JPH08126314A - Multi-output controlled power supply - Google Patents

Abstract

PURPOSE: To suppress the output voltage fluctuation of a plurality of chopper circuits which output prescribed voltages by inputting the DC power source voltage from a converter circuit to the chopper circuits. CONSTITUTION: When a prescribed voltage is supplied to a plurality of loads RL11, RL12, and RL13 by connecting a plurality of chopper circuits 101, 102, and 103 to the output of a converter circuit 100, the disconnecting/connecting periods of switching transistors Q11, Q12, and Q13 are changed at every chopper circuit. Therefore, the state where the turn-on timing of switching elements in the chopper circuits overlap upon another does not continue and the output voltage fluctuation of each chopper circuit can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-output control power supply device for supplying power to a plurality of loads by a plurality of chopper circuits.

[0002]

2. Description of the Related Art A general structure of a multi-output control power supply device for supplying power to a plurality of loads by chopper control is shown in FIG. 7 as a block diagram. In FIG. 7, the converter circuit is composed of an AC / DC converter or a DC / DC converter, and acts as a main power supply circuit that outputs a constant power supply voltage Vo. Each chopper circuit 101, 102,
Reference numeral 103 denotes switching transistors Q11, Q12, which switch the output voltage Vo of the converter circuit, respectively.
Q13, a switching control circuit 11, 12, 13 for controlling the on / off of the switching transistor, a choke coil L11, L12, L13 for smoothing the power supply voltage interrupted by the on / off of the switching transistor, and a smoothing circuit including smoothing capacitors C11, C12, C13. It consists of Each switching control circuit 11, 12, 1
A control signal 3 is input to control the on-duty ratio of the switching transistor to stop the output voltage or control the voltage. With this configuration, each chopper circuit 10
1, 102 and 103 receive the output voltage Vo of the converter circuit, step down this voltage to a predetermined voltage, and load RL11 and RL.
12 and RL13 function as a sub-power supply circuit that outputs a predetermined voltage.

[0003]

In the multi-output control power supply device shown in FIG. 7, each chopper circuit has the same configuration and the switching transistors have substantially the same intermittent period. However, since each chopper circuit needs to drive each load independently, each switching control circuit is configured to control each switching transistor independently. Therefore, the switching timing of each switching transistor is not synchronized. Therefore, even if the circuit configurations of the chopper circuits are the same, an error occurs in the intermittent period of the switching transistor due to a slight difference in the circuit constant, and the ON timing of the switching transistor may or may not overlap. An example is shown in FIG.

FIG. 5A shows a case where the on timings of the two switching transistors Q11 and Q13 overlap.
(B) shows three switching transistors Q11, Q12,
The graph shows changes in the output current Io and the output voltage Vo of the converter circuit when Q13 overlaps. (A)
In the case shown in (1), the load current Io for the converter circuit is larger in the period in which the switching transistors Q11 and Q13 are on than in the period in which Q12 is on. Although it depends on the configuration of the converter circuit, in general, its output current Io
Becomes larger, the output voltage Vo decreases due to the discharge of the smoothing circuit, the voltage drop due to the line, and the like. Therefore, the output voltage Vo of the converter circuit at the on-timing of the switching transistors Q11 and Q13 becomes lower than Vo at the on-timing of Q12. As a result, in the chopper circuits 101 and 103, the energy stored in the smoothing circuit when the switching transistors Q11 and Q13 are turned on decreases.

As shown in FIG. 5B, when the ON timings of the switching transistors Q11, Q12, Q13 are aligned, the above-mentioned point becomes remarkable, and the output of the converter circuit at the ON timings of Q11, Q12, Q13. The voltage Vo further decreases, and the chopper circuits 101, 102, 103
The energy stored in the smoothing circuit will decrease.

The smaller the error or fluctuation in the intermittent period of the switching transistors of each chopper circuit, the smaller the on-timing relationship (deviation relationship) of each switching transistor.
Is long lasting. Therefore, if there is little variation in the circuit constants of the switching control circuits in each chopper circuit, the degree of overlap of the ON timings of the switching transistors changes gently, and in the middle of the change,
The state shown in (A) or (B) lasts for a relatively long time. This is shown in FIG.

