JPH0775470B2 - Switching power supply control circuit - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a stabilized DC power supply device having a plurality of DC-DC converters, and more particularly to improvement of a circuit that controls switching.

[Prior art]

One method of constructing a stabilized DC power supply device having a large capacity or multiple outputs is to combine a plurality of DC-DC converters. In such a power supply, the switching frequency is used in synchronization to prevent the occurrence of beats. However, when noise generated from each DC-DC converter is superposed, the burden of measures against EMI (electromagnetic interference) increases, so the inventors of the present invention output signals of these DC-DC converters (referred to as a supply signal to a transformer, (Before rectifying and smoothing) are operated so as to have opposite phases to reduce noise. FIG. 5 is a configuration block diagram used in a conventional DC-DC converter. In the figure, ICs 1 and 2 are switching regulator control ICs (for example, elements such as TL494), which have two transistor switches built therein and a frequency synchronization signal terminal C _T. Driving signals φ11, 12 are supplied to the DC-DC converter 1 from each switch, and driving signals φ21, 22 are supplied to the DC-DC converter 2. Reference numeral 10 is a rectifying / smoothing circuit that obtains a DC unstabilized voltage from a commercial AC power source. 20 is a half-bridge type converter in which two switching elements SW are provided for the transformer T,
30 is a rectifying / smoothing circuit, which is a half-bridge converter 20
There are two systems corresponding to each other. 40 is a control circuit, which outputs the input voltage Vin as the regulated voltage Vout1, 2 as a whole.
It is a DC-DC converter. 50 is the drive signal φ11,12,
It is a filter that removes the signal components related to the switching frequency sw of 21,22. Next, details of the half-bridge converter 20 will be described.
One end of the capacitor C11 is connected to the + side of the input voltage Vin,
The other end is connected to the capacitor C12, and the other end of the other capacitor C12 is connected to one side of the input voltage Vin. The switch element SW11 is, for example, a field effect transistor.
It is composed of FET, and its drain is + of input voltage Vin.
Of the switching element SW12, and the source of the switching element SW12 is connected to one side of the input voltage Vin. Switch element SW11,12
An on / off control signal is supplied from the control circuit 30 to the gate of. Further, since the switch elements SW11, 12 generate heat, heat sinks HS11, 12 (not shown) are attached for cooling, and a capacitance is formed and grounded between them. Preferably, a diode D (not shown) is attached between the drain and source of the switch elements SW11, SW12 in order to prevent reverse current flow. One end of the primary side of the transformer T1 is coupled to the connection point of the switch elements SW11 and 12, and the other end is coupled to the connection point of the capacitors C11 and C12. The secondary side of the transformer T1 is connected to the rectifying / smoothing circuit 30 to stabilize the voltage Vout.
Output 1 Regarding the second system of the half-bridge type converter 20, the subscripts 11 and 12 attached to the above components are replaced with 21, 22 and transformers T1 and T2. The operation of the device configured as described above will be described next. By operating the first and second DC-DC converters in opposite phases by the test study by the present inventors, the switch element SW and the heat sink HS are passed through. It has become clear that the common current flowing through it decreases.

[Problems to be Solved by the Invention]

By the way, the frequency synchronization signal supplied from the control circuit 40 to the C _T terminals of the control ICs 1 and 2 has not been able to perfectly synchronize the control ICs 1 and 2. For example, FIG. 6 shows drive waveforms for a half-bridge converter called push-pull mode, where (A) shows in-phase and (B) shows anti-phase waveforms. With respect to the switching frequency 2sw, the supply to the transistor built in each control IC is alternated, and the waveform of the output frequency of sw is provided to the transformer T. In this case, for each of the two controls
There is a problem that it is not possible to control whether IC1 and IC2 are in phase or in reverse phase. Similarly, Fig. 7 shows on / o called single-ended mode.
Drive waveform for n converter (only one switching element SW for transformer T), (A) in phase,
(B) shows a reverse-phase waveform. Switching frequency
With respect to sw, the waveform of the output frequency of sw is provided to the transformer T. In this case, between the two control ICs 1 and 2,
There was a problem that in-phase operation was possible, but reverse phase operation was not possible. The present invention solves such a problem, and for each control
An object of the present invention is to provide a control circuit for a switching power supply device that can reliably control the phase state between ICs.

