Three-phase full-bridge circuit with overcurrent protection function and three-phase motor control system

Abstract

The embodiment of the utility model provides a three-phase full-bridge circuit with an overcurrent protection function, comprising a three-phase full-bridge sub-circuit comprising three half-bridge branches connected in parallel, each half-bridge branch at least comprising two power transistors connected in series; the overcurrent detection sub-circuit is arranged between the output of each half-bridge branch and the three drive control sub-circuits, and outputs a drive signal based on whether the detected current is greater than a reference current or not; and the three driving control sub-circuits are respectively arranged between the over-current detection sub-circuit and each half-bridge branch and are used for controlling the opening and closing of each half-bridge branch based on the received driving signal. Through the combination of the monitoring circuit and the driving circuit, whether the three-phase full bridge is over-current in practical application is monitored in real time, the problem of over-current failure of the power transistor is avoided, and the power transistor is protected in time.

Description

Technical Field

[0001] The utility model relates to the technical field of motor drive, in particular to a three-phase full-bridge circuit and a three-phase motor control system with an overcurrent protection function. Background Art

[0002] In the application of the three-phase full-bridge circuit in the existing motor, the probability of overcurrent failure of the power transistor (for example, metal-semiconductor oxide field effect transistor, MOSFET) is relatively high. The existing solution is that an analog comparator gives a signal to the digital control unit, and the digital control unit rectifies according to the current limiting requirement. After rectification, the output signal of the digital control unit quantifies the motor speed and load size to achieve current limiting. However, the existing technology uses a digital control unit. Compared with a simple analog control system, the design and implementation of the digital control unit require more complex hardware and software, with a higher cost, and the digital power supply is more sensitive to current noise. Poor power supply quality may affect the control accuracy and stability. Therefore, a simpler and more effective power transistor protection circuit is needed. Summary of the Utility Model

[0003] Aiming at the deficiencies in the prior art, the utility model provides a three-phase full-bridge circuit and a three-phase motor control system with an overcurrent protection function, which solves the problem of the lack of a simple and effective power transistor protection circuit in the prior art.

[0004] In a first aspect, according to an embodiment of the utility model, a three-phase full-bridge circuit with an overcurrent protection function is provided, including: a three-phase full-bridge sub-circuit, including three half-bridge branches connected in parallel, and each half-bridge branch includes at least two power transistors connected in series; an overcurrent detection sub-circuit, arranged between the output of each half-bridge branch and three drive control sub-circuits, and outputting a drive signal based on whether the detected current is greater than a reference current; three drive control sub-circuits, respectively arranged between the overcurrent detection sub-circuit and each half-bridge branch, and controlling the opening and closing of each half-bridge branch based on the received drive signal.

[0005] According to an embodiment of the utility model, the first pole of one power transistor in each half-bridge branch is connected to the first power supply voltage, its second and third poles are respectively connected to different pins of the corresponding drive control sub-circuit, and the first, second, and third poles of the other power transistor in each half-bridge branch are respectively connected to different pins of the corresponding drive control sub-circuit, wherein the third pole of the one power transistor is connected to the first pole of the other power transistor.

[0006] According to an embodiment of the present invention, the overcurrent detection sub - circuit includes a sampling resistor, a current comparator, and a micro - control unit. Among them, the sampling resistor is set between the output of each half - bridge branch and the ground. The current comparator samples the current passing through the sampling resistor, and the micro - control unit generates a driving signal for the corresponding drive control sub - circuit based on the output of the current comparator.

[0007] According to an embodiment of the present invention, when the detected current is greater than the reference current, the driving signal is at a low level.

[0008] According to an embodiment of the present invention, the drive control sub - circuit includes a drive chip, and the input of some pins of the drive chip is provided by the output of the overcurrent detection sub - circuit and the second power supply voltage.

[0009] According to an embodiment of the present invention, the HO pin of the drive chip is connected to the second pole of one power transistor, and the LO pin of the drive chip is connected to the second pole of the other power transistor.

[0010] According to an embodiment of the present invention, a first resistor and a second resistor are further included between the HO pin and the LO pin and the corresponding second poles.

[0011] According to an embodiment of the present invention, the drive control sub - circuit further includes a first capacitor, a first diode, and a second capacitor, which are used to provide an input level to some pins of the drive chip based on the first power supply voltage.

[0012] According to an embodiment of the present invention, the power transistor is a MOSFET or an IGBT. When using an IGBT, the IGBT is connected in parallel with the FRD.

[0013] In a second aspect, according to another embodiment of the present invention, a three - phase motor control system is provided, including a three - phase full - bridge circuit with an over - current protection function as described in the first aspect.

