MOS tube soft switching drive circuit and H-bridge drive circuit

Abstract

The utility model discloses an MOS tube soft switching drive circuit and an H-bridge drive circuit. The circuit is provided with a switch SW, a triode U and a capacitor C, one end of the switch SW is used as an input end of the driving circuit and is used for accessing a power supply VCC; the other end of the switch SW is connected with the base electrode of the triode U, and the collector electrode of the triode U is connected with the first pole plate and the second pole plate of the capacitor C; the first pole plate of the capacitor C is also connected with one end of the switch SW serving as the input end of the driving circuit and serves as the first output end of the driving circuit, and the second pole plate serves as the second output end of the driving circuit; the first output end and the second output end are used for being connected with the MOS tube. According to the driving circuit provided by the utility model, soft switching of the MOS tube is realized by using the charging and discharging process of the capacitor, high-frequency harmonic waves and peak voltage generated by rapid changes of current and voltage in the switching process of the MOS tube are effectively avoided, the switching loss of the MOS tube is reduced, and the service life of a switching device is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of electronic circuit, especially is involved in a MOS tube soft switch drive circuit and H bridge drive circuit. BACKGROUND

[0002] The switching speed of MOS tube is fast, and there are high-frequency harmonics and peak voltage in the switching moment, which is large in loss and generates a large amount of heat, which increases the complexity and cost of heat dissipation design, and the high temperature also shortens the service life of the switching device and reduces the reliability of the circuit system composed of MOS tube. SUMMARY

[0003] In order to solve the problems existing in the prior art, the purpose of the utility model is to provide a MOS tube soft switch drive circuit, which can avoid high-frequency harmonics and peak voltage generated due to sharp changes of current and voltage in the MOS tube switching process.

[0004] The soft switch drive circuit provided by the utility model is configured with a switch SW, a triode U and a capacitor C;

[0005] One end of the switch SW is used as the input end of the drive circuit and is used for connecting the power supply VCC; the other end of the switch SW is connected to the base of the triode U; the collector of the triode U is connected to the first and second plates of the capacitor C; the first plate of the capacitor C is also connected to one end of the switch SW as the input end of the drive circuit and is used as the first output end of the drive circuit, and the second plate is used as the second output end of the drive circuit; the first and second output ends are used for connecting the MOS tube.

[0006] Further, the circuit is also configured with a resistor R1, and the power supply VCC is connected to the base of the triode U through the resistor R1.

[0007] Further, the circuit is also configured with a resistor R2, one end of the resistor R2 is connected to one end of the switch SW and the base of the triode U, and the other end is connected to the circuit ground.

[0008] Further, the circuit is also configured with a resistor R3, one end of the resistor R3 is connected to the collector of the triode U, and the other end is connected to the first plate of the capacitor C.

[0009] Further, the circuit is also configured with a resistor R4 connected to the second output end.

[0010] The utility model also provides an H bridge drive circuit, and the circuit is configured with a MOS tube Q1, a MOS tube Q2, a MOS tube Q3, a MOS tube Q4, a switch SW1, a switch SW2, a triode U1, a triode U2, a capacitor C1 and a capacitor C2.

[0011] One end of the switch SW1 and one end of the switch SW2 are respectively used as input terminals of the driving circuit for power supply access; the other end of the switch SW1 is connected to the base of the triode U1 and the gate of the MOS tube Q4, the collector of the triode U1 is connected to the first plate of the capacitor C1 and the gate of the MOS tube Q1; the first plate of the capacitor C1 is also connected to one end of the switch SW1 as the input terminal of the driving circuit and the source of the MOS tube Q1, and the second plate is connected to the gate of the MOS tube Q1;

[0012] The other end of the switch SW2 is connected to the base of the triode U2 and the gate of the MOS tube Q3, and the collector of the triode U2 is connected to the first plate of the capacitor C2 and the gate of the MOS tube Q2; the first plate of the capacitor C2 is also connected to one end of the switch SW2 as the input terminal of the driving circuit and the source of the MOS tube Q2, and the second plate is connected to the gate of the MOS tube Q2;

[0013] The MOS tube Q1 to the MOS tube Q4 constitute an H-bridge circuit.

[0014] Further, the circuit is further provided with a resistor R1, and after the power supply is connected to the switch SW1 and the switch SW2, the resistor R1 is connected to the gate of the MOS tube Q4, the gate of the MOS tube Q3, the base of the triode U1 and the base of the triode U2.

[0015] Further, the circuit is further provided with a resistor R2, and after the power supply is connected to the switch SW1 and the switch SW2, the resistor R2 is connected to the circuit.

