DC / DC converter

Abstract

The purpose of the present disclosure is to protect an input-side capacitor in the event of an abnormality. The DC / DC converter includes a first transformer circuit, a second transformer circuit, and a switching control circuit. The first voltage transformation circuit comprises a first switch and a first coil. The second transformation circuit comprises a second switch and a second coil. The first coil and the second coil are connected in parallel with the input port of the DC / DC converter and the input side capacitor. The DC / DC converter further includes a first detection circuit, a second detection circuit, and a stop determination circuit. The first detection circuit detects a first current flowing through the first coil. The second detection circuit detects a second current flowing through the second coil. The stop determination circuit stops the transformation operation on the basis of the difference between the first current and the second current.

Description

Technical Field

[0001] This disclosure relates to a DC / DC converter for transforming direct current power. Background Technology

[0002] A DC / DC converter comprises an input port, an input-side capacitor, a transformer circuit, an output port, and a switching control circuit. The transformer circuit includes a switch and a coil. The switching control circuit controls the transformer circuit's transformation operation by controlling the switch.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 167271 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] This disclosure addresses the problems that may arise when a prescribed structure is used in such a DC / DC converter, as shown below. Specifically, in this structure, the first and second transformer circuits are connected in parallel with the input port and the input-side capacitor. The switching control circuit controls the switching of the first transformer circuit without feedback on the current value of the first transformer circuit. Furthermore, the switching control circuit controls the switching of the second transformer circuit without feedback on the current value of the second transformer circuit. In other words, the switching control circuit performs open-loop control of the transformer operation of the first and second transformer circuits. In this case, the problems shown below may arise.

[0008] If an abnormality such as a broken wire or other fault occurs in either the first or second transformer circuit, an imbalance will arise between the impedances of the first and second transformer circuits. Because it is an open-loop control system, the current magnitudes will diverge during the periods when current flows through the first and second transformer circuits, resulting in a larger current fluctuation. This fluctuation leads to increased current flowing into and out of the input capacitor. This inflow and outflow causes the input capacitor to heat up, potentially leading to its failure. Therefore, in the event of such an abnormality, it is necessary to quickly detect the anomaly to protect the input capacitor.

[0009] However, in methods that detect anomalies based on overcurrent, anomalies cannot be detected when current repeatedly flows in and out of the input capacitor within a range where no overcurrent is detected. Furthermore, methods that detect the temperature of the input capacitor using a temperature sensor require the temperature sensor to be installed inside the input capacitor, thus increasing costs.

[0010] This disclosure was made in view of the above circumstances, and its purpose is to protect the input-side capacitor by an appropriate method in the event of an malfunction in a DC / DC converter that performs open-loop control of transformer operation.

[0011] Methods for solving problems

[0012] The DC / DC converter disclosed herein features:

[0013] Input port, input-side capacitor, first transformer circuit, second transformer circuit, output port, and switch control circuit.

[0014] The first transformer circuit includes a first switch and a first coil.

[0015] The second transformer circuit includes a second switch and a second coil.

[0016] The first coil and the second coil are connected in parallel with the input port and the input-side capacitor.

[0017] The switch control circuit performs open-loop control of the transformation operation of the first transformer circuit and the second transformer circuit through the control of the first switch and the second switch.

[0018] The power, transformed by the transformer action, is output from the output port.

[0019] in,

[0020] The DC / DC converter has the following features:

[0021] The first detection circuit detects a first current as the current flowing through the first coil;

[0022] The second detection circuit detects a second current as the current flowing through the second coil;

[0023] The stop determination circuit stops the transformer operation based on the difference between the first current and the second current. Attached Figure Description

[0024] Figure 1 This is a circuit diagram illustrating the DC / DC converter of the first embodiment.

[0025] Figure 2 This is a circuit diagram representing the stop determination circuit.

[0026] Figure 3 It is a circuit diagram representing the first state of operation when the power is running.

[0027] Figure 4 This is a circuit diagram representing the second state of operation when the power source is running.

[0028] Figure 5 It is a graph showing the shift of various currents during power operation.

[0029] Figure 6 It is a graph showing the shift of various currents during abnormal operation of the power system.

[0030] Figure 7 It is a graph showing the shift of each current before and after the stop control is applied.

[0031] Figure 8 This is a circuit diagram representing the first state during regeneration.

[0032] Figure 9 This is a circuit diagram representing the second state during regeneration.

[0033] Figure 10 It is a graph showing the shift of various currents during regeneration.

[0034] Figure 11 This is a circuit diagram showing the stop determination circuit of the second embodiment.

[0035] Figure 12 It is a graph showing the shift of each current before and after the stop control is applied. Detailed Implementation

[0036] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to any of the following embodiments and can be implemented with appropriate modifications without departing from the spirit of the present disclosure.

