TEMPERATURE CALCULATION OF IGBT MODULE FREQUENCY CONVERTOR AT START OF INDUCTION MOTOR

Abstract

The most effective and economical way to a smooth start and control the rotor speed of the induction motor is to change the frequency of the voltage supply. During acceleration of the motor it is necessary to ensure not only the actuator static torque, and the dynamic inertia overcoming. Thus, the value of the dynamic moment of inertia depends on the time of increasing the motor rotational speed. To overcome this dynamic torque on the engine during acceleration, stator windings create additional magnetic field due to increase current consumption. Typically, it is desirable that the duration of the engine acceleration was minimal, i.e. , the acceleration is maximized. This may cause excessive increase in the output current of the frequency converter and damage of bipolar transistors with insulated gate (IGBT), which power switches are used. To ensure reliable operation of AC Drivers the method to perform calculations to determine the type of IGBT module, temperatures structures of transistor and inverse diode of the inverter, when starting the engine, depending on the load torque and the moment of inertia of the actuator is proposed. Method for determination of the values of the polynomials coefficients that approximate energy IGBT switching losses and reverse diode recovery losses depending on the value of the collector current IGBT is proposed. A method for determination of the required values of heat sink thermal resistance, which cool IGBT module is proposed. Charts of the transistor temperature dependence and inverse diode values of the acceleration duration and of induction motor inertia – the actuator are shown.