Pacific Scientific SCE900 Servo Drive Complete Guide

Pacific Scientific SCE900 series fully digital AC servo drive: a high-performance single axis motion control solution based on Resolver feedback

Product Series Overview

In the field of modern precision motion control, the performance, flexibility, and reliability of servo drives directly affect the overall performance of automation equipment. The SCE900 series is an economical, high-performance single axis servo drive family launched by Danaher Motion (formerly Pacific Scientific), designed specifically for three-phase permanent magnet brushless servo motors equipped with a rotary transformer (Resolver). On the basis of inheriting the mature control interface of SC900 series, this series of drivers has comprehensively upgraded the power electronics part, making it compatible with North American 480VAC and European 400VAC three-phase main power supplies, and meeting CE certification requirements. The SCE900 series adopts a fully digital DSP control architecture, integrating advanced digital rotary transformer conversion technology, sine wave current control, and modular tab design. It is widely used in industrial fields such as machine tools, packaging, textiles, robots, and specialized automation equipment.

Core control technology

2.1 Fully digital DSP control architecture

All control loops (current loop, speed loop, position loop) of the SCE900 series are implemented through digital signal processors, abandoning the traditional analog potentiometer adjustment method. The current loop update cycle is only 62.5 microseconds, the speed loop update cycle is 250 microseconds, and the position loop update cycle is 1 millisecond, ensuring extremely high dynamic response performance. The advantages brought by fully digital design include: no temperature drift, repeatable parameters, easy implementation of adaptive control algorithms, and firmware upgrades that can be completed through software.

2.2 Patent Digital Resolver Converter

The driver integrates a digital rotary transformer to digital converter (DRDC) with US patent number 5162798, which directly processes the analog sine/cosine signals of the solver at high speed without the need for an external RDC chip. The converter provides a 24 bit position resolution (approximately 0.0013 arcminutes per revolution), with an absolute accuracy of ± 5.3 arcminutes (for the driver itself). When combined with a standard 20 arcminutes precision solver, the overall accuracy is approximately ± 25 arcminutes. The repeatability is better than ± 0.08 arcminutes (RMS), and the noise level is lower than 0.3 arcminutes RMS without filtering. This performance makes SCE900 capable of high-precision positioning applications, such as semiconductor manufacturing, precision measuring equipment, etc.

2.3 Signature Series Sine Current Control

Using the patented "Signature Series" sine wave current control technology, the motor is driven by a back EMF matched sine wave phase current, resulting in extremely low torque ripple and uniform control dynamic characteristics throughout the entire speed range. Compared to traditional square or trapezoidal wave drives, sine wave control significantly reduces high-frequency noise and mechanical vibration during motor operation, improving shaft power output and smoothness.

2.4 Automatic digital tuning

SCE900 supports digital automatic tuning function. Users only need to input basic parameters such as motor model and load inertia in the configuration software, and the driver can automatically calculate and set the optimal current loop, speed loop, position loop gain, integration time, filter parameters, etc. This enables the system to operate stably upon initial power on, significantly reducing the debugging cycle. For advanced applications, users can still manually adjust parameters such as KVP (speed loop proportional gain), KVI (speed loop integral), KPP (position loop proportional gain), KVFF (speed feedforward), etc. to achieve the ultimate performance.

Product Model and Power Classification

The SCE900 series is divided into four basic power levels based on output current and power: SCE902, SCE903, SCE904, and SCE905. The suffix number of each model represents the power level.

3.1 SCE902 (Low Power Version)

SCE902 is the lowest power member in the series, designed for 115-240VAC single-phase or three-phase power supply. The peak output current is 7.5A (0-p, 5 seconds), and the continuous output current is 3.75A under convection cooling at 25 ° C, and the same is true under forced air cooling at 50 ° C. The rated power is reduced to 2.5A at 50 ° C under pure convection cooling. The peak output power is 2.2kW (1 second) under 240VAC three-phase input, and the continuous output power is 1.1kW (25 ° C convection cooling) or 0.75kW (50 ° C convection cooling). If using 120VAC single-phase power supply, all power ratings must be reduced by 50%. This model is suitable for applications such as small robotic arms, labeling machines, and lightweight conveyor belts. Its external dimensions are 370mm in height, 60mm in width, and 218mm in depth, with a weight of approximately 3.2kg.

3.2 SCE903 (Medium Power)

SCE903 is suitable for three-phase 180-528VAC power supply, with a peak current of 10.6A and a continuous current of 5.3A under convection cooling at 25 ° C, maintained at 5.3A under forced air cooling at 50 ° C, and 3.5A under convection cooling at 50 ° C. The peak power reaches 5kW (1 second) at 400VAC and 6kW at 480VAC, with a corresponding continuous power of 2.5kW (25 ° C convection) or 2.1kW (50 ° C convection). This model is suitable for most industrial single axis applications, such as X-Y worktables, flying shears, and winding machines. The size is 370 × 85 × 229mm and weighs approximately 5.0kg.

3.3 SCE904 (medium high power)

The peak current of SCE904 is 21.2A, and the continuous current is 10.6A (25 ° C convection or 50 ° C forced air cooling). The 50 ° C convection cooling drops to 7.1A. The peak power is 10kW at 400VAC and 12kW at 480VAC; the continuous power corresponds to 5.0kW (25 ° C convection) or 3.3kW (50 ° C convection). Its power level is suitable for high load applications such as large CNC machine tools and injection molding machine parts taking manipulators. Size 370 × 114 × 229mm, weight approximately 6.6kg.

3.4 SCE905 (High Power)

SCE905 is the most powerful model in the series, with a peak current of 31.8A and a continuous current of 15.9A (25 ° C convection or 50 ° C forced air cooling). The 50 ° C convection cooling drops to 10.6A. The peak power is 15kW at 400VAC and 18kW at 480VAC; the continuous power is 7.5kW (25 ° C convection) or 5.0kW (50 ° C convection). This model is suitable for heavy-duty servo presses, large flying saws, centrifugal test benches, etc. Size 370 × 160 × 229mm, weight approximately 9.5kg.

3.5 Power Supply and Bus Voltage

The AC power input range of SCE903/904/905 is 180-528VAC, three-phase, 47-63Hz. The nominal bus voltage under different input voltages is: 480VAC three-phase input → 650VDC; 400VAC three-phase input → 540VDC; 240VAC three-phase input → 320VDC. The control power supply is 90-264VAC single-phase, with power-off holding time: it can maintain 1 cycle at 90VAC 50Hz, 2.5 cycles at 120VAC 60Hz, and 10 cycles at 240VAC 60Hz. The control power supply of SCE902 shares the same input terminal with the main power supply, with a voltage range of 90-264VAC single-phase or three-phase.

Modular design and tabs

The SCE900 series adopts a modular structure, and users can choose different tabs to insert into the expansion slot at the front of the drive according to their needs. This design allows the same base driver to adapt to multiple command sources and communication protocols.

4.1 Available Tabs

OCE900-001: Blank panel, used to cover tab slots, suitable for low-cost applications where parameters have been solidified in the base drive.

OCE930-001-00/01: Serial Communication tab, providing RS-232 or RS-485 interfaces for parameter settings and command control. Comes with 930WIN configuration software. The suffix -01 includes the software upgrade function for the base driver.

OCE940-001-01: ERCOS interface tab, based on fiber optic ring network industrial standard motion control bus, supports multi axis high real-time synchronous control.

OCE950-50x-01: Standard single axis programmable positioning tab, built-in non-volatile RAM (32KB or 128KB), can independently run motion programs, supports PacLAN network.

OCE950-60x-01: Enhanced single axis programmable positioning tab, adding MODBus, Allen Bradley DF-1 communication, and electronic cam functions on the basis of the standard version.

4.2 Mobile personality parameters

One important feature of SCE900 is the 'movable personality parameter'. All system parameters and application parameters of the drive are stored in EEPROM (with a typical write life of 1 million times). Users can configure the driver through the tab, then save the parameters to the internal non-volatile memory of the base driver, and then remove the tab and cover it with a blank panel. This not only reduces costs but also prevents unauthorized parameter modifications on site. On the contrary, if the parameters are stored on a tab, when replacing the damaged base drive, simply insert the original tab into the new drive without downloading the parameters again to restore all settings of the axis.

Interface and Input/Output Definition

All connections of SCE900 series drives use pluggable terminals and are designed to prevent misconnection. The main connectors include:

5.1 Power connector

J1 (AC main power supply): L1, L2, L3 three-phase inputs (SCE902 is single-phase/three-phase shared), and PE chassis grounding terminal.

J6 (control power supply): N and L1 terminals, accepting 90-264VAC single-phase control power supply. Also provide PE terminals.

J2 (motor power output): U, V, W three-phase motor phase line output, and motor housing grounding terminal.

