Woodward EM-80/EM-300 Actuator system

Woodward EM-80/EM-300 Actuator system

The EM-80 and EM-300 are all-electric actuator systems that provide a nominal

40° of actuator output rotation. Each system consists of a three-phase brushless

ac motor which drives a high-precision planetary reduction gear box. A dedicated

driver controls the actuator position.

A complete system consists of:

 an actuator (Woodward-supplied) (Chapter 4)

 a driver (Woodward-supplied) (Chapter 5)

 a resolver cable (Woodward-supplied)

 shielded power cable

 shielded motor drive cable

 an EMI filter (Woodward-supplied) (Chapter 6)

 metal cabinet enclosure

 15- and 25-pin filter pin D-sub connector adapters (Woodward-supplied)

 protected 24 Vdc power source

The actuator is available in two versions, offering two work output levels, EM-80

and EM-300 (see the specifications in Chapter 9). Both versions use the same

three-phase brushless AC motor.

The difference in output is achieved by the use of two different gearboxes. The

EM-80 uses a single-stage planetary 1:7 gear ratio, while the EM-300 uses a

two-stage planetary 1:20 gear ratio.

The motor–gearbox combination comes assembled on a mounting bracket with a

fixed hole pattern. Although the EM-300 is longer than the EM-80, both use the

same mounting hole pattern, allowing the actuators to be interchangeable.

The output flange provides an easy mounting surface for a variety of lever

configurations, and is equipped with a rugged pointer and scale for quick output

position reference while working on the prime mover. A breakaway extension and

two stop pins form a simple means of detecting whether the actuator has been

driven outside its operating boundaries.

Electrical connections are made in a standard, shielded, three-phase terminal

box mounted on the motor, and will accommodate standard cable. The resolver

cable has a 1 m (39”) flying lead that removes the connector from the high

vibration environment of the prime mover. The use of the specified resolver cable

and connector will help ensure correct connections to the driver.

The EM-80 and EM-300 actuators have different position-sensing systems. Both

systems use the same hollow shaft resolver, producing a sine and cosine wave

output with an overall accuracy of 12 arc-minutes. This resolver is mounted at the

rear of the motor and looks at the relative position of the motor shaft.

The EM-80 uses only the resolver since the 1:7 gear ratio within the gearbox

allows full stroke of the actuator output flange with less than one full revolution of

the motor shaft.

The EM-300 has a 1:20 gearbox ratio to achieve the required torque output.

Because of this, the motor shaft rotates more than one full revolution to achieve

full stroke. To ensure proper position indication over the full range, a 10-turn

potentiometer is added behind the resolver to supply a coarse position signal

from which the correct rotor revolution is deduced. The same resolver as used on

the EM-80 gives the accurate position within that revolution.

Motor Controller Module Description

The motor controller module is a digital closed loop motor control, which works

with a position loop at 62.5 μs. For position feedback, it receives a resolver signal

form the motor shaft. The motor controller configuration is divided into several

functional modules. The main modules are the:

 Positioning/encoder module

 Position control module

 Speed control module

 Torque/current control module

 PLC logic module

The positioning/encoder module manages the resolver feedback signal and the

“engine” controller position command signal. The module receives both setpoint

and actual and generates an output to the position control module. The position

control module generates an output to the speed controller module. It signals the

speed control module which direction to rotate and how fast. These three

modules determine the dynamic behavior of the actuator system.

The speed control module generates an output to the torque/current control

module. The torque/current control module controls the excitation of the proper

motor phase with the proper current level. The current is limited to limit the

torque.

The PLC logic module is programmed to convert the “engine” controller position

command signal into a hexadecimal position address. The PLC is programmed

with the specific algorithms to define rotation direction and stroke. The PLC and

the motor controller module are communicating by means of a parallel interface.

The interface takes care of the cyclic update of the position command signals

and the non-cyclic calls for parameters.

The PLC logic program also defines the start-up sequence and enabling of the

motor control module.

Motor Driver Module Description

The Motor Driver module consists of two parts, the feed current converter on the

mains side and the motor-end inverter.

 The supply converter for generating the intermediate circuit voltage is

designed as an unregulated diode bridge. To reduce the starting current

inrush, the system charges the intermediate circuit capacitors via a charging

resistor (an NTC thermistor).

 The IGBT motor-end inverter processes the transistor control signals, which

the controller supplies, and provides the measuring signals for closed-loop

control. The Motor Driver module has its own monitoring facilities (selfprotecting

power section).

Feed Current Converter

Within the Motor Driver module, the feed current converter is an unregulated

rectifier with starting current load relief.

The driver is the device which receives the actuator position command signal

from the controller and positions the actuator by means of controlling the current

and potential of the three phases of the actuator electromotor. The driver is

loaded with configuration settings for the EM-80 or EM-300 actuator and with an

application file for the proper and safe operation of the actuator system.

The driver is an integrated package of two main modules.

 Motor Controller module

 Motor Driver module

3522-1009

Marine Type Approval Compliance

Bureau Veritas (BV) Certified under BV Rules for the Classification of Steel

Ships.

EM 80 Driver 3522-xxxx

EM300 Driver 3522-xxxx

EM80 Actuator 8256-308

EM300 Actuator 8256-310

Det Norske Veritas Drivers 3522-1004 through 3522-1012

(DNV) EM-300 Actuators 8256-308 & 8256-310

Certified for Marine Applications

Temperature: Actuator Class B, Driver Class A

Humidty: Actuator and Driver Class B

Vibration: Actuator Class B, Driver Class A

EMC: Actuator and Driver Class A

Enclosure: Actuator Class C, Driver Class A