Driving circuit based on H bridge

Abstract

The utility model discloses a driving circuit based on an H bridge, and the circuit comprises a first driving unit which is used for driving a first switch unit U1 and a second switch unit U3 on a first branch of the H bridge; the second driving unit is used for driving a first switch unit U2 and a second switch unit U4 on a second branch of the H bridge; each of the first driving unit and the second driving unit comprises a first switching device, a first resistor and a diode. The driving circuit is provided with a diode which is connected to a driving circuit part of first and second switch units (upper and lower switch units) which are in the same phase of an H bridge, if the upper and lower switch units have short turn-on time at the same time, the diode and a triode Q1 are connected in series to lower the voltage of the second pole of the lower switch unit, and the lower switch unit is prevented from being turned on until the upper switch unit is completely turned off; when the triode Q1 is completely switched off, the lower switch unit can be normally switched on, so that the condition that the upper switch unit and the lower switch unit of the H bridge are switched on simultaneously is effectively avoided, and the driving protection of the H bridge is realized.

Description

Technical Field

[0001] The utility model belongs to the field of electronic circuits, and in particular relates to a drive circuit based on an H-bridge. Background Art

[0002] The H-bridge drive circuit is a typical DC motor control circuit. Because its circuit shape resembles the letter "H", it is named "H-bridge". By combining the on-off control of each switch in the H-bridge drive circuit, the voltage across the load or output terminal connected to it can be reversed or the current can be reversed. Based on such a function, the H-bridge drive circuit is widely used in various technical fields; the protection and control of the H-bridge are the most important and core parts. Usually, the H-bridge is composed of four switches. If both the upper and lower arms of two switches on the half-bridge are turned on simultaneously during the operation of the system, it will cause the main voltage of the control system to be directly connected to the ground, thus burning out the entire control system. Summary of the Utility Model

[0003] To solve the technical problems existing in the prior art, the utility model provides a drive circuit based on an H-bridge, which can effectively avoid the situation where the upper and lower switch units of the H-bridge are turned on simultaneously, and realize the drive protection of the H-bridge.

[0004] This drive circuit includes:

[0005] A first drive unit for driving a first switch unit U1 and a second switch unit U3 on the first branch of the H-bridge;

[0006] A second drive unit for driving a first switch unit U2 and a second switch unit U4 on the second branch of the H-bridge;

[0007] Both the first drive unit and the second drive unit include a first switching device, a first resistor, and a diode; the first pole of the first switching device serves as the first connection end of the drive circuit for connecting to the first switch unit to be driven, the second pole serves as the second connection end of the drive circuit for accessing the drive signal, and the third pole is used to connect to the circuit ground; one end of the first resistor serves as the third connection end of the drive circuit for accessing the drive signal; the other end of the first resistor serves as the fourth connection end of the drive circuit for connecting to the second switch unit to be driven; the anode of the diode is connected to one end of the first resistor serving as the third connection end of the drive circuit, and the cathode is connected to the first pole of the first switching device.

[0008] In some embodiments, this drive circuit further includes a second resistor connected in series to the first connection end.

[0009] In some embodiments, this drive circuit further includes a third resistor connected in series between the fourth connection end and the circuit ground.

[0010] In some embodiments, the driving circuit further includes a fourth resistor connected in series between the second pole and the third pole of the first switching device.

[0011] In some embodiments, the driving circuit further includes a turn-off protection circuit mainly composed of a fifth resistor and a second switching device. One end of the fifth resistor is connected to the third connection terminal, and the other end is connected to the first pole of the second switching device; the second pole of the second switching device serves as the fifth connection terminal of the driving circuit for driving signal access; the third pole of the second switching device is used to connect to the circuit ground.

[0012] In some embodiments, the sum of the resistance value of the fifth resistor and the on-resistance value of the second switching device is less than the resistance value of the first resistor.

[0013] In some embodiments, the driving circuit further includes a capacitor connected in parallel with the fifth resistor.

[0014] In some embodiments, the driving circuit further includes an MCU for generating a driving signal and an acquisition module for acquiring the H-bridge current, and the acquisition module is communicatively connected to the MCU.

[0015] In some embodiments, the driving circuit is provided by the MCU.

[0016] The present utility model further provides an H-bridge circuit, which includes a first switching unit for building an upper bridge arm, a second switching unit for building a lower bridge arm, and a driving circuit for driving the first switching unit and the second switching unit to conduct and cut off; the driving circuit is the driving circuit provided by the present utility model.

