JP5696898B2 - Power conversion device and power supply system - Google Patents

Description

  The present invention relates to a power conversion device including at least a switching element and a transformer, and a power supply system including the power conversion device.

  Conventionally, an example of a technique related to a demagnetization prevention circuit that aims to prevent a demagnetization phenomenon by a circuit control technique without requiring a gap in a transformer has been disclosed (see, for example, Patent Document 1). When the positive DC component resulting from the characteristics of the conversion elements (S1 to S4) is generated in the output of the inverter circuit, the demagnetization prevention circuit converts the conversion element (S1) every anti-cycle in which the AC output of the inverter circuit becomes negative. The time width of the pulse signal for activating S4) is increased according to the magnitude of the positive DC component (see paragraph 0033 of the same document).

  In addition, an example of a technique related to a demagnetization prevention circuit of a high-frequency transformer for the purpose of suppressing a saturation phenomenon due to demagnetization with a simple and inexpensive configuration is disclosed (for example, see Patent Document 2). The demagnetization prevention circuit of this high-frequency transformer is a Td creation circuit (31) including a CR circuit and an AND circuit (34) composed of a variable resistor (32) and a capacitor (33). In the Td creation circuit (31), since the CR circuit works as a delay time element with respect to the gate signal, the delay time (Td1) at which the U phase and the Y phase are turned on, the V phase that generates a negative voltage, and the X phase By adjusting separately the delay time (Td2) of the phase turn-on timing, the difference between the positive and negative on-time widths (Δt) is adjusted in advance (see paragraphs 0020-0022 of the same document). ).

Japanese Patent Laid-Open No. 06-098559 Japanese Patent No. 3501548

  However, when the technique of Patent Document 1 is applied and a negative DC component due to the characteristics of the conversion elements (S1 to S4) is generated, the bias of the transformer cannot be suppressed. That is, in the circuit configuration shown in FIG. 1 of Patent Document 1, the time width of the pulse signal for operating the conversion elements (S1 to S4) cannot be increased according to the magnitude of the negative DC component. Although it is possible to deal with the positive and negative DC components caused by the characteristics of the conversion elements (S1 to S4), respectively, it is necessary to provide a demagnetization prevention circuit corresponding to each of the positive and negative DC components. become.

  Moreover, in the technique of patent document 2, the electric current (I) which flows through the secondary side circuit of a transformer (4) is detected by the 1st current sensor (10) (refer FIG. 4 of patent document 2). Thus, when using the DC deviation signal from one current sensor, it can be suppressed in terms of cost and physique. On the other hand, it is necessary to separate the current sensor signals in cooperation with the pulse drive timing, which easily leads to a complicated circuit configuration. In general, the current tends to be more complicated in the measurement circuit than the voltage. Therefore, if the technique of Patent Document 2 is applied to an insulation type power converter, it is necessary to insulate and measure the current, and thus the current measurement tends to be complicated.

  The present invention has been made in view of these points, and can cope with positive and negative DC components while suppressing cost, and suppresses the bias of the transformer without adding a circuit element to the current flow path ( It is an object of the present invention to provide a power conversion device and a power supply system that can include a reduction.

The invention according to claim 1, which has been made to solve the above problem, includes at least a switching element that performs switching based on an operation signal, and a transformer that electrically connects the switching element to a primary terminal. , A plurality of the switching elements configured by any one of a full bridge, a half bridge, a push-pull, a plurality of single forward systems, and a plurality of flyback systems, and AC power output from the secondary terminal of the transformer Two or more rectifying units, an integrating unit for outputting a power time product obtained by individually and temporally integrating DC power rectified by the two or more rectifying units, and the two or more power time products Based on the deviation amount detected by the deviation amount detection unit and the deviation amount detection unit that detects the deviation amount according to There and an operation signal controller that performs control to change the operation signal to be zero, the operation signal controller, for the duty ratio indicating the ratio of the period for turning on / off the switching elements, a plurality of When the duty ratio applied to the switching element serving as a reference among the switching elements reaches a predetermined ratio value, the duty ratio applied to one of the switching elements included in the plurality of switching elements is changed. To do.

According to this configuration, the integration unit individually determines the power time product of each DC power rectified for each rectification unit, and the deviation amount detection unit detects the deviation amount (that is, the difference amount) of the power time product. Based on the deviation amount thus detected, the operation signal control unit performs control to change the operation signal so that the deviation amount becomes zero. When the deviation amount becomes zero, the power time product of the DC power becomes equal, and the bias of the transformer can be suppressed (including reduction). By making each rectifier correspond to positive and negative DC power, it is possible to suppress the bias of the transformer regardless of positive or negative. Since it is only necessary to provide a rectifying unit corresponding to the positive / negative of the AC power output from the secondary terminal of the transformer without adding a circuit element to the current flow path, the cost of the entire apparatus can be suppressed.
Moreover, what is necessary is just to transmit an operation signal to a switching element by changing the duty ratio of an operation signal so that the deviation | shift amount of an electric power time product may become zero. Since the existing control method can be used, the cost of the entire apparatus can be suppressed.
Further, when the duty ratio included in the operation signal to be output reaches a predetermined ratio value, the duty ratio applied to one switching element included in the plurality of switching elements is changed. Since the duty ratio is changed within a range that does not exceed the predetermined ratio value, the plurality of switching elements can be stably operated, and the bias of the transformer can be suppressed.

The “switching element” includes two switching elements connected in series by upper and lower arms, and any semiconductor element capable of switching operation can be applied. For example, an FET (specifically, MOSFET, JFET, MESFET, etc.), IGBT, GTO, power transistor, or the like is applicable. “Power” includes power by voltage control and power by current control. Therefore, the “power time product” includes a voltage time product and a current time product. The “rectifier unit” is configured by a rectifier circuit, a rectifier, or the like, and includes half-wave rectification and full-wave rectification. The “operation signal” is arbitrary regardless of the type as long as it is a signal capable of switching the switching element. An on signal for turning on the switching element and an off signal for turning off the switching element are included. For example, in addition to pulse signals, analog signals and digital signals are applicable. The “predetermined ratio value” includes a controllable maximum value and minimum value related to the duty ratio, and an appropriate numerical value according to the configuration of the power conversion device (for example, the type of switching element, voltage to be controlled, current, etc.). It is desirable to set. Considering that the switching operation of the switching element becomes unstable, the range in which the duty ratio can be changed is limited.

The invention according to claim 2 is a power conversion device including at least a switching element that performs switching based on an operation signal, and a transformer that electrically connects the switching element to a primary terminal. A plurality of switching elements configured by any one of a pull, a plurality of single forward systems, and a plurality of flyback systems, and two or more rectifiers that rectify AC power output from a secondary terminal of the transformer; An integration unit for outputting a power time product obtained by integrating DC power rectified by the two or more rectification units individually and over time, and a deviation amount for detecting a deviation amount of the two or more power time products Based on the deviation amount detected by the detection unit and the deviation amount detection unit, the operation signal is set so that the deviation amount becomes zero. An operation signal control unit that performs control to change, the operation signal control unit of the two switching elements that can be short-circuited when simultaneously turned on among the plurality of switching elements The length of the first dead time from changing the state to changing the state of the other switching element is changed .