[0037] [First Implementation Method]

[0038] like Figure 1 As shown, the DC / DC converter Dcv has input ports Pi+ and Pi- and output ports Po+ and Po-. Hereinafter, the positive terminal of the input ports Pi+ and Pi- will be referred to as "input port Pi+", and the negative terminal will be referred to as "input port Pi-". Similarly, the positive terminal of the output ports Po+ and Po- will be referred to as "output port Po+", and the negative terminal will be referred to as "output port Po-".

[0039] A DC power supply Ps is electrically connected to the input ports Pi+ and Pi-. An amplifier AP, used to drive the robot Rb, is electrically connected to the output ports Po+ and Po-.

[0040] The DC / DC converter Dcv also includes an input-side capacitor Ci, a first transformer circuit Tc1, a second transformer circuit Tc2, and an output-side capacitor Co. The first transformer circuit Tc1 includes a first upper switch Q1U, a first lower switch Q1D, and a first coil L1. The second transformer circuit Tc2 includes a second upper switch Q2U, a second lower switch Q2D, and a second coil L2.

[0041] Hereinafter, the first upper switch Q1U and the first lower switch Q1D will be collectively referred to as "first switches Q1U and Q1D". Similarly, the second upper switch Q2U and the second lower switch Q2D will be collectively referred to as "second switches Q2U and Q2D". Furthermore, the first upper switch Q1U, the first lower switch Q1D, the second upper switch Q2U, and the second lower switch Q2D will be collectively referred to as "each switch Q1U, Q1D, Q2U, and Q2D". Each switch Q1U, Q1D, Q2U, and Q2D is a semiconductor switch such as a transistor.

[0042] One end of the first coil L1 is electrically connected via the first upper switch Q1U to the positive terminals of the input ports Pi+ and Pi- and the input capacitor Co, respectively. This same end is also electrically connected via the first lower switch Q1D to the negative terminals of the input ports Pi+ and Pi-, the input capacitor Co, the output capacitor Ci, and the output ports Po+ and Po-, respectively. The other end of the first coil L1 is electrically connected to the positive terminals of the output capacitor Co and the output ports Po+ and Po-, respectively.

[0043] One end of the second coil L2 is electrically connected via the second upper switch Q2U to the positive terminals of the input ports Pi+, Pi-, and the input capacitor Co. This same end is also electrically connected via the second lower switch Q2D to the negative terminals of the input ports Pi+, Pi-, the input capacitor Co, the output capacitor Ci, and the output ports Po+, Po-. The other end of the second coil L2 is electrically connected to the positive terminals of the output capacitor Co and the output ports Po+, Po-.

[0044] Therefore, the input ports Pi+, Pi- and the input-side capacitor Ci are electrically connected to the output-side capacitor Co and the output ports Po+, Po- via the parallel-connected first coil L1 and second coil L2. That is, the first coil L1 and the second coil L2 are connected in parallel with the input ports Pi+, Pi- and the input-side capacitor Ci.

[0045] In this embodiment, each switch Q1U, Q1D, Q2U, and Q2D has a parasitic diode. Specifically, the first upper switch Q1U has a parasitic diode that allows current to flow from the first coil L1 to the input-side capacitor Ci and the input port Pi+. Similarly, the second upper switch Q2U has a parasitic diode that allows current to flow from the second coil L2 to the input-side capacitor Ci and the input port Pi+. Furthermore, the first lower switch Q1D has a parasitic diode that allows current to flow from the output-side capacitor Co and the output port Po- to the first coil L1. And the second lower switch Q2D has a parasitic diode that allows current to flow from the output-side capacitor Co and the output port Po- to the second coil L2.

[0046] However, instead of the above, semiconductor switches such as IGBTs that do not have parasitic diodes can be used as switches Q1U, Q1D, Q2U, and Q2D, and freewheeling diodes can be connected in parallel to ground for each switch Q1U, Q1D, Q2U, and Q2D.

[0047] Hereinafter, the current flowing from the DC power supply Ps to the input port Pi+ is referred to as the "input current Ii". Additionally, the current flowing from the electrical connection point ei between the input port Pi+ and the input-side capacitor Ci to the electrical connection point eu between the first upper switch Q1U and the second upper switch Q2U is referred to as the "input-side current Iis". Furthermore, the current flowing through the first upper switch Q1U is referred to as the "first upper current Iq1u", and the current flowing through the first lower switch Q1D is referred to as the "first lower current Iq1d". Additionally, the current flowing through the second upper switch Q2U is referred to as the "second upper current Iq2u", and the current flowing through the second lower switch Q2D is referred to as the "second lower current Iq2d". Finally, the current flowing through the first coil L1 is referred to as the "first current It1", and the current flowing through the second coil L2 is referred to as the "second current It2".

[0048] The DC / DC converter Dcv also includes a switch control circuit Sc. The switch control circuit Sc controls the first switches Q1U and Q1D without providing feedback on the value of the first current It1. Furthermore, the switch control circuit Sc controls the second switches Q2U and Q2D without providing feedback on the value of the second current It2. That is, the switch control circuit Sc performs open-loop control of the transformation operation of the first transformer circuit Tc1 and the second transformer circuit Tc2.

[0049] Through this open-loop control, during power operation, the power input to input ports Pi+ and Pi- is stepped down and output from output ports Po+ and Po-. On the other hand, during regeneration, [the power is]... Figure 1 Conversely, the power input to the output ports Po+ and Po- is boosted and output from the input ports Pi+ and Pi-.

[0050] The following, such as Figure 3As shown, the state in which the first upper switch Q1U and the second lower switch Q2D are connected and the first lower switch Q1D and the second upper switch Q2U are disconnected is called "first state s1". Additionally, as... Figure 4 As shown, the state in which the first upper switch Q1U and the second lower switch Q2D are open and the first lower switch Q1D and the second upper switch Q2U are closed is called "second state s2". Furthermore, in Figure 3 , Figure 4 In this document, for the visibility of the on / off states of each switch Q1U, Q1D, Q2U, and Q2D, the markings for mechanical switches are used to represent the semiconductor switches Q1U, Q1D, Q2U, and Q2D. This will be discussed later. Figure 8 , Figure 9 The same applies to China.

[0051] During power operation, when the current flows from... Figure 1 As shown, with the flow from input port Pi+ to output port Po+, the switch control circuit Sc alternately switches to... Figure 3 The first state s1 shown and Figure 4 The second state s2 is shown. Figure 3 In the first state s1 shown, the first current It1 increases and the second current It2 decreases. On the other hand, in Figure 4 In the second state s2 shown, the first current It1 decreases and the second current It2 increases. Therefore, as... Figure 5 As shown, the first current It1 and the second current It2 shift their phases by 180°.

[0052] like Figure 5 As shown, the first current It1 is the sum of the first upward current Iq1u in the first state s1 and the first downward current Iq1d in the second state s2. The second current It2 is the sum of the second downward current Iq2d in the first state s1 and the second upward current Iq2u in the second state s2.

[0053] The input-side current Iis is the sum of the first current Iq1u in the first state s1 and the second current Iq2u in the second state s2. That is, the input-side current Iis is the sum of the first current It1 in the first state s1 and the second current It2 in the second state s2. This relates to the problem that should be solved in this embodiment, which will be described later.

[0054] During regeneration, with Figure 1 The arrows shown are in opposite directions. When current flows from the output port Po+ to the input port Pi+, the switching control circuit Sc alternately switches between... Figure 8 The first state s1 shown and Figure 9 The second state s2 is shown. Therefore, during regeneration, it is also as follows... Figure 10As shown, the first current It1 and the second current It2 shift their phases by 180°.

[0055] In this embodiment, the time for maintaining the first state s1 is equal to the time for maintaining the second state s2, even during power operation and regeneration. Therefore, the duty cycle of each switch Q1U, Q1D, Q2U, and Q2D is approximately 50%. More specifically, the duty cycle of each switch Q1U, Q1D, Q2U, and Q2D is shorter than 50% by the amount of dead time.

[0056] Furthermore, the dead time mentioned here refers to the instant during which both the upper and lower switches are disconnected when switching from one of the first state s1 to the other of the second state s2. Figure 1 During the dead time of the power operation shown, current flows through the parasitic diodes of each lower switch Q1D and Q2D. On the other hand, with Figure 1 Conversely, during the dead time of current regeneration, current flows through the parasitic diodes of each upper switch Q1U and Q2U.

[0057] Since the duty cycles of each switch Q1U, Q1D, Q2U, and Q2D are approximately 50%, therefore... Figure 1 During the power operation shown, the voltage input to the input ports Pi+ and Pi- is reduced to approximately half and output from the output ports Po+ and Po-. On the other hand, with Figure 1 Conversely, during the regeneration of current flow, the voltage input to the output ports Po+ and Po- is boosted by approximately 2 times and output from the input ports Pi+ and Pi-.

[0058] Next, the problems to be solved in this embodiment will be explained. Figure 1 If an open circuit or other fault occurs in either the first transformer circuit Tc1 or the second transformer circuit Tc2, an imbalance will occur between the impedances of the first transformer circuit Tc1 and the second transformer circuit Tc2. At this time, due to open-loop control, therefore... Figure 6 As shown, the magnitudes of the first current It1 and the second current It2 sometimes diverge from each other.

[0059] As described above, the input-side current Iis is the sum of the first current It1 in the first state s1 and the second current It2 in the second state s2. Therefore, as Figure 6 As shown, when the magnitudes of the first current It1 and the second current It2 are opposite to each other, the variation amplitude ΔIis of the input current Iis is greater than that of the input current Iis. Figure 5 The normal value shown is large. According to this... Figure 6The fluctuation ΔIis shown indicates an increase in the current flowing into and out of the input capacitor Ci. This increased current causes the input capacitor Ci to heat up, potentially leading to its failure. Therefore, in the event of such an anomaly, it is necessary to detect the anomaly quickly to protect the input capacitor Ci.

[0060] To solve the above problems, such as Figure 1 As shown, the DC / DC converter Dcv also includes a first detection circuit A1, a second detection circuit A2, and a stop determination circuit Jc.

[0061] The first detection circuit A1 detects a first current It1 by detecting the current in the portion connected in series with the first coil L1, and outputs a "first voltage V1" as a voltage based on the magnitude of the detected first current It1. The second detection circuit A2 detects a second current It2 by detecting the current in the portion connected in series with the second coil L2, and outputs a second voltage V2 as a voltage based on the magnitude of the detected second current It2.

[0062] The stop determination circuit Jc outputs a stop signal Vb to the switch control circuit Sc based on the difference between the first voltage V1 and the second voltage V2. The stop signal Vb is used to stop the transformer operation. That is, the stop determination circuit Jc stops the transformer operation based on the difference between the first current It1 and the second current It2.

[0063] Next, refer to Figure 2 The details of the stop determination circuit Jc are explained below. The stop determination circuit Jc includes first to third operational amplifiers Ap1 to Ap3, first to ninth resistors R1 to R9, first and second diodes Do1 and Do2, and a constant voltage source Pth.

[0064] The output terminal of the first detection circuit A1 is electrically connected to the inverting input terminal of the first operational amplifier Ap1 via a first resistor R1, and to the non-inverting input terminal of the second operational amplifier Ap2 via a fourth resistor R4. The output terminal of the second detection circuit A2 is electrically connected to the non-inverting input terminal of the first operational amplifier Ap1 via a second resistor R2, and to the inverting input terminal of the second operational amplifier Ap2 via a third resistor R3. The non-inverting input terminal of the first operational amplifier Ap1 is electrically connected to ground via a fifth resistor R5. The non-inverting input terminal of the second operational amplifier Ap2 is electrically connected to ground via a sixth resistor R6.

[0065] The output terminal of the first operational amplifier Ap1 is electrically connected to the anode of the first diode Do1. The cathode of the first diode Do1 is electrically connected to the inverting input terminal of the first operational amplifier Ap1 via the seventh resistor R7, and is also electrically connected to the non-inverting input terminal of the third operational amplifier Ap3.

[0066] The output terminal of the second operational amplifier Ap2 is electrically connected to the anode of the second diode Do2. The cathode of the second diode Do2 is electrically connected to the inverting input terminal of the second operational amplifier Ap2 via the eighth resistor R8, and is also electrically connected to the non-inverting input terminal of the third operational amplifier Ap3.

[0067] The non-inverting input terminal of the third operational amplifier Ap3 is electrically connected to ground via the ninth resistor R9. A constant voltage source Pth is electrically connected to the inverting input terminal of the third operational amplifier Ap3, receiving the input threshold voltage Vth.

[0068] Based on the circuit structure described above, the first operational amplifier Ap1 outputs a "first differential voltage ΔV1" as the voltage based on the value (V1-V2) obtained by subtracting the second voltage V2 from the first voltage V1. Conversely, the second operational amplifier Ap2 outputs a "second differential voltage ΔV2" as the voltage based on the value (V2-V1) obtained by subtracting the first voltage V1 from the second voltage V2. The third operational amplifier Ap3 outputs a voltage as a stop signal Vb, provided that the larger of the first differential voltage ΔV1 and the second differential voltage ΔV2 is greater than the threshold voltage Vth.

[0069] As a result of the above, Figure 7 As shown, the stop determination circuit Jc outputs a stop signal Vb when the absolute value of the difference (It1-It2) between the value of the first current It1 and the value of the second current It2 is greater than the threshold Ith.

[0070] Figure 1 The switch control circuit Sc shown executes stop control upon receiving a stop signal Vb. This stop control is achieved by controlling each switch Q1U, Q1D, Q2U, and Q2D to halt the transformer operation. More specifically, the stop control is performed, for example, in the following manner.

[0071] That is, the switch control circuit Sc is in Figure 3 , Figure 4 When the power system receives a stop signal Vb during operation, the switches Q1U, Q1D, Q2U, and Q2D are fixed to be open via stop control. Even in this case, current flows through the parasitic diodes in the first switch Q1D and the second switch Q2D.

[0072] Through the above stop control, the return current in the closed circuit including the first down switch Q1D and the first coil L1, and the closed circuit including the second down switch Q2D and the second coil L2, is maintained. Thus, as... Figure 7 As shown, the first current It1 and the second current It2 are reduced to zero, causing the transformer operation to stop.

[0073] On the other hand, the switch control circuit Sc is in Figure 8 , Figure 9 When the regeneration process receives the stop signal Vb, the switches Q1U, Q1D, Q2U, and Q2D are fixed to be open via stop control. Even in this case, current flows through the parasitic diodes in the first upper switch Q1U and the second upper switch Q2U. Through the above stop control, similar to the case during power operation, the first current It1 and the second current It2 are reduced to zero, thus stopping the transformer operation.

[0074] like Figure 1 As shown, an alarm device Nd is installed externally to the DC / DC converter Dcv. The stop determination circuit Jc also outputs a stop signal Vb to the alarm device Nd. The alarm device Nd sounds an alarm upon receiving the stop signal Vb. This alarm can be, for example, a screen-based alarm, an audible alarm, or a combination of both.

[0075] The structure and effects of this embodiment are summarized below.

[0076] Figure 1 The switch control circuit Sc shown provides open-loop control of the transformer operation of the first transformer circuit Tc1 and the second transformer circuit Tc2 through the control of switches Q1U, Q1D, Q2U, and Q2D. The first detection circuit A1 detects the first current It1 flowing through the first coil L1. The second detection circuit A2 detects the second current It2 flowing through the second coil L2. The stop determination circuit Jc stops the transformer operation based on the difference between the first current It1 and the second current It2.

[0077] Therefore, as Figure 7 As shown, when the values ​​of the first current It1 and the second current It2 deviate abnormally, that is, when in Figure 1 When the current flowing into and out of the input-side capacitor Ci increases abnormally, the transformer operation can be stopped. This suppresses the heating of the input-side capacitor Ci caused by this inflow and outflow, protecting the input-side capacitor Ci. Therefore, according to this embodiment, when a DC / DC converter that performs open-loop control of the transformer operation malfunctions, the input-side capacitor Ci can be protected by an appropriate method.

[0078] Figure 1The stop determination circuit Jc shown stops the transformer operation based on the difference between the first current It1 and the second current It2 during both power operation and regeneration. Therefore, it can protect the input-side capacitor Ci in case of abnormality during both power operation and regeneration.

[0079] The stop determination circuit Jc outputs a stop signal Vb to the switch control circuit Sc based on the difference between the first current It1 and the second current It2. Upon receiving the stop signal Vb, the switch control circuit Sc stops the transformer operation by controlling each switch Q1U, Q1D, Q2U, and Q2D. Therefore, the transformer operation can be stopped using a simple structure that only outputs the stop signal Vb to the switch control circuit Sc.

[0080] like Figure 2 As shown, the first detection circuit A1 outputs a first voltage V1 based on the magnitude of the first current It1. The second detection circuit A2 outputs a second voltage V2 based on the magnitude of the second current It2. The first operational amplifier Ap1 outputs a first differential voltage ΔV1 based on the value (V1-V2) obtained by subtracting the second voltage V2 from the first voltage V1. The second operational amplifier Ap2 outputs a second differential voltage ΔV2 based on the value (V2-V1) obtained by subtracting the first voltage V1 from the second voltage V2. The third operational amplifier Ap3 outputs a voltage as a stop signal Vb, provided that the larger of the first differential voltage ΔV1 and the second differential voltage ΔV2 is greater than the threshold voltage Vth. Therefore, the stop determination circuit Jc can be implemented using a simple structure of three operational amplifiers Ap1, Ap2, and Ap3.

[0081] As a result, such Figure 7 As shown, the stop determination circuit Jc stops the transformer operation when the absolute value of the difference (It1-It2) between the values ​​of the first current It1 and the second current It2 is greater than the threshold Ith. Therefore, when the absolute value of this difference (It1-It2) is greater than the threshold Ith, the transformer operation can be stopped quickly.

[0082] like Figure 1 As shown, the stop determination circuit Jc outputs the stop signal Vb, which serves as the specified signal, not only to the switch control circuit Sc, but also to the alarm device Nd. The alarm device Nd issues an alarm upon receiving the stop signal Vb. Therefore, operators can identify abnormalities in the DC / DC converter Dcv based on the alarm.

[0083] [Second Implementation]

[0084] Next, refer to Figure 11 , Figure 12The second embodiment will be described. This embodiment is based on the first embodiment and focuses on the differences between it and the first embodiment. Points that are the same as or similar to the first embodiment will be omitted as appropriate.