[0016] Further, the circuit is further provided with a resistor R3, and the collectors of the triode U1 and the triode U2 are respectively connected to the first plate of the capacitor C1 and the first plate of the capacitor C2 through the resistor R3.

[0017] Further, the circuit is further provided with a resistor R4, and the collectors of the triode U1 and the triode U2 are respectively connected to the gate of the MOS tube Q1 and the gate of the MOS tube Q2 through the resistor R4.

[0018] The driving circuit provided by the utility model realizes the soft switching of the MOS tube by the charging and discharging process of the capacitor, effectively avoids the high-frequency harmonic and peak voltage generated due to the sharp change of current and voltage in the switching process of the MOS tube, reduces the switching loss of the MOS tube, and prolongs the service life of the switching device. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application, the drawings needed to be used or referred to in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only some embodiments of the present application, and other drawings can be obtained without paying creative labor on the premise of these drawings:

[0020] Figure 1 The circuit principle diagram of the soft switch driving circuit is provided for the utility model;

[0021] Figure 2 The application circuit principle diagram of the soft switch driving circuit is provided for the utility model;

[0022] Figure 3 The circuit principle diagram of the H bridge driving circuit is provided for the utility model. DETAILED DESCRIPTION

[0023] This part describes the present application more fully with reference to the drawings, in which illustrative embodiments of the present application are shown. However, the present application also embodies in many different forms and should not be understood as limiting to the embodiments described here. On the contrary, these embodiments are provided in order to make the present disclosure sufficient and complete, and to fully convey the scope of the present application to those skilled in the art.

[0024] The terms used herein are only used for the purpose of describing specific embodiments and do not attempt to limit the present application. As used herein, the singular forms "a", "an" and "the" are intended to include plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise" and "include" when used herein specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof.

[0025] Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs. It will be further understood that terms such as those defined in a common dictionary should be interpreted in accordance with their meanings in the context of the relevant art, and should not be interpreted in accordance with the idealized or very formal meanings, unless specifically defined herein.

[0026] In order to solve the problem of overvoltage stress damage of MOS tube switch in the process of sharp change of current and voltage, the utility model provides a kind of MOS tube soft switch driving circuit, the circuit can carry out soft switch protection to MOS tube, reduce the risk of MOS tube damage.

[0027] Please refer to Figure 1The soft switch drive circuit is configured with a switch SW, a triode U and a capacitor C; one end of the switch SW is used as an input end of the drive circuit and is connected with a power supply VCC; the other end of the switch SW is connected with a base of the triode U, a collector of the triode U is connected with first and second plates of the capacitor C; the first plate of the capacitor C is also connected with one end of the switch SW as the input end of the drive circuit and is used as a first output end of the drive circuit, and the second plate is used as a second output end of the drive circuit; the first and second output ends are used for connecting MOS tubes.

[0028] The working principle of the soft switch drive circuit is as follows: Figure 2 The MOS tube Q1 is connected with the soft switch drive circuit in the connection mode shown in the figure, the power supply VCC is connected with the switch SW, and a collector bias is formed on the collector of the triode U. The switch SW is closed, the power supply VCC is connected with the base of the triode U through the switch SW to provide a base bias of the triode U, the triode U is turned on, and the current flows from the power supply to GND through the triode U. This process can charge the capacitor C, and before the charging of the capacitor C is completed, the gate drive voltage of the MOS tube Q1 is insufficient to open it; when the capacitor C is fully charged, the gate drive voltage of the MOS tube Q1 reaches the opening condition, at this time, the MOS tube Q1 is in the opening state, the power supply VCC is output through the MOS tube Q1 to provide power for the load (the source of the MOS tube Q1 is used as an output and is connected with the load). The switch SW is opened, the power supply VCC is no longer powered, at this time, the charge stored in the capacitor C can maintain a certain time of work before stopping working, so that the MOS tube Q1 is slowly closed.

[0029] The charging and discharging process of the capacitor C realizes the soft switch control of the MOS tube, the voltage across the capacitor C cannot be suddenly changed, the high-frequency resonance and the peak voltage of the MOS tube switch in an instant are effectively solved, the soft switch protection of the MOS tube is realized, and the risk of damage of the MOS tube is reduced.

