Switching power supply and electrical equipment

Abstract

The present invention provides a switching power supply device and electrical equipment that can change the output depending on the direction of the flowing current and the ON / OFF state of a switching element based on the voltage of an auxiliary winding on the primary side, and can appropriately change the judgment threshold in a short period of time. [Solution] A switching power supply that operates a switching element to induce a pulse voltage, comprising: a comparator having a first input terminal, a second input terminal, and an output terminal; a primary-side voltage detection terminal that detects the voltage of a primary-side auxiliary winding; and a gate signal response terminal whose output voltage changes depending on whether a gate signal is HI or LOW, wherein the primary-side voltage detection terminal is connected to the first input terminal of the comparator, and the gate signal response terminal is connected to the first input terminal or the second input terminal of the comparator, and the output of the output terminal of the comparator changes depending on the detected voltage of the primary-side auxiliary winding and the gate signal.

Description

[Technical Field]

[0001] The present disclosure relates to a switching power supply device and an electric device. [Background technology]

[0002] Generally, switching power supplies have an overcurrent protection (OCP) function for safety reasons. Switching power supplies have several operating states (operating modes), such as a normal state (normal mode) and a standby state (standby mode), and there has been a demand for an OCP threshold that can be changed appropriately depending on the operating state.

[0003] Various studies have been carried out to address this issue, and proposals such as those in Patent Documents 1 to 3 have been disclosed.

[0004] Patent Document 1 aims to provide a power supply control device that can reduce power consumption under light load or no load conditions, and discloses a power supply control device that acts as the main controller of an isolated switching power supply, and is characterized by having a controller that monitors a first output detection signal that corresponds to the DC output voltage to the load and a second output detection signal that corresponds to the difference between the DC output voltage and its target value, and switches between multiple operating modes with different power consumption depending on the results of both monitoring.

[0005] Patent Document 2 discloses a switching power supply device that prevents a large current from flowing when the output voltage is set low, thereby eliminating the need to select components to accommodate a large output current. The switching power supply device has an overcurrent protection circuit that sets the overcurrent limit to a first overcurrent limit when switched to a first output voltage and sets the overcurrent limit to a second overcurrent limit when switched to a second output voltage, and an oscillator circuit that sets the maximum limit of the switching frequency to a first maximum switching frequency when the overcurrent limit is the first overcurrent limit and sets the maximum limit of the switching frequency to a second maximum switching frequency when the overcurrent limit is the second overcurrent limit. Here, switching from the first output voltage to the second output voltage can be considered to be similar to switching from normal mode to standby mode.

[0006] Patent Document 3 aims to provide a switching power supply that can adjust the overcurrent protection reference voltage using a first external resistor and that corrects the overcurrent protection reference voltage to be smaller at high input voltages in order to solve the conventional problem of maximum power being higher at high input voltages than at low input voltages, and discloses a switching power supply that corrects the overcurrent protection reference voltage according to a first DC voltage obtained by connecting to a first primary winding of a transformer. Here, switching from a high input voltage to a low input voltage can be considered to be similar to switching from normal mode to standby mode. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-122240 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-127109 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-343900 Summary of the Invention [Problem to be solved by the invention]

[0008] In this way, for example, Patent Documents 1 to 3 show that it has become possible to appropriately change the determination threshold for overcurrent protection depending on the operating state.

[0009] However, there is a problem of delay in judgment immediately after the operating state changes. For example, when switching from the normal state to the standby state, even if the judgment threshold is changed, there is a time delay before the judgment starts, and there is a problem that the judgment immediately after the operating state changes cannot be performed properly.

[0010] Furthermore, when we look at the current on the primary side of a switching power supply, the current value changes depending on the direction of the flow of current, and furthermore, the current value also changes depending on whether the switching element is turned on or off. Therefore, the conventional approach of maintaining the same judgment threshold value throughout a single operating state has the problem of being unable to respond to such instantaneous changes in current value at the switching cycle level.

