CN216598976U - Short-circuit protection device of intelligent power module, frequency converter and servo system - Google Patents

Abstract

The utility model discloses a short-circuit protection device, a frequency converter and a servo system of an intelligent power module, wherein the device comprises: the short circuit detection circuit is connected with the three-phase bridge arm of the intelligent power module and outputs a short circuit signal when detecting that the three-phase bridge arm is short-circuited; and the trigger circuit is connected with the short circuit detection circuit and is used for switching off six control signals output to the three-phase bridge arm when receiving the short circuit signal. According to the short-circuit protection device, when the three-phase bridge arm is short-circuited, six control signals output to the three-phase bridge arm are cut off, so that no current path exists in the intelligent power module, and short-circuit protection is timely and reliably realized.

Description

Short-circuit protection device of intelligent power module, frequency converter and servo system

Technical Field

The utility model relates to the technical field of power electronics, in particular to a short-circuit protection device of an intelligent power module, a frequency converter and a servo system.

Background

An Intelligent Power Module, i.e., an IPM (Intelligent Power Module), is a Power driver that combines Power electronics and integrated circuit technology. The intelligent power module gains a bigger and bigger market due to the advantages of high integration level, high reliability and the like, is particularly suitable for frequency converters of driving motors and various inverter power supplies, and is a common power electronic device for variable-frequency speed regulation, metallurgical machinery, electric traction, servo drive and variable-frequency household appliances.

In order to prevent the module from being damaged due to short circuit, when the intelligent power module is detected to be short-circuited in the related art, only the lower bridge arm of the three-phase bridge arm is turned off, and current still exists outside the bridge arm under the condition, so that the intelligent power module is damaged, and even a safety fault occurs. The related art also provides a method for realizing software protection by using a controller, and the method has various delay problems, is not suitable for an intelligent power module application scene with weak short circuit tolerance capability and has poor universality.

SUMMERY OF THE UTILITY MODEL

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, a first object of the present invention is to provide a short-circuit protection device for an intelligent power module.

A second objective of the present invention is to provide a frequency converter.

A third object of the present invention is to provide a servo system.

In order to achieve the above object, a first aspect of the present invention provides a short-circuit protection device for an intelligent power module, including: the short circuit detection circuit is suitable for being connected with a three-phase bridge arm of the intelligent power module and outputs a short circuit signal when detecting that the three-phase bridge arm is short-circuited; and the trigger circuit is connected with the short circuit detection circuit and is used for switching off six control signals output to the three-phase bridge arm when receiving the short circuit signal.

According to the short-circuit protection device of the intelligent power module, the short-circuit detection circuit outputs the short-circuit signal when detecting that the three-phase bridge arm is short-circuited, and the trigger circuit turns off the six control signals output to the three-phase bridge arm when receiving the short-circuit signal. Therefore, the device can cut off six control signals output to the three-phase bridge arm when the three-phase bridge arm is short-circuited, so that no current path exists in the intelligent power module, and short-circuit protection is realized timely and reliably.

In addition, the short-circuit protection device of the intelligent power module according to the present invention may further have the following additional technical features:

further, the short-circuit protection device of the intelligent power module further comprises an isolation circuit arranged between the short-circuit detection circuit and the trigger circuit, and the isolation circuit is used for isolating the short-circuit signal output to the trigger circuit and the six control signals output to the three-phase bridge arm respectively.

Specifically, the isolation circuit comprises a first high-speed optical coupler and a second high-speed optical coupler, the first high-speed optical coupler is connected between the output end of the short circuit detection circuit and the input end of the trigger circuit, and the second high-speed optical coupler is connected between the output end of the trigger circuit and the control signal input end of the intelligent power module.

Specifically, the trigger circuit comprises a buffer circuit, and the buffer circuit stops outputting six paths of control signals when receiving the short-circuit signal through an enable end.

Specifically, the short circuit detection circuit includes a current detection unit and a comparison unit, the current detection unit detects a current flowing through each phase of the bridge arm to generate a detection voltage, and the comparison unit compares the detection voltage with a preset reference voltage and generates a short circuit signal when the detection voltage is greater than the preset reference voltage.

Specifically, the comparison unit is disposed inside the smart power module.

Specifically, the output terminal of the comparison unit is connected to a short-circuit protection pin of the intelligent power module to output a short-circuit signal to the trigger circuit.

Specifically, the current detection unit comprises a sampling resistor, one end of the sampling resistor is grounded, the other end of the sampling resistor is connected with the input end of the comparison unit, and the lower bridge arms of the three-phase bridge arms are connected together and then connected with the other end of the sampling resistor.

