Power converter

Abstract

The embodiment of the invention provides a power converter, the power converter comprises a power conversion circuit, an auxiliary power supply circuit and a controller, the power conversion circuit comprises at least one switching tube unit, and the switching tube unit comprises a switching tube and a driving circuit of which the first ends are connected with each other. The first ends of the switch tubes are connected with each other and then connected with the first output end of the auxiliary power supply circuit, the second end of each switch tube is connected with the second output end of the auxiliary power supply circuit through a driving circuit, and the potential of the first end of each switch tube is lower than that of the third end of each switch tube. The controller controls the target switch tube to be switched on and outputs fault information when an absolute value of a difference value between a first electrical parameter and a second electrical parameter of the auxiliary power supply circuit is greater than a set threshold value, the first electrical parameter is an electrical parameter when the target switch tube is switched off, and the second electrical parameter is an electrical parameter when the target switch tube is switched on.

Description

Technical Field

[0001] This application relates to the field of power electronics, and in particular, to a power converter. Background Art

[0002] With the gradual increase in the penetration rate of distributed energy sources such as photovoltaic, wind power, and energy storage devices, inverters or converters, as important components for energy exchange, are increasingly widely used in power supply systems. During the operation of an inverter or converter, the situation of switch tube failure may occur. For example, due to the short - circuit of the switch tube, the circuit topology may be directly connected, the bus may be short - circuited, and the switch tube may be damaged by over - current. In order to avoid starting the inverter or converter when there is a faulty switch tube to prevent further damage to the device, it is necessary to perform a power - on self - test before the inverter or converter is powered on to ensure the safe operation of the device. Summary of the Invention

[0003] An embodiment of this application provides a power converter that can detect a short - circuited switch tube in the power converter.

[0004] In a first aspect, this application provides a power converter. The power converter includes a power conversion circuit, an auxiliary power supply circuit, and a controller. The power conversion circuit includes at least one switch tube unit. The switch tube unit includes at least one switch tube and at least one drive circuit, and the first ends of at least one switch tube are connected to each other. The input end of the auxiliary power supply circuit is used to connect to a DC power supply. The auxiliary power supply circuit includes at least one first output end and at least one second output end. After the first ends of at least one switch tube in each switch tube unit are connected to each other, they are connected to a first output end of the auxiliary power supply circuit. The second end of each switch tube in the switch tube unit is connected to a second output end of the auxiliary power supply circuit through a drive circuit, and the potential of the first end of each switch tube in the switch tube unit is lower than the potential of the third end. The drive circuit connected to any one switch tube in each switch tube unit is configured to disconnect the connection between the second end of any one switch tube and the second output end of the auxiliary power supply circuit when any one switch tube is turned off, and connect the second end of any one switch tube and the second output end of the auxiliary power supply circuit when any one switch tube is turned on. The controller is configured to control the target switch tube in any one switch tube unit to conduct, and when the absolute value of the difference between the first electrical parameter and the second electrical parameter of the auxiliary power supply circuit is greater than a set threshold, output information that there is a fault in the power conversion circuit, where the first electrical parameter is the electrical parameter in the auxiliary power supply circuit when the target switch tube is turned off, and the second electrical parameter is the electrical parameter in the auxiliary power supply circuit when the target switch tube is turned on.

[0005] In this application, when the target switching device is off, the driving circuit connected to it will disconnect the connection between the second end of the target switching device and a second output terminal of the auxiliary power supply circuit; when the target switching device is on, the driving circuit connected to it will connect the second end of the target switching device to a second output terminal of the auxiliary power supply circuit. In other words, when the target switching device is off, the target switching device is not connected between a pair of first and second output terminals of the auxiliary power supply circuit, that is, it can be regarded as an open circuit between the above-mentioned first and second output terminals; when the target switching device is on, the target switching device is connected between the first and second output terminals of the auxiliary power supply circuit. It should be understood that when other conditions remain unchanged, the electrical parameters of the auxiliary power supply circuit are related to the impedance value connected between the first and second output terminals. Therefore, if the target switching device is normal, since the impedance between the first and second ends of the target switching device itself is large, after the target switching device is turned on, it can be regarded as an open circuit between the first and second output terminals of the auxiliary power supply circuit corresponding to the target switching device. Compared with when the target switching device is off, the electrical parameters between the corresponding first and second output terminals of the auxiliary power supply circuit do not change much; if an internal short circuit occurs in the target switching device, after the target switching device is turned on, the first and second output terminals of the auxiliary power supply circuit corresponding to the target switching device will be short-circuited, which will cause a large change in the electrical parameters between the first and second output terminals of the auxiliary power supply circuit. Therefore, after the controller controls the above-mentioned target switching device to be turned on, if the absolute value of the difference between the first electrical parameter and the second electrical parameter of the above-mentioned auxiliary power supply circuit is too large, such as greater than the set threshold, it is determined that the currently detected target switching device is short-circuited, and information about a fault in the output power conversion circuit is output to avoid damage to the power converter caused by the short-circuited switching device.

[0006] In a possible implementation, the auxiliary power supply circuit includes a transformer, which includes a primary winding and at least one secondary winding. The primary winding of the transformer serves as the input end of the auxiliary power supply circuit, the first end of each secondary winding of the transformer serves as a first output end of the auxiliary power supply circuit, and the second end of each secondary winding of the transformer serves as a second output end of the auxiliary power supply circuit. Since the electrical parameters on the secondary winding are related to the impedance connected between its first end and second end, after the target switch tube switches from off to on, if the target switch tube is normal, because the impedance between the first end and the second end of the target switch tube itself is large, after conduction, the first end and the second end of the secondary winding can also be regarded as an open circuit, and the power change on the secondary side of the transformer is not significant; if the target switch tube has an internal short circuit, after conduction, the first end and the second end of the secondary winding are shorted, and the power on the secondary side of the transformer increases. Therefore, if the electrical parameters on the secondary winding or the primary winding change too much, it is determined that the currently detected target switch tube is short-circuited. In addition, by providing multiple secondary windings in the transformer, one transformer in the auxiliary power supply circuit can be connected to multiple switch tube units at the same time, so as to perform short-circuit detection on the switch tubes in multiple switch tube units, reducing circuit components and saving costs.

