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Abstract: The laptop battery lithium batteries due to its small size, energy density, single-voltage high self-discharge rate is low, and small internal resistance characteristics have been widely used in hybrid systems. The traditional Li-ion battery protection circuit and charging circuit to show the limitations of proposed based on DSP2407A Intelligent Management System (which can effectively protect the lithium power system), and PFC-based charging circuit (which can effectively charge the battery). The experimental results show the correctness of the design for the hybrid electric vehicle power systems using lithium laid a solid foundation.
Key words: hybrid lithium battery to protect power factor correction Intelligent Management System

With the continuous development of the automobile industry, the excessive energy consumption and serious pollution of the environment, forcing people to start thinking about the development of a new generation of energy-saving environmentally friendly vehicles. The development of hybrid electric vehicle (Hybrid Electric Vehicle) to solve the energy crisis and PCG-V505 environmental pollution, one of the best programs [1-3]. When the car is in low-pollution emission zone required in order to enhance the efficiency of the engine and fuel performance, the general shut down the engine, using high-performance batteries to provide energy-driven vehicle to normal driving. Therefore, the battery performance to a large extent determines the vehicle pollutant emissions and distance traveled.
For the current hybrid batteries power the system are: lead-acid batteries, nickel-metal hydride batteries and lithium-ion batteries [4-5].
Due to the low energy density of lead-acid batteries, charge-discharge and short life span, waste has been largely refractory and other shortcomings of the future out of a hybrid system. Ni-MH battery voltage is relatively low monomer, and only 1.2V, and have "memory effect" need for regular and large-scale discharge protection, which largely increased the power management system tasks; Secondly, the nickel-metal hydride PCG-Z505 batteries since the discharge rate, under normal circumstances to achieve 10% ~ 15%.
Compared with the other batteries, lithium-ion batteries in terms of volume, power has a larger advantage. High power density lithium-ion battery (800W/Kg), single-voltage high (average voltage of 3.6V), does not pollute the environment, there is no "memory effect", self-discharge rate is low (about 3% ~ 5%), is a kinds of dynamic ideal battery, in foreign countries has been widely used in hybrid power systems and aerospace vehicles in the. China, for high-power lithium batteries power the study is only in recent years and immature, this article is based on this reality is presented based on the lithium battery DSP2407A intelligent management system and the charging system based on the PFC.
1 60V/50A lithium battery Intelligent Management System
In reference to Li-ion battery protection circuit at home and abroad, based on the design of lithium-based battery DSP2407A intelligent management system, its schematic PA2487U diagram shown in Figure 1.

Li-ion battery pack composed of 14 monomers, charge the maximum limit voltage 60V, discharge lower limit voltage of 40.5V, the average discharge voltage of 50V, the average discharge current of 40A, temperature protection threshold for the 110 ° C, equilibrium points, 4.2 V, the maximum charge current of 50A.
This intelligent management system include: over-voltage protection, undervoltage protection, overcurrent protection, short circuit protection, temperature protection circuit and the maximum charge voltage based on the balance of protection circuits, based on minimum discharge voltage of the lower limit of self-locking circuit and display circuit such as electricity . In this system, the lithium battery power display circuit is very important: on the one hand due to lithium power supply for the sealing device, battery displays can prompt the user how much energy can be used; the other hand, consumption display circuit in the power supply when the low-voltage control not only to the DSP proposed protection device, but also through the CAN bus, charging PA3107U-1BRS a request made to the charging system.
2 60V/50A lithium battery charging system design
To be designed for Li-ion battery charging system performance are as follows:
(1) The limited flow constant voltage mode;
(2) The power factor PF> 0.97;
(3) AC input voltage range: 200V ~ 240V;
(4) Output Power Pout = 3kW;
(5) DC output float voltage Vout = 60V;
(6) Maximum charge current Imax = 50A.
Circuit consists of two composition of PFC pre-grade level, on the input power factor correction, while increasing the voltage to 380V; after the class using DC / DC programs, the voltage from 380V down to 60V, and use constant pressure limiting means charging, The basic schematic diagram shown in Figure 2.

