Patent Publication Number: US-10784800-B2

Title: Signal control apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a signal control circuit, and more particularly to a signal control apparatus used in a power conversion device that controls a rotating electric machine that generates driving force of a vehicle. 
     BACKGROUND ART 
     An electric control apparatus includes a microcomputer (main microcomputer  20  in PTL 1) and an output control unit (sub microcomputer  30  and latch circuit  40  in PTL 1) and controls a load output signal (relay  50  in PTL 1). 
     In a case where there is an abnormality in the microcomputer, the microcomputer is reset by a reset signal (RESET  11  in PTL 1). During the period, a state of the load output signal is maintained by the output control unit. 
     PTL 1 aims to prevent a failure due to continuous ON/OFF of the load output signal (relay  50 ). 
     However, it has been insufficient to secure reliability after the control of the microcomputer  100  recovers from the time of various abnormalities. 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2008-223692 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     An object of the present invention is to improve reliability after the control of a microcomputer recovers. 
     Solution to Problem 
     A signal control apparatus according to the present invention includes a microcomputer, an output control unit that receives a reset signal and a load control signal from the microcomputer and outputs a load output signal to a load, and when the output control unit receives the reset signal, the output control unit maintains a state of the load output signal immediately before the reset signal is received, and when the load control signal is switched, the output control unit releases the maintaining state of the load output signal. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to improve the reliability after the control of the microcomputer recovers. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to the present embodiment. 
         FIG. 2  is a block configuration diagram of an output control unit  200 . 
         FIG. 3  is a timing chart of each signal illustrated in  FIG. 1 . 
         FIG. 4  is a table illustrating a state corresponding to each timing in  FIG. 3 . 
         FIG. 5  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to a second embodiment. 
         FIG. 6  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to a third embodiment. 
         FIG. 7  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to a fourth embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments according to the present invention will be described with reference to  FIG. 1  or figures. 
     First Embodiment 
       FIG. 1  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to the present embodiment. 
     The motor control circuit  1  according to the present embodiment includes a battery power supply  10 , an ignition switch  20 , a ground line  30  connected to the battery power supply  10 , a transistor  50  controlled by a load output signal  210 , a microcomputer  100  that outputs a motor control signal  120  that is a pulse width modulation (PWM) signal for converting a direct current power supply into an alternating-current signal, a reset signal  130 , and a load control signal  110 , a output control unit  200  that outputs the load output signal  210 , a load  300  controlled by the transistor  50 , and a reset control unit  400  incorporated in the microcomputer  100 . 
     The gate control circuit  2  includes a gate drive unit  500 , an insulated gate bipolar transistor (IGBT) control signal  510 , an IGBT  600 , and a high voltage battery  700 . 
     The microcomputer  100  controls the load control signal  110  and the motor control signal  120 . 
     For example, a main function is to control a motor  800  by the motor control signal  120  via the gate drive unit  500  and the IGBT  600 . 
     The load control signal  110  is a signal for switching the load  300  to ON or OFF when the microcomputer  100  is not in a reset period and in an initialization period. For example, when the voltage is 5 V, the load  300  is turned on, and when the voltage is 0 V, the load  300  is turned off. 
     The motor control signal  120  is a signal that controls a U-phase of the motor  800 , a signal that controls a V-phase and a signal that controls a W-phase. 
     The output control unit  200  outputs the load output signal  210  in accordance with the reset signal  130  and the load control signal  110 . The load output signal  210  turns on or off the load  300  by turning on or off the transistor  50 . 
     The load  300  is subjected to ON/OFF control by the load output signal  210  from the output control unit  200 . For example, the load  300  controls ON/OFF of a power supply of the gate drive unit  500  in accordance with the load output signal  210 . In the present embodiment, the load  300  is a power supply unit of the gate drive unit  500 . 
     The reset control unit  400  controls the reset signal  130  and includes, for example, a power supply integrated circuit (IC). The reset control unit  400  monitors a state of the battery power supply  10  via the ignition switch  20  and issues the reset signal  130  when the voltage decreases. 
     The reset signal  130  issues a reset in a case where there is an abnormality in the control of the microcomputer  100 . The reset signal  130  is notified to the microcomputer  100  and the output control unit  200 . As for the reset signal  130 , High represents a normal state and Low represents a reset state. 
