Power electronics and method for supplying a voltage to a drive circuit of a power semiconductor switch

Abstract

The invention relates to a power electronic device having a first power semiconductor switch, a drive circuit and an auxiliary circuit arrangement, which has a supply capacitor and an auxiliary capacitor, a normally-off auxiliary semiconductor switch, a diode and a bootstrap diode, the auxiliary semiconductor switch being connected via a first connection point on a reference potential terminal of the first power semiconductor switch, from which first connection point a series circuit of the diode, a second connection point and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch, such that when the auxiliary semiconductor switch is switched off, the auxiliary capacitor is charged by the current flowing through the first power semiconductor switch, and the supply capacitor is electrically connected to the second connection point via the bootstrap diode on the one hand and to the reference potential terminal on the other hand, such that when the auxiliary semiconductor switch is switched on and the auxiliary capacitor is charged, the supply capacitor is charged by the auxiliary capacitor via the bootstrap diode.

Description

[0001] This invention relates to a power electronic device, particularly a converter, having at least one first power semiconductor switch. The power electronic device further includes a drive circuit to drive the first power semiconductor switch.

[0002] The present invention also relates to a method for supplying voltage to a drive circuit of a power semiconductor switch.

[0003] Power electronic devices can be, for example, buck converters, boost converters, or buck-boost converters or inverters. Such converters include power semiconductor switches that are switched accordingly by the converter to transform the voltage applied to the input side. To drive the power semiconductor switches, a control signal is applied to the control input of the power semiconductor switches. The control input can be, for example, the gate terminal of an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Integrated circuits (which may also be called clock generators or signal generators) typically use, for example, microprocessors to generate drive signals for the power semiconductor switches. However, the output current or voltage provided by these integrated circuits is often insufficient to directly drive the power semiconductor switches. Therefore, drive circuits are used between the clock generator and the power semiconductor switches. These drive circuits generate control signals of sufficient current and voltage from the drive signals of the clock generator, making these control signals available at the drive output at the control input of the power semiconductor switches. The drive and control signals can be so-called pulse-width modulated (PWM) drive / control signals, where the pulse pattern of the drive / control signals can be generated in a clock generator using modulation and control variables. The modulation variable can have a periodic, triangular, or sawtooth voltage curve, while the control variable can have a constant curve corresponding to the voltage value of the control variable. The pulse pattern of the PWM drive signal can be generated by comparing the control and modulation variables, where the clock generator is controlled, for example, by the converter's controller, in terms of the frequency and amplitude (Höhe) of the modulation variable and the amplitude of the control value, based on the current operating state of the converter. Alternatively, the control signal can also have a fixed duty cycle, be generated via an attached current regulator (current mode), or be generated in other ways based on a switching threshold and / or a fixed switching time, where the switching frequency can also be variable. The clock generator and drive circuitry can be housed in a common component. The power semiconductor switches can each have a body diode or include diodes with polarity corresponding to the body diode for protection of these power semiconductor switches or for reverse conduction functionality.

[0004] During the operation and startup of electrical equipment, electrical power should be supplied to its necessary components (in the case of a converter, such as the converter controller and the drive circuit of the converter's power semiconductor switches). For example, during the startup of a converter, a DC voltage can be applied at least between the first and second terminals of the converter's input, provided, for example, by a DC generator such as a photovoltaic module or a series circuit (string) of such modules. The DC voltage applied in this way can, for example, power the necessary components during startup.

[0005] This invention relates to supplying voltage to at least one drive circuit of a power electronic device. The invention also relates to a method of supplying voltage to a drive circuit of a power semiconductor switch. Such a drive circuit for a power semiconductor switch (e.g., a MOSFET or IGBT) requires a supply of a voltage typically between 10 and 20 volts, which is related to the potential of a reference potential terminal of the power semiconductor switch. The reference potential terminal is, for example, the emitter terminal in the case of a bipolar transistor or IGBT, or the source terminal in the case of a MOSFET. In particular, drive circuits for power semiconductor switches are difficult to power, as these drive circuits must be operational before or are part of the onboard power supply of the converter.

[0006] It is well known that, using an integrated drive circuit (PWM controller), the input voltage of a converter designed as a flyback converter (Sperrwandler) charges the power supply capacitor of the clock generator via a high-impedance resistor, and the capacitor voltage is limited via a parallel Zener diode. This device is inefficient, achieving only 15V / 400V = 3.8% efficiency with an input voltage of, for example, 400V and a required drive voltage of 15V. Therefore, this known device is only suitable for the startup of the flyback converter.

[0007] The object of the present invention is to provide a power electronic device of the type described at the beginning, particularly a converter of the type described at the beginning, and a method of the type described at the beginning, by means of which a voltage can be supplied to at least one drive circuit of a power semiconductor switch in a manner and method at least suitable for the operation mode of a power electronic device or a power semiconductor switch.

[0008] According to the present invention, this objective is achieved in power electronic devices of the type described at the outset by including an electrical auxiliary circuit arrangement for supplying voltage to a drive circuit, wherein the auxiliary circuit arrangement includes a power supply capacitor and an auxiliary capacitor, a normally off auxiliary semiconductor switch, a diode, and a bootstrap diode. Here, the auxiliary semiconductor switch is connected via a first connection point to a reference potential terminal of a first power semiconductor switch. Starting from the first connection point, a series circuit of the diode, a second connection point, and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch such that when the auxiliary semiconductor switch is off, the auxiliary capacitor is charged by the current flowing through the power semiconductor switch. To supply voltage to the drive circuit, the drive circuit is connected to the power supply capacitor, and the power supply capacitor is electrically connected via the bootstrap diode to a second connection point via a first terminal and to the reference potential terminal via a second terminal, such that when the auxiliary semiconductor switch is on and the auxiliary capacitor is at least partially charged, the power supply capacitor is charged by the auxiliary capacitor via the bootstrap diode.

