JP2021023013A - Switching power supply device - Google Patents

Abstract

To provide a switching power supply device that can suppress fluctuations in an output voltage even when an input voltage fluctuates abruptly.SOLUTION: A switching power supply device 1 includes a switching circuit 10 that converts an input voltage VIN to a target voltage VTARGET by pulse modulation control of a switching element SW and outputs the target voltage, a modulation amount calculation unit 40 that calculates the next modulation amount of pulse modulation control on the basis of the output voltage VOUT of the switching circuit 10, and a modulation amount correction unit 50 that determines whether the correction of the next modulation amount is necessary on the basis of a comparison between a change amount ΔVIN of the input voltage VIN and a predetermined change amount threshold Vset, and outputs a correction value x obtained by performing multiplication predetermined first gain G1 and a change amount ΔVIN to the modulation amount calculation unit 40 when the correction of the next modulation amount is necessary, and the modulation amount calculation unit 40 corrects the next modulation amount with the previous modulation amount corrected by the correction value x.SELECTED DRAWING: Figure 2

Description

The present invention relates to a switching power supply device.

A switching power supply device is widely used as one of the power conversion devices that converts an input voltage into a desired voltage and outputs it. In recent years, an increasing number of switching power supply devices are fully digitally controlled by A / D converting feedback signals such as output voltage, output current, and temperature and incorporating them into a microcomputer control circuit to perform power conversion based on the feedback signals. There is. Such a switching power supply device by full digital control can accurately control the timing of the switching operation in response to changes in load conditions and input conditions, so that noise and power loss can be reduced. Further, in the switching power supply device by full digital control, various sequence operations can be set by the firmware, so that the number of parts can be reduced and the system can be miniaturized.

By the way, switching power supply devices are often equipped with a protection function that stops operation when the output voltage or output current rises abnormally. For example, an overvoltage protection function (OVP) that enters a latch-off state when the output voltage of a switching power supply exceeds a predetermined threshold, or a latch-off state when the output current of a switching power supply exceeds a predetermined threshold. An overcurrent protection function (OCP: Over Current Protection) is known, and a switching power supply device equipped with the latter function is disclosed in Patent Document 1. More specifically, the prior art described in Patent Document 1 is a switching power supply device that puts a latch-off state when an overcurrent is detected and releases the latch-off at a predetermined timing.

Japanese Unexamined Patent Publication No. 11-18418

However, since the digitally controlled switching power supply performs feedback control that suppresses fluctuations in the output voltage at a discrete time associated with the clock frequency, the fluctuation suppression control of the output voltage is not in time for sudden input fluctuations, and the output is still output. There is a risk that voltage fluctuations cannot be suppressed.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a switching power supply device capable of suppressing fluctuations in output voltage even when input voltages fluctuate abruptly. To provide.

<First aspect of the present invention>
The first aspect of the present invention is a switching circuit that converts an input voltage into a target voltage by pulse modulation control of a switching element and outputs it, and calculates the next modulation amount of the pulse modulation control based on the output voltage of the switching circuit. When the necessity of correction for the next modulation amount is determined based on the comparison between the modulation amount calculation unit and the change amount of the input voltage and the predetermined change amount threshold, and the correction of the next modulation amount is necessary, A modulation amount correction unit that outputs a correction value obtained by multiplying a predetermined first gain and the change amount to the modulation amount calculation unit is provided, and the modulation amount calculation unit is previously corrected by the correction value. This is a switching power supply device that corrects the next modulation amount with the modulation amount.

The switching power supply device converts the input voltage into a target voltage and outputs it by controlling the switching element by pulse modulation based on the output voltage. At this time, when the modulation amount correction unit of the switching power supply device detects a sudden change in the input voltage by comparing the change amount of the input voltage with the predetermined change amount threshold, the next modulation amount in the pulse modulation control It is determined that correction is necessary. Further, the modulation amount correction unit calculates a correction value according to the change amount of the input voltage, and outputs the correction value to the modulation amount calculation unit that calculates the next modulation amount of the pulse modulation control. Then, the modulation amount calculation unit corrects the next modulation amount to be calculated by the previous modulation amount corrected by the correction value.

