DE112018001236T5 - Power source device and method for controlling the same - Google Patents

Abstract

A power source device is provided with a voltage detecting section for detecting the input voltage in the ON period of the first switching device and a determining section for determining whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first one Switching device is turned on, and the input voltage that was detected in a second period before the first period by a predetermined cycle, wherein a control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

Description

Technical part

The present invention relates to a power source apparatus and a method of controlling the power source apparatus.

This application claims priority on the basis of the filed on March 9, 2017 Japanese Patent Application No. 2017-045257 and their disclosure is incorporated herein in its entirety.

State of the art

DC / DC converters for converting DC voltages have been used in industrial equipment and vehicle equipment. As such, DC / DC converters, active-clamp type DC / DC converters are available. In an active-terminal-type DC / DC converter, a series circuit of the primary winding of a transformer and a main switching device is connected to a DC power source, and an active-terminal circuit consisting of a capacitor and an auxiliary switching device is over both ends of the primary winding connected. In addition, the main switching device and the auxiliary switching device are turned on and off alternately in a desired duty ratio, whereby the magnetization energy and the loss energy of the transformer can be circulated through the capacitor of the active terminal circuit and the power efficiency of the converter can be improved.

If there is a delay in maintaining the duty cycle, z. B. by changing the input voltage, too high excitation current flows in the transformer, the transformer is magnetically saturated, and there is a risk that the excitation current increases abruptly. Therefore, a DC / DC converter has been disclosed in which the instantaneous value of the primary side current of the transformer is detected, the difference between the detected instantaneous value and the mean value of past instantaneous values is obtained, and if the difference is equal to or greater than a predetermined value, Excitation operation of the transformer is stopped and a magnetic reset is performed (refer to Patent Document 1).

Document on the state of the art

Patent document

Patent Document 1: Japanese Patent Application Laid-open Publication No. Hei. 2008-199878

Summary of the invention

The power source device according to this disclosure is a power source device equipped with: a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series connection of a second switching device and a second capacitor, which are connected in parallel with the primary winding; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required duty ratio, an input voltage is applied to the primary winding of the transformer, the power source device is further provided with a voltage detecting section for detecting the input voltage in the ON period of the first switching device and a determining section for determining whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first switching device is turned on and the input voltage in a second period was detected before the first period by a predetermined cycle, wherein the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

The method of controlling the power source apparatus according to this disclosure is a method of controlling a power source apparatus equipped with: a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series connection of a second switching device and a second capacitor, which are connected in parallel with the primary winding; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required duty ratio, an input voltage is applied to the primary winding of the transformer, the voltage detecting section detects the input voltage in the ON period of the first switching device Determining section determines whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first switching device is turned on and the input voltage detected in a second period before the first period through a predetermined cycle and the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

list of figures

• 1 Fig. 10 is an explanatory view showing an example of a circuit configuration of a power source device according to this embodiment;
• 2 Fig. 12 is an explanatory view showing an example of a circuit configuration of a voltage detection section according to this embodiment;
• 3 FIG. 10 is a timing chart showing examples of waveforms at various portions of the power source device according to this embodiment; FIG.
• 4 FIG. 14 is an explanatory view showing an example of the operation state of the power source device according to this embodiment in period. FIG D1 shows;
• 5 FIG. 14 is an explanatory view showing an example of the operation state of the power source device according to this embodiment in period. FIG D2 shows;
• 6 FIG. 14 is an explanatory view showing an example of the operation state of the power source device according to this embodiment in period. FIG D3 shows;
• 7 FIG. 14 is an explanatory view showing an example of the operation state of the power source device according to this embodiment in period. FIG D4 shows;
• 8th FIG. 12 is a schematic diagram illustrating the relationship between the input voltage and the output voltage of the power source device according to this embodiment; FIG.
• 9 Fig. 10 is a timing chart showing an example of a method for determining the duty ratio of the FET of the power source device according to this embodiment;
• Fig. 11 is a timing chart showing an example of the traceability of the duty ratio in the case where the input voltage abruptly increases;
• 11 Fig. 11 is a timing chart showing an example of the traceability of the duty ratio in the case where the input voltage abruptly decreases;
• 12 Fig. 11 is a timing chart showing an example of a control method by the power source apparatus according to this embodiment in the case where the input voltage abruptly increases;
• 13 Fig. 11 is a timing chart showing an example of a control method by the power source apparatus according to this embodiment in the case where the input voltage abruptly decreases;
• 14 Fig. 12 is an explanatory view showing another example of a circuit configuration of the power source device according to this embodiment;
• 15 Fig. 12 is an explanatory view showing an example of a circuit configuration of the voltage detection section according to this embodiment; and
• 16 FIG. 12 is a flowchart showing an example of a processing process of the method for controlling the power source apparatus according to this embodiment. Modes for carrying out the invention

Problem to be solved by the present disclosure.

However, since the instantaneous value of the current is compared with the average value of the conventional DC / DC converter disclosed in Patent Document 1, even if the value of the current that has not reached the current value is the value of the current that is the magnetic saturation caused the transformer, the excitation operation of the transformer is stopped only when the value of the current has reached its peak value. As a result, the magnetic recovery occurs after the magnetic saturation of the transformer, whereby the transformer can not be prematurely prevented from the magnetic saturation.

Accordingly, the present disclosure is intended to provide a power source device capable of prematurely preventing the transformer from becoming magnetically saturated and a method of controlling the power source device.

[Advantageous Effects of the Present Disclosure]

According to the present disclosure, the transformer can be prematurely prevented from magnetic saturation.

[Explanation of an embodiment of the present invention]

The power source device according to an embodiment is a power source device equipped with: a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series connection of a second switching device and a second capacitor, which are connected in parallel with the Primary winding are switched; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required duty ratio, an input voltage is applied to the primary winding of the transformer, the current source device further comprising a voltage detecting section for detecting the input voltage in the ON period the first switching device and a determining section for determining whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first switching device is turned on and the input voltage that is in a second period before the first one Period is detected by a predetermined cycle, the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

The method of controlling the power source apparatus according to the embodiment is a method of controlling a power source apparatus equipped with: a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series connection of a second switching device and a second capacitor, which are connected in parallel with the primary winding; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required duty ratio, an input voltage is applied to the primary winding of the transformer, a voltage detecting section detects the input voltage in the ON period of the first switching device Determining section determines whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first switching device is turned on and the input voltage detected in a second period before the first period through a predetermined cycle and the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

The voltage detecting section detects the input voltage in the ON period of the first switching device. Specifically, the input voltage detected at the voltage detection section is a voltage corresponding to the actual input voltage applied to the power source device, and may be set lower than the actual input voltage.

On the basis of the input voltage detected in the first period in which the first switching device is turned on and the input voltage detected in the second period before the first period through the predetermined cycle, the determining section determines whether the transformer is magnetically saturated or not. The predetermined cycle can z. B. can be set to the switching cycle of the first switching device and the second switching device. In the event that the first period is assumed to be an n-cycle, the second period may be assumed to be a (n-1) cycle.