     The gate drive unit  500  drives the motor  800  by controlling the IGBT  600  by the IGBT control signal  510  in accordance with the motor control signal  120  from the microcomputer  100 . The IGBT control signal  510  is a signal that controls the IGBT  600  to be ON and OFF and includes a total of six signals of a U-phase upper arm, a U-phase lower arm, a V-phase upper arm, a V-phase lower arm, a W-phase upper arm, and a W-phase lower arm in order to control the motor  800 . 
     The IGBT  600  is a switch for passing a current to the motor  800  and is controlled by the IGBT control signal  510 . 
     The high voltage battery  700  is a power supply for driving the motor  800 . The motor  800  is a motor for driving a vehicle. 
     The battery power supply  10  supplies a power supply to the microcomputer  100  and the reset control unit  400  via the ignition switch  20 . The battery power supply  10  includes, for example, a 12 V lead battery mounted on the vehicle. The battery power supply  10  supplies a power supply to the load  300 . 
     The ignition switch  20  shuts off the supply of the battery power supply  10  to the microcomputer  100  and the reset control unit  400 . The ignition switch  20  includes, for example, a key switch of the vehicle and is turned on when the vehicle is started up and turned off when the vehicle is stopped. 
     A gatedrive power supply line  40  is a control power supply line to the gate drive unit  500 . The transistor  50  turns on and off the load  300  by the load output signal  210 . 
       FIG. 2  is a block configuration diagram of the output control unit  200 . 
     The output control unit  200  includes a pull-up resistor  201 , a NOT element  202 , an AND element  203 , a flip-flop  204 , an OR element  205 , a pull-down resistor  206 , a reset input terminal  207 , a load control signal input terminal  208 , and a load output signal terminal  209 . 
     The pull-up resistor  201  sets an initial value of the reset signal  130  input to the reset input terminal  207  to High. 
     The Not element  202  inverts the reset signal  130  input to the reset input terminal  207 . 
     The AND element  203  outputs a state of the load output signal  210  output to the load output signal terminal  209  when the reset signal  130  input to the reset input terminal  207  is Low. 
     The flip-flop  204  outputs an output signal of the AND element  203  at the fall timing of the load control signal  110  input to the load control signal input terminal  208 . 
     The OR element  205  subjects the output signal of the flip-flop  204  and the load control signal  110  input to the load control signal input terminal  208  to OR. 
     A pull-down resistor  206  sets an initial value of the load control signal  110  input to the load control signal input terminal  208  to Low. 
       FIG. 3  is a timing chart of each signal illustrated in  FIG. 1 . 
     (1) Ignition illustrates a state of the ignition switch  20 . The example of  FIG. 3  illustrates that the ignition switch  20  is ON at High and the ignition switch  20  is OFF at Low. 
     (2) Load control signal  110  illustrates a state of the load control signal  110 . 
     (3) Reset signal  130  illustrates a state of the reset signal  130 . The example of  FIG. 3  illustrates a normal state at High and a reset state at Low. 
     (4) Load output signal  210  illustrates a state of the load output signal  210 . The example of  FIG. 3  illustrates that the load is ON at High and the load is OFF at Low. 
     Timing  1001  illustrates a start timing of the vehicle. At timing  1002 , when the load control signal  110  is switched to ON, the load output signal  210  changes from a state of maintaining an immediately preceding state to an ON state. 
     Timing  1003  illustrates that when the reset state is entered, that is, when the reset signal  130  turns to Low, the load output signal  210  maintains the immediately preceding state. The timing  1003  illustrates a state in which the output of the microcomputer  100  becomes unstable, but the load control signal  110  turns to OFF by the pull-down resistor  206 . 
     Timing  1004  illustrates a state in which the load output signal  210  maintains the previous state when reset is released, that is, when the reset signal  130  turns to High. The timing  1004  illustrates a state in which the output of the microcomputer  100  becomes unstable because the output is being initialized but the load control signal  110  turns to OFF by the pull-down resistor  206 . 
     Timing  1005  illustrates a state in which since the load control signal  110  turns to ON after the output of the microcomputer  100  is initialized, the load output signal  210  turns to ON. 
