MXPA96006298A - Energy source of electric vehicle propulsion system with integr test - Google Patents

Abstract

The present invention relates to an energy bridge (48) for a propulsion system of an electric vehicle, which comprises a switching circuit that includes first and second switching elements (54, 56), which can operate between the states "on" and "off", and a midpoint detector (68,69) coupled with the switching circuit, to detect a fault of at least one of the first and second switching elements (54, 5).

Description

ENERGY BRIDGE OF ELECTRIC VEHICLE PROPULSION SYSTEM WITH INTEGRATED TEST RELATED APPLICATIONS The following patent applications of the United States of America were filed on the same date as the present application and are related and incorporated by reference in this application. The United States patent application of North America entitled "Flat Topping Concept" which bears the case number 58.95, and which was filed on the same date as this; The United States of America Patent Application entitled "Electric Induction Motor And Related Method Of Cooling" bearing the case number 58,332, and which was filed on the same date herewith, - The United States Patent Application. of North America entitled "Automotive 12 Volt System For Electric Vehicles" bearing the case number 58,333, -and which was filed on the same date herewith; The United States patent application of North America titled "Direct Cooled Switching Module For Electric Vehicle Propulsion System "bearing the case number 58,334, and which was filed on the same date with the present; The patent application of the United States of North America entitled "Electric Vehicle Propulsion System" bearing the case number 58,335, and which was filed on the same date herewith; The United States patent application of North America entitled "Speed Control and Bootstrap Technique for High Voltage Motor Control" bearing the case number 58,336, and which was filed on the same date with the present; The United States patent application of North America entitled "Vector Control Board For An Electric Vehicle Propulsion System Motor Controller" bearing the case number 58,337, and which was filed on the same date herewith; The United States patent application of North American entitled "Digital Pulse Width Modulator With Integrated Test And Control" which bears the case number 58,338, and which was filed on the same date with the present; The United States patent application of North America entitled "Control Mechanism For Electric Vehicle" bearing the case number 58,339, and which was filed on the same date herewith; The United States of America Patent Application entitled "Improved EMI Filter Topology for Power Inverters" bearing case number 58,340, and which was filed on the same date herewith; The United States patent application of North American entitled "Fault Detection Circuit For Sensing Leakage Currents Between Power Source And Chassis" which bears the case number 58,341, and which was filed on the same date with the present; The application for a United States of America Patent entitled "Electric Vehicle Relay Assembly" bearing case number 58,342, and which was filed on the same date herewith; The patent application of the United States of North America entitled "Three Phase Power Bridge Assembly" bearing the case number 58,343, and which was filed on the same date herewith; The United States patent application of North America titled "Method For Testing A Power Bridge For An Electric Vehicle Propulsion System "bearing the case number 58,345, and which was filed on the same date as this; United States Patent Application North America titled "Electric Vehicle Power Distribution Module "bearing the case number 58,346, and which was filed on the same date with the present one: The United States of America Patent Application entitled" Electric Vehicle Chassis Controller "bearing the case number 58,347, and which was filed on the same date herewith: The United States of America Patent Application entitled "Electric Vehicle System Control Unit Housing" bearing case number 58,348, and which was filed on the same date herewith; of the United States Patent of North American entitled "Low Cost Fluid Cooled Housing for Electric Vehicle System Control Unit" bearing the case number 58,349, and which was filed on the same date with this; The United States of America Patent Application entitled "Electric Vehicle Coolant Pump Assembly" bearing case number 58,350, and which was filed on the same date herewith; The United States of America Patent Application entitled "Heat Dissipating Transformer Coil" bearing case number 58,351, and which was filed on the same date herewith; The patent application of the United States of North America entitled "Electric Vehicle Battery Charger" bearing the case number 58,352, and which was filed on the same date herewith.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an energy bridge. More particularly, the present invention relates to an energy bridge of a propulsion system of an electric vehicle. Although the invention is subject to a wide range of applications, it is especially convenient for use in electric vehicles that use batteries or a combination of batteries and other sources, for example, a heat engine coupled to an alternator, as a source of energy, and will be particularly described in connection with this.

