JP2006238569A - Resonant power supply and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resonant power supply which can exhibit sufficient performance even if input power voltage fluctuates in a wide range, and its driving method. <P>SOLUTION: The resonant power supply, which is equipped with resonant circuits (Cr and N1) and switching means consisting of first to fourth switches (Q1-Q4), is equipped with an input voltage detecting circuit (40) which detects input power voltage (Vin) and outputs a detection signal (E), and control means (35 and 45) which control the ON/OFF of the switching means, according to the detection signal (E), thereby switching whether to operate the resonant power supply in full bridge or operate it in half bridge. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resonance type power supply apparatus, and more particularly to a full bridge resonance type power supply apparatus that can perform both a full bridge operation and a half bridge operation by switching, and a driving method thereof.

  As is well known in this technical field, the resonance type power supply device is classified into a full bridge resonance type power supply device and a half bridge resonance type power supply device. In general, when realizing a resonance type power supply device, a full bridge resonance type power supply device is often employed when the input power supply voltage is low. On the other hand, when the input power supply voltage is high, a half-bridge resonant power supply device is often employed to reduce the number of components. Specifically, a full bridge resonance type power supply device is employed when the AC voltage is 100V, and a half bridge resonance type power supply device is employed when the AC voltage is 240V. A full bridge resonance type power supply device is disclosed in, for example, Patent Document 1, and a half bridge resonance type power supply device is disclosed in, for example, Patent Document 2.

  FIG. 1 shows a full bridge resonance type power supply device, and FIG. 2 shows a half bridge resonance type power supply device.

  First, a full bridge resonance type power supply device will be described with reference to FIG. An AC voltage from an AC power supply (not shown) is full-wave rectified by a full-wave rectifier (not shown), and is smoothed by a smoothing capacitor (not shown) to obtain an input power supply voltage Vin. That is, a direct current power source is constituted by the full wave rectifier and the smoothing capacitor.

  The input power supply voltage Vin is supplied between the first and second input terminals 11 and 12. The first input terminal 11 is called a power input terminal, and the second input terminal 12 is called a ground terminal. Between the first and second input terminals 11 and 12, a first series circuit including the first and second switches Q1 and Q2 and a second series including the third and fourth switches Q3 and Q4 are provided. The circuit is connected. Each of the first to fourth switches Q1 to Q4 includes an N-channel insulated gate field effect transistor (FET). The first to fourth clamp diodes D1, D2, D3, and D4 are connected to the first to fourth switches Q1 to Q4 in reverse parallel. The first to fourth switches Q1 to Q4 are collectively referred to as switching means.

  Resonant with the primary winding N1 of the transformer T between the first connection point 21 of the first and second switches Q1, Q2 and the second connection point 22 of the third and fourth switches Q3, Q4. An LC series resonance circuit with the capacitor Cr is connected. The LC series resonance circuit is also simply called a resonance circuit. The transformer T has a secondary winding N2. The secondary winding N2 is connected to an output smoothing capacitor (not shown) via an output rectifier diode (not shown). That is, an output rectification smoothing circuit is constituted by the output rectification diode and the output smoothing capacitor. The output rectifying / smoothing circuit is also simply called an output circuit.

  A controller (not shown) is connected to the gates of the first to fourth switches Q1 to Q4. The controller controls on / off of the first to fourth switches Q1 to Q4.

  In the full bridge resonance type power supply circuit having such a configuration, the controller simultaneously turns on diagonally facing switches (for example, the first and third switches Q1 and Q3 or the second and fourth switches Q2 and Q4). In this way, a current is caused to flow through the resonance circuit. Therefore, both ends 21 and 22 of the resonance circuit are alternately connected to the power input terminal 11 and the ground terminal 12. As a result, the resonance circuit is driven with a voltage 2Vin that is twice the input power supply voltage Vin.

  Next, a half-bridge resonance type power supply device will be described with reference to FIG. The half-bridge resonant power supply apparatus has the same configuration as the full-bridge resonant power supply apparatus shown in FIG. 1 except that the third and fourth switches Q3 and Q4 in FIG. 1 are omitted. That is, the power input terminal 11 and the second connection point 22 are opened, and the second connection point 22 and the ground terminal 12 are short-circuited.

  In the half-bridge resonant power supply device having such a configuration, the controller drives the resonant circuit by controlling the first and second transistors Q1 and Q2 to be alternately turned on / off and off / on. Therefore, one end 21 of the resonance circuit is alternately connected to the power input terminal 11 and the ground terminal 12. As a result, the resonance circuit is driven by the input power supply voltage Vin.

