Switch state detection circuit

Abstract

The utility model provides a switch state detection circuit. A secondary winding of a transformer is connected in parallel with a switch of which the switch state needs to be detected through an isolation unit; the state detection unit is connected with one end of a primary winding of the transformer through the pulse current generation circuit; the pulse current generating circuit is used for generating pulse current with the frequency higher than the preset frequency and is coupled to the two ends of the switch through the transformer and the isolation unit, so that the secondary winding of the transformer is isolated from the switch through the isolation unit while the state of the switch is detected by the state detection unit; the situation that the switch cannot disconnect the system where the switch is located due to the fact that the secondary winding of the transformer enables the switch to be short-circuited is avoided, mutual interference work is avoided through electrical connection between the transformer isolation switch and the state detection unit, even if power sources are arranged at the two ends of the switch, independent detection of the switch is still achieved, and the detection accuracy is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of power electronics, and more specifically, relates to a detection circuit for a switch state. Background Art

[0002] With the rapid development of science and technology, the power that equipment can withstand is getting higher and higher. High-power relays have also emerged and are being used in an increasingly wide range of applications. When using high-power relays, it is necessary to monitor the switching status of the relays. Then, different operations and analyses can be performed according to the different switching states of the relays to improve the safety of high-power relays.

[0003] The current method of monitoring the switching state of a relay is to measure the voltage across the relay through an isolated voltage sampling circuit and compare the voltages across the relay. If the difference between the voltages across the relay is less than a threshold, the relay is determined to be in a closed state; otherwise, the relay is determined to be in an open state.

[0004] However, if voltage sources are configured at both ends of the relay and the voltage values of the two voltage sources are similar, the existing monitoring method cannot accurately determine the switching state of the relay, and misjudgment may occur. Utility Model Content

[0005] In view of this, an object of the present invention is to provide a switch state detection circuit for realizing independent detection of the switch and improving the detection accuracy.

[0006] The present application discloses a switch state detection circuit, comprising: an isolation unit, a transformer, a pulse current generating circuit and a state detection unit;

[0007] The secondary winding of the transformer is connected in parallel to the switch whose switch state needs to be detected through the isolation unit;

[0008] The first end of the pulse current generating circuit is connected to one end of the primary winding of the transformer;

[0009] The second end of the pulse current generating circuit is connected to the other end of the primary winding of the transformer;

[0010] The third terminal of the pulse current generating circuit is connected to the input terminal of the state detection unit;

[0011] The fourth terminal of the pulse current generating circuit is connected to the ground terminal of the state detection unit;

[0012] The pulse current generating circuit is used to generate a pulse current with a frequency higher than a preset frequency and is coupled to both ends of the switch through the transformer and the isolation unit.

[0013] Optionally, the isolation unit includes: a capacitor;

[0014] One end of the capacitor is connected to one end of the secondary winding of the transformer;

[0015] The other end of the capacitor is connected to one end of the switch;

[0016] The other end of the secondary winding of the transformer is connected to the other end of the switch.

[0017] Optionally, the isolation unit includes: an isolation diode;

[0018] The anode of the isolation diode is connected to one end of the secondary winding of the transformer;

[0019] The cathode of the isolation diode is connected to the input end of the switch;

[0020] The other end of the secondary winding of the transformer is connected to the output end of the switch.

[0021] Optionally, the isolation unit includes: an H-bridge topology;

[0022] The first input end of the H-bridge topology is connected to one end of the secondary winding of the transformer;

[0023] The second input end of the H-bridge topology is connected to the other end of the secondary winding of the transformer;

[0024] The first output terminal of the H-bridge topology is connected to the input terminal of the switch;

[0025] The second output terminal of the H-bridge topology is connected to the output terminal of the switch.

[0026] Optionally, the H-bridge topology includes: a first diode, a second diode, a third diode and a fourth diode;

[0027] The anode of the first diode is connected to the cathode of the third diode, and the connection point serves as the first input terminal of the H-bridge topology;

[0028] The anode of the second diode is connected to the cathode of the fourth diode, and the connection point serves as the second input terminal of the H-bridge topology;

[0029] The cathode of the first diode and the cathode of the second diode are connected, and the connection point serves as the first output end of the H-bridge topology;

[0030] The anode of the third diode is connected to the anode of the fourth diode, and the connection point serves as the second output end of the H-bridge topology.

