Torque Pulse Simulation
Unico’s Torque Pulse Simulation Drive is an all-digital AC flux vector drive engineered for engine-testing applications. The drive system consists of a Unico 2000 Series Performance Vector Drive that incorporates software designed specifically for simulating the torque pulses produced by internal combustion engines.
Unico’s internal engine simulator calculates the real-time torque output of an internal combustion engine based upon engine design characteristics. The torque output of the drive automatically updates with changes in throttle position and engine speed to provide a realistic simulation.
Unico’s torque estimator calculates the feedback torque produced by the motor without the need for expensive torque transducers. With a bandwidth that exceeds 2 kHz, the torque estimator provides feedback at rates that can track the profile of an individual torque pulse. When combined with Unico’s torque regulator, the drive can internally close the loop on the torque estimator to ensure that the amount of torque commanded is the amount that is produced.
The drive is capable of simulating torque signals up to 2 kHz. This allows it to simulate not only the fundamental frequency output of the engine, but the harmonics that make up the shape of the torque pulse as well. The result is a much more realistic engine simulation.
This hardware and software feature takes Unico’s performance digital signal processor (DSP) and adds a second processor that is dedicated to doing the engine simulation and vector control. By dedicating a processor to these tasks, software update rates of 20 kHz can be achieved, giving a significantly better reproduction of an actual engine torque pulse.
The drive can be configured for ultra-quiet operation using the built-in dual current regulators. The ability to set switching frequencies as high as 20 kHz makes the drive ideal for sound-sensitive applications requiring very low torque ripple.
With the inertia of an internal combustion engine being significantly smaller than a typical AC motor, the drive uses inertia simulation to cancel out the additional inertia of the motor so that the motor inertia appears to be the same as the internal combustion engine that is being simulated.
The drive has full four-quadrant operation with the ability to limit or block operation in any of the quadrants. Additionally, the drive has the capability to limit power for both motoring and regenerating modes.
The modular design of the drive allows individual components to be selected and sized for each application. Inverters for running motors and for use as line regenerative front ends are fully interchangeable, thus reducing the size of individual components and the quantity of spare parts required.
Motor Independent Design
A unique design incorporating a proprietary digital current regulator and a state-of-the-art controller allows the drive to operate any AC induction, AC synchronous, servo, or brushless DC motor without the current-loop setup required by conventional drives.
The drive features full automatic tuning capabilities that can be operated from either a remote terminal or the drive’s built-in keypad. After entering the motor nameplate data, the auto-tuning algorithm automatically identifies the additional parameters for operating the attached motor and configures itself for operation.
Control and Data Acquisition
The high-speed control option includes Unico’s Titan interface:
- Sampling capabilities up to 2 kHz
- 15” SVGA liquid crystal display with touch screen for test system status and results
- National Instruments data-acquisition hardware
- Windows 2000 OS
- Data acquisition and analysis
- Export capabilities
- Multiple test sequences
- Real-time display of test data
- Operator prompting
- Uses MS Excel 2000 for support files
- Control capabilities for load, drive motor, and product under test
The basic control option includes Unico’s Motion interface with sampling capabilities up to 10 Hz.
The standard interface included on all systems provides a keypad for programming the drive and entering engine parameters, speeds, and torques.
- Serial connectivity to various PLC, PC, and control platforms
- Three 14-bit analog commands
- Two 14-bit analog feedbacks
Machine Base with Hydraulic Power Unit
- Steel welded reservoir with 1/4”-thick sides, top, and bottom, cleanout end plate, side mount filler/breather, drain, sight gauge, and leveling pads
- 1”-thick Blanchard ground test bed with (24) 1/2” or M12 locating holes and mounting holes for servo base
- Servo motor mounting base weldment with motor mount bolt pattern and oil hole
- Hydraulic circulation system 3 to 5 gpm (10 to 20 lpm) including hydraulic pump, motor, couplers, flow control valve, relief valve, filter, and plumbing
- Power unit sound abatement cover
- Designed and built to customer specifications