In order to achieve the above object, a second aspect of the present invention provides a frequency converter, including: an intelligent power module; according to the short-circuit protection device of the intelligent power module, the short-circuit protection device carries out short-circuit protection on the intelligent power module.

According to the frequency converter, the short-circuit protection can be timely and reliably realized through the short-circuit protection device of the intelligent power module, and the reliability of the frequency converter is improved.

To achieve the above object, a third aspect of the present invention provides a servo system, comprising: an intelligent power module; the short-circuit protection device performs short-circuit protection on the intelligent power module.

According to the servo system, the short-circuit protection device of the intelligent power module can timely and reliably realize short-circuit protection and improve the operation reliability of the servo system.

Additional aspects and advantages of the utility model will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the utility model.

Drawings

Fig. 1 is a block schematic diagram of a short-circuit protection device of an intelligent power module according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a short-circuit protection device of a smart power module according to one embodiment of the present invention;

fig. 3 is a block schematic diagram of a short circuit protection device of a smart power module according to one embodiment of the present invention;

fig. 4 is a block schematic diagram of a short-circuit protection device of a smart power module according to another embodiment of the present invention;

FIG. 5 is a block schematic diagram of a frequency converter according to one embodiment of the present invention;

FIG. 6 is a block diagram of a servo system according to one embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the utility model and are not to be construed as limiting the utility model.

The short-circuit protection device, the frequency converter and the servo system of the intelligent power module according to the embodiment of the utility model are described below with reference to the accompanying drawings.

The present application was made by the inventors based on the following studies:

the IPM module is internally provided with a protection circuit, when the IPM module is short-circuited, the lower bridge arm bus sampling resistor collects a large voltage, the voltage is sent into the IPM module and is compared with a reference voltage arranged in the IPM module, if the sampling voltage is larger than the reference voltage, the IPM module is short-circuited, and at the moment, the IPM module turns off the three-phase lower bridge arm and simultaneously outputs a low-level signal. However, when the IPM module is short-circuited, only the lower arm of the three-phase arm is turned off, but in an actual complex application environment, there is also a case where: when short circuit occurs outside an Insulated Gate Bipolar Transistor (IGBT) of a certain phase in a three-phase lower bridge arm of an IPM module, the IGBT of the lower bridge arm is turned off inside the IPM module, but the IGBT is already short-circuited outside the IPM module, and even if the IGBT is turned off inside, an external current path still exists, which inevitably causes damage to the IPM module and even some safety accidents.

In addition, in the related art, software protection is also realized through a controller, when the IPM module is short-circuited, a low-level control signal is sent out and transmitted to the controller through an opto-coupler, the level of the low-level signal is judged through a software program, and when the level of the low-level signal changes, 6-path PWM (Pulse width modulation) wave output of the controller is turned off through the control program, so that short-circuit protection is realized. However, in an actual application case, due to various delay problems such as optical coupling delay, signal transmission line delay, software delay and the like, the protection delay is usually several microseconds or even more than ten microseconds, and the short circuit tolerance time of the IPM module is usually only several microseconds, so that the software protection scheme is not suitable for an IPM module application scenario with weak short circuit tolerance capability, and the universality is poor.

In order to solve the problems, the utility model provides a short-circuit protection device of an intelligent power module, wherein a trigger circuit directly cuts off six control signals output to a three-phase bridge arm when the three-phase bridge arm is short-circuited, so that no current path exists in the intelligent power module, the short-circuit protection is realized timely and reliably, and the problems of signal delay, software delay and the like can be effectively avoided by using a pure circuit mode for short-circuit protection.

Fig. 1 is a block diagram illustrating a short-circuit protection device of an intelligent power module according to an embodiment of the present invention.

As shown in fig. 1, the short-circuit protection device of the smart power module according to the embodiment of the present invention may include: a short detection circuit 10 and a trigger circuit 20.

The short-circuit detection circuit 10 is adapted to be connected to a three-phase bridge arm of the intelligent power module 30, and the short-circuit detection circuit 10 outputs a short-circuit signal when detecting that the three-phase bridge arm is short-circuited. The trigger circuit 20 is connected to the short-circuit detection circuit 10, and the trigger circuit 20 turns off the six control signals output to the three-phase bridge arm when receiving the short-circuit signal. It can be understood that, in the normal working process of the IPM module, the six control signals can be driven and amplified by the corresponding driving circuit and then input to the control electrode of the IGBT tube of the corresponding bridge arm to control the switching of the switching state of the control electrode, and finally, the corresponding three-phase driving signals are output to drive the normal operation of the motor. In one embodiment of the present invention, the six-way control signal is generally a PWM control signal, and in the following embodiments, the six-way control signal is taken as an example of the PWM control signal.

