Abstract:
A monitoring device for protecting against contact or access to a hybrid vehicle having a plurality of high-voltage components and an electronic control unit connected to a low-voltage vehicle electrical system battery. Power actuators for actuating at least one electric machine are connected to a high-voltage battery by way of a power switch. The high-voltage components are monitored by way of a looped circuit and deactivated if the looped circuit is broken. A sensor that is sensitive to magnetic field changes is disposed in or at a removable contact connection of the electric machine or the electronic control unit. The sensor is connected to the looped circuit. A control component of the electronic control unit activates a discharge unit for discharging an energy storage device upon receiving a sensor signal generated by the sensor when the contact connection is broken.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation, under 35 U.S.C. §120, of copending international application No. PCT/EP2009/001413, filed Feb. 27, 2009, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent applications Nos. DE 10 2008 011 962.8, filed Mar. 1, 2008, and DE 10 2008 021 542.2, filed Apr. 30, 2008; the prior applications are herewith incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a monitoring device for providing over-voltage or shock protection in a hybrid vehicle having a number of high-voltage components and having an electronic control unit which is connected to a low-voltage vehicle electrical system battery and whose power actuators are connected to a high-voltage battery via a power switch and actuate at least one electric machine. The invention also relates to a method for monitoring high voltages of such a hybrid vehicle. Monitoring protection is understood here in particular to be protection against shocks from dangerous voltages (shock protection). 
     An electric drive system of a drive configuration in a motor vehicle having high-voltage components (hybrid drive, hybrid vehicle, electric vehicle, or fuel cell vehicle) having at least one electric machine (synchronous machine or asynchronous machine) has high-voltage components with voltages which, at present, are already over 300 V (higher than 60 V DC , higher than 25 V AC ). These include, in particular, also power actuators such as, in particular, inverters, power converters and/or transformers, of an electronic control unit or ECU (electronic controller unit). 
     The high-voltage network which is composed of the high-voltage components and a high-voltage battery which feeds them is usually protected with access protection in order to avoid a risk of injury in the event of contact with the high-voltage components conducting the high voltage. It is therefore possible, for example when the drive system is switched off (and the machine is still turning), to ensure that shock protection is provided against a high voltage which is still available at the motor terminals of the electric machine. It is also necessary, when releasing plug-type contacts or contact connections, as well as when opening the machine housing of the electric machine or the equipment housing of the electronic control unit, which contains the power actuators, to ensure that the high voltage drops in the shortest possible time. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a method and a device for monitoring high-voltage connections and for overvoltage protection which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a device for providing overvoltage protection of a hybrid vehicle to prevent shocks from a dangerous voltage, which device is of simple design while at the same time providing a high degree of shock protection. Furthermore, a suitable method for providing shock-proof monitoring of the high-voltage components and in particular of the electric machine, or of each electric machine, of a hybrid vehicle is to be specified. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a monitoring device for providing protection against electrical shock in a hybrid vehicle having a plurality of high-voltage components, an electronic control unit connected to a low-voltage vehicle electrical system battery, and power actuators connected to a high-voltage battery via a power switch and configured to actuate at least one electric machine. The monitoring device comprises: 
     a loop circuit for monitoring the high-voltage components and for deactivating the high-voltage components when said loop circuit is opened; 
     a magnetic-field-sensitive sensor disposed at a releasable contact connection of the electric machine and/or of the electronic control unit, said magnetic-field-sensitive sensor generating a sensor signal when the releasable contact connection is released; and 
     a control module of the electronic control unit connected to said magnetic-field-sensitive sensor and to a discharge unit, said magnetic-field-sensitive sensor being connected to said loop circuit to cause said control module to activate said discharge unit for the shock-proof discharging of an energy accumulator in dependence on the sensor signal generated by said sensor when the contact connection is released. 
     In other words, the objects are achieved, according to the invention, by providing the monitoring device which serves to provide protection for a hybrid vehicle, in particular for the electric drive system thereof, with which the high-voltage components are monitored through a loop circuit or looped line. This monitoring expediently extends at least to those high-voltage components which are connected together with a high-voltage battery and a power switch (relay or contactor) to a high-voltage voltage network of the hybrid vehicle, and in which a high-voltage shock is possible or cannot be ruled out. These include, in particular, the electric machine, or every electric machine, and the power actuators which feed the latter and are controlled by an electronic control unit (ECU) and are arranged in a corresponding device housing. The control unit is connected to a low-voltage vehicle electrical system battery, for example to a customary 12 V DC  battery or 14 V DC  battery. 
