JPH09154241A - Power supply unit for solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to judge solar array bus lock up by a monitor signal alone within the same apparatus by judging the state of main bus voltage by using the main bus current telemetry signal. SOLUTION: Reference power supply 15 multiplies the output ISA-TLM of a solar array current monitor with a multiplier 16 and calculates the power generated. Then, the output (VMB-TLM) of a bus voltage monitor 12 and the output IBM-TLM of a load current monitor 10 are multiplied by a multiplier 17 to calculate the load power. Outputs of multipliers 16 and 17 are judged by a comparator 18 and if power generated is large, then output, 1 is output; if the load power is great, then 0 is output. VMB-TLM is judged by a comparator 19, and 1 is output if it is satisfactory and 0 if not satisfactory. Outputs of comparators 18 and 1 are judged by an AND circuit 21, and a load power relieving signal is output from the AND circuit 21 if bus voltage is not a stabilized voltage of normal insulation nevertheless the power generated is larger than tone load power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell power supply system such as an artificial satellite for supplying power to a load from a solar cell by a shunt device during sunshine, and supplying power to the load by discharging a storage battery during shade. A solar array bus that sometimes determines that the voltage of the solar battery power system is fixed to the battery voltage and that the load can be supplied only by the power generated by the solar battery, but that the battery is also discharged for a long period of time. The present invention relates to a lockup determination device.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional solar battery power supply device, in which 1 is a solar battery, 2 is a storage battery, 3 is an anode connected to the output end of the solar battery 1, and its cathode is a power supply bus. The constituting blocking diodes 4 are connected in parallel with the solar cell 1 between the anode of the blocking diode 3 and a return line (hereinafter, simply referred to as RTN), and a shunt that consumes the surplus electric power generated in the solar cell 1. A device 5 is a discharge diode whose cathode is connected to the power supply bus, and 6 is a parallel connection to the discharge diode 5 on the power supply bus.
A charger for charging the battery, 7 a capacitor bank connected between the power bus and RTN, 8 a load connected between the power bus and RTN, 9 a current flowing from the blocking diode 3 into the power bus A solar array current monitor 10 which detects a value, converts it into a telemetry signal ISA-TLM, and sends it out. A solar array current monitor 10 detects a current value flowing into the load 8 from the power supply bus, and a telemetry signal IMB-TLM.
A load current monitor 11, which converts and outputs the current, is connected between the discharge diode 5 and the storage battery 2 to detect a charge / discharge current value of the storage battery 2, and a telemetry signal ID / C-
A charge / discharge current monitor for converting into a TLM and sending the same, a reference numeral 12 for detecting a voltage of the capacitor bank 7, and a bus voltage monitor for converting into a telemetry signal VMB-TLM and sending it out, 1
A solar array bus 3 calculates output signals of the solar array current monitor 9, the charge / discharge current monitor 11, and the bus voltage monitor 12, detects a solar array bus lockup state, and sends a power reduction signal to a load. Lockup determination device, 14 adder, 15 standard power supply, 1
6 is a first multiplier, 17 is a second multiplier, and 18 is a comparator.

During sunlight, the electric power generated by the solar cell 1 is supplied to the load 8 via the blocking diode 3. Part of the electric power generated by the solar cell 1 that exceeds the power consumption of the load 8 is the charger 6
Is supplied as charging power to the storage battery 2 via the battery and is consumed by the shunt device 4 when there is a surplus.
At this time, the voltage of the capacitor bank 7 (hereinafter referred to as “bus voltage”) is stabilized to a value of VSSU. Generally, the bus voltage VSSU during sunshine is selected to be higher than the voltage VBAT of the storage battery 2.

