Novel storage battery charging and discharging device

Abstract

The invention relates to a novel storage battery charging and discharging device which comprises a power circuit and a control circuit. The power circuit comprises a charging circuit and a discharging circuit; the control circuit comprises a main controller and a signal acquisition circuit; the signal acquisition circuit is used for acquiring voltage and current values of the storage battery and sending the voltage and current values to the main controller, and the main controller performs charging and discharging control on the storage battery according to the voltage and current states and the state duration of the storage battery; the discharging circuit comprises a step-down circuit, a step-up circuit and a discharging load circuit which are connected in sequence; the discharge load circuit comprises multiple paths of parallel circuits, each branch comprises a current regulation switch tube and a PTC resistor, and the step-down circuit and the step-up circuit respectively comprise a voltage regulation switch tube; the main controller sends PWM (Pulse Width Modulation) pulse to the voltage regulation switch tube, so that the output voltage of the step-down circuit and the step-up circuit reaches a set threshold value; and the main controller sends a wide PWM pulse to the current regulation switch tube, so that the current value of the discharge circuit reaches a set threshold value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery charging and discharging, and particularly relates to a novel battery charging and discharging device. BACKGROUND

[0002] With the development of new energy batteries, the battery is one of the main power sources of various new energy vehicles and related power supply systems. How to ensure the performance of the battery in the standby state is an important issue for new energy batteries. In the state of charge preservation, due to the influence of factors such as undercharging, self-discharge and environmental temperature change, the performance of lead-acid batteries will gradually decrease, and even cannot be used normally. The main reason for the failure of the battery is that the lead sulfate of the battery plate gradually loses activity under the action of the above factors, the crystal becomes coarse and hard, and the "sulfuration" phenomenon occurs, thereby causing the battery capacity to decrease or be completely scrapped.

[0003] Due to over-discharge or long-term storage after discharging, the "sulfuration" phenomenon occurs, and the battery must be treated to prevent or eliminate sulfuration. Any crystal has a resonant frequency after the molecular structure is determined, and the frequency is related to the size of the crystal. The larger the size of the crystal, the lower the resonant frequency. If a front steep positive pulse is applied to the battery, it can be known from frequency spectrum analysis using Fourier series that the pulse contains rich harmonic components, and the amplitude of the low-frequency part is large and the amplitude of the high-frequency part is small. In this way, the large lead sulfate crystal of the negative plate of the battery obtains a large amount of energy, and the small lead sulfate crystal obtains a small amount of energy. During the positive pulse period, the amplitude of the resonance of the large lead sulfate crystal is large, and it is easier to be dissolved than the small lead sulfate crystal. Properly controlling the pulse current value, charging the positive plate with a small current density, basically will not cause damage to the positive plate. For sealed batteries, the oxygen generated by the charging voltage of the positive plate in an instant can also be absorbed on the negative plate through oxygen circulation, so the battery will not lose water.

[0004] Although the charging equipment is currently equipped, the sealed battery is regularly maintained and charged, but the traditional regular charging maintenance is time-consuming and laborious, the means is backward, the degree of automation is low, and the maintenance effect is poor. Therefore, it is imperative to use intelligent control technology to automatically enter the charging or maintenance state according to the charge condition of the sealed battery. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a novel battery charging and discharging device to solve the problems of low efficiency and poor maintenance effect of the existing battery maintenance and charging.

[0006] The embodiment of the present application provides a novel battery charging and discharging device, the device comprises a power circuit and a control circuit; the power circuit comprises a charging circuit and a discharging circuit; the control circuit comprises a main controller and a signal acquisition circuit; the signal acquisition circuit is used for acquiring the voltage and current value of the battery and sending the voltage and current value to the main controller; the main controller controls the charging and discharging of the battery according to the voltage and current state and state duration of the battery.

[0007] The discharging circuit comprises a step-by-step connected voltage reduction circuit, voltage increase circuit and discharging load circuit; the discharging load circuit comprises a plurality of parallel branches, each branch comprises a current regulating switch tube and a PTC resistor in series; the voltage reduction circuit and the voltage increase circuit each comprise a voltage regulating switch tube; the main controller sends a PWM pulse to the voltage regulating switch tube, so that the output voltage of the voltage reduction circuit and the voltage increase circuit reaches a set threshold range; the main controller sends a wide PWM pulse to the current regulating switch tube, so that the current value of the discharging circuit reaches a set threshold.

[0008] Further, in the voltage reduction circuit and the voltage increase circuit, the duty cycle range of the PWM pulse sent by the main controller to the voltage regulating switch tube is 0.3-0.8.