[0014] The technical principle of the present invention is: by adding current detection and comparing with a reference voltage, it can monitor in real - time whether there is an over - current problem, and the driving signal is generated based on the detection result.

[0015] Compared with the prior art, the present invention has the following beneficial effects: by combining the monitoring circuit and the driving circuit, it can monitor in real - time whether the three - phase full - bridge is over - current in actual applications, so as to avoid the problem of over - current failure of the power transistor and protect the power transistor in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a circuit diagram of the three - phase full - bridge circuit according to the embodiment of the present invention. Detailed implementation mode

[0017] The technical solutions in the present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] As described in the background art, there is a problem of lacking a simple and effective power transistor protection circuit in the prior art. To solve the above problems, as Figure 1 shown, an embodiment of the present utility model provides a three-phase full-bridge circuit 100 with an overcurrent protection function, including: a three-phase full-bridge sub-circuit 110, including three half-bridge branches connected in parallel, and each half-bridge branch includes at least two power transistors connected in series (shown as MOSFETs, but can be other power transistors); an overcurrent detection sub-circuit 120, arranged between the output of each half-bridge branch and three drive control sub-circuits, and outputting a drive signal based on whether the detected current is greater than a reference current; three drive control sub-circuits 130, respectively arranged between the overcurrent detection sub-circuit and each half-bridge branch, and controlling the turn-on and turn-off of each half-bridge branch based on the received drive signal. By adding current detection and comparing with a reference voltage, it is possible to monitor in real time whether there is an overcurrent problem, and the drive signal is generated based on the detection result to control the turn-on and turn-off of the three-phase full-bridge circuit. By combining the monitoring circuit and the drive circuit, it is possible to monitor in real time whether the three-phase full-bridge is overcurrent in actual applications, avoiding the problem of power transistor overcurrent failure and protecting the power transistor in a timely manner.

[0019] Referring again to Figure 1 , according to an embodiment of the present utility model, the first pole (drain) of one power transistor (MOSFET) (Q1, Q3, and Q5) in each half-bridge branch is connected to the first power supply voltage VCC2, and its second pole (gate) and third pole (source) are both connected to different pins of the corresponding drive control sub-circuit 130. Moreover, the second pole (gate), third pole (source), and first pole (drain) of the other power transistor (MOSFET) (Q2, Q4, and Q6) in each half-bridge branch are all connected to different pins of the corresponding drive control sub-circuit 130, wherein the third pole (source) of the one power transistor (MOSFET) is connected to the first pole (drain) of the other power transistor (MOSFET). In addition, the third poles (sources) of Q1, Q3, and Q5 are also respectively connected to inductor L1 and fourth resistor R4, inductor L2 and fourth resistor R5, and inductor L3 and fourth resistor R6 (collectively equivalent to a three-phase motor), and then connected to the first poles (drains) of Q2, Q4, and Q6. In addition, a third capacitor C3 is connected in parallel to each half-bridge branch.

[0020] In order to monitor the output current in real time, according to an embodiment of the present invention, the overcurrent detection sub-circuit 120 includes a sampling resistor R3, a current comparator U2, and a microcontroller unit U3. Among them, the sampling resistor R3 is disposed between the output of each half-bridge branch and the ground. The current comparator U2 samples the current passing through the sampling resistor R3, and the microcontroller unit U3 generates a drive signal for the corresponding drive control sub-circuit 130 based on the output of the current comparator U2. In one example, when the detected current is greater than the reference current, the drive signal is at a low level.

[0021] In order to drive the half-bridge branch, according to an embodiment of the present invention, the drive control sub-circuit 130 includes a drive chip U1. The input of some pins of the drive chip U1 is provided by the output of the overcurrent detection sub-circuit 120 and the second power supply voltage VCC1. For example, the input pin IN (pin 2) of the drive chip U1 is provided with an input level by the microcontroller unit U3, and the power supply pin VCC (pin 1) of the drive chip U1 is provided with an input level by the second power supply voltage VCC1. In addition, the SD# pin (pin 3) of the drive chip U1 is also provided with an input level by the microcontroller unit U3. Additionally, the HO pin (pin 7) of the drive chip is connected to the second pole (gate) of the one power transistor (MOSFET) (Q1, and the corresponding drive circuits of Q3 and Q5 are not shown), and the LO pin of the drive chip is connected to the second pole (gate) of the other power transistor (MOSFET) (Q2).

[0022] In addition, in order to protect the second pole (gate) of the power transistor (MOSFET), a first resistor R1 and a second resistor R2 are further included between the HO pin and the LO pin and the corresponding second pole (gate).