[0009] Therefore, the objective of the invention is achieved in a power electronic device of the type described at the outset using an auxiliary circuit comprising an auxiliary switch integrated into the basic circuitry for the main function of the power electronic device. For example, the main function of a converter is to rectify current. Here, the auxiliary switch is only used to supply power to the drive circuit of a first power semiconductor switch and, if necessary, to the additional drive circuits of other power semiconductor switches, and has no or substantially no effect on the main function of the power electronic device or converter compared to the first power semiconductor switch used for the main function. The period during which the auxiliary switch is closed (i.e., turned on) to charge the supply capacitor by the auxiliary capacitor does not interfere with this main function of the power electronic device or converter, because the turned-on auxiliary switch essentially acts as part of the electrical connection. In the startup condition of the power electronic device or converter, that is, during the startup process of a power electronic device or converter that is turned off, a DC voltage is applied to the first power semiconductor switch between its reference potential terminal and another main terminal, for example because the DC voltage of a DC generator is applied to the input terminal of the power electronic device. In the startup condition, the auxiliary switch cannot interfere with the main function of the power electronic device or converter itself, because this main function does not yet exist during the startup condition. During the operation of the power electronic equipment or converter, the first power semiconductor switch switches at a high frequency. If the first power semiconductor switch is off, that is, not conducting, the auxiliary switch, depending on its switching state, either behaves as part of the electrical connection or as the first power semiconductor switch itself, such that the main function of the power electronic equipment or converter is unaffected by the corresponding switching state of the auxiliary switch. If the first power semiconductor switch is closed, that is, conducting, the current intensity of the power path of the basic circuit flows through the first power semiconductor switch. Due to the low energy demand of the drive circuit, the basic circuit is not significantly affected by the charging of the auxiliary capacitor, and because of the current intensity of the basic circuit, the time period during which the auxiliary switch is off is kept sufficiently small to not significantly affect the main function.

[0010] During startup, the auxiliary capacitor can be charged via a first power semiconductor switch and a first diode, wherein the first power semiconductor switch can be normally open or normally closed. In both cases, the first power semiconductor switch can have leakage current in the off switching state. Typically, the first power semiconductor switch is normally closed and has leakage current when a voltage is applied between the two main terminals of the power semiconductor switch (i.e., between the reference potential terminal of the power semiconductor switch and the other main terminal) in the off switching state. Leakage current is the residual current that still flows through the component when a corresponding voltage is present when the power semiconductor switch is off. This leakage current flows through the power semiconductor switch in the normal flow direction, or through the body diode of the power semiconductor switch or an additional diode with the same polarity as the body diode included in the power semiconductor switch in the off direction. During the operation of the power electronic equipment or converter, the auxiliary capacitor can also be charged via the leakage current of the first power semiconductor switch during the off period, and during the on operation period of the first power semiconductor switch, the auxiliary capacitor can be charged by means of a portion of the current that normally flows through the first power semiconductor switch. Whenever the auxiliary semiconductor switch is turned on, the auxiliary capacitor releases at least a portion of its charge to the power supply capacitor, allowing the power supply capacitor to power the actual drive circuit. To shorten the charging time of the power supply capacitor during startup, an additional starting resistor can be provided to provide additional charging current to both the power supply capacitor and the auxiliary capacitor. One terminal of the starting resistor can be electrically connected, for example, to another main terminal of the first power semiconductor switch, and the second terminal of the starting resistor can be electrically connected to the first terminal of the power supply capacitor of the drive circuit.

[0011] Therefore, according to the present invention, voltage is supplied to the drive circuit of the first power semiconductor switch by charging the power supply capacitor from the auxiliary capacitor, wherein the auxiliary capacitor is charged during the operation of the power electronic device or converter by means of the current flowing through the first power semiconductor switch (leakage current or current when the first power semiconductor switch is turned on), so that the power electronic device or converter according to the present invention can supply voltage to the drive circuit of the first power semiconductor switch, and due to its good efficiency, such voltage supply is suitable for both the start-up and operation of the power electronic device or converter.

[0012] To illustrate the integration of auxiliary switches from auxiliary circuitry into the basic circuitry (which includes a first power semiconductor switch) for the main function of the converter, according to an embodiment, the converter may have an input terminal and an output terminal, wherein a third connection point is electrically connected to a first terminal of the input terminal, and a fourth connection point is connected to a second terminal of the input terminal, wherein a first connection branch extends from the third connection point to the fourth connection point. According to an embodiment, starting from the third connection point, the first connection branch includes the first power semiconductor switch, the first connection point, and a normally-off auxiliary switch connected in series. According to an embodiment, a second electrical connection branch extends from the fourth connection point to a fifth connection point, and starting from the fourth connection point, includes an auxiliary capacitor, a second connection point, a diode, the first connection point, and a supply capacitor connected in series, wherein the fifth connection point and the second connection point are electrically connected in parallel with the second connection branch via a bootstrap diode. According to an embodiment, the converter further includes a drive circuit electrically connected to the control terminal of the first power semiconductor switch via a drive output terminal, the drive circuit being connected in parallel with the supply capacitor to supply voltage to the drive circuit. According to an embodiment, the converter may further include a comparator circuit connected to a control terminal of an auxiliary switch via a comparator output. The comparator circuit is designed to provide a control signal at its comparator output based on the charging voltage of the auxiliary capacitor. The diode is arranged to conduct in such a way that, in at least one first operating state of the converter, when the auxiliary switch is off, the auxiliary capacitor is charged via the diode and a first power semiconductor switch. The bootstrap diode is arranged to conduct in such a way that, in at least one second operating state, when the auxiliary switch is on, the power supply capacitor is charged by the auxiliary capacitor via the bootstrap diode.

[0013] Advantageous designs of the present invention are given in this application, and their features can be applied individually or in any combination thereof.

