JP2011010491A - Switching power supply by digital control system, and safety interruption method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To turn off the power supply output safely when arithmetic processing is abnormal.SOLUTION: In a power supply, a constant voltage circuit 11 outputs a constant voltage by switching an input voltage Vin and the output level of the constant voltage circuit 11 is digitized by an A/D converter 12, an arithmetic circuit 13 periodically operates the control value of switching for stabilized output based on the data of output level, and a PWM circuit 17 controls the on/off-period of switching based on that control value. The arithmetic circuit 13 is provided with a pulse generation circuit 14 which generates a pulse every time the operation is performed, a decision circuit 15 compares the period of a pulse generated in the pulse generation circuit 14 with a reference period, brings the constant voltage circuit 11 into an operating state by deciding that the operation is performed normally if the period of a pulse is shorter than the reference period, and stops the constant voltage circuit 11 by deciding that the operation is abnormal if the period of a pulse is longer than the reference period.

Description

  The present invention relates to a switching power supply apparatus that stabilizes output by, for example, digital control, and more particularly, to a method for safely shutting off output when an abnormality occurs.

  In recent years, digital control systems are being adopted for switching power supply devices (see Patent Document 1), but the control circuit unit, that is, the arithmetic processing circuit, is originally updated when arithmetic processing is not performed due to factors such as interruption or temperature. The expected calculation result is not updated, and the previous control value remains unchanged. At this time, when an input fluctuation or a load fluctuation occurs, the controlled output voltage or output current largely fluctuates, which may destroy the load device.

JP 2008-125349 A

  As described above, in the conventional switching power supply device using the digital control method, when an abnormality occurs in the arithmetic processing due to factors such as interruption or temperature, the calculation result of the control value is not updated and the previous control value remains unchanged. Therefore, when input fluctuation or load fluctuation occurs, the output voltage or output current may fluctuate greatly and the load device may be destroyed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a switching power supply device using a digital control system that can safely turn off the power supply when a calculation process is abnormal, and a safety shut-off method thereof.

  In order to achieve the above object, a digital control switching device according to the present invention includes a stabilization circuit that stabilizes and outputs an input signal by switching processing, and digitizes and monitors the output of the stabilization circuit. An arithmetic processing circuit that periodically calculates a control value of the switching process for stabilizing output based on a result, a control circuit that controls an on / off period of the switching process based on the control value, and the arithmetic When a pulse generation circuit that generates a pulse every time the calculation is performed in the processing circuit and the period of the pulse generated by the pulse generation circuit are compared with a reference period, and the pulse period is less than the reference period Determines that the calculation is normally performed, puts the stabilization circuit in an operating state, and calculates when the pulse period exceeds the reference period. And an aspect that it is determined that the normal has occurred; and a decision circuit for stopping the stabilization circuit.

  In addition, the safety shutoff method according to the present invention digitizes and monitors the output of a stabilizing circuit that stabilizes and outputs an input signal by switching processing, and periodically performs the switching for stabilizing output based on the monitoring result. A digital control switching power supply device that calculates a control value of a process and controls an on / off period of the switching process based on the control value, and generates a pulse each time the calculation is performed. The period is compared with a reference period, and when the pulse period is lower than the reference period, it is determined that the calculation is normally performed, and the stabilization circuit is activated, and the pulse period exceeds the reference period. One aspect is to determine that an abnormality has occurred in the operation and stop the stabilization circuit.

  According to one aspect of the switching power supply device having the above-described configuration and its safety shutoff method, a pulse is generated each time an operation is performed, and the cycle is compared with a reference cycle by a determination circuit, so that the calculation process is not performed. In addition, it is determined that the pulse period has exceeded the reference period due to the generation stop of the pulse, an off signal is output to the stabilization circuit, and the operation is urgently stopped.

  By taking such means, it is possible to safely turn off the power even if an abnormality occurs in the arithmetic processing.

  ADVANTAGE OF THE INVENTION According to this invention, the switching power supply by the digital control system which can be turned off safely at the time of arithmetic processing abnormality, and its safe interruption | blocking method can be provided.

The block block diagram which shows one Embodiment of the switching power supply device by the digital control system which concerns on this invention. The flowchart which shows the flow of a process of the determination circuit used for the said power supply device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a digital control switching power supply device according to the present invention. The switching power supply device 100 shown in FIG. 1 is supplied with a voltage Vin from an input source, and converted to a stabilized voltage by a constant voltage circuit 11 using a switching regulator to obtain an output voltage Vout.

  The constant voltage circuit 11 may be a constant current circuit, and the output voltage Vout may be the output current. Hereinafter, the constant voltage circuit 11 will be described.

  In order to stabilize the voltage, the output voltage Vout of the constant voltage circuit 11 is converted into data by analog / digital conversion of an A / D (analog / digital) converter 12 and input to the arithmetic processing circuit 13. The arithmetic processing circuit 13 monitors the level change of the output voltage Vout from the input data, calculates a control value (data) for stabilizing the voltage periodically, and holds it in the storage circuit 16. The control value data held in the storage circuit 16 is sent to a PWM (Pulse Width Modulation) circuit 17. The PWM circuit 17 supplies a switching control signal that is pulse-width modulated in accordance with a control value to the constant voltage circuit 11, and by increasing or decreasing the switching ON period of the constant voltage circuit 11 in accordance with the control value. The output voltage Vout is stabilized.

