Abstract: This paper introduces a design and implementation scheme of intelligent power management system based on DSP. The system uses TI's TMS320LF2407A DSP as the control core, which is mainly composed of signal acquisition module, circuit conditioning module, DSP processing module, display module, keyboard module, DC-DC parallel power supply module and auxiliary power supply module. The design uses a BUCK step-down conversion circuit to realize DC/DC conversion, and designs and manufactures a high-efficiency two-way DC-DC converter in parallel. This parallel power supply system can convert 36 V DC voltage into 12V DC voltage, allowing current to reach 20 A works for a long time, and the current of the two parallel switching power supply modules can work according to the default shunt proportional shunt and control split proportional shunt modes. In addition, the system has been designed to resist interference, so that it has better anti-interference ability and ensures reliable system operation.
With the development of society and economy, the requirements for the quality and reliability of power supply are getting higher and higher. In many key applications, such as subway stations, hospitals and other power supplies, there must be no mistakes, otherwise it will bring serious, Even catastrophic consequences. Therefore, in many key places, there are backup power supplies or dual power supplies in parallel, such as UPS (Uninterruptible Power System). There are two main advantages of parallel power supply for two-way power supply: 1 expansion capacity to achieve high-power power system, 2 redundancy-tolerant function, that is, when a power module fails, the system can also provide load power to achieve power system Intermittent power supply.
However, the traditional parallel power supply mode of the two-way power supply has its own limitations, such as: 1 Poor flexibility, independent control of the working current can not be realized when the two-way power supply is working online; 2 can not effectively achieve energy saving, such as in the field, solar energy And wind energy resources are very rich, we can fully use this kind of green energy, supplemented by other power supply methods, and supply power for some key equipment working in the field. However, sometimes the power generated by solar energy and wind energy is not enough to maintain the normal operation of the equipment. If the battery is stored, the battery capacity is limited, and it is completely discarded. It is a pity to use the backup power directly. Based on this design and implementation of a new power supply system. The current of the parallel power supply can be operated according to the default split ratio split or control split ratio split mode . This avoids the above problems. The following describes the implementation principle and method of a dual-channel DC power supply.
1 Scheme design and demonstration
Design a safe, reliable, low-cost, 200 W 12 V DC parallel power supply system for field use. The system can meet the output voltage is basically unchanged when the load changes. The output current of the parallel power supply system can automatically distribute the current according to a certain ratio. The absolute value of the relative error of the output current of each module is not more than 5%. The specific requirements are as follows: 1 When the load changes, keep the output voltage unchanged, so that the load current Iout is 10 When the change between ~ 20 A, the output current of the two modules can be automatically allocated within the range of 5 ~ 15 A according to the specified ratio. The absolute value of the relative error of the output current of each module is not more than 2%. 2 Rated output power operation In the state, further improve the efficiency of the power supply system. 3 With load short circuit protection and automatic recovery function, the protection threshold current is 20A (Â± 0.2 A deviation), the overall system block diagram is shown in Figure 1.
1. 1 core processor solution selection
DSP has the advantages of fast computing speed, support for floating point operation, high measurement accuracy and strong anti-interference ability. The DSP device features an improved Harvard architecture with independent program and data space for simultaneous access to programs and data. Built-in high-speed hardware multipliers and enhanced multi-stage pipelines enable DSP devices to have high-speed data computing capabilities. The DSP (TM320LF2407A) comes with several 12-bit A/D conversions to achieve the accuracy required by the design. The DSP device also provides a highly specialized instruction set that improves the speed of the FFT Fast Fourier Transform and the filter. In addition, the DSP device features a high speed, synchronous serial port and standard asynchronous serial port. For the above reasons, we use a controller based on DSP (TM320LF2407A).
1. 2 main circuit DC-DC converter selection
The BUCK conversion circuit is adopted, the circuit is small in size, and the circuit is simpler than the single-ended flyback conversion circuit, and the efficiency is higher than that of the single-ended flyback conversion circuit, and there are many places where the loss can be increased and the transformer is not wounded. This problem has been chosen for problems such as loss and transformer noise.
1. 3 switch tube selection
The FET IR2125 is selected as the switching transistor. The conduction voltage of this tube is reduced and the on-resistance is only a few tens of milliohms. The loss is much smaller than that of the IGBT as the switching tube. Therefore, we choose this scheme.
1. 4 Control Strategy Selection
This design uses voltage and current double closed-loop PI regulation to control the output voltage, and its switching power supply can be shunted according to the preset ratio. We use a small resistor to collect the respective current signals and the overall output voltage signals of the two switching power supplies, and transmit them to the DSP through signal conditioning. The PI regulation current control mode is used for shunt regulation to achieve the effect of stabilizing the output voltage distribution output current.
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