     The loop circuit is suitably embodied as a signal line or signal line system which connects to one another all the high-voltage components which are to be monitored. Disconnection or short circuiting to ground or to the positive pole of the vehicle electrical system battery at any desired location within the loop circuit is detected and all the high-voltage components are deactivated. Virtually at the same time, the power switch which serves as the main contactor opens owing to corresponding actuation, and disconnects all the components from the high-voltage network. 
     The detection of the opened loop circuit which is effective as a high-voltage disconnection circuit or high-voltage disconnection request takes place in a contactless fashion by means of a magnetic-field-sensitive sensor, preferably by means of a Hall sensor, which expediently has a signal output which can be connected to the vehicle electrical system reference potential (ground). The sensor is connected to the loop circuit via a releasable contact connection of the electric machine and/or of the electronic control unit. The connection of the sensor is expediently carried out by its connection into one or more already present signal lines of the drive system in conjunction with the contact connection. The contactless transmission of information (loop circuit open or closed) is suitably embodied in the power-conducting high-voltage plug-type contact or screw-type contact (for example by means of a permanent magnet). 
     When the contact connection of the signal path or power path is released, the sensor generates a sensor signal on the basis of which the electronic control unit, in particular a function module or control module which is provided for this purpose, activates a discharge unit so that an energy accumulator which is connected into the high-voltage power circuit and is in the form of, in particular, one or more intermediate circuit capacitors is discharged within a very short time. The release of the contact connection can be carried out by pulling off a corresponding plug-type contact or by opening a machine housing of the electric machine or a device housing of the electronic control unit. 
     The control module of the electronic control unit is suitably coupled to the discharge unit via an optocoupler. When the sensor signal or the voltage value thereof deviates from a reference voltage, the control module generates a control signal for activating the discharge unit. Again, preferably virtually also at the same time, the control module generates a control signal, which blocks the power actuators, when the contact connection is released. The discharging of the energy accumulator or the locking or deactivation of the power actuators takes place whenever the sensor signal, i.e. a voltage value which corresponds thereto or is derived therefrom, undershoots or exceeds a reference value which is expediently derived from the terminal voltage of the low-voltage vehicle electrical system battery. A faulty loop circuit is therefore preferably determined if the sensory voltage value deviates from, for example, half the terminal voltage (+14 V) of the vehicle electrical system battery by a larger or smaller fraction of the terminal voltage. 
     The electronic control unit has a number of signal inputs, at least two inputs of which are connected to the control module. Further connections or connecting contacts of the control unit are connected to the discharge unit which is itself connected on the output side to the energy accumulator in the form of a typical intermediate circuit capacitor. The connecting contacts serve to connect the electronic control unit to the high-voltage battery. 
     A first input of the electronic control unit can expediently be connected to the low-voltage vehicle electrical system battery and to a reference input of the control module, as well as expediently via an ohmic resistor to a second input. The loop circuit can be coupled thereto and is connected via a third input of the electronic control unit to a monitoring input of the control module which is referred to below as a signal input. 
     The signal input of the control module is expediently connected via a controllable semiconductor switch, preferably a bipolar transistor, to the vehicle electrical system potential (ground). The sensor signal or the corresponding voltage value can be conducted to the signal input of the control module in a way which is positionally independent of where the respective magnetic-field-sensitive sensor is located. When there is a contact connection with the electronic control unit, the magnetic-field-sensitive sensor is expediently located within the device housing. 
     When there is a machine-side contact connection, the sensor is expediently located in the machine housing. In this variant, the sensor is connected to a temperature sensor which is assigned to the corresponding electric machine. In addition to the operationally induced temperature signal, opening of the conductor loop, detected by sensor, as a result of opening of the contact connection can also be conducted to the electronic control unit, as a state that can be correspondingly evaluated, via the usually already existing signal line or line connection of said temperature sensor to the electronic control unit. An evaluation unit which is provided for this purpose and which evaluates, within the electronic control unit, both the temperature signal and the opening of the loop circuit which is detected by the sensor, supplies a corresponding control signal to the transistor. Accordingly, the voltage value at the signal input of the control module is correspondingly changed and the discharge unit for discharging the high-voltage energy accumulators which are connected into the high-voltage power circuit is activated. At the same time, the power actuators are locked. 