When the input voltages applied to the power source device change abruptly (eg, abruptly increase or abruptly decrease), there is sometimes a delay in maintaining the duty cycle. In the transitional period when the delay in maintaining the duty ratio occurs, an unbalanced state occurs between the positive electrode magnetic energy and the negative electrode magnetic energy of the transformer, and there is a risk that the transformer may be magnetically saturated , On the basis of the input voltages detected in the first and second periods, it is thus determined whether the input voltage has changed abruptly. For example, when the rate of change (or the amount of change) of the voltage detected in the first period (eg, the n-cycle) is greater than that of the voltage detected in the second period (eg, the (n-1) cycle) , it can be determined that the transformer will be magnetically saturated before the transformer magnetically saturates.

The control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section. For example, when the determination section has determined that the magnetic saturation is occurring, the control section may control the ON / OFF operation of the first switching device before the magnetic saturation occurs. This can prevent the transformer from becoming magnetically saturated.

In the power source apparatus according to this embodiment, in the case where the ratio of the input voltage detected in the first period to the In the second period, if the input voltage detected in the second period is equal to or more than a predetermined upper limit value or equal to or less than a predetermined lower limit value, the determination section determines that the transformer will be magnetically saturated.

In the case that the ratio of the input voltage detected in the first period to the input voltage detected in the second period is equal to or more than a predetermined upper limit value, or equal to or smaller than a predetermined lower limit value, the determining section determines that the transformer is magnetically saturated will be.

It is assumed that the second period is the (n-1) cycle that the input voltage V (n-1) detected in the second period is that the first period is the n-cycle and that the one detected in the first period input voltage V (n) is. In the case of V (n) ≥ X1 * V (n-1), where X1 is the upper limit, the determination section may determine that the transformer will be magnetically saturated. The upper limit X1 may be used as a threshold after which the determining section may determine that the transformer will be magnetically saturated before the transformer is magnetically saturated. In other words, although the transformer at the time of detection of V (n) is not yet magnetically saturated, the upper limit can only be used as a threshold, after which the determining section can determine that the transformer becomes magnetically saturated at a time after the above-mentioned time.

In the case of V (n) ≦ X2 * V (n-1), where X2 is the lower limit, the determining section may determine that the transformer will be magnetically saturated. The lower limit X2 may be used as a threshold after which the determining section may determine that the transformer will be magnetically saturated before the transformer is magnetically saturated.

With the above configuration, even with an abrupt change in input voltage (eg, abrupt increase or abrupt drop), it can be determined that the transformer will be magnetically saturated before the transformer is magnetically saturated.

In the power source device according to this embodiment, when the ratio is equal to or greater than the upper limit, the control section controls the ON / OFF operation of the first switching device such that the ON period of the first switching device becomes shorter than the ON period based on the required duty cycle.

If the ratio is equal to or greater than the upper limit value, the control section controls the ON / OFF operation of the first switching device so that the ON period of the first switching device becomes shorter than the ON period based on the required duty ratio.

If the ratio is equal to or greater than the upper limit, i. H. at V (n) ≥ X1 * V (n-1), the voltage (eg, the positive electrode voltage) to be applied to the transformer in the ON period of the first switching device is increased and the exciting current at the positive Electrode rises, whereby an imbalance between the magnetic energy at the positive electrode and the magnetic energy at the negative electrode (the magnetic energy of the positive electrode> the negative electrode magnetic energy) and magnetic saturation may occur.

Thus, the ON / OFF operation of the first switching device is controlled so that the ON period of the first switching device becomes shorter than the ON period based on the required duty ratio. Thus, it is possible to prevent the voltage (eg, the positive electrode voltage) applied to the transformer in the ON period of the first switching device from becoming too high, and it is still possible to increase the exciting current suppressing the positive electrode, whereby the magnetic energy at the positive electrode and the magnetic energy at the negative electrode is brought into a balanced state and the transformer can be protected from magnetic saturation.

In the power source device according to this embodiment, when the ratio is equal to or smaller than the lower limit, the control section controls the ON / OFF operation of the first switching device such that the ON period of the first switching device becomes longer than the ON period based on the required duty cycle.

When the ratio is equal to or smaller than the lower limit value, the control section controls the ON / OFF operation of the first switching device so that the ON period of the first switching device becomes longer than the ON period based on the required duty ratio.

If the ratio is equal to or less than the lower limit, i. H. in the case of V (n) ≦ X1 * V (n-1), the voltage (eg, the positive electrode voltage) to be applied to the transformer in the ON period of the first switching device becomes insufficient and the exciting current at the positive electrode, whereby an imbalance between the magnetic energy at the positive electrode and the magnetic energy at the negative electrode (the magnetic energy of the positive electrode <the negative electrode magnetic energy) and a magnetic saturation may occur.

Thus, the ON / OFF operation of the switching device is controlled so that the ON period of the first switching device corresponding to the required duty ratio becomes longer than the ON period. Thus, it is possible to prevent the voltage (eg, the positive electrode voltage) applied to the transformer in the ON period of the first switching device from being insufficient, and it is further possible to suppress the decrease of the exciting current at the suppressing positive electrode, whereby the magnetic energy at the positive electrode and the magnetic energy at the negative electrode is brought into a balanced state and the transformer can be protected from magnetic saturation.

The power source device according to this embodiment is provided with a binary output section that outputs either one of the binary values depending on whether the ratio is equal to or greater than the upper limit value or the ratio is equal to or smaller than the lower limit value, or with an insulating transmission device for transmission of the binary value from the binary output section, wherein the determining section determines whether the transformer is magnetically saturated depending on the output of the insulating transmission device.

The binary output section outputs one of the binary values depending on whether the ratio is equal to or greater than the upper limit value or the ratio is equal to or less than the lower limit value. The binary output section may for example consist of a circuit with comparators and may include a comparator in which the ratio and the upper limit are input and the other comparator in which the ratio and the lower limit are input.

The insulating transmission device transmits the binary value output from the binary output section. The insulating transmission means may be made of, for example, a photocoupler, and the input side may be electrically insulated from the output side. The determination section determines whether the transformer is magnetically saturated depending on the power of the insulating transmission device.

Since the binary output section and the insulating transmission device are used, the change of the input voltage can be transmitted to the determining section by means of a digital signal. In general, if the change in input voltage is transmitted via an analog signal without conversion, a separate isolation transformer or the like is required to provide electrical isolation between the primary side (eg, the circuit to which the input voltage is applied) is) of the power source device and the determination section to secure, which is expensive. Since the binary output section and the insulating transmission device are used, the change of the input voltage can be transmitted to the determining section via the electrically isolated digital signal, whereby this configuration can be achieved inexpensively.

The power source apparatus according to this embodiment is provided with a first voltage divider circuit connected across input terminals to which the input voltage is applied and having a plurality of resistors connected in series and a second voltage divider circuit connected across the input terminals and having resistors and one in Row capacitor connected, wherein the voltage detecting portion detects the input voltage in the first period of the first voltage divider circuit and also detects the input voltage in the second period of the second voltage divider circuit.