FIG. 5 shows the relationship between the power generated by the solar cell 1 and the load power consumed by the load 8. The generated power of the solar cell 1 is represented by the IS-VS curve in FIG. On the other hand, the load 8 is generally treated as a constant power load because a DC / DC converter is built in the inside and the bus voltage is converted into an appropriate constant voltage to consume power. Therefore, the relationship between the bus voltage and the load current is a curve represented by P-P 'in FIG. As described above, since the shunt device 4 consumes the surplus power generated in the solar cell 1 so as to stabilize the bus voltage at VSSU, the power operating point is MM ′ and PP ′ in FIG. It becomes intersection A.

On the other hand, since the power generated by the solar cell 1 cannot be obtained in the shade, the storage battery 2 is discharged to supply the load 8 through the discharge diode 5. At this time, the bus voltage is the voltage VBA depending on the discharge voltage of the storage battery 2.
It becomes T.

In order to monitor the operating state of the power supply system, the solar array current monitor 9, the load current monitor 10, the charge / discharge current monitor 11 and the bus voltage monitor 12 detect the state of each part and convert it into a telemetry signal to convert it to ground. Send to the station.

FIG. 6 shows the transition of the power operating point when the load power fluctuates during daylight. In FIG. 6, an IS-VS curve is a generated current-voltage characteristic of the solar cell 1, VBAT is a bus voltage when the storage battery 2 is discharging, and VSSU is surplus power control of the solar cell 1 by the shunt device 4. And is the stabilized bus voltage value.

Now, consider a case where the power consumption of the load 8 fluctuates when the power consumption of the load 8 is P1 and the operating point is the point A. When the power consumption of the load 8 fluctuates within a range not exceeding VSSU × IS, the power operating point is the straight line M- in FIG.
It is on M '. However, the power consumption of the load 8 is VSSU ×
When P1 is increased to P2 beyond IS, solar cell 1
Since the generated power is exceeded, the storage battery 2 is discharged to compensate for the insufficient power, and the power operating point moves from A to M to B.

Once the power operating point moves to point B, even if the power consumption of the load 8 returns to P1 immediately thereafter,
The power operating point cannot be returned to the point A, and the bus voltage is fixed to the discharge voltage of the storage battery 2 even though the solar cell 1 has enough generated power to cover all the load power simply by moving to the point C. A solar array bus lockup phenomenon occurs in which discharge from the storage battery 2 cannot be avoided.

Therefore, the solar array bus lockup determination device detects the above-mentioned solar array bus lockup state by using each of the load current monitor 10, charge / discharge current monitor 11, and bus voltage monitor 12 telemetry monitors. A control signal for temporarily reducing the load power to P3 or less in FIG. 6 is sent to the load 8. Here, a value obtained by performing engineering conversion of the telemetry ISA-TLM of the solar array current monitor 9 is ISA, and the value of the load current monitor 10 is telemetry IM.
A value obtained by performing engineering conversion of B-TLM is IMB, and a value obtained by performing engineering conversion of telemetry VMB-TLM of bus voltage monitor 12 is VMB.
MB, when the stabilized bus voltage value by the shunt device 4 at the time of sunshine is VSSU, the effective generated power and load power of the solar cell 1 are calculated using the above-mentioned values, and the load 8 is applied when the following formula is satisfied. The load power reduction signal is sent.

[0011]

(Equation 1)

That is, the power operating point changes from C to D to E, and the bus voltage can be restored to the stabilized voltage VSSU during sunshine. It is clear that if the load power is reset to P1 again, it will return to the power operating point A in the steady state. Hereinafter, the method for determining the solar array bus lockup in the solar array bus lockup determination device 13 will be described in detail.

The first multiplier 16 has a telemetry output terminal of the solar array current monitor 9 and the reference power source 1.
The output PS of the solar array current monitor 9 multiplied by the telemetry ISA-TLM of the solar array current monitor 9 and the output VREF of the reference power supply 15 is sent to the comparator 17.