In FIG. 6, the ON timings of the three switching transistors do not overlap in the period A, and the ON timings of the two switching transistors Q11 and Q13 overlap in the period B. The ON period and the C period are periods in which the ON timings of the three switching transistors Q11, Q12, and Q13 overlap. When the load of each chopper circuit is the same, as shown in the figure, during the period A, the energy accumulated in the smoothing circuit during the ON period of each switching transistor in each chopper circuit becomes equal, and their output voltage V1, V2 and V3 are equal. After that, in the period B in which the on timings of the switching transistors Q11, Q12, Q13 are gradually deviated and the on timings of Q11, Q13 overlap, the energy accumulated in the smoothing circuits in the chopper circuits 101, 103 decreases, so V1,
V3 decreases. On the other hand, after Q11 and Q13 are turned off, only Q12 is turned on with a sufficient delay, so that the output voltage Vo of the converter circuit (that is, the input voltage of the chopper circuit 102) Vo when Q12 is turned on becomes high and is accumulated in the smoothing circuit in the chopper circuit 102. The energy applied increases and its output voltage V2 increases. After that, a period C in which the on-timing of the three switching transistors Q11, Q12, and Q13 overlaps
Then, since the energy accumulated in the smoothing circuits in the chopper circuits 101, 102, 103 decreases, the output voltages V1, V2, V3 of the chopper circuits 101, 102, 103 decrease.

As described above, in the above-described example, the output voltage V1 of the chopper circuit depends on the overlap of the ON timings of the three switching transistors Q11, Q12, and Q13.
V2 and V3 will change. If the capacity of the converter circuit 100 shown in FIG. 7 is increased, the fluctuation rate of the output voltages V1, V2 and V3 of each chopper circuit can be suppressed to a low level, but as a result, the converter circuit 100 becomes large. In particular, the loads RL11, RL12, RL13 are exciting coils of the electromagnetic switch, and when they are activated, a large current is passed through them.
After the response of the switch is completed, the holding current required to maintain that state is applied to increase the response speed of the electromagnetic switch and suppress the heat generation of the exciting coil. RL11, RL12, R
Even though the load supply current to L13 is the holding current or 0, the converter circuit 100 must be provided with the power capacity required to start all the loads RL11, RL12, RL13 at the same time. Further, if the capacity of the converter circuit 100 is increased in preparation for the decrease of the output voltage Vo of the converter circuit 100 due to the above-mentioned problem, the utilization efficiency of the converter circuit 100 will be further decreased.

An object of the present invention is to suppress the fluctuation of the input power supply voltage to the chopper circuits without inputting the DC power supply voltage output from the converter circuit and synchronizing a plurality of chopper circuits outputting the predetermined voltage. An object of the present invention is to provide a multi-output control power supply device that suppresses fluctuations in the output voltage of each chopper circuit.

[0010]

A multi-output control power supply device of the present invention receives a converter circuit for inputting an AC power supply or a DC power supply to generate a DC power supply voltage, and a DC power supply voltage output by the converter circuit. And a plurality of chopper circuits that output a predetermined power supply voltage to the load. As described in claim 1, the switching period of each switching element of the plurality of chopper circuits is made different for each chopper circuit.

Further, according to the present invention, when the applied voltage to the load of each chopper circuit is changed, the intermittent period of each switching element is different for each chopper circuit. The switching control circuit of the circuit controls the output voltage of each chopper circuit by controlling the on-duty ratio while keeping the intermittent period of each switching element constant.

[0012]

In the multi-output control power supply device according to claim 1 of the present invention, the converter circuit inputs the AC power supply or the DC power supply and supplies the DC power supply voltage to each chopper circuit, and the switching element of each chopper circuit is switched. By the control of the control circuit, the input DC power supply voltage is interrupted,
The smoothing circuit smoothes the intermittent DC power supply voltage to generate a predetermined power supply voltage determined by the input power supply voltage to the chopper circuit and the on-duty ratio of the switching element. The intermittent period of the switching element of each chopper circuit differs for each chopper circuit.

