An alternating current drive protection circuit and apparatus

Abstract

The application relates to an alternating current driving protection circuit and device, which comprises a power supply circuit, a rectification brake circuit, an inverter circuit, an MCU control circuit, a voltage detection circuit and a motor, the power supply circuit is used for providing an alternating voltage; the rectification brake circuit is used for converting the alternating voltage into a direct current voltage after rectification; the inverter circuit is used for driving the motor to work after converting the direct current voltage into a multi-phase alternating voltage; the voltage detection circuit is used for detecting voltage change in the rectification brake circuit; and the MCU control circuit is used for controlling the on-off state of the power supply circuit according to the voltage change by using an MCU. The application increases a relay, so that the relay and a diode can be controlled to be disconnected at the same time when the inverter unit part has a fault, the protection purpose is achieved, the relay is connected in series with a starting buffer resistor, a small-current relay can be used, the additional cost is very small, and the protection purpose is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of alternating current servo drive protection, and particularly relates to an alternating current drive protection circuit and device. BACKGROUND

[0002] The current market general single-phase or three-phase motor driver (including frequency converter, such as Figure 1 ; servo driver, such as Figure 2 , brushless DC driver, such as Figure 3 ) main circuit diagram, three-phase or single-phase alternating current is rectified by a rectifier bridge into direct current, charges a storage filter link composed of C1 and C2 electrolytic capacitors through a charging buffer network composed of a resistor R1 and a contactor (relay) RLY1, and then is given to a motor through an inverter link composed of six IGBTs, thereby driving the motor to run. The charging buffer network composed of R1 and RLY1 can be placed on the DC+ bus or the DC- bus. Because the motor runs with acceleration and deceleration, the energy generated during deceleration will be fed back to the direct current (DC+, DC-) bus, at which time the excess energy will be discharged by a brake IGBT opening an external energy consumption resistor R2 to protect the direct current bus devices within the operating range.

[0003] During the operation of the driver, internal single device failure cannot be avoided due to various reasons. When a single device fails, it is generally required that no fire or safety accident occurs, so safety protection measures are required for all single faults.

[0004] Disadvantages of the prior art solution:

[0005] 1. As shown in Figure 1 , the current technical solution has a motor side U V W short circuit function, that is, when the U V W of the driver connected to the motor is short-circuited or the internal short circuit of the motor, protection is achieved by detection and protection, but if the motor U V W is short-circuited to the ground, such as Figure 1 , only the LM3 can be detected, and then an external signal is given by the control loop to cut off the incoming line R S T power supply, such as Figure 2 , Figure 3 , other ways are required for protection, such as incoming line leakage switch tripping protection;

[0006] 2. As shown in Figure 1 VT1、 Figure 2 3IGBT1 single device failure (such as installation of iron filings type pin short circuit leading to damage), the external brake resistor may be always on, leading to heating and fire, and Figures 1-3 there is no better way to protect the driver inside, which can only rely on external protection;

[0007] 3 When the inverter IGBT fails and is short-circuited, the DC+DC- is in a short-circuit state, at this time, if the relay RLY1 is in the attracted state, it is equivalent to the RST input short-circuit, and external protection is required, and when the RLY1 is in the disconnected state, the internal buffer starting resistor R1 will heat up, which may cause a fire, and these in the current frequency converter or servo drive can only rely on external circuit protection or no protection.

[0008] In summary, the driver in the prior art can only rely on external circuit protection or no protection, therefore, it is urgent to find a solution that does not need to rely on external circuit for driving protection. SUMMARY

[0009] Therefore, it is necessary to provide an alternating current driving protection circuit and device to solve the technical problem that the driver in the prior art can only rely on external circuit protection or no protection.

[0010] The present application provides an alternating current driving protection circuit, comprising:

[0011] A power supply circuit, a rectification braking circuit, an inverter circuit, an MCU control circuit, a voltage detection circuit and a motor, the power supply circuit, the rectification braking circuit and the inverter circuit are sequentially connected with the motor, the MCU control circuit is connected with the power supply circuit and the rectification braking circuit, and the voltage control circuit is connected with the rectification braking circuit, the MCU control circuit and the inverter circuit.

[0012] The power supply circuit is used for providing an alternating voltage.

[0013] The rectification braking circuit is used for converting the alternating voltage into a direct current voltage after rectification.

[0014] The inverter circuit is used for driving the motor to work after converting the direct current voltage into a multi-phase alternating voltage.

