JP5123761B2 - Switching power supply - Google Patents

Description

  The present invention relates to an interleaved switching power supply, and more particularly, to a switching power supply suitable when critical boost chopping converters are connected in parallel.

  For example, a conventional interleave type switching power supply as shown in FIG. 5 is known. As shown in the figure, this interleaved switching power supply has two step-up chopper circuits 101 and 102 connected in parallel. The step-up chopper circuit 101 connects an inductor L101, a switching element Q101, and a diode D101 in a T-type connection. The step-up chopper circuit 102 is configured by connecting the inductor L102, the switching element Q102, and the diode D102 in a T shape.

  In this interleaved switching power supply, the pulsating current obtained by rectifying the AC of the commercial power supply with the rectifier circuit 110 is boosted and chopped by the boost chopper circuits 101 and 102 under the control of the control unit 120, and the output thereof is output. The capacitor C101 is smoothed and supplied to the load, and the AC of the commercial power supply is supplied through the line filter 130.

  The control unit 120 detects the input voltage detection value ea of the boost chopper circuits 101 and 102 obtained by the voltage dividing resistors R101 and R102, the detection value ec of the input current of the boost chopper circuits 101 and 102 obtained by the current detection resistor R100, and the division. The switching elements Q101 and Q102 are controlled by control signals G1 and G2 based on the detected value eb of the output voltage of the capacitor C101 obtained by the piezoresistors R103 and R104 (see, for example, Patent Document 1).

  By the way, in the interleave type switching power supply having a critical type chopping converter, the current flowing through the diode on the slave side becomes zero, and the voltage applied to the slave side switching element is minimized (Vds resonance lowest point). Ideally, an ON trigger is supplied to the switching element. However, when the on-width of the master-side main SW is shorter than the on-width of the slave-side main SW, as indicated by a point “A” in FIG. The slave-side switching element is turned on while the current is flowing through the slave-side diode, and the slave-side current continuous mode is set, resulting in a current waveform as shown in “Slave-side current waveform” in FIG.

In order to avoid such a state, it is necessary to shorten the ON width on the slave side with respect to the ON width of the main SW on the master side, and a circuit as shown in FIG. 8 has been proposed.
JP-A-5-328783

  However, the circuit as shown in FIG. 8 requires a special circuit for controlling the interleaving as shown in the point “B” in the figure, and there is a problem that the configuration of the power supply itself becomes complicated and complicated.

  Accordingly, the present invention has been made in view of the above-described problems, and provides a switching power supply that shortens the ON width on the slave side with respect to the ON width of the master SW on the master side with a simple circuit configuration. With the goal.

  The present invention proposes the following items in order to solve the above-described problems.

  (1) The present invention includes a master-side power supply and a slave-side power supply, each of which rectifies the commercial power supply (for example, equivalent to D101 in FIG. 1) and boosts chopping the output of the rectifier circuit, respectively. In each of the interleave type switching power supplies including a critical step-up chopping converter and an output voltage detection circuit (for example, equivalent to the output voltage detection unit 2 in FIG. 1) for detecting the output voltage of the critical step-up chopping converter A critical boost chopping converter is connected to the output of the rectifier circuit, and includes a transformer (for example, corresponding to Np1 in FIG. 1) and a control winding (for example, corresponding to Nc1 and Nc2 in FIG. 1). For example, it corresponds to T101 in FIG. 1), a drive circuit for controlling on / off of the switching element (for example, equivalent to the driver units 4 and 14 in FIG. 1), and an on-width control means for controlling the on-width of the switching element. (E.g., corresponding to the master-side ON width control unit 3 and the slave-side ON width control unit 13 in FIG. 1), and the master-side on-width control unit is configured to perform the above operation according to the voltage value by the output voltage detection circuit. The on-width control unit on the slave side controls the on-width of the switching element, and the on-width control unit on the slave side determines the on-width of the on-width control unit on the master side and the on-width control unit on the slave side from the voltage value by the output voltage detection circuit. A switching power supply characterized by controlling the ON width of the switching element with a voltage value obtained by subtracting the voltage for correcting the setting variation of To have.

  According to the present invention, the master-side on-width control means controls the on-width of the switching element based on the voltage value of the output voltage detection circuit, and the slave-side on-width control means controls the voltage value of the output voltage detection circuit. Since the ON width of the switching element is controlled by a voltage value obtained by subtracting the voltage for correcting the ON width setting variation of the ON side control means on the master side and the ON width control means on the slave side, The ON width on the slave side can be made shorter than the ON width of the main SW on the side.