[0007] In a possible implementation, the first electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is off, and the second electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is on. Here, if the target switch tube is normal, because the impedance between the first end and the second end of the target switch tube itself is large, after the target switch tube is turned on, the first end and the second end of the secondary winding can also be regarded as an open circuit. Compared with when the target switch tube is off, the power change on the secondary side of the transformer is not significant, making the current on the secondary winding stable; if the target switch tube has an internal short circuit, after the target switch tube is turned on, the first end and the second end of the secondary winding are shorted, and the power on the secondary side of the transformer increases, making the current on the secondary winding increase. Therefore, after the controller controls the above-mentioned target switch tube to be turned on, if the difference in the current change on the secondary winding is too large, it is determined that the currently detected target switch tube is short-circuited.

[0008] In a possible implementation, the first electrical parameter is the current value on the primary winding when the target switching device is off, and the second electrical parameter is the current value on the primary winding when the target switching device is on. Here, if the target switching device is normal, since the impedance between the first end and the second end of the target switching device itself is large, after the target switching device is turned on, the first end and the second end of the secondary winding can also be regarded as an open circuit. Compared with when the target switching device is off, the power on the secondary side of the transformer changes little, so that the power on the primary side of the transformer remains stable, and the current on the primary winding remains stable. If there is a short circuit inside the target switching device, after the target switching device is turned on, the first end and the second end of the secondary winding are short-circuited, the power on the secondary side of the transformer increases, and drives the power on the primary side to increase, resulting in an increase in the current on the primary winding. Therefore, after the controller controls the above-mentioned target switching device to be turned on, if the difference in the current change on the primary winding is too large, it is determined that the currently detected target switching device is short-circuited.

[0009] In a possible implementation, the first electrical parameter is the voltage value across the secondary winding connected to the target switching device when the target switching device is off, and the second electrical parameter is the voltage value across the secondary winding connected to the target switching device when the target switching device is on. Here, if the target switching device is normal, since the impedance between the first end and the second end of the target switching device itself is large, after the target switching device is turned on, the first end and the second end of the secondary winding can also be regarded as an open circuit. Compared with when the target switching device is off, the impedance between the first end and the second end of the secondary winding remains unchanged, and the voltage across the two ends remains stable. If there is a short circuit inside the target switching device, after the target switching device is turned on, the first end and the second end of the secondary winding are short-circuited, the impedance between the first end and the second end of the secondary winding approaches zero, and the voltage across the two ends decreases. Therefore, after the controller controls the above-mentioned target switching device to be turned on, if the difference in the voltage change of the secondary winding is too large, it is determined that the currently detected target switching device is short-circuited.

[0010] In a possible implementation, the first electrical parameter is the voltage value across the primary winding when the target switching device is off, and the second electrical parameter is the voltage value across the primary winding when the target switching device is on. Here, if the target switching device is normal, since the impedance between the first end and the second end of the target switching device itself is large, after the target switching device is turned on, the first end and the second end of the secondary winding can also be regarded as an open circuit. Compared with when the target switching device is off, the impedance between the first end and the second end of the secondary winding remains unchanged, so that the voltage across the secondary winding remains stable, and the voltage across the primary winding also remains stable. If there is a short circuit inside the target switching device, after the target switching device is turned on, the first end and the second end of the secondary winding are short-circuited, and the impedance between the first end and the second end of the secondary winding tends to zero, causing the voltage across the secondary winding to decrease and driving the voltage across the primary winding to increase. Therefore, after the controller controls the above-mentioned target switching device to turn on, if the change difference in the voltage across the primary winding is too large, it is determined that the currently detected target switching device is short-circuited.

[0011] In a possible implementation, the drive circuit includes a first push-pull switching device and a second push-pull switching device connected in series. The second end of any switching device in the switching device unit is connected to the second end of the secondary winding of any switching device through the first push-pull switching device in the corresponding drive circuit. The first push-pull switching device is configured to turn off when any switching device is off and turn on when any switching device is on. The second push-pull switching device conducts alternately with the first push-pull switching device, so that when any switching device is turned off, the second end of the switching device is disconnected from the second end of the corresponding secondary winding, and no switching device is connected between the first end and the second end of the corresponding secondary winding, and the first end and the second end of the secondary winding can be regarded as an open circuit. When the controller controls any switching device to turn on, the second end of the switching device remains electrically connected to the second end of the above-mentioned secondary winding, that is, a switching device is connected between the first end and the second end of the secondary winding, so that the controller detects the short-circuited switching device based on the voltage or current changes corresponding to the switching device in the on and off states.