[0015] The voltage detection circuit is used for detecting the voltage change in the rectification braking circuit or the inverter circuit.

[0016] The MCU control circuit is used for controlling the on-off state of the power supply circuit according to the voltage change by using the MCU.

[0017] Preferably, the power supply circuit is a three-phase alternating circuit, and the three-phase ports are R, S and T ports respectively.

[0018] Preferably, the rectification braking circuit comprises a rectification circuit and a braking circuit, the rectification circuit comprises diodes D16, D17, D18, D20, D21 and D22, and the braking circuit comprises an IGBT tube M7, a diode D23 and an external braking resistor Rext.

[0019] D17 and D21 are connected to the R terminal voltage, D16 and D20 are connected to the S terminal voltage, and D18 and D22 are connected to the T terminal voltage;

[0020] The diode D23 is connected in parallel with the external braking resistor R and then connected in series with the IGBT transistor M7.

[0021] Preferably, the rectifier braking circuit further includes a buffer circuit, which includes a relay RLY1, a diode D19, and a buffer resistor RA; RLY1 and RA are connected in series and then in parallel with the diode D19.

[0022] Preferably, the voltage detection circuit includes resistors R155 and R156 and a thyristor Q18, and the resistors R155, the thyristor Q18 and R156 are all connected in series.

[0023] Preferably, the voltage detection circuit is a thyristor detection circuit.

[0024] Preferably, the inverter circuit includes six IGBT transistors M1, M2, M3, M4, M5 and M6, and two of the six IGBT transistors are grouped together to provide three-phase AC voltage to the motor to drive the motor to work.

[0025] The present invention provides an AC drive protection device, comprising the AC drive protection circuit as described in any of the preceding claims.

[0026] The beneficial effects of this invention are as follows: By adding a relay, when the inverter unit malfunctions, the relay and diode can be simultaneously disconnected to achieve the purpose of protection. At the same time, the relay is connected in series with the starting buffer resistor, so a small current relay can be used, and the additional cost is very small, thus achieving the purpose of protection. Attached Figure Description

[0027] Figure 1 This is a diagram of the main circuit of a frequency converter drive in a conventional motor driver.

[0028] Figure 2 This is the main circuit diagram of a servo driver in a conventional motor driver.

[0029] Figure 3 This is the main circuit diagram of a brushless DC driver in a conventional motor driver.

[0030] Figure 4 A circuit framework diagram of an embodiment of the AC drive protection circuit provided by the present invention;

[0031] Figure 5 A circuit schematic diagram of another embodiment of the AC drive protection circuit provided by the present invention;

[0032] Figure 6 The circuit principle diagram of another embodiment of the AC drive protection circuit provided by the present application;

[0033] Figure 7 The circuit principle diagram of an embodiment of part of the AC drive protection circuit provided by the present application;

[0034] Figure 8 The circuit principle diagram of another embodiment of part of the AC drive protection circuit provided by the present application. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application. The drawings and the associated descriptions are provided to illustrate the preferred embodiments of the present application and to explain the principles of the present application, but are not intended to limit the scope of the present application.

[0036] As shown in Figure 4 , the embodiments of the present application provide an AC drive protection circuit, which comprises:

[0037] a power supply circuit 10, a rectification brake circuit 20, an inverter circuit 30, an MCU control circuit 40, a voltage detection circuit 50 and a motor 60, the power supply circuit 10, the rectification brake circuit 20, the inverter circuit 30 and the motor 60 are electrically connected in sequence, the MCU control circuit 40 is electrically connected with the power supply circuit 10 and the rectification brake circuit 20, and the voltage control circuit 50 is electrically connected with the rectification brake circuit 20, the MCU control 40 circuit and the inverter circuit 30;

[0038] The power supply circuit 10 is used for providing an AC voltage;

[0039] The rectification brake circuit 20 is used for converting the AC voltage into a DC voltage after rectification;

[0040] The inverter circuit 30 is used for driving the motor 60 to work after converting the DC voltage into a multi-phase AC voltage through inversion;

[0041] The voltage detection circuit 40 is used for detecting the voltage change in the rectification brake circuit or the inverter circuit;

[0042] The MCU control circuit 50 is used for controlling the on-off state of the power supply circuit according to the voltage change through MCU.