The adder 14 is connected to the telemetry output terminal of the solar array current monitor 9 and the telemetry output terminal of the charging / discharging current monitor 11, and the telemetry ISA-TLM of the solar array current monitor 9 and the telemetry of the charging / discharging current monitor 11 are connected. The result of addition of ID / C-TLM (ISA-TLM + ID / C-TLM) is sent to the second multiplier 17. The second multiplier 17 is connected to the output terminal of the adder 14 and the telemetry output terminal of the bus voltage monitor 12, and the output of the adder 14 (I
SA-TLM + ID / C-TLM) and bus voltage monitor 1
The output VBUS-TLM of 2 is multiplied and the result is sent to the comparator 18.

The comparator 18 is the first multiplier 16
Output PS and output PL of the second multiplier 17 are compared, and if the following expression is satisfied, a load power reduction signal is output to the load 8.

[0016]

(Equation 2)

Input signals VREF, ISA− to the first multiplier 16, the adder 18, and the second multiplier 17 are input.
TLM, ID / C-TLM, and VBUS-TLM have the following relationships between the stabilized bus voltage VSSU, the solar array current ISA, the discharge current ID of the storage battery 2, and the bus voltage VBUS that are actually obtained by the shunt device 4. doing.

[0018]

(Equation 3)

[0019]

(Equation 4)

[0020]

(Equation 5)

[0021]

(Equation 6)

In Expressions 3 to 6, K1 and K2 are constant conversion coefficients for converting the actual current level or voltage level into telemetry. In addition, the reference power source 1
The output VREF of 5 is set so that the equation 6 is satisfied. The input signals PS and PL to the comparator 18 are expressed by Equation 3
From Equation 6

[0023]

(Equation 7)

[0024]

(Equation 8) Given by

In Equation 8, (ISA + ID) is the actual solar array current plus the discharge current of the storage battery 2, so that in the solar array bus lockup state,
It is equal to the actual load current IL flowing from the bus into the load 8. That is, at the time of lockup of the solar array bus, PS indicates a value corresponding to the effective generated power of the solar cell 1, and PL indicates a value corresponding to the load power of the load 8. Therefore, by substituting the equations 7 and 8 into the equation 2 in consideration of the above, the equation 1 is obtained, but the equation 1 is nothing but the determination condition of the solar array bus lockup.

[0026]

Since the solar cell power supply device in the geostationary satellite can secure a long charging time by its orbital element, the charger can be made small. Therefore, as described in the prior art, it is usual that the above solar array current, main bus voltage, and charge / discharge current monitors are provided in the same device. On the other hand, the solar battery power supply device in an orbiting satellite is required to be charged at a high speed because the charging time is extremely shorter than that of a geostationary satellite. As a result, the charging power increases and it is difficult to physically and thermally store the chargers in the same device like a geostationary satellite. Therefore, the devices are generally separated. For this reason,
In many cases, it is difficult to perform signal processing within the same device like a geostationary satellite, and the charge / discharge current telemetry ID described above is used.
Since only / C-TLM is a monitor signal from another device, there is a problem that the interface becomes complicated and the performance cannot be evaluated by a single device.
Further, since the multiplier is composed of a digital IC, the circuit structure is complicated and the arithmetic processing capability is very effective, but it often causes increase in weight or cost.

The present invention has been made to solve the above problems, and even in a solar cell power supply device for an orbiting satellite, a solar array bus lockup is performed only by a monitor signal in the same device without having an interface with other devices. The purpose is to determine.

Further, according to the present invention, a multiplier having a complicated circuit structure is conventionally used, which uses a relatively expensive digital IC.
Although it was configured using a single unit, in order to reduce the weight and reduce the cost, a solar array bus lockup determination device capable of determining the solar array bus lockup state with a single multiplier and outputting a load power reduction signal can be obtained. With the goal.

Further, the present invention does not use an expensive digital IC for further weight reduction and cost reduction,
An object of the present invention is to obtain a solar array bus lockup determination device equipped with a multiplier by using a pulse width control IC.

[0030]

Embodiment 1 of the present invention
The solar array bus lockup determination device involved in
A comparator for determining the state of the main bus voltage by using the main bus current telemetry signal instead of the charge / discharge current telemetry is provided.

