Supercharging system, control device for supercharging system, and method for operating supercharging system

Abstract

A supercharging system includes: a first supercharger including a first compressor for compressing air to be supplied to an engine and a motor for driving the first compressor; a leakage current measuring part for measuring a leakage current of the motor; and a first controller for controlling the first supercharger. The first controller includes a motor control part configured to, when a measurement result by the leakage current measuring part is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold, and to control an output of the motor within a range which does not exceed the upper limit value.

1 . A supercharging system, comprising:
 a first supercharger including a first compressor for compressing air to be supplied to an engine and a motor for driving the first compressor;   a leakage current measuring part for measuring a leakage current of the motor; and   a first controller for controlling the first supercharger,   wherein the first controller includes a motor control part configured to, if a measurement result by the leakage current measuring part is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold, and to control an output of the motor within a range which does not exceed the upper limit value.   
     
     
         2 . The supercharging system according to  claim 1 ,
 wherein the motor control part is configured to:
 set, if the measurement result is not less than the first threshold and less than a second threshold which is greater than the first threshold, the upper limit value of the output command value for the motor to be greater than zero and smaller than when the measurement result is less than the first threshold; and 
 set, if the measurement result is not less than the second threshold, the upper limit value of the output command value for the motor to zero. 
   
     
     
         3 . The supercharging system according to  claim 1 ,
 wherein the first supercharger further includes:
 a first turbine configured to be capable of being rotary driven by exhaust gas from the engine and by the motor; and 
 a first nozzle vane configured to adjust a flow path area of the exhaust gas flowing into the first turbine, 
   wherein the first controller further includes a first vane control part for controlling an opening degree of the first nozzle vane on the basis of a measurement result of the leakage current measuring part, and   wherein the first vane control part is configured to, if the measurement result by the leakage current measuring part is not less than the first threshold, control an opening degree of the first nozzle vane so as to reduce the flow path area compared to when the measurement result is less than the first threshold, in response to reduction of the upper limit value of the output command value for the motor by the motor control part.   
     
     
         4 . The supercharging system according to  claim 3 ,
 wherein the first vane control part is configured to determine a first target opening degree of the first nozzle vane on the basis of a difference between a boost pressure by the supercharging system and a target boost pressure, and to control the opening degree of the first nozzle vane to the first target opening degree.   
     
     
         5 . The supercharging system according to  claim 4 ,
 wherein the first vane control part is configured to obtain a first corrected opening degree by correcting the first target opening degree, corresponding to a reduction amount of the output command value for the motor by the upper limit value, and to control the opening degree of the first nozzle vane to the first corrected opening degree.   
     
     
         6 . The supercharging system according to  claim 1 , further comprising:
 a second supercharger including a second compressor for compressing air to be supplied to the engine, a second turbine configured to be rotary driven by exhaust gas from the engine to drive the second compressor, and a second nozzle vane configured to adjust a flow path area of the exhaust gas flowing into the second turbine; and   a second controller for controlling the second supercharger,   wherein one of the first supercharger or the second supercharger is a low-pressure stage supercharger,   wherein the other one of the first supercharger or the second supercharger is a high-pressure stage supercharger configured to further compress air which is compressed by the compressor of the low-pressure stage supercharger and to supply the air to the engine, and   wherein the second controller includes a second vane control part configured to, if the measurement result by the leakage current measuring part is not less than the first threshold, control an opening degree of the nozzle vane so as to reduce the flow path area compared to when the measurement result is less than the first threshold, in response to reduction of the upper limit value of the output command value for the motor by the motor control part.   
     
     
         7 . The supercharging system according to  claim 6 ,
 wherein the second vane control part is configured to determine a second target opening degree of the second nozzle vane on the basis of a difference between a boost pressure by the supercharging system and a target boost pressure, to control the opening degree of the second nozzle vane to the second target opening degree.   
     
     
         8 . The supercharging system according to  claim 7 ,
 wherein the second vane control part is configured to obtain a second corrected opening degree by correcting the second target opening degree corresponding to a reduction amount of the output command value for the motor by the upper limit value, and to control the opening degree of the second nozzle vane to the second corrected opening degree.   
     
     
         9 . The supercharging system according to  claim 1 ,
 wherein the motor includes an inverter for converting a direct current voltage from a battery to a three-phase alternating current voltage and supplying the three-phase alternating current voltage to a motor winding, and   wherein the leakage current measuring part includes an ammeter capable of collectively measuring a three-phase alternating current between the inverter and the motor.   
     
     
         10 . The supercharging system according to  claim 1 ,
 wherein the motor includes an inverter for converting direct current voltage from a battery to three-phase alternating current voltage and supplying the three-phase alternating current voltage to a motor winding, and   wherein the leakage current measuring part includes an ammeter capable of collectively measuring going and returning direct current between the battery and the inverter.   
     
     
         11 . The supercharging system according to  claim 1 ,
 wherein the leakage current measuring part includes an insulation resistance meter capable of measuring an insulation resistance value of the motor.   
     
     
         12 . A control device for the supercharging system according to  claim 1 , the control device comprising a first controller which includes a motor control part configured to, if a measurement result by the leakage current measuring part is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold, to control an output of the motor within a range which does not exceed the upper limit value. 
     
     
         13 . A method of operating a supercharging system which comprises a first supercharger including a first compressor for compressing air to be supplied to an engine and a motor for driving the first compressor, the method comprising:
 a leakage current measuring step of measuring a leakage current of the motor;   an output upper-limit-value setting step of setting, if a measurement result in the leakage current measuring step is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold; and   an output control step of controlling an output of the motor within a range which does not exceed the upper limit value set in the output upper-limit-value setting step.