Current detection circuit of half-bridge circuit and control method thereof

Abstract

The invention relates to the field of power electronics, in particular to a current detection circuit of a half-bridge circuit and a control method of the current detection circuit. The current detection circuit of the half-bridge circuit comprises a detection circuit, the detection circuit comprises a detection power device, the detection power device comprises a control end, a first end and a second end, the control end of the detection power device is used for controlling connection and disconnection of a power device, and the first end and the second end of the detection power device are connected when the detection power device is connected; the first end of the detection power device is configured to be the first end of the detection circuit, the second end of the detection power device is connected with the first input end of a comparator, the second input end of the comparator is configured to be the second end of the detection circuit, and a detection resistor is arranged between the first input end and the second input end of the comparator. The current detection circuit of the half-bridge circuit can detect the current in the half-bridge circuit.

Description

Technical Field

[0001] The present application relates to the field of power electronics, and in particular to a current detection circuit of a half-bridge circuit and a control method thereof. Background Art

[0002] A DC motor is a rotating electromagnetic machine driven by a DC voltage, used to achieve the conversion between electrical energy and mechanical energy. A DC motor uses DC as a power source, has a simple control circuit, and a simple and smooth speed regulation method, so it is widely used in household appliances and industrial control fields. In household appliances, DC motors are used, for example, as drive motors for tape recorders and cooling fans in computers.

[0003] In the prior art, the circuits used for motor driving mostly adopt an H-bridge structure. When the DC motor needs to rotate, it is only necessary to turn on the high-side power tube and the low-side power tube diagonally opposite to the H-bridge circuit. Different paths are formed according to the different conduction states of the power tubes on the two diagonal sides, thereby realizing forward or reverse rotation of the DC motor.

[0004] However, when using an H-bridge for driving, current may flow into the body diode of the power tube, resulting in circuit power waste and high circuit power consumption. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the purpose of the present application is to provide a current detection circuit for a half-bridge circuit and a control method thereof, which detect the current direction in the half-bridge circuit to reduce the power consumption of the circuit.

[0006] To achieve the above object, the present application provides a current detection circuit of a half-bridge circuit, wherein the bridge circuit is a half-bridge circuit configured between a first node and a second node, including a first load voltage output node, including:

[0007] A detection circuit, wherein a first end of the detection circuit is connected to the first load voltage output node, and a second end of the detection circuit is connected to any one of the first node and the second node, and is used to detect the flow direction of the current of the power tube located between the first end and the second end of the detection circuit in the half-bridge circuit, comprising:

[0008] A detection power device, the detection power device includes a control end, a first end, and a second end. The control end of the detection power device is used to control the on and off of the power device. The first end and the second end of the detection power device are connected when the detection power device is turned on. The first end of the detection power device is configured as the first end of the detection circuit. The second end of the detection power device is connected to a first input end of a comparator. The second input end of the comparator is configured as the second end of the detection circuit. A detection resistor is arranged between the first input end and the second input end of the comparator.

[0009] Furthermore, the detection circuit also includes an offset voltage adjustment unit, which is configured to invert the output of the comparator when the voltage difference between the first end and the second end of the detection resistor is close to the offset voltage; when the second end of the detection circuit is connected to the second node, the offset voltage is configured to be less than 0; when the second end of the detection circuit is connected to the first node, the offset voltage is configured to be greater than 0.

[0010] Furthermore, the offset voltage adjustment unit includes an offset resistor, two ends of the offset resistor are respectively connected to the second end of the detection power device and the first input end of the comparator, and the first input end of the comparator is also connected to an offset current source.

[0011] To achieve the above object, the present application provides a control method for a current detection circuit of a half-bridge circuit, the method being applied to the current detection circuit of the half-bridge circuit as described above, comprising:

[0012] In response to a power tube located between a first terminal and a second terminal of the detection circuit being in an off state, determining an output of the comparator;

[0013] Based on the output of the comparator, a power tube located between the first end and the second end of the detection circuit in the half-bridge circuit is controlled; when the output of the comparator is in the first state, the power tube is maintained in the off state and the detection is stopped; when the output of the comparator is in the second state, the power tube is turned on until the output of the comparator is in the first state, or until the power tube is turned off by an external control signal, and the detection is stopped.

[0014] Furthermore, the method further comprises:

[0015] When the power tube is turned off, the power tubes located in the same path as the power tube are turned off at the same time.