[0085] Figure 11 The stop determination circuit Jc shown in this embodiment is not the absolute value of the difference (It1-It2) between the first current It1 and the second current It2, but outputs a stop signal when the absolute value of the value that increases as the difference accumulates is greater than a threshold.

[0086] Specifically, the stop determination circuit Jc in this embodiment also includes a first capacitor C1 and a second capacitor C2. The output terminal of the first operational amplifier Ap1 is electrically connected to the inverting input terminal of the first operational amplifier Ap1 via a seventh resistor R7 connected in parallel and the first capacitor C1. Alternatively, the seventh resistor R7 can be replaced with a "first feedback resistor". Furthermore, the output terminal of the second operational amplifier Ap2 is electrically connected to the inverting input terminal of the second operational amplifier Ap2 via an eighth resistor R8 connected in parallel and the second capacitor C2. Alternatively, the eighth resistor R8 can be replaced with a "second feedback resistor".

[0087] As described above, the first differential voltage ΔV1 increases as the value (V1-V2) obtained by subtracting the second voltage V2 from the first voltage V1 accumulates. On the other hand, the second differential voltage ΔV2 increases as the value (V2-V1) obtained by subtracting the first voltage V1 from the second voltage V2 accumulates. The third operational amplifier Ap3 outputs a stop signal Vb when the larger of these first differential voltages ΔV1 and second differential voltages ΔV2 exceeds the threshold voltage Vth.

[0088] As a result of the above, the stop determination circuit Jc does not use the absolute value of the difference (It1-It2) between the first current It1 and the second current It2 as a condition, but rather uses the absolute value of the increase in the value as this difference (It1-It2) accumulates as a condition, which causes the transformer operation to stop. Therefore, as Figure 12 As shown, compared to the first embodiment, the timing for stopping the transformer operation is delayed. Therefore, the drawback of stopping the transformer operation when the absolute value of the difference (It1-It2) temporarily exceeds the threshold Ith due to interference or the like can be suppressed.

[0089] Moreover, according to Figure 2 The state of the first embodiment shown is as follows: Figure 11As shown, this embodiment can be implemented with a simple structure that only adds a first capacitor C1 and a second capacitor C2. That is, the stop determination circuit Jc can be implemented with a simple structure using three operational amplifiers Ap1, Ap2, and Ap3 and two capacitors C1 and C2.

[0090] [Other Implementation Methods]

[0091] The embodiments described above can be modified as follows: The DC / DC converter Dcv can be changed to a converter that can transform voltage only in the power operation direction, rather than in both the power operation and regeneration directions. In this case, the first and second switches can be replaced with diodes, respectively.

[0092] Instead of the stop determination circuit Jc outputting a stop signal Vb to the switch control circuit Sc, the stop determination circuit Jc can also directly switch each switch Q1U, Q1D, Q2U, and Q2D to be off.

[0093] Based on the above implementation methods, the DC / DC converters shown in Appendix 1 to Appendix 9 can be realized.

[0094] [Postscript 1]

[0095] A DC / DC converter (DCV) having:

[0096] The circuit includes input ports (Pi+, Pi-), input-side capacitors (Ci), a first transformer circuit (Tc1), a second transformer circuit (Tc2), output ports (Po+, Po-), and a switch control circuit (Sc).

[0097] The first transformer circuit (Tc1) includes a first switch (Q1U, Q1D) and a first coil (L1).

[0098] The second transformer circuit (Tc2) includes a second switch (Q2U, Q2D) and a second coil (L2).

[0099] The first coil (L1) and the second coil (L2) are connected in parallel with the input port (Pi+, Pi-) and the input-side capacitor (Ci).

[0100] The switch control circuit (Sc) performs open-loop control of the transformer operation of the first transformer circuit (Tc1) and the second transformer circuit (Tc2) through the control of the first switch (Q1U, Q1D) and the second switch (Q2U, Q2D).

[0101] The power transformed by the transformer action is output from the output port (Po+, Po-).

[0102] in,

[0103] The DC / DC converter (Dcv) has the following features:

[0104] The first detection circuit (A1) detects a first current (It1) as the current flowing through the first coil (L1);

[0105] The first detection circuit (A2) detects the second current (It2) as the current flowing through the second coil (L2);

[0106] The stop determination circuit (Jc) stops the transformer operation based on the difference between the first current (It1) and the second current (It2).

[0107] [Postscript 2]

[0108] According to the DC / DC converter described in Appendix 1, wherein,

[0109] The first switch (Q1U, Q1D) includes a first upper switch (Q1U) and a first lower switch (Q1D).

[0110] The second switch (Q2U, Q2D) includes a second upper switch (Q2U) and a second lower switch (Q2D).