5.2 Feedback connector J3

Resolver signal: S1 (SIN+), S3 (SIN -), S2 (COS+), S4 (COS -) differential input, input impedance>25k Ω, strong common mode rejection capability.

Resolver excitation: R1 (excitation output), R2 (excitation return). Output 9.2V RMS, 6510.42Hz, maximum load 75mA RMS, with short-circuit protection.

Motor PTC thermal protection: PTC and PTC RTN terminals are connected to the built-in positive temperature coefficient thermistor or normally closed temperature control switch of the motor. When the resistance is greater than 6.2k Ω, the driver reports a "motor overheating" fault.

5.3 Command I/O connector J4 (25 pin D-sub)

Analog command input (J4-1,2): differential input, full range ± 13.5V, maximum single ended range ± 21V, input impedance>50k Ω, adjustable offset and low-pass filtering bandwidth through software.

DAC monitoring output (J4-3,4): ± 5V analog output, resolution 10V/256 ≈ 0.039V, can be mapped to 28 internal variables such as speed, current, position error, bus voltage, etc., used for oscilloscope diagnosis.

Enable input (J4-6): Low level active, internal pull-up 3.3k Ω, minimum driving capacity 5mA, maximum external voltage 30V. Equipped with 2ms low-pass filtering and programmable logic threshold (5V or 12V pull-up).

Bidirectional digital I/O (BDIO 1-6) (J4-7 to 12): programmable as input or output. As an output, it is an open collector electrode with a withstand voltage of 30V and a current capacity of 100mA for BDIO1-5 and 200mA for BDIO6 (non short-circuit protection). As input, it has a 20 μ s filtering and 1V hysteresis. Factory default functions: BDIO1=fault reset, BDIO2=forward limit (CW Inhibit), BDIO3=reverse limit (CCW Inhibit), BDIO4=unmapped, BDIO5=brake output (engaged when driver enabled), BDIO6=fault output.

I/O common terminal (J4-5, 13, 18): signal ground.

Encoder simulation output (J4-14 to 17,19,20): differential TTL signal, A、A̅、B、B̅、Z、Z̅， Generated from the position of the Resolver, simulating a photoelectric encoder. The output resolution can be programmed into 16 levels (binary: 128/256/.../16384 PPR; Decimal: 125/250/ ../16000 PPR）。 Using 26LS31 driver, with a maximum load of ± 20mA, it can drive 10 RS-422 receivers and output ground short-circuit protection.

Encoder input (J4-21 to 24): Differential RS-422 compatible (26LS32), capable of receiving orthogonal encoders, step/direction or addition/subtraction pulse signals. The maximum input frequency is 800kHz (fast decoding mode). Supports single ended TTL signals (requires an external pull-up resistor). The decoding mode is selected through the EncMode parameter and has programmable 4:1, 8:1, or 16:1 filtering deceleration modes.

+5V auxiliary output (J4-25, reference ground J4-18): 5V ± 5%, maximum 200mA, short circuit protection, can be used to power external encoders or sensors.

Rotary Transformer Feedback System

The SCE900 series comes standard with Resolver feedback, allowing for high-precision and highly reliable position and velocity closed-loop without the need for a photoelectric encoder. The excitation frequency of the Resolver is 6510.42Hz, the maximum tracking speed is>48600 rpm, the maximum recommended speed is 25 krpm, and the maximum tracking acceleration is 16 × 10 ^ 6 rpm/s. The maximum length of the Resolve cable is 50 meters. Noise level of speed feedback:<3 rpm RMS without filtering,<0.6 rpm RMS after single pole filtering at 150Hz,<0.06 rpm RMS after filtering at 10Hz. The typical value of DC accuracy is ± 0.01%, and the worst is ± 0.05%. This performance far exceeds traditional analog speed sensors.

Protection function and fault diagnosis

SCE900 integrates comprehensive protection circuits, and all faults are indicated in the form of flashing codes through a seven segment LED display screen (while extended fault codes can be read through software). The main protection functions include:

Output short circuit protection: phase to phase short circuit and phase to neutral point (ground) short circuit detection.

Motor overheating: monitored through PTC input.

Drive overheating: Power module heat sink temperature monitoring, automatically disabling output when exceeding threshold.

Bus overvoltage/undervoltage: The overvoltage threshold is adjustable, and undervoltage detection controls the power supply.

I ² t current limiting: Intelligent adjustment of continuous current limit based on heat sink temperature to prevent overheating of power devices.