[0009] Further, the main controller controls the charging and discharging of the battery according to the voltage and current state and state duration of the battery, comprising:

[0010] The main controller sets different currents according to the current voltage value of the battery obtained by the signal acquisition circuit sampling to perform trial charging, and performs normal charging on the battery when the trial charging is normal; during the normal charging process, the main controller obtains the current charging current of the battery by sampling the signal acquisition circuit, and judges the current charging current; first, it is judged whether the current charging current is below 0.1C, if yes, the pulse charging and discharging stage is entered; otherwise, it is judged whether the current charging current is greater than 0.4C, if yes, the main controller sets the current charging current to 0.3C, if less than or equal to 0.4C, the main controller sets the current charging current to 0.2C or 0.1C; when the first charging end condition is reached, the charging is stopped.

[0011] Further, the first charging end condition comprises: the main controller judges the voltage value obtained by the signal acquisition circuit sampling to determine that the battery voltage exceeds 1.33 times of the nominal voltage, or the difference between the current battery voltage and the maximum battery voltage is less than or equal to 0.6V, or the current decreases to 0.06C; the duration of any of the above states is greater than or equal to 4s.

[0012] Further, the pulse charging and discharging stage includes a pulse charging and discharging test stage and a pulse charging stage and a pulse discharging stage; in the pulse charging and discharging test stage, the main controller controls the battery to perform pulse charging test, if the battery pulse charging test is normal, first perform the conventional discharge, the discharge duration is 1 second, if the 1 second conventional discharge is normal, convert to the pulse charging stage, until the second charging end condition is reached, the pulse charging is stopped; in the pulse charging and discharging test stage, if the battery pulse charging test is not normal, first perform the conventional charging, the charging duration is 1 second, if the 1 second conventional charging is normal, convert to the pulse discharging stage, until the second discharging end condition is reached, the pulse discharging is stopped.

[0013] Further, the pulse charging stage includes: the main controller sets different currents for pulse charging according to the current battery voltage value sampled by the signal acquisition circuit, when the sampled voltage value is less than 1.01 times of the nominal voltage, the main controller sets the charging current to 1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the charging current to 0.5C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the charging current to 0.2C; in the pulse charging stage, the main controller sets the battery charging voltage to 1.33 times of the nominal voltage.

[0014] Further, the pulse discharging stage includes: the main controller sets different currents for pulse discharging according to the current battery voltage value sampled by the signal acquisition circuit, when the sampled voltage value is less than 1.01 times of the nominal voltage, the main controller sets the discharging current to 0.1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the discharging current to 0.2C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the discharging current to 0.5C; in the pulse discharging stage, the main controller sets the discharging voltage to 0.7 times of the nominal voltage.

[0015] Further, the second charging end condition includes: the time when the pulse charging voltage is greater than 1.33 times of the nominal voltage is more than 2s, or the time when the pulse charging current decreases to less than or equal to 0.06C is more than 2s, or the total length of the time when the voltage value is in the range of 1.01-1.05 times of the nominal voltage in the battery conventional charging and pulse charging stage is more than 175min, or the length of the pulse charging stage is more than 85min, or the total length of the time when the voltage value is less than 1.01 times of the nominal voltage in the battery conventional charging and pulse charging stage is more than 420min.

[0016] Further, the second discharge end condition comprises: the total length of time when the voltage value of the battery regular charging and pulse discharge stage is in the range of 1.01-1.05 times of the nominal voltage exceeds 175 min, or the total length of time when the voltage value of the regular charging and pulse discharge stage is less than 1.01 times of the nominal voltage exceeds 420 min, or the total length of the pulse discharge stage exceeds 85 min, or the length of time when the current of the pulse discharge reduces to less than or equal to 0.06C exceeds 2s.

[0017] Further, the charging circuit comprises an interleaved parallel Boost PFC circuit, an LLC half-bridge resonant circuit and a synchronous rectification circuit connected in sequence; the interleaved parallel Boost PFC circuit and the LLC half-bridge resonant circuit each comprise a plurality of switching tubes; when the difference between the charging voltage or current set by the main controller and the voltage value or current value sampled by the signal acquisition circuit is greater than a set voltage threshold or current threshold, the main controller preferentially adjusts the switching tubes of the interleaved parallel Boost PFC circuit, otherwise when the difference between the charging voltage or current set by the main controller and the voltage value or current value sampled by the signal acquisition circuit is less than or equal to the set voltage threshold or current threshold, the main controller preferentially adjusts the duty cycle of the switching tubes of the LLC half-bridge resonant circuit.

[0018] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0019] 1、The novel battery charging and discharging device sets a self-adaptive charging and discharging strategy according to the charge condition of the battery, the signal acquisition circuit samples to detect the current battery voltage and current in real time, the main controller changes the pulse current at any time according to the detected current battery voltage and current, maintains dynamic balance with the self-discharge of the battery, adopts the first and second charging end conditions, and can prevent overcharging of the battery; the battery is maintained in a combination mode of regular charging and pulse charging and discharging, so that the maintained battery will neither be overcharged nor lose water.