[0111] One end of the first coil (L1) is electrically connected via the first upper switch (Q1U) to the positive terminals of the input port (Pi+, Pi-) and the input-side capacitor (Ci), respectively, and via the first lower switch (Q1D) to the negative terminals of the input port (Pi+, Pi-), the input-side capacitor (Ci), and the output port (Po+, Po-), respectively.

[0112] One end of the second coil (L2) is electrically connected via the second upper switch (Q2U) to the positive terminals of the input port (Pi+, Pi-) and the input-side capacitor (Ci), respectively, and via the second lower switch (Q2D) to the input port (Pi+, Pi-), the input-side capacitor (Ci), and the output port (P). O The terminals on the negative sides of the + and Po- terminals are electrically connected.

[0113] [Postscript 3]

[0114] According to Appendix 1 or 2, the DC / DC converter (Dcv) wherein,

[0115] The DC / DC converter (DCV) transforms the power input to the input ports (Pi+, Pi-) and outputs it from the output ports (Po+, Po-) during power operation; during regeneration, it transforms the power input to the output ports (Po+, Po-) and outputs it from the input ports (Pi+, Pi-).

[0116] The stop determination circuit (Jc) stops the transformer operation based on the difference between the first current (It1) and the second current (It2) during both the power operation and the regeneration operation.

[0117] [Postscript 4]

[0118] According to any one of Appendices 1 to 3, the DC / DC converter (DCV) wherein,

[0119] Based on the difference, the stop determination circuit (Jc) outputs a specified stop signal (Vb) to the switch control circuit (Sc).

[0120] When the switch control circuit (Sc) receives the stop signal (Vb), it stops the transformer operation by controlling the first switch (Q1U, Q1D) and the second switch (Q2U, Q2D).

[0121] [Postscript 5]

[0122] According to the DC / DC converter (Dcv) described in Appendix 4, wherein,

[0123] The first detection circuit (A1) outputs a first voltage (V1) as a voltage based on the magnitude of the first current (It1).

[0124] The second detection circuit (A2) outputs a second voltage (V2) as a voltage based on the magnitude of the second current (It2).

[0125] The stop determination circuit (Jc) includes:

[0126] The first operational amplifier (Ap1) outputs a first differential voltage (ΔV1) based on the value (V1-V2) obtained by subtracting the second voltage (V2) from the first voltage (V1);

[0127] The second operational amplifier (Ap2) outputs a second differential voltage (ΔV2) based on the value (V2-V1) obtained by subtracting the first voltage (V1) from the second voltage (V2);

[0128] The third operational amplifier (Ap3) outputs a voltage as the stop signal (Vb) on the condition that the larger of the first differential voltage (ΔV1) and the second differential voltage (ΔV2) is greater than the threshold voltage (Vth).

[0129] [Postscript 6]

[0130] According to any one of Appendices 1 to 5, the DC / DC converter (Dcv) wherein,

[0131] The stop determination circuit stops the transformer operation when the absolute value of the difference (It1-It2) between the value of the first current (It1) and the value of the second current (It2) is greater than a threshold (Ith).

[0132] [Postscript 7]

[0133] According to any one of Appendices 1 to 5, the DC / DC converter (Dcv) wherein,

[0134] The stop determination circuit stops the transformer operation when the absolute value of the increase in the difference (It1-It2) between the value of the first current (It1) and the value of the second current (It2) is greater than a threshold.

[0135] [Postscript 8]

[0136] According to the DC / DC converter (Dcv) described in Appendix 5, wherein,

[0137] The stop determination circuit stops the transformer operation when the absolute value of the increase in the difference (It1-It2) between the values ​​of the first current (It1) and the second current (It2) exceeds a threshold.

[0138] The output terminal of the first operational amplifier (Ap1) is electrically connected to the inverting input terminal of the first operational amplifier (Ap1) via a first feedback resistor (R7) and a first capacitor (C1) connected in parallel.

[0139] The output terminal of the second operational amplifier (Ap2) is electrically connected to the inverting input terminal of the second operational amplifier (Ap2) via a second feedback resistor (R8) and a second capacitor (C2) connected in parallel.

[0140] [Postscript 9]

[0141] According to any one of Appendices 1 to 8, the DC / DC converter (Dcv) wherein,

[0142] The stop determination circuit (Jc) outputs a specified signal (Vb) to the specified alarm device (Nd) when the transformer operation is stopped.

[0143] The alarm device (Nd) issues an alarm when it receives the signal (Vb).

