RU2337452C1 - Method of load supply with direct current in composition of autonomous system of earth power supply and autonomous power supply system for its implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: suggested invention is related to electrotechnical industry and may be used in creation and operation of autonomous power supply systems of artificial Earth satellites (AES). Method is suggested for load supply with DC current in composition of autonomous system of artificial Earth satellite power supply from sun battery and set of "n" secondary sources of power supply - lithium-ion accumulator batteries, which consists in stabilisation of voltage in load, performance of charge-discharge cycles through individual charge and discharge transducers, control of accumulator batteries voltage and limitation of charge and discharge of accumulator batteries by preset values of charge and discharge voltage. Besides, autonomous system of power supply is suggested, which contains sun battery connected to load via stabilised voltage transducer, "n" accumulator batteries connected via "n" charge transducers to sun battery, and via "n" discharge transducers to the load, at that every accumulator battery consists of "m" serially connected accumulators that have opening contacts of relay in serial circuit and closing contacts of relay that embrace every accumulator together with its serially connected opening contact. Objective of the present invention is increase of efficiency of accumulator batteries usage and specific energetic characteristics of autonomous power supply system. Technical result is achieved by the fact that whenever voltage of any accumulator battery drops below preset bottom value in the process of discharge, this voltage is stabilised in it. At that in autonomous power supply system additionally voltage stabiliser is introduced, which is connected with its inlet to accumulator batteries via "n" untying, in direction of discharge current flow, devices, and with its outlet connected to accumulator batteries via "n" untying, in direction of charge current flow, devices. Substance of suggested solution is explained in the drawing, where in fig. 1 functional diagram of autonomous power supply system is pictured, which explains operation according to suggested method.

EFFECT: provision of accumulator battery voltage stabilisation after achievement of preset bottom value.

2 cl, 1 dwg

Description

The invention relates to the electrical industry and can be used to create and operate autonomous power systems for artificial Earth satellites (AES).

Currently, in space technology, the process of creating connected Earth satellites with a large output power (10-25 kW) and a long (10-15 years) resource is underway.

This problem, in relation to an autonomous satellite power supply system, can only be successfully solved if solar panels are used on the basis of multi-stage gallium arsenide photoconverters, lithium-ion batteries and an automation system that harmonizes the operation of these sources with a stable voltage at the inputs of electricity consumers.

Known methods for supplying a load with a constant, stable voltage, implemented by the DC load power systems described in "Spacecraft Power Supply Systems, Novosibirsk, VO" Nauka ", 1994" [1].

Known methods of supplying the load with direct current, provide for voltage stabilization from a primary source of limited power (solar battery) on the load with stabilized converters of various types.

There is a known method of supplying a load with direct current, which involves increasing the capacity of an autonomous power supply system by installing additional modules to ensure their uniform loading (see [1] chapter 2, items 2, 5).

The closest technical solution is the DC load power supply method implemented by the "Autonomous power supply system of an artificial Earth satellite" (patent No. 2059988 dated May 10, 1996), which is selected as a prototype.

Known methods and autonomous systems provide for the modular construction of secondary sources of electricity with individual charging and discharge converters.

A common drawback of the known methods and autonomous systems is that they do not allow the full use of secondary sources based on lithium-ion batteries and reduce the specific energy-weight characteristics of an autonomous satellite power supply system.

This is due to the following operational features of lithium-ion batteries.

Unlike nickel-hydrogen storage batteries widely used in space technology today, lithium-ion batteries (more precisely, their batteries) have a strict limitation on the maximum charging and minimum discharge voltages (see “Li-ion batteries, Krasnoyarsk, IPC Platinum,” 2002 ”[2]).

However, to ensure a long service life of the battery (10 years or more), it is necessary to limit the depth of its discharge, which depends on several operational factors. The most important of them: the number of charge-discharge cycles, battery temperature, charge and discharge currents.

From the practice of designing and operating modern satellites, the maximum value of the discharge depth is, for example, for geostationary satellites (100 cycles per year, and the service life of 10-15 years) - 0.7-0.8 of the nominal capacity. This fact allows the operation of lithium-ion batteries to be guided by the discharge voltage of the entire battery, and the appearance in this case of a battery with a voltage equal to its lower (critical) value indicates a malfunction of this battery. Such a battery is to be excluded from the battery serial circuit by opening its opening relay contact and closing its closing relay contact.

In case of degradation of the capacitive characteristics of any battery during the operation of the satellite and this battery reaches the lower voltage level during the discharge by a large current, the residual energy in it cannot be used, since further discharge by the current mode is unacceptable. As a result, the ability of a satellite to fulfill its target functions may be limited.

The task of the invention is to increase the efficiency of using batteries and the specific energy characteristics of an autonomous power supply system.

The problem is achieved in that when a battery reaches a predetermined lower value during the discharge process, this voltage is stabilized on it.

At the same time, a voltage stabilizer is additionally introduced into the autonomous power supply system, connected to the batteries through the “n” decoupling devices in the direction of the discharge current, and devices connected to the batteries through the “n” decoupling devices in the direction of the charging current.

Indeed, the termination of the discharge of the battery when it reaches a voltage equal to the lower predetermined value does not allow full use of the available capacity in it. When stabilizing the voltage on this battery, its discharge will continue with the incident current, which will make full use of its residual capacity, respectively, increasing the efficiency of use of this battery.

In addition, in an autonomous power supply system with such a technology, the discharge converter of a completely discharged battery remains loaded, including the need to not increase the power of each discharge converter to ensure load consumption when any (some) battery is fully discharged batteries. This increases the specific energy characteristics of an autonomous power supply system.