The first voltage divider circuit is connected across the input terminals to which the input voltage is applied, and has the plurality of resistors connected in series. The second voltage divider circuit is connected across the input terminals and has the resistors and the capacitor connected in series.

The voltage detecting section detects the input voltage in the first period (eg, the n-cycle) from the first voltage dividing circuit. More specifically, assuming that the voltage to be applied across the first voltage divider circuit is VIN (n) is and that the voltage to be divided by the plurality of resistors of the first voltage divider circuit V (n) is, the voltage detecting section detects the voltage V (n) ,

The voltage detecting section detects the input voltage in the second period (eg, the (n-1) cycle) from the second voltage dividing circuit. More specifically, the voltage detecting section can detect the voltage at the junction of the resistors and the capacitor. Since the time constant, after which the capacitor is charged or discharged via the resistors, is almost equal to the given cycle (ie the time from (n - 1) Cycle to the n cycle), the voltage detecting section may detect the voltage V (n - 1) from the second voltage divider circuit at the time when the voltage V (n) is detected by the first voltage divider circuit.

The power source device according to this embodiment is provided with a first one Voltage divider circuit which is connected via one end side of the secondary winding of the transformer and a predetermined ground and having a plurality of series-connected resistors and a second voltage divider circuit which is connected via the one end side and the ground and having resistors and a capacitor connected in series wherein the voltage detecting section detects the input voltage in the first period from the first voltage dividing circuit and also detects the input voltage in the second period from the second voltage dividing circuit.

The first voltage divider circuit is connected across the one end side of the secondary winding of the transformer and the predetermined ground, and has the plurality of resistors in series. The second voltage divider circuit is connected across the one end side of the secondary winding of the transformer and the ground and has the resistors and the capacitor connected in series.

The voltage detecting section detects the input voltage in the first period (eg, the n-cycle) from the first voltage dividing circuit. More specifically, assuming that the winding ratio of the primary winding to the secondary winding is 1: N, the voltage to be applied to the first voltage dividing circuit is N * VIN (n), and that of the voltage to be divided by the plurality of resistors of the first voltage dividing circuit V (n) is, the voltage detecting section detects the voltage V (n) ,

The voltage detecting section detects the input voltage in the second period (eg, the (n-1) cycle) from the second voltage dividing circuit. More specifically, the voltage detecting section can detect the voltage at the junction of the resistors and the capacitor. Since the time constant after which the capacitor is charged or discharged through the resistors is set to be almost equal to the predetermined cycle (ie, the time of (n - 1) Cycle to the n cycle), the voltage detecting section may detect the voltage V (n - 1) from the second voltage divider circuit at the time when the voltage V (n) is detected by the first voltage divider circuit.

[Details of the embodiment of the present invention]

The embodiment of the present invention will be described below with reference to the drawings. 1 FIG. 14 is an explanatory view showing an example of a circuit configuration of a power source device. FIG 100 according to this embodiment shows. The power source device 100 according to this embodiment is with the terminals A and B on the input side and the connections C and D equipped on the output side, a DC power source (not shown) is via the terminals A and B connected to the input side, and a load is across the connections C and D connected on the output side. The power source device 100 is, for example, a buck converter.

The power source device 100 is for example with a transformer 30 ; a MOSFET (Metal Oxide Semiconductor Field Effect Transistor, hereinafter called "FET") 11 as the first switching device; a capacitor 21 as the first capacitor; a FET 12 as the second switching device; a capacitor 22 serving as second capacitor; a diode 41 and a diode 42 which form a rectifier circuit; a capacitor 23 ; an inductance 61 (a choke coil on the output side); and a control section 50 for controlling the ON / OFF operation of the FET 11 and the FET 12 fitted.

An end to the primary winding 31 of the transformer 30 is connected to port A. The drain of the FET 11 is with the other end of the primary winding 31 connected. The source of the FET 11 is connected to port B. The capacitor 21 (Resonance capacitor) is across the drain and the source of the FET 11 connected.

A series connection of the FET 12 and the capacitor 22 is over the two ends of the primary winding 31 connected. The series connection of the FET 12 and the capacitor 22 forms an active terminal circuit.

In the in 1 Example shown is one end of the capacitor 22 with one end of the primary winding 31 connected, and the drainage of the FET 12 is with the other end of the capacitor 22 connected. The source of the FET 12 is with the other end of the primary winding 31 connected.

The cathode of the diode 41 is with one end of the secondary winding 32 of the transformer 30 connected, and the anode of the diode 41 is with the connection D (Grounding) connected. The cathode of the diode 42 and one end of the inductor 61 are at the other end of the secondary winding 32 connected. The anode of the diode 42 is with the anode of the diode 41 connected. In the in 1 Although the anodes of the respective diodes 41 and 42 interconnected but not limited to the cathodes of the respective diodes 41 and 42 be connected to each other.

The other end of the inductor 61 is with the connection C connected. The capacitor 23 is about the connections C and D connected. The control section 50 gives gate voltages to the gates of the FET 11 and the FET 12 out.

The control section 50 is for example with a determination section 51 fitted.

2 FIG. 10 is an explanatory view showing an example of a circuit configuration of a voltage detection section. FIG 70 according to this embodiment shows. The voltage detection section 70 is for example with the resistors 711 . 712 and 721 , a capacitor 722 , the multiplication circuits 73 and 74 , the comparators 75 and 76 , a NAND circuit 77 and a photocoupler 78 fitted. Each of the comparators 75 and 76 and the multiplication circuits 73 and 74 have the function of serving as a voltage detection section.

More specifically, the resistors 711 and 712 over the connections A and B connected in series. The resistance 721 and the capacitor 722 are above the connection point of the resistors 711 and 712 and the connection B connected in series. The connection point of the resistors 711 and 712 is to the inverting input terminal of the comparator 75 and the non-inverting input terminal of the comparator 76 connected. The connection point of the resistor 721 and the capacitor 722 is connected to the input terminals of the multiplication circuits 73 and 74 connected. The multiplication circuit 73 multiplies the supplied voltage with X1 and then outputs the obtained voltage through its output terminal. The output terminal of the multiplication circuit 73 is connected to the non-inverting input terminal of the comparator 75 connected. In addition, the multiplication circuit multiplies 74 the supplied voltage with X2 and then outputs the obtained voltage through its output terminal. The output terminal of the multiplication circuit 74 is to the inverting input terminal of the comparator 76 connected. The output terminals of the comparators 75 and 76 are connected to the input terminals of the NAND circuit 77 connected. The output terminal of the NAND circuit 77 is with the input side of the photocoupler 78 and the output side of the photocoupler 78 with the control section 50 connected.

The series connection of the resistors 711 and 712 over the connections A and B are connected, forms a first voltage divider circuit 71 , In other words, the first voltage divider circuit 71 gives the tension V out by dividing the input voltage VIN over the connections A and B to the inverting input terminal of the comparator 75 and the non-inverting input terminal of the comparator 76 is obtained.