Specifically, as shown in fig. 2, the three-phase bridge arm in the IPM module (intelligent power module 30) may include a three-phase upper bridge arm and a three-phase lower bridge arm, where the three-phase upper bridge arm includes three IGBT tubes (e.g., the three-phase upper bridge arm includes T1, T2, and T3, and the three-phase lower bridge arm includes T4, T5, and T6, where T1-T6 are labels of corresponding IGBT tubes), and an output end of each PWM control signal is connected to a control electrode of each corresponding IGBT to control the IGBT to switch the switching state. The six paths of PWM control signals are respectively connected with control poles of T1, T2 and T3 in the three-phase upper bridge arm and control poles of T4, T5 and T6 in the three-phase lower bridge arm, first ends of T1, T2 and T3 in the three-phase lower bridge arm are respectively connected with a positive pole of a power supply, second ends of T1, T2 and T3 in the three-phase upper bridge arm are respectively connected with first ends of T4, T5 and T6 in the three-phase lower bridge arm, second ends of T4, T5 and T6 in the three-phase lower bridge arm are connected together, and output nodes are respectively arranged between the second ends of T1, T2 and T3 in the three-phase upper bridge arm and first ends of T4, T5 and T6 in the three-phase lower bridge arm for driving a motor load to work (not shown in the figure). In an embodiment of the present invention, the T1-T6 in the above embodiments may be an N-type switch tube or a P-type switch tube.

The short-circuit detection circuit 10 is connected to three-phase arms (including a three-phase upper arm and a three-phase lower arm) of the IPM module, for example, second ends of T4, T5, and T6 in the three-phase lower arm are connected together and then connected to the short-circuit detection circuit 10, and when it is detected that a current value suddenly increases and exceeds a threshold value during normal operation, it is determined that a short-circuit phenomenon occurs in the IGBT in the three-phase lower arm, and at this time, the short-circuit detection circuit 10 outputs a short-circuit signal. When receiving the short circuit signal, the trigger circuit 20 directly turns off the six PWM control signals output to the IPM module, i.e., immediately stops outputting the PWM control signals to the three-phase upper arm and the three-phase lower arm. Because 6 IGBTs in the three-phase bridge arm do not receive the PWM control signal and are in the turn-off state, even if the IGBTs in the three-phase lower bridge arm are short-circuited and can not be turned off, because the IGBTs in the three-phase upper bridge arm are in the turn-off state, the current does not flow in the three-phase lower bridge arm under the condition that the three-phase upper bridge arm is turned off based on the connection relation of the IGBTs in the three-phase lower bridge arm and the three-phase upper bridge arm, and therefore the short-circuit protection of the lower bridge arm is realized.

According to an embodiment of the present invention, as shown in fig. 3, the short-circuit protection device further includes: and the isolation circuit 40 is arranged between the trigger circuit 20 and the short-circuit detection circuit 10, and the isolation circuit 40 is used for isolating the short-circuit signal output to the trigger circuit 20 by the short-circuit detection circuit 10 and isolating the six control signals output to the three-phase bridge arm by the trigger circuit 20. Therefore, single-phase transmission of signals can be realized, the input end and the output end are completely electrically isolated, the output signals have no influence on the input end, the anti-interference capability is strong, and the work is stable.

In order to solve the problem of optical coupling delay, the existing isolation circuit 30 adopts a common optical coupling isolation, the optical coupling may include a triode and a driving amplification circuit, and since the response time of the optical coupling working in a linear region is limited, a delay condition may occur, in an embodiment of the present invention, the isolation circuit 40 may include a first high-speed optical coupling 41 and a second high-speed optical coupling 42, wherein the first high-speed optical coupling 41 is connected between the output end of the short-circuit detection circuit 10 and the input end of the trigger circuit 20, and the second high-speed optical coupling 42 is connected between the output end of the trigger circuit 20 and the control signal input end of the intelligent power module 30.

