CN206164154U - Balanced power supply system - Google Patents

Abstract

The utility model relates to a lithium battery supply balanced system technical field, in particular to balanced power supply system, including outer electric input end, lithium cell group, sampling module, charging and discharging circuit, master control system, auxiliary electrical power source, direct current steady voltage electric output / input, display module and button module, this system adoption buck topology steps down and charges, the boost topology is stepped up and is discharged, and with MSP430F5438A as main control chip, carry out the sampling of multiple spot current detection with AD analog -to -digital conversion to the system, make the adjustment according to feedback signal to the PWM signal, control current's flow, thereby carry out reliable closed -loop control, the realization is charged to the battery under the condition of external power abundance, with lithium cell power supply in coordination when external power source powering insufficient, play at the mesh of unstable power supply occasion for provide stable power with electrical apparatus.

Description

A balanced power supply system

【Technical field】

The utility model relates to the technical field of a lithium battery power balance system, in particular to a balanced power supply system.

【Background technique】

Due to the special working environment and nature of some special equipment, they cannot be connected to the power grid or are in an environment with unstable external power supply, such as DC uninterruptible power supply system, hybrid new energy vehicles and new energy power supply. For this type of equipment, lithium battery energy storage is mostly used to stabilize the working environment, but today's lithium battery management technology is mainly based on low power and has no balanced power supply function. Charging and discharging are carried out at the same time, and there are multiple charging and discharging that affect the battery. However, in the utility model, sampling points are set at the electrical power supply end, the external power supply end and the lithium battery end, and the synchronous rectification circuit balances the power output and effectively improves the efficiency. When the external power supply is sufficient, the system is in constant current charging mode and has a battery overcharge protection function. When the external power supply is insufficient, the circuit switches to a boost discharge mode to supplement electric energy with a lithium battery, so that the output voltage remains stable.

【Content of utility model】

In view of the above, it is necessary to provide a balanced power supply system that can effectively achieve the purpose of maintaining a stable output voltage.

In order to achieve the above object, the technical solution adopted in the utility model is:

A balanced power supply system, comprising an external power input terminal, a lithium battery pack, a sampling module, a charging and discharging circuit, a main control system, an auxiliary power supply, a DC stabilized voltage output/input terminal, a display module and a key module; the charging and discharging circuit includes : DC-DC step-down circuit and DC-DC step-up circuit; the main control system includes: a main control chip and a PWM drive circuit; the main control chip is connected with a PWM output circuit, a display module, a button module, a sampling module, The DC-DC step-down circuit of the charge-discharge circuit is connected to the auxiliary power supply; the PWN output circuit is connected to the DC voltage output/input end; the external power input end is connected to the DC-DC step-down circuit and the auxiliary circuit respectively, and the lithium The battery pack is respectively connected with the DC-DC step-down circuit and the DC-DC step-up circuit, and the sampling module is respectively connected with the output end of the DC-DC step-down circuit, the output end of the DC-DC step-up circuit and the output end of the auxiliary power supply.

Further, the main control chip is a single-chip microcomputer, the model of which is MSP430F5438A.

Further, the DC-DC step-down circuit includes: a power supply U ₁ field effect transistor S ₁ , a filter inductor L ₁ , a filter capacitor C ₁ , a freewheeling diode D ₁ and a resistor R ₁ ; one end of the power supply U ₁ is connected to _The field effect transistor S1 is connected, and the other end _of the field effect transistor S1 is connected to the output end _of the filter inductor L1 and the freewheeling diode D1 respectively, and the other end _of the filter inductor L1 is _respectively connected to the filter capacitor _C1 and the resistor _R1 , the input end _of the freewheeling diode D1 is connected in parallel with the other end of the filter capacitor _C1 and the other end _of the resistor R1 to the other end of the power supply.

Further, the DC-DC boost circuit includes: a lithium battery pack V ₁ , a field effect transistor S ₂ , an inductor L ₂ , a capacitor C ₂ , a diode D ₂ and a resistor R ₂ ; the positive side of the lithium battery pack V _{1 The} stage is connected with the inductor L2 _; the other end of the inductor L2 is connected with the input end of the diode D2 and one end of the field effect transistor S2 respectively, and the output end of the diode _D2 is connected with the _{capacitor C2} and one end of the resistor R2 _{respectively ; The} other end of the field effect transistor S2, the other end of the capacitor _C2 and the other end of the resistor _R2 are connected in parallel to the negative electrode _of the lithium battery pack V1.