That is, when a sudden change in the input voltage is detected in the calculation of the next modulation amount in the modulation amount calculation unit, the switching power supply device performs the next modulation with the previous modulation amount corrected by the correction value based on the change amount. Since the amount is corrected, pulse modulation control according to the input fluctuation can be performed before the output voltage fluctuates. Further, the correction of the next modulation amount enables high-speed processing because division is not used in the calculation. Furthermore, since the next modulation amount is corrected only when a sudden fluctuation in the input voltage is detected, the correction that greatly affects the output voltage is not performed during normal operation, and the input voltage is slight. It is possible to prevent the stabilization of the output voltage from being hindered by fluctuations. As a result, the switching power supply device according to the first aspect of the present invention can suppress fluctuations in the output voltage even when the input voltage fluctuates abruptly.

<Second aspect of the present invention>
A second aspect of the present invention is the switching power supply device according to the first aspect of the present invention, wherein the modulation amount correction unit is set to increase the correction value as the input voltage decreases. is there.

According to the switching power supply device according to the second aspect of the present invention, the correction value is set higher as the input voltage decreases, so that the output voltage fluctuates by appropriate pulse modulation control according to the decrease width of the input voltage. The width can be further suppressed.

<Third aspect of the present invention>
In the third aspect of the present invention, in the first or second aspect of the present invention described above, the change amount threshold is the input rise threshold applied when the change amount of the input voltage is a positive value. It is a switching power supply device including an input lowering threshold value applied when the change amount of the input voltage is a negative value.

According to the switching power supply device according to the third aspect of the present invention, since the change amount threshold value is set separately for the case where the input voltage rises and the case where the input voltage falls, for example, when the input voltage rises more than when it falls. It is possible to set a difference in the detection criteria when the response to the above is emphasized.

<Fourth aspect of the present invention>
In the fourth aspect of the present invention, in the third aspect of the present invention described above, the modulation amount correction unit uses the correction value when the change amount of the input voltage is either a positive value or a negative value. It is a switching power supply that invalidates the output of.

According to the switching power supply device according to the fourth aspect of the present invention, for example, when the modulation amount calculation unit has a function of skipping a pulse when the output voltage rises above the change amount threshold value, the modulation amount correction unit By disabling the output of the correction value by the sign of the change amount of the input voltage, such as stopping the output of the correction value, the output voltage can be further stabilized by matching with the control by the modulation amount calculation unit. Can be done.

<Fifth aspect of the present invention>
In a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention described above, the modulation amount correction unit is set to a difference value between a predetermined upper limit value and the input voltage with respect to the input voltage. This is a switching power supply device that adjusts the correction value by a correction coefficient multiplied by the second gain of.

According to the switching power supply device according to the fifth aspect of the present invention, a difference value obtained by subtracting the input voltage from the preset upper limit value of the input voltage is calculated, and the correction value is a correction coefficient proportional to the difference value. Is adjusted, so it is possible to make corrections according to the fluctuation range of the input voltage with simple control.

<Sixth Aspect of the Present Invention>
A sixth aspect of the present invention is a switching power supply device in which the pulse modulation control is PWM control in any one of the first to fifth aspects of the present invention described above.

According to the switching power supply device according to the sixth aspect of the present invention, it is possible to correct the next modulation amount for the switching power supply device in which the PWM control method is adopted.

<7th aspect of the present invention>
A seventh aspect of the present invention is a switching power supply device in which the pulse modulation control is PFM control in any one of the first to fifth aspects of the present invention described above.

According to the switching power supply device according to the seventh aspect of the present invention, it is possible to correct the next modulation amount for the switching power supply device in which the PFM control method is adopted.

According to the present invention, it is possible to provide a switching power supply device capable of suppressing fluctuations in the output voltage even when the input voltage fluctuates abruptly.

It is a circuit diagram which shows the structure of the switching power supply device which concerns on 1st Embodiment of this invention. It is a block diagram which shows the calculation of the modulation amount in a calculation part. It is a figure which shows an example of the correction value with respect to the input voltage and the amount of change. It is a waveform diagram of the input voltage and the output voltage when the modulation amount correction unit is not provided. It is a waveform diagram of the input voltage and the output voltage of the switching power supply device which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the correction value with respect to the input voltage and the amount of change which concerns on 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described below, and can be arbitrarily modified and implemented without changing the gist thereof. In addition, the drawings used for explaining the embodiments are all schematically showing the constituent members, and are partially emphasized, enlarged, reduced, or omitted in order to deepen the understanding of the constituent members. It may not accurately represent the scale or shape.

<First Embodiment>
FIG. 1 is a circuit diagram showing a configuration of a switching power supply device 1 according to a first embodiment of the present invention. In the present embodiment, the switching power supply device 1 is input from the external power supply 2 by connecting the external power supply 2 to the two input terminals T _IN and connecting the external load 3 to the two output terminals T _OUT. This is a so-called DC-DC converter that converts a DC input voltage Vin into a desired target voltage V _TARGET and outputs a stable DC output voltage Vout to an external load 3. The switching power supply device 1 includes a switching circuit 10 that converts electric power, a driver circuit 20 that drives the switching element SW of the switching circuit 10, and a control unit 30 that controls the driver circuit 20 based on the input / output voltage of the switching circuit 10. Be prepared.

The switching circuit 10 includes an input capacitor C _IN , a switching element SW, a choke coil L, a commutation diode D, and an output capacitor C _OUT .

One end of the input capacitor C _IN is connected to the input terminal T _IN on the high potential side, and the other end is connected to the input terminal T _IN on the low potential side, so that the input capacitor C _IN is input to the pair of input terminals from the external power supply 2. Suppresses fluctuations in the input voltage Vin.

In this embodiment, the switching element SW is composed of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), the drain is connected to the input terminal T _IN on the high potential side, and the source is the choke coil L. It is connected to the output terminal T _OUT on the high potential side via. Then, as will be described later, the switching element SW is pulse-modulated controlled by inputting a pulse signal from the driver circuit 20 to the gate. The switching element SW may be a known bipolar transistor or another element such as an IGBT (Insulated Gate Bipolar Transistor).

The choke coil L stores energy by the current flowing from the switching element SW to the output terminal T _OUT on the high potential side when the switching element SW is ON. The commutation diode D is composed of, for example, a Schottky barrier diode, the anode is connected to the connection point between the input capacitor C _IN and the input terminal T _IN on the low potential side, and the cathode is the connection point between the switching element SW and the choke coil L. It is connected. The commutation diode D releases the energy stored in the choke coil L by flowing a forward current in a state where the switching element SW is OFF.

One end of the output capacitor C _OUT is connected to the connection point between the choke coil L and the output terminal T _OUT on the high potential side, and the other end is the connection point between the anode of the commutation diode D and the output terminal T _OUT on the low potential side. It is connected to the.

The switching circuit 10 in the present embodiment can step down the input voltage Vin and output the output voltage Vout by PWM control (PWM: Pulse Width Modulation) for the switching element SW. However, the pulse modulation control for the switching element SW is not limited to the PWM control, and may be PFM control (PFM: Pulse Frequency Modulation) depending on the application.

Further, the switching circuit 10 according to the present invention is not limited to the above configuration, and various modifications can be made. For example, the switching circuit 10 may be configured as an AC-DC converter when AC power is input from the external power supply 2, or the input voltage Vin may be boosted to form an output voltage Vout. Further, the switching circuit 10 is not limited to diode rectification, and may be synchronous rectification in which a switching element is adopted instead of the commutation diode D. Further, the switching circuit 10 may be an isolated DC-DC converter via an isolation transformer, and has various types such as a so-called flyback system, a forward system, a push-pull system, a half bridge system, and a full bridge system. The circuit configuration of the form can be adopted.

The driver circuit 20 outputs a pulse voltage to the gate of the switching element SW based on the output signal of the control unit 30, so that the output voltage Vout of the switching circuit 10 becomes the target voltage V _TARGET .

The control unit 30 is composed of, for example, a known microcomputer control circuit, detects an input voltage Vin input from an external power supply 2 to a switching circuit 10, and an output voltage Vout output from a switching circuit 10 to an external load, and detects a target voltage. Pulse modulation control for controlling the switching element SW is performed via the driver circuit 20 so that the output voltage Vout does not fluctuate with respect to V _TARGET . Further, the control unit 30 of the present embodiment includes an input ADC 31, an output ADC 32, a calculation unit 33, and a pulse generation unit 34.

The input ADC 31 is an AD converter for detecting an input voltage Vin at the connection point between the input terminal T _IN on the high potential side and the input capacitor C _IN , converting an analog value into a digital value, and incorporating the analog value into the arithmetic unit 33. .. The input ADC 31 may be connected to the input terminal T _IN on the low potential side in addition to the input terminal T _IN on the high potential side in order to acquire the input voltage Vin with higher accuracy.

