JPH0648390U - Boost chopper circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a boost chopper circuit in which the hunting phenomenon does not occur due to the output ripple from the DC power supply. A summing inverting amplifier 14 for adding a voltage corresponding to a ripple of a DC input current to a voltage corresponding to a DC output voltage, and a comparator 8 for comparing the summed voltage obtained from the summing inverting amplifier 14 with a triangular wave are provided. The switching element 2 is controlled by the pulse width control signal from the comparator 8 to control the DC output voltage and the ripple of the DC input current to constant values. [Effect] Even if a rectifier is used as a DC power supply and the output ripple of the rectifier increases as the load current increases, this output ripple is detected as the ripple of the DC input current and the switching element is controlled. It is possible to prevent the hunting phenomenon from occurring.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a step-up chopper circuit, and more specifically, to a step-up chopper circuit capable of suppressing an increase in ripple of a DC input current due to an increase in its load current.

[0002]

[Prior art]

 As shown in FIG. 2, the conventional step-up chopper circuit includes a DC power supply 1, a series circuit of a choke coil 3 and a switching element 2 connected between the DC power supply 1, and a switching circuit connected in parallel with the switching element 2. It is composed of a diode 5 and a capacitor 6 connected in series, and is configured to supply a DC output to a load 4 connected between the terminals of the capacitor 6. By turning on the switching element 2, a DC output is generated. The voltage of the power supply 1 is applied to the choke coil 3 to store energy in the choke coil 3, and the switching element 2 is turned off to transfer this energy to the capacitor 6 via the diode 5 to change the voltage across the terminals of the capacitor 6. It is higher than the voltage of the DC power source 1.

To control the switching element 2 to be turned on and off, the voltage across the terminals of the capacitor 6, that is, the DC output voltage is converted to a corresponding voltage by the resistor 10, and then the inverting amplifier 7 is used to control the comparator 8. The pulse width control signal is output by comparing the triangular wave input to the non-inverting input terminal with the triangular wave input to the inverting input terminal, and the driving circuit 9 amplifies the pulse width control signal.

That is, when the DC output voltage rises, the output voltage of the inverting amplifier 7 falls, so that the H level period of the output of the comparator 8 is shortened, the ON period of the switching element 2 is shortened, and the choke coil 3 The energy stored in the output voltage decreases and the DC output voltage decreases, and when the DC output voltage decreases, the output voltage of the inverting amplifier 7 increases, so that the H level period of the output of the comparator 8 becomes longer and the switching becomes longer. The ON period of the element 2 becomes longer, the energy accumulated in the choke coil 3 increases, and acts to increase the DC output voltage, and the DC output voltage is controlled to be constant.

[0005]

[Problems to be solved by the device]

 In the conventional boost chopper circuit described above, if the output of the rectifier is used as the DC power supply 1, the output ripple of the rectifier increases when the load current increases, and the input voltage and input current of the boost chopper circuit fluctuate at low frequencies. There was a problem of causing a hunting phenomenon.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a series circuit of a DC power supply, a choke coil connected between the DC power supplies and a switching element, and a series circuit of a diode and a capacitor connected in parallel with the switching element. In a step-up chopper circuit that obtains a DC output from between the terminals of this capacitor, a summing inverting amplifier that adds and inverts the corresponding voltage of the DC input current ripple to the corresponding voltage of the direct current output voltage A comparator for comparing the added voltage obtained from the adding and inverting amplifier with the triangular wave is provided, and the switching element is controlled by the pulse width control signal from the comparator, and the DC output voltage and the DC input current are controlled. It is characterized by controlling ripple and a constant value.

[0007]

[Work]

 Therefore, even if the output ripple of the rectifier increases, this output ripple is detected as the ripple of the DC input current and the on / off of the switching element is controlled, so that the occurrence of the hunting phenomenon can be prevented.

[0008]

【Example】

 FIG. 1 is a circuit diagram of a boost chopper circuit according to the present invention. The parts having the same functions as those in FIG.

The features of the present invention are: a current detector 15 for detecting a ripple of a DC input current, a filter 11 for removing a high frequency component from the ripple detected by the current detector 15, and an output of the filter 11. Is provided with an inverting amplifier 12 and a resistor 13 for converting the corresponding voltage of the ripple to a corresponding voltage of the ripple, and an adding and inverting amplifier 14 for adding the corresponding voltage of the ripple and the corresponding voltage of the DC output voltage. The comparator 8 compares the triangular wave with the triangular wave to obtain a pulse width control signal.

In the boost chopper circuit described above, when the ripple of the DC input current increases, the output voltage of the inverting amplifier 12 decreases, so that the addition voltage obtained from the adding and inverting amplifier 14 increases, which causes the comparator 8 to increase. The H level period of the output becomes longer and the ON period of the switching element 2 becomes longer. Therefore, the peak value of the current flowing from the DC power supply 1 into the step-up chopper circuit increases, the ripple of the DC input current decreases, and the ripple is controlled to be a constant value.

On the contrary, when the ripple of the DC input current is reduced, the ON period of the switching element 2 is shortened and the peak value of the current flowing from the DC power supply 1 into the step-up chopper circuit is reduced, so that the ripple of the DC input current is reduced. It increases and the ripple is controlled to have a constant value.

On the other hand, when the load current increases, the DC output voltage tends to decrease, but this change is transmitted to the summing inverting amplifier 14 via the resistor 10 and prolongs the ON period of the switching element 2. Due to the operation, the peak value of the current flowing from the DC power supply 1 to the boost chopper circuit increases, the energy stored in the choke coil 3 increases, the DC output voltage rises, and the voltage is controlled to a constant value. To be done.

On the contrary, when the load current decreases, the DC output voltage rises and the ON period of the switching element 2 becomes short, so that the peak value of the current flowing from the DC power supply 1 to the boost chopper circuit becomes small, The output voltage drops, and the voltage is controlled to have a constant value.

[0014]

[Effect of device]

 As described above, according to the present invention, when the rectifier is used as the DC power supply, the hunting phenomenon can be prevented even if the load current increases and the output ripple of the rectifier increases.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a boost chopper circuit of the present invention.

FIG. 2 is a circuit diagram of a conventional boost chopper circuit.

[Explanation of symbols]

 1 DC power supply 2 Switching element 3 Choke coil 4 Load 5 Diode 6 Capacitor 7 Inverting amplifier 8 Comparator 11 Filter 12 Inverting amplifier 14 Summing inversion amplifier 15 Current detector

Claims (1)

[Scope of utility model registration request] 1. A DC power supply, and a series circuit of a choke coil and a switching element connected between the DC power supplies,
In a step-up chopper circuit, which is composed of a series circuit of a diode and a capacitor connected in parallel with this switching element, and obtains a DC output from between the terminals of this capacitor, a DC input current of the DC output voltage corresponds to the DC output voltage. An adding and inverting amplifier that adds and inverts the corresponding voltage of the ripple and a comparator that compares the adding voltage obtained from the adding and inverting amplifier with a triangular wave are provided, and the switching element is controlled by a pulse width control signal from the comparator. Control the
A step-up chopper circuit which controls the DC output voltage and the ripple of the DC input current to constant values.