[0023] Regarding the setting of the remaining pins of the drive chip, according to an embodiment of the present invention, the drive control sub-circuit further includes a first capacitor C1, a first diode D1, and a second capacitor C2, which are used to provide input levels to some pins of the drive chip based on the first power supply voltage. The some pins include the COM pin provided with input through the first capacitor C1, the VB pin provided with input through the first diode D1, and the VS pin provided with input through the first diode D1 and the second capacitor C2.

[0024] According to an embodiment of the present utility model, the working principle of the three-phase full-bridge circuit is as follows: The current starts from VCC2 and sequentially flows through Q1, L1, R4, R5, L2, Q4, R3 to GND. At this time, the sampling resistor R3 can collect the current. When the current exceeds the working current of the power transistor (MOSFET), the comparator U2 immediately transmits a signal to the MCU. After receiving the overcurrent signal, the MCU stops outputting signals to the half-bridge drive chip, thereby preventing the power transistor (MOSFET) from failing due to overcurrent and protecting the power transistor (MOSFET); Similarly, when the current sequentially flows through Q3, L2, R5, R6, L3, Q6, R3 to GND, the sampling resistor R3 can also collect the current at this time to monitor the magnitude of the current, and the MCU performs protection when overcurrent occurs; Similarly, when the current sequentially flows through Q5, L3, R6, R4, L1, Q2, R3 to GND, the sampling resistor R3 can also collect the current at this time to monitor the magnitude of the current, and the MCU performs protection when overcurrent occurs; The current flowing through any pair of transistors in the three-phase full bridge can be collected by the sampling resistor R3, realizing the overcurrent detection function, improving safety, and reducing the situation of overcurrent failure.

[0025] According to an embodiment of the present utility model, the power transistor is a MOSFET or an insulated gate bipolar transistor (IGBT). When using an IGBT, the IGBT is connected in parallel with a fast recovery diode (FRD).

[0026] According to another embodiment of the present utility model, a three-phase motor control system is provided, including a three-phase full-bridge circuit with an overcurrent protection function as described above.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them. Although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present utility model can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present utility model, and they should all be covered within the scope of the claims of the present utility model.

Claims

1. A three-phase full-bridge circuit with overcurrent protection function, characterized in that: include: A three-phase full-bridge subcircuit, comprising three half-bridge branches connected in parallel, each half-bridge branch comprising at least two power transistors connected in series; an overcurrent detection subcircuit, which is arranged between the output of each half-bridge branch and the three drive control subcircuits, and outputs a drive signal based on whether the detected current is greater than a reference current; The three drive control sub-circuits are respectively arranged between the overcurrent detection sub-circuit and each half-bridge branch, and control the opening and closing of each half-bridge branch based on the received drive signal.

2. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 1, characterized in that: The first pole of a power transistor in each half-bridge branch is connected to the first power supply voltage, and the second pole and the third pole thereof are connected to different pins of the corresponding drive control sub-circuit, and the first pole, the second pole and the third pole of another power transistor in each half-bridge branch are connected to different pins of the corresponding drive control sub-circuit, wherein the third pole of the one power transistor is connected to the first pole of the other power transistor.

3. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 1, characterized in that: The overcurrent detection subcircuit includes a sampling resistor, a current comparator and a microcontroller unit, wherein the sampling resistor is arranged between the output of each half-bridge branch and the ground, the current comparator collects the current experienced by the sampling resistor, and the microcontroller unit generates a drive signal of the corresponding drive control subcircuit based on the output of the current comparator.

4. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 3, characterized in that: When the detection current is greater than the reference current, the driving signal is at a low level.

5. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 4, characterized in that: The drive control subcircuit includes a drive chip, and inputs of some pins of the drive chip are provided by the output of the overcurrent detection subcircuit and the second power supply voltage.

6. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 5, characterized in that: The HO pin of the driving chip is connected to the second electrode of the one power transistor, and the LO pin of the driving chip is connected to the second electrode of the other power transistor.

7. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 6, characterized in that: A first resistor and a second resistor are further provided between the HO pin and the LO pin and the corresponding second pole.

8. A three-phase full-bridge circuit with overcurrent protection function as claimed in claim 6, characterized in that: The drive control subcircuit also includes a first capacitor, a first diode and a second capacitor, which are used to provide input levels to some pins of the drive chip based on the first power supply voltage.

9. A three-phase full-bridge circuit with overcurrent protection function as claimed in any one of claims 1 to 8, characterized in that: The power transistor is a MOSFET or an IGBT, wherein when the IGBT is used, the IGBT is connected in parallel with the FRD.

10. A three-phase motor control system, characterized in that: It comprises a three-phase full-bridge circuit with overcurrent protection function as described in any one of claims 1 to 9.

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