilled in the art, with both positive and negative power supplies coupled to the amplifiers 39,
166 (+15 volts).
Accordingly, it is seen that the apparatus provides a compact and efficient active arrangement for permitting aircraft instruments and controls originally intended to operate from three-phase aircraft power supplies to operate equally well with aircraft power supply systems generating direct current power and only limited power levels of single-phase alternating current. Use of a portion of the direct current power for quadrature power alternating current signal generation advantageously reduces the demand placed by the apparatus upon the relatively low power single-phase generator.
Further, use of the aircraft single-phase power output as a phase and frequency reference signal makes unnecessary the phase synchronizing elements or tuned circuits required inònven- tional static inverters and their attendant cost and size disadvantages. Size and cost factors are further reduced, since integratedcircuit packaging techniques are readily applied in designing the apparatus.
In fact, the relatively small size attained by use of the apparatus permits it to be incorporated directly into an instrument or control whose three-phase output it is to employ. The apparatus reduces the demand placed upon the relatively low level aircraft single-phase power by augmenting it with direct current energy.
Size and cost are further minimized by using the single-phase power as a reference for quadrature signal generation and alsoms a direct contributor to the final three-phase power level with corresponding similar input and output levels. Apparatus according to the present invention need occupy only a third of the volume required for a static inverter at a cost as low as
about fifteen per cent of the cost of such an inverter.
While the apparatus is a useful entity in itself as described in connection with Figure 1, its reliability and utility are greatly enhanced when the protective circuit of Figure 2 is also employed. The protective circuit operates to
eliminate damage to the power converter when excessive overload current is inadvertently drawn for any cause. Thus, the power converter is protected from failures occurring in normal operation and also from wiring connection errors made in the aircraft during initial assembly or repair. Furthermore, the protective circuit operates also to protect itself by forcing the operator to clear the offending defect before the system can again be recycled into normal operation.
The described embodiment of the invention thus provides an efficient and compact arrangement permitting aircraft instrumentation and control systems originally designed to operate primarily from three-phase power supplies to operate successfully and safely with aircraft power supplies yielding considerable direct current power but only limited power levels of single-phase alternating current.
Whilst in the described embodiment the phase output signal uA is taken from the secondary winding 153 of the transformer 152, it can be taken direct from the primary winding
151 of that transformer if the isolation provided by the secondary is not required.
WHAT WE CLAIM IS:
1. Power conversion apparatus intended to be responsive jointly to aircraft single-phase alternating current power supply means and to aircraft direct current power supply means for generating three-phase alternating current aboard an aircraft of substantially greater power level than the power level of said aircraft single-phase power supply means, comprising: network means for shifting the phase of said single phase alternating current by substantially ninety degrees, first amplifier means having an input responsive to said network means, pushpull power amplifier means responsive to said first amplifier means, first transformer means having first primary and first secondary means, said first primary means being responsive to said push-pull power amplifier means, said first secondary means having first tap means which are at the centre of the first secondary means, second transformer means having second primary and second secondary means, said second primary means being responsive to said single phase alternating current, said first tap means being coupled to a first end of said second secondary means, said second transformer means providing neutral output coupling means and a first phase output signal, a first end of said first secondary means providing a second phase output signal, anda second end of said first secondary means providing a third phase output signal.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (20)
- **WARNING** start of CLMS field may overlap end of DESC **.amplifier 39 and with the junction 49 being placed at ground potential, all succeeding stages of the power converter are effectively biased into a non-operating mode. Thus, all transistors are protected from the disturbance. Only by removal of the source of excessive current demand by the load and by removal and re-supply of the input direct current to the amplifier 166 will the overload protective circuit be switched from its dominating protective condition. With respect to Figures 1 and 2, it will be understood that in the usual aircraft installation, the unidirectional energization voltages applied in Figures 1 and 2 at the terminals 30,38,45,51, 91,98 and 174 will normally be supplied from the aircraft primary direct current supply. For simplicity, the apparatus does not utilize a negative supply for operational amplifiers 39, 166, but operates with +28 volts and ground connected to the amplified supply terminals.The terminals 9,11 14,16,34,35,43, 49 and174 are therefore biased at +14 volts with respect to ground (supplies not shown). However, the circuit may be operated in the more usual manner, as will be understood by those skilled in the art, with both positive and negative power supplies coupled to the amplifiers 39,166 (+15 volts).Accordingly, it is seen that the apparatus provides a compact and efficient active arrangement for permitting aircraft instruments and controls originally intended to operate from three-phase aircraft power supplies to operate equally well with aircraft power supply systems generating