A lithium battery charge-discharge management system based on kinetic energy recovery

Abstract

The utility model discloses a lithium battery charge -discharge management system based on kinetic energy recovery, its characterized in that, including kinetic energy recovery power generation module, external quick charging module, lithium battery management module, external discharge module and user interactive module, kinetic energy recovery power generation module and external quick charging module are connected with lithium battery management module through charging switch and selection circuit, lithium battery management module is connected with external discharge module through discharge switch circuit, user interactive module inputs control signal to charging switch and selection circuit, discharge switch circuit and external discharge module, realizes man -machine interaction, kinetic energy recovery power generation module includes permanent magnet synchronous motor, rectifier circuit and kinetic energy recovery intensity intelligent regulation and control circuit, the utility model realizes the function that charges with the fluctuation high voltage power supply that permanent magnet synchronous motor kinetic energy recovery generates.

Description

Technical Field

[0001] This utility model relates to the field of battery management systems, and in particular to a lithium battery charging and discharging management system based on kinetic energy recovery. Background Technology

[0002] A single-cell lithium battery charge / discharge management system manages the current and voltage during battery charging, facilitating rapid charging while simultaneously providing the voltage required by various loads and monitoring the temperature and current during battery discharge. When an malfunction is detected, the system can quickly shut off the battery's output, effectively extending its lifespan. These systems are widely used in small handheld devices due to their small size and low cost.

[0003] Traditional single-cell lithium battery charge / discharge management systems rely on a single power source, typically using a relatively stable DC power output from an external power adapter for charging. The charging voltage is generally below 20V, which cannot withstand the fluctuating high-voltage power output of a permanent magnet synchronous motor. Furthermore, some single-cell lithium battery charge / discharge management systems that support high-voltage charging have not optimized kinetic energy recovery. When connected to a permanent magnet synchronous motor, excessive kinetic energy recovery at low speeds leads to excessive resistance and a poor user experience. These shortcomings limit their application scenarios. Utility Model Content

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this utility model is to provide a lithium battery charging and discharging management system based on kinetic energy recovery.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] A lithium battery charging and discharging management system based on kinetic energy recovery includes a kinetic energy recovery power generation module, an external fast charging module, a lithium battery management module, an external discharging module, and a user interaction module.

[0007] The kinetic energy recovery power generation module and the external fast charging module are connected to the lithium battery management module through a charging switch and selection circuit. The lithium battery management module is connected to the external discharge module through a discharge switch circuit. The user interaction module inputs control signals to the charging switch and selection circuit, the discharge switch circuit and the external discharge module to realize human-computer interaction.

[0008] The kinetic energy recovery power generation module includes a permanent magnet synchronous motor, a rectifier circuit, and a kinetic energy recovery intensity intelligent control circuit. The kinetic energy recovery intensity intelligent control circuit includes a back EMF detection circuit, an overvoltage protection circuit, and a high withstand voltage conversion circuit connected in sequence. The back EMF detection circuit is also connected to a microcontroller.

[0009] Furthermore, the back EMF detection circuit includes three resistors, an NMOS field-effect transistor, and a capacitor. Two resistors are connected in series and then in parallel on the DC bus to form a voltage divider circuit, and one resistor serves as a current-limiting resistor. The capacitor is connected in parallel with the lower half of the resistors in the voltage divider circuit to form a filter circuit. The gate of the NMOS field-effect transistor is connected to the microcontroller through the current-limiting resistor, and the drain of the NMOS field-effect transistor is connected to the Zener diode of the overvoltage protection circuit.

[0010] Furthermore, the overvoltage protection circuit includes three resistors, a Zener diode, a transistor, and a PMOS field-effect transistor.

[0011] Furthermore, the high-voltage conversion circuit includes a DC-DC chip, a resistor, a diode, an inductor, and two electrolytic capacitors. The diode, inductor, and DC-DC chip are connected in the form of a Buck circuit. One of the electrolytic capacitors and the diode are connected in parallel across the two ends of the inductor. The other electrolytic capacitor is placed between the DC-DC chip and the DC bus. One end of the resistor is connected to the port of the DC-DC chip, and the other end is grounded.