[0144] Explanation of reference numerals in the attached figures

[0145] A1 First Detection Circuit

[0146] A2 Second Detection Circuit

[0147] Ap1 First Operational Amplifier

[0148] Ap2 Second Operational Amplifier

[0149] Ap3 Third Operational Amplifier

[0150] C1 First capacitor

[0151] C2 Second capacitor

[0152] Ci input-side capacitor

[0153] DC / DC converter

[0154] It1 First Current

[0155] It2 Second Current

[0156] Ith threshold

[0157] Jc Stop Detection Circuit

[0158] L1 First coil

[0159] L2 Second Coil

[0160] Nd alarm device

[0161] Pi+ Input Port

[0162] Pi - Input Port

[0163] Po+ output port

[0164] Po- Output Port

[0165] Q1U First switch (first switch)

[0166] Q1D First Switch (First Switch)

[0167] Q2U Second Upper Switch (Second Switch)

[0168] Q2D Second Switch (Second Switch)

[0169] R7 Seventh resistor (first feedback resistor)

[0170] R8 is the eighth resistor (second feedback resistor).

[0171] Sc switch control circuit

[0172] Tc1 First Transformer Circuit

[0173] Tc2 Second Transformer Circuit

[0174] V1 First Voltage

[0175] V2 Second Voltage

[0176] Vb Stop signal (specified signal)

[0177] Vth threshold voltage

[0178] ΔV1 First differential voltage

[0179] ΔV2 is the second differential voltage.

Claims

1. A DC / DC converter, comprising: Input port, input-side capacitor, first transformer circuit, second transformer circuit, output port, and switch control circuit. The first transformer circuit includes a first switch and a first coil. The second transformer circuit includes a second switch and a second coil. The first coil and the second coil are connected in parallel with the input port and the input-side capacitor. The switch control circuit performs open-loop control of the transformation operation of the first transformer circuit and the second transformer circuit through the control of the first switch and the second switch. The power, transformed by the transformer action, is output from the output port. Its features are, The DC / DC converter has the following features: The first detection circuit detects a first current as the current flowing through the first coil; The second detection circuit detects a second current as the current flowing through the second coil; The stop determination circuit stops the transformer operation based on the difference between the first current and the second current.

2. The DC / DC converter according to claim 1, characterized in that, The first switch includes a first upper switch and a first lower switch. The second switch includes a second up switch and a second down switch. One end of the first coil is electrically connected via the first upper switch to the positive terminals of the input port and the input-side capacitor, respectively, and via the first lower switch to the negative terminals of the input port, the input-side capacitor, and the output port, respectively. One end of the second coil is electrically connected to the positive terminals of the input port and the input-side capacitor via the second upper switch, and is electrically connected to the negative terminals of the input port, the input-side capacitor and the output port via the second lower switch.

3. The DC / DC converter according to claim 1 or 2, characterized in that, When the DC / DC converter is in operation, it transforms the power input to the input port and outputs it from the output port; when regenerating, it transforms the power input to the output port and outputs it from the input port. The stop determination circuit stops the transformer operation based on the difference between the first current and the second current during both the power operation and the regeneration operation.

4. The DC / DC converter according to any one of claims 1 to 3, characterized in that, Based on the difference, the stop determination circuit outputs a specified stop signal to the switch control circuit. When the switch control circuit receives the stop signal, it stops the transformer operation by controlling the first switch and the second switch.

5. The DC / DC converter according to claim 4, characterized in that, The first detection circuit outputs a first voltage based on the magnitude of the first current. The output of the second detection circuit is a second voltage based on the magnitude of the second current. The stop determination circuit includes: A first operational amplifier whose output is a first differential voltage based on the value obtained by subtracting the second voltage from the first voltage; The second operational amplifier outputs a second differential voltage based on the value obtained by subtracting the first voltage from the second voltage; The third operational amplifier outputs a voltage as the stop signal, provided that the larger of the first differential voltage and the second differential voltage is greater than a threshold voltage.

6. The DC / DC converter according to any one of claims 1 to 5, characterized in that, The stop determination circuit stops the transformer operation when the absolute value of the difference between the value of the first current and the value of the second current is greater than a threshold.

7. The DC / DC converter according to any one of claims 1 to 5, characterized in that, The stop determination circuit stops the transformer operation when the absolute value of the increase in the difference between the first current and the second current is greater than a threshold.

8. The DC / DC converter according to claim 5, characterized in that, The stop determination circuit stops the transformer operation when the absolute value of the increase in the difference between the first current and the second current exceeds a threshold. The output terminal of the first operational amplifier is electrically connected to the inverting input terminal of the first operational amplifier via a first feedback resistor and a first capacitor connected in parallel. The output terminal of the second operational amplifier is electrically connected to the inverting input terminal of the second operational amplifier via a second feedback resistor and a second capacitor connected in parallel.

9. The DC / DC converter according to any one of claims 1 to 8, characterized in that, The stop determination circuit outputs a specified signal to a designated alarm device when the transformer operation is stopped. The alarm device sounds an alarm when it receives the signal.

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