Resolver one step delay in the resulted sin/cos values

I used the resolver Simscape block in order to capture the motor angle and compare it with the ideal roational motion sensor Simscape block.

Then, in order to calculate the sensor angle the atan2 function is used.

What realized is that the resulted resolver sensor angle has a one excitation signal period delay compared to the ideal sensor. This has been verified by trying different excitation signal frequencies.

The parametrization selected was the "Specify transformation ratio and omit dynamics".

Is it reasonable to have one excitation period step delay in the reported sine and cosine output values? As I think that resolver consists of a rotary transformer that couples an AC voltage applied to the primary winding to two secondary windings.

Answer 1

[Naren]

Hello Nikolaos,

Due to the nature of the resolver, it is conceivable for the sensor angle to have a step delay of one excitation period when compared to the ideal sensor and resolver operates by connecting two secondary windings that are physically separated from one another by an angle to an AC voltage. Two output signals from the resolver—typically sine and cosine—represent the angle between the rotor and the stator.

Beacuse of resolver's inherently slow processing speed, there may be a delay when utilising the resolver Simscape block to measure the motor angle and compare it to the optimum rotational motion sensor Simscape block. The time it takes for the resolver to generate the output signals, the phase shift the resolver introduces, and the time it takes for the output signals to propagate through the system can all contribute to this delay.

In general, the parameters used for the Simscape block and the specific resolver implementation will determine how much delay is added by the resolver block. However, especially when using the "Specify transformation ratio and omit dynamics" parameterization, it is not uncommon for the resolver sensor angle to have a one excitation period step delay in comparison to the ideal sensor.

If the delay created by the resolver block worries you, you might wish to experiment with changing the Simscape block's parameters to see if you can lessen or completely get rid of the delay. In contrast, you might want to think about utilising an other kind of sensor block, like a magnetic encoder or a Hall effect sensor, which might not add as much delay as the resolver block.