[0031] Optionally, the pulse current generating circuit includes: a switching tube and a DC power supply;

[0032] The control end of the switch tube receives a pulse signal;

[0033] The first end of the switch tube serves as the first end of the pulse current generating circuit;

[0034] The second end of the switch tube serves as the third end of the pulse current generating circuit;

[0035] The positive electrode of the DC power supply serves as the second end of the pulse current generating circuit;

[0036] The negative electrode of the DC power supply serves as the fourth terminal of the pulse current generating circuit.

[0037] Optionally, the state detection unit includes: a current detection unit and a current comparison and judgment unit;

[0038] The input end of the current detection unit serves as the input end of the state detection unit;

[0039] The output end of the current detection unit is connected to the input end of the current comparison and judgment unit.

[0040] Optionally, the current detection unit includes: a first resistor;

[0041] One end of the first resistor serves as an input end and an output end of the current detection unit respectively;

[0042] The other end of the first resistor serves as a grounding end of the current detection unit.

[0043] Optionally, the current detection unit includes: a current transformer, a detection diode and a second resistor;

[0044] One end of the primary winding of the current transformer serves as the input end of the current detection unit;

[0045] The other end of the primary winding of the current transformer serves as the grounding terminal of the current detection unit;

[0046] One end of the secondary winding of the current transformer is connected to the anode of the detection diode;

[0047] The cathode of the detection diode is connected to one end of the second resistor, and the connection point serves as the output end of the current detection unit;

[0048] The other end of the second resistor is connected to the other end of the secondary winding of the current transformer.

[0049] Optionally, the current comparison and judgment unit includes: a reference voltage source and a comparator;

[0050] The positive electrode of the reference voltage source is connected to the inverting input terminal of the comparator;

[0051] The positive input of the comparator serves as the input terminal of the current comparison and judgment unit;

[0052] The output end of the comparator serves as the output end of the current comparison and judgment unit.

[0053] It can be seen from the above technical solution that the utility model provides a switch state detection circuit, wherein: the secondary winding of the transformer is connected in parallel with the switch whose switch state needs to be detected through an isolation unit; the state detection unit is connected to one end of the primary winding of the transformer through a pulse current generating circuit; the pulse current generating circuit is used to generate a pulse current with a frequency higher than a preset frequency and couple it to the two ends of the switch through a transformer and an isolation unit, and then, while the state detection unit detects the state of the switch, the secondary winding of the transformer is isolated from the switch through the isolation unit to avoid the secondary winding of the transformer short-circuiting the switch, causing the switch to be unable to disconnect the system in which it is located, and, through the transformer isolating the electrical connection between the switch and the state detection unit, mutual interference is avoided. Even if a power supply is configured at both ends of the switch, independent detection of the switch is still achieved, thereby improving the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 This is a schematic diagram of a switch state detection circuit provided by an embodiment of the present utility model;

[0056] Figure 2 This is a schematic diagram of another switch state detection circuit provided by an embodiment of the present utility model;

[0057] Figure 3 This is a schematic diagram of another switch state detection circuit provided by an embodiment of the present utility model;

[0058] Figure 4 This is a schematic diagram of another switch state detection circuit provided by an embodiment of the present utility model;

[0059] Figure 5 This is a schematic diagram of another switch state detection circuit provided by an embodiment of the present utility model. DETAILED DESCRIPTION

[0060] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0061] In the present application, the term "comprise", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only include those elements, but also include other elements not clearly listed, or also include elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprising a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In addition, the terms "first", "second", "third", "fourth" etc. (if present) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein.

[0062] An embodiment of the present application discloses a switch state detection circuit, which is used to solve the problem in the prior art that when voltage sources are configured at both ends of a relay and the voltage values of the two voltage sources are similar, the existing monitoring method cannot accurately determine the switch state of the relay, resulting in misjudgment.