[0014] Advantageously, the auxiliary circuit device includes a drive circuit designed and configured to provide a control signal for switching the auxiliary semiconductor switch at the control input terminal of the auxiliary semiconductor switch based on the charging voltage of the auxiliary capacitor.

[0015] The drive circuit can obtain its own voltage supply from the auxiliary capacitor. Since the auxiliary switch is usually normally off, the auxiliary capacitor can therefore be initially charged via the first power semiconductor switch. The drive circuit only needs to provide a control signal at the control input of the auxiliary switch to charge the supply capacitor from the auxiliary capacitor. The auxiliary switch can only close when the auxiliary capacitor is charged to a voltage sufficient to supply power to the drive circuit, and can be opened again at a lower charging voltage (hysteresis), so that whenever the auxiliary switch is turned on, the auxiliary capacitor supplies power to the supply capacitor of the drive circuit for the first power semiconductor switch via a bootstrap diode according to a bootstrap principle. The auxiliary circuit arrangement can be designed such that after the first power semiconductor switch is first turned on, the supply capacitor is charged and supplies power to the drive circuit, so that when the first power semiconductor switch is clocked, a higher current flows through the auxiliary circuit, and the auxiliary capacitor and the supply capacitor are continuously recharged. Specifically, the drive circuit can be designed and configured such that when the charging voltage of the auxiliary capacitor exceeds a first threshold, the drive circuit provides a control signal at its control input to turn on the auxiliary switch. The first threshold may correspond to or substantially correspond to the supply voltage of the drive circuit. Within the scope of this application, the term "supply voltage of the drive circuit" does not mean the voltage applied to the drive circuit or the voltage provided by the power supply capacitor for the drive circuit, but rather means a voltage value associated with the components of the drive circuit suitable for driving the first power semiconductor switch. For example, the supply voltage of the drive circuit may be between a minimum supply voltage associated with the components and a maximum supply voltage associated with the components, or a predetermined voltage value associated with the components, and in particular, may be a voltage value appropriately selected based on the first power semiconductor switch used to power the drive circuit. Because the auxiliary switch and auxiliary circuit device are protected from excessive voltage by means of the switching on of the auxiliary switch when a first threshold is reached, all components of the auxiliary circuit device can be designed only for this lower voltage, thereby allowing the use of inexpensive components in the auxiliary circuit device.

[0016] Advantageously, the drive circuit can be designed and configured to provide a control signal to turn on the auxiliary semiconductor switch at the control input terminal when the charging voltage of the auxiliary capacitor exceeds a first threshold, and to provide a control signal to turn off the auxiliary semiconductor switch at the control input terminal when the charging voltage of the auxiliary capacitor is lower than a second threshold less than the first threshold, wherein the first threshold corresponds at least to the supply voltage of the drive circuit.

[0017] Since the auxiliary switch is a normally closed auxiliary switch, the cut-off control signal can, for example, be a control signal that is not present. This is also referred to as a "cut-off control signal" within the scope of this invention. In other words, when the charging voltage of the auxiliary capacitor is lower than the second threshold, the drive circuit may not provide a control signal at the control input terminal of the auxiliary semiconductor switch, because, depending on the switch type, this can also have a cut-off effect on the auxiliary semiconductor switch. The term "on" refers to a control signal that places the auxiliary semiconductor switch in a closed switching state, i.e., a conducting switching state, so that the auxiliary capacitor charges the power supply capacitor.

[0018] The first threshold may correspond at least to the voltage value of the supply voltage of the drive circuit of the first power semiconductor switch. Refer to the above explanation for the meaning of the term "supply voltage of the drive circuit." Specifically, the first threshold may be equal to or slightly higher than this supply voltage (e.g., higher than the turn-on voltage of the bootstrap diode) such that, in operation, the supply voltage of the drive circuit is substantially set at the supply capacitor while the auxiliary capacitor is charging it. An advantageous design of the drive circuit of the power electronic device has a hysteresis function that avoids instability in the switching behavior of the auxiliary switch while the auxiliary capacitor is charging the supply capacitor.

[0019] According to an advantageous design of the invention, the drive circuit can be a two-point regulator, particularly a comparator circuit, or a monostable trigger, a PWM regulator, or a frequency regulator.

[0020] Advantageous designs of the present invention can be implemented using standard components. For example, the comparator circuit may include a common comparator having inverting and non-inverting inputs and an output connected to a control input of an auxiliary switch. For hysteresis behavior, a positive feedback resistor is electrically included between the comparator's output and non-inverting inputs.

[0021] Advantageously, it can be further proposed that the drive circuit is designed and configured to be electrically connected to an auxiliary capacitor, so that voltage is supplied to the drive circuit by means of the auxiliary capacitor.

[0022] Powering the drive circuit from an auxiliary capacitor is particularly effective. For example, the drive circuit can be connected in parallel with the auxiliary capacitor. In a comparator circuit design, the comparator circuit can include a comparator connected in parallel with the auxiliary capacitor via two power supply terminals. The charging voltage of the auxiliary capacitor can be applied to the non-inverting input of the comparator via wiring, and a reference voltage can be applied to the inverting input of the comparator. For example, a series circuit of a Zener diode in the cutoff direction, an eighth connection point, and a resistor can be arranged in parallel with the auxiliary capacitor, wherein the non-inverting input of the comparator is connected to the eighth connection point, and the inverting input of the comparator is connected to the reference potential.

[0023] It can also be considered advantageous that the auxiliary semiconductor switch has the same polarity as the first power semiconductor switch.

[0024] Furthermore, it can be advantageously proposed that the first power semiconductor switch is designed to be normally closed, and has leakage current when a voltage is applied between the reference potential terminal of the first power semiconductor switch and another main terminal in the closed switching state.

[0025] The first power semiconductor switch has a reference potential terminal, another main terminal, and a control terminal. As an embodiment of the normally off first power semiconductor switch, the first power semiconductor switch can be designed as an n-channel MOSFET, and the reference potential terminal can be the source terminal of the MOSFET, and the other main terminal can be the drain terminal of the MOSFET.

[0026] Alternatively, in addition to the advantageous design described above, the first power semiconductor switch may be designed to be normally off and may include a start-up resistor. The start-up resistor may be connected via a first terminal to another main terminal of the first power semiconductor switch and via a second terminal to a terminal of the power supply capacitor.

[0027] If the normally closed first power semiconductor switch has leakage current, the starting resistor can advantageously shorten the startup time. If the normally closed first power semiconductor switch has no leakage current, the starting resistor can charge the power supply capacitor and the auxiliary capacitor during startup, such that when the auxiliary semiconductor switch is off, the current flowing through the starting resistor during startup and subsequently through the current flowing through the first power semiconductor switch during operation charge the auxiliary capacitor.

[0028] Furthermore, it can be advantageously proposed that auxiliary circuit devices, particularly auxiliary semiconductor switches, be dedicated to supplying power to at least one drive circuit.

[0029] This design of the invention clarifies that the auxiliary switch has no or substantially no impact on the primary function of the power electronic device or converter, just like the primary power semiconductor switch used for the primary function. Although the auxiliary switch is integrated into the basic circuitry for the primary function of the power electronic device, it is not included in the power semiconductor switches of the power electronic device or converter, which, in the case of a converter, are arranged and configured to perform the primary function of rectifying current in the converter.

[0030] An advantageous design of the present invention may be proposed in which the drive circuit is designed to be integrated with a clock generator, wherein the clock generator is designed to generate pulse patterns of control signals provided by the drive circuit.

[0031] This reduces the space requirements of components and the manufacturing cost of power electronic devices.

[0032] Alternatively, the pulse pattern can be generated in another circuit section and supplied to the drive circuit directly or electrically isolated (e.g., via an optocoupler).

[0033] It can also be considered advantageous that the power electronic device includes a half-bridge, which, starting from a third connection point, includes a series circuit consisting of a high-voltage side power semiconductor switch, a branch point (Abzweigpunkt), a low-voltage side power semiconductor switch, and a fourth connection point, wherein the low-voltage side power semiconductor switch is designed as the first power semiconductor switch, and in particular, the power electronic device is a DC / DC converter or inverter.

[0034] An auxiliary switch is arranged together with the first power semiconductor switch above or below the branch point. According to the design of the present invention, the power electronic device includes at least one auxiliary circuit device for supplying voltage to the drive circuit driving the low-voltage-side power semiconductor switch. This enables the supply of voltage to the drive circuit driving the low-voltage-side power semiconductor switch during startup and operation. The power electronic device may include a starting resistor connected via one terminal to a third connection point or branch point and via another terminal to a first terminal of the power supply capacitor of the auxiliary circuit device to supply voltage to the drive circuit driving the low-voltage-side power semiconductor switch.

[0035] If the converter is an inverter, it can be, for example, a single-phase inverter and includes a full bridge (so-called H-bridge) consisting of two half-bridges, with chokes connected downstream of one or two branch points. The inverter can also be, for example, a three-phase inverter, with each phase including a half-bridge, where a choke is connected downstream of each of the three branch points. If the converter is a bidirectional DC / DC converter, it can include a half-bridge with chokes connected downstream of the branch points of that half-bridge. The voltage can be set using a half-bridge regardless of the current direction. Therefore, energy can be transferred in both directions. Thus, the concepts of input and output terminals of the converter can be arbitrarily chosen as needed. For an inverter, the input terminal is arranged on the DC side and is referred to as the DC side, while the output terminal is arranged on the AC side and is referred to as the AC side. To supply voltage to the drive circuit of the low-voltage side power semiconductor switches of the inverter, according to the design of the present invention, each low-voltage side power semiconductor switch can include its own auxiliary circuitry and its own auxiliary switch.

[0036] It can also be considered advantageous to include an intermediate circuit having an electrical connection that connects the third connection point to the fourth connection point via one or more intermediate circuit capacitors connected in series or in parallel.

[0037] Furthermore, it can be advantageously proposed that the high-voltage side power semiconductor switch and the low-voltage side power semiconductor switch each include a drive circuit for driving the respective power semiconductor switch, and each includes its own electrical auxiliary circuit device for supplying voltage to the drive circuit, so that the high-voltage side power semiconductor switch and the low-voltage side power semiconductor switch are respectively designed as first power semiconductor switches.

[0038] Alternatively, it may be advantageously proposed to include a drive circuit for driving a high-voltage-side power semiconductor switch and a supply capacitor for supplying voltage to the drive circuit. The supply capacitor is electrically connected via one terminal to a reference potential terminal of the high-voltage-side power semiconductor switch and via another terminal to a first terminal of the supply capacitor included in an auxiliary circuit arrangement via another bootstrap diode. The supply capacitor is used to supply voltage to the drive circuit for driving the low-voltage-side power semiconductor switch.

[0039] It can also be advantageously proposed that the high-voltage side power semiconductor switch and the low-voltage side power semiconductor switch are normally closed and have leakage current when a voltage is applied between their reference potential terminals and their other main terminals in the closed switching state.

[0040] Another objective of the present invention is to provide a method for supplying voltage to a drive circuit, by which voltage can be supplied to at least one drive circuit of a power semiconductor switch in a manner and method at least suitable for the operation mode of a power semiconductor switch.

[0041] Therefore, the power supply capacitor supplies voltage to the drive circuit. During the switching state of the normally closed auxiliary switch, the auxiliary capacitor is charged by the current flowing through the power semiconductor switch, thus charging the power supply capacitor. When the normally closed auxiliary switch is turned on, the auxiliary capacitor charges the power supply capacitor.