[0020] 2、The PTC resistance value of the discharge circuit can be set according to actual needs, different branch duty cycles can be switched by the MOSFET switch to coarsely adjust the output load power, and the switching duty cycles of the step-down circuit and the step-up circuit connected in sequence in the discharge circuit are used to finely adjust the load power; the switching duty cycles of the step-down circuit and the step-up circuit are both set in the range of 0.3-0.8, so that the harmonics of the MOS switch tube are suppressed, and the power supply efficiency is relatively high.

[0021] 3、The charging circuit adopts an LLC half-bridge resonant circuit design, the LLC half-bridge resonant circuit power supply realizes zero-voltage turn-on (ZVS) of the two main MOS switches on the primary side and zero-current turn-off (ZCS) of the rectifier diode on the secondary side, and through the soft switching technology, the switching loss of the power supply can be reduced, and the efficiency and power density of the power converter can be improved.

[0022] The above technical solutions can be combined with each other in the present application to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent description, and some advantages will become apparent from the description, or will be understood by those skilled in the art through implementation of the present application. The purposes and other advantages of the present application can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0024] Figure 1 Flow chart of charging and discharging of a new type of battery charging and discharging device;

[0025] Figure 2 Structure block diagram of a new type of battery charging and discharging device;

[0026] Figure 3 Structure block diagram of the charging part of a new type of battery charging and discharging device;

[0027] Figure 4 Principle diagram of the discharging circuit of a new type of battery charging and discharging device;

[0028] Figure 5 Function block diagram of the DSP controller of a new type of battery charging and discharging device;

[0029] Figure 6 Interleaved parallel Boost PFC circuit in the charging circuit of a new type of battery charging and discharging device;

[0030] Figure 7 LLC half-bridge resonant circuit in the charging circuit of a new type of battery charging and discharging device. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application will be specifically described below in combination with the drawings, wherein the drawings constitute a part of this application, and are used to explain the principles of the embodiments of the present application, and are not used to limit the scope of the present application.

[0032] One specific embodiment of the present application discloses a new type of battery charging and discharging device, and the structure block diagram of the charging and discharging device is as follows: Figure 2As shown. The device includes power circuit and control circuit; power circuit includes charging circuit, discharging circuit; control circuit includes main controller, signal acquisition circuit; signal acquisition circuit is used for collecting voltage, current value of storage battery and sending to main controller, main controller controls charging and discharging of storage battery according to voltage, current state and state duration of storage battery,

[0033] Wherein, the discharging circuit includes a voltage reducing circuit, a voltage increasing circuit and a discharging load circuit connected in sequence; the discharging load circuit includes a plurality of parallel branches, each branch includes a current regulating switch tube and a PTC resistor connected in series; the voltage reducing circuit and the voltage increasing circuit each include a voltage regulating switch tube; the main controller sends PWM pulses to the voltage regulating switch tube, so that the output voltage of the voltage reducing circuit and the voltage increasing circuit reaches the set threshold range; the main controller sends wide PWM pulses to the current regulating switch tube, so that the current value of the discharging circuit reaches the set threshold.

[0034] Specifically, the charging circuit mainly consists of interleaved parallel Boost PFC circuit, LLC half-bridge resonant circuit and synchronous rectification circuit.

[0035] Exemplarily, the structure block diagram of the charging part of the charging and discharging device is as shown in Figure 3 The main controller includes a DSP controller, a PFC controller and an LLC controller. The DSP controller determines to use the PFC controller or the LLC controller to adjust the duty cycle of the switch tube of the corresponding interleaved parallel Boost PFC circuit and LLC half-bridge resonant circuit according to the difference between the set voltage and current value and the voltage value or current value sampled by the signal acquisition circuit.

[0036] The PFC controller and the LLC controller respectively receive the sampling signals of the output voltage and current of the interleaved parallel Boost PFC circuit and LLC half-bridge resonant circuit from the signal acquisition circuit, and can compare with the respective preset values to realize the adjustment of the control switch duty cycle.

[0037] The charging circuit includes interleaved parallel Boost PFC circuit, LLC half-bridge resonant circuit and synchronous rectification circuit connected in sequence; the interleaved parallel Boost PFC circuit and LLC half-bridge resonant circuit each include a plurality of switch tubes; when the difference between the set charging voltage or current of the main controller and the voltage value or current value sampled by the signal acquisition circuit is greater than the set voltage threshold or current threshold, the main controller preferentially adjusts the switch tube of the interleaved parallel Boost PFC circuit, otherwise when the difference between the set charging voltage or current of the main controller and the voltage value or current value sampled by the signal acquisition circuit is less than or equal to the set voltage threshold or current threshold, the main controller preferentially adjusts the duty cycle of the switch tube of the LLC half-bridge resonant circuit.

