CN114614688A - Protection device for inverter, inverter system, and electric vehicle - Google Patents

Abstract

The application discloses protection device for dc-to-ac converter, the device includes: an overvoltage detection circuit connected to the inverter and a power source of the inverter, the overvoltage detection circuit generating a fault signal in the form of an analog signal from an overvoltage voltage of the inverter; and a low side active short circuit protection circuit connected to the overvoltage detection circuit and the inverter, the low side active short circuit protection circuit to receive the fault signal to generate a drive signal from the fault signal, the drive signal to turn on a lower side IGBT in the inverter. The application also relates to an inverter system and an electric vehicle comprising the protection device. The inverter protection method and the inverter protection device can provide protection for the inverter more quickly and reliably.

Description

Protection device for inverter, inverter system, and electric vehicle

Technical Field

One or more embodiments of the present specification relate to protection of an inverter, and more particularly, to a protection device for an inverter, an inverter system, and an electric vehicle.

Background

Inverters are widely used in various scenarios, such as household and industrial appliances, uninterruptible power supplies, grid access, and so on. In recent years, with the large-scale use of electric vehicles such as electric automobiles, electric unmanned transportation vehicles, or electric bicycles, inverters are widely used in electric vehicles for converting electric power supplied from a direct-current power source (e.g., a battery) into alternating-current power to drive an alternating-current motor using the alternating-current power.

In scenarios where an inverter is used, the inverter may over-voltage due to various faults or other causes. The over-voltage can damage the inverter and other associated components and can cause other losses (e.g., losses due to loss of control of the electric vehicle). Therefore, it is often necessary to provide a protection device, or protection circuit, for the inverter.

The inverter protection device of the prior art monitors an abnormal signal of the inverter mainly through a rotation speed or voltage sensor. Upon detection of the anomaly signal, the anomaly signal is transmitted to a microcontroller unit (MCU). The MCU typically includes software logic that processes exception signals to make a fault determination. If the software logic judges that the fault comes from the motor, the MCU executes short-circuit operation on the corresponding winding of the motor through the IGBT so as to protect the inverter and personnel safety.

However, the prior art processing using an MCU (i.e., using digital circuitry) has problems, including: 1) the delay of a fault detection and processing loop is long, and the possibility of untimely protection exists; 2) the related circuit needs low-voltage power supply and is difficult to protect when the low-voltage power supply fails.

Therefore, there is a need for an inverter protection scheme that is faster, more reliable, and has a wider range of applications.

Disclosure of Invention

To overcome the deficiencies of the prior art, one or more embodiments of the present disclosure provide inverter protection schemes that are faster, more reliable, and have a wider range of applicability.

One or more embodiments of the present specification achieve the above objects by the following technical solutions.

In one aspect, a protection device for an inverter is disclosed, comprising: an overvoltage detection circuit connected to the inverter and a power source of the inverter, the overvoltage detection circuit generating a fault signal in the form of an analog signal from an overvoltage voltage of the inverter; and a low side active short circuit protection circuit connected to the overvoltage detection circuit and the inverter, the low side active short circuit protection circuit for receiving the fault signal to generate a drive signal from the fault signal, the drive signal for turning on a lower side Insulated Gate Bipolar Transistor (IGBT) in the inverter.

Optionally, the overvoltage detection circuit comprises a first electrolytic capacitor for converting the overvoltage voltage into the fault signal.

Optionally, the overvoltage detection circuit further includes a first voltage regulator tube, wherein the overvoltage voltage charges the first electrolytic capacitor to a regulated value of the first voltage regulator tube to be output as the fault signal.

Optionally, the overvoltage detection circuit further provides a low-side supply voltage with the overvoltage voltage to power the low-side active short-circuit protection circuit.

Optionally, the overvoltage detection circuit further includes a second electrolytic capacitor and a second regulator, wherein the overvoltage voltage charges the second electrolytic capacitor to a regulated value of the second regulator and is output as the low-side supply voltage.

Optionally, the low side active short circuit protection circuit is connected to a microcontroller unit, MCU, the low side active short circuit protection circuit further receiving an MCU signal from the MCU and a current signal from the inverter and generating the drive signal based on the fault signal and based on either or both of the MCU signal and the current signal.

Optionally, the protection device further includes a signal isolation circuit and a high-side active short-circuit protection circuit connected to each other, wherein the high-side active short-circuit protection circuit is connected to the low-side active short-circuit protection circuit through the signal isolation circuit, and the high-side active short-circuit protection circuit is connected to the inverter.

Optionally, the low-side active short-circuit protection circuit further outputs an interlock signal to an input side of the signal isolation circuit, the signal isolation circuit isolates voltages at the input side and the output side and is used for inverting the interlock signal and outputting the inverted interlock signal to the high-side active short-circuit protection circuit, and the high-side active short-circuit protection circuit is used for conducting an upper IGBT in the inverter based on at least the inverted interlock signal.

Optionally, the high-side active short-circuit protection circuit is connected to a microcontroller unit MCU, the high-side active short-circuit protection circuit further receives an MCU signal from the MCU and a current signal from the inverter, and generates the driving signal based on the reverse interlock signal and based on either or both of the MCU signal and the current signal.

Optionally, the protection device further includes a high-side power supply, and the high-side power supply is configured to receive and store driving power from a driving power supply, and supply power to the high-side active short-circuit protection circuit under the control of the reverse interlock signal and an MCU signal from the MCU.

Optionally, the protection device further comprises a high voltage isolation power supply that utilizes the overvoltage voltage from the inverter to power the high side active short circuit protection circuit.

Optionally, the signal isolation circuit is powered by a low side supply voltage from the overvoltage detection circuit and a voltage from the high side supply.

In another aspect, an inverter system is also disclosed, which comprises an inverter, and is characterized by further comprising the protection device for the inverter.