[Means for solving problems]

The power supply control circuit of the first invention which achieves such an object is provided with a synchronization signal of a predetermined switching frequency (2sw) and first and second switches, and switches these two switches in synchronization with the synchronization signal. A plurality of signal output circuits that turn on and off, a first control signal that receives the synchronization signal and that turns on and off at a frequency (sw) that is half the switching frequency, and a second control that is out of phase with the first control signal. A control circuit that outputs a signal, and controls the first switch that is a part of the signal output section and the second switch that is the remaining part of the signal output section by the first control signal, and the switching frequency sw in phase with each other. Output a first switch control signal from the first switch, and control the second switch which is a part of the signal output section and the first switch which is the remaining part of the signal output section by the second control signal. Switch system In which the more the enable / disable circuit which outputs a second switch control signal of the switching frequency sw is a signal with opposite phase. The switching power supply device to be controlled includes a plurality of transformers whose primary side is connected to a DC power supply and whose secondary side is connected to a load, and switches mounted on the respective primary sides of these transformers and turned on / off by a switch control signal. It consists of elements and a grounded heat sink for cooling these switching elements. Further, the relationship between the power supply control circuit and the switching power supply device is such that a part of the switch element SW is driven by the first switch control signal and the rest of the switch element SW is driven by the second switch control signal. It is characterized by having done. The power supply control circuit of the second invention which achieves such an object is provided with a synchronization signal of a predetermined switching frequency (2sw) and first and second switches, and switches these two switches in synchronization with the synchronization signal. A plurality of signal output circuits that are turned on and off, a first switch that is a part of the signal output unit and a second switch that is the remaining portion of the signal output unit are input via diodes, and the connection with the ground is turned on and off by the synchronization signal. The third switch, the second switch that is a part of the signal output section, and the first switch that is the remaining part of the signal output section are input via the diode, and the connection with the ground is turned on / off by the synchronization signal. An enable / disable circuit including a fourth switch, and a third switch which is a part of the signal output unit and the signal. The first switch control signal having the switching frequency sw in phase with each other is output from the second switch of the remaining part of the force section, and the second switch and the signal output section which are part of the signal output section are output by this fourth switch. The remaining first switch outputs a second switch control signal having a switching frequency sw that is in anti-phase with the first switch control signal. The relationship between the switching power supply device and the power supply control device of the second invention is the same as that of the first invention.

[Action]

Each component of the first invention has the following action. The signal output circuit has first and second switches, respectively,
It operates according to the synchronization signal, but each signal output circuit cannot be operated in reverse phase. Therefore, the enable / disable circuit controls the switch output of the signal output circuit to output the first and second switch control signals having mutually opposite phases. When these switch control signals are used in the switching power supply device, noise corresponding to the switching frequency sw is canceled. Each constituent element of the second invention has a different structure to achieve the same object as that of the first invention.