[0038] Specifically, asFigure 6 As shown, the front stage of the interleaved parallel Boost PFC circuit is a single-phase bridge uncontrolled rectifier circuit composed of four diodes D1-D4, and the rear stage consists of two Boost circuits connected in parallel (the Boost circuit is the power section). The circuit schematic is shown below. Figure 6 As shown; this circuit first rectifies single-phase AC into DC, and then controls the charging and discharging of the PFC inductor by controlling the on / off state of VD1 and VD2. Figure 6 When MOSFET VD1 is turned on, inductor L1 charges and stores energy through VD1. When VD1 is turned off, inductor L1 discharges through D5. Simultaneously, another MOSFET, VD2, is turned on, and inductor L2 charges and stores energy through VD2. When VD2 is turned off, inductor L2 discharges through D6. The two MOSFETs alternately conduct, and their outputs are connected in parallel. This circuit is an interleaved parallel PFC circuit. The interleaved parallel circuit forms a new converter by controlling the phases of the two power sections in parallel, allowing each power section to handle half of the total power, reducing the current load on the switching devices. Because the two currents are staggered by a certain phase, the superposition of currents reduces input and output current ripple and makes EMI filtering easier. Simultaneously, the interleaved parallel Boost PFC circuit controls the switching transistors of the Boost circuit in an interleaved manner, causing them to operate at different stages. This results in a more even distribution of current at the power input and output, significantly reducing power loss caused by current fluctuations and improving overall energy efficiency.

[0039] like Figure 7 As shown, the LLC half-bridge resonant circuit is a power conversion circuit used for DC / AC conversion, such as... Figure 7 As shown, voltage regulation is mainly achieved by the main controller outputting PWM control signals to the two switching transistors VD1 and VD2. The LLC controller receives the current output voltage sampling results of the LLC half-bridge resonant circuit in real time and controls the resonant frequency to keep the voltage across the transformer stable, thereby achieving voltage stabilization. Its working principle is as follows: When MOSFETs VD1 and VD2 are off, the input DC voltage is applied to the resonant capacitor, and the resonant circuit begins to charge; when MOSFET VD1 is on and VD2 is off, the resonant capacitor C1 begins to discharge, and the resonant inductor begins to charge. The output voltage is applied to the primary side of transformer T1. When C1 = C2, the voltage is approximately half of the power supply voltage, and energy is transferred from the primary side to the secondary side; when MOSFET VD1 is off and VD2 is on, the inductor L1 and capacitor C2 begin to discharge. The output voltage is applied to the primary side of transformer T1. When C1 = C2, the voltage is approximately half of the power supply voltage, and energy is transferred from the primary side to the secondary side. The magnitude and frequency of the output voltage between L2' and N2' can be adjusted by regulating the switching time and duty cycle of the MOSFET.

[0040] The resonant capacitances C1 and C2 can be equivalent to a capacitor with a capacitance of (C1+C2), and the capacitor and two inductances L1 and Lm in series with the capacitor and the magnetizing inductance Lm of the primary side of the transformer T1 together form a resonance point; under the heavy load condition, Lm will be considered as a complete short circuit under the action of the reflected load, and under the light load condition, Lm still remains in series with the resonant inductance L1. Therefore, the resonant frequency is determined by the load condition. L1 and (C1+C2) determine the resonant frequency f1, (C1+C2) and two inductances L1 and Lm determine the second resonant frequency f2, and as the load increases, the resonant frequency also increases. The resonant frequency varies between the maximum value and the minimum value determined by the transformer and the resonant capacitance (C1+C2). By changing the frequency, the voltage of 1 / s(C1+C2)+sLr changes accordingly, where Lr is the total inductance formed by the inductance L1 and the magnetizing inductance Lm of the primary side of the transformer; finally, the Lm voltage remains unchanged, that is, the output voltage remains unchanged.

[0041] As shown in Figure 2 The charging and discharging device further comprises an input filter circuit, a cooling fan and a heating module.

[0042] The external AC power input is filtered by the input filter circuit to prevent external signal interference; after filtering, the soft start part is used to prevent the charging and discharging device from causing impact on the external AC power grid when starting. Then, the Boost PFC circuit is used for step-up rectification to DC. The DC after step-up is converted into high-frequency AC by the LLC half-bridge resonant circuit, and then rectified into DC by the synchronous rectification circuit, and finally filtered into smooth DC by the capacitor.

[0043] The cooling fan is used for cooling the charging circuit and the discharging circuit, and is started when the environmental temperature exceeds 45℃; the heating module is used for heating the battery, and is started when the environmental temperature is lower than -10℃.

