Method and device for improving charging efficiency of battery of electric bicycle

Abstract

The invention discloses a method and device for improving the charging efficiency of an electric bicycle battery, and relates to the technical field of electric bicycle charging, and the method comprises the steps: enabling a charger MCU to enter a corresponding battery charging stage according to the current electric quantity of a battery after the charger is connected to the battery, sequentially entering the next battery charging stage according to a specified sequence until the charging is completed; and when the battery enters a trickle charging stage, the MCU of the charger starts a micro-pulse strategy, so that the charger outputs a target charging voltage and an instantaneous current meeting a certain pulse frequency, and the target charging voltage and the instantaneous current are used for de-vulcanization of the battery. The side reaction of the negative electrode of the battery in the charging process is eliminated through high voltage and instantaneous large current generated in the trickle charging stage, so that the service life of the battery is prolonged, and the driving mileage is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of electric bicycle charging, and in particular to a method and a device for improving the charging efficiency of an electric bicycle battery. Background Art

[0002] Nowadays, electric bicycles are the first choice for many people to travel short distances, and the main power source of electric bicycles is battery packs. While electric bicycles bring convenience to everyone, their endurance and charging capabilities are facing new challenges. Since electric bicycles are affected by battery volume and safety, the battery size cannot be increased infinitely to achieve long-term endurance. The public has put forward higher requirements for battery chargers and charging methods, such as safety, portability, compactness, high charging efficiency, and compatibility.

[0003] At the same time, the new national standard GB42296 strictly defines high-efficiency charging and high-voltage charging, and puts forward higher requirements for charging. The current charging strategy can no longer meet the needs of efficient charging of the whole vehicle. In this case, a new charging strategy is proposed to solve the problems of long charging time, easy heating and short battery life. Summary of the invention

[0004] In view of the above problems and technical requirements, the inventors have proposed a method and device for improving the charging efficiency of electric bicycle batteries. The technical solution of the present invention is as follows:

[0005] In a first aspect, the present application provides a method for improving the charging efficiency of an electric bicycle battery, comprising the following steps:

[0006] After the charger is connected to the battery, the charger MCU determines to enter the corresponding battery charging stage according to the current battery power, and enters the next battery charging stage in the prescribed order until charging is completed;

[0007] When entering the trickle charging stage, the charger MCU enables the micro-pulse strategy to make the charger output a target charging voltage and instantaneous current that meets a certain pulse frequency, which is used to desulfurize the battery.

[0008] A further technical solution is that the charger MCU determines to enter the corresponding battery charging stage according to the current battery power, including:

[0009] If the current battery power is lower than the first power threshold, the first high-efficiency charging stage is entered;

[0010] If the current battery power is neither lower than the first power threshold nor higher than the second power threshold, the second high-efficiency charging stage is entered;

[0011] If the current battery power is higher than the second power threshold, the second high-voltage charging stage is entered;

[0012] It is also stipulated that charging is completed in the order of a first high-efficiency charging stage, a second high-efficiency charging stage, a second high-voltage charging stage and a trickle charging stage.

[0013] Its further technical solution is that, in the first and second high-efficiency charging stages, the battery is charged with constant current and high efficiency, and when the battery charging voltage rises to the corresponding voltage threshold, it enters the next battery charging stage;

[0014] The voltage threshold of the first high-efficiency charging stage is smaller than the voltage threshold of the second high-efficiency charging stage.

[0015] Its further technical solution is that the method further comprises:

[0016] A first high-voltage charging stage is provided between the first and second high-efficiency charging stages.

[0017] A further technical solution is to charge the battery with a constant voltage and variable current in the first and second high-voltage charging stages, and to enter the next battery charging stage when the charging current decreases to a corresponding current conversion point;

[0018] The current conversion point in the first high-voltage charging stage is greater than the current conversion point in the second high-voltage charging stage.

[0019] A further technical solution is that the charger MCU determines to enter a corresponding battery charging stage according to the current battery power, and also includes:

[0020] If the current battery voltage is lower than the first voltage threshold, the pre-charging stage is entered first, and when the battery voltage rises to the second voltage threshold, the first high-efficiency charging stage is entered;

[0021] Otherwise, determine to enter the corresponding battery charging stage according to the current battery power.

[0022] The further technical solution is that the charger MCU enables the micro-pulse strategy to make the charger output high voltage and instantaneous high current that meet a certain pulse frequency, including:

[0023] A pulse control circuit is added inside the charger, the control end of the pulse control circuit is connected to the charger MCU, the input end of the pulse control circuit is connected to the charging voltage, and the output end of the pulse control circuit is connected to the battery;

[0024] When the charger MCU detects that it has entered the trickle charging stage, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency. At the same time, the charger MCU cooperates with the charger switching power supply circuit to adjust its own PWM duty cycle, so that the charger outputs high voltage and instantaneous large current that meet a certain pulse frequency.