In yet another aspect, an electric vehicle is also disclosed, comprising an inverter system as described above.

One or more embodiments of the present description can protect the inverter more quickly and reliably than the related art.

Drawings

The foregoing summary, as well as the following detailed description of the embodiments, is better understood when read in conjunction with the appended drawings. It is to be noted that the figures are only examples of the claimed invention. In the drawings, like reference characters designate the same or similar elements.

Fig. 1 shows a schematic diagram of a conventional overvoltage protection device for an inverter.

Fig. 2 illustrates a schematic diagram of an example protection device for an inverter, according to an embodiment of the present description.

Fig. 3 illustrates a schematic diagram of another example protection device for an inverter, according to an embodiment of the present description.

Fig. 4 illustrates a schematic diagram of yet another example protection device for an inverter, according to an embodiment of the present description.

Fig. 5 shows a schematic diagram of a first example of an over-voltage detection circuit in accordance with an embodiment of the present description.

Fig. 6 illustrates a schematic diagram of a second example of an over-voltage detection circuit in accordance with embodiments of the present description.

Fig. 7 shows a schematic diagram of a first example of a low side active short protection circuit according to an embodiment of the present description.

Fig. 8 shows a schematic diagram of a second example of a low side active short protection circuit according to an embodiment of the present description.

Fig. 9 illustrates a schematic diagram of an example of a signal isolation circuit in accordance with an embodiment of the present description.

Fig. 10 shows a schematic diagram of a first example of a high-side active short-circuit protection circuit in accordance with an embodiment of the present description.

Fig. 11 shows a schematic diagram of a second example of a high-side active short-circuit protection circuit in accordance with embodiments herein.

Fig. 12 shows a schematic diagram of a first example of a high-side power supply according to an embodiment of the present description.

Fig. 13 shows a schematic diagram of a second example of a high-side power supply according to an embodiment of the present description.

Fig. 14 shows a schematic diagram of an example of a high voltage isolated power supply in accordance with an embodiment of the present description.

Detailed Description

The following detailed description is sufficient to enable any person skilled in the art to understand the technical content of one or more embodiments of the present specification and to implement the same, and the objects and advantages related to one or more embodiments of the present specification can be easily understood by those skilled in the art from the description, claims and drawings disclosed in the present specification.

In the following description, the same reference numbers will generally be used throughout the different drawings to refer to the same or like elements.

Referring to fig. 1, a schematic diagram of a conventional overvoltage protection device 100 for an inverter is shown.

As shown in fig. 1, the overvoltage protection device 100 may include a microcontroller unit (MCU)104 connected to the inverter 102, the microcontroller unit 104 typically receiving the measurement signal. The inverter 102 is powered by a dc power source (e.g., a battery) 108 and is used to drive a load, such as a three-phase load MGU. The measurement signal may be, for example, a fault signal or an overspeed signal. The fault signal can be measured, for example, by a voltage sensor, while the overspeed signal can be measured by a rotational speed detection sensor. When an overvoltage condition exists in the inverter 102 (e.g., due to an inverter fault or other reason), the measurement signal may reflect such overvoltage.

Typically, the measurement signal is transmitted to MCU 104 in the form of a digital signal. MCU 104 includes software logic or digital circuitry to process the measurement signals in the form of digital signals to detect an overvoltage condition in inverter 102. If MCU 104 determines that there is an overvoltage in inverter 102, inverter MCU 104 may transmit an Active Short (ASC) signal to gate drive circuit 106, and finally gate drive circuit 106 controls the IGBTs to short the upper or lower arms of the inverter, thereby protecting the inverter from damage.

It can be seen that this overvoltage protection device uses the signal in digital form and processes the measurement signal using software logic or digital circuitry in the MCU. However, due to the inevitable delay in the processing of the digital signals by the MCU, the fault response time of this scheme is long and therefore may not react in time to time sensitive scenarios. For example, in electric vehicles, as short a fault response time as possible is generally required to ensure safety of vehicles and personnel.

On the other hand, the overvoltage protectors mentioned above do not cover all possible faults. For example, when the MCU itself or the power supply of the overvoltage protection device fails, the overvoltage protection device cannot operate normally. And the probability of the failure of the power supply and the inverter at the same time is not low. Therefore, the applicability and reliability of the above scheme still need to be improved.

Example of an overvoltage protection device

Referring to fig. 2, a schematic diagram of an example protection device 200 for an inverter according to an embodiment of the present description is shown.

As shown in fig. 2, the protection device 200 may include an overvoltage detection circuit 202 and a low side active short circuit protection circuit 204. The overvoltage detection circuit 202 and the low side active short circuit protection circuit 204 are connected to each other and both are connected to the inverter 205.

As shown in fig. 2, in the preferred example of the present specification, the inverter 205 is connected to a three-phase load MGU, and the inverter includes three sets of IGBTs (insulated gate bipolar transistors) connected respectively to each phase U, V, W of the three-phase load, where each set of IGBTs includes an upper side IGBT and a lower side IGBT. Accordingly, in the protection device 200, a respective circuit and signal may be provided for each phase.

For ease of description, reference will generally be made to only one of the phases, but those skilled in the art will appreciate that the corresponding circuitry and signals for the other two phases may actually be included. For example, hereinafter, when referring to low side active short protection circuit 204, it may refer to any one of low side active short protection circuit U, low side active short protection circuit V, low side active short protection circuit W; when referring to a current signal, it may refer to a respective one of the current signal U, the current signal V, the current signal W; and so on.

However, it should be appreciated that aspects of the present description may be applied to other types of inverters, such as two-phase inverters. At this time, three groups of IGBTs of three phases in the inverter may be modified into two groups of IGBTs, and the corresponding circuits and signals of three phases in the overvoltage protection device 200 may be modified into circuits and signals of two phases, which is known by those skilled in the art under the teaching of this specification and will not be described herein again.