[0063] See also Figure 1 and Figure 2 , including: an isolation unit 10, a transformer T, a pulse current generating circuit 20 and a state detection unit 30.

[0064] The secondary winding N2 of the transformer T is connected in parallel to the switch K1 whose switching state needs to be detected through the isolation unit 10 .

[0065] The switch K1 for detecting the switch state can be a relay or a contactor; of course, it can also be other types of switches, which will not be described here one by one, and all are within the protection scope of this application.

[0066] Both ends of the secondary winding N2 of the transformer T are connected to both ends of the switch K1 through the isolation unit 10. Alternatively, one end of the secondary winding N2 of the transformer T is connected to one end of the switch K1 through the isolation unit 10, and the other end of the secondary winding N2 of the transformer T is directly connected to the other end of the switch K1.

[0067] Specifically, one end of the secondary winding N2 of the transformer T is connected to the first end of the isolation unit 10; the other end of the secondary winding N2 of the transformer T is connected to the second end of the isolation unit 10; the third end of the isolation unit 10 is connected to one end of the switch K1; and the fourth end of the isolation unit 10 is connected to the other end of the switch K1, thereby connecting the secondary winding N2 of the transformer T and the switch K1 in parallel through the isolation unit 10.

[0068] Alternatively, one end of the secondary winding N2 of the transformer T is connected to one end of the isolation unit 10; the other end of the isolation unit 10 is connected to one end of the switch K1, and the other end of the secondary winding N2 of the transformer T is directly connected to the other end of the switch K1; and then the secondary winding N2 of the transformer T and the switch K1 are connected in parallel through the isolation unit 10.

[0069] As can be seen from the above description, there are various connection relationships between the isolation unit 10 and the transformer T and the switch K1. Accordingly, the isolation unit 10 may also have various structures, such as having four terminals or two terminals that can adopt different connection methods.

[0070] The transformer T and the isolation unit 10 can be regarded as an isolation coupling circuit.

[0071] The primary winding N1 of the transformer T is connected to the pulse terminal of the pulse current generating circuit 20 .

[0072] Specifically, a first terminal of the pulse current generating circuit 20 is connected to one end of the primary winding N1 of the transformer T.

[0073] The second end of the pulse current generating circuit 20 is connected to the other end of the primary winding N1 of the transformer T.

[0074] The pulse current generating circuit 20 is used to generate a pulse current with a frequency higher than a preset frequency and is coupled to both ends of the switch K1 through the transformer T and the isolation unit 10 .

[0075] That is to say, the pulse current generating circuit 20 generates a high-frequency pulse current, and is sequentially coupled to the secondary winding N2 of the transformer T and the isolation unit 10 through the primary winding N1 of the transformer T, and finally coupled to both ends of the switch K1, so as to apply a pulse current to both ends of the switch K1. At the same time, the pulse current generating circuit 20 and the switch K1 are isolated by the transformer T, so as to avoid the influence of the switch K1 and the system in which it is located on the pulse current generating circuit 20 and the status detection unit 30.

[0076] When the switch K1 is in different states, such as closed state and open state, the pulse current generated by the pulse current generating circuit 20 will have different magnitudes. Therefore, the state detection unit 30 can determine the state of the switch K1 by detecting and comparing the pulse current.

[0077] A third terminal of the pulse current generating circuit 20 is connected to an input terminal of the state detecting unit 30 .

[0078] A fourth terminal of the pulse current generating circuit 20 is connected to the ground terminal of the state detecting unit 30 .

[0079] That is, the state detection unit 30 can detect the current value of the primary winding N1 of the transformer T through the pulse current generating circuit 20 , and further determine the state of the switch K1 connected to the secondary winding N2 of the transformer T.

[0080] Specifically, the detection process may be to collect the current value of the secondary winding N2 of the transformer T, and when the current value is greater than or equal to a threshold, determine that the switch K1 is in a closed state; when the current value is less than the threshold, determine that the switch K1 is in an off state. Of course, other detection methods may also be used.