[0025] A further technical solution is that, during the trickle charging stage, the maximum value of the target charging voltage generated does not exceed 1.3 times the rated voltage of the charger, and the maximum value of the target instantaneous current does not exceed 10 times the rated current of the charger.

[0026] In a second aspect, the present application also provides a device for improving the charging efficiency of an electric bicycle battery, comprising a charger body and placed therein: a charger MCU, a switching power supply circuit, a detection circuit and a pulse control circuit;

[0027] The input end of the switching power supply circuit is connected to the DC charging voltage converted from the AC mains, the output end of the switching power supply circuit is connected to the input end of the pulse control circuit through the detection circuit, and the output end of the pulse control circuit is connected to the battery;

[0028] The charger MCU is respectively connected to the detection circuit, the control end of the pulse control circuit, the feedback end of the switching power supply circuit and the battery BMS. The detection circuit is used to detect the charging voltage and current information;

[0029] The charger MCU determines to enter the corresponding battery charging stage according to the current battery power fed back by the battery BMS, and enters the next battery charging stage in the prescribed order until charging is completed;

[0030] When the charger MCU detects that it has entered the trickle charging stage, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency. At the same time, it feeds back the charging voltage and current information required for this stage to the switching power supply circuit, thereby adjusting the PWM duty cycle of the switching power supply circuit, so that the charger outputs a target charging voltage and instantaneous current that meet a certain pulse frequency, which is used to desulfurize the battery.

[0031] A further technical solution is that the pulse control circuit includes: first to fourth resistors, first to third MOS tubes, a first diode and an optical coupler;

[0032] The anode of the first diode is connected to one end of the second resistor through the first resistor, and the connection end of the first and second resistors is connected to the charger MCU as the control end of the pulse control circuit; the cathode of the first diode is connected to the gate of the first MOS tube through the third resistor, and the source of the first MOS tube is grounded; the two ends of the transmitting side of the optocoupler are respectively connected to the drain of the first MOS tube and the other end of the second resistor, one end of the light receiving side of the optocoupler is connected to the power supply, and the other end is respectively connected to one end of the fourth resistor and the gates of the second and third MOS tubes, the drain of the second MOS tube is used as the input end of the pulse control circuit, the drain of the third MOS tube is used as the output end of the pulse control circuit, the source of the second MOS tube is connected to the source of the third MOS tube, and the other end of the fourth resistor is connected between the sources of the second and third MOS tubes;

[0033] When the charger MCU detects that it has entered the trickle charging stage, it controls the on and off of the first MOS tube according to the set pulse frequency, and then drives the on and off of the second and third MOS tubes through the optical coupler.

[0034] The beneficial technical effects of the present invention are:

[0035] In the method and device for improving the charging efficiency of electric bicycle batteries provided in the present application, the charging stage is divided into a pre-charging stage, a first high-efficiency charging stage, a first high-voltage charging stage, a second high-efficiency charging stage, a second high-voltage charging stage and a trickle charging stage. The high-efficiency and high-voltage charging stages ensure that the charging voltage is stable and gradually increases, and the charging current alternates between constant current and reduction, which can not only shorten the charging time, but also alleviate the problem of battery heating. In the final trickle charging stage, a micro-pulse strategy is used to make the charger output high voltage and instantaneous high current to eliminate the problem of side reactions at the negative electrode of the battery during charging, thereby increasing battery life and extending driving mileage. This charging method can effectively overcome the limitations of traditional constant current and constant voltage charging strategies, and solve problems such as long charging time, fast temperature rise of high current charging, battery bulging, and low safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of a method for improving the charging efficiency of an electric bicycle battery provided in this application.

[0037] Figure 2 It is a schematic diagram of the charging voltage and charging current changing with time in each charging stage provided by the present application.