     At timing  1006 , when the load control signal  110  is switched to OFF, the load output signal  210  changes from the state of maintaining the immediately preceding state to an OFF state. 
     At timing  1007 , when the reset state is entered, that is, when the reset signal  130  turns to Low, the load output signal  210  maintains the immediately preceding state. The timing  1007  illustrates a state in which the output of the microcomputer  100  becomes unstable, but the load control signal  110  turns to OFF by the pull-down resistor  206 . 
     At timing  1008 , when the reset is released, that is, when the reset signal  130  turns to High, the load output signal  210  maintains the immediately preceding state. 
     At timing  1009 , when the load control signal  110  is switched to ON, the load output signal  210  changes from the state of maintaining the immediately preceding state to a state of turning to ON. 
       FIG. 4  is a table illustrating a state corresponding to each timing in  FIG. 3 . 
     In a normal state  2001 , when the reset signal is High and the load control signal input terminal is ON, the load output signal turns to ON. The normal state  2001  illustrates a state from the timing  1002  to  1003  in  FIG. 3  and a state from the timing  1005  to  1006 . 
     In a reset state  2002 , when the reset signal turns to Low, an immediately preceding state of the load output signal is maintained. The reset state  2002  illustrates the state from the timing  1003  to  1004  in  FIG. 3 . 
     In an initial processing state  2003 , since timing at which the maintaining state of the load output signal is released is when the load control signal is switched, the reset signal turns to High, but the immediately preceding state of the load output signal is maintained. The initial processing state  2003  illustrates a state from the timing  1004  to  1005  in  FIG. 3 . 
     In a normal state  2011 , when the reset signal is High and the load control signal input terminal is OFF, the load output signal turns to OFF. The normal state  2011  illustrates a state from the timing  1001  to  1002  in  FIG. 3  and the state from the timing  1006  to  1007 . 
     In a reset state  2012 , the immediately preceding state of the load output signal is maintained when the reset signal turns to Low. The reset state  2012  illustrates a state from the timing  1007  to  1008  in  FIG. 3   
     In an initial processing state  2013 , since timing at which the maintaining state of the load output signal is released is when the load control signal is switched, the reset signal turns to High, but the immediately preceding state of the load output signal is maintained. The initial processing state  2013  illustrates a state from the timing  1008  to  1009  in  FIG. 3 . 
     Since the microcomputer  100  cannot control the load output signal  210  in the reset state, the state of the load output signal  210  immediately before the reset signal  130  is received, and after the control of the microcomputer  100  recovers, that is, after the load control signal  110  is switched, the maintaining state of the load output signal  210  is released. 
     Therefore, even after the control of the microcomputer  100  recovers, the load  300  by the load output signal  210  can be continuously controlled. 
     Second Embodiment 
       FIG. 5  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to a second embodiment. A difference from the first embodiment is that a reset control unit  400  is configured to be separated from a microcomputer  100  and receives supply of power from a battery power supply  10  that is the power supply of the microcomputer  100 . 
     The reset control unit  400  controls a second reset signal  410 . The reset control unit  400  includes, for example, a power supply IC and monitors a state of the battery power supply  10  via an ignition switch  20  and transmits the second reset signal  410  when a voltage decreases. 
     As a result, by monitoring a power supply voltage of the microcomputer  100 , it is diagnosed whether the control of a load control signal  110  is correct. For example, in a case where the power supply voltage decreases, since the microcomputer  100  includes a logic circuit, a threshold specification of the logic circuit cannot be satisfied. That is, the load control signal  110  cannot be correctly controlled. 
     In addition, in the present embodiment, by separating power supplies of the microcomputer  100  and an output control unit  200 , it is possible to maintain a mode at the output control unit  200  while the power supply voltage of the microcomputer  100  is decreasing and to continue a process even after recovery. Therefore, abnormal control of a load caused by a decrease the power supply voltage or the like is prevented. A user can avoid stopping the control at an unintended timing. 
     Third Embodiment 
       FIG. 6  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to the third embodiment. A difference from the second embodiment is that a microcomputer  100  includes a first control unit  101  and a second control unit  102 . 
     The first control unit  101  controls a motor control signal  120 . The second control unit  102  controls a load control signal  110 . 
