JPS6398712A - Controller for power generating system of fuel cell - Google Patents

Abstract

PURPOSE:To avoid both overdischarge and overcharge states by decreasing the difference between a load power pattern and a generated power pattern. CONSTITUTION:When a power generating system is started, the difference the load power and the generated power of a fuel cell 1 is corrected by the discharge power of an accumulator 3. Then a set level is varied so that the output signal of an output power setter 6 of the cell 1 is selected by a minimum selector 16. If the residual capacity of the accumulator 3 is reduced (overdischarge) owing to the continuous supply of the power of the accumulator 3, this drop of potential is detected by a function generator 13. As a result, the output signal of a load power detector 15 is corrected so that the output enable power of the cell 1 is increased. Thus the output of the cell 1 is selected by the selector 16 when the output enable power of the cell 1 is sufficiently increased. Then, the transfer power of a chopper circuit 2 increases larger than the load power. Thus, it is possible to supply the load power and to charge the accumulator 3 for recovery by means of the transfer power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention supplies power generated by a fuel cell to a load circuit via a chopper circuit. The present invention relates to a control device for a fuel cell power generation system including a storage battery on the load side of a chopper circuit.

[Prior art and its problems]

In an independent fuel cell power generation system that does not have a power system that should be operated in parallel, in order to prevent difficulty in supplying power to the load circuit during the start-up period of the generated power when starting the fuel cell, Alternatively, a system is known in which a storage battery is provided on the output side of a fuel cell via a chopper circuit or the like in order to compensate for a delay in response to load fluctuations.

FIG. 6 is a configuration diagram of an output electric circuit of a fuel cell power generation system showing the prior art. The output circuit of the fuel cell 1 is connected to a load 4 via a chopper circuit 2 and a storage battery 3 connected in parallel to the output side of the chopper circuit 2. It consists of a P1 regulator, etc., so that the output of the power detector 5 connected to the output side of the fuel cell 1 and the output setting signal of the setter B of the outputtable power of the fuel cell 1 are equal to each other. The output signal of the (power) regulator 7 controls the conduction rate of the chopper circuit 2, and sets the output power of the fuel cell 1, which is transferred to the load side via the chopper circuit 2. The fuel cell 1 is configured to be controlled based on the output setting signal of the fuel cell 1, and a fuel system (not shown) of the fuel cell 1 is controlled in conjunction with this.

In the fuel cell power generation system configured as described above, when the power consumption cover of the load 4 and the power generation cover of the fuel cell are almost balanced with each other during normal operation, the storage battery 5 responds to fluctuations in the load 4. By repeating discharge to the load side and recovery charging from the fuel cell side, a normal terminal voltage can be maintained, but when starting up the fuel cell 1, the output power is determined by the temperature rise rate of the fuel reformer (not shown), etc. When the voltage rises, the difference between the pattern and the load cover turn is compensated for by the discharge energy of the storage battery 6 which does not have a control device, and there is a problem that a large capacity storage battery must be provided to prevent over-discharge of the storage battery. In addition, when the power required by the load 4 is significantly reduced during normal operation, there are problems such as overcharging of the storage battery 6 due to the charging current supplied from the fuel cell 1 side, and there is a need for improvement. It is being

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation, and provides a control circuit that can suppress the difference between the load current cover turn and the generator xi cover turn, and that can prevent over-discharging and over-charging of the storage battery even when the deviation accumulates. The purpose is to provide a fuel cell power generation system with the following features.

[Key points of the invention]

The present invention provides power detectors on the fuel cell side and the load side of the storage battery, detects the terminal voltage of the storage battery, and issues correction signals with mutually different polarities when the voltage falls outside the upper and lower limits of the normal voltage range. A function generator is provided, the addition circuit adds the side positive signal and the output signal of the load side power detector, and the corrected load filJ 11! The lowest level signal between the force detection signal and the setting signal of the output power setting device is selected by the minimum selector, this low level signal is used as the setting signal, and this signal and the output signal of the fuel cell side power detector are mutually connected. By controlling the chopper circuit on and off using the power regulator to control the power output from the fuel cell to ensure equalization, when the function generator detects overdischarge of the storage battery, On the load side, the output signal of the force detector is corrected to be higher than the setting signal of the power setting device, the output setting signal of the setting device is selected by the minimum selector, and the chopper circuit starts generating electricity from the fuel cell! By fully transferring available power, load power can be supplied while charging the storage battery all the time, and when the function generator detects overcharging of the storage battery, the corrected output signal of the load side power detector is minimized. By correcting to the reduction side as selected by the selector, the transfer power of the chopper circuit is suppressed and the load power is also supplied from the storage battery, thereby avoiding overcharging of the storage battery and hypersensitive electric current. At the same time, it is possible to generate power corresponding to the load power cover turn.