Further, the solar array bus lockup determination device according to the second embodiment of the present invention is configured so that a single multiplier can determine by providing a comparator for determining the state of the solar array current. .

In the solar array bus lockup determination device according to the third embodiment of the present invention, the multiplier in the first invention or the second invention is a pulse width control IC (PW) which is a switching regulator control IC.
(M-IC).

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 is an example showing the first embodiment of the present invention, in which 1 to 13 are exactly the same as the conventional solar cell power supply device. 15 is a first reference power source, 16 is a first multiplier,
17 is a second multiplier, 18 is a first comparator, 19 is a second
Is a second reference power source, and 21 is an AND circuit. The solar array lockup determination device will be described below.

The first reference power supply 15 is VSS in the equation 1.
U, ie about 50 stabilized bus voltage during daylight
The first multiplier 16 multiplies V by a signal whose level is converted according to the signal level of the ISA-TLM and the ISA-TLM output from the solar array current monitor 9. As a result, the left term of Equation 1, that is, the generated power is calculated.
Next, the output VMB-TLM of the bus voltage monitor 12 and the output IMB-TLM of the load current monitor 10 are multiplied by the second multiplier 17. As a result, the right term of Equation 1, that is, the load power is calculated. The output of the first multiplier 16 and the second
The output of the multiplier 17 is determined by the first comparator for the magnitude relation, and the output is "1" when the generated power is large, and "0" is output when the load power is large.

On the other hand, the output VMB- of the bus voltage monitor 12
The second comparator 19 determines whether the TLM satisfies the equation 9, and outputs "1" when the equation is satisfied, and outputs "0" when the equation is not satisfied. The output of the first comparator 18 and the output of the second comparator 19 are determined by the AND circuit 21, and the two input signals of the AND circuit 21 are both "1".
In other words, if the bus voltage is not the regulated voltage during sunshine, even though the generated power is greater than the load power, AND
A load power reduction signal is output from the circuit 21.

[0036]

(Equation 9)

Embodiment 2 FIG. 2 is an example showing the second embodiment of the present invention, in which 1 to 13 are exactly the same as the conventional solar cell power supply device. 15 is a reference power source, 17 is a multiplier,
18 is a first comparator, 19 is a second comparator, 21 is an AN
The D circuit, 22 is a constant K. The solar array lockup determination device will be described below.

Output VMB- of main bus voltage monitor 12
The TLM and the output IMB-TLM of the load current monitor 10 are calculated by the multiplier 17 to obtain the load power, which is the right side of Expression 1. Here, Equation 1 is transformed into Equation 10.

[0039]

(Equation 10)

That is, the ISA-TLM transfers the load power to VS.
It is none other than what is divided by SU. So VSSU
Is assumed to be a stabilized bus voltage of 50 V during sunshine, and is divided by "50", that is, the constant K18 is 0.02 times, and voltage conversion is performed. This output and the output I of the solar array current monitor 9
By comparing the SA-TLM with the first comparator 18,
Equivalently, the magnitude relationship of Equation 1 can be compared. The output of the comparator 18 is "1" when the expression 10 is satisfied, and "0" is output when the expression 10 is not satisfied.

On the other hand, the output VMB- of the bus voltage monitor 12
The second comparator 19 determines whether the TLM satisfies Expression 9, and if it is satisfied, outputs "1", and if not satisfied, outputs "0". The first comparator 18
Output of the second comparator 19 is determined by the AND circuit 21, and the two input signals of the AND circuit 21 are both "1", that is, the generated power is larger than the load power, the bus voltage is When the voltage is not the stabilized voltage during sunshine, the AND circuit 21 outputs a load power reduction signal.