[0017] The beneficial effects of the present utility model are as follows:

[0018] In the driving circuit of the present utility model, a diode is configured to be connected to the driving circuit parts of the first and second switching units (upper and lower switching units) of the same phase of the H-bridge. If the upper and lower switching units have short simultaneous on-times, the diode and the triode Q1 are connected in series to pull down the voltage of the second pole of the lower switching unit, preventing the lower switching unit from being turned on until the upper switching unit is completely turned off and the triode Q1 is completely turned off, and then the lower switching unit can be normally turned on, effectively avoiding the situation where the upper and lower switching units of the H-bridge conduct simultaneously, and realizing the driving protection of the H-bridge.

[0019] The driving circuit of the present utility model is further configured with a turn-off protection circuit, realizing the fast turn-off protection of the lower switching unit of the H-bridge. Description of the Drawings

[0020] To more clearly illustrate the embodiments of the present application, the following will briefly introduce the drawings required or involved in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. Without creative efforts, other drawings can be obtained based on these drawings:

[0021] Figure 1-2 It is the circuit schematic diagram of the H-bridge described in the present utility model;

[0022] Figure 3 It is one of the circuit schematic diagrams after the driving circuit provided by the present utility model is connected to the H-bridge;

[0023] Figure 4 It is the second circuit schematic diagram after the driving circuit provided by the present utility model is connected to the H-bridge;

[0024] Figure 1 、 2 The direction indicated by the arrow of the arrowed line in is the current direction. Detailed implementation manners

[0025] This part describes the present utility model more comprehensively with reference to the drawings, in which illustrative embodiments of the present utility model are shown. However, the present utility model can be embodied in many different forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided so that this disclosure is thorough and complete, and fully conveys the scope of the present utility model to those skilled in the art.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs. It will be further understood that terms such as those defined in a common dictionary should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and will not be interpreted in an idealized or overly formal sense unless specifically defined herein.

[0027] Now, the exemplary embodiments will be described more comprehensively with reference to the drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present utility model will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0028] As used herein, two switching units in the same phase refer to the upper and lower two switching units located on the same branch, such as Figure 1 、 2 in which the switching units U1 and U3 are two switching units in the same phase, and the switching units U2 and U4 are two switching units in the same phase.

[0029] As used in this article, the first switching unit refers to the switching unit located in the upper half-bridge of the H-bridge, and the second switching unit refers to the switching unit located in the lower half-bridge of the H-bridge; for example Figure 1 , 2 in the switching units U1 and U2 are the first switching units, and the switching units U3 and U4 are the second switching units.

[0030] The H-bridge circuit includes four independently controlled switching units. The switching units are IGBTs or MOSFETs. The four independently controlled switching units are controlled to conduct and cut off through a driving circuit. For example Figure 1 , 2 as shown, a capacitor C1 for filtering and reducing stray capacitance is configured in the H-bridge, and an RC series resonance circuit composed of a resistor R and a capacitor C2 in series. The RC series resonance circuit functions to absorb the oscillation at both ends of the load and ensure the stable operation of the load.

[0031] The operating states of the H-bridge include Figure 1 the state 1 (current flowing from left to right through the load) as shown in Figure 2 and the state 2 (current flowing from right to left through the load) as shown in. If two switching units in the same phase are simultaneously turned on during the operation of the H-bridge, it will cause the main voltage of the H-bridge to be short-circuited to ground, and the switching units will be burned out. Therefore, it is necessary to avoid the situation where two switching units in the same phase of the H-bridge are simultaneously turned on.

[0032] In order to avoid the situation where two switching units in the same phase of the H-bridge are simultaneously turned on, the present utility model provides a driving circuit with a protection circuit. The structure of this circuit is specifically described in the following embodiments. Embodiment

[0033] The driving circuit provided in this embodiment includes:

[0034] A first driving unit for driving the first switching unit U1 and the second switching unit U3 on the first branch of the H-bridge;

[0035] A second driving unit for driving the first switching unit U2 and the second switching unit U4 on the second branch of the H-bridge;

[0036] The first driving unit includes a first switching device Q1, a first resistor R1, and a diode D1; the second driving unit includes a first switching device Q2, a first resistor R2, and a diode D2; the diodes D1 and D2 form a protection circuit.

[0037] Please refer to Figure 3, the first pole of the first switching device Q1 serves as the first connection terminal of the first driving unit and is used to connect to the first switching unit U1 to be driven. The second pole serves as the second connection terminal of the first driving unit and is used for driving signal access. The third pole is used to connect to the circuit ground; one end of the first resistor R1 serves as the third connection terminal of the first driving unit and is used for driving signal access, and the other end serves as the fourth connection terminal of the first driving unit and is used to connect to the second switching unit U3 to be driven; the anode of the diode D1 is connected to one end of the first resistor R1 serving as the third connection terminal of the first driving unit, and the cathode is connected to the first pole of the first switching device Q1.