[0081] In this embodiment, the secondary winding N2 of the transformer T is connected in parallel with the switch K1 whose switch state needs to be detected through the isolation unit 10; the state detection unit 30 is connected to one end of the primary winding N1 of the transformer T through the pulse current generating circuit 20; the pulse current generating circuit 20 is used to generate a pulse current with a frequency higher than a preset frequency and couple it to both ends of the switch K1 through the transformer T and the isolation unit 10. Therefore, while the state detection unit 30 detects the state of the switch K1, the secondary winding N2 of the transformer T is isolated from the switch K1 through the isolation unit 10, thereby preventing the secondary winding N2 of the transformer T from short-circuiting the switch K1, causing the switch K1 to be unable to disconnect from the system in which it is located. In addition, the electrical connection between the switch K1 and the state detection unit 30 is isolated by the transformer T to avoid mutual interference. Even if a power supply is configured at both ends of the switch, independent detection of the switch is still achieved, thereby improving detection accuracy.

[0082] It should be noted that the isolation unit 10 can be used to isolate the switch state detection circuit provided by the present application from the system in which the switch K1 is located, thereby preventing the switch state detection circuit provided by the present application from affecting the system in which the switch K1 is located. The system in which the switch K1 is located can operate normally, for example, the system state can be switched normally by controlling the state of the switch K1. At the same time, the provision of the isolation unit 10 does not affect the operation of the detection circuit provided by the present application. Specifically, the isolation unit 10 can be implemented in various ways, as illustrated below by examples:

[0083] (1) Figure 2 As shown, the isolation unit 10 includes a capacitor C1.

[0084] One end of the capacitor C1 is connected to one end of the secondary winding N2 of the transformer T.

[0085] The other end of the capacitor C1 is connected to one end of the switch K1.

[0086] The other end of the secondary winding N2 of the transformer T is connected to the other end of the switch K1.

[0087] Specifically, one end of the capacitor C1 is connected to the same-name end of the secondary winding N2 of the transformer T; the opposite-name end of the secondary winding N2 of the transformer T is directly connected to the contact of the switch K1.

[0088] The switch K1 includes two contacts, which are the two ends of the switch K1 described above.

[0089] That is to say, connecting the capacitor C1 in series between the secondary winding N2 of the transformer T and the contact of the switch K1 can solve the situation where the secondary winding N2 of the transformer T short-circuits the switch K1, causing the switch K1 to be unable to disconnect the system in which it is located. That is, setting the capacitor C1 can avoid the influence of the switch state detection circuit provided in the present application on the system in which the switch K1 is located. The system in which the switch K1 is located can operate normally, for example, the system state can be switched normally by controlling the state of the switch K1.

[0090] (2) Figure 3 As shown, the isolation unit 10 includes an isolation diode D1.

[0091] The anode of the isolation diode D1 is connected to one end of the secondary winding N2 of the transformer T. Specifically, the anode of the isolation diode D1 is connected to the same-name end of the secondary winding N2 of the transformer T.

[0092] The cathode of the isolation diode D1 is connected to the input terminal of the switch K1.

[0093] The other end of the secondary winding N2 of the transformer T is connected to the output end of the switch K1 . Specifically, the opposite-polarity end of the secondary winding N2 of the transformer T is connected to the output end of the switch K1 .

[0094] The function of the isolation diode D1 is similar to that of the capacitor C1, and will not be described in detail here.

[0095] (3) Figure 4 As shown, the isolation unit 10 includes: an H-bridge topology.

[0096] The first input terminal of the H-bridge topology is connected to one end of the secondary winding N2 of the transformer T.

[0097] The second input terminal of the H-bridge topology is connected to the other end of the secondary winding N2 of the transformer T.

[0098] The first output terminal of the H-bridge topology is connected to the input terminal of the switch K1.

[0099] The second output terminal of the H-bridge topology is connected to the output terminal of the switch K1.

[0100] Optionally, the H-bridge topology includes: a first diode D1 , a second diode D2 , a third diode D3 and a fourth diode D4 .

[0101] The anode of the first diode D1 is connected to the cathode of the third diode D3 , and the connection point serves as the first input terminal of the H-bridge topology.