[0016] To achieve the above object, the present application provides a control method for a current detection circuit of a half-bridge circuit, the method being applied to the current detection circuit of the half-bridge circuit as described above, the method comprising:

[0017] In response to a power tube located between the first terminal and the second terminal of the detection circuit being in a conducting state, determining an output of the comparator;

[0018] Based on the output of the comparator, a power tube located between the first end and the second end of the detection circuit in the half-bridge circuit is controlled; when the output of the comparator is in a first state, the power tube is turned off and the detection stops; when the output of the comparator is in a second state, the on state of the power tube is maintained until the output of the comparator is in the first state, or until the power tube is turned off by an external control signal and the detection stops.

[0019] Compared with the prior art, the current detection circuit of a half-bridge circuit of the present application has the following beneficial effects:

[0020] The current detection circuit of the half-bridge circuit of the present application can stably and accurately detect the flow direction of the current at the load voltage output node in the bridge circuit and has good robustness.

[0021] The current detection circuit of the half-bridge circuit of the present application can use the detection result to more effectively control the on and off of the power tube in the bridge circuit, thereby saving the power consumption of the circuit.

[0022] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the structure of the current detection circuit of the half-bridge circuit of Example 1 of the present application;

[0025] Figure 2 This is a schematic diagram of the structure of the current detection circuit of the half-bridge circuit of Example 2 of the present application;

[0026] Figure 3 This is a structural schematic diagram of a current detection circuit of a half-bridge circuit according to Embodiment 3 of the present application;

[0027] Figure 4 This is a structural schematic diagram of a current detection circuit of a half-bridge circuit according to Embodiment 4 of the present application;

[0028] Figure 5 It is a structural diagram of a full-bridge circuit;

[0029] Figure 6 A schematic flow chart of a method for controlling a current detection circuit of a half-bridge circuit according to Embodiment 5 of the present application;

[0030] Figure 7 This is a flow chart of a method for controlling a current detection circuit of a half-bridge circuit according to Embodiment 6 of the present application. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0032] It should be understood that the various steps described in the method implementation of the present application can be performed in different orders and / or performed in parallel. In addition, the method implementation may include additional steps and / or omit the steps shown. The scope of the present application is not limited in this respect.

[0033] The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0034] It should be noted that the modifications of "one" and "plurality" mentioned in this application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more". "Plurality" should be understood as two or more.

[0035] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0036] Example 1

[0037] An embodiment of the present application provides a current detection circuit for a half-bridge circuit to detect the current in the half-bridge circuit.

[0038] Figure 1 Schematic diagram of the structure of the current detection circuit of the half-bridge circuit of Example 1 of the present application, such as Figure 1 As shown, the current detection circuit of the half-bridge circuit of the present application includes:

[0039] The half-bridge circuit includes: a first power tube M1, a drain connected to a first node VM, a source connected to a drain of a second power tube M2, a source of the second power tube M2 connected to a second node VSS, and a source of the first power tube M1 being a first load voltage output node V SW ;

[0040] A detection circuit, a first terminal of the detection circuit and a first load voltage output node V SW The second end of the detection circuit is connected to the second node VSS, and is used to detect the flow direction of the current of the power tube located between the first end and the second end of the detection circuit in the half-bridge circuit, specifically including:

[0041] A detection power device, which generally includes a control end, a first end, and a second end. The control end of the detection power device is used to control the on and off of the power device. The first end and the second end of the detection power device are connected when the detection power device is turned on. The first end of the detection power device is configured as the first end of the detection circuit. The second end of the detection power device is connected to the first input end of a comparator Co1. The second input end of the comparator Co1 is configured as the second end of the detection circuit. The first input end and the second input end of the comparator are respectively connected to the first end and the second end of the detection resistor R1.

[0042] In this embodiment, the detection power device is a detection power tube M3 , the detection power tube M3 has a drain as its first end, a source as its second end, and a gate as its control end.

[0043] In some other implementations, the detection power device may also be an active device such as MOS, BJT, IGBT, etc.

[0044] In this embodiment, the gate of the detection power tube M3 is connected to the gate of the second power tube M3, and the drain of the detection power tube M3 is connected to the first load voltage output node V SW The source of the detection power tube M3 is connected to the first input terminal (positive input terminal) of a comparator Co1, the second input terminal (negative input terminal) of the comparator Co1 is connected to the second node VSS, and the first input terminal and the second input terminal of the comparator Co1 are respectively connected to the first end and the second end of the detection resistor R1.