[0012] Furthermore, the external fast charging module includes a Type-C interface, a fast charging protocol handshake circuit, and a voltage conversion circuit connected in sequence.

[0013] Furthermore, the user interaction module includes LED indicator lights and buttons. The LED indicator lights can provide battery power indication, kinetic energy recovery prompts, and system fault warnings, while the buttons provide kinetic energy recovery switch and discharge voltage selection.

[0014] Furthermore, the external discharge module includes an output voltage control circuit, a load overcurrent protection circuit, and a load connected in sequence.

[0015] Furthermore, the charging switch and selection circuit includes two parts: one part is used to control kinetic energy recovery, and the other part is used to control fast charging.

[0016] Both parts include two resistors, one NMOS field-effect transistor, one PMOS field-effect transistor, one MCU, and one capacitor; the specific connections are as follows:

[0017] Two resistors form a voltage divider circuit, and the divided voltage is sent to the microcontroller port. The PMOS field-effect transistor is connected in series with the DC bus. The gate of the NMOS field-effect transistor is connected to the microcontroller, the drain is connected to the gate of the PMOS field-effect transistor, and the source of the NMOS field-effect transistor is grounded.

[0018] Furthermore, the section for controlling kinetic energy recovery also includes a capacitor, and the two resistors and capacitor that form the voltage divider circuit are shared with the back EMF detection circuit.

[0019] Furthermore, the capacitance of the capacitor is 5uF.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. This utility model, by designing a high-voltage conversion circuit with high withstand voltage, achieves the function of charging with fluctuating high-voltage power generated by the kinetic energy recovery of a permanent magnet synchronous motor, while keeping the single-cell lithium battery charging and discharging management system small in size. The maximum voltage can reach 60V, thus expanding the power source of the system.

[0022] 2. This utility model, through the design of a back EMF sampling circuit, eliminates the need for a speed sensor at the motor, enabling motor speed identification. The design of the switching circuit avoids the kinetic energy recovery process lowering the back EMF, which could lead to inaccurate speed estimation. Furthermore, the design of the filter circuit removes high-frequency noise from the back EMF, improving the accuracy of speed estimation.

[0023] 3. This utility model designs a kinetic energy recovery and power generation module. Based on the obtained speed of the permanent magnet synchronous motor, it adjusts the power generation duty cycle and intelligently regulates the power generation, making the motor's power generation resistance similar to a frictional load. This results in low-intensity energy recovery at low speeds and high-intensity energy recovery at high speeds. The resistance generated by kinetic energy recovery increases smoothly with the overall resistance, without abrupt changes. The recovery intensity can quickly follow changes in motor speed without any jerking.

[0024] 4. This utility model incorporates an overvoltage protection circuit that shuts down the input circuit within microseconds when the input voltage exceeds 60V, protecting the downstream circuitry. When the permanent magnet synchronous motor rotates at extremely high speeds and the output voltage exceeds the limit, the generator can be immediately cut off, protecting the downstream circuitry and preventing damage to the circuit hardware. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this utility model;

[0026] Figure 2 This is the circuit diagram of the kinetic energy recovery power generation module of this utility model;

[0027] Figure 3 This is a circuit diagram of the charging and selection switch circuit of this utility model. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0029] Example

[0030] like Figure 1 and Figure 2As shown, a lithium battery charging and discharging management system based on kinetic energy recovery includes a kinetic energy recovery power generation module, an external fast charging module, a lithium battery management module, an external discharging module, and a user interaction module. The specific connection method is as follows:

[0031] The kinetic energy recovery power generation module and the external fast charging module are connected to the lithium battery management module through a charging switch and selection circuit. The lithium battery management module is connected to the external discharge module through a discharge switch circuit. The user interaction module inputs control signals to the charging switch and selection circuit, the discharge switch circuit and the external discharge module to realize human-computer interaction.

[0032] The user interaction module has LED indicator lights and buttons;

[0033] The LED indicator provides battery power indication, energy recovery prompts, and system fault warnings, while the button provides an energy recovery switch and discharge voltage selection.