[0011] The present disclosure has been made to solve the above problems, and aims to provide a switching power supply and electrical equipment that can change the output depending on the direction of the flowing current and the ON / OFF state of the switching element based on the voltage of the auxiliary winding on the primary side, and that can change the decision threshold appropriately in a short time. [Means for solving the problem]

[0012] In order to solve the above-described problems, the switching power supply device of the present disclosure is a switching power supply device that induces a pulse voltage by performing a switching operation on a switching element, and includes a comparator having a first input terminal, a second input terminal, and an output terminal, a primary-side voltage detection terminal that detects the voltage of a primary-side auxiliary winding, and a gate signal response terminal whose output voltage changes depending on whether a gate signal of the switching element is HI or LOW, wherein the primary-side voltage detection terminal is connected to the first input terminal of the comparator, and the gate signal response terminal is connected to the first input terminal or the second input terminal of the comparator, and the output of the output terminal of the comparator changes depending on the detected voltage of the primary-side auxiliary winding and the gate signal.

[0013] In such a switching power supply, first, the primary-side voltage detection terminal detects the voltage of the primary-side auxiliary winding, thereby detecting changes according to the direction of current flowing to the primary side, then the gate signal response terminal detects changes in detection voltage depending on whether the gate signal of the switching element is HI or LOW, thereby detecting changes according to the ON / OFF of the switching element, and then the output of the comparator output terminal changes according to the detected voltage of the primary-side auxiliary winding and the gate signal.As a result, the output of the comparator output terminal changes according to the direction of current flow and the ON / OFF of the switching element based on the voltage of the primary-side auxiliary winding, making it possible to change the decision threshold appropriately in a short time.

[0014] Furthermore, it is preferable that the detected voltage of the primary-side auxiliary winding is a forward voltage and a flyback voltage, and that the forward voltage and the flyback voltage are detected at a common primary-side voltage detection terminal.

[0015] The forward voltage and flyback voltage flow in opposite directions, and by detecting the forward voltage and flyback voltage at a common primary side voltage detection terminal, changes in the direction of the flowing current can be reliably detected.

[0016] Furthermore, it is preferable that the switching power supply device has a transformer with an auxiliary winding on the primary side, a primary winding, and a secondary winding, thereby forming a primary side and a secondary side, the detected voltage of the auxiliary winding on the primary side is the forward voltage and the flyback voltage applied to the auxiliary winding on the primary side, and the primary side voltage detection terminal is connected to the auxiliary winding on the primary side to detect the forward voltage and the flyback voltage.

[0017] By using such a transformer, it is possible to reliably detect the forward voltage and the flyback voltage, and to detect changes according to the direction of the flowing current.

[0018] It is also preferable that a first resistor, a second resistor, and a Zener diode are connected in series in this order from the ground side of the primary-side auxiliary winding, the primary-side voltage detection terminal is connected between the first resistor and the second resistor, and the gate signal response terminal is connected to the second input terminal of the comparator.

[0019] In a switching power supply connected in this manner, the voltage at the first input terminal of the comparator connected to the primary side voltage detection terminal changes depending on the direction of the flowing current, and the voltage at the second input terminal of the comparator connected to the gate signal response terminal changes depending on the ON / OFF state of the switching element.As a result, the output of the comparator changes reliably depending on the direction of the flowing current and the ON / OFF state of the switching element.

[0020] It is also preferable that a Schottky barrier diode and a third resistor are connected in series in this order from the ground side of the primary-side auxiliary winding, the primary-side voltage detection terminal is connected between the Schottky barrier diode and the third resistor, and the gate signal response terminal is connected to the first input terminal of the comparator.

[0021] In a switching power supply device connected in this manner, the voltage at the first input terminal of the comparator connected to the primary side voltage detection terminal changes depending on the direction of the flowing current, and furthermore, the voltage at the first input terminal of the comparator connected to the gate signal response terminal changes depending on the ON / OFF state of the switching element, so that the output of the comparator changes reliably depending on the direction of the flowing current and the ON / OFF state of the switching element.

[0022] It is also preferable that the inverter has a protection function of determining an overvoltage on at least one of the primary side and the secondary side in response to the output of the output terminal of the comparator and stopping the switching operation.

[0023] A switching power supply device with such a protection function can quickly and appropriately determine overvoltage on at least one of the primary and secondary sides and stop switching operation according to the output of the comparator output terminal, which changes depending on the direction of the flowing current and the ON / OFF state of the switching element, thereby providing a protection function that is extremely safe and allows for fast and precise determination.