[0012] In a possible implementation, the switching device in the switching device unit is a MOS transistor, and the first end of the switching device in the switching device unit is the source electrode, the second end is the gate electrode, and the third end is the drain electrode. Alternatively, the switching device in the switching device unit is an IGBT transistor, and the first end of the switching device in the switching device unit is the emitter, the second end is the gate electrode, and the third end is the collector. Description of the Drawings

[0013] Figure 1 is a schematic diagram of an application scenario of the power supply system provided by the present application;

[0014] Figure 2 is another schematic diagram of an application scenario of the power supply system provided by the present application;

[0015] Figure 3 is a schematic structural diagram of a power converter provided by this application;

[0016] Figure 4 is another schematic structural diagram of a power converter provided by this application;

[0017] Figure 5 is another schematic structural diagram of a power converter provided by this application;

[0018] Figure 6 is another schematic structural diagram of a power converter provided by this application;

[0019] Figure 7 is another schematic structural diagram of a power converter provided by this application;

[0020] Figure 8 is another schematic structural diagram of a power converter provided by this application. Detailed implementation manners

[0021] Refer to Figure 1 , Figure 1 is a schematic diagram of an application scenario of a power supply system provided by this application. The power supply system provided by this application may include a DC power source and at least one power converter. Among them, the DC power source is a photovoltaic module. Taking the power supply system including multiple power converters as an example, the DC terminals of the power converters are used to connect the photovoltaic module, and the AC terminals of the power converters are connected in parallel and then used to connect the power grid and the load. The power converter can perform an inversion conversion on the direct current provided by the photovoltaic module and output the alternating current obtained after the inversion conversion to the power grid and the load for power supply.

[0022] In some feasible implementation manners, the DC power source is a storage battery, and the DC terminals of each power converter can be used to connect the storage battery. Please refer to Figure 2 , Figure 2 is another schematic diagram of an application scenario of a power supply system provided by this application. Among the multiple power converters of the power supply system, the DC terminals of some power converters are used to connect the storage battery, and the AC terminals of the multiple power converters are connected in parallel and then used to connect the power grid and the load. Each power converter can perform an inversion conversion on the direct current provided by the photovoltaic module or the storage battery and output the alternating current obtained after the inversion conversion to the power grid and the load for power supply. Here, the power converter connecting the photovoltaic module in the power supply system can be an inverter, and the power converter connecting the storage battery in the power supply system can be a current converter.

[0023] In Figure 1 or Figure 2In the application scenario of the power supply system shown, during the operation of the power converter, the situation of switch tube failure may occur. For example, some switch tubes in the power converter are short-circuited. If the power converter operates in the case of a short-circuited switch tube, it will cause the power conversion circuit topology in the power converter to be directly connected, the bus to be short-circuited, and the switch tube to be damaged by overcurrent. In order to avoid starting the power converter when there are faulty switch tubes and causing further damage to the power converter, it is necessary to perform self-check of short-circuited switch tubes before the power converter starts to operate, that is, before the power converter is connected to the load or the power grid and performs inverter conversion, to ensure the safe operation of the device. For example, by directly detecting the conduction voltage drop across the switch tube when there is power current flowing through the switch tube to determine whether the switch tube is short-circuited. However, if the power current flows through the short-circuited switch tube, short-circuit current diffusion may occur in the power converter, which also poses a risk of damage to the power converter.

[0024] In the power converter provided by the present application, the power converter includes a power conversion circuit, an auxiliary power supply circuit, and a controller. Among them, the power conversion circuit includes a plurality of switch tube units, each switch tube unit includes at least one switch tube and at least one drive circuit, and the first ends of all the switch tubes in the switch tube unit are connected to each other. Refer to Figure 3 , Figure 3 is a schematic structural diagram of the power converter provided by the present application. As Figure 3 shown, the power conversion circuit in the power converter may include at least one switch tube unit. Taking the power conversion circuit including m switch tube units as an example, m is a positive integer. Each switch tube unit includes at least one switch tube. For example, switch tube unit 1 includes n switch tubes, that is, switch tubes K1 to Kn, and the first ends of switch tubes K1 to Kn are connected to each other, and n is a positive integer. The auxiliary power supply circuit in the power converter includes m first output terminals and m second output terminals. Taking the connection between switch tube unit 1 and the auxiliary power supply circuit as an example, refer to again Figure 3, the first ends of the switching transistors K1 to Kn in the switching transistor unit 1 are connected to each other and then connected to a first output terminal of the auxiliary power supply circuit, and the second ends of the switching transistors K1 to Kn are respectively connected to a second output terminal of the auxiliary power supply circuit through the driving circuits 1 to n. Here, among the multiple switching transistors included in the switching transistor unit 1, the potentials of the first end and the third end of any switching transistor are different. For example, the first end of the switching transistor is grounded or connected to other switching transistors, and the third end of the switching transistor is used to connect to the positive pole of the DC power supply or other switching transistors. When any switching transistor is turned on, the current passing through the switching transistor flows in from the third end of the switching transistor and flows out from the first end. In other words, the potential of the first ends of the switching transistors K1 to Kn is lower than that of the third end. The input terminal of the auxiliary power supply circuit is used to connect to the DC power supply, and the auxiliary power supply circuit is used to transform the direct current provided by the DC voltage and supply power to the driving circuits 1 to n. The driving circuits 1 to n are used to power-amplify the pulse width modulation signals generated by the controller, so that the power-amplified pulse width modulation signals can control the corresponding switching transistors to act. It can be understood that the connection of the switching transistors in the switching transistor units 2 to m and their connection to the auxiliary power supply circuit are similar to those of the switching transistor unit 1, and will not be elaborated here.