  It is difficult for the resonance type power supply device having such a configuration to have a wide input voltage range. The reason is as follows. The resonance current flowing in the resonance circuit is determined by the input power supply voltage Vin and the impedance of the resonance circuit (resonance capacitor Cr, primary winding N1 of the transformer T). Therefore, the withstand voltage of the resonance capacitor Cr and the saturation current of the transformer T are designed in accordance with the resonance current.

  As a kind of resonance type power supply device, there is a world wide power supply device that supports both 100V system and 240V system. That is, in the world-wide power supply device, the input power supply voltage Vin is about 100V to 240V, which is twice or more wide. Therefore, the resonance current also has a double range. However, in the conventional resonance type power supply device, if the transformer T is designed not to saturate at 240 V, the 100 V system may not be able to bring out sufficient performance or malfunction. That is, it is difficult to make a conventional resonance power supply device as a world-ready power supply device as it is.

  For this reason, in the conventional resonance type power supply device, a special circuit that makes the input power supply voltage Vin constant is added in the previous stage, the capacitance value of the resonance capacitor Cr, and the inductance value of the primary winding N1 of the transformer T. It is dealt with by switching.

JP-A-9-163735 (FIG. 4) JP-A-8-66025

  As described above, the conventional resonance type power supply device has a problem that when the input power supply voltage fluctuates in a wide range, sufficient performance cannot be exhibited or malfunction occurs. For this reason, it is necessary to add a special circuit to the previous stage or replace the components constituting the resonance circuit.

  Accordingly, an object of the present invention is to provide a resonance type power supply device and a driving method thereof that can exhibit sufficient performance even when the input power supply voltage fluctuates in a wide range and does not cause malfunction.

  Another object of the present invention is to provide a resonant power supply apparatus and a driving method thereof that can automatically cope with fluctuations in the input power supply voltage without adding a special circuit in the previous stage or replacing parts. It is to provide.

  According to the first aspect of the present invention, there is provided a driving method of a full bridge resonance type power supply apparatus having a resonance circuit (Cr, N1) and turning on / off an input power supply voltage (Vin) by four switches (Q1 to Q4). When the input power supply voltage (Vin) is lower than a predetermined voltage, the full bridge resonant power supply device is operated in a full bridge, and when the input power supply voltage (Vin) is higher than the predetermined voltage, A driving method of the full bridge resonance type power supply apparatus, characterized in that the full bridge resonance type power supply apparatus is operated in a half bridge mode.

  Further, according to the second aspect of the present invention, there is provided a resonance type power supply device having a power supply input terminal (11) to which an input power supply voltage (Vin) is applied and a ground terminal (12). N1), a first switch (Q1) connected between the power input terminal and one end (21) of the resonance circuit, and a first switch connected between one end of the resonance circuit and the ground terminal. Two switches (Q2), a third switch (Q3) connected between the power input terminal and the other end (22) of the resonance circuit, and the other end of the resonance circuit and the ground terminal. Switching means comprising a fourth switch (Q4) connected in between, an input voltage detection circuit (40) for detecting the input power supply voltage and outputting a detection signal (E), and according to the detection signal By controlling on / off of the switching means Resonant power supply, characterized in that it comprises a control means for switching whether to or half bridge operation to full-bridge operation the resonant power supply (35, 45) is obtained.

  In the resonant power supply according to the second aspect of the present invention, the input voltage detection circuit (40) includes, for example, voltage dividing means (R1, R2) for dividing the input power supply voltage to generate a divided voltage. Reference voltage generating means (41) for generating a reference voltage, and a comparator (42) for comparing the divided voltage with the reference voltage and outputting the detection signal may be included.

  Further, the control means generates, for example, first to fourth control signals (A, B, C, D) for the first to fourth switches, respectively, so that the resonant power supply device is Based on the detection signal (E), the controller (35) for controlling to perform a full bridge operation, the third and fourth control signals are changed, and the changed third and fourth control signals ( C ′, D ′) to the third and fourth switches to switch the resonant power supply device between the full bridge operation and the half bridge operation, and a mode switching circuit (45). It may consist of Each of the first to fourth switches (Q1 to Q4) includes a switch that is turned on when the first to fourth control signals are at a logic high level, and the input voltage detection circuit (40) includes: A logic low level signal is output as the detection signal when the input power supply voltage (Vin) is lower than the predetermined voltage, and the detection is performed when the input power supply voltage (Vin) is higher than the predetermined voltage. A signal having a logic high level may be output as the signal. In this case, when the detection signal (E) is at a logic low level, the mode switching circuit (45) changes the third and fourth control signals (C, D) as they are. Control signal (C ', D') and when the detection signal (E) is at a logic high level, the changed third and fourth control signals (C ', D') are respectively logic low. Output level and logic high level signals. For example, the mode switching circuit (45) obtains a logical product of an inverter gate (G1) that inverts the detection signal and outputs an inverted signal, and the third control signal and the inverted signal. The AND gate (G2) that outputs the logical product result signal as the modified third control signal, and the logical sum of the fourth control signal and the detection signal are taken to change the logical sum result signal. An OR gate (G3) that outputs as a fourth control signal may be included.

