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Resolver Model Description

A resolver is a sensor that provides feedback about the angular position and velocity of a rotating component, such as the rotor of an electrical motor. Image Removed

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Figure 1.  An example of a operating resolver where a sinusoidal excitation signal is input into the resolver and the result is two output signals, Sine Output and Cosine Output

During operation, a sinusoidal excitation signal is provided to the resolver.  The resolver modulates the input excitation signal to produce two outputs representing sin(x) and cos(x), where x is the angle of the rotor.  From the sin(x) and cos(x) signals controllers are reconstituted to calculate angular position of the machine.

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Figure 2.  Sine and Cosine signals generated by a resolver with an input Excitation sinusoidal signal.

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Equations Equations

Resolver Model Equations

The resolver model outputs are calculated using the following sets of equations:

Sine \; Output = [Sin.Sin*sin(pp(\theta_m - \theta_{Offset})) + Sin.Cos * cos(pp * \theta_m - \theta_{Offset}))] * Excitation

Cosine \; Output = [Cos.Sin*sin(pp(\theta_m - \theta_{Offset})) + Cos.Cos * cos(pp * \theta_m - \theta_{Offset}))] * Excitation

Where Sin.Sin, Sin.Cos, Cos.Sin, and Cos.Cos represent gains that are applied to simulate a non-ideal resolver.  To simulate an ideal resolver, set the Sin.Sin and Cos.Cos gains to 1, set the Sin.Cos and Cos.Sin gains to 0, set the pp to 1, and set the θ_Offset to  to 0.  This results in the following equations:

Sine \; Output = sin(\theta_m) * Excitation

Cosine \; Output = cos(\theta_m) * Excitation

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Excitation Excitation

Resolver Excitation Signal

For this resolver model, the excitation signal must be provided through an Analog Input channel.  To confirm the index of the channel to use, refer to the pinout information for your hardware configuration in the the Archived Hardware Configurations section.  In most cases, the following channels are used:

The amplitude of the excitation signal must be within

a -1V to 1V

 range.  If inputting a signal outside this range, use the Gain parameter for the Analog Input channel to manipulate the amplitude. Also note that the input signal must not exceed the specified voltage limitations of the hardware in any case.  Typically, this hardware range is -10V to 10V, although the exact value can be confirmed on the description page of the Hardware Configuration.