direct current power and only limited power levels of single-phase alternating current. Use of a portion of the direct current power for quadrature power alternating current signal generation advantageously reduces the demand placed by the apparatus upon the relatively low power single-phase generator.Further, use of the aircraft single-phase power output as a phase and frequency reference signal makes unnecessary the phase synchronizing elements or tuned circuits required inònven- tional static inverters and their attendant cost and size disadvantages. Size and cost factors are further reduced, since integratedcircuit packaging techniques are readily applied in designing the apparatus.In fact, the relatively small size attained by use of the apparatus permits it to be incorporated directly into an instrument or control whose three-phase output it is to employ. The apparatus reduces the demand placed upon the relatively low level aircraft single-phase power by augmenting it with direct current energy.Size and cost are further minimized by using the single-phase power as a reference for quadrature signal generation and alsoms a direct contributor to the final three-phase power level with corresponding similar input and output levels. Apparatus according to the present invention need occupy only a third of the volume required for a static inverter at a cost as low as about fifteen per cent of the cost of such an inverter.While the apparatus is a useful entity in itself as described in connection with Figure 1, its reliability and utility are greatly enhanced when the protective circuit of Figure 2 is also employed. The protective circuit operates to eliminate damage to the power converter when excessive overload current is inadvertently drawn for any cause. Thus, the power converter is protected from failures occurring in normal operation and also from wiring connection errors made in the aircraft during initial assembly or repair. Furthermore, the protective circuit operates also to protect itself by forcing the operator to clear the offending defect before the system can again be recycled into normal operation.The described embodiment of the invention thus provides an efficient and compact arrangement permitting aircraft instrumentation and control systems originally designed to operate primarily from three-phase power supplies to operate successfully and safely with aircraft power supplies yielding considerable direct current power but only limited power levels of single-phase alternating current.Whilst in the described embodiment the phase output signal uA is taken from the secondary winding 153 of the transformer 152, it can be taken direct from the primary winding151 of that transformer if the isolation provided by the secondary is not required.WHAT WE CLAIM IS: 1. Power conversion apparatus intended to be responsive jointly to aircraft single-phase alternating current power supply means and to aircraft direct current power supply means for generating three-phase alternating current aboard an aircraft of substantially greater power level than the power level of said aircraft single-phase power supply means, comprising: network means for shifting the phase of said single phase alternating current by substantially ninety degrees, first amplifier means having an input responsive to said network means, pushpull power amplifier means responsive to said first amplifier means, first transformer means having first primary and first secondary means, said first primary means being responsive to said push-pull power amplifier means, said first secondary means having first tap means which are at the centre of the first secondary means, second transformer means having second primary and second secondary means, said second primary means being responsive to said single phase alternating current, said first tap means being coupled to a first end of said second secondary means, said second transformer means providing neutral output coupling means and a first phase output signal, a first end of said first secondary means providing a second phase output signal, anda second end of said first secondary means providing a third phase output signal.
- 2. Apparatus according to Claim 1, whereinthe second secondary means has second tap means providing the neutral output coupling means and has a second end providing the first phase output signal.
- 3. Apparatus according to Claim 1, wherein the first phase output signal is derived direct from the second primary means of the second transformer means.
- 4. Apparatus according to any of Claims 1 to 3 wherein the first and second transformer means have such polarities and are so electrically interconnected that, with respect to the phase of said single phase alternating current the phase angle of the first phase output signal is substantially zero degrees, the phase angle of the second phase output signal is substantially one hundred and twenty degrees, and the phase angle of the third phase output signal is substantially two hundred and forty degrees.
- 5. Apparatus according to any of the preceding claims and further including first feedback means responsive to the first amplifier means for additionally coupling a direct current gain controlling signal to the input of the first amplifier means.
- 6. Apparatus according to Claim 5 and further including inductive isolation means for coupling only alternating current from the first amplifier means into the push-pull power amplifier means.
- 7. Apparatus according to Claim 6 and further including second feedback means responsive to the push-pull power amplifier means for additionally coupling an alternating current gaincontrolling signal to the input of the first amplifier means.
- 8. Apparatus according to any of the preceding claims wherein at least the first amplifier means and the push-pull power amplifier means are adapted for energization by the direct current power supply means of the aircraft.
- 9. Apparatus according to Claims 6 and 8 wherein the inductive isolation means and the push-pull power amplifier means cooperate to supply one hundred and eighty degree out of phase versions of the ninety degree phase shifted output of the network means to the ends of the first primary means.