  (2) The present invention is a rectifier circuit for rectifying a commercial power supply (e.g., corresponding to D101 in FIG. 2) and n (n: positive integer) critical boost choppings that respectively boost the output of the rectifier circuit. In an interleave type switching power supply comprising a converter and an output voltage detection circuit (for example, equivalent to the output voltage detection unit 2 in FIG. 2) for detecting the output voltage of the critical boost chopping converter, the respective critical boost chopping A converter is connected to the output of the rectifier circuit, and includes a transformer (for example, equivalent to T101 in FIG. 2) including a choke winding and a control winding, and a switching element provided between the other end of the transformer and the ground ( For example, it corresponds to MOS1, MOS2, and MOS3 in FIG. 2 and a drive circuit that controls on / off of the switching element (eg 2 and the ON width control means for controlling the ON width of the switching element (for example, the master side ON width control unit 3, the slave side ON width control unit 13, FIG. 2), And the first on-width control means controls the on-width of the switching element according to the voltage value of the output voltage detection circuit and the kth (1 ≦ k ≦ n) on-state. A voltage obtained by subtracting a voltage for correcting the setting variation of the on widths of the k-th on-width control unit and the (k−1) -th on-width control unit from the voltage value of the output voltage detection circuit. The switching power supply is characterized in that the ON width of the switching element is controlled by the value.

  According to this invention, the first on-width control means controls the on-width of the switching element based on the voltage value of the output voltage detection circuit, and the kth (1 ≦ k ≦ n) on-width control means includes The on-width of the switching element is a voltage value obtained by subtracting the voltage for correcting the on-width setting variation of the k-th on-width control means and the (k-1) -th on-width control means from the voltage value by the output voltage detection circuit. Therefore, even in an interleave type switching power source in which n critical type step-up chopping converters are connected in parallel, an ideal current critical type power source can be configured.

  According to the present invention, the ON width of the switching element is controlled by the voltage value of the output voltage detection circuit, and the ON width control means on the master side and the ON width control means on the slave side are determined from the voltage value of the output voltage detection circuit. By controlling the ON width of the switching element with a voltage value obtained by reducing the voltage for correcting the ON width setting variation, the slave side continuous current operation can be reliably avoided with a simple circuit configuration. There is. A similar effect can also be obtained in an interleaved switching power supply in which n critical boost chopping converters are connected in parallel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

<First Embodiment>
A first embodiment of the switching power supply according to the present invention will be described with reference to FIGS. 1, 3, and 4.

<Configuration of switching power supply>
As shown in FIG. 1, the switching power supply according to the present embodiment includes a D101 that constitutes a rectifier circuit, an output capacitor C122, a critical boost chopping converter on the master side, and a critical boost chopping converter on the slave side. ing.

  The critical boost chopping converter on the master side includes a transformer T101 composed of a choke coil Np1 and control windings Nc1, Nc2, a diode D103, an ON trigger detection unit 1, an output voltage detection unit 2, and a master side ON width control. It is comprised from the structure from the part 3, the driver part 4, the overcurrent detection part 5, and MOS1 which is a switching element.

  On the other hand, the critical boost chopping converter on the slave side includes a choke coil Np2, a diode D104, an ON trigger detection unit 11, a slave side ON width control unit 13, a driver unit 14, an overcurrent detection unit 15, and a switching unit. The device is composed of a MOS2 as an element. Further, an ON width subtraction unit 7 is provided between the output of the output voltage detection unit 2 and the slave-side ON width control unit 13.

  The D101 constituting the rectifier circuit supplies a pulsating flow obtained by full-wave rectification of the alternating current of the commercial power supply to the choke coil Np1 of the transformer T1 and the choke coil Np2 on the slave side. Both the choke coil Np1 and Np2 store electromagnetic energy by the voltage applied between the terminals of the choke coil Np1 and Np2 when the switching element MOS1 or MOS2 is ON, and the switching element MOS1 or MOS2 is OFF. In some cases, the accumulated electromagnetic energy is supplied to the load via the diode D103 or D104.

  One end of the control winding Nc1 of the transformer T1 is connected to the master-side ON trigger detection unit 1 via a resistor R107, and supplies a signal corresponding to the current flowing through the choke coil Np to the ON trigger detection unit 1. Similarly, one end of the control winding Nc2 of the transformer T1 is connected to the slave-side ON trigger detection unit 11 via the resistor R108, and supplies a signal corresponding to the current flowing through the choke coil Np1 to the ON trigger detection unit 11. . This signal becomes a trigger signal for turning on the switching element MOS1 or MOS2 in the ON trigger detection units 1 and 11.