[0043] It should be noted that, in normal circumstances, when the power supply circuit 10 provides power supply voltage, generally three-phase power, through the rectifier brake circuit 20 to convert the power supply voltage to DC voltage, and after voltage and current buffering treatment, by the inverter circuit 30, the three-phase AC power is converted back to AC three-phase power, and then the motor 60 is driven to work. However, in actual motor operation, when a fault occurs, such as motor side three-phase U V W short circuit, inverter circuit failure, etc., it will cause the driver to short circuit and damage, and the present application detects the voltage change (such as sudden voltage drop) in the rectifier brake circuit or inverter circuit by setting the voltage detection circuit 50 to consume the heat caused by short circuit by switching the on-off state of the diode / thyristor, and further the voltage change in the rectifier brake circuit or inverter circuit can be fed back to the MUC control circuit 40 to control the on-off of the power supply circuit 10.

[0044] As a preferred embodiment, please refer to Figure 5 , Figure 5 The circuit principle diagram of another embodiment of the AC drive protection circuit provided by the present application, the power supply circuit (i.e. starting power supply) is a three-phase AC circuit, and the three-phase ports are R, S and T respectively. In this embodiment, the voltage detection circuit is a thyristor detection circuit.

[0045] Further, the rectifier brake circuit (i.e. rectifier brake part) includes a rectifier circuit and a brake circuit; the rectifier circuit includes diodes D16, D17, D18, D20, D21 and D22, and the brake circuit includes IGBT tube M7, diode D23 and external brake resistor Rext.

[0046] The D17 and D21 are connected to the R port voltage, the D16 and D20 are connected to the S port voltage, and the D18 and D22 are connected to the T port voltage. Specifically, the rectifier circuit is a bridge rectifier circuit.

[0047] The diode D23 is connected in parallel with the external brake resistor Rext and connected in series with the IGBT tube M7.

[0048] As a preferred embodiment, the rectifier brake circuit further includes a buffer circuit, and the buffer circuit includes a relay RLY1, a diode D19 and a buffer resistor RA; the RLY1 is connected in series with the RA and connected in parallel with the diode D19.

[0049] Specifically, the buffer circuit is the core content of the present application. By adding RLY1, when the inverter unit part fails, RLY1 and D19 can be controlled to be disconnected at the same time, so as to achieve the purpose of protection. At the same time, RLY1 is connected in series with the starting buffer resistor RA, a small current relay can be used, the additional cost is very small, and the purpose of protection is achieved.

[0050] It should be noted that,Figure 5 D19 is a turn-off thyristor, and the gate signal of D19 is positive in normal operation, so that D19 operates normally, and when a fault occurs, the control signal of relay RLY1 and the gate control signal of D19 are simultaneously cut off, so that the unit in the rear stage is powered off, and the protection purpose is achieved.

[0051] As a preferred embodiment, the inverter circuit comprises six IGBT tubes M1, M2, M3, M4, M5 and M6, and two groups of the six IGBT tubes respectively provide three-phase alternating voltage to drive the motor to operate.

[0052] Further, please refer to Figure 6 , Figure 6 The circuit principle diagram of another embodiment of the AC drive protection circuit provided by the application is shown in the figure.

[0053] In order to further illustrate how the application protects the drive circuit when the inverter unit has a fault, please refer to Figures 7-8 , Figure 7 The circuit principle diagram of an embodiment of part of the AC drive protection circuit provided by the application is shown in the figure. Figure 8 The circuit principle diagram of another embodiment of part of the AC drive protection circuit provided by the application is shown in the figure, and the inverter circuit and the motor part are not included in the figure.

[0054] In the embodiment, the buffer circuit comprises relay RLY1, diode D19 and buffer resistor RA, and the RLY1 and the RA are connected in series and then connected in parallel with the diode D19.

[0055] The voltage detection circuit comprises resistors R155, R156 and thyristor Q18, and the resistors R155, thyristor Q18 and R156 are all connected in series.

[0056] Please refer to the circuit CD point in the figure, and the C point and the D point in the figure are the anode and the cathode of the D19 diode, and the gate of D19 is opened in normal operation. The voltage between CD changes with the current flowing therethrough, and the maximum voltage drop between CD in normal operation is within a certain range, for example, within 1.5V, and when a short circuit or a fault in the rear stage occurs, the voltage drop between CD increases because the current suddenly increases, so that whether a short circuit occurs can be judged by detecting the voltage between CD (the control timing of the starting MCU needs to be combined to judge), the scheme circuit is simple, the cost is lower, and no power consumption is generated. The technical point that needs to be overcome in the method of detecting the voltage between CD is that the circuit needs to be switched at the time of starting or after protection, and the voltage between CD is detected, for example, Figure 8, can be from the figure R155 sampling, when R155 resistance voltage is greater than a certain value, can be closed in the figure Q18, can protect the circuit, or use automatic range switching circuit (mature circuit - multimeter mature circuit, in the measurement industry belongs to general circuit, not here). This circuit and the measurement industry difference is here only need to detect a low voltage as a reference, the accuracy requirement is not high.