[0102] That is to say, the anode of the first diode D1 and the cathode of the third diode D3 are both connected to one end of the secondary winding N2 of the transformer T; more specifically, the anode of the first diode D1 and the cathode of the third diode D3 are both connected to the same-named ends of the secondary winding N2 of the transformer T.

[0103] The anode of the second diode D2 is connected to the cathode of the fourth diode D4, and the connection point serves as the second input terminal of the H-bridge topology.

[0104] That is to say, the anode of the second diode D2 and the cathode of the fourth diode D4 are both connected to the other end of the secondary winding N2 of the transformer T; more specifically, the anode of the second diode D2 and the cathode of the fourth diode D4 are both connected to the opposite-name ends of the secondary winding N2 of the transformer T.

[0105] The cathode of the first diode D1 is connected to the cathode of the second diode D2, and the connection point serves as the first output end of the H-bridge topology.

[0106] That is, the cathode of the first diode D1 and the cathode of the second diode D2 are both connected to the input end of the switch K1 .

[0107] The anode of the third diode D3 is connected to the anode of the fourth diode D4 , and the connection point serves as the second output end of the H-bridge topology.

[0108] That is, the anode of the third diode D3 and the anode of the fourth diode D4 are both connected to the output end of the switch K1 .

[0109] When the same-name end of the secondary winding N2 of the transformer T is positive, the current flows through the first diode D1 → the closed switch K1 → the fourth diode D4 → and flows back to the secondary winding.

[0110] When the same-name terminal of the secondary winding N2 of the transformer T is the negative pole, the current flows through the second diode D2 → the closed switch K1 → the third diode D3 → and flows back to the secondary winding.

[0111] The H-bridge topology ensures that when high-frequency AC occurs in the secondary winding N2, the current flows through the switch K1 in the same direction.

[0112] The function of the H-bridge topology is similar to that of capacitor C1 and will not be described in detail here.

[0113] The input end of the switch K1 can be connected to a device that provides power, such as a power source, and the output end of the switch K1 can be connected to a power-consuming device, such as a load. When the switch K1 is in a closed state, the power-providing device can supply power to the power-consuming device through the switch K1.

[0114] Optional, such as Figure 2 As shown, the pulse current generating circuit 20 includes: a switch tube Q1 and a DC power supply DC.

[0115] The control end of the switch tube Q1 receives a pulse signal.

[0116] Specifically, the pulse signal may be sent by the controller, that is, when switch state detection is required, the controller sends a pulse signal to the pulse current generating circuit 20. The pulse signal may be understood as a PWM (Pulse Width Modulation) signal or a chopping signal.

[0117] The first end of the switch tube Q1 serves as the first end of the pulse current generating circuit 20 and is connected to one end of the primary winding N1 of the transformer T.

[0118] The second end of the switch tube Q1 serves as the third end of the pulse current generating circuit 20 and is connected to the input end of the state detection unit 30 .

[0119] The positive electrode of the DC power supply DC serves as the second end of the pulse current generating circuit 20 and is connected to the other end of the primary winding N1 of the transformer T.

[0120] The negative electrode of the DC power supply DC serves as the fourth terminal of the pulse current generating circuit 20 and is connected to the ground terminal of the state detection unit 30 .

[0121] That is, the DC power supply DC, the switch tube Q1, the secondary winding N2 of the transformer T, and the state detection unit 30 form a detection circuit. When the switch tube Q1 receives a pulse signal, the current of the detection circuit can be coupled to the two contacts of the switch K1. When the switch K1 is in different states, the current value of the detection circuit is different, thereby realizing the detection of the switch state.

[0122] Optionally, the state detection unit 30 includes: a current detection unit and a current comparison and judgment unit.

[0123] The input end of the current detection unit serves as the input end of the state detection unit 30 and is connected to the third end of the pulse current generating circuit 20 ; more specifically, the input end of the current detection unit is connected to the second end of the switch tube Q1 .

[0124] The output end of the current detection unit is connected to the input end of the current comparison and judgment unit.