  The arithmetic processing circuit 13 includes a pulse generation circuit 14 that generates a pulse every time a control value is calculated. The pulse generated by the pulse generation circuit 14 is sent to a pulse period determination circuit 15. This pulse period determination circuit 15 compares the period of the pulse sent from the pulse generation circuit 14 with a reference period, and generates an ON signal when the period of the input pulse is shorter than the reference period, and generates an OFF signal when it becomes longer than the reference period. And output to the constant voltage circuit 11. The constant voltage circuit 11 turns on / off its operating state in accordance with an on / off signal from the pulse period determination circuit 15.

  The operation of the digital control switching power supply device 100 having the above configuration will be described with reference to the processing procedure of the determination circuit 15 shown in FIG.

  First, when there is no abnormality in the arithmetic processing circuit 13 and arithmetic processing is regularly performed, a pulse is generated and sent to the determination circuit 15 every time the arithmetic is executed. As shown in FIG. 2, the determination circuit 15 receives a pulse from the pulse generation circuit 14 provided in the arithmetic processing circuit 13, and compares the pulse period with a reference period (step S1). In the normal state, since it is determined that the cycle of the input pulse is lower than the reference cycle, an ON signal is generated and continuously output to the constant voltage circuit 11 (step S2). At this time, the control value stored in the storage circuit 16 is sequentially updated to the data of the control value calculated by the arithmetic processing circuit 13, and the PWM circuit 17 performs the pulse width modulation of the control signal accompanying the fluctuation of the output voltage Vout. As a result, the output voltage Vout of the constant voltage circuit 11 is stabilized.

  On the other hand, in the arithmetic processing circuit 13, when the arithmetic processing is not performed due to an interrupt, a temperature rise or the like, the storage circuit 16 is not periodically updated, and does not follow the change in the output voltage Vout. 17 pulse width control is not executed. If this is left as it is, when the input fluctuation or load fluctuation occurs, the output voltage Vout may change greatly and the load device may be destroyed.

  Therefore, in the present embodiment, the pulse generation circuit 14 of the arithmetic processing circuit 13 generates a pulse every time the calculation is executed, and the determination circuit 15 compares the period with the reference period. That is, when the arithmetic processing is not performed, no pulse is generated. Therefore, the determination circuit 15 determines that the pulse period exceeds the reference period, generates an off signal, and outputs the off signal to the constant voltage circuit 11. (Step S3). Thereby, the operation of the constant voltage circuit 11 is urgently stopped.

  Therefore, according to the digital control type switching power supply device having the above-described configuration, an abnormality in calculation is immediately determined and the output is stopped, so that an extremely safe specification can be achieved.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, according to the present invention, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 100 ... Switching power supply device, 11 ... Constant voltage circuit, Vin ... Input voltage, Vout ... Output voltage, 12 ... A / D (analog / digital) converter, 13 ... Arithmetic processing circuit, 14 ... Pulse generation circuit, 15 ... Pulse cycle Judgment circuit, 16 ... memory circuit, 17 ... PWM (Pulse Width Modulation) circuit.

Claims (7)

A stabilization circuit that stabilizes and outputs an input signal by switching processing;
An arithmetic processing circuit that digitizes and monitors the output of the stabilization circuit and periodically calculates a control value of the switching process for the stabilization output based on the monitoring result;
A control circuit for controlling an on / off period of the switching process based on the control value;
A pulse generation circuit that generates a pulse each time the calculation is performed in the calculation processing circuit;
The period of the pulse generated by the pulse generation circuit is compared with a reference period, and when the pulse period is lower than the reference period, it is determined that the calculation is normally performed, and the stabilization circuit is set in an operating state. And a determination circuit for determining that an abnormality has occurred in the operation when the pulse period exceeds a reference period and stopping the stabilization circuit. 2. The digitally controlled switching power supply device according to claim 1, wherein the stabilizing circuit is a constant voltage circuit that stabilizes an output voltage. 2. The digitally controlled switching power supply device according to claim 1, wherein the stabilizing circuit is a constant current circuit that stabilizes an output current. 2. The digitally controlled switching power supply device according to claim 1, wherein the control circuit is a pulse width modulation circuit that increases or decreases the pulse width of the switching on / off pulse in accordance with the control value. The output of the stabilization circuit that stabilizes and outputs the input signal by the switching process is digitized and monitored, and the control value of the switching process for the stabilized output is periodically calculated based on the monitoring result, and the control value Is used in a digital control switching power supply device that controls the on / off period of the switching processing based on
A pulse is generated each time the calculation is performed,
The period of the pulse is compared with a reference period, and when the pulse period is lower than the reference period, it is determined that the calculation is normally performed and the stabilization circuit is activated, and the pulse period is the reference period. A safety shut-off method for a digitally controlled switching power supply, characterized in that, when the value is further exceeded, it is determined that an abnormality has occurred in the operation and the stabilization circuit is stopped. 6. The safety shutoff method for a digitally controlled switching power supply device according to claim 5, wherein the stabilizing circuit is a constant voltage circuit that stabilizes an output voltage. 6. The safety shutoff method for a digitally controlled switching power supply device according to claim 5, wherein the stabilizing circuit is a constant current circuit that stabilizes an output current.

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