Referring to fig. 2 and 3, the first high-speed optocoupler 41 is disposed at the input end of the trigger circuit 20 and the output end of the short circuit detection circuit 10, and transmits the short circuit signal to the input end of the trigger circuit 20 by using the high-speed optocoupler, so that the trigger circuit 20 takes corresponding measures according to the short circuit signal, thereby effectively avoiding problems of optocoupler delay, signal transmission delay and the like, improving response speed, being applicable to application scenarios of IPM modules with weak short circuit tolerance, and having strong universality. The high-speed opto-coupler 42 of second sets up between the control signal input of intelligent power module 30 and trigger circuit 20's output, can carry out signal isolation to six way PWM control signal that trigger circuit 20 sent, can also carry out level conversion simultaneously when control signal can not satisfy the requirement, for example, what trigger circuit 20 provided is 3.3V power supply, need export 5V square wave, and the opto-coupler can play level conversion's effect this moment.

It can be understood that the optical coupler works according to the principle that when an electric signal is applied to the input end of the optical coupler to enable the light-emitting device to emit light, the photosensitive device is sensitive to light to generate a photocurrent, so that the conversion between electricity and light and electricity is realized. In addition, the high-speed optocoupler comprises a photosensitive diode and an amplification driving circuit, and the common optocoupler comprises an optocoupler triode and an amplification driving circuit, wherein the response speed of the photosensitive diode is nanosecond level, and the response speed of the optocoupler triode is microsecond level, so that the response speed can be increased and the time delay can be reduced by adopting the high-speed optocoupler.

In an embodiment of the present invention, the trigger circuit 20 may be a buffer circuit, and the buffer circuit 20 stops outputting the six-way control signal when receiving the short-circuit signal through the enable terminal EN.

That is, when the IPM module normally operates, the signal received by the enable terminal EN of the buffer circuit is a high level signal, and when the IPM module is short-circuited, the signal received by the enable terminal EN of the buffer circuit is a low level signal, that is, the buffer circuit is not allowed to output the control signal to the IPM module, and immediately stops outputting the control signal to the gates of the six IGBTs of the IPM module.

In one embodiment of the present invention, as shown in fig. 4, the short circuit detection circuit 10 may include a current detection unit 11 and a comparison unit 42, the current detection unit 11 detects a current flowing through each phase of the bridge arm to generate a detection voltage, and the comparison unit 12 compares the detection voltage with a preset reference voltage and generates a short circuit signal when the detection voltage is greater than the preset reference voltage. Wherein the comparing unit 12 is arranged inside the smart power module 30. The preset reference voltage may be calibrated according to an actual condition, and may be, for example, a voltage when the IPM module normally operates, or may have a certain threshold.

Referring to fig. 2 and 4, in one embodiment of the present invention, the output terminal of the comparing unit 12 is connected to the short protection pin of the smart power module 30 to output a short signal to the trigger circuit 20.

Referring to fig. 2, in an embodiment of the present invention, the current detection unit 11 may include a sampling resistor R, one end of the sampling resistor R is grounded (corresponding to a negative electrode of a power supply), the other end of the sampling resistor R is connected to an input end of the comparison unit 12, and the lower arms of the three-phase arms are connected together and then connected to the other end of the sampling resistor R.

Specifically, as described with reference to fig. 2 and 4, when the IPM module normally operates, the 6 IGBTs are switched in a certain combination order, and the short-circuit protection pin Vfo of the IPM module outputs a high-level signal, so that the enable terminal EN of the buffer circuit normally operates, and the buffer circuit can normally output six paths of PWM control signals. Assuming that T4 in the three-phase lower bridge arm is short-circuited, at the moment, T4 is not controlled by a PWM control signal and always keeps an on state, and when T1 connected with T4 is on, the upper and lower bridge arms are directly connected and enter a short-circuit state.

When the IPM module is in a short-circuit state, a large current is generated, so that the output current of the IPM module can be collected by the current detection unit 11, the collected current is converted into a detection voltage by the bus sampling resistor (sampling resistor R) of the three-phase lower bridge arm, and then whether the IPM module is in the short-circuit state is determined according to the detection voltage value. For example, the comparing unit 12 compares the detected voltage with a reference voltage Vcin (preset reference voltage) built in the IPM module, wherein when the detected voltage is less than or equal to the reference voltage Vcin, it indicates that the IPM module is operating normally; when the detection voltage is greater than the reference voltage Vcin, the IPM module is indicated to be in short circuit, a short-circuit protection pin Vfo of the IPM module outputs a low level signal, the low level signal is accessed to an enable end EN of the cache circuit after being isolated by a high-speed optical coupler, the cache circuit is enabled, and 6 paths of PWM control signals are turned off. When the 6 paths of PWM control signals are switched off, 6 IGBTs are switched off (T1-T6 are switched off). At this time, even if the three-phase lower bridge arm is short-circuited and cannot be turned off, but the three-phase upper bridge arm is turned off, no current flows through all the 6 IGBTs in the IPM module, and short-circuit protection of the three-phase lower bridge arm is realized.