[0045] It is understandable that in some other implementations, the first power tube M1 and the second power tube M2 in the bridge circuit may also be active devices such as MOS, BJT, IGBT, etc.

[0046] It should be noted that the resistance of the detection resistor R1 is much larger than the on-resistance of the detection power tube M3.

[0047] The working process of detecting whether the body diode of the second power tube M2 is turned on in the first embodiment of the present application is as follows: when performing the detection, the first power tubes M1 and M2 are both controlled to be in the off state, and when there is a current flowing from the first load voltage output node V SWWhen the current flows out, it means that the body diodes of the detection power tube M3 and the second power tube M2 are both turned on, and the current flows out through the body diode of the second power tube M2. Since the resistance of the detection resistor R1 is much larger than the conduction impedance of the detection power tube M3, the voltage V S Will be close to -V dio (V dio The voltage of the positive input terminal of the comparator Co1 is -600mV, which is less than the voltage of the negative input terminal 0V. The comparator outputs a low level 0, which means that the current flows through the body diode of the second power tube M2.

[0048] In this embodiment, the first end and the second end of the detection circuit are configured at the drain-source ends of the second power transistor M2, and the first load voltage output node V is detected. SW The current flow direction is detected to detect whether the body diode of the second power tube M2 is turned on.

[0049] It is understandable that the first end and the second end of the detection circuit may also be configured at the drain and source ends of the first power tube M1 in the half-bridge circuit to detect whether the body diode of the first power tube is turned on.

[0050] It is understood that the control circuit can also be used in a full bridge circuit (H bridge circuit), see Figure 5 , Figure 5 is a schematic diagram of the structure of the full-bridge circuit. The detection circuit can output the voltage at the first load voltage node V SW1 or the second load voltage output node V SW2 node is configured to detect the first load voltage output node V SW1 or the second load voltage output node V SW2 The current at the node can then determine the conduction state of the body diode of each power tube in the circuit for subsequent control.

[0051] It can be understood that when applied to a full-bridge circuit, when it is detected that the body diode of a power tube is turned on, the body diode of the power tube located in the same path (diagonal) is also turned on. For example, when the current is detected to be the first load voltage output node V SW1 The outgoing current, that is, the body diode of the second power tube M2 is turned on, and at this time, the body diode of the third power tube M3 at the opposite corner is also turned on.

[0052] Example 2

[0053] An embodiment of the present application provides a current detection circuit for a half-bridge circuit to detect the current in the half-bridge circuit.

[0054] See also Figure 2 The difference between implementation 2 of the present application and implementation 1 is that:

[0055] The comparator used in Example 2 of the present application has an offset voltage V os The comparator Co1 of this structure design can be used when the voltage difference between the two input terminals of the comparator Co1 is close to the offset voltage V os The output is reversed when the current is zero-crossing, that is, the current change signal can be given in advance to control the power tube in time.

[0056] It is understandable that the comparator can be provided with an offset voltage by making the input tube pair of the comparator Co1 mismatched.

[0057] In this embodiment, the offset voltage V os is configured to -10mV so that when there is current flowing from the first load voltage output node V SW Flows in, and the second power tube M2 is in the off state, the first end of the detection resistor R1 (V s When the voltage of the first node is equal to the voltage of the second node VSS, the comparator Co1 can output 1, and when the second power tube M2 is in the on state, a current change signal is given in advance at the current zero crossing point, so as to facilitate the subsequent timely control of the power tube and improve stability.

[0058] Example 3

[0059] An embodiment of the present application provides a current detection circuit for a half-bridge circuit to detect whether a body diode of a power tube in the bridge circuit is turned on.

[0060] See also Figure 3 The difference between implementation 3 of the present application and implementation 1 is that:

[0061] An offset voltage adjustment unit 100 is provided between the source of the detection power tube M3 and the first input terminal of the comparator Co1, for providing an offset voltage V os , including an offset resistor R2, the two ends of which are respectively connected to the source of the detection power tube M3 and the first input end of the comparator Co1, and the first input end of the comparator Co1 is also connected to an offset current source I B .

