| Title |
Sensorless Measurement Method of the DC Link Ripple Current of Three-Phase Active Power |
| DOI |
http://dx.doi.org/10.5207/JIEIE.2018.32.4.032 |
| Keywords |
Active Power Filter ; Life Time of Aluminum Electrolytic Capacitor ; DC Capacitor Ripple Current ; Sensorless Measurement |
| Abstract |
In general, it is important to measure the ripple current of a DC capacitor, which is closely related to the lifetime of a power electronic converter. However, it is very difficult to measure directly with the current sensor because the DC capacitor is connected to the switching module at the shortest distance to minimize the inductance parasitic component of the DC capacitor and the overshoot of the switching device. This paper proposes a method to measure the ripple current of a DC capacitor of an active power filter indirectly without a sensor. The proposed method calculates the ripple current of the DC capacitor by sensorless method using the DC capacitor voltage, the output phase voltages and the compensation currents of the active power filter. The compensation current and DC voltage are directly detected to control the active power filter, and the compensation voltage is indirectly measured by using the switching function and DC voltage. The basic p-q power theory was applied to the 3-phase 3-wire active power filter and the DC capacitor current of the active power filter was measured for three-phase balanced, unbalanced power source condition, steady state and transient state. As a result, it was possible to indirectly measure the DC capacitor ripple current irrespective of the condition of the power source and the load variation, and the result was consistent with the results measured by the sensor. |