Power supply device

Abstract

The present invention provides a power supply capable of generating a control voltage without requiring additional auxiliary windings. [Solution] A power supply device comprising a transformer section 4 including a primary winding, a secondary winding and an auxiliary winding N3; a primary-side circuit connected to the primary winding; a control unit (first control unit 7 and second control unit 8) that controls the primary-side circuit; a secondary-side circuit connected to the secondary winding; and a voltage supply circuit 10 connected to the auxiliary winding N3 that supplies a control voltage to the control unit, wherein the voltage supply circuit 10 comprises a first charge storage unit that stores charge in a first capacitor C11 via a first path using the voltage of the auxiliary winding N3; and a second charge storage unit that stores the charge of the first capacitor C11 in a second capacitor C12 via a second path and supplies the terminal voltage of the second capacitor C12 as a control voltage.

Description

Technical Field

[0001] The present invention relates to a power supply device.

Background Art

[0002] As a power supply device, a switching power supply device including a transformer section, an active filter circuit and a DC / DC converter circuit provided on the primary winding side of the transformer section, and a control section for controlling these circuits is known (see, for example, Patent Documents 1 and 2). In this switching power supply device, a control voltage (DC power supply voltage) of the control section is generated based on the induced voltage of the auxiliary winding of the transformer section.

[0003] In the above switching power supply device, in order to generate a control voltage, a configuration in which the auxiliary winding is wound up (a configuration in which two auxiliary windings are connected in series) is adopted. For this reason, in the above switching power supply device, a process of winding up the auxiliary winding is required, and problems such as an increase in the number of man-hours in the manufacturing process of the transformer section and the need for pins for winding the auxiliary windings cause a cost increase.

[0004] In the above switching power supply device, since a coupling capacitance is added by adding an auxiliary winding (winding up the auxiliary winding), it may affect the coupling of other windings of the transformer section. In that case, adjustments such as increasing or decreasing the windings are required. In addition, by adding an auxiliary winding, it is necessary to ensure an insulation distance between the added auxiliary winding and the secondary winding, which causes a problem that the structure of the transformer section becomes complicated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] The present invention has been made in view of the above circumstances, and its objective is to provide a power supply device capable of generating a control voltage without requiring additional auxiliary windings. [Means for solving the problem]

[0007] To solve the above problems, the power supply device according to the present invention is A transformer section including a primary winding, a secondary winding, and an auxiliary winding, The primary side circuit connected to the primary winding, A control unit that controls the primary side circuit, The secondary side circuit connected to the aforementioned secondary winding, A voltage supply circuit connected to the auxiliary winding to supply a control voltage to the control unit, A power supply device comprising, The aforementioned voltage supply circuit is A first charge storage unit includes a first capacitor and stores charge in the first capacitor via a first path using the voltage of the auxiliary winding, The device is characterized by comprising a second charge storage unit which includes a second capacitor, stores the charge of the first capacitor in the second capacitor via a second path, and supplies the terminal voltage of the second capacitor as the control voltage.

[0008] With this configuration, the voltage supply circuit can generate the control voltage using the first and second charge storage units, thus eliminating the need for additional auxiliary windings in the transformer section.

[0009] In the aforementioned power supply device, The aforementioned voltage supply circuit is A series circuit of a first diode and an inductor provided on the first path, The system can be configured to include a second diode provided on the second path.

[0010] In the aforementioned power supply device, The voltage supply circuit may be configured to include: a rectifying and smoothing unit that rectifies and smoothes the induced voltage of the auxiliary winding to generate a first voltage; a constant voltage conversion unit that converts the terminal voltage of the second capacitor into a constant voltage to generate a second voltage; an output unit that supplies the higher one of the voltage values of the first voltage and the second voltage to the control unit as the control voltage.

[0011] In the power supply device, the primary side circuit includes: an active filter circuit including a first switching element; a DC / DC converter circuit connected to the output side of the active filter circuit and including a second switching element. The control unit includes: an active filter control unit that controls the first switching element; a DC / DC converter control unit that controls the second switching element. The voltage supply circuit may be configured to supply the control voltage to the active filter control unit and the DC / DC converter control unit.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a power supply device capable of generating a control voltage without requiring an additional auxiliary winding.

Brief Description of the Drawings

[0013] [Figure 1] FIG. is a circuit diagram of a power supply device according to the present invention. [Figure 2] FIG. is a circuit diagram of a voltage supply circuit of a power supply device according to the present invention.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of a power supply device according to the present invention will be described with reference to the accompanying drawings.

[0015] Figure 1 shows a power supply device 1 according to an embodiment of the present invention. The power supply device 1 includes an active filter circuit 2, a DC / DC converter circuit 3, a transformer section 4, a rectifying and smoothing circuit 5, a detection circuit 6, a first control section 7, a second control section 8, a feedback circuit 9, a voltage supply circuit 10, input terminals T1 and T2, and output terminals T3 and T4.