[0044] Figure 5 The function block diagram of the DSP controller is shown in the figure, and the main functions are as follows:

[0045] The charging and discharging circuit, the heating module and the cooling fan are controlled through the I / O interface respectively;

[0046] Through connection with the signal acquisition circuit, the voltage, current and temperature of the battery are detected;

[0047] The display communicates with the received data to display the working state of the device, the battery voltage, current, temperature and other related information;

[0048] The software is upgraded through the USB interface;

[0049] The network module controlled by the UART realizes network communication with the upper computer;

[0050] The RS485 communication function is realized by driving the special RS485 chip through the UART, and the communication with the host computer is realized; meanwhile, the host computer can also send various maintenance instructions to the main controller through the RS485 interface, and receive and analyze the temperature, voltage, current and various fault information of the storage battery.

[0051] In the buck circuit and the boost circuit, the duty cycle range of the PWM pulse sent by the main controller to the voltage regulating switch tube is 0.3-0.8.

[0052] Specifically, the load circuit in the discharging circuit realizes the adjustment of different discharging currents through different PTC resistance value matching and boost-buck circuit control. The duty cycle range of the PWM pulse sent by the main controller to the voltage regulating switch tube is 0.3-0.8, which is beneficial to suppress the harmonic of the MOS tube, and the power supply efficiency is relatively high.

[0053] The discharging circuit schematic diagram is as shown in Figure 4 BAT+ and BAT- are connected to the positive and negative poles of the storage battery respectively, and are connected to the BUCK circuit after being filtered by L1 and C1. In an embodiment of the present application, the BUCK circuit is composed of MOS tube VD1, diode D1, inductor L2 and capacitor C2. When VD1 is turned on, the battery supplies power to the subsequent load through VD1 and L2, and C2 filter capacitor makes the output voltage smooth; when VD1 is turned off, L2 inductor supplies power to the subsequent load through D1, and C2 filter capacitor makes the output voltage smooth. The main controller can adjust the output voltage U o1 and the current size by adjusting the width of the PWM pulse acting on VD1 to control the conduction time of VD1. o1 After being filtered by L3 and C3, it is connected to the BOOST circuit. The BOOST circuit is composed of MOS tube VD2, diode D2, inductor L4 and capacitor C4. When VD2 is turned off, diode D2 is turned on, U o1 and the voltage of inductor L4 are added to the load at the same time, and C4 filter capacitor makes the output voltage smooth. The adjustment principle is as follows:

[0054] The output voltage of the BUCK circuit after voltage reduction is U o1 , the battery voltage is U BT , the switching MOS tube period is T1, the conduction time is T1 on , the disconnection time is T1 off , and the conduction duty cycle of the switching MOS tube VD1 is d1=T1 on / T1, so 0 o1 ≤d1≤1, and U BT =d1·U o1The longer the opening time is, the higher the output voltage is.

[0055] The output voltage of the BOOST circuit is U o2 The input voltage is U o1 The switching MOS tube period is T2, and the conduction time is T2 on The conduction duty ratio of the switching MOS tube VD2 is d2=T2 on / T2, thus 0≤d2<1, and U o2 =U o1 / (1-d2) can be obtained through calculation, and it can be seen from the above formula that the output voltage value can be adjusted by adjusting the opening time of the switching MOS tube, and the longer the opening time is, the higher the output voltage is.

[0056] Thus, the voltage U o2 =d1·U BT / (1-d2) loaded on the PTC resistance can be obtained, that is, the voltage across the PTC resistance is adjusted by adjusting the conduction duty ratio d1 of the switching MOS tube VD1 and the conduction duty ratio d2 of the switching MOS tube VD2, and thus the discharge power is adjusted.

[0057] In an embodiment of the present application, when the highest discharge voltage of the battery is 50V and the current is 600mA, the minimum output voltage is 15V according to the BUCK circuit voltage reduction range, and the output PWM duty ratio d1 can be adjusted to 0.3 (because the duty ratio is in the range of 0.3-0.8, and the power supply efficiency reaches a high state). The BOOST voltage boosting circuit boosts 11V, and the boosted output voltage value is stabilized at about 26V (d2=0.42). When the battery discharge voltage is low, the input voltage of the BOOST voltage boosting circuit is lower than 6V, and then the under-voltage alarm is triggered. When the input voltage is lower than 6V, the main controller detects the battery capacity and judges to switch the battery connection circuit from the discharge circuit to the charging circuit to charge and maintain the battery.

[0058] The discharge resistance value can be set according to actual needs, different discharge loads can be switched through the MOSFET switch, and the output load power can be adjusted, and the output load power can also be fine-tuned through the above two voltage adjustment circuits.

[0059] The charge and discharge flow chart of the charge and discharge device is shown in Figure 1 .

[0060] The main controller controls the charging and discharging of the battery according to the voltage and current state of the battery and the state time length, including:

[0061] The main controller sets different currents for trial charging according to the current voltage value sampled by the signal acquisition circuit, and performs normal charging on the storage battery when the trial charging is normal; during the normal charging process, the main controller samples the current charging current of the storage battery according to the signal acquisition circuit, and judges the current charging current; first, it is judged whether the current charging current is below 0.1C, if yes, the pulse charging and discharging stage is entered; otherwise, it is judged whether the current charging current is greater than 0.4C, if yes, the main controller sets the current charging current to 0.3C, if less than or equal to 0.4C, the main controller sets the current charging current to 0.2C or 0.1C; when the first charging end condition is reached, the charging is stopped.