Here, regarding the three chopper circuits,
FIG. 2 shows the relationship between the output current and the output voltage of the converter circuit when the intermittent period of each switching element is different. In this example, switching transistors Q11 and Q1
2, the intermittent period T11, T12, T13 of Q13 is T11>T12> T1
Due to the relationship of 3, the intermittent cycle is set short. Therefore, 3
The timing when three switching elements Q11, Q12, and Q13 turn on at the same time, the timing when two of them turn on at the same time, and the timing when only one turns on appear substantially randomly. Therefore, unlike the example shown in FIG. 5, the state in which the output voltage Vo of the converter circuit decreases every time a certain switching element is turned on does not continue, and fluctuations in the output voltage of each chopper circuit are suppressed. .

In the multi-output control power supply device according to claim 2,
The on-duty ratio is controlled while the intermittent period of each switching element remains constant, so the output voltage of the chopper circuit is controlled while maintaining the relationship that the intermittent period of each switching element differs for each chopper circuit. . Therefore, even if the output voltage of each chopper circuit is changed,
The condition that the ON timings of the plurality of switching transistors remain the same does not occur, and the above-mentioned problem does not occur.

[0015]

FIG. 1 shows the configuration of a multi-output control power supply device according to an embodiment of the present invention. In FIG. 1, 100 is an AC power supply A
A converter circuit for inputting C to generate a DC power supply voltage Vo, 101, 102, 103 are converter circuits 100
Input the DC power supply voltage Vo output from the load RL1
1, RL12, RL13 for power supply voltage V1, V respectively
It is a chopper circuit that outputs 2, V3. The converter circuit 100 is a forward converter circuit, and includes a converter transformer Tr and a switching transistor Q.
1. A switching control circuit 1 including a separately excited oscillation circuit or a self-excited oscillation circuit, a rectifier diode D1, a choke coil L1, a smoothing capacitor C2, and a flywheel diode D2. Further, the diode bridge DB rectifies the AC power supply AC, and the capacitor C1 smooths it and supplies it to the primary side of the converter transformer Tr.

The operation of the converter circuit 100 is as follows. First, when the switching transistor Q1 is turned on by the output of the switching control circuit 1, a primary current flows in the primary side of the converter transformer Tr. As a result, the electromotive force generated on the secondary side is charged to the choke coil L1 and the smoothing capacitor C2 and is supplied to the load side. After that, when the switching transistor Q1 is turned off, the energy accumulated in the choke coil L1 is supplied to the load side via the flywheel diode D2.

Each chopper circuit 101, 1 shown in FIG.
02 and 103 are step-down chopper circuits,
Switching transistors Q11, Q12, Q13 and switching control circuits 11, 1 for controlling these transistors, respectively.
2, 13, choke coils L11, L12, L13, smoothing capacitors C11, C12, C13 and flywheel diodes D11, D12, D13. The operation of these chopper circuits is as follows. Taking the chopper circuit 101 as an example, first, when the switching control circuit 11 turns on the switching transistor Q11, the input energy of the DC power supply is charged in the choke coil L11 and the smoothing capacitor C11 and is supplied to the load RL11. . After that, when the switching control circuit 11 turns off the switching transistor Q11, the energy accumulated in the choke coil L11 is supplied to the load RL11 via the flywheel diode D11. Assuming that the on-duty ratio of the switching transistor Q11 is d11, the output voltage V11 to the load RL11 is V11 = Vo *
It is expressed by the relationship of d11.

