JP4076572B1 - Non-insulated booster circuit for inrush current - Google Patents

Abstract

An object of the present invention is to make it easy to start up from a capacitor power supply using a switching booster circuit without limiting the inrush current for a low resistance load at the time of start-up, and to prevent the boost switch from being destroyed by the inrush current.
A non-isolated boost circuit for inrush current that is activated by flowing an inrush current to a load 4 that is activated with a low resistance, and includes a booster circuit having a series reactor L1 and a booster switch SW1, and a booster switch SW1. PWM control means 2 for PWM control, a power switch SW3 connected in series to the output side of the booster circuit, and the power switch SW3 is turned on based on the start signal of the load 4 and then turned on. And a start control means 3 for turning on the power, and based on the start signal of the load 4, the power switch SW3 is turned on to cause an inrush current to flow through the load 4, and after the inrush current is attenuated, the PWM control means 2 is turned on to increase the voltage. .
[Selection] Figure 1

Description

The present invention relates to rush current corresponding non-insulated boost circuit that starts flowing the inrush current to the load is started with a low resistance.

For example, motors, incandescent bulbs, halogen heaters and the like have a low resistance at start-up and a low resistance load at start-up that is almost close to a short circuit state, and a large inrush current flows at start-up. For this reason, in such a power supply that supplies power to the low resistance load at the time of startup, means for suppressing the flow of a large inrush current is provided (see, for example, Patent Document 1).
Japanese Patent No. 3281822

  However, if the inrush current is limited at the time of starting the low resistance load at the time of starting as described above, there is a problem that it becomes difficult to start and time is required for starting. In a low temperature environment, the startup characteristics are further deteriorated and it is difficult to start up.

  Since the capacitor can supply a larger current than the secondary battery, the load startup time and standby time can be shortened. When a switching type boost converter is used for such a capacitor power supply and power is supplied to a low resistance load at start-up without limiting the inrush current, a large inrush current flows at start-up, which destroys the switching circuit of the boost converter.

  The present invention solves the above-mentioned problem. For a low resistance load at the time of start-up, it is easy to start up without limiting the inrush current from the capacitor power source using the switching booster circuit, and the inrush current This makes it possible to prevent the boost switch from being destroyed.

To this end, the present invention is a non-insulated booster circuit for inrush current that is activated by flowing an inrush current to a load that is activated with a low resistance, and includes a series reactor between a capacitor power source and the capacitor power source and an output terminal. And a series switch connected in series, and a booster circuit in which a booster switch that short-circuits the series circuit of the capacitor power supply and the series reactor is connected in parallel to the output side of the series reactor, and is connected in parallel to the output terminal of the booster circuit and a smoothing capacitor, a PWM control means for PWM controlling the series switch and the boost switch, and an output terminal of said boosting circuit and power-on switch connected in series between the load, based on said load activation signal the power-on switch on a start control means for turning on the PWM control means by a predetermined condition after to the oN, the negative Of the start signal to turn on the power-on switch based flow inrush current to the load from the capacitor being charged through said series reactor by the capacitor power supply, the rush current as the predetermined condition by the start control means After the attenuation, the PWM control means is turned on, and the boost switch and the series switch are boosted by PWM control .

Said activation control means, as said predetermined condition, said the power on switch is turned on, characterized in that to turn the PWM controller after a predetermined time has elapsed, also, the activation control means, as said predetermined condition, The PWM control means is turned on by determining that an inrush current flows through the load and the current has attenuated to a predetermined value after a peak.

  According to the present invention, the power supply switch connected in series to the output side of the booster circuit is turned on based on the start signal of the load, the inrush current is supplied to the load and the inrush current is attenuated, and then the PWM control means is turned on to boost the voltage. As a result, an inrush current can be passed when the load is activated to facilitate the activation, and the inrush current can prevent the boost switch of the booster circuit from being destroyed by the inrush current. Therefore, the load start time and standby time can be shortened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an embodiment of a non-insulated booster circuit for inrush current according to the present invention. 1 is a capacitor power supply, 2 is a PWM control unit, 3 is a start-up control unit, 4 is a load, C1, C2 C11 and C12 are capacitors, L1 is a series reactor, PD11 and PD12 are photodiodes, PT11 and PT12 are phototransistors, R11 to R17 are resistors, SW1 to SW3 are switch elements, and TR11 to TR13 are transistors.

