Patent Publication Number: US-2007096684-A1

Title: Apparatus for controlling electric power for electric vehicle

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an apparatus for controlling electric power for an electric vehicle. More particularly, the present invention relates to an engine control apparatus for preventing malfunction of the control unit and battery management system when auxiliary battery power and power from an ignition switch are applied.  
      2. Description of the Related Art  
      Control systems of current electric vehicles can experience a number of problems. For example, because a first reset portion of the control circuit can output voltage in the form of an exponential function because of a charging/discharging characteristic of circuit capacitors, a problem can occur in that the width of the control reset signal is unstable. Therefore, the reset signal is not detected consistently by the controller.  
      In addition, in a case in which the reset signal in a state of active “low” is supplied to the controller, because the reset signal occurs after a long length of time in which the output between capacitors of a first reset portion and the output of capacitors of a second reset portion are added to each other, a problem can occur in that the operating time of the engine control apparatus is delayed.  
      Therefore, because initializing communication time after resetting becomes long with respect to the torque control unit (TCU), the hybrid control unit (HCU), the battery control unit (BCU), and so on of the electric vehicle, a problem can occur in that rapid response to a request for driving cannot be supplied. In addition, in a case in which the ignition switch is turned on repeatedly during the power ratchet period, a problem can occur in that durability of certain sensors and actuators is reduced. Moreover, in a case in which the power of the main battery is cut off by the ignition switch, a problem can occur in that the voltage from the MCU and BCU are wrongly detected so a self-diagnosis code is output.  
      The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.  
     SUMMARY OF THE INVENTION  
      Embodiments of the present invention provide an apparatus for controlling electric power for an electric vehicle having advantages of stable communication between control apparatuses. An exemplary apparatus for controlling electric power for an electric vehicle according to an embodiment of the present invention includes a stand-by power generating portion for generating stand-by power by utilizing auxiliary battery power applied from an auxiliary battery and outputting a micro control unit (MCU) reset signal for resetting an MCU in a case in which an MCU reset signal output condition exists, an operating power generating portion for generating operating power supplied to a power consuming device by utilizing power applied from the stand-by power generating portion in a case in which an operating power generating condition exists, and an operation control portion for operating to form the MCU reset signal output condition and the operating power generating condition on the basis of an ignition switch signal and a main relay signal, wherein the operation control portion operates to form the MCU reset signal output condition only when the ignition switch is turned on in a state in which the main relay signal is in an off state, and wherein the operation control portion operates to form the operating power generating condition in a case in which at least one of the main relay signal and the ignition switch signal is in an on state. The stand-by power generating portion comprises a regulator for regulating the stand-by voltage to be constant, and the regulator comprises a reset terminal configured to output an MCU reset signal and a delay terminal for outputting current to the operation control portion. The operating power generating portion comprises a regulator for regulating a voltage of power supplied to the power consuming devices to be constant, wherein the regulator comprises an enable terminal for receiving a signal from the operation control portion and maintains a voltage of an output power to be constant if a signal indicative of existence of the operating power generating condition is input to the enable terminal. The operation control portion comprises a diode unit for receiving the ignition switch signal and main relay signal in parallel and processing said signals, a capacitor electrically connected to the delay terminal of the stand-by power generating portion to be charged by the current output from the delay terminal, a differential circuit for differentiating a signal output from the diode unit and outputting a differentiated signal, and a transistor comprising a base terminal for receiving the signal output from the differential circuit, a collector terminal connected to the capacitor, and an emitter terminal connected to a ground, and discharging the current of the capacitor by being turned on by the signal output from the differential circuit. The differential circuit temporarily turns on the transistor on the basis of the signal transmitted from the diode unit in a case in which the reset signal output condition has occurred. A diode is connected to the base terminal of the transistor of the operation control portion so as to prevent a negative edge of the signal output from the differential circuit from being applied to the transistor. The regulator generates the MCU reset signal until the capacitor is recharged by the current output from the delay terminal, in a case in which the current of the capacitor is discharged. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic drawing illustrating a power control apparatus of an electric vehicle according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      An embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.  
      As shown in  FIG. 1 , according to an exemplary embodiment of the present invention, an electric power control apparatus of an electric vehicle includes a stand-by power generating portion  10 , an operating power generating portion  20 , and an operation control portion  30 . The stand-by power generating portion  10  generates stand-by power by utilizing auxiliary battery power applied from an auxiliary battery  401 , and outputs a micro control unit (MCU) reset signal for resetting an MCU  40  in a case in which an MCU reset signal output condition exists.  
      The term MCU used in an exemplary embodiment of the present invention generally refers to a control unit including a central processing unit (CPU). The CPU may include a processor, memory and associated hardware, software and/or firmware as may be selected and programmed by a person of ordinary skill in the art based on the teachings of the present invention.  