[0057] The application also provides an AC drive protection device, which comprises an AC drive protection circuit, and the AC drive protection device is similar to the implementation process of the AC drive protection circuit, and details are not repeated here.

[0058] In summary, the AC drive protection device provided by the application has the following beneficial effects:

[0059] The application has the following beneficial effects: the application adds a relay, so that the relay and the diode can be controlled to be turned off simultaneously when the inverter unit part has a fault, and the protection purpose is achieved; the relay is connected in series with the starting buffer resistor, a small-current relay can be used, the additional cost is very small, and the protection purpose is achieved.

[0060] In summary, only the preferred specific implementation of the application is described, but the protection scope of the application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, and all the changes or replacements should be covered in the protection scope of the application.

Claims

1. An alternating current drive protection circuit, characterized by, The application relates to an alternating current driving protection circuit, which comprises a power supply circuit, a rectification braking circuit, an inverter circuit, an MCU control circuit, a voltage detection circuit and a motor, wherein the power supply circuit, the rectification braking circuit and the motor are sequentially electrically connected, the MCU control circuit is electrically connected with the power supply circuit and the rectification braking circuit, and the voltage detection circuit is electrically connected with the rectification braking circuit, the MCU control circuit and the inverter circuit. The power supply circuit is used for providing an alternating voltage. The rectification braking circuit comprises a buffer circuit, a rectification circuit and a braking circuit; the rectification circuit is used for converting the alternating voltage into a direct current voltage after rectification. The braking circuit comprises an IGBT tube M7, a diode D23 and an external braking resistor Rexternal; the diode D23 and the external braking resistor Rexternal are connected in parallel and then connected in series with the IGBT tube M7. The buffer circuit comprises a relay RLY1, a diode D19 and a buffer resistor RA; the RLY1 and the RA are connected in series and then connected in parallel with the diode D19; the RLY1 is a small-current relay; the diode D19 is a turn-off thyristor; when the inverter circuit is faulty, the control signal of the RLY1 and the gate control signal of the diode D19 are simultaneously cut off so as to make the inverter circuit lose power. The inverter circuit is used for driving the motor to work after converting the direct current voltage into a multiphase alternating voltage. The voltage detection circuit is used for detecting voltage changes in the rectification braking circuit or the inverter circuit; the heat caused by short circuit is consumed by switching the on-off state of the diode D19; the voltage detection circuit is a silicon controlled detection circuit; the detection end of the voltage detection circuit is connected between the anode and the cathode of the diode D19, and the detection end connected with the cathode of the diode D19 is also connected with the input side of the inverter circuit; whether short circuit or the inverter circuit is faulty is judged by detecting the voltage change between the anode and the cathode of the diode D19. The MCU control circuit is used for controlling the on-off state of the power supply circuit according to the voltage changes. The power supply circuit is a three-phase alternating current circuit, and the three-phase ports are R, S and T respectively.

2. The AC drive protection circuit of claim 1, wherein, The rectification circuit comprises diodes D16, D17, D18, D20, D21 and D22.

3. The AC drive protection circuit of claim 2, wherein, The D17 and D21 are connected with the R voltage, the D16 and D20 are connected with the S voltage, and the D18 and D22 are connected with the T voltage. The voltage detection circuit comprises resistors R155, R156 and a thyristor Q18, and the resistors R155, the thyristor Q18 and the resistor R156 are connected in series.

4. The AC drive protection circuit of claim 3, wherein, The inverter circuit comprises six IGBT tubes M1, M2, M3, M4, M5 and M6, and two groups of the six IGBT tubes respectively provide three-phase alternating voltages for the motor to drive the motor to work.

5. The AC drive protection circuit of claim 1, wherein, The application further discloses an alternating current driving protection circuit comprising the alternating current driving protection circuit as claimed in any one of claims 1-5.

6. An alternating current drive protection device characterized by, ​

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