The overvoltage detection circuit 202 is connected between the inverter 205 and a power source (typically a dc power source, such as a battery) 210 to obtain the voltage between the high voltage buses of the inverter. The overvoltage detection circuit 202 generates a fault signal in the form of an analog signal from the overvoltage voltage when the high voltage inter-bus voltage exceeds a set threshold, i.e. when the inverter presents an overvoltage voltage. In the embodiments of the present description, the fault signal in the form of an analog signal is used and processed using analog circuitry, as opposed to the digital signal processed by the microcontroller unit MCU in the prior art. The fault signal may be obtained, for example, by charging an electrolytic capacitor using an overvoltage voltage between the high voltage buses of the inverter 205.

In a preferred example, the overvoltage detection circuit 202 also generates a low side supply voltage (see low side supply in fig. 2) from the overvoltage voltage, which is used to power low side circuitry (e.g., low side active short circuit protection circuit 204, etc.) for its proper operation as a power source. For example, the low side supply voltage may be obtained by charging an electrolytic capacitor using an overvoltage voltage between the high voltage busbars of the inverter 205. After an overvoltage fault occurs (for example, the back electromotive force is too high due to the runaway of the motor), the low-side active short-circuit protection circuit 204 is powered by the low-side power supply voltage through the overvoltage voltage, so that the circuit is ensured to work normally, and the generation of a driving signal can be ensured. By skillfully utilizing the overvoltage voltage of the inverter 205 itself to supply power to the protection circuit, the embodiment of the present specification can operate normally even when the power supply fails, so that more failure situations can be dealt with, and the reliability is greatly improved. It will be appreciated that although the overvoltage voltage may be used to provide the low side supply voltage in the preferred embodiment, in other embodiments the low side supply voltage may instead be provided by a dedicated voltage source.

While in other examples, the overvoltage detection circuit 202 may not generate the low side supply voltage. In this case, the low side supply voltage may be provided by a dedicated low side supply circuit, for example by a circuit connected to an external power supply.

Unlike prior art integrated circuits that utilize an MCU or the like to control protection of the inverter, in the present embodiment the low side active short protection circuit 204 (e.g., low side active short protection circuit W, low side active short protection circuit V, or low side active short protection circuit U) does not include an MCU or other form of digital integrated circuit.

The low side active short circuit protection circuit 204 may be configured to receive a fault signal from the overvoltage detection circuit 202 and generate a drive signal from the fault signal, which may be used to turn on the IGBTs on the underside of the inverter 205 to protect the inverter from damage.

In addition to fault signals, the low side active short circuit protection circuit 204 may also be connected to a MCU (not shown in the figure). The low-side active short-circuit protection circuit 204 may receive the MCU signal from the MCU and the current signal from the inverter 205, and generate a driving signal according to the MCU signal, the fault signal, and the current signal.

The MCU signal is an MCU signal sent by the MCU. When the inverter is working normally, the MCU signal is used to lock the low-side active short-circuit protection circuit 204, preventing the low-side active short-circuit protection circuit 204 from false triggering. When the MCU or the voltage source fails, the MCU signal releases the low-side active short-circuit protection circuit 204, and the low-side active short-circuit protection circuit 204 generates a driving signal (e.g., driving signal W, driving signal V, or driving signal U) based on the fault signal and the current signal. The drive signal may short circuit the corresponding IGBT on the lower side, thereby protecting the inverter 205.

The current signal (e.g., current signal W, current signal V, or current signal U in fig. 2) may be emitted by a respective IGBT of the inverter 205. The current signal represents the current flowing through the corresponding IGBT, which will be turned off after the low-side active short-circuit protection circuit 204 detects that the IGBT current is too high through the signal, thereby providing overcurrent protection.

It should be understood that, although the driving signal is generated based on the MCU signal, the fault signal and the current signal in the above preferred embodiment, in other embodiments, the driving signal may be generated based on the fault signal only, or may be generated based on the fault signal and the MCU signal only, or may be generated based on the fault signal and the current signal only, and at this time, only the circuit element not used needs to be removed or disconnected, and those skilled in the art will know how to implement the method after reading this application, and will not be described herein again.

As can also be seen in fig. 2, for an inverter 205 connected to a three-phase load MGU comprising three groups of IGBTs, a respective active short-circuit protection sub-circuit may be provided for each of the lower three IGBTs, in order to receive the current signal from each IGBT and provide a respective drive signal to each IGBT.

The connection relationship and the operation principle of the overvoltage detection circuit 202 and the low-side active short-circuit protection circuit 204 are described above, and the specific circuit structure thereof will be described in detail below.

Example two overvoltage protection device

Referring to fig. 3, a schematic diagram of another example protection device 300 for overvoltage protection of an inverter according to embodiments herein is shown.

The protection device 300 comprises all the circuitry described above with reference to fig. 2 and is extended over the circuitry of fig. 2. For example, the protection device 300 also includes the overvoltage detection circuit 202 and the low-side active short-circuit protection circuit 204, and the connection relationship between the two and other elements and the operation principle thereof can refer to the description above with respect to fig. 2.

In contrast, as shown in fig. 3, the protection device 300 may further include a signal isolation circuit 302, a high-side active short-circuit protection circuit 304, and a high-side power supply 306. The signal isolation circuit 302, the high-side active short-circuit protection circuit 304, and the high-side power supply 306 are connected to each other. In addition, the high-side active short-circuit protection circuit 304 and the high-side power supply 306 are connected to a low-side circuit (e.g., the low-side active short-circuit protection circuit 204) through the signal isolation circuit 302. The high-side active short-circuit protection circuit 304 is also connected to the inverter 205 to provide a drive signal (e.g., drive signal W, drive signal V, or drive signal U on the upper side of fig. 3) to the IGBTs on the upper side of the inverter 205.

The signal isolation circuit 302 can isolate the high voltage between the upper and lower sides (i.e., between the input and output sides of the signal isolation circuit 302) so that the circuits on the upper side can operate normally. In this case, the low side active short circuit protection circuit 204 also outputs an interlock signal (e.g., interlock signal W, interlock signal V, or interlock signal U) to an input side of a signal isolation circuit 302 (e.g., signal isolation circuit W, signal isolation circuit V, or signal isolation circuit U). The signal isolation circuit 302 may receive the interlock signal from the interlock circuit, invert the interlock signal, and transmit the inverted interlock signal (e.g., inverted interlock signal W, inverted interlock signal V, and inverted interlock signal U) to the circuits on the upper side (e.g., the high-side active short-circuit protection circuit 304). That is, the interlock signal is transmitted from the low-side active short-circuit protection circuit 204 to the high-side active short-circuit protection circuit 304 and/or the high-side power supply 306 through the signal isolation circuit 302 after being inverted, so as to ensure that the high-side IGBT is always turned off when an overvoltage fault occurs and the low-side IGBT is turned on, and the high-side IGBT is turned on when the low-side IGBT fails.

The high-side active short protection circuit 304 (e.g., the high-side active short protection circuit W, the high-side active short protection circuit V, and the high-side active short protection circuit U) may receive the reverse interlock signal sent by the signal isolation circuit 302 and turn on the upper three IGBTs based on the reverse interlock signal.

In the example shown in fig. 3, the high-side active short-circuit protection circuit 304 may also receive MCU signals (e.g., MCU signal B/MCU signal C) from the MCU. The MCU signal allows the operation of the high-side active short protection circuit 304 to be controlled by the MCU.

In addition, the high-side active short-circuit protection circuit 304 may also receive a current signal (e.g., current signal W, current signal V, or current signal U in fig. 3, upper side IGBT from the inverter) and control the operation of the high-side active short-circuit protection circuit 304 based on the current signal.

That is, the high-side active short protection circuit 304 may operate based on only the reverse interlock signal, may be based on both the reverse interlock signal and the MCU signal from the MCU, may be based on both the reverse interlock signal and the current signal from the inverter, or may be based on both the reverse interlock signal and the MCU signal from the MCU and the current signal from the inverter, so as to generate a drive signal (e.g., upper side in fig. 3) to turn on the upper side IGBT in the inverter.

In fig. 3, the high-side power supply 306 may receive a drive power supply voltage, such as the drive power supply in fig. 3 (e.g., drive power supply W, drive power supply V, or drive power supply U). The drive power supply provides an input voltage to the high side power supply 306.

The high-side power supply 306 may store power to drive the power supply while being controlled by the reverse interlock signal and the MCU signal (e.g., MCU signal a) to power the high-side active short protection circuit 304 with a high-side power supply (e.g., high-side power supply W, high-side power supply V, or high-side power supply U).

When the lower side works normally, the internal energy storage element is always in a charging state and the driving power supply is used for directly supplying power to the high-side active short-circuit protection circuit 304 and the signal isolation circuit 302. And when the MCU signal and the driving power supply disappear and the interlocking signal indicates that the lower side has a fault, the power can be supplied through the internal energy storage circuit. By this design, it is ensured that the upper protection circuit part can still operate normally when a fault occurs on the lower side.

As shown in fig. 3, there may be two MCU signals: MCU signal A and MCU signal _ B/C. The MCU signal a may be sent by an MCU (not shown in the figure) and may be used to control the relay inside the high-side power supply 306 to be turned on. The MCU signal B/MCU signal C is also an MCU signal that can be sent by the MCU and can be used to control the high side active short protection circuit 304 to allow the MCU to actively control the upper side IGBT to turn on or off when the MCU and the low voltage power supply are faultless.

It can be seen that the protection device 300 adds a protection circuit of the upper three IGBTs compared to the protection device 200. In this way, even if the IGBT on the lower side fails, an active short-circuit protection action can be made, thereby further increasing reliability with respect to the protection device 200.

It may be appreciated that although shown in fig. 3 as passing MCU signals from the MCU, it should be appreciated that in some other examples, one or both of the high-side power supply 306 or the high-side active short protection circuit 304 may not receive MCU signals from the MCU, at which time only the respective elements need to be removed or disconnected, which those skilled in the art will know after reading this application how to implement and will not be described herein. Without receiving a signal from the MCU, although the corresponding elements cannot be controlled by the MCU, the basic function of the protection circuit can still be realized, i.e., protection can still be provided on the high side if necessary based on the reverse interlock signal.

A specific circuit structure of each circuit element is described below.

Example three overvoltage protection devices

Referring to fig. 4, a schematic diagram of yet another example protection device 400 for overvoltage protection of an inverter according to embodiments herein is shown.

The protection device 400 is similar to the protection device 300 except that the high side power supply is not included in the circuit 400, but rather includes a high voltage isolated power supply (such as the high side isolated power supply 402 shown in fig. 4). The input end of the high-voltage isolation power supply is connected to the P/N point of the positive and negative connection points of the high-voltage bus, the output end of the high-voltage isolation power supply is at a specified voltage, and meanwhile, the power supply is carried out on the U/V/W of the high-side active short-circuit protection circuit. The power supply not only realizes the function of converting high-voltage electricity into designated low-voltage electricity, but also provides electrical isolation between the input side (positive and negative connection points of a high-voltage bus) and the output side and between the input side and the output side, and ensures the normal work of each part of the circuit.

The high voltage isolated power supply uses the high voltage bus voltage of the inverter as an input voltage to utilize the overvoltage voltage itself to power various circuits on the high side (e.g., the high side active short circuit protection circuit 304, etc.).

