Revealing dynamic characteristics of the two-stage thermoelectric cooler under double-pulse excitation.

Conventional two-stage thermoelectric coolers (TECs) generally employ identical continuous pulse current waveforms. In this study, we for the first time systematically investigate double-pulse current excitation with different waveform shapes under thermal shock. By analyzing the double-pulse waveform combinations, the amplitude and width of the second pulse, as well as the intervals between thermal shock and the first pulse (Δt1) and between double-pulses (Δt2), we reveal their governing effects on the transient subcooling performance of TECs, including the minimum cold end temperature (Tc,min), the maximum overshoot temperature (Tc,max), the cold-holding time (thold), and the recovery time (trec). The results show that the cold end waveform influences the transient response more strongly than the hot end, and triangular excitation effectively suppresses overshoot and accelerates recovery. Specifically, compared with the Square + Square case, the Triangle + Triangle case reduces Tc,max from 347.23 K to 325.31 K and shortens trec from 82.96 s to 75.47 s, while thold increases from 0.66 s to 0.84 s. Increasing the second pulse amplitude enhances cooling but intensifies Joule heating, and an excessively long second pulse width significantly degrades recovery. In addition, larger Δt2 promotes heat dissipation between pulses. For example, increasing Δt2 from 1 s to 3 s reduces Tc,max from 336.15 K to 316.05 K and shortens trec from 69.10 s to 63.50 s. These findings provide theoretical guidance for waveform design and parameter selection of two-stage TECs under thermal shock.