JP5738627B2 - Switching power supply device and starting method thereof - Google Patents

Description

  The present embodiment relates to a switching power supply device that supplies power to an RF module that requires a rectangular wave voltage, for example, in a radar transmission device, and a startup method thereof.

  As is well known, the RF module of the radar transmitter requires a rectangular wave voltage, and a switching power supply is used to supply power. The rise time required for this switching power supply is several μs or less, which is only a few switching times when converted to a period of a switching power supply of several hundred kHz to several MHz.

  In a conventional switching power supply device, a slow start method in which feedback control is started immediately after startup or after reaching a certain voltage is common. However, in the slow start method as described above, when starting up with several switching times, the error amplifier signal becomes too large immediately after starting up, the error amplifier becomes saturated and becomes uncontrollable. There was a problem that a large voltage fluctuation occurred.

JP 2004-297993 A JP 2004-297985 A JP 2006-180599 A

  As described above, in the conventional switching power supply device, when starting with a few switching times, the error amplifier signal becomes too large immediately after startup and the error amplifier becomes saturated, and the control becomes in an uncontrollable state. There was a problem that a large voltage fluctuation occurred later.

  The present embodiment has been made in view of the above problems, and a switching power supply device that can suppress the occurrence of large voltage fluctuations immediately after startup and can start up the voltage arbitrarily and at high speed with a predetermined number of pulses, and It aims at providing the starting method.

  In order to solve the above problem, a switching power supply according to the present embodiment includes a switching power supply circuit that controls an output voltage by controlling on / off of a switch element based on a drive signal, and a start instruction to the switching power supply circuit Pre-starting means for sending a drive signal of a predetermined on / off period over a certain period of time, monitor signal extracting means for extracting a monitor signal from the output voltage of the switching power supply circuit, and the monitor signal and reference signal Comparing means for obtaining an error signal by comparison and feedback control means for controlling an on / off period of the drive signal based on the error signal after the operation period of the preliminary activation means is completed.

  In addition, the switching power supply device startup method according to the present embodiment provides a switching power supply circuit that controls the output voltage by turning on / off the switch element based on the drive signal, over a certain period from the startup instruction. Preliminary start-up is performed to increase the output voltage by sending a drive signal of a predetermined on / off period, and a monitor signal is extracted from the output voltage of the switching power supply circuit, and the monitor signal is compared with a reference signal to obtain an error. A signal is obtained, and after completion of the preliminary activation operation period, feedback control is performed on the on / off period of the drive signal based on the error signal.

The block circuit diagram which shows the structure of the switching power supply device which concerns on this embodiment. The wave form diagram for demonstrating the principle of operation of this embodiment shown in FIG. The flowchart which shows the flow of a process of the arithmetic processing circuit of this embodiment shown in FIG.

  Hereinafter, this embodiment will be described with reference to the drawings.

  FIG. 1 is a block circuit diagram showing a configuration of a switching power supply device according to this embodiment. In FIG. 1, a switching power supply circuit 10 is supplied with a voltage Vin from an input voltage source 1 and supplies an arbitrary output voltage Vout to a load 2. The output voltage Vout is controlled by a drive circuit 16 that generates a drive signal for controlling on / off of the switch element.

  The switching power supply circuit 10 is a converter in a discontinuous mode shown in Patent Document 3, for example. This is merely an example, and a normal DC / DC converter may be used, and a simple switch element may be used.

  In order to monitor the output voltage Vout of the switching power supply circuit 10, the resistors 11 and 12 divide the voltage to an appropriate voltage and take it out as a monitor signal. This monitor signal is supplied to an A / D (analog / digital) converter 13. Here, resistors 11 and 12 for voltage division are included, but may be omitted if not necessary. The monitor signal is converted from an analog signal to a digital signal by the A / D converter 13 and supplied to the arithmetic processing circuit 14.