- 10. Power conversion apparatus intended to be responsive jointly to aircraft single phase alternating current power supply means and to aircraft direct current power supply means for generating three-phase alternating current aboard an aircraft of substantially greater power level than the maximum power level of said aircraft single phase power supplyJneans, the apparatus comprising network means for shifting the phase of the single phase alternating current by substantially ninety degrees, first amplifier means having signal input means responsive to the network means, push-pull power amplifier means responsive to the first amplifier means, output transformer means having two secondary winding means for providing discrete three-phase output currents, the output transformer means having first and second primary winding means, the first primary winding means being responsive to the push-pull power amplifier means, and the second primary winding means being responsive to the single phase alternating current, impedance means coupled to the centre tap means for sensing the level of the three-phase output currents and comparing the latter with a predetermined safe value, and limiter means responsive to the impedance means for generating a control signal only when the predetermined safe value is exceeded, the signal output means thereuponbeing responsive to the limiter means control signal by reducing the output of the first amplifier means substantially to zero.
- 11. Apparatus according to Claim 10 and further including first feedback means responsive to the first amplifier means for additionally coupling a direct current gaincontrolling signal to the signal input means.
- 12. Apparatus according to Claim 10 or 11 and further including isolation means for coupling only alternating current from the first amplifier means into the push-pull power amplifier means.
- 13. Apparatus according to Claim 11 and further including second feedback means responsive to the push-pull power amplifier means for additionally coupling an alternating current gaincontrolling signal to the signal input means.
- 14. Apparatus according to any of Claims 10 to 13, wherein the limiter means comprise capacitive blocking means coupled to the centre tap means at the impedance means, voltage divider means having intermediate tap means and one end coupled to the capacitive blocking means, unidirectional voltage source means coupled to the voltage divider means opposite the capacitive blocking means, voltage comparator means having first and second input means respectively responsive to signals at the intermediate tap means of the voltage divider means and to said unidirectional voltage source means and having output means, and first non-linear circuit means for coupling said voltage comparator means output means to the second signal input means.
- 15. Apparatus according to Claim 14, wherein the first non-linear circuit means include series connected diode means and resistor means.
- 16. Apparatus according to Claim 14 or 15 and additionally including second non-linear circuit means coupled to the voltage comparator means first input means and between the voltage comparator means output means and the first non-linear circuit means.
- 17. Apparatus according to Claim 16, wherein the second non-linear circuit means include series connected diode means and resistor means.
- 18. Apparatus according to Claim 16 or 17 further including rectifying positive feedback coupling means for coupling the voltage comparator means output means to the voltage comparator means first input means.
- 19. Apparatus according to any of Claims 16 to 18 wherein the first and second nonlinear circuit means are so arranged and cooperatively operated that an excessive voltage sensed across the impedance means causes the second non-linear circuit means to break down, unbalancing the input to the voltage comparator means and consequently causing the first non-linear circuit means to break down, whereupon the output of the first amplifier means is reduced substantially to zero for protecting the power conversion apparatus from damage.
- 20. Power conversion apparatus constituted and arranged substantially as herein particularly described with reference to the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/779,214 US4103325A (en) | 1977-03-18 | 1977-03-18 | Aircraft power and phase converter |
| US05/779,421 US4100596A (en) | 1977-03-18 | 1977-03-18 | Protected aircraft power and phase converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1588303A true GB1588303A (en) | 1981-04-23 |
Family
ID=27119552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8730/78A Expired GB1588303A (en) | 1977-03-18 | 1978-03-06 | Power conversion apparatus for aircraft |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE2811479A1 (en) |
| FR (1) | FR2384379A1 (en) |
| GB (1) | GB1588303A (en) |
| IT (1) | IT1155891B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007063494A1 (en) * | 2005-12-02 | 2007-06-07 | Nxp B.V. | Low noise amplifier |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1543291A (en) * | 1965-12-23 | 1968-10-25 | Varo | High-frequency, phase-demodulated DC to AC bridge converter |
-
1978
- 1978-03-06 GB GB8730/78A patent/GB1588303A/en not_active Expired
- 1978-03-16 DE DE19782811479 patent/DE2811479A1/en not_active Withdrawn
- 1978-03-17 FR FR7807877A patent/FR2384379A1/en active Granted
- 1978-03-17 IT IT48488/78A patent/IT1155891B/en active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007063494A1 (en) * | 2005-12-02 | 2007-06-07 | Nxp B.V. | Low noise amplifier |
| US8149053B2 (en) | 2005-12-02 | 2012-04-03 | Nxp B.V. | Low noise amplifier |
| CN103956977A (en) * | 2005-12-02 | 2014-07-30 | Nxp股份有限公司 | Low noise amplifier |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2384379B1 (en) | 1983-02-18 |
| IT1155891B (en) | 1987-01-28 |
| IT7848488A0 (en) | 1978-03-17 |
| FR2384379A1 (en) | 1978-10-13 |
| DE2811479A1 (en) | 1978-09-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |