17.Do you really know AV-Product Dynamic Processing System? (3)

Battery Emulation

With its computer control capabilities, the ABC-150/DCU can be programmed to emulate a battery. The ABC-150/DCU would first be put into constant Voltage Mode at the desired state of charge. As current is drawn from the ABC- 150/DCU, the voltage would be lowered as if the?battery?were being discharged.

Similarly, as the ?battery?is charged, the voltage would be increased. The algorithm to determine how voltage changes in response to charging and discharging would be determined by the user, based on the size and type of battery to be emulated, and then programmed into the ABC-150/DCU Remote Operation System.?

System Block Diagram

The ABC-150/DCU architecture is shown in the following system block diagram. The AC Inverter connects to the utility via an isolation transformer. The DC Converter and AC Inverter transfer power via an Intermediate DC Bus and communicate via an RS-485 data bus. The DC Converter also communicates to the ABC-150/DCU Remote Operation (ROS) System via an RS-232 data link. The DC Converter provides the DC interface to a load (or possibly two separate loads) in one of two configurations.

AC Inverter Functions and Controls

The AC Inverter interfaces the utility to an internal Intermediate DC Bus. The Intermediate DC Bus is regulated by the AC Inverter based on the maximum voltage expected by the DC Converter connected. The range for the Intermediate DC Bus is 350 - 425 Volts DC. (An optional upgrade raises the maximum Intermediate DC Bus voltage to 450 Volts DC.)

Circuitry designed into the AC Inverter monitors the utility to detect any abnormalities. This is accomplished by measuring the frequency and amplitude of the utility and verifying that it remains within the specified range given in the Technical Specifications.

The AC Inverter operates under current control instead of the more common phase control. This allows for a more robust interface to the utility and linear response in the inverter dynamics.

In addition, references for the current are obtained from the utility wave forms, thereby maintaining the AC Inverter as a true unity power factor interface regardless of line harmonics.

The following Figure shows the AC Inverter front panel. Each of the front panel controls and indicators are described below.

MAIN POWER:Pressed to apply and remove power to the system. The switch is illuminated when power is applied to the system.

EMERGENCY OFF: pressed to remove all power to the system. The switch has a locking mechanism and must be rotated counterclockwise to enable the system to be repowered.

NOTE: Either switch must be used to remove power to the system for at least five minutes prior to accessing the interior of either cabinet for service.

READY light:(Green) when the system power is on and the system is functioning normally.

FAULT lights:(Red) when a fault has been detected. The four lights are AC Inverter Fault, DC Converter Fault, Utility Fault, and Communication Fault. (Refer to Table 5.1 in Section 5 of this manual to determine the definition of any faults indicated.)

DC Converter Functions and Controls

The DC Converter monitors load connections, processes power from the Intermediate DC Bus for the load, and provides a local control interface for the user.

The DC Converter is composed of two separately controllable converters, converter A and converter B. Each converter has its own set of front panel meters, mode select switches and output terminals.

The converter has the ability to operate in two different configurations:

Independent Configuration:Two loads can be connected and separately controlled. (The negative sides of the ABC-150/DCU outputs are tied together when outputs are active, so the two outputs cannot be placed in series.)

Parallel Configuration:The output from the converter (A) has double the current capability but the same voltage limitation as the Independent configuration. This configuration is called Parallel because internally the two converter circuits are connected in parallel to provide higher current capability. The DC Converter can present the power to the load using a variety of control algorithms (modes). It can be operated as a constant current source, a constant voltage source or a constant power source. In addition, limit values for voltage, current, and power are specified by the operator to additionally constrain the output. The DC Converter incorporates safety features that minimize the possibility of an improperly connected load or hazardous voltage exposure. The DC Converter monitors internal switches, which indicate when load connectors are inserted and verifies that the load connections and the chosen configuration are compatible. If the load configuration requested does not match the load connections, the requested configuration will not be acknowledged. Additionally if one of the connectors is removed from the unit, the internal contactors will open automatically disconnecting the output from the load.The internal contactors remain disconnected during load configuration or reconfiguration, and will also be disconnected in the event of a load fault condition (e.g., a short circuit) or an unsafe operating condition (e.g., a voltage higher than the user-defined limit).?

The displays and controls are described below.?

1.CONFIGURATION

(yellow) is used to select the load configuration and wiring connection. There is one button each for Parallel, and Independent.

2.LIMITS

(yellow) is used to set upper and lower operating limits for each converter. The user presses either the UPPER or the LOWER button to view the existing limits and holds the button down while pressing the Up arrow and Down arrow buttons to adjust those limits. Upper and lower limit buttons are included for each converter (A and B). When these buttons are flashing, the DC Converter is prompting the user to check the operating limits and adjust them if necessary.

3.MODE

A mode determines what control algorithm a converter will use. The choices are VOLTAGE, CURRENT, POWER control (green), or STANDBY (red). When all four of these buttons on one converter (A or B) are flashing, the DC Converter is prompting the user to choose a mode. When a mode has been selected, only the appropriate button will be lit (not flashing) for that converter. Another mode button may also be flashing at the same time if the DC Converter is at an operating limit for one of the parameters that is not being controlled.

4.STATUS

Each channel will display (remote) status independently (Remote A and Remote B). When operating remotely, the REMOTE button will be lit for that channel. When the system is initially powered up, it begins in local operation.

5.PROTECTED REMOTE OPERATION

While operating in Remote mode, the operator can change the status of the ABC-150/DCU to standby by pushing the Standby button. This action will cause the output contactor to open, isolating the output of the respected channel from the load. To re-initiate Remote mode operation, the operator must manually push the flashing Remote A/B button, which will resume operation under ROS control.??

Communication Between AC Inverter and DC Converter

The AC Inverter and DC Converter communicate over an RS-485 high speed, multiplexed data bus. This communication bus is not intended to be accessed by the user at any time. The AC Inverter sends information about its status and mode of operation to the DC Converter. The DC Converter sends fault status information and communicates to the Remote Operation System (ROS) via an RS232 link.

Remote Operation Interface

The Remote Operation Interface, based on the RS-232 communication standard, allows communication between the DC Converter and the ABC-150/DCU (ROS). The purpose of this interface is to provide status information and DC output measurements from the ABC-150/DCU to the ROS and to accept commands from the ROS. For more information about the Remote Operation Interface, please refer to the ABC-150/DCU Remote Operation System Manual, AeroVironment document number 05953.?

ABC-150/DCU Remote Operation System ROS

The ABC-150/DCU ROS is a personal computer based system for controlling the ABC- 150/DCU. The system consists of the computer itself and any peripherals, and the ABC- 150/DCU ROS application. This software provides a graphical user interface for controlling and monitoring the operation of the ABC-150/DCU, a command language interpreter that allows for simple implementation of complex test programs, communication with the ABC- 150/DCU system, and the option of integrating external data acquisition devices into the system.

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Author:Allen He