Resolver In
Purpose
Generates an exciter voltage and calculates the rotation angle or speed based on sine- and cosine-modulated feedback signals.
Description
The Resolver In input of the RT Box 2, 3 and 4 is intended to be connected to a physical two-pole transmitter resolver. The input connects to an AD2S1210 resolver-to-digital converter from Analog Devices, Inc. The Resolver In connector on the RT Box provides a differential, sinusoidal exciter voltage with variable frequency and amplitude on the +EXCOUT and -EXCOUT pins. The differential feedback pins, +COSIN, -COSIN, +SININ and -SININ take amplitude modulated feedback signals from the physical resolver. The ratio of the input signals allows to calculate the angle (in rad) or speed (in rad/s) of the resolver. The Resolver In block configures the AD2S1210 converter.
The input voltages applied to the +COSIN, -COSIN, +SININ and -SININ input pins are required to be in the range of 2.3 \(\mathrm{V_{pp}}\) to 4.4 \(\mathrm{V_{pp}}\). Each voltage referred to ground must be in the range of 0.15 \(\mathrm{V}\) to 4.8 \(\mathrm{V}\).
The RT Box 2 or 4 provides one resolver input, and the RT Box 3 provides two of them. There is no resolver input available on the RT Box 1 or CE.
The minimum readout time for one resolver is around \(2\,\mu\)s. This time is doubled when both resolver inputs of an RT Box 3 are active. If the model step size is smaller than the resolver readout time, a value of 1 at the output v signals the arrival of valid data.
The settling time and the maximum tracking speed are resolution dependent:
Resolution |
Maximum tracking speed |
Settling time 10° step |
Rec. exciter frequency |
|---|---|---|---|
10 bit |
5000 \(\pi\)/s |
0.6 ms |
10 - 20 kHz |
12 bit |
2000 \(\pi\)/s |
2.2 ms |
6 - 20 kHz |
14 bit |
1000 \(\pi\)/s |
6.5 ms |
3 - 12 kHz |
16 bit |
250 \(\pi\)/s |
27.5 ms |
2 - 10 kHz |
The output e signals the error state of the resolver. It consists of 8 bit where each bit indicates a separate fault condition:
Bit |
Description |
|---|---|
D7 |
Sine/cosine inputs clipped |
D6 |
Sine/cosine inputs below threshold |
D5 |
Sine/cosine inputs overrange |
D4 |
Sine/cosine inputs mismatch |
D3 |
Tracking error |
D2 |
Velocity exceeds range |
D1 |
Phase error |
D0 |
Configuration parity error |
For more details consult the AD2S1210 datasheet, available from the Analog Devices website (https://www.analog.com).
Parameters
- Resolver module
Specifies which resolver input to use. The second resolver input is available on the RT Box 3 only.
- Measurement
Specifies if the block output is the position (in rad) or the speed (in rad/s).
- Resolution
The resolver resolution can be 10, 12, 14 or 16 bit. The resolution influences the maximum tracking speed and the settling time (see table above).
- Exciter frequency
The frequency of the exciter output voltage (see table above for recommended settings).
- Exciter voltage
The amplitude (measured peak-to-peak) for the exciter voltage. The exciter voltage should be chosen depending on the attenuation of the connected resolver such that the SIN and COS feedback voltages are within their allowed range.