[0024] Furthermore, the electrical device of the present disclosure preferably includes the above-described switching power supply device.

[0025] By using a switching power supply device that can appropriately change the determination threshold in a short time, such electrical equipment can be made highly reliable and free from delays in determination or erroneous determination. [Effects of the Invention]

[0026] As described above, the switching power supply device of the present disclosure can first detect changes in the direction of current flowing to the primary side by detecting the voltage of the primary-side auxiliary winding at the primary-side voltage detection terminal, then detect changes in the detection voltage at the gate signal response terminal depending on whether the gate signal of the switching element is HI or LOW, thereby detecting changes in the ON / OFF state of the switching element, and further change the output of the comparator output terminal depending on the detected voltage of the primary-side auxiliary winding and the gate signal. As a result, the output of the comparator output terminal changes depending on the direction of current flow and the ON / OFF state of the switching element based on the voltage of the primary-side auxiliary winding, making it possible to change the decision threshold appropriately in a short time. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a circuit configuration diagram of a switching power supply device according to a first embodiment of the present disclosure. [Figure 2] 1 is a circuit configuration diagram of a main part of a switching power supply device according to a first embodiment of the present disclosure. [Figure 3] 10 is a graph showing changes in voltage at each part relative to an input voltage. [Figure 4] 10 is a graph showing a change in voltage of an auxiliary winding on the primary side relative to an output voltage. [Figure 5] FIG. 10 is a circuit configuration diagram of a main part of a switching power supply device according to a second embodiment of the present disclosure. [Figure 6] FIG. 1 is a circuit configuration diagram of a main part of a switching power supply device according to a reference embodiment. [Figure 7] 1 is a diagram illustrating an air conditioner as an electrical appliance equipped with a switching power supply device according to the present disclosure. [Figure 8] FIG. 1 is a circuit configuration diagram of a conventional switching power supply device. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present disclosure will be described in detail below, but the present disclosure is not limited thereto.

[0029] As described above, there has been a demand for a switching power supply device and an electrical device that can change the output in accordance with the direction of the flowing current and the ON / OFF state of the switching element based on the voltage of the auxiliary winding on the primary side, and that can change the decision threshold appropriately in a short period of time.

[0030] As a result of extensive research, the inventors have found that the above-mentioned problems can be solved by providing a primary-side voltage detection terminal that detects the voltage of an auxiliary winding on the primary side of a switching power supply device and a gate signal response terminal whose output voltage changes depending on whether the gate signal of the switching element is HI or LOW, and by appropriately connecting this primary-side voltage detection terminal and gate signal response terminal to the input terminal of a comparator, and have completed the present disclosure.

[0031] That is, the present disclosure provides a switching power supply device that induces a pulse voltage by performing a switching operation on a switching element, the switching power supply device comprising: a comparator having a first input terminal, a second input terminal, and an output terminal; a primary-side voltage detection terminal that detects the voltage of a primary-side auxiliary winding; and a gate signal response terminal whose output voltage changes depending on whether a gate signal of the switching element is HI or LOW, the primary-side voltage detection terminal being connected to the first input terminal of the comparator, and the gate signal response terminal being connected to the first input terminal or the second input terminal of the comparator, and the output of the output terminal of the comparator changing depending on the detected voltage of the primary-side auxiliary winding and the gate signal.

[0032] The present disclosure also relates to an electrical device including the above-described switching power supply device.

[0033] The following description will be made with reference to the drawings.

[0034] [First embodiment: switching power supply device] Fig. 1 is a circuit diagram of a switching power supply device according to a first embodiment of the present disclosure, and Fig. 2 is a circuit diagram of the main parts of Fig. 1. Figs. 3 and 4 are graphs showing the time changes in voltage at each part, and in particular Fig. 3 shows the change in voltage at each part relative to the input voltage, and Fig. 4 shows the change in voltage at the primary-side auxiliary winding relative to the output voltage.