Output ADC32, in order to obtain the output voltage Vout of the switching circuit 10, and detects the voltage from the output terminal _{T OUT} of the high-potential Vsense (+), low potential side of the output terminal _{T OUT} from the voltage Vsense (- ) Is detected, an analog value is converted into a digital value, and the AD converter is used to incorporate the analog value into the arithmetic unit 33. The output ADC 32 may detect only the voltage Vsense (+) at the output terminal T _OUT on the high potential side and set the output voltage V out.

The calculation unit 33 modulates and controls the switching element SW so that the output voltage Vout becomes the target voltage V _TARGET based on the input / output voltage of the switching circuit 10 input from the input ADC 31 and the output ADC 32. Calculate the modulation amount of the series. At this time, the calculation unit 33 samples the input / output voltage of the switching circuit 10 at the operating frequency of the pulse modulation control. The specific configuration and operation of the calculation unit 33 will be described in detail later.

The pulse generation unit 34 generates a pulse sequence based on the information of the modulation amount calculated by the calculation unit 33, and outputs the pulse sequence to the driver circuit 20.

Next, the configuration and operation of the calculation unit 33 described above will be described more specifically. FIG. 2 is a block diagram showing the calculation of the modulation amount in the calculation unit 33. The calculation unit 33 includes a modulation amount calculation unit 40 and a modulation amount correction unit 50.

The modulation amount calculation unit 40 includes a first adder 41, a second adder 42, and a compensator 43, and modulates and controls a pulse sequence for feeding back the output voltage Vout of the switching circuit 10 to drive the switching element SW. Calculate the amount of modulation to be used.

The first adder 41 calculates the output voltage Vout based on the difference between the voltage Vsense (+) and the voltage Vsense (−) of the switching circuit 10 detected via the output ADC 32, and outputs the output voltage Vout to the second adder 42. .. Further, the second adder 42 has an error between the output voltage Vout and the target voltage V _TARGET due to the difference between the reference voltage Vref corresponding to the target voltage V _TARGET and the value of the output voltage Vout output from the first adder 41. (Error) is calculated and output to the compensator 43.

The compensator 43 calculates the next modulation amount so that the error becomes 0 based on the output voltage Vout due to the previous modulation amount output by the calculation unit 33, and outputs the next modulation amount to the pulse generation unit 34. Since the compensator 43 in the present embodiment employs the PWM control method, it outputs the duty of the pulse series as the modulation amount. When the compensator 43 adopts the PFM control method, the frequency of the pulse series is output as the modulation amount.

The modulation amount correction unit 50 includes a digital high-pass filter 51, a third adder 52, a second amplifier 53, a determination unit 54, a first amplifier 55, and a fourth adder 56, and measures the modulation amount output by the compensator 43. Correct if necessary.

The digital high-pass filter 51 calculates the amount of change ΔVin of the input voltage Vin acquired via the input ADC 31 and outputs it to the determination unit 54. The third adder 52 calculates the difference value d between the predetermined upper limit value Vk and the input voltage Vin with respect to the input voltage Vin. The second amplifier 53 multiplies the difference value d by a predetermined second gain G2 to calculate a correction coefficient c = (Vk−Vin) × G2 and outputs it to the determination unit 54.

Here, the upper limit value Vk is a threshold value arbitrarily set in advance as a value equal to or less than VinMax when the maximum voltage that can be input as the input voltage Vin is VinMax, and the correction coefficient as the input voltage Vin decreases. c is set to rise. The second gain G2 is a parameter that is arbitrarily set in advance to define the rate of increase of the correction coefficient c. In this embodiment, for example, Vk = VinMax × 0.7 and G2 = 0.025.

The determination unit 54 determines the necessity of correction for the next modulation amount output by the modulation amount calculation unit 40 by comparing the change amount ΔVin of the input voltage Vin with the predetermined change amount threshold value Vset. More specifically, the determination unit 54 determines that when the absolute value of the change amount ΔVin is equal to or greater than the change amount threshold value Vset, it is assumed that a sudden change in the input voltage Vin has occurred and the next modulation amount needs to be corrected. When the absolute value of the change amount ΔVin is less than the change amount threshold value Vset, it is determined that the correction of the next modulation amount is unnecessary.

Here, the change amount threshold value Vset is a threshold value arbitrarily set in advance in order to define the allowable fluctuation range of the input voltage Vin, and is set as, for example, Vset = 0.1 in the present embodiment. ..