[0042] Therefore, the auxiliary capacitor can be charged by the current or a portion of the current flowing through the power semiconductor switch, regardless of the manner in which it is charged, making this charging of the auxiliary capacitor particularly energy-efficient. The electrical energy stored in the auxiliary capacitor in this way can be used at least partially to power the supply capacitor, which in turn ultimately powers the power semiconductor switch, and can also be used, for example, to power the auxiliary switch or at least one additional supply capacitor of at least one other drive circuit. For example, the current flowing through the power semiconductor switch can be the leakage current during startup or the operating current during operation of the power semiconductor switch; therefore, the method is applicable to both startup and operation of the power semiconductor switch. The power semiconductor switch can also be referred to as a first power semiconductor switch. This method can be performed using the device described in this application, wherein the power semiconductor switch used in the method is the first power semiconductor switch of that device.

[0043] It is also advantageous to connect a normally closed auxiliary switch to the reference potential terminal of the power semiconductor, such that in the first step, when the auxiliary switch is off, at least a portion of the current flowing through the power semiconductor switch is diverted to the auxiliary capacitor and at least partially charges the auxiliary capacitor; in the second step, the auxiliary switch is turned on and at least a portion of the charge of the auxiliary capacitor is released to the power supply capacitor; and in the third step, the auxiliary switch is turned off again, thereby supplying electrical power to the power supply capacitor by repeating these three steps multiple times, so as to supply power to the drive circuit in operation.

[0044] It can also be advantageously proposed that the auxiliary switch be turned on based on the charging voltage of the auxiliary capacitor.

[0045] This process is independent of the current intensity flowing through the power semiconductor switch, and therefore applies to the startup and operation of the power semiconductor switch.

[0046] It can also be advantageously proposed that when the charging voltage of the auxiliary capacitor exceeds a first threshold, the auxiliary switch is turned on, and when the charging voltage of the auxiliary capacitor is lower than a second threshold, the auxiliary switch is turned off, wherein the second threshold is less than the first threshold.

[0047] An advantageous design of this method allows the auxiliary capacitor to charge the power supply capacitor while the switching behavior of the auxiliary switch remains stable. The first threshold may correspond at least to the voltage value of the supply voltage of the drive circuit of the power semiconductor switch. Specifically, the first threshold may be equal to or slightly higher than the supply voltage value, such that during operation, while the auxiliary capacitor charges the power supply capacitor, the supply voltage of the drive circuit is substantially set at the power supply capacitor. Within the scope of this application, the term "supply voltage of the drive circuit" does not mean the voltage applied to the drive circuit or the voltage provided by the power supply capacitor used for the drive circuit, but rather means a voltage value associated with the components of the drive circuit and suitable for driving the power semiconductor switch. For example, the supply voltage of the drive circuit may be between a minimum supply voltage associated with the components and a maximum supply voltage associated with the components of the drive circuit, or a predetermined voltage value associated with the components, and in particular, may be a voltage value appropriately selected according to the power semiconductor switch used to power the drive circuit.

[0048] It is also advantageous to use the power electronic equipment described in this application to perform the method.

[0049] This enables the supply of voltage to the drive circuit of at least the first power semiconductor switch in an energy-efficient manner during device startup and operation.

[0050] Other advantageous designs and benefits of the invention are described with reference to the accompanying drawings, in which like reference numerals denote functionally like components.

[0051] In the attached diagram:

[0052] Figure 1 schematically illustrates a boost converter according to the prior art.

[0053] Figure 2 schematically illustrates a buck converter according to the prior art.

[0054] Figure 3 schematically illustrates a half-bridge device according to the prior art.

[0055] Figure 4 schematically illustrates an inverter according to the prior art.

[0056] Figure 5 A boost converter according to a first embodiment of the present invention is schematically shown.

[0057] Figure 6 The half-bridge device according to a second embodiment of the present invention is illustrated schematically.

[0058] Figure 7 The half-bridge device according to a third embodiment of the present invention is illustrated schematically.

[0059] Figure 8A flowchart of a method according to a fourth embodiment of the present invention is shown.

[0060] Figure 1 schematically illustrates a power electronic device 1a according to the prior art, which is a converter 1b in the form of a boost converter 1, wherein details such as the housing of the boost converter 1 are not shown for clarity. A DC voltage generator 3, providing a DC voltage, is connected to the input terminal 2 of the boost converter 1. The boost converter 1 includes a choke 4, a diode 5, and a power semiconductor switch 6. To convert the DC voltage applied to the input terminal 2 into a higher DC voltage to be provided at the output terminal 7, the power semiconductor switch 6 is driven by a drive circuit (not shown) and switched accordingly, thereby generating an electrical flow in the direction of arrow 8.

[0061] Figure 2 schematically illustrates a converter in the form of a buck converter 9 according to the prior art. A DC voltage source 10 is connected to the input terminal 2 of the buck converter. The buck converter 9 includes a power semiconductor switch 6, a diode 5, and a choke 4. In order to convert the DC voltage applied to the input terminal 2 into a lower DC voltage to be provided at the output terminal 7, the power semiconductor switch 6 is driven by a drive circuit (not shown) and switched accordingly, thereby generating an electrical flow in the direction of arrow 11.

[0062] Figure 3 schematically illustrates a converter in the form of a half-bridge device 14 according to the prior art. The DC voltage can be bidirectionally set by means of the half-bridge device 14, enabling power flow in both directions of the bidirectional arrows 15. For this reason, the names of the input terminal 2 and the output terminal 7 of the converter in the figure are arbitrarily chosen. A DC voltage source 16 is connected to the input terminal 2; this DC voltage source can be, for example, a battery that can operate as both a DC voltage source and a load. A DC voltage source 18 is connected to the output terminal 7; this DC voltage source can be, for example, an intermediate loop of an inverter, which can be connected to a solar panel (not shown) on the DC side and to an AC grid (not shown) on the AC side. To set the DC voltage, the half-bridge device 14 includes a half-bridge 20 extending from a third connection point 21 to a fourth connection point 22 and a choke 25. The half-bridge 20 includes a series circuit consisting of a high-side power semiconductor switch 23 and a low-side power semiconductor switch 24. The high-side power semiconductor switch 23 includes a diode 26, and the low-side power semiconductor switch 24 includes a diode 27. In order to set the DC voltage, the two power semiconductor switches of the half-bridge 20 are driven by a drive circuit (not shown) at their control terminals, so that an electrical flow is generated in one of the two directions of the bidirectional arrow 15 as needed.

[0063] Figure 4 schematically illustrates an inverter 29 according to the prior art. Inverter 29 can convert DC voltage to AC voltage and vice versa, enabling power flow in the direction of bidirectional arrow 15. For this reason, the names of the input terminal 2 and output terminal 7 of the inverter in the figure are arbitrarily chosen. Inverter 29 includes an intermediate loop 28 having a first intermediate loop pole 30 and a second intermediate loop pole 31, which are connected to each other via an intermediate loop capacitor 32. Inverter 29 includes two half-bridges 33 and 34 extending between a third connection point 21 or 35 connected to the first intermediate loop pole 30 and a fourth connection point 22 or 36 connected to the second intermediate loop pole 31. Starting from the third connection point 21 or 35, each half-bridge includes a series circuit consisting of a high-side power semiconductor switch 37 or 38, a branch point 39 or 40, and a low-side power semiconductor switch 41 or 42. Choke 44 is connected downstream of branch point 39 in the direction of output terminal 7. DC voltage generator 45 is connected to input terminal 2 of inverter 29, and AC voltage grid 46 is connected to output terminal 7 of inverter 29. To set the voltage, drive circuitry (not shown) for driving and switching power semiconductor switches is arranged such that power flow can be achieved in both directions of bidirectional arrow 15 as needed.

[0064] Figure 5 A converter in the form of a boost converter 48 according to a first embodiment of the present invention is illustrated schematically. To drive a first power semiconductor switch 6a, a drive circuit 49 is connected to the control input terminal 51 of the power semiconductor switch 6a. The drive circuit 49 is integrated with a clock generator 50 in a single component. To supply voltage to the drive circuit 49, an auxiliary circuit device 52 is included, comprising a power supply capacitor 53, an auxiliary capacitor 54, a normally off auxiliary semiconductor switch 55, a diode 56, and a bootstrap diode 57. The auxiliary semiconductor switch 55 is connected to the reference potential terminal 59 of the first power semiconductor switch 6a via a first connection point 58 and is integrated into the basic circuitry of the boost converter 48. Starting from the first connection point 58, a series circuit including the diode 56, a second connection point 60, and the auxiliary capacitor 54 is arranged in parallel with the auxiliary semiconductor switch 55. In order to supply voltage to the drive circuit 49, the drive circuit is connected to the power supply capacitor 53, which is electrically connected to the second connection point 60 via the bootstrap diode 57 through the first terminal 61, and electrically connected to the reference potential terminal 59 via the second terminal 62.

[0065] Furthermore, to drive the auxiliary semiconductor switch 55, the auxiliary circuit device 52 includes a drive circuit 64, which is designed as a comparator circuit 65. This comparator circuit is connected in parallel with the auxiliary capacitor 54 via two power supply terminals. Additionally, a series circuit consisting of a Zener diode 66 in the cutoff direction, an eighth connection point 67, and a resistor 68 is connected in parallel with the auxiliary capacitor 54. The non-inverting input 69 of the comparator circuit 65 is connected to the eighth connection point 67, while the inverting input (not shown) of the comparator circuit 65 is connected to a reference potential (not shown).

[0066] During the operation and startup of the boost converter 48, its necessary components (e.g., drive circuit 49) require electrical power. For example, during startup, a DC voltage, provided by, for example, a DC generator (not shown), can be applied at least between the first terminal 2a and the second terminal 2b of the input 2 of the boost converter 48. Therefore, during startup, a DC voltage is applied between the reference potential terminal 59 of the first power semiconductor switch 6a and another main terminal 70, causing a leakage current through the first power semiconductor switch 6a, such that when the auxiliary semiconductor switch 55 is off, the current flowing through the first power semiconductor switch 6a charges the auxiliary capacitor 54. If the charge on the auxiliary capacitor 54 exceeds a first threshold, the comparator circuit 65 provides a control signal at the control input of the auxiliary semiconductor switch 55 to turn the switch on, such that when the auxiliary semiconductor switch 55 is on and the auxiliary capacitor 54 is at least partially charged, the power supply capacitor 53 is charged by the auxiliary capacitor 54 via the bootstrap diode 57. Here, the charge of the auxiliary capacitor drops below the second threshold, so the comparator circuit no longer provides a control signal at the control input of the auxiliary semiconductor switch 55, and the auxiliary semiconductor switch 55 switches back to the off state, and the auxiliary capacitor is recharged. During the operation of the boost converter 48, operating current flows through the first power semiconductor switch 6a, supplying power to the power supply capacitor 53 through multiple repetitive charging processes to power the drive circuit 49 during operation. To shorten the startup time, a startup resistor 63 may be optionally arranged, which electrically connects the first terminal 2a of the input to the first terminal 61 of the power supply capacitor 53.