[0035] The switching power supply device of the present disclosure is a switching power supply device that induces a pulse voltage by switching operation of a switching element Q1, and is equipped with a comparator 14 having a first input terminal 11, a second input terminal 12, and an output terminal 13, a primary-side voltage detection terminal 15 that detects the voltage of a primary-side auxiliary winding D, and a gate signal response terminal 16 whose output voltage changes depending on whether a gate signal G of the switching element Q1 is HI or LOW, wherein the primary-side voltage detection terminal 15 is connected to the first input terminal 11 of the comparator 14, and the gate signal response terminal 16 is connected to the second input terminal 12 of the comparator 14, and the output of the output terminal 13 of the comparator 14 changes depending on the detected voltage of the primary-side auxiliary winding D and the gate signal G.

[0036] In such a switching power supply, first, the voltage of the primary-side auxiliary winding D is detected by primary-side voltage detection terminal 15, thereby detecting changes according to the direction of current flowing on the primary side, then the gate signal response terminal 16 changes its detection voltage depending on whether the gate signal G of switching element Q1 is HI or LOW, thereby detecting changes according to the ON / OFF of switching element Q1, and further the output of output terminal 13 of comparator 14 changes according to the detected voltage of the primary-side auxiliary winding D and the gate signal G. As a result, the output of output terminal 13 of comparator 14 changes according to the direction of current flow and the ON / OFF of the switching element based on the voltage of the primary-side auxiliary winding D, thereby making it possible to change the decision threshold appropriately in a short time.

[0037] Furthermore, although not particularly limited, the detected voltage of the primary side auxiliary winding D is a forward voltage (voltage when the current flows in the forward direction) and a flyback voltage (voltage when the current flows in the reverse direction), and it is preferable to detect the forward voltage and the flyback voltage at a common primary side voltage detection terminal 15.

[0038] The forward voltage and the flyback voltage flow in opposite directions, and by detecting the forward voltage and the flyback voltage at the common primary side voltage detection terminal 15, changes according to the direction of the flowing current can be reliably detected.

[0039] Furthermore, although not particularly limited, the switching power supply device has a transformer 17 equipped with a primary-side auxiliary winding D, primary-side windings P1 and P2, and secondary-side windings S1 and S2, thereby constituting a primary side A1 and a secondary side A2, and the detected voltage of the primary-side auxiliary winding D is the forward voltage and flyback voltage applied to the primary-side auxiliary winding D, and it is preferable that the primary-side voltage detection terminal 15 is connected to the primary-side auxiliary winding D to detect the forward voltage and flyback voltage.

[0040] By using such a transformer 17, it is possible to reliably detect the forward voltage and the flyback voltage, and to detect changes according to the direction of the flowing current.

[0041] Furthermore, although not particularly limited, it is preferable that a first resistor R1, a second resistor R2, and a Zener diode D1 are connected in series in this order from the ground 18 side of the primary-side auxiliary winding D, that the primary-side voltage detection terminal 15 is connected between the first resistor R1 and the second resistor R2, and that the gate signal response terminal 16 is connected to the second input terminal 12 of the comparator 14.

[0042] In a switching power supply connected in this manner, the voltage at the first input terminal 11 of the comparator 14 connected to the primary side voltage detection terminal 15 changes depending on the direction of the flowing current, and the voltage at the second input terminal 12 of the comparator 14 connected to the gate signal response terminal 16 changes depending on the ON / OFF state of the switching element Q1. As a result, the output of the comparator 14 changes reliably depending on the direction of the flowing current and the ON / OFF state of the switching element Q1.

[0043] As shown in FIG. 1, the input voltage of this switching power supply can be expressed as Vin and the output voltage as Vo.

[0044] 3 shows the change in voltage of each part with respect to the input voltage in this embodiment. Fig. 3(a) shows the input voltage Vin, Fig. 3(b) shows the voltage of the auxiliary winding D on the primary side, and the positive side shows the flyback voltage V REV1 , the negative side is the forward voltage V FW1 When the input voltage Vin increases, the flyback voltage V REV1 does not change, but the forward voltage V FW1 increases in proportion to the input voltage Vin.

[0045] Also, Figure 3(c) shows the voltage V of the Zener diode D1. DZBD , Figure 3(d) shows the voltage V of the primary side voltage detection terminal 15. FW2 The input voltage Vin rises and the forward voltage V FW1 is the voltage V Z If this happens, V will be generated as shown in B, C, and D in the figure. FW2 generates a negative voltage.