[0125] The ground terminal of the current detection unit serves as the ground terminal of the state detection unit 30 and is connected to the fourth terminal of the pulse current generating circuit 20; more specifically, the ground terminal of the current detection unit is connected to the negative electrode of the DC power supply DC.

[0126] Specifically, the detection process can be as follows: the pulse current generating circuit 20 generates a pulse current, which is coupled to both ends of the switch K1 via the isolation coupling circuit. Simultaneously, the current comparison circuit detects and compares the magnitude of the pulse current. If the switch K1 is in the open state, the pulse current will be relatively small. If the switch K1 is in the closed state, which is equivalent to short-circuiting the isolation coupling circuit, the pulse current increases enough to cause the current comparison circuit to flip, thereby determining whether the relay is closed.

[0127] The current detection unit can have various forms. The following example illustrates the structure of the current detection unit:

[0128] (1) See Figure 2 , the current detection unit includes: a first resistor R1.

[0129] One end of the first resistor R1 serves as an input end and an output end of the current detection unit respectively.

[0130] Specifically, one end of the first resistor R1 is connected to the third end of the pulse current generating circuit 20 and the input end of the state detection unit 30 respectively; more specifically, one end of the first resistor R1 is connected to the second end of the switch tube Q1 and the input end of the state detection unit 30 respectively.

[0131] The other end of the first resistor R1 serves as the ground terminal of the current detection unit and is connected to the fourth end of the pulse current generating circuit 20. More specifically, the other end of the first resistor R1 is connected to the negative electrode of the DC power supply DC.

[0132] The first resistor R1 can be regarded as a current measuring resistor, that is, the first resistor R1 is mainly used to detect the current.

[0133] (2) See Figure 5 The current detection unit includes: a current transformer CT, a detection diode Ds and a second resistor R2.

[0134] One end of the primary winding of the current transformer CT serves as the input end of the current detection unit and is connected to the third end of the pulse current generating circuit 20; more specifically, one end of the primary winding of the current transformer CT is connected to the second end of the switch tube Q1.

[0135] The other end of the primary winding of the current transformer CT serves as the ground terminal of the current detection unit and is connected to the fourth end of the pulse current generating circuit 20; more specifically, the other end of the primary winding of the current transformer CT is connected to the negative pole of the DC power supply DC.

[0136] One end of the secondary winding of the current transformer CT is connected to the anode of the detection diode Ds.

[0137] The cathode of the detection diode Ds is connected to one end of the second resistor R2, and the connection point serves as the output end of the current detection unit and is connected to the input end of the current comparison and judgment unit.

[0138] The other end of the second resistor R2 is connected to the other end of the secondary winding of the current transformer CT.

[0139] That is, the primary winding of the current transformer CT receives the pulse current generated by the pulse current generating circuit 20 and transmits the pulse current to the current comparison and judgment unit through the secondary winding of the current transformer CT.

[0140] The resistance value of the second resistor R2 is not specifically limited here and can be determined according to actual conditions and is within the protection scope of this application.

[0141] It should be noted that the current transformer CT is also a form of transformer T, and the current flowing through it is inversely proportional to the turns ratio of the coil; generally speaking, the number of turns of the primary winding is very small, usually only one turn, so that the impedance of the primary winding is very small, which can avoid interference with the measured current (the current of the pulse current generating circuit 20). The current formed by the secondary winding is inversely proportional to the number of turns. The specific turns ratio is not specifically limited here and can be determined according to the actual situation, all of which are within the scope of protection of this application.

[0142] Optionally, the current comparison and judgment unit includes: a reference voltage source Vref and a comparator U1.

[0143] The positive electrode of the reference voltage source Vref is connected to the inverting input terminal of the comparator U1.

[0144] The negative electrode of the reference voltage source Vref can be grounded or connected to the relevant terminal of the current detection unit; for example, Figure 2 As shown, the negative electrode of the reference voltage source Vref is connected to the other end of the first resistor R1 and the negative electrode of the DC power supply DC respectively; Figure 5 As shown, the negative electrode of the reference voltage source Vref is connected to the other end of the second resistor R2 and the other end of the secondary winding of the current transformer CT respectively.