[0062] In the third embodiment of the present application, the offset resistor R2 and the offset current source I B The offset voltage adjustment unit 100 is formed to provide an offset voltage V for the comparator. os so that when there is current from the first load voltage output node V SW The second power tube M2 is in the off state, and the first end of the detection resistor R1 (V sWhen the voltage of the first node is equal to the voltage of the second node VSS, the comparator Co1 can output 1, and when the second power tube M2 is in the on state, a current change signal is given in advance at the current zero crossing point, so as to facilitate the subsequent timely control of the power tube and improve stability.

[0063] Example 4

[0064] An embodiment of the present application provides a current detection circuit for a half-bridge circuit to detect whether a body diode of a power tube in the bridge circuit is turned on.

[0065] See also Figure 4 The difference between implementation 4 of the present application and implementation 3 is that:

[0066] In the embodiment of the present application, the second end of the detection circuit is connected to the first node VM, that is, used to detect the current flow direction of the first power tube M1.

[0067] In this embodiment, the source of the detection power tube M3 is connected to the first load voltage output node V SW The drain of the detection power tube M3 is connected to the first end of the detection resistor R1 as the second end, the second end of the detection resistor R1 is connected to the second input end (positive input end) of the comparator Co1, the drain of the detection power tube M3 is connected to the first input end (negative input end) of the comparator Co1 through the offset resistor R2, and the offset current source I B Configured at the first input terminal (negative input terminal) of the comparator Co1.

[0068] In this embodiment, the offset resistor R2 and the offset current source I B Provided adaptation voltage V os Greater than 0, when the first end of the sense resistor (V s The voltage difference between the node) and the second terminal (VM node) is equal to V os When the current is zero-crossing, a current change signal is given in advance to facilitate the subsequent timely control of the power tube and improve stability.

[0069] Example 5

[0070] An embodiment of the present application provides a control method for a current detection circuit of a half-bridge circuit, which is applied to the current detection circuit of the above-mentioned half-bridge circuit. Figure 1 The control method of this embodiment is described by taking the current detection circuit of the half-bridge circuit shown in FIG. Figure 6 , control methods include:

[0071] S101: in response to a power tube located between a first terminal and a second terminal of a detection circuit being in an off state, determining an output of a comparator;

[0072] In this implementation, the detection circuit determines the output of the comparator when the second power tube M2 is in the off state.

[0073] S102: Based on the output of the comparator, control a power tube located between a first end and a second end of the detection circuit in the half-bridge circuit;

[0074] In this embodiment, when the output of the comparator is 1, the second power tube M2 is maintained in the off state and the detection ends; when the output of the comparator is 0, the second power tube M2 is turned on; after the second power tube M2 is turned on, when the output of the comparator becomes 1, the second power tube M2 is turned off and the detection ends; after the second power tube M2 is turned on, the second power tube is turned off by an external control signal and the detection ends.

[0075] It can be understood that when the output of the comparator is 0, the body diode of the second power tube M2 is considered to be in a conducting state, so the second power tube M2 is turned on to reduce power consumption; when the output of the comparator of the detection circuit is 1, the body diode of the second power tube M2 is considered to be in a non-conducting state.

[0076] It is understandable that when applied to a full-bridge circuit, when it is detected that the body diode of a power tube is turned on, the body diode of the diagonal power tube in the same path will also be turned on, so when a power tube is turned on / off, the diagonal power tube will be turned on / off synchronously. For example, see Figure 4 That is, when it is detected that the body diode of the second power tube M2 is turned on and the second power tube M2 is to be turned on, the third power tube M3 is turned on synchronously.

[0077] Example 6

[0078] An embodiment of the present application provides a control method for a current detection circuit of a half-bridge circuit, which is applied to the current detection circuit of the above-mentioned half-bridge circuit. Figure 1 The control method of this embodiment is described by taking the current detection circuit of the half-bridge circuit shown in FIG. Figure 7 , control methods include:

[0079] S201: In response to a power tube located between a first terminal and a second terminal of a detection circuit being in a conducting state, determining an output of a comparator;

[0080] In this embodiment, the detection circuit determines the output of the comparator when the second power tube M2 is in the on state.