[0046] Therefore, the simplest way to use it is to check the voltage V at the primary side voltage detection terminal 15. FW2 can be set as the judgment threshold for the protection function that protects against overvoltage of the input voltage Vin. For example, if a judgment threshold is set between B and C in Figure 3(d), A and B do not exceed the judgment threshold and are therefore determined not to be overvoltage, allowing operation to continue as is, while C and D exceed the judgment threshold and are therefore determined to be overvoltage, allowing operation to be stopped immediately.

[0047] Furthermore, instead of using it directly as a judgment threshold in this way, it is conceivable to use it to adjust the judgment threshold. For example, even if none of A, B, C, and D corresponds to an overvoltage, it is possible to adjust the judgment threshold finely by lowering the judgment threshold in case A (i.e., when the input voltage Vin is low) and raising the judgment threshold in case D (i.e., when the input voltage Vin is high).

[0048] 4 shows the change in the voltage of the primary-side auxiliary winding D with respect to the output voltage in this embodiment. FIG. 4(a) shows the output voltage Vo, and FIG. 4(b) shows the voltage of the primary-side auxiliary winding D, with the positive side showing the flyback voltage V REV1 , the negative side is the forward voltage V FW1 When the output voltage Vo increases, the flyback voltage V REV1 also increases proportionally.

[0049] Therefore, the simplest way to use it is to use the flyback voltage V REV1 It is possible to set this as a determination threshold for the protection function that protects the output voltage Vo from an overvoltage.

[0050] Furthermore, instead of using it directly as a decision threshold, it can be used to adjust the decision threshold. For example, the flyback voltage V REV1 V cc Even if there is no overvoltage protection (OVP) at the terminal, the flyback voltage V REV1 By setting a determination threshold when the output voltage Vo is low (that is, when the output voltage Vo is low), it is possible to make a more precise determination.

[0051] Although not particularly limited, it is preferable to have a protection function that judges an overvoltage on at least one of the primary side A1 and the secondary side A2 according to the output of the output terminal 13 of the comparator 14 and stops the switching operation.

[0052] A switching power supply device having such a protection function can appropriately determine overvoltage on at least one of the primary side A1 and secondary side A2 in a short time and stop switching operation according to the output of output terminal 13 of comparator 14, which changes according to the direction of the flowing current and the ON / OFF state of the switching element, thereby enabling fast and precise determination and providing an extremely safe protection function.

[0053] For reference, the circuit configuration diagram of this embodiment (FIG. 1) is shown in contrast to the conventional circuit configuration diagram in FIG. 8. First, comparing FIG. 1 and FIG. 8, it can be seen that FIG. 1 of this embodiment does not have particularly more components than the conventional FIG. 8.

[0054] Also, referring to FIG. 8, conventionally, the input voltage Vin, which is assumed to be a high voltage such as 400 V, is divided by resistors R11, R12, R13, and R14 and detected at the detection terminal 25. Therefore, a voltage resistance to the high input voltage Vin is required, and the number of resistors is increased.

[0055] In contrast to this, in FIG. 1 of this embodiment, connection to a high input line as in the conventional example shown in FIG. 8 is not necessary, and the pattern layout becomes easier.

[0056] 8, only switching between normal mode and standby mode was possible. In contrast, in the case of the present embodiment shown in FIGS. 1 and 2, the output of output terminal 13 of comparator 14 changes in response to the detected voltage of primary-side auxiliary winding D and gate signal G. Therefore, by first detecting the voltage of primary-side auxiliary winding D at primary-side voltage detection terminal 15, it is possible to detect a change in the direction of current flowing to the primary side. Next, gate signal response terminal 16 detects a change in detection voltage depending on whether gate signal G of switching element Q1 is HIGH or LOW, thereby detecting a change in the ON / OFF state of switching element Q1. Furthermore, the output of output terminal 13 of comparator 14 changes in response to the detected voltage of primary-side auxiliary winding D and gate signal G. As a result, the output of comparator 14 changes in response to the direction of current flow and the ON / OFF state of switching element Q1 based on the voltage of primary-side auxiliary winding D, and the decision threshold can be appropriately changed in a short time (at the switching cycle level) in response to this output.