Embodiment 3. 3 is an example showing the third embodiment of the present invention, in which 23 is a pulse width control circuit, 24 is a switching element, and 25 is a smoothing circuit. The output IMB-TLM voltage of the load current monitor 10 is duty ratio converted by the pulse width control circuit 23. As shown in FIG. 7, by comparing the input voltage and the triangular wave, the characteristic is that the switching element 24 is in the ON state in the region where the IMB-TLM voltage is higher than the triangular wave, and the smoothing circuit 25 outputs the output V of the bus voltage monitor circuit.
The MB-TLM voltage is applied, and in a region lower than the triangular wave, the switching element is turned off, and the smoothing circuit 2
The voltage is controlled so that the VMB-TLM voltage is not applied to 2. Based on the ratio of the ON period and the OFF period, the right side of Equation 1 can be equivalently calculated, that is, the load power can be calculated, and the load power value can be extracted in the form of voltage conversion by adjusting the voltage to be averaged by the smoothing circuit. it can. As a result, it is possible to determine the solar array lockup state exactly the same as in the first invention or the second invention.

[0043]

Since the present invention is configured as described above, in the orbiting satellite, the solar array bus lockup determination can be performed only by the monitor signal in the same device, so that the interface with other devices becomes unnecessary, This can contribute to prevention of erroneous wiring and weight reduction, and also has the effect of preventing malfunction due to shortened wiring.

Further, the present invention can reduce the cost and the weight by reducing the number of multipliers from two to one.

Furthermore, the present invention can achieve further cost reduction and weight reduction by replacing the multiplier with a multiplication circuit using a pulse width control IC.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a solar cell power supply device according to the present invention.

FIG. 2 is a diagram showing a second embodiment of a solar cell power supply device according to the present invention.

FIG. 3 is a diagram showing Embodiment 3 of the solar cell power supply device according to the present invention.

FIG. 4 is a diagram showing a conventional solar cell power supply device.

FIG. 5 is a diagram showing a relationship between load power and generated power in a conventional solar cell power supply device.

FIG. 6 is a diagram showing transition of a power operating point in the occurrence and avoidance of a solar array bus lockup.

FIG. 7 is a diagram showing a relationship between a triangular wave of a multiplier according to the present invention and a main bus current telemetry signal.

[Explanation of symbols]

1 solar cell, 2 storage battery, 3 blocking diode, 4 shunt device, 5 discharge diode, 6 charger, 7 capacitor bank, 8 load, 9 solar array current monitor, 10 load current monitor, 11 charge / discharge current monitor, 12 bus voltage Monitor, 13 solar array bus lockup determination device, 14 adder, 15 1st
Reference power source, 16 first multiplier, 17 second multiplier, 18 first comparator, 19 first comparator, 20 first reference power source, 21 AND circuit, 22 constant K, 23
Pulse width control IC, 24 switching element, 25
Smoothing circuit.

Claims (3)

[Claims] 1. A solar cell, and a shunt device connected in parallel between an output terminal and a return line of the solar cell,
Between the first diode whose anode is connected to the output terminal of the solar cell, the solar array current monitor whose output end is connected to the cathode of this diode to form a power supply bus, and between the power supply bus and the return line N (n is 2 or more) chargers, charge / discharge current monitors and storage batteries connected in series, and n (n is 2 or more) chargers connected to the power source bus in parallel with the cathodes. Discharge diode, bus voltage monitor and bus capacitor connected in parallel between the power bus and return line, load current monitor connected in series between the power bus and return line, and output of the bus voltage monitor signal,
The solar array bus lockup state of the solar cell power supply system is calculated by the operation of two multipliers using only the output signal of the load current monitor and the output signal of the solar array current monitor without using the output signal of the charge / discharge current monitor. A solar cell power supply device comprising a solar array bus lockup determination device capable of detecting a load and transmitting a control signal for reducing the load to the load. 2. The solar array bus lockup determination device is configured such that the solar array bus lockup state of the solar cell power supply system is detected by one multiplier. Solar cell power supply. 3. The solar array bus lockup determination device is characterized in that a pulse width controlling IC is used as the multiplier to detect the solar array bus lockup state of the solar cell power supply system based on the duty ratio. Item 2. The solar cell power supply device according to item 1.