      The operating power generating portion  20  generates operating power supplied to a power consuming device  420  by utilizing power applied from the stand-by power generating portion  10  in a case in which an operating power generating condition exists.  
      The operation control portion  30  operates to form the MCU reset signal output condition and the operating power generating condition on the basis of an ignition switch signal and a main relay signal, wherein the operation control portion operates to form the MCU reset signal output condition only when the ignition switch is turned on when the main relay signal is in an off state, and wherein the operation control portion operates to form the operating power generating condition in a case in which at least one of the main relay signal and the ignition switch signal is in an on state.  
      The stand-by power generating portion  10  includes a regulator U 1  which regulates stand-by voltage to be constant, and the reset signal is for booting the MCU  40 . More particularly, the reset signal output condition is a case in which the ignition switch signal is detected when a signal from the main relay  403  does not exist. In addition, the operating power generating condition is a case in which at least one signal of the main relay signal or the ignition switch signal is input to the MCU.  
      A detailed description of the operation of the operation control portion  30  on the basis of reset signal output condition and operating power generating condition is given later.  
      In a case in which the power of the auxiliary battery  401  is supplied, the regulator U 1  of the stand-by power generating portion  10  generates the stand-by power and supplies the power to respective control units. According to an exemplary embodiment of the present invention, the stand-by power is realized as 5 volts (V).  
      As also shown in  FIG. 1 , the stand-by power is supplied through terminal V 5 , and the respective control units are realized as elements, for example, a memory of the control unit which is always turned on.  
      The regulator U 1  includes a reset terminal RST configured to output the MCU reset signal, and a delay terminal DLY. In addition, the regulator U 1  may include a reset signal generator. The reset signal generator generates a reset signal in the regulator U 1 .  
      When the power of the auxiliary battery  401  is initially supplied, in a state in which the stand-by power is output, the regulator U 1  outputs a reset signal in a state of active “low” through the reset terminal RST and transmits the signal to the MCU  40  through the resistor R 4 .  
      In addition, the regulator U 1  outputs current to the operation control portion  30  through delay terminal DLY. More particularly, the regulator U 1  outputs the current and charges a capacitor C 4  of the operation control portion  30 . At that point, if the capacitor C 4  is fully charged, the regulator U 1  transmits a reset signal in a state of an active “high” output from the reset terminal to the MCU  40  RST through a resistor R 4 .  
      The reset signal in the state of active “low” is for booting the MCU  40  which is generated at the reset signal output condition, and the reset signal in the state of active “high” is for maintaining an operation of the MCU  40  which is generated at the operating power generating condition.  
      The operating power generating portion  20  includes the regulator U 2 . The regulator U 2  regulates a voltage of the power which is supplied to the power consuming devices  420  to be constant, and the power consuming device  420  is connected to the VCC terminal VCC. Power consuming devices  420  are realized as elements that are turned on/off corresponding to the on/off of the ignition switch.  
      The regulator U 2  includes an enable terminal EN for receiving a signal from the operation control portion  30 , and it maintains a voltage of an output power to be constant if a signal indicative of existence of the operating power generating condition is input to the enable terminal EN. That is, the voltage of the auxiliary battery  401  is applied to an input terminal VI of the regulator U 2 , and the ignition switch signal and the main relay signal are input to the enable terminal EN of the regulator U 2 .  
      The regulator U 2  maintains the power of 5V on the basis of the input signal until an end of the power ratchet period such that the regulator U 2  prevent a malfunction of sensors and actuators related to the EMS.  
      The power ratchet period is a period corresponding to the operating power generating condition of an engine control unit connected to the main relay  403 , and it is a period of from 5 to 8 seconds in which the engine control unit is left on after the ignition switch signal is detected to change from on to off.  
      The operation control portion  30  includes a diode unit D 4 , a capacitor C 4 , a differential circuit  31 , and a transistor Q 1 . The diode unit D 4  receives the ignition switch signal and main relay signal in parallel and processes said signals. The capacitor C 4  is electrically connected to the delay terminal of the stand-by power generating portion  10 , to be charged by the current output from the delay terminal DLY. The differential circuit  31  differentiates a signal output from the diode unit D 4  and outputs the differentiated signal.  
      The transistor Q 1  includes a base terminal  415  for receiving the signal output from the differential circuit  31 , a collector terminal  410  connected to the capacitor C 4 , and an emitter terminal  413  connected to a ground  421 . The transistor Q 1  discharges the current of the capacitor C 4  by being turned on by the signal output from the differential circuit  31 . According to an exemplary embodiment of the present invention, the diode unit D 4  is realized as an OR gate.  
      Therefore, if one or more signals of the ignition switch signal or the main relay signal is input to the diode unit D 4 , the diode unit D 4  generates a signal. The signal generated in the diode unit D 4  is transmitted to the enable terminal EN of the operating power generating portion  20 , and is simultaneously transmitted to the differential circuit  31  including resistors R 2  and R 3  and a capacitor C 3 . That is, the operating power generating portion  20  supplies the power to the power consuming device  420  on the basis of the signal transmitted from the diode unit D 4  to the operating power generating portion  20 .  