According to this configuration, the integration unit individually determines the power time product of each DC power rectified for each rectification unit, and the deviation amount detection unit detects the deviation amount (that is, the difference amount) of the power time product. Based on the deviation amount thus detected, the operation signal control unit performs control to change the operation signal so that the deviation amount becomes zero. When the deviation amount becomes zero, the power time product of the DC power becomes equal, and the bias of the transformer can be suppressed (including reduction). By making each rectifier correspond to positive and negative DC power, it is possible to suppress the bias of the transformer regardless of positive or negative. Since it is only necessary to provide a rectifying unit corresponding to the positive / negative of the AC power output from the secondary terminal of the transformer without adding a circuit element to the current flow path, the cost of the entire apparatus can be suppressed.
Moreover, what is necessary is just to transmit an operation signal to a switching element by changing the duty ratio of an operation signal so that the deviation | shift amount of an electric power time product may become zero. Since the existing control method can be used, the cost of the entire apparatus can be suppressed.
Further, the operation signal may be transmitted to the switching element by changing the length of the first dead time applied to the two switching elements that can be short-circuited when they are simultaneously turned on so that the deviation amount of the power time product becomes zero. . Since the existing control method can be used, the cost of the entire apparatus can be suppressed.

The invention according to claim 3 is characterized in that the operation signal control section changes a duty ratio indicating a ratio of a period during which the switching element is turned on / off .
According to this configuration , the operation signal may be transmitted to the switching element by changing the duty ratio of the operation signal so that the deviation amount of the power time product becomes zero. Since the existing control method can be used, the cost of the entire apparatus can be suppressed.

According to a fourth aspect of the present invention, there are two sets of the two switching elements that can be short-circuited when simultaneously turned on among the plurality of switching elements, and the operation signal control unit is one of the two sets. When the length of the first dead time applied to a set reaches a predetermined length value , the two switching elements applied to the other set of the two sets are changed in the state of one of the switching elements, and then the other The length of the second dead time until the state of the switching element is changed is changed .
According to this configuration, when the first dead time included in the operation signal to be output reaches a predetermined length value, the second dead time is changed in addition to the first dead time. Since the first dead time and the second dead time applied to the plurality of switching elements are changed within a range not exceeding the predetermined length value, the plurality of switching elements can be stably operated, and the bias of the transformer can be suppressed. .

  The “two switching elements to be operated in cooperation” mean switching elements connected in series. The “predetermined length value” includes a maximum value and a minimum value that can be controlled with respect to the length of the dead time, and is appropriate depending on the configuration of the power conversion device (for example, the type of switching element, the voltage or current to be controlled, etc.). It is desirable to set a numerical value. Considering that the switching operation of the switching element becomes unstable, the range in which the length of the dead time can be changed is limited.

According to a fifth aspect of the present invention, in the power supply system, the power conversion device according to any one of the first to fourth aspects is provided, and the connection unit that electrically connects the output terminals of the two or more rectification units And a filter unit for reducing the AC component of the DC power in the connection unit. According to this configuration, it is possible to provide a power supply system that can cope with positive and negative DC components while suppressing cost and can suppress the bias of the transformer without adding a circuit element to the current flow path.

It is a schematic diagram which shows the 1st structural example of the power supply system containing a power converter device. It is a flowchart which shows an example of an operation signal process. It is a time chart which shows the 1st control example which suppresses the magnetic bias of a transformer. It is a time chart which shows the 2nd control example which suppresses the bias magnetism of a transformer. It is a time chart which shows the 3rd control example which suppresses the bias magnetism of a transformer. It is a time chart which shows the 4th control example which suppresses the magnetic bias of a transformer. It is a time chart which shows the 5th control example which suppresses the bias magnetism of a transformer. It is a schematic diagram which shows the 2nd structural example of the power supply system containing a power converter device. It is a schematic diagram which shows the other structural example of a switching part.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Unless otherwise specified, “connect” means electrical connection. Each figure shows elements necessary for explaining the present invention, and does not show all actual elements. When referring to directions such as up, down, left and right, the description in the drawings is used as a reference. The continuous code is simply expressed using the symbol “˜”. For example, “switching elements Q1 to Q4” means “switching elements Q1, Q2, Q3, Q4”.

[Embodiment 1]
The first embodiment is an example of suppressing the bias of the transformer based on the electric power by voltage control, and will be described with reference to FIGS. First, FIG. 1 is a schematic diagram illustrating a first configuration example of a power supply system including a power conversion device. A circuit included in the schematic diagram shows a main part necessary for realizing the present invention (the same applies to FIG. 8 described later).

  A power supply system 10 shown in FIG. 1 is a so-called “DC-DC converter”, and uses a DC voltage (for example, 300 [V]) supplied from a power source Edc (for example, a battery or a fuel cell) as a target voltage (for example, 300 [V]). For example, it has a function of converting to 12 [V] or the like and outputting to the output device 30. The power supply system 10 includes a power conversion device 20, and includes a choke coil L10, capacitors C10 and C11, diodes D11 and D12, a filter unit 12, and the like.

  For example, a battery or a fuel cell is used as the power source Edc that supplies a DC voltage (corresponding to “DC power”). The plus terminal and minus terminal of the power source Edc are connected to the power converter 20 via the choke coil L10 and the capacitor C10. The choke coil L10 functions as an input filter. Capacitor C10 repeatedly charges and discharges the DC voltage. Before describing the remaining diodes D11 and D12, the capacitor C11, the filter unit 12, and the like, the configuration and operation of the power conversion device 20 will be described below for convenience of description.

  The power conversion device 20 is a so-called “inverter” and has a function of converting a DC voltage supplied from the power source Edc into an AC voltage (corresponding to “AC power”) and outputting the AC voltage. The power conversion device 20 includes switching elements Q1 to Q4, diodes D1 to D4, a transformer Tr1, diodes D21 and D22, an operation signal control unit 21, integration units 22 and 23, a deviation amount detection unit 24, and the like.

  The switching elements Q1 to Q4 are driven on / off in accordance with operation signals individually transmitted from an operation signal control unit 21 described later. For example, N-channel MOSFETs are used for the switching elements Q1 to Q4 of this embodiment. Switching element Q1 and switching element Q3 are connected in series by upper and lower arms, and switching element Q2 and switching element Q4 are connected in series by upper and lower arms. The group of switching elements Q1, Q3 and the group of switching elements Q2, Q4 are connected in parallel. A connection point between the switching element Q1 (source terminal) and the switching element Q3 (drain terminal) is connected to a primary terminal (one end side) of the transformer Tr1. Similarly, the connection point between the switching element Q2 (source terminal) and the switching element Q4 (drain terminal) is connected to the primary terminal (the other end side) of the transformer Tr1.

  The diodes D1 to D4 may be connected in parallel corresponding to the switching elements Q1 to Q4, respectively, and function as a freewheel diode. Therefore, it may be incorporated in the switching elements Q1 to Q4 or may be externally attached.

  As the transformer Tr1, for example, a transformer having at least three terminals as secondary terminals in addition to the primary terminal and outputting a two-phase voltage with reference to the potential of the intermediate terminal (intermediate tap) is used. With reference to the potential of the intermediate terminal, a positive secondary voltage Vs1 is output to the secondary terminal on one side, and a negative secondary voltage Vs2 is output to the secondary terminal on the other side. When viewing each voltage in absolute value, | Vs1 | = | Vs2 | is desirable, but | Vs1 | ≠ | Vs2 | The secondary voltages Vs1 and Vs2 correspond to “AC power”, respectively.

  The diode D22 and the integrating unit 23 are connected in series between the secondary terminal on one side where the secondary voltage Vs1 is generated and the minus terminal of the deviation amount detecting unit 24. The diode D21 and the integrating unit 22 are connected in series between the other secondary terminal where the secondary voltage Vs2 is generated and the plus terminal of the deviation amount detecting unit 24.

  The integrating units 22 and 23 have a function of integrating the DC voltages rectified by the diodes D21 and D22, respectively, and outputting the integrated values individually. This integrated value is a value that changes in accordance with the time during which the secondary voltages Vs1 and Vs2 are applied, and is hereinafter referred to as a “voltage-time product”. The integrating units 22 and 23 of this embodiment are each configured with a resistor and a capacitor in order to keep costs low. In this configuration, it is desirable to adjust the resistance value and the capacitance value so as to increase the time constant. As shown, one end of the capacitor is connected to the resistor, and the other end is connected to the ground N. Note that the potential of the ground N is not necessarily 0 [V].

  The deviation amount detector 24 detects and outputs a deviation amount ΔTP (that is, a difference value) between the voltage time product based on the secondary voltage Vs1 and the voltage time product based on the secondary voltage Vs2. For example, a differential amplifier (for example, a differential amplifier circuit using an operational amplifier) is used for the deviation amount detection unit 24 of this embodiment. Specifically, a voltage time product based on the secondary voltage Vs1 is input to the minus terminal, and a voltage time product based on the secondary voltage Vs2 is input to the plus terminal. When the amplification factor is assumed to be “1”, the difference value (Vs2−Vs1) is output as the deviation amount ΔTP.

The operation signal control unit 21 includes a drive circuit 21a, a control circuit 21b, and the like. The operation signal control unit 21 performs control to change the operation signal based on the above-described deviation amount ΔTP so that the deviation amount ΔTP becomes zero. The operation signal is a signal that is individually transmitted to the switching elements Q1 to Q4 to be turned on / off. For example, a pulse signal is used as the operation signal of this embodiment. The control circuit 21 b governs the overall operation of the power conversion device 20. In realizing the present invention, the control circuit 21b outputs a command signal Vc ^* for driving the drive circuit 21a so that the deviation amount ΔTP transmitted from the deviation amount detector 24 becomes zero. The drive circuit 21a generates the above-described operation signal (pulse signal) based on the command signal Vc ^* transmitted from the control circuit 21b and outputs it individually to the switching elements Q1 to Q4.

  The power conversion device 20 configured as described above outputs two-phase secondary voltages Vs1 and Vs2 with reference to the potential of the intermediate terminal from the transformer Tr1. In the power supply system 10, the intermediate terminal of the transformer Tr1 is connected to the ground N. In order to perform two-phase full-wave rectification, the secondary voltage Vs1 is rectified by the diode D11, the secondary voltage Vs2 is rectified by the diode D12, and is connected (directly connected) at the connection portion J after both rectifications. The diodes D11 and D12 each correspond to a “rectifying unit”. Since the rectified DC voltage is merely synthesized at the connection portion J, it is smoothed by the capacitor C11, and non-DC components (for example, high-frequency components and pulsations) are removed by the filter portion 12. The filter unit 12 includes a reactor L12 (coil), a capacitor C12, and the like. The stabilized DC voltage is output to the output device 30. Any device that requires a predetermined DC voltage can be applied to the output device 30.

A control example for suppressing (including reducing) the magnetic bias when the magnetic bias occurs in the transformer Tr1 included in the power supply system 10 described above will be described with reference to FIG. FIG. 2 is a flowchart showing an example of the operation signal processing. This operation signal process is one of the control processes performed by the control circuit 21b shown in FIG. 1, and is repeatedly executed while the control circuit 21b operates. Since the control circuit 21b outputs the command signal Vc ^* to perform switching of the switching elements Q1 to Q4, it is natural to determine which switching element is currently turned on / off, the cycle of each switching element, and the like. I know.

  In the operation signal processing shown in FIG. 2, when the timing for inputting the deviation amount ΔTP has not been reached (NO in step S10), the operation signal processing is returned. On the other hand, when the timing for inputting the deviation amount ΔTP is reached (YES in step S10), the deviation amount ΔTP is inputted from the deviation amount detection unit 24 [step S11]. The “timing to input the deviation amount ΔTP” can be arbitrarily set, and corresponds to, for example, one cycle of a specific switching element among the switching elements Q1 to Q4.

  If the deviation amount ΔTP input in step S11 is zero (YES in step S12), no bias is generated in the transformer Tr1, and the operation signal processing is returned. On the other hand, if the input deviation amount ΔTP is not zero (NO in step S12), the operation signal is changed so that the deviation amount ΔTP becomes zero [step S13]. Specifically, for one switching element, (a) the length of the dead time between the switching elements is changed, or (b) the duty ratio of the pulse signal is changed. Specific examples of these changes will be described in operation signal control examples 1 to 4 described later (see FIGS. 3 to 6).

  In the case where the operation signal is changed in step S13, if the change in the operation signal does not exceed the limit value (NO in step S14), the operation signal processing is returned. The “limit value” on the flowchart corresponds to the “predetermined length value” for the length of the dead time, and corresponds to the “predetermined ratio value” for the duty ratio of the pulse signal. For the predetermined length value and the predetermined ratio value, appropriate numerical values for the power conversion device 20 are set.

  On the other hand, if the change in the operation signal exceeds the limit value (YES in step S14), the operation signal is changed for other switching elements in addition to the target switching element in step S13 [step S15. ], The operation signal processing is returned. That is, in step S15, the deviation amount ΔTP is set to zero by changing the operation signal for two or more switching elements among the switching elements Q1 to Q4.

  The “case where the change in the operation signal exceeds the limit value” will be described by taking the switching elements Q1, Q3 connected in series as an example. If the switching elements Q1 and Q3 are simultaneously turned on, the power source Edc is short-circuited, and thus must be avoided. Therefore, the case where the switching elements Q1 and Q3 are simultaneously turned on by changing the length of the dead time and the duty ratio corresponds to “when the change in the operation signal exceeds the limit value”. Further, even when the operation signal is transmitted from the operation signal control unit 21 to the switching elements Q1 to Q4, there is a considerable time lag until the on / off state of the switching element that has received the signal actually changes. . The case where the switching elements Q1 and Q3 are simultaneously turned on with this time lag also corresponds to “when the change in the operation signal exceeds the limit value”. These restrictions also apply to switching elements Q2 and Q4 connected in series as well.

  Operation signal control examples 1 to 5 for executing the operation signal processing shown in FIG. 2 and changing the operation signals transmitted to the switching elements Q1 to Q4 to suppress the bias of the transformer Tr1 are shown in FIGS. Will be described with reference to FIG. In order to simplify the explanation, in the operation signal control examples 1 to 5, the control based on the cycle of the switching element Q1 will be described. In FIG. 3 to FIG. 7, the voltage time product VT is indicated by hatched hatching in order to distinguish it from the pulse signal.

(Operation signal control example 1)
The operation signal control example 1 is an example of changing the length of the dead time and the duty ratio applied to the switching element Q1, and will be described with reference to FIG. FIG. 3 shows changes with time of the switching elements Q1, Q3, Q2, Q4 and the secondary voltages Vs1, Vs2 in order from the top (the same applies to FIGS. 4 to 7). However, the voltage-time product VT is shown to show the integrated value in each cycle, and does not show a change with time.

  One cycle of the switching element Q1 illustrated in FIG. 3 is a cycle Cy11 (a period from time t11 to time t16), a cycle Cy12 (a period from time t16 to time t1d), and a cycle Cy13 (a period after time t1d). Control is performed so that a bias magnetism occurs in the transformer Tr1 at the cycle Cy11 and the bias magnetism is suppressed after the cycle Cy12.

  In the cycle Cy11, since the switching elements Q1 and Q4 are simultaneously turned on from time t11 to time t12, the secondary voltage Vs1 is generated and the voltage time product VT1 is integrated. As shown in FIG. 1, since the secondary voltage Vs1 is input to the minus terminal of the deviation amount detection unit 24, the voltage time product VT1 is shown as a negative value in FIG. 3 (the same applies to FIGS. 4 to 7). On the other hand, since switching elements Q2 and Q3 are simultaneously turned on from time t13 to time t14, secondary voltage Vs2 is generated and voltage time product VT2 is integrated. The control circuit 21b inputs the deviation amount ΔTP (= | VT2 | − | VT1 |) at the timing after time t15 when the switching element Q3 is turned off (YES in step S10 in FIG. 2), and the deviation amount ΔTP is not zero. Therefore, the length of the dead time and the duty ratio are changed (steps S11 to S13 in FIG. 2).

  First, an example in which the length of the dead time is changed will be described. The switching elements Q1 and Q3 having the cycle Cy11 had a dead time Dt11 (a period from time t10 to time t11). Since the control circuit 21b sets the deviation amount ΔTP to zero, the dead time Dt12 (Dt12 <Dt11; the period from the time t15 to the time t16, or the time t1c after the time t15 when the switching element Q3 is turned off (period Cy12 or later). Until the time t1d). As the length of the dead time is changed, as a result, one cycle of the switching element Q1 becomes “Cy11 <Cy12, Cy13,.

  By shortening the length of the dead time from Dt11 to Dt12, the timing at which the switching element Q1 is turned on is advanced from time t17 to time t16 (see arrow D1). Thus, in the cycle Cy12, the switching elements Q1 and Q4 are simultaneously turned on from time t16 to time t18 to generate the secondary voltage Vs1, and the voltage time product VT2 is integrated. On the other hand, switching elements Q2 and Q3 are simultaneously turned on from time t16 to time t18 to generate secondary voltage Vs2, and voltage time product VT2 is also accumulated. The same applies to the cycle Cy13 and thereafter. In this way, the voltage-time products applied to the secondary voltages Vs1, Vs2 become equal, so that it is possible to suppress the occurrence of magnetic bias in the transformer Tr1. From the viewpoint of shortening the length of the dead time, delaying the timing at time t19 when the switching element Q1 is turned off is meaningless because the switching element Q4 is turned off.

  Next, an example in which the duty ratio is changed will be described. As described above, it can be seen that the deviation amount ΔTP is not zero at time t15, and the transformer Tr1 is biased. Therefore, the duty ratio of the switching element Q1 is changed after the cycle Cy12. In the cycle Cy11, the duty ratio is Dr11, but in the cycle Cy12 and later, the timing for turning on the switching element Q1 is advanced to control the pulse signal with the duty ratio Dr12 (Dr11 <Dr12). Therefore, in the same way as the control for changing the length of the dead time described above, the control for changing the duty ratio can also suppress the occurrence of bias in the transformer Tr1 after the cycle Cy12.

(Operation signal control example 2)
The operation signal control example 2 is an example of changing the length of the dead time and the duty ratio applied to the switching element Q3 connected in series with the switching element Q1, and will be described with reference to FIG. One cycle of the switching element Q1 shown in FIG. 4 is a cycle Cy21 (a period from time t20 to time t26), a cycle Cy22 (a period from time t26 to time t2d), and a cycle Cy23 (a period after time t2d). Control is performed so that a bias magnetism is generated in the transformer Tr1 in the cycle Cy21 and the bias magnetism is suppressed after the cycle Cy22.

  In the cycle Cy21, since the switching elements Q1 and Q4 are simultaneously turned on from time t20 to time t21, the secondary voltage Vs1 is generated and the voltage time product VT3 is integrated. On the other hand, since switching elements Q2 and Q3 are simultaneously turned on from time t23 to time t24, secondary voltage Vs2 is generated and voltage time product VT4 is integrated. The control circuit 21b inputs the deviation amount ΔTP (= | VT4 | − | VT3 |) at a timing after time t25 when the switching element Q3 is turned off (YES in step S10 in FIG. 2), and the deviation amount ΔTP is not zero. Therefore, the length of the dead time and the duty ratio are changed (steps S11 to S13 in FIG. 2).

  First, an example in which the length of the dead time is changed will be described. The switching elements Q1 and Q3 having the cycle Cy21 had a dead time Dt21 (a period from time t22 to time t23). In order to make the deviation amount ΔTP zero, the control circuit 21b sets the dead time Dt22 (Dt22> Dt21; a period from time t28 to time t2a, etc.) after time t28 when the switching element Q1 is turned off (period Cy22 and later). . Note that one cycle of the switching element Q1 is not changed by “Cy21 = Cy22 = Cy23 =...”.

  By increasing the length of the dead time from Dt21 to Dt22, the timing at which the switching element Q3 is turned on is delayed from time t29 to time t2a (see arrow D2). Thus, in the cycle Cy22, the switching elements Q1 and Q4 are simultaneously turned on from time t26 to time t28 to generate the secondary voltage Vs1, and the voltage time product VT3 is integrated. On the other hand, switching elements Q2 and Q3 are simultaneously turned on from time t2a to time t2b to generate secondary voltage Vs2, and voltage time product VT3 is also accumulated. The same applies to the cycle Cy23 and thereafter. In this way, the voltage-time products applied to the secondary voltages Vs1, Vs2 become equal, so that it is possible to suppress the occurrence of magnetic bias in the transformer Tr1.

  Next, an example in which the duty ratio is changed will be described. As described above, it can be seen that the deviation amount ΔTP is not zero at the time t25 and the transformer Tr1 is demagnetized. Therefore, the duty ratio of the switching element Q3 is changed after the cycle Cy22. In the cycle Cy21, the duty ratio is Dr21, but in the cycle Cy22 and later, the timing at which the switching element Q3 is turned off is delayed to control the pulse signal with the duty ratio Dr22 (Dr21> Dr22). Therefore, in the same way as the control for changing the length of the dead time described above, the control for changing the duty ratio can also suppress the occurrence of bias in the transformer Tr1 after the cycle Cy22.

(Operation signal control example 3)
The operation signal control example 3 is an example in which the length of the dead time and the duty ratio applied to the switching elements Q1 and Q2 are changed, and will be described with reference to FIG. One cycle of the switching element Q1 shown in FIG. 5 is a cycle Cy31 (period from time t31 to time t35), a period Cy32 (period from time t35 to time t3b), and a period Cy33 (period after time t3b). Control is performed so that a bias magnetism occurs in the transformer Tr1 in the cycle Cy31 and the bias magnetism is suppressed after the cycle Cy32.

  In the cycle Cy31, since the switching elements Q1 and Q4 are simultaneously turned on from time t30 to time t31, the secondary voltage Vs1 is generated and the voltage time product VT5 is integrated. On the other hand, since switching elements Q2 and Q3 are simultaneously turned on from time t33 to time t34, secondary voltage Vs2 is generated and voltage time product VT6 is integrated. The control circuit 21b inputs the deviation amount ΔTP (= | VT6 | − | VT5 |) at the timing from time t34 to time t35 (YES in step S10 in FIG. 2), and since the deviation amount ΔTP is not zero, the dead time of The length and duty ratio are changed (steps S11 to S13 in FIG. 2).

  First, an example in which the length of the dead time is changed will be described. The switching elements Q2 and Q4 having the cycle Cy31 had a dead time Dt31 (a period from time t33 to time t34). In order to make the deviation amount ΔTP zero, the control circuit 21b sets the dead time Dt32 (Dt32> Dt31; the period from the time t38 to the time t3a, etc.) after the time t35 when the switching element Q1 is turned on (period Cy32 or later). . Note that one cycle of the switching element Q1 does not change as “Cy31 = Cy32 = Cy33 =...”.

  By increasing the length of the dead time from Dt31 to Dt32, the timing at which the switching element Q2 is turned off is advanced from time t39 to time t38 (see arrow D3). Thus, in the cycle Cy32, the switching elements Q1 and Q4 are simultaneously turned on from time t36 to time t38 to generate the secondary voltage Vs1, and the voltage time product VT5 is integrated. On the other hand, switching elements Q2 and Q3 are simultaneously turned on from time t3a to time t3b to generate secondary voltage Vs2, and voltage time product VT5 is also accumulated. The same applies to the cycle Cy33 and thereafter. In this way, the voltage-time products applied to the secondary voltages Vs1, Vs2 become equal, so that it is possible to suppress the occurrence of magnetic bias in the transformer Tr1.

  Next, an example in which the duty ratio is changed will be described. As described above, it can be seen that the deviation amount ΔTP is not zero at the time t35 and the transformer Tr1 is demagnetized. Therefore, the duty ratio of the switching element Q2 is changed after the cycle Cy32. In the cycle Cy31, the duty ratio is Dr31, but in the cycle Cy32 and later, the pulse signal is controlled with the duty ratio Dr32 (Dr31> Dr32) by advancing the timing of switching the switching element Q4 from on to off. Therefore, similarly to the control for changing the length of the dead time described above, the control for changing the duty ratio can also prevent the occurrence of bias in the transformer Tr1 after the cycle Cy32.

(Operation signal control example 4)
The operation signal control example 4 is an example in which the length of the dead time and the duty ratio applied to the switching element Q4 controlled together with the switching element Q1 are changed, and will be described with reference to FIG. One cycle of the switching element Q1 shown in FIG. 6 is a cycle Cy41 (a period from time t40 to time t46), a cycle Cy42 (a period from time t46 to time t4e), and a cycle Cy43 (a period after time t4e). Control is performed so that a bias magnetism occurs in the transformer Tr1 in the cycle Cy41, and the bias magnetism is suppressed after the cycle Cy42.

  In the cycle Cy41, since the switching elements Q1 and Q4 are simultaneously turned on from time t40 to time t41, the secondary voltage Vs1 is generated and the voltage time product VT7 is integrated. On the other hand, since switching elements Q2 and Q3 are simultaneously turned on from time t43 to time t44, secondary voltage Vs2 is generated and voltage time product VT8 is integrated. The control circuit 21b inputs the deviation amount ΔTP (= | VT8 | − | VT7 |) at the timing after time t44 when the switching element Q2 is turned off (YES in step S10 in FIG. 2), and the deviation amount ΔTP is not zero. Therefore, the length of the dead time and the duty ratio are changed (steps S11 to S13 in FIG. 2).

  First, an example in which the length of the dead time is changed will be described. The switching elements Q2 and Q4 having the cycle Cy41 have a dead time Dt41 (a period from time t41 to time t42). Since the control circuit 21b sets the deviation amount ΔTP to zero, the dead time Dt42 (Dt42 <Dt41; the period from the time t48 to the time t49, or the time t4f after the time t45 when the switching element Q4 is turned on (after the period Cy42). Until the time t4g). Note that one cycle of the switching element Q1 does not change as “Cy41 = Cy42 = Cy43 =...”.

  By shortening the length of the dead time from Dt41 to Dt42, the timing at which the switching element Q4 is turned off is delayed from time t47 to time t48 (see arrow D4). Thus, in the cycle Cy42, the switching elements Q1 and Q4 are simultaneously turned on from time t46 to time t48 to generate the secondary voltage Vs1, and the voltage time product VT8 is integrated. On the other hand, switching elements Q2 and Q3 are simultaneously turned on from time t4a to time t4b to generate secondary voltage Vs2, and voltage time product VT8 is also accumulated. The same applies to the cycle Cy43 and subsequent cycles. In this way, the voltage-time products applied to the secondary voltages Vs1, Vs2 become equal, so that it is possible to suppress the occurrence of magnetic bias in the transformer Tr1.

  Next, an example in which the duty ratio is changed will be described. As described above, it can be seen that the deviation amount ΔTP is not zero at the time t45 and the transformer Tr1 is demagnetized. Therefore, after the cycle Cy42, the duty ratio of the switching element Q4 is changed. In the cycle Cy41, the duty ratio is Dr41. In the cycle Cy42 and later, the timing at which the switching element Q4 is turned off is delayed to control the pulse signal with the duty ratio Dr42 (Dr41 <Dr42). Therefore, in the same way as the control for changing the length of the dead time described above, the control for changing the duty ratio can also suppress the occurrence of bias in the transformer Tr1 after the cycle Cy42.

(Operation signal control example 5)
The operation signal control example 5 is different from the operation signal control examples 1 to 4 in which the dead time length and duty ratio applied to one switching element are changed, and the dead time length and duty ratio applied to a plurality of switching elements are changed. It is an example. Specifically, this is an example of changing the length of the dead time and the duty ratio applied to both the switching element Q1 and the switching element Q4, and will be described with reference to FIG.

  One cycle of the switching element Q1 shown in FIG. 7 is a cycle Cy51 (a period from time t51 to time t57), a cycle Cy52 (a period from time t57 to time t5f), and a cycle Cy53 (a period after time t5f). Control is performed so that a bias magnetism occurs in the transformer Tr1 in the cycle Cy51, and the bias magnetism is suppressed after the cycle Cy52.

  In the cycle Cy51, since the switching elements Q1 and Q4 are simultaneously turned on from time t51 to time t52, the secondary voltage Vs1 is generated and the voltage time product VT9 is integrated. On the other hand, since switching elements Q2 and Q3 are simultaneously turned on from time t54 to time t55, secondary voltage Vs2 is generated and voltage time product VTa is integrated. The control circuit 21b inputs the deviation amount ΔTP (= | VTa | − | VT1 |) at the timing after time t56 when the switching element Q3 is turned off (YES in step S10 in FIG. 2), and the deviation amount ΔTP is not zero. Therefore, the length of the dead time and the duty ratio are changed (steps S11 to S13 in FIG. 2).

  However, even if it is attempted to change the length of the dead time applied to one switching element (switching element Q1 in this example), the limit value that can change the operation signal may be exceeded. For example, with regard to the timing at which the switching element Q1 is turned on from OFF, a control that advances from time t58 to time t56 in order to make the deviation amount ΔTP zero is considered. Since the time t56 is also a timing at which the switching element Q3 is turned off from on, the switching elements Q1 and Q3 may be turned on at the same time even temporarily, considering the time lag described above. In other words, there is a possibility that the power source Edc is short-circuited.

