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AN-1090

Once current regulator diagnostic is executed, step current response can be observed from trace

function or current probes on w-phase. It is recommended to use current probe to observe step

current response. Figure 4 shows (current probe) the step current response of w-phase when

Current Reg diagnostic function is executed. In this figure, 25% step rated motor current is

commanded. The step level can be controlled by parameter ParkI (inside Current Reg Diagnostic

function). Figure 5 shows the expanded version of Figure 4. The measured current loop response

is critically damped at 0.65 msec time constant (0 – 66.3% of final steady value), which is

approximately equal to the anticipated current regulator bandwidth response (1/1500 =

0.667msec).

0%

25%

Figure 4. Step Current Response

0.65 msec

Figure 5. Step Current Response (Expanded Time Scale)