The elevator-specific inverter is a high-end product in medium and small power inverters. Although China is the world's largest elevator manufacturing country, the elevator's core component elevator special inverter is monopolized by foreign brands. The special control algorithm for elevator characteristics needs to be long-term. Accumulating and perfecting in production practice; elevator inverter software system is a huge complex real-time hybrid (Hybrid) software system. Developing stable and mature elevator inverter software is a serious engineering challenge. This paper mainly introduces C/C++ in this DSP. Under the integrated development environment CCS (Code Composer Studio), how to develop elevator real-time multi-tasking software system based on object-oriented technology, the core concept of software system development is software layering and virtual device-based
1. Functional requirements and software system structure of elevator inverter
Using the hierarchical opinions to study the functional requirements of the elevator inverter, the elevator inverter software system adopts a four-layer hierarchical structure, that is, a layer can only be called by its upper layer, and the large module groups in each layer are parallel and identical. There is no coupling between the layer modules, which enables parallel expansion of software functions. The basic principle of designing a software module is that there is probably no coupling between the modules.
The elevator inverter software is real-time multi-tasking software. This design directly uses the priority interrupt mechanism to implement multi-task scheduling and processing for the hardware interrupt mechanism of the DSP. The advantage of this method is that it can accurately determine the execution time of each task, which is absolutely necessary for the real-time behavior of the task must be accurate to the microsecond level of the motor control software.
2. DSP hardware peripheral management level
Because the peripheral programming of the TMS320F2811 is very complicated, and keeping the compatibility of the software on the hardware platform is critical throughout the software life cycle, the primary task of the DSP hardware peripheral management layer design is to realize the hardware correlation of the split software module. The upper software module is independent of the hardware.
2.1 define the object structure
Through the object-oriented programming technology, each peripheral of the DSP is defined by the corresponding software structure. The same type of object defines only one structure, and then the object instance points to the specific peripheral. For example, there are multiple timers in the DSP, and the timer structure structCPUTIMER_REGS is defined to describe the control register of the timer. The structure is as follows: structCPUTIMER_REGS{
Uint32 TIM; / / timer count register
Uint32 PRD; //cycle register
Uint32 TCR; / / timer control register
Uint32 rsvd1;//Reserved
Uint32 TPR; / / timer predetermined value register low
Uint32 TPRH; / / timer predetermined value register high bit};
After defining the structure, define three variables of the structure, and then describe the three timers in the DSP.
2.2 control register bit field access function
Once the control register accesses a bit of the direct manipulation register, this program is poorly readable, especially when the number of registers is very large, it is easy to make mistakes, and it is not easy to check. The application of the C language joint structure directly manipulates the peripherals to be simple and easy to use.
2.3 unified peripheral and upper layer software data exchange method
Each peripheral is defined as a standard object. The upper layer software accesses the data members of these objects to obtain peripheral information or manipulate peripherals. The real-time interrupt task performs the update operation of the peripherals by calling the method function of the peripheral object. Set event response processing. After the ADC_DRV object obtains the conversion result of the ADC peripheral, the hardware dependency of the software function module is completely divided, and the standardization of the peripheral interface processing is realized, thereby greatly improving the portability of the software. Object's different method functions are executed in different processes, which is a significant difference between object-oriented programming and traditional waterfall structured programming.
3. Functional algorithm module layer
The functional algorithm module layer is divided into two quite a lot.
Part 1: Basic operations and signal processing function library. For the 32-bit TMS320F281x family of DSPs, TI offers a base virtual floating-point arithmetic library and a rich library of digital signal processing.
The second part: motor parameter identification and vector control module library, this part is the core algorithm of motor control. The key to development is the one-to-one correspondence between the control system signal flow diagram and the software module structure diagram. The use of a visual signal flow diagram is the basic method for representing complex control strategies.
Because the object-oriented development method is adopted, the specific control module can be realized by using the software object one by one for the above control algorithm, and the whole process of the control signal transmission is directly expressed by the object member variable.
Using object-oriented technology to make the control algorithm and software module one-to-one correspondence, has the following advantages: 1 control algorithm debugging is convenient. 2 control algorithm is convenient to expand. 3 greatly reduces the difficulty of software development, greatly reducing the probability of software errors.
4. User interface management level
From the outside, the complexity of the elevator inverter reflects the complicated user interface function.
There are three types according to the specific interface mode: digital manipulator, asynchronous serial communication interface, CAN bus function extension. According to the communication protocol to achieve hierarchical division, the user interface management level is largely divided into communication sub-layer and parameter transmission analysis layer. Asynchronous serial communication in the communication sublayer uses the Modbus protocol, which is a communication protocol commonly used in PLCs and inverters, and maintains consistency with industry standards.
The parameter transfer sublayer is used for parameter passing and modification for different software application layers. In the whole process of elevator control, the parameters of the relevant modules in each layer of the software can be modified. Sometimes, the modification of an application parameter by the user is probably related to many different layer modules in the software system. In order to ensure the consistency of parameter modification, a variety of parameter parsing transfer objects are set up to guarantee the correctness of parameter modification, and filter out various illegal manipulation and error parameter output. After calling different manipulation objects, you can implement specific interface handling functions.
5. Equipment operation logic management level
The elevator frequency converter is a hybrid system with both continuous control and complex sequential logic control. There must be an appropriate way to describe this complex system. In the whole process of elevator operation, there are many different working situations. It is not possible to cover all working conditions with a single control strategy, and there must be a perfect fault control strategy, which increases the complexity of software development. Avoiding the coupling of software modules due to the complexity of control is the key to the design of the logic management layer of the device. To this end, the concept of "virtual device" is introduced. The equipment here is a tool for expressing mixed objects, not for specific equipment in the industry.
The device management logic management layer is composed of different virtual device objects, mainly including inverter devices and programmable logic devices. The virtual device logic is specifically defined as follows:
5.1 mode logic
Describe how a virtual device can be transformed from one mode to another. A virtual device can define multiple mode groups. For example, the inverter device can define “operation mode groupâ€, “manipulation mode group†and so on.
5.2 State Logic
Describes the observable controllable virtual device state establishment condition because the current device state is determined by determining external commands, modes, faults, and given values.
5.3 Control Logic
Describe how the physical output value of the system is determined based on the value of the internal variable in the state.
5.4 Fault Logic
Describe the condition for determining the abnormality of the device, and once it is determined that there is a fault, interrupt the normal operation of the inverter and enter the fault handling mode. The fault logic is executed before the state logic is executed.
5.5 Alarm Logic
Describe the condition that the equipment is not a very serious abnormal situation. When there is an alarm, the normal operation of the inverter is not interrupted, but the application is notified.
From the above, the key to the programming of device logic is to treat each virtual device into five logical categories, realize the logic decoupling of the real-time control software of the hybrid object, and greatly reduce the difficulty of describing the complex real-time software, greatly improving the software. Reliability and scalability.
6 Conclusion
The designed elevator inverter software system has completed the laboratory development stage, and the operation test is being carried out at the factory. The prototype system has been put into actual test operation on site. In the whole process of software development and testing, I deeply realized the concept of introducing device logic and realized the macro-logic decoupling of software modules, which greatly improved the software's scalability. Since the development of complex real-time software is in accordance with the landmark development method advocated by Microsoft (first proposed), how to determine the software milestone in the whole process of software development depends mainly on the deliberation of the software structure, five categories of equipment logic. It provides practical basis for the specific scientific division of software milestones, and provides macro guidance for complex real-time software development. The concept of device logic also provides lessons for developing other complex real-time control software such as automotive engine control software.
Concerned about surprises
Label: Control Algorithm Software Module Control Register Parameter Modification Software System Structure
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