[0034] To further explain, the kinetic energy recovery power generation module includes a permanent magnet synchronous motor, a rectifier circuit, and an intelligent control circuit for kinetic energy recovery intensity. The intelligent control circuit for kinetic energy recovery intensity includes a back EMF detection circuit, an overvoltage protection circuit, a high-voltage conversion circuit, and a microcontroller.

[0035] The permanent magnet synchronous motor, rectifier circuit, back EMF detection circuit, overvoltage protection circuit, and high withstand voltage conversion circuit are connected in sequence; the back EMF detection circuit is also connected to the microcontroller, and the microcontroller sends control signals to the charging switch and selection circuit.

[0036] In general, the back electromotive force generated by a permanent magnet synchronous motor when it rotates is a sine wave, and the phase difference between the three phases is 120°. In order to provide energy to the downstream stage, rectification is usually required. The AC power is rectified into DC power through the rectifier circuit to power the lithium battery.

[0037] The rectifier circuit includes six single-phase uncontrolled diodes D1 to D6, which are connected in the form of a three-phase bridge rectifier circuit.

[0038] The back EMF detection circuit includes resistors R1, R2, and R3, capacitor C1, and NMOS field-effect transistor Q1. R1 and R2 are connected in series on the DC bus to form a voltage divider circuit, sending the divided voltage to the BEMF_Detect port of the microcontroller. The microcontroller is an STM32F103C8T6 MCU. Capacitor C1 is a small capacitor with a capacitance of 5uF, connected in parallel with resistor R2 to filter out high-frequency noise in the back EMF of the permanent magnet synchronous motor, making speed detection more accurate. The gate of NMOS field-effect transistor Q1 is connected to the BEMF_Switch port of the MCU, while the drain of NMOS field-effect transistor Q1 is connected to resistor R5 of the overvoltage protection circuit.

[0039] The working principle of the back EMF detection circuit is as follows:

[0040] When the system is performing kinetic energy recovery, it will inevitably lower the back electromotive force output by the permanent magnet synchronous motor. At this time, the back electromotive force obtained from the BEMF_Detect port of the MCU through the voltage divider circuit will inevitably be too small, resulting in inaccurate speed estimation and further affecting the control of kinetic energy recovery intensity.

[0041] Therefore, the designed back EMF detection circuit outputs a high level through the BEMF_Switch port of the MCU, causing the NMOS field-effect transistor Q1 to saturate and conduct. This subsequently leads to a voltage across R4 in the overvoltage protection circuit, causing transistor Q2 to saturate and conduct, while Q3 is cut off. This prevents energy from entering the subsequent kinetic energy recovery circuit, avoiding the kinetic energy recovery from pulling down the back EMF. The capacitor C1 has a very small capacitance, allowing the pulled-down back EMF to quickly recover and stabilize. At this point, an accurate back EMF can be obtained from the MCU's BEMF_Detect port. The detection time is only a few milliseconds, and kinetic energy recovery can resume immediately after detection, without affecting kinetic energy recovery or user experience. The advantages of this back EMF detection circuit compared to other implementations are:

[0042] First, by using a small-value capacitor for filtering, high-frequency noise can be effectively filtered out, reducing fluctuations in the estimated rotational speed. It can also avoid excessively long voltage stabilization time, which would cause a delay in the obtained rotational speed. Furthermore, the small size of the capacitor is beneficial for the miniaturization of the circuit.

[0043] Secondly, it utilizes devices in the overvoltage protection circuit. This circuit can control the PMOS in the overvoltage protection circuit to realize its function of turning off energy and entering kinetic energy recovery, saving one PMOS, realizing efficient utilization of components, and facilitating the miniaturization of the circuit.

[0044] Third, the addition of a high-performance MCU enables high-frequency, fast, and accurate back EMF detection. The MCU's main frequency reaches 72MHz, allowing for back EMF measurement within milliseconds, and its built-in algorithm enables accurate estimation of the permanent magnet synchronous motor's speed.