      In the case in which the reset signal output condition occurs, the differential circuit  31  temporarily turns on the transistor Q 1  on the basis of the signal transmitted from the diode unit D 4 .  
      The signal of the diode unit D 4  transmitted to the differential circuit  31  is selectively output to the base terminal  415  of the transistor Q 1  by the differential circuit  31 . That is, the differential circuit  31  outputs the signal only in a case in which the change in the signal transmitted from the diode unit D 4  exists. In another words, the signal output from the diode unit D 4  changes if the ignition switch  405  is turned on only when both the main relay  403  and the ignition switch  405  are off, i.e., the reset signal output condition occurs. At that time, the differential circuit  31  outputs the signal. In this case, the signal is input to the base terminal  415  of the transistor Q 1  and the transistor Q 1  is turned on.  
      The signals generated in the differential circuit  31  include a positive edge and a negative edge. The transistor Q 1  is temporarily turned on by the positive edge, and the negative edge is prevented by a diode D 5  connected to the base terminal  415  of the transistor Q 1 . Therefore, damage to the transistor Q 1  can be prevented.  
      Operation of the power control apparatus according to an exemplary embodiment of the present invention is described hereinafter.  
      If an initial power of the auxiliary battery  401  is supplied, that is, the auxiliary battery  401  is connected, the regulator U 1  of the stand-by power generating portion  10  outputs the power of the auxiliary battery  401  supplied through a diode DI as a stand-by power. The stand-by power is realized as a 5V power and is output through an output terminal Vo.  
      At that time, the regulator U 1  outputs the reset signal in the state of active “low” through the reset terminal RST, and the reset signal is applied to the MCU  40  through the resistor R 4 . Simultaneously, the regulator U 1  charges the capacitor C 4  of the operation control portion  30  by outputting the current through the delay terminal DLY.  
      If an equilibrium between a level of a charge voltage and an output current level by completing the charge of the capacitor C 4  exists, the regulator U 1  outputs the reset signal in the state of active “high” and it is applied to the MCU  40 .  
      At that time, there is no signal output from the main relay  403  or the ignition switch  405 , and if the ignition switch  405  is then turned on, a signal of the ignition switch  405  to the diode unit D 4  is supplied and the diode unit D 4  transmits the signal to the differential circuit  31 .  
      Then, because a positive signal (positive edge) output from the differential circuit  31  is input to the base terminal  415  of the transistor Q 1 , the transistor Q 1  is temporarily turned on.  
      At that time, the regulator U 1  of the stand-by power generating portion  10  outputs and supplies the reset signal in the state of active “low” to the MCU  40  in response to which the charge of the capacitor C 4  connected to the collector terminal  410  is discharged to a ground  420 .  
      In a case in which the current of the capacitor C 4  is discharged, the regulator U 1  generates an MCU reset signal until the capacitor C 4  is recharged. If the reset signal in the state of active “low” is transmitted to the MCU  40 , the main relay  403  is turned on for supplying the power of the main battery to the sensors and actuators related to the engine control unit.  
      Then, after the ignition switch  405  is turned off, because the signal of the main relay  403  is transmitted to the diode unit D 4  during the power ratchet period, the operating power generating portion  20  supplies the power to the VCC terminal VCC during the power ratchet period.  
      After the power ratchet period, if the ignition switch  405  is turned on, because the ignition switch signal is applied to the base terminal  415  of the transistor Q 1  via the differential circuit  31 , the current charged in the capacitor C 4  is discharged.  
      The regulator U 1  generates the MCU reset signal until the capacitor C 4  is recharged by the current output from the delay terminal DLY, in a case in which the current of the capacitor C 4  is discharged.  
      Therefore, after the power ratchet period is completed, if the ignition switch  405  is turned on just once, a reset signal having a square wave identical to the signal generated when the auxiliary battery  401  is connected is applied to the MCU  40 .  
      As described above, according to an exemplary embodiment of the present invention, from the time the ignition switch  405  is turned on to when the power ratchet period is completed, because the reset signal in the state of active “low” is supplied only once, communications between the MCU  40  and apparatuses connected to the MCU  40  can be stable.  
      In addition, because a reset period and a waveform are constantly maintained as the square wave under both auxiliary battery power and the power from the ignition switch, a communication starting time is constantly realized. Therefore, stable control can be realized.  
      In addition, because the reset signal in the state of active “low” is not generated even though the ignition switch is turned on during the power ratchet period after the ignition switch is turned off, unnecessary booting does not occur. Therefore, a malfunction between the MCU and a battery management system can be prevented. Furthermore, because the circuit is simplified, manufacturing costs can be reduced in addition to the reduction in malfunctions.  
      While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.