[0016] In the power supply device , the active filter circuit 2 and the DC / DC converter circuit 3 correspond to the "primary side circuit" of the present invention, the rectifying and smoothing circuit 5 and the detection circuit 6 correspond to the "secondary side circuit" of the present invention, and the first control section 7 and the second control section 8 correspond to the "control section" of the present invention.

[0017] A rectifying section (not shown) is provided in front of the input terminals T1 and T2. The rectifying section rectifies the input AC voltage and outputs it to the input terminals T1 and T2. The rectifying section includes, for example, a diode bridge circuit.

[0018] The active filter circuit 2 includes a reactor such as a choke coil and a switching element (corresponding to the "first switching element" of the present invention). The active filter circuit 2 can improve the power factor by shaping the voltage output from the rectifying section into a sine wave.

[0019] The DC / DC converter circuit includes a capacitor C , a switching element Q (corresponding to the "second switching element" of the present invention), and resistors R to R . The capacitor C is connected between the output terminals of the active filter circuit 2. The switching element Q is an N-channel MOSFET in this embodiment. The gate of the switching element Q is connected to the second control section 8 via the resistor R . A resistor R is connected between the gate and source of the switching element Q . The drain of the switching element Q is connected to the high-potential side terminal of the capacitor C via a primary winding N described later, and the source of the switching element Q is connected to the low-potential side terminal of the capacitor C via the resistor R .

[0020] The transformer section 4 comprises a primary winding N1, a secondary winding N2, and a single auxiliary winding N3. One end of the primary winding N1 is connected to the high-potential terminal of capacitor C1, and the other end of the primary winding N1 is connected to the drain of switching element Q1. The secondary winding N2 is connected to the rectifier and smoothing circuit 5, and the single auxiliary winding N3 is connected to the voltage supply circuit 10.

[0021] The rectifier-smoothing circuit 5 comprises diodes D1 and D2 connected in parallel, and a capacitor C2. The anodes of diodes D1 and D2 are connected to one end of the secondary winding N2, and the cathodes of diodes D1 and D2 are connected to the high-potential terminal of capacitor C2. The low-potential terminal of capacitor C2 is connected to the other end of the secondary winding N2.

[0022] The detection circuit 6 includes a voltage detection circuit that detects the DC output voltage output from output terminals T3 and T4. The voltage detection circuit is composed of, for example, at least two resistors connected in series between output terminals T3 and T4. The detection circuit 6 outputs a signal (feedback signal) regarding the magnitude of the output voltage (feedback signal) to the second control unit 8 via the feedback circuit 9.

[0023] The first control unit 7 is an active filter control unit that controls the active filter circuit 2, and switches the switching elements of the active filter circuit 2 on and off. The first control unit 7 may be composed of digital circuits such as a microprocessor or a digital signal processor, or it may be composed of analog circuits, or it may be composed of a circuit that combines digital and analog circuits.

[0024] The second control unit 8 is a DC / DC converter control unit that controls the DC / DC converter circuit 3, and switches the switching element Q1 of the DC / DC converter circuit 3 on and off. The second control unit 8, like the first control unit 7, is composed of digital and / or analog circuits. A feedback signal is input to the second control unit 8 from the feedback circuit 9. The second control unit 8 performs constant voltage control to keep the output voltage constant based on the feedback signal, for example.

[0025] The feedback circuit 9 includes at least one photocoupler. The light-emitting part of the photocoupler (e.g., an LED) may be included in the detection circuit 6, and the light-receiving part of the photocoupler (e.g., a phototransistor) may be included in the second control unit 8.

[0026] The voltage supply circuit 10 is connected to a single auxiliary winding N3 and generates control voltages (DC power supply voltages) for the first control unit 7 and the second control unit 8 based on the voltage of the auxiliary winding N3. As shown in Figure 2, the voltage supply circuit 10 includes a rectifier and smoothing unit 11, a charge storage unit 12, a voltage stabilization unit 13, and an output unit 14. The low-potential side of the voltage supply circuit 10 is connected to one end (black circle side) of the auxiliary winding N3 and the low-potential terminal of the capacitor C1.

[0027] The rectifier and smoothing section 11 comprises a capacitor C10 and a diode D10. The low-potential terminal of capacitor C10 is connected to one end of the auxiliary winding N3, and the high-potential terminal of capacitor C10 is connected to the cathode of diode D10. The anode of diode D10 is connected to the other end of the auxiliary winding N3.

[0028] The charge storage unit 12 includes a diode D11 (corresponding to the "first diode" of the present invention), an inductor L11, a capacitor C11 (corresponding to the "first capacitor" of the present invention), a diode D12 (corresponding to the "second diode" of the present invention), and a capacitor C12 (corresponding to the "second capacitor" of the present invention). The diode D11, inductor L11, and capacitor C11 constitute the "first charge storage unit" of the present invention, and the diode D12 and capacitor C12 constitute the "second charge storage unit" of the present invention.

