ATC-M16_Report_1_0.pdf

Aberdeen Proving Ground – M16 Mobile Dynamometer © Copyright Dyne Systems, Inc.

Functional_Report_Rev1.0 i

DOCUMENT HISTORY

REVISION HISTORY

Revision Number Revision Date Summary of Changes Author(s)

1.0 04/30/2015 Initial Release Brad Staehler Mike Morrison

DISTRIBUTION

This document has been distributed to:

Name Title

Nate Simmons Mechanical Engineer

Kevin Brink Mechanical Engineer

Chanel D. De Silva Contracting Officer ii

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TABLE OF CONTENTS

1 Abstract

2 Purpose

3 Vehicle Make-Up (Electrical Focus)

3.1 Introduction

3.2 Prime Mover

3.3 Governor (Air Controlled)

3.4 Main Generator

3.5 Auxiliary Generator & Blower

3.6 Traction Motors

3.7 Electrical Control Cabinet

3.8 Braking Resistors

3.9 Control Modules

3.10 Operator Controls

4 Theory of Operation

4.1 Functional Modes

Truck Mode – Primary Operating Mode

Prime Mover Mode – Primary Operating Mode

Dynamometer Mode – Primary Operating Mode

Inch Mode – Secondary Operating Mode

Winch Mode – Secondary Operating Mode

4.2 Functional Block

Block Diagram

Block (1): Dash Components

Overview

Key Driver Controls

Key Dynamometer Operator Controls

Block (2): Air Panel

Block (3): Prime Mover

Engine

Generator – Main

Generator – Excitation

Block (4): Electrical Enclosure

Overview

Panel #1: Discrete Supporting Components

Panel #2: Supporting Control Relays and Speed Monitoring

Panel #3: Supporting Control Relays

Panel #4: Connection Terminals

Panel #5: EMD dash-2 Control Modules

Panel #6: Switchgear (1 of 2) – Power, Shorting, & Dynamic Braking

Panel #7: Switchgear (2 of 2) – Dynamic Braking & Reversing

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Panel #8: Contactors – Main Generator Field Control Status

Panel #9 – Traction Circuit Feedback Devices

Block (5): Traction Motors

Use Case – Motor

Use Case – Generator

Block (6): Transfer Case

Block (7): Driveline

Blocks (8 & 9): Resistor Grid Contactors (8) and Resistor Grid (9)

4.3 Functional Descriptions – Key Components

Speed Sensing Panel

EMD Dash-2 Control Module – VR12

Control Module – RC11

EMD Dash-2 Control Module – SB14

EMD Dash-2 Control Module – PF32

EMD Dash-2 Control Module – SE12

EMD Dash-2 Control Module – DR15

Barnes & Reinecke (BRI) Control Module

5 Evaluation of Major Components

5.1 Overview

5.2 Dash Components

5.3 BRI Control Module

Power supply and Monitoring Section

Electronic Speed Servo

Interface Circuit Board

5.4 Air Panel

5.5 Electrical Enclosure

General Wiring

Power Contactors

EMD dash-2 Control Modules

5.6 Traction Motors

5.7 Main Generator / Rectifiers

Generator

Rectifiers and Protective Fuses

Wiring

Other Components

Additional Comments

5.8 Auxiliary Generator

5.9 Resistor Grid Contactors and Resistor Grid

6 Conclusions

7 Parts List

8 Glossary of Terms

9 Resource Citations iv

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1 ABSTRACT

M16 Mobile Dynamometer

Figure 1

The M16 Mobile Dynamometer is a road vehicle used at the Aberdeen Test Center

(ATC) to test the power output of tracked and wheeled military vehicles. Typical testing performed by the M16 includes tractive power, resistance to towing, and braking capacity. To accomplish these tests, while also allowing for travel to and from the test course, the vehicle has three main modes of operation; Truck, Prime

Mover, and Dynamometer. Directional control in all three operating modes is accomplished via the steering wheel, it is in the control of acceleration or braking where the three modes differ. In Truck Mode, the vehicle acts much like a regular automobile through the use of accelerator and brake pedals at the driver’s feet.

Operation of the vehicle in Prime Mover and Dynamometer modes is similar to cruise control in a standard automobile. Operation of the vehicle in all three modes will be discussed later in this document.

The M16 was designed and built in 1979 by Barnes and Reinecke, Inc. (BRI) based in Arlington Heights, Illinois. It utilizes a locomotive platform situated on a custom frame and chassis. By utilizing a locomotive platform, standard locomotive control systems allow the vehicle to apply either tractive or braking effort, depending on the selected operational control mode. Common locomotive components used on the

M16 include an Electro-Motive Diesel (EMD) V8 engine with alternator, an auxiliary generator, DC traction motors, and EMD dash-2 electrical controls. Additional benefits to utilizing the locomotive platform include the usage of equipment readily available in the marketplace, and it was a mature technology that provided for stable and reliable operation.

In simplest terms, a dynamometer can be defined as an instrument that measures power output. When referring to vehicles, power output is the product of speed and force. To get an accurate mapping of a vehicles output power through its operational range requires tight regulation of either speed or force at each measurement point.

During testing in either Dynamometer or Prime Mover mode, the M16 utilizes tight speed regulation. The resulting force is a byproduct of the speed set point and available power from the test article.

