As the ambient temperature increases the switching transistors are the the elements which mostly suffer from the increasing the ambient temperature.

As the ambient temperatures increases the the rate of heat flow from the transistor to the ambient decreases. There is a derating factor of the allowed power dissipated in the device as the environmental temperature increases. This power derating curve is given in the data sheet of the power transistors.

As for the conversion efficiency it will not suffer much as the ambient temperatures is still in the allowed range. This is because the on resistance of the MOSFET transistors increases but the power dissipated in the transistor is still small compared to the load power.

One can consider that the loss deficiency is proportional to VL/VI= (Vi- Von)/Vi

where VL is the load voltage, Vi is the input voltage, Von is the on voltage of the MOS transistor switch. Von is the term that will increase with ambient temperature and so the efficiency will basically decrease. But this decrease is small if the transistor is operated within the allowed dissipated power.

A said before, you can derive an expression for the efficiency and quantify this problem. For the calculation of the loss efficiency please follow the paper in the link: Article “Computer-aided analysis of stepped sine wave inverters

Best wishes

Most of the energy transformed by a converter is dissipated within the active components (transistors, diodes) and inductors (copper and core energy losses). I'd say there is no specific general formula you are looking for, for all the converters.

The amount of energy loss mostly depends on:

. the topology of a given converter and its mode of operation (CCM, DCM),

. components used,

. cooling system used.

One can approach to calculate a heat dissipation model of a specific converter based on the energy loss calculations.

My regards, Adam.

As the ambient temperature increases the switching transistors are the the elements which mostly suffer from the increasing the ambient temperature.

As the ambient temperatures increases the the rate of heat flow from the transistor to the ambient decreases. There is a derating factor of the allowed power dissipated in the device as the environmental temperature increases. This power derating curve is given in the data sheet of the power transistors.

As for the conversion efficiency it will not suffer much as the ambient temperatures is still in the allowed range. This is because the on resistance of the MOSFET transistors increases but the power dissipated in the transistor is still small compared to the load power.

One can consider that the loss deficiency is proportional to VL/VI= (Vi- Von)/Vi

where VL is the load voltage, Vi is the input voltage, Von is the on voltage of the MOS transistor switch. Von is the term that will increase with ambient temperature and so the efficiency will basically decrease. But this decrease is small if the transistor is operated within the allowed dissipated power.

A said before, you can derive an expression for the efficiency and quantify this problem. For the calculation of the loss efficiency please follow the paper in the link: Article “Computer-aided analysis of stepped sine wave inverters

Best wishes

You may have a look on Article Effect of Ambient Temperature on Performance of Grid-Connect...

it depends on the reflectivity