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V012024 • © 2024 Portescap. Specifications subject to change without notice.Therefore the motor regulation parameter R/k2 is directly related to the motor’s capability of converting electrical power to mechanical power. A lower value of R/k2 means better heat conversion. R/k2 values are usually in the same range for a motor family and are very good indicators of motor performance across different motor types.For example:22DCP types offer R/k2 values around 60 × 103/Nms. 22DCT types offer R/k2 values around 11 × 103/Nms.For the same package size (22 mm diameter, 32 mm length) and the same mechanical output power, the Athlonix 22DCT will have five times less joules losses and therefore better efficiency.To take into consideration thermal properties of the motor, we can compare the values for R/k2 × Rth which reflect the ability of a motor to convert electrical power to mechanical power and dissipate joule losses for a given job:R/k2[103/Nms] Rth = Rth rotor - body + Rth body - ambientR/k2 x Rth[°C x103/(Nm)2]22DCP 32G1 213P 60 28 168022DCT 32G1 226E 11 28 308The above table predicts best thermal behavior under load conditions for 22DCT motor. If we do the math, we will have the following parameters and results:22DCT 32G1 226Ek = 12.12 mNm/AI = τ/k + I0 = 0.53 A R0 = 1.7 ΩRth = 6 °C/W + (22 °C/W)/2 = 17 °C/WUsing the method of calculation as the previous example:Tcoil = 30 °C R30 °C = 1.75 ΩUrequired = 3.47 VPelec = 3.47 V × 0.53 A = 1.84 WPmech = 6 ×10-3 Nm × 2,000 rpm × 2π/60 rad-s-1/rpm = 1.26WPJoule = R30 °C × I2 = 1.75 Ω × 0.53 A2 = 0.49 WEfficiency = Pmech / Pelec = 1.26 W / 1.84 W = 68%.Selecting a motor with better R/k2 enabled us to more than double the efficiency. Thermal considerations are important for an optimal motor selection and to ensure best performance.During the whole exercise we could identify two solutions that meet the requirements. If efficiency was a critical parameter in the application (battery operation for example), the 22DCT is a more suitable option.227