[0145] The positive input of the comparator U1 is used as the input of the current comparison and judgment unit and is connected to the output of the current detection unit; more specifically, Figure 2 As shown, the positive input terminal of the comparator U1 is connected to the connection point between the first resistor R1 of the switch tube Q1; Figure 5 As shown, the non-inverting input terminal of the comparator U1 is connected to the connection point between the detection diode Ds and the second resistor R2.

[0146] The output terminal of the comparator U1 serves as the output terminal of the current comparison and judgment unit.

[0147] That is to say, the output result of the comparator U1 can be used as the state detection result of the switch K1.

[0148] For example, when the comparator U1 outputs the first state, it is detected that the switch K1 is in the closed state. When the comparator U1 outputs the second state, it is detected that the switch K1 is in the open state.

[0149] by Figure 2 The structure shown in the figure explains the detection process of the switch state detection circuit:

[0150] Figure 2 The DC power supply DC and the switch tube Q1 constitute a pulse current generating circuit 20; the switch tube Q1 is driven by a high-frequency driving signal; the isolation unit 10 includes a capacitor C1, and the state detection unit 30 includes a first resistor R1, a comparator U1 and a reference voltage source Vref.

[0151] When the switch K1 is in the off state, the secondary winding N2 of the transformer T and the capacitor C1 do not form a loop. When the switch Q1 is in the on state, the DC power supply DC, the primary winding N1 of the transformer T, the switch Q1, and the first resistor R1 form a current loop; the current in this current loop is ON It starts to rise and its peak current is Where U is the voltage of DC power supply DC, T ON is the on-time of the switch tube Q1, L m is the excitation inductance of the primary winding N1 of the transformer T, L r is the leakage inductance of the primary winding N1 of the transformer T.

[0152] When the switch K1 is closed, the secondary winding N2 of the transformer T and the capacitor C1 form a loop; in high-frequency conditions, the capacitor C1 is equivalent to short-circuiting the secondary winding N2 of the transformer T. When the switch Q1 is closed, the DC power supply DC, the primary winding N1 of the transformer T, the switch Q1, and the first resistor R1 form a current loop; the current in this current loop is constant during the conduction time T of Q1. ON It starts to rise and its peak current is

[0153] The capacitor C1 and the secondary winding N2 of the transformer T are connected in series. The high-frequency AC signal generated by the secondary winding N2 of the transformer T can pass through the capacitor C1. If the switch K1 is closed, the capacitor C1 is equivalent to short-circuiting the secondary winding N2 of the transformer T.

[0154] In addition, in the transformer T, the primary winding N1 and the secondary winding N2 are two tightly coupled coils. If the secondary winding N2 is short-circuited, it is equivalent to the primary winding N1 being short-circuited. After the secondary winding N2 is short-circuited, the excitation inductance of the primary winding N1 will disappear; therefore, the peak current is

[0155] When the switch K1 is closed and turned on, the high-frequency signal transmitted from the primary winding N1 to the secondary winding N2 is allowed to pass through itself, and finally the capacitor C1, the secondary winding N2 and the switch K1 form a loop.

[0156] Since the excitation inductance L of the transformer T m Much larger than the leakage inductance L r , so I PK2 >I PK1 , select the appropriate resistance value of the first resistor R1 and the reference voltage Vref so that U PK1 <Vref,U PK2 >Vref; where U PK1 =R1×I PK1 , U PK2 =R1×I PK2 ; In this way, when the switch K1 is in the closed state, the output of the comparator U1 will flip, thereby confirming the switch state.

[0157] In this embodiment, the switch K1 and the detection circuit are electrically isolated and do not interfere with each other. In addition, the detection circuit includes components such as the switch tube Q1, a power supply (Vref), a resistor (R1 or R2), and a comparator U1. The circuit is simple and low-cost, and the switch state can be measured independently.