[0062] Specifically, when the battery to be maintained is connected to the charging and discharging device of the embodiment, the charging and discharging device is connected to the upper computer, the upper computer issues the charging parameter command according to the type of the battery to be maintained, and the upper computer first preliminarily detects whether it can be normally charged, and if not, the charging and discharging device is turned off. If it can be normally charged, the charging current is set according to the current battery voltage range, including: if the current battery voltage is greater than 1.05 times the nominal voltage, the charging is set to be performed by supplementing charging, the charging current is set to 0.3C for normal charging; if the current battery voltage is between 1.01 times and 1.05 times the nominal voltage, it is judged to be half-electric, the charging current is set to 1C for normal charging; if the current battery voltage is less than 1.01 times the nominal voltage, it is judged to be empty, the charging current is set to 1C for normal charging. After the above settings, the charging is first performed by trial charging, including: if the current is less than 0.06C within 1 minute, the charging and discharging device is turned off, if the current is normal within 1 minute, the charging is continued for 4 minutes, and the voltage indicated by the voltage table fed back by the signal acquisition circuit shows that the voltage is in a rising state, it is judged whether the difference between the current voltage and the maximum voltage set by the upper computer is less than 0.5V, if yes, it indicates that the battery is close to the full charging state, in order to avoid overcharging, the charging and discharging device is turned off.

[0063] During the normal charging process, if it is detected that the current is below 0.1C, it indicates that the current battery may be full of power, or the battery has been over-discharged for a long time or has a sulfuration trend, and pulse charging is adopted for recovery. If it is detected that the current is greater than 0.4C during the normal charging process, in order to avoid damage to the battery caused by long-time large-current charging, the current is reduced to 0.3C; similarly, if it is less than or equal to 0.4C, 0.2C or 0.1C is used for charging as much as possible.

[0064] The first charging end condition includes: the main controller judges the storage battery voltage to be more than 1.33 times the nominal voltage according to the voltage value sampled by the signal acquisition circuit, or the difference between the current battery voltage and the maximum battery voltage is less than or equal to 0.6V, or the current is reduced to 0.06C; any of the above states lasts for more than or equal to 4s.

[0065] Specifically, since the types of batteries are different, the maximum charging voltage is also different, therefore, two voltage conditions of 1.33 times of the nominal voltage or the difference between the current battery voltage and the maximum battery voltage is less than or equal to 0.6V are set as the full charge judgment condition of the end of charging to prevent overcharging.

[0066] The pulse charging and discharging phase includes a pulse charging and discharging test phase and a pulse charging phase and a pulse discharging phase; in the pulse charging and discharging test phase, the main controller controls the battery to perform pulse charging test, if the battery pulse charging test is normal, first perform normal discharge, the discharge duration is 1 second, if the 1 second normal discharge is normal, switch to the pulse charging phase, until the second charging end condition is reached, the pulse charging is stopped; in the pulse charging and discharging test phase, if the battery pulse charging test is not normal, first perform normal charging, the charging duration is 1 second, if the 1 second normal charging is normal, switch to the pulse discharging phase, until the second discharging end condition is reached, the pulse discharging is stopped.

[0067] Specifically, in order to comprehensively and accurately analyze the current state of the battery, set the corresponding charging strategy for adaptive charging, in the pulse charging test phase, if the battery pulse charging test is normal, first perform normal discharge test, if the discharge is also normal, the pulse charging can be continued. Similarly, in the pulse charging and discharging test phase, if the battery cannot perform pulse charging, first perform normal charging for 1 second, if the 1 second state is normal, the battery will at least store some power, if the pulse discharging is normal, feedback can be received, a variety of combination strategies are adopted to deal with overcharging and overdischarging, and the sulfuration phenomenon is about to occur, and the battery is maintained.

[0068] The pulse charging phase includes: the main controller sets different currents for pulse charging according to the current battery voltage value sampled by the signal acquisition circuit, when the sampled voltage value is lower than 1.01 times of the nominal voltage, the main controller sets the charging current to 1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the charging current to 0.5C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the charging current to 0.2C; in the pulse charging phase, the main controller sets the battery charging voltage to 1.33 times of the nominal voltage.

[0069] The pulse discharging stage comprises: the main controller sets different currents for pulse discharging according to the current battery voltage value sampled by the signal acquisition circuit; when the sampled voltage value is lower than 1.01 times of the nominal voltage, the main controller sets the discharging current to be 0.1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the discharging current to be 0.2C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the discharging current to be 0.5C; and the main controller sets the discharging voltage to be 0.7 times of the nominal voltage in the pulse discharging stage.

