JP4942574B2 - Switching power supply, switching power supply control method, and switching power supply control program - Google Patents

Description

  The present invention relates to a digitally controlled switching power supply, a switching power supply control method, and a switching power supply control program.

Conventionally, there is a voltage mode control means as a means for controlling on / off of a rectifier switch in a switching power supply. This is specifically shown in FIG. The switching power supply according to the embodiment shown in FIG. 5 is configured to amplify an error between the detection voltage and the reference voltage Vref by connecting the negative input of the error amplifier 51 to the output side of the power supply circuit. The output of the error amplifier 51 is connected to the positive input of the comparator 52, the oscillator 53 is connected to the negative input of the comparator 52, and a triangular wave is transmitted from the oscillator 53 to the comparator 52. It is. The output of the comparator 52 is connected to the input of the driver 11, and the output of the driver 11 is connected to the gate of the rectifier switch Q1 and the gate of the commutation switch Q2 (see, for example, Patent Document 1).
US Pat. No. 6,147,478

  However, the switching power supply having such a control means has a problem that frequency characteristics change depending on the magnitude of the input / output voltage, and it is difficult to set an optimum gain for the switching power supply. For example, as shown in FIG. 6, when the input voltage is changed to 5 V, 9 V, and 12 V, the deviation of the deviation is larger at 9 V than at 12 V. Furthermore, this becomes remarkable when it becomes 5V.

  If it is difficult to set an optimum gain, the output voltage at the time of sudden change of input or sudden change of output greatly changes, and it is difficult to obtain a stable switching power supply operation.

  The present invention has been made in view of the above problems, and provides a switching power supply, a switching power supply control method, and a switching power supply control program capable of obtaining the same frequency characteristics regardless of the magnitude of the input / output voltage. To do.

  In order to solve the above problems, a switching power supply according to the present invention has a switching element that controls an output power supply voltage based on a pulse width of a drive signal, and the switching power supply is based on a drive signal having a pulse width based on a control amount. A switching power supply that controls the output voltage by driving an element, a sampling means for sampling the output voltage, an output voltage obtained from the sampling means, and a deviation calculating means for obtaining a deviation from a difference between a reference voltage, Correction deviation calculating means for calculating a correction deviation using the obtained deviation and input voltage, and a control amount for controlling the pulse width of the switching element based on the correction deviation calculated by the correction deviation calculating means. Control amount calculation means to be obtained; drive means for generating a drive signal having a pulse width based on the control amount from the control amount calculation means; Characterized in that it comprises a.

  Further, the correction deviation calculating means divides the initial input voltage of the switching power supply by the input voltage of the switching power supply, and multiplies the divided value by the deviation to calculate the correction deviation. To do.

  A switching power supply control method according to the present invention is a switching power supply control program for controlling an output voltage by driving a switching element based on a drive signal having a pulse width based on a control amount, and a step of sampling the output voltage; Calculating the deviation from the difference between the output voltage obtained by the sampling and a reference voltage, calculating the correction deviation using the obtained deviation and the input voltage, and calculating by the correction deviation calculating means And a step of obtaining a control amount for controlling the pulse width of the switching element based on the corrected deviation.

  The switching power supply control program according to the present invention is a switching power supply control program for controlling the output voltage by driving a switching element based on a drive signal having a pulse width based on a controlled variable, and sampling the output voltage. A step of obtaining a deviation from a difference between the output voltage obtained by the sampling and a reference voltage, a step of calculating a correction deviation using the obtained deviation and an input voltage, and the correction deviation calculation Obtaining a control amount for controlling the pulse width of the switching element based on the correction deviation calculated by the means.

  According to the present invention, the same frequency characteristic can be obtained regardless of the magnitude of the input / output voltage. Since the optimum gain setting can be performed for the switching power supply, the change of the output voltage at the time of sudden change of input or sudden change of output is made constant, and there is an effect that a stable operation of the switching power supply can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of a switching power supply according to this embodiment. As shown in FIG. 1, the switching power supply of this embodiment controls the output power supply voltage by PWM based on the input capacitor C1 connected in parallel with the DC input power supply Vin and the pulse width of the drive pulse signal applied to the gate. The two switching elements Q1 and Q2 made of MOSFET, the output inductor L1, the smoothing capacitor C2, and the output power supply voltage are taken in, and the pulse width of the drive signal applied to the switching elements Q1 and Q2 is controlled according to the output power supply voltage. The digital control circuit 10 generates a control signal for performing the control, and the driver 11 supplies a drive pulse signal to the switching elements Q1 and Q2 based on the control signal of the digital control circuit 10.

