3320A: Servo Motor Analyzer

Overview

The 3320A Servo Motor Analyzer automates the process of testing fractional horsepower brush and brushless DC servo motors. The analyzer gives full electrical and electromechanical motor parameter coverage with minimal operator interaction.

Capable of testing up to 25 servo motor characteristics, the 3320A can analyze motors used in consumer electronics, data storage devices, automobiles, light industrial applications, and many other areas. After just a few minutes of setup, the analyzer automatically tests multiple motor parameters such as torque constant, friction, break-away torque, torque vs. velocity trend, rotor inertia, viscous damping, motor winding resistance and inductance, and many other characteristics.

In addition to testing motor parameters, the analyzer tests and characterizes the motor's feedback sensors. Feedback from a servo motor's encoder and commutation sensor (e.g. Hall-effect sensors) is constantly monitored for fault conditions. A snapshot of sensor waveforms is recorded by the analyzer when sensor faults are detected. Waveforms showing the alignment of the back-EMF to the commutation sensor outputs can also be captured and displayed.

The 3320A greatly simplifies motor characterization and is an essential motor analysis tool for:

• Mechanical design engineers

• Motion control system designers

• Motor driver design engineers

• Quality control engineers

• Manufacturing engineers

Verify servo motor specifications, validate new designs and diagnose problems in just a few minutes with the new 3320A Servo Motor Analyzer.

Parameter Analysis

In just a few moments of testing, the 3320A can determine multiple motor parameters. All of the following parameters can be quickly determined without needing to couple anything to the servo motor's shaft.

• Torque Constant - K_T	• Breakaway Current/Torque
• Back-EMF Constant - K_E	• Mechanical Time Constant - t_m
• Rotor Inertia - J_M	• Winding Resistance & Inductance
• Viscous Damping Coefficient	• Electrical Time Constant - t_e
• Coulomb Friction	• Encoder and Commutation Sensor CPR

Plots

Observe parameter trends and transient response behavior by generating plots of your motor'

s mechanical and electrical characteristics.

• Velocity/Current/Power/Eff. vs. Torque • Torque Constant vs. Current

• Mechanical Time Constant Transient • Commutation Sensor Alignment

• Electrical Time Constant Transient • Current-Step Response

Fault Detection

Automatically detects and reports common servo motor problems.

• Motor and Sensor Short Circuits

• Encoder Phase Errors

• Commutation Sensor Bad States, Bad State Order, Phase Errors

Manual Testing Mode

The analysis capabilities of the 3320A are not limited to the list of automated tests. A powerful Manual Mode allows you to take control of the integrated motor driver and torque load to produce your own custom tests. In this mode, you can manually control the motor driver's current, voltage or velocity setpoint while simultaneously observing an oscilloscope view (Waveform Viewer) of the motor voltage, encoder signals and commutation sensor signals. Average power, efficiency, velocity, position, present commutation state and other information can also be viewed while in this mode.

Fully Integrated Standalone Analyzer

Unlike other motor test systems, all of the functions of the 3320A are integrated into a single unit. This allows for greater reliability and ease of use.

The 3320A integrates:

• Graphical User Interface: Color LCD display, load/save data & settings, on-screen help

• Digital Signal Processors: DSPs control/monitor motor voltage, current, power, velocity, etc.

• Motor Driver: Brush DC, brushless DC, precision voltage, current, and velocity regulation modes

• Dual Sensor Power Supplies: 3.3-24V DC power for encoder and commutation sensor VCC

• Encoder Input: Accepts differential or single-ended quadrature incremental encoders

• Commutation Sensor Input: Accepts Hall-effect sensors, optical, etc.

• Tachometer Input: Accepts pulsed or sinusoidal inputs

• Resistance & Inductance Meter: Precision resistance and inductance measurements

• Torque Load Controller: Drives a optional calibrated Instrument Brake

• Waveform Viewer: Simultaneously view motor voltage/back-EMF, encoder and Hall signals

Load Testing

The 3320A can measure most of its range parameters without the motor-under-test being coupled to a load. But for more detailed testing, the motor can be coupled to an optional Instrument Brake. An Instrument Brake is a calibrated torque load with an incremental encoder whose torque output is controlled by the analyzer. In this test configuration, the instrument can produce torque vs. velocity and torque constant vs. motor current plots. The torque output of the brake can also be manually controlled by the operator in the analyzer's Manual Mode.

The Instrument Brake is also useful when doing basic testing of motors that are not equipped with an encoder or commutation sensor. Coupling the motor to an Instrument Brake allows you to use the Instrument Brake's encoder for velocity feedback and/or for commutation feedback.

Features

Motor Driver

Dual digital signal processors
Drives brush DC and brushless DC (trapezoidal six-step drive) motors
Precision auto-ranging 180W, 4A, 45V output
- Voltage output mode
- Current output mode - Current controller automatically adapts to winding characteristics
- Velocity control mode - 3320A aids in control parameter selection
- Capable of driving motors with zero inductance (no series inductor needed)
Multiple commutation options for BLDC motors
- Commutation sensor feedback (e.g. Halls) - 3320A automatically adapts itself to sensor
- Encoder feedback - 3320A automatically adapts itself to encoder for commutation use
- Open-loop step-drive (i.e. drives motor like a stepper motor)
Multiple velocity feedback options
- Encoder
- Commutation sensor
- Tachometer
- Instrument Brake
- No feedback (note: testing options are limited when no velocity feedback is available)
Fault detection (over-current, over-voltage, etc.)

Precision Measurements

Average terminal voltage, back-EMF, current, power, and efficiency measurements
Auto-ranging
Winding inductance - up to 0.5A of measurement current
Winding resistance - four-lead type with up to 4A of measurement current
Automatically analyzes 25 servo motor characteristics

Waveform Viewer

Oscilloscope-like operation
9 simultaneous channels
- 3 differential/single-ended encoder channels
- 3 single-ended commutation sensor channels
- 3 differential motor terminal channels
10-bit 60MHz sampling per channel
Large sample buffer - 32,000 samples per channel
Multiple triggering options
- Trigger on encoder or commutation sensor faults
- Trigger on rising or falling edges
- Auto triggering

Manual Mode

Operator-directed testing
Manual control over motor driver mode and setpoint
Torque load (Instrument Brake) control
View servo motor waveforms, average voltage, power, etc.

Fault Detection

Encoder phase errors
Commutation sensor bad states, bad sequence, phase errors
Encoder and commutation sensor power over-current
Motor driver over-current, over-voltage

Output Trigger

Configurable - can be set to trigger on particular fault conditions
Can be connected to an external oscilloscope, counter or other device
Output trigger line is pulsed when faults occur

Graphical User Interface

640x480 color LCD display
Save/Load - store up to 8 of each of the following:
- Settings/configurations
- Test result reports
- Plots
- Fault log
Selectable Units of Measure
- Velocity: RPM, rad/s, etc.
- Torque: oz·in, N·m, etc.
On-screen Help

External Interface

Download reports and plots to a PC via the built-in Ethernet interface.

100/10Base-T, IEEE 802.3U compatible.

Upgrade Path

As new members are added to the family of 3320 servo motor analyzers, the 3320A can be continually upgraded for a fraction of the cost of a new unit. The forthcoming 3320B and 3320C will provide a host of additional features such as USB printer and flash disk support, additional tests and advanced fault detection.

Warranty

Our standard warranty covers the 3320A for manufacturer defects for a period of 2 years from the date of purchase. This also includes two free factory calibrations: the initial calibration after completion of the sale and another calibration anytime during the second year of ownership.

The warranty is automatically extended another 2-years when you purchase a 3320 series upgrade.

Probes

A full set probes come standard with the 3320. This set of five probes allows the instrument to be connected to an encoder, a commutation sensor and to the terminals of a brush or brushless DC motor.

Two probes are used to connect to the output of a single-ended encoder: a "channel" probe (model P301), for connecting to encoder outputs A and B, and an "index" probe (model P303) which is used to connect to an encoder's optional index output. A single probe (model P304) connects the instrument to the three commutation sensor output lines. Power is delivered to the encoder and commutation sensors using the Sensor Power probe (model P305). For the connection to the motor terminals, two probes are used: a "power" probe (model P307) and a "sense" probe (model P306). Two probes are used here in order to form a Kelvin connection which improves instrument accuracy when testing motors with low resistance windings.

When connecting to the output of a differential encoder, the differential probes P300 and P302 are recommended. These two differential probes are sold separately.

Specifications

Operator Manual

Parameter	Specification	Notes
Winding inductance drive/measurement range	0 to 100 mH	No series inductor needed
Winding inductance measurement accuracy	±1%
Winding resistance drive/measurement range	0 to 10k ohm	Current controller BW is tapered with increasing t_e
Winding Resistance measurement accuracy	±0.5%
Motor driver current output/measurement range	±4.0 A	10-bit resolution, auto-ranging, 5 ranges
Motor current measurement accuracy	±0.3%	Percentage of full-scale of a given range
Motor driver voltage output/measurement range	±45 V	10-bit resolution, auto-ranging, 7 ranges
Motor drive common-mode output voltage	0 V	Driver output is differential with the midpoint centered at 0V
Motor voltage measurement accuracy	±0.3%	Percentage of full-scale of a given range
Current controller bandwidth	4.5 kHz	Typical bandwidth for most loads. Bandwidth is lower (tapered) for large time constant loads
Voltage controller bandwidth	6.0 kHz	Typical bandwidth for most loads. Bandwidth is lower for loads that have both low resistance and low inductance
Velocity controller sampling rate	66.7 Hz	The sampling rate implies a lower limit to the velocity setpoint for the resolution of the velocity feedback device in use
Maximum commutation rate	26 kHz
Encoder common-mode input range	-12 to +30 V	10-bit resolution, three ranges: 7V, 14V, 28V
Encoder differential input range	±30 V
Encoder sensor power supply output voltages	3.3/5/12/24V	0.5A max current, over-current protected
Commutation sensor input range	-12 to +30 V	10-bit resolution, three ranges: 7V, 14V, 28V
Waveform sampling rate	60 MHz ±50 ppm
Waveform sampling jitter	< 1ps RMS
Commutation sensor power supply output voltages	3.3/5/12/24V	0.5A max current, over-current protected
Encoder & commutation sensor counter size	32-bit
Counts per encoder electrical cycle	4
Counts per commutation sensor electrical cycle	6
Encoder/commutation sensor/tachometer max frequency	200 kHz
Maximum encoder resolution when encoder is used as commutation source	16,000 CPR	Where CPR refers to electrical cycles per revolution (not counts per revolution)
Recommended factory calibration interval	yearly	Periodic calibrations ensure the instrument's accuracy and provide you with the most up-to-date firmware
AC Power Input Voltage Frequency	55-63 Hz
AC Input Power	450 VA Max
AC Input Voltage	106-130 V_AC

Ordering Information

31-001-10

3320A - Desktop

31-001-10-R

3320A - Rackmount (for 19" rack)

Contact Sales for pricing and lead-time.

3320A: Servo Motor Analyzer