2.1 PFC-level main circuit design
Active power factor correction circuits are based on the DC / DC topologies, in principle, there is Buck, Boost, flyback, forward and other structures. As the Boost circuit has a continuous inductor current, allowing a wide input voltage range, drive circuit PA3383U-1BRS and other features easily, it is widely used in power factor correction circuits. Boost topology designed in this paper based on the PFC main circuit schematic diagram shown in Figure 3.

2.2 DC / DC Main Circuit Design
DC / DC circuit main function is to PFC main circuit output voltage is converted to 380V DC 60V float voltage, the maximum output current is 50A. Commonly used in high-power DC / DC converter circuit full bridge and half-bridge circuit, but two kinds of circuits have the following disadvantages:
(1) bridge arm, the next switch in unforeseen interference will produce direct short circuit, damaged switch;
(2) a driving pulse is missing a switch, the transformer primary side may arise due to partial magnetic saturation phenomenon;
(3) two-way driving pulse width of the inconsistency will lead to transformer primary side bias magnetic saturation.
Forward transform circuit can avoid the occurrence of these phenomena, it is widely used in a number of demanding switching power supply. This design is PA3384U-1BRS based on twin-tube shock of the DC / DC circuit topology shown in Figure 4.
2.3 Control Circuit Design
2.3.1 PFC-level control circuit design
ML4824 for the PFC / PWM 2 composite control chip. PFC-level control circuit diagram in Figure 5. Diagram, the DC bus-wave signal via R2, R3, R4, C6, C7 constitute the second-order filter network becomes an input voltage feedforward signal, while bus-wave signal is input through resistor R5 into the signal voltage waveform sampling. PFC-level output voltage by R9, R17 voltage divider sent to the ML4824 error amplifier input, the signal and reference voltage comparison of a voltage error signal. R1 as the input current sampling resistor, sampled current signal sent to the ISENSE feet. R8, C11, C12, and R18, C16, C17 constituting the current error amplifier and voltage error amplifier compensation network.
2.3.2 DC / DC Control Circuit
ML4824 can be used as voltage mode PWM PA3285U-1BRS control chip, but also can be used as current-mode PWM control chip. This article will its application to current-mode PWM control chip controls DC / DC circuit, control schematic diagram shown in Figure 6. The figure, the output voltage is sampled by the resistor divider formed with the TL431 reference voltage for comparison, are the output voltage error signal sent by the opto-chip, after the formation of isolated voltage loop; while switching current through the R19 sample sent to the chip, the formation of current ring, and thus constitute a double-loop regulation. SQ-based circuit switch Q3 of the S foot.

DC / DC circuit current limiting constant pressure mode charge refers to the initial restriction in the charge a maximum charge current (Figure 6, by adjusting the resistance R19, R16 to achieve), as the battery voltage between positive and negative electrodes gradually increased, the charge current is also with the The decreases, until the battery is full, battery voltage between positive and negative output voltage is equal to the circuit, this time in a floating battery state of charge of a stage to be detected by DSP controller, current, when the charge is less than a certain PA3191U-1BRS value on the closure of loop.
2.4 Auxiliary Power Supply Design
For the entire system, the need for multiple DC power supply at different voltage levels, such as the DSP control board needs 5V, 15V two-way power supply, but also for the use of Hall-current sensor. Comprehensive cost and practicality of two considerations, the choice of TOPSWITCH flyback power, its principle as shown in Figure 7.
3 Experiment
Figure 8 for the PFC control circuit does not work when the input voltage and input current waveform, due to PFC circuit does not work, the input current distortion is very serious.

Figure 9 for the PFC control circuit after the input voltage and input current waveforms can be seen from the figure, the input current can be a good track the input voltage waveform, power factor reached 0.99.

Figure 10 for the charging circuit in the PA3166U-1BRS constant current phase of the current waveform. From the figure we can see that the output current ripple is very small.

(1) for the general defects in Li-ion battery protection circuit is proposed based on the lithium battery DSP2407A intelligent management system. Experiments show that may well protect the power system.
(2) for the general charging circuit current is a serious distortion of the issues raised in power factor correction PFC based on the charging circuit. Experiments proved to be effective in limiting constant pressure realization of lithium battery, the current ripple small.