JPS6096175A - Constant-voltage power source - Google Patents

Abstract

PURPOSE:To increase the output capacity and the frequency of a power source by diode-OR connecting the outputs of two feed forward converters, and commonly using a smoothing choke coil. CONSTITUTION:Feed forward converters 1, 2 are controlled at the voltage of an input power source 3 by a signal of a controller 4 to apply the output to a load. The controller 4 is composed of an integrated circuit IC1 for a pulse width modulation switching regulator, and the drive transistors TR1, TR2 of the converters 1, 2 are alternately driven by the output signal. Inverter transformers T1, T3 are alternately driven by the operations of the transistors TR1, TR2, and the outputs are supplied to output smoothing choke coil L1 through the OR connection of output rectifiers D4, D5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to increasing the output capacity of a high frequency switching power supply.

[Prior art]

With the shift to DC drive motors in copying machines, there has been a transition from DC power supply series regulators to switching regulators.

As the trend toward direct current becomes stronger, the output capacity required for direct current power supplies (DC power supplies) is increasing day by day.

Conventionally, methods for increasing output capacity include a bush-pull circuit system, a full bridge circuit system, and the like. However, these methods are not suitable for increasing the frequency of the power supply for the purpose of miniaturizing the power supply.
It is disadvantageous because it is easily unbalanced, and troubles are likely to occur due to biased magnetization of the transformer.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned defects.
It is an object of the present invention to provide a constant voltage power supply device that is compatible with higher output capacity and higher frequency of DC power supplies.

[Structure of the invention]

In the present invention, each drive transistor of two feedforward converters is controlled by one switching regulator, and the outputs of the feedforward converters are diode-OR connected, and a smoothing choke coil is shared.

〔Example〕

The present invention will be explained in detail below based on examples.

In Figure 3, (IJ and (2) are incoming power supplies (3) that have rectified and smoothed AC power with a feedforward converter.
It generates an output whose voltage is controlled by a signal from a control section (4). The control unit (4) is composed of an integrated circuit C1 for a pulse width modulation type switching regulator,
Its output signal is the feedforward converter (1)
, (2) drive transistors TRI and TR2 alternately. The integrated circuit ICI is an existing circuit, and a detailed explanation of its configuration will be omitted.

The conduction width of the drive transistors TRI and TR2 is
The maximum number of transistors is set to 40 in consideration of the storage time of each transistor. Transistor 'rR1, TR2
, the inverter transformers T1 and T2 are driven alternately, and their outputs are supplied to the output smoothing choke coil L1 via the OR connection of the output rectifiers D4 and D5.

The output state of each part has a waveform as shown in FIG.

As can be seen from this waveform diagram, the frequency of the output smoothing choke coil L1 increases to twice the drive frequency of the transformers T1 and T2, and the conduction width also increases to 80 degrees. Therefore, the output voltage of the inverter transformer Tl is only % compared to the conventional configuration of a single feedforward converter, and approximately twice the output can be obtained with the same transformer size.

Further, since the output smoothing choke coil L1 is driven at twice the frequency of a single feedforward converter, it can be made smaller. Therefore, it is possible to downsize the power supply by downsizing and distributing the transformer, and by using low-power drive transistors. Furthermore, in terms of output characteristics, it is also possible to reduce output ripple noise and shorten response time by increasing the frequency.

〔Effect of the invention〕

Since the present invention is constructed as described above, it has the following features.

(1) Since it uses a feedforward converter type, it can handle higher frequencies while suppressing troubles caused by transformer saturation.

(2) Since the output can be driven at a frequency twice the capacity of the drive transistor, the output filter (Ll) can be made smaller.

(3) Since the conduction width of the output can be doubled compared to when it is used alone, the load on the freewheel diode (D6) is reduced.

(4) Higher output capacitance (Regarding 1, since the output load is shared by multiple transistors, it is possible to drive with relatively low power transistors.

(5) Since the output voltage of the transformer is lowered, the reverse withstand voltage of the diodes D4 to D6 can be lowered, and diodes with a faster switching speed can be used accordingly.

(Similar to 61F41, the volume per transformer is reduced, contributing to reduction in size and weight.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIG. 2 is a waveform diagram illustrating the present invention in detail. (11(2)...Feedforward converter (3)...Input power supply section (4)...
Control Department Patent Applicant Fuji Xerox Co., Ltd. Agent Tomohiro Tsuchinaka Patent Attorney Katsuo Narigan

Claims (1)

[Claims] A constant voltage power supply device characterized in that the drive transistors of two feedforward converters are driven alternately, the outputs of the converters are diode-OR connected, and a smoothing choke coil is shared.