[0025] During the short-circuit detection of the target switch in the power converter, for example, before the power converter starts to operate, when the target switch is off, the driving circuit connected to it disconnects the connection between the second end of the target switch and a second output terminal of the auxiliary power supply circuit; when the target switch is on, the driving circuit connected to it connects the second end of the target switch to a second output terminal of the auxiliary power supply circuit. In other words, when the target switch is off, the target switch is not connected between a pair of first and second output terminals of the auxiliary power supply circuit, that is, it can be regarded as an open circuit between the above-mentioned first and second output terminals; when the target switch is on, the target switch is connected between the first and second output terminals of the auxiliary power supply circuit. Taking the target switch as the switch K1 in the above-mentioned switch unit 1 as an example, when the switch K1 is in the off state, the driving circuit 1 connected to it will disconnect the connection between the second end of the switch K1 and a second output terminal of the auxiliary power supply circuit, and it can be regarded as an open circuit between the first and second output terminals of the auxiliary power supply circuit connected to the switch unit 1. Obtain the first electrical parameter of the current auxiliary power supply circuit. The first electrical parameter can be the current value, voltage value, etc. between the first and second output terminals of the auxiliary power supply circuit connected to the switch unit 1. Then, the controller controls the switch K1 to conduct. When the switch K1 conducts, the second end of the switch K1 is electrically connected to a second output terminal of the above-mentioned auxiliary power supply circuit through the driving circuit 1 connected to it, that is, the switch K1 is connected between the first and second output terminals of the auxiliary power supply circuit. At this time, obtain the second electrical parameter of the current auxiliary power supply circuit. It should be understood that when other conditions remain unchanged, the electrical parameter of the auxiliary power supply circuit is related to the impedance connected between its first and second output terminals. Therefore, if the switch K1 is normal, since the impedance between the first and second ends of the switch K1 itself is large, after the switch K1 conducts, it can be regarded as an open circuit between the first and second output terminals of the auxiliary power supply circuit corresponding to the switch K1. Compared with when the switch K1 is off, the electrical parameters between the first and second output terminals of the corresponding auxiliary power supply circuit change little; if the switch K1 has an internal short circuit, after the switch K1 conducts, the first and second output terminals of the auxiliary power supply circuit corresponding to the switch K1 will be short-circuited, resulting in a large change in the electrical parameters between the first and second output terminals of the auxiliary power supply circuit. Therefore, after the controller controls the above-mentioned switch K1 to conduct, if the absolute value of the difference between the first electrical parameter and the second electrical parameter of the above-mentioned auxiliary power supply circuit is too large, for example, greater than the set threshold, it is determined that the currently detected switch K1 is short-circuited, and information about a fault in the output power conversion circuit is output to avoid damage to the power converter caused by the short-circuited switch. It can be understood that the process of short-circuit detection for other switches can refer to the detection process of the above-mentioned switch K1, which will not be elaborated here.In addition, during the short-circuit detection of the switching tube described above, since no power current flows through the short-circuited switching tube, the spread of short-circuit current is prevented, further improving the safety of the device.

[0026] In some feasible embodiments, the switching tube in the above-mentioned switching tube unit may be a metal-oxide-semiconductor field-effect transistor (MOSFET), simply referred to as a MOS tube, or may also be an insulated gate bipolar transistor (IGBT), which is not limited here. Specifically, when the switching tube in the switching tube unit is a MOS tube, the first end of the switching tube is the source electrode, the second end is the gate electrode, and the third end is the drain electrode. Or, when the switching tube in the switching tube unit is an IGBT tube, the first end of the switching tube is the emitter, the second end is the gate electrode, and the third end is the collector.

[0027] In some feasible embodiments, the auxiliary power supply circuit includes a transformer, and the transformer includes a primary winding and at least one secondary winding. Among them, the primary winding of the transformer is connected to the DC power supply as the input end of the auxiliary power supply circuit, the first end of each secondary winding of the transformer is used as a first output end of the auxiliary power supply circuit, and the second end of each secondary winding of the transformer is used as a second output end of the auxiliary power supply circuit. Taking the auxiliary power supply circuit in the power converter shown above as an example, and taking this auxiliary power supply circuit as a flyback conversion circuit as an example, please refer to Figure 3 Figure Figure 4 , Figure 4 which is another schematic structural diagram of the power converter provided by this application. As shown in Figure 4As shown in the figure, the auxiliary power supply circuit in the power converter includes a transformer T1. The primary winding L1 of the transformer T1 is connected in series with a switching transistor Q1 and then connected in parallel across both ends of a capacitor C0. The transformer T1 includes m secondary windings. The secondary windings L21 to L2m are respectively connected to switching transistor units 1 to m. Taking the connection between the secondary winding L21 and the switching transistor unit 1 as an example, the first ends of the switching transistors in the switching transistor unit 1 are connected to each other and then connected to the first end of the secondary winding L21. The second end of each switching transistor in the switching transistor unit 1 is connected to the second end of the secondary winding L21 through a driving circuit. Among them, a diode D11 is connected in series between the first end of the secondary winding L21 and the switching transistor unit 1, and after the secondary winding L21 and the diode D11 are connected in series, they are connected in parallel across both ends of a capacitor C11. The diode D11 is used to rectify the alternating current on the secondary winding L21. Both ends of the capacitor C0 are used to connect to a DC power supply. The controller is used to control the operation of the switching transistor Q1, so that the auxiliary power supply circuit transforms the DC power stored on the capacitor C0. The secondary winding L21 outputs the transformed DC power to charge the capacitor C11, and the capacitor C11 supplies power to the driving circuits 1 to n in the switching transistor unit 1. It can be understood that the connection method between the switching transistor units 2 to m and the corresponding secondary windings is similar to that of the switching transistor unit 1 above, and will not be elaborated here. In addition, by setting multiple secondary windings in the transformer, one transformer in the auxiliary power supply circuit can be connected to multiple switching transistor units at the same time, so as to perform short-circuit detection on the switching transistors in multiple switching transistor units, reducing circuit components and saving costs.