  In addition, the code | symbol in the said parenthesis is attached | subjected in order to make an understanding of this invention easy, and it is only an example, and of course is not limited to these.

  In the present invention, when the input power supply voltage is lower than the predetermined voltage, the full bridge resonant power supply device is operated in full bridge. When the input power supply voltage is higher than the predetermined voltage, the full bridge resonant power supply device is operated in half bridge. Therefore, even if the input power supply voltage fluctuates in a wide range, sufficient performance can be exhibited and no malfunction occurs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  With reference to FIG. 3, the resonance type power supply device of the present invention will be described. The resonant power supply apparatus shown in the figure is a full-bridge resonant power supply apparatus in itself, but automatically switches between full-bridge operation and half-bridge operation according to the input power supply voltage Vin, as will be described later. It is possible to operate. Further, the resonance type power supply device is configured to be able to operate at either 100 V or 240 V as an AC voltage of an AC power supply (not shown).

  The AC voltage from the AC power source is full-wave rectified by the full-wave rectifier 30. The illustrated full wave rectifier 30 includes four rectifier bridge diodes D6, D7, D8, and D9. The voltage that has been full-wave rectified by the full-wave rectifier 30 is smoothed by the smoothing capacitor Ci to obtain the input power supply voltage Vin. That is, the full-wave rectifier 30 and the smoothing capacitor Ci constitute a DC power source.

  The input power supply voltage Vin is supplied between the first and second input terminals 11 and 12. The first input terminal 11 is called a power input terminal, and the second input terminal 12 is called a ground terminal. Between the first and second input terminals 11 and 12, a first series circuit including the first and second switches Q1 and Q2 and a second series including the third and fourth switches Q3 and Q4 are provided. The circuit is connected. Each of the first to fourth switches Q1 to Q4 includes an N-channel insulated gate field effect transistor (FET). First to fourth clamp diodes D1, D2, D3, and D4 are connected to the first to fourth switches Q1 to Q4 in reverse parallel, respectively. The first to fourth switches Q1 to Q4 are collectively referred to as switching means.

  Resonant with the primary winding N1 of the transformer T between the first connection point 21 of the first and second switches Q1, Q2 and the second connection point 22 of the third and fourth switches Q3, Q4. An LC series resonance circuit with the capacitor Cr is connected. The LC series resonance circuit is also simply called a resonance circuit. The transformer T has secondary windings N2a and N2b. One ends of the secondary windings N2a and N2b are connected to the output smoothing capacitor Co via first and second output rectifier diodes D11 and D12, respectively. That is, the first and third output rectifier diodes D11 and D12 and the output smoothing capacitor Co constitute an output rectification smoothing circuit. The output rectifying / smoothing circuit is also simply called an output circuit.

  A controller 35 is connected to the gates of the first to fourth switches Q1 to Q4. The controller 35 controls on / off of the first to fourth switches Q1 to Q4 as described later according to the input power supply voltage Vin. As will be described later, the controller 35 generates first to fourth control signals A, B, C, and D for controlling the first to fourth switches Q1 to Q4, respectively.

  As described above, since the first to fourth switches Q1 to Q4 are composed of N-channel insulated gate field effect transistors, the first to fourth switches supplied to their control electrodes (gates). The control signals A, B, C, and D are turned on when they are at a logic high level.

  The illustrated resonance power supply apparatus further includes an input voltage detection circuit 40 and a mode switching circuit 45.

  The input voltage detection circuit 40 is a circuit that detects the input power supply voltage Vin. When the input power supply voltage Vin is lower than a predetermined voltage, the input voltage detection circuit 40 outputs a detection signal E having a logic low level. When the input power supply voltage Vin is higher than a predetermined voltage, the input voltage detection circuit 40 outputs a detection signal E having a logic high level.