[0057] Therefore, in this embodiment, the judgment threshold can be changed not only when switching between operation modes such as normal mode and standby mode, but also when an instantaneous change in voltage value at the switching period level occurs within the same operation mode, and judgment can be made using an appropriate judgment threshold without any time delay even immediately after the operation mode has changed.

[0058] [Second embodiment: switching power supply device] FIG. 5 is a circuit configuration diagram of a main part of a switching power supply device according to the second embodiment of the present disclosure.

[0059] The switching power supply device of the present disclosure is a switching power supply device that induces a pulse voltage by performing switching operations on a switching element, and is equipped with a comparator 14 having a first input terminal 11, a second input terminal 12, and an output terminal 13, a primary-side voltage detection terminal 19 that detects the voltage of a primary-side auxiliary winding D, and a gate signal response terminal 20 whose output voltage changes depending on whether a gate signal G of the switching element is HI or LOW, wherein the primary-side voltage detection terminal 19 is connected to the first input terminal 11 of the comparator 14, and the gate signal response terminal 20 is also connected to the first input terminal 11 of the comparator 14, and the output of the output terminal 13 of the comparator 14 changes depending on the detected voltage of the primary-side auxiliary winding D and the gate signal G.

[0060] In such a switching power supply device, first, the voltage of the primary-side auxiliary winding D is detected by the primary-side voltage detection terminal 19, thereby making it possible to detect changes according to the direction of current flowing to the primary side, then the gate signal response terminal 20 changes its detection voltage depending on whether the gate signal G of the switching element is HI or LOW, thereby making it possible to detect changes according to the ON / OFF of the switching element, and further the output of the output terminal 13 of the comparator 14 changes according to the detected voltage of the primary-side auxiliary winding D and the gate signal G. As a result, the output of the output terminal 13 of the comparator 14 changes according to the direction of current flow and the ON / OFF of the switching element based on the voltage of the primary-side auxiliary winding D, making it possible to change the decision threshold appropriately in a short time.

[0061] Furthermore, although not particularly limited, the detected voltage of the primary side auxiliary winding D is a forward voltage and a flyback voltage, and it is preferable that the forward voltage and the flyback voltage are detected at a common primary side voltage detection terminal 19.

[0062] The forward voltage and the flyback voltage flow in opposite directions, and by detecting the forward voltage and the flyback voltage at the common primary side voltage detection terminal 19, changes according to the direction of the flowing current can be reliably detected.

[0063] Furthermore, although not particularly limited, the switching power supply device has a primary-side auxiliary winding D and a transformer with a primary-side winding and a secondary-side winding, thereby forming a primary side and a secondary side, and the detected voltage of the primary-side auxiliary winding D is the forward voltage and flyback voltage applied to the primary-side auxiliary winding D, and it is preferable that the primary-side voltage detection terminal 19 is connected to the primary-side auxiliary winding D to detect the forward voltage and flyback voltage.

[0064] By using such a transformer, it is possible to reliably detect the forward voltage and the flyback voltage, and to detect changes according to the direction of the flowing current.

[0065] Furthermore, although not particularly limited, it is preferable that, in this order from the ground 18 side of the primary-side auxiliary winding D, a Schottky barrier diode D2 and a third resistor R3 are connected in series, the primary-side voltage detection terminal 19 is connected between the Schottky barrier diode D2 and the third resistor R3, and the gate signal response terminal 20 is connected to the first input terminal 11 of the comparator 14.

[0066] In a switching power supply connected in this manner, the voltage at first input terminal 11 of comparator 14 connected to primary side voltage detection terminal 19 changes depending on the direction of the flowing current, and further, the voltage at first input terminal 11 of comparator 14 connected to gate signal response terminal 20 changes depending on the ON / OFF state of the switching element, so that the output of comparator 14 changes reliably depending on the direction of the flowing current and the ON / OFF state of the switching element.

[0067] Here, for reference, we will try to calculate the voltage at the primary side voltage detection terminal 19 with reference to Figure 5. In Figure 5, Q11 and Q12 are switching elements, Ra and Rb are resistors, V1, V2, V3, V Reg , V forward , V flyback is the voltage, and in particular, the voltage at the primary side voltage detection terminal 19 is V1, and the forward voltage of the primary side auxiliary winding D is V forward , the flyback voltage is V flyback is.