[0028] In some feasible embodiments, during the short - circuit detection of a target switch tube in a power converter, the controller controls the target switch tube in any switch - tube unit to conduct, and when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than a set threshold, outputs information indicating that there is a fault in the power - conversion circuit. Herein, the first electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is off, and the second electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is on. Specifically, taking the switch tube K1 in switch - tube unit 1 as the target switch tube as an example, when the switch tube K1 is off, the second end of the switch tube K1 is disconnected from the second end of the secondary winding L21. At this time, no switch tube is connected between the first end and the second end of the current secondary winding L21, and the first end and the second end of the secondary winding L21 can be regarded as an open circuit. The current on the current secondary winding L21 is obtained as the first electrical parameter. Then, the controller controls the switch tube K1 to conduct. When the switch tube K1 conducts, the second end of the switch tube K1 is electrically connected to the second end of the secondary winding L21 through the driving circuit connected thereto, that is, the switch tube K1 is connected between the first end and the second end of the secondary winding L21. At this time, the current value on the secondary winding L21 is obtained as the second electrical parameter. If the switch tube K1 is normal, since the impedance between the first end and the second end of the switch tube K1 itself is large, after the switch tube K1 conducts, the first end and the second end of the secondary winding L21 can also be regarded as an open circuit. Compared with when the switch tube K1 is off, the power on the secondary side of the transformer T1 changes little, so that the current on the secondary winding L21 remains stable. If the switch tube K1 is short - circuited internally, after the switch tube K1 conducts, the first end and the second end of the secondary winding L21 are short - circuited, and the power on the secondary side of the transformer T1 increases, so that the current on the secondary winding L21 increases. Therefore, after the controller controls the switch tube K1 to conduct, if the change difference of the current on the secondary winding L21 is too large, that is, when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than the set threshold, it is determined that the currently detected switch tube K1 is short - circuited, and information indicating that there is a fault in the power - conversion circuit is output, avoiding damage to the power converter caused by the short - circuited switch tube. In addition, during the above - mentioned short - circuit detection of the switch tube, no power current flows through the short - circuited switch tube, preventing the spread of short - circuit current and further improving the equipment safety.

[0029] In some feasible embodiments, during the short - circuit detection of a target switch in a power converter, the controller controls the target switch in any switch unit to conduct, and when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than a set threshold, it outputs information that there is a fault in the power conversion circuit. Here, the first electrical parameter is the current value on the primary winding when the target switch is off, and the second electrical parameter is the current value on the primary winding when the target switch is on. Specifically, when the switch K1 is off, the second end of the switch K1 is disconnected from the second end of the secondary winding L21. At this time, no switch is connected between the first end and the second end of the current secondary winding L21, and the first end and the second end of the secondary winding L21 can be regarded as an open circuit. The current on the current primary winding L1 is obtained as the first electrical parameter. For example, the switch Q1 is connected in series with the resistor R1, and the current value flowing through the resistor R1 is obtained as the first electrical parameter. Then, the controller controls the switch K1 to conduct. When the switch K1 conducts, the second end of the switch K1 is electrically connected to the second end of the secondary winding L21 through the driving circuit connected thereto, that is, the switch K1 is connected between the first end and the second end of the secondary winding L21. At this time, the current value on the primary winding L1 is obtained as the second electrical parameter. If the switch K1 is normal, since the impedance between the first end and the second end of the switch K1 itself is large, after the switch K1 conducts, the first end and the second end of the secondary winding L21 can also be regarded as an open circuit. Compared with when the switch K1 is off, the power on the secondary side of the transformer T1 changes little, so that the power on the primary side of the transformer T1 also remains stable, and the current on the primary winding L1 remains stable. If the switch K1 is short - circuited internally, after the switch K1 conducts, the first end and the second end of the secondary winding L21 are short - circuited, the power on the secondary side of the transformer T1 increases, and it drives the power on the primary side to increase, so that the current on the primary winding L1 increases. Therefore, after the controller controls the switch K1 to conduct, if the change difference of the current on the primary winding L1 is too large, that is, when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than the set threshold, it is determined that the currently detected switch K1 is short - circuited, and information that there is a fault in the power conversion circuit is output to avoid damage to the power converter caused by the short - circuited switch. In addition, during the above - mentioned short - circuit detection of the switch, no power current flows through the short - circuited switch, preventing the spread of short - circuit current and further improving the safety of the equipment.

[0030] In some feasible embodiments, during the short - circuit detection of a target switch in a power converter, the controller controls the target switch in any switch unit to conduct, and when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than a set threshold, it outputs information indicating that there is a fault in the power conversion circuit. Here, the first electrical parameter is the voltage value across the secondary winding connected to the target switch when the target switch is off, and the second electrical parameter is the voltage value across the secondary winding connected to the target switch when the target switch is on. Taking the switch K1 in switch unit 1 as the target switch as an example, when the switch K1 is off, the second end of the switch K1 is disconnected from the second end of the above - mentioned secondary winding L21. No switch is connected between the first end and the second end of the current secondary winding L21, and the first end and the second end of the secondary winding L21 can be regarded as an open circuit. The voltage across the current secondary winding L21 is obtained as the second electrical parameter. For example, the voltage value across the capacitor C11 is obtained as the second electrical parameter. The controller controls the switch K1 to conduct. When the switch K1 conducts, the second end of the switch K1 is electrically connected to the second end of the above - mentioned secondary winding L21 through the driving circuit connected to it, that is, the switch K1 is connected between the first end and the second end of the secondary winding L21. At this time, the voltage value across the capacitor C11 is obtained as the second electrical parameter. If the switch K1 is normal, since the impedance between the first end and the second end of the switch K1 itself is large, after the switch K1 conducts, the first end and the second end of the secondary winding L21 can also be regarded as an open circuit. Compared with when the switch K1 is off, the impedance between the first end and the second end of the secondary winding L21 remains unchanged, so that the voltage on the capacitor C11 remains stable. If the switch K1 is short - circuited internally, after the switch K1 conducts, the first end and the second end of the secondary winding L21 are short - circuited, and the impedance between the first end and the second end of the secondary winding L21 approaches zero, causing the voltage on the capacitor C11 to decrease. Therefore, after the controller controls the above - mentioned switch K1 to conduct, if the change difference in the voltage on the capacitor C11 is too large, that is, when the absolute value of the difference between the above - mentioned second electrical parameter and the second electrical parameter is greater than the set threshold, it is determined that the currently detected switch K1 is short - circuited, and information indicating that there is a fault in the power conversion circuit is output, avoiding damage to the power converter caused by the short - circuited switch. In addition, during the above - mentioned short - circuit detection of the switch, no power current flows through the short - circuited switch, preventing the spread of short - circuit current and further improving the equipment safety.