     The advantages which can be achieved with the invention consist in particular in the fact that by means of a magnetic-field-sensitive sensor which is coupled in a virtually contactless fashion to a loop circuit which is effective as an overvoltage-limiting circuit or as what is referred to as a hazardous voltage interlock loop (HVIL), it becomes possible to monitor at least those high-voltage components of a hybrid vehicle which require shock protection, access protection or overvoltage protection, in a way which is particularly reliable and economical both in terms of lines and contacts. As a result, an interruption within the loop circuit can be detected both independently of time and independently of location, and any high-voltage component can be deactivated in a very short time and in addition the residual charge can be removed from the system by the virtually undelayed activation of the discharge unit for the energy accumulators or intermediate circuit capacitors. 
     The device according to the invention and the method according to the invention are therefore suitable in particular as shock protection against dangerous voltages in a hybrid vehicle. If contact connections in the form of plug-type contacts are opened or by opening a high-voltage component-containing housing, in particular the machine housing of the electric machine or the device housing of the electronic control unit with the power actuators, the actuation of the power actuators is disabled within a very short time and the energy accumulator is discharged virtually at the same time. These measures take place in a contactless fashion owing to the use of the magnetic-field-sensitive sensors and therefore virtually without an additional expenditure on signal lines, in particular by virtue of the fact that the signal lines of the temperature sensor of the electric machine are additionally used for the sensor signal. 
     With the above and other objects in view there is also provided, in accordance with the invention, a method for monitoring high voltages of a hybrid vehicle having a number of high-voltage components and having an electronic control unit for actuating at least one electric machine and power actuators connected to a high-voltage battery via a power switch. The method comprises: 
     monitoring the high-voltage components by means of a loop circuit and deactivating the high-voltage components when the loop circuit is opened; and 
     when a contact connection of one or both of the electric machine and the electronic control unit is released, generating a sensor signal with a magnetic-field-sensitive sensor, and activating a discharge unit for shock-proof discharging of an energy storage device. 
     In other words, the method monitors whether the high-voltage connection, or each high-voltage connection, of a vehicle with high-voltage components is closed. For this purpose, on the one hand, the high-voltage components which are monitored by means of the loop circuit which is effective as a detection circuit or limiting circuit are deactivated when the loop circuit is opened. On the other hand, owing to release of a contact connection which is detected by the sensor within the high-voltage voltage network, the discharging of the energy accumulator or energy storage device, connected to the high-voltage circuit, of the hybrid-electric vehicle drive is activated and the power actuators are disabled. In addition, preferably virtually at the same time the power switch (main contactor, also referred to as a circuit breaker) is activated and the electronic control unit is disconnected from the high-voltage battery. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a method and a device for monitoring high-voltage connections of a hybrid vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a schematic plan view of a drive system of a hybrid vehicle with electric high-voltage components; and 
         FIG. 2  is a schematic block circuit diagram of the connection of an electric machine and of an electronic control unit to a conductor loop for the provision of shock-proof overvoltage protection by means of Hall sensors. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a schematic view of a hybrid vehicle  1  with an internal combustion engine  2  which is coupled to a drive axle  5  or front axle  5  of the hybrid vehicle  1  via a transmission  3  that is connected to a first electric machine  4 . A second electric machine  6  is coupled in an analogous fashion to a further drive axle  8  or rear axle  8  of the hybrid vehicle  1  via a transmission  7 . The electric machines  4  and  6  are, for example, synchronous machines or asynchronous machines. 
     The electric drive system of the hybrid vehicle  1  has, as electrical or electronic high-voltage components in addition to the electric machines  4 ,  6 , primarily a high-voltage battery (for example 300 V battery)  101  and a power switch (relay, main contactor, circuit breaker)  102  which is assigned thereto, as well as an electrical air-conditioning system  103 , a heater  104  and a power inverter unit as a power actuator of an electronic control unit (ECU)  120  which is shown in more detail in  FIG. 2 . These high-voltage components which are denoted below in their entirety by  100  are connected to one another within a high-voltage voltage circuit or high-voltage voltage network via high-voltage lines  10  and are connected to the electric machines  4 ,  6 . 
     A 12 V or 24 V vehicle electrical system battery  12  and low-voltage loads  13  are connected via low-voltage lines  11  to the power inverter unit and to a central vehicle control component or vehicle electrical system control component  130 . The latter is connected via signal lines  14  to the control unit  120  and to the internal combustion engine  2  and to the high-voltage battery  101 . 