[0045] The overvoltage protection circuit includes resistors R4, R5, and R6, transistor Q2, a Zener diode ZD1, and a PMOS field-effect transistor Q3. Resistor R4 and Zener diode ZD1 are first connected in series, and then the two are connected in parallel to the DC bus. One end of resistor R5 is connected to the cathode of Zener diode ZD1, and the other end is connected to the base of transistor Q2. PMOS field-effect transistor Q3 is connected in series to the DC bus. One end of resistor R6 is connected to the gate of PMOS field-effect transistor Q3, and the other end is grounded. The emitter and collector of transistor Q2 are connected in parallel to the gate and source of PMOS field-effect transistor.

[0046] The rated voltage of Zener diode ZD1 is selected to be the maximum voltage that the subsequent stage current can withstand. When the voltage is lower than the rated voltage of the Zener diode, there is no voltage across resistor R4. At this time, transistor Q2 is not conducting, and the gate of PMOS MOSFET Q3 is connected to ground through resistor R6, so PMOS MOSFET Q3 conducts, and current can flow through PMOS MOSFET Q3 to the subsequent stage. When the voltage exceeds the rated voltage of Zener diode ZD1, there is voltage across resistor R4, transistor Q2 conducts, and the gate of PMOS MOSFET Q3 is connected to the DC bus through transistor Q2. PMOS MOSFET Q3 immediately turns off. The excessive voltage is prevented from flowing to the subsequent stage in microseconds, thus providing protection.

[0047] The high-voltage conversion circuit includes an integrated DC-DC chip U1, a resistor R7, a diode D7, an inductor L1, and two electrolytic capacitors C2 and C3. U1, model TX4144, is a monolithic step-down switch-mode converter with a built-in power MOSFET. The TX4144 supports a wide input power range of 6-60V and achieves a maximum output current of 1.5A.

[0048] The inductor L1, diode D7, and integrated DC-DC chip U1 are connected in the form of a Buck circuit. U1 integrates a high-voltage MOSFET and a voltage feedback circuit, which can automatically control the duty cycle of the Buck circuit based on the feedback voltage, thereby stabilizing the output voltage under high input voltage fluctuations. Electrolytic capacitors C2 and C3 are connected in parallel on the DC bus, located before U1 and after L1 respectively, to filter out the ripple before and after rectification, thus stabilizing the output voltage.

[0049] To further explain, such as Figure 3As shown, the charging switch and selection circuit comprises two parts: one part controls kinetic energy recovery, and the other part controls fast charging. It includes four resistors, two NMOS field-effect transistors, two PMOS field-effect transistors, an MCU, and a capacitor; the specific connections are as follows:

[0050] In the kinetic energy recovery section, resistors R1 and R2 form a voltage divider circuit, and the divided voltage is sent to the BEMF_Detect port of the MCU. A small capacitor C1 is connected in parallel with R2. This part is consistent with the previous section. Figure 2 The back EMF detection circuit in the MCU shares common components. PMOS field-effect transistor Q4 is connected in series with the DC bus; the gate of NMOS field-effect transistor Q5 is connected to the PMSM_Enable port of the MCU, the drain is connected to the gate of the PMOS field-effect transistor, and the source of the NMOS field-effect transistor is grounded.

[0051] In the fast charging section, two resistors R10 and R11 form a voltage divider circuit, and the divided voltage is sent to the TYPEC_Detect port of the MCU. The PMOS field-effect transistor Q6 is connected in series with the DC bus. The gate of the NMOS field-effect transistor Q7 is connected to the TYPEC_Enable port of the MCU, the drain is connected to the gate of the PMOS field-effect transistor Q6, and the source is grounded.

[0052] This lithium battery management system has two charging sources: external fast charging and kinetic energy recovery. This circuit is designed to ensure that only one charging source charges the lithium battery at a time, avoiding interference. When the user connects an external fast charger, kinetic energy recovery automatically shuts off, preventing the permanent magnet synchronous motor from generating resistance and achieving a superior user experience.

[0053] In addition, users can turn off kinetic energy recovery via a button, and the circuit will enable or disable kinetic energy recovery according to the user's settings.