     A monitoring signal  420  periodically communicates with the first control unit  101  of the microcomputer  100  and monitors an abnormality of the first control unit  101 . For example, the monitoring signal  420  causes the microcomputer  100  to calculate an example and in a case where an answer is incorrect, a second reset signal  410  is transmitted. There is general-purpose serial peripheral interface (SPI) serial communication or the like. 
     As a result, in a case where there is an abnormality in the first control unit  101  that controls the motor control signal  120  of the microcomputer  100 , a reset control unit  400  monitors the first control unit  101  with the monitoring signal  420 , thereby being able to suppress runaway of a motor  800  controlled by the motor control signal  120 . 
     In addition, even after the control of the microcomputer  100  illustrated in the first embodiment or the second embodiment recovers, a load  300  by a load output signal  210  can be continuously controlled. 
     Therefore, after stopping the runaway of the microcomputer  100 , it is possible to continue the motor control process even after the recovery and as a result, reliability improves. 
     Fourth Embodiment 
       FIG. 7  is a block configuration diagram of a motor control circuit and a gate control circuit  2  according to a fourth embodiment. 
     A contactor  750  shuts off connection with a high voltage battery  700 . For example, in a case where an abnormal current flows in a motor  800 , the contactor  750  is shut off by the control of a microcomputer  100 . 
     A smoothing capacitor  751  is a smoothing circuit for converting a PWM signal that controls a motor into an alternating current. 
     A discharge resistor  752  is a resistor for removing the residual charge of the smoothing capacitor  751 . A discharge switch  753  is turned on when the contactor  750  is OFF. In addition, the discharge switch  753  turns to OFF when the contactor  750  is ON. 
     A NOT element  754  inverts the control of the contactor  750  to control the discharge switch  753 . A contactor control signal  310  is controlled by a load output signal  210 . 
     The smoothing capacitor  751  plays an important role in converting a direct current into an alternating current. However, it is necessary to remove the residual electric charge accumulated in the smoothing capacitor  751  except during traveling such as when the motor is stopped or at the time of an abnormality. 
     A control circuit in a case where there is an abnormality in the gate control circuit  2  includes the contactor  750 , the discharge resistor  752 , the discharge switch  753 , and the NOT element  754 . In a case where there is an abnormality in the gate control circuit  2 , by simultaneously turning off the contactor  750  and turning on the discharge switch  753 , the electric charge accumulated in the smoothing capacitor  751  is discharged, and the circuit is released from a state in which a high voltage is applied. 
     In other words, since the control by the load output signal  210  in the microcomputer  100  can be continued, the residual charge remaining in the smoothing capacitor  751  can be removed and more safe control can be performed. 
     In addition, the output control unit  200  has a function of counting a reset signal  130  and turns off the load output signal  210  in a case where there is a count of a predetermined value on the basis of this count function. 
     In a case where an abnormality of the microcomputer  100  occurs a plurality of times and recovery cannot be achieved, by turning off the load output signal  210  to shut off a circuit, it is possible to further improve the reliability. 
     REFERENCE SIGNS LIST 
     
         
           1  motor control circuit 
           2  gate control circuit 
           10  battery power supply 
           20  Ignition switch 
           30  grand line 
           40  gatedrive power supply line 
           50  transistor 
           100  microcomputer 
           101  first control unit 
           102  second control unit 
           110  load control signal 
           120  motor control signal 
           130  reset signal 
           200  output control unit 
           201  pull-up resistor 
           202  NOT element 
           203  AND element 
           204  flip-flop 
           205  OR element 
           206  pull-down resistor 
           207  reset input terminal 
           208  load control signal input terminal 
           209  load output signal terminal 
           210  load output signal 
           300  load 
           400  reset control unit 
           410  second reset signal 
           420  monitoring signal 
           500  gate drive unit 
           510  IGBT control signal 
           600  IGBT 
           700  high voltage battery 
           750  contactor 
           751  smoothing capacitor 
           752  discharge resistor 
           753  discharge switch 
           754  NOT element 
           800  motor 
           1001  timing 
           1002  timing 
           1003  timing 
           1004  timing 
           1005  timing 
           1006  timing 
           1007  timing 
           1008  timing 
           1009  timing