Power conversion device

Abstract

To obtain a power conversion device capable of improving robustness of an operation for stopping a switching operation.SOLUTION: A power conversion device according to an embodiment of the present disclosure includes an input power terminal, a switching circuit, a first driving circuit capable of performing a first driving operation for driving the switching circuit and capable of stopping the first driving operation based on a first driving control signal, a transformer including first and second windings, and a rectifier circuit including a first rectification switching element capable of being turned on and off based on a first driving signal and capable of rectifying a signal supplied from the second winding. The switching power supply device includes a second driving circuit capable of stopping a second driving operation based on a second driving control signal corresponding to a control signal, a signal generation circuit capable of generating a first driving control signal based on the control signal and a first driving signal, a smoothing circuit, and an output power terminal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device that converts electric power. [Background technology]

[0002] Some power conversion devices have a switching circuit having a switching element on the primary side of a transformer and a rectifier circuit having a switching element on the secondary side of the transformer. For example, Patent Document 1 discloses a technique for stopping the operation of a power conversion device by stopping the operation of the switching element of the rectifier circuit on the secondary side and then stopping the operation of the switching element of the switching circuit on the primary side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-215356 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power conversion device, it is desirable to stop the switching operation of the primary side circuit after stopping the switching operation of the secondary side circuit, and it is expected that the robustness of the operation of stopping such switching operation will be improved.

[0005] It is desirable to provide a power conversion device that can improve the robustness of the operation of stopping the switching operation. [Means for solving the problem]

[0006] The power conversion device of the present invention includes an input power terminal, a switching circuit, a first drive circuit, a transformer, a rectifier circuit, a second drive circuit, a signal generating circuit, a smoothing circuit, and an output power terminal. The switching circuit is connected to the input power terminal and is capable of performing a switching operation. The first drive circuit is capable of performing a first drive operation to drive the switching circuit and is capable of stopping the first drive operation based on a first drive control signal. The transformer has a first winding and a second winding connected to the switching circuit. The rectifier circuit is connected to the second winding and has a first rectifier switching element that can be turned on and off based on the first drive signal, and is capable of rectifying a signal supplied from the second winding by performing a switching operation. The second drive circuit is capable of generating a first drive signal and is capable of performing a second drive operation to drive the first rectifier switching element using the first drive signal and is capable of stopping the second drive operation based on a second drive control signal corresponding to the control signal. The signal generating circuit is capable of generating a first drive control signal based on the control signal and the first drive signal. The smoothing circuit is capable of smoothing the voltage rectified by the rectifying circuit. The output power terminal is connected to the smoothing circuit. [Effects of the Invention]

[0007] According to the power conversion device of the present invention, it is possible to improve the robustness of the operation of stopping the switching operation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram illustrating an example of the configuration of the signal generating circuit shown in FIG. [Figure 3] FIG. 3 is a timing waveform diagram illustrating an example of the operation of the power conversion device shown in FIG. [Figure 4A] FIG. 4A is an explanatory diagram illustrating one operating state of the power conversion device shown in FIG. [Figure 4B] FIG. 4B is an explanatory diagram showing another operating state of the power conversion device shown in FIG. [Figure 5] FIG. 5 is a timing waveform diagram showing an example of an operation for starting a switching operation in the power conversion device shown in FIG. [Figure 6] FIG. 6 is a timing waveform diagram showing an example of an operation for stopping a switching operation in the power conversion device shown in FIG. [Figure 7] FIG. 7 is a circuit diagram illustrating an example of the configuration of a signal generating circuit according to a modified example. [Figure 8] FIG. 8 is a circuit diagram illustrating an example of the configuration of a power conversion device according to another modified example. [Figure 9] FIG. 9 is a circuit diagram illustrating an example of the configuration of the signal generating circuit shown in FIG. [Figure 10] FIG. 10 is a timing waveform diagram showing an example of an operation for stopping a switching operation in the power conversion device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] [Configuration example] 1 shows an example of the configuration of a power conversion device (power conversion device 1) according to an embodiment of the present invention. The power conversion device 1 has input power terminals T11 and T12 and output power terminals T21 and T22. The input power terminals T11 and T12 are connected to a high-voltage battery BH, and the output power terminals T21 and T22 are connected to a low-voltage battery BL. The voltage of the high-voltage battery BH is, for example, 400 V, and the voltage of the low-voltage battery BL is, for example, 12 V. The power conversion device 1 is configured to convert power by stepping down the voltage supplied from the high-voltage battery BH and supply the converted power to the low-voltage battery BL.

[0011] The power conversion device 1 includes a capacitor 11, a switching circuit 12, a transformer 13, a rectifier circuit 14, a smoothing circuit 20, a voltage sensor 15, a control circuit 19, drive circuits 31 and 32, capacitors C1 and C2, an interface circuit 33, and a signal generating circuit 34. The high-voltage battery BH, the capacitor 11, and the switching circuit 12 form a primary circuit of the power conversion device 1, while the rectifier circuit 14, the smoothing circuit 20, the voltage sensor 15, and the low-voltage battery BL form a secondary circuit of the power conversion device 1. In the power conversion device 1, the input power terminal T11 is connected to the voltage line L11, and the input power terminal T12 is connected to the reference voltage line L12. The output power terminal T21 is connected to the voltage line L21B, and the output power terminal T22 is connected to the reference voltage line L22.

[0012] One end of the capacitor 11 is connected to the voltage line L11, and the other end is connected to the reference voltage line L12.

[0013] The switching circuit 12 is configured to convert a DC voltage supplied from the high-voltage battery BH into an AC voltage by performing a switching operation. The switching circuit 12 is a full-bridge circuit and includes transistors SA, SB, SC, and SD. The transistors SA to SD are switching elements that perform switching operations based on drive signals GA to GD, respectively. The transistors SA to SD are configured using, for example, N-type field effect transistors (FETs). Each of the transistors SA to SD has a body diode. For example, the anode of the body diode of the transistor SA is connected to the source of the body of the transistor SA, and the cathode is connected to the drain of the body of the transistor SA. The same is true for the transistors SB to SD. Note that, although an N-type field effect transistor is used in this example, any switching element may be used.