The drawing shows a functional diagram of an autonomous satellite power supply system that implements the claimed invention.

The self-contained satellite power supply system contains a solar battery 1 connected to load 2 through a voltage converter 3, rechargeable batteries 4 ₁ -4 _n connected through charging converters 5 ₁ -5 _n to the solar battery 1, and through discharge converters 6 ₁ -6 _n to input to the output filter of the voltage converter 3.

At the same time, load 2 in its composition contains an on-board computer, a telemetry system and a command-measuring radio line.

Rechargeable batteries 4 ₁ -4 _n consist of series-connected accumulators, closing and opening relay contacts (positions are not indicated in the drawing).

In parallel with the batteries 4 ₁ -4 _n , control devices for batteries 7 ₁ -7 _n connected to the batteries 4 ₁ -4 _{n are} connected to monitor the voltage and temperature of the battery and its batteries, and control the closing and opening relay contacts, and output with load 2.

Measuring shunts 8 ₁ -8 _{n are} installed in the charge-discharge circuit of the batteries.

Charging converters 5 ₁ -5 _n consist of a control key 9, controlled by a control circuit 10, a voltage boost unit made on a transformer Tr, transistors T1 and T2, and a rectifier on diodes D1 and D2.

Bit converters 6 ₁ -6 _n consist of a control key 11, controlled by a control circuit 12.

The voltage converter 3 consists of a control key 13, controlled by a control circuit 14, an input filter C1 and an output filter on a diode D, inductor L and capacitor C.

Control schemes: 10 charging converters 5 ₁ -5 _n , 12-bit converters 6 ₁ -6 _n , 14 - voltage converters 3, are made in the form of pulse-width modulators, connected to stabilized voltage buses by an input. The control circuit 10 of the charging converters 5 ₁ -5 _{n are} additionally associated with the measuring shunts 8 ₁ -8 _n and load 2.

In addition, the self-contained satellite power supply system includes a voltage stabilizer 15, connected by an input to the batteries 4 ₁ -4 _n through the “n” decoupling devices 16 ₁ -16 _n , in the direction of the flow of discharge current, and the output to the batteries through “n” decoupling devices, in the direction of flow of the charging current, 17 ₁ -17 _n , connected to control the load (on-board computer, telemetry system and command and measurement radio line). Decoupling devices in the direction of flow of the discharge current 16 ₁ -16 _n and the charging current 17 ₁ -17 _n are diode or transistor circuits.

The device operates as follows. During operation, rechargeable batteries 4 ₁ -4 _n work mainly in storage mode and periodic recharges from the solar battery 1 through charging converters 5 ₁ -5 _n . This mode of operation allows you to keep them in constant readiness in case of emergency (loss of satellite orientation on the Sun) or when passing regular shadow areas of the orbit.

Power supply of the load 2 is carried out in this case from the solar battery 1 through the voltage Converter 3.

When passing shadow portions of the orbit or in violation of orientation, load 2 is powered by batteries 4 ₁ -4 _n through discharge converters 6 ₁ -6 _n .

Monitoring and control devices 7 ₁ -7 _n monitor the voltage and temperature of the battery batteries 4 ₁ -4 _n and transmit information about their condition to the load 2.

If the voltage of any rechargeable battery 4 ₁ -4 _n decreases during the discharge to the lower controlled level, the voltage stabilizer 15 is turned on. In this case, the voltage of the voltage stabilizer 15 (supplied to the “vx” terminal) will be taken from the rechargeable battery (s) having the largest voltage, due to the presence of decoupling devices in the direction of flow of the discharge current, 16 ₁ -16 _n . From the output (terminal “out”) of the voltage stabilizer 15 stabilized at the level of the lower discharge voltage of the batteries (taking into account the voltage drop across the decoupling devices), the voltage through the decoupling devices in the direction of discharge current 17 ₁ -17 _n flows to all the batteries, however, the current will only flow towards batteries that have reached lower discharge voltage.

In this case, the discharge current of a discharged battery will gradually decrease to zero and further operation of the corresponding discharge converter will be carried out from the voltage regulator.

If any battery is disconnected from the serial battery circuit, the voltage stabilized for this battery decreases in proportion to the decrease in the number of batteries in the battery.

Thus, the proposed method and an autonomous satellite power supply system can improve the efficiency of using batteries and the specific energy characteristics of the autonomous power system itself.

Claims (2)

1. The method of supplying the load with direct current as a part of the autonomous power supply system of the artificial Earth satellite from the solar battery and a set of "n" secondary sources of electricity - lithium-ion batteries, which consists in stabilizing the voltage at the load, conducting charge-discharge cycles through individual charging and discharge converters, monitoring the voltage of the batteries and their batteries and limiting the charge and discharge of the batteries according to the specified values of the charger and discharge th voltage, characterized in that when the discharge voltage during a predetermined low battery value, this voltage is stabilized therein. 2. An autonomous power supply system for implementing the method according to claim 1, comprising a solar battery connected to a load through a stabilized voltage converter, “n” batteries connected through “n” charging converters to the solar battery, and through “n” discharge converters to load, each battery consisting of “t” series-connected batteries having disconnect relay contacts in a series circuit and closing relay contacts covering each battery together with its serially connected opening contact, characterized in that a voltage stabilizer is additionally introduced, connected to the batteries through the “n” decoupling devices, in the direction of discharge current flow, and connected to the batteries through the “n” decoupling devices, in the direction flow of charging current devices.