  The positive side of the DC input power source Vin is connected to the positive side power line LN11, the negative side of the DC input power source Vin is connected to the negative side power line LN21, and the input is between the power line LN11 and the power line LN21. A capacitor C1 is connected. Switching element Q1 is connected between power supply line LN11 and power supply line LN12. Switching element Q2 is connected between power supply line LN12 and power supply line LN21. A drive pulse signal is supplied from the driver 11 to the gates of the switching element Q1 and the switching element Q2. An output inductor L1 is connected between the power supply line LN12 and the power supply line LN13. A smoothing capacitor C2 is connected between the power supply line LN13 and the power supply line LN21. A load RL is connected between the power supply line LN13 and the power supply line LN21.

  The output voltage Vout of the switching power supply circuit is taken out from the power supply line LN13, and this output voltage Vout is sent to the digital control circuit 10. The digital control circuit 10 samples the output voltage Vout and performs A / D conversion, and control for controlling the pulse width of the drive signal applied to the switching elements Q1 and Q2 from the sample value of the output voltage Vout. And an arithmetic unit 22 for obtaining a signal.

  The computing unit 22 obtains a deviation between the reference voltage Vref and the output voltage Vout, calculates a correction deviation from the deviation and the input voltage Vin, and based on the correction deviation, a pulse of the drive signal applied to the switching elements Q1 and Q2. A control signal for controlling the width is generated.

  A control signal from the digital control circuit 10 is sent to the driver 11. The driver 11 forms a drive pulse having a pulse width based on a control signal from the digital control circuit 10. This drive pulse is supplied to the gates of the switching elements Q1 and Q2.

FIG. 2 shows processing of the digital control circuit 10 according to the embodiment of the present invention.
In FIG. 2, first, the first input voltage of the DC input power source Vin of FIG. 1 is set as an operation input voltage (initial input voltage) Vin0 (step S1). Subsequently, control parameters are set (step S2). In this embodiment, three control parameters are set: a control parameter including a proportional element, a control parameter including an integral element, and a control parameter including a derivative element. Subsequently, the reference voltage Vref is set (step S3), and the input voltage Vin is further set (step S4).

  Subsequently, the output voltage Vout is acquired from the A / D converter of the sampling unit 21 in FIG. 1 (step S5). Then, a deviation E (n) between the reference voltage Vref and the output voltage Vout is obtained (step S6). Using this deviation E (n), the input voltage Vin, and the initial input voltage Vin0, a correction deviation E (n) 'is calculated (step S7).

Here, the correction deviation E (n) ′ in step S7 is obtained by the following equation.
E (n) ′ = (Vin0 / Vin) × E (n) (1)

Then, the control amount of the pulse width is calculated using the correction deviation E (n) ′ obtained in step S7 (step S8).
Here, the calculation of the control amount U (n) is performed as follows.
U (n) = U (n−1) + Δd (2)
The calculation of Δd is performed as follows.
Δd = K0 * E (n) ′ + K1 * E (n−1) ′ + K2 * E (n−2) ′ (3)
K0, K1, and K2 are parameters. For example, K0 can be a control parameter including a proportional element, K1 can be a control parameter including an integral element, and K2 can be a control parameter including a differential element.

  In step S5, the control amount is obtained using the correction deviation E (n) 'in this way. Based on this control amount, the pulse width of the drive signal applied to the switching elements Q1 and Q2, that is, the duty is controlled (step S9). When step S9 ends, the process returns to step S5, and the operations from step S5 to step S9 are repeated.

  Thus, in this embodiment, the input voltage Vin of the switching power supply circuit is set in step S4, the output voltage Vout of the switching power supply circuit is taken in in step S5, and the deviation between the reference voltage Vref and the output voltage Vout in step S6. E (n) is obtained, and the correction deviation E (n) ′ is calculated in step S7.

  Through the processing as described above, the same frequency versus gain characteristic can be obtained regardless of the magnitude of the input / output voltage. Since the optimum gain setting can be performed for the switching power supply, the change in the output voltage at the time of the sudden change of the input or the sudden change of the output becomes constant, and the optimum operation of the switching power supply can be obtained.

FIG. 3 is a functional block diagram showing the processing of the digital control circuit 10 described above.
In FIG. 3, the initial input voltage Vin <b> 0 and the input voltage Vin are input to the input voltage setting unit 33. The sample value of the output voltage Vout from the sampling unit 21 is supplied to a subtracter 31 that is a deviation calculating means. The subtracter 31 is supplied with the reference voltage Vref from the reference voltage generator 32. In the subtractor 31, a deviation E (n) between the reference voltage Vref and the output voltage Vout is obtained.

