JP3047935B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for supplying power generated by a solar cell to a load during a sunshine while stabilizing a bus voltage by a shunt device and a charge / discharge control device. The present invention relates to a power supply device for an artificial satellite or the like to be supplied.

[0002]

2. Description of the Related Art An example of a conventional power supply device is shown in FIG. FIG.
, 1 is a solar cell, 2 is a blocking diode whose anode side is connected to the output of the solar cell 1, 3 is a cathode of the blocking diode 2 constitutes a power bus,
A load 4 connected between this and the return is connected in parallel with the solar cell 1 on the anode side of the blocking diode 3, and a shunt device 5 that consumes surplus power during sunshine.
Is an error amplifier circuit that detects the voltage of the power supply bus and outputs an error amplifier signal as an error signal. A circuit, 7 is a capacitor bank connected between the power supply bus and the return, 8 is a first storage battery of n (n is an integer of 2 or more) storage batteries, and 9 is a first storage battery of n storage batteries. a first charge / discharge control device, 11 connected in series to charge the first storage battery 8 in the sunshine and to supply the discharge power of the first storage battery 8 to the load in the shade, 11
Is an n-th charge / discharge control device connected in series to charge the n-th storage battery 9 during sunshine and to supply the discharge power of the n-th storage battery 9 to the load during shade.

Next, the operation of the conventional power supply device shown in FIG. 4 will be described. At the time of sunshine, power generated by the solar cell 1 is supplied to the load 3 via the blocking diode 2. The surplus power generated by the solar cell 1 in excess of the power consumed by the load 3 is stored in the capacitor bank 7, so that the voltage of the power bus increases. At this time, the error amplifier circuit 5 monitoring the voltage of the power supply bus outputs a bus control signal for suppressing a rise in the bus voltage, that is, an error amplifier signal. First, n storage batteries from the first storage battery to the n-th storage battery are simultaneously charged by the first charge / discharge control device to the n-th charge / discharge control device to consume surplus power, and the voltage of the power supply bus is It operates to suppress the rise of Further, in a case where surplus power is still consumed at the maximum level of charging power in the n storage batteries, there is still surplus power, a shunt drive signal is output from the shunt drive circuit 6, and the shunt device consumes the surplus power. Is started, the rise of the bus voltage is suppressed.

FIG. 5 shows the relationship between the error amplifier signal, the charging current, and the shunt power. First, regarding the charging current, in a certain range of the error amplifier signal (when the voltage is relatively low), the charging current is determined by a proportional characteristic, and when a certain level is exceeded, a constant charging current value (maximum value) is obtained. ). Therefore, it can be seen that the charging power of the storage battery naturally has an upper limit. on the other hand,
The shunt device starts its operation at the same time as the charging power to the storage battery reaches a certain value, that is, the maximum, by a shunt driver signal having a characteristic proportional to the error amplifier signal, and has a power consumption characteristic proportional to the error amplifier signal.
In this way, the bus voltage during sunshine is stably controlled. Further, since the power generated by the solar cell 1 is lost in the shade, the power is supplied from the first storage battery to the load 3 via the charge / discharge control device connected in series to each storage battery from the nth storage battery. At this time, the voltage of the power supply bus becomes a voltage dependent on the discharge voltage of the storage battery.

[0005]

In the above-described power supply device, when a single failure occurs in any of the n storage batteries and power cannot be supplied from a certain system in the shade, Since the power supplied to the load is reduced by (n-1) / n times, there is a problem that the full mission operation cannot be performed. It is clear that the smaller the number n of parallels, the greater the effect.

The present invention has been made to solve such a problem, and even if a single failure occurs in a storage battery,
The purpose is to supply the same power to a load in the shade as in normal operation.

[0007]

A power supply device according to the present invention is such that a charging current can be switched in a conventional charge / discharge control device.

[0008]

In the power supply device according to the present invention, even if a single failure occurs in the storage battery, the depth of discharge of the other normal (n-1) storage batteries in the shade is multiplied by n / (n-1) times. And the charge current value of the storage battery during the next sunshine is n
By changing it to / (n-1) times, the charge / discharge power balance of the storage battery can be satisfied.

[0009]

[Embodiment 1] FIG. 1 is a view showing an embodiment of the present invention.
2 is a first charge current switching type charge / discharge control device, 13 is an nth
A charging current switching type charge / discharge control device, 14 a charging current switching unit, 15 a changeover switch, and 16 a linear amplifier for outputting a control signal for determining a charging current value based on a reference voltage.

FIG. 2 is a diagram showing the relationship between the error amplifier signal and the charging current and shunt power according to the present invention.
FIG. 3 is a diagram showing details of the charging current switching unit. Hereinafter, the power supply device having the above configuration will be described in detail.

In the sunshine, electric power generated by the solar cell 1 is supplied to a load 3 via a blocking diode 2.
The surplus power generated in the solar cell 1 with power exceeding the power consumption in the load 3 is stored in the capacitor bank 7,
This will increase the voltage of the power bus. At this time, the error amplifier circuit 5 monitoring the bus voltage outputs a bus voltage control signal, that is, an error amplifier signal, in order to suppress a rise in the bus voltage. First, in order to consume surplus power, charging of n storage batteries from the first storage battery to the nth storage battery is performed by the first charging current switching type charging / discharging control device to the nth charging current switching type charge / discharge control device. Simultaneously, the operation is performed to suppress the rise of the bus voltage. Further, in a case where the surplus power is still consumed even though the n storage batteries consume the surplus power, the shunt drive circuit 6 outputs a shunt drive signal and the shunt device starts consuming the surplus power. As a result, an increase in the bus voltage can be suppressed.

