1. Field of the Invention
The present invention relates to a power semiconductor module, and in particular to a power semiconductor module having a detector for detecting main circuit current passing through a power semiconductor element. The present invention also relates to a system for determining the main circuit current.
2. Description of the Related Art
Conventionally, there has been known a power semiconductor module in which main circuit current passing through a power semiconductor element is detected in order to prevent a breakdown of the element due to overcurrent or to feedback control an external load, as disclosed in, for example, Japanese Patent Publication No. 6-112614.
In general, in order to detect main circuit current through a power semiconductor element, a current detection resistance or shunt resistance is provided in a passage of the main circuit current. By measuring a voltage drop V generated across the shunt resistance, the main circuit current I is calculated as V/R. R is an ohmic value of the shunt resistance.
However, cost and power loss associated with the shunt resistance are high. Also, regardless of where the shunt resistance is located, i.e. within or outside the module, the size of a wiring area becomes greater because of the shunt resistance. Further, since the circuit becomes complicated, the cost of the module is increased.
In addition, where a fast switching element such as IGBT (Insulated Gate Bipolar Transistor) is used as power semiconductor element, inductance of the wiring of the module need to be reduced in order to, for example, protect the element.