Purpose of the Universal Solenoid Driver
The Universal Solenoid Driver (version II) from Global Electronics, Ltd is a modularized system that drives multiple solenoids from any of a variety of different electronic circuits whose configuration and operation are dynamically controlled by the user’s host computer. In this manner, solenoids in automotive transmission test stands or any industrial bench test consisting of automotive-sized solenoids can be driven according to engineering requirements.
Specifically, the USD-II consists of a 19 inch-wide chassis with a Motherboard designed to accept 7 plug-in modules. In most cases, these modules are used to drive transmission solenoids; however, other specialized modules have been developed to provide specific functionality requested by users. (One such example is the Speed Sensor module, which measures the frequencies of pulses from speed sensors within the transmission, allowing engineers to monitor rotation of various parts of the transmission in response to control signals sent to its solenoids by other modules in the USD-II rack.)
The electronics within each type of plug-in module vary according to the type of solenoid driver chip(s), the number of solenoids (channels) that each module can control independently, and the set of commands from the host computer appropriate to each type of solenoid driver. Users may install any type and number (up to 7) of modules in a rack, and multiple racks may be daisy-chained together if more than 7 modules are needed. The host computer communicates with each module according to the unique slot ID (and rack ID, if multiple racks are used).
Contents of Plug-In Modules
Every module consists of several circuit boards, one of which is a common circuit board called the “Smartboard”. This board contains the microcontroller that translates CAN messages from a PC into the form needed by the particular driver chip(s) located on a daughterboard in the module. (The exact data in these CAN messages will vary according to the requirements of the driver chip.)
The daughterboard contains the same type of solenoid driver electronics used by the manufacturer in its production controller. By matching the circuitry within the USD-II module’s daughterboard to the production hardware, engineers are assured that test stands used in product development or production testing match the behavior seen in finished products. This feature is what makes the USD-II unique.
For example, if an automaker’s Transmission Control Unit contains driver chips from IC manufacturer Infineon, part number TLE7242-2G (known commonly as the “Adler” chip), then the same chips are utilized in the “Adler” modules for the USD-II. Similarly, Infineon chips “Adler 2” and “Phoenix” are found in the USD-II modules “Adler 2” and “Phoenix”, respectively.
Since the inception of USD-II, many different types of modules have been created at the request of users in order to match the various drivers that appear within production automotive solenoid controllers. During this time, solenoid drivers have evolved from simple “On/Off” control to more sophisticated variable duty cycle control, used on so-called Variable Force Solenoids (VFS) which have a range of operation between “On” and “Off” according to the commanded duty cycle.
Lately, even more advanced driver chips incorporate a closed feedback loop between the driver and the solenoid, so that the chip adjusts the duty cycle of applied power so as to achieve the desired average coil current. In an example of this, the Adler 2 chip receives a command for the desired coil current (instead of a specified duty cycle), and the chip achieves that current by regulating the duty cycle via a PI controller in the chip. Along with the “Set Current” command, users can adjust the PI control constants and many other parameters via CAN messages from the PC.
External Interfaces to Modules
Because the USD-II is driven by a PC having a CAN interface, users can write software to send CAN messages directly to the Smartboard in the UDS-II module according to the desired actions of the solenoid driver. As mentioned, the commands appropriate to each type of driver vary, so the Smartboard is “smart” enough to know which type of daughterboard is plugged into it, and will translate the CAN messages into the exact format appropriate for that driver on that daughterboard.
USD-II is used in both development and production testing, including end-of-line testing. In some cases, users need to monitor solenoid current flow by means of a third circuit board (known as an “Analog ICE board”) within the module that outputs a set of voltages proportional to the current flow in each channel. This optional configuration is identifiable by the 9-pin D-sub connector on the front of the module.
Selection of System Components
As future types of solenoid drivers are developed for automotive products, Global Electronics will create additional USD-II modules to incorporate these new drivers, depending on demand of customers and their collaboration with Global Electronics in the development.
The USD-II system components provided by Global Electronics include the USD-II rack, USD-II plug-in modules as ordered, and optional power and wiring harnesses. Customers supply their own power supply to the rack (12 V at 20 A recommended), a host computer with a CAN interface (implemented as either a PC card for desktop computers or a USB-to-CAN interface adapter), and programming software of their choice for sending the appropriate control messages to the modules via CAN. Global provides a demo PC executable program to operate the USD-II until users replace it with their own customized programs.