There are essential differences between DC resistance and AC resistance in definition, characteristics and application. The following is a system comparison analysis:
一、Core definition differences
|
Parameters |
DC resistance (DCR) |
AC resistance (impedance, Z) |
| Physical essence | The obstructive effect of conductors on constant current (pure resistance) | The total obstruction of conductors to alternating current (including reactance component) |
| Mathematical expression | Scalar (R=V/I) | Complex number (Z=R+jX, including real part resistance and imaginary part reactance) 13 |
| Phase relationship | Voltage and current are in phase | There is a phase difference between voltage and current (inductive load lagging, capacitive load leading) 36 |
II. Measurement method and characteristic comparison
measuring principle
DC resistance: calculated directly by Ohm’s law (R = V/I), without considering frequency.
AC resistance: It should be measured with an AC bridge or impedance analyzer, specifying a frequency (e.g., 1kHz). For example, in lithium battery internal resistance testing, the AC method injects a 1kHz sinusoidal current, while the DC method calculates through pulse discharge.
III. Frequency dependence comparison
| Characteristics |
DC resistance |
Communication resistance |
| Frequency impact | constant and unchanging | Increasing with frequency (dominated by reactive component) |
| High frequency performance | Always stable | Skin effect/proximity effect leads to a significant increase in equivalent resistance |
| Extreme cases | Superconducting material DC resistance ≈ 0 | High frequency AC resistors still have inductive components |
IV. Typical Application Differences
DC resistance scenarios:
Power equipment: transformer winding resistance detection (to assess poor contact);
Electronic manufacturing: PCB wire resistance and solder joint quality inspection.
AC resistance scenario
High-frequency circuits: RF cable impedance matching (skin effect control required);
Dynamic systems: AC internal resistance of electric vehicle batteries (affecting start-stop response speed);
Electromagnetic equipment: Transformer no-load loss analysis (core eddy current losses frequency-dependent)
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Post time: Oct-31-2025
