Power resistors for power electronics applications
In power electronics, in addition to converter elements (semiconductor devices) - power switches and diodes, which primarily determine the quality indicators of converter devices, various passive components are also actively used - capacitors, inductances, protection elements, resistors and others. The scope of powerful resistances in power converters is quite wide: these are current-measuring shunts, discharge resistors, snubber elements, loads, braking resistors, and much more. It is not always reasonable or possible to replace them in these applications with active components, so the use of powerful power resistors will almost always be in demand.
One of the series of power resistors in demand in power electronics is the AH series from THUNDER and its analogues.
Appearance of AH series resistorsThe features of AH series power resistors are high power rating, small overall dimensions and high resistance accuracy, high performance stability, and reinforced structure for cooling and heat dissipation. Permissible operating temperature range - from -55°C to +275°C (with a reduction in maximum power). The most popular in our range are the following series of AH resistors:
| Name | Rated power | Resistance range | Accuracy class |
|---|---|---|---|
| AH-25 | 25 W | 0.1 ohm - 100 ohm | 5% |
| AH-50 | 50 W | 0.1 Ohm - 2.2 kOhm | 5% |
| AH-100 | 100 W | 0.1 Ohm - 1 kOhm | 5% |
Overall dimensions of resistors AH-25 and AH-50 
Overall dimensions of AH-100 resistorsA fairly common use of power resistors is to measure the current flowing in a circuit. At a low current value (usually not exceeding tens of amperes), resistive current shunts are used to measure it, the voltage from which is supplied to a differential amplifier. The advantages of resistive shunts are their low cost and immunity to electromagnetic interference, as well as, in some cases, compactness. However, the resistive shunt dissipates power proportional to the square of the current flowing times the shunt resistance, reducing the efficiency of the converter. Therefore, the range of currents in which the use of resistive meters is justified is determined by the permissible level of losses on the shunt resistance.
For more details on the technical characteristics of the powerful resistors of the AH series, see the Specifications on the product page.