[0031] In some feasible embodiments, during the short - circuit detection of a target switch tube in a power converter, the controller controls the target switch tube in any switch - tube unit to conduct, and when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than a set threshold, it outputs information indicating that there is a fault in the power - conversion circuit. Herein, the first electrical parameter is the voltage value across the primary winding when the target switch tube is off, and the second electrical parameter is the voltage value across the primary winding when the target switch tube is on. Specifically, when the switch tube K1 is off, the second end of the switch tube K1 is disconnected from the second end of the secondary winding L21. At this time, no switch tube is connected between the first end and the second end of the current secondary winding L21, and the first end and the second end of the secondary winding L21 can be regarded as an open circuit. The voltage across the current primary winding L1 is obtained as the second electrical parameter. Then, the controller controls the switch tube K1 to conduct. When the switch tube K1 conducts, the second end of the switch tube K1 is electrically connected to the second end of the secondary winding L21 through the connected drive circuit, that is, the switch tube K1 is connected between the first end and the second end of the secondary winding L21. At this time, the voltage value across the primary winding L1 is obtained as the second electrical parameter. If the switch tube K1 is normal, since the impedance between the first end and the second end of the switch tube K1 itself is large, after the switch tube K1 conducts, the first end and the second end of the secondary winding L21 can also be regarded as an open circuit. Compared with when the switch tube K1 is off, the impedance between the first end and the second end of the secondary winding remains unchanged, so that the voltage on the secondary winding L21 remains stable, and the voltage on the primary winding L1 also remains stable. If the switch tube K1 is short - circuited internally, after the switch tube K1 conducts, the first end and the second end of the secondary winding L21 are short - circuited, and the impedance between the first end and the second end of the secondary winding tends to zero, causing the voltage on the secondary winding L21 to decrease and driving the voltage on the primary winding L1 to increase. Therefore, after the controller controls the switch tube K1 to conduct, if the voltage change difference on the primary winding L1 is too large, that is, when the absolute value of the difference between the first electrical parameter and the second electrical parameter is greater than the set threshold, it is determined that the currently detected switch tube K1 is short - circuited, and information indicating that there is a fault in the power - conversion circuit is output, avoiding damage to the power converter caused by the short - circuited switch tube. In addition, during the above - mentioned short - circuit detection of the switch tube, no power current flows through the short - circuited switch tube, preventing the spread of short - circuit current and further improving the safety of the equipment.

[0032] In some feasible embodiments, the drive circuit includes a first push - pull switch tube and a second push - pull switch tube connected in series. Among them, the second end of any switch tube in each switch - tube unit is connected to the second end of the secondary winding connected to the switch tube through the first push - pull switch tube in the corresponding drive circuit. The first push - pull switch tube is used to disconnect when the above - mentioned any switch tube is off and conduct when the switch tube is on. The second push - pull switch tube conducts alternately with the first push - pull switch tube. Above Figure 4Taking the drive circuit 1 connected to the switching transistor K1 in the switching transistor unit 1 as an example, please refer to Figure 5 , Figure 5 which is another structural schematic diagram of the power converter provided by this application. As Figure 5 shown, the drive circuit 1 in the power converter includes a signal isolation circuit, a first push-pull switching transistor Q21, and a second push-pull switching transistor Q22. Among them, the first end of the switching transistor K1 is connected to the first end of the secondary winding L21, the second end of the switching transistor K1 is connected to the second end of the secondary winding L21 through the first push-pull switching transistor Q21 in the drive circuit 1, and one end of the second push-pull switching transistor Q22 is connected to the first end of the secondary winding L21. The signal isolation circuit includes a light-emitting diode D21 and a photosensitive diode D22. The pulse-width modulation signal input by the controller drives the light-emitting diode D21 to emit light of a certain wavelength, and the photosensitive diode D22 reconverts the light from the light-emitting diode D21 into a pulse-width modulation signal and outputs it. The first push-pull switching transistor Q21 and the second push-pull switching transistor Q22 conduct alternately. When the switching transistor K1 is turned off, the first push-pull switching transistor Q21 remains off, and the second end of the switching transistor K1 is disconnected from the second end of the above-mentioned secondary winding L21. At this time, no switching transistor is connected between the first end and the second end of the current secondary winding L21, and the first end and the second end of the secondary winding L21 can be regarded as an open circuit, and the first electrical parameter of the current auxiliary power supply circuit is obtained. This first electrical parameter can be the current or voltage on the current primary winding L1 or secondary winding L21. When the controller controls the switching transistor K1 to conduct, the first push-pull switching transistor Q21 remains conducting, so the second end of the switching transistor K1 is kept electrically connected to the second end of the above-mentioned secondary winding L21, that is, the switching transistor K1 is connected between the first end and the second end of the secondary winding L21, and the second electrical parameter of the current auxiliary power supply circuit is obtained. If the switching transistor K1 is normal, since the impedance between the first end and the second end of the switching transistor K1 itself is large, after the switching transistor K1 conducts, the first end and the second end of the secondary winding L21 can also be regarded as an open circuit, and the difference between the first electrical parameter and the second electrical parameter is small; if the switching transistor K1 is short-circuited internally, after the switching transistor K1 conducts, the first end and the second end of the secondary winding L21 are short-circuited, resulting in a large difference between the first electrical parameter and the second electrical parameter. Therefore, after the controller controls the above-mentioned switching transistor K1 to conduct, if the absolute value of the difference between the first electrical parameter and the second electrical parameter of the auxiliary power supply circuit is too large, such as greater than the set threshold, it is determined that the currently detected switching transistor K1 is short-circuited, and information about a fault in the power conversion circuit is output to avoid damage to the power converter caused by the short-circuited switching transistor. It can be understood that the drive circuit structures connected to other switching transistors in the switching transistor unit 1 and the switching transistors in other switching transistor units ( Figure 5 not shown) are similar to the drive circuit 1 connected to the above-mentioned switching transistor K1, and the process of short-circuit detection of other switching transistors can refer to the detection process of the above-mentioned switching transistor K1, which will not be elaborated here.