Control power undervoltage.

+5V auxiliary output short circuit protection.

Processor watchdog malfunction.

After the fault occurs, the drive locks the fault state, disables the output stage, and activates the mappable fault output (BDIO6). The fault can be cleared by resetting the input (BDIO1) or re powering on the control power supply. Typical fault codes include: 1 flicker (speed feedback overspeed), 2 flicker (motor overheating), 3 flicker (driver overheating), 4 flicker (I ² t overcurrent), 7 flicker (output overcurrent or bus overvoltage), 8 flicker (brake chopper overload), 9 flicker (DSP detects bus overvoltage), etc.

CE compliant installation and EMC measures

To ensure compliance with the Low Voltage Directive (73/23/EEC) and the EMC Directive (89/336/EEC), the SCE900 series must comply with the following requirements during installation:

8.1 Grounding

Due to the leakage current to ground of the internal circuit filter of the driver being approximately 15mA, a dual PE line redundant connection must be used: J1 pin4 and J6 pin1 (both PE symbols) must be independently connected to the protective ground, and the connection point must be a permanent hard wire (plug-in connectors cannot be used). Cannot rely on residual current devices (RCD) as safety protection.

8.2 Shielding and Grounding

The shielding layer of the motor cable must be connected to the PE pin of J2 at the driver end, and the shielding layer must be connected to the grounding plate (ground plane) with conductive clamps. If a cable with inner aluminum foil shielding and outer braided shielding is used, the inner layer should be connected to a PE pin and the outer layer should be clamped to the grounding plate.

Resolver cables should have independent internal shielding for each pair of twisted pair cables, plus total braided shielding. The inner shield is connected to J3 pin5, and the outer shield is clamped to the grounding plate.

The outer braided shield of the J4 command I/O cable needs to be clamped to the grounding plate.

The leads of the external braking resistor also need to be shielded and clamped to the grounding plate.

All shielding connection points need to remove the paint coating to ensure good high-frequency grounding.

8.3 Heat dissipation requirements

The driver must be installed vertically inside the cabinet, leaving at least 100mm of unobstructed space above and below. During convective cooling, a free space of 40mm is required on both sides; When forced air cooling (optional OFE90x fan) is used, there is no need to leave space on both sides. It is necessary to ensure that the chassis temperature does not exceed the specified value. SCE9x3 only requires convective cooling; SCE9x4/9x5 comes with optional 120VAC or 240VAC fan kits. Under convective cooling at 25 ° C, it can output continuous current at full capacity; At 50 ° C, it is necessary to reduce the rating or use forced air cooling.

8.4 External fuses

SCE903: 10A 500V slow melting fuse (Bussmann FLQ 10); SCE904: 15A 500V； SCE905: 20A 500V。 The J6 circuit of the control power supply uses a 1A 250V slow melting fuse (3AG or FLM 1). The SCE902 main power supply uses a 15A 250V delay fuse (Bussmann MDA-15).

8.5 Regenerative braking and external resistance

The driver integrates a brake chopper and an internal regenerative resistor. The internal resistance of SCE9x3 is 80W, and the internal resistance of SCE9x4/9x5 is 36W. If the regenerative energy exceeds the internal resistance capacity, an external resistor can be connected between+Bus and R at the J5 terminal (the short wire between Ri and R needs to be removed). External resistance values: SCE9x3 is 80 Ω± 10%, SCE9x4/9x5 is 36 Ω± 10%. The power rating of external resistors should be calculated based on the load inertia and deceleration, and if necessary, a series parallel combination should be used.

Software configuration and debugging

When the SCE900 is paired with the OCE930 tab, it can be configured using the 930WIN.EXE software (running on Windows 3.1/95). When the driver leaves the factory, it is in an unconfigured state (status display "U C"), and motor parameters, feedback types, current limits, control loop parameters, etc. must be set through software. The software provides Auto Setup mode, where users only need to answer questions about motor model, rated current, pole pairs, etc. The software automatically calculates and writes parameters. After configuration, the parameters can be stored in the base EEPROM or tab EEPROM. In addition, the driver also supports real-time modification of parameters and monitoring variables (such as speed, current, temperature, fault codes, etc.) through digital communication.

For the OCE950 programmable positioning tab, users can use the 950IDE integrated development environment to write BASIC style motion programs that enable single axis independent operation, including jog, absolute positioning, relative positioning, zeroing, conditional jump, I/O control, and support for electronic gears and electronic camshafts (enhanced version).