FIG. 2 is a diagram showing the state of each part shown in FIG. 1 and changes in the waveform. In FIG. 2, Q11, Q12, Q13
In the figure, the high level is on and the low level is off. Io and Vo are output current and output voltage of the converter circuit 100 shown in FIG. As shown in FIG. 2, as the number of switching transistors that are turned on at the same time increases, the output current Io of the converter circuit 100 increases, and the output voltage Vo decreases accordingly. However, the overlapping degree of the ON timings of the three switching transistors does not coincide with each intermittent period of each switching transistor. Looking at each switching transistor, the output voltage Vo of the converter circuit is changed every time a certain switching transistor is turned on. The state that the voltage drops each time does not continue, and thus the fluctuation of the output voltage of each chopper circuit is suppressed. As a result, as shown in FIG. 3, the output voltages V1, V2 and V3 of the chopper circuits are output.
Maintains an almost constant voltage.

Load RL of each chopper circuit shown in FIG.
When 11, RL12, RL13 are exciting coils of the electromagnetic switch, the switching control circuits 11, 12, 13 turn on the switching transistors Q11, Q12, Q13 at the time of starting the electromagnetic switch according to a control signal given from the outside. The duty ratio is increased and the on-duty ratio is reduced after completion of the response. Here, an example of the base signal for the switching transistor when the on-duty ratio is changed is shown in FIG.
Shown in In FIG. 4, B1, B2, and B3 are base voltages given to the switching transistors Q11, Q12, and Q13 by the switching control circuits 11, 12, and 13 when the starting voltage is output to the exciting coil of the electromagnetic switch.
Reference numerals 1 ', B2' and B3 'are base voltages given to the respective switching transistors by the switching control circuits 11, 12 and 13 when the holding voltage is applied to the exciting coil. In this way, the intermittent period T11, T of each switching transistor
The on-duty ratio is controlled while keeping T12 and T13 constant. As a result, even if the on-duty ratio of each switching transistor is changed independently, the on-timings of a plurality of switching transistors overlap each other,
Such a state does not continue, and the output voltages V1, V2 and V3 are correctly maintained at the predetermined starting voltage or holding voltage.

[0020]

According to the multi-output control power supply device according to the first aspect of the present invention, the state in which the output voltage of the converter circuit drops every time the switching element of a certain chopper circuit is turned on does not continue. The fluctuation of the output voltage of each chopper circuit can be suppressed.

According to the multi-output control power supply device according to the second aspect, even if the output voltage is changed by changing the on-duty ratio of each switching element of each chopper circuit, the on-timing of a plurality of switching transistors is in agreement. Does not occur, and a predetermined power supply voltage can be stably supplied to each load.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a multi-output control power supply device that is an embodiment of the present invention.

FIG. 2 is a diagram showing a state and a waveform of each part in FIG.

FIG. 3 is a diagram showing a relationship between a state of a switching transistor in each chopper circuit and an output voltage of each chopper circuit.

FIG. 4 is a diagram showing a waveform of a base voltage for each switching element when the on-duty ratio is changed.

FIG. 5 is a diagram showing a relationship between a state of a switching transistor and an input power supply voltage for a chopper circuit in a conventional multi-output control power supply device.

FIG. 6 is a diagram showing a relationship between a state of a switching transistor of each chopper circuit and an output voltage of each chopper circuit in a conventional multi-output control power supply device.

FIG. 7 is a diagram showing a configuration of a conventional multi-output control power supply device.

[Explanation of symbols]

 1-Switching control circuit 11, 12, 13-Switching control circuit RL11, RL12, RL13-Load 100-Converter circuit 101, 102, 103-Chopper circuit

Claims (2)

[Claims] 1. A switching element for inputting the DC power supply voltage and connecting and disconnecting the DC power supply voltage to a converter circuit for inputting an AC power supply or a DC power supply to generate a DC power supply voltage, and the switching circuit. In a multi-output control power supply device connected with a plurality of chopper circuits consisting of a switching control circuit for controlling on / off of an element and a smoothing circuit for smoothing the interrupted DC power supply voltage, each switching element of the switching control circuit A multi-output control power supply circuit characterized in that an intermittent cycle is made different for each switching control circuit. 2. The switching control circuit controls the output voltage of each chopper circuit by controlling the on-duty ratio while keeping the intermittent period of each switching element constant. Multi-output control power supply.