At the time the M16 was built, speed control in standard locomotive control systems was accomplished via a throttle control lever or a brake control lever, each with eight preset settings. As described above, dynamometer type testing requires tight speed regulation, which is something the eight coarse settings of the standard throttle or brake lever simply could not provide. Therefore, BRI designed a custom speed control system which interfaces with the EMD dash-2 electrical controls.

The custom speed control system consists of a dash mounted assembly, a control panel mounted assembly, and multiple external speed sensing devices. The combination of these components allowed the speed to be controlled within ±0.1 km/hr of the speed set-point for speeds between 0.5 to 20 km/hr, and within ±0.3 km/hr of the speed set-point for speeds above 20 km/hr. [1]

On the force side of the power equation, the M16 can be used either by itself or in combination with up to two self-powered load trailers and the M-18 Mobile

Dynamometer to present a load to the test article. Used by itself, the M16 can generate drawbar loads up to 55,000 lbs. When used in combination with the trailers and the M-18, the combined equipment can generate drawbar loads in excess of

160,000 lbs.

In recent years, the M16 has been “increasingly prone to problems. Parts are difficult to obtain and recent repairs have required ATC technicians to troubleshoot and remedy board level problems associated with the speed control subsystem. Major components are no longer commercially available and replacement parts on hand for repairs have been depleted to a critical level. The original manufacturer and technical personnel are no longer in business to provide maintenance support or product improvement.” [2] While the breakdowns have been both electrical and mechanical in nature, the electrical breakdowns are causing ATC technicians the most trouble.

Taking into account both the age and current state of the M16, coupled with the advancements in technology over the past 35 years, there is a strong desire to upgrade the electrical control system. In efforts to help clarify the feasibility of an upgrade, this report focus on both the M16’s theory of operation and an evaluation of the major system components.

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2 PURPOSE

The M16 Mobile Dynamometer has been in use for over 35 years and is in need of an upgrade. Given the complexities inherent to the M16 design, several factors can influence the approach to and performance of an electrical control system replacement. These factors include:

The age of the system

Completeness of existing documentation

Accuracy of existing documentation

An understanding of custom control system operation and interaction with the standard locomotive control system

An understanding of major component functional status and usage

In order to better understand the requirements of a control system upgrade, it is first important to understand the functionality of the electrical control system based on the factors listed above, original design intent, and current operating state of the vehicle.

This report will discuss in detail the functional theory of operation of the control system as it relates to the various operational modes and their interaction with the major components of the system. During the process of data collection and analysis for this report, particular attention was given to the current state of the major electrical components used in the control system. A section of this report is dedicated to the inspection and evaluation of the major electrical components.

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3 VEHICLE MAKE-UP (ELECTRICAL FOCUS)

3.1 INTRODUCTION

The M16 Mobile Dynamometer is a diesel-electric hybrid vehicle used at the ATC for testing the power output of tracked and wheeled military vehicles. Designed and built in 1979 by BRI, it consists of a locomotive power system situated on a custom built chassis and frame. Major components of the power system include a diesel engine directly connected to a main generator and auxiliary generator. Power wires connect the generators to an electrical control cabinet, the DC traction motors for propulsion, and the resistor grid for braking power. In addition, there are several “standard” heavy duty truck components including an air brake system with on-board compressor, a transfer case connected to the drive axles and tires, and an alternator with on-board batteries for both 12V and 24V typical automotive type systems (i.e.

dash gauges, fuel pump, headlamps, windshield wipers, turn signals, etc.). An independent AC generator system is situated in the vehicle to provide standard

120/208Vac power for cabin lighting, heat, air conditioning, and data acquisition instrumentation.

There are three primary operational control modes: Truck, Prime Mover, and

Dynamometer. Truck mode is used for moving the vehicle to and from various sites within the ATC. In this mode, the vehicle operates like a typical heavy duty truck, where the speed is controlled via accelerator and brake foot pedals. Both the Prime

Mover and Dynamometer Modes are used for testing where the speed is electronically controlled via a speed set potentiometer located in the dash. To provide for safe operation, the brake foot pedal can be used at any time to override the current mode setting and bring the vehicle to a stop.

When used for testing higher power output vehicles, the M16 can be coupled with up to two additional load trailers and the M18 Mobile Dynamometer to provide the required loading. The vehicle is typically operated by a three person crew consisting of a driver, dynamometer operator, and engineer. The driver controls the steering of the vehicle and test article, the dynamometer operator controls the electronic speed control and auxiliary trailers (if used), and the engineer is responsible for data acquisition.

This chapter provides a basic overview of the major components, and their relationships to each other, used in the M16. See Theory of Operation, Chapter 4, for a detailed description of the operation and interaction of the major components.

3.2 PRIME MOVER

EMD Model 645E Series Engine

Figure 2

As is typical of any diesel-electric application, the system uses a diesel engine to provide the required power for all of the other system components. The M16 is powered by an EMD Model 645E series turbo-charged V8 engine capable of producing 1500hp. This engine is widely used in the locomotive and marine industries, and was typical of those found in applications from 1965 to today. The

645E series engine was designed for 24/7 continuous operation without the need for extensive maintenance.

In addition to normal engine components such as a 24Vdc alternator, batteries, fuel pump, cooling fans, etc., there are several important auxiliary components attached to various parts of the engine. The crankshaft of the engine turns the main generator which, in combination with a separate auxiliary generator, produces power for the traction motors. The auxiliary generator, or exciter, is connected to the auxiliary output shaft of the engine. A blower which provides cooling air for the main generator, exciter generator, traction motors, and electrical control cabinet, is also connected to this same auxiliary output shaft.