The series connection of the resistors 711 and 721 and the capacitor 722 over the connections A and B are connected, forms a second voltage divider circuit 72 , In other words, the second voltage divider circuit 72 outputs the voltage V by dividing the input voltage VIN is obtained through the connections A and B to the multiplication circuits 73 and 74 is created.

In the second voltage divider circuit 72 becomes the time constant after which the capacitor 722 about the resistance 721 is charged or discharged almost equal to the switching cycle (given cycle) of the power source device 100 made, wherein the voltage to be detected via the second voltage divider circuit 72 with respect to the voltage V to be detected via the first voltage divider circuit 71 by the given cycle (the switching cycle of the FETs 11 and 12 the power source device 100 ) can be delayed. In other words, as in 2 shown, can be a voltage V (n - 1) from the second voltage divider circuit 72 be detected at the time to which a voltage V (n) from the first voltage divider circuit 71 is detected. The voltage V (n) herein is an n-cycle voltage and the voltage V (n - 1) is herein a tension with a (n - 1) Cycle.

The multiplication circuit 73 outputs a voltage X1 * V (n - 1) by multiplying the voltage V (n - 1) With X1 is obtained. The coefficient X1 herein is the upper limit. In addition, there is the multiplication circuit 74 a voltage X2 * V (n - 1) by multiplying the voltage V (n - 1) With X2 is obtained. The coefficient X2 herein is the lower limit.

The comparator 75 has the function of serving as the voltage detecting section and the binary output section, and the comparator 75 In the case where the voltage V (n) ≥ is the voltage X1 * V (n-1), 0 (low level) outputs 0, and outputs 1 (high level) in the case where the voltage V (n) < the voltage X1 -V (n - 1) is off. In other words, the comparator 75 returns 0 if the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or greater than the upper limit X1 is.

The comparator 76 has the function of serving as the voltage detecting section and the binary output section, and the comparator 76 gives 0 (low level) for the case that the voltage V (n) ≦ the voltage X2 * V (n-1), and outputs 1 (high level) in the case where the voltage V (n)> the voltage X2 * V (n - 1) is off. In other words, the comparator 76 gives 0 off, if the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or less than the lower limit X2 is.

In the event that either the comparator 75 or the comparator 76 0 outputs, outputs the NAND circuit 77 1 (high level) and drives the photo clutch 78 on, with the photocoupler 78 1 (high level) to the control section 50 outputs.

In other words, in the case that the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or greater than the upper limit X1 is, or in the event that the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or less than the lower limit X2 is, the control section can 50 1 (high level) from the voltage detection section 70 purchase.

In the case of a connection configuration, not shown, in which instead of the NAND circuit 77 separate emergency circuits to the respective output stages of the comparators 75 and 76 and separate photocouplers are connected to the outputs of the respective NOT circuits, the control section 50 distinguish and determine if the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or greater than the upper limit X1 or the ratio of the voltage detected in the n-cycle V (n - 1) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or less than the lower limit X2 is.

Next, the operation of the power source device will be described 100 described according to this embodiment.

3 FIG. 13 is a timing chart showing examples of waveforms at various portions of the power source apparatus. FIG 100 according to this embodiment shows. 3 schematically shows the different waveforms of the gate voltage of the FET 11 , the gate voltage of the FET 12 , the voltage of the transformer 30 (also called transformer voltage) and the excitation current of the transformer 30 (hereinafter also called exciting current). Since the waveforms of the respective sections are schematically illustrated for the sake of clarity, the actual waveforms of the respective sections may be different in some cases.

As in shown, a cycle T is divided into four periods: D1 . D2 . D3 and D4 , The cycle T is a predetermined cycle and is the switching cycle of the FETs 11 and 12 , For example, although the duty cycle is about 100 kHz, the cycle is not limited to this value. The period D1 is the ON period of the FET 11 , and the FET 11 is used with a given duty cycle ( D1 / T) on and off. In the period D1 becomes the positive electrode voltage V1 of the transformer 30 created. In addition, the excitation current increases linearly.

In addition, the period is D3 the ON period of the FET 12 , and the FET 12 is used with a given duty cycle ( D3 / T) on and off. In the period D3 becomes the negative electrode voltage V2 of the transformer 30 created. In addition, the excitation current decreases linearly. In the state in which the magnetic energy of the transformer 30 is balanced, a formula V1 × D1 ≈ V2 × D3 is set.

The periods D2 and D4 are periods in which both the FET 11 as well as the FET 12 are turned off. Subsequently, the operating conditions of the power source device 100 in the respective periods D1 to D4 described in succession.

4 FIG. 16 is an explanatory view showing an example of the operation state of the power source device. FIG 100 according to this embodiment in the period D1 shows. As in is shown in the period D1 the FET 12 switched on and the FET 12 under the control of the control section 50 switched off. In the period D1 becomes the input side power source voltage to the primary winding of the transformer 30 applied and the voltage of the primary winding becomes positive. The voltage of the secondary winding also becomes positive, and the diode 41 becomes conductive and a load current flows in the load. The sum of load current and excitation current flows in the primary winding of the transformer 30 , As in shown, the excitation current increases linearly. In 4 A reference symbol Lm represents the excitation inductance of the transformer 30 of and a reference character ls represents a leakage inductance. For clarity, in in the case that the potential at the upper end of the primary winding and the secondary winding is higher than at the lower end, the potential is assumed to be the positive electrode voltage.

Although that of the on the primary side and the secondary side of the transformer 30 flowing magnetic fluxes are canceled together because the excitation current generates a magnetic flux, one of the factors that determines whether the transformer 30 is magnetically saturated or not, the excitation current.

5 FIG. 16 is an explanatory view showing an example of the operation state of the power source device. FIG 100 according to this embodiment in the period D2 shows. In the period D2 will the FET 11 switched off. Of the FET 12 stays off. Because the FET 11 in the period D2 is turned off, the capacitor becomes Cs ( 21 ) and kept the exciting current. The capacitor 21 is also called a capacitor Cs indicated to indicate that the capacitor 21 serves as a resonance capacitor. When the voltages of the transformer 30 (the primary winding and the secondary winding) will decrease and become negative, the diode is 41 biased backwards and does not become conductive. The load current leading to the diode 41 has flowed, flows over the diode 42 ,

6 FIG. 16 is an explanatory view showing an example of the operation state of the power source device. FIG 100 according to this embodiment in the period D3 shows. In the period D3 will the FET 12 switched on. Of the FET 11 stays off. Since the FET 12 in the period D3 is turned on, the voltage of the capacitor 22 in the opposite direction (negative voltage direction) to the transformer 30 applied, the excitation current of the transformer 30 decreases and the excitement of the transformer 30 is put in a reset state. Thereafter, the excitation current of the transformer 30 vice versa (becomes negative, the direction of the current is reversed), that in the condenser 22 stored energy is discharged, and the energy is in the leakage inductance Ls of the transformer 30 saved.

7 FIG. 16 is an explanatory view showing an example of the operation state of the power source device. FIG 100 according to this embodiment in the period D4 shows. In the period D4 will the FET 12 turned off and the FET 11 stays off. In the period D4 a resonance occurs through the transformer 30 (more precisely, the leakage inductance ls ) and the capacitor Cs on. The load current I1 (indicated by solid lines in the figure), the excitation current Im flowing in the load (indicated by broken lines in the figure) of the transformer 30 and the resonance current Ir (indicated by dashed lines in the figure) caused by the resonance of the transformer 30 (the leakage inductance Ls of the transformer 30 ) and the capacitor Cs flow in the diode 42 ,

The load current I1 flows in the out of the diode 42 , the inductor 61 and the closed loop formed by the load. The load current I1 becomes a constant value by, for example, the inductance of the inductor 61 relatively increased.

The excitation current Im flows in the out of the transformer 30 and the diodes 41 and 42 formed closed circuit. Since the voltage applied to the excitation inductance Lm in the period D4 is close to zero, the excitation current Im remains.

8th is a schematic representation showing the relationship between the input voltage and the output voltage of the power source device 100 represents according to this embodiment. In the figure it is assumed that the switching cycle is T and that the ON period of the FET 11 D is (according to the period D1 in 3 ). The horizontal axis represents the time. It is assumed that the winding ratio of the primary winding to the secondary winding is 1: N. Because of the conversion of the input voltage VIN in the secondary side voltage is N-VIN, a relationship of D * N * VIN = T * VOUT is established if a loss and the like are ignored. In other words, the duty ratio Dt of the FET 11 can be determined by Dt = D / T = (VOUT / VIN) * (1 / N).

In the power source device 100 according to this embodiment, in the period D in which the FET 11 in the switching cycle (given cycle) T is turned on, the transformer 30 fed magnetic energy and the output power of the load through to the transformer 30 delivered in the period D. The magnetic energy is discharged and the magnetic reset occurs in the ON period (corresponding to the period D3 in 3 ) of the FET 12 although this is in 8th not shown.

9 FIG. 13 is a timing chart showing an example of a method of determining the duty of the FET. FIG 11 the power source device 100 according to this embodiment shows. The upper part of the figure shows the input voltage VIN , and the lower part of the figure shows the duty cycle of the FET 11 , The horizontal axis represents the time.

If initially it is assumed that the duty cycle in the (n - 1) cycle Dt (n - 1) is, the FET turns off 11 only in the period corresponding to Dt (n-1), and it is assumed that the input voltage in (n - 1) cycle VIN (n - 1) is. The control section 50 obtains the duty ratio Dt (n) in the n-cycle with Dt (n) = (VOUT / VIN (n-1)) * (1 / N). VOU is herein a given output voltage and has a constant value.

In the n-cycle, the FET 11 only in the period that Dt (n) equals, turns on, and it is assumed that the input voltage is in the n-cycle VIN (n) is. The control section 50 gets the duty cycle Dt (n + 1) in the (n + 1) Cycle with Dt (n + 1) = (VOUT / VIN (n)) * (1 / N). As described above, the control section determines 50 the Duty cycle of the FET 11 in a given cycle based on the input voltage in the previous cycle. Thus, even if the input voltage VIN changes within its allowable range, the required output voltage can be adjusted by adjusting the duty ratio of the FET 11 be issued.

The respective duty cycles Dt (n - 1) . Dt (n) and Dt (n + 1) are duty ratios which have been finely adjusted in response to the change of the input voltage on the basis of the required duty ratio predetermined for outputting the predetermined output voltage (output power), and the duty ratios may be referred to as required duty ratios.

Next, a case where the input voltage abruptly changes will be described. The case where the input voltage abruptly changes is, for example, a case in which a delay in keeping the duty ratio occurs.

FIG. 13 is a timing chart showing an example of the traceability of the duty ratio in the case where the input voltage abruptly increases. The upper part of the figure shows the input voltage VIN , and the lower part of the figure shows the duty cycle of the FET 11 , The horizontal axis represents time. Assuming at first that the duty cycle in the (n - 1) cycle Dt (n - 1) is, the turns FET 11 only in the period that Dt (n - 1) corresponds to, and the input voltage in (n - 1) Cycle is called VIN (n - 1) accepted.

The duty cycle Dt (n) in the n-cycle is given by Dt (n) = (VOUT / VIN (n-1)) * (1 / N), and the input voltage in the n-cycle is assumed to have changed as far as the input voltage indicated by the dashed line, ie, relatively small relative to the input voltage VIN (n - 1) in the (n - 1) Cycle is changed. In practice, however, it is assumed that the input voltage VIN (n), which is opposite to the input voltage VIN (n - 1) has significantly increased, was created. Consequently, it is considered that the voltage corresponding to the shaded area has been applied too much and a delay in keeping the duty ratio occurs. In this case, that will be the transformer 30 supplied magnetic energy greater than the magnetic energy to be discharged and the magnetic energy is unbalanced.

11 FIG. 13 is a timing chart showing an example of the traceability of the duty ratio in the case where the input voltage abruptly decreases. The upper part of the figure shows the input voltage VIN , and the lower part of the figure shows the duty cycle of the FET 11 , The horizontal axis represents time. Assuming at first that the duty cycle in the (n - 1) cycle Dt (n - 1) is, the turns FET 11 only in the period that Dt (n - 1) corresponds to, and the input voltage in (n - 1) Cycle is called VIN (n - 1) accepted.

The duty cycle Dt (n) in the n-cycle, Dt (n) = (VOUT / VIN (n-1)) * (1 / N), and it is assumed that the input voltage in the n-cycle changes as the voltage in the n-cycle changes Input voltage is indicated by the broken line, ie, relatively small compared to the input voltage VIN (n - 1) is changed in the (n - 1) cycle. In reality, however, it is assumed that the input voltage VIN (n), which abruptly compared to the input voltage VIN (n - 1) has decreased, was created. Consequently, it is considered that the voltage corresponding to the shaded area becomes insufficient and a delay in keeping the duty ratio occurs. In this case, that will be the transformer 30 to be supplied magnetic energy smaller than the magnetic energy to be discharged and the magnetic energy is brought out of balance.

Next, a method for determining if the transformer 30 in the power source device 100 according to this embodiment is magnetically saturated or not described.

On the basis of the input voltage, which in a first period in which the FET 11 is turned on, and the input voltage detected in a second period before the first period by the predetermined cycle, the determining section determines 51 whether the transformer 30 is magnetically saturated or not. The predetermined cycle can z. B. on the switching cycle of FETs 11 and 12 be set. In the event that the first period is assumed to be an n-cycle, the second period may be considered a (n - 1) Cycle are accepted.

The at the comparators 75 and 76 measured input voltage is a voltage that is the actual input voltage to the power source device 100 corresponds to (equivalent) and can be set lower than the actual input voltage.

When the to the power source 100 abruptly changing applied input voltages (eg abruptly rising or falling off abruptly), there is sometimes a delay in maintaining the duty cycle, as in and shown. In the transitional period when the delay in maintaining the duty cycle occurs An unbalanced state occurs between the positive electrode magnetic energy and the negative electrode magnetic energy of the transformer 30 on, and there is a risk that the transformer 30 can be magnetically saturated.