[Embodiments of the invention] The present invention will be explained below based on examples.

FIG. 1 is a block diagram showing an embodiment of the present invention.
The same reference numerals are given to the same parts as in the conventional device, and detailed explanation thereof will be omitted. Referring to FIG. 1, reference numeral 15 denotes a load side power detector provided on the load circuit side of the storage battery B in correspondence with the fuel cell side power detector 5. +9, chopper circuit 2
A load power cover turn consisting of the sum of the power generated by the fuel cell 10 and the mtm power discharged by the storage battery 6 transferred via the power source can be detected. 13 monitors the terminal voltage of the storage battery 5 and outputs a correction signal 13A.
.

It is a function generator that emits 13B, and when the voltage of storage battery 3 exceeds the upper limit of the normal voltage range and shows signs of overcharging, it emits i.
It is configured to output a correction signal 15A that urges a reduction in t-force, and a correction signal 13B that urges an increase in generated power when the voltage falls below the lower limit of the normal voltage range and shows signs of overdischarge. In the circuit 14 the power detector 1
5 and one of the correction signals having different polarities from the function generator 16, when the terminal voltage of the storage battery 6 is within the normal voltage range, the output signal of the power detector The signal is output as is, and when the storage battery is in an overcharged state, a signal corrected to the reduction side is output, and when the storage battery is in an overdischarged state, a signal corrected to the increase side is outputted. Reference numeral 16 is a minimum selector, and the output setting signal of the output power setting device 6 for setting the power that can be generated by the fuel cell 1, or the output signal of the adder circuit 14, whichever is lower, is selected, and the output signal of the minimum selector is selected. is supplied to the power regulator 7 as a setting signal for the power regulator 7, and the chopper circuit 2 controls the fuel cell power generation so that the output signal of the fuel cell side power detector 5 is equal to the setting signal level supplied from the minimum selector side. It is configured to perform power transfer control.

FIG. 2 is a circuit diagram of the main parts in the embodiment, in which the function generator 15 is connected to setting devices 25A and 23B that respectively set the upper and lower limits of the normal voltage range of the storage battery B, and the terminal voltage and upper limit of the storage battery B. It can be configured with a pair of comparison circuits 66A and 3B for comparing the value and the lower limit signal, respectively. In addition, the minimum selector 16 has its input side configured with a resistor 16A and a diode 16B, and selects the minimum value of either the output signal of the adder circuit 14 or the output signal of the setting device 6 (in the figure, the signal level is negative, so the absolute value is The lower one) can be selected. Note that the addition circuit 14. The power regulator 7 has a well-known circuit configuration. In addition, in FIG. 2, the relationship between the remaining capacity of the cell and the terminal voltage is shown. changes depending on the temperature and current, so by setting upper and lower limits corrected by these, charging and discharging control of the storage battery can be performed more efficiently.

In the device configured as described above, for example, when starting the power generation system, the difference between the faK power of the fuel cell 1 and the load power can be compensated for by the broadcast power of the storage battery 6. Output power setting 6
By changing the settings so that the output signal B is selected, the amount of power generated by the fuel cell can be increased slowly according to the fuel supply state of the fuel cell 1, that is, the amount of power that can be outputted. . Furthermore, when the remaining capacity of the storage battery 3 decreases due to the supply of load power (over-discharge state), the function generator 15 detects the decrease in the storage battery voltage and converts the output signal of the load power detector 15 into the fuel Since a signal corrected in a direction that promotes an increase in the output power of the battery is outputted via the adder circuit 14, the output of power setting 6B is selected by the minimum selector 16 when the outputtable power of the fuel cell is sufficiently increased. , the transfer power of the chopper circuit increases to more than the load power via the power regulator 13t, and the transfer power can supply the load power and perform recovery charging of the storage battery B. Further, when the function generator 13 detects a voltage increase indicating overcharging of the storage battery 6 and outputs a correction signal that reduces the output signal of the load-side power detector 15, the minimum selector 16 selects the addition circuit 14. Output signal is selected and
The transferred power of the chopper circuit 2 is suppressed, and as a result, overcharging and overdischarging of the storage battery 3 are avoided, and power control can be performed with a small difference between the power generation amount cover turn and the load power cover turn.