In the above embodiment, the T4 short circuit is taken as an example, and similarly, even if T5 or T6, or two or more short circuits are simultaneously performed, short circuit protection can be achieved. In addition, the application is also applicable when the IGBT in the three-phase upper bridge arm is short-circuited. In addition, it may be defined that the short-circuit protection pin of the IPM module is in a normal operating state when outputting a low level, and the corresponding output is in a short-circuit state when outputting a high level, which is not limited herein.

In summary, according to the short-circuit protection device of the intelligent power module of the present invention, when the three-phase bridge arm is short-circuited, the six control signals output to the three-phase bridge arm can be disconnected, so that no current path exists in the intelligent power module, and the short-circuit protection is timely and reliably realized.

Corresponding to the embodiment, the utility model further provides a frequency converter.

Fig. 5 is a block diagram of a frequency converter according to an embodiment of the present invention, and as shown in fig. 5, the frequency converter 200 of the present invention includes: the short-circuit protection device 100 comprises an intelligent power module 30 and the short-circuit protection device 100 of the intelligent power module, wherein the short-circuit protection device 100 performs short-circuit protection on the intelligent power module 30.

According to the frequency converter, the short-circuit protection can be timely and reliably realized through the short-circuit protection device, and the reliability of the frequency converter is improved.

Corresponding to the above embodiment, the utility model further provides a servo system.

Fig. 6 is a block diagram of a servo system according to an embodiment of the utility model, and as shown in fig. 6, the servo system 300 of the utility model may include: the intelligent power module 30 and the short-circuit protection device 100 are provided, and the short-circuit protection device 100 performs short-circuit protection on the intelligent power module 30.

According to the servo system, the short-circuit protection device can timely and reliably realize short-circuit protection and improve the operation reliability of the servo system.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A short-circuit protection device of an intelligent power module, comprising:

the short circuit detection circuit is suitable for being connected with a three-phase bridge arm of the intelligent power module and outputs a short circuit signal when detecting that the three-phase bridge arm is short-circuited;

and the trigger circuit is connected with the short circuit detection circuit, and the trigger circuit turns off six control signals output to the three-phase bridge arm when receiving the short circuit signal.

2. The short-circuit protection device of claim 1, further comprising an isolation circuit disposed between the short-circuit detection circuit and the trigger circuit, the isolation circuit isolating the short-circuit signal output to the trigger circuit and the six-way control signal output to the three-phase bridge arm, respectively.

3. The short-circuit protection device of claim 2, wherein the isolation circuit comprises a first high-speed optocoupler and a second high-speed optocoupler, the first high-speed optocoupler connected between the output of the short-circuit detection circuit and the input of the trigger circuit, the second high-speed optocoupler connected between the output of the trigger circuit and the control signal input of the smart power module.

4. The short-circuit protection device according to any one of claims 1 to 3, wherein the trigger circuit comprises a buffer circuit that stops outputting the six-way control signal when receiving the short-circuit signal through an enable terminal.

5. The short-circuit protection device according to any one of claims 1 to 3, wherein the short-circuit detection circuit includes a current detection unit that detects a current flowing through each phase bridge arm to generate a detection voltage, and a comparison unit that compares the detection voltage with a preset reference voltage and generates the short-circuit signal when the detection voltage is greater than the preset reference voltage.

6. The short-circuit protection device of claim 5, wherein the comparison unit is disposed inside the smart power module.

7. The short-circuit protection device of claim 6, wherein an output of the comparison unit is connected to a short-circuit protection pin of the smart power module to output the short-circuit signal to the trigger circuit.

8. The short-circuit protection device of claim 5, wherein the current detection unit comprises a sampling resistor, one end of the sampling resistor is grounded, the other end of the sampling resistor is connected with the input end of the comparison unit, and the lower bridge arms of the three-phase bridge arms are connected together and then connected with the other end of the sampling resistor.

9. A frequency converter, comprising:

an intelligent power module;

the short-circuit protection device according to any one of claims 1-8, short-circuit protecting the smart power module.

10. A servo system, comprising:

an intelligent power module;

the short-circuit protection device according to any one of claims 1-8, short-circuit protecting the smart power module.

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