【Example】

The first and second inventions will be described below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the first invention. In FIG. 1, components having the same functions as those in FIG. 5 are designated by the same reference numerals, and a description thereof will be omitted. The DC-DC converter to be controlled will be described with two or a larger natural number n. In the figure, 60 is a signal output circuit, which is provided in a one-to-one correspondence with the number of channels n of the DC-DC converter. 70
Is an output pattern control circuit that supplies a control signal, and 80 is an enable / disable circuit that inputs a signal output from the signal output circuit 60 and converts it into a switch control signal according to the control signal supplied from the output pattern control circuit 70. .
These form a power supply control circuit. The signal flow will be described. The synchronization signal (frequency 2sw) supplied from the control circuit 40 is supplied to each signal output circuit 60 and also to the output pattern control circuit 70. The signal output circuit 60 outputs a signal of frequency 2sw to the enable / disable circuit 80. Then, according to the control signal of the output pattern control circuit 70, two systems of signals having frequencies opposite to each other in frequency sw are supplied to the switch element SW20. FIG. 2 is a circuit diagram of a main part of the apparatus shown in FIG. For the signal output circuit 60 and the output pattern control circuit 70, for example, the control IC (TL494) described above may be used. Here, the enable / disable circuit 80 is a combination of the signal line of the signal output circuit 60 and the signal line of the output pattern control circuit 70. The first switch element Tr of the output pattern control circuit 70
The emitter output of 31 is connected to the collector terminals of the first switch element Tr11 of the first signal output circuit 60 and the second switch element Tr22 of the second signal output circuit 60 via resistors R1 and R4, respectively. There is. Similarly, the emitter output of the second switch element Tr32 of the output pattern control circuit 70 is the collector of the second switch element Tr12 of the first signal output circuit 60 and the first switch element Tr21 of the second signal output circuit 60. The terminals are connected via resistors R2 and R3, respectively. A switch control signal φ11 is output from the first switch element Tr11 of the first signal output circuit 60 as an emitter output,
Similarly, the switch control signals φ12, 21, 22 are output from the other switch elements Tr12, 21, 22 as emitter outputs. FIG. 3 is a waveform diagram for explaining the operation of the apparatus shown in FIG.
The sync signal is supplied to the sync terminal C _T at a frequency of 2 sw. Then, the switching elements Tr31, 32 of the output pattern control circuit 70
Operates in push-pull mode, it outputs complementary signals of frequency sw. Further, since the switching elements Tr11, 12, 21, 22 of the signal output circuit 60 are operated in the single end mode, they are synchronized signals of frequency 2sw. As a result, the switch control signals φ11,22 are
The switch control signals φ12,21 have the synchronized frequency sw, and have a phase opposite to that of the switch control signals φ11,22. When such a switch control signal is supplied to the DC-DC converter, electromagnetic noise is reduced. FIG. 4 is a block diagram of the essential parts showing an embodiment of the second invention, in which the DC-DC converter is omitted. The same operation as that of the first invention is realized by another configuration. In the figure, the signal output circuit 60 shows all switching elements Tr.
The collector terminals of 11,12,21,22 are pulled up,
It operates in single-ended mode as shown in FIG. The enable / disable circuit 90 is a switch element
The emitter outputs of the Trs 11, 12, 21, 22 are input with low impedance and output as switch control signals φ11, 12, 21, 22. That is, as the collector input of the third switch element Tr31 of the enable / disable circuit 90, the emitter output of the first switch element Tr11 of the first signal output circuit 60 and the second
The emitter outputs of the second switch element Tr22 of the signal output circuit 60 are guided via the diodes D1 and D2, respectively. Similarly, as the collector input of the fourth switch element Tr32 of the enable / disable circuit 90, the emitter output of the second switch element Tr12 of the first signal output circuit 60 and the second
The emitter outputs of the first switch element Tr21 of the signal output circuit 60 are guided via the diodes D3 and D4, respectively. In addition, the switch elements Tr31,3 of the enable / disable circuit 90
The operation of No. 2 is the same as that of the output pattern control circuit 70 of FIG. Therefore, the target switch control signals φ11, 12, 21, 22 can be obtained. Here, the reason why the diodes D1 and 2 are interposed is to change the pulse widths of the switch control signals φ11 and φ22 independently. Similarly, the reason that the diodes D3 and 4 are interposed is the switch control signal. This is because the pulse widths of φ12 and φ21 are changed independently. By doing so, the limitation of the operation of the control circuit 40 is relaxed, and the preferable characteristics of the DC-DC converter can be obtained. It should be noted that, in the above-described embodiment, the description has been made with respect to the two DC-DC converters, but the present invention is not limited to this, and even if there are three or more DC-DC converters, the same phase and the opposite phase are provided between them. It may be one that is operated in two groups.