[0038] Figure 3 It is a schematic diagram of the internal circuit of the charger provided in this application. DETAILED DESCRIPTION

[0039] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0040] Please refer to Figure 1 As shown, an embodiment of the present application provides a method for improving the charging efficiency of an electric bicycle battery, which specifically includes the following steps:

[0041] Step 1: After the charger is connected to the battery, the charger MCU determines to enter the corresponding battery charging stage according to the current battery power, and enters the next battery charging stage in the prescribed order until charging is completed. The charger MCU reads the battery voltage and power (SOC) fed back by the battery BMS through one-line communication, and then compares it with the various thresholds pre-stored in the MCU to determine to enter the corresponding battery charging stage. This step specifically includes the following contents:

[0042] If the current battery voltage is lower than the first voltage threshold Va, it will first enter the pre-charging stage T1. When the battery voltage rises to the second voltage threshold Vb, it will enter other charging stages until charging is completed. When the current battery voltage is not lower than the first voltage threshold: If the current battery power is lower than the first power threshold (for example, SOC < 90%), it will directly enter the first high-efficiency charging stage T2. The pre-charging stage T1 does not overlap with the first high-efficiency charging stage T2, and the charging time of T1 is much shorter than the charging time of T2; if the current battery power is not lower than the first power threshold and not higher than the second power threshold (for example, 90% ≤ SOC ≤ 98%), it will directly enter the second high-efficiency charging stage T4; if the current battery power is higher than the second power threshold (for example, SOC > 98%), it will enter the second high-voltage charging stage T5. In this embodiment, a first high-voltage charging stage T3 is provided between the first and second high-efficiency charging stages, and it is stipulated that each charging stage completes charging in the order of a pre-charging stage T1, a first high-efficiency charging stage T2, a first high-voltage charging stage T3, a second high-efficiency charging stage T4, a second high-voltage charging stage T5 and a trickle charging stage T6.

[0043] Combination Figure 2 As shown, in the first high-efficiency charging stage T2, the battery is charged with constant current and high efficiency, and when the battery charging voltage rises to the third voltage threshold Vc, the first high-voltage charging stage T3 is entered to charge the battery with constant voltage and current, at which time the charging current begins to decrease until it decreases to the first current conversion point Ia, and preferably Ia is 40% of the maximum constant current charging current. When the charging current drops to the first current conversion point Ia, after detection and judgment by the charger MCU, the second high-efficiency charging stage T4 is entered to charge the battery with constant current and high efficiency, and when the battery charging voltage rises to the fourth voltage threshold Vd, the second high-voltage charging stage T5 is entered to charge the battery with constant voltage and current, at which time the charging current begins to decrease until it decreases to the second current conversion point Ib, and preferably Ib is 15% of the maximum constant current charging current. When the charging current drops to the second current conversion point Ib, the trickle charging stage T6 is entered and timed charging begins until charging ends T7.

[0044] Optionally, the magnitude relationship of the above voltage thresholds is: Va<Vb<Vc<Vd.

[0045] Step 2: When entering the trickle charge stage T6, the charger MCU enables the micro-pulse strategy to make the charger output a target charging voltage and instantaneous current that meets a certain pulse frequency, which is used to desulfurize the battery. Figure 3As shown, a pulse control circuit is added inside the charger, the control end of the pulse control circuit is connected to the charger MCU, the input end of the pulse control circuit is connected to the charging voltage, and the output end of the pulse control circuit is connected to the battery. When the charger MCU detects that it has entered the trickle charging stage, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency. At the same time, the charger MCU cooperates with the charger switching power supply circuit to adjust its own PWM duty cycle, so that the charger outputs a target charging voltage and instantaneous current that meet a certain pulse frequency. The target charging voltage needs to be a high voltage, and the target instantaneous current is an instantaneous large current, thereby playing a desulfurization role. In this embodiment, the maximum value of the target charging voltage is set to not exceed 1.3 times the rated voltage of the charger, and the maximum value of the target instantaneous current is set to not exceed 10 times the rated current of the charger. The high voltage and instantaneous large current have an obvious repair effect on the battery capacity reduction due to sulfurization, which can greatly increase the battery life and extend the driving mileage.

[0046] Optionally, the pulse frequency range is set between 10 Hz and 20 KHz, and the specific implementation strategy is adjusted according to different requirements and tests.

[0047] Based on the same inventive concept, another embodiment of the present application provides a device for improving the charging efficiency of an electric bicycle battery, such as Figure 3 As shown, the device includes a charger body and the following components placed therein: a charger MCU, a switching power supply circuit, a detection circuit, and a pulse control circuit. After the charger AC is connected to the mains and the DC is connected to the battery, the AC mains is converted into a DC charging voltage through the surge protection, rectification and filtering circuit, and DC conversion of the front-end processing circuit. The input end of the switching power supply circuit is connected to the DC charging voltage, and the output end of the switching power supply circuit is connected to the input end of the pulse control circuit through the detection circuit. The output end of the pulse control circuit is connected to the battery. The charger MCU is respectively connected to the detection circuit, the control end of the pulse control circuit, the feedback end of the switching power supply circuit, and the battery BMS, wherein the detection circuit is used to detect the charging voltage and current information.