  The deviation E (n) between the reference voltage Vref and the output voltage Vout obtained by the subtracter 31 is sent to the control amount calculation unit 34. The control amount calculator 34 obtains the correction deviation E (n) ′ based on the equation (1), and obtains the control amount of the pulse width based on the equations (2) and (3). This control amount is sent to the driver 11, and the switching elements Q1 and Q2 are driven by a drive pulse having a pulse width based on this control amount.

  By performing the processing as shown in FIG. 2 using the digital control circuit 10 as described above, the control according to the present invention can obtain the same frequency characteristic regardless of the magnitude of the input / output voltage. is there. FIG. 4 shows a load sudden increase waveform when the switching power supply according to the present invention is controlled. In the waveform diagram of FIG. 4 as well as the waveform diagram of FIG. 6, the input voltage is changed to 5 V, 9 V, and 12 V, but the load sudden increase waveform of the conventional control shown in FIG. 6 and the control of the present invention shown in FIG. As can be seen from comparison with the load sudden increase waveform, the control by the switching power supply according to the present invention can obtain the same frequency characteristic regardless of the magnitude of the input voltage. Since the optimum gain setting can be performed for the switching power supply, the change of the output voltage at the time of the sudden change of the input or the sudden change of the output becomes constant, and a stable operation of the switching power supply can be obtained. 4 and 6, the horizontal axis indicates time, and the vertical axis indicates deviation.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

  The present invention can be used for a digital control type switching power supply in which a process for controlling an output voltage is performed by a digital control circuit.

It is a circuit diagram which shows the structure of the switching power supply of embodiment of this invention. It is a flowchart of an example of the power supply control process in the switching power supply of embodiment of this invention. It is a functional block diagram used for description of the power supply control process in the switching power supply of embodiment of this invention. It is a graph which shows the effect of the switching power supply of the embodiment of the present invention. It is a circuit diagram which shows the structure of the conventional switching power supply. It is a graph which shows the effect of the conventional switching power supply.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Digital control circuit 11 Driver 21 Sampling part 22 Operation part 31 Subtractor 32 Reference voltage generator 33 Input voltage setting part 34 Control amount calculation part 51 Error amplifier 52 Comparator 53 Oscillator C1 Input capacitor C2 Smoothing capacitor L1 Output inductors Q1, Q2 Switching element

Claims (3)

A switching power source that has a switching element that controls an output power supply voltage based on a pulse width of a drive signal, and that controls the output voltage by driving the switching element based on a drive signal having a pulse width based on a control amount;
Sampling means for sampling the output voltage;
Deviation calculation means for obtaining a deviation from the difference between the output voltage obtained from the sampling means and a reference voltage;
The initial input voltage of the switching power supply is divided by the input voltage of the switching power supply, and a deviation obtained by the division value and said deviation calculating means multiplies a correction deviation calculating means for calculating a correction deviation,
Control amount calculation means for obtaining a control amount for controlling the pulse width of the switching element based on the correction deviation calculated by the correction deviation calculation means;
And a drive unit that generates a drive signal having a pulse width based on a control amount from the control amount calculation unit. A switching power supply control program for driving a switching element based on a drive signal having a pulse width based on a control amount to control an output voltage,
Sampling the output voltage;
Obtaining a deviation from the difference between the output voltage obtained by the sampling and a reference voltage;
Wherein dividing the initial input voltage of the switching power supply with an input voltage of the switching power supply, by multiplying the deviation obtained in step of determining the division value and said deviation, calculating a correction deviation,
Obtaining a control amount for controlling the pulse width of the switching element based on the correction deviation calculated in the step of calculating the correction deviation;
A control method for a switching power supply, comprising: A control program for a switching power supply configured to control an output voltage by driving a switching element based on a drive signal having a pulse width based on a control amount,
Sampling the output voltage;
Obtaining a deviation from the difference between the output voltage obtained by the sampling and a reference voltage;
A step in which the initial input voltage of the switching power supply is divided by the input voltage of the switching power supply, and a deviation obtained by determining the division value and the deviation is multiplied to calculate a correction deviation,
Obtaining a control amount for controlling the pulse width of the switching element based on the correction deviation calculated in the step of calculating the correction deviation;
A switching power supply control program comprising:

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