[0029] The anode of diode D11 is connected to the low-potential terminal of capacitor C10 and one end of auxiliary winding N3. The cathode of diode D11 is connected to the anode of diode D10 and the other end of auxiliary winding N3 via inductor L11 and capacitor C11. Diode D11 and inductor L11 are connected in series.

[0030] The anode of diode D12 is connected to the connection point between inductor L11 and capacitor C11. The cathode of diode D12 is connected to the high-potential terminal of capacitor C12. The low-potential terminal of capacitor C12 is connected to the anode of diode D11 and the low-potential terminal of capacitor C10.

[0031] The voltage stabilization unit 13 comprises a Zener diode ZD, switching elements Q11 and Q12, resistors R11 to R13, capacitors C13 and C14, and a phototransistor PT. In this embodiment, switching element Q11 is an NPN transistor, and switching element Q12 is a PNP transistor. Switching element Q11, Zener diode ZD, resistor R11, and capacitor C13 constitute a series regulator. Switching element Q12, resistors R12 and R13, capacitor C14, and phototransistor PT constitute a stop circuit that stops the operation of the series regulator when in standby mode.

[0032] In the series regulator, the cathode of the Zener diode ZD is connected to the base of the switching element Q11. The collector of the switching element Q11 is connected to the high-potential terminal of the capacitor C12 of the charge storage unit 12, and the anode of the Zener diode ZD is connected to the low-potential terminal of the capacitor C12. A capacitor C13 is connected between the anode of the Zener diode ZD and the emitter of the switching element Q11. The cathode of the Zener diode ZD is also connected to the collector of the switching element Q11 via the current path of the resistor R11 and the switching element Q12.

[0033] In the stop circuit, the switching element Q12 is provided between the base and collector of the switching element Q11, and a parallel circuit of resistor R12 and capacitor C14 is connected between the base and emitter of the switching element Q12. The base of the switching element Q12 is connected to the low-potential terminal of capacitor C1 via the current path of resistor R13 and phototransistor PT. The phototransistor PT, together with an LED (not shown), constitutes a photocoupler. The phototransistor PT is on during normal operation, including startup, to turn on the switching element Q12, and off during standby to turn off the switching element Q12.

[0034] The output section 14 includes an OR circuit of diodes D13 and D14, and a capacitor C15. The anode of diode D13 is connected to the emitter of the switching element Q11 of the voltage stabilization section 13. The cathode of diode D13 is connected to the cathode of diode D14, and the anode of diode D14 is connected to the connection point between the high-potential terminal of capacitor C10 of the rectifier / smoothing section 11 and the cathode of diode D10. The high-potential terminal of capacitor C15 is connected to the connection point between the cathode of diode D13 and the cathode of diode D14, and the low-potential terminal of capacitor C15 is connected to the low-potential terminal of capacitor C1.

[0035] Next, the operation of the voltage supply circuit 10 during the startup of the power supply unit 1 will be described.

[0036] In power supply unit 1, when input voltages obtained by rectifying AC voltages in the rectifier section are supplied to input terminals T1 and T2, the power supply voltage is supplied to the second control unit 8 via a starting resistor (not shown), and the second control unit 8 starts up. The started second control unit 8 begins controlling the switching element Q1 of the DC / DC converter circuit 3 and generates an induced voltage in the auxiliary winding N3.

[0037] In the rectifier and smoothing section 11, the induced voltage of the auxiliary winding N3 is rectified and smoothed to generate the first voltage (the terminal voltage of capacitor C10). The terminal voltage of capacitor C10 is supplied to the output section 14 while gradually increasing.

[0038] In the charge storage unit 12, charge is stored in capacitor C11 via the first path of diode D11 → inductor L11 → capacitor C11 by utilizing the voltage at one end of the auxiliary winding N3 (voltage on the black circle side). The charge in capacitor C11 moves to capacitor C12 via the second path of diode D12 → capacitor C12, and charge is stored in capacitor C12. As a result, the terminal voltage of capacitor C12 at startup is higher than the terminal voltage of capacitor C10. The terminal voltage of capacitor C12 is supplied to the voltage stabilization unit 13 as a control voltage.

[0039] In the voltage stabilization unit 13, when the terminal voltage of capacitor C12 is less than the Zener voltage of Zener diode ZD, Zener diode ZD becomes non-conductive, and the output voltage of the voltage stabilization unit 13 increases in accordance with the rise in the terminal voltage of capacitor C12. When the terminal voltage of capacitor C12 becomes equal to or greater than the Zener voltage of Zener diode ZD, Zener diode ZD becomes conductive, and the output voltage of the voltage stabilization unit 13 is limited to a constant voltage (corresponding to the "second voltage" of this invention). The output voltage of the voltage stabilization unit 13 is supplied to the output unit 14.