Since this engine is meant for continuous operation, once it has stopped for an extended period of time, there is a starting process that needs to be followed. This process involves opening a petcock on each cylinder and then barring the engine over by hand for at least one complete revolution. This process drives any water or coolant out of the cylinders in order to prevent cylinder damage during engine firing.

Upon completion of barring the engine over, the petcocks are closed and the oil pump is turned on. Once oil pressure is built up, the engine can then be started with the key. The M16 utilizes an air motor, rather than an electric motor, to start the engine.

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3.3 GOVERNOR (AIR CONTROLLED)

Woodward Air Governor

Figure 3

Once the engine is started, the engine speed is ultimately controlled by a pneumatic governor. The governor is located between the engine and the back wall of the M16 chassis. Depending on operating mode, the governor will be controlled by one of the following:

The throttle control foot pedal

The BRI Control System.

In Truck Mode the throttle pedal, in combination with the electrical control panel and traction motors, is used to control the vehicle speed. The throttle control foot pedal is a pneumatic regulator which varies the amount of air pressure in direct proportion to how far the foot pedal is depressed. In other words, the foot pedal allows the vehicle engine and ground speed to be controlled much like an automobile. When compared to an automobile, the most noticeable difference to the driver is the sluggish operation of the vehicle. This response is a function of the control system and will be explained later in the document.

During operation in Prime Mover and Dynamometer Modes the throttle foot pedal is taken out of the air circuit. Engine speed is controlled through a combination of electronics, the air control panel, and a voltage controlled pressure regulator. The voltage controlled pressure regulator, as shown in Figure 4, creates a simulated foot pedal signal which is sent to the governor for engine speed control. In these modes, the vehicle speed is set like a cruise control by a potentiometer dial located in the dash.

Voltage Controlled Pressure Regulator

Figure 4

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3.4 MAIN GENERATOR

EMD Main Generator (Model AR-5-B)

Figure 5

An EMD model AR-5-B generator is used to provide power for the traction motors.

The main generator is directly connected to the crankshaft of the engine. This connection provides rotational energy which is converted to 3-phase AC electrical energy by the generator. The 3-phase AC power is then converted to DC power for operation of the traction motors.

In general, the principal of operation for a motor and a generator is the same, it is the way the machine is utilized that determines the functional purpose. In the case of a motor, electrical energy is applied to the stator windings which creates rotation of the rotor shaft that can then be used as mechanical energy. In a generator, the situation is reversed in that mechanical energy is used to turn the rotor shaft which creates electrical energy at the stator windings. The main difference between the motor and generator is the direction of the energy conversion.

In the case of the main generator, a magnetic field must be present in order for any energy conversion to take place. The magnetic field is created by supplying DC electrical energy from the exciter to the rotating field windings of the main generator.

The generator’s AC output power is taken from the stationary armature windings.

The amount of AC power available from the generator is determined by the speed of rotation and the strength of the magnetic field in the field windings.

The AC power from the generator is converted to DC power by a group of diodes used to create a full wave 3 phase bridge rectifier. Typically, a bridge rectifier of this type would require 2 diodes per phase for a total of 6 diodes. Due to the M16’s power requirements, there are 10 diodes per phase connected in a parallel arrangement. These 10 diodes are grouped in pairs, with each pair having its own fuse for protection. The resulting 3 phase rectifier has a total of 30 diodes and 15 fuses.

The main generator is protected by a ground relay protection system designed to detect high voltage DC grounds, main generator AC grounds, shorted windings, or the loss of a phase. The ground relay protection system also protects the traction motors and high voltage wiring. [3]

3.5 AUXILIARY GENERATOR & BLOWER

Exciter Generator and Blower

Figure 6

The auxiliary generator, or exciter, as it is referred to in the system drawings, and the blower are connected to a common auxiliary drive shaft of the engine. The exciter generator provides field excitation power for the main generator and 74Vdc power for the electrical control cabinet. The blower provides forced cooling air for the main generator, traction motors, exciter generator, and electrical control cabinet.

Much like the main generator, the exciter generator produces 3-phase AC power which in turn is converted to DC power for use by other components. DC power conversion is accomplished by 2 different methods, a fixed rectifier circuit and an

SCR circuit. The fixed rectifier circuit is used to provide power to the electrical control panel. Whereas the SCR circuit is used to provide power to the main generator field coils.

The exciter generator output voltage must be tightly regulated for the circuits in the electrical control panel to operate properly. Voltage regulation is accomplished using an electronic regulator board located in the electrical control panel. Since the exciter generator provides power to the electrical control cabinet, which in turns controls the voltage produced by the same generator, this is considered a self-excited system.

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3.6 TRACTION MOTORS

DC Traction Motors

Figure 7

Power for propulsion and dynamic braking is provided by the two DC traction motors which are located in the mid-section of the vehicle. The output shafts of both motors are connected to a common transfer case. The transfer case has a single output shaft which connects it to the drive axles and wheels. Connecting both motors to a common transfer case forces the load on the M16 to be shared equally by the motors.

The motors have two sets of windings, field and armature, which are connected to switching components within the electrical control panel. The switching components change how the field and armature windings are connected based on whether the vehicle is in a motoring or braking state.