In this way, the high side can still operate normally even when the power supply fails, so that more failure situations can be dealt with, and the reliability is further improved.

It can be seen that in a preferred example, both the low-side protection circuit and the high-side protection circuit can be powered by the power generated by the overvoltage of the inverter itself, or both can be powered by another power supply, or one can be powered by a dedicated drive power supply and the other by the overvoltage. The skilled person can select as desired.

Overvoltage detection Circuit example one

Referring to fig. 5, a schematic diagram of a first example of an over-voltage detection circuit in accordance with embodiments of the present description is shown.

As shown in fig. 5, the over-voltage detection circuit 202 may include: voltage regulators D1 and D2; an anti-reverse diode D3; a zener diode D4; electrolytic capacitors C1 and C2; and current limiting resistors R1 and R2.

As shown in fig. 5, both ends of the electrolytic capacitor C1 are connected to the high-voltage bus negative connection point N and the fault signal terminal, respectively. When the voltage between the positive connection point P of the high-voltage bus and the negative connection point N of the high-voltage bus exceeds the breakdown value of the Zener diode D4, the electrolytic capacitor C1 is charged to be close to the voltage stabilizing value of the voltage stabilizing tube D1 by the excessively high voltage, and the voltage on two sides of the electrolytic capacitor C1 is finally output from one side of the voltage stabilizing tube D1 as a fault signal.

Similarly, two ends of the electrolytic capacitor C2 are respectively connected to the high-voltage bus negative connection point N and the low-side power supply end. When the voltage between the two points P, N exceeds the breakdown value of zener diode D4, the excessive voltage will charge electrolytic capacitor C2 to the vicinity of the regulated voltage value of the zener diode D2, and finally output as the low-side power supply voltage from one side of the zener diode D2. Generally, the regulated voltage value of the regulator D2 is lower than that of the regulator D1, so that the MOSFET in the low-side active short-circuit protection circuit 204 in the subsequent stage can be normally turned on.

The diode D3 can be used for preventing the voltage of the circuit connected from flowing backward into the low-side power supply circuit when the low-side power supply voltage is too low, the current-limiting resistor R1 can be used for limiting the current value flowing through the voltage regulator tube D1 and ensuring that the voltage regulator tube works at a reasonable voltage-stabilizing value, and the current-limiting resistor R2 can be used for limiting the current value flowing through the voltage regulator tube D2 and ensuring that the voltage regulator tube D2 works at a reasonable voltage-stabilizing value. The corresponding parameters of these elements can be selected by those skilled in the art as required, and are not described in detail herein.

Overvoltage detection electricityWay example two

Referring to fig. 6, a schematic diagram of a second example of an over-voltage detection circuit in accordance with embodiments of the present description is shown.

As shown in fig. 6, the over-voltage detection circuit 202 may include: voltage regulators D1 and D2; an anti-reverse diode D3; electrolytic capacitors C1 and C2; a transistor T1 and current limiting resistors R1 and R2. The difference from fig. 5 is that in the example of fig. 6, the zener diode D4 is replaced with a transistor T1.

As shown in fig. 6, two ends of the electrolytic capacitor C1 are connected to the high-voltage bus negative connection point N and the low-side power supply terminal, respectively. When the voltage between the positive connection point P of the high-voltage bus and the negative connection point N of the high-voltage bus is higher than a preset design value, the voltage regulator tube D1 provides a switching-on voltage for the transistor T1. When the transistor T1 is turned on, the voltage between the two points P, N will charge the electrolytic capacitor C1 to near the regulated value of the regulator D1, and finally output as the low-side supply voltage for supplying the low side.

Similarly, two ends of the electrolytic capacitor C2 are respectively connected to the high-voltage bus negative connection point N and the fault signal end. When the voltage between the two points P, N is higher than a preset design value, the stabilivolt D1 provides a switching-on voltage for the transistor T1, after the transistor T1 is switched on, the voltage between the two points P, N is used for charging the C2 to be close to the regulated voltage value of the stabilivolt D2, the regulated voltage value of the stabilivolt D2 is higher than the regulated voltage value of the stabilivolt D1, so that the MOSFET in the rear-stage low-side active short-circuit can be ensured to be normally switched on and finally output as a fault signal.

The diode D3 can be used for preventing the voltage of the circuit connected from flowing backward into the low-side power supply circuit when the low-side power supply voltage is too low, the current-limiting resistor R1 can be used for limiting the current value flowing through the voltage regulator tube D1 and ensuring that the voltage regulator tube works at a reasonable voltage-stabilizing value, and the current-limiting resistor R2 can be used for limiting the current value flowing through the voltage regulator tube D2 and ensuring that the voltage regulator tube D2 works at a reasonable voltage-stabilizing value.

Low side active short protection circuit example one

Referring to fig. 7, a schematic diagram of a first example of a low side active short protection circuit 204 is shown, in accordance with an embodiment of the present description.

As shown in fig. 7, the low side active short protection circuit may include: resistors R1, R2, R3, R4, R5; comparators I1, I2; a transistor T1, and a flip-flop.

As shown in FIG. 7, the positive terminal of the comparator I2 may be connected to the fault signal through resistor R4, while the negative terminal may be directly connected to the MCU signal. When the motor control related circuit breaks down, the MCU signal will output a low level, and if the fault signal is high and the Q terminal of the flip-flop is low, the comparator I2 will output a high level, so as to drive the transistor T1 to turn on as a driving signal, and finally realize the turn-on operation of the IGBT. In a preferred example, the level output by the comparator I2 may also be output as an interlock signal to the signal isolation circuit.