  The ON trigger detection units 1 and 11 detect a trigger signal for turning on the switching element MOS1 or MOS2 based on a signal from the control winding Nc1 or Nc2. Specifically, the ON trigger detection unit 1 detects the trigger signal using the vibration of the control winding Nc1 coupled to the choke coil Np1 when the current of the diode D103 becomes zero, and the ON trigger detection unit 11 detects the trigger signal by utilizing the fact that the polarity of the control winding Nc2 is inverted at the timing when the switching element MOS1 is turned off.

  For example, the output voltage detection unit 2 compares the divided voltage value of the resistor for detecting the output voltage with the reference voltage, detects the output voltage according to the comparison result, and the detected voltage is the master side Input to the ON width controller 3.

  The master-side ON width control unit 3 generates an OFF trigger pulse for controlling the ON width based on the voltage detected by the output voltage detection unit.

  The driver units 4 and 14 supply driving pulses to the switching element MOS1 or MOS2 by the ON trigger supplied from the ON trigger detection units 1 and 11, and from the master side ON width control unit 3 or the slave side ON width control unit 13 The drive pulse to the switching element MOS1 or MOS2 is turned OFF by the supplied OFF trigger pulse.

  When the switching element MOS1 or MOS2 is in the ON state, the overcurrent detection units 5 and 15 detect the current flowing through the switching element MOS1 or MOS2 by converting the voltage into a voltage, and compare this value with a predetermined threshold voltage. Then, overcurrent detection is performed.

  The ON width subtraction unit 7 subtracts the voltage for correcting the ON width setting variation of the master side ON width control unit 3 and the slave side ON width control unit 13 from the voltage detected by the output voltage detection unit 2. The voltage is supplied to the slave-side ON width control unit 13. The slave-side ON width control unit 13 generates an OFF trigger pulse for controlling the ON width based on the voltage input from the ON width subtraction unit 7.

  Here, the master-side ON width control unit 3 and the slave-side ON width control unit 13 generally have a timer circuit in order to control the ON width, but there is a variation in the elements constituting the timer circuit. As a result, the ON width varies, and the ON width on the master side may be shorter than the ON width on the slave side. At this time, the slave-side current continuous mode as described above occurs. In the present embodiment, in order to avoid this, the ON width subtraction unit 7 detects the ON widths of the master side ON width control unit 3 and the slave side ON width control unit 13 with respect to the voltage detected by the output voltage detection unit 2. The voltage obtained by subtracting the voltage for correcting the setting variation is supplied to the slave-side ON width control unit 13 so that the master-side ON width is always shorter than the slave-side ON width.

<Operation waveform>
3 and 4 show operation waveforms of the present embodiment. FIG. 3 shows an output voltage waveform, a slave-side current waveform, and a master-side current waveform in order from the top. FIG. 4 shows the gate signal supplied to the switching element MOS1 or MOS2, and the master-side and slave-side waveforms. The current waveform is shown.

  Focusing on the point “C” in FIG. 4, the slave-side switching element is turned on after the current flowing through the slave-side diode D104 becomes zero, and the generation condition of the slave-side current continuous mode can be avoided. I understand. This is apparent from the “slave-side current waveform” in FIG.

  Therefore, according to the present embodiment, by providing the ON width subtraction unit and making the ON width on the master side longer than the ON width on the slave side, the slave-side current continuous operation can be reliably avoided with a simple configuration. be able to.

<Second Embodiment>
Next, a second embodiment according to the switching power supply of the present invention will be described with reference to FIG.

<Configuration of switching power supply>
As shown in FIG. 2, the switching power supply according to the present embodiment is configured by connecting D101 that constitutes a rectifier circuit, an output capacitor C122, and n critical step-up chopping converters in parallel. Note that the function of each component is the same as in the first embodiment, and a detailed description thereof will be omitted. In the following, in order to make the explanation easy to understand, three critical boost chopping converters (hereinafter referred to as “first critical boost chopping converter” and “second critical boost chopping converter” in order from the upper side of FIG. 2). , “Third critical step-up chopping converter”) will be described in comparison with the first embodiment.

  First, in the second critical step-up chopping converter, a control winding Nc3 is provided facing the choke coil Np2, and one end of the control winding Nc3 is connected to the ON trigger of the third critical step-up chopping converter via a resistor R109. It is connected to the detection unit 21.