On the basis of the input voltages detected in the first and second periods, it is thus determined whether the input voltage has changed abruptly. For example, if the rate of change (or the amount of change) of the voltage detected in the first period (eg, the n-cycle) is greater than that in the second period (eg, the n-cycle) (n - 1) Cycle) detected voltage, it can be determined that the transformer 30 is magnetically saturated before the transformer 30 is magnetically saturated.

The control section 50 controls the ON / OFF operation of the FET 11 based on the determination result of the determination section 51 , For example, if the determining section 51 has determined that the magnetic saturation occurs, the control section 50 the ON / OFF operation of the FET 11 control before the magnetic saturation occurs. Thus, the transformer 30 be prevented prematurely from magnetic saturation.

Specifically, in the case that the ratio of the input voltage detected in the first period to the input voltage detected in the second period is equal to or more than a predetermined upper limit, or equal to or less than a predetermined lower limit, the determination section determines 51 in that the transformer becomes magnetically saturated.

It is believed that the second period of (n - 1) Cycle is that the input voltage detected in the second period V (n - 1) is that the first period is the n-cycle and that the input voltage detected in the first period is V (n). In the case of V (n) ≥ X1 * V (n-1), where X1 is the upper limit, that is, 1 (high level) from the voltage detection section 70 (via the comparator 75 ) is detected, the determination section 51 determine that the transformer 30 becomes magnetically saturated. The upper limit X1 can be used as a threshold, after which the determining section can determine that the transformer 30 will be magnetically saturated before the transformer 30 is magnetically saturated. In other words, although the transformer 30 is not yet magnetically saturated at the time of detection of V (n), the upper limit can only be used as a threshold value after which the determining section can determine that the transformer 30 at a time after the above date will be magnetically saturated. Although the upper limit z. B. can be set to about 1.5, the upper limit is not limited to this value.

In addition, the determination section 51 in the case of V (n) ≤ X2 * V (n - 1), where X2 the lower limit is, that is, in case of 1 (high level) from the voltage detection section 70 (via the comparator 76 ), determine that the transformer 30 becomes magnetically saturated. The lower limit X2 can be used as a threshold, after which the determining section can determine that the transformer 30 will be magnetically saturated before the transformer 30 is magnetically saturated. Although the lower limit z. B. can be set to about 0.5, the lower limit is not limited to this value.

With the above configuration, even if the input voltage has abruptly changed (eg, abruptly increased or decreased), it can be determined that the transformer 30 will be magnetically saturated before the transformer 30 is magnetically saturated.

12 FIG. 11 is a timing chart showing an example of a control method by the power source apparatus. FIG 100 according to this embodiment, in the case where the input voltage abruptly increases. The upper part of the figure shows the input voltage VIN , and the lower part of the figure shows the duty cycle of the FET 11 , The horizontal axis represents the time. For reasons of clarity, the cycles go through T (1) . T (2) . T (3) and T (4 ). First, if it is assumed that the duty cycle in the cycle T (1) Dt (1) is, the turns FET 11 only in the period that Dt (1) corresponds, and the input voltage in the cycle T (1) is called VIN (1) accepted.

The control section 50 determines the duty cycle Dt (2) in the cycle T (2) based on the input VIN (1) in the cycle T (1) , The FET 11 turns on only in the period that Dt (2) corresponds, and the input voltage in the cycle T (2) is called VIN ( 2 ) accepted.

Because the ratio of the input voltage VIN (2) to the input voltage VIN (1) less than the upper limit X1 is, determines the control section 50 in the cycle T (3) based on the input voltage VIN (2) in the cycle T (2) the duty cycle Dt (3). Of the FET 11 turns on only in the period that Dt (3) corresponds, and the input voltage in the cycle T (3) is called VIN (3) accepted.

Because the ratio of the input voltage VIN (3) to the input voltage VIN (2) equal to or greater than the upper limit X1 is the control section 50 in the cycle T (4) the duty cycle Dt (4) less than the predetermined duty cycle (eg smaller than ΔD).

In the cycle T (4) , although the FET 11 only in the period corresponding to Dt ( 4 ) is switched on, since the duty cycle is made smaller, even if the input voltage VIN (4) in the cycle T (4) continues to increase, which can be the transformer 30 supplied magnetic energy to be reduced by the amount corresponding to the reduced level of the duty cycle, whereby the unbalanced state of the magnetic energy is suppressed and the transformer 30 can be prevented from magnetic saturation.

As described above, the control section controls 50 in the case that the ratio of the input voltage detected in the n-cycle to the im (n - 1) Cycle detected input voltage equal to or greater than the upper limit X1 is the ON / OFF operation of the FET 11 so that the ON period of the FET 11 becomes shorter than the ON period according to the required duty ratio.

If the ratio is equal to or greater than the upper limit, ie, V (n) ≥ X1 * V (n-1), the voltage (eg, the positive electrode voltage) in the ON period of the FET 11 to the transformer 30 is to be applied, increased and the excitation current at the positive electrode rise, whereby an imbalance between the magnetic energy at the positive electrode and the magnetic energy at the negative electrode (the magnetic energy of the positive electrode> the magnetic energy of the negative electrode) arises and a magnetic saturation can occur.

Therefore, as in 12 shown, the ON / OFF operation of FET 11 controlled so that the ON period of the FET 11 becomes shorter than the ON period based on the required duty ratio. Thus, it is possible to prevent the voltage (eg, the positive electrode voltage) occurring in the ON period of the FET 11 to the transformer 30 is applied, becomes too high and also possible to suppress the increase of the excitation current at the positive electrode, whereby the magnetic energy at the positive electrode and the magnetic energy at the negative electrode is brought into a balanced state and the transformer 30 can be protected from magnetic saturation.

13 FIG. 11 is a timing chart showing an example of a control method by the power source apparatus. FIG 100 according to this embodiment, in the case where the input voltage abruptly decreases. The upper part of the figure shows the input voltage VIN , and the lower part of the figure shows the duty cycle of the FET 11 , The horizontal axis represents the time. For reasons of clarity, the cycles go through T (11) . T (12) T (13) and T (14) shown. First, if it is assumed that the duty cycle in the cycle T (11 ) Dt (11) is, the turns FET 11 only in the period that Dt ( 11 ) and the input voltage in the cycle T (11) is called VIN (11) accepted.

The control section 50 determines the duty cycle Dt (12) in the cycle T (12) based on the input VIN (11) in the cycle T (11) , Of the FET 11 turns on only in the period that Dt (12) corresponds, and the input voltage in the cycle T (12) is called VIN (12) accepted.

Because the ratio of the input voltage VIN (12) to the input voltage VIN (11) greater than the lower limit X2 is, determines the control section 50 in the cycle T (13) the duty cycle Dt (13) based on the input VIN (12) in the cycle T (12) , The FET 11 turns on only in the period that Dt (13) corresponds, and the input voltage in the cycle T (13) is called VIN (13) accepted.

As the ratio of the input voltage VIN (13) to the input voltage VIN (12) equal to or less than the lower limit X2 is the control section 50 the duty ratio Dt ( 14 ) in cycle T (14) is greater than the predetermined duty cycle (eg greater than ΔD).

In the cycle T (14) although the FET 11 only in the period accordingly Dt (14) is on, as the duty cycle is made larger, even if the input voltage VIN (14) in the cycle T (14) continues to decrease, the transformer 30 supplied magnetic energy to be increased by the amount corresponding to the increased height of the duty cycle, whereby the unbalanced state of the magnetic energy is suppressed and the transformer 30 can be prevented from magnetic saturation.

As described above, the control section controls 50 in the case that the ratio of the input voltage detected in the n-cycle to the im (n - 1) Cycle detected input voltage equal to or less than the lower limit X2 is the ON / OFF operation of the FET 11 so that the ON period of the FET 11 becomes longer than the ON period based on the required duty ratio.

In the event that the ratio is equal to or less than the lower limit X2 is, ie in the case of V (n) ≤ X1 * V (n - 1), the voltage (eg, the positive electrode voltage) that is in the ON period of the FET 11 to the transformer 30 is to be applied, inadequate and the excitation current at the Positive electrode decreases, whereby an imbalance between the magnetic energy at the positive electrode and the magnetic energy at the negative electrode (the magnetic energy of the positive electrode <the magnetic energy of the negative electrode) is formed and it can come to a magnetic saturation.

Thus, as in 13 shown, the ON / OFF operation of the switching device FET 11 so controlled that the ON period of the FET 11 becomes longer than the ON period based on the required duty ratio. Thus, it is possible to prevent being connected to the transformer 30 voltage to be applied (eg, the positive electrode voltage) in the ON period of FET 11 is insufficient and also the decrease of the excitation current at the positive electrode is suppressed, whereby the magnetic energy at the positive electrode and the magnetic energy at the negative electrode is brought into a balanced state and the transformer 30 can be protected from magnetic saturation.

Although the time when the FET 11 from ON to OFF, in the examples in the and is set, the time is not limited to that time, but the time at which the FET 11 from OUT switch to ON, can also be set.

The comparator 75 outputs one of the two binary values, depending on whether the ratio of the input voltage detected in the n-cycle to that in the n-cycle (n - 1) Cycle detected input voltage equal to or greater than the upper limit X1 is. In addition, there is the comparator 76 one of the two binary values, depending on whether the ratio of the input voltage detected in the n-cycle to that in the n-cycle (n - 1) Cycle detected input voltage equal to or less than the lower limit X2 is.

The photocoupler 78 transmits the binary values from the comparators 75 and 76 were issued. The input side can through the photocoupler 78 be electrically isolated from the output side.

Because the photocoupler 78 and the comparators 75 and 76 can be used, the change of the input voltage via a digital signal to the control section 50 (the determination section 51 ) be transmitted. In general, in the case that the change in the input voltage is transmitted via an analog signal without conversion, a separate isolation transformer or the like is required to provide electrical isolation between the primary side (eg, the circuit to which the input voltage is applied) is) of the electricity supplier and the control section to secure, which is expensive. By using the photocoupler 78 and the comparators 75 and 76 may be the change of the input voltage via the electrically isolated digital signal to the control section 50 (the determining part 51 ), whereby this configuration can be realized inexpensively.

The first voltage divider circuit 71 is about the connections A and B on the input side to which the input voltage is applied, and has the plurality of resistors 711 and 712 connected in series. The second voltage divider circuit 72 is connected via terminals A and B and has the resistors 711 and 721 and the capacitor 722 connected in series.

The comparator 75 (Voltage detecting section) detects the input voltage in the first period (eg, the n-cycle) from the first voltage divider circuit 71 , Specifically, if it is assumed that the voltage across the first voltage divider circuit 71 is to be applied, VIN (n) is and that the voltage caused by the multiplicity of resistors 711 and 712 the first voltage divider circuit 71 is to be shared, V (n) is captured by the comparator 75 the voltage V (n). Also the comparator 76 works in a similar way.

The multiplication circuit 73 (Voltage detecting section) detects the input voltage in the second period (eg, the (n-1) cycle) from the second voltage divider circuit 72 , More specifically, the multiplication circuit 73 the voltage at the junction of the resistor 721 and the capacitor 722 capture. Since the time constant after which the capacitor 722 about the resistance 721 is loaded or unloaded, is almost equal to the given cycle (ie the time from (n - 1) Cycle to n cycle), the multiplication circuit 73 the voltage V (n - 1) from the second voltage divider circuit 72 at the time when the voltage V (n) from the first voltage divider circuit 71 is detected. Also the multiplication circuit 74 works similarly.

Although the voltage detection section 70 is configured to be in the above-mentioned embodiment on the input side via the terminals A and B is connected, the configuration of the voltage detection section is not limited to this configuration. For example, such a voltage detection section on the secondary side of the transformer 30 be provided.

14 FIG. 16 is an explanatory view showing another example of a circuit configuration of the power source apparatus. FIG 100 according to this embodiment shows. This example is different from the one in 1 example shown thereby, that a tension detection section 170 over one end side of the secondary winding 32 of the transformer 30 and a predetermined ground is connected. In particular, the voltage detection section 170 via the connection point of one end side of the secondary winding of the transformer 30 and the cathode of the diode 42 and the ground plane on the secondary side of the transformer 30 connected. Assuming that the winding ratio of the primary winding to the secondary winding is 1: N, although the voltage VIN to the voltage detection section 70 is applied, the voltage (N * VIN) is applied to the voltage detection section 170 created. Also in this case, the voltage divided by the plurality of resistors of the first voltage divider circuit 71 , also called V (n).

15 FIG. 16 is an explanatory view showing an example of a circuit configuration of the voltage detection section. FIG 170 according to this embodiment shows. The voltage detection section 170 is different from the one in 2 illustrated voltage detection section 70 in that the voltage detection section 170 not with the photocoupler 78 is provided. Since the voltage detection section 170 on the secondary side of the transformer 30 is provided, it is therefore not necessary, the primary side of the secondary side of the transformer 30 to isolate. With this configuration, component costs can be further reduced. Because the function and operation of the voltage detection section 170 those of 2 shown voltage detection section 70 is similar, accounts for the descriptions of it.

In in the event that the comparator 75 or 76 0 outputs, outputs the NAND circuit 77 1 (high level) to the control section 50 out.

In the event that the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or greater than the upper limit X1 or that the ratio of the voltage detected in the n-cycle V (n) to the im (n - 1) Cycle detected voltage V (n - 1) equal to or less than the lower limit X2 is, the control section can 50 1 (high level) from the voltage detection section 70 capture.

16 FIG. 12 is a flowchart illustrating an example of a processing process of the method for controlling the power source apparatus. FIG 100 according to this embodiment shows. The control section 50 turn that on FET 11 and the FET 12 in the given cycle T (at S11 ) ON OFF. The control section 50 determines if the FET 11 in the ON period or not (at S12 ), and then when the FET 11 not in the ON period (NO at S12 ), sets the control section 50 the process of step S12 continued.

Is the FET located? 11 in the ON period (YES at S12 ), the control section detects 50 the input voltages in the n-cycle (eg in the current cycle) and in the (n - 1) Cycle (in the previous cycle) (at S13 ) were obtained. The detected input voltages are the voltages (which correspond to the input voltage) respectively divided by the first voltage divider circuit 71 and the second voltage divider circuit 72 to be obtained.

The control section 50 determines whether the ratio of the input voltage detected in the n-cycle to that in the n-cycle (n - 1) Cycle detected input voltage equal to or greater than the upper limit X1 (at S14). In the event that the ratio is equal to or greater than the upper limit X1 (Yes at S14 ) makes the control section 50 the duty cycle of the FET 11 in the (n + 1) Cycle less than the required duty cycle (at S15 ) and performs the step process described later S19 by.

In the event that the ratio is less than the upper limit X1 (NO at S14 ), the control section determines 50 Whether the ratio of the input voltage detected in the n-cycle to the input voltage detected in the (n-1) cycle is equal to or less than the lower limit X2 (at S16 ). In the event that the ratio is equal to or less than the lower limit X2 (Yes at S16 ) makes the control section 50 the duty cycle of the FET 11 in the (n + 1) Cycle greater than the required duty cycle (at S 17 ) and performs the step process described later S19 by.

In the event that the ratio is greater than the lower limit X2 (NO at S16), the control section continues 50 the duty cycle of the FET 11 in the cycle (n + 1) to a predetermined value (a value which is finely adjusted due to the required duty ratio) (at S18 ). The control section 50 determines if the processing is terminated (at S19 ), and then, if processing does not finish (NO at S19 ), the control section repeats 50 the processing at step P 11 and the subsequent steps. In the event that the processing is terminated (YES at S19 ), the control section stops 50 the switching of the FET 11 and of FET 12 and thus stops the processing.

The method of controlling the power source device 100 According to this embodiment, on a computer as a method of controlling the power source device 50 be achieved, for example by configuring the control section 50 using a CPU (processor), a RAM (memory), etc., by loading a Computer program that the in 16 specified corresponding processing steps specified in the RAM (memory) and by executing the computer program on the CPU (processor).

In this embodiment, in each cycle in the ON state of the FET 11 measured voltage is a current value or an average value. The time at which the voltage is detected may be the central point in time of the ON period of the FET 11 his. In addition, the average value of the voltages detected immediately after the ON operation and immediately before the OFF operation can also be detected.

The switching device is not limited to a MOSFET but may be a device such as an IGBT (Insulated Gate Bipolar Transistor). In the case where the switching device is a MOSFET as in this embodiment, there is a correspondingly built-in substrate diode between the drain and the source. In addition, when using a bipolar transistor as a switching device diodes can only be connected in parallel in parallel between the collector and the emitter of the transistor.

Although the configuration of such a DC / DC converter as in 1 The configuration of the DC / DC converter is not the same as that described in FIG 1 shown configuration, but the configuration may be merely a configuration in which a switching device is connected in series with the primary winding of a transformer and a magnetic reset of the transformer is performed.

It is believed that the embodiments and examples disclosed above are merely examples in all respects and are not to be considered as limiting. The scope of the present invention is defined not by the above-mentioned embodiments and examples, but by the appended claims, and includes all changes and additions within the meanings and ranges equivalent to the claims.

LIST OF REFERENCE NUMBERS

11, 12

FET

21, 22, 23

capacitor

30

transformer

31

primary

32

secondary winding

41, 42

diode

50

control section

51

determining section

61

inductor

70, 170

Voltage detection section

71

first voltage divider circuit

72

second voltage divider circuit

73, 74

multiplication circuit

75, 76

comparator

77

NAND circuit

78

photocoupler

711, 712, 712, 721

resistance

722

capacitor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2017045257 [0002]
• JP 2008199878 [0005]

Claims (8)

A power source device comprising a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series circuit of a second switching device and a second capacitor, which are connected in parallel with the primary winding; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required duty ratio, wherein an input voltage is applied to the primary winding of the transformer, the current source device further comprising: a voltage detecting section for detecting the input voltage in the ON period of the first switching device and a determination section for determining whether the transformer is magnetically saturated based on the input voltage detected in a first period in which the first switching device is turned on and the input voltage that is in a second period before the first period by a predetermined period Cycle was recorded, where the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section. The power source device according to Claim 1 wherein, in the case that the ratio of the input voltage detected in the first period to the input voltage detected in the second period is equal to or greater than a predetermined upper limit value, or equal to or smaller than a predetermined lower limit value, the determining section determines that the transformer will be magnetically saturated. The power source device according to Claim 2 wherein, in the case where the ratio is equal to or greater than the upper limit value, the control section controls the ON / OFF operation of the first switching device so that the ON period of the first switching device is shorter than the duty cycle based on the required duty cycle Period becomes. The power source device according to Claim 2 or 3 wherein, in the case where the ratio is equal to or smaller than the lower limit value, the control section controls the ON / OFF operation of the first switching device such that the ON period of the first switching device is longer than the duty cycle based on the required duty cycle. Period becomes. The power source device according to any one of Claims 2 to 4 further comprising: a binary output section that outputs one of the binary values depending on whether the ratio is equal to or greater than the upper limit value or the ratio is equal to or smaller than the lower limit value, and an insulating transmission device for transmitting the binary value from the binary output section, wherein the determining section determines whether the transformer is magnetically saturated depending on the power of the insulating transmission device. The power source device according to any one of Claims 1 to 5 , further comprising: a first voltage divider circuit connected across input terminals to which the input voltage is applied and having a plurality of resistors connected in series, and a second voltage divider circuit connected across the input terminals and having resistors and one in The voltage detecting section detects: the input voltage in the first period from the first voltage divider circuit and also detects: the input voltage in the second period from the second divider circuit. The power source device according to any one of Claims 1 to 5 , further comprising: a first voltage divider circuit connected across one end side of the secondary winding of the transformer and a predetermined ground and having a plurality of resistors connected in series, and a second voltage divider circuit connected across the one end side and the ground and resistors and one The voltage detecting section detects: the input voltage in the first period from the first voltage dividing circuit, and also detects: the input voltage in the second period from the second clamping divider circuit. A method of controlling a power source device, comprising: a transformer; a first switching device connected in series with the primary winding of the transformer; a first capacitor connected in parallel with the first switching device; a series connection of a second switching device and a second capacitor, which are connected in parallel to the primary winding; and a control section for controlling the ON / OFF operation of the first switching device and the second switching device based on a required one Duty ratio, wherein an input voltage is applied to the primary winding of the transformer, wherein a voltage detecting portion detects the input voltage in the ON period of the first switching device, a determining section determines whether the transformer is magnetically saturated based on the input voltage, which in a first period, in which the first switching device is turned on, and the input voltage detected in a second period before the first period by a predetermined cycle, and the control section controls the ON / OFF operation of the first switching device based on the determination result of the determination section.

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