The existing method for evaluating the derating characteristics is generally carried out with the use of a thermal cyclic chamber based on manufacturer requirements as there are no international standards pertaining to this characteristics test. This paper proposes an alternative test method which is developed for manufacturers and test laboratories across the world which can easily be adopted because of its advantages like low cost in terms of investment, practicality, accuracy and less time-consuming. The proposed alternate method for the temperature derating test is validated by carrying out the test on a three-phase 60 kW grid tie solar PV inverter with input DC MPPT voltage of 850 V. The experimental analysis and results show that during the power- temperature derating process, the variations in input DC voltage, output AC voltage, frequency, power factor, and voltage harmonics are constant. The variations were observed in the output AC current and input DC current showed a similar pattern by having maximum value during maximum continuous power delivery period i.e. 66 kW active power output and starts decreasing to 43 kW till the inverter tripped. It is concluded that the temperature difference (ΔT) between the external ambient air temperature and the internal ambient air temperature plays a major role in the power-temperature derating process of an inverter.

现有的评估降额特性的方法通常是根据制造商的要求使用热循环室进行的，因为没有与此特性测试相关的国际标准。本文提出了一种替代测试方法，该方法是为世界各地的制造商和测试实验室开发的，该方法具有投资成本低、实用性、准确性和耗时少等优点，易于采用。通过对输入直流 MPPT 电压为 850 V 的三相 60 kW 并网太阳能光伏逆变器进行测试，验证了所提出的温度降额测试替代方法。 实验分析和结果表明，在功率温度降额期间过程，输入直流电压、输出交流电压、频率的变化，功率因数和电压谐波是恒定的。在输出交流电流和输入直流电流中观察到的变化显示出类似的模式，在最大连续功率输送期间具有最大值，即 66 kW 有功功率输出，并开始下降到 43 kW，直到逆变器跳闸。得出的结论是，外部环境空气温度和内部环境空气温度之间的温差（ΔT）在逆变器的功率温度降额过程中起主要作用。