[0158] The features described in the various embodiments of this specification can be replaced or combined with each other. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0159] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0160] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A switch state detection circuit, characterized in that: include: Isolation unit, transformer, pulse current generating circuit and status detection unit; The secondary winding of the transformer is connected in parallel to the switch whose switch state needs to be detected through the isolation unit; The first end of the pulse current generating circuit is connected to one end of the primary winding of the transformer; The second end of the pulse current generating circuit is connected to the other end of the primary winding of the transformer; The third terminal of the pulse current generating circuit is connected to the input terminal of the state detection unit; The fourth terminal of the pulse current generating circuit is connected to the ground terminal of the state detection unit; The pulse current generating circuit is used to generate a pulse current with a frequency higher than a preset frequency and is coupled to both ends of the switch through the transformer and the isolation unit.

2. The switch state detection circuit according to claim 1, characterized in that: The isolation unit includes: a capacitor; One end of the capacitor is connected to one end of the secondary winding of the transformer; The other end of the capacitor is connected to one end of the switch; The other end of the secondary winding of the transformer is connected to the other end of the switch.

3. The switch state detection circuit according to claim 1, characterized in that: The isolation unit includes: an isolation diode; The anode of the isolation diode is connected to one end of the secondary winding of the transformer; The cathode of the isolation diode is connected to the input end of the switch; The other end of the secondary winding of the transformer is connected to the output end of the switch.

4. The switch state detection circuit according to claim 1, characterized in that: The isolation unit includes: an H-bridge topology; The first input end of the H-bridge topology is connected to one end of the secondary winding of the transformer; The second input end of the H-bridge topology is connected to the other end of the secondary winding of the transformer; The first output terminal of the H-bridge topology is connected to the input terminal of the switch; The second output terminal of the H-bridge topology is connected to the output terminal of the switch.

5. The switch state detection circuit according to claim 4, characterized in that: The H-bridge topology includes: a first diode, a second diode, a third diode and a fourth diode; The anode of the first diode is connected to the cathode of the third diode, and the connection point serves as the first input terminal of the H-bridge topology; The anode of the second diode is connected to the cathode of the fourth diode, and the connection point serves as the second input terminal of the H-bridge topology; The cathode of the first diode and the cathode of the second diode are connected, and the connection point serves as the first output end of the H-bridge topology; The anode of the third diode is connected to the anode of the fourth diode, and the connection point serves as the second output end of the H-bridge topology.

6. The switch state detection circuit according to claim 1, characterized in that: The pulse current generating circuit includes: a switch tube and a DC power supply; The control end of the switch tube receives a pulse signal; The first end of the switch tube serves as the first end of the pulse current generating circuit; The second end of the switch tube serves as the third end of the pulse current generating circuit; The positive electrode of the DC power supply serves as the second end of the pulse current generating circuit; The negative electrode of the DC power supply serves as the fourth terminal of the pulse current generating circuit.

7. The switch state detection circuit according to claim 6, characterized in that: The state detection unit includes: a current detection unit and a current comparison and judgment unit; The input end of the current detection unit serves as the input end of the state detection unit; The output end of the current detection unit is connected to the input end of the current comparison and judgment unit.

8. The switch state detection circuit according to claim 7, characterized in that: The current detection unit includes: a first resistor; One end of the first resistor serves as an input end and an output end of the current detection unit respectively; The other end of the first resistor serves as a grounding end of the current detection unit.

9. The switch state detection circuit according to claim 7, characterized in that: The current detection unit includes: a current transformer, a detection diode and a second resistor; One end of the primary winding of the current transformer serves as the input end of the current detection unit; The other end of the primary winding of the current transformer serves as the grounding terminal of the current detection unit; One end of the secondary winding of the current transformer is connected to the anode of the detection diode; The cathode of the detection diode is connected to one end of the second resistor, and the connection point serves as the output end of the current detection unit; The other end of the second resistor is connected to the other end of the secondary winding of the current transformer.

10. The switch state detection circuit according to claim 7, characterized in that: The current comparison and judgment unit includes: a reference voltage source and a comparator; The positive electrode of the reference voltage source is connected to the inverting input terminal of the comparator; The positive input of the comparator serves as the input terminal of the current comparison and judgment unit; The output end of the comparator serves as the output end of the current comparison and judgment unit.

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