Then, the determination unit 54 outputs the following output value y to the first amplifier 55 based on the magnitude of the absolute value of the change amount ΔVin.
When | ΔVin | ≧ Vset, y = ΔVin × c = ΔVin × (Vk−Vin) × G2
When | ΔVin | <Vset, y = 0

The first amplifier 55 multiplies the output value y output by the determination unit 54 and the predetermined first gain G1 to calculate the correction value x, and outputs the correction value x to the fourth adder 56. Here, the first gain G1 is a parameter that is arbitrarily set in advance to define the rate of increase of the correction value x with respect to the amount of change ΔVin, and is set as, for example, G1 = 2.5 in the present embodiment. There is. As a result, the first amplifier 55 outputs the following correction value x to the fourth adder 56 based on the magnitude of the absolute value of the amount of change ΔVin.
When | ΔVin | ≧ Vset, x = ΔVin × (Vk−Vin) × G2 × G1
When | ΔVin | <Vset, x = 0

The fourth adder 56 inputs to the compensator 43 the difference between the previous modulation amount output by the compensator 43 and the correction value x output from the first amplifier 55. As a result, when the input voltage Vin suddenly changes with reference to the change amount threshold Vset, the compensator 43 inputs the previous modulation amount corrected by the correction value x, and the next modulation amount is based on the corrected previous modulation amount. By the feed forward control that calculates the above, pulse modulation control that quickly suppresses fluctuations in the output voltage Vout can be performed.

FIG. 3 is a diagram showing an example of a correction value x with respect to an input voltage Vin and a change amount ΔVin. More specifically, FIG. 3 shows the relationship between the input voltage Vin and the correction value x when the amount of change ΔVin is ± 0.4 and ± 0.2, respectively. The horizontal axis is shown as the relative ratio of the input voltage Vin to the maximum input voltage VinMax.

As seen in FIG. 3, for example, when the change amount ΔVin is ± 0.4, the correction value x is maintained at 0 and the modulation amount is maintained until the Vin / VinMax value drops to 0.6 or less. Is set not to be corrected for. Further, the absolute value of the correction value x is set to increase as the value of Vin / VinMax decreases, and at this time, the inclination of the correction value x is set to increase as the fluctuation range of the change amount ΔVin increases. There is.

Here, in the present embodiment, the modulation amount correction unit 50 has a correction value x other than 0 when the absolute value is equal to or greater than the change amount threshold value Vset regardless of whether the change amount ΔVin is a positive value or a negative value. Is output, but depending on the balance with other functions, one may be invalidated by the sign of the amount of change ΔVin. More specifically, for example, when the compensator 43 has a function of skipping a pulse for a predetermined period when the input voltage Vin rises above the change amount threshold value Vset, the modulation amount correction unit 50 is also provided. The output of the correction value x may be stopped for the predetermined period.

Subsequently, the effect of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a waveform diagram of an input voltage Vin and an output voltage Vout when the modulation amount correction unit 50 is not provided. Further, FIG. 5 is a waveform diagram of an input voltage Vin and an output voltage Vout of the switching power supply device 1 according to the first embodiment of the present invention. In FIGS. 4 and 5, the elapsed time from the timing when the input voltage Vin suddenly drops is represented by the horizontal axis, and the changes in the input voltage Vin and the output voltage Vout are represented in the lower half and the upper half of the figure, respectively. ..

As can be seen in FIG. 4, when the correction by the modulation amount correction unit 50 is not performed, the output voltage Vout also drops significantly from 50V to about 30V when the input voltage Vin drops sharply from 48V to 36V. However, it can be confirmed that it takes about 4.6 ms for the output voltage Vout to recover to the voltage before the input fluctuation.

On the other hand, as seen in FIG. 5, when the correction by the modulation amount correction unit 50 is performed, the output voltage Vout is from 50V even when the input voltage Vin suddenly drops from 48V to 36V. It can be confirmed that the decrease width is suppressed as the decrease to about 40 V, and the time until the output voltage Vout recovers to the voltage before the input fluctuation is shortened to about 0.8 ms.