[0030] The soft switch drive circuit can be applied to directly drive a single MOS tube, as shown in the figure; and can also be applied to construct an H-bridge circuit, as shown in the figure. Figure 2 Figure 3

[0031] ​​The H bridge circuit is configured with MOS Q1, MOS Q2, MOS Q3, MOS Q4, switch SW1, switch SW2, triode U1, triode U2, capacitor C1 and capacitor C2; one end of switch SW1 and one end of switch SW2 are used as the input end of the driving circuit, and are used for connecting the power supply VCC; the other end of switch SW1 is connected to the base of triode U1 and the gate of MOS Q4, and the collector of triode U1 is connected to the first plate of capacitor C1 and the gate of MOS Q1; the first plate of capacitor C1 is also connected to one end of switch SW1 as the input end of the driving circuit and the source of MOS Q1, and the second plate is connected to the gate of MOS Q1; the other end of switch SW2 is connected to the base of triode U2 and the gate of MOS Q3, and the collector of triode U2 is connected to the first plate of capacitor C2 and the gate of MOS Q2; the first plate of capacitor C2 is also connected to one end of switch SW2 as the input end of the driving circuit and the source of MOS Q2, and the second plate is connected to the gate of MOS Q2; MOS Q1-MOS Q4 constitute an H bridge circuit, which can be connected to a load.

[0032] Here, the working principle of the H bridge driving circuit is described by taking a motor as a load: when the motor rotates forward, switch SW1 is closed and switch SW2 is opened, at this time the power supply VCC supplies power, the current passes through switch SW1 to the base of triode U1 and the gate of MOS Q4, triode U1 and MOS Q4 are opened, the power supply current passes through triode U1 to the circuit ground GND, this process can charge capacitor C1, before the charging is completed, the gate drive voltage of MOS Q1 is not enough to open it, when C1 is fully charged, the gate drive voltage of MOS Q1 reaches the opening condition, at this time MOS Q1 and MOS Q4 are simultaneously in the open state, the power supply VCC passes through MOS Q1, the motor and MOS Q4, and finally reaches the circuit ground GND, realizing the forward rotation of the motor; when switch SW1 is opened, switch SW2 remains open, the power supply no longer supplies power, at this time the charge stored in capacitor C1 can work for a certain time before stopping work, so that MOS Q1 slowly closes.

[0033] When the motor is reversed, SW1 is disconnected and SW2 is connected. At this time, the power supply VCC supplies power, and the current passes through the switch SW2 to the base of the transistor U2 and the gate of the MOS tube Q3. The transistor U2 and the MOS tube Q3 are opened, and the power supply current passes through the transistor U2 to the circuit ground GND. This process can charge the capacitor C2. Before the capacitor C2 is fully charged, the gate drive voltage of the MOS tube Q2 is not enough to open it. When the capacitor C2 is fully charged, the gate drive voltage of the MOS tube Q1 reaches the opening condition. At this time, the MOS tube Q2 and the MOS tube Q3 are simultaneously in the open state, and the power supply current passes through the MOS tube Q2, the motor, and the MOS tube Q3, and finally reaches the circuit ground GND, realizing the reverse rotation of the motor. When the switch SW2 is disconnected, the switch SW1 remains disconnected, and the power supply no longer supplies power. At this time, the charge stored in the capacitor C2 can maintain a certain time of work before stopping, so that the MOS tube Q2 slowly closes.

[0034] The charging and discharging process of the capacitor C1 and the capacitor C2 can realize soft switching of the MOS tube Q1 and the MOS tube Q2, which avoids high-frequency resonance and peak voltage of the MOS switch at the moment to the greatest extent, and improves the reliability and stability of the system.

[0035] Please refer to Figures 1-3 The driving circuit is also configured with some or all of the following components:

[0036] 1) Resistor R1, connected in series between the switch SW (SW1, SW2) and the base of the transistor U (U1, U2), used to limit the base current of the transistor U, stabilize the static working point, provide bias control, and perform temperature compensation, so that the circuit is more stable and reliable. By configuring different resistance values of the resistor R1, the setting of the static working point of the transistor U can be realized, which can better meet the design requirements.

[0037] 2) Resistor R2, one end of which is connected to the end of the switch SW (SW1, SW2) connected to the base of the transistor U (U1, U2), and the other end is connected to the circuit ground. Resistor R2 is a current-limiting resistor that can be used alone to limit the base current of the transistor U (U1, U2), stabilize the static working point, provide bias control, and perform temperature compensation, so that the circuit is more stable and reliable. By configuring different resistance values of the resistor R2, the setting of the static working point of the transistor U (U1, U2) can be realized, which can better meet the design requirements. It can also form a voltage dividing circuit with resistor R1 to achieve the above-mentioned effects of making the circuit more stable and reliable and better meeting the design requirements.

[0038] 3) Resistor R3, connected in series between the collector of the transistor U (U1, U2) and the first plate of the capacitor C (C1, C2); by configuring resistors R3 with different resistance values, the charging and discharging time of the capacitor C (C1, C2) can be adjusted to meet the circuit design requirements.

[0039] 4) a resistor R4 connected in series between the collector of the transistor U (U1, U2) and the second plate of the capacitor C (C1, C2).

[0040] The soft switching drive circuit and the H-bridge drive circuit effectively solve the high-frequency harmonic and peak voltage generated by the sharp change of current and voltage in the switching process of the MOS tube, reduce the switching loss, the heat generated by the system will also be reduced accordingly (because the heat generated by the system is closely related to the switching loss, the higher the switching loss, the more heat generated by the system, the soft switching design can reduce the switching loss, accordingly, the heat generated by the system can be reduced), prolong the service life of the switching device, thereby improving the reliability and stability of the circuit system composed of the switching device.

[0041] The present disclosure has been described by the above-mentioned related embodiments, however, the above-mentioned 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, variations and modifications made without departing from the spirit and scope of the present disclosure are within the scope of the patent protection of the present disclosure.

Claims

1. A MOS tube soft switch driving circuit, characterized in that: The circuit is configured with a switch SW, a transistor U and a capacitor C; One end of the switch SW is used as the input end of the driving circuit and is connected to the power supply VCC; the other end of the switch SW is connected to the base of the transistor U; the collector of the transistor U is connected to the first plate and the second plate of the capacitor C; the first plate of the capacitor C is also connected to one end of the switch SW as the input end of the driving circuit and is used as the first output end of the driving circuit; the second plate is used as the second output end of the driving circuit; the first output end and the second output end are used to connect MOS tubes.

2. The MOSFET soft switching drive circuit of claim 1, wherein, The circuit is further configured with a resistor R1, and the power supply VCC is connected to the base of the transistor U through the resistor R1.

3. The MOSFET soft switching drive circuit of claim 2, wherein, The circuit is further configured with a resistor R2, one end of the resistor R2 is connected to one end of the switch SW and the base of the transistor U, and the other end is connected to the circuit ground.

4. The MOSFET soft switching drive circuit of claim 1, wherein, The circuit is further configured with a resistor R3, one end of the resistor R3 is connected to the collector of the transistor U, and the other end is connected to the first plate of the capacitor C.

5. The MOSFET soft switching drive circuit according to any one of claims 1 to 4, characterized in that, The circuit is further configured with a resistor R4 connected to the second output end.

6. An H-bridge drive circuit, characterized by The circuit is configured with MOS tubes Q1, Q2, Q3, Q4, switches SW1 and SW2, transistors U1 and U2, capacitors C1 and C2; One end of the switch SW1 and one end of the switch SW2 are used as the input end of the driving circuit and are connected to the power supply; the other end of the switch SW1 is connected to the base of the transistor U1 and the gate of the MOS tube Q4; the collector of the transistor U1 is connected to the first plate of the capacitor C1 and the gate of the MOS tube Q1; the first plate of the capacitor C1 is also connected to one end of the switch SW1 as the input end of the driving circuit and the source of the MOS tube Q1, and the second plate is connected to the gate of the MOS tube Q1; The other end of the switch SW2 is connected to the base of the transistor U2 and the gate of the MOS tube Q3; the collector of the transistor U2 is connected to the first plate of the capacitor C2 and the gate of the MOS tube Q2; the first plate of the capacitor C2 is also connected to one end of the switch SW2 as the input end of the driving circuit and the source of the MOS tube Q2, and the second plate is connected to the gate of the MOS tube Q2; The MOS tubes Q1-Q4 form an H-bridge circuit.

7. The H-bridge drive circuit of claim 6, wherein, The circuit is further configured with a resistor R1, and the power supply is connected to the gate of the MOS tube Q4, the gate of the MOS tube Q3, the base of the transistor U1 and the base of the transistor U2 through the resistor R1 after being connected to the switch SW1 and the switch SW2.

8. The H-bridge drive circuit of claim 6, wherein, The circuit is further configured with a resistor R2, and the power supply is connected to the circuit ground through the resistor R2 after being connected to the switch SW1 and the switch SW2.

9. The H-bridge drive circuit of any one of claims 6-8, wherein, The circuit is further configured with a resistor R3, and the collectors of the transistors U1 and U2 are connected to the first plate of the capacitor C1 and the first plate of the capacitor C2 through the resistor R3.

10. The H-bridge drive circuit of any one of claims 6-8, wherein, The circuit is also configured with a resistor R4, the collector of the transistor U1, the collector of the transistor U2, respectively via the resistor R4, the gate of the MOS transistor Q1, the gate of the MOS transistor Q2.

Images