JPH0644391U - 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 corresponding voltage of a DC power supply voltage to a corresponding voltage of a DC output voltage, and a comparator 8 for comparing a summed voltage obtained from the adding and 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 DC power supply voltage to constant values. [Effect] Even if a rectifier is used as a DC power supply and the output ripple of the rectifier increases due to an increase in load current, this output ripple is detected as a change in the DC power supply voltage 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 fluctuations in DC power supply voltage due to increase in 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 into a corresponding voltage by the resistor 10 and then compared via the inverting amplifier 7. The pulse width control signal is output by comparing it with the triangular wave input to the inverting input terminal of the input device 8, and the pulse width control signal is amplified by the drive circuit 9. There is.

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, an adding and inverting amplifier that adds and inverts the corresponding voltage of the DC power supply voltage 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 a 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 power supply voltage are It is characterized by controlling to a constant value.

[0007]

[Work]

 Therefore, even if the output ripple of the rectifier increases, this output ripple is detected as a fluctuation of the DC power supply voltage, 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 feature of the present invention is that the voltage of the DC power supply 1 is input to the filter 11, the high frequency component thereof is removed, the voltage is converted to the corresponding voltage through the inverting amplifier 12 and the resistor 13, and then the addition / inverting amplifier 14 is used. Is added to the corresponding voltage of the DC output voltage, and the obtained added voltage is compared with the triangular wave by the comparator 8 to obtain a pulse width control signal.

In the step-up chopper circuit described above, when the DC power supply voltage rises, the output voltage of the inverting amplifier 12 drops, so the added voltage obtained from the addition inverting amplifier 14 rises, which causes the output of the comparator 8 to rise. The H level period 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 to the boost chopper circuit increases, the DC power supply voltage decreases, and the voltage is controlled to be a constant value.

On the contrary, when the DC power supply voltage decreases, the ON period of the switching element 2 becomes shorter, the peak value of the current flowing from the DC power supply 1 into the boost chopper circuit becomes smaller, and the direct current power supply voltage rises. The voltage is controlled to be 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]

EFFECTS OF THE INVENTION As described above, the present invention can prevent the occurrence of the hunting phenomenon when the rectifier is used as the DC power supply, even if the load current increases and the output ripple of the rectifier increases. it can.

[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

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 that 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 power supply voltage corresponding to the DC output voltage An addition inverting amplifier for adding and inverting corresponding voltages and a comparator for comparing the addition voltage obtained from the addition inverting amplifier with a triangular wave are provided, and the switching element is controlled by a pulse width control signal from the comparator. The boost chopper circuit is characterized in that the DC output voltage and the DC power supply voltage are controlled to constant values.