[0033] Optionally, each secondary winding of the above transformer is connected to two capacitors in series. Taking the auxiliary power supply circuit in the power converter shown above as an example, please also refer to Figure 5 For example, the auxiliary power supply circuit in the power converter shown in Figure 6 , Figure 6 FIG. is another schematic structural diagram of the power converter provided by the present application. As Figure 6 shown, taking the connection between the secondary winding L21 and the switching tube unit 1 as an example, after the secondary winding L21 is connected in series with the diode D11, it is connected in parallel across the series-connected capacitors C11 and C21. The first end of the switching tube K1 in the switching tube unit 1 is connected to the first end of the secondary winding L21, or the first end of the switching tube K1 is connected to the connection end of the capacitors C11 and C21. The second end of the switching tube K1 is connected to the second end of the secondary winding L21 through the driving circuit 1. It can be understood that the connection between other switching tubes in the switching tube unit 1 and the switching tubes in other switching tube units ( Figure 6 not shown) and the secondary winding is similar to the driving circuit 1 connected to the switching tube K1, and will not be elaborated here.

[0034] Optionally, the driving circuit includes a driving gate circuit, which is composed of any one or a combination of a resistor and a diode. Refer to Figure 7 , Figure 7 FIG. is another schematic structural diagram of the power converter provided by the present application. As Figure 7 shown, Figure 7 in the power converter shown in Figure 7 In the power converter shown in

[0035] In some feasible embodiments, the power conversion circuit in the power converter may be an inverter circuit. Taking the inverter circuit with a T-type three-level topology as an example, refer to Figure 8 , Figure 8 which is another structural schematic diagram of the power converter provided by this application. As Figure 8 shown, Figure 8 the power conversion circuit in the power converter in may include a series-connected capacitor C1 and capacitor C2, and an A-phase bridge arm, a B-phase bridge arm, and a C-phase bridge arm. The above-mentioned A-phase bridge arm, B-phase bridge arm, and C-phase bridge arm respectively correspond to the A-phase, B-phase, and C-phase outputs of the power converter. Capacitor C1 is connected to the positive DC bus BUS+, and capacitor C2 is connected to the negative DC bus BUS-. The A-phase bridge arm may include a series-connected switch tube K11 and switch tube K14. The series-connected switch tube K11 and switch tube K14 are connected in parallel across the two ends of capacitor C1 and capacitor C2. The connection end of switch tube K11 and switch tube K14 is connected to the connection end of capacitor C1 and capacitor C2 through a reversely series-connected switch tube K12 and switch tube K13, and the connection end of switch tube K11 and switch tube K14 can lead out an A-phase output port. The above-mentioned B-phase bridge arm may include switch tubes K21, K22, K23, and K24, and the above-mentioned C-phase bridge arm may include switch tubes K31, K32, K33, and K34. The circuit structures of the B-phase bridge arm and the C-phase bridge arm are the same as those of the above-mentioned A-phase bridge arm, and will not be elaborated here. Figure 8The power conversion circuit shown includes multiple switch tube units. For example, the first switch tube unit includes switch tubes K13, K23, and K33, and the first ends of switch tubes K13, K23, and K33 are connected to each other. Here, after the first ends of switch tubes K13, K23, and K33 are connected to each other, they are connected to a first output terminal of the auxiliary power supply circuit a. The second ends of switch tubes K13, K23, and K33 are respectively connected to a second output terminal of the auxiliary power supply circuit a through drive circuits 13, 23, and 33. Further, a short-circuit detection is performed on the target switch tube in the above switch tube unit. The target switch tube can be any one of switch tubes K13, K23, and K33. Taking switch tube K13 as the target switch tube as an example. When switch tube K13 is turned off, the second end of switch tube K13 is disconnected from a second output terminal of the auxiliary power supply circuit a, and no switch tube is connected between the first output terminal and the second output terminal of the auxiliary power supply circuit a, that is, it can be regarded as an open circuit between the first output terminal and the second output terminal. The first electrical parameter of the current auxiliary power supply circuit a is obtained. This first electrical parameter can be the current value, voltage value, etc. between the first output terminal and the second output terminal of the auxiliary power supply circuit. Then, the controller controls switch tube K13 to conduct. When switch tube K13 conducts, the second end of switch tube K13 is electrically connected to a second output terminal of the above auxiliary power supply circuit through the connected drive circuit, that is, switch tube K13 is connected between the first output terminal and the second output terminal of the auxiliary power supply circuit. At this time, the second electrical parameter of the current auxiliary power supply circuit is obtained. If switch tube K13 is normal, since the impedance between the first end and the second end of switch tube K13 itself is large, after switch tube K13 conducts, it can be regarded as an open circuit between the first output terminal and the second output terminal of the auxiliary power supply circuit. Compared with when switch tube K13 is off, the electrical parameters between the first output terminal and the second output terminal of the auxiliary power supply circuit change little. If switch tube K13 has an internal short circuit, after switch tube K13 conducts, the first output terminal and the second output terminal of the auxiliary power supply circuit are short-circuited, which will cause a large change in the electrical parameters between the first output terminal and the second output terminal of the auxiliary power supply circuit. Therefore, after the controller controls switch tube K13 to conduct, if the absolute value of the difference between the first electrical parameter and the second electrical parameter of the above auxiliary power supply circuit is too large, for example, greater than the set threshold, it is determined that the currently detected switch tube K13 is short-circuited, and information about a fault in the output power conversion circuit is output to avoid damage to the power converter caused by the short-circuited switch tube. In addition, during the above short-circuit detection of the switch tube, no power current flows through the short-circuited switch tube, preventing the spread of short-circuit current and further improving the safety of the device.For other switch tube units in the power conversion circuit, for example, the second switch tube unit includes switch tubes K14, K24, and K34, the third switch tube unit includes switch tubes K11 and K12, the fourth switch tube unit includes switch tubes K21 and K22, and the fifth switch tube unit includes switch tubes K31 and K32. The first ends of all the switch tubes included in each of the above-mentioned switch tube units are connected to each other, and each switch tube unit is correspondingly connected to a first output terminal and a second output terminal of the auxiliary power supply circuit a. The process of short-circuit detection for the switch tubes in each switch tube unit can refer to the detection process of the above-mentioned switch tube K13, which will not be elaborated here.