[0068] (1) Forward voltage Q11 is ON and V2=V Reg , Q12 is OFF and V3=V1. Therefore, the voltage V1 at the primary side voltage detection terminal 19 is V1=V forward ×Ra / (Ra+R3)

[0069] (2) Flyback voltage When Q11 is OFF, V2 = V1, and when Q12 is ON, V3 = 0 (GND). Therefore, the voltage V1 at the primary side voltage detection terminal 19 is V1=(V flyback ×Rb+V Reg ×R3) / (Rb+R3)

[0070] From the above equation, an advantage of this embodiment is that the level of the voltage V1 at the primary side voltage detection terminal 19 can be freely changed by the resistance values ​​of Ra, Rb, and R3.

[0071] [Reference form: Switching power supply] FIG. 6 is a circuit configuration diagram of the main part of a switching power supply device according to a reference embodiment.

[0072] The right side of FIG. 6 showing the reference embodiment is the same as the right side of FIG. 2 showing the first embodiment, but the left side is different.

[0073] In this embodiment, although not limited to this, there are multiple comparators 14a, 14b, and 14c, each of which has a different purpose, such as for the forward voltage, the flyback voltage, and the voltage detection signal during flyback standby.

[0074] Even with this configuration, it is possible to detect changes in the direction of the current flowing on the primary side by detecting the voltage of the primary-side auxiliary winding D with the primary-side voltage detection terminal 15, and the outputs of the output terminals of the comparators 14a, 14b, and 14c change in accordance with the detected voltage of the primary-side auxiliary winding D. As a result, the outputs of the output terminals of the comparators 14a, 14b, and 14c change in accordance with the direction of the current flowing based on the voltage of the primary-side auxiliary winding D, and the decision threshold can be changed appropriately in a short time.

[0075] Furthermore, although the number of comparators increases in this embodiment, each can be designed individually for each purpose, which has the effect of facilitating design.

[0076] [Electrical Equipment] Furthermore, an embodiment of an electrical device including a switching power supply device according to the present disclosure will be described with reference to FIG.

[0077] Although not particularly limited, the electrical device of the present disclosure preferably includes the above-described switching power supply device.

[0078] By using a switching power supply device that can appropriately change the determination threshold in a short time, such electrical equipment can be made highly reliable and free from delays in determination or erroneous determination.

[0079] The electrical equipment is not particularly limited, but the above-described switching power supply device can be suitably applied to electrical equipment for driving compressors such as air conditioners and refrigerators, or the main motor of washing machines.

[0080] FIG. 7 is a diagram illustrating an air conditioner 300 as an electrical appliance equipped with a switching power supply device according to the fourth embodiment of the present disclosure.

[0081] Air conditioner 300 comprises indoor unit 310 and outdoor unit 320, each equipped with fan motors 311, 321, compressor 322, and switching power supply device 200. It is advisable to use switching power supply device 200 with specifications suited to driving the respective motors and compressors.

[0082] The present disclosure encompasses the following aspects. [1]: A switching power supply device that induces a pulse voltage by switching a switching element, a comparator having a first input terminal, a second input terminal, and an output terminal; a primary side voltage detection terminal for detecting the voltage of the primary side auxiliary winding; a gate signal response terminal whose output voltage changes depending on whether the gate signal of the switching element is HI or LOW; Equipped with the primary side voltage detection terminal is connected to the first input terminal of the comparator; the gate signal response terminal is connected to the first input terminal or the second input terminal of the comparator; a gate signal that is supplied to the output terminal of the comparator and that is connected to the auxiliary winding; [2]: The detected voltage of the primary-side auxiliary winding is a forward voltage and a flyback voltage; The switching power supply device according to [1] above, wherein the forward voltage and the flyback voltage are detected by a common primary side voltage detection terminal. [3]: the switching power supply device includes a transformer having an auxiliary winding on the primary side, a winding on the primary side, and a winding on the secondary side, thereby forming a primary side and a secondary side; the detected voltage of the primary-side auxiliary winding is the forward voltage and the flyback voltage applied to the primary-side auxiliary winding; The switching power supply device according to [2] above, characterized in that the primary side voltage detection terminal is connected to the primary side auxiliary winding to detect the forward voltage and the flyback voltage. [4]: a first resistor, a second resistor, and a Zener diode are connected in series in this order from the ground side of the primary-side auxiliary winding; the primary-side voltage detection terminal is connected between the first resistor and the second resistor; The switching power supply device according to any one of [1] to [3] above, wherein the gate signal response terminal is connected to the second input terminal of the comparator. [5]: a Schottky barrier diode and a third resistor are connected in series in this order from the ground side of the auxiliary winding on the primary side; the primary-side voltage detection terminal is connected between the Schottky barrier diode and the third resistor; The switching power supply device according to any one of [1] to [3] above, wherein the gate signal response terminal is connected to the first input terminal of the comparator. [6]: The switching power supply device according to any one of [1] to [5] above, characterized in that it has a protection function of determining an overvoltage on at least one of the primary side and the secondary side according to the output of the output terminal of the comparator, and stopping the switching operation. [7]: An electrical device comprising the switching power supply device according to any one of [1] to [6] above.