[0038] The first pole of the first switching device Q2 serves as the first connection terminal of the second driving unit and is used to connect to the first switching unit U3 to be driven. The second pole serves as the second connection terminal of the second driving unit and is used for driving signal access. The third pole is used to connect to the circuit ground; one end of the first resistor R2 serves as the third connection terminal of the second driving unit and is used for driving signal access, and the other end serves as the fourth connection terminal of the second driving unit and is used to connect to the second switching unit U4 to be driven; the anode of the diode D2 is connected to one end of the first resistor R2 serving as the third connection terminal of the second driving unit, and the cathode is connected to the first pole of the first switching device Q2.

[0039] Here, the first switching unit U1 on the first branch of the H-bridge is a P-type MOS transistor, and the second switching unit U3 is an N-type MOS transistor; the first switching unit U2 on the second branch is a P-type MOS transistor, and the second switching unit U4 is an N-type MOS transistor. The working principle of this driving circuit will be described by taking this as an example.

[0040] According to Figure 3 the shown connection relationship, this driving circuit is connected to the four independent switching units of the H-bridge, and the driving process is as follows:

[0041] Process 1: A low-level driving signal is applied to the first connection terminal of the first driving unit, and a high-level driving signal is applied to the third connection terminal. High-level driving signals are applied to the first connection terminal and the third connection terminal of the second driving unit (or a high-level driving signal is applied to the first connection terminal of the second driving unit, and a low-level driving signal is applied to the third connection terminal); the first switching device Q1 and the diode D1 are turned off, the first switching unit U1 on the first branch is turned off, and the second switching unit U3 is turned on; the first switching device Q2 and the diode D2 are turned on, the level on the third connection terminal of the second driving unit is pulled low, the first switching unit U2 on the second branch is turned on, and the second switching unit U4 is turned off. The H-bridge circuit operates in state 1 ( Figure 1 shown).

[0042] Process 2: The first connection terminal and the third connection terminal of the first driving unit are connected to a high-level driving signal (or the first connection terminal of the first driving unit is connected to a high-level driving signal, and the third connection terminal is connected to a low-level driving signal), the first connection terminal of the second driving unit is connected to a low level, and the third connection terminal is connected to a high level; the first switching device Q1 and the diode D1 are turned on, the level on the third connection terminal of the first driving unit is pulled down, the first switching unit U1 on the first branch is turned on, and the second switching unit U3 is turned off; the first switching device Q2 and the diode D2 are turned off, the first switching unit U2 on the second branch is turned off, and the second switching unit U4 is turned on, and the H-bridge circuit operates in state 2.

[0043] By switching the control signals connected according to Process 1 and Process 2, the H-bridge can be switched between state 1 and state 2. If the switching time intervals of the first switching units U1 / U2 and the second switching units U3 / U4 are not enough, there will be a short time when the first switching units U1 / U2 and the second switching units U3 / U4 are both turned on, resulting in a direct short circuit of the first switching units U1 / U2 and the second switching units U3 / U4 and burning out the devices.

[0044] This driving circuit is configured with diodes connected between the drives of the first switching units U1 / U2 and the second switching units U3 / U4. In the conduction state of the first switching devices Q1 / Q2 and the diodes D1 / D2, the voltages at the third connection terminals of the first driving unit and the second driving unit will be pulled down, resulting in the second switching units not being turned on; until the first switching devices Q1 / Q2 are completely turned off and the diodes are turned off, when the third connection terminals of the first driving unit and the second driving unit are connected to valid signals (signals that turn on the second switching units U3 / U4), the second switching units U3 / U4 can be normally turned on. Embodiment

[0045] Based on all the technical features of the driving circuit in Embodiment 1, the driving circuit provided in this embodiment further includes a second resistor R3 and a second resistor R4. One end of the second resistor R3 is connected to the first pole of the first switching device Q1, and the other end is used as the fifth connection terminal of the first driving unit for connecting to the first switching unit to be driven; one end of the second resistor R4 is connected to the first pole of the first switching device Q2, and the other end is used as the fifth connection terminal of the second driving unit for connecting to the first switching unit to be driven.