  In this arithmetic processing circuit 14, the monitor signal of the output voltage Vout supplied from the A / D converter 13 is compared with the reference signal generated by the internal reference signal source 141 by the error amplifier (difference calculation) 142, and the difference therebetween. An error signal corresponding to is obtained. The error signal thus obtained is supplied to a PID (Proportional Integral Differential) control circuit 144, for example. Further, data obtained by the calculation and error signal data are stored in the memory 145. The limiter 143 is for preventing the error signal from becoming excessive at the time of start-up, that is, overshooting, and may be removed after the start-up.

  Data of a predetermined pulse width at the time of activation is stored in the memory 145. At the time of activation, the pulse width data from the memory 145 is supplied to a PWM (Pulse Width Modulation) circuit 15, and after the activation, The calculation result of the PID control is supplied to the PWM circuit 15. The control method may be any method other than PID control as long as it is a control method that amplifies an error signal, such as PI control or robust control. Further, the switching power supply 10 is turned on / off by inputting a pulse signal from the pulse signal source 3 synchronized with the pulse output to the arithmetic processing circuit 14.

  For example, a signal that has been pulse width modulated by the PWM circuit 15 is output to the drive circuit 16, for example. The PWM circuit 15 may be any method as long as it controls the output voltage of the converter, such as PFM modulation or phase shift.

  For example, the drive circuit 16 amplifies the signal and controls on / off of the switching element of the switching power supply circuit 10. If the PWM circuit 15 is capable of driving on / off of the switching element of the switching power supply circuit 10, it may be omitted. In this case, the PWM circuit 15 is directly connected to the switching power supply circuit 10.

  In the circuit diagram of FIG. 1, the waveform of each part will be described with reference to FIG.

  For example, the switching power supply circuit 10 operates a converter in a discontinuous mode disclosed in Patent Document 3 by a two-phase operation. For simplification, the switch element represents only the high-side signal as PWM1 to PWM4, and the high level on the drawing is turned on. A pulse signal from the pulse signal source 3 synchronized with the pulse output is represented as an ON / OFF signal, and a high level on the drawing is turned on. Data values of the arithmetic processing circuit 14 to the PWM circuit 15 are represented as d1 to d8 and c1 to c8. d1 to d8 are data of a predetermined pulse width stored in the memory 145, and c1 to c8 are data of feedback control calculated by the PID control circuit 144. A circle on the output voltage Vout represents a sample point.

  When the activation instruction is given, the ON / OFF signal is turned from OFF to ON. At this time, predetermined pulse width data stored in the memory 145 and the PWM signal are output to the PWM1 to PWM4, respectively, and the switching power supply circuit 10 is turned on by the corresponding pulse width to start increasing the output voltage. By changing the data d1 to d8, the start-up time can be arbitrarily adjusted as long as it is equal to or less than the start-up limit speed of the switching power supply circuit 10.

  The discontinuous converter is a first-order lag system, and basically no overshoot occurs. Further, even during startup, data necessary for the PID control circuit 144 is sampled after startup and stored in the memory 145.

  Here, the value of the error signal obtained by comparing the monitor signal of the output voltage Vout with the reference signal is large, the calculation result of the PID control circuit 144 becomes an excessive value, and as a result, the output voltage Vout varies greatly. Suppose the situation. However, the error signal of a large fluctuation occurring at the time of start-up is limited by the limiter 143 to prevent an excessive voltage from being applied. As a result, it is possible to configure a switching power supply device that can be started at high speed without generating an overshoot with a small switching cycle, and can smoothly shift without causing voltage fluctuation even when shifting to feedback control. it can.

  A specific processing flow of the arithmetic processing circuit 14 is shown in FIG. In FIG. 3, in the initial state, all of PWM1 to PWM4 are in the OFF state (step S1). When the ON / OFF signal based on the pulse signal from the pulse signal source 3 is turned on (step S2), data 1 and 2 are output (step S3), and sampling data is acquired from the A / D converter 13 (step S2). S4). At this time, since the difference between the monitor signal of the output voltage Vout and the reference signal is large, the limiter 143 limits (step S5). Subsequently, data 3 and 4 are output (step S6), and sampling data is acquired from the A / D converter 13 (step S7). Even at this time, since the difference between the monitor signal of the output voltage Vout and the reference signal is large, the limiter 143 places a limit (step S8).