[0048] The charger MCU determines to enter the corresponding battery charging stage according to the current battery power fed back by the battery BMS, and enters the next battery charging stage in the prescribed order until the charging is completed. The content of this part can refer to the specific content of step 1 in the above-mentioned method for improving the charging efficiency of electric bicycle batteries, which will not be repeated here. In addition, when the charger MCU detects that it has entered the trickle charging stage T6, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency, and cooperates with the detection circuit to feed back the charging voltage and current information required for this stage to the switching power supply circuit through the feedback network. The switching power supply circuit adjusts its own (i.e., MOS tube Q1) PWM duty cycle to stabilize the current output power, so that the charger outputs a target charging voltage (high voltage) and instantaneous current (instantaneous high current) that meet a certain pulse frequency, which is used to desulfurize the battery, and sets the maximum value of the target charging voltage to not exceed 1.3 times the rated voltage of the charger, and the maximum value of the target instantaneous current to not exceed 10 times the rated current of the charger.

[0049] The pulse control circuit includes: first to fourth resistors, first to third MOS tubes, first diode D1 and optocoupler U3. Among them, the anode of the first diode D1 is connected to one end of the second resistor R10 through the first resistor R11, the connection end of the first resistor R11 and the second resistor R10 is connected to the charger MCU as the control end of the pulse control circuit, the cathode of the first diode D1 is connected to the gate of the first MOS tube Q4 through the third resistor R8, and the source of the first MOS tube Q4 is grounded. The two ends of the optocoupler transmitting side U3A are respectively connected to the drain of the first MOS tube Q4 and the other end of the second resistor R10, one end of the optocoupler light receiving side U3B is connected to the power supply VDD, and the other end is respectively connected to one end of the fourth resistor R7, the gates of the second MOS tube Q2 and the third MOS tube Q3, the drain of the second MOS tube Q2 is used as the input end of the pulse control circuit, the drain of the third MOS tube Q3 is used as the output end of the pulse control circuit, the source of the second MOS tube Q2 is connected to the source of the third MOS tube Q3, and the other end of the fourth resistor R7 is connected between the sources of the second MOS tube Q2 and the third MOS tube Q3.

[0050] The working principle of the pulse control circuit is that when the charger MCU detects that it has entered the trickle charging stage T6, it controls the on and off of the first MOS tube Q4 according to the set pulse frequency, and then turns the optical coupler U3 on and off, and then drives the on and off of the second MOS tube Q2 and the third MOS tube Q3 through the optical coupler U3, so that the charger outputs high voltage and instantaneous high current. At the same time, the second MOS tube Q2 and the third MOS tube Q3 also play a protective role in preventing backflow and wrong connection.

[0051] The high voltage and instantaneous high current generated by the charger will break down the macromolecular lead sulfate crystals with an insulating layer, and the coarse lead sulfate will become conductive. Under the strong redox effect of the current, lead and sulfuric acid will be regenerated to participate in the electrochemical reaction. Under the condition of ensuring the breakdown of the coarse lead sulfate crystals, the micro-charging that occurs at the same time will not have time to form gas evolution. In this way, pulse elimination of sulfidation can be achieved without damaging the battery, and the repair effect of the battery whose capacity is reduced due to sulfidation is obvious, which can greatly increase the battery life and extend the driving mileage.

[0052] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A method for improving the charging efficiency of an electric bicycle battery, characterized in that: The method comprises: After the charger is connected to the battery, the charger MCU determines to enter the corresponding battery charging stage according to the current battery power, and enters the next battery charging stage in the prescribed order until charging is completed; When entering the trickle charging stage, the charger MCU enables the micro-pulse strategy to make the charger output a target charging voltage and instantaneous current that meet a certain pulse frequency, which is used to desulfurize the battery.

2. The method for improving the charging efficiency of an electric bicycle battery according to claim 1, characterized in that: The charger MCU determines to enter a corresponding battery charging stage according to the current battery power, including: If the current battery power is lower than the first power threshold, the first high-efficiency charging stage is entered; If the current battery power is neither lower than the first power threshold nor higher than the second power threshold, the second high-efficiency charging stage is entered; If the current battery power is higher than the second power threshold, the second high-voltage charging stage is entered; It is also stipulated that charging is completed in the order of the first high-efficiency charging stage, the second high-efficiency charging stage, the second high-voltage charging stage and the trickle charging stage.

3. The method for improving the charging efficiency of an electric bicycle battery according to claim 2, characterized in that: In the first and second high-efficiency charging stages, the battery is charged with constant current and high efficiency, and when the battery charging voltage rises to the corresponding voltage threshold, it enters the next battery charging stage; The voltage threshold of the first high-efficiency charging stage is smaller than the voltage threshold of the second high-efficiency charging stage.