Description of the Related Art For an electric vehicle to be commercially viable, its cost and performance must be competitive with that of its petrol-fueled counterparts. Typically, the propulsion system of the vehicle and the battery are the main factors that contribute to the competitiveness in cost and performance of the vehicle. "Generally, to achieve commercial acceptance, a propulsion system for electric vehicles must provide the following characteristics: ( 1) vehicle performance equivalent to typical propulsion systems energized with gasoline, (2) even control of vehicle propulsion, (3) regenerative braking, (4) high efficiency; (5) low cost, - (6) self-cooling; (7) confinement of electromagnetic interference (EMI); (8) fault detection and self-protection; (9) self-test and diagnostic capability, - (10) control and status interfaces with external systems, - (11) safe operation and maintenance; (12) Flexible capacity to charge the battery, - and (13) 12 volt auxiliary power from the main battery. However, in previous practice the design of electric vehicle propulsion systems consisted largely of matching an engine and a controller with a set of vehicle performance goals, so that performance was often sacrificed to allow a design practical motor and controller. In addition, little attention was paid to the above characteristics that increase commercial acceptance. A typical conventional propulsion system for electric vehicles comprises, among other things, an energy bridge that includes high-power electronic switches to supply current to the windings of a motor. When one or more of these switches fail, the manual diagnostic test of the power bridge is performed to detect and isolate the transistor or the transistors that failed. However, manual testing of the switching transistors can be both costly and time consuming and often requires trial and error techniques.

COMPENDIUM OF THE INVENTION In accordance with the foregoing, the present invention is directed to an energy bridge of an electric vehicle propulsion system that substantially obviates one or more of the problems due to limitations and inconveniences of the related art. The features and advantages of the invention will be presented in the description that follows, and in part will be apparent from the description or can be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the method and apparatus particularly indicated in the written description and in the claims thereof as well as in the accompanying drawings. To achieve these and other advantages in accordance with the purpose of the invention, as incorporated and described extensively, the invention provides an energy bridge for an electric vehicle propulsion system, comprising a circuit of switches that includes a first and a second switching element that can operate between the "on" states and "off" and a midpoint detector coupled with the switching circuit to detect a fault of at least one of the first and second switching elements. In another aspect, the invention provides a puont or power for an electric vehicle propulsion system, comprising a plurality of switching circuits each including a first and a second switching element that can operate between the "on" states and "off" and a midpoint detector coupled with one of the plurality of switching circuits to detect a fault of at least one of the first and second switching elements of each of the plurality of switching circuits. It will be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide additional explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a better understanding of the invention and are incorporated and constitute a part of this specification, illustrate a currently preferred embodiment of the invention and, together with the description, serve to explain the principles of the invention. In the drawings: Figure 1 is a block diagram of an electric vehicle propulsion system according to a preferred embodiment of the invention; Figure 2 is a power distribution diagram of the electric vehicle propulsion system of Figure 1, - Figure 3 is a functional diagram of the electric vehicle propulsion system of Figure 1; Figure 4 is a functional diagram of the motor controller of the electric vehicle propulsion system of Figure 1; Figure 5 is a cooling diagram of the electric vehicle propulsion system of Figure 1; Figure 6A is a schematic diagram of the motor of the electric vehicle propulsion system of Figure 1; Figure 6B is a schematic diagram of the separator of the electric vehicle propulsion system of Figure 1; Figures 7 and 8 are schematic diagrams of the power bridges of the motor controller of Figure 4; and Figure 9 is a schematic diagram of a midpoint detector.

DESCRIPTION OF THE PREFERRED MODALITY Reference will now be made in detail to a currently preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. As shown in Figure 1, there is provided an electric vehicle propulsion system 10 comprising a system control unit 12, a motor assembly 24, a cooling system 32, a battery 40, and a DC / DC converter 38. The system control unit 12 includes a cold plate 14, a battery charger 16, a motor controller 18, an energy distribution module 20, and a chassis controller 22. The motor assembly 24 includes a separator 26, a motor 28, and a filter 30. The cooling system 32 includes an oil pump unit 34 and a radiator / fan 36. As shown in Figure 2, the battery 40 serves as the primary source of energy for the electric propulsion system 10. The battery 40 comprises, for example, a sealed lead acid battery, a monopolar lithium-sulfide metal battery, a bipolar lithium-sulfide metal battery, or the like, to provide an output of 320 volts. Preferably, the electric propulsion system 10 operates over a wide voltage range, for example 120 volts to 400 volts, to accommodate changes in battery output voltage 40 due to the discharge load or depth. However, the electric vehicle propulsion system 10 is preferably optimized for nominal battery voltages of approximately 320 volts. The power distribution module 20 is coupled with the output of the battery 40 and includes, among other things, fuses, cables, and connectors for distributing the 320 volt output from the battery 40 to various components of the power system. electric vehicle 10. For example, the power distribution module 20 distributes the 320 volt output of the battery 40 to the motor controller 18, the DC / DC converter 38, the oil pump unit 34, and the battery charger 16. The power distribution module 20 also distributes the 320-volt output of the battery 40 to various vehicle accessories, which are external to the electric vehicle propulsion system 10. These vehicle accessories include, for example, a power system. air conditioning, a heating system, an energy management system and any other accessory that may require a power supply of 320 volts. The DC / DC converter 38, which, as described above, is coupled to the 320 volt output of the power distribution module 20, converts the 320 volt output of the power distribution module 20 to 12 volts. The DC / DC converter 38 then supplies its 12 volt output as operating power to the battery charger 16, the motor controller 18, the chassis controller 22, the oil pump unit 34, and the radiator / fan 36. The DC / DC converter 38 also supplies its 12 volt output as operating power to various vehicle accessories, which are external to the electric vehicle propulsion system 10. These vehicle accessories include, for example, vehicle lighting, a audio system, and any other accessory that may require a 12 volt power supply. It should be appreciated that the DC / DC converter 38 eliminates the need for a separate 12-volt storage battery. The operation of the electric vehicle propulsion system 10 will now be described with reference to Figures 3 to 9. As shown in Figures 3 and 4, the components of the electric vehicle propulsion system 10 are interconnected by several data bus bars . The bus bars can be of the electrical, optical, or electro-optical type, as is known in the art. The battery charger 16 receives command signals from and sends status signals to the motor controller 18 to charge the battery 40. The battery charger 16 provides a controlled battery charge current from an external source of AC power (not shown). Preferably, the alternating current is extracted from the external source at an energy factor close to unity and low harmonic distortion according to future expected energy quality standards. In addition, the battery charger 16 is preferably designed to be compatible with standard earth leakage current interrupters and single phase power normally found in residential locations. The oil pump unit 34 and radiator / fan 36 also receive command signals from and send status signals to the motor controller 18. As shown in Figure 5, the electric vehicle propulsion system 10 utilizes a cooling system closed cycle including cold plate 14, filter 30, engine 28, oil pump unit 34, and radiator / fan 36. Preferably, cold plate 14 is a hollow body having a double-sided surface on which the battery charger 16, the motor controller 18, and the power distribution module 20 are mounted in thermal contact. It is contemplated that the DC / DC converter 38 can also be mounted in thermal contact with the cold plate 14. The oil pump unit 34 circulates oil, for example, aircraft turbine oil, from the engine oil container 28 through the radiator / fan 36, the cold plate 14, the filter 30, and again through the 28 motor as shown in Figure 5. The heat is removed from the oil by the radiator / fan 36 and the oil is filtered by the filter 30, which may comprise an oil filter commercially available in the art. Preferably the oil pump unit 34 is controlled by the motor controller 18 to provide a variable speed of oil flow. It should be appreciated that the closed-cycle oil cooling system of Figure 5 protects the electric vehicle propulsion system 10 from the harsh environment of automotive operation, thereby increasing reliability and reducing maintenance. In addition, because the same oil used to lubricate the motor 28 is also used to cool the control unit of the system 12, the cooling system can have a simplified design. The separator 26 is illustrated in Figure 6B and is positioned close to the motor 28 to detect the angular position of the motor shaft and to provide signals indicative of the angular position of the motor. the arrow of the motor to the motor controller 18. The reference signal line R connected to the separator is for a positive or negative reference value indicating the angular position of the motor shaft. The signal line S [of the separator provides a positive or negative sine value for the angular position of the motor shaft and the line of signal S2 of the separator provides a positive or negative cosine value for the angular position of the motor shaft. The separator 26 may comprise a commercially available separator or other separator known in the art. The reference signals for the separator 26 are provided by the motor controller 18. The chassis controller 22 and the motor controller 18 receive signals from a vehicle communication bus. Usually, the vehicle communication busbar serves as a communication path for interconnecting various sensors and controllers of the vehicle to the chassis controller 22 and the motor controller 18, as will be explained in more detail below. The chassis controller 22 comprises a digital and aneroid microprocessor-based electronic system and provides control and status interconnection for the sensors and controllers of the vehicle and for the motor controller 18. For example, the chassis controller 22 is connected, via the vehicle communication busbar, to the vehicle key switch, accelerator, brake and steering selector switches. The chassis controller 22 interprets the signals from these switches to provide the motor controller 18 with start-up commands, driving mode (eg, forward, reverse, and neutral) torque of the motor, regenerative braking, shutdown, and integrated test (BIT). Preferably, the chassis controller 22 communicates with the motor controller 18 via an opto-coupled data interface in series and receives status signals from the controller 18 of all commands sent to verify the communication links between the chassis controller 22 , the vehicle, and the engine controller 18 and verify that the vehicle is operating properly. It should be appreciated that because the chassis controller 22 provides the control and status interconnection to the sensors and controllers of the vehicle and to the motor controller 18, the electric vehicle propulsion system 10 can be modified for use with any number of different vehicles by simply modifying the chassis controller 22 for a particular vehicle. The chassis controller 22 also provides battery management capabilities using the signals received on the vehicle communication bus from a battery current sensor located in the power distribution module 20. The chassis controller 22 interprets signals from the battery current sensor, provides charging commands to the motor controller 18, and sends a charge status value to a "fuel" gauge on the vehicle dashboard. The chassis controller 22 also connects, via the vehicle communication busbar, to vehicle controllers that include the odometer, speedometer, lighting, diagnostic and emission controllers, as well as an RS-232 interface for system development. As shown in Figure 4, the motor controller 18 includes a low voltage power supply 42, an input filter and a DC relay control unit 44, a vector control board 46, and a first and a second power bridges and gate actuators 48 and 50, respectively. The low voltage power supply 42 converts the 12 volt output of the DC / DC converter 38 to provide outputs of + 15V, +/- 15V, and + 20V to the input filter and relay control unit DC 44, the board vector control 46, the first energy bridge 48, and the second energy bridge 50. The low voltage power supply 42 may comprise a commercially available power supply as is known in the art. The input filter and relay control unit DC 44 includes electrical connections for coupling the 320 volt output of the power distribution module 20 to the first and second power bridges 48 and 50, respectively. The input filter and relay control unit DC 44 includes EMI filtering, a relay circuit for disconnecting the coupling from the 320 volt output of the power distribution module 20 to the first and second energy bridges 48 and 50, respectively , and several integrated test circuits that include voltage sensing circuits and a chassis ground loss circuit. Preferably, the input filter and the DC relay control unit 44 receive control signals from and send status signals, for example, integrated test signals, to the vector control board 46. The vector control board 46 comprises a digital and analog electronic system based on microprocessor. As its primary function, the vector control board 46 receives acceleration initiated by the driver and braking requests from the chassis controller 22. The vector control board 46 then acquires measurements of the rotor position from separator 26 and current measurements from the first and second energy bridges 48 and 50, respectively, and uses these measurements to generate pulse width modulated voltage (PWM) waveforms to drive the first and second energy bridges 48 and 50, respectively, for producing the desired acceleration or braking effects in the motor 28. Modulated pulse width voltage waveforms are generated according to a control program that is designed to result in the production of the requested torque. As described above, the vector control board 46 also has the function of controlling the input filter and relay control unit DC 44, the oil pump unit 34, the radiator / fan 36, the battery charger 16, the input filter and DC 44 relay control unit, integrated test circuits, vehicle communication, and fault detection. As shown in Figure 6A, the motor 28 is a 3-phase AC induction motor having two identical windings, electrically isolated, per phase (windings Al and A2 are for phase "A", windings Bl and B2 are for phase "B", and windings Cl and C2 are for phase "C") to produce high torque at zero speed to provide performance comparable to conventional gasoline powered machines. The arrow (not shown) of the engine 28 engages with the transaxle of the vehicle (not shown). Preferably, the two windings in each phase of the motor 28 are substantially aligned on top of one another and are electrically in phase so that each winding provides about half of the total energy of the phase. Preferably also the motor 28 is completely sealed and uses spray oil cooling to remove heat directly from the rotor and from the end windings to increase reliability. As shown in Figure 7, the first energy bridge 48 includes three isolated gate bipolar transistor (IGBT) switching circuits 52a, 52b and 52c and the second energy bridge 50 includes three bipolar transistor switching circuits 53a, 53b and 53c. The isolated gate bipolar transistor switching circuits 52a, 52b and 52c apply drive currents to the windings Al, Bl and Cl, respectively, of the motor 28. Similarly, the insulated gate bipolar transistor switching circuits 53a, 53b and 53c apply drive currents to the windings A2, B2 and C2, respectively, of the motor 28. Each of the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c includes a bipolar transistor isolated top and bottom door 54 and 56, respectively, upper and lower diodes 58, 60, respectively, and a capacitor 62 connected as shown in Figure 7. Preferably the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c are all identical so that each of the first and second energy bridges 48 and 50, respectively, provides half the drive current to the b 28 of motor 28, thereby allowing the use of low-cost, easily available insulated gate bipolar transistor switching circuits. It is contemplated that the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c may be replaced with other switching circuits known in the art. As also shown in Figure 7, the first energy bridge 48 further includes three gate drive circuits 64a, 64b, and 64c and the second energy bridge 50 further includes three gate drive circuits 65a, 65b, and 65c . The gate drive circuits 64a, 64b, 64c receive the modulated pulse width voltage waveforms in the form of gate drive signals AU1 and AL1, gate drive signals BU1 and BL1, and drive signals of gate CU1 and CL1, respectively, from the vector control board 46. Likewise, the gate drive circuits 65a, 65b, and 65c receive the modulated pulse width voltage waveforms in the form of signals from gate drive AU2 and AL2, gate drive signals BU2 and BL2, and gate drive signals CU2 and CL2, respectively, from the vector control board 46. The gate drive circuits 64a, 64b and 64c and the gate drive circuits 65a, 65b, and 65c change the level of the received gate drive signals and apply the changed gate drive signals to the gate switching circuits. Isolated gate bipolar transistors 52a, 52b, 52c, 53a, 53b and 53c as shown in Figure 7 for driving the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c. It is contemplated that each of the gate drive circuits 64a, 64b, 64c, 65a, 65b, and 65c may comprise, for example, a Fuji EXB841 Gate Drive Hybrid or other similar device known in the art. As shown in Figure 8, the current sensors 66 are provided on the windings Al, A2, Cl and C2 of the motor 28. As described above, the vector control board 46 uses current measurements from the sensors of current 66 to generate the gate drive signals AU1, AL1, BU1, BL1, CU1, and CL1. The placement of the current sensors 66 can be varied as is known in the art. For example, instead of being provided in the windings Al, A2, Cl and C2, the current sensors 66 could be provided to the windings in the windings Al, A2, Bl, and B2 or in the windings Bl, B2, Cl and C2. As also shown in Figure 8, the mid-point detectors 68 and 69 are provided in each of the windings Bl and B2, respectively, of the motor 28. As will be described in more detail below, the mid-point detectors 68 and 69 are used to automatically detect and isolate the faults of the transistors in the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c. As shown in Figure 9, each of the midpoint detectors 68 and 69 includes a pair of resistors 70 and 72 and a pair of opto-couplers 74 and 76 connected as shown. A series combination of the resistor 70 and the optocoupler 74 is connected in parallel with the bipolar upper isolated gate transistor 54 of phase B and the series combination of the resistor 72 and the opto-coupler 76 is connected in parallel with the transistor bipolar of bottom insulated door 56 of phase B. Each of the opto-couplers 74 and 76 may comprise, for example, an opto-coupler Toshiba H11L1F1 or other similar device known in the art. Although Figure 9 shows that the optocouplers 74 and 76 are of the reversal type, the optocouplers 74 and 76 may alternatively be of the noninverting type as is also known in the art. In addition, the values of the resistors 70 and 72 are chosen so that the resistors 70 and 72 excite the input LEDs of the optomaxers 74 and 76, respectively, both with half-full voltage and through the switching circuits of insulated gate bipolar transistors 52b and 53b. In this way, the presence of at least half the voltage across the lower insulated gate bipolar transistor 54 and 56 will result in the generation of a signal at the output of the respective opto-couplers 74 or 76. The logic of the Midpoint detectors 68 and 69 of Figure 9 are summarized in Table I below. The test of the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c is carried out by the vector control board 46, preferably during a diagnostic routine in the ignition or during a routine Fault detection. It is contemplated, however, that the testing of the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c can also be carried out by an external diagnostic computer in a repair facility. The proper operation of the first and second power bridges 48 and 50, respectively, will exhibit the following characteristics when their isolated gate bipolar transistors are selectively activated in a test mode: TABLE I The test of the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c, is performed in this manner by operating the vector control board 46 or the external diagnostic computer to first turn off both the upper transistor 54 as lower transistor 56 of each of the insulated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c and check to make sure that the outputs of each of the midpoint detectors 68 and 69 are low. Then, the vector control board 46 or the external diagnostic computer turns on and then sequentially turns off each transistor while monitoring the outputs of the midpoint detectors 68 and 69. If an output of one of the midpoint detectors 68 and 69 does not match the logic of Table I above, the isolated gate bipolar transistor switching circuit that includes the transistor that produced the incorrect output is considered to be faulty. However, if all the bipolar gate transistor switching circuits isolated from a set of windings are faulty, the midpoint detector for that set of windings is considered to be faulty. The test of the isolated gate bipolar transistor switching circuits 52a, 52b, 52c, 53a, 53b and 53c is summarized in Table II and Table III below, wherein "Inf" designates a lower transistor 56, "Sup" "designates an upper transistor 54," P "designates a transistor-pitch, and" F "designates a transistor with a fault. ' TABLE II It should be noted that because the windings Al, Bl, and Cl of the motor 28 have a short direct current, as well as the windings A2, B2, and C2, only one midpoint detector is required per winding set (one detector). medium point for the set of windings Al, Bl, and Cl and a midpoint detector for the set of windings A2, B2, and C2) as shown in Figure 8. In addition, although Figure 8. In addition, although Figure 8 shows that the mid-point detectors 68 and 69 are connected to the windings Bl and B2, respectively, the mid-point detectors 68 and 69 can alternatively be connected to the windings Al and A2, respectively, or to the windings Cl and C2, respectively, or a combination thereof. It should also be noted that if the windings Al, Bl and Cl and the windings A2, B2, and C2 do not present direct current shorts, three mid-point detectors would be required per set of windings (one detector for each winding in the set). It should be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they are within the scope of the appended claims and their equivalents.

Claims (12)

1. An energy bridge for an electric vehicle propulsion system, comprising: a switching circuit including a first and a second switching element that can operate between "on" and "off" states; and a midpoint detector coupled to the switching circuit for independently and simultaneously monitoring the first and second switching elements to detect and isolate, thereby, a fault of at least one of the first and the. second switching elements, the midpoint detector capable of detecting and isolating a fault when the switching elements eet in the "on" or "off" states. The power bridge according to claim 1, wherein the midpoint detector detects a fault of at least one of the first and second switching elements upon detecting a voltage 'through at least one of the first and second switching elements. The power bridge according to claim 1, wherein the switching circuit comprises an isolated gate bipolar transistor (IGBT) switching circuit and wherein the first and second switching elements include first and second bipolar transistors of isolated door, respectively. The power bridge according to claim 3, wherein the first and second switching elements further include first and second diodes connected in parallel with the first and second insulated gate bipolar transistors, respectively, and wherein the element The bipolar gate transistor switching device also includes a capacitor connected in parallel with the first and second insulated gate bipolar transistors. The power bridge according to claim 1, wherein the midpoint detector includes a first voltage detector for detecting a voltage through the first switching element and a second switching element, and wherein the first detector of voltage produces a first output signal having a first value after detecting the voltage through the first switching element, and wherein the second voltage detector produces a second output signal having the second value after detecting the presence of the voltage through the second switching element. The power bridge according to claim 1, wherein the midpoint detector includes a first optocoupler circuit connected in parallel with the first switching element and a second optocoupler circuit connected in parallel with the second element switching. The power bridge according to claim 6, wherein the first opto-coupler circuit produces a first output signal having a first value when the first switching element is in the "off" state, and wherein the second opto-coupler circuit produces the first output signal having the first value when the second switching element is in the "on" state and produces the second output signal having the second value when the second switching element is in the second state of "off". The power bridge according to claim 3, wherein the midpoint detector includes a first opto-coupler circuit connected in parallel with the first bipolar isolated gate transistor and a second optocoupler circuit connected in parallel with the second isolated door bipolar transistor. The power bridge according to claim 8, wherein the first optocoupler circuit produces a first output signal having a first value when the first isolated gate bipolar transistor is in the "on" state and produces a second output signal having a second value when the first isolated gate bipolar transistor is in the "off" state, and wherein the second optocoupler circuit produces a first output signal having a first value when the second bipolar transistor The isolated gate is in the "on" state and produces the second output signal having a second value when the second isolated gate bipolar transistor is in the "off" state. 10. The energy bridge according to claim 1, which further comprises a door drive circuit for providing door drive signals for operating the first and second switching elements between the "on" and "off" states. 11. An energy bridge for an electric vehicle propulsion system, comprising: a plurality of switching circuits, each including a first and a second switching element that can operate between the "on" and "off" states ", - and a midpoint detector coupled to one of a plurality of switching circuits for independently and simultaneously monitoring the first and second switching elements to detect and isolate, by this, a fault of at least one of the loc. first and second switching elements, the midpoint detector capable of detecting and isolating a fault when the switching elements are in the "on" or "off" states. The power bridge according to claim 11, further comprising a plurality of gate drive circuits for providing gate drive signals for operating the respective ones of the first and second switching elements between the "on" states already paid" .