  In addition, the voltage on the slave side ON width control unit 23 of the third critical step-up chopping converter is input with respect to the output voltage of the output voltage detection unit 2 via the ON width subtraction unit 7 and the ON width subtraction unit 17. Has been.

  Here, the ON width subtracting unit 17 is connected to the slave side ON width control unit 13 of the second critical boost chopping converter and the slave side of the third critical boost chopping converter with respect to the output voltage of the ON width subtracting unit 7. The voltage obtained by subtracting the voltage for correcting the ON width setting variation of the ON width control unit 23 is supplied to the slave side ON width control unit 23.

Therefore, the relationship between the ON width of MOS1 in the first critical boost chopping converter, the ON width of MOS2 in the second critical boost chopping converter, and the ON width of MOS3 in the third critical boost chopping converter is:
The ON width of MOS1> the ON width of MOS2> the ON width of MOS3. This relationship is the same when three or more critical boost chopping converters are connected in parallel.

  As described above, according to the present embodiment, an ON width subtraction unit is also provided in an interleave type switching power supply configured by connecting n critical step-up chopping converters in parallel, and each ON width is provided. By satisfying the above relationship, the slave-side current continuous operation can be reliably avoided with a simple configuration.

  Note that the present invention is not limited to the above-described embodiments, and various modifications and applications are possible without departing from the spirit of the present invention.

It is a block diagram which shows the structure of the switching power supply which concerns on 1st Embodiment. It is a block diagram which shows the structure of the switching power supply which concerns on 2nd Embodiment. It is a wave form diagram of each part in the switching power supply concerning a 1st embodiment. It is a wave form diagram of each part in the switching power supply concerning a 1st embodiment. It is a block diagram which shows the structure of the switching power supply which concerns on a prior art example. It is a wave form diagram of each part in the switching power supply concerning a prior art example. It is a wave form diagram of each part in the switching power supply concerning a prior art example. It is a block diagram which shows the structure of the switching power supply which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11, 21 ... ON trigger detection part 2 ... Output voltage detection part 3 ... Master side ON width control part 4, 14, 24 ... Driver part 5, 15, 25 ... Overcurrent Detection unit 13, 23 ... Slave ON width control unit 7, 17 ... ON width subtraction unit C108 ... Input capacitor C122 ... Output capacitor D101 ... Rectifier circuit D103, D104, D105 ... Diode MOS1, MOS2, MOS3 ... Switching element Np1, Np2, Np3 ... Choke coil Nc1, Nc2, Nc3, Nc4 ... Control winding T101 ... Transformer

Claims (2)

A master side power supply and a slave side power supply, each rectifying a commercial power supply, a critical boost chopping converter for boosting chopping the output of the rectifier circuit, and an output voltage of the critical boost chopping converter In an interleaved switching power supply with an output voltage detection circuit to detect,
Each of the critical boost chopping converters is
A transformer connected to the output of the rectifier circuit and comprising a choke winding and a control winding;
A switching element provided between the other end of the transformer and ground,
A drive circuit for controlling on / off of the switching element;
An on-width control means for controlling the on-width of the switching element;
With
The master-side on-width control means controls the on-width of the switching element according to the voltage value by the output voltage detection circuit, and the slave-side on-width control means determines from the voltage value by the output voltage detection circuit. The on-width of the switching element is controlled by a voltage value obtained by subtracting the voltage for correcting the on-width setting variation of the master-side on-width control means and the slave-side on-width control means. Switching power supply. A rectifying circuit for rectifying a commercial power supply, n (n: positive integer) critical boost chopping converters for boosting chopping the output of the rectifier circuit, and an output voltage for detecting an output voltage of the critical boost chopping converter In an interleaved switching power supply with a detection circuit,
Each of the critical boost chopping converters is
A transformer connected to the output of the rectifier circuit and comprising a choke winding and a control winding;
A switching element provided between the other end of the transformer and ground,
A drive circuit for controlling on / off of the switching element;
An on-width control means for controlling the on-width of the switching element;
With
The first on-width control means controls the on-width of the switching element according to the voltage value of the output voltage detection circuit, and the kth (1 ≦ k ≦ n) on-width control means controls the output voltage detection. The on-width of the switching element is a voltage value obtained by subtracting the voltage for correcting the setting variation of the on-width of the k-th on-width controller and the k−1-th on-width controller from the voltage value by the circuit. A switching power supply characterized by controlling.