[0067] Figure 6 A schematic diagram of a half-bridge device 72 according to a second embodiment of the present invention is shown. The following will mainly discuss... Figure 6The difference between the half-bridge device 72 shown in Figure 72 and the prior art half-bridge device 14 shown in Figure 3 is that the half-bridge 20a of the half-bridge device 72, extending between the third connection point 21 and the fourth connection point 22, also includes a series circuit consisting of a high-side power semiconductor switch 23a, a branch point 39, and a low-side power semiconductor switch 24a, starting from the third connection point 21. In the illustrated embodiment, these two power semiconductor switches each have an integrated body diode, and an auxiliary semiconductor switch 55 is integrated into the half-bridge 20a. To power the drive circuit 49 of the low-side power semiconductor switch 24a, the low-side power semiconductor switch is designed as a first power semiconductor switch, thereby supplying voltage to the drive circuit 49 for driving the low-side power semiconductor switch 24a by means of an auxiliary circuit device 52 including the auxiliary semiconductor switch 55. Regarding the auxiliary circuit device 52, see reference... Figure 5 The accompanying drawings illustrate this. To drive the high-voltage side power semiconductor switch 23a, the half-bridge device 72 has a drive circuit 73, which is electrically connected to a supply capacitor 74 to supply voltage. To charge the supply capacitor 74 in order to supply voltage to the drive circuit 73 driving the high-voltage side power semiconductor switch 23a, the supply capacitor is electrically connected via terminal 75 to the reference potential terminal 59 of the high-voltage side power semiconductor switch 23a, and via another terminal 76 through another bootstrap diode 77 to the first terminal 61 of the supply capacitor 53 included in the auxiliary circuit device 52. Therefore, in the illustrated embodiment, the drive circuit 73 for driving the high-voltage side power semiconductor switch 23a can also be supplied with electrical power in an energy-efficient manner during the operation of the half-bridge device 72.

[0068] Figure 7 A schematic diagram illustrates a half-bridge device 78 according to a third embodiment of the present invention. Figure 6 The difference in the embodiment lies in showing an alternative solution for supplying voltage to the drive circuit of the high-voltage side power semiconductor switch 23a. For this purpose, the high-voltage side power semiconductor switch 23a and the low-voltage side power semiconductor switch 24a are each designed as first power semiconductor switches. Therefore, the two drive circuits 49a and 49b used to drive the high-voltage side power semiconductor switch 23a and the low-voltage side power semiconductor switch 24a are supplied with voltage via their own auxiliary circuit devices 52a and 52b, respectively. Thus, this alternative embodiment can also supply voltage to the drive circuits driving these two power semiconductor switches in an energy-efficient manner for the startup and operation of the half-bridge device 78. Figure 6 and Figure 7 The drive circuit supply voltage can also be transferred to power electronic devices with more than one half-bridge, such as in single-phase or three-phase inverters with inverter bridges of appropriate design.

[0069] Figure 8 A flowchart of a method for supplying voltage to a drive circuit of a power semiconductor switch according to a fourth embodiment of the present invention is shown. In this method, firstly, in a preparation step VVS for startup, a voltage is applied between a reference potential terminal of the power semiconductor switch and another main terminal of the power semiconductor switch. In a first method step VS1, during the normally closed auxiliary switch's off-state, an auxiliary capacitor is charged by means of at least a portion of the current flowing through the power semiconductor switch. In a second method step VS2, when a first threshold value exceeding the charging voltage of the auxiliary capacitor is reached, the auxiliary switch is turned on, and at least a portion of the charge from the auxiliary capacitor is released to a supply capacitor for supplying voltage to the drive circuit. In a third method step VS3, when the charging voltage of the auxiliary capacitor is lower than a smaller second threshold value, the auxiliary switch is again switched to the off-state. Electrical power is supplied to the supply capacitor by repeatedly performing these three steps VS1-VS3 to supply power to the drive circuit during operation of the power semiconductor switch.

[0070] Reference tag list

[0071]

[0072]

[0073] .

Claims

1. A power electronic device (1a) comprising a first power semiconductor switch (6a), a drive circuit (49, 49a, 49b) for driving the first power semiconductor switch (6a), and electrical auxiliary circuit devices (52, 52a, 52b) for supplying voltage to the drive circuit (49, 49a, 49b), wherein the auxiliary circuit devices (52, 52a, 52b) include a power supply capacitor (53, 53a, 53b) and an auxiliary capacitor (54), a normally closed auxiliary semiconductor switch (55, 55a, 55b), a diode (56), and a bootstrap diode (57), wherein The auxiliary semiconductor switches (55, 55a, 55b) are connected to the reference potential terminal (59) of the first power semiconductor switch (6a) via a first connection point (58). Starting from the first connection point (58), the series circuit of the diode (56), the second connection point (60), and the auxiliary capacitor (54) is arranged in parallel with the auxiliary semiconductor switches (55, 55a, 55b), such that when the auxiliary semiconductor switches (55, 55a, 55b) are turned off, the auxiliary capacitor (54) is charged by the current flowing through the first power semiconductor switch (6a). The drive circuits (49, 49a, 49b) are connected to the power supply capacitors (53, 53a, 53b) to supply voltage to the drive circuits, and The power supply capacitors (53, 53a, 53b) are electrically connected to the second connection point (60) via the bootstrap diode (57) through a first terminal (61), and electrically connected to the reference potential terminal (59) via a second terminal (62), such that when the auxiliary semiconductor switch (55, 55a, 55b) is turned on and the auxiliary capacitor (54) is at least partially charged, the power supply capacitors (53, 53a, 53b) are charged by the auxiliary capacitor (54) via the bootstrap diode (57), wherein, The auxiliary circuit devices (52, 52a, 52b) include a drive circuit (64) designed and configured to provide a control signal for switching the auxiliary semiconductor switches (55, 55a, 55b) at the control input of the auxiliary semiconductor switches (55, 55a, 55b) based on the charging voltage of the auxiliary capacitor (54).

2. The power electronic device (1a) according to claim 1, wherein, The drive circuit (64) is designed and configured to provide a control signal at the control input of the auxiliary semiconductor switches (55, 55a, 55b) to turn on the auxiliary semiconductor switches (55, 55a, 55b) when the charging voltage of the auxiliary capacitor (54) exceeds a first threshold, and to provide a control signal at the control input of the auxiliary semiconductor switches (55, 55a, 55b) to turn off the auxiliary semiconductor switches (55, 55a, 55b) when the charging voltage of the auxiliary capacitor (54) is lower than a second threshold less than the first threshold, wherein the first threshold corresponds at least to the amplitude of the supply voltage of the drive circuit (49, 49a, 49b).