  In FIG. 1 (a), a capacitor power source 1 is charged by a charging power source and discharged in response to a power supply request of a load 4. The load 4 has a low resistance at start-up and a motor or incandescent bulb that is almost in a short-circuit state. Low resistance load at start-up such as halogen heater. A series reactor L1 and switch elements SW2 and SW3 are connected in series between the capacitor power supply 1 and the load 4, and a switch element SW1 is connected to the output terminal of the series reactor L1, so that the capacitor power supply 1 and the series reactor L1 are connected. The series circuit is short-circuited. The series reactor L1 and the switch elements SW1 and SW2 constitute a circuit for stepping up and down by PWM (Pulse Width Modulation) control by turning on and off the switch elements SW1 and SW2 by the PWM controller 2. The switch element SW1 is a switch for boosting. In the boosting mode, the switch element SW1 is turned on and off by PWM control, and supplies power to the load 4 from the capacitor power supply 1 through the series reactor L1, switch elements SW2, and SW3 without passing through a transformer or the like. An insulated booster circuit is configured. The switch element SW2 is a step-down switch, and is turned on and off by PWM control in the step-down mode. The switch element SW3 is a so-called power-on switch for the load 4 that is turned on when the load 4 is activated. The switch elements SW1 to SW3 are illustrated as FET elements, but may be thyristor elements or contacts. Capacitors C1 and C2 connected to the input side of series reactor L1 and the output side of switch element SW2 are for smoothing. The start control unit 3 controls the switch element SW3 to be turned on (SW3-ON) and the PWM control unit 2 to be turned on (PWM-ON) in accordance with a start (on) signal for starting the load 4. The switch element SW3 is turned on to allow the inrush current to flow from the capacitor C2 charged through the series reactor L1 by the capacitor power supply 1 to the load 4 to easily start the load 4, and then the PWM controller 2 is turned on under a predetermined condition. To.

  FIG. 1B shows a specific circuit configuration example of the activation control unit 3. In FIG. 1B, an activation (on) signal for activating the load 4 is input to the base-emitter circuit of the NPN transistor TR11 through a parallel circuit of a resistor R11 and a capacitor C11. The resistor R12 and the photodiode PD11 are connected in series to the collector of the transistor TR11, and an on (SW3-ON) signal of the switch element SW3 is output from the photodiode PD11 and the phototransistor PT11 that constitutes the photocoupler.

  A series circuit of resistors R13 and R14 is connected in parallel to a series circuit of the resistor R12 and the photodiode PD11, and an emitter-base circuit of a PNP transistor TR12 is connected to the resistor R13. Further, a series circuit of a resistor R15 and a resistor R16 is connected to the collector of the transistor TR12, and a capacitor C12 and a base-emitter circuit of an NPN transistor TR13 are connected in parallel to the resistor R16. The resistor R17 and the photodiode PD12 are connected in series to the collector of the transistor TR13, and an on (PWM-ON) signal of the PWM control unit 2 is output from the photodiode PD12 and the phototransistor PT12 constituting the photocoupler.

  When a start (on) signal for starting the load 4 is input by the circuit of the start control unit 3, the transistor TR11 is turned on, and the switch element SW3 is turned on via the photocoupler photodiode PD11-phototransistor PT11. To do. When the transistor TR11 is turned on, the transistor TR12 is also turned on, and after the time delay until the voltage of the capacitor C12 reaches the voltage for turning on the transistor TR13, the transistor TR13 is turned on and the photodiode PD12− of the photocoupler is turned on. The PWM controller 2 is turned on via the phototransistor PT12. As described above, after the switch element SW3 is turned on and delayed for a predetermined time, the PWM control unit 2 is turned on. Therefore, an inrush current can be passed through the load 4 during this period to shorten the startup time of the load 4. it can. Further, while the inrush current is flowing, the on / off operation of the switch element SW1 by PWM control is not performed, and the on / off operation of the switch element SW1 is performed after the inrush current is attenuated. It is possible to prevent the switch element SW1 from being destroyed by the inrush current.

  FIG. 2 is a diagram for explaining the timing of load activation and PWM control, FIG. 3 is a diagram for explaining another embodiment of a non-insulated booster circuit for inrush current according to the present invention, and FIG. 4 is a diagram showing the activation shown in FIG. FIG. 5 is a diagram illustrating a configuration example of the control unit, and FIG. 5 is a diagram illustrating another configuration example of the activation control unit illustrated in FIG. 3. 1, the same reference numerals as those in FIG. 1 denote the same elements as in FIG. 1, 21 is a signal falling detection circuit, 22 is a signal rising detection circuit, 23, 28 and 30 are latch circuits, 24 and 25 are comparators, and 26 is Inverter, 27 and 29 are AND circuits, PD21 and PD22 are photodiodes, PT21 and PT22 are phototransistors, R1 is a current detection resistor, R21 to R24, R31 to R36 are resistors, TR21 to TR25 are transistors, and X31 is a shunt regulator Indicates.

