JPS63124728A - Load current automatic balancing circuit of charging means - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to the case where a plurality of charging means for outputting constant voltage DC power and supplying constant voltage DC power to a load such as a battery are operated in parallel. The present invention relates to an automatic load current balancing circuit for charging means, which allows each charging means to share and operate a load proportional to the number or capacity of the charging means.

[Conventional technology]

A charger that supplies DC power at a constant voltage to a DC load such as a battery can be used to supply power to a load by running multiple chargers in parallel when the capacity is insufficient or when you want to improve the reliability of the power supply. supply. At this time, in order to balance the current shared by each charger, if each charger is given a so-called drooping characteristic, in which the output voltage of that charger decreases as the output current increases, then the load fluctuation It is well known that stable parallel operation can be expected because the current shared by each charger is automatically balanced in response to the current. However, having the drooping characteristic means that the output voltage also changes in response to load fluctuations, and cannot meet the demand for supplying DC power at a constant voltage as described in the introduction.

Therefore, when multiple chargers that output constant voltage DC are connected in parallel and operated, conventionally each charger is equipped with a voltage adjustment circuit to automatically adjust its output voltage to a constant voltage. As for the current, by providing a limiter function, when the output current of the charger reaches the value that should be limited, for example, the rated voltage, the output voltage is suddenly reduced to prevent overcurrent.
When multiple such chargers are operated in parallel, the charger whose output voltage is adjusted to the highest level within a predetermined voltage range starts supplying power to the load preferentially. When the output current of the charger increases to the rated voltage, the output voltage will drop rapidly due to the limiter function described above, and from there the charger adjusted to the second highest voltage will
Subsequently, the power for the shortage will be supplied to the second charger, and each charger will start or stop supplying the second power according to the load power.

Figure 3 is a graph showing the current shared by each charger when conventional chargers equipped with a current limiter function and output constant voltage DC power are operated in parallel, and shows the case where three chargers are operated in parallel. ing. Figure 3 (a) shows the voltage characteristics of each charger, and Figure 3 (b) shows the total output current 11 of each charger.
++2+ I3, Figure 3 (C) shows the output current 11 of the No. 1 charger, and Figure 3 (D) shows the output current I2 of the No. 2 charger.
, and Figure 3 (e) shows the output current I of the No. 3 charger, respectively.

In this Figure 3, the total current flowing to the load is 11 and the output current of each charger No. 1, No. 2, and No. 3 is 11 and I2, respectively.
・■. As shown in Figure 3 (a), the output voltages of the three chargers are each adjusted to a value vI r v2 +V, and there is a slight difference in the magnitude relationship between the values v, > V2 > V3. Assume that the No. 1 charger has an output current value of 1. When the rated value is reached, the output voltage suddenly drops from vl, and similarly for chargers No. 2 and 3, when the output current reaches the rated value, the output voltage drops suddenly. shall be. Here, when the load current I gradually increases, the No. 1 charger with the highest voltage bears this load current, but when the value reaches the rated current value l of the No. 1 charger, suddenly Since the output voltage decreases, a current of 11 or more is not output (see FIG. 3 (c)). Therefore, the No. 2 charger that outputs the second highest voltage v2 bears the portion of the current exceeding this ll (see Figure 3 (d)), but this No. 2 charger also outputs a current of If exceeds the rated value, the current limiter function will be activated and the output voltage will drop sharply, and any load current beyond that will be supplied from the No. 3 charger (see Figure 3 (E)).

Therefore, the current supplied to the load by parallel operation of these three chargers is 1++I2, as shown in Figure 3 (b).
It becomes +13.

