4.8 SECTION FOUR - COMPONENT DESCRIPTION AND SPECIFICATION
4.2.2.3. Analog to Digital Section
The analog command input has an input voltage level of +/- 10VDC. It is brought in to a
differential amplifier. The choice is available in software to either use this command signal
unfiltered or to use a low pass filter on the command. The filter has a -3dB point of 1KHz
and an inband time delay of 360µsec. The command signals are converted by the A/D
converter, a 12 bit converter.
The resolver excitation signal is sinusoidal at 3.0 KHz, 4VRMS, and can drive up to 100ma.
The resolver SIN and COS feedback signals are expected to be at a 2VRMS level. They
are brought in to differential amplifiers, filtered, and converted by the A/D converter.
4.2.2.4. Digital to Analog Section
The CPU outputs the properly commutated motor phase A and phase B current commands
to the current loop through the D/A converter section. One customer programmable test
point and one fixed test point are also provided by the D/A converter section.
4.2.2.5. Current Loop
The current loop takes the command signals from the D/A section and the motor phase
current feedback signals and generates a closed loop current error signal which drives the
PWM (pulse width modulation) stage. PWM is used to convert the analog current error into
a digital command for the three phase inverter bridge. The setup parameters of the current
loop are varied depending on the type of motor and controller size used. This motor
specific information is contained in the MCO module and is provided to the current loop
upon power up. The gate drive takes the digital current loop PWM commands and level
and amplitude shifts them to an appropriate voltage to drive the 6 high voltage IGBT
transistors in the inverter output bridge.
4.2.2.6. UART
The UART (universal asynchronous receiver/transmitter) is used to provide the CPU with
communication information from the user and to provide the user with controller status information.
Two modes of communication are available through the UART interface: RS232 and RS485. RS232
is a 3 wire standard computer serial interface for talking from one device (computer or terminal) to
one other device (T161 Series Controller). RS485 is a 2 wire multidrop communication interface. Up
to 32 communication nodes are supported (31 "slaves", i.e. T161 Series Controllers, and 1 "master",
i.e. a PC). RS232 or RS485 is selected by the position of the jumpers L2 through L5. Installing the
jumpers across L2,L3,andL5 will provide RS232 and connecting the jumper across L4 only will
provide RS485.