Further, the PWM drive circuit includes connector J1, connector _J2 , resistor _R3 , resistor _R4 , resistor _R5 , resistor _R6 , transistor _Q1 , transistor _Q2 , transistor _Q3 and _{diode D3} , the connector J ₁ is connected in series with the resistor R ₃ and the base 2 of the transistor Q ₁ in sequence; the collector 3 of the transistor Q ₁ is connected with the resistor R ₄ and the base 2 of the transistor Q ₂ and the transistor Q ₃ respectively; the transistor Q The emitter ₁ of ₁ is connected to the emitter ₁ of the transistor _Q3 and the connector J2 in parallel to the ground _; the other end of the resistor R4 is connected to the power supply and the resistor _R5 respectively, and the other end of the resistor R5 is connected to the collector of the transistor _Q2 3 connected; the emitter 1 of the triode _Q2 is respectively connected with the collector ₁ of the triode _Q3 and the resistor R6 _; the diode _D3 is connected in parallel at both ends of the resistor R6.

Further, the display module is a NOKIA 5110 liquid crystal display.

The utility model has the following beneficial effects:

1. The utility model aims at the defect of repeated charging and discharging of the existing lithium battery management equipment, and adopts a balanced output mode and a high-efficiency scheme of synchronous rectification. When the external power supply is unstable, the lithium battery power supply mode is started to reduce the charging and discharging of the lithium battery The number of times effectively prolongs the life of the lithium battery, thereby achieving the purpose of stabilizing the voltage and reducing maintenance costs; the control system of the utility model uses MSP430F5438A as the main control device, which is a powerful 16-bit ultra-low power consumption feature produced by TI. The advantage of low power consumption is conducive to the requirement of high system efficiency, and its ADC12 is a high-precision 12-bit A/D conversion module, which has the characteristics of high speed and general purpose. Using MSP430 can complete the closed-loop adjustment of voltage feedback, voltage Current display, charging overvoltage protection and other functions.

【Description of drawings】

Fig. 1 is the control flow schematic diagram of the utility model embodiment;

Fig. 2 is the circuit diagram of the DC-DC step-down circuit of the utility model embodiment;

Fig. 3 is the circuit diagram of the DC-DC step-up circuit of the utility model embodiment;

Fig. 4 is a PWM driving circuit diagram of the embodiment of the present invention.

Description of drawings: U ₁ , power supply; S ₁ , FET; L ₁ , filter inductor; C ₁ , filter capacitor; D ₁ , freewheeling diode; R ₁ , resistor; V ₁ , lithium battery pack; S ₂ , Field effect tube; L ₂ , inductor; C ₂ , capacitor; D ₂ , diode; R ₂ , resistor; J ₁ , J ₂ are connectors; R ₃ , R ₄ , R ₅ , R ₆ are resistors; Q ₁ , Q ₂ and Q ₃ are triodes; D ₃ , diodes; 1, emitters of the triodes; 2, bases of the triodes; 3, collectors of the triodes.

【detailed description】

In order to make the above purpose, features and advantages of the present utility model more obvious and understandable, the specific implementation of the present utility model will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a full understanding of the present invention. However, the utility model can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific implementation disclosed below .

Example 1:

As shown in Figure 1, the balanced power supply system of the present invention includes an external power input terminal, a lithium battery pack, a sampling module, a charging and discharging circuit, a main control system, an auxiliary power supply, a DC stabilized voltage output/input terminal, a display module and a key module The charging and discharging circuit includes: a DC-DC step-down circuit and a DC-DC boosting circuit; the main control system includes: a main control chip and a PWM drive circuit; the main control chip is connected with a PWM output circuit and a display module respectively , the button module, the sampling module, the DC-DC step-down circuit of the charging and discharging circuit are connected with the auxiliary power supply; the PWN output circuit is connected with the DC voltage output/input end; the external power input end is respectively connected with the DC-DC step-down circuit and the The auxiliary circuit is connected, the lithium battery pack is connected with the DC-DC step-down circuit and the DC-DC step-up circuit respectively, and the sampling module is connected with the output end of the DC-DC step-down circuit, the output end of the DC-DC step-up circuit and the Auxiliary power output connected.

In order to meet the advantages of low power consumption of the system and the requirement of high system efficiency, the main control chip of the utility model is a single-chip microcomputer, and the model is MSP430F5438A.