[0054] This circuit uses an MCU to continuously monitor the voltage of two charging sources and intelligently selects the charging source based on the built-in logic.

[0055] When a voltage greater than 4V is detected at the TYPEC_Detect port of the MCU, it indicates that a charger is connected. At this time, the TYPEC_Enable port of the MCU outputs a high level, while the PMSM_Enable port outputs a low level, causing PMOS field-effect transistor Q4 to be turned off and PMOS field-effect transistor Q6 to be turned on, allowing only fast charging and turning off kinetic energy recovery.

[0056] When the MCU detects that the voltage on the BEMF_Detect port exceeds 4V, it indicates that the permanent magnet synchronous motor is generating electricity. At this time, the MCU enters the kinetic energy recovery charging mode and intelligently adjusts the intensity of kinetic energy recovery. The MCU's TYPEC_Enable port outputs a low level, the PMOS field-effect transistor Q6 is turned off, while the PMSM_Enable port outputs a PWM wave with a corresponding duty cycle based on the acquired speed, and the PMOS field-effect transistor Q4 is intermittently turned on, intelligently adjusting the intensity of kinetic energy recovery.

[0057] If there is voltage on both the TYPEC_Detect and BEMF_Detect ports, it indicates that the user is performing kinetic energy recovery and fast charging simultaneously. In this case, fast charging is prioritized, the TYPEC_Enable port outputs a high level, and the PMSM_Enable port outputs a low level, causing the PMOS field-effect transistor Q4 to be turned off and the PNMOS field-effect transistor Q5 to be turned on, allowing only fast charging and turning off kinetic energy recovery.

[0058] If the user turns off kinetic energy recovery via a button, the PMSM_Enable port outputs a low level, the PMOS field-effect transistor Q4 is turned off, and the kinetic energy recovery circuit is directly shut down.

[0059] Implementing the above logic using an MCU requires minimal components to achieve the control described above, which facilitates product miniaturization and reduces product failure rates. With a main frequency of up to 72MHz, the MCU can complete voltage detection for two channels and output the corresponding logic within microseconds, offering extremely high speed and excellent performance.

[0060] The aforementioned intelligent regulation circuit for recycling intensity consists of the back EMF detection circuit, overvoltage protection circuit, high withstand voltage conversion circuit, and charging switch and selection circuit described above.

[0061] To further explain, the external fast charging module includes a Type-C interface, a fast charging protocol handshake circuit, and a voltage conversion circuit, which are connected in sequence.

[0062] To further explain, the external discharge module includes an output voltage control circuit, a load overcurrent protection circuit, and a load, which are connected in sequence.

[0063] The output voltage control circuit comprises a DC-DC chip, an inductor, a diode, two resistors, and two capacitors. The DC-DC chip, model FP6291, is a current-mode boost DC-DC converter with a built-in MOSFET, a maximum withstand voltage of 16V, and built-in overcurrent, overvoltage, and overheat protection. The DC-DC chip, inductor, and diode are connected in a boost circuit configuration. The two resistors form a voltage divider circuit, connected in parallel to the output of the DC-DC chip, and send the divided voltage to the FB pin of the DC-DC chip. The DC-DC chip automatically maintains the FB port voltage at 0.6V. The output voltage of the DC-DC chip can be adjusted by changing the resistance value. The two capacitors, one before and one after the DC-DC chip, are used to rectify the output and maintain a stable output voltage.

[0064] The overcurrent protection circuit includes an MCU and two resistors. The two resistors form a voltage divider circuit connected to the output of the DC-DC chip, and the divided voltage is sent to the Vout_Detect terminal of the MCU. When the load is too large, the DC-DC chip will reduce the output voltage to maintain the current below the limit. At this time, the voltage on the Vout_Detect terminal of the MCU will decrease. By continuously monitoring the voltage at this port, the MCU detects an overcurrent when the output voltage is less than a preset value, and sends a control signal to the discharge switch circuit to shut off the external discharge.

[0065] This invention can be installed in various hand-operated devices, driving a permanent magnet synchronous motor via its wheels. When a user pushes the device equipped with this patent, the system automatically detects the user's pushing speed and