Claims

1. A power converter, characterized in that: The power converter comprises a power conversion circuit, an auxiliary power supply circuit and a controller, wherein the power conversion circuit comprises at least one switch tube unit, wherein the switch tube unit comprises at least one switch tube and at least one drive circuit, wherein the first ends of the at least one switch tube are connected to each other, and the auxiliary power supply circuit comprises at least one first output end and at least one second output end; and the input end of the auxiliary power supply circuit is used to connect a DC power supply; The first ends of at least one switch tube in each of the switch tube units are connected to each other and then connected to a first output end of the auxiliary power supply circuit, the second end of each switch tube in the switch tube unit is connected to a second output end of the auxiliary power supply circuit through a driving circuit, and the potential of the first end of each switch tube in the switch tube unit is lower than the potential of the third end; The driving circuit connected to any switch tube in each of the switch tube units is used to disconnect the connection between the second end of any switch tube and the second output end of the auxiliary power supply circuit when any switch tube is disconnected, and to connect the connection between the second end of any switch tube and the second output end of the auxiliary power supply circuit when any switch tube is turned on; The controller is used to control the conduction of a target switch tube in any of the switch tube units, and output information about the presence of a fault in the power conversion circuit when the absolute value of the difference between a first electrical parameter and a second electrical parameter of the auxiliary power supply circuit is greater than a set threshold, wherein the first electrical parameter is the electrical parameter in the auxiliary power supply circuit when the target switch tube is disconnected, and the second electrical parameter is the electrical parameter in the auxiliary power supply circuit when the target switch tube is turned on.

2. The power converter according to claim 1, characterized in that: The auxiliary power supply circuit includes a transformer, and the transformer includes a primary winding and at least one secondary winding; The primary winding of the transformer serves as the input end of the auxiliary power supply circuit, the first end of each secondary winding of the transformer serves as a first output end of the auxiliary power supply circuit, and the second end of each secondary winding of the transformer serves as a second output end of the auxiliary power supply circuit.

3. The power converter according to claim 2, characterized in that: The first electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is disconnected, and the second electrical parameter is the current value on the secondary winding connected to the target switch tube when the target switch tube is turned on.

4. The power converter according to claim 2, characterized in that: The first electrical parameter is the current value on the primary winding when the target switch tube is turned off, and the second electrical parameter is the current value on the primary winding when the target switch tube is turned on.

5. The power converter according to claim 2, characterized in that: The first electrical parameter is the voltage value across the secondary winding connected to the target switch tube when the target switch tube is disconnected, and the second electrical parameter is the voltage value across the secondary winding connected to the target switch tube when the target switch tube is turned on.

6. The power converter according to claim 2, characterized in that: The first electrical parameter is the voltage value across the primary winding when the target switch tube is disconnected, and the second electrical parameter is the voltage value across the primary winding when the target switch tube is turned on.

7. The power converter according to any one of claims 2 to 6, characterized in that: The driving circuit comprises a first push-pull switch tube and a second push-pull switch tube connected in series; The second end of any switch tube in the switch tube unit is connected to the second end of the secondary winding connected to any switch tube through the first push-pull switch tube in the corresponding connected driving circuit. The first push-pull switch tube is used to be disconnected when any switch tube is disconnected, and to be turned on when any switch tube is turned on. The second push-pull switch tube is turned on alternately with the first push-pull switch tube.

8. The power converter according to any one of claims 1 to 7, characterized in that: The switch tube in the switch tube unit is a MOS tube, and the first end of the switch tube in the switch tube unit is a source, the second end is a gate, and the third end is a drain; Alternatively, the switch tube in the switch tube unit is an IGBT tube, and the first end of the switch tube in the switch tube unit is an emitter, the second end is a gate, and the third end is a collector.

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