RU2305888C1 - Pulse load power supply - Google Patents

Abstract

FIELD: designing power supplies incorporating pulse load and energy-storage capacitor.

SUBSTANCE: proposed device has nonadjustable multiphase unsteady-frequency magnetoelectric AC voltage generator 1 feeding main steady-frequency load and pulse load incorporating storage capacitor 7; voltage across storage capacitor 7 is shaped in the form of gradually rising curve for which purpose phase leads of generator 1 are connected to storage capacitor 7 in series one after another until desired voltage level Uo fixed by comparison unit 9 is attained across this capacitor, whereupon all phase leads are disconnected simultaneously. Control unit 8 generates instruction for periodic connection of one of phase leads of voltage generator 1 to maintain voltage at desired level Uo up to end of load connection period (with capacitor partially discharged to minimal admissible level). Additional capacitors 5 are connected in parallel with windings of single-phase transformers 4.

EFFECT: provision for dispensing with voltage modulation and for maintaining optimal mass and size of device.

1 cl, 2 dwg

Description

The invention relates to the field of electrical engineering and can be used in the design of power supplies of pulse loads with capacitive energy storage.

Known power supply systems of pulsed loads containing a multiphase voltage generator with a main load of a stable frequency and a capacitive storage connected to a pulsed consumer of electricity (1).

In order to reduce the influence of the pulse load on the shape and magnitude of the generator voltage supplying it, i.e. to reduce the modulation of the generator supply voltage, special chargers connected to a capacitive energy storage device are used. However, these devices are complex and require special construction of the power part of the system, which generally complicates the design and leads to a decrease in reliability and deterioration of overall dimensions.

Closest to this invention, the technical solution is a centralized power supply with a pulse load, containing an unregulated magnetoelectric alternating current generator of unstable frequency, connected to the main load and the pulse load connected to a storage capacitor having a special charger, and the power of the pulse load is comparable with the power of the generator (2). This device is inherent to all of the above disadvantages of the device (1).

A positive result that can be achieved using this invention is to increase reliability and improve overall dimensions by simplifying the design.

A positive result is achieved in that in a pulsed load power supply containing an unregulated multiphase unstable frequency voltage generator, the power of which is comparable to the power of a pulsed load, each of the M phases of the voltage generator is connected to the corresponding input of the unstable frequency voltage converter into a stable and primary winding of the corresponding single-phase transformer the secondary winding of which is connected to the input of the rectifier, connected to the storage con the output terminals of which serve to connect the pulser to the pulser (2), the indicated connection of each of the M phases of the voltage generator with the primary winding of the corresponding single-phase transformer is carried out through a controlled key corresponding to this phase, the control input of which is connected to the output of the control unit, the input of which is connected to the output of the unit comparison, measuring input connected to the conclusions of the storage capacitor, while the control unit is made providing in each of the periods under pulse voltage generation, the voltage across the storage capacitor by sequentially connecting the phases of the voltage generator to the storage capacitor until it reaches the specified voltage level with the subsequent simultaneous disconnection of all phases, while maintaining the ability to periodically connect one of the phases while reducing the specified voltage level on the storage capacitor, parallel to the primary winding of each single-phase transformer connected corresponding additional capacitor capacitance C is selected from the condition

, где

where

S _f (W) - power of the corresponding phase of the pulse load in the nominal mode;

M is the number of phases of the voltage generator;

ω (Hz) is the frequency of the output voltage of the voltage generator;

U _g (V) is the operating voltage of the generator;

K = from 0.5 to 1.5 is a coefficient depending on the frequency of change of the generator speed and the range of variation of its main load connected to the output of the converter of unstable frequency to stable during the period of connecting the pulse load.

Figure 1 presents the electrical circuit of the device.

Figure 2 presents the timing diagrams of the operation of the device.

The device (Figure 1) contains an unregulated, magnetoelectric, multiphase voltage generator 1 of an alternating current voltage of an unstable frequency, operating, for example, from an aircraft engine with a variable speed (n _var ). Each of the M phases of the voltage generator 1 is connected to the corresponding input of the converter of unstable frequency to stable 2, the output terminals of which serve to connect the main load (phases A, B, C). Each of the M phases of the generator 1 is also connected via a controlled key 3 corresponding to this phase to the primary winding (w ₁ ) of the corresponding single-phase transformer 4, in parallel with which the corresponding additional capacitor 5 is connected. Secondary windings (w ₂ ) of the single-phase transformers 4 are connected to the input of the rectifier 6 high voltage, the output terminals of which are connected to the storage capacitor 7, are used to connect a pulse load. The control input of each of the controlled keys 3 is connected to the corresponding output of the control unit 8, the input of which is connected to the output of the comparison unit 9, by the measuring input connected to the terminals of the storage capacitor 7. The control unit 8 is configured to provide voltage generation on the storage capacitor in each of the periods of the pulse load connection 7 by sequentially connecting the phases of the voltage generator 1 to the storage capacitor 7 until it reaches the specified voltage level with after by simultaneously disconnecting all phases, while maintaining the ability to periodically connect one of the phases while lowering the specified voltage level (U _o ) on the storage capacitor 7 to the minimum allowable (U _{o min} ).

The device operates as follows.