As shown in fig. 7, the positive terminal of the comparator I1 can be connected to the current signal pin of the corresponding IGBT, and the negative terminal of the comparator I1 can be connected to the reference voltage generated by the resistor R2 and the resistor R5. When the current signal of the corresponding IGBT exceeds the reference voltage of the negative terminal of the comparator I1, the comparator I1 outputs a high level as the trigger signal of the CP terminal of the flip-flop, the flip-flop updates the level of the Q terminal according to the level of the D terminal, and if the fault signal is a high level, the flip-flop outputs a high level to the negative terminal of the comparator I2, so that the transistor T1 is turned off, and finally the corresponding IGBT is turned off.

Resistors R3 and R4 may be used to divide the fault signal to generate a suitable voltage output to the positive terminal of comparator I2; resistors R2 and R5 may be used to divide the low side supply voltage to generate a suitable reference voltage output to the negative terminal of comparator I1; resistor R1 is the output resistor of the flip-flop and is used to adjust the output impedance at the Q-terminal of the flip-flop.

Low side active short protection circuit example two

Referring to fig. 8, a schematic diagram of a second example of a low side active short protection circuit 204 is shown, in accordance with an embodiment of the present description.

As shown in fig. 8, the low side active short protection circuit may include: resistors R1, R2, R3, R4, R5; comparators I1, I2; a transistor T1, and a flip-flop. The difference from fig. 7 is that in the example of fig. 8, the fet T1 in fig. 7 is replaced by a transistor T1 and the supply of the comparator I2 is changed to the low-side supply.

As shown in FIG. 8, the positive terminal of the comparator I2 may be connected to the fault signal through a resistor R4, and the negative terminal is directly connected to the MCU signal. When the motor control related circuit breaks down, the MCU signal will output a low level, if the fault signal is high at the moment and the Q end of the trigger is a low level, the comparator I2 will output a high level to drive the triode T1 to be conducted and output as an interlocking signal, and finally the conduction action of the IGBT is realized.

As shown in fig. 8, the comparator I1 is connected to the IGBT current signal pin, and the negative terminal is connected to the reference voltage generated by the resistor R2 and the resistor R3. When the IGBT current signal is detected to exceed the reference voltage of the negative terminal, the comparator I1 outputs a high level as a trigger signal of the CP terminal of the trigger, the trigger updates the level of the Q terminal according to the level of the D terminal, and if the fault signal is a high level, the trigger outputs a high level to the negative terminal of the comparator I2, so that the triode T1 is turned off, and the IGBT is turned off finally.

The resistor R4 and the resistor R5 in the circuit are used for dividing the fault signal to generate a proper voltage output to the positive terminal of the I2; the resistor R2 and the resistor R3 are used for dividing the low-side power supply to generate a proper reference voltage to be output to the negative terminal of the I1; resistor R1 is the output resistor of the flip-flop and adjusts the output impedance at the Q terminal of the flip-flop.

Example of Signal isolation Circuit

Referring to fig. 9, a schematic diagram of an example of a signal isolation circuit 302 is shown, according to an embodiment of the present description.

As shown in fig. 9, the signal isolation circuit may include a voltage isolation chip, which can isolate the upper and lower voltages of the IGBT and also reverse the interlock signal. Optionally, the signal isolation circuit may be powered on the lower side using a low side supply voltage. Further, optionally, the signal isolation circuit may be powered on the upper side using the high side supply 1 voltage. In addition, the signal isolation circuit receives the interlock signal from the low-side active short-circuit protection circuit at an input terminal (in), inverts the interlock signal, and outputs an inverted interlock signal at an output terminal (out) of the signal isolation circuit. In other examples, other power supply means may be used. For example, a separate power source may be used to provide power to the upper or lower side.

High side active short protection circuit example one

Referring to fig. 10, a schematic diagram of a first example of a high-side active short protection circuit 304 is shown, in accordance with an embodiment of the present description.

As shown in fig. 10, the high-side active short protection circuit may include: resistors R1, R2, R3, R4, R5; comparators I1, I2; field effect transistors T1, T2; an electrolytic capacitor C1; an anti-reverse diode D1.

As shown in FIG. 10, the positive terminal of the comparator I1 is connected to the MCU signal C and the interlock signal, and the negative terminal is connected to the MCU signal B through the anti-reverse diode D1. When the motor control related circuit is in fault, the MCU signal B/C outputs low level, if the interlock signal outputs high level at the moment, the level is higher than the level of two ends of the electrolytic capacitor C1, the comparator I1 outputs high level, the N-type field effect transistor T2 is driven to be conducted, the gate pole of the P-type field effect transistor T1 is pulled down, the T2 is conducted, and the IGBT is finally conducted.

As shown in fig. 10, the positive terminal of the comparator I2 is connected to the current signal pin of the corresponding IGBT, and the negative terminal of the comparator I2 is connected to the reference voltage generated by the resistor R4 and the resistor R5. When the corresponding IGBT current signal exceeds the reference voltage of the negative terminal of the comparator I2, the comparator I2 will output a high level to the negative terminal of the comparator I1, and the output high level is higher than the high level of the interlock signal, so the comparator I1 will output a low level, turning off the field effect transistors T1 and T2, and finally turning off the corresponding IGBT.

The resistor R1 and the resistor R2 in the circuit are pull-down resistors, so that the false operation caused by hanging pins is prevented; the resistor R3 is a pull-up resistor at the gate of the transistor T1, so that the normal on-off of the transistor T1 is ensured; the resistors R4 and R5 are used for dividing the high-side power supply 1 to generate a proper reference voltage to be output to the negative terminal of the comparator I2; the electrolytic capacitor C1 is used as an energy storage capacitor to ensure that when the MCU signal B is pulled down, the negative terminal of the comparator I1 can keep a high level for a certain time; the diode D1 is an anti-reverse diode and can be used to prevent the electric quantity stored in the electrolytic capacitor C1 from being discharged quickly when the MCU signal B is low.