In the embodiment shown in FIG. 1, a delay time is used to delay a certain time from when the switch element SW3 that supplies power to the load 4 is turned on until PWM control is turned on. by detecting the inrush current as shown, it may control the timing of on of the PWM control to determine the inrush current at the reference value V _s. In order for this inrush current when it is determined that the to decay to the reference value V _s, it is necessary to enable the determination circuit of the reference value V _s by the reference value V _r shown higher in Fig. 2 it. The embodiment will be described with reference to FIGS.

  In the embodiment shown in FIG. 3, the current detection resistor R1 is inserted and connected in series with the output of the capacitor power supply 1, and the activation control unit 3 turns on the switch element SW3 by activation (ON), and then detects the current. It is determined that the inrush current based on the current detected by the resistor R1 has attenuated, and the PWM control unit 2 is turned on (PWM-ON). For example, the activation control unit 3 is shown in FIGS. 4 and 5.

In FIG. 4, a signal falling detection circuit 21 inputs a start (ON) signal and detects its falling, and a signal rising detection circuit 22 similarly inputs a start (ON) signal and detects its rising. A detection pulse is output at the time of detection. The latch circuit 23 latches with the detection pulse from the signal rise detection circuit 22 and outputs an ON (SW3-ON) signal of the switch element SW3. The comparator 24 compares enter the detection value V _I and the reference value V _r of the current detected by the current detecting resistor R1, the detection value V _I of the current exceeds the reference value V _r, so far A signal that changes from L to H is output. The comparator 25 compares enter the detection value V _I and the reference value V _s of the current detected by the current detecting resistor R1, the detection value V _I of the current exceeds the reference value V _s, the far The inverter 26 outputs a signal that changes from L to H. The inverter 26 inverts the output of the comparator 25, and when the detected current value V _I attenuates to the reference value V _s , the inverter 26 inverts the L signal of the comparator 25. Output a signal. The AND circuit 27 ANDs the output of the latch circuit 23 and the output of the comparator 24 and latches the result in the latch circuit 28. The AND circuit 29 AND-processes the output of the latch circuit 28 and the output of the comparator 25 inverted by the inverter 26, latches the result in the latch circuit 30, and turns on the PWM controller 2 (PWM-ON). Output a signal. The latch circuits 23, 28 and 30 are cleared by the detection pulse from the signal falling detection circuit 21.

  According to the above circuit, the latch circuit 23 is latched at the timing t0 shown in FIG. 2, the switch element SW3 ON (SW3-ON) signal is output, and the latch circuit 28 is latched at the timing t1. When the inrush current is attenuated after the latch circuit 28 is latched, the AND condition of the AND circuit 29 is established at the timing t2, the latch circuit 30 is latched, and the PWM control unit 2 is turned on (PWM-ON). A signal is output.

In the circuit shown in FIG. 5, instead of the delay circuit shown in FIG. 1 (b), the photodiode PD12 and the phototransistor PT12 constituting the photocoupler are turned on (PWM−) at the timing when the inrush current is attenuated. ON) signal output circuit. In FIG. 5A, a circuit comprising a phototransistor PT21, resistors R21 and R22, and transistors TR21 and TR22 is connected in parallel to a series circuit of a resistor R12 and a photodiode PD11, and a current detection value V _I is a reference value V. _{When r} is exceeded, the transistor TR22 is turned on. In this circuit, the collector-base of the NPN transistor TR22 and the base-collector of the PNP transistor TR21 are connected to each other, and the phototransistor PT21 is turned on when the detected current value V _I exceeds the reference value V _r. A base current for turning on TR22 is supplied.

Further, when a circuit composed of the phototransistor PT22, resistors R23 to R24, and transistors TR23 to TR25 is connected and the current detection value V _I is attenuated to the reference value V _s , the transistor TR13 is turned on, and the photodiode PD12 of the photocoupler is turned on. -Outputs an ON (PWM-ON) signal of the PWM control unit 2 via the phototransistor PT12. In this circuit, through a resistor R23 to the collector of the NPN transistor TR23 to be turned on with ON of the transistor TR22, the base of the phototransistor PT22, PNP transistor TR24 to be turned on when the detected value V _I of the current exceeds the reference value V _s - Emitter Connect the parallel circuit of the circuit. The transistor TR13 also has its collector-base circuit and the base-collector circuit of the PNP transistor connected to each other, the collector output of the transistor TR24 is connected to the base of the transistor TR13, and the transistor TR13 is turned on by the transistor TR24. Supply the base current.