When motoring (i.e. driving in Truck Mode or operation in Prime Mover Mode), the traction motors are connected like a series wound DC motor. This means the armature windings and field windings are electrically connected in a series configuration. A series wound DC motor is capable of producing very high torque while maintaining a small footprint. The downside of using this type of motor is it is unable to self-regulate the shaft speed. Speed regulation is accomplished through a combination of controlling the voltage applied to the field and armature windings, and by applying a load to the motor. Since a series wound motor is capable of producing high torque but has poor speed regulation, it is important to maintain a load on the motor. As a worst case, when left unloaded the motor speed will keep increasing until it meets or exceeds its electrical or mechanical limitations.

While operating in Dynamometer Mode or during dynamic braking in any mode, the

DC traction motors are connected as a separately excited generator. In this configuration, the armature winding is disconnected from the field winding and connected directly to a resistor grid. The field winding continues to receive its power from the electrical control panel. When connecting the motor in this configuration it acts similar to the main generator described earlier. There are two main differences in using the traction motors as a generator as opposed to the main generator. First, the rotational energy for the motors is provided by vehicle motion through the wheels and transfer case rather than from the engine. Second, instead of using the electrical energy created by the traction motors to power the M16, the electrical energy created by the motors during dynamic braking is applied to a group of resistors where it is converted to heat. The amount of braking force generated by the motors is regulated by the vehicle velocity, traction motor field excitation, and the amount of resistance applied to the armature winding.

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3.7 ELECTRICAL CONTROL CABINET

Electrical Control Cabinet

Figure 8

The electrical control cabinet houses the majority of the power control components required for the operation of the vehicle. This cabinet, located directly behind the main cabin on the driver’s side of the vehicle, is typical of locomotive control cabinets.

Types of components located within this cabinet include power switching contactors for control of the traction motors, a speed sensing system for resistor grid control, and the EMD dash-2 series control modules. A detailed description of the various components and their function is included in Theory of Operation, Chapter 4.

3.8 BRAKING RESISTORS

Braking Resistor Grid (1 of 2)

Figure 9

The resistor grids, as described in Section 3.5, are located on either side of the vehicle just behind the main cabin. They can be seen in Figure 9, located behind the vents near the top of the vehicle. As electrical energy is applied to the resistors they produce heat. As more energy is applied to the resistors, there is more braking force applied to the vehicle, which results in more heat generated by the resistors. Cooling air is drawn across both resistor grids by a central roof mounted fan.

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3.9 CONTROL MODULES

EMD dash-2 Control Modules

Figure 10

Located within the electrical control cabinet, the EMD dash-2 control modules regulate and control much of the function of the M16. The control modules govern and regulate the operation of the main engine, main generator, exciter generator, and dynamic braking functions. See Theory of Operation, Chapter 4 for a more detailed discussion of these modules and their functions.

3.10 OPERATOR CONTROLS

View of Operator Controls

Figure 11

Within the main cabin of the M16 Mobile Dynamometer, the operator(s) have access to a variety of control functions. These control functions range from the selection of direction of travel, operational gear, primary operating mode, secondary operating mode, speed control, speed readout, force readout, and steering control. Figure 11, shows a picture of the main dashboard. The operator controls are discussed in more detail in Theory of Operation, Chapter 4.

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4 THEORY OF OPERATION

4.1 FUNCTIONAL MODES

TRUCK MODE – PRIMARY OPERATING MODE

The Truck Control Mode gives the driver direct control over the speed of the engine via the foot pedal on the floor. This mode is typically used in maneuvering the M16

Mobile Dynamometer to and from the test track.

In this mode of operation, the foot pedal acts much like an accelerator pedal in an automobile. By pressing the foot pedal towards the floor, pressure is allowed to build in the air circuit feeding the engine governor, which results in increased engine speed. As engine speed increases so does the voltage generated by the main generator. This voltage is then applied to the traction motors resulting in a tractive effort generated by the drivetrain. The amplitude of the voltage and magnitude of the current being generated by the main generator is tracked by the PF32 EMD Control

Module. This feedback is used to generate a power feedback signal that is looped through the BRI Control Module and to the SB14 EMD Control Module. The SB14

EMD Control Module is responsible for controlling field excitation of the main generator. It is worth noting, the BRI Control Module has no influence on the M16 control system when in Truck Mode.

In the Truck Control Mode, a change in engine speed will lead to a change in vehicle power. This relationship is regulated by the RC11 EMD Control Module. The air pressure being used to control engine speed is monitored by the RC11. A change in air pressure feeding the governor results in an engine speed change. To avoid shock-loading the M16 chassis and/or bogging the engine, the RC11 controls the rate at which system power is changed by providing a rate control variable to the

SB14 EMD Control Module.

PRIME MOVER MODE – PRIMARY OPERATING MODE

The Prime Mover Control Mode acts as a motoring control mode. It gives the dynamometer operator the ability to regulate the speed of the M16 strictly through motoring effort. This acts much like cruise control in an automobile, removing the function of the foot pedal, and automating the action of engine throttle control based on the vehicle’s speed reference. The speed reference is set by the Speed Adjust potentiometer on the dash and is fed to the BRI Control Module. The BRI Control

Module processes this speed reference and compares it to a speed feedback, supplied by the M16’s 5th-wheel encoder, to develop a speed error signal. The speed error is used, in conjunction with other EMD Control Modules, to control both the engine speed and main generator field excitation. Function of the EMD Control

Modules is the same as described above for Truck Mode.

DYNAMOMETER MODE – PRIMARY OPERATING MODE

The Dynamometer Control Mode acts as a dynamic braking control mode. It gives the dynamometer operator the ability to regulate the speed of the M16 strictly through braking effort. This acts like cruise control for the operators brake pedal. The Speed

Adjust potentiometer and the 5th-wheel encoder interface the same as they did in

Prime Mover Control Mode. The BRI Control Module also functions in much the same fashion.

In this mode, the traction motors are utilized as generators. The speed of the motor shaft is governed by road speed and the field of each motor is regulated by generated voltage from the main generator. The speed of the engine is kept constant. The voltage generated by the traction motors is applied to a resistor grid.

Current developed through the resistor grid results in vehicle braking force. The braking current is monitored by the EMD Control Modules and a power reference is supplied by the BRI Control Module. Using these two signals, the SB14 EMD Control

Module regulates the main generator field excitation. By regulating field excitation of the main generator the voltage applied to the traction motor fields is controlled. In addition, the total resistance of the grid is modified at five different speed points. This is done to match the total resistance with the traction motors ability to generate voltage within a given speed range. It is this method that is used to control resistor grid current and braking force.

INCH MODE – SECONDARY OPERATING MODE

The Inch Mode of operation can be considered a functional mode within the Truck

Mode selection. Inch Mode functions similar to Truck Mode in that the accelerator foot pedal is used to control vehicle speed. The difference being that Inch Mode provides fine speed control at low ground speeds. When operating in Inch Mode, the

M16 is power limited which, in part, provides the fine speed control. The engine speed is limited and the control over the main generator’s field excitation is altered.

While a depression of the accelerator foot pedal may result in a large swing in engine speed/vehicle power when operating strictly in Truck Mode, in Inch Mode that same amount of pedal movement will result in a much smaller change. This mode is typically used when connecting to the test device or when parking the M16.

WINCH MODE – SECONDARY OPERATING MODE

The Winch Mode of operation can be considered a functional mode within the

Dynamometer Mode selection. Winch Mode is similar to Dynamometer Mode in that the M16 is utilized to generate braking effort. The difference being that Winch Mode provides fine speed control at low ground speeds. In this mode, the amount of braking effort is limited by the ground speed of the M16. Low ground speed correlates to low shaft speed on the traction motors. Therefore, traction motor voltage generation is limited. This mode is typically used to test recovery winches.

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4.2 FUNCTIONAL BLOCK

BLOCK DIAGRAM

Figure 12

BLOCK (1): DASH COMPONENTS

OVERVIEW

Within the main cabin of the M16 Mobile Dynamometer, the operator(s) have access to a variety of control functions. These control functions include the selection of travel direction, operational gear, primary operating mode, secondary operating mode, speed control, speed readout, force readout, and vehicle steering. A picture of the main dashboard is shown in Figure 13.

Figure 13

As mentioned earlier in the document, the M16 is typically operated by a three person crew consisting of a driver, dynamometer operator, and engineer. The driver controls the steering of the M16 in conjunction with the test article. The dynamometer operator is responsible for speed control, monitoring of vehicle loading, and the control of auxiliary trailers (if used). Finally, the engineer is responsible for data acquisition from the test article.

The following sub-sections will cover the major control functions used by each crew member.

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KEY DRIVER CONTROLS

DIRECTION SWITCH - FORWARD, NEUTRAL, AND REVERSE

The direction selection switch is labeled “FWD” “NEUTRAL” and “REV.” It is a 3-position selector switch located slightly down and right of the steering column. The selector switch is used by the driver to identify the direction of travel that is desired.

MODE SELECTOR SWITCH – DYNAMOMETER, TRUCK, AND PRIME MOVER

The primary “Mode Selector” switch is labeled “DYNMT” “TRUCK” and “PRIME

MOVER.” It is a 3-position selector switch located near the speed adjustment potentiometer. The selector switch is used by the driver to select the desired mode of operation.

SECONDARY MODE SWITCH – WINCH, INCH, AND NORMAL

The secondary mode selection switch is labeled “WINCH” “INCH” and “NORMAL.” It is a 3-position toggle switch located adjacent to the Direction Switch. The toggle switch is used by the driver to select the type of control required for the desired vehicle function. Normal will result in speed control with full vehicle power available.

Inch will result in fine low speed control with limited vehicle power available. This is typically used in conjunction with Truck Mode. Winch will also result in fine low speed control with limited vehicle power available. This is typically used in conjunction with Dynamometer Mode.

TRANSFER CASE SWITCH – HIGH AND LOW

The transfer case gear selection switch is labeled “HIGH” and “LOW.” It is a 2-position toggle switch located below the Mode Selector switch. The toggle switch is used by the driver to select the gear in which the M16 will function. This selection is made based on speed and load requirements for a given test article.

FOOT PEDAL

The foot pedal acts much like an accelerator pedal in an automobile in that it is used to control engine speed. It is located under the steering column at the driver’s feet.

Engine speed increases as the pedal is depressed. The foot pedal is only active when the M16 is in the Truck Control Mode. Truck Mode is typically used when driving the M16 to or from the testing location.

KEY DYNAMOMETER OPERATOR CONTROLS

SPEED ADJUST POTENTIOMETER

The speed adjust potentiometer is labeled “SPEED ADJ.” It is a multi-turn type potentiometer with a numerical display. The display correlates to the commanded speed reference. The potentiometer is used by the dynamometer operator to regulate the speed of the M16 in effort to achieve the desired load points for the test.

This potentiometer is only functional when in either the Dynamometer or the Prime

Mover control modes.

SPEED CONTROLLER WITH GAIN ADJUST POTENTIOMETER

The speed control module is integral to the dash and is located right of the traction trailer controls. This control module provides both feedback to the dynamometer operator and a means to adjust the control system response. The feedback indicator lights along with the analog DC meter provide active status of the control system. In addition, a potentiometer is provided for the purpose of gain adjustment. This is used to “tune” the control system in efforts to modify the M16’s response to test dynamics.

Speed feedback is provided to the speed controller from a 5th-wheel with integrated encoder feedback. The 5th-wheel must be lowered whenever the speed controller is to be used. Height adjustment of the 5th- wheel can be accomplished through the

“FIFTH WHEEL” adjustment toggle switch. This 3-position toggle switch is non-maintained with a spring return to the center position. The switch positions are labeled “RAISE” and “LOWER.” Speed feedback is displayed on a panel meter labeled ‘VEHICLE SPEED” located above the Speed Adjust potentiometer.

TORQUE MEASUREMENT AND READOUT

There are two torque measurement devices installed on the M16, one at the front of the vehicle and one at the rear. Each are tension/compression style load cells. The feedback from each device is fed to a Himmelstein 700 series processing module for display. This display is used by the dynamometer operator when setting the velocity reference using the Speed Adjust potentiometer. It is also used to monitor the load being presented by the traction trailers (if used).

TRACTION TRAILER CONTROLS

When running in the Dynamometer Control Mode, up to two traction trailers (load trailers) can be connected to the rear of the M16 to increase its loading capacity.

Each load trailer is self-excited using an on-board generator. The trailers are monitored and the field of the trailer’s generator is regulated utilizing the traction trailer controls in the cabin of the M16. These controls are located on the dash panel to the left of the BRI Control Module.

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BLOCK (2): AIR PANEL

The Air Panel is integral to the control of engine speed and is located behind the electrical enclosure. Access to air panel components can be obtained from inside the

M16. Internal to the air panel enclosure are the components called out on Barnes &

Reinecke, Inc. drawing D27 as part of the “Control Box Assembly”. The following table provides a listing of the components installed in the air panel:

Figure 14

Based on the mode of operation selected (Truck, Prime Mover, or Dynamometer) the air circuit functions differently. When in a motoring mode of operation, air pressure is directly related to throttle position. Throttle position is controlled by the air pressure sent to the engine governor. As air pressure builds the engine speed increases and conversely as air pressure decreases the engine speed decreases. When in a dynamic braking mode of operation, the air pressure to the engine governor is held constant which keeps the engine speed constant.

If the M16 is operated in Truck Mode, the air pressure is regulated by the driver’s foot pedal. By pressing the pedal towards the floor, pressure is allowed to build in the air circuit feeding the engine governor. The air being supplied to the engine governor is processed by multiple components internal to the air panel. When in Truck Mode, air is routed from the supply through the foot pedal (THROTTLE TREDDLE VALVE) and through a shuttle valve external to the air panel. The air entering the air panel is routed to the “AS” pressure switch and then to the input of shuttle valves #1 and #2.

“SHUTTLE VALVE #1” directs airflow to a Rotary Actuator. A pressure transducer is installed in the same airline for the purpose of air pressure feedback to the RC11

EMD Control Module. “SHUTTLE VALVE #2” directs airflow through a solenoid valve to the engine governor.

When in Prime Mover Mode, the air circuit is configured slightly different. External to the air panel, the airflow can take two paths, either through the foot pedal or through an electrically controlled pressure regulator before it passes through a solenoid

“VALVE STACK.” The “VALVE STACK” is responsible for directing airflow given the selected mode of operation. This supplies airflow to the opposite input of the same shuttle valve that is supplied by the foot pedal. This shuttle valve will allow airflow from the input with the highest pressure. From the point of entry into the air panel the same air circuitry is utilized as in Truck Mode. The difference being, the air pressure supplied to the air panel is regulated by an interface between the BRI Control Module and the electrically controlled pressure regulator, rather than the foot pedal.

Location Tag Drawing Component Related Function

DBMV1 D 27, R-65 Solenoid Valve Engine Speed Air Circuit Control -

Dynamic Braking

DBMV2 D 27, R-65 Solenoid Valve Engine Speed Air Circuit Control -

Motoring/Acceleration

BS D 27, R-65 Pressure Switch Engine Speed Air Circuit Monitor -

Pressure Feedback to Brake Control Circuit

AS D 27, R-65 Pressure Switch Engine Speed Air Circuit Monitor -

Pressure Feedback to Acceleration Control Circuit

Regulator D 27 Pressure regulator Engine Speed Air Circuit Control -

Engine Throttle Position

Actuator D 27 Rotary Actuator Engine Speed Air Circuit Control -

Air Circuit Dampener

Pressure Sensor D 27 Pressure Sensor Engine Speed Air Circuit Monitor -

Pressure Feedback to RC11

Shuttle Valve D 27 Shuttle Valve Engine Speed Air Circuit Control -

Air Flow Direction

Solenoid D 27 Solenoid Valve Engine Speed Air Circuit Control -

Engine Throttle Position

Air Panel

When in Dynamometer Control Mode, the air circuit is configured different than either of the other two functional modes. Air supplied to the valve stack is passed to the input of a shuttle valve external to the air panel. The other input of this shuttle valve is supplied by the “DUAL BRAKE VALVE.” The “DUAL BRAKE VALVE” supplies air to the input of the shuttle valve whenever the foot brake is applied by the driver. The output of this shuttle valve then feeds the air panel. Internal to the air panel, airflow is routed through the “BS” pressure switch, the “DBMV2” solenoid, and to the pressure transducer providing pressure feedback to the RC11 EMD Control Module.