  Similarly, data 5 and 6 are output (step S9), and sampling data is acquired from the A / D converter 13 (step S10). Even at this time, since the difference between the monitor signal of the output voltage Vout and the reference signal is large, the limiter 143 places a limit (step S11). Subsequently, data 7 and 8 are output (step S12), and sampling data is acquired from the A / D converter 13 (step S13). At this time, when the difference between the monitor signal of the output voltage Vout and the reference signal falls within the allowable range, the PID control circuit 144 calculates the PID (step S14), and the PWM signal for the PWM1 to PWM4 based on the calculation result. Is calculated and output (step S15).

  At this time, the ON / OFF signal is monitored (step S16). If the signal remains ON (N), the processes of steps S13 to S15 are repeated. If it is OFF in step S16 (Y), the process returns to step S1 and enters an ON standby state.

  As described above, according to the present embodiment, an overshoot immediately after the switching power supply circuit is started can be generated, and the voltage can be started arbitrarily and at high speed with a predetermined pulse width. In particular, in order to prevent an excessive input from being applied to the error signal at the time of startup, the voltage fluctuation immediately after switching to feedback control can be prevented by reducing the sensitivity of the error signal.

  In addition, the said embodiment is not limited as it is, In the implementation stage, a component can be deform | transformed and embodied in the range which does not deviate from the summary. Moreover, an appropriate combination of a plurality of constituent elements disclosed in the above embodiment may be used. 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 1 ... Input voltage source, 2 ... Load, 3 ... Pulse signal source, 10 ... Switching power supply circuit, 11, 12 ... Resistance, 13 ... A / D converter, 14 ... Arithmetic processing circuit, 141 ... Reference signal source, 142 ... Error Amplifier (difference calculation), 143 ... limiter, 144 ... PID control circuit, 145 ... memory, 15 ... PWM circuit, 16 ... drive circuit.

Claims (5)

A switching power supply circuit that controls an output voltage by controlling on / off of a switch element based on a drive signal having an on period and an off period ;
A memory for storing pulse width data used in a preliminary start-up period over a predetermined period from the start instruction;
A modulation circuit that performs pulse width modulation on the drive signal in the preliminary activation period based on a pulse width stored in the memory;
Preliminary activation means for sending a drive signal output from the modulation circuit to the switching power supply circuit in the preliminary activation period ;
Monitor signal extraction means for extracting a monitor signal from the output voltage of the switching power supply circuit;
Comparison means for obtaining an error signal by comparing the monitor signal and a reference signal;
A switching power supply device comprising feedback control means for controlling an on / off period of the drive signal based on the error signal after the preliminary activation period ends . 2. The switching power supply device according to claim 1, further comprising a limiter that limits the error signal at a specified level at least during the preliminary activation period .   The switching power supply device according to claim 1, wherein the switching power supply circuit is a converter in a discontinuous mode. A method applicable to a switching power supply circuit that controls an output voltage by controlling on / off of a switch element based on a drive signal having an on period and an off period ,
The drive signal in the preliminary startup period over a certain period from the startup instruction is pulse width modulated based on the pulse width stored in the memory storing the pulse width data used in the preliminary startup period,
In the preliminary activation period, the pulse width modulated drive signal is sent to the switching power supply circuit to perform the preliminary activation to increase the output voltage,
A monitor signal is extracted from the output voltage of the switching power supply circuit,
An error signal is obtained by comparing the monitor signal with a reference signal,
An activation method for a switching power supply apparatus, comprising: feedback control of an on / off period of the drive signal based on the error signal after the preliminary activation period ends . 5. The method according to claim 4, further comprising limiting the error signal to a specified level at least during the preliminary activation period .

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