JP6437317B2 - Full-bridge bidirectional DC / DC converter - Google Patents

Description

  The present invention relates to a full bridge type bidirectional insulated DC / DC converter, and more particularly to a full bridge type bidirectional insulated DC / DC converter that does not require switching control between a power running operation and a regenerative operation.

  The bidirectional insulated DC / DC converter includes a transformer, a DC power source (primary side power source) connected to the primary side of the transformer, and a DC power source (secondary side power source) connected to the secondary side of the transformer, This is a circuit that can transmit power in both directions between the primary power supply and the secondary power supply.

  Specific applications of the bidirectional insulated DC / DC converter include, for example, a battery charge / discharge test apparatus. In this case, a system power source or a DC bus is connected as a primary power source, and a test target battery is connected as a secondary power source. When a battery charge test is performed (powering), power is sent from the system power source to the battery via the bidirectional insulated DC / DC converter, and when a battery discharge test is performed (regeneration). Then, electric power is sent from the battery to the system power supply via the bidirectional insulated DC / DC converter. As described above, the bidirectional insulated DC / DC converter plays a role of transmitting power bidirectionally between the system power supply and the battery.

  Patent Document 1 discloses bidirectional insulation having a primary side circuit configured by a push-pull method, a half-bridge method, a full-bridge method, and the like, and a secondary side circuit configured by a half-wave rectifier circuit or a full-wave rectifier circuit. A DC / DC converter is disclosed. In this bidirectional insulated DC / DC converter, for example, as shown in FIGS. 2 to 5 of Patent Document 1, the control side of each switching element is not particularly switched between power running and regeneration, and the primary side is used during power running. Power is transmitted from the power supply to the secondary power supply, and power is transmitted from the secondary power supply to the primary power supply during regeneration.

  Patent Document 2 discloses a bidirectional insulated DC / DC converter in which both a primary side circuit and a secondary side circuit are configured by a full bridge system. The primary side circuit of this bidirectional insulated DC / DC converter is in a positive connection state (a state where the positive electrode of the primary power supply is connected to one end of the primary winding of the transformer and the negative electrode of the primary power supply is connected to the other end). And a negative connection state (a state in which the negative electrode of the primary power supply is connected to one end of the primary winding of the transformer and the positive electrode of the primary power supply is connected to the other end) with a duty ratio of 50%. . Similarly, in the secondary circuit, the positive connection (the state where the positive electrode of the secondary power supply is connected to one end of the transformer secondary winding and the negative electrode of the secondary power supply is connected to the other end) and the negative connection The state (a state in which the negative electrode of the secondary power supply is connected to one end of the secondary winding of the transformer and the positive electrode of the secondary power supply is connected to the other end) is configured to be repeated at a duty ratio of 50%. Then, by shifting the phase of this repetitive operation between the primary side circuit and the secondary side circuit, power transmission between the primary side power source and the secondary side power source is realized. Switching between the power running operation and the regenerative operation is realized by switching the phase shift amount.

JP2012-210104 JP2013-176174A

  Incidentally, in recent years, in a large-capacity switching power supply that outputs an output of several kW or more, as shown in Patent Document 2, a bidirectional insulated DC / DC converter in which both a primary side circuit and a secondary side circuit are configured by a full bridge circuit. (Hereinafter referred to as “full-bridge bidirectionally isolated DC / DC converter”) has come to be used. This is because the number of turns of the transformer can be reduced as compared with the case where other types of circuits are used, so that the size can be reduced and the copper loss of the transformer can be reduced.

  However, in the conventional full-bridge bidirectionally insulated DC / DC converters, as shown in Patent Document 2, the control method (specifically, phase shift amount) of each switching element is different between powering and regeneration. There was a need to switch. As a result, a complicated control mechanism is required to switch between the power running operation and the regenerative operation, which is expensive.

  Accordingly, one of the objects of the present invention is that power can be transmitted from the primary side power source to the secondary side power source during power running without particularly switching the control method of each switching element during power running and regeneration, and the secondary side during regeneration. An object of the present invention is to provide a full-bridge bidirectionally isolated DC / DC converter capable of transmitting power from a power supply to a primary power supply.

  In order to achieve the above object, a full bridge bidirectional insulated DC / DC converter according to the present invention includes a transformer, a first coil having one end connected to one end of a second power source, and one end having a first power source. A first switching element connected to one end and the other end connected to one end on the primary side of the transformer; one end connected to one end on the primary side of the transformer; the other end connected to the other end of the first power source A second switching element connected to the first power supply, one end connected to one end of the first power supply, the other end connected to the other end of the primary side of the transformer, and one end connected to the transformer A fourth switching element connected to the other end of the primary side, the other end connected to the other end of the first power source, one end connected to the other end of the first coil, and the other end connected to the other end of the first coil. The fifth connected to one end of the secondary side of the transformer An switching element, a sixth switching element having one end connected to one end on the secondary side of the transformer and the other end connected to the other end of the second power source, and one end connected to the other end of the first coil A seventh switching element having the other end connected to the other end on the secondary side of the transformer, one end connected to the other end on the secondary side of the transformer, and the other end connected to the second power source. An eighth switching element connected to the other end of the first switching element, and a control unit that controls on / off of the first to eighth switching elements. The control unit changes the active state and the inactive state at a predetermined cycle. The on-off state of the first, second, fifth, and seventh switching elements is controlled according to the repeated first drive signal, and the second drive signal is obtained by shifting the phase of the first drive signal. Depending on the active state, the third, fourth, 6, characterized in that it is configured to control the on-off state of the switching device of the eighth.

  The full-bridge bidirectionally insulated DC / DC converter according to the present invention transmits power from the first power supply to the second power supply without particularly switching the control method of each switch between powering and regeneration. In the case), it functions as a step-down chopper that steps down the voltage of the first power source and supplies it to the second power source, and the second time during regeneration (when power is transmitted from the second power source to the first power source). Functions as a step-up chopper that boosts the voltage of the first power source and supplies it to the first power source. Therefore, power is transferred from the primary power supply to the secondary power supply during power running, and power is transferred from the secondary power supply to the primary power supply during regeneration without switching the control method of each switch between power running and regeneration. It becomes possible to do. The specific value of the voltage transmitted to the power source on the transmission side may be adjusted by the phase difference between the first and second drive signals and the transformer transformation ratio.

  In the full-bridge bidirectionally isolated DC / DC converter, the control unit turns on each of the first and fifth switching elements in response to activation of the first drive signal, and the second and second switching elements. Each of the seventh switching elements is turned off, each of the second and seventh switching elements is turned on in response to the deactivation of the first drive signal, and each of the first and fifth switching elements is turned on. Each is turned off, and each of the third and sixth switching elements is turned on in response to activation of the second drive signal, and each of the fourth and eighth switching elements is turned off. Each of the fourth and eighth switching elements is turned on in response to the deactivation of the drive signal of 2 and the third and Each may be configured to turn off the sixth switching element. In this way, it is possible to suitably control the on / off states of the first to eighth switching elements.

  In the full-bridge bidirectionally insulated DC / DC converter, the control unit further turns on the first switching element after a second delay time has elapsed since turning off the second switching element, The first switching element is turned off, the second switching element is turned on after elapse of the second delay time, and the fourth switching element is turned off after elapse of the second delay time. The third switching element may be turned on, and the fourth switching element may be turned on after elapse of the second delay time after the third switching element is turned off. According to this, the primary side circuit can be provided with a dead time equal to the second delay time.

  In each of the full-bridge bidirectionally isolated DC / DC converters, the controller further turns off the seventh switching element after a third delay time has elapsed since turning on the fifth switching element. The fifth switching element is turned off after the third delay time has elapsed since the seventh switching element was turned on, and the sixth switching element was turned on after the third delay time has elapsed. The eighth switching element may be turned off, and the sixth switching element may be turned off after the third delay time has elapsed since the eighth switching element was turned on. According to this, it is possible to provide an overlap time equal to the third delay time in the secondary side circuit.

  In each of the full-bridge bidirectionally isolated DC / DC converters, the second drive signal is configured to be activated after a first delay time after the first drive signal is activated, and the control unit Turns on the third switching element after elapse of the first delay time from turning on the first switching element, and turns on the second switching element after turning on the second switching element. After the elapse of time, the fourth switching element is turned on, the first switching element is turned off, the third switching element is turned off after the first delay time has elapsed, and the second switching element is turned off. After the first delay time has elapsed, the fourth switching element is turned off, the fifth switching element is turned on, and After the elapse of a time obtained by adding the fourth delay time to the delay time of 1, the sixth switching element is turned on, the seventh switching element is turned on, and then the fourth delay time is reached. After the elapse of the time obtained by adding the delay time, the eighth switching element is turned on, the fifth switching element is turned off, and the fourth delay time is added to the first delay time. The sixth switching element is turned off after a lapse of a certain time, the fourth switching time is added to the first delay time after the seventh switching element is turned off, and the fourth delay time is added. 8 switching elements may be configured to be turned off. According to this, by adjusting the fourth delay time, it becomes possible to vary the amount of electric power transmitted during power running and during regeneration.

  In each of the full-bridge bidirectionally isolated DC / DC converters, a second coil having one end connected to one end of the first coil and a first anode connected to the other end of the first coil. A diode, one end connected to the cathode of the first diode, the other end connected to the other end of the second coil, and an anode connected to the other end of the second power source. A second diode having a cathode connected to the other end of the ninth switching element; one end connected to the other end of the second power supply; and the other end connected to one end of the ninth switching element. A capacitor to be connected may be further provided. According to this, since the snubber circuit is constituted by the second coil, the first diode, the ninth switching element, the second diode, and the capacitor, it is possible to protect the circuit from a transient high voltage. become.

  In the full-bridge bidirectionally isolated DC / DC converter, the control unit further turns on the fifth switching element after turning on the ninth switching element when turning off the fifth to eighth switching elements at the same time. Alternatively, the eighth switching element may be configured to be turned off. According to this, it becomes possible to urgently stop the full bridge type bidirectionally insulated DC / DC converter without causing destruction of the fifth to eighth switching elements during regeneration.

  According to the present invention, power is transmitted from the primary power source to the secondary power source during power running without particularly switching the control method of each switching element during power running and regeneration, and from the secondary power source to the primary side during regeneration. It is possible to transmit power to the power source.

It is a figure which shows the structure of the full bridge system bidirectional | two-way insulated DC / DC converter 1 by preferable embodiment of this invention. FIG. 2 is a signal diagram illustrating an operation of the full-bridge bidirectionally insulated DC / DC converter 1 illustrated in FIG. 1. It is a signal diagram which shows the ideal operation | movement of the full bridge system bidirectional | two-way insulated DC / DC converter 1 shown in FIG. (A)-(d) is a figure which shows the on-off state of switching element Q1-Q8 in state S1-S4 shown in FIG. 3, respectively. (A) is the figure which replaced the part concerning switching elements Q1-S8 among full bridge system bidirectional insulation DC / DC converters 1 (except for snubber circuit S) with the equivalent circuit, and (b) FIG. 7 is a diagram in which a portion related to T1 is replaced with an equivalent circuit, and (c) is a diagram illustrating a case where the transformer T1 is further replaced with an ideal transformer. 6A and 6B are diagrams showing the operation of the equivalent circuit diagram shown in FIG. 5C, where FIG. 5A corresponds to the states S1 and S3 shown in FIG. 3, and FIG. 5B corresponds to the states S2 and S4 shown in FIG. doing.

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

  As shown in FIG. 1, the full-bridge bidirectionally insulated DC / DC converter 1 according to the present embodiment includes a transformer T1, a primary-side inverter circuit IV1, a secondary-side inverter circuit IV2, and a control unit 2. Configured. The primary side inverter circuit IV1 is connected between the power source P1 (first power source) and the primary side of the transformer T1, and the secondary side inverter circuit IV2 is a secondary side of the power source P2 (second power source) and the transformer T1. Connected between the sides. The full-bridge bidirectionally insulated DC / DC converter 1 is, for example, a battery charge / discharge test apparatus. In this case, the power source P1 is a system power source or a DC bus, and the power source P2 is a battery to be tested.

  The primary side inverter circuit IV1 includes two bridge circuits B1 and B2. The bridge circuit B1 has one end connected to one end of the power supply P1, the other end connected to one end on the primary side of the transformer T1, and one end connected to one end on the primary side of the transformer T1. And a switching element Q2 (second switching element) having the other end connected to the other end of the power supply P1. The bridge circuit B2 has one end connected to one end of the power supply P1, the other end connected to the other end of the primary side of the transformer T1, and one end connected to the primary side of the transformer T1. A switching element Q4 (fourth switching element) is connected to the other end and the other end is connected to the other end of the power supply P1.

  The secondary-side inverter circuit IV2 includes two bridge circuits B3 and B4, a coil L1 (first coil), and a snubber circuit S. One end of the coil L1 is connected to one end of the power source P2. The bridge circuit B3 has one end connected to the other end of the coil L1, the other end connected to one end on the secondary side of the transformer T1, and one end connected to the other end of the coil L1. And a switching element Q7 (seventh switching element) having the other end connected to the other end on the secondary side of the transformer T1. The bridge circuit B4 has one end connected to one end on the secondary side of the transformer T1, the other end connected to the other end of the power supply P2, and one end connected to the secondary side of the transformer T1. And a switching element Q8 (eighth switching element) connected to the other end of the power source P2. The snubber circuit S includes a coil L2 (second coil) having one end connected to one end of the coil L1, a diode D1 (first diode) having an anode connected to the other end of the coil L1, and a diode D1 having one end connected to the other end of the coil L1. Switching element Q9 (the ninth switching element) whose other end is connected to the other end of the coil L2, the anode is connected to the other end of the power supply P2, and the cathode is connected to the other end of the switching element Q9. A diode D2 (second diode) to be connected and a capacitor C1 having one end connected to the other end of the power supply P2 and the other end connected to one end of the switching element Q9.

  As shown in FIG. 1, each of the switching elements Q1 to Q9 is composed of an N channel type MOS transistor having a parasitic diode. One end of each of the switching elements Q1 to Q9 constitutes the drain of the MOS transistor (the cathode of the parasitic diode), and the other end constitutes the source of the MOS transistor (the anode of the parasitic diode).

  Control signals UP, UN, VP, VN, XP, XN, YP, YN, and SN are supplied from the control unit 2 to the gate electrodes of the switching elements Q1 to Q9, respectively. The on / off states of the switching elements Q1 to Q9 can be individually controlled by the control unit 2 individually controlling the voltage levels of these control signals. For example, the switching element Q1 is turned on when the control signal UP is at a high level, and is turned off when the control signal UP is at a low level. The same applies to the other switching elements Q2 to Q9.

  The control unit 2 is supplied with a drive signal DR1 (first drive signal) from the outside. The control unit 2 generates a drive signal DR2 (second drive signal) based on the drive signal DR1, and further, on / off states of the switching elements Q1, Q2, Q5, Q7 constituting the bridge circuits B1, B3 (control) The active states of the signals UP, UN, XP, YP) are controlled according to the drive signal DR1, and the on / off states of the switching elements Q3, Q4, Q6, Q8 constituting the bridge circuits B2, B4 (control signals VP, VN, XN and YN are activated) according to the drive signal DR2.

  As shown in FIG. 2, the drive signal DR1 is a periodic signal that repeats an active state and an inactive state at a predetermined period T. The duty ratio between the active state and the inactive state is 50%. The control unit 2 generates the drive signal DR2 by shifting the phase of the drive signal DR1 by a time t1 (first delay time, 0 <t1 ≦ T / 2). Therefore, the drive signal DR2 is also a periodic signal that repeats the active state and the inactive state in the cycle T, and the activation timing of the drive signal DR2 comes after time t1 after the drive signal DR1 is activated. In FIG. 2, the drive signals DR1 and DR2 are illustrated as high active signals, but these may be low active signals.

  The control unit 2 controls the active states of the control signals UP, UN, VP, VN, XP, XN, YP, and YN according to the drive signals DR1 and DR2, thereby turning on and off the switching elements Q1 to Q8. To control. Specifically, switching elements Q1 and Q5 are turned on and switching elements Q2 and Q7 are turned off in response to activation of drive signal DR1, and switching elements Q2 and Q7 are turned on and switched in response to inactivation of drive signal DR1. Elements Q1 and Q5 are turned off, switching elements Q3 and Q6 are turned on in response to activation of drive signal DR2, switching elements Q4 and Q8 are turned off, and switching elements Q4 and Q8 are turned on in response to inactivation of drive signal DR2. The active states of the control signals UP, UN, VP, VN, XP, XN, YP, YN are controlled so that the switching elements Q3, Q6 are turned off. Hereinafter, changes in the active states of the control signals UP, UN, VP, VN, XP, XN, YP, and YN controlled by the control unit 2 will be described in more detail with reference to FIG.

  First, the control unit 2 activates the control signal UP after the elapse of the delay time t2 (second delay time) from the activation of the drive signal DR1 and returns to the inactivation when the drive signal DR1 is deactivated. Be controlled. On the other hand, the control signal UN is controlled by the control unit 2 so as to be activated after the delay time t2 has elapsed from the deactivation of the drive signal DR1 and to return to the deactivation when the drive signal DR1 is activated. Thereby, the switching element Q1 is turned on after the delay time t2 has elapsed since the switching element Q2 was turned off, and the switching element Q2 is turned on after the delay time t2 has elapsed since the switching element Q1 was turned off. Become.

  Next, the control signal VP is controlled by the control unit 2 so as to be activated after the delay time t2 has elapsed from the activation of the drive signal DR2 and to return to the inactivation when the drive signal DR2 is deactivated. On the other hand, the control signal VN is controlled by the control unit 2 so as to be activated after the delay time t2 has elapsed from the deactivation of the drive signal DR2 and to be deactivated with the activation of the drive signal DR2. Thus, the switching element Q3 is turned on after the delay time t2 has elapsed since the switching element Q4 was turned off, and the switching element Q4 is turned on after the delay time t2 has elapsed since the switching element Q3 was turned off. Become. Further, the switching element Q3 is turned on after a lapse of the delay time t1 since the switching element Q1 is turned on, and is turned off after the lapse of the delay time t1 after the switching element Q1 is turned off. The switching element Q2 is turned on after the delay time t1 has elapsed since the switching element Q2 was turned on, and is turned off after the delay time t1 has elapsed since the switching element Q2 was turned off.

  Next, the control signal XP is activated after the elapse of the delay time t5 from the activation of the drive signal DR1, and the delay time t3 (third delay time) is added to the delay time t5 from the deactivation of the drive signal DR1. Then, the controller 2 controls to return to the inactive state after the elapse of time t5 + t3. On the other hand, the control signal YP is controlled by the control unit 2 so as to be activated after the delay time t5 has elapsed from the deactivation of the drive signal DR1 and to be deactivated after the time t5 + t3 has elapsed from the activation of the drive signal DR1. The Thereby, the switching element Q7 is turned off after the elapse of the delay time t3 since the switching element Q5 is turned on, and the switching element Q5 is turned off after the elapse of the delay time t3 after the switching element Q7 is turned on. Become.

  Next, the control signal XN is activated after elapse of time t5 + t4 obtained by adding the delay time t4 (fourth delay time) to the delay time t5 from the activation of the drive signal DR2, and the drive signal DR2 is inactivated. Control unit 2 controls to return to the inactive state after elapse of time t5 + t4 + t3, which is obtained by adding delay time t3 to time t5 + t4. On the other hand, the control signal YN is controlled by the control unit 2 so as to be activated after the elapse of time t5 + t4 from the deactivation of the drive signal DR2 and to be deactivated after the elapse of time t5 + t4 + t3 from the activation of the drive signal DR2. . Thereby, the switching element Q8 is turned off after the lapse of the delay time t3 since the switching element Q6 is turned on, and the switching element Q6 is turned off after the lapse of the delay time t3 after the switching element Q8 is turned on. Become. Further, the switching element Q6 is turned on after a lapse of time t1 + t4 since the switching element Q5 is turned on, and is turned off after a lapse of time t1 + t4 after the switching element Q5 is turned off. It is turned on after elapse of time t1 + t4 since Q7 was turned on, and turned off after elapse of time t1 + t4 after switching element Q7 was turned off.

  With the change in the on / off state of the switching elements Q1 to Q8 as described above, the full bridge type bidirectionally insulated DC / DC converter 1 does not particularly switch the control method of the switching elements Q1 to Q8 between power running and regeneration. During power running, power can be transmitted from the power source P1 to the power source P2, and during regeneration, power can be transmitted from the power source P2 to the power source P1.

  Here, the delay time t2 is a dead time provided to prevent a short circuit from occurring in the primary side inverter circuit IV1, and the delay time t3 is a cutoff of the coil L1 in the secondary side inverter circuit IV2. This is the overlap time provided to prevent the The delay time t5 is provided to prevent current from being generated by the parasitic inductor. Therefore, in an ideal state where occurrence of a short circuit in the primary side inverter circuit IV1, interruption of the coil L1 in the secondary side inverter circuit IV2, and generation of current due to the parasitic inductor can be ignored, the delay times t2, t3, and t5 are each 0. Can be set. The delay time t4 is provided to increase the power transmission time during regeneration by a time t4-t5 (short when t4 is negative) with respect to the power transmission time during power running. The basic operation of the full-bridge bidirectionally insulated DC / DC converter 1 is that when t4 = 0. Therefore, in the following, the principle that the full bridge type bidirectionally insulated DC / DC converter 1 exhibits the above-described effect will be described in detail with reference to an ideal operation in which the delay times t2 to t5 are all zero. In the following description, the snubber circuit S shown in FIG. 1 and its effects are also ignored.

  First, a description will be given focusing on powering. The operation of the control unit 2 regarding the switching elements Q1 to Q4 of the primary side inverter circuit IV1 is complementary to the control signals UP and UN constituting the bridge circuit B1 according to the drive signal DR1, as shown in FIG. 3 and Table 1 below. On the other hand, the control signals VP and VN constituting the bridge circuit B2 are changed complementarily according to the drive signal DR2. As a result of this control, the control signal UP becomes active during the active period of the drive signal DR1 and becomes inactive during the inactive period of the drive signal DR1. Similarly, control signal UN is activated during the inactive period of drive signal DR1, and deactivated during the active period of drive signal DR1. The control signal VP becomes active during the active period of the drive signal DR2, and becomes inactive during the inactive period of the drive signal DR2. The control signal VN is activated during the inactive period of the drive signal DR2, and deactivated during the active period of the drive signal DR2.

  As a result of the control signals UP, UN, VP, and VN changing as described above, the primary-side inverter circuit IV1 has positive ends of the power supply P1 connected to both ends of the primary side of the transformer T1, as shown in Table 1 and FIG. A period S1 for connecting, a period S2 for shorting both ends of the primary side of the transformer T1, a period S3 for negatively connecting both ends of the power source P1 to both ends of the primary side of the transformer T1, and a period for shorting both ends of the primary side of the transformer T1 It will operate | move so that S4 may be repeated in order. Note that FIG. 4 illustrates each of the switching elements Q1 to Q8 as a simple one-circuit / one-contact switch for easy understanding, and a thick line indicates a current path.

  Next, the operation of the control unit 2 with respect to the switching elements Q5 to Q8 of the secondary side inverter circuit IV2 is performed by using the control signals XP and YP constituting the bridge circuit B3 as the drive signal DR1 as shown in FIG. The control signals XN and YN constituting the bridge circuit B4 are changed in a complementary manner in accordance with the drive signal DR2. As a result of this control, the control signal XP becomes active during the active period of the drive signal DR1, and becomes inactive during the inactive period of the drive signal DR1. Similarly, the control signal YP becomes active during the inactive period of the drive signal DR1, and becomes inactive during the active period of the drive signal DR1. The control signal XN becomes active during the active period of the drive signal DR2, and becomes inactive during the inactive period of the drive signal DR2. The control signal YN becomes active during the inactive period of the drive signal DR2, and becomes inactive during the active period of the drive signal DR2.

  As a result of the control signals XP, YP, XN, and YN changing as described above, the secondary side inverter circuit IV2 supplies power to both ends of the secondary side of the transformer T1 in the period S1, as shown in Table 2 and FIG. In the period S2, both ends of the power supply P2 are short-circuited via the coil L1, in the period S3, the secondary ends of the transformer T1 are negatively connected to both ends of the power supply P2, and in the period S4. It will operate | move so that the both ends of the power supply P2 may be short-circuited via the coil L1.

  In the period S1, since the primary side inverter circuit IV1 positively connects both ends of the power source P1 to both ends of the primary side of the transformer T1, the voltage V1 applied between both ends of the primary side of the transformer T1 is between the both ends of the power source P1. Equal to the voltage. At this time, since the both ends of the secondary side of the transformer T1 are positively connected to both ends of the power source P2 by the operation of the secondary side inverter circuit IV2, the voltage across the power source P1 is transmitted to the power source P2 via the transformer T1. Will be.

  In the period S3, since the primary side inverter circuit IV1 negatively connects both ends of the power source P1 to both ends of the primary side of the transformer T1, the voltage V1 applied between both ends of the primary side of the transformer T1 is the voltage of the power source P1. It becomes equal to the voltage obtained by reversing the sign of the voltage between both ends. At this time, both ends of the secondary side of the transformer T1 are negatively connected to both ends of the power source P2 by the operation of the secondary side inverter circuit IV2, so that the voltage across the power source P1 causes the transformer T1 to be similar to the period S1. Is transmitted to the power source P2.

  On the other hand, in the periods S2 and S4, since the primary-side inverter circuit IV1 short-circuits both ends of the primary side of the transformer T1, the voltage across the power supply P1 is not directly transmitted to the power supply P2. Absent. On the other hand, the electric power from the power source P1 is accumulated in the coil L1 during the periods S1 and S3, and the electric power accumulated in the coil L1 is supplied to the power source P2 in the periods S2 and S4.

  In this way, the full-bridge bidirectionally insulated DC / DC converter 1 during power running transmits the voltage across the power source P1 to the power source P2 and accumulates power in the coil L1 in the periods S1 and S3, and the periods S2 and S4. , The power source P1 is disconnected from the transformer T1, while the power is transmitted from the coil L1 to the power source P2. In short, this operation is a well-known operation of a step-down chopper. Hereinafter, this point will be described in detail with reference to FIGS. 5 and 6.

  As can be understood from the operation of the full-bridge bidirectionally insulated DC / DC converter 1 described so far, the full-bridge bidirectionally insulated DC / DC converter 1 includes a power supply P1 as shown in FIG. The switching elements Q1 to Q4 can be replaced by a switching element Q10 connected in series with the switching element Q10, and the switching elements Q5 to Q8 can be replaced by a switching element Q20 connected in parallel with the power source P2. However, the illustrated drive signal DR3 is an exclusive OR signal of the drive signal DR1 and the drive signal DR2, as shown in FIG. The drive signal DR3 is supplied to the gate electrode of the switching element Q10, and the inverted signal of the drive signal DR3 is supplied to the gate electrode of the switching element Q20.

  FIG. 5B is obtained by replacing the transformer T1 with an equivalent circuit in the circuit of FIG. As shown in the figure, the transformer T1 includes a primary side leakage inductance La and a secondary side leakage inductance Lb connected in series with the switching element Q10, and a mutual inductance M connected in parallel with the switching element Q20. Represented by

  If the transformer T1 is an ideal transformer, the leakage inductances La and Lb are both 0, and the mutual inductance M is infinite. Therefore, FIG. 5B is further rewritten as shown in FIG.

  In the circuit of FIG. 5C, as shown in FIG. 6, the state in which the switching element Q10 is on and the switching element Q20 is off corresponds to the periods S1 and S3, and the switching element Q10 is off. The state in which Q20 is on corresponds to the periods S2 and S4. In FIG. 6, as in FIG. 4, each of the switching elements Q <b> 10 and Q <b> 20 is illustrated as a simple one-circuit / one-contact switch for easy understanding. A thick line indicates a current path.

  As shown in FIG. 6A, in the periods S1 and S3, the power source P1 is connected in series with the power source P2, and the voltage across the power source P1 is transmitted to the power source P2. Further, electric power is accumulated in the coil L1. On the other hand, as shown in FIG. 6B, in the periods S2 and S4, the power source P1 is disconnected from the power source P2, and both ends of the power source P2 are short-circuited via the coil L1. And the electric power accumulate | stored in the coil L1 in period S1, S3 is supplied to the power supply P2. This operation is nothing but the well-known operation of a step-down chopper.

  Thus, the full bridge type bidirectional insulated DC / DC converter 1 during powering operates as a step-down chopper. Therefore, power can be transmitted from the power source P1 to the power source P2.

  Note that the amount of power transmitted from the power source P1 to the power source P2 varies depending on the ratio between the time lengths of the periods S1 and S3 and the time lengths of the periods S2 and S4. As understood from FIG. 3, the time lengths of the periods S1 and S3 are equal to the delay time t1, and the time lengths of the periods S2 and S4 are equal to T-t1, so that the power source P1 is adjusted by appropriately adjusting the delay time t1. The amount of power transmitted from the power source P2 to the power source P2 can be controlled.

  Next, a description will be given focusing on the regeneration. The operation of the control unit 2 during regeneration is exactly the same as during powering. Therefore, the change in the active state of each of the control signals UP, UN, VP, VN, XP, YP, XN, and YN and the change in the on / off state of each of the switching elements Q1 to Q8 are shown in FIGS. This is exactly the same as that during powering described with reference to Table 2.

  In periods S2 and S4 during regeneration, as shown in FIGS. 4B and 4D, the secondary inverter circuit IV2 short-circuits both ends of the power supply P2 via the coil L1. Therefore, the voltage across the power source P2 is not directly transmitted to the power source P1, but the power supplied from the power source P2 is accumulated in the coil L1. The electric power stored in the coil L1 serves to boost the voltage transmitted to the power source P1 in the periods S1 and S3.

  In the regeneration period S1, as shown in FIG. 4A, both ends of the power source P2 are positively connected to both ends of the secondary side of the transformer T1 by the secondary side inverter circuit IV2. At this time, since the coil L1 is connected between one end of the power source P2 and one end of the transformer T1, the voltage V2 applied between both ends of the secondary side of the transformer T1 is the voltage between both ends of the power source P2. , Equal to the voltage obtained by adding the voltage across the coil L1 generated by the power accumulated in the period S4. At this time, both ends of the primary side of the transformer T1 are positively connected to both ends of the power source P1 by the operation of the primary side inverter circuit IV1, so that the voltage is transmitted to the power source P1 via the transformer T1. .

  Similarly, in the period S3 during regeneration, as shown in FIG. 4C, both ends of the power source P2 are negatively connected to both ends of the secondary side of the transformer T1 by the secondary side inverter circuit IV2. At this time, since the coil L1 is connected between one end of the power supply P2 and the other end of the transformer T1, the voltage V2 applied across the secondary side of the transformer T1 is the voltage across the power supply P2. And the voltage obtained by inverting the sign of the voltage obtained by adding the voltage across the coil L1 generated by the electric power accumulated in the period S2. At this time, both ends of the primary side of the transformer T1 are negatively connected to both ends of the power source P1 by the operation of the primary side inverter circuit IV1, so that the voltage is transmitted to the power source P1 via the transformer T1. .

  As described above, the full-bridge bidirectionally insulated DC / DC converter 1 during regeneration stores the power from the power source P2 to the coil L1 while disconnecting the power source P1 from the transformer T1 during the periods S2 and S4. In S3, an operation is performed so as to transmit power to the power supply P1 by adding a voltage between both ends of the power supply P2 and a voltage between both ends of the coil L1 generated by the power accumulated in the period S2. In short, this operation is a well-known operation of a boost chopper. Hereinafter, this point will be described in detail with reference to FIG. 6 again.

  As shown in FIG. 6B, in periods S2 and S4, the power source P1 is disconnected from the power source P2, and both ends of the power source P2 are short-circuited via the coil L1. As a result, the electric power supplied from the power source P2 is accumulated in the coil L1. On the other hand, as shown to Fig.6 (a), in period S1, S3, the power supply P1, the coil L1, and the power supply P2 are connected in series. Therefore, the power source P1 is supplied with a voltage obtained by adding the voltage across the power source P2 and the voltage across the coil L1 generated by the power accumulated in the immediately preceding period S2 or S4. This operation is nothing but the well-known operation of the boost chopper.

  As described above, the full-bridge bidirectionally insulated DC / DC converter 1 at the time of regeneration operates as a step-up chopper. Therefore, power can be transmitted from the power source P2 to the power source P1.

  Note that the amount of power transmitted from the power source P2 to the power source P1 varies according to the ratio between the time lengths of the periods S1 and S3 and the time lengths of the periods S2 and S4, as in powering. Therefore, the amount of power transmitted from the power source P2 to the power source P1 can be controlled by appropriately adjusting the delay time t1.

  As described above, the full-bridge bidirectionally insulated DC / DC converter 1 operates as a step-down chopper during power running and does not require switching between the control methods of the switching elements Q1 to Q8 during power running and regeneration. Operates as a boost chopper. Therefore, power is transmitted from the power source P1 to the power source P2 during power running and power is transmitted from the power source P2 to the power source P1 during regeneration without particularly switching the control method of the switching elements Q1 to Q8 during power running and regeneration. Is possible.

  Next, returning to FIG. 1 and FIG. 2, a supplementary explanation about the flow of current and an operation of the snubber circuit S will be given.

  First, the current flow during powering will be described. During power running, when switching element Q1 is turned on at time A shown in FIG. 2, application of voltage from power supply P1 to the primary side of transformer T1 is started, and voltage V1 rises as shown in FIG. At this time, as shown in FIG. 2, a surge component appears in the current I1 flowing on the primary side of the transformer T1 because the current temporarily flows into the capacitor C1 in the snubber circuit S.

  Next, when the switching element Q4 is turned off at the time point B shown in FIG. 2, the power source P1 is disconnected from the primary side of the transformer T1, but for a short time (period shown in FIG. 2) through the parasitic capacitance of the switching element Q4. During δt1, the current I1 continues to flow. The drain-source voltage of the switching element Q4 rises due to the current I1 that continues to flow, and the body diode of the switching element Q3 is turned on, so that both ends of the primary side of the transformer T1 are short-circuited to the primary side of the transformer T1. The application of the voltage stops. Thereafter, at time C when the electromotive force of the leakage inductance of the transformer T1 disappears, the current I1 becomes zero.

  From the time point A to the time point C, since the switching elements Q5 and Q8 are turned on in the secondary inverter circuit IV2, the coil L1 is charged by the voltage V2 induced by the voltage V1. After the current I1 becomes 0 at time C, the body diode of the switching element Q7 is turned on by the electromotive force of the coil L1. As a result, a current path connecting the coil L1, the switching elements Q7, Q8, and the power source P2 is formed, and the current flows back to the power source P2.

  Next, the current flow during regeneration will be described. During regeneration, when the switching element Q7 is turned off at the time point F shown in FIG. 2, application of voltage from the power source P2 to the secondary side of the transformer T1 is started, and the voltage V2 increases as shown in FIG.

  Next, when the switching element Q6 is turned on at the time point D shown in FIG. 2, the secondary side inverter circuit IV2 is short-circuited, and the application of voltage from the power source P2 to the secondary side of the transformer T1 is stopped. However, current continues to be supplied to the primary inverter circuit IV1 due to the electromotive force of the leakage inductance of the transformer T1.

  Here, after the electromotive force of the leakage inductance of the transformer T1 disappears, a voltage is applied to the leakage inductance in the opposite direction by the power regenerated by the power source P1, and a current from the primary side to the secondary side is generated. In order to prevent this invalid current from flowing, the control unit 2 quickly turns on the switching element Q3 at the timing when the electromotive force possessed by the leakage inductance of the transformer T1 disappears. When the switching element Q3 is turned on, the primary side of the transformer T1 is short-circuited, so that the application of the reverse voltage as described above is stopped.

  Next, the snubber circuit S is a circuit that plays a role of preventing a surge voltage from being generated in the secondary inverter circuit IV2. That is, in the secondary side inverter circuit IV2, when the switching element Q1 is turned on, when the switching element Q2 is turned on, when the switching element Q5 is turned off, and when the switching element Q7 is turned off, Surge voltage is generated. The snubber circuit S prevents the occurrence of this surge voltage by accumulating the generated high voltage in the capacitor C1 via the diode D1.

  Here, in order to appropriately prevent the generation of the surge voltage, the voltage between the plates of the capacitor C1 is set to a certain level, specifically, the normal voltage V2 applied across the secondary side of the transformer T1. It is necessary to keep the peak voltage (peak voltage when no surge voltage is generated). If the voltage between the plates of the capacitor C1 is too large, it becomes impossible to store the voltage and it becomes impossible to suppress the generation of the surge voltage. On the other hand, if the voltage between the plates of the capacitor C1 is too small, the voltage that is not the surge voltage This is because the efficiency of the full-bridge bidirectionally insulated DC / DC converter 1 is lowered. Therefore, as shown in FIG. 2, the control unit 2 controls the control signal SN so that the switching element Q9 is repeatedly turned on and off at a predetermined cycle. When the switching element Q9 is on, the charge accumulated in the capacitor C1 is absorbed by the power source P2, and when the switching element Q9 is off, the charge is accumulated in the capacitor C1, so that the control unit 2 By controlling the control signal SN as described above, the voltage between the plates of the capacitor C1 can be maintained at the above-mentioned constant level. In the example of FIG. 2, the control unit 2 activates the control signal SN at the timing when the switching elements Q6 and Q8 are turned on. However, the control signal SN may be activated at other timing. Further, the cycle in which the switching element Q9 is repeatedly turned on and off is preferably T / 2 as shown in FIG. 2 because the generation cycle of the surge voltage is repeated at a cycle of T / 2.

  The switching element Q9 has a role as a brake during regeneration in addition to the above role. That is, when it is necessary to stop the full-bridge type bidirectionally insulated DC / DC converter 1 urgently, if it is during power running, all the switching elements Q1 to Q4 in the primary-side inverter circuit IV1 are turned off to The system bidirectionally insulated DC / DC converter 1 can be stopped. On the other hand, at the time of regeneration, if all the switching elements Q5 to Q8 in the secondary inverter circuit IV2 are turned off, the full-bridge bidirectionally insulated DC / DC converter 1 can be stopped as in the case of powering. When such control is actually performed, the switching elements Q5 to Q8 are destroyed due to the current generated in the coil L1. Therefore, when an emergency stop is required at the time of regeneration, the control unit 2 turns on the switching element Q9 by activating the control signal SN to secure a discharge path for the current generated in the coil L1, and then the switching element Q5. Turn off ~ Q8. By doing so, the full-bridge bidirectionally insulated DC / DC converter 1 can be urgently stopped even during regeneration without causing the destruction of the switching elements Q5 to Q8.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to such embodiment at all, and this invention can be implemented in various aspects in the range which does not deviate from the summary. Of course.

DESCRIPTION OF SYMBOLS 1 Full bridge system bidirectional insulation DC / DC converter 2 Control part B1-B4 Bridge circuit C1 Capacitor D1, D2 Diode DR1-DR3 Drive signal IV1 Primary side inverter circuit IV2 Secondary side inverter circuit L1, L2 Coil La, Lb Transformer T1 Leakage inductance M mutual inductance P1, P2 power supply Q1-Q9, Q10, Q20 switching element S snubber circuit T1 transformer UP, UN, VP, VN, XP, XN, YP, YN, SN control signal

Claims (6)

With a transformer,
A first coil having one end connected to one end of a second power source;
A first switching element having one end connected to one end of the first power supply and the other end connected to one end of the primary side of the transformer;
A second switching element having one end connected to one end of the primary side of the transformer and the other end connected to the other end of the first power source;
A third switching element having one end connected to one end of the first power supply and the other end connected to the other end of the primary side of the transformer;
A fourth switching element having one end connected to the other end of the primary side of the transformer and the other end connected to the other end of the first power source;
A fifth switching element having one end connected to the other end of the first coil and the other end connected to one end on the secondary side of the transformer;
A sixth switching element having one end connected to one end on the secondary side of the transformer and the other end connected to the other end of the second power source;
A seventh switching element having one end connected to the other end of the first coil and the other end connected to the other end of the secondary side of the transformer;
An eighth switching element having one end connected to the other end of the secondary side of the transformer and the other end connected to the other end of the second power source;
A controller for controlling on / off of the first to eighth switching elements,
The control unit controls on / off states of the first, second, fifth, and seventh switching elements according to a first drive signal that repeats an active state and an inactive state at a predetermined cycle, The on-off state of the third, fourth, sixth, and eighth switching elements is controlled according to the active state of the second drive signal obtained by shifting the phase of the drive signal.
The controller is
Turning on each of the first and fifth switching elements in response to activation of the first drive signal and turning off each of the second and seventh switching elements;
Turning on each of the second and seventh switching elements in response to deactivation of the first drive signal and turning off each of the first and fifth switching elements;
In response to the activation of the second drive signal, each of the third and sixth switching elements is turned on and each of the fourth and eighth switching elements is turned off.
Each of the fourth and eighth switching elements is turned on in response to the deactivation of the second drive signal, and each of the third and sixth switching elements is turned off. full Ruburijji scheme bidirectional insulated DC / DC converter shall be the features. The controller is
Turning on the first switching element after a second delay time has elapsed since turning off the second switching element;
After turning off the first switching element and turning on the second switching element after the second delay time has elapsed,
After turning off the fourth switching element and turning on the third switching element after the second delay time has elapsed,
The third full-bridge bidirectional claim 1, characterized in that configured to turn on the fourth switching element after a second delay time of the switching element off and then on Isolated DC / DC converter. The controller is
After the third delay time has elapsed since turning on the fifth switching element, turning off the seventh switching element,
Turning on the fifth switching element after the third delay time has elapsed since turning on the seventh switching element;
After the third delay time has elapsed since turning on the sixth switching element, turning off the eighth switching element;
The full bridge system according to claim 1 or 2 , wherein the sixth switching element is turned off after the third delay time has elapsed since the eighth switching element was turned on. Bidirectional insulated DC / DC converter. The second drive signal is configured to be activated after a first delay time from the activation of the first drive signal;
The controller is
Turning on the third switching element after the first delay time has elapsed since turning on the first switching element;
Turning on the fourth switching element after the first delay time has elapsed since turning on the second switching element;
Turning off the third switching element after elapse of the first delay time since turning off the first switching element;
Turning off the fourth switching element after elapse of the first delay time since turning off the second switching element;
Turning on the sixth switching element after the first delay time has elapsed since turning on the fifth switching element;
Turning on the eighth switching element after the first delay time has elapsed since turning on the seventh switching element;
Turning off the sixth switching element after elapse of the first delay time since turning off the fifth switching element;
To any one of claims 1 to 3, characterized in that configured to the seventh of the eighth off the switching element after a switching element and the first delay time after turning off the Full-bridge bidirectional DC / DC converter as described. A second coil having one end connected to one end of the first coil;
A first diode having an anode connected to the other end of the first coil;
A ninth switching element having one end connected to the cathode of the first diode and the other end connected to the other end of the second coil;
A second diode having an anode connected to the other end of the second power supply and a cathode connected to the other end of the ninth switching element;
One end connected to the other end of the second power source, to any one of claims 1 to 4 other end and further comprising a capacitor connected to one end of the ninth switching element Full-bridge bidirectional DC / DC converter as described. The controller is configured to turn off the fifth to eighth switching elements after turning on the ninth switching element when the fifth to eighth switching elements are simultaneously turned off. The full-bridge bidirectionally isolated DC / DC converter according to claim 5 .

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