[0070] Specifically, different currents are set according to the current voltage value in the pulse charging stage; when the voltage is about to be full, the current is not easy to enter the battery, so the higher the current voltage is, the lower the charging current is set, so that the utilization rate of the power supply can be improved. In the pulse discharging stage, different currents are set according to the current voltage value; the higher the current voltage is, the higher the charging current is set, so that the stable operation of the battery discharging can be maintained.

[0071] The second charging end condition comprises: the time when the pulse charging voltage is greater than 1.33 times of the nominal voltage is more than 2s, or the time when the pulse charging current is reduced to be less than or equal to 0.06C is more than 2s, or the total length of the time when the voltage value in the battery conventional charging and pulse charging stage is in the range of 1.01-1.05 times of the nominal voltage is more than 175min, or the length of the pulse charging stage is more than 85min, or the total length of the time when the voltage value in the battery conventional charging and pulse charging stage is lower than 1.01 times of the nominal voltage is more than 420min.

[0072] The second discharging end condition comprises: the total length of the time when the voltage value in the battery conventional charging and pulse discharging stage is in the range of 1.01-1.05 times of the nominal voltage is more than 175min, or the total length of the time when the voltage value in the battery conventional charging and pulse discharging stage is lower than 1.01 times of the nominal voltage is more than 420min, or the total length of the pulse discharging stage is more than 85min, or the length of the time when the pulse discharging current is reduced to be less than or equal to 0.06C is more than 2s.

[0073] Specifically, the set second charging and discharging end condition is the total end condition of this maintenance, and the total charging and pulse charging and discharging time length set according to different voltage ranges can automatically end the charging and discharging, so that long-time invalid charging or discharging can be avoided.

[0074] Compared with the prior art, the new type battery charging and discharging device provided by the embodiment sets an adaptive charging and discharging strategy according to the charge condition of the battery, a signal acquisition circuit samples to detect the current battery voltage and current in real time, and the main controller changes the pulse current at any time according to the detected current battery voltage and current, maintains dynamic balance with the self-discharge of the battery, adopts the first and second charging end conditions, and can prevent overcharging of the battery; the combination of the conventional charging and the pulse charging and discharging is adopted to maintain the battery, so that the maintained battery will neither be overcharged nor lose water. The PTC resistance value of the discharging circuit of the embodiment can be set according to actual needs, the load power can be coarsely adjusted by switching different branch duty cycles through the MOSFET switch, and the load power can be finely adjusted through the switching duty cycles of the step-down circuit and the step-up circuit connected in sequence in the discharging circuit; the switching duty cycles of the step-down circuit and the step-up circuit are both set in the range of 0.3-0.8, the harmonics of the MOS switch tube are suppressed, and the power supply efficiency is relatively high. The charging circuit of the embodiment adopts the LLC half-bridge resonant circuit design, the primary side two main MOS switches of the LLC half-bridge resonant circuit power supply realize zero voltage turn-on (ZVS) and the secondary side rectifier diode realizes zero current turn-off (ZCS), through the soft switching technology, the switching loss of the power supply can be reduced, and the efficiency and power density of the power converter can be improved.

[0075] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing related hardware, and the program can be stored in a computer readable storage medium, wherein the computer readable storage medium is a disk, an optical disk, a read-only memory or a random access memory, etc.

[0076] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A novel battery charging and discharging device, characterized by, The device comprises a power circuit and a control circuit; the power circuit comprises a charging circuit and a discharging circuit; the control circuit comprises a main controller and a signal acquisition circuit; the signal acquisition circuit is used for acquiring the voltage and current values of the storage battery and sending them to the main controller; the main controller controls the charging and discharging of the storage battery according to the voltage and current states and state time length of the storage battery. The discharging circuit comprises a step-by-step connected voltage reduction circuit, voltage increase circuit and discharging load circuit; the discharging load circuit comprises a plurality of parallel branches, each branch comprising a current regulating switch tube and a PTC resistor connected in series; the voltage reduction circuit and the voltage increase circuit each comprise a voltage regulating switch tube; the main controller sends PWM pulses to the voltage regulating switch tube, so that the output voltages of the voltage reduction circuit and the voltage increase circuit reach the set threshold range; the main controller sends wide PWM pulses to the current regulating switch tube, so that the current value of the discharging circuit reaches the set threshold.

2. The charge and discharge device according to claim 1, wherein In the voltage reduction circuit and the voltage increase circuit, the duty cycle range of the PWM pulses sent by the main controller to the voltage regulating switch tube is 0.3-0.

8.

