Method and apparatus for estimating semiconductor junction temperature

An apparatus for estimating a semiconductor junction temperature of a corresponding first and second semiconductor device coupled together to a common node to provide a positive portion and a negative portion, respectively, of an output current, the apparatus comprising:

• a current sensor coupled to the common node, the current sensor operative to sense said output current and to provide an output current signal indicative of the magnitude and polarity of said output current;
• a switching module coupled to the current sensor arid operative to provide the output current signal to a first output in the event that the output current signal has a positive polarity and to provide the output current signal to a second output in the event that the output current signal has a negative polarity;
• a positive channel processor coupled to the first output of the switching module to receive the output current signal and operative to provide a first temperature signal that is a function of the output current signal, wherein the first temperature signal is an estimate of the semiconductor junction temperature in the first semiconductor device;
• a negative channel processor coupled to the second output of the switching module to receive the output current signal and operative to provide a second temperature signal that is a function of the output current signal, wherein the second temperature signal is an estimate of the semiconductor junction temperature in the second semiconductor device;
• and
• an output module coupled to the positive and negative channels and receiving the first and second temperature signals therefore arid operative to compare the first and second temperature signals to a predetermined constant, and in the event that either the first or second temperature signals exceeds the predetermined constant, providing an output alarm signal indicating that the semiconductor junction is overheating in the corresponding first and second semiconductor device.

A method for estimating a semiconductor junction temperature of a corresponding first and second semiconductor device Coupled together to a common node to provide a positive portion and a negative portion, respectively, of an output current, the apparatus comprising:

• sensing the magnitude and polarity of the output current;
• switching the output current signal to a first output in the event that the output current signal has a positive polarity or to a second output in the event that the output current signal has a negative polarity;
• processing the magnitude and polarity of the sensed output current from the first output to provide a first temperature signal that is a function of the output current signal and is an estimate of the semiconductor junction temperature in the first semiconductor device;
• processing the magnitude and the polarity of the sensed output current from the second output to provide a second temperature signal that is a function of the output current signal and is an estimate of the semiconductor junction temperature in the second semiconductor device;
• and
• detecting whether the first and second temperature signals exceed a predetermined constant;
• and
• in the event that either the first and second temperature signals exceeds the predetermined constant, providing an output alarm signal indicative that the semiconductor junction in the is overheating in the corresponding first and second semiconductor device.

An apparatus for predicting a semiconductor junction temperature of a semiconductor device in a high power full bridge amplifier having first and second semiconductor devices coupled to a first output and providing positive and negative components of a first output current respectively, and third and fourth semiconductor devices coupled to the second output and providing positive and negative components of a second output current respectively, the apparatus comprising:

• first and second switching modules coupled to the first and second current sensors respectively, and each operative to provide the output current signal to a first output in the event that the output current signal has a positive polarity and to provide the output current signal to a second output in the event that the output current signal has a negative polarity;
• first and second positive channel processors coupled to the first output of the first and second switching modules respectively, each to receive the output current signal and each operative to provide a first temperature signal that is a function of the first and second output current signals respectively, wherein each of the first temperature signals is an estimate of the semiconductor junction temperature in the first and third semiconductor devices respectively;
• first and second negative channel processors coupled to the second output of the first and second switching modules, respectively, each to receive the respective output current signal and each operative to provide a second temperature signal that is a function of the output current signal, wherein the second temperature signal is an estimate of the semiconductor junction temperature in the second and fourth semiconductor devices respectively;
• and
• an output module coupled to the positive and negative channels and receiving the first and second temperature signals from each and operative to compare the first and second temperature signals from each to a predetermined constant, and in the event that any of the first or second temperature signals exceeds the predetermined constant, providing an output alarm signal indicative that the semiconductor junction in the is overheating in the corresponding first and second semiconductor device.

A method for estimating a temperature of a junction of a semiconductor device coupleable to an output node to provide an output current, the method comprising the steps of:

• providing a virtual current waveform, to a user input current module, the virtual current waveform having a magnitude and a polarity representative of the output current of the semiconductor device;
• taking an absolute value of the virtual current waveform;
• generating a virtual junction temperature signal by a processor, including the sub-steps of computing and summing individual components of virtual power losses in the junction as a function of the virtual current waveform and the absolute value of the virtual current waveform;
• comparing the virtual junction temperature signal to a predetermined constant;
• and
• in the event the virtual junction temperature signal exceeds the predetermined constant, providing an indication of potential semiconductor junction.

A system for estimating a semiconductor junction temperature of a corresponding semiconductor device coupled to an output node to provide an output current comprising:

• a processor and a memory, the memory containing program code, the processor being operative to execute program code contained within the respective memory;
• said program code within said memory being operative to:
• receive as an input the output current waveform;
• estimate the temperature of the semiconductor junction temperature in the semiconductor device as a function of the output current waveform;
• and
• compare the estimated temperature to a predetermined constant, and in the event that the temperature signal exceeds the predetermined constant, providing an output alarm signal indicative that the semiconductor junction in is overheating in the semiconductor device.