In order to further reduce the use of components and parts to achieve a better step-down effect, the system step-down module of the present invention is implemented by a Buck converter. The circuit diagram is shown in Figure 2, including: power supply U ₁ FET S ₁ , filter inductor L ₁ , filter capacitor C ₁ , freewheeling diode D ₁ and resistor R ₁ ; one end of the power supply U ₁ is connected to the field effect transistor S ₁ , and the other end of the field effect transistor S ₁ is respectively connected to the filter inductor L ₁ It is connected to the output end _of the freewheeling diode D1, and the other end _of the filter inductor L1 is respectively connected to the filter capacitor _C1 and the resistor R1, and the input end _of the freewheeling diode D1 is connected to the other end _of the filter capacitor _C1 and the resistor _R1 The other end is connected in parallel to the other end of the power supply.

The working process of the above step _- down circuit is: the PWM square wave signal drives the field effect transistor S1 to turn _on , and the current in the filter inductor L1 gradually increases. After the conduction is completed, the field effect transistor _S1 enters the closed period. _The current of the filter inductor L1 reaches the maximum value ILmax, and the current in the inductor cannot change abruptly, so the current continues to flow, and the freewheeling diode D1 acts as _a freewheeling element during the cut-off period. When the cut-off time is over, the current in the inductor reaches the minimum value ILmin, and then restarts a new cycle, thereby obtaining a stable output voltage. By adjusting the turn-on and turn-off time _of the field effect transistor S1, the size of the output voltage is changed. The output voltage increases with the conduction time _of FET S1 increasing.

In order to further reduce the use of components to achieve a better boosting effect, the system boosting module of the utility model is realized by a Boost converter. The circuit diagram is shown in Figure 2, including: lithium battery pack V ₁ , field effect Tube S ₂ , inductor L ₂ , capacitor C ₂ , diode D ₂ and resistor R ₂ ; the positive stage of the lithium battery pack V ₁ is connected to the inductor L ₂ ; the other end of the inductor L ₂ is respectively connected to the input end of the diode D ₂ It is connected to one end of the field effect transistor S2, and the output end of the diode D2 is connected to the capacitor _C2 and one end of the resistor R2 _{respectively ;} the other end of the field effect transistor _S2 , the other end of the capacitor _{C2 and} the other end of the resistor _R2 One end is connected in parallel to the negative electrode of the lithium battery pack V ₁

_The working process of the above boost circuit is: when the field effect transistor S2 is turned _on , the input current flows through the inductor L2 and the field effect transistor S2, the voltage drop at _both ends of the field effect transistor S2 is zero, and a voltage is generated at _both ends of the inductor _L2 . When the voltage drops, the current of the inductor L ₂ begins to increase linearly to store energy, and the diode D ₂ is in the off state at this time. When the field effect transistor S2 is cut off, because the current of the inductor _L2 has _continuity , the magnetic field generated by the coil of the inductor L2 will change the polarity of the _two ends of the coil to keep the inductor current constant, so the inductor voltage appears negative during this period. Voltage, which is converted from the magnetic energy of the coil, is connected in series with the lithium battery pack V1, and supplies power to the rear stage of the circuit with _a voltage higher _than the lithium battery pack V1, so that the circuit produces a boost effect. At this time, the inductor L2 _releases energy to the subsequent stage, and the inductor current decreases continuously. After the inductor current reaches the output terminal through the diode _D2 , part of it provides energy for the output, and part of it charges the capacitor. At this point, the boost converter completes a working cycle , and then the converter repeats the above-mentioned process to work in a steady state.

Since the driving signal generated by the MCU is not enough to drive the FET, the PWM signal needs to be amplified. The PWM driving circuit is shown in Figure 4: Connector J ₁ , Connector J ₂ , Resistor R ₃ , Resistor R ₄ , Resistor R ₅ , resistor R ₆ , transistor Q ₁ , transistor Q ₂ , transistor Q ₃ and diode D ₃ , the connector J ₁ is connected in series with the resistor R ₃ and the base 2 of the transistor Q ₁ in sequence; the collector of the transistor Q ₁ 3 are respectively connected to the resistor R4 and the base ₂ of the transistor _Q2 and transistor _Q3 ; the emitter ₁ of the transistor Q1 is connected in parallel with the emitter ₁ of the transistor _Q3 and the connector J2 _; the other end of the resistor R4 Connect to the power supply and resistor R5 respectively, and the other end of resistor R5 is connected to collector ₃ of transistor _{Q2 ;} emitter ₁ of transistor Q2 is connected to collector ₁ of transistor _Q3 and resistor R6 respectively; diode _D3 connected in parallel across the resistor _R6 .