3. The charge and discharge device according to claim 1, wherein The main controller controls the charging and discharging of the storage battery according to the voltage and current states and state time length of the storage battery, comprising: The main controller sets different currents according to the current voltage value of the storage battery obtained by the signal acquisition circuit sampling to perform trial charging, and performs normal charging on the storage battery when the trial charging is normal; during the normal charging, the main controller obtains the current charging current of the storage battery by sampling the signal acquisition circuit and judges the current charging current; first, it is judged whether the current charging current is below 0.1C, if yes, it enters the pulse charging and discharging stage; otherwise, it is judged whether the current charging current is greater than 0.4C, if yes, the main controller sets the current charging current to 0.3C, if less than or equal to 0.4C, the main controller sets the current charging current to 0.2C or 0.1C; stop charging when the first charging end condition is reached.

4. The charge and discharge device according to claim 3, wherein The first charging end condition includes: the main controller judges that the voltage value obtained by sampling the signal acquisition circuit indicates that the voltage of the storage battery exceeds 1.33 times of the nominal voltage, or the difference between the current battery voltage and the maximum battery voltage is less than or equal to 0.6V, or the current decreases to 0.06C; the duration of any of the above states is greater than or equal to 4s.

5. The charge and discharge device according to claim 3, wherein The pulse charging and discharging stage comprises a pulse charging and discharging test stage and a pulse charging stage and a pulse discharging stage; in the pulse charging and discharging test stage, the main controller controls the storage battery to perform pulse charging test, if the pulse charging test of the storage battery is normal, first perform normal discharge, the discharge time is 1 second, if the 1 second normal discharge is normal, convert to pulse charging stage, until the second charging end condition is reached to stop pulse charging; in the pulse charging and discharging test stage, if the pulse charging test of the storage battery is not normal, first perform normal charging, the charging time is 1 second, if the 1 second normal charging is normal, convert to pulse discharging stage, until the second discharging end condition is reached to stop pulse discharging.

6. The charge and discharge device according to claim 5, wherein The pulse charging stage comprises: the main controller sets different currents for pulse charging according to the current battery voltage value sampled by the signal acquisition circuit; when the sampled voltage value is lower than 1.01 times of the nominal voltage, the main controller sets the charging current to 1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the charging current to 0.5C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the charging current to 0.2C; in the pulse charging stage, the main controller sets the battery charging voltage to 1.33 times of the nominal voltage.

7. The charge and discharge device according to claim 6, wherein The pulse discharging stage comprises: the main controller sets different currents for pulse discharging according to the current battery voltage value sampled by the signal acquisition circuit; when the sampled voltage value is lower than 1.01 times of the nominal voltage, the main controller sets the discharging current to 0.1C; when the sampled voltage value is in the range of 1.01-1.33 times of the nominal voltage, the main controller sets the discharging current to 0.2C; when the sampled voltage value is greater than 1.33 times of the nominal voltage, the main controller sets the discharging current to 0.5C; in the pulse discharging stage, the main controller sets the discharging voltage to 0.7 times of the nominal voltage.

8. The charge and discharge device according to claim 7, wherein The second charging end condition comprises: the time when the pulse charging voltage is greater than 1.33 times of the nominal voltage exceeds 2s, or the time when the pulse charging current decreases to be less than or equal to 0.06C exceeds 2s, or the total length of the time when the voltage value in the battery normal charging and pulse charging stages is in the range of 1.01-1.05 times of the nominal voltage exceeds 175min, or the length of the pulse charging stage exceeds 85min, or the total length of the time when the voltage value in the battery normal charging and pulse charging stages is lower than 1.01 times of the nominal voltage exceeds 420min.

9. The charge and discharge device according to claim 7, wherein The second discharging end condition comprises: the total length of the time when the voltage value in the battery normal charging and pulse discharging stages is in the range of 1.01-1.05 times of the nominal voltage exceeds 175min, or the total length of the time when the voltage value in the battery normal charging and pulse discharging stages is lower than 1.01 times of the nominal voltage exceeds 420min, or the total length of the pulse discharging stage exceeds 85min, or the length of the time when the pulse discharging current decreases to be less than or equal to 0.06C exceeds 2s.

10. The charge and discharge device according to claim 1, wherein The charging circuit comprises an interleaved parallel Boost PFC circuit, an LLC half-bridge resonant circuit and a synchronous rectification circuit connected in sequence; the interleaved parallel Boost PFC circuit and the LLC half-bridge resonant circuit each comprise a plurality of switching tubes; when the difference between the charging voltage or current set by the main controller and the voltage value or current value sampled by the signal acquisition circuit is greater than a set voltage threshold or current threshold, the main controller preferentially adjusts the switching tubes of the interleaved parallel Boost PFC circuit, otherwise when the difference between the charging voltage or current set by the main controller and the voltage value or current value sampled by the signal acquisition circuit is less than or equal to the set voltage threshold or current threshold, the main controller preferentially adjusts the duty cycle of the switching tubes of the LLC half-bridge resonant circuit.

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