[0046] After connecting the first switching unit to be driven to this driving circuit, the second resistors R3 and R4 are connected in series between the second pole and the third pole of the first switching unit. Embodiment

[0047] On the basis of including all the technical features of the driving circuits in Embodiment 1 and Embodiment 2, the driving circuit provided in this embodiment further includes a third resistor R5 connected in series between the fourth connection end of the first driving unit and the circuit ground, and a third resistor R6 connected in series between the fourth connection end of the second driving unit and the circuit ground.

[0048] After the second switching unit to be driven is connected to this driving circuit, the third resistors R5 and R6 are connected in series between the second pole of the second switching unit and the circuit ground.

[0049] The resistors R3 - R6 configured in this driving circuit mainly prevent driving oscillation to ensure the normal operation of the switching unit. At the same time, a bias voltage is provided for the first switching unit through the voltage division of the resistors R3 and R4, which helps to control the turning on and off of the first switching unit. Since the resistance values of the resistors R3 and R4 are different, the provided bias voltages are different, thus helping to control the turning on and off of the first switching unit. Embodiment

[0050] On the basis of including all the technical features of the driving circuits in Embodiment 1, Embodiment 2, and Embodiment 3, the driving circuit provided in this embodiment further includes a fourth resistor R7 connected in series between the second pole and the third pole of the first switching device Q1, and a fourth resistor R8 connected in series between the second pole and the third pole of the first switching device Q2.

[0051] The fourth resistors R7 and R8 are connected between the second pole and the third pole of the switching device, which can effectively limit the magnitude of the current flowing through the second pole of the switching device, prevent the switching device from being damaged due to excessive current, and at the same time play a role in stabilizing the circuit, avoiding circuit failures caused by current fluctuations. Embodiment

[0052] On the basis of including all the technical features of the driving circuits in Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4, the driving circuit provided in this embodiment further includes a turn - off protection circuit for realizing fast turn - off protection of the lower H - bridge tube (the second switching unit).

[0053] Please refer to Figure 3 , the turn - off protection circuit includes a fifth resistor R9, a fifth resistor R10, a second switching device Q3, and a second switching device Q4; one end of the fifth resistor R9 is connected to the third connection end of the first driving unit, and the other end is connected to the first pole of the second switching device Q3; the second pole of the second switching device Q3 is for driving signal access, and the third pole is connected to the circuit ground; one end of the fifth resistor R10 is connected to the third connection end of the second driving unit, and the other end is connected to the first pole of the second switching device Q4; the second pole of the second switching device Q4 is for driving signal access, and the third pole is connected to the circuit ground.

[0054] The fifth resistors R9 and R10 are current-limiting circuits, which are connected in series with the second switching devices Q3 and Q4 to form a fast discharge circuit for the second pole voltage of the lower H-bridge (second switching unit). When an effective driving signal is applied, the second switching devices Q3 and Q4 are turned on to achieve fast turn-off protection for the lower H-bridge.

[0055] To ensure fast discharge and achieve the purpose of fast turn-off protection, the sum of the resistance values of the fifth resistors R9 and R10 and the on-resistance values of the second switching devices Q3 and Q4 is much smaller than the resistance values of the first resistors R1 and R2.

[0056] This turn-off protection circuit further includes a capacitor C3 connected in parallel with the fifth resistor R9 and a capacitor C4 connected in parallel with the fifth resistor R10. Embodiment

[0057] The driving circuit provided in this embodiment, on the basis of including all the technical features of the driving circuit in Embodiment 5, further includes an MCU for generating a driving signal and an acquisition module for acquiring the H-bridge current. The acquisition module is communicatively connected to the MCU, as Figure 4 shown.

[0058] The acquisition module acquires the H-bridge current, converts it into a corresponding voltage and compares it with a threshold voltage. When the voltage corresponding to the acquired current exceeds the threshold voltage, it indicates that there is an overcurrent situation in the H-bridge circuit. The acquisition module outputs an effective signal to the input MCU, and the MCU generates a driving signal to be applied to the second power device Q3 / Q4 to turn on and off the second switching unit by the second power device Q3 / Q4, effectively solving the problem that the switching unit fails due to overcurrent in the H-bridge and achieving overcurrent protection.

[0059] The driving signal for accessing the driving circuits provided in Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4 can be generated by the MCU. The MCU has a storage function for storing a computer program, and this program is run after the MCU is powered on to generate a driving signal to be applied to this driving circuit. Alternatively, the driving signal for accessing this driving circuit is provided by an existing circuit capable of generating high and low level pulse signals.