In such a power supply device, consider a case where a single failure occurs in the storage battery and the supply power in the shade decreases. When the depth of discharge of the storage battery in a normal state is DOD [%], the charging current is I CHG [A], the voltage of the storage battery is V BAT [V], and the nominal capacity of the storage battery is C [AH], the total discharge power of the storage battery PO Is determined by equation (1). PO [WH] = C [AH] x VBAT [V] x DOD [%] x number of storage batteries (1)

Assuming that the number of discharge systems becomes (n-1) due to a single failure of the storage battery, the supply power PO becomes (n-1) / n times as is apparent from the equation (1). It can be seen that if the same power is supplied to the load as in the normal state, the same power can be obtained if any parameter is multiplied by n / (n-1). Here, when examining each of the above parameters,
The parameter that is considered operable is the depth of discharge of the storage battery. The expression for calculating the depth of discharge of the storage battery is as shown in Expression (2). By allowing the depth of discharge DOD of the storage battery to be n / (n-1) times, the same power as in the normal state can be supplied. DOD [%] = C [AH] x VBAT [V] x number of storage batteries / P [WH] (2)

Next, the charging current will be considered. The charging current usually has a value proportional to the depth of discharge, and is as shown in Expression (3). Therefore, when the charge / discharge capacity ratio is fixed, the charge current is changed at the same ratio in order to increase the DOD by n / (n-1) at the time of a single failure of the storage battery. Can be satisfied. I CHG [A] = C [AH] x DOD [%] x charge / discharge capacity ratio ... (3)

When the charging power is obtained, the charging rate is obtained from equation (4), and therefore the maximum charging power per vehicle is obtained from equation (5). Equation (3) is added to equation (5).
By substituting Equation (4) and Equation (4), it is clear that the charging power is also proportional to the depth of discharge DOD, and it can be understood that the charging power also becomes n / (n-1) times. Charge rate = I CHG [A] / C [AH] (4) P CHG [W] = C [AH] × V BAT [V] × Charge rate / η (5)

Here, details of the switching of the charging current will be described. The determination of the charging current is performed via the changeover switch 15 in the charging current switching unit 14 shown in FIG. 3, and in a normal state, the first reference voltage signal VREF1 is selected as the input signal of the linear amplifier. The charging of the storage battery is performed according to the charging current characteristic shown in FIG. At this time, a control signal for obtaining the normal charging current shown in FIG. 2 is output to the output of the linear amplifier 16. If a failure as described above occurs in a certain storage battery, the input signal of the linear amplifier is switched to the second reference signal VREF2 by the changeover switch 15 in the charging current switching unit 14. VREF2 has a charging current of n /
This is a reference voltage provided so that a control signal of the linear amplifier that can be multiplied by (n-1) times can be output. The characteristic of the charging current at this time is a characteristic given by the maximum value at the time of abnormality shown in FIG. 2, and at the time of abnormality, the characteristic is n / (n-1) times the maximum value of the normal state.

As described above, even when a single failure occurs in an arbitrary storage battery and power cannot be supplied from the corresponding discharge system, the depth of discharge and the maximum value of the charge current in the shade during operation in orbit Is changed to n / (n-1) times, an operation satisfying the charge / discharge power balance can be achieved, and the same amount of power as in the normal state can be supplied to the load.

[0018]

As described above, in the power supply device according to the present invention, even when a single failure occurs in the storage battery, the same power as in the normal state can be supplied to the load in the shade, and the single storage battery can be used. There is an effect that an operation plan that is not limited to mission operation can be implemented even at the time of failure.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power supply device showing one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an error amplifier signal, a charging current, and shunt power according to the present invention.

FIG. 3 is a diagram showing details of a charging current switching unit of the power supply device according to the present invention.

FIG. 4 is a diagram showing a configuration of a conventional power supply device.

FIG. 5 is a diagram showing a relationship between an error amplifier signal, a charging current, and shunt power in a conventional power supply device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 solar cell 2 blocking diode 3 load 4 shunt device 5 error amplifier circuit 6 shunt drive circuit 7 capacitor bank 8 first storage battery 9 nth storage battery 10 first charge / discharge control device 11 nth charge / discharge control device 12th 1 current switching type charge / discharge control device 13 nth current switching type charge / discharge control device 14 charging current switching unit 15 changeover switch 16 linear amplifier

Claims (1)

(57) [Claims] 1. A solar cell, a shunt device connected in parallel between an output terminal of the solar cell and a return, a blocking diode having an anode connected to the output terminal of the solar cell and a cathode constituting a power bus. A capacitor bank and a load connected between the power bus and the return, an error amplifier circuit that detects a voltage of the power bus and outputs a drive signal for consuming surplus power generated in the solar cell; and A shunt drive circuit that outputs a control signal for driving the shunt device in accordance with an output signal of an amplifier circuit; and n (n is an integer of 2 or more) that supplies power to the load when there is no power generated by the solar cell. Storage batteries, and the n storage batteries, each of which is connected in series, and n charging / discharging control devices forming an n-system charging / discharging system between a power supply bus and a return; When the charging / discharging control device charges the storage battery in a state where the number of discharge systems is n-1 due to a single failure of the storage battery, the charge current value of the power supply device at normal time A power supply unit characterized in that a function of switching to be n / n-1 times is added to the charge / discharge control device.