[0083] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Explanation of symbols]

[0084] 11...first input terminal; 12...second input terminal; 13...output terminal; 14, 14a, 14b, 14c...Comparators, 15, 19... Primary side voltage detection terminals; 16, 20... Gate signal response terminals; 17...Transformer, 18...Ground, 25...Detection terminal, 200...Switching power supply unit, 300...Air conditioner, 310...Indoor unit, 311, 321...fan motor, 320...outdoor unit, 322...compressor. A1...primary side, A2...secondary side, D...primary side auxiliary winding, D1: Zener diode, D2: Schottky barrier diode, G: Gate signal, P1, P2: Primary winding, Q1, Q11, Q12...switching elements, R1...first resistor, R2...second resistor, R3...third resistor, R11, R12, R13, R14, Ra, Rb...Resistance, S1, S2: Secondary windings, V1, V FW2 …Voltage at the primary side voltage detection terminal, V2, V3, V Reg , V Z …voltage, V DZBD …Zener diode voltage, V flyback , V REV1 …flyback voltage, V forward , V FW1 …forward voltage, Vin…input voltage, Vo...output voltage.

Claims

1. A switching power supply device that induces a pulse voltage by switching a switching element, a comparator having a first input terminal, a second input terminal, and an output terminal; a primary side voltage detection terminal for detecting the voltage of the primary side auxiliary winding; a gate signal response terminal whose output voltage changes depending on whether the gate signal of the switching element is HIGH or LOW; Equipped with the primary side voltage detection terminal is connected to the first input terminal of the comparator; the gate signal response terminal is connected to the first input terminal or the second input terminal of the comparator; a gate signal that is supplied to the output terminal of the comparator and that is connected to the auxiliary winding;

2. The detected voltage of the primary-side auxiliary winding is a forward voltage and a flyback voltage; 2. The switching power supply device according to claim 1, wherein the forward voltage and the flyback voltage are detected at a common primary side voltage detection terminal.

3. the switching power supply device includes a transformer having an auxiliary winding on the primary side, a winding on the primary side, and a winding on the secondary side, thereby forming a primary side and a secondary side; the detected voltage of the primary-side auxiliary winding is the forward voltage and the flyback voltage applied to the primary-side auxiliary winding; 3. The switching power supply device according to claim 2, wherein the primary-side voltage detection terminal is connected to an auxiliary winding on the primary side to detect the forward voltage and the flyback voltage.

4. a first resistor, a second resistor, and a Zener diode are connected in series in this order from the ground side of the primary-side auxiliary winding; the primary-side voltage detection terminal is connected between the first resistor and the second resistor; 4. The switching power supply device according to claim 3, wherein the gate signal response terminal is connected to the second input terminal of the comparator.

5. a Schottky barrier diode and a third resistor are connected in series in this order from the ground side of the auxiliary winding on the primary side; the primary-side voltage detection terminal is connected between the Schottky barrier diode and the third resistor; 4. The switching power supply device according to claim 3, wherein the gate signal response terminal is connected to the first input terminal of the comparator.

6. 2. The switching power supply device according to claim 1, further comprising a protection function for determining an overvoltage on at least one of the primary side and the secondary side in accordance with an output from the output terminal of the comparator, and stopping a switching operation.

7. An electrical device comprising the switching power supply device according to any one of claims 1 to 6.

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