Air pressure must be removed from the “AS” pressure switch prior to the closing of

“DBMV2”. When operating in this mode, engine speed remains constant. A fixed air pressure is supplied to the engine governor through the uncontrolled “PRESSURE

REGULATOR,” the “DBMV1” solenoid valve, and “SHUTTLE VALVE #2”. Despite the mode of operation, dynamic braking by means of the driver’s brake pedal functions in the same fashion except the air supplied from the “DUAL BRAKE

VALVE.”

An additional solenoid valve (ASCO) has also been installed in-line with the air line running out to the engine governor. This additional valve provides a means to cut-off airflow to the engine governor as required by the M16’s control system.

Figure 15

Functional_Report_Rev1.0 25

BLOCK (3): PRIME MOVER

ENGINE

An EMD Model 645E series turbo-charged V8 engine capable of producing 1500Hp is used in the M16 Mobile Dynamometer. The V8 engine is responsible for providing the mechanical energy necessary to run the M16. The engine’s mechanical energy is used to drive the rotor shafts of the main generator and the exciter generator.

Each generator takes mechanical energy provided by the engine and converts it to electrical energy used for vehicle propulsion and as a supply to other supporting devices.

GENERATOR – MAIN

A generator is a machine responsible for converting mechanical energy to electrical energy. In the case of the M16, the mechanical energy is provided by the EMD 645E series turbo-charged V8 engine which is directly coupled to the rotor of the AR5 generator assembly. This mechanical energy is then converted to electrical energy in the form of a 3-phase, Wye connected, alternating current (AC). The 3-phase AC voltage generated by the generator is rectified through a full-wave fixed bridge rectifier. The resulting direct current (DC) voltage is then supplied to the traction motors and used as a means to control the M16’s movement.

The AR5 generator used on the M16 can be defined as a synchronous machine, a machine in which the rotational speed of the rotor is directly proportional to the frequency of the voltage developed across the stator windings. The rotor windings of the AR5 are excited by an external DC source, which develops a fixed flux in the rotor. As the rotor is rotated by the engine, the rotor flux intensity varies with respect to the stator windings. This varying flux induces an alternating current into the stator windings and a voltage is developed. In general, the root-mean square (rms) value of the phase voltage generated in a synchronous machine can be expressed as follows:

𝐸𝑎 = 𝐾 ∗ ∗ 𝜔

Where:

Ea Generated Voltage (Vac)

K Motor Constant

Φ Rotor Flux w Rotational Speed (radians/second)

The amplitude of the generated voltage is directly related to two controlled variables, the speed of the rotor and the magnitude of the rotor flux. An increase in either the rotor speed or rotor flux will result in an increase in the amplitude of the generated voltage.

In regulating the generated voltage, the M16 utilizes control over both of the variables listed above. By way of an air actuated engine governor, the rotational speed of the engine is controlled. Since the engine shaft is directly coupled to the generator rotor the speed of the generator is controlled by the engine speed. In addition to rotor speed control, the M16’s control system also has the ability to indirectly control the rotor flux. The excitation generator, coupled to a secondary engine shaft, provides voltage to the AC side of a full-wave controlled bridge rectifier located inside of the main generator’s enclosure. In conjunction with the EMD dash-2 control modules, the magnitude of the rectified DC voltage being applied to the main generator’s field is regulated. It is by means of field voltage regulation that the field current, and the resulting motor flux, is controlled. More on the excitation generator and the EMD dash-2 control modules will be discussed in the coming sections.

A variety of supporting components are housed internal to the main generator’s enclosure. Figure 16 shows general placement of the internal components.

Figure 16

Functional_Report_Rev1.0 27

Within the main generator’s enclosure is a combination of series RC circuits responsible for the suppression of transient voltage spikes. The R and C components have been circled in Figure 16. These transient voltage spikes occur during commutation. In general, commutation can be defined as the process of transferring current from one connection to another within an electric circuit. In this case commutation refers to the transition of the diodes, used in the full-wave fixed bridge rectifier, from a conducting state to a blocking state. During this transition there is a short time when a high reverse current flows though the diode. When the diode finishes the transition to a blocking state, this high reverse current suddenly drops to zero. It is this event, in combination with other circuit characteristics, which causes transient voltage spikes. Without suppression, these spikes can have amplitudes large enough to exceed the reverse rating of the diodes and cause diode failure. By adding filtering to the circuit, by means of series RC combinations across the phase legs of the main generator, these transient voltages are greatly reduced.