[0060] Referring to Figure 1 、 2 , when the H-bridge is in operating state 1, the MCU outputs a signal to the connection terminal of the corresponding driving circuit to achieve the conduction of the first switching unit U1 and the second switching unit U4, realizing the normal operation of the motor in the forward direction. When the H-bridge is in operating state 2, the MCU outputs a signal to the connection terminal of the corresponding driving circuit to achieve the conduction of the first switching unit U2 and the second switching unit U3, realizing the reverse rotation of the motor.

[0061] When converting between State 1 and State 2, there is a risk of direct connection between the upper and lower transistors when the dead time between the upper and lower transistors is not safe enough. In this design, the protection circuit diode is connected to the drive circuit part of the upper and lower transistors, and during the time when the upper transistor (the first switching unit) is turned on, the drive voltage of the lower transistor (the second switching unit) is pulled down so that the lower transistor cannot be turned on, thus ensuring the safe operation of the system.

[0062] It can be understood that, in addition to the manner described in Embodiment 6, the drive signals connected to the second power devices Q3 / Q4 can also be directly provided by the MCU and generated according to the computer program stored in the MCU after power-on.

[0063] The first switching devices Q1-Q2 described in this article are configured as triodes and used as switches; the second switching devices Q3-Q4 can be configured as triodes or MOS transistors and used as switches.

[0064] The "first pole", "second pole" and "third pole" described in this article, when the switching device is configured as a triode, the first pole is the C pole, the second pole is the B pole, and the third pole is the E pole; when the switching device is configured as a MOS transistor, the first pole is the D pole, the second pole is the G pole, and the third pole is the S pole.

[0065] The present disclosure has been described by the above related embodiments. However, the above embodiments are only examples for implementing the present disclosure. It must be pointed out that the disclosed embodiments do not limit the scope of the present disclosure. On the contrary, changes and modifications made without departing from the spirit and scope of the present disclosure fall within the scope of patent protection of the present disclosure.

Claims

1. A driving circuit based on an H-bridge, characterized in that: The circuit includes: A first driving unit, used to drive a first switch unit U1 and a second switch unit U3 on a first branch of the H bridge; A second driving unit, used to drive a first switch unit U2 and a second switch unit U4 on a second branch of the H bridge; The first driving unit and the second driving unit both include a first switching device, a first resistor and a diode; the first electrode of the first switching device serves as the first connection end of the driving circuit, for connecting to the driven first switching unit, the second electrode serves as the second connection end of the driving circuit, for accessing the driving signal, and the third electrode serves as the circuit ground; one end of the first resistor serves as the third connection end of the driving circuit, for accessing the driving signal; the other end of the first resistor serves as the fourth connection end of the driving circuit, for connecting to the driven second switching unit; the anode of the diode is connected to one end of the first resistor serving as the third connection end of the driving circuit, and the cathode is connected to the first electrode of the first switching device.

2. The H-bridge based driving circuit according to claim 1, characterized in that: The device also includes a second resistor connected in series to the first connection end.

3. The H-bridge based driving circuit according to claim 1, characterized in that: A third resistor is also included which is connected in series between the fourth connection terminal and the circuit ground.

4. The H-bridge based driving circuit according to claim 1, characterized in that: It also includes a fourth resistor connected in series between the second electrode and the third electrode of the first switching device.

5. The H-bridge based driving circuit according to claim 1, characterized in that: It also includes a shutdown protection circuit mainly composed of a fifth resistor and a second switching device, one end of the fifth resistor is connected to the third connection end, and the other end is connected to the first pole of the second switching device; the second pole of the second switching device serves as the fifth connection end of the driving circuit for driving signal access; the third pole of the second switching device is used to connect to the circuit ground.

6. The H-bridge based driving circuit according to claim 5, characterized in that: The sum of the resistance of the fifth resistor and the on-resistance of the second switch device is smaller than the resistance of the first resistor.

7. The H-bridge based driving circuit according to claim 5, characterized in that: A capacitor connected in parallel with the fifth resistor is also included.

8. The H-bridge based driving circuit according to any one of claims 5 to 7, characterized in that: It also includes an MCU for generating a driving signal and a collection module for collecting H-bridge current, and the collection module is communicatively connected with the MCU.

9. The H-bridge based driving circuit according to any one of claims 1 to 4, characterized in that: The driving circuit is provided by MCU.

10. An H-bridge circuit, characterized in that: The circuit includes a first switch unit for building an upper bridge arm, a second switch unit for building a lower bridge arm, and a drive circuit for driving the first switch unit and the second switch unit to be turned on and off; the drive circuit is the drive circuit described in any one of claims 1-9.

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