This patent application is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a control unit for driving an electric load, in particular an electric machine, having a first and a second voltage terminal in order to supply the control unit with electrical energy, a capacitor, which is connected between the voltage terminals, at least one half-bridge, which is connected between the voltage terminals, wherein the half-bridge has two controllable switches, between which there is formed a half-bridge tap for connecting the load, a safety circuit, which is designed to close one of the controllable switches of the half-bridge in the event of a fault, and a discharge circuit, which is designed to connect the voltage terminals electrically in the event of a fault.
"The present invention further relates to a method for initiating a safety mode of a control unit for driving an electric load, in particular an electric machine, wherein the control unit has a first and a second voltage terminal in order to supply the control unit with electrical energy, a capacitor, which is connected between the voltage terminals, at least one half-bridge, which is connected between the voltage terminals, wherein the half-bridge has two controllable switches, between which there is formed a half-bridge tap for connecting the load. Said method comprises the steps: detecting a fault, closing a controllable switch of the half-bridge by means of a safety circuit and connecting the voltage terminals electrically by means of a discharge circuit.
"Finally, the present invention relates to a drive train of a motor vehicle comprising an electric machine for providing the driving power, an energy supply unit for providing electrical energy and a control unit of the kind described above for driving the electric machine.
"In the field of automotive drive technology, it is universally known to use an electric machine as the sole drive or jointly with a drive motor of another type (hybrid drive). Power electronics, which include a power inverter that converts the DC voltage/DC current of a battery situated on-board of the motor vehicle into an AC current, serve to drive such electrical machines in a motor vehicle.
"Known power inverters comprise a plurality of switching elements, with which the individual phases of the electric machine are connected to a high supply voltage potential or to a low supply voltage potential. In so doing, two switching elements are each interconnected in series to a half-bridge, wherein a half-bridge tap is formed between the switching elements, at which tap the respective phase of the electrical machine is connected.
"In the event of a fault, e.g. due to too high a battery current or too high a supply current, the power inverter is switched into a safe state in order to prevent possible damage to the electrical components. Essentially two different power-off methods are known from the prior art which are used alternatively. In the first method, individual or all of the controllable switches which are connected to the low supply voltage potential (low-side switches) are closed. This operating mode is also designated as the short-circuit mode. In the other power-off method the voltage terminals of the power inverter are connected to one another via an electrical resistor in order to produce a discharge of the intermediate circuit capacitor of the power inverter. Such a discharge circuit can be selectively implemented as a permanently energized discharge, which however permanently converts energy from the intermediate circuit capacitor into heat and therefore leads to a reduced degree of efficiency, or even implemented as a discharge circuit which can be switched on or switched off and which must be activated, for example, if an opening of the traction network connector is recognized.
"The German patent application DE 10 2006 003 254 A1 discloses a method for operating an electric machine with a pulse width modulated inverter in the event of a fault, in which method the electric machine is initially switched into a disconnected mode and subsequently into a short-circuit mode.
"A disadvantage of the known power-off methods is that the individual disconnections are activated using different triggering criteria and therefore require considerable technical complexity, high costs and large installation space.
"It is therefore the aim of the present invention to provide an improved control unit for driving an electric load, which control unit can be switched into a safe state with less technical complexity. It is further the aim of the present invention to provide a corresponding method."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventor's summary information for this patent application: "According to the invention, this aim is met with the control unit stated at the beginning of the application by virtue of the fact that provision is made for a control circuit that is designed to provide a control signal which triggers the safety circuit and the discharge circuit in the event of a detected fault.
"In addition, the aforementioned aim of the method specified above is met by virtue of the fact that the safety circuit and the discharge circuit are triggered by a signal which is provided by a control circuit.
"Finally the aim mentioned above is met by means of a drive train of a motor vehicle comprising an electric machine for providing the driving power, an energy supply unit for providing electrical energy and a control unit of the type specified above for driving the electric machine.
"By means of the present invention, a switch-off of a power inverter can be provided which is implemented with a reduced number of actuations. This results from the fact that the one control circuit actuates or, respectively, triggers the emergency discharge circuit as well as the safety circuit and thus a separate control can be eliminated. In so doing, costs and installation space for the control unit can be considerably reduced.
"The discharge circuit preferably comprises a resistor and a controllable switch, wherein the resistor and the controllable switch are connected in series between the voltage terminals.
"The intermediate circuit capacitor can thereby be discharged with simple means and the stored energy can be converted to heat in the resistor.
"It is furthermore preferred that the safety circuit comprises a controllable switch which is designed to connect the first voltage terminal to a voltage input of the connected controllable switch.
"The controllable switch of the half-bridge can thereby be closed using simple means, wherein the corresponding voltage or, respectively, electrical energy for actuating the switch out of the traction network can be used at the same time, whereby energy is additionally led away from the traction network.
"It is furthermore preferred that the control circuit is designed to trigger the safety circuit and the discharge circuit substantially at the same time.
"In so doing, the resistor of the emergency discharge circuit can be dimensioned smaller because the safety circuit extracts a portion of the energy of the traction network by actuating the controllable switch.
"It is generally preferred that the control unit comprises a high-voltage section and a low-voltage section, wherein the high-voltage section has a supply voltage which is greater than a supply voltage of the low-voltage section and wherein the high-voltage section is galvanically isolated from the low-voltage section.
"In so doing, components of the control unit can be used from other control units having a low supply voltage without additional voltage converters being required.
"It is thereby preferred that the control circuit is associated with the high-voltage section.
"The control signal of the safety circuit and the discharge circuit can thereby be directly provided without a galvanic isolation having to be overcome, whereby the shut-down speed is not delayed.
"It is furthermore generally preferred that the control circuit is connected to detection means which are designed to monitor at least one function of the control unit.
"Possible malfunctions of the control unit can thereby be continually monitored.
"It is thereby particularly preferred that the control circuit is connected via signal transmission means to the detection means of the low-voltage section, wherein the detection means are designed to monitor at least one function of the low-voltage section.
"In so doing, malfunctions of the low-voltage section of the control unit can also be taken into account.
"It is generally preferred that the first voltage terminal is associated with a high voltage potential and the second voltage terminal with a low voltage potential, wherein the switch which can be actuated by the safety circuit is connected to the low voltage potential.
"High induction currents which can possibly occur can thereby be quickly and simply discharged, whereby the entire control unit can be brought more quickly into a safe state.
"It goes without saying that the features, properties and advantages of the inventive control unit also accordingly pertain to or apply to the inventive method.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 shows in schematic depiction a motor vehicle having a hybrid drive train which comprises a combustion engine or an electric machine; and
"FIG. 2 shows in schematic depiction a circuit diagram of a control unit for driving an electric machine comprising an emergency discharge circuit and a safety circuit."
URL and more information on this patent application, see: Schoenknecht, Andreas. Control Unit. Filed
Keywords for this news article include: Electronics, High Voltage,
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