JP4389596B2 - DC power supply - Google Patents

Description

  The present invention relates to a simple and inexpensive DC power supply device capable of improving power factor.

  A conventional DC power supply device with improved power factor is shown in FIG. 9 (Patent Document 1). In FIG. 9, a full-wave rectifier circuit B1 is connected to both ends of the AC power supply Vac1, and a reactor L1, a capacitor C2, and an FET are disposed between the positive-side output terminal P1 and the negative-side output terminal P2 of the full-wave rectifier circuit B1. A series circuit with a main switch Q1 is connected. Between the connection point of the capacitor C2 and the main switch Q1 and the negative output terminal P2 of the full-wave rectifier circuit B1, the primary winding 5a (number of turns n1) of the transformer T and the tertiary winding 5c ( A series circuit of a winding number n3) and a power supply capacitor C1 (hereinafter abbreviated as capacitor C1) is connected. A diode D1 is connected between a connection point between the reactor L1 and the capacitor C2 and a connection point between the primary winding 5a and the tertiary winding 5c of the transformer T. A diode Dq1 is connected to the main switch Q1 in parallel.

  Instead of providing the primary winding 5a and the tertiary winding 5c of the transformer T separately, the cathode of the diode D1 is positioned at the intermediate tap n1: n3 of the primary winding (number of turns (n1 + n3)) of the transformer T. And the anode of the diode D1 may be connected to the capacitor C2 and the reactor L1.

  Smoothing capacitors Co are connected to both ends of a series circuit of the secondary winding 5b of the transformer T and the diode Do. The voltage across the smoothing capacitor Co is taken out as an output voltage, and the control circuit 100 performs on / off control of the main switch Q11 so that the output voltage becomes a predetermined voltage.

  Next, the operation of the conventional DC power supply device shown in FIG. 9 will be described with reference to the timing chart of FIG. In FIG. 10, Vq1 indicates the voltage between the drain and source of the main switch Q1, and Iq1 indicates the current flowing through the main switch Q1.

First, at time _{t 2, the} the main switch Q1 is turned on, C1 → 5c → 5a → Q1 → C1 and a current flows. Further, when the anode voltage of the diode D1 is reduced by the winding ratio (n1: n3) between the primary winding 5a and the tertiary winding 5c, and the reduced anode voltage of the diode D1 is lower than the input voltage, B1 → L1 → D1 → 5a → Q1 → B1 and current Iq1 flow. That is, since the current flows through the reactor L1, energy is stored in the reactor L1. The current flowing through the reactor L1 increases with a slope, and this peak value changes according to the amplitude of the rectified voltage (corresponding to the input voltage Vi) of the full-wave rectifier circuit B1.

  Also, energy is stored in the transformer T. Since a downward voltage is generated in the secondary winding 5b, no current flows through the diode Do. At the same time, current flows in the order of B1, L1, D1, 5c, C1, and B1. That is, the capacitor C1 is charged.

Then, at time t _3, when the main switch Q1 is turned off, the diode Do is turned on capacitor C2 discharges, the energy stored in the transformer T is supplied to the load Ro through the diode Do. Further, the energy stored in the reactor L1 is discharged through the capacitor C1 and the diode D1, supplies energy to the load Ro on the secondary side of the transformer T, and charges the capacitor C1.

Accordingly, when the main switch Q1 is turned off, that is, when the voltage Vq1 of the main switch Q1 rises and the capacitor C2 is charged, the main switch Q1 performs a soft switching operation, and the voltage Vq1 of the main switch Q1 is The slope of the voltage is determined by the size of the capacitor C2. Note that a capacitor of 1000 pF to several 1000 pF is used as the capacitor C2.
Japanese Patent No. 3127979 (FIG. 5)

  However, in an actual circuit, when a current flows into the taps of the primary winding 5a and the tertiary winding 5c of the transformer T, if there is a leakage inductance in the tap of the transformer T, the leakage inductance vibrates. Due to this vibration, a surge voltage is generated in the main switch Q1, so that the voltage Vq1 of the main switch Q1 dampens. For this reason, since loss and noise occur in the main switch Q1, the efficiency decreases. Therefore, although it is desired to reduce the leakage inductance as much as possible, it has been difficult to reduce it with an actual transformer.

  An object of the present invention is to provide a DC power supply device that can achieve low noise and high efficiency by reducing a surge voltage of a main switch.

  The present invention has the following configuration in order to solve the above problems. The invention of claim 1 is a DC power supply device that inputs AC, improves the power factor and outputs DC, and is connected to the AC power source to rectify the AC voltage, and the negative side of the rectifier circuit A main switch having one end connected to the output end and a first series circuit in which the primary winding of the transformer is connected in series, and one end connected to the negative output side of the rectifier circuit, A power supply capacitor connected in parallel, and connected between a positive output side of the rectifier circuit and the other end of the power supply capacitor, a first reactor, a tertiary winding of the transformer and a diode are connected in series. A second series circuit connected; a capacitor connected between a connection point between the main switch and the primary winding of the transformer; and a connection point between the tertiary winding of the transformer and the diode; Connected to the secondary winding of the transformer Characterized a rectifying smoothing circuit including a rectifying element and a smoothing element, that a control circuit for controlling the output voltage from the rectifying smoothing circuit to a predetermined voltage by turning on / off control of the main switch.

  According to a second aspect of the present invention, in the DC power supply device according to the first aspect, the transformer further includes a quaternary winding and is connected in parallel to the main switch, and the quaternary winding of the transformer, the second reactor, and the backflow A third series circuit in which a prevention diode and an auxiliary switch are connected in series; a resonance capacitor and a resonance diode connected in parallel to the main switch; and the control circuit is configured to turn on the main switch. The main switch is zero-voltage switched at turn-off.

  According to a third aspect of the present invention, in the DC power supply device according to the second aspect, the control circuit turns on the auxiliary switch before turning on the main switch.

  According to a fourth aspect of the present invention, in the DC power supply device according to the first or second aspect, the second reactor includes a leakage inductance of the transformer.

  According to a fifth aspect of the present invention, in the DC power supply device according to any one of the first to fourth aspects, when the AC power supply is turned on and connected between the rectifier circuit and the power supply capacitor. An inrush current limiting resistor for reducing an inrush current of the power supply capacitor; the main switch is a normally-on type switch; and the control circuit is configured to detect the inrush current limiting resistor when the AC power source is turned on. The main switch is turned off by the voltage generated at the time, and after the power supply capacitor is charged, a switching operation for turning on / off the main switch is started.

  According to a sixth aspect of the present invention, in the DC power supply device according to the fifth aspect, the transformer further includes an auxiliary winding, and a normal operation power supply unit that supplies a voltage generated in the auxiliary winding of the transformer to the control circuit. It is characterized by that.

  A seventh aspect of the present invention is the DC power supply device according to the fifth or sixth aspect, further comprising a semiconductor switch connected in parallel to the inrush current limiting resistor, wherein the control circuit performs a switching operation of the main switch. After the start, the semiconductor switch is turned on.

  According to the present invention, since the third winding of the transformer is separated and independent from the primary winding of the transformer without being connected in series, the surge current when the main switch is turned off is 3 It discharges through a capacitor, a diode, and a power supply capacitor without passing through the next winding. For this reason, since it is not affected by the leakage inductance of the transformer, low noise and high efficiency can be achieved by reducing the surge voltage of the main switch.

  Embodiments of a DC power supply apparatus according to the present invention will be described below in detail with reference to the drawings.

  The DC power supply device according to the embodiment is a circuit in which a leakage inductance is not affected without using a transformer tap. That is, by using another tertiary winding 5c on the same transformer T and winding it separately, a circuit unrelated to the apparent leakage inductance of the transformer is obtained.

  FIG. 1 is a circuit configuration diagram of the DC power supply device according to the first embodiment. In FIG. 1, a full-wave rectification circuit B1 is provided which is connected to an AC power supply Vac1 and rectifies an AC voltage. A series circuit of a main switch Q1 composed of an FET having one end connected to the negative output terminal P2 of the full-wave rectifier circuit B1 and a primary winding 5a (number of turns n1) of a transformer Ta is provided. A diode Dq1 is connected to the main switch Q1 in parallel. This diode Dq1 may be a parasitic capacitance of the main switch Q1. One end of the capacitor C1 is connected to the negative output terminal P2 of the full-wave rectifier circuit B1, and is connected in parallel to the series circuit.

  A first reactor L1, a tertiary winding 5c of a transformer Ta, and a diode D1 are connected in series between the positive output terminal P1 of the full-wave rectifier circuit B1 and the other end of the capacitor C1. A capacitor C2 is connected between a connection point between the main switch Q1 and the primary winding 5a of the transformer Ta and a connection point between the tertiary winding 5c of the transformer Ta and the diode D1.

  Smoothing capacitors Co are connected to both ends of the series circuit of the secondary winding 5b of the transformer Ta and the diode Do. The voltage across the smoothing capacitor Co is taken out as an output voltage, and the control circuit 10 performs on / off control of the main switch Q1 so that the output voltage becomes a predetermined voltage.

Next, the operation of the DC power supply device according to the first embodiment shown in FIG. 1 will be described with reference to the timing chart of FIG. In FIG. 2, Vq1 is a drain-source voltage of the main switch Q1, Iq1 is a current flowing through the main switch Q1, Ido is a current flowing through the diode Do, I _L1 is a current flowing through the reactor L1, and I _C2 flows through the capacitor C2. Current is shown.

First, in the period T4, when the main switch Q1 is turned on, a current Iq1 flows through the main switch Q1 as C1 → 5a → Q1 → C1. For this reason, energy is stored in the transformer Ta. Further, the diode D1 is turned off, and the current _IL1 flows from B1 → L1 → 5c → C2 → Q1 → B1, the energy is stored in the reactor L1, and the current _IC2 flows in the capacitor C2. After discharging, the capacitor C2 is charged such that the end of the diode D1 connected to the anode has a positive electrode.

Next, during the period T1, when the main switch Q1 is in the on state, the capacitor C2 finishes charging and the diode D1 is turned on. Then, B1, L1, 5c, D1, 5a, Q1, B1, current Iq1, and current _IL1 flow and increase. The current flowing through the reactor L1 increases with a slope, and this peak value changes according to the amplitude of the rectified voltage (corresponding to the input voltage Vi) of the full-wave rectifier circuit B1. For this reason, as shown in FIG. 3, since the input current Ii of the commercial AC power supply changes according to the input voltage Vi of the commercial AC power supply, the power factor is improved. With respect to the input voltage Vi, when the voltage subtracted by the voltage of the tertiary winding 5c of the transformer Ta is lower than the input voltage Vi, it flows through the reactor L1.

  Next, when the main switch Q1 is turned off in the period T2, the capacitor C2 is discharged and charged with the energy of the transformer Ta so that the connection end side to the main switch Q1 becomes a positive electrode, so the voltage Vq1 of the main switch Q1 Will rise.

Next, when charging of the capacitor C2 is completed in the period T3, the energy of the transformer Ta and the reactor L1 is released through the diode D1 and the capacitor C1. For this reason, the current _IL1 decreases. Further, since an upward voltage is generated in the secondary winding 5b, the diode Do is turned on, the current Ido flows, and power is supplied to the load Ro.

  In the conventional DC power supply device shown in FIG. 9, the surge current when the main switch Q1 is turned off is discharged through the path C2-> D1-> 5c-> C1-> Dq1-> C2.

  On the other hand, in the DC power supply device of the first embodiment, the surge current when the main switch Q1 is turned off is a path C2-> D1-> C1-> Dq1-> C2 without passing through the tertiary winding 5c of the transformer Ta. Discharge at. For this reason, since it is not influenced by the leakage inductance of the transformer Ta, the surge voltage of the main switch Q1 can be reliably absorbed. Therefore, low noise and high efficiency can be achieved by reducing the surge voltage of the main switch Q1.

  In the conventional DC power supply device, as shown in FIG. 10, when the main switch Q1 is turned off due to the leakage inductance of the transformer T, a surge voltage (damped oscillation voltage) is generated in the voltage Vq1 of the main switch Q1. In the DC power supply device of Example 1, as shown in FIG. 2, the surge voltage of the voltage Vq1 of the main switch Q1 is sufficiently suppressed.

  Next, a DC power supply device according to Embodiment 2 will be described. FIG. 4 is a circuit configuration diagram illustrating the DC power supply device according to the second embodiment. The DC power supply device according to the second embodiment shown in FIG. 4 has the configuration of the DC power supply device according to the first embodiment shown in FIG. 1, and further performs zero voltage switching (ZVS) operation for turning on and turning off the main switch Q1. Thus, the switching loss and switching noise of the main switch Q1 are reduced.

  4 that are the same as those shown in FIG. 1 are given the same reference numerals, and detailed descriptions thereof are omitted. Only the newly added components will be described here.

  In FIG. 4, the transformer Tb includes a primary winding 5a, a secondary winding 5b, a tertiary winding 5c, and a quaternary winding 5d (number of turns n4). A series circuit of a quaternary winding 5d of the transformer Tb, a second reactor L2, a backflow prevention diode D2, and an auxiliary switch Q2 is connected in parallel to the main switch Q1. The second reactor L2 may be a leakage inductance of the transformer Tb, or may be an inductance different from the leakage inductance.

  A resonance capacitor Cq1 and a resonance diode Dq1 are connected in parallel to the main switch Q1. The resonance capacitor Cq1 and the resonance diode Dq1 may be a parasitic capacitance and a parasitic diode of the main switch Q1.

  As the main switch Q1 and the auxiliary switch Q2, any of bipolar transistors, FETs, and IGBTs can be used.

  The control circuit 10a turns on the auxiliary switch Q2 before turning on the main switch Q1. The control circuit 10a performs zero voltage switching of the main switch Q1 when the main switch Q1 is turned on and off, and stabilizes the output voltage from the smoothing capacitor Co to a predetermined voltage.

Next, the operation of the DC power supply device according to the second embodiment configured as described above will be described with reference to the timing chart of FIG. In FIG. 5, Vg1 is applied from the control circuit 10a to the control terminal of the main switch Q1 (for example, the gate of the FET) to turn on / off the main switch Q1, and Vg2 controls the auxiliary switch Q2 from the control circuit 10a. A Q2 control signal applied to a terminal (for example, the gate of the FET) to turn on / off the auxiliary switch Q2, Vq1 is a voltage between the drain and source of the main switch Q1, Iq1 is a current flowing through the main switch Q1, and Vq2 is an auxiliary switch The drain-source voltage of Q2, Iq2 is a current flowing through the auxiliary switch Q2, It is a current flowing through the transformer Tb, _IL1 is a current flowing through the reactor L1, and Ido is a current flowing through the diode Do.

First, during the period T1, when the main switch Q1 and the auxiliary switch Q2 are in the on state, the capacitor C2 finishes charging and the diode D1 is turned on. Then, B1 → L1 → 5c → D1 → 5a → Q1 → B1 and current Iq1 and current _IL1 flow and increase. For this reason, energy is stored in the transformer Tb, and energy is stored in the reactor L1 by the current flowing from the AC power supply Vac1.

  Next, when the main switch Q1 and the auxiliary switch Q2 are turned off in the period T2, the voltage Vq1 of the main switch Q1 increases while the resonance capacitor Cq1 and the capacitor C2 are charged by the energy of the transformer Tb and the reactor L1. .

When charging of the capacitor C2 and the resonance capacitor Cq1 is completed in the period T3, the energy of the transformer Tb and the reactor L1 is released through the diode D1 and the capacitor C1. For this reason, the current _IL1 decreases. Further, since an upward voltage is generated in the secondary winding 5b, the diode Do is turned on, the current Ido flows, and power is supplied to the load Ro. In period T4, the previously eliminated current _{I L1} of the reactor L1, becomes only the current Ido of the diode Do.

  In period T5, when auxiliary switch Q2 is turned on, current Iq2 flows through quaternary winding 5d of transformer Tb, reactor L2, and diode D2, and voltage Vq1 of main switch Q1 drops to zero.

  In the period T6, when the voltage Vq1 of the main switch Q1 becomes zero and the main switch Q1 is turned on, the main switch Q1 can be operated in ZVS. Then, the current Iq2 of the auxiliary switch Q2 decreases and falls to zero, and the capacitor C2 is charged so that the end of the diode D1 connected to the anode is positive after discharging. The current Iq1 of the main switch Q1 flows from a negative direction to a positive direction. In the next period T1, the capacitor C2 finishes charging and the current becomes zero, the main switch Q1 is turned on, and returns to the original state.

  As described above, according to the second embodiment, the effects of the first embodiment can be obtained, and the ZVS operation can be turned on / off regardless of whether the main switch Q1 is turned on or off. A DC power supply device can be provided.

  Next, a DC power supply device according to Embodiment 3 will be described. In the DC power supply devices according to Example 1 and Example 2, a normally-off type FET or the like was used as a switch. This normally-off type switch is a switch that is turned off when the power is turned off.

  On the other hand, normally-on type switches such as SIT (static induction transistor) are switches that are turned on when the power is turned off. This normally-on type switch has a high switching speed, a low on-resistance, and is an ideal element when used in a power conversion device such as a switching power supply, and can be expected to reduce switching loss and achieve high efficiency.

  However, in the normally-on type switching element, when the power is turned on, the switch is in an on state, so that the switch is short-circuited. For this reason, normally-on type switches cannot be activated and cannot be used for anything other than special purposes.

  Therefore, the direct current power supply device according to the third embodiment has the configuration of the direct current power supply device according to the first embodiment and uses a normally-on type switch for the main switch Q1. The voltage due to the voltage drop of the inrush current limiting resistor inserted for the purpose of reducing the voltage is used as the reverse bias voltage of the normally-on type switch, and a configuration for eliminating the problem at the time of power-on is added.

  FIG. 6 is a circuit configuration diagram illustrating a DC power supply device according to a third embodiment. The DC power supply device shown in FIG. 6 has the configuration of the DC power supply device according to the first embodiment shown in FIG. 1, and the main switch Q1n is a normally-on type switch such as SIT, and the main switch Q1n is on / off controlled. And a normally-on circuit.

  This normally-on circuit is configured as follows. An inrush current limiting resistor R1 is connected between the negative output terminal P2 of the full-wave rectifier circuit B1 and the connection point between the main switch Q1n and the capacitor C1. The main switch Q1n is a normally-on type switch such as SIT, and is turned on / off by PWM control of the control circuit 11.

  A switch S1 is connected to both ends of the inrush current limiting resistor R1. The switch S1 is a semiconductor switch such as a normally-off type FET or BJT (bipolar junction transistor), and is ON-controlled by a short circuit signal from the control circuit 11.

  A starting power supply unit 12 including a capacitor C12, a resistor R2, and a diode D12 is connected to both ends of the inrush current limiting resistor R1. This starting power supply unit 12 takes out the voltage generated at both ends of the inrush current limiting resistor R1, and outputs the voltage across the capacitor C12 to the control circuit 11 in order to use it as a reverse bias voltage to the gate of the main switch Q1n. Further, the charging voltage charged in the capacitor C <b> 1 is supplied to the control circuit 11.

  When the AC power supply Vac1 is turned on, the control circuit 11 is activated by the voltage supplied from the capacitor C12, outputs a reverse bias voltage from the terminal b to the gate of the main switch Q1n as a control signal, and turns off the main switch Q1n. . This control signal is composed of, for example, a pulse signal of −15V and 0V, the main switch Q1n is turned off by a voltage of −15V, and the main switch Q1n is turned on by a voltage of 0V.

  After the charging of the capacitor C1 is completed, the control circuit 11 outputs a pulse signal of 0V and −15V as a control signal from the terminal b to the gate of the main switch Q1n, and switches the main switch Q1n. The control circuit 11 causes the main switch Q1n to perform a switching operation, and then outputs a short circuit signal to the gate of the switch S1 after a predetermined time has elapsed, thereby turning on the switch S1.

  One end of the auxiliary winding 5e (number of turns n5) provided in the transformer Tc is connected to one end of the main switch Q1n, one end of the capacitor C13, and the control circuit 11, and the other end of the auxiliary winding 5e is a diode D13. The anode of the diode D13 is connected to the other end of the capacitor C13 and the terminal c of the control circuit 11. The auxiliary winding 5e, the diode D13, and the capacitor C13 constitute a normal operation power supply unit 13. The normal operation power supply unit 13 transfers the voltage generated in the auxiliary winding 5e to the control circuit 11 via the diode D13 and the capacitor C13. Supply.

  Next, the operation of the DC power supply device according to the third embodiment configured as described above will be described with reference to FIGS.

  In FIG. 8, Vac1 indicates the AC voltage of the AC power supply Vac1, the input current indicates the current flowing through the AC power supply Vac1, the R1 voltage indicates the voltage generated in the inrush current limiting resistor R1, and the C1 voltage is , The voltage of the capacitor C1, the voltage C12 indicates the voltage of the capacitor C12, the output voltage indicates the voltage of the capacitor Co, and the control signal is output from the terminal b of the control circuit 11 to the gate of the main switch Q1n. Signals are shown.

First, at time _{t 0,} applying the AC power Vac1 (ON), the AC voltage of the AC power source Vac1 is full-wave rectified by the full-wave rectifier circuit B1. At this time, the normally-on type main switch Q1n is in the on state, and the switch S1 is in the off state. For this reason, the voltage from the full-wave rectifier circuit B1 is applied to the inrush current limiting resistor R1 via the capacitor C1 ((1) in FIG. 7).

  The voltage generated in the inrush current limiting resistor R1 is stored in the capacitor C12 via the diode D12 and the resistor R2 ((2) in FIG. 7). Here, the terminal f side of the capacitor C12 is, for example, zero potential, and the terminal g side of the capacitor C12 is, for example, negative potential. For this reason, the voltage of the capacitor C12 becomes a negative voltage (reverse bias voltage) as shown in FIG. The negative voltage of the capacitor C12 is supplied to the control circuit 11 via the terminal a.

When the voltage of the capacitor C12 reaches the threshold voltage THL of the main switch Q1n (time t _{1 in} FIG. 8), the control circuit 11 sends a control signal of −15V from the terminal b to the gate of the main switch Q1n. ((3) in FIG. 7). For this reason, the main switch Q1n is turned off.

  Then, the capacitor C1 is charged by the voltage from the full-wave rectifier circuit B1 ((4) in FIG. 7), the voltage of the capacitor C1 rises, and the charging of the capacitor C1 is completed.

Then, at time _{t 2, the} control circuit 11 starts the switching operation. First, a control signal of 0V is output from the terminal b to the gate of the main switch Q1n ((5) in FIG. 7). Therefore, since the main switch Q1n is turned on, a current flows through C1 → 5a → Q1n → C1 ((6) in FIG. 7). For this reason, energy is stored in the primary winding 5a of the transformer Tc.

  A voltage is also generated in the auxiliary winding 5e electromagnetically coupled to the primary winding 5a of the transformer Tc, and the generated voltage is supplied to the control circuit 11 via the diode D13 and the capacitor C13 (FIG. 7). (7) in the middle. For this reason, since the control circuit 11 can continue the operation, the switching operation of the main switch Q1n can be continued.

Then, at time _{t 3,} and outputs from the terminal b of the control signal of -15V to the gate of the main switch Q1n. Therefore, the main switch Q1n is turned off at time t _3, and the counter electromotive force generated in the primary winding 5a, a current to the load Ro and the capacitor Co via the secondary winding 5b diode Do flow, An output voltage is generated at the load Ro. Further, when the output from the control circuit 11 at time t ₃ the short signal to the switch S1, the switch S1 is turned on (in FIG. 7 (8)), both ends of the inrush current limiting resistor R1 is short-circuited. For this reason, the loss of the inrush current limiting resistor R1 can be reduced.

The time _{t 3} is about when the turning on the AC power Vac1 is set as the elapsed time from (time _{t 0),} for example, the time constant of the capacitor C1 and the inrush current limiting resistor R1 (τ = C1 · R1) 5 It is set to a time more than double. Thereafter, the main switch Q1n repeats the switching operation by on / off. After the main switch Q1n starts the switching operation, the main switch Q1n is similar to the operation of the switch Q1 of the DC power supply device according to the first embodiment shown in FIG. 1, that is, the operation according to the timing chart shown in FIG. Operate.

  Thus, according to the DC power supply device according to the third embodiment, the control circuit 11 turns off the main switch Q1n by the voltage generated in the inrush current limiting resistor R1 when the AC power supply Vac1 is turned on, and the capacitor C1 is charged. After that, since the switching operation for turning on / off the main switch Q1n is started, there is no problem when the power is turned on. Therefore, a normally-on type semiconductor switch can be used, and a low-loss, that is, high-efficiency DC power supply device can be provided. Moreover, the effect of Example 1 is acquired.

  The present invention is not limited to the first to third embodiments. For example, a normally-on circuit provided in the DC power supply device according to the third embodiment shown in FIG. 6 may be added to the DC power supply device according to the second embodiment shown in FIG. The normally-on circuit includes an inrush current limiting resistor R1, a switch S1, a startup power supply unit 12, a control circuit 11, and a normal operation power supply unit 13, and uses a normally-on type main switch Q1n.

  The DC power supply device of the present invention can be applied to an AC-DC conversion type power supply circuit.

1 is a circuit configuration diagram illustrating a DC power supply device according to Embodiment 1. FIG. 3 is a signal timing chart in each part of the DC power supply device according to the first embodiment. It is a figure which shows the waveform of the input voltage and input current of the DC power supply device which concern on Example 1. FIG. 6 is a circuit configuration diagram showing a DC power supply device according to Embodiment 2. FIG. 6 is a signal timing chart in each part of the DC power supply device according to the second embodiment. FIG. 6 is a circuit configuration diagram illustrating a DC power supply device according to a third embodiment. FIG. 10 is a diagram for explaining an operation of the DC power supply device according to the third embodiment. 10 is a signal timing chart in each part of the DC power supply device according to the third embodiment. It is a circuit block diagram which shows the conventional DC power supply device. It is a timing chart of the signal in each part of the conventional direct-current power supply device.

Explanation of symbols

Vac1 AC power supply B1 Full-wave rectifier circuit 10, 10a, 11, 100 Control circuit Q1, Q1n Main switch Q2 Auxiliary switch Ro Load
R1, R2 Resistors L1, L2 Reactor Co, C1, C2, C12, C13 Capacitor S1 Switch T, Ta, Tb, Tc Transformer 5a Primary winding (n1)
5b Secondary winding (n2)
5c Tertiary winding (n3)
5d quaternary winding (n4)
5e Auxiliary winding (n5)
12 Start-up power supply unit 13 Normal operation power supply unit Do, D1, D2, Dq1, D12, D13 Diode

Claims (7)

A DC power supply that inputs AC, improves the power factor and outputs DC,
A rectifier circuit that rectifies the AC voltage by connecting to an AC power source;
A first series circuit in which a main switch having one end connected to the negative output side of the rectifier circuit and a primary winding of a transformer are connected in series;
One end is connected to the negative output side of the rectifier circuit, and the power supply capacitor is connected in parallel to the first series circuit;
A second series circuit connected between a positive output terminal of the rectifier circuit and the other end of the power supply capacitor, and a first reactor, a tertiary winding of the transformer and a diode connected in series;
A capacitor connected between a connection point between the main switch and the primary winding of the transformer and a connection point between the tertiary winding of the transformer and the diode;
A rectifying / smoothing circuit connected to the secondary winding of the transformer and having a rectifying element and a smoothing element;
A control circuit for controlling the output voltage from the rectifying / smoothing circuit to a predetermined voltage by controlling on / off of the main switch;
A direct current power supply device comprising: The transformer further includes a quaternary winding,
A third series circuit connected in parallel to the main switch, in which a quaternary winding of the transformer, a second reactor, a backflow prevention diode, and an auxiliary switch are connected in series;
A resonance capacitor and a resonance diode connected in parallel to the main switch;
2. The DC power supply device according to claim 1, wherein the control circuit performs zero voltage switching of the main switch when the main switch is turned on and off.   3. The DC power supply device according to claim 2, wherein the control circuit turns on the auxiliary switch before turning on the main switch. 4. The DC power supply device according to claim 2, wherein the second reactor includes a leakage inductance of the transformer. 5. An inrush current limiting resistor connected between the rectifier circuit and the power supply capacitor to reduce the inrush current of the power supply capacitor when the AC power supply is turned on;
The main switch is a normally-on type switch,
The control circuit switches off the main switch by a voltage generated in the inrush current limiting resistor when the AC power source is turned on, and turns on / off the main switch after the power supply capacitor is charged. The DC power supply device according to any one of claims 1 to 4, wherein an operation is started. 6. The DC power supply device according to claim 5, wherein the transformer further includes an auxiliary winding, and further includes a normal operation power supply unit that supplies a voltage generated in the auxiliary winding of the transformer to the control circuit. Having a semiconductor switch connected in parallel to the inrush current limiting resistor;
The DC power supply device according to claim 5 or 6, wherein the control circuit turns on the semiconductor switch after starting the switching operation of the main switch.

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