This in turn protects the diodes and prevents premature component failures. Figure

17 depicts the configuration of the suppression circuit. [3]

Figure 17

GENERATOR – EXCITATION

Like the main AR5 generator, the excitation generator (EXC) functions as a 3-phase synchronous machine. More information on the function of a synchronous machine acting as a generator can be found in the previous section Generator – Main. The

EXC generator’s rated capacity is significantly smaller than the AR5 generator and is coupled to a secondary drive shaft found on the EMD 645E series turbo-charged V8 engine.

Electrical energy generated by the EXC generator is utilized in the following M16 functions.

1. Main AR5 Generator Field Excitation

2. Main 74Vdc Control Bus Supply

The field excitation of the AR5 generator is regulated using a full-wave controlled bridge rectifier (SCR) housed internal to the AR5 generator’s enclosure. The SCR receives 3-phase AC voltage from the EXC generator for the purpose of the AR5 generator’s field excitation control.

The SE12 control module, part of the EMD dash-2 family of control modules, is responsible for controlling the SCR bridge. In conjunction with the feedback from the

SB14 control module, the SE12 controls the firing angle used to trigger the on-state of the rectifier bridge’s switch elements. This firing angle is adjusted for each electrical cycle of the voltage generated by the EXC generator.

In addition to supplying energy for field excitation of the AR5 generator, the EXC generator also supplies the 74Vdc control bus. The 74Vdc control bus is fed from a full-wave fixed bridge rectifier (CRCR) which in turn is fed from the secondary of a 3-phase transformer (TREX). The primary of the TREX transformer is fed directly from the EXC generator.

Many of the ancillary control devices used in the M16 are rated for use with a voltage of 74Vdc. To ensure proper operation of the ancillary devices the control bus supplied by the EXC generator must be regulated to 74Vdc. In the case of the EXC generator, the speed of the engine cannot be controlled for the purpose of regulating the EXC’s generated voltage. This is because the rotor of the EXC generator is directly connected to an engine drive shaft and the engine’s rotational speed is controlled for the purpose of regulating the main AR5 generator’s output voltage.

This leaves field control of the EXC generator as the only feasible method to regulate the amplitude of the generated voltage. Field control is performed by the VR12 control module, part of the EMD dash-2 family of control modules. In short, the VR12 acts as a voltage regulator connected in between the positive 74Vdc bus and the

EXC generator’s field winding. By controlling the amplitude of the voltage applied to the EXC generator’s field winding the field current and magnitude of the rotor flux is controlled. As speed of the engine’s drive shaft increases, the amplitude of the control bus voltage also increases. In this scenario, the voltage applied to the EXC generator’s field winding is reduced, therefore compensating for the increased shaft speed and maintaining the control bus voltage at 74Vdc.

When starting the EMD 645E series diesel engine, residual magnetism internal to the

EXC generator is used to begin the process of voltage generation. This is accomplished by utilizing a No Voltage Relay (NVR) driven by a No Voltage Relay

Driver (NVRD) that ties the rectified voltage generated across the stator winding to the field winding. The residual magnetism in the generator is used to excite the field winding. As field excitation increase so does the generated voltage. This loop is maintained until adequate voltage has developed on the control bus, at which time the NVR relay coil energizes (relay contact opens) and the responsibility of voltage regulation transitions to the VR12 control module.

Functional_Report_Rev1.0 29

BLOCK (4): ELECTRICAL ENCLOSURE

OVERVIEW

The electrical enclosure is integral to the M16 Mobile Dynamometer’s vehicle body.

This enclosure can be accessed using two swing doors located outside the cabin on the driver’s side of the vehicle.

Figure 18

The electrical enclosure houses many of the electrical components responsible for vehicle function. Key items in this cabinet include control modules, control relays, termination points, high-power switch gear, and much of the interface wiring. The enclosure is broken up into nine panels; the location of each panel is shown in Figure

19.

Figure 19

In general, the layout of the cabinet is such that the high-power electronics are located in the bottom half of the enclosure and the control devices are located in the top half. The majority of wire entrance and exit locations are behind or below Panel

#4.

PANEL #1: DISCRETE SUPPORTING COMPONENTS

Related Drawing: D-521

Panel #1 holds many of the discrete components required to support the M16’s electrical functions. These components support functions such as ground fault detection, voltage monitoring, dynamic braking, and generator field excitation. In addition, these components also interface with the M16’s control modules. The following table provides a listing of the components installed on Panel #1:

Figure 20

Location Tag Drawing Component Related Function

TRPF1 (TRGP1) R-65 Transformer SB14 Control Module Interface

TRPF2 (TRGP2) R-65 Transformer SB14 Control Module Interface

RELD R-65 Resistor (Power) Excitation Alternator Field

REGR R-65 Resistor (Power) Ground Fault Identification

REEF R-65 Resistor (Power) Excitation Alternator Field

CRTL1

CTRL2

REDB R-65 Resistor (Power) Vehicle Over Speed Control

CRDB R-65 Rectifier Over Speed Dyne Brake Control

CRRCD R-65 Rectifier Over Speed Dyne Brake Control

CRFD R-65 Rectifier Ground Fault Identification

CRGR R-65 Rectifier Ground Fault Identificaiton

REDBLR R-65 Resistor (Power) RC11 Control Module Interface

RERC R-65 Resistor (Power) RC11 Control Module Interface

CANV R-65 Capacitor No Control Voltage Monitoring

CREX R-65 Rectifier Excitation Alternator Generated Voltage

CAGR R-65 Capacitor Ground Fault Identification

TRBWR R-65 Transformer Dynamic Braking

TR…