Circuit components and rectifier circuits for electric motors

Abstract

The present invention relates to a circuit component, which has a switching transistor with a first load connection, a second load connection and a control connection and a control circuit, wherein the control circuit also has a control transistor with a first load connection, a second load connection and a control connection, a diode unit, a first resistor element, a second resistor element, a third resistor element and a potential unit, wherein there is a signal path between the second load connection of the switching transistor and the control connection of the control transistor, the signal path has a diode unit and a first resistor element, between the first load connection of the switching transistor and the control connection of the switching transistor; between the second load connection of the control transistor and the first load connection of the switching transistor; between the control connection of the control transistor and the potential unit, the signal path has a third resistor element, and between the first load connection of the control transistor and the potential unit, the signal path has a second resistor element.

Description

Technical Field

[0001] The invention relates to a circuit assembly having a switching transistor and a control circuit for controlling the switching transistor, and to a rectifier circuit for an electric machine having such a circuit assembly. Background Art

[0002] In modern vehicles with internal combustion engines, electric machines are used in the form of generators, which are driven by the rotation of the crankshaft and provide electrical energy for supplying the vehicle with electricity and charging the vehicle battery. In order to convert the AC voltage generated by such a generator into a DC voltage, a rectifier circuit is used, which is usually designed as a bridge rectifier and has a high-side rectifier element and a low-side rectifier element for each phase of the generator.

[0003] For example, DE 102007060219 A1 shows such a bridge rectifier with silicon PN diodes as such high-side rectifier elements and low-side rectifier elements. In addition, DE 102007060219 A1 discloses the use of a circuit arrangement having a MOSFET with an integrated reverse diode between the cathode connection and the anode connection and a control circuit for the MOSFET as a rectifier element instead of using such a diode, wherein the control circuit comprises a differential amplifier consisting of a transistor and a resistor. Summary of the invention

[0004] Against this background, a circuit arrangement and a rectifier circuit are proposed. Advantageous embodiments are the subject of preferred embodiments and the following description.

[0005] The circuit component has a switching transistor and a control circuit for controlling the switching transistor, the switching transistor having a first load connection, a second load connection and a control connection, wherein the control circuit also has a control transistor, in particular a bipolar transistor, the control transistor having a first load connection, a second load connection and a control connection, the control circuit also has a diode unit, a first resistor element, a second resistor element, a third resistor element and a potential unit, wherein a corresponding signal path exists between: - the second load connection of the switching transistor and the control connection of the control transistor, the signal path having a diode unit and a first resistor element; - between the first load connection of the control transistor and the control connection of the switching transistor; - between the second load connection of the control transistor and the first load connection of the switching transistor; - between the control connection of the control transistor and the potential unit, the signal path having a third resistor element, and - between the first load connection of the control transistor and the potential unit, the signal path having a second resistor element.

[0006] A rectifier circuit for an electric machine is used for rectifying a phase voltage of the electric machine and has two switches for each phase connection of the electric machine, wherein at least one of the switches is designed as the circuit component.

[0007] As described above, the circuit arrangement has a switching transistor with a first load connection, a second load connection and a control connection, and a control circuit for controlling the switching transistor. In particular, the switching transistor is designed as a MOSFET, wherein in this case the first load connection is in particular designed as a source connection, the second load connection is in particular designed as a drain connection, and the control connection is in particular designed as a gate connection. It is also conceivable that the switching transistor is designed, for example, as a bipolar transistor, for example an IGBT.

[0008] In particular, the control circuit is configured to control the switching transistor such that the switching transistor is conductive in a first direction from the first load connection to the second load connection and is blocked in a second direction from the second load connection to the first load connection. In addition to the switching transistor, the control circuit also has a control transistor with a first load connection, a second load connection and a control connection, as well as a diode unit, a first resistor element, a second resistor element, a third resistor element and a potential unit.

[0009] In particular, the control transistor is designed as a bipolar transistor, wherein the first load connection is designed as a collector of the bipolar transistor, the second load connection is designed as an emitter of the bipolar transistor, and the control connection is designed as a base of the bipolar transistor.

[0010] A diode cell has, like a single diode, in particular a cathode connection and an anode connection and conducts current only from the anode connection to the cathode connection. For example, a diode cell can be designed as a single diode or as a circuit that simulates these characteristics of a single diode.

[0011] The first, second and third resistance element can each be expediently designed as an ohmic resistor.

[0012] The potential unit serves in particular to supply the circuit component with a supply voltage and can comprise, for example, a potential connection, a battery and / or a capacitor.

[0013] When referring to connections below, this refers to signal paths that exist between the mentioned elements. These signal paths may also have other mentioned or unmentioned elements.

[0014] A second load connection of the switching transistor, in particular a drain load connection of a MOSFET, is connected in a signal path to the diode unit, in particular to the cathode connection of the diode unit, then to the first resistor element and then to the control connection of the control transistor, in particular to the base of the bipolar transistor.

[0015] A first load connection of the control transistor, in particular the collector of a bipolar transistor, is connected in a signal path to a control connection of the switching transistor, in particular to a gate load connection of a MOSFET.

[0016] A second load connection of the control transistor, in particular an emitter of a bipolar transistor, is connected in a signal path to a first load connection of the switching transistor, in particular to a source connection of a MOSFET.

[0017] A control connection of the control transistor, in particular a base of the bipolar transistor, is connected in the signal path to a third resistor element and a potential unit. A first load connection of the control transistor, in particular a collector of the bipolar transistor, is connected in the signal path to a second resistor element and a potential unit.

[0018] The circuit arrangement advantageously allows the switching transistor to be operated in such a way that it conducts in a first direction from the first load connection to the second load connection and blocks in a second direction from the second load connection to the first load connection. Thus, the switching transistor of the circuit arrangement can be operated in particular like a diode, wherein the first load connection of the switching transistor corresponds to the anode of the diode and the second load connection corresponds to the cathode. Advantageously, the control circuit is used to control the switching transistor in such a way that this diode characteristic is obtained.

[0019] Compared to semiconductor switches, diodes have a significant voltage drop in the flow direction, so that when rectifying high currents, corresponding power loss in the form of heat occurs, which leads to the need for expensive cooling elements. The present circuit assembly makes it possible to simulate the characteristics of a diode using a switching transistor, which has a much smaller power loss than a diode. Therefore, the circuit assembly is suitably suitable for use in a circuit to replace a diode, thereby reducing power loss and the need for cooling elements. In particular, the circuit assembly can be constructed as an integrated circuit and thus as a single component or element with two connections, an anode connection and a cathode connection, the anode connection being connected to a first load connection of the switching transistor, and the cathode connection being connected to a second load connection of the switching transistor. Preferably, the control connection is only connected internally, and therefore the correct voltage value is automatically obtained according to the voltage applied to the anode connection and the cathode connection.

[0020] In particular, the control circuit and thus the circuit arrangement itself generates the control signal or control voltage for the switching transistor required for the diode characteristic. This control signal or this control voltage is expediently provided at a first load connection of the control transistor, which is connected to the control connection of the switching transistor. In particular, by special dimensioning and designing the individual elements of the control circuit, a threshold value can be predetermined, starting from which the characteristic of the control transistor changes, in particular starting from which the control transistor is no longer conductive. In particular, the threshold value is also predetermined when the switching transistor changes between conductive mode and non-conductive mode.

[0021] In particular, a switching transistor designed as a MOSFET should expediently conduct current only when current flows from the source to the drain and should be blocked in the opposite case. A prerequisite for this is, in particular, that the potential at the source terminal of the MOSFET is higher than the potential at its drain terminal. The associated voltage drop from the source to the drain is expediently monitored by the control circuit. If this voltage drop exceeds a threshold value that can be predefined in particular, a corresponding control signal is generated for the gate terminal of the MOSFET in order to expediently increase the conduction rate of the MOSFET as the current rises and to suppress an increase in the power loss at the switching transistor.

[0022] According to a particularly advantageous embodiment, the switching transistor can also be controlled by an external signal, and in this case, in particular, it is externally predetermined whether the switching transistor should be permanently turned on or permanently turned off. Advantageously, for this purpose, the control terminal of the control transistor, in particular the base of the bipolar transistor, is also connected to a first signal terminal for receiving a first control signal. Alternatively or additionally, for this purpose, the second load terminal of the control transistor, in particular the collector of the bipolar transistor, is also connected to a second signal terminal for receiving a second control signal.

[0023] These control signals can be, in particular, external signals for actuating the switching transistor, for example from an external or superordinate control unit. The switching transistor can be switched on in particular by means of such a first control signal, and can be switched off in particular by means of such a second control signal. In particular, the actuation signal generated in the actuation circuit, which actuation signal is generated in particular by an analysis of the voltage drop across the switching transistor, is overwritten by these external control signals.

[0024] Preferably, the potential unit is designed as a potential terminal for connecting the circuit component to a voltage source. The external voltage source can in particular provide the necessary voltage in order to switch the switching transistor to conduction with a corresponding control voltage. In particular, a sufficiently high voltage can be provided by the external voltage source so that a higher potential can be applied to the gate terminal of the switching transistor designed as a MOSFET than to its source terminal in order to switch the switching transistor designed as a MOSFET to conduction.

[0025] Alternatively or additionally, the potential unit is preferably designed as a capacitor that is connected to the first load connection of the switching transistor and is preferably connected to the second load connection of the switching transistor via another resistor element and a diode. With the help of such a capacitor, the voltage itself required for controlling the switching transistor can be generated in the circuit component. The capacitor, resistor element and diode are particularly used as a so-called bootstrap circuit (Bootstrap-Schaltung) or a charge pump, in which energy can be appropriately guided to the capacitor through the diode and can be stored there. Here, the resistor element limits the flowing current and protects the diode from damage caused by large currents. This charging process occurs especially when a higher potential is applied to the second load connection of the switching transistor than on its first load connection and therefore especially prevents the current flow through the switching transistor. For this purpose, the second load connection of the switching transistor is particularly connected to the anode of the diode, and the cathode of the diode is connected to the capacitor through the resistor element.

[0026] Preferably, the control connection of the control transistor is connected to the first load connection of the control transistor via a capacitor in the signal path. Possible oscillation characteristics of the control transistor can be suppressed by the capacitor in particular. If the capacitance required for this is small enough, the oscillation characteristics can also be suppressed in particular by a suitable circuit board layout.

[0027] Advantageously, the first load connection of the control transistor is connected to the control connection of the switching transistor via an amplifier circuit in a signal path. In particular, the amplifier circuit is used to amplify the control signal provided at the first load connection of the control transistor for the control connection of the switching transistor. If a high-frequency-changing voltage is applied to the first load connection and the second load connection of the switching transistor, the control connection must be actuated in particular correspondingly quickly. By means of the amplifier circuit, the control connection of the switching transistor can now be supplied with a control signal with a high current, so that charging and discharging can be performed sufficiently quickly at the control connection of the switching transistor.

[0028] Advantageously, the amplifier circuit has two complementary transistors (pnp and npn, or n-channel and p-channel), each having a first load connection, a second load connection and a control connection. The first load connection of the control transistor is preferably connected together to the control connection of the two complementary transistors. The second connection of the two complementary transistors is preferably connected together to the control connection of the switching transistor. The amplifier circuit is therefore configured in particular as a so-called push-pull or push-pull stage. The complementary switching transistor has in particular a significantly smaller output resistance than in the previous stage of the circuit assembly, so that a higher current can be directed to the control connection of the switching transistor. Preferably, the two complementary transistors are each configured as a bipolar transistor, wherein the first load connection of these bipolar transistors is each configured as a collector, the second load connection is each configured as an emitter and the control connection is each configured as a base.

[0029] Preferably, the diode unit is designed as a diode and / or a transistor, in particular a bipolar transistor, whose first load connection and its control connection are connected to one another. In particular, the base and collector of the transistor, which is preferably designed as a bipolar transistor, are connected to one another. Compared to a single diode, a higher stability with respect to temperature fluctuations and aging effects can be achieved with a transistor connected in this way, in particular, if it is designed in the same manner as the control transistor, preferably in the same integrated circuit.

[0030] In summary, therefore, with the aid of the preferred embodiment of the circuit arrangement according to the invention, a diode characteristic can be simulated with the aid of a switching transistor and a control circuit, wherein a much lower power loss occurs than with a conventional diode. Furthermore, an external signal can be predefined, by means of which it can be externally predefined whether the switching transistor should be permanently blocked or conducting. Due to these properties, the circuit arrangement is particularly advantageously suitable for use in a (synchronous) rectifier for an electric machine.

[0031] Therefore, the rectifier circuit for an electric machine according to the invention has at least one preferred embodiment of the circuit assembly according to the invention. The rectifier circuit is designed to rectify the phase voltage of the electric machine and has two switches for each phase connection of the electric machine, preferably one high-side switch and one low-side switch. At least one of these switches is designed as a preferred embodiment of the circuit assembly according to the invention.

[0032] Thus, the circuit assembly can be used in a rectifier circuit like a conventional diode. However, due to the circuit assembly in the rectifier circuit, significantly lower power losses occur compared to conventional diodes, and the need for cooling elements can be significantly reduced. Therefore, each switch is particularly advantageously designed as a preferred embodiment of the circuit assembly according to the invention. Thus, for example, four circuit assemblies are used for a single-phase motor and for example, six circuit assemblies are used for a three-phase motor.

[0033] Rectifier circuits are particularly suitable for use in vehicles, where the motor is, for example, a three-phase AC motor and is coupled to the crankshaft of the vehicle's internal combustion engine. The AC voltage generated by the motor can be rectified by the rectifier circuit with low losses and used to supply the vehicle with electrical energy and to charge the vehicle battery.

[0034] According to a preferred design, the rectifier circuit also has a short-circuit unit. The short-circuit unit is particularly configured to control the rectifier circuit or the individual switches of the rectifier circuit so that a short circuit of the phase of the motor is generated. In order to generate this short circuit, the switch of the rectifier circuit is appropriately operated by the short-circuit unit so that the high-side switch is cut off and the low-side switch is fully turned on. This short circuit can be appropriately used for voltage regulation, or in the case of a fully charged battery, for not further charging the battery and thus overloading it, wherein the battery is connected to the output end of the rectifier circuit. Through the fully turned-on low-side switch, the phase connection of the motor is appropriately short-circuited. The high-side switch is appropriately decoupled from the motor to the battery. Therefore, the high-side switch is not short-circuited and at the same time another current flow from the motor to the battery is blocked and overcharging is avoided. The battery pack can be discharged, for example, through the on-board power supply in this case. Once there is no other danger of overcharging, the short-circuit state is appropriately terminated.

[0035] Advantageously, the short-circuit unit comprises a signal input terminal for receiving a control signal. In particular, an external control signal or a short-circuit signal for generating a short circuit can be received via the signal input terminal. For example, such an external control signal can be output by an external controller or an internal monitoring unit.

[0036] Furthermore, the short-circuit unit advantageously comprises at least two switching transistors, each having a first load connection, a second load connection and a control connection. In particular, the switching transistors can each be designed as a MOSFET, wherein the first load connection is each designed as a source connection, the second load connection is each designed as a drain connection and the control connection is each designed as a gate connection.

[0037] The first load connection of each of the at least two switching transistors is preferably connected to a potential connection, in particular to ground, in a signal path. The second load connection of each of the at least two switching transistors is preferably connected to at least one switch of the rectifier circuit in a signal path. The control connection of each of the at least two switching transistors is preferably connected to a signal input in a signal path, in particular via a resistor element.

[0038] In particular, each switch of the rectifier circuit is therefore connected in the signal path to one of the switching transistors of the short-circuit unit. If the short-circuit unit receives a corresponding short-circuit signal at the signal input, the short-circuit signal is transmitted to the individual switches by means of the switching transistors in order to actuate the switches to produce a short circuit of the motor.

[0039] According to an advantageous embodiment, the short-circuit unit has a switching transistor for each switch of the rectifier circuit. The second load connection of each of these switching transistors is preferably connected to the switch of the rectifier circuit in a signal path. Therefore, for each switch, the short-circuit signal applied to the signal input of the short-circuit unit is transmitted individually by means of the assigned switching transistor.

[0040] Alternatively, the short-circuit unit has exactly two switching transistors according to an advantageous design. One of the two switching transistors is particularly configured for a high-side switch, and the other switching transistor is particularly configured for a low-side switch. The second load connection of the first switching transistor of the two switching transistors is preferably connected to a first number of switches of the rectifier circuit via a diode in the signal path, advantageously connected to all high-side switches. The second load connection of the second switching transistor of the two switching transistors is preferably connected to a second number of switches of the rectifier circuit via a diode in the signal path, advantageously connected to all low-side switches.

[0041] According to a particularly advantageous design, each switch of the rectifier circuit is designed as a circuit component with a first signal connection and / or with a second signal connection. The second load connection of each switching transistor of at least two switching transistors of the short-circuit unit is advantageously connected to the first signal connection of one of the switches of the rectifier circuit or to the second signal connection in the signal path. As described above, the first or second signal connection is used to predetermine whether the corresponding switching transistor should be continuously turned on or continuously turned off by an external signal. The circuit component designed in this way is therefore particularly suitable for the rectifier circuit, so as to short-circuit the phase of the motor when necessary. Preferably, the high-side switch can be constructed as a circuit component with a second signal connection, and the low-side switch can preferably be constructed as a circuit component with a first signal connection. The short-circuit unit is suitably connected to the second signal connection of the high-side switch, so that these switches are switched off for short-circuiting. In addition, the short-circuit unit is suitably connected to the first signal connection of the low-side switch, so as to continuously turn on these switches for short-circuiting.

[0042] Advantageously, the rectifier circuit also has a fault protection unit, which has a signal input for receiving a control signal and a signal output, wherein the signal output of the fault protection unit is preferably connected to the signal input of the short-circuit unit. Preferably, the fault protection unit also has a diode, in particular a Zener diode, a resistor and a capacitor. The resistor and the capacitor are preferably connected in series between the potential outputs of the rectifier circuit. The cathode of the diode is preferably connected to the resistor, and the anode of the diode is preferably connected to the signal output. In particular, the fault protection unit is used to determine whether the short circuit of the phase of the motor should be performed when the external controller does not make the determination, for example because the communication line between the short-circuit unit and the controller is faulty. For this purpose, the fault protection unit monitors the output voltage of the rectifier circuit and therefore monitors the battery voltage in particular. When a pre-given threshold is reached, the fault protection unit appropriately triggers the short circuit of the motor. Similarly, when safe operation is ensured again, the fault protection unit can end the short circuit again.

[0043] Further advantages and embodiments of the invention are apparent from the description and the accompanying drawings.

[0044] The invention is illustrated schematically in the drawings on the basis of exemplary embodiments and is described below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figures 1 to 3 A preferred design scheme of the circuit assembly according to the present invention is schematically shown respectively;

[0046] Figure 4 and Figure 5 A preferred embodiment of the rectifier circuit according to the present invention is respectively schematically shown. DETAILED DESCRIPTION

[0047] In the figures, the same reference signs denote identical or structurally identical elements.

[0048] exist Figure 1 A preferred embodiment of the circuit arrangement according to the invention is schematically shown in FIG. 1 as a block diagram consisting of individual functional blocks.

[0049] M1 denotes a switching element 110 in the form of a switching transistor designed as a MOSFET, which has a first load or source connection S, a second load or drain connection D and a control or gate connection G. For controlling the MOSFET M1 , a control circuit is provided which can be divided into four functional blocks 121 to 124 .

[0050] In particular, a current flow through the MOSFET M1 occurs only when the current is to flow from the source to the drain, so that the potential at the source is higher than the potential at the drain. In the opposite case, the MOSFET M1 is driven in blocking mode and the body diode blocks the current flow.

[0051] The first functional block 121 of the control circuit is configured to generate the required supply voltage for all circuit parts. The voltage required for this purpose can be predetermined by an external voltage source via the input terminal V+ or generated by the control circuit itself. Possible solutions for realizing the corresponding supply voltage can be so-called start-up circuits or charge pumps. If the feasible solution of providing a voltage source via the external input terminal V+ is sufficient, the circuit for generating the voltage source can also be omitted.

[0052] The second functional block 122 of the control circuit is provided for detecting the current flow through the switching transistor M1. The MOSFET M1 should only conduct current when the current flows from the source to the drain in the flow direction of the body diode of the MOSFET and should be cut off in the opposite case. The prerequisite for this is that the potential at the source of the MOSFET M1 is higher than the potential at the drain. The voltage drop from the source to the drain associated with this is monitored by a suitable circuit 122. The following voltage is provided at the output of the circuit part, the amplitude of which corresponds to the intensity of the current flow through the switching transistor. In particular, the circuit 122 can perform a corresponding scaling (Skalierung) of this output voltage, so that a fully analyzable signal is provided for the subsequent circuit part.

[0053] The third functional block 123 of the control circuit is provided for generating a control signal for the switching transistor M1 as a function of the detected current flow and, if necessary, of an external control signal. If the voltage drop across the MOSFET M1 exceeds an adjustable threshold value, a corresponding control signal for the gate of the MOSFET M1 is generated. This serves to increase the conduction rate of the MOSFET M1 as the current increases and thereby to counteract the increase in the power loss at the switching transistor M1.

[0054] Preferably, external control signals 123a and 123b can be received and evaluated by the functional block 123. If a corresponding first control signal is applied to the first signal terminal 123a, a control signal for the gate of the MOSFET M1 is generated, which is intended to completely switch on the first signal terminal. If a corresponding second control signal is applied to the second signal terminal 123b, a control signal for the gate of the MOSFET M1 is generated, which completely switches off the second signal terminal. In both cases, the control signals resulting from the current flow analysis are preferably overwritten.

[0055] A fourth functional block 124 may be provided to amplify the switching transistor control signal in order to increase the reaction speed of the circuit. In order to achieve the fast reaction capability of the MOSFET M1, its gate must be charged or discharged with a corresponding current. In order to achieve these currents, the control signal generated in the functional block 123 may be amplified by means of suitable circuits in the functional block 124. One possible implementation is, for example, a so-called push-pull stage. If the power of the control signal generated in the functional block 123 is sufficient, the amplifier stage 124 may also be omitted.

[0056] exist Figure 2 , a preferred embodiment of a circuit arrangement according to the invention is schematically shown in FIG. 1 as a circuit diagram and is denoted by 100 .

[0057] A control circuit for controlling a switching transistor 110 designed as a MOSFET M1 is designated 120. The control circuit 120 has a control transistor Q3 in the form of a bipolar transistor having a first load connection designed as a collector, a second load connection designed as an emitter, and a control connection designed as a base.

[0058] Furthermore, the control circuit 120 has a diode unit D2, a first resistor element R4, a second resistor element R2, a third resistor element R3 and a potential unit. The potential unit comprises a potential connection V+ and a capacitor C1. The capacitor C1 is further part of a charge pump and is connected to the drain connection of the switching transistor M1 via a resistor element R5 and a diode D1. In the example shown, the diode unit is designed as a single diode D2.

[0059] The first load connection or collector of the bipolar transistor Q3 is connected to the control connection or gate connection of the MOSFET M1 via an amplifier circuit in the signal path. The amplifier circuit comprises two complementary transistors in the form of bipolar transistors Q1 and Q2. The third connections or bases of the two complementary bipolar transistors Q1 (npn), Q2 (pnp) form a common input of the amplifier circuit and are connected together to the first load connection and the collector of the control transistor Q3. The second connections or emitters of the two complementary bipolar transistors Q1, Q2 form a common output of the amplifier circuit and are connected together to the control connection or gate connection of the MOSFET M1 in the signal path. In addition, the first load connection or collector of the bipolar transistor Q1 is connected to a further resistor element R1 in the signal path.

[0060] The second load connection or drain connection of the MOSFET M1 is connected to the cathode of the diode unit D2 in the signal path, then to the first resistor element R4, and then to the control connection or base of the bipolar transistor Q3. The control connection or base of the bipolar transistor Q3 is connected to the third resistor element R3 in the signal path, then to the capacitor C1, and then to the first load connection or source connection of the MOSFET M1. In addition, the first load connection or collector of the bipolar transistor Q3 is connected to the second resistor element R2 in the signal path, then to the capacitor C1, and then to the first load connection or source connection of the MOSFET M1. The second load connection or emitter of the bipolar transistor Q3 is connected to the first load connection or source connection of the MOSFET M1 in the signal path. In addition, the control connection, base and first load connection, collector of the bipolar transistor Q3 are connected to each other via the capacitor C2.

[0061] In order to switch on MOSFET M1, a higher potential must be applied to its gate terminal G than to its source terminal S, for which the required voltage can be predefined via input V+ by an external voltage source or generated by control circuit 120 itself. For this purpose, a charge pump consisting of diode D1, resistor element R5 and capacitor C1 is used.

[0062] In particular, at any point in time when the potential at the drain connection D of the MOSFET M1 is higher than the potential at the point V+, energy is conducted to the capacitor C1 via the diode D1 and stored there. The resistor element R5 limits the current flowing there and protects the diode D1 from damage due to high currents. This charging process usually occurs when the potential at the drain connection D of the MOSFET M1 is higher than the potential at its source connection S, so that the current flow through the MOSFET M1 is interrupted.

[0063] If the potential at the source terminal S of the MOSFET M1 now rises, the voltage difference at the two terminals of the capacitor C1 remains, and the potential V+ therefore rises to the same extent as the source potential (lower terminal potential of the capacitor C1). The potential V+ is therefore higher than the source potential and is available for actuating the gate terminal G of the MOSFET M1.

[0064] If an external voltage is applied via the input V+, which external voltage is high enough in any case to be able to apply a correspondingly higher voltage to the gate terminal G of the MOSFET M1 than to its source terminal S, then the charge pump and therefore the diode D1 and the resistor R5 can be omitted. Furthermore, if the voltage applied externally to the input V+ is sufficiently stabilized, the capacitor C1 can also be omitted.

[0065] Figure 2 The control circuit shown in Figure 1 The functional blocks 122 and 123 in FIG. 1 are combined in a common circuit, as explained below. Components R2, R3, R4, D2, C2 and Q3 are used to generate the control signal for the MOSFET gate terminal G. The MOSFET M1 conducts the current only when the current flows from the source to the drain (in the forward direction of the body diode of the MOSFET) and blocks it in the opposite case.

[0066] The prerequisite for this is that the potential at the source terminal S of the MOSFET M1 is higher than the potential at its drain terminal D. The associated voltage drop from source to drain is monitored by the components R2, R3, R4, D2, C2 and Q3. If this voltage drop exceeds a threshold value that can be adjusted by dimensioning the components mentioned, a control signal for the gate G of the MOSFET M1 is generated.

[0067] If there is no voltage drop, the same voltage is applied between the base and the emitter of the bipolar transistor Q3 of the npn type, which voltage is dropped via the resistor element R4 and the diode D2. When the voltage between V+ and the source S of the MOSFET M1 is greater than the necessary activation voltage of the bipolar transistor Q3 (given by the charge pump or an external voltage source in operation), the bipolar transistor Q3 is turned on. This means that the potential UA of the collector of the bipolar transistor Q3, which is used to drive the MOSFET gate G, will be almost at the level of the source potential, so that the MOSFET M1 is not turned on.

[0068] For a negative voltage drop, the voltage between the base and the emitter of the bipolar transistor Q3 corresponds to the voltage drop across the resistor element R4, the diode D2 and the drain-source (positive) of the MOSFET M1. The bipolar transistor Q3 is thus turned on, the potential UA remains at the source level and the MOSFET M1 is thus turned off.

[0069] For a positive voltage drop, the voltage between the base and the emitter of the bipolar transistor Q3 also corresponds to the voltage drop across the resistor element R4, the diode D2 and the drain-source (now negative) of the MOSFET M1. If the voltage drop between the source S and the drain D becomes sufficiently large, the voltage between the base and the emitter of the bipolar transistor Q3 is no longer sufficient to drive the bipolar transistor Q3, so that the bipolar transistor Q3 is cut off. As a result, UA across the resistor element R2 is pulled to the level of V+ and assumes a positive control potential relative to the source connection S of the MOSFET M1, so that the MOSFET M1 becomes conductive and supports the current flow from the source S to the drain D.

[0070] The exact point at which the bipolar transistor Q3 is no longer conducting can be adjusted by dimensioning the resistor element R4. Since a bipolar transistor requires a typical diode voltage drop of about 0.7 V between base and emitter to conduct, and this is given by the diode D2, there is a point between the conducting and the blocked bipolar transistor Q3 when the voltage drop across the resistor element R4 corresponds to the voltage drop between the source S and the drain D of the MOSFET M1. In order to avoid sensitivity of the circuit to small noise-induced currents, the resistor element R4 is in particular selected such that only a clear voltage drop from the source S to the drain D (caused by the current through the body diode of the MOSFET M1) leads to the actuation of the gate G of the MOSFET M1.

[0071] Therefore, the current flow used is not conducted through the body diode of MOSFET M1 until a certain current intensity, before MOSFET M1 itself supports and thus limits the power loss in M1. Capacitor C2 suppresses possible oscillating behavior of control transistor Q3. Typically, the capacitance required for this is so small that a suitable circuit board layout of control circuit 120 is sufficient and C2 can also be omitted.

[0072] In addition to analyzing the voltage drop between drain D and source S of MOSFET M1 for controlling gate G, it is also possible to externally specify by means of an external control signal whether MOSFET M1 is to be completely blocked or switched on.

[0073] For this purpose, a control terminal or base of the bipolar transistor Q3 is connected to a first signal terminal 123a for receiving a first control signal, and a second load terminal or collector of the bipolar transistor Q3 is connected to a second signal terminal 123b for receiving a second control signal.

[0074] If MOSFET M1 is fully turned on, a potential less than or equal to the source potential of MOSFET M1 can be applied to control channel 123a. Therefore, bipolar transistor Q3 is fully turned off and pulls potential UA toward V+ through resistor element R2 as described above, thereby controlling MOSFET M1 through UAV.

[0075] If MOSFET M1 is to be completely turned off, a potential less than or equal to the source potential of MOSFET M1 can be applied to control channel 123b. Since control channel 123b directly predetermines potential UA, UAV also only has the potential applied to source S of MOSFET M1, so that MOSFET M1 is turned off.

[0076] If there are high-frequency-changing voltages at the source S and drain D of the MOSFET M1, the gate G of the MOSFET M1 must be actuated accordingly quickly. Depending on the dimensioning of the resistor element R2, the gate G may be charged too slowly. In this case, an optional amplifier stage can be connected in between. For this purpose, in the example shown, an amplifier circuit is used, which reproduces the actuation signal UA at the output and can drive a higher current at the output, so that the charging and discharging of the gate G occurs very quickly. The components R1, Q1 and Q2 are used for this purpose.

[0077] The npn bipolar transistor Q1 and the pnp bipolar transistor Q2 form a potential UAV at their common emitter output, which is predetermined at their common base input UA. At the same time, they have a significantly smaller output resistance than in the preceding stage of the control circuit 120, so that a higher current can be conducted in the direction of the gate G of the MOSFET M1.

[0078] The resistance element R2 serves in particular to limit the maximum possible current in order to avoid overloading of the control circuit 120 and the associated damage.

[0079] exist Figure 3 1 shows a circuit assembly 100 according to another preferred embodiment. In this case, the diode unit is not designed as a single diode D2, but as a transistor Q4 in the form of an npn bipolar transistor, the collector and base of which are connected to one another. This embodiment of the diode unit can achieve a higher stability against temperature fluctuations and aging effects.

[0080] The bipolar transistor Q4 is of an identical construction to the bipolar transistor Q3. By means of the selected switching, the bipolar transistor Q4 simulates a pure diode characteristic. The voltage drop occurring between the base and the emitter corresponds in particular exactly to the voltage drop of the bipolar transistor Q3 and behaves in particular identically even in the case of temperature fluctuations. The operating point set by the resistor element R4, from which the MOSFET M1 starts to conduct, is therefore even less sensitive to external influences.

[0081] There are such IC components which provide two identical (in particular independently operating) bipolar transistors of the npn type in a housing. If the bipolar transistors Q3 and Q4 are implemented with such an IC, they have in particular the same temperature characteristics and the same temperature in all cases, and possible aging effects generally act on both transistors to the same extent. The operating point of the circuit assembly 100 is therefore almost exclusively dependent on the resistor element R4. With a sufficiently non-critical dimensioning of this resistor element, a stable modification of the circuit element 100 can be achieved, in particular over a wide temperature range and over a long application period.

[0082] Except in Figure 2 and Figure 3In addition to the feasible solution shown in the figure, which discretely constructs the circuit component 100 from individual components, IC solutions with different degrees of integration can also be realized. In the highest integration level, in particular, the entire circuit component can be integrated into a single integrated circuit IC. From this, in particular, the following module is obtained, which has five connections, namely: a source connection S, a drain connection D, a first signal connection 123a, in order to continuously conduct the MOSFET M1 in both current directions, a second signal connection 123b, in order to continuously cut off the MOSFET M1, and a potential connection V+ for predetermining the external supply voltage of the circuit component 100. The connections 123a, 123b and V+ can also be omitted in particular. Therefore, the integrated circuit component 100 only has anode and cathode connections in the form of source and drain connections.

[0083] If MOSFET M1 is operated with high power loss, the control circuit 120 must also cope with the temperatures that occur in this case in the entire integration level. If this is to be avoided, MOSFET M1 and control circuit 120 can also be considered separately and only control circuit 120 can be integrated. This results in an IC with six connections, namely the source of MOSFET M1, the drain of MOSFET M1, the gate of MOSFET M1, 123a, 123b and V+.

[0084] If, in order to provide the supply voltage of the circuit, the charge pump uses a large capacitor C1 to provide a voltage that is as stable as possible, the manufacturing process for integrating the capacitance may reach its limits. In this case, C1 can be not integrated but arranged as a separate component near the corresponding connections (V+ and source) of the IC.

[0085] Thus, the circuit assembly 100 simulates a diode characteristic by means of the switching transistor 110 and the control circuit 120, wherein a much lower power loss occurs than in a conventional diode. In addition, it is possible to predetermine an external signal, by means of which it can be externally predetermined whether the switching transistor 110 should be completely blocked or should be switched on. Due to these properties, the circuit assembly 100 is particularly advantageously suitable for use in a rectifier for an electric motor, as described below with reference to Figure 4 and 5 As described.

[0086] Figure 4 A preferred design of a rectifier circuit 200 according to the present invention for rectifying a phase voltage of an electric motor 210 is schematically shown.

[0087] Electric machine 210 is shown as a single-phase electric machine by way of example, but can also be designed in a corresponding manner, for example as a three-phase electric machine. In particular, electric machine 210 is designed as a generator in a motor vehicle, for example as a three-phase AC machine, and is coupled to a crankshaft of an internal combustion engine of the vehicle, which crankshaft is connected to the crankshaft for reasons of clarity. Figure 4 In particular, the electric machine 210 is provided for charging a battery, which is in particular designed as a motor vehicle battery and can be part of the vehicle electrical system. The battery has a connection at Figure 4 Indicated by B+ and B-.

[0088] The rectifier circuit 200 is provided to rectify an AC voltage generated by the motor 210 and provided at the output terminals Vgen+ and Vgen− into a DC voltage.

[0089] For this purpose, the rectifier circuit 200 has a bridge rectifier 220 composed of high-side switches 100a, 100b and low-side switches 100c, 100d. Each of the switches 100a, 100b, 100c and 100d is designed as a preferred embodiment of the circuit assembly according to the present invention, such as in Figure 3 As shown in .

[0090] In addition, the rectifier circuit 200 has a short-circuit unit 230, which can control switches 100a, 100b, 100c and 100d in such a way that a short circuit of the phases of the motor 210 is generated. Such a short circuit can be triggered, for example, by an external controller, which can, for example, send a control signal or a short-circuit signal to the rectifier circuit 200 at the signal input terminal KS. It is also conceivable that such a short-circuit signal is triggered by an internal monitoring unit. Such a short circuit can be used in particular to not continue charging the battery when the battery is fully charged and thus not overcharge. If the decision about the short circuit is not made by an external controller, for example because the communication line between the short-circuit unit and the controller is faulty, then in addition, the fault protection unit 240 is used to make this decision.

[0091] In the example shown, the short-circuit unit 230 has a signal input 231 for receiving a control signal or a short-circuit signal. Furthermore, for each switch 100a, 100b, 100c, 100d of the bridge rectifier 220, a switching transistor or MOSFET M5, M6, M7, M8 is provided in the short-circuit unit 230, respectively.

[0092] The control terminal or gate terminal of each MOSFET M5, M6, M7, M8 is connected to the signal input 231 via an optional resistor element R25, R26, R27, R28, respectively, in order to limit the current into the gate and reduce the load on the signal input 231. A first load terminal or source terminal of each MOSFET M5, M6, M7, M8 is connected to a potential terminal B or ground, respectively.

[0093] A second load connection or drain connection of each MOSFET M5 , M6 , M7 , M8 is connected to a switch 100 a , 100 b , 100 c , 100 d of the rectifier circuit, in particular to a first signal connection 123 a or a second signal connection 123 b of the respective switch.

[0094] For example, the drain terminal of MOSFET M5 is connected to the second signal terminal of circuit component 100a in order to be able to transmit control signal Off1 to the circuit component and to permanently turn it off. Correspondingly, the drain terminal of MOSFET M6 is connected to the second signal terminal of circuit component 100b in order to permanently turn off circuit component 100b by means of control signal Off2.

[0095] The drain terminal of MOSFET M7 is connected to the first signal terminal of circuit component 100c, for example, to switch it on permanently by means of control signal On3. To switch on circuit component 100d permanently, the drain terminal of MOSFET M8 is connected to the first signal terminal of circuit component 100d for transmitting control signal On4.

[0096] If a control signal or a short-circuit signal is now applied to the signal input KS, the corresponding control signals are respectively conducted to the switches 100a, 100b, 100c, 100d by the MOSFETs M5, M6, M7 and M8, so as to turn off the high-side switches 100a and 100b and turn on the low-side switches 100c, 100d. The optional resistors R25, R26, R27 and R28 limit the current into the gates of the associated MOSFETs M5, M6, M7 and M8 as required.

[0097] The fault protection unit 240 includes a signal input terminal 241 connected to the signal input terminal KS of the rectifier circuit 200 to receive a control signal or a short-circuit signal. In addition, the fault protection unit 240 includes a signal output terminal 242 connected to the signal input terminal 231 of the short-circuit unit 230.

[0098] In addition, the fault protection unit 240 includes a diode D5, in particular a Zener diode, a resistor element R29 and a capacitor C9, wherein the resistor element R29 and the capacitor C9 are connected in series between the potential output terminals B+ and B- of the rectifier circuit 200, wherein the cathode of the diode D5 is connected to the resistor element R29, and wherein the anode of the diode D5 is connected to the signal output terminal 242.

[0099] As soon as the Zener voltage of diode D5 is exceeded, the diode breaks down and the short-circuit signal is superimposed on the KS input. In order to prevent the activation and deactivation of the Zener diode D5 for the short circuit from exceeding the high frequency, the RC element formed by the resistor element R29 and the capacitor C9 superimposes the short dead time of the fluctuation of B+, so that switching can be carried out again by the Zener diode D5 at the earliest after the dead time has expired.

[0100] exist Figure 5 In, similar to Figure 4 A preferred embodiment of a rectifier circuit 200 according to the present invention is schematically shown, wherein in this example, the short-circuiting unit has only two switching transistors M10 and M11 which are designed as MOSFETs.

[0101] The control terminal or gate terminal of the MOSFET M10 is connected via an optional resistor element R30 to the signal input 231. Correspondingly, the control terminal or gate terminal of the MOSFET M11 is connected via an optional resistor element R31 to the signal input 231. If the current into the gates of the MOSFETs M10 and M11 does not have to be limited because the input power at the signal input 231 is sufficiently high, the gate terminals can be connected directly to the signal input 231 and the resistor elements R30 and R31 can be omitted.

[0102] The second load connection or drain connection of MOSFET M10 is connected to high-side switches 100a and 100b or their second signal connection via Zener diodes D6 and D7, respectively. The second load connection or drain connection of MOSFET M11 is connected to low-side switches 100c and 100d or their first signal connection via Zener diodes D8 and D9, respectively. Therefore, MOSFET M10 is used to turn off the two high-side switches 100a and 100b for short-circuiting, and MOSFET M11 turns on the low-side switches 100c and 100d.

Claims

1. A circuit component (100) comprising a switching transistor (110, M1) and a control circuit (120) for controlling the switching transistor (110, M1), the switching transistor having a first load connection (S), a second load connection (D) and a control connection (G), The control circuit further comprises a control transistor (Q3), in particular a bipolar transistor, the control transistor having a first load connection, a second load connection and a control connection, the control circuit further comprises a diode unit (D2, Q4), a first resistor element (R4), a second resistor element (R2), a third resistor element (R3) and a potential unit (C1, V+), in, A corresponding signal path exists in - between a second load connection (D) of the switching transistor (110, M1) and a control connection of the control transistor (Q3), the signal path having a diode unit (D2, Q4) and a first resistance element (R4), - between a first load connection of the control transistor (Q3) and a control connection (G) of the switching transistor (110, M1), - between a second load connection of the control transistor (Q3) and a first load connection (S) of the switching transistor (110, M1), - between the control connection of the control transistor (Q3) and the potential unit (C1, V+), the signal path has a third resistance element (R3), and Between the first load connection of the control transistor (Q3) and the potential unit (C1, V+), the signal path has a second resistance element (R2).