As described above, since the switching power supply device 1 according to the present invention corrects the modulation amount by feed forward in the pulse modulation control, the output voltage Vout is relatively quick even with a sudden fluctuation of the input voltage Vin. Fluctuations can be suppressed. Therefore, the output voltage Vout can be minimized in its decrease and can be restored to the voltage before the input fluctuation in a short time. Further, the correction of the next modulation amount enables high-speed processing because division is not used in the calculation. At this time, the switching power supply device 1 maintains the correction value x at 0, assuming that the correction for the next modulation amount is unnecessary until the change amount ΔVin of the input voltage Vin exceeds the change amount threshold value Vset. As a result, the modulation amount correction unit 50 does not interfere with the feedback control of the modulation amount calculation unit 40 based on the output voltage Vout during normal operation without receiving sudden input fluctuations, and does not interfere with the stabilization of the output voltage Vout. can do. Therefore, according to the switching power supply device 1 according to the first embodiment of the present invention, it is possible to suppress the fluctuation of the output voltage Vout even when the input voltage Vin suddenly fluctuates.

<Second Embodiment>
Subsequently, the second embodiment of the present invention will be described. The switching power supply device 1 according to the second embodiment is different from the first embodiment in the method of setting the change amount threshold value Vset in the first embodiment. Hereinafter, the parts different from those of the first embodiment will be described, and the components common to the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 6 is a diagram showing an example of a correction value x with respect to an input voltage Vin and a change amount ΔVin according to the second embodiment of the present invention. In the switching power supply device 1 according to the second embodiment, the change amount threshold value Vset for determining whether or not the correction with respect to the modulation amount output by the modulation amount calculation unit 40 is necessary differs depending on the sign of the change amount ΔVin. That is, the change amount threshold value Vset according to the second embodiment is the input rise threshold value applied when the change amount ΔVin of the input voltage Vin is a positive value and the change amount ΔVin of the input voltage Vin is a negative value. Includes the applied input descending threshold.

Even if the fluctuation range of the amount of change ΔVin is the same, the input voltage Vin is damaged in each electronic component of the switching power supply device 1 when it rises sharply as compared with the case where it drops sharply. In many cases, there is a high risk of letting them do it. Therefore, by setting the change amount threshold value Vset to a different value depending on the sign of the change amount ΔVin, it is possible to more appropriately determine the necessity of correction for the modulation amount according to the conditions.

More specifically, for example, in the example of FIG. 6, when the input voltage Vin drops sharply, the correction value x is maintained at 0 for modulation until the value of Vin / VinMax drops to 0.5 or less. It is set not to correct the amount. On the other hand, when the input voltage Vin rises sharply, the correction value x is output and the modulation amount is corrected when the value of Vin / VinMax drops to 0.6. Therefore, according to the switching power supply device 1 according to the second embodiment of the present invention, the risk of damage to parts due to a sudden fluctuation of the input voltage Vin is reduced, and the correction for the next modulation amount is suppressed as much as possible to perform normal operation. Output fluctuations over time can be suppressed.

1 Switching power supply 2 External power supply 3 External load 10 Switching circuit 30 Control unit 33 Calculation unit 40 Modulation amount calculation unit 43 Compensator 50 Modulation amount correction unit 51 Digital high-pass filter 54 Judgment unit SW switching element

Claims (7)

A switching circuit that converts the input voltage to the target voltage by pulse modulation control of the switching element and outputs it,
A modulation amount calculation unit that calculates the next modulation amount of the pulse modulation control based on the output voltage of the switching circuit, and
The necessity of correction for the next modulation amount is determined based on the comparison between the change amount of the input voltage and the predetermined change amount threshold, and when the correction of the next modulation amount is necessary, the predetermined first gain and the predetermined first gain and the above. A modulation amount correction unit that outputs a correction value obtained by multiplying the change amount to the modulation amount calculation unit is provided.
The modulation amount calculation unit is a switching power supply device that corrects the next modulation amount with the previous modulation amount corrected by the correction value. The switching power supply device according to claim 1, wherein the modulation amount correction unit is set to increase the correction value as the input voltage decreases. The change amount threshold includes an input rising threshold value applied when the change amount of the input voltage is a positive value, and an input falling threshold value applied when the change amount of the input voltage is a negative value. The switching power supply device according to claim 1 or 2, comprising the above. The switching power supply device according to claim 3, wherein the modulation amount correction unit invalidates the output of the correction value when the change amount of the input voltage is either a positive value or a negative value. Any one of claims 1 to 4, wherein the modulation amount correction unit adjusts the correction value by a correction coefficient obtained by multiplying a difference value between a predetermined upper limit value and the input voltage with respect to the input voltage by a predetermined second gain. The switching power supply according to. The switching power supply device according to any one of claims 1 to 5, wherein the pulse modulation control is PWM control. The switching power supply device according to any one of claims 1 to 5, wherein the pulse modulation control is PFM control.

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