4. The method for improving the charging efficiency of an electric bicycle battery according to claim 2 or 3, characterized in that: The method further comprises: A first high-voltage charging stage is provided between the first and second high-efficiency charging stages.

5. The method for improving the charging efficiency of an electric bicycle battery according to claim 4, characterized in that: In the first and second high-voltage charging stages, the battery is charged with a constant voltage variable current, and when the charging current is reduced to the corresponding current conversion point, the next battery charging stage is entered; Wherein, the current conversion point of the first high-voltage charging stage is greater than the current conversion point of the second high-voltage charging stage.

6. The method for improving the charging efficiency of an electric bicycle battery according to claim 2, characterized in that: The charger MCU determines to enter a corresponding battery charging stage according to the current battery power, and also includes: If the current battery voltage is lower than the first voltage threshold, the pre-charging stage is first entered, and when the battery voltage rises to the second voltage threshold, the first high-efficiency charging stage is entered; Otherwise, determine to enter the corresponding battery charging stage according to the current battery power.

7. The method for improving the charging efficiency of an electric bicycle battery according to claim 1, characterized in that: The charger MCU enables the micro-pulse strategy to enable the charger to output high voltage and instantaneous high current that meet a certain pulse frequency, including: A pulse control circuit is added inside the charger, the control end of the pulse control circuit is connected to the charger MCU, the input end of the pulse control circuit is connected to the charging voltage, and the output end of the pulse control circuit is connected to the battery; When the charger MCU detects that it has entered the trickle charging stage, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency. At the same time, the charger MCU cooperates with the charger switching power supply circuit to adjust its own PWM duty cycle, so that the charger outputs high voltage and instantaneous large current that meet a certain pulse frequency.

8. The method for improving the charging efficiency of an electric bicycle battery according to claim 1, characterized in that: In the trickle charging stage, the maximum value of the target charging voltage generated does not exceed 1.3 times the rated voltage of the charger, and the maximum value of the target instantaneous current does not exceed 10 times the rated current of the charger.

9. A device for improving the charging efficiency of an electric bicycle battery, characterized in that: It includes a charger body and the following components placed therein: a charger MCU, a switching power supply circuit, a detection circuit and a pulse control circuit; The input end of the switching power supply circuit is connected to the DC charging voltage converted from the AC mains, the output end of the switching power supply circuit is connected to the input end of the pulse control circuit through the detection circuit, and the output end of the pulse control circuit is connected to the battery; The charger MCU is respectively connected to the detection circuit, the control end of the pulse control circuit, the feedback end of the switch power supply circuit and the battery BMS, and the detection circuit is used to detect the charging voltage and current information; The charger MCU determines to enter the corresponding battery charging stage according to the current battery power fed back by the battery BMS, and enters the next battery charging stage in a prescribed order until charging is completed; When the charger MCU detects that it has entered the trickle charging stage, it controls the pulse control circuit to repeatedly connect and disconnect the charger and the battery according to the set pulse frequency, and at the same time feeds back the charging voltage and current information required for this stage to the switching power supply circuit, thereby adjusting the PWM duty cycle of the switching power supply circuit, so that the charger outputs a target charging voltage and instantaneous current that meet a certain pulse frequency, which is used to desulfurize the battery.

10. The device for improving the charging efficiency of an electric bicycle battery according to claim 9, characterized in that: The pulse control circuit comprises: first to fourth resistors, first to third MOS tubes, a first diode and an optical coupler; The anode of the first diode is connected to one end of the second resistor through the first resistor, and the connection end of the first and second resistors is connected to the charger MCU as the control end of the pulse control circuit; the cathode of the first diode is connected to the gate of the first MOS tube through the third resistor, and the source of the first MOS tube is grounded; the two ends of the transmitting side of the optocoupler are respectively connected to the drain of the first MOS tube and the other end of the second resistor, one end of the light receiving side of the optocoupler is connected to the power supply, and the other end is respectively connected to one end of the fourth resistor and the gates of the second and third MOS tubes, the drain of the second MOS tube is used as the input end of the pulse control circuit, the drain of the third MOS tube is used as the output end of the pulse control circuit, the source of the second MOS tube is connected to the source of the third MOS tube, and the other end of the fourth resistor is connected between the sources of the second and third MOS tubes; When the charger MCU detects that it has entered the trickle charging stage, it controls the on and off of the first MOS tube according to the set pulse frequency, and then drives the on and off of the second and third MOS tubes through the optical coupler.

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