In order to improve the cost performance, the display module of the utility model selects the liquid crystal display of model NOKIA 5110 for use.

The programming idea of this system is:.

1. Set the output voltage according to the external power consumption, as follows:

(1) The keyboard realizes the function: set the boost output voltage and current and step the current value as required.

(2) Display part: display voltage value, setting current value and output current value.

2. Program Design Ideas

(1) The current voltage value is collected through A/D data, and the voltage value and current value are displayed on the NOKIA 5110 liquid crystal.

(2) Determine the size of the current required by the user by detecting the input of the keyboard.

(3) The current voltage value is collected by the single-chip microcomputer, converted into a PWM control number, and the PWM control number corresponding to the set current value is calculated to control the output current and voltage.

(4) When the battery pack exceeds the threshold voltage of overshoot protection, charging is stopped to protect the circuit.

(5) The single-chip microcomputer controls the NOKIA 5110 liquid crystal display voltage value and current value. .

The above-mentioned embodiment only expresses one implementation mode of the present utility model, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the scope of the present utility model. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the present utility model should be based on the appended claims.

Claims (6)

1. a kind of balanced feeding system, it is characterised in that including outer electrical input, lithium battery group, sampling module, charge-discharge circuit, Master control system, accessory power supply, DC voltage-stabilizing electricity output/input, display module and key-press module；The charge-discharge circuit bag Include：DC-DC reduction voltage circuits and DC-DC booster circuit；The master control system includes：Master control chip and PWM drive circuit；Institute State Master control chip to be depressured with the DC-DC of PWM output circuits, display module, key-press module, sampling module, charge-discharge circuit respectively Circuit is connected with accessory power supply；The PWN output circuits are connected with direct voltage output/input；The outer electrical input point It is not connected with DC-DC reduction voltage circuits and auxiliary circuit, the lithium battery group rises piezoelectricity with DC-DC reduction voltage circuits and DC-DC respectively Road is connected, and the sampling module is defeated with DC-DC reduction voltage circuit output ends, DC-DC booster circuit output end and accessory power supply respectively Go out end to be connected.

2. a kind of balanced feeding system according to claim 1, it is characterised in that the Master control chip is single-chip microcomputer, Model MSP430F5438A.

3. a kind of balanced feeding system according to claim 1, it is characterised in that the DC-DC reduction voltage circuits include：Electricity Source U₁FET S₁, filter inductance L₁, filter capacitor C₁, sustained diode₁With resistance R₁；The power supply U₁One end and field Effect pipe S₁It is connected, FET S₁The other end respectively with filter inductance L₁And sustained diode₁Output end be connected, filtering Inductance L₁The other end respectively with filter capacitor C₁With resistance R₁It is connected, sustained diode₁Input and filter capacitor C₁It is another End, resistance R₁The in parallel other end for accessing power supply of the other end.

4. a kind of balanced feeding system according to claim 1, it is characterised in that the DC-DC booster circuit includes：Lithium Battery pack V₁, FET S₂, inductance L₂, electric capacity C₂, diode D₂With resistance R₂；Lithium battery group V₁Positive level and inductance L₂ It is connected；Inductance L₂The other end respectively with diode D₂Input and FET S₂One end be connected, diode D₂Output End respectively with electric capacity C₂With resistance R₂One end be connected；FET S₂The other end, electric capacity C₂The other end and resistance R₂It is another One end is in parallel to access lithium battery group V₁Negative pole.

5. a kind of balanced feeding system according to claim 1, it is characterised in that the PWM drive circuit includes：Connection Device J₁, connector J₂, resistance R₃, resistance R₄, resistance R₅, resistance R₆, triode Q₁, triode Q₂, triode Q₃With diode D₃, The connector J₁With resistance R₃, triode Q₁Base stage 2 be sequentially connected in series；Triode Q₁Colelctor electrode 3 respectively with resistance R₄With three Pole pipe Q₂, triode Q₃Base stage 2 be connected；Triode Q₁Emitter stage 1 respectively with triode Q₃Emitter stage 1 and connector J₂And Connection ground；Resistance R₄The other end respectively with power supply and resistance R₅It is connected, resistance R₅The other end and triode Q₂Colelctor electrode 3 It is connected；Triode Q₂Emitter stage 1 respectively with triode Q₃Colelctor electrode 1 and resistance R₆It is connected；Diode D₃It is connected in parallel on resistance R₆ Two ends.

6. a kind of balanced feeding system according to claim 1, it is characterised in that the display module selects model The liquid crystal display of NOKIA5110.