  More specifically, the input voltage detection circuit 40 is connected in series between the first and second input terminals 11 and 12, and includes two voltage dividing resistors R1 and R2 that generate a divided voltage Vdiv, and a reference. The reference voltage generating source 41 generates the voltage Vref, and the comparator 42 compares the divided voltage Vdiv with the reference voltage Vref. The divided voltage Vdiv is supplied to the non-inverting input terminal of the comparator 42, and the reference voltage Vref is supplied to the inverting input terminal. When the divided voltage Vdiv is lower than the reference voltage Vref, the comparator 42 determines that the AC power source generates an AC voltage of 100 V, and outputs a detection signal E having a logic low level. On the other hand, when the divided voltage Vdiv is higher than the reference voltage Vref, the comparator 42 determines that the AC power source generates an AC voltage of 240 V, and outputs a detection signal E having a logic high level. This detection signal E is supplied to the mode switching circuit 45.

  The mode switching circuit 45 is a circuit that switches between a full-bridge operation and a half-bridge operation of the resonance power supply device in cooperation with the controller 35 in accordance with the detection signal E. In other words, the mode switching circuit 45 changes the third and fourth control signals C and D output from the controller 35 according to the detection signal E, and changes the third and fourth control signals C ′. , D '. The changed third and fourth control signals C ′ and D ′ are supplied to the control electrodes (gates) of the third and fourth switches Q3 and Q4, respectively.

  Specifically, the mode switching circuit 45 includes an inverter gate G1, an AND gate G2, and an OR gate G3. The inverter gate G1 inverts the detection signal E and outputs an inverted signal. The AND gate G2 takes a logical product of the third control signal C output from the controller 35 and the inverted signal, and outputs the logical product as a third control signal C ′ obtained by changing the logical product result signal. The OR gate G3 takes the logical sum of the fourth control signal D output from the controller 35 and the detection signal E, and outputs the logical sum as a fourth control signal D ′ obtained by changing the logical sum result signal.

  In any case, the combination of the controller 35 and the mode switching circuit 45 is to control the on / off of the switching means in accordance with the detection signal E, so that the resonance type power supply device is operated in full bridge or half bridge. Acts as a control means for switching.

  Next, referring to FIG. 4 in addition to FIG. 3, the operation of the resonant power supply device according to the present embodiment will be described. FIG. 4 shows the first and second control signals A and B, the logical product result signal (modified third control signal) C ′, and the logical sum result signal (modified fourth control signal) D ′. 3 is a time chart showing a waveform of a detection signal E.

  First, an operation when an AC voltage of 100 V is applied from the AC power supply to the resonance power supply device will be described. In this case, since the divided voltage Vdiv of the input power supply voltage Vin is lower than the reference voltage Vref, the input voltage detection circuit 40 outputs a detection signal E having a logic low level. In this case, the mode switching circuit 45 uses the third and fourth control signals C and D output from the controller 35 as they are as the logical product result signal (changed third control signal) C ′ and the logical sum result signal (changed). Output as a fourth control signal D ′. In other words, the resonance type power supply device operates in the same manner as without the added mode switching circuit 45. As a result, the first to fourth control signals A, B, C, and D output from the controller 35 are directly guided to the gates of the first to fourth switches Q1 to Q4.

  Therefore, the resonant power supply device performs a normal (original) full-bridge operation. That is, the controller 35 controls the diagonally facing switches (for example, the first and third switches Q1 and Q3 or the second and fourth switches Q2 and Q4) to be turned on at the same time, and supplies current to the resonance circuit. To flow. Therefore, both ends 21 and 22 of the resonance circuit are alternately connected to the power input terminal 11 and the ground terminal 12. As a result, the resonance circuit is driven with a voltage 2Vin that is twice the input power supply voltage Vin.

  Next, an operation when an AC voltage of 240 V is applied from the AC power source to the resonant power supply device will be described. In this case, since the divided voltage Vdiv of the input power supply voltage Vin becomes higher than the reference voltage Vref, the input voltage detection circuit 40 outputs a detection signal E having a logic high level. In this case, the mode switching circuit 45, instead of the third and fourth control signals C and D output from the controller 35, is a logical low level logical product result signal (changed third control signal) C, respectively. 'And a logical high level logical sum result signal (changed fourth control signal) D' are output. As a result, the third switch Q3 maintains the off state, and the fourth switch Q4 maintains the on state. Therefore, the power input terminal 11 and the second connection point 22 are opened, and the second connection point 22 and the ground terminal 12 are short-circuited.

  As a result, the resonant power supply device performs a half-bridge operation. That is, the controller 35 drives the resonance circuit by controlling the first and second transistors Q1 and Q2 to be alternately turned on / off and off / on. Therefore, one end 21 of the resonance circuit is alternately connected to the power input terminal 11 and the ground terminal 12. As a result, the resonance circuit is driven by the input power supply voltage Vin.