[0040] In the output unit 14, the OR circuit of diodes D13 and D14 outputs the higher of the output voltage values ​​of the voltage stabilization unit 13 (second voltage) and the output voltage of the rectifier / smoothing unit 11 (first voltage) to the first control unit 7 and the second control unit 8 as the control voltage. At startup, the output voltage of the voltage stabilization unit 13 is higher than the output voltage of the rectifier / smoothing unit 11, so the output unit 14 outputs the output voltage of the voltage stabilization unit 13 as the control voltage. After a predetermined time has elapsed since startup, when the output voltage of the rectifier / smoothing unit 11 becomes higher than the output voltage of the voltage stabilization unit 13, the output unit 14 outputs the output voltage of the rectifier / smoothing unit 11 as the control voltage.

[0041] The first control unit 7 is activated by the control voltage and starts controlling the active filter circuit 2 after the operation of the DC / DC converter circuit 3 has stabilized.

[0042] As described above, in the power supply unit 1 at startup, the control voltage generated by the charge storage unit 12 is supplied to the first control unit 7 and the second control unit 8 via the voltage stabilization unit 13 and the output unit 14. Therefore, in the power supply unit 1 according to this embodiment, an additional auxiliary winding is not required in the transformer unit 4, and various problems caused by the additional auxiliary winding (see background art) can be avoided.

[0043] Although embodiments of the power supply device according to the present invention have been described above, the present invention is not limited to the above embodiments.

[0044] The power supply device according to the present invention comprises a transformer section including a primary winding, a secondary winding, and an auxiliary winding; a primary-side circuit connected to the primary winding; a control unit for controlling the primary-side circuit; a secondary-side circuit connected to the secondary winding; and a voltage supply circuit connected to the auxiliary winding for supplying a control voltage to the control unit. The voltage supply circuit includes a first charge storage unit that includes a first capacitor and stores charge in the first capacitor via a first path using the voltage of the auxiliary winding; and a second charge storage unit that includes a second capacitor and stores the charge of the first capacitor in the second capacitor via a second path, and supplies the terminal voltage of the second capacitor as a control voltage. The configuration can be modified as appropriate.

[0045] For example, the primary circuit of the present invention may be configured to include a switching circuit that includes at least one switching element. In this case, the control unit of the present invention can be configured to control the switching element.

[0046] In the charge storage unit 12 of the above embodiment, the arrangement of the diode D11 and the inductor L11 may be reversed, or other electronic components (e.g., resistors) may be provided on the first path and / or the second path. [Explanation of symbols]

[0047] 1 Power supply 2 Active filter circuit 3. Converter Circuit 4. Transformer section 5 Rectifier smoothing circuit 6. Detection circuit 7. First Control Unit 8. Second Control Unit 9. Feedback Circuit 10 Voltage supply circuit 11 Rectification and Smoothing Section 12 Charge storage section 13. Voltage stabilization section 14 Output section

Claims

1. A transformer section including a primary winding, a secondary winding, and an auxiliary winding, The primary side circuit connected to the primary winding, A control unit that controls the primary side circuit, The secondary side circuit connected to the aforementioned secondary winding, A voltage supply circuit connected to the auxiliary winding to supply a control voltage to the control unit, A power supply device comprising, The aforementioned voltage supply circuit is A first charge storage unit includes a first capacitor and stores charge in the first capacitor via a first path using the voltage of the auxiliary winding, The system includes a second capacitor, a second charge storage unit that stores the charge of the first capacitor in the second capacitor via a second path, and supplies the terminal voltage of the second capacitor as the control voltage. A power supply device characterized by the following features.

2. The aforementioned voltage supply circuit is A series circuit of a first diode and an inductor provided on the first path, A second diode provided on the second path, The power supply device according to feature 1.

3. The aforementioned voltage supply circuit is A rectifier and smoothing unit that rectifies and smooths the induced voltage of the auxiliary winding to generate a first voltage, A voltage stabilization unit that stabilizes the terminal voltage of the second capacitor to generate a second voltage, The system includes an output unit that supplies the higher of the first voltage and the second voltage values ​​to the control unit as the control voltage. The power supply device according to feature 1.

4. The primary side circuit is, An active filter circuit including a first switching element, The active filter circuit is connected to the output side and comprises a DC / DC converter circuit including a second switching element, The control unit, An active filter control unit that controls the first switching element, The system includes a DC / DC converter control unit that controls the second switching element, The voltage supply circuit supplies the control voltage to the active filter control unit and the DC / DC converter control unit. A power supply device according to any one of claims 1 to 3, characterized by the features described herein.

Images