〔Effect of the invention〕

As described above, the present invention provides an output signal of a function generator that monitors the state of a storage battery according to its terminal voltage, an output signal of a load-side power detector that has been corrected, and a setting device for the outputtable power of a fuel cell. Among the output signals, a low-level signal is selected by a minimum selector and used as a setting signal for a power regulator that controls the transfer power of the chopper circuit. the result,
The output of the load-side power detector corrected by the output signal of the fuel cell's outputtable power setting device and the output signal of the function generator that monitors the storage battery's over-light and over-discharge according to changes in its terminal voltage. Among the signals, the low-level output signal ttiL can be used as a setting signal for the force regulator to control the power transferred by the chopper circuit, in other words, the power generated by the fuel cell, so it can be used to control the start-up state of the power generated when the fuel cell is started, and the load. It is possible to finely control the transferred power by detecting the responsiveness to power fluctuations and the remaining capacity of the storage battery in steady operation conditions, and the conventional method of controlling the transferred power based on the output power of the fuel cell. Problems such as the gap between generated power and consumed power, as well as overcharging and overdischarging of storage batteries, which have become problems in technology, are reduced or eliminated. Therefore, overcharging and overdischarging that accelerate storage battery deterioration are suppressed, and the load It is possible to provide a control device for a fuel cell power generation system that has excellent coordination and stability with respect to fluctuations in power, and that requires less installation capacity of storage batteries because the difference between generated power and power consumption is reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a main part of the device according to the embodiment, and FIG. 6 is a block diagram showing a conventional device. DESCRIPTION OF SYMBOLS 1... Fuel cell, 2... Chopper circuit, 6... Power storage arm 4... Load, 5, 15... Power detector, 6...
・Output (possible) [force setting device, 7...power regulator, 16
...Function generator, 14... Addition circuit, 16... Minimum selector, 13A, 13B... Correction signal,
23A, 23B... Upper limit value, lower limit value setter, 55,
33B...Compare e11g Fig. 2 Fig. 3

Claims (1)

[Scope of Claims] 1) A storage battery connected in parallel to the output side of a fuel cell via a chopper circuit, and a power regulator that controls on/off of the chopper circuit to control transfer of power generated by the fuel cell. a function generator that monitors the state of charge of the storage battery using its terminal voltage and issues a correction signal for the transferred power; and a pair of power generators arranged on the output side of the fuel cell and the load side of the storage battery, respectively. a detector, an adder circuit that emits an output signal of the load-side power detector corrected by the correction signal, and a lower level of the output signal of the adder circuit and the output signal of the outputtable power setting device of the fuel cell; A fuel cell power generation system comprising: a minimum selector that selects and outputs a signal; and the power regulator whose input signals are the output signal of the minimum selector and the output signal of the fuel cell side power detector. control device. 2) In the device according to claim 1, the function generator includes a pair of setting devices for setting an upper limit value and a lower limit value of the normal voltage range of the storage battery, and output signals of each of the pair of setting devices and the storage battery voltage. a pair of comparators that mutually compare the voltage of the storage battery, and a correction signal that reduces the output signal of the load side power detector when the storage battery voltage exceeds the upper limit value, and a correction signal that reduces the output signal of the load side power detector when the storage battery voltage falls below the lower limit value A control device for a fuel cell power generation system, characterized in that the control device for a fuel cell power generation system is characterized in that the control device outputs correction signals for increasing the output signal of each to an adding circuit. 3) The fuel according to claim 2, wherein the upper limit value and lower limit value set in the pair of setting devices take into account the temperature dependence and current dependence of the storage battery voltage. Control circuit for battery power generation system.