Abnormality detection circuit, switching power supply circuit and electric equipment

Abstract

The utility model discloses an anomaly detection circuit, a switching power supply circuit and electric equipment. The abnormity detection circuit comprises a current sensor which is arranged at the input end of the power switch and is used for detecting the input current of the power switch; the detection module is connected with a driving chip and the current sensor, is used for acquiring a control signal which is output by the driving chip and aims at the power switch, and is also used for generating a detection signal based on the input current of the power switch and the control signal; and the main control chip is connected with the detection module and is used for judging whether the on-off state of the power switch is abnormal or not according to the detection signal. According to the utility model, abnormal on-off states of the power switch can be found in time, elements can be replaced or overhauled in time, and the stability and reliability of the switching power supply circuit are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field, specifically, relate to an abnormal detection circuit, switching power supply circuit and electric equipment. BACKGROUND

[0002] The energy loss of traditional linear power supply is large in the conversion process, which is particularly important in today's increasingly tight energy situation. In order to reduce the overall energy consumption and operating cost, switching power supply circuit emerges as the times require, not only broadens the use environment, but also significantly improves the power conversion efficiency. With the development of technology, various types of power switches (such as MOSFET and IGBT) appear, the power conversion process is simplified, and the efficiency is improved, which makes the switching power supply circuit begin to be widely used. The main working principle of switching power supply circuit is to realize the role of voltage rise and fall by using inductance, power switch and diode and other components. Its main working principle is to control the charge and discharge of inductance and capacitance by the high-speed on and off of power switch, so as to realize voltage rise and fall. However, the current switching power supply circuit lacks a monitoring circuit for monitoring the on-off state of the power switch. If the resistance value of the driving resistor of the power switch drifts, the control end of the power switch will not accurately receive the PWM control signal output by the driving chip, and then the power switch cannot be turned on and off according to the PWM control signal. If the above abnormal situation cannot be found in time, the stability and reliability of the switching power supply circuit will be affected.

[0003] At present, there is no effective solution to the problem that the abnormal on-off state of the power switch in the prior art cannot be detected in time, which affects the stability and reliability of the switching power supply circuit. UTILITY MODEL CONTENTS

[0004] The utility model embodiment provides an abnormal detection circuit, switching power supply circuit and electric equipment to solve the problem that the abnormal on-off state of the power switch in the prior art cannot be detected in time, which affects the stability and reliability of the switching power supply circuit.

[0005] To solve the above technical problem, the utility model provides an abnormal detection circuit applied to a power switch, which comprises:

[0006] A current sensor is arranged at the input end of the power switch and is used to detect the input current of the power switch.

[0007] A detection module is connected with the driving chip and the current sensor, is used to obtain the control signal of the driving chip output for the power switch, and is also used to generate a detection signal based on the input current of the power switch and the control signal.

[0008] The main control chip is connected with the detection module and is configured to determine whether the on-off state of the power switch is abnormal according to the detection signal.

[0009] Further, the detection module comprises:

[0010] The first detection unit is connected with the current sensor at the input end and is configured to output a first detection signal based on the input current of the power switch;

[0011] The subtraction operation unit is connected with the output end of the first detection unit at the input end and is configured to generate a second detection signal based on the first detection signal and a control signal for the power switch output by the driving chip;

[0012] The window comparator is connected with the output end of the subtraction operation unit at the input end and is connected with the main control chip at the output end, and is configured to generate a third detection signal and a fourth detection signal according to the second detection signal;

[0013] The main control chip is configured to determine whether the on-off state of the power switch is abnormal according to the third detection signal and the fourth detection signal.

[0014] Further, the first detection unit comprises:

[0015] The first comparator is connected with the current sensor at the non-inverting input end, is input with a first reference voltage at the inverting input end, and is connected with the subtraction operation unit at the output end.

[0016] Further, the subtraction operation unit comprises:

[0017] The subtraction operator is connected with the output end of the first detection unit at the positive input end, is connected with the driving chip of the power switch and a reference ground at the negative input end respectively, and is connected with the input end of the window comparator at the output end.

[0018] Further, the window comparator comprises:

[0019] The second comparator is configured to input a second reference voltage ref2 at the non-inverting input end, is connected with the output end of the subtraction operator at the inverting input end, and is connected with the main control chip at the output end.

[0020] The third comparator is connected with the output end of the subtraction operator at the non-inverting input end, is configured to input a third reference voltage ref3 at the inverting input end, and is connected with the main control chip at the output end.

[0021] Further, the main control chip is configured to:

[0022] When the second comparator and the third comparator both output high-level signals, it is determined that the on-off state of the power switch is normal.

[0023] When the second comparator and the third comparator both output low level signals, or the second comparator outputs a low level signal and the third comparator outputs a high level signal, it is determined that the on-off state of the power switch is abnormal.

[0024] Further, the circuit further comprises:

[0025] An alarm device is connected to the master control chip, and the master control chip controls the alarm device to issue an alarm when the on-off state of the power switch is abnormal.

[0026] The utility model also provides a switching power supply circuit, including power switch, still include above-mentioned abnormality detection circuit.

[0027] The utility model also provides a power utilization equipment, including above-mentioned switching power supply circuit.

[0028] The utility model discloses a technical scheme, the input current of power switch is detected, and the detection signal is generated based on the input current of power switch, the input current can represent the on-off state of power switch, and then is compared with the control signal for power switch output by drive chip, and the detection signal is generated according to the input current and the control signal, specifically, if the on-off state matches the control signal, the detection signal generated by the on-off state and the control signal can represent the on-off state of power switch, and if the on-off state does not match the control signal, the detection signal generated by the on-off state and the control signal can represent the on-off state of power switch, through the scheme, the on-off state of power switch can be found in time and accurately, and the stability and reliability of switching power supply circuit are improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structure block diagram of abnormality detection circuit according to the embodiment of the utility model;

[0030] Figure 2 It is the corresponding relation diagram of current sensor current signal and voltage signal according to the embodiment of the utility model;

[0031] Figure 3 It is abnormality detection circuit according to another embodiment of the utility model;

[0032] Figure 4 It is the waveform comparison diagram of PWM control signal output by drive chip, voltage output by current sensor and first detection signal according to the embodiment of the utility model;

[0033] Figure 5 It is the structure diagram of switching power supply circuit according to the embodiment of the utility model. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model will be described in further detail below in combination with the drawings. Obviously, the described embodiments are only some of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the utility model.

[0035] The terms used in the embodiments of the utility model are merely for the purpose of describing specific embodiments, and are not intended to limit the utility model. The singular forms "a", "an" and "the" used in the embodiments of the utility model and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Multiple" generally includes at least two.

[0036] It should be understood that the term "and / or" used herein is merely a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0037] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the utility model to describe the comparators, these comparators should not be limited to these terms. These terms are only used to distinguish different comparators. For example, without departing from the scope of the embodiments of the utility model, the first comparator can also be called the second comparator, and similarly, the second comparator can also be called the first comparator.

[0038] Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (a stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detecting (a stated condition or event)" or "in response to detecting (a stated condition or event)".

[0039] It should also be noted that the terms "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the goods or devices comprising a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such goods or devices. Without more limitations, the element defined by the sentence "comprising a" does not exclude the presence of other identical elements in the goods or devices comprising the element.

[0040] The optional embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0041] Example 1

[0042] To address the problem in existing technologies that the abnormal on / off states of power switches cannot be detected in a timely manner, thus affecting the stability and reliability of switching power supply circuits, this embodiment provides an anomaly detection circuit applied to power switches. Figure 1 This is a structural block diagram of the anomaly detection circuit according to an embodiment of the present invention, such as... Figure 1 As shown, the anomaly detection circuit includes:

[0043] A current sensor 1 is installed at the input terminal of the power switch to detect the input current of the power switch. The input current of the power switch reflects its conduction state; if the power switch is on, the input current will be greater than 0, and if it is not on, the input current will be 0. In this embodiment, the current sensor can be a Rogowski coil. During detection, the Rogowski coil is wrapped around the wire at the input terminal of the power switch. By detecting the induced current in the Rogowski coil, the current flowing through the wire at the input terminal of the power switch is obtained. Then, the input current of the power switch is converted into a voltage signal and output to the detection module 2. The detection module 2 generates a detection signal based on this voltage signal. Figure 2 The diagram showing the correspondence between the current signal and voltage signal of the current sensor according to an embodiment of the present invention is as follows: Figure 2 As shown, when the current sensor in this embodiment detects a current of 0, the output voltage is 2.5V. As the detected current increases, the output voltage of 2.5V also gradually increases.

[0044] The detection module 2, connected to the driver chip and the current sensor 1, is used to acquire the control signal output by the driver chip for the power switch, and also to generate a detection signal based on the input current of the power switch and the control signal. The detection module 2 compares whether the detection signal and the control signal output by the driver chip for the power switch match. If they match, it outputs a normal detection signal to indicate that the on / off state of the power switch is normal. If they do not match, it outputs a normal detection signal to indicate that the on / off state of the power switch is abnormal.

[0045] The main control chip 3 is connected to the detection module 2 and is used to determine whether the on / off state of the power switch is abnormal based on the above detection signals.

[0046] The anomaly detection circuit in this embodiment detects the input current of the power switch and generates a detection signal based on this input current. This input current characterizes the on / off state of the power switch. This signal is then compared with the control signal output by the driver chip for the power switch. A new detection signal is generated based on the input current and the control signal. Specifically, if the on / off state matches the control signal, the generated detection signal indicates that the power switch is in a normal on / off state. If the on / off state does not match the control signal, the generated detection signal indicates that the power switch is in an abnormal on / off state. This method allows for timely and accurate detection of abnormal power switch on / off states, enabling timely replacement or repair of components and improving the stability and reliability of the switching power supply circuit.

[0047] Figure 3 According to another embodiment of the present invention, the abnormal detection circuit obtains the current flowing through the wire at the input terminal of the power switch using the current sensor described above, and then converts the input current of the power switch into a voltage signal. Therefore, in order to obtain the current flowing through the wire at the input terminal of the power switch detected by the current sensor, and thus determine the on / off state of the power switch, as shown in the figure... Figure 3 As shown, the detection module 2 includes: a first detection unit 21, whose input terminal is connected to a current sensor, for outputting a first detection signal based on the input current of the power switch. The first detection unit 21 includes: a first comparator U1, whose non-inverting input terminal is connected to the current sensor, whose inverting input terminal receives a first reference voltage Vref1, and whose output terminal is connected to the input terminal of the subtraction unit 22.

[0048] To determine whether the detection signal and the control signal output by the driver chip for the power switch match, such as... Figure 3 As shown, the detection module 2 further includes a subtraction unit 22, whose input is connected to the output of the first detection unit 21, for generating a second detection signal based on the first detection signal and the control signal for the power switch output by the driver chip. The subtraction unit 22 includes a subtraction operator U2, whose positive input is connected to the output of the first detection unit 21 via a first resistor R1, whose negative input is connected to the driver chip of the power switch via a second resistor R2, whose negative input is connected to reference ground via a third resistor R3, and whose output is connected to the input of the window comparator 23.

[0049] In order to realize the detection of the above two situations, the detection module 2 further comprises a window comparator 23, an input end of which is connected to an output end of the subtraction operation unit 22, and an output end of which is connected to the main control chip, the window comparator being used for generating a third detection signal V3 and a fourth detection signal V4 according to the second detection signal V2; the main control chip 3 judges whether the on-off state of the power switch is abnormal according to the third detection signal V3 and the fourth detection signal V4.

[0050] Further, in order to realize the detection of the above two situations, the window comparator 23 comprises a second comparator U3, a same-phase input end of which is used for inputting a second reference voltage ref2, an opposite-phase input end of which is connected to the output end of the subtraction operation unit, and an output end of which is connected to the main control chip; a third comparator U4, a same-phase input end of which is connected to the output end of the subtraction operation unit, an opposite-phase input end of which is used for inputting a third reference voltage ref3, and an output end of which is connected to the main control chip.

[0051] The principle of the abnormality detection circuit of the embodiment is as follows: the current detected by the current sensor is converted into a voltage signal by using the electrical characteristics of the current sensor, and the voltage signal is compared with the first reference voltage through the first comparator U1, if the voltage value carried by the voltage signal is greater than the first reference voltage Vref1, the first comparator U1 outputs a high level; if the voltage value carried by the voltage signal is less than the first reference voltage Vref1, the first comparator U1 outputs a low level, that is, the first comparator U1 outputs the first detection signal V1, the first detection signal V1 and the PWM wave control signal output by the driving chip of the power switch are calculated through the subtraction operation unit 22, the second detection signal V2 is output according to the calculation result, and two-bit binary data is obtained through the data processing of the window comparator, and the chip processes the data to judge whether the on-off state of the power switch is abnormal.

[0052] Figure 4 For the waveform comparison chart of the PWM control signal output by the driving chip according to the embodiment of the utility model, the voltage output by the current sensor and the first detection signal, as shown in Figure 4 When the power switch is turned on, the current starts to rise, and the current value detected by the current sensor rises from 0A, according to the above-mentioned Figure 2It can be seen that the value of the voltage signal output by the current sensor rises by 2.5V according to a certain slope, therefore, with the rise of the value of the voltage signal output by the current sensor, the voltage input at the non-inverting input terminal of the first comparator U1 is greater than 2.5V, which is higher than the first reference voltage Vref1 of 2.5V at the inverting input terminal, since the voltage input at the non-inverting input terminal of the first comparator U1 is greater than the voltage input at the inverting input terminal, the first detection signal V1 output by the first comparator U1 is 5V voltage; when the power switch is turned off, the circuit is disconnected, the input current of the power switch is 0A, the voltage value input at the non-inverting input terminal of the first comparator U1 is 2.5V, since there is a bias or reference voltage for some comparators, at this time the voltage value at the non-inverting input terminal is equal to that at the inverting input terminal, the first detection signal V1 output by the first comparator U1 is 0V voltage.

[0053] The value of the above-mentioned first reference voltage Vref1 is determined according to the selection of the current sensor, for example, the current sensor selected here, according to the sensor specification book, the current-voltage conversion relationship can be queried, when the current rises from 0A, the voltage rises from 2.5V, therefore the first reference voltage Vref1 is selected as 2.5V, the selection principle is that when the current is detected, the voltage converted by the sensor should be greater than the first reference voltage Vref1.

[0054] The first detection signal V1 output by the first comparator U1 and the PWM control signal output by the driving chip of the power switch are input into the subtraction operation unit 22 together, and the subtraction operation unit 22 performs subtraction operation on the two waveforms and outputs the second detection signal V2. The second detection signal V2 has three voltage values: +5V, -5V and 0V. When the first detection signal V1 and the PWM control signal output by the driving chip of the power switch are consistent, the voltage value of the second detection signal V2 is 0V; when the first detection signal V1 is 5V and the value of the PWM control signal is 0V, the voltage value of the second detection signal V2 is +5V, indicating that the control signal output by the driving chip of the power switch is 0V (off signal), while the power switch is on, that is, the power switch is abnormal off; when the first detection signal V1 is 0V and the value of the PWM control signal is 5V, the voltage value of the second detection signal V2 is -5V, indicating that the control signal output by the driving chip of the power switch is 5V (on signal), while the power switch is off, that is, the power switch is abnormal on. The second detection signal V2 is input into the window comparator 23. The window comparator 23 includes the second comparator U3 and the third comparator U4. When the value of the second detection signal V2 is 0V, the second comparator U3 outputs a high level and the third comparator U4 outputs a high level, indicating that the on-off state of the power switch matches the control signal output by the driving chip, that is, the on-off state of the power switch is normal; when the value of the second detection signal V2 is +5V, the second comparator U3 outputs a low level and the third comparator U4 outputs a high level, indicating that the control signal output by the driving chip of the power switch is 0V (off signal), while the power switch is on, that is, the power switch is abnormal off; when the value of the second detection signal V2 is -5V, the second comparator U3 outputs a low level and the third comparator U4 outputs a low level, indicating that the control signal output by the driving chip of the power switch is 5V (on signal), while the power switch is off, that is, the power switch is abnormal on. Therefore, the main control chip 3 determines that the on-off state of the power switch is normal when both the second comparator U3 and the third comparator U4 output high level signals; determines that the on-off state of the power switch is abnormal when both the second comparator U3 and the third comparator U4 output low level signals, or the second comparator U3 outputs a low level signal and the third comparator U4 outputs a high level signal. Specifically, when the second comparator U3 outputs a low level and the third comparator U4 outputs a high level, it is determined that the power switch is abnormal off; when the second comparator U3 outputs a low level and the third comparator U4 outputs a low level, it is determined that the power switch is abnormal on.

[0055] In practical implementation, to alert staff that the power switch's on / off state has malfunctioned, the aforementioned abnormality detection circuit also includes an alarm device D, connected to the main control chip 3 via a fourth resistor R4. When the power switch's on / off state is abnormal, the main control chip 3 controls the alarm device D to issue an alarm. The alarm device can be an LED light or a buzzer light; this embodiment uses an LED light as an example.

[0056] After receiving the third detection signal V3 output by the second comparator U3 and the third detection signal V4 output by the third comparator U4, the main control chip 3 performs the next step of processing. Specifically: when the waveforms of V3 and V4 are high, the I / O port of the main control chip outputs a low level, controlling the LED to be off, indicating that the on / off state of the power switch is normal; when V3 is low and V4 is high, the I / O port of the main control chip outputs a high level, controlling the LED to be on, indicating that the on / off state of the power switch is abnormal; when V3 is low and V4 is low, the I / O port of the main control chip outputs a high level, controlling the LED to be on, indicating that the on / off state of the power switch is abnormal.

[0057] Example 2

[0058] This embodiment provides a switching power supply circuit, including a power switch, and also includes the fault detection circuit described in the above embodiment. Figure 5 The following is a structural diagram of the switching power supply circuit according to an embodiment of the present invention: Figure 5 As shown, the switching power supply circuit is a BUCK step-down circuit, which includes an inductor L1, a capacitor C1, a diode D1, and a load R0 in addition to the power switch.

[0059] Example 3

[0060] This embodiment provides an electrical device, including the switching power supply circuit described in the above embodiment.

[0061] The circuit embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. 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 to achieve the purpose of this embodiment according to actual needs.

[0062] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application, but not limited to; although the present application is described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still be modified to the technical solutions recorded in the foregoing examples, or part of the technical features are replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An anomaly detection circuit applied to a power switch, characterized by, The circuit comprises: a current sensor arranged at an input end of the power switch and configured to detect an input current of the power switch; a detection module connected to the drive chip and the current sensor, configured to acquire a control signal for the power switch output by the drive chip, and further configured to generate a detection signal based on the input current of the power switch and the control signal; a master control chip connected to the detection module and configured to determine whether a breakover state of the power switch is abnormal according to the detection signal.

2. The circuit of claim 1, wherein, The detection module comprises: a first detection unit having an input end connected to the current sensor and configured to output a first detection signal based on the input current of the power switch; a subtraction operation unit having an input end connected to an output end of the first detection unit and configured to generate a second detection signal based on the first detection signal and the control signal for the power switch output by the drive chip; a window comparator having an input end connected to an output end of the subtraction operation unit and an output end connected to the master control chip, and configured to generate a third detection signal and a fourth detection signal according to the second detection signal; The master control chip is configured to determine whether the breakover state of the power switch is abnormal according to the third detection signal and the fourth detection signal.

3. The circuit of claim 2, wherein, The first detection unit comprises: a first comparator having a non-inverting input end connected to the current sensor and an inverting input end inputting a first reference voltage, and having an output end connected to an input end of the subtraction operation unit.

4. The circuit of claim 2, wherein, The subtraction operation unit comprises: a subtraction operator having a positive input end connected to an output end of the first detection unit, a negative input end connected to the drive chip of the power switch and a reference ground respectively, and an output end connected to an input end of the window comparator.

5. The circuit of claim 4, wherein, The window comparator comprises: a second comparator having a non-inverting input end for inputting a second reference voltage ref2, an inverting input end connected to an output end of the subtraction operator, and an output end connected to the master control chip; a third comparator having a non-inverting input end connected to an output end of the subtraction operator, an inverting input end for inputting a third reference voltage ref3, and an output end connected to the master control chip.

6. The circuit of claim 5, wherein, The master control chip is configured to: determine that the breakover state of the power switch is normal when high-level signals are output by both the second comparator and the third comparator; and determine that the breakover state of the power switch is abnormal when low-level signals are output by both the second comparator and the third comparator, or when a low-level signal is output by the second comparator and a high-level signal is output by the third comparator.

7. The circuit of claim 1, wherein, The circuit further comprises: an alarm device connected to the master control chip, and configured to be controlled by the master control chip to issue an alarm when the breakover state of the power switch is abnormal.

8. A switching power supply circuit comprising a power switch, characterized by The abnormality detection circuit of any one of claims 1 to 7.

9. An electric device, characterized by The switching power supply circuit of claim 8.

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