[Problem that the invention seeks to solve]

As mentioned above, when multiple chargers are operated in parallel to supply constant voltage DC power to a load, it is important to provide each charger with a droop characteristic in order to stabilize the parallel operation. The output DC voltage will change in response to the fluctuation, and DC power at a constant voltage will not be supplied. Therefore, multiple charging devices are operated in parallel, each equipped with a voltage adjustment means to keep the output voltage constant, and a limiter function that sharply drops the output voltage when the output current reaches a predetermined value. However, in such a configuration, a large imbalance occurs in the load sharing between each charging means, and a charging means that outputs 100% of the rated value and a charging means with no load at all may operate in parallel at the same time. This causes various inconveniences, such as shortening the life of the device.

Therefore, an object of the present invention is to distribute the current flowing through the load to each charging means when a plurality of charging means that output constant voltage DC power are operated in parallel, and each charging means outputs this divided current. By controlling the output voltage so as to balance the load shared by each charging means.

Means for Solving Problem C] In order to achieve the above object, according to the present invention, a voltage regulating means for outputting constant voltage DC power is provided, and constant voltage DC power is supplied to a load such as a battery. In a device that operates by connecting a plurality of supply charging means in parallel, a current distribution means distributes the current flowing to the load to each charging means as a current command signal, and an actual current value output by a specific charging means and the current. Current regulating means compares the current command value distributed to the specific charging means from the distributing means and outputs a voltage signal that makes the deviation between the two zero; Each of the charging means is equipped with a circuit for inputting a correction signal to the voltage regulating means of the charging means, and the current distribution means sends a current command signal to each charging means of a magnitude proportional to its capacity. shall be configured to output.

[Effect]

In this invention, a current distribution means is provided which detects the load current and distributes it in proportion to the number of operating charging means operating in parallel or the capacity of the charging means, and from this current distribution means to each charging means. A circuit is configured such that a current regulating means is installed and the output of the current regulating means is inputted as a correction signal to the voltage regulating means so that the charging means outputs a main stream of a magnitude equal to the current command value to be output. By doing so, the output voltages of each charging means are made the same, and the load sharing ratio is made equal.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which three charging means operate in parallel and supply constant voltage DC power to a load.

Note that the No. 2 charger 20 and No. 3 charger 30 shown in FIG.
The current adjustment circuits 22 and 32 and the voltage adjustment circuits 27 and 37 provided in the battery charger 10 have the same configuration as the current regulation circuit 12 and the voltage regulation circuit 17 provided in the No. 1 charger 10, Also, the explanation will be omitted.

In FIG. 1, the No. 1 charger 10 has a current detector 11 that detects the actual value of its output current, and compares this actual current value with the current command value obtained from the current distributor 4 using a comparator. 13 manually calculates the deviation between the two, and inputs this deviation to the regulator 14, which outputs a voltage signal that makes the input deviation zero. and the regulator 14 to form the current regulation circuit 1
2 is formed.

Further, the output voltage of the No. 1 charger 10 is detected by the voltage detector 16, and the output voltage of the No. 1 charger 10 is maintained at a predetermined value using this and the setting value of the voltage setting device 18. The circuit is configured so that the voltage signal from the above-mentioned current adjustment circuit 12 is input manually as a correction signal.

The No. 2 charger 20 is also equipped with a current detector 21, a current adjustment circuit 22), a voltage detector 26, and a voltage adjustment circuit 27, and the No. 3 charger 30 is also equipped with a current detector 31 and a current adjustment circuit. 32) A voltage detector 36 and a voltage adjustment circuit 37 are attached, and the current command signal from the current distributor 4 is input to each of them.

These three chargers 10, 20, and 30 are connected in parallel to each other to supply DC power to a common load 2, and the load current at that time is detected by the load current detector 3.
The current is sent to the current divider 4.

If we assume that the three chargers 10, 20, and 30 have the same capacity 1, the current divider 4 manually calculates the load current detected by the load current detector 3, divides it into three equal parts, Current adjustment circuit 12.22. of each charger with each as a current command value.
Output to 32.