FIG. 5 shows a configuration example of a circuit that detects a current exceeding the reference value by comparing the detected value V _{I of the} current detected by the current detection resistor R1 with the reference values V _r and V _s . b). In the circuit shown in FIG. 5B, the detection value V _{I of the} current detected by the current detection resistor R1 is applied to a series circuit of resistors R31 and R32 and a series circuit of resistors R34 and R35. Then, a series connection point between the resistance R31 and R32 connected to the base of an NPN transistor TR31, to connect the reference voltage source Ref of the reference value V _r to the emitter, and a resistor R33 and the photodiode PD21 to the collector When the detected current value V _I exceeds the reference value V _r , the phototransistor PT21 is turned on via the photodiode PD21. The resistance R34 and the series connection point connected to the gate of the shunt regulator X31 operating at the reference value V _s of the R35, and a resistor R36 and the photodiode PD22 to an anode, the detection value V _I is the reference value of the current When V _s is exceeded, the phototransistor PT22 is turned on via the photodiode PD22. These circuits may have a configuration using transistors, a configuration using a shunt regulator, or another configuration, and the circuits having the same configuration are usually used for each. For example, circuits having different configurations are shown. Is.

Next, the operation of the circuit shown in FIG. 5 will be described. When an activation (on) signal is input, the transistor TR11 is first turned on, and the phototransistor PT11 is turned on via the photodiode PD11, whereby an on (SW3-ON) signal of the switch element SW3 is output. At this time, the detected current value V _I is smaller than the reference values V _r and V _s , and the phototransistors PT21 and PT22 are off, so that the transistor TR21 is off. Accordingly, all of the other transistors TR22 to TR24 and TR13 are off. When an inrush current flows through the load 4 and the detected current value V _I increases and first exceeds the reference value V _s , the phototransistor PT22 is turned on, but since the transistor TR23 is turned off, the other transistors TR24, TR13 also remains off. When the detected current value V _I further increases and exceeds the reference value V _r , the phototransistor PT21 is also turned on, the transistors TR22 and TR23 are turned on, and the transistor TR24 is also turned on. At this time, the transistor TR24 is kept off because the phototransistor PT22 is on and the emitter-base circuit is short-circuited.

Thereafter, even when the inrush current passes the peak and starts to attenuate, the detected value V _{I of the} current becomes smaller than the reference value V _r and the phototransistor PT21 is turned off, so that the transistor TR21 in which the base-collector circuits are connected to each other And TR22 are kept on, and the transistor TR23 is also kept on. That is, the transistors TR21 and TR22 are holding circuits that hold the ON state regardless of whether the phototransistor PT21 is turned on or off after the phototransistor PT21 is turned on.

Further, when the detected current value V _I becomes smaller than the reference value V _s and the phototransistor PT22 is turned off, the transistor TR24 is turned on, so that the transistor TR13 is turned on and the PWM controller 2 is turned on (PWM-ON) signal. Is output. When the transistor TR25 is turned on by turning on the transistor TR13, and thereafter, the transistor TR13 and the transistor TR25 are also turned on regardless of whether the transistor TR24 is turned on or off when the transistor TR24 is turned on. . In this way, the hold circuit consisting of the transistors TR21 to TR23 and the hold circuit consisting of the transistors TR25 and TR13 are activated (on) from H to L depending on the load 4 stop mode. Thus, the transistor TR11 is reset when it is turned off.