[0014] The transistor SA is provided in a path connecting the voltage line L11 and the node N1, and is configured to connect the node N1 to the voltage line L11 when it is turned on. The drain of the transistor SA is connected to the voltage line L11, the gate is supplied with a drive signal GA, and the source is connected to the node N1. The transistor SB is provided in a path connecting the node N1 and the reference voltage line L12, and is configured to connect the node N1 to the reference voltage line L12 when it is turned on. The drain of the transistor SB is connected to the node N1, the gate is supplied with a drive signal GB, and the source is connected to the reference voltage line L12.

[0015] The transistor SC is provided in a path connecting the voltage line L11 and the node N2, and is configured to connect the node N2 to the voltage line L11 when it is turned on. The drain of the transistor SC is connected to the voltage line L11, the gate is supplied with a drive signal GC, and the source is connected to the node N2. The transistor SD is provided in a path connecting the node N2 and the reference voltage line L12, and is configured to connect the node N2 to the reference voltage line L12 when it is turned on. The drain of the transistor SD is connected to the node N2, the gate is supplied with a drive signal GD, and the source is connected to the reference voltage line L12.

[0016] Transformer 13 insulates the primary circuit from the secondary circuit in terms of DC current and connects them in terms of AC current. Transformer 13 converts AC voltage supplied from the primary circuit using the transformation ratio of transformer 13 and supplies the converted AC voltage to the secondary circuit. Transformer 13 has windings 13A, 13B, and 13C. Winding 13A is a primary winding, and one end is connected to node N1 of switching circuit 12 and the other end is connected to node N2 of switching circuit 12. Windings 13B and 13C are secondary windings. One end of winding 13B is connected to the drain of transistor SF (described later) in rectifier circuit 14, and the other end is connected to voltage line L21A. Winding 13C is connected to voltage line L21A and the other end is connected to the drain of transistor SE (described later) in rectifier circuit 14.

[0017] The rectifier circuit 14 is configured to rectify the AC voltage output from the windings 13B and 13C of the transformer 13. The rectifier circuit 14 has transistors SE and SF. The transistors SE and SF are switching elements that perform switching operations based on drive signals GE and GF, respectively. The transistors SE and SF are configured using, for example, N-type field effect transistors. Like the transistors SA to SD, each of the transistors SE and SF has a body diode. Note that in this example, N-type field effect transistors are used, but any switching element may be used.

[0018] Transistor SE is configured to connect the other end of winding 13C of transformer 13 to reference voltage line L22 when turned on. The drain of transistor SE is connected to the other end of winding 13C of transformer 13, a drive signal GE is supplied to its gate, and a source is connected to reference voltage line L22. Transistor SF is configured to connect one end of winding 13B of transformer 13 to reference voltage line L22 when turned on. The drain of transistor SF is connected to one end of winding 13B of transformer 13, a drive signal GF is supplied to its gate, and a source is connected to reference voltage line L22.

[0019] The smoothing circuit 20 is configured to smooth the voltage rectified by the rectifier circuit 14. The smoothing circuit 20 has an inductor 21 and a capacitor 22. One end of the inductor 21 is connected to the voltage line L21A, and the other end is connected to the voltage line L21B. One end of the capacitor 22 is connected to the voltage line L21B, and the other end is connected to the reference voltage line L22.

[0020] The voltage sensor 15 is configured to detect the voltage VL on the voltage line L21B. One end of the voltage sensor 15 is connected to the voltage line L21B, and the other end is connected to the reference voltage line L22. The voltage VL is the voltage on the voltage line L21B relative to the voltage on the reference voltage line L22. The voltage sensor 15 detects this voltage VL and supplies the detection result of this voltage VL to the control circuit 19.

[0021] The control circuit 19 is configured to control the switching operation of the switching circuit 12 and the switching operation of the rectifier circuit 14 based on the detection result of the voltage sensor 15, thereby controlling the operation of the power conversion device 1. The control circuit 19 generates control signals GA1 to GD1 and controls the switching operation of the switching circuit 12 via the drive circuit 31 using these control signals GA1 to GD1. The control circuit 19 also generates control signals GE1 and GF1 and controls the switching operation of the rectifier circuit 14 via the drive circuit 32 using these control signals GE1 and GF1. The control circuit 19 controls the switching operation of the switching circuit 12 and the switching operation of the rectifier circuit 14 based on the detection result of the voltage sensor 15 so as to maintain the voltage VL at a predetermined voltage. The control circuit 19 also operates based on instructions supplied from an external device via the interface circuit 33. The control circuit 19 may be configured using, for example, a microcontroller.

[0022] The drive circuit 31 is configured to drive the transistors SA to SD of the switching circuit 12 based on the control signals GA1 to GD1. The drive circuit 31 generates drive signals GA to GD, respectively, based on the control signals GA1 to GD1, and drives the transistors SA to SD using these drive signals GA to GD, respectively. The drive circuit 31 also starts or stops driving the transistors SA to SD based on a drive control signal SCTL1 supplied to an enable terminal ENB.

[0023] One end of the capacitor C1 is connected to the enable terminal ENB of the drive circuit 31, and the other end is grounded.

[0024] The drive circuit 32 is configured to drive the transistors SE and SF of the rectifier circuit 14 based on the control signals GE1 and GF1. The drive circuit 32 generates drive signals GE and GF, respectively, based on the control signals GE1 and GF1, and drives the transistors SE and SF using these drive signals GE and GF. The drive circuit 32 also starts or stops driving the transistors SE and SF based on a drive control signal SCTL2 that is supplied to an enable terminal ENB and corresponds to a drive control signal SCTL (described below).

[0025] One end of the capacitor C2 is connected to the enable terminal ENB of the drive circuit 32, and the other end is grounded.

[0026] The interface circuit 33 is configured to be able to communicate with an external device (not shown). For example, the interface circuit 33 receives an instruction from the external device and transmits the instruction to the control circuit 19. The interface circuit 33 also transmits, for example, information about the operating state of the power conversion device 1, supplied from the control circuit 19, to the external device. For example, when the interface circuit 33 receives an instruction to start or stop a switching operation from the external device, the interface circuit 33 generates a drive control signal SCTL in accordance with the instruction and outputs the generated drive control signal SCTL from the output terminal CTL. The interface circuit 33 is configured using, for example, a microcontroller.

[0027] The signal generating circuit 34 is configured to generate a drive control signal SCTL1 based on the drive control signal SCTL generated by the interface circuit 33 and the drive signal GE generated by the drive circuit 32.

[0028] Fig. 2 shows an example of the configuration of the signal generating circuit 34. In addition to the signal generating circuit 34, Fig. 2 also shows the control circuit 19, drive circuits 31 and 32, and capacitors C1 and C2.

[0029] The signal generating circuit 34 has diodes 41 and 42, a resistive element 43, a capacitor 44, and resistive elements 45 and 46. A drive control signal SCTL is supplied from the interface circuit 33 to an input node NI1 of the signal generating circuit 34, a drive signal GE is supplied from the drive circuit 32 to an input node NI2, and an output node NO is connected to the enable terminal ENB of the drive circuit 31.

[0030] The anode of the diode 41 is connected to the input node NI1, and the cathode is connected to the output node NO. The anode of the diode 42 is connected to the input node NI2, and the cathode is connected to one end of the resistor element 43.

[0031] One end of the resistor element 43 is connected to the cathode of the diode 42, and the other end is connected to one end of the capacitor 44 and one end of the resistor element 45. One end of the capacitor 44 is connected to the other end of the resistor element 43 and one end of the resistor element 45, and the other end is grounded. The resistor element 43 and the capacitor 44 form a low-pass filter LPF.

[0032] One end of resistor element 45 is connected to the other end of resistor element 43 and one end of capacitor 44, and the other end is connected to output node N0. One end of resistor element 46 is connected to output node N0, and the other end is grounded. Resistor elements 45 and 46 form a voltage divider circuit.

[0033] With this configuration, the signal generation circuit 34 generates the drive control signal SCTL1 based on the drive control signal SCTL and the drive signal GE. As a result, in the power conversion device 1, when stopping the switching operation, the drive circuit 32 stops generating the drive signals GE and GF, and then the drive circuit 31 stops generating the drive signals GA to GD.

[0034] Here, the input power terminals T11 and T12 correspond to a specific example of an "input power terminal" in an embodiment of the present disclosure. The switching circuit 12 corresponds to a specific example of a "switching circuit" in an embodiment of the present disclosure. The drive circuit 31 corresponds to a specific example of a "drive circuit" in an embodiment of the present disclosure. The drive control signal SCTL1 corresponds to a specific example of a "first drive control signal" in an embodiment of the present disclosure. The transformer 13 corresponds to a specific example of a "transformer" in an embodiment of the present disclosure. The winding 13A corresponds to a specific example of a "first winding" in an embodiment of the present disclosure. The winding 13C corresponds to a specific example of a "second winding" in an embodiment of the present disclosure. The rectifier circuit 14 corresponds to a specific example of a "rectifier circuit" in an embodiment of the present disclosure. The transistor SE corresponds to a specific example of a "first rectifier switching element" in an embodiment of the present disclosure. The drive circuit 32 corresponds to a specific example of a "drive circuit" in an embodiment of the present disclosure. The drive signal GE corresponds to a specific example of a "first drive signal" in an embodiment of the present disclosure. The drive control signal SCTL2 corresponds to a specific example of a "second drive control signal" in an embodiment of the present disclosure. The signal generation circuit 34 corresponds to a specific example of a "signal generation circuit" in an embodiment of the present disclosure. The drive control signal SCTL corresponds to a specific example of a "control signal" in an embodiment of the present disclosure. The smoothing circuit 20 corresponds to a specific example of a "smoothing circuit" in an embodiment of the present disclosure. The output power terminals T21 and T22 correspond to a specific example of an "output power terminal" in an embodiment of the present disclosure.

[0035] The input node NI1 corresponds to a specific example of a "first input node" in an embodiment of the present disclosure. The input node NI2 corresponds to a specific example of a "second input node" in an embodiment of the present disclosure. The output node NO corresponds to a specific example of an "output node" in an embodiment of the present disclosure. The diode 41 corresponds to a specific example of a "first diode" in an embodiment of the present disclosure. The diode 42 corresponds to a specific example of a "second diode" in an embodiment of the present disclosure. The low-pass filter LPF corresponds to a specific example of a "low-pass filter" in an embodiment of the present disclosure. The voltage divider circuit DIV corresponds to a specific example of a "voltage divider circuit" in an embodiment of the present disclosure. The resistive elements 45 and 46 correspond to a specific example of a "plurality of resistive elements" in an embodiment of the present disclosure.

[0036] [Actions and Actions] Next, the operation and function of the power conversion device 1 of this embodiment will be described.

[0037] (Overview of overall operation) First, referring to FIG. 1, an overview of the overall operation of the power conversion device 1 will be described. Drive circuit 31 generates drive signals GA-GD based on control signals GA1-GD1. Switching circuit 12 converts the DC voltage supplied from high-voltage battery BH into an AC voltage by performing a switching operation based on drive signals GA-GD. Transformer 13 insulates the primary circuit from the secondary circuit in terms of DC and connects them in terms of AC, converts the AC voltage supplied from the primary circuit using the transformation ratio of transformer 13, and supplies the converted AC voltage to the secondary circuit. Drive circuit 32 generates drive signals GE and GF based on control signals GE1 and GF1. Rectifier circuit 14 rectifies the AC voltage output from windings 13B and 13C of transformer 13 by performing a switching operation based on drive signals GE and GF. Smoothing circuit 20 smoothes the voltage rectified by rectifier circuit 14. Voltage sensor 15 detects voltage VL on voltage line L21A. The control circuit 19 controls the switching operation of the switching circuit 12 and the switching operation of the rectifier circuit 14 based on the detection result of the voltage sensor 15, thereby controlling the operation of the power conversion device 1. The control circuit 19 generates control signals GA1 to GD1, and uses these control signals GA1 to GD1 to control the switching operation of the switching circuit 12 via the drive circuit 31. The control circuit 19 also generates control signals GE1 and GF1, and uses these control signals GE1 and GF1 to control the switching operation of the rectifier circuit 14 via the drive circuit 32.

[0038] The interface circuit 33 receives, for example, instructions from an external device and transmits these instructions to the control circuit 19. The interface circuit 33 also transmits, for example, information about the operating state of the power conversion device 1, supplied from the control circuit 19, to the external device. When the interface circuit 33 receives, for example, an instruction to start or stop a switching operation from an external device, it generates a drive control signal SCTL in response to the instruction and outputs the generated drive control signal SCTL from the output terminal CTL. The drive circuit 32 starts or stops driving the transistors SE and SF based on a drive control signal SCTL2 supplied to the enable terminal ENB in ​​response to the drive control signal SCTL. The signal generation circuit 34 generates a drive control signal SCTL1 based on the drive control signal SCTL and the drive signal GE. The drive circuit 31 starts or stops driving the transistors SA to SD based on the drive control signal SCTL1 supplied to the enable terminal ENB.

[0039] (Detailed operation) 3 shows an example of operation of the power conversion device 1, where (A) to (D) respectively show the waveforms of the drive signals GA to GD, and (E) shows the power transfer operation from the primary side circuit to the secondary side circuit in the power conversion device 1. The power conversion device 1 transfers power from the primary side circuit to the secondary side circuit during a period T when the waveform shown in Fig. 3(E) is at a high level.

[0040] At timing t1, the drive circuit 31 changes the drive signal GD from low to high based on the control signal GD1 (FIG. 3(D)), which changes the transistor SD from an off state to an on state.

[0041] Next, at timing t2, the drive circuit 31 changes the drive signal GB from high to low based on the control signal GB1 (FIG. 3(B)), thereby changing the transistor SB from an on state to an off state.

[0042] Next, at timing t3, the drive circuit 31 changes the drive signal GA from low level to high level based on the control signal GA1 (FIG. 3(A)), thereby changing the transistor SA from an off state to an on state.

[0043] Next, at timing t4, the drive circuit 31 changes the drive signal GD from high to low based on the control signal GD1 (FIG. 3(D)), thereby changing the transistor SD from an on state to an off state.

[0044] In this way, the transistors SA and SD are both in the ON state during the period T from timing t3 to t4. During this period T, the drive signals GB and GC are at a low level, so the transistors SB and SC are both in the OFF state.

[0045] 4A shows one operating state of the power conversion device 1 at a certain timing during a period T from timing t3 to t4. For ease of explanation, the power conversion device 1 is depicted in a simplified form in FIG. 4A. The transistors SA to SF are depicted as switches that exhibit an on / off state. During this period, the transistor SE is in an on state, and the transistor SF is in an off state.

[0046] Because transistors SA and SD are on, current I1 can flow in the primary circuit of power conversion device 1, in the order of voltage line L11, transistor SA, winding 13A, transistor SD, and reference voltage line L12. Correspondingly, current I2 can flow in the secondary circuit of power conversion device 1, in the order of winding 13C, inductor 21, capacitor 22 and low-voltage battery BL, reference voltage line L22, transistor SE, and winding 13C. In this way, power conversion device 1 transfers power from the primary circuit to the secondary circuit during period T from timing t3 to t4.

[0047] 3, at timing t5, the drive circuit 31 changes the drive signal GC from low to high based on the control signal GC1 (FIG. 3(C)), thereby changing the transistor SC from an off state to an on state.

[0048] Next, at timing t6, the drive circuit 31 changes the drive signal GA from high to low based on the control signal GA1 (FIG. 3(A)), thereby changing the transistor SA from an on state to an off state.

[0049] Next, at timing t7, the drive circuit 31 changes the drive signal GB from low level to high level based on the control signal GB1 (FIG. 3(B)), thereby changing the transistor SB from the off state to the on state.

[0050] Next, at timing t8, the drive circuit 31 changes the drive signal GC from high to low based on the control signal GC1 (FIG. 3(C)), thereby changing the transistor SC from the on state to the off state.

[0051] In this way, both the transistors SB and SC are in the ON state during the period T from timing t7 to t8. During this period T, the drive signals GA and GD are at a low level, so that both the transistors SA and SD are in the OFF state.

[0052] 4B shows one operation state of the power conversion device 1 at a certain timing in a period T from timing t7 to t8. During this period, the transistor SE is in an off state, and the transistor SF is in an on state.

[0053] Because transistors SB and SC are on, current I1 can flow in the primary circuit of power conversion device 1, in the order of voltage line L11, transistor SC, winding 13A, transistor SB, and reference voltage line L12. Correspondingly, current I2 can flow in the secondary circuit of power conversion device 1, in the order of winding 13B, inductor 21, capacitor 22 and low-voltage battery BL, reference voltage line L22, transistor SF, and winding 13B. In this way, power conversion device 1 transfers power from the primary circuit to the secondary circuit during period T from timing t7 to t8.

[0054] In this way, the power conversion device 1 transfers power from the primary side circuit to the secondary side circuit during the period T from timing t3 to t4 and the period T from timing t7 to t8.

[0055] The control circuit 19 determines, for example, the ratio (duty ratio) of the time lengths of two periods T during which power is transmitted within a cycle period Tsw corresponding to the switching cycle of the drive signals GA to GD, based on the voltage VL, which is the output voltage of the power conversion device 1. Then, based on this duty ratio, the control circuit 19 generates the control signals GA1 to GD1 that are the basis of the drive signals GA to GD. For example, if the voltage VL is lower than the target voltage, the control circuit 19 attempts to increase the voltage VL by increasing the duty ratio. For example, if the voltage VL is higher than the target voltage, the control circuit 19 attempts to decrease the voltage VL by decreasing the duty ratio. In this way, the control circuit 19 performs feedback control so that the voltage VL becomes the target voltage.

[0056] (Operation based on instructions from an external device) When an external device issues an instruction to start or stop a switching operation to the power conversion device 1, the interface circuit 33 of the power conversion device 1 generates a drive control signal SCTL based on the instruction. Then, the power conversion device 1 starts or stops the switching operation based on the drive control signal SCTL. This operation will be described in detail below.

[0057] 5 shows an example of the operation of the power conversion device 1 when an external device instructs the power conversion device 1 to start a switching operation. (A) shows the waveform of the drive control signal SCTL, (B) shows the waveform of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31, (C) shows the waveform of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32, (D) shows the waveform of the control signal GA1, (E) shows the waveform of the drive signal GA, (F) shows the waveform of the control signal GE1, and (G) shows the waveform of the drive signal GE. Note that the waveforms of the control signals GB1, GC1, and GD1 are the same as the waveform of the control signal GA1 shown in FIG. 5(D), and the waveforms of the drive signals GB, GC, and GD are the same as the waveform of the drive signal GA shown in FIG. 5(E). Also, the waveform of the control signal GF1 is the same as the waveform of the control signal GE1 shown in FIG. 5(F), and the waveform of the drive signal GF is the same as the waveform of the drive signal GE shown in FIG. 5(G).

[0058] When the interface circuit 33 of the power conversion device 1 receives an instruction to start a switching operation transmitted from an external device, it changes the drive control signal SCTL from low to high at timing t11 (FIG. 5(A)). This charges the capacitor C2, and the voltage of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32 increases (FIG. 5(C)). As a result, the drive circuit 32 becomes able to generate the drive signals GE and GF based on the control signals GE1 and GF1. Note that, because the control signals GE1 and GF1 have not yet been generated, the drive circuit 32 maintains the drive signals GE and GF at low levels (FIGS. 5(F) and 5(G)).

[0059] Furthermore, at timing t11, when the drive control signal SCTL goes high, the diode 41 of the signal generation circuit 34 transitionally turns on, charging the capacitor C1 and increasing the voltage of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31 (FIG. 5(B)). As a result, the drive circuit 31 is able to generate the drive signals GA-GD based on the control signals GA1-GD1. Note that, because the control signals GA1-GD1 have not yet been generated, the drive circuit 32 maintains the drive signals GA-GD at low levels (FIGS. 5(D) and (E)).

[0060] Then, at timing t12, the control circuit 19 starts generating the control signals GA1 to GD1 (FIG. 5(D)). The drive circuit 31 starts generating the drive signals GA to GD based on these control signals GA1 to GD1 (FIG. 5(E)).

[0061] Then, at timing t13 after timing t12, the control circuit 19 starts generating the control signals GE1 and GF1 (FIG. 5(F)). The drive circuit 32 starts generating the drive signals GE and GF based on the control signals GE1 and GF1 (FIG. 5(G)).

[0062] As described above, in the power conversion device 1, when starting a switching operation, the control circuit 19 starts generating the control signals GA1-GD1, and then starts generating the control signals GE1 and GF1. As a result, after the drive circuit 31 starts generating the drive signals GA-GD, the drive circuit 32 starts generating the drive signals GE and GF. As a result, in the power conversion device 1, the rectifier circuit 14 in the secondary side circuit starts operating after the switching circuit 12 in the primary side circuit starts operating. Therefore, in the power conversion device 1, there is no period in which only the rectifier circuit 14 performs a switching operation, and therefore, for example, the possibility of a surge occurring in the rectifier circuit 14 can be reduced.

[0063] Figure 6 shows an example of the operation of the power conversion device 1 when an external device instructs the power conversion device 1 to stop switching operation, where (A) shows the waveform of the drive control signal SCTL, (B) shows the waveform of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31, (C) shows the waveform of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32, (D) shows the waveform of the control signal GA1, (E) shows the waveform of the drive signal GA, (F) shows the waveform of the control signal GE1, and (G) shows the waveform of the drive signal GE.

[0064] When the interface circuit 33 of the power conversion device 1 receives an instruction to stop the switching operation transmitted from an external device, it changes the drive control signal SCTL from high to low at timing t21 (FIG. 6(A)). This causes the capacitor C2 to discharge, and the voltage of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32 decreases (FIG. 6(C)). At timing t22, when the voltage of the drive control signal SCTL2 falls below the threshold voltage TH, the drive circuit 32 stops generating the drive signals GE and GF based on this drive control signal SCTL2 (FIG. 6(G)).

[0065] At timing t21, after the drive control signal SCTL goes low, from timing t21 to timing t22, the drive circuit 32 continues to generate the drive signal GE, so the signal generation circuit 34 maintains the voltage of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31 at a high voltage (FIG. 6(B)). Then, at timing t22, the drive circuit 32 stops generating the drive signals GE and GF, and the drive signal GE is maintained at a low level (FIG. 6(G)), so the signal generation circuit 34 reduces the voltage of this drive control signal SCTL1 (FIG. 6(B)). At timing t23, when the voltage of the drive control signal SCTL1 falls below the threshold voltage TH, the drive circuit 31 stops generating the drive signals GA to GD based on this drive control signal SCTL1 (FIG. 6(E)).

[0066] As described above, when the power conversion device 1 stops its switching operation, the drive circuit 32 first stops generating the drive signals GE and GF based on the drive control signal SCTL2 corresponding to the drive control signal SCTL. This causes the drive signal GE to go low. The signal generation circuit 34 reduces the voltage of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31 based on this drive signal GE. The drive circuit 31 stops generating the drive signals GA to GD based on this drive control signal SCTL1. As a result, in the power conversion device 1, the switching circuit 12 in the primary side circuit stops operating after the rectifier circuit 14 in the secondary side circuit stops operating. Therefore, in the power conversion device 1, there is no period in which only the rectifier circuit 14 performs switching operation, which can reduce the possibility of a surge occurring in the rectifier circuit 14, for example.

[0067] Thus, the power conversion device 1 includes input power terminals T11, T12, a switching circuit 12 connected to the input power terminals T11, T12 and capable of performing a switching operation, a first drive circuit (drive circuit 31) capable of performing a first drive operation to drive the switching circuit 12 and capable of stopping the first drive operation based on a first drive control signal (drive control signal SCTL1), a transformer 13 having a first winding (winding 13A) and a second winding (winding 13C) connected to the switching circuit 12, and a first rectifying switching element (transistor SE) connected to the second winding (winding 13C) and capable of being turned on and off based on a first drive signal (drive signal GE), and by performing a switching operation, the first rectifying switching element (transistor SE) supplied from the second winding (winding 13C) The power conversion device 1 includes a rectifier circuit 14 capable of rectifying a signal, a second drive circuit (drive circuit 32) capable of generating a first drive signal (drive signal GE) and performing a second drive operation to drive a first rectifier switching element (transistor SE) using the first drive signal (drive signal GE) and stopping the second drive operation based on a second drive control signal (drive control signal SCTL2) corresponding to a control signal (drive control signal SCTL), a signal generation circuit 34 capable of generating a first drive control signal (drive control signal SCTL1) based on the control signal (drive control signal SCTL) and the first drive signal (drive signal GE), a smoothing circuit 20 capable of smoothing the voltage rectified by the rectifier circuit 14, and output power terminals T21 and T22 connected to the smoothing circuit 20. In this way, in the power conversion device 1, the signal generation circuit 34 generates the drive control signal SCTL1 based on the drive control signal SCTL and the drive signal GE, and the drive circuit 31 stops the operation of driving the transistors SA to SD based on this drive control signal SCTL1. 6, the drive circuit 31 stops generating the drive signals GA to GD based on the result that the drive circuit 32 has stopped generating the drive signal GE. Therefore, in the power conversion device 1, the robustness of the operation of stopping the switching operation can be improved.

[0068] That is, for example, in the technology disclosed in Patent Document 1, due to variations in the characteristics of elements and circuits, it is possible that the switching circuit in the primary circuit will not stop operating after the rectifier circuit in the secondary circuit stops operating. On the other hand, in the power conversion device 1 according to this embodiment, the drive circuit 31 stops generating the drive signals GA to GD based on the result of the drive circuit 32 stopping the generation of the drive signal GE. This operation is less susceptible to variations in elements and circuits. Therefore, in the power conversion device 1, the robustness of the operation of stopping the switching operation can be improved.

[0069] Furthermore, because of this high robustness, the time from when the generation of drive signal GE is stopped to when the generation of drive signals GA to GD is stopped can be shortened. That is, in a circuit with low robustness, in order to increase robustness, the time from when the rectifier circuit in the secondary side circuit stops operating to when the switching circuit in the primary side circuit stops operating can be made longer. However, in this case, the operation of power conversion device 1 cannot be stopped in a short time. For example, when an overcurrent or overvoltage occurs, the power conversion device 1 needs to be stopped in a short time, but such a circuit cannot stop the operation of power conversion device 1 in a short time. On the other hand, because the power conversion device 1 according to this embodiment has such high robustness, the time from when the rectifier circuit in the secondary side circuit stops operating to when the switching circuit in the primary side circuit stops operating can be shortened.

[0070] In addition, in the power conversion device 1, the signal generating circuit 34 has a first input node (input node NI1) to which a drive control signal SCTL can be input, a second input node (input node NI2) to which a first drive signal (drive signal GE) can be input, an output node (output node NO) to which a first drive control signal (drive control signal SCTL1) can be output, a first diode (diode 41) provided in a path connecting the first input node (input node NI1) and the output node (output node NO) and having an anode connected to the first input node and a cathode connected to the output node, and a second diode (diode 42) provided in a path connecting the second input node (input node NI2) and the output node (output node NO) and having an anode connected to the second input node and a cathode connected to the output node. As a result, in the power conversion device 1, for example, when the drive control signal SCTL changes from high to low, the voltage at the anode of the diode 41 becomes lower than the voltage at the cathode, and the diode 41 enters an OFF state. Then, when the generation of the drive signal GE is stopped and the drive signal GE becomes low, the voltage at the anode of the diode 42 becomes lower than the voltage at the cathode, and the diode 42 enters an OFF state. Then, the capacitor C1 is discharged, and the drive control signal SCTL1 falls to a low level. As a result, in the power conversion device 1, the drive control signal SCTL1 falls to a low level based on the result of the drive circuit 32 stopping the generation of the drive signal GE, and the drive circuit 31 stops generating the drive signals GA to GD. Therefore, in the power conversion device 1, the robustness of the operation of stopping the switching operation can be improved with a simple configuration.

[0071] [effect] As described above, in this embodiment, there is provided an input power terminal, a switching circuit connected to the input power terminal and capable of performing a switching operation, a first drive circuit capable of performing a first drive operation for driving the switching circuit and capable of stopping the first drive operation based on a first drive control signal, a transformer having a first winding and a second winding led to the switching circuit, and a first rectifying switching element connected to the second winding and capable of being turned on and off based on the first drive signal, and capable of rectifying a signal supplied from the second winding by performing a switching operation. The power supply is provided with a rectifier circuit, a second drive circuit capable of generating a first drive signal and performing a second drive operation to drive a first rectifier switching element using the first drive signal and capable of stopping the second drive operation based on a second drive control signal corresponding to a control signal, a signal generating circuit capable of generating the first drive control signal based on the control signal and the first drive signal, a smoothing circuit capable of smoothing the voltage rectified by the rectifier circuit, and an output power terminal connected to the smoothing circuit, thereby increasing the robustness of the operation of stopping the switching operation.

[0072] In this embodiment, the signal generating circuit has a first input node to which a drive control signal can be input, a second input node to which a first drive signal can be input, an output node to which the first drive control signal can be output, a first diode provided in a path connecting the first input node and the output node and having an anode connected to the first input node and a cathode connected to the output node, and a second diode provided in a path connecting the second input node and the output node and having an anode connected to the second input node and a cathode connected to the output node. Thus, with a simple configuration, the robustness of the operation of stopping the switching operation can be improved.

[0073] [Variation 1] In the above embodiment, the signal generation circuit 34 generates the drive control signal SCTL1 based on the drive control signal SCTL and the drive signal GE, but this is not limited to this. Instead, for example, as shown in Figure 7, the signal generation circuit 34 may generate the drive control signal SCTL1 based on the drive control signal SCTL and the drive signal GF.

[0074] [Variation 2] In the above embodiment, the signal generation circuit 34 generates the drive control signal SCTL1 based on one of the drive signals GE and GF, but this is not limited to this, and instead, for example, the drive control signal SCTL1 may be generated based on both the drive signals GE and GF. This modification will be described in detail below.

[0075] 8 shows an example of the configuration of a power conversion device 1A according to this modification. The power conversion device 1A includes a signal generation circuit 34A. The signal generation circuit 34A is configured to generate a drive control signal SCTL1 based on the drive control signal SCTL generated by the interface circuit 33 and the drive signals GE and GF generated by the drive circuit 32.

[0076] 9 shows an example of the configuration of the signal generating circuit 34A. The signal generating circuit 34A has a diode 42A. A drive signal GF is supplied from the drive circuit 32 to an input node NI3 of the signal generating circuit 34. The anode of the diode 42A is connected to the input node NI3, and the cathode is connected to one end of the resistance element 43.

[0077] Here, winding 13B corresponds to a specific example of a "third winding" in an embodiment of the present disclosure. Transistor SF corresponds to a specific example of a "second rectifying switching element" in an embodiment of the present disclosure. Drive signal GF corresponds to a specific example of a "second drive signal" in an embodiment of the present disclosure. Signal generating circuit 34A corresponds to a specific example of a "signal generating circuit" in an embodiment of the present disclosure. Input node NI3 corresponds to a specific example of a "third input node" in an embodiment of the present disclosure. Diode 42A corresponds to a specific example of a "third diode" in an embodiment of the present disclosure.

[0078] Figure 10 shows an example of the operation of the power conversion device 1 when an external device instructs the power conversion device 1 to stop switching operation, where (A) shows the waveform of the drive control signal SCTL, (B) shows the waveform of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31, (C) shows the waveform of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32, (D) shows the waveform of the control signal GA1, (E) shows the waveform of the drive signal GA, (F) shows the waveform of the control signal GE1, (G) shows the waveform of the control signal GF1, (H) shows the waveform of the drive signal GE, and (I) shows the waveform of the drive signal GF.

[0079] When the interface circuit 33 of the power conversion device 1 receives an instruction to stop the switching operation transmitted from an external device, it changes the drive control signal SCTL from high to low at timing t31 (FIG. 10(A)). This causes the capacitor C2 to discharge, and the voltage of the drive control signal SCTL2 at the enable terminal ENB of the drive circuit 32 decreases (FIG. 10(C)). At timing t32, when the voltage of the drive control signal SCTL2 falls below the threshold voltage TH, the drive circuit 32 stops generating the drive signals GE and GF based on this drive control signal SCTL2 (FIGS. 10(H) and 10(I)).

[0080] At timing t31, after the drive control signal SCTL goes low, from timing t31 to timing t32, the drive circuit 32 continues to generate the drive signals GE and GF, so the signal generation circuit 34A maintains the voltage of the drive control signal SCTL1 at the enable terminal ENB of the drive circuit 31 at a high voltage (FIG. 10(B)). Then, at timing t32, the drive circuit 32 stops generating the drive signals GE and GF, and the drive signals GE and GF are maintained at a low level (FIGS. 10(H) and (I)), so the signal generation circuit 34 reduces the voltage of this drive control signal SCTL1 (FIG. 10(B)). At timing t23, when the voltage of the drive control signal SCTL1 falls below the threshold voltage TH, the drive circuit 31 stops generating the drive signals GA to GD based on this drive control signal SCTL1 (FIG. 10(E)).

[0081] Even in this case, in the power conversion device 1A, the switching circuit 12 in the primary side circuit stops operating after the rectifier circuit 14 in the secondary side circuit stops operating. Therefore, in the power conversion device 1A, there is no period during which only the rectifier circuit 14 performs a switching operation, and therefore, for example, the possibility of a surge occurring in the rectifier circuit 14 can be reduced.

[0082] Although the present invention has been described above by way of embodiments and modifications, the present invention is not limited to these embodiments and can be modified in various ways.

[0083] For example, although the above embodiment has the circuit configuration shown in Fig. 1, the present invention is not limited to this. For example, the switching circuit 12 of the primary side circuit may be a half-bridge type circuit.

[0084] The effects described in this specification are merely examples, and the effects of the present disclosure are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present disclosure.

[0085] Furthermore, the present disclosure may take the following aspects.

[0086] (1) an input power terminal; a switching circuit connected to the input power terminal and capable of performing a switching operation; a first drive circuit capable of performing a first drive operation to drive the switching circuit and capable of stopping the first drive operation based on a first drive control signal; a transformer having a first winding and a second winding connected to the switching circuit; a rectifier circuit that is connected to the second winding and has a first rectifier switching element that can be turned on and off based on a first drive signal, and that can rectify a signal supplied from the second winding by performing a switching operation; a second drive circuit capable of generating the first drive signal, performing a second drive operation to drive the first rectifying switching element using the first drive signal, and stopping the second drive operation based on a second drive control signal corresponding to a control signal; a signal generating circuit capable of generating the first drive control signal based on the control signal and the first drive signal; a smoothing circuit capable of smoothing the voltage rectified by the rectifier circuit; an output power terminal connected to the smoothing circuit; A power conversion device comprising: (2) The signal generating circuit a first input node to which the control signal can be input; a second input node to which the first drive signal can be input; an output node capable of outputting the first drive control signal; a first diode provided in a path connecting the first input node and the output node, the first diode having an anode connected to the first input node and a cathode connected to the output node; a second diode provided in a path connecting the second input node and the output node, the second diode having an anode connected to the second input node and a cathode connected to the output node; have The power conversion device according to (1) above. (3) The signal generating circuit further includes a low-pass filter provided in a path connecting the second input node and the output node at a stage subsequent to the second diode. The power conversion device according to (2) above. (4) The signal generating circuit further includes a voltage dividing circuit that is provided in a path connecting the second input node and the output node at a subsequent stage of the second diode, includes a plurality of resistive elements, and is capable of dividing an input voltage. The power conversion device according to (2) or (3) above. (5) the transformer further has a third winding; the rectifier circuit further includes a second rectifier switching element connected to the third winding and capable of being turned on and off based on a second drive signal, and is capable of rectifying a signal supplied from the third winding; the second drive circuit is further capable of generating the second drive signal; the second driving operation further includes driving the second rectifying switching element using the second driving signal; The signal generating circuit is capable of generating the first drive control signal based on the control signal, the first drive signal, and the second drive signal. The power conversion device according to (1) above. (6) The signal generating circuit a first input node to which the control signal can be input; a second input node to which the first drive signal can be input; a third input node to which the second drive signal can be input; an output node capable of outputting the first drive control signal; a first diode provided in a path connecting the first input node and the output node, the first diode having an anode connected to the first input node and a cathode connected to the output node; a second diode provided in a path connecting the second input node and the output node, the second diode having an anode connected to the second input node and a cathode connected to the output node; a third diode provided in a path connecting the third input node and the output node, the third diode having an anode connected to the third input node and a cathode connected to the output node; have The power conversion device according to (5) above. [Explanation of symbols]

[0087] 1,1A...power conversion device, 11...capacitor, 12...switching circuit, 13...transformer, 13A, 13B, 13C...winding, 14...rectifier circuit, 15...voltage sensor, 19...control circuit, 20...smoothing circuit, 21...inductor, 22...capacitor, 31,32...drive circuit, 33...interface circuit, 34,34A...signal generation circuit, 41,42,42A...diode, 43...resistance element, 44...capacitor, 45,46...resistance element, BH...high-voltage battery, BL...low-voltage battery, C1,C2...capacitor, CTL...output terminal, DIV...divider voltage circuit, ENB...enable terminal, GA, GB, GC, GD, GE, GF...drive signal, GA1, GB1, GC1, GD1, GE1, GF1...control signal, L11, L21A, L21B...voltage line, L12, L22...reference voltage line, NI1, NI2, NI3...input node, NO...output node, SA, SB, SC, SD, SE, SF...transistor, SCTL...drive control signal, SCTL1...drive control signal, SCTL2...drive control signal, T11, T12...input power terminal, T21, T22...output power terminal, TH...threshold voltage, VL...voltage.

Claims

1. an input power terminal; a switching circuit connected to the input power terminal and capable of performing a switching operation; a first drive circuit capable of performing a first drive operation to drive the switching circuit and capable of stopping the first drive operation based on a first drive control signal; a transformer having a first winding and a second winding connected to the switching circuit; a rectifier circuit connected to the second winding, including a first rectifier switching element that can be turned on and off based on a first drive signal, and that can rectify a signal supplied from the second winding by performing a switching operation; a second drive circuit capable of generating the first drive signal, performing a second drive operation to drive the first rectifying switching element using the first drive signal, and stopping the second drive operation based on a second drive control signal corresponding to a control signal; a signal generating circuit capable of generating the first drive control signal based on the control signal and the first drive signal; a smoothing circuit capable of smoothing the voltage rectified by the rectifier circuit; an output power terminal connected to the smoothing circuit; A power conversion device comprising:

2. The signal generating circuit a first input node to which the control signal can be input; a second input node to which the first drive signal can be input; an output node capable of outputting the first drive control signal; a first diode provided in a path connecting the first input node and the output node, the first diode having an anode connected to the first input node and a cathode connected to the output node; a second diode provided in a path connecting the second input node and the output node, the second diode having an anode connected to the second input node and a cathode connected to the output node; have The power conversion device according to claim 1 .

3. The signal generating circuit further includes a low-pass filter provided in a path connecting the second input node and the output node at a stage subsequent to the second diode. The power conversion device according to claim 2 .

4. The signal generating circuit further includes a voltage dividing circuit that is provided in a path connecting the second input node and the output node at a subsequent stage of the second diode, includes a plurality of resistive elements, and is capable of dividing an input voltage. The power conversion device according to claim 2 .

5. the transformer further includes a third winding; the rectifier circuit further includes a second rectifier switching element connected to the third winding and capable of being turned on and off based on a second drive signal, and is capable of rectifying a signal supplied from the third winding; the second drive circuit is further capable of generating the second drive signal; the second driving operation further includes driving the second rectifying switching element using the second driving signal; The signal generating circuit is capable of generating the first drive control signal based on the control signal, the first drive signal, and the second drive signal. The power conversion device according to claim 1 .

6. The signal generating circuit a first input node to which the control signal can be input; a second input node to which the first drive signal can be input; a third input node to which the second drive signal can be input; an output node capable of outputting the first drive control signal; a first diode provided in a path connecting the first input node and the output node, the first diode having an anode connected to the first input node and a cathode connected to the output node; a second diode provided in a path connecting the second input node and the output node, the second diode having an anode connected to the second input node and a cathode connected to the output node; a third diode provided in a path connecting the third input node and the output node, the third diode having an anode connected to the third input node and a cathode connected to the output node; have The power conversion device according to claim 5 .

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