Each charger 10.20.30 has its own voltage regulation circuit 1
7, 27.37 maintains the output voltage at a predetermined value, but there is a slight difference in the value of each output voltage, and due to this voltage difference, the However, in the present invention, each charger is equipped with a current adjustment circuit,
The voltage signal output from this current adjustment circuit is input to the voltage adjustment circuit as a correction signal, so that the actual current value output from each charger and the current command value output from the current divider 4 are Since the output voltage is adjusted so as to make the deviation zero, it is possible to prevent imbalance in the output current between each charger.

FIG. 2 is a graph showing the output voltage and output current of each charger in the example circuit shown in FIG. 1, and FIG. ) is the total output current I, +I2++3 of each charger, FIG. 2 (c) is the output current 11 of the No. 1 charger 10, and FIG. FIG. 2 (e) shows the output current I3 of the No. 3 charger 30, respectively.

As is clear from FIG. 2, by applying the present invention, the output voltage of each charger is adjusted so that the output current of each charger becomes equal, so the output voltage of each charger becomes equal ( (See Figure 2 (A)) Therefore, each charger increases or decreases its output current at the same rate in response to variations in load current, and the variation in output voltage is also zero.

In the example circuit shown in FIG. 1, three chargers 10
．． It is assumed that 20 and 30 have the same capacity, but when these capacities 1 are different, the current command value output by the current distributor 4 may be distributed in proportion to the capacity. That is, the load current is I, and the capacity of the No. 1 charger 10 is P.
8. When the capacities of the No. 2 charger 20 and the No. 3 charger 30 are Pi and Ps, respectively, the current command 1st shift 'I+'2+'3 given to each charger becomes the following equations.

P.

In other words, the current divider 4 has the above (1), (2), (
It is sufficient to configure the circuit so as to output the calculation result of equation 3), and as long as the above equation is satisfied, it goes without saying that even if the chargers have the same capacity, they can be used as they are.

〔Effect of the invention〕

According to the present invention, when operating a plurality of sets of charging means equipped with a voltage regulating means and supplying constant voltage DC power to a load while regulating the output voltage thereof to a constant value, the voltage regulating means is connected in parallel. A current adjustment means is provided at the front stage so that the actual current value output by each charging means matches the current command value from the current distribution means, thereby preventing the output currents of each charging means from becoming unbalanced. However, this current distribution means distributes the total load current so that the current command value is proportional to the capacity of each charging means. As a result, the load sharing among the plurality of charging means operating in parallel is balanced, so that it is possible to eliminate the problem of concentration of load on a specific charging means, resulting in a shortened lifespan.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the output voltage and output current of each charger in the embodiment circuit shown in FIG. It is a graph showing the current shared by each charger when conventional chargers equipped with a limiter function and output constant voltage DC power are operated in parallel. 2 load, 3 load current detector, 4 current distributor, 10
-1 Charger, 11.21.31 Current detector, 12
)22.32 Current adjustment circuit, 13 Comparator, 14
Regulator, 16.26.36 Voltage detector, 17.
27.37 Voltage adjustment circuit, 18 Voltage setting device, 2
No. 02 charger, No. 30-3 charger.

Claims (1)

[Scope of Claims] 1) A device that operates by connecting a plurality of charging means in parallel, which includes a voltage adjustment means for outputting constant voltage DC power and supplies constant voltage DC power to a load such as a battery, A current distribution means for distributing the current flowing to the load as a current command signal to each charging means, an actual current value outputted by the specific charging means, and a current command value distributed from the current distribution means to the specific charging means. A current adjusting means for comparing and outputting a voltage signal that makes the deviation between the two zero, and a circuit for inputting the voltage signal from this current adjusting means as a correction signal to the voltage adjusting means of the specific charging means are connected to each charging unit. A load current automatic balancing circuit for a charging means, characterized in that the means is provided with a load current automatic balancing circuit. 2) In the load current automatic balancing circuit according to claim 1, the current distribution means is configured to output a current command signal having a magnitude proportional to the capacity of each charging means. A load current automatic balancing circuit for a charging means, characterized in that: