Misconduction control circuit, inverter, frequency converter and frequency conversion electric appliance

Abstract

The invention discloses a misconduction control circuit, an inverter, a frequency converter and a frequency conversion electric appliance. The error conduction control circuit is applied to the inverter, the inverter comprises a plurality of inverter bridges, each inverter bridge comprises an upper bridge arm switch tube and a lower bridge arm switch tube, and the error conduction control circuit comprises clamping modules which are arranged in one-to-one correspondence with the lower bridge arm switch tubes, the first end of the clamping module is connected with the source electrode of the lower bridge arm switch tube, and the second end of the clamping module is connected with the grid electrode of the lower bridge arm switch tube. According to the invention, the voltage difference between the grid electrode and the source electrode of the lower bridge arm switch tube can be prevented from exceeding the conduction threshold value of the lower bridge arm switch tube, thereby preventing the lower bridge arm switch tube from being mistakenly conducted when the lower bridge arm switch tube does not need to be conducted, and further preventing short circuit caused by simultaneous conduction of the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge. And the reliability and the stability of the inverter circuit are improved.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a misdirection control circuit, an inverter, a frequency converter and a frequency conversion electrical appliance. Background Art

[0002] With the development of electronic power technology, inverters have gradually been popularized and matured in the field of motor control. Inverters are usually full-bridge circuits composed of power switch tubes. The switching characteristics of the power switch tubes are used to convert direct current into alternating current. The power switch tubes in the inverter must be turned on alternately and orderly. If the two power switch tubes in the same bridge arm are turned on at the same time, a short circuit will occur. In order to solve this problem, a dead time is usually set in the software program for the conduction of the upper and lower power switch tubes of the same bridge arm. However, when the line between the control ground of the PWM chip and the power ground connected to the source of the lower bridge arm switch tube is too long, a surge negative voltage will be generated at the source of the lower bridge arm switch tube, causing the lower bridge arm switch tube to be mistakenly turned on. At this time, if the corresponding upper bridge arm is also turned on, a short circuit problem will occur.

[0003] Currently, no effective solution has been proposed to solve the problem that a surge negative voltage is generated at the source of the lower bridge arm switch tube in the inverter in the prior art, causing the lower bridge arm switch tube to be mis-conducted and then cause a short circuit. Summary of the invention

[0004] The embodiments of the present invention provide a mis-conduction control circuit, an inverter, a frequency converter and a frequency conversion electrical appliance to solve the problem in the prior art that a surge negative voltage is generated at the source of a lower bridge arm switch tube in an inverter, causing the lower bridge arm switch tube to be mis-conducted and thus causing a short circuit.

[0005] In order to solve the above technical problems, the present invention provides a mis-conduction control circuit, which is applied to an inverter, wherein the inverter includes a plurality of inverter bridges, wherein the inverter bridge includes an upper arm switch tube and a lower arm switch tube, and the mis-conduction control circuit includes:

[0006] The clamping module is arranged in one-to-one correspondence with the lower bridge arm switch tube, the first end of the clamping module is connected to the source of the lower bridge arm switch tube, and the second end of the clamping module is connected to the gate of the lower bridge arm switch tube.

[0007] Furthermore, the clamping module includes a clamping diode, an anode of the clamping diode is connected to the source of the lower bridge arm switch tube, and a cathode of the clamping diode is connected to the gate of the lower bridge arm switch tube.

[0008] Furthermore, the mis-conduction control circuit further includes:

[0009] The negative pressure consumption module is arranged one by one between the source of each lower bridge arm switch tube and the power ground, with its first end connected to the source of the lower bridge arm switch tube, its second end connected to the power ground, and its third end connected to the isolation ground.

[0010] Furthermore, the negative pressure consumption module comprises:

[0011] A controllable switch tube, a control end of which is connected to the power ground, an output end of which is connected to the source of the lower bridge arm switch tube, and an input end of which is connected to the isolation ground through a resistor unit;

[0012] The resistance unit is used to consume the negative voltage at the source of the lower bridge arm switch tube.

[0013] Further, the resistance unit includes at least one cement resistor;

[0014] If the number of the cement resistors is two, the cement resistors are connected in series or in parallel;

[0015] If the number of the cement resistors is three or more, the cement resistors are connected in series, in parallel, or in a mixed manner.

[0016] Furthermore, the controllable switch tube is a P-channel MOS tube or a P-type triode.

[0017] The present invention also provides an inverter, comprising a plurality of inverter bridges, wherein the inverter bridges comprise upper bridge arm switch tubes and lower bridge arm switch tubes, and also comprise the above-mentioned mis-conduction control circuit.

[0018] The present invention also provides a frequency converter, comprising the above inverter.

[0019] The present invention also provides a frequency conversion electrical appliance, comprising the above-mentioned frequency converter.

[0020] Furthermore, the variable frequency electrical appliances include at least one of the following: a variable frequency air conditioner, a variable frequency refrigerator, and a variable frequency washing machine.

[0021] By applying the technical solution of the present invention, a clamping module is set between the gate and the source of the lower bridge arm switch tube to clamp the voltage difference between the gate and the source of the lower bridge arm switch tube at a certain value, thereby preventing the voltage difference between the gate and the source of the lower bridge arm switch tube from exceeding the conduction threshold of the lower bridge arm switch tube, thereby avoiding the lower bridge arm switch tube from being mis-conducted when it should not be turned on, thereby avoiding the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge from being turned on at the same time to cause a short circuit, thereby improving the reliability and stability of the inverter circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a structural diagram of an inverter according to an embodiment of the present invention;

[0023] Figure 2 4 is a structural diagram of a mis-conduction control circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0026] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0027] It should be understood that, although the terms first, second, third, etc. may be used to describe the power switch tube in the embodiments of the present invention, these power switch tubes should not be limited to these terms. These terms are only used to distinguish different power switch tubes. For example, without departing from the scope of the embodiments of the present invention, the first power switch tube may also be referred to as the second power switch tube, and similarly, the second power switch tube may also be referred to as the first power switch tube.

[0028] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0029] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0030] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] With the development of electronic power technology, inverters have gradually been popularized and matured in the field of motor control. Inverters are usually full-bridge circuits composed of power switch tubes. The switching characteristics of the power switch tubes are used to convert direct current into alternating current. The power switch tubes in the inverter must be turned on alternately and orderly. If the two power switch tubes in the same bridge arm are turned on at the same time, a short circuit will occur. In order to solve this problem, a dead time is usually set in the software program for the conduction of the upper and lower power switch tubes of the same bridge arm. However, when the line between the control ground of the PWM chip and the power ground connected to the source of the lower bridge arm switch tube is too long, a surge negative voltage will be generated at the source of the lower bridge arm switch tube, causing the lower bridge arm switch tube to be mistakenly turned on. At this time, if the corresponding upper bridge arm is also turned on, a short circuit problem will occur.

[0033] Aiming at the problem in the prior art that a surge negative voltage is generated at the source of the lower bridge arm switch tube in the inverter, causing the lower bridge arm switch tube to be mis-conducted and then causing a short circuit, this embodiment provides a mis-conduction control circuit applied to the inverter. Figure 1 is a structural diagram of an inverter according to an embodiment of the present invention, such as Figure 1As shown, the inverter includes a plurality of inverter bridges, each of which includes an upper bridge arm switch tube and a lower bridge arm switch tube. In this embodiment, the number of inverter bridges is three. The first inverter bridge includes a first power switch tube Q1 and a second power switch tube Q2. A lead line is drawn between the first power switch tube Q1 and the second power switch tube Q2 to connect the first phase of the motor. The second inverter bridge includes a third power switch tube Q3 and a fourth power switch tube Q4. A lead line is drawn between the third power switch tube Q3 and the fourth power switch tube Q4 to connect the second phase of the motor. The third inverter bridge includes a fifth power switch tube Q5 and a sixth power switch tube Q6. A lead line is drawn between the fifth power switch tube Q5 and the sixth power switch tube Q6 to connect the third phase of the motor. The first power switch tube Q1, the third power switch tube Q3 and the fifth power switch tube Q5 are upper bridge arm switch tubes, the second power switch tube Q2, the fourth power switch tube Q4 and the sixth power switch tube Q6 are upper bridge arm switch tubes, and the PWM chip sends six control signals PWM1-PWM6 to control the on and off of the power switch tubes Q1-Q6 respectively. Figure 1 As shown, the mis-conduction control circuit includes: a clamping module 10, which is arranged one by one with the lower bridge arm switch tube, the first end of the clamping module 10 is connected to the source of the lower bridge arm switch tube, and the second end of the clamping module is connected to the gate of the lower bridge arm switch tube. The voltage difference between the gate and the source of the lower bridge arm switch tube is clamped at a certain value by the clamping module 10 to avoid mis-conduction of the lower bridge arm switch tube. It should be noted that in actual application, a clamping module 10 is arranged between the gate and the source of each lower bridge arm switch tube, and a clamping module 10 is also arranged between the source and the gate of the fourth power switch tube Q4 and the sixth power switch tube Q6.

[0034] The mis-conduction control circuit of the present embodiment clamps the voltage difference between the gate and the source of the lower bridge arm switch tube at a certain value by setting a clamping module 10 between the gate and the source of the lower bridge arm switch tube, thereby preventing the voltage difference between the gate and the source of the lower bridge arm switch tube from exceeding the conduction threshold of the lower bridge arm switch tube, thereby avoiding mis-conduction of the lower bridge arm switch tube when it should not be turned on, thereby avoiding the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge from being turned on at the same time to cause a short circuit, thereby improving the reliability and stability of the inverter circuit.

[0035] Figure 2 is a structural diagram of a mis-conduction control circuit according to an embodiment of the present invention, as shown in FIG. Figure 2 As shown, the clamping module includes a clamping diode D, an anode of the clamping diode D is connected to the source of the lower bridge arm switch tube, and a cathode of the clamping diode is connected to the gate of the lower bridge arm switch tube.

[0036] After a clamping diode is set between the source S and the gate G of the lower bridge arm switch tube, the negative voltage can be clamped by using the unidirectional conduction characteristics of the diode. However, clamping the negative voltage alone cannot completely consume the negative voltage. In order to consume the negative voltage, the above-mentioned misconduction control circuit also includes: a negative voltage consumption module 20, which is set one by one between the source of each lower bridge arm switch tube and the power ground GND2, with its first end connected to the source of the lower bridge arm switch tube, its second end connected to the power ground GND2, and its third end connected to the isolation ground GND3. Figure 2 As shown, the negative voltage consumption module 20 includes: a controllable switch tube Q, whose control end is connected to the power ground GND2, whose output end is connected to the source of the lower bridge arm switch tube, and whose input end is connected to the isolation ground GND3 through a resistor unit 201; the resistor unit 201 is used to consume the negative voltage at the source of the lower bridge arm switch tube. Figure 2 As shown, in this example, the resistance unit 201 includes two cement resistors R1 and R2 connected in series. In other embodiments of the present invention, the resistance unit 201 includes at least one cement resistor. If the number of cement resistors is two, the cement resistors are connected in series or in parallel. If the number of cement resistors is three or more, the cement resistors are connected in series, in parallel, or in a mixed connection. Mixed connection refers to a combination of series and parallel connection. For example, when the number of cement resistors is three, two of the cement resistors can be connected in series and then in parallel with the third cement resistor, or two cement resistors can be connected in parallel and then in series with the third cement resistor.

[0037] In order to ensure that the controllable switch tube is turned on when a negative voltage is generated at the source of the lower bridge arm switch tube, the controllable switch tube is a P-channel MOS tube or a P-type triode.

[0038] In summary, a normal inverter circuit is a full-bridge inverter circuit composed of 6 power devices. In the actual PCB drawing process, due to many factors such as the long loop of the power ground GND2 and the control ground GND1, a surge negative voltage may be generated at the source S of the lower bridge arm switch tube. For example, the turn-on voltage of the lower bridge arm switch tube is 5V, and this negative voltage is just ≤-5V. When the control signal of PWM2 is 0V, that is, the software program controls the second power switch tube Q2 not to turn on, the gate G of Q2 is 0V. At this time, 0V-(-5V)≥5V will cause the second power switch tube Q2 to be mis-turned on. In this case, if the first switch tube Q1 is just in the on state, the power supply Vin is directly short-circuited to the ground.

[0039] In this embodiment, a misleading conduction control circuit is added between the gate and source of the lower bridge arm, and the misleading conduction control circuit includes a clamping diode and a controllable switch tube, cement resistors R1 and R2. A clamping diode D1 is added between the source S and the gate G of the lower bridge arm switch tube, and the negative voltage is clamped by the unidirectional conduction of the diode. However, clamping the negative voltage alone cannot completely consume the negative voltage. By using the negative voltage conduction characteristic of the controllable switch Q, when the negative voltage at the source S of the lower bridge arm switch tube is less than -5V, the controllable switch Q is turned on, and then the negative voltage will form a new loop through the controllable switch Q, cement resistors R1, R2, and the isolation ground GND3 in sequence, and the negative voltage at the source S of the bridge arm switch tube is consumed by the cement resistor.

[0040] Example 2

[0041] This embodiment provides an inverter, as shown in the figure above. Figure 1 As described in, the inverter includes multiple inverter bridges and also includes the mis-conduction control circuit in the above embodiment, which is used to prevent the voltage difference between the gate and the source of the lower bridge arm switch tube from exceeding the conduction threshold of the lower bridge arm switch tube, thereby avoiding the lower bridge arm switch tube from being mis-conducted when it should not be turned on, thereby avoiding the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge from being turned on at the same time to cause a short circuit, thereby improving the reliability and stability of the inverter circuit.

[0042] Example 3

[0043] The present embodiment provides a frequency converter, including the above-mentioned inverter, which is used to prevent the voltage difference between the gate and the source of the lower bridge arm switch tube from exceeding the conduction threshold of the lower bridge arm switch tube, thereby avoiding the lower bridge arm switch tube from being mistakenly turned on when it should not be turned on, thereby avoiding the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge from being turned on at the same time and causing a short circuit, thereby improving the reliability and stability of the inverter circuit, and thereby improving the reliability and stability of the entire frequency converter.

[0044] Example 4

[0045] The present embodiment provides a variable frequency electrical appliance, including the above-mentioned inverter, which is used to prevent the voltage difference between the gate and the source of the lower bridge arm switch tube from exceeding the conduction threshold of the lower bridge arm switch tube, thereby avoiding the lower bridge arm switch tube from being mistakenly turned on when it should not be turned on, thereby avoiding the upper bridge arm switch tube and the lower bridge arm switch tube of the same inverter bridge from being turned on at the same time to cause a short circuit, thereby improving the reliability and stability of the inverter circuit, thereby improving the reliability and stability of the entire inverter, and ultimately improving the reliability and stability of the entire variable frequency electrical appliance.

[0046] In some embodiments of the present invention, the variable frequency electrical appliances include at least one of the following: a variable frequency air conditioner, a variable frequency refrigerator, and a variable frequency washing machine.

[0047] The circuit embodiments described above are merely illustrative, wherein the modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, i.e., they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mis-conduction control circuit, applied to an inverter, wherein the inverter comprises a plurality of inverter bridges, wherein the inverter bridges comprise upper arm switch tubes and lower arm switch tubes, wherein: The mis-conduction control circuit comprises: The clamping module is arranged in one-to-one correspondence with the lower bridge arm switch tube, the first end of the clamping module is connected to the source of the lower bridge arm switch tube, and the second end of the clamping module is connected to the gate of the lower bridge arm switch tube.

2. The mis-conduction control circuit according to claim 1, characterized in that: The clamping module comprises a clamping diode, an anode of the clamping diode is connected to the source of the lower bridge arm switch tube, and a cathode of the clamping diode is connected to the gate of the lower bridge arm switch tube.

3. The mis-conduction control circuit according to claim 1, characterized in that: The mis-conduction control circuit further comprises: The negative pressure consumption module is arranged one by one between the source of each lower bridge arm switch tube and the power ground, with its first end connected to the source of the lower bridge arm switch tube, its second end connected to the power ground, and its third end connected to the isolation ground.

4. The mis-conduction control circuit according to claim 3, characterized in that: The negative pressure consumption module comprises: A controllable switch tube, whose control end is connected to the power ground, whose output end is connected to the source of the lower bridge arm switch tube, and whose input end is connected to the isolation ground through a resistor unit; The resistance unit is used to consume the negative voltage at the source of the lower bridge arm switch tube.

5. The mis-conduction control circuit according to claim 4, characterized in that: The resistor unit includes at least one cement resistor; If the number of the cement resistors is two, the cement resistors are connected in series or in parallel; If the number of the cement resistors is three or more, the cement resistors are connected in series, in parallel, or in a mixed manner.

6. The mis-conduction control circuit according to claim 4, characterized in that: The controllable switch tube is a P-channel MOS tube or a P-type triode.

7. An inverter, comprising a plurality of inverter bridges, wherein the inverter bridges include upper bridge arm switch tubes and lower bridge arm switch tubes, characterized in that: It also includes a misdirection control circuit as claimed in any one of claims 1 to 6.

8. A frequency converter, characterized in that: Includes the inverter as claimed in claim 7.

9. A variable frequency electrical appliance, characterized in that: Including the frequency converter as claimed in claim 8.

10. The mis-conduction control circuit according to claim 9, characterized in that: The variable frequency electrical appliances include at least one of the following: a variable frequency air conditioner, a variable frequency refrigerator, and a variable frequency washing machine.

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