3. The power electronic device (1a) according to claim 1, wherein, The driving circuit (64) is a two-point regulator, or a monostable trigger, or a PWM regulator or a frequency regulator.

4. The power electronic device (1a) according to claim 1, wherein, The drive circuit (64) is designed and configured and electrically connected to the auxiliary capacitor (54) in such a way that the drive circuit (64) is supplied with voltage by means of the auxiliary capacitor (54).

5. The power electronic device (1a) according to claim 1, wherein, The auxiliary semiconductor switches (55, 55a, 55b) have the same polarity as the first power semiconductor switch (6a).

6. The power electronic device (1a) according to claim 1, wherein, The first power semiconductor switch (6a) is designed to be normally closed, and has leakage current when a voltage is applied between the reference potential terminal (59) of the first power semiconductor switch (6a) and another main terminal (70) in the closed switching state.

7. The power electronic device (1a) according to claim 1, wherein, The auxiliary circuit devices (52, 52a, 52b) are dedicated to supplying power to at least one drive circuit (49, 49a, 49b, 73).

8. The power electronic device (1a) according to claim 1, wherein, The drive circuits (49, 49a, 49b) are designed to be integrated with a clock generator (50), wherein the clock generator (50) is designed to generate pulse patterns of control signals provided by the drive circuits (49, 49a, 49b).

9. The power electronic device (1a) according to claim 1, wherein, The power electronic device (1a) is a converter (1b).

10. The power electronic device (1a) according to claim 3, wherein, The two-point regulator is a comparator circuit (65).

11. The power electronic device (1a) according to claim 7, wherein, The auxiliary semiconductor switches (55, 55a, 55b) are dedicated to powering at least one drive circuit (49, 49a, 49b, 73).

12. The power electronic device (1a) according to any one of claims 1-11, wherein, The system includes a half-bridge (20a, 20b) that, starting from a third connection point (21, 35), comprises a series circuit consisting of a high-voltage side power semiconductor switch (23a), a branch point (39), a low-voltage side power semiconductor switch (24a), and a fourth connection point (22, 36), wherein the first power semiconductor switch (6a) is the low-voltage side power semiconductor switch (24a).

13. The power electronic device (1a) according to claim 12, wherein, The power electronic device (1a) is a DC / DC converter or inverter (29).

14. The power electronic device (1a) according to claim 12, wherein, Includes an intermediate circuit (28) having an electrical connection that connects the third connection point (21, 35) to the fourth connection point (22, 36) via one or more intermediate circuit capacitors connected in series or in parallel.

15. The power electronic device (1a) according to claim 12, wherein, For the high-voltage side power semiconductor switch (23a) and the low-voltage side power semiconductor switch (24a), each includes a drive circuit (49a, 49b) for driving the corresponding power semiconductor switch, and each includes its own electrical auxiliary circuit device (52a, 52b) for supplying voltage to the drive circuit (49a, 49b). Therefore, both the high-voltage side power semiconductor switch (23a) and the low-voltage side power semiconductor switch (24a) are designed as first power semiconductor switches (6a).

16. The power electronic device (1a) according to claim 12, wherein, The device includes a drive circuit (73) to drive the high-voltage side power semiconductor switch (23a) and a supply capacitor (74) to supply voltage to the drive circuit (73). The supply capacitor is electrically connected to the reference potential terminal (59) of the high-voltage side power semiconductor switch (23a) via a terminal (75) and to the first terminal (61) of the supply capacitor (53) included in the auxiliary circuit device (52) via another bootstrap diode (77) via another terminal (76) to supply voltage to the drive circuit (49) that drives the low-voltage side power semiconductor switch (24a).

17. The power electronic device (1a) according to claim 12, wherein, The high-voltage side power semiconductor switch (23a) and the low-voltage side power semiconductor switch (24a) are normally off and have leakage current when a voltage is applied between their reference potential terminal (59) and their other main terminal (70) in the off switching state.

18. A method for supplying voltage to a drive circuit (49) of a power semiconductor switch, wherein a power supply capacitor (53, 53a, 53b) supplies voltage to the drive circuit (49, 49a, 49b), wherein, in order to charge the power supply capacitor (53, 53a, 53b), during a switching state in which a normally closed auxiliary switch is off, an auxiliary capacitor (54) is charged by means of a current flowing through the power semiconductor switch, and when the normally closed auxiliary switch is turned on, the auxiliary capacitor (54) charges the power supply capacitor (53), wherein the auxiliary switch is turned on based on the charging voltage of the auxiliary capacitor (54).

19. The method according to claim 18, wherein, The normally closed auxiliary switch is connected to the reference potential terminal (59) of the power semiconductor, such that in the first method step (VS1), when the auxiliary switch is off, at least a portion of the current flowing through the power semiconductor switch is diverted to the auxiliary capacitor and at least partially charged thereon, wherein in the second method step (VS2), the auxiliary switch is turned on and at least a portion of the charge of the auxiliary capacitor is released to the power supply capacitor, and in the third method step (VS3), the auxiliary switch is switched back to the off state, thereby supplying electrical power to the power supply capacitor by repeating the three method steps multiple times, so as to supply power to the drive circuit in operation.

20. The method according to claim 18, wherein, When the charging voltage of the auxiliary capacitor (54) exceeds the first threshold, the auxiliary switch is turned on, and when the charging voltage of the auxiliary capacitor (54) is lower than the second threshold, the auxiliary switch is turned off, wherein the second threshold is less than the first threshold.

21. The method according to any one of claims 18 to 20, wherein, The method is performed using a power electronic device (1a) according to any one of claims 1 to 17.

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