     The electronic control unit  120 , which comprises a discharge unit  121  and a power inverter unit as well as one or more transformers (DC/AC inverter)  122  and a power converter/transformer (DC/DC converter)  123  is connected via signal lines  14  to the two electric machines  4 ,  6 . 
     The vehicle control component or vehicle electrical system control component  130  comprises a superordinate vehicle open-loop or closed-loop controller (vehicle control)  131  to which a motor control unit  132 , an energy management system  133  and an open- or closed-loop drive controller (drive control unit)  134  are subordinate. The electric machines  4 ,  6  are connected via the high-voltage line  10  to the corresponding electric or electronic components (inverters)  122  of the power inverter unit of the control unit  120  via contact connections  15  which are embodied as high-voltage connections. 
     According to  FIG. 2 , the machine-side contact connection  15  is embodied as a three-pole plug-type contact with integrated permanent magnet as a signal generator  16  of a Hall sensor  17 . The Hall sensor  17  or a Hall IC with integrated evaluation circuit  18  and a transistor  19  is integrated as a controllable semiconductor switch into the electric machine  4 , i.e. inserted into the machine housing  20  thereof. The contact connection  15  can also be integrated into the machine housing  20  in such a way that when the machine housing  20  is opened, the contact connection  15  opens and the connection to other high-voltage components  100  is disconnected. Such a contact connection  15  is likewise suitably provided on the machine  6 . 
     A further contact connection  21  is provided on the electronic control unit  120  and there in turn expediently on the device housing  22 . The contact connection  21  can also in turn be integrated into the electronic control unit  120  in such a way that when the device housing  22  opens or the housing lid thereof opens, the contact connection  21  is released and therefore the connection to other high-voltage components  100  is opened. A permanent magnet serves in turn as a signal generator  23  of a Hall sensor  24  with an integrated evaluation circuit  25  and with a transistor  26 , connected to ground G, as a controllable semiconductor switch. The Hall sensor  24  has a signal output  27  at which a sensor signal S H  or voltage signal U H  can be tapped via an ohmic resistor R 3 . The voltage value U H  thereof changes during the detection of contact opening of the contact connection  21 , since the Hall sensor  24  detects the changing magnetic field of the permanent magnet  23  when the contact connection  21  opens. The contact connections  15 ,  21  can also be screw-tight connections with a cover and magnet. 
     The electronic control unit  120  has a control module  30  with a reference input  31  and with a signal input  32 . On the output side, the control module  30  is coupled to a discharge unit  121  via an optical coupling  33 , which comprises a light-emitting diode  34  and a phototransistor  35 . The discharge unit is connected on the output side to connections  37 ,  38  for connecting the control unit  120  to the high-voltage battery  101 . An intermediate circuit capacitor as an energy storage device or energy accumulator  39  is connected between the connections  37 ,  38 . The control module  30 , furthermore, has signal connections  28 ,  29  to the DC/AC converter  122  and to the DC/DC converter  123 , respectively. 
     The reference input  31  of the control module  30  is connected on the inside of the device to a first input  40  of the control unit  120 . This input  40  is connected, on the one hand, to the vehicle electrical system battery  12  via the low-voltage line  11 . On the other hand, this input  40  is connected on the inside of the device via an ohmic resistor R 1  to a second input  41 . The latter is in turn connected via a looped line or loop circuit  42  to a further input  43 , which is in turn connected inside the device to the signal input  32  of the control module  30  of the electronic control unit  120 . A controllable semiconductor switch in the form of a transistor  44  is connected to the signal input  32  and to the signal input  32  on the collector side via an ohmic resistor R 2 , and to ground G on the center side. On the control side or base side, this transistor  44  is connected to an evaluation unit  45  which is connected on the input side to signal inputs  46 ,  47  of the control unit  120 . The corresponding signal line  14  is connected to said signal inputs  46 ,  47  and to the signal connections  48 ,  49  of the electric machine  4 . On the machine side, these signal connections  48 ,  49  are connected to a temperature sensor  50 . The collector/emitter path of the transistor  19  of the sensor  17  is connected into the connection between the temperature sensor  50  and the signal connection  48 . The evaluation circuit  18  of said sensor  17  actuates the transistor  19  as a function of the state of the contact connection  15 . 
     The electrical loop circuit  42  for providing shock protection connects at least those high-voltage components  100  of the hybrid vehicle  1  which are to be monitored and on which shock protection is provided. If a contact connection is opened on one of these high-voltage components  100 , by, for example, a corresponding device being opened or a plug contact being released, the control module  30  of the electronic control unit  120  generates a control signal S T  in order to activate the discharge unit  121 . The energy accumulator  39  is discharged at least approximately simultaneously with the actuation of the main contactor  102  and therefore the interruption of the high-voltage voltage circuit  100 . When the loop circuit  42  is open owing to a short-circuit or disconnection of a high-voltage component  100 , which is illustrated by the opened switch symbol, the voltage value U H  at the signal input  32  of the control module  30  changes. 
     Similarly, the control module  30  generates the control signal S T  if the device-side contact connection  21  of the electronic control unit  120  is opened. If the device-side contact connection  21  is then opened, the sensor  24  generates a corresponding voltage value U H  at the signal input  32  of the control module  30 . For this purpose, the transistor  26  of the Hall sensor  24  and the transistor  44  are connected in series in a way which is not illustrated in more detail, with the transistor  26  being connected on the collector side to the resistor R 2  and on the center side to the transistor  44 . The resistor R 3  which is illustrated can then be dispensed with. Alternatively, the transistor  26  of the Hall sensor  24  can be connected to a further input (not illustrated) of the control module  30 , and the resistor R 3  can be connected to the reference voltage U KI . 
     The control module  30  compares the current voltage value U H  with a reference value U KI , which preferably corresponds to the terminal voltage U KI =(+)14V of the vehicle electrical system battery  12 . During interruption-free and fault-free operation, this voltage value U H  at the signal input  32  of the control module  30  is expediently set as a test signal to half the terminal voltage U KI  of the vehicle electrical system battery (U H =½U KI ). At a separate input of the control module  30 , this voltage value is approximately zero volts (0 V). Changing this voltage value U H  owing to opening of the contact connection  21  is therefore used by the control unit  120  to activate the discharge unit  121  by virtue of the connection of the device-side sensor  24  to the conductor loop  42 . 
     In an analogous fashion, the machine-side sensor  17  is also connected to the conductor loop  42 . For this, use is made of the signal line  14  of the temperature sensor  50 , via which signal line  14  the operationally induced temperature signal T of the temperature sensor  50  is conducted to the evaluation unit  45 . If the machine-side contact connection  15  is opened, this is detected by the sensor  17 . To do this, the evaluation circuit  18  actuates the transistor  19  in such a way that, for example, no temperature signal T, or an implausible temperature signal T, is conducted to the evaluation unit  45  via the signal line  14 . This information or this state is detected virtually as a corresponding sensor signal S H  by the evaluation unit  45  so that a corresponding control signal is conducted to the control input (base) of the transistor  44  and the latter is correspondingly actuated. Accordingly, the voltage value U H  changes in turn at the signal input  32  of the control module  30 . The machine-side sensor  17  is therefore also connected to the conductor loop  42 , in turn in particular via the signal input  32  of the control module  30 . 
     When the contact connection  15  or  21  is opened, the voltage value U H  at the signal input  32  also deviates from the reference value (U H =½U KI ) of the control module  30 . For example a faulty loop circuit  42  or an opened contact connection  15 ,  21  is therefore detected if the voltage value U H  is greater than ⅔ or less than ⅓ of the terminal voltage U KI . In such a case of the reference value ½U KI  being undershot or exceeded, the main contactor  102  is opened and therefore virtually any high-voltage component  100  is deactivated. At the same time, owing to the actuation of the discharge unit  121  via the control module  30  of the electronic control unit  120 , the residual charge stored in the energy accumulator  39  is removed from the high-voltage system of the hybrid vehicle. 
     Such deactivation of the high-voltage components  100  and activation of the discharge unit  121  for the discharge of the energy accumulator  39  ensures reliable shock protection or access protection within a very short time. This is a significant safety aspect in particular in the case of maintenance work and repair work to the hybrid vehicle  1  in order to avoid potential risks of injury owing to contact with high-voltage components  100  which correspondingly conduct high voltages. Electric shock protection through the deactivation of the high-voltage components  100  on the one hand and the virtually simultaneous activation of the discharge unit  121  in order to reduce the residual charge of the energy accumulators  39  to zero or to non-hazardous voltage values within a very short time takes place expediently if the loop circuit  42  is disconnected, a short circuit to ground G or to the positive potential (+) 14 V takes place within the conductor loop  42  or if the 14 V vehicle electrical system voltage U KI  is absent, i.e. U KI =0.