[0081] S202: Based on the output of the comparator, control a power tube located between a first end and a second end of the detection circuit in the half-bridge circuit;

[0082] In this embodiment, when the output of the comparator is 1, the second power tube M2 is turned off and the detection ends; when the output of the comparator is 0, the second power tube M2 is kept turned on until the output of the comparator becomes 1, and the second power tube M2 is turned off; when the output of the comparator is 0, the second power tube M2 is kept turned on, and when the second power tube M2 is turned off by an external control signal, the detection also ends.

[0083] It is understandable that when the output of the comparator becomes 1, the current flowing through the second power tube M2 approaches 0. In order to prevent the current from continuing to increase after the current direction is switched and affecting the circuit, the second power tube M2 needs to be turned off.

[0084] It is understandable that when applied to a full-bridge circuit, when it is detected that the body diode of a power tube is turned on, the body diode of the diagonal power tube in the same path will also be turned on, so when a power tube is turned on / off, the diagonal power tube will be turned on / off synchronously. For example, see Figure 4 That is, when it is detected that the body diode of the second power tube M2 is turned on and the second power tube M2 is to be turned on, the third power tube M3 is turned on synchronously.

[0085] The above description is only a partial embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

[0086] In addition, although each operation is described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the application. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0087] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

Claims

1. A current detection circuit for a half-bridge circuit, characterized in that: The half-bridge circuit is configured between a first node and a second node, includes a first load voltage output node, and further includes: A detection circuit, wherein the first end of the detection circuit is connected to the first load voltage output node, and the second end of the detection circuit is connected to any one of the first node and the second node, and is used to detect the flow direction of the current of the power tube located between the first end and the second end of the detection circuit in the half-bridge circuit, including: a detection power device, the detection power device includes a control end, a first end and a second end, the control end of the detection power device is used to control the conduction and shutdown of the power device, the first end and the second end of the detection power device are connected when the detection power device is turned on, the first end of the detection power device is configured as the first end of the detection circuit, the second end of the detection power device is connected to the first input end of a comparator, the second input end of the comparator is configured as the second end of the detection circuit, and the first input end and the second input end of the comparator are respectively connected to the first end and the second end of the detection resistor.

2. The current detection circuit of the half-bridge circuit according to claim 1, characterized in that: The detection circuit also includes an offset voltage adjustment unit, which is configured to invert the output of the comparator when the voltage difference between the first end and the second end of the detection resistor is close to the offset voltage; when the second end of the detection circuit is connected to the second node, the offset voltage is configured to be less than 0; when the second end of the detection circuit is connected to the first node, the offset voltage is configured to be greater than 0.

3. The current detection circuit of the half-bridge circuit according to claim 2, characterized in that: The offset voltage adjustment unit comprises an offset resistor, two ends of the offset resistor are respectively connected to the second end of the power device and the first input end of the comparator, and the first input end of the comparator is also connected to an offset current source.

4. A method for controlling a current detection circuit of a half-bridge circuit, characterized in that: A current detection circuit applied to a half-bridge circuit according to any one of claims 1 to 3, the method comprising: In response to a power tube located between a first terminal and a second terminal of the detection circuit being in an off state, determining an output of the comparator; Based on the output of the comparator, a power tube located between the first end and the second end of the detection circuit in the half-bridge circuit is controlled; when the output of the comparator is in the first state, the power tube is maintained in the off state and the detection is stopped; when the output of the comparator is in the second state, the power tube is turned on until the output of the comparator is in the first state, or until the power tube is turned off by an external control signal, and the detection is stopped.

5. The control method of the current detection circuit of the half-bridge circuit according to claim 4 is characterized in that: The method further comprises: When the power tube is turned off, the power tubes located in the same path as the power tube are turned off at the same time.

6. A method for controlling a current detection circuit of a half-bridge circuit, characterized in that: A current detection circuit applied to a half-bridge circuit according to any one of claims 1 to 3, the method comprising: In response to a power tube located between the first terminal and the second terminal of the detection circuit being in a conducting state, determining an output of the comparator; Based on the output of the comparator, a power tube located between the first end and the second end of the detection circuit in the half-bridge circuit is controlled; when the output of the comparator is in a first state, the power tube is turned off and the detection stops; when the output of the comparator is in a second state, the on state of the power tube is maintained until the output of the comparator is in the first state, or until the power tube is turned off by an external control signal and the detection stops.

7. The control method of the current detection circuit of the half-bridge circuit according to claim 6, characterized in that: The method further comprises: When the power tube is turned off, the power tubes located in the same path as the power tube are turned off at the same time.

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