  As described above, in the resonance type power supply device according to the present embodiment, it is possible to automatically switch between the full bridge resonance type power supply device and the half bridge operation according to the input power supply voltage Vin. For this reason, even if the input power supply voltage Vin fluctuates in a wide range, sufficient performance can be exhibited and no malfunction occurs. Further, unlike a conventional resonance type power supply device, it is not necessary to add a special circuit or replace parts in the previous stage.

  Although the present invention has been described above with reference to preferred embodiments, it is needless to say that the present invention is not limited to the above-described embodiments. For example, the resonant circuit is not limited to the LC series resonant circuit of the above-described embodiment, and various configurations of resonant circuits may be employed. The switch constituting the switching means is not limited to the N-channel insulated gate field effect transistor of the above embodiment, and it is needless to say that switches having various configurations may be adopted. Further, the input voltage detection circuit is not limited to that of the above embodiment, and input voltage detection means having various configurations may be employed. Of course, the control means is not limited to the above embodiment. Further, the mode switching circuit is not limited to the one in the above embodiment, and any configuration may be used as long as the circuit can switch between the full bridge operation and the half bridge operation. Further, the present invention can be applied not only to an AC power supply system but also to a DC / DC converter for a purpose in which the input power supply voltage fluctuation range is wide or the output voltage load fluctuation is large.

It is a block diagram which shows the structure of the principal part of the conventional full bridge resonance type power supply device. It is a block diagram which shows the structure of the principal part of the conventional half bridge resonance type power supply device. It is a block diagram which shows the structure of the resonance type power supply device which concerns on one embodiment of this invention. 4 is a time chart for explaining the operation of the resonant power supply device shown in FIG. 3.

Explanation of symbols

Ci smoothing capacitor Q1 to Q4 switch T transformer N1 primary winding N2a, N2b secondary winding Cr resonance capacitor 30 full-wave rectifier 35 controller 40 input voltage detection circuit 45 mode switching circuit

Claims (6)

A driving method of a full bridge resonance type power supply device having a resonance circuit and turning on / off an input power supply voltage with four switches,
When the input power supply voltage is lower than a predetermined voltage, the full bridge resonant power supply device is operated in a full bridge,
When the input power supply voltage is higher than the predetermined voltage, the full-bridge resonant power supply device is operated in a half-bridge mode. A resonant power supply device having a power input terminal to which an input power supply voltage is applied and a ground terminal,
A resonant circuit;
A first switch connected between the power input terminal and one end of the resonant circuit; a second switch connected between one end of the resonant circuit and the ground terminal; and the power input terminal; Switching means comprising a third switch connected between the other end of the resonant circuit and a fourth switch connected between the other end of the resonant circuit and the ground terminal;
An input voltage detection circuit for detecting the input power supply voltage and outputting a detection signal;
Control means for switching on / off of the switching means in accordance with the detection signal to switch between the full-bridge operation and the half-bridge operation of the resonance type power supply device. Type power supply.   The input voltage detection circuit compares the divided voltage and the reference voltage with voltage dividing means for dividing the input power supply voltage to generate a divided voltage, reference voltage generating means for generating a reference voltage, The resonant power supply device according to claim 2, further comprising a comparator that outputs the detection signal. The control means includes
A controller that generates first to fourth control signals for the first to fourth switches, respectively, and controls the resonant power supply device to perform the full-bridge operation;
By changing the third and fourth control signals based on the detection signal and supplying the changed third and fourth control signals to the third and fourth switches, the resonance A mode switching circuit that switches between a full-bridge operation and a half-bridge operation of the power supply device,
The resonance type power supply device according to claim 2, comprising: Each of the first to fourth switches is a switch that is turned on when the first to fourth control signals are at a logic high level, and the input voltage detection circuit is configured such that the input power supply voltage is the predetermined value. A logic low level signal is output as the detection signal when the voltage is lower than a voltage, and a logic high level signal is output as the detection signal when the input power supply voltage is higher than the predetermined voltage. And
The mode switching circuit outputs the third and fourth control signals as the changed third and fourth control signals as they are when the detection signal is at a logic low level, and the detection signal is at a logic high level. 5. The resonant power supply apparatus according to claim 4, wherein a logic low level signal and a logic high level signal are output as the changed third and fourth control signals, respectively. The mode switching circuit is
An inverter gate for inverting the detection signal and outputting the inverted signal;
An AND gate that takes a logical product of the third control signal and the inverted signal, and outputs a logical product result signal as the changed third control signal;
6. The resonance type power supply device according to claim 5, further comprising: an OR gate that takes a logical sum of the fourth control signal and the detection signal and outputs a logical sum result signal as the changed fourth control signal. .

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