DG-IRMCK203 Datasheet, PDF (8/67 Pages) International Rectifier – Application Developer’s Guide

IRMCK203 Application Developer’s Guide
2.1.3 Rotor Angle Estimation
Motor shaft angle information is required for high performance control of Permanent Magnet motors. The
IRMCK203 Sensorless control IC contains a motor shaft angle estimator, which provides shaft angle and motor speed
information. There is no need for encoder or hall sensor element feedback.
2.1.4 Start-Stop Sequencer and Fault Detection
A Start-Stop sequencer provides total drive sequencing for handling start-stop and start-up failure retry functions.
There are various fault triggers (detailed in Section 2.6) to ensure that the drive is protected under various fault
conditions.
2.2 Current Feedbacks
2.2.1 Using IR2175
Two channels of current feedback interface logic are provided in the IRMCK203. Each module measures the
incoming varying duty period of the 130 kHz carrier frequency signal at the IR2175 output. Measurement is
performed for both carrier frequency period and on duty period at the same time using fast counters. Counting
frequency is 133 MHz with a 33.3 MHz system clock.
The IR2175 is the unique high voltage IC capable of measuring the motor phase current through an associated shunt
resistor, which can generate ±260mV voltage range. The output of the IR2175 is an open drain with a 130 kHz fixed
carrier frequency where the duty variance is linearly proportional to ±260 mV input voltage. The counting
frequency is 133.3 MHz when the system clock crystal frequency is 33.3 MHz, which yields 10-bit resolution of the
current measurement data from the IR2175. A more detailed description of the IR2175 can be found in Appendix B.
2.2.2 Using Inverter Leg Shunt
The IRMCK203 provides another means of current feedback through the use of an ADS7818 (BurrBrown) serial A/D
converter. Inverter Leg Shunt (install in Low side) currents can be used instead of IR2175 current feedback for
Sensorless motor control. The minimum requirement is two Leg Shunt feedbacks (V and W phases). An application
example is given in Section 2.4.2 for interfacing Leg Shunt currents to the IRMCK203 digital control IC.
In the IRMCK203, the selection of current feedback is done via a user configuration parameter (provided in the Motor
commissioning tools). The Leg Shunt option is recommended for Inverter switching frequencies less than 10KHz.
2.3 Communication
The IRMCK203 contains a rich set of externally addressable "Host" registers documented in Section 4 of this guide.
There are three physical interfaces that can access the Host Registers: RS-232, SPI and Host Parallel.
2.3.1 RS-232 Serial Interface
The slowest of the three, the Serial Interface, is used for inter-board communications typically using cables as the
connection medium. The IRMCK203 implements an error detecting protocol layer that facilitates maintaining the
integrity of the Host Registers. Prior to updating any Host Register, the incoming data must match a checksum
string to detect single bit errors. Please refer to the RS-232 protocol documentation in Section 4.1.3 for the specific
protocol definition. The RS-232 Serial Interface supports four baud rates based on the signal levels on pins 30 and
42 of the IRMCK203, as shown in Table 1.
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