RH850/C1M-A R/D Converter (RDC3A)
R01AN4051EJ0211 Rev.2.11 Page
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July.6.22
ε is the control deviation in this control loop. The negative feedback control provides feedback so that the
control deviation becomes 0. When θ = Φ, the analog angle information from a resolver has been converted
to the digital angle Φ.
Sets the response speed with the PI compensator in a loop.
2.2.3 Setting the R/D Converter Bandwidth
The bandwidth of the PI compensator needs to be set when an R/D converter is used. The bandwidth is
expressed by the frequency. When the frequency is set high, the response becomes quick but has a large
influence by noise and other factors. On the other hand, when the frequency is set low, the response
becomes slow and immune to noise and the R/D converter output becomes stable. For an R/D converter
mounted on the Renesas MCU, the default is 800Hz and can be changed.
Some R/D converters have a function to set the bandwidth automatically. When this function is used, the
bandwidth is set low when the resolver is stable and it is set high automatically when the quick response is
required such as at acceleration. The R/D converters mounted on the Renesas MCU have an auto-adjusted
function.
The bandwidth setting of an R/D converter has influence on response speed for acceleration and angle step
but has no influence on the maximum speed of when a resolver is rotating stationary. For example, when the
bandwidth is set low (around 200Hz), if a resolver is slowly accelerated, it can be tracked even the final
speed is high (for example 1000Hz=60000rpm). Also, when a resolver is rotating stationary at high speed,
inside an R/D converter remains stationary (ε is small) and the bandwidth is set low in auto-adjusted.
Figure 2.7 Output Change by the Bandwidth Change of PI Compensator shows the difference in output
by the bandwidth of PI compensator setting.
Figure 2.7 Output Change by the Bandwidth Change of PI Compensator
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