2. The circuit assembly (100) according to claim 1, wherein: A signal path exists between a control connection of the control transistor (Q3) and a first signal connection (123a) for receiving a first control signal and / or between a first load connection of the control transistor (Q3) and a second signal connection (123b) for receiving a second control signal (Off).

3. The circuit assembly (100) according to claim 1 or 2, wherein: The potential unit (C1, V+) is constructed as a potential connection (V+) for connecting the circuit component (100) to a voltage source and / or as a capacitor (C1) arranged in a signal path between a first load connection (S) and a second load connection (D) of the switching transistor (110, M1), the signal path having a resistor element (R5) and a diode (D1).

4. The circuit assembly (100) according to claim 1 or 2, wherein: Between a control connection of the control transistor (Q3) and a first load connection of the control transistor (Q3) there is a signal path which has a capacitor (C2).

5. The circuit assembly (100) according to claim 1 or 2, wherein: A signal path between a first load connection of the control transistor (Q3) and a control connection (G) of the switching transistor (110, M1) has an amplifier circuit.

6. The circuit assembly (100) according to claim 5, wherein: The amplifier circuit comprises two complementary transistors (Q1, Q2), each of which comprises a first load connection, a second load connection and a control connection, wherein the first load connection of the control transistor (Q3) is connected to the third connection of the two complementary transistors (Q1, Q2), and the second connection of the two complementary transistors (Q1, Q2) is commonly connected to the control connection (G) of the switching transistor (110, M1).

7. The circuit assembly (100) according to claim 1 or 2, wherein: The diode unit (D2, Q4) is designed as a diode (D2) and / or a transistor (Q4), in particular a bipolar transistor, whose first load connection and control connection are connected to one another.

8. The circuit assembly (100) according to claim 1 or 2, wherein: The switching transistor (110, M1) is designed as a MOSFET, wherein a first load connection of the switching transistor is designed as a source connection (S) of the MOSFET, a second load connection of the switching transistor is designed as a drain connection (D) of the MOSFET, and a control connection of the switching transistor is designed as a gate connection (G) of the MOSFET.

9. The circuit assembly (100) according to claim 1 or 2, wherein: The control transistor (Q3) is designed as a bipolar transistor, wherein a first load connection of the control transistor is designed as a collector of the bipolar transistor, a second load connection of the control transistor is designed as an emitter of the bipolar transistor, and a control connection of the control transistor is designed as a base of the bipolar transistor.

10. A rectifier circuit (200) for a motor (210), the rectifier circuit being used to rectify the phase voltage of the motor (210), the rectifier circuit having two switches (100a, 100b, 100c, 100d) for each phase connection of the motor (210), At least one of the switches (100a, 100b, 100c, 100d) is designed as a circuit component according to any one of claims 1 to 9.

11. The rectifier circuit (200) according to claim 10, wherein: Each switch (100a, 100b, 100c, 100d) is designed as a circuit component according to any one of claims 1 to 9.

12. The rectifier circuit (200) according to claim 10 or 11, further comprising a short-circuit unit (230) having a signal input (231) for receiving a control signal and having at least two switching transistors (M5, M6, M7, M8, M10, M11) each having a first load connection, a second load connection and a control connection, wherein the signal paths are respectively present in between a first load connection and a potential connection (B−) of each of the at least two switching transistors (M5, M6, M7, M8, M10, M11), - between a second load connection of each of the at least two switching transistors (M5, M6, M7, M8, M10, M11) and at least one switch (100a, 100b, 100c, 100d) of the rectifier circuit (200), and - between a control connection of each of the at least two switching transistors (M5, M6, M7, M8, M10, M11) and the signal input (231), the signal path in each case having in particular a resistor element (R25, R26, R27, R28, R30, R31).

13. The rectifier circuit (200) according to claim 12, - wherein the short-circuit unit (230) has a switching transistor (M5, M6, M7, M8) for each switch (100a, 100b, 100c, 100d) of the rectifier circuit (200), wherein a signal path exists between a second load connection of each of the switching transistors (M5, M6, M7, M8) and the switch (100a, 100b, 100c, 100d) of the rectifier circuit (200), or -in, The short-circuit unit (230) has two switching transistors (M10, M11), wherein a signal path exists between a second load connection of a first switching transistor (M10) of the two switching transistors and a first number of switches (100a, 100b) of the rectifier circuit (200), and the signal path has a diode (D6, D7), and wherein a signal path exists between a second load connection of a second switching transistor (M11) of the two switching transistors and a second number of switches (100c, 100d) of the rectifier circuit (200), and the signal path has a diode (D8, D9).

14. The rectifier circuit (200) of claim 12, wherein: Each switch (100a, 100b, 100c, 100d) of the rectifier circuit (200) is respectively constructed as a circuit component (100a, 100b, 100c, 100d) having a first signal connection (123a) and / or having a second signal connection (123b), and a signal path exists between the second load connection of each switching transistor of at least two switching transistors (M5, M6, M7, M8, M10, M11) of the short-circuit unit (230) and the first signal connection (123a) or the second signal connection (123b) of one of the switches (100a, 100b, 100c, 100d) of the rectifier circuit (200).

15. The rectifier circuit (200) according to claim 12, further comprising a fault protection unit (240) having a signal input (241) for receiving a control signal and a signal output (242), in, There is a signal path between the signal output end (242) of the fault protection unit (240) and the signal input end (231) of the short-circuit unit (230), The fault protection unit (240) further comprises a diode (D5), in particular a Zener diode, a resistor element (R29) and a capacitor (C9), wherein the resistor element (R29) and the capacitor (C9) are connected in series between the potential output terminals (B+, B-) of the rectifier circuit (200), and The cathode of the diode (D5) is connected to the resistor element (R29), and the anode of the diode (D5) is connected to the signal output terminal (242).

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