System and method for measuring switching loss associated with semiconductor switching devices

Abstract

A method according to an exemplary aspect of the present disclosure includes, among other things, controlling a vehicle using switching loss information of a semiconductor switching device, the switching loss information derived from a conduction loss and a combined conduction and switching loss.

What is claimed is: 
     
         1 . A method, comprising:
 controlling a vehicle using switching loss information of a semiconductor switching device mounted on the vehicle, the switching loss information monitored by a switching loss measurement system and derived from a conduction loss and a combined conduction and switching loss.   
     
     
         2 . The method as recited in  claim 1 , wherein the step of controlling includes modifying an amount of thermal cooling that is communicated to cool the semiconductor switching device. 
     
     
         3 . The method as recited in  claim 1 , comprising calculating the conduction loss and the combined conduction and switching loss by:
 charging an inductor with energy from a capacitor;   performing a multitude of switching cycles; and   discharging the energy from the inductor into the capacitor.   
     
     
         4 . The method as recited in  claim 3 , comprising measuring voltages and currents associated with the capacitor and the inductor during each of the charging, performing and discharging steps. 
     
     
         5 . The method as recited in  claim 4 , wherein the voltages are measured using the following equation:
     V   C1 ( t )= L   1   dI ( t )/ dt+I ( t )*( R   IGBT1   +R   IGBT4   +R   L1 )   where   C 1 =the capacitor   L 1 =the inductor   IGBT 1 =a first switching unit   IGBT 4 =a fourth switching unit.   
     
     
         6 . The method as recited in  claim 4 , wherein the currents are measured using the following equation:
     I ( t )= I ( t   2 )* e   −(t)/τ       where     τ= L 1/( R   L1   +R   D2   +R   IGBT1 ).
   
     
     
         7 . The method as recited in  claim 1 , comprising deriving the switching loss information by subtracting the conduction loss from the combined conduction and switching loss. 
     
     
         8 . The method as recited in  claim 1 , wherein the conduction loss is expressed using the following equation:
     E   c =0.5* C   1 *[( V   C1(t0)   2   −V   C1−C(t4)   2 )].   
     
     
         9 . The method as recited in  claim 8 , wherein the combined conduction and switching loss is expressed using the following equation:
     E   C+SW =0.5* C   1 *[( V   C1(t0)   2   −V   C1−C+SW(t4)   2 )].   
     
     
         10 . The method as recited in  claim 9 , wherein the switching loss information is calculated using the following equation:
     E   SW =( E   C+SW )−( E   C ).
   
     
     
         11 . A semiconductor switching device, comprising:
 a switching loss measurement system including:
 a first measuring device connectable to a semiconductor circuit and configured to measure a voltage of a first energy storage device of said semiconductor circuit; 
 a second measuring device connectable to said semiconductor circuit and configured to measure a current of a second energy storage device of said semiconductor circuit; and 
 a control unit configured to monitor said semiconductor circuit and derive a switching loss associated with said semiconductor circuit based on voltage and current inputs from said first and second measuring devices. 
   
     
     
         12 . The device as recited in  claim 11 , wherein said control unit is configured to communicate said switching loss to a control system of an electrified vehicle. 
     
     
         13 . The device as recited in  claim 11 , wherein said semiconductor circuit includes a plurality of switching units configured in a H-bridge arrangement. 
     
     
         14 . The device as recited in  claim 11 , wherein said first energy storage device is a capacitor and said second energy storage device is an inductor. 
     
     
         15 . The device as recited in  claim 11 , wherein said control unit is configured to operate said semiconductor circuit in each of a conduction cycle and a conduction and switching cycle in order to calculate said switching loss.