  When the above limit value is exceeded (YES in step S14 in FIG. 2), the dead time length and duty ratio applied to other switching elements (in this example, switching element Q4) are also changed (step in FIG. 2). S15). It should be noted that the ratio of changing the dead time length and the duty ratio applied to the plurality of switching elements can be arbitrarily set. In this example, for easy understanding, the length of the dead time and the duty ratio are changed in the same manner for both of the switching elements Q1 and Q4.

  First, an example in which both the length of the dead time applied to the switching elements Q1, Q3 and the length of the dead time applied to the switching elements Q2, Q4 are changed will be described. Switching elements Q1 and Q3 having a cycle Cy51 have a dead time Dt51 (period from time t50 to time t51), and switching elements Q2 and Q4 having the same cycle have a dead time Dt52 (period from time t52 to time t53). .

  After time t57 when switching element Q1 is turned on (period Cy52 and later), dead time Dt53 (Dt53 <Dt51; period from time t56 to time t57, period from time t5e to time t5f, etc.) for switching elements Q1 and Q3, etc. ) And switching elements Q2 and Q4 are set to dead time Dt54 (Dt54 <Dt52; a period from time t5a to time t5b, a period from time t5g to time t5h, etc.).

  In the cycle Cy52, the timing at which the switching element Q1 is turned on is advanced from time t58 to time t57 by shortening the length of the dead time from Dt51 to Dt52 (see arrow D5a). Further, by shortening the length of the dead time from Dt53 to Dt54, the timing at which the switching element Q4 is turned off is delayed from time t59 to time t5a (see arrow D5b). Due to these changes, the switching elements Q1 and Q4 are simultaneously turned on from time t57 to time t5a to generate the secondary voltage Vs1, and the voltage time product VTa is integrated. On the other hand, switching elements Q2 and Q3 are simultaneously turned on from time t5c to time t5d to generate secondary voltage Vs2, and voltage time product VTa is also accumulated. The same applies to the cycle Cy53 and thereafter. In this way, the voltage-time products applied to the secondary voltages Vs1, Vs2 become equal, so that it is possible to suppress the occurrence of magnetic bias in the transformer Tr1.

  Next, an example in which the duty ratio is changed will be described. As described above, it can be seen that the deviation amount ΔTP is not zero and the transformer Tr1 is demagnetized at the time t56. Even if an attempt is made to change the duty ratio applied to one switching element (switching element Q1 in this example) so as to make the deviation amount ΔTP zero, there is a case where a predetermined ratio value that can change the operation signal is exceeded. This is the same as the case where the length of the dead time is changed as described above.

  Therefore, after the cycle Cy52, the duty ratio is changed for each of the plurality of switching elements Q1, Q4. Regarding the switching element Q1, the duty ratio Dr51 is in the cycle Cy51, whereas the pulse signal is controlled with the duty ratio Dr52 (Dr52> Dr51) by advancing the timing of turning on from OFF in the cycle Cy52 and thereafter. Similarly, for the switching element Q4, the duty ratio Dr53 is in the cycle Cy51, but after the cycle Cy52, the pulse signal is controlled with the duty ratio Dr54 (Dr53> Dr54) by delaying the timing of turning from OFF to ON. Therefore, in the same way as the control for changing the length of the dead time described above, the control for changing the duty ratio can also suppress the occurrence of bias in the transformer Tr1 after the cycle Cy52.

  In the operation signal control example 5 described above, the voltage-time product VT9 by the switching elements Q1, Q4 is controlled to be the voltage-time product VTa. Instead of this control example, the voltage time product VT applied to the switching elements Q2 and Q3 may be controlled so that the voltage time product VTa in the cycle Cy51 where the demagnetization occurs becomes the voltage time product VT9 after the cycle Cy52. Good. When this control is performed, the above limit value is not exceeded. Therefore, as shown in the operation signal control example 2, the timing for turning on the switching element Q3 is delayed (see arrow D2), or the operation signal control example 3 As shown in FIG. 4, the timing of switching the switching element Q2 from on to off may be advanced (see arrow D3). Even when this control is performed, the voltage-time product applied to the secondary voltages Vs1 and Vs2 becomes equal as in the operation signal control example 5 described above, so that the occurrence of bias magnetism can be suppressed by the transformer Tr1.

In the operation signal control example 5, the switching element Q1 is applied to the “one switching element”, and the switching element Q4 is applied to the “other switching element”. Instead of this form, the switching element Q4 may be applied to the “one switching element”, and the switching element Q1 may be applied to the “other switching element”. Similarly, the switching elements Q2 and Q3 may be applied to the “one switching element”, and the switching elements Q3 and Q2 may be applied to the “other switching element”. The applicable switching elements vary depending on the timing at which the operation signal (pulse signal) transmitted to the switching elements Q1 to Q4 is turned on / off.

According to the first embodiment described above, the following effects can be obtained.
(1) In the power converter 20, diodes D11 and D12 that rectify the secondary voltages Vs1 and Vs2 (AC power) output from the secondary terminal of the transformer Tr1, and diodes D11 and D12 (two or more rectifiers) Integration units 22 and 23 that output voltage time products obtained by integrating DC voltages (DC power) to be rectified individually and over time, and deviation amount detection that detects a deviation amount ΔTP related to two or more voltage time products. And an operation signal control unit 21 that performs control to change the operation signal so that the deviation amount ΔTP becomes zero based on the deviation amount ΔTP detected by the deviation amount detection unit 24 ( (See FIG. 1). According to this configuration, based on the deviation amount ΔTP detected by the deviation amount detection unit 24, the operation signal control unit 21 performs control to change the operation signal so that the deviation amount ΔTP becomes zero. If the deviation amount ΔTP becomes zero, the voltage time product of the DC voltage becomes equal, and the bias of the transformer Tr1 can be suppressed (including reduction). By making the individual diodes D11 and D12 correspond to positive and negative DC voltages, it is possible to suppress the bias of the transformer Tr1 regardless of positive or negative. Since it is only necessary to provide the diodes D11 and D12 corresponding to the positive and negative of the secondary voltages Vs1 and Vs2 output from the secondary terminal of the transformer Tr1, without adding a circuit element to the current flow path, the cost of the entire apparatus can be reduced. Can be suppressed.

(2) The operation signal control unit 21 is configured to change the duty ratios Dr11, Dr21, Dr31, Dr41, Dr51, and Dr53 indicating the ratio of the period during which the switching elements Q1 to Q4 are turned on / off (operation signal control example 1 ~ 5; see Figures 3-7). According to this configuration, the operation signal is changed to the switching elements Q1 to Q4 by changing the duty ratios Dr11, Dr21, Dr31, Dr41, Dr51, Dr53 of the operation signal so that the deviation amount ΔTP of the voltage time product becomes zero. Just communicate. Since the existing control method can be used, the cost of the entire apparatus can be suppressed.

(3) Having a plurality (two or more) of switching elements Q1 to Q4, the operation signal control unit 21 applies to another switching element Q4 when the duty ratio Dr51 applied to one switching element Q1 reaches a predetermined ratio value. The duty ratio Dr52 is changed (operation signal control example 5; see FIG. 7). According to this configuration, when the duty ratio Dr51 applied to one switching element Q1 reaches a predetermined ratio value, the duty ratio Dr52 applied to another switching element Q4 is also changed in addition to the duty ratio Dr51. Since the duty ratios Dr51 and Dr52 applied to the plurality of switching elements Q1 and Q4 are changed within a range not exceeding the predetermined ratio value, the plurality of switching elements Q1 to Q4 are stably operated, and the bias of the transformer Tr1 is suppressed. can do.

(4) a plurality a switching element Q1~Q4 of (two or more), the second switching element to be operating in conjunction (switching elements Q1, Q3 or the switching elements Q2, Q4), the operation signal controller 21 Is configured to change the length of dead time Dt11, Dt21, Dt31, Dt41 (first dead time) from the change of the state of one switching element to the change of the state of the other switching element (operation signal control). Examples 1-4; see Figures 3-6). According to this configuration, the operation signals may be transmitted to the switching elements Q1 to Q4 by changing the lengths of the dead times Dt11, Dt21, Dt31, and Dt41 associated with one switching element from the other switching element. Since the existing control method can be used, the cost of the entire apparatus can be suppressed.

(5) When the length of the dead time Dt51 (first dead time) applied to the switching elements Q1 and Q3 to be operated in cooperation with each other reaches the predetermined length value, the operation signal control unit 21 switches the switching elements Q1 and Q3. the (one set) and the separate switching element Q2, Q4 (the other set), the dead from instead off one the state of the switching element Q4 from oN to change the on state of the other switching element Q2 from oFF The length Dt52 (second dead time) is changed (operation signal control example 5; see FIG. 7). According to this configuration, when the dead time Dt51 included in the operation signal to be output reaches a predetermined length value, the dead time Dt52 is also changed in addition to the dead time Dt51. Since the dead times Dt51 and Dt52 applied to the plurality of switching elements Q1 to Q4 are changed to the dead times Dt53 and Dt54 within a range not exceeding the predetermined length value, the plurality of switching elements Q1 to Q4 are stably operated, In addition, the bias of the transformer Tr1 can be suppressed.

  Although not shown, similar control may be performed even when the pulse signal pattern shown in the operation signal control example 5 (FIG. 7) is switched between the switching elements Q1 and Q3 and the switching elements Q2 and Q4. Even in this case, only the switching elements to be operated in cooperation with each other are different, so that the bias of the transformer Tr1 can be suppressed.

(6) The power supply system 10 having the power conversion device 20 includes a connection portion J that electrically connects the output terminals of the diodes D11 and D12 (rectifying portion), and a filter portion that reduces the AC component of the DC voltage at the connection portion J. 12 (see FIG. 1). According to this configuration, it is possible to cope with positive and negative DC components while suppressing cost, and it is possible to suppress the bias of the transformer Tr1 without adding a circuit element to the current flow path.

[Embodiment 2]
The second embodiment is an example of suppressing the bias of the transformer based on the electric power by the voltage control, as in the first embodiment, and will be described with reference to FIG. A part of the configuration of the power supply system 10 including the power conversion device 20 is the same as that of the first embodiment. Therefore, in the second embodiment, the same elements as those used in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and contents different from the above-described first embodiment are described.

  The second embodiment is greatly different in that a transformer Tr2 is used instead of the transformer Tr1 (see FIG. 1) of the first embodiment. The transformer Tr1 used a type having at least three terminals as a secondary terminal together with a primary terminal. On the other hand, the transformer Tr2 is of the same type as the primary terminal and the secondary terminal, and does not have an intermediate terminal like the transformer Tr1. Note that a transformer having an intermediate terminal may be used as in the case of the transformer Tr1, but the intermediate terminal is not used.

  Along with the use of the transformer Tr2, rectifiers Db1, Db2, switches SW1, SW2, etc. are newly added. The rectifiers Db1, Db2, and the input side are connected in parallel to the secondary terminal of the transformer Tr2. The rectification unit Db1 also functions as the “connection unit J” and is provided in the power supply system 10. One terminal of the rectifying unit Db1 is connected to the capacitor C11 and the filter unit 12, and the other terminal is connected to the ground N. The rectifying unit Db2 is provided in the power conversion device 20. One terminal of the rectifying unit Db2 is connected to the integrating units 22 and 23, and the other terminal is connected to the ground N. These rectifiers Db1 and Db2 are composed of diodes or the like, and have a function of rectifying the secondary voltage Vs3 (AC power) output to the secondary terminal of the transformer Tr2 into DC voltage (DC power), and are a half-wave rectifier circuit It does not matter if it is a full-wave rectifier circuit.

  The switches SW1 and SW2 are individually controlled to be turned on / off by the control circuit 21b. The switch SW1 can be switched whether to transmit the output of the integrating unit 22 (that is, the voltage time product VT of the secondary voltage Vs3 corresponding to the secondary voltage Vs2) to the deviation amount detecting unit 24. The switch SW2 can be switched whether to transmit the output of the integrating unit 23 (that is, the voltage time product VT of the secondary voltage Vs3 corresponding to the secondary voltage Vs1) to the deviation amount detecting unit 24.

  For example, the switch SW2 is controlled to be turned on / off at the same timing as the switching element Q1 shown in FIGS. 3 to 7, and the switch SW1 is controlled to be turned on / off contrary to the switch SW2. That is, when the secondary voltage Vs3 corresponding to the secondary voltage Vs1 in the first embodiment is detected, the switch SW1 is turned on. Similarly, when the secondary voltage Vs3 corresponding to the secondary voltage Vs2 in the first embodiment is detected, the switch SW2 is turned on. By controlling the switches SW1 and SW2, the operation signal control examples 1 to 5 (see FIGS. 3 to 7) described in the first embodiment can be realized.

  According to the second embodiment described above, since the operation signal control examples 1 to 5 (see FIGS. 3 to 7) described in the first embodiment can be realized, the embodiments corresponding to claims 1 to 5 respectively. 1 is obtained. That is, it is possible to suppress the bias of the transformer Tr2.

  The power supply system 10 having the power conversion device 20 corresponding to claim 6 includes a rectifying unit Db1 including the function of the connecting unit J, and a filter unit 12 that reduces the AC component of the DC voltage output from the rectifying unit Db1. (See FIG. 8). According to this configuration, it is possible to deal with positive and negative DC components while suppressing cost, and it is possible to suppress the bias of the transformer Tr2 without adding a circuit element to the current flow path.

[Other Embodiments]
In the above, although the form for implementing this invention was demonstrated according to Embodiment 1, 2, this invention is not limited to the said form at all. In other words, various forms can be implemented without departing from the scope of the present invention. For example, the following forms may be realized.

  In the first and second embodiments described above, the power conversion unit that converts DC voltage (DC power) to AC voltage (AC power) in the power conversion device 20 is a full bridge using the switching elements Q1 to Q4. It comprised (refer FIG. 1, FIG. 8). Instead of this form, a power conversion unit that reduces the number of switching elements may be configured. For example, you may comprise with the half bridge shown to FIG. 9 (A), and may comprise with the push pull shown to FIG. 9 (B). In the half-bridge configuration shown in FIG. 9A, a capacitor C2 is used instead of the switching element Q2, and a capacitor C4 is used instead of the switching element Q4. Although not shown, a plurality of single forward systems, flyback systems, etc. (for example, 2 or 4) may be used and connected to the primary terminal side of the transformers Tr1 and Tr2. Since only the configuration of the power conversion unit connected to the primary terminal side of the transformers Tr1 and Tr2 is different, the same effects as those of the first and second embodiments can be obtained.

  In the first and second embodiments described above, the operation signal of the switching element Q1 to Q4 is changed based on the operation signal of the switching element Q1 (operation signal control examples 1 to 4; FIGS. 3 to 6 reference). Instead of this form, the operation signals of the switching elements Q1 to Q4 may be changed with reference to the operation signals of the switching elements other than the switching element Q1 (that is, any one of the switching elements Q2 to Q4). Since only the reference operation signal is different, the same operational effects as those of the first and second embodiments can be obtained.

  In the above-described first and second embodiments, RC circuits each including a resistor and a capacitor and having a large time constant are applied as the integrating units 22 and 23 (see FIGS. 1 and 8). Instead of this form, for example, an integration circuit using an operational amplifier may be used. Further, an RC circuit or an integration circuit having a small time constant may be applied. In this case, it is desirable to connect the peak hold circuits PH1 and PH2 as shown by two-dot chain lines in FIGS. The peak hold circuit PH individually generates voltage time products VT applied to the secondary voltages Vs1 and Vs2 (secondary voltages Vs3 corresponding to these) until a predetermined time (time t15 and time t1c in the example of FIG. 3). Responsible for holding the function. Regardless of the configuration, the voltage-time product VT can be integrated, so that the same effects as those of the first and second embodiments can be obtained.

  In the first and second embodiments described above, the LC circuit including the reactor L12 and the capacitor C12 is applied as the filter unit 12 (low-pass filter) (see FIGS. 1 and 8). Instead of (or in addition to) this form, a filter unit having another configuration capable of removing a high-frequency component of a DC voltage (DC power) may be applied. For example, an RC circuit composed of a resistor and a capacitor, an active low-pass filter using an operational amplifier, or the like may be used. Not only analog filters such as these, but digital filters may also be used. Since any filter unit can remove the high-frequency component of the DC voltage (DC power), the same effects as those of the first and second embodiments can be obtained.

  In the first and second embodiments described above, the N-channel MOSFET is used for the switching elements Q1 to Q4 (see FIGS. 1, 8, and 9). Instead of this form, another switching element may be used. Examples of other switching elements include FETs (specifically, P-channel MOSFETs, JFETs, MESFETs, etc.), IGBTs, GTOs, power transistors, and the like. Regardless of which switching element is used, a power converter that converts a DC voltage (DC power) into an AC voltage (AC power) can be configured, so that the same effects as those of the first and second embodiments can be obtained.

  In the first and second embodiments described above, the voltage time products VT of the secondary voltages Vs1, Vs2, and the secondary voltage Vs3 are obtained based on the DC voltage (DC power) supplied from the power source Edc, and within one cycle. When the deviation amount ΔTP is not 0, the operation signal for operating the switching elements Q1 to Q4 is changed (see FIGS. 1 to 8). That is, it applied about the electric power by voltage control. It can replace with this form and can also apply to the electric power by current control. In this case, the power conversion device 20 is supplied with a direct current (direct current power) from the power source Edc, converts it into an alternating current (alternating current power), and outputs it. Since the method for converting the circuit configuration related to the constant voltage source to the circuit configuration related to the constant current source is well known, the circuit configurations shown in FIGS. 1 and 8 can be converted in the same manner. However, since phase lag is generated by the transformers Tr1 and Tr2, the switching elements Q1 to Q4 need to be controlled in consideration of the phase lag. Therefore, the same effects as those of the first and second embodiments described above can be obtained for the electric power by the current control.

  In the first and second embodiments described above, the operation signal for operating the switching elements Q1 to Q4 is changed only when the deviation amount ΔTP is 0 (see steps S12 and S13 in FIG. 2). Instead of this configuration, the operation signal may not be changed when the allowable range (ΔTP ≦ α) has almost no influence on the output even when the bias is generated in the transformers Tr1 and Tr2. In the parentheses shown in step S12 of “ΔTP ≦ α?”). In other words, when the magnetic bias generated in the transformers Tr1 and Tr2 is outside the allowable range (ΔTP> α), the operation signal is changed. For α, an appropriate numerical value is set according to the configuration of the power conversion device 20 (for example, the type of switching element, the voltage or current to be controlled, and the like). When this control is performed, the bias magnetism of the transformers Tr1 and Tr2 can be suppressed within an allowable range.

DESCRIPTION OF SYMBOLS 10 Power supply system 12 Filter part 20 Power converter 21 Operation signal control part 21a Drive circuit 21b Control circuit 22,23 Integration part 24 Deviation amount detection part 30 Output device VT1, VT2, VT3 Voltage time product Q1, Q2, Q3, Q4 switching Element Tr1, Tr2 Transformer Dt11, Dt12, ... Dead time Dr11, Dr12, ... Duty ratio ΔTP Deviation

Claims (5)

In a power converter including at least a switching element that performs switching based on an operation signal, and a transformer that electrically connects the switching element to a primary terminal,
A plurality of the switching elements configured by one of a full bridge, a half bridge, a push-pull, a plurality of single forward systems, and a plurality of flyback systems;
Two or more rectifiers for rectifying AC power output from the secondary terminal of the transformer;
An integrator for outputting a power time product obtained by integrating the DC power rectified by the two or more rectifiers individually and over time; and
A deviation amount detection unit for detecting a deviation amount according to the two or more power time products;
Based on the deviation amount detected by said deviation detecting section, and an operation signal controller for controlling the amount of the deviation varying said operation signal to be zero,
The operation signal control unit, when the duty ratio indicating a ratio of a period during which the switching element is turned on / off, when the duty ratio applied to the switching element serving as a reference among the plurality of switching elements reaches a predetermined ratio value A power conversion device that changes the duty ratio applied to one of the switching elements included in the plurality of switching elements . In a power converter including at least a switching element that performs switching based on an operation signal, and a transformer that electrically connects the switching element to a primary terminal,
A plurality of the switching elements configured by one of a full bridge, a half bridge, a push-pull, a plurality of single forward systems, and a plurality of flyback systems;
Two or more rectifiers for rectifying AC power output from the secondary terminal of the transformer;
An integrator for outputting a power time product obtained by integrating the DC power rectified by the two or more rectifiers individually and over time; and
A deviation amount detection unit for detecting a deviation amount according to the two or more power time products;
Based on the deviation amount detected by said deviation detecting section, and an operation signal controller for controlling the amount of the deviation varying said operation signal to be zero,
The operation signal control unit changes a state of one of the switching elements and then changes a state of the other switching element of two switching elements that can be short-circuited when turned on simultaneously among the plurality of switching elements. The power converter characterized by changing the length of the 1st dead time until . The power conversion device according to claim 2 , wherein the operation signal control unit changes a duty ratio indicating a ratio of a period during which the switching element is turned on / off. There are two sets of two switching elements that can be short-circuited when simultaneously turned on among the plurality of switching elements,
When the length of the first dead time applied to one of the two sets reaches a predetermined length value, the operation signal control unit includes the two switching elements applied to the other set of the two sets. 4. The power conversion device according to claim 2 , wherein the length of the second dead time from when the state of one of the switching elements is changed to when the state of the other switching element is changed is changed. . It has the power converter device according to any one of claims 1 to 4 ,
A connection part for electrically connecting output terminals of the two or more rectification parts;
A filter unit for reducing an AC component of DC power in the connection unit;
A power supply system comprising:

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