When the device is turned on, the voltage of a stable frequency alternator 1 (f = Const) is supplied through an unstable to stable 2 frequency converter to the output terminals used to connect the main load. The AC voltage of an unstable frequency through the controlled keys 3, the windings of the corresponding single-phase transformers 4 and the high-voltage rectifier 6 is supplied to the output terminals, which are used to connect a pulsed load with a capacitive energy storage (capacitor 7). Connecting a pulsed load to the supply generator causes a modulation of the supply voltage, the value of which depends on the ratio of the power of the generator 1 and the charging power of the storage capacitor 7. To exclude modulation, the voltage on the capacitor 7 is formed in the form of a smoothly growing curve, for which the phases of the generator 1 are connected to the capacitor 7 in series one after another to achieve a predetermined level thereon voltage (U _o), fixed by the comparison unit 9. at this stage, the capacitor charge current has the minimum the increment ix amplitude.

When the voltage on the capacitor of a given level U _{o is} reached, the control unit 8, upon a signal from the output of the comparison unit 9, generates a command to simultaneously disconnect all previously used phases of the generator (opening the corresponding controlled keys 3). Ideally, in which there are no discharge circuits of the capacitor 7, caused, for example, by leakage currents through voltage dividers, the level U _o will remain until the end of the load connection period, after which the capacitor 7 is discharged and a pause is formed.

In the real version, the capacitor 7 is partially discharged to the level of the minimum allowable voltage, which is fixed by the comparison unit 9. In this case, the control unit generates a command to periodically connect one of the phases of the voltage generator 1 to the capacitor (to raise the voltage to a given level U _o and maintain it up to end of load connection period). The comparison node 9 has a threshold characteristic, providing operation according to the value of the specified voltage U _o and the minimum allowable U _{o min} .

Connecting additional capacitors 5 to the primary windings of single-phase transformers 4 further reduces the modulation of the voltage of the generator 1, which is illustrated by the timing diagrams shown in Figure 2, where:

10 - static external characteristic of the generator 1 with a linear load with Cosφ≤1 ind. in steady state before connecting additional capacitors 5;

11 - static external characteristic of the generator 1 after connecting the capacitors 5 with a linear load with Cosφ≤1 capacitance.

Until the moment of impulse load connection, the generator 1 is in a state determined by the operating point 10-1 (Un, In). When a pulse load is connected, the voltage of the generator 1 changes by ΔU imp and the operating point moves to point 10-2, while the current changes by ΔI imp.

In case of incomplete compensation or overcompensation caused, for example, by changing the frequency of the voltage generator 1, the magnitude of the pulse load, the influence of phases unloaded by the pulse load, the voltage of the generator 1 may be in the circle of point 11-1. In this case, the voltage change when the load is connected will always be less than ΔU imp in the absence of compensation.

The choice of the magnitude of each of the additional capacitors 5 is determined by the condition that the resonant frequency of the circuit, consisting of an additional capacitor and the leakage inductance of the generator winding, is required to exceed the minimum frequency of the generator 1. The value of the capacitance C of the additional capacitor is selected from the condition:

, где

where

S _Ф (W) - power of the corresponding phase of the pulse load in the nominal mode;

M is the number of phases of the voltage generator;

ω (Hz) is the frequency of the output voltage of the voltage generator;

U _g (V) is the operating voltage of the generator;

K = from 0.5 to 1.5 is a coefficient depending on the frequency of change of the generator speed and the range of variation of its main load connected to the output of the converter of unstable frequency to stable during the period of connecting the pulse load.

This device provides the exclusion of voltage modulation of the supply alternating current generator when connecting a pulsed load, maintaining optimal weight and size indicators, which makes it preferable when designing power supply systems used, for example, in aircraft construction.

Information sources

1. Bulatov O.G. and others. "Semiconductor chargers of capacitive energy storage." M., "Radio and Communications, 1986, p.41-51.

2. Mizyurin S.R. and others. "Calculation of synchronous generators and transformers with a pulsed load on a capacitive energy storage." M., 1974, p. 48.

Claims (1)

An impulse load power supply containing an unregulated multiphase voltage generator of unstable frequency, the power of which is comparable with the power of a pulse load, each of the M phases of the voltage generator is connected to the corresponding input of the voltage converter of unstable frequency into a stable and primary winding of the corresponding single-phase transformer, the secondary winding of which is connected to the input rectifiers connected to a storage capacitor, the output terminals of which serve for connecting a pulsed load, characterized in that the indicated connection of each of the M phases of the voltage generator with the primary winding of the corresponding single-phase transformer is made through a controlled key corresponding to this phase, the control input of which is connected to the output of the control unit, the input of which is connected to the output of the comparison unit, by the measuring input of the connected to the terminals of the storage capacitor and having a threshold characteristic providing operation at a predetermined value and minimum U _o allowable U _min voltage, wherein the control unit is provided in each of the periods of connection of the pulse load voltage formation on the storage capacitor by sequentially connecting a voltage generator phases to the storage capacitor to achieve thereon a predetermined voltage level, followed by the simultaneous disconnection of all phases, while maintaining the possibility periodic connection of one of the phases while reducing the specified voltage level on the storage capacitor, and in parallel no primary winding of each single-phase transformer connected respective additional capacitor capacitance C is chosen from the condition:

, where S _f (W) is the power of the corresponding phase of the pulse load in the nominal mode; M is the number of phases of the voltage generator; ω (Hz) is the frequency of the output voltage of the voltage generator; U _g (B) is the effective voltage of the generator; K = from 0.5 to 1.5 - coefficient.

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