【The invention's effect】

As described above, the present invention has the following effects. (1) Using a common synchronization signal, the phase state between the control ICs can be ensured and in-phase and anti-phase can be easily distinguished. (2) When the switching regulator control IC is used for the signal output circuit 60 and the output pattern control circuit 70 as in the embodiment, the parts are shared and the manufacturing is facilitated.
In the push-pull mode, two switch elements are prevented from being turned on at the same time, and no double pulse is generated. (3) When the present invention is applied to an on / on converter, the signals shown in FIG. 7 (B) are supplied to a plurality of converters, the switching timings are shifted to disperse the peaks of the input current, and the input current ripples. Can be reduced. Furthermore, when using the outputs of multiple converters in tandem,
The output voltage ripple is also reduced.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the first invention,
FIG. 2 is a circuit diagram of essential parts of the device of FIG. 1, FIG. 3 is a waveform diagram for explaining the operation of the device of FIG. 2, and FIG. 4 is a structural block diagram of essential parts showing an embodiment of the second invention. It is a figure. FIG. 5 is a block diagram of a structure used in a conventional DC-DC converter, FIG. 6 is a drive waveform for a half-bridge type converter called push-pull mode, and FIG. 7 is an on / on converter called single-ended mode. In the drive waveform, (A) shows an in-phase waveform and (B) shows an anti-phase waveform. 10 ... Rectification smoothing circuit, 20 ... DC-DC converter, 30 ... Smoothing circuit, 40 ... Control circuit, 50 ... Filter, 60 ... Signal output circuit, 70 ... Output pattern control circuit, 80, 90 ... Enable /
Disable circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunobu Iwata 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. (56) Reference JP-A-60-106361 (JP, A)

Claims (2)

[Claims] 1. A synchronizing signal having a predetermined switching frequency (2sw), a plurality of signal output circuits which are provided with first and second switches and turn on and off these two switches in synchronization with the synchronizing signal, and the synchronizing signal. And a control circuit that outputs a first control signal that is turned on and off at a frequency (sw) that is half the switching frequency, and that outputs a second control signal that is in anti-phase with the first control signal. The first part of the signal output unit is controlled by the control signal.
And the second switch, which is the rest of the signal output section, to control the first switching frequency sw of the same phase.
Of the second switch control signal, and controls the second switch which is a part of the signal output section and the first switch which is the remaining part of the signal output section by the second control signal to control the first switch. A power supply control circuit comprising an enable / disable circuit that outputs a second switch control signal having a switching frequency sw that is in opposite phase to the signal, the primary side of which is connected to the DC power supply and the secondary side of which is connected to the load. A switching power supply device comprising a plurality of transformers, switch elements mounted on respective primary sides of the transformers and turned on / off by a switch control signal, and a grounded heat sink for cooling these switch elements, The switch element SW according to the switch control signal of 1.
A part of the switching power supply device is driven, and the remaining part of the switch element SW is driven by the second switch control signal. 2. A plurality of signal output circuits which are provided with a synchronizing signal of a predetermined switching frequency (2sw) and first and second switches, and which turn on and off these two switches in synchronization with the synchronizing signal, said signal output. A third switch whose part of the first switch and the remaining second switch of the signal output part are input via a diode and whose connection to the ground is turned on and off by the synchronization signal; and the signal output part. Of the second switch, and a fourth switch to which the first switch of the remaining part of the signal output section is input via a diode and whose connection to ground is turned on and off by the synchronization signal. An enable circuit, and the third switch connects the first switch, which is a part of the signal output section, and the second switch, which is the remaining part of the signal output section, to each other. The first switch control signal having the in-phase switching frequency sw is output, and the fourth switch outputs the first switch from the second switch which is a part of the signal output section and the first switch which is the rest of the signal output section. Of a plurality of transformers, the primary side of which is connected to the DC power supply and the secondary side of which is connected to the load. And a switching power supply device that is mounted on the primary side of each of these transformers and is turned on / off by a switch control signal, and a grounded heat sink that cools these switching devices. The switch element SW depending on the signal
A part of the switching power supply device is driven, and the remaining part of the switch element SW is driven by the second switch control signal.