  FIG. 6 is a diagram for explaining another embodiment of a non-insulated booster circuit for inrush current according to the present invention. In the above embodiment, the power-on switch SW3 of the load 4 is inserted between the output 4 of the booster circuit and the load 4 between the capacitor power supply 1 on the input side of the booster circuit as shown in FIG. 1 may be inserted. In the embodiment shown in FIG. 1, since the power-on switch SW3 is connected to the output side of the non-insulated booster circuit, the capacitor power source 1 It is impossible to prevent leakage current from flowing into the booster circuit by the power-on switch SW3.However, according to the embodiment shown in Fig. 6, the power-on switches SW3 'and SW3 "are connected to the input side of the booster circuit. Therefore, it is possible to prevent leakage current from flowing through the booster circuit. In the case of the embodiment shown in FIG. 1, the power-on switch SW3 only allows the inrush current of the load 4 to flow when the power is turned on. Therefore, the current capacity may be designed for the inrush current. However, in the case of the embodiment shown in FIG. 6, since the power is turned on at the input side of the booster circuit, not only the inrush current of the load 4 flows but also the inrush current also flows in the capacitors C1 and C2. Flowing. Therefore, as the power-on switch SW3 ′ shown in FIG. 6A, one having a larger current capacity than the power-on switch SW3 shown in FIG. 1 is required. Further, in order to keep the current capacity of the power-on switch SW3 ′ small, as shown in FIG. 6B, a power-on switch SW3 ″ in which a current limiting resistor R3 ″ is connected in series is connected in parallel with the power-on switch SW3 ′. First, after the power-on switch SW3 ″ connected in series with the current limiting resistor R3 ″ is powered on, the power-on switch SW3 ′ is turned on with a time difference, and the timing control of the power-on switches SW3 ′ and SW3 ″ is performed. Therefore, the embodiment shown in Fig. 6 has a longer startup time than the embodiment shown in Fig. 1, but the inrush current of the load 4 is greatly limited by the embodiment shown in Fig. 6. By starting without starting, the load 4 such as a motor, an incandescent bulb, and a halogen heater can be substantially started easily, and the boost switch is destroyed by the inrush current. It can be prevented.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the circuit configured using a transistor as the activation control unit has been described, but it is needless to say that details can be appropriately changed depending on the design. For example, in the circuit shown in FIG. 5, the hold circuit composed of the transistors TR21 to TR23 and the hold circuit composed of the transistors TR25 and TR13 are reset by the stop mode of the load 4, but the hold circuit composed of the transistors TR21 to TR23 It may be reset by a hold circuit composed of TR25 and TR13. Further, the resistor R23 may be connected to the collector of the transistor TR22 to omit the transistor TR23, or the transistor TR25 and the resistor R24 may be omitted. Eliminating the transistor TR25 and the resistor R24, the elimination of the hold circuit, by setting larger than the detection value within the range of current flowing through the load 4 in the normal state reference value V _s, during normal operation of the load 4, Photo The transistor PT22 is never turned off. However, if the abnormal current exceeding the reference value V _s flow in the normal state can phototransistor PT22 is turned off, to turn off the transistor TR13, to turn off the PWM control. Further, this signal can be used as an abnormality notification signal and a signal for turning off the switch element SW3.

The figure explaining embodiment of the non-insulation type | mold boost circuit corresponding to the inrush current which concerns on this invention. The figure explaining the starting of load and the timing of PWM control. The figure explaining other embodiment of the non-insulation type | mold boost circuit corresponding to the inrush current which concerns on this invention. The figure which shows the structural example of the starting control part shown in FIG. The figure which shows the other structural example of the starting control part shown in FIG. The figure explaining other embodiment of the non-insulation type | mold boost circuit corresponding to the inrush current which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Capacitor power supply, 2 ... PWM control part, 3 ... Start-up control part, 4 ... Load, C1, C2, C11, C12 ... Capacitor, L1 ... Series reactor, PD11, PD12 ... Photodiode, PT11, PT12 ... Phototransistor, R11 to R17 ... resistors, SW1 to SW3 ... switch elements, TR11 to TR13 ... transistors

Claims (3)

A non-insulated booster circuit for inrush current that starts by flowing an inrush current to a load that is started with low resistance,
A capacitor power supply;
A booster circuit in which a series reactor and a series switch are connected in series between the capacitor power supply and an output terminal, and a booster switch that short-circuits the series circuit of the capacitor power supply and the series reactor is connected in parallel to the output side of the series reactor; ,
A smoothing capacitor connected in parallel to the output terminal of the booster circuit;
PWM control means for PWM controlling the boost switch and the series switch ;
A power-on switch that is connected in series between the load and the output terminal of the booster circuit,
And a start control means for turning on the PWM control means by a predetermined condition after turn on the power-on switch on the basis of the load start signal and to the ON, turns on the power-on switch on the basis of the activation signal of the load Then, an inrush current is caused to flow from the capacitor charged through the series reactor by the capacitor power source to the load, and the PWM control means is turned on after the inrush current is attenuated as the predetermined condition by the activation control means. A non-insulated booster circuit for inrush current , wherein the booster switch and the series switch are boosted by PWM control . Said activation control means, said a predetermined condition, the rush current corresponding non-isolated step-up circuit according to claim 1, wherein the turning on the PWM control means after a predetermined time to turn the power on switch. The start control means determines that the inrush current flows through the load and the current has attenuated to a predetermined value as the predetermined condition, and turns on the PWM control means. A non-insulated booster circuit corresponding to inrush current according to 1.

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