High side active short protection circuit example two

Referring to fig. 11, a schematic diagram of a second example of a high-side active short-circuit protection circuit 304 is shown, in accordance with an embodiment of the present description.

As shown in fig. 11, the high-side active short protection circuit may include: resistors R1, R2, R3, R4; comparators I1, I2; a transistor T1; an electrolytic capacitor C1; an anti-reverse diode D1. The difference from fig. 10 is that in the example of fig. 11, the fets T1 and T2 of fig. 10 are replaced by a transistor T1, and there is only one high-side supply 2.

As shown in FIG. 11, the positive terminal of the comparator I1 is connected to the MCU signal C and the interlock signal, and the negative terminal is connected to the MCU signal B through the anti-reverse diode D1. When the motor control related circuit breaks down, the MCU signal B/C outputs a low level, if the interlock signal outputs a high level at the moment, and the level is higher than the voltage at the two ends of the electrolytic capacitor C1, the comparator I1 outputs a high level to drive the triode T1 to be conducted, and finally the IGBT is conducted.

As shown in fig. 11, the comparator I2 is connected to the IGBT current signal pin, and the negative terminal is connected to the reference voltage generated by the resistor R3 and the resistor R4. When detecting that the IGBT current signal exceeds the reference voltage of the negative terminal, the comparator I2 outputs a high level to the negative terminal of the comparator I1, where the level is higher than the high level of the interlock signal, so that the comparator I1 outputs a low level, turns off the transistor T1, and finally turns off the IGBT.

A resistor R1 and a resistor R2 in the circuit are pull-down resistors and can be used for preventing false operation caused by hanging pins; the resistor R3 and the resistor R4 can be used for dividing the high-side power supply 2 to generate a proper reference voltage to be output to the negative terminal of the I2; the electrolytic capacitor C1 can be used as an energy storage capacitor to ensure that when the MCU signal B is pulled down, the negative terminal of the comparator I1 can keep a high level for a certain time; the diode D1 is an anti-reverse diode and can be used to prevent the electric quantity stored in the electrolytic capacitor C1 from being discharged quickly when the MCU signal B is low.

High side Power supply example one

Referring to fig. 12, a schematic diagram of a first example of a high-side power supply 306 is shown, according to an embodiment of the present description.

As shown in fig. 12, the high-side power supply may include: a resistor R1; an electrolytic capacitor C1; an anti-reverse diode D1; a zener diode D2.

As shown in fig. 12, the positive pole of the zener diode D2 is connected to Ground, i.e. the three-phase output terminal, and the negative pole of the zener diode is connected to the high-side power supply 1, so as to ensure that the high-side power supply 1 outputs according to the set regulated voltage value.

As shown in fig. 12, the electrolytic capacitor C1 is connected negatively to the Ground, i.e. the three-phase output, and the positive terminal can be connected to the high side supply 2; preferably, the capacitance value of the electrolytic capacitor C1 can be selected to be large, or a super capacitor can be used instead. When the drive power supply fails, the energy stored in electrolytic capacitor C1 will be used to power high side supply 1 and high side supply 2.

A resistor R1 in the circuit is a current-limiting resistor of a voltage stabilizing diode D2, so that the voltage stabilizing diode D2 is ensured to work at a set voltage stabilizing value; the diode D1 is an anti-reverse diode, which prevents the stored electricity at the end of the electrolytic capacitor C1 from being released quickly when the driving power supply voltage is too low.

High side Power supply example two

Referring to fig. 13, a schematic diagram of a second example of a high-side power supply according to an embodiment of the present description is shown.

As shown in fig. 13, the high-side power supply may include: an electrolytic capacitor C1; an anti-reverse diode D1; a battery; a relay.

As shown in fig. 13, the negative pole of the battery is connected to the Ground, i.e. the three-phase output terminal, and the positive pole of the battery is connected to the high-side power supply 1, so as to ensure that the high-side power supply 1 is not affected when the driving power supply fails.

As shown in fig. 13, one end of the relay is connected to the positive electrode of the battery, and the other end is connected to the high-side power supply 2. When the motor control related circuit normally works, the MCU signal controls the relay to be conducted, so that the driving power supply is ensured to charge the battery all the time and is used as an input power supply of the high-side power supply 1; when the motor control related circuit breaks down, if the interlocking signal is high, the relay is controlled to be conducted, and therefore the high-side power supply 2 is supplied with power by the battery.

A diode D2 in the circuit is an anti-reverse diode and can be used for preventing energy from flowing backwards when the voltage of the battery is higher than that of the driving power supply; the electrolytic capacitor C1 is an energy storage capacitor of the high-side power supply 2, and mainly plays a role in filtering.

High Voltage isolated Power supply example

Referring to fig. 14, a schematic diagram of a first example of a high voltage isolated power supply 402 is shown, according to an embodiment of the present description.

As shown in fig. 14, the high voltage isolated power supply may include: electrolytic capacitors C2, C3 and C4, and a high-voltage capacitor C1; rectifier diodes D1, D2, D3; a field effect transistor T1; transformer L1.

As shown in fig. 14, the transformer is divided into a primary winding 1 and secondary windings 2, 3, 4; wherein, two ends of the primary winding 1 are respectively connected with a positive P point of the high-voltage bus and a D pole of the field effect transistor; one end of each of the secondary windings 2, 3 and 4 is connected to A, B, C three points of the three-phase output line, and the other end is connected to the anodes of the diodes D1, D2 and D3. The windings of the transformer L1 are insulated from each other, so that the energy of the high-voltage bus is transmitted to the high-side power supply U/V/W, and the insulation isolation between the high-voltage bus and the high-side power supply U/V/W is ensured. Meanwhile, the output voltage of the high-side power supply U/V/W can be controlled within a reasonable range by pre-adjusting the turn ratio between the primary winding and the secondary winding.

As shown in fig. 14, the G pole of the fet T1 receives the PWM switching signal, the D pole is connected to the winding 1 of the transformer L1, and the S pole is connected to the negative N point of the high-voltage bus. The field effect transistor receives a PWM (pulse width modulation) switching signal sent by a special power supply chip, alternately conducts a D/S (digital/analog) pole according to a certain frequency and duty ratio, and finally accurately controls the output voltage of the high-side power supply U/V/W to be a fixed value.

A capacitor C1 in the circuit is an input energy storage capacitor and is used for filtering the power supply at the input end; the capacitors C2, C3 and C4 are electrolytic capacitors and mainly play a role in filtering; the diodes D1, D2, and D3 are rectifier diodes, and function to rectify the ac voltage transmitted by the secondary windings 2, 3, and 4 into a dc voltage.

It will be appreciated that although the specific circuit structure of each circuit may be described above for only one phase, those skilled in the art will appreciate that other phases may be similarly implemented.

In another embodiment of the present specification, an inverter system is also disclosed, which may include an inverter and an inverter protection device as described in the embodiments of the present specification.

In yet another embodiment of the present specification, an electric vehicle is also disclosed, which may include the inverter system as described above. The electric vehicle may be, for example, an electric automobile, an electric unmanned transport vehicle, an electric bicycle, or the like. The electric vehicle may also include an electric aircraft, such as an unmanned aerial vehicle or the like.

Various embodiments of the present description disclose specific circuit elements and specific connections for the same. It should be appreciated, however, that those skilled in the art, having the benefit of the teachings of this specification, may implement modules having the same or similar functionality using more, less or different circuit elements and combinations thereof, and still fall within the scope of the invention.

It should be understood that the embodiments in the present specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment is described with emphasis on the differences from the other embodiments. In particular, the description of the apparatus and system embodiments is relatively simple in that they are substantially similar to the method embodiments, and reference may be made to some descriptions of the method embodiments for related aspects.

It should be understood that the above description describes particular embodiments of the present specification. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.

It should be understood that an element described herein in the singular or shown in the figures only represents that the element is limited in number to one. Furthermore, modules or elements described or illustrated herein as separate may be combined into a single module or element, and modules or elements described or illustrated herein as single may be split into multiple modules or elements.

It is also to be understood that the terms and expressions employed herein are used as terms of description and not of limitation, and that the embodiment or embodiments of the specification are not limited to those terms and expressions. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.

Also, it should be noted that while the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in the art that the above embodiments are merely illustrative of one or more embodiments of the present invention, and that various changes and substitutions of equivalents may be made without departing from the spirit of the invention, and therefore, it is intended that all such changes and modifications to the above embodiments be included within the scope of the appended claims.

Claims (14)

1. A protection device for an inverter, comprising:

an overvoltage detection circuit connected to the inverter and a power source of the inverter, the overvoltage detection circuit generating a fault signal in the form of an analog signal from an overvoltage voltage of the inverter; and

a low side active short protection circuit connected to the over-voltage detection circuit and the inverter for receiving the fault signal to generate a drive signal from the fault signal for turning on a lower insulated gate bipolar transistor IGBT in the inverter.

2. The protection device of claim 1, wherein said overvoltage detection circuit includes a first electrolytic capacitor for converting said overvoltage voltage to said fault signal.

3. The protection device of claim 2 wherein said overvoltage detection circuit further includes a first regulator, wherein said overvoltage voltage charges said first electrolytic capacitor to a regulated value of said first regulator for output as said fault signal.

4. The protection device of claim 1, wherein the overvoltage detection circuit further utilizes the overvoltage voltage to provide a low side supply voltage to power the low side active short circuit protection circuit.

5. The protection device of claim 4 wherein said overvoltage detection circuit further includes a second electrolytic capacitor and a second regulator, wherein said overvoltage voltage charges said second electrolytic capacitor to a regulated value of said second regulator and for output as said low side supply voltage.

6. The protection device of claim 1, wherein the low side active short circuit protection circuit is connected to a microcontroller unit (MCU), the low side active short circuit protection circuit also receiving an MCU signal from the MCU and a current signal from the inverter and generating the drive signal based on the fault signal and based on either or both of the MCU signal and the current signal.

7. The protection device of claim 1, further comprising a signal isolation circuit and a high-side active short protection circuit connected to each other, wherein the high-side active short protection circuit is connected to the low-side active short protection circuit through the signal isolation circuit and the high-side active short protection circuit is connected to the inverter.

8. The protection device of claim 7, wherein the low side active short circuit protection circuit further outputs an interlock signal to an input side of the signal isolation circuit, the signal isolation circuit isolating voltages at its input and output sides and for outputting the interlock signal back to the high side active short circuit protection circuit, the high side active short circuit protection circuit for turning on an upper side IGBT in the inverter based at least on a reverse interlock signal.

9. The protection device of claim 8, wherein the high side active short circuit protection circuit is connected to a microcontroller unit (MCU), the high side active short circuit protection circuit further receiving an MCU signal from the MCU and a current signal from the inverter and generating the drive signal based on the reverse interlock signal and based on either or both of the MCU signal and the current signal.

10. The protection device of claim 8, further comprising a high side power supply for receiving and storing drive power from a drive power supply and powering the high side active short circuit protection circuit under control of the reverse interlock signal and the MCU signal from the MCU.

11. The protection device of claim 10, wherein the signal isolation circuit is powered by a low side supply voltage from the overvoltage detection circuit and a voltage from the high side supply.

12. The protection device of claim 7, further comprising a high voltage isolation power supply that utilizes overvoltage voltage from the inverter to power the high side active short circuit protection circuit.

13. An inverter system comprising an inverter, characterized by further comprising a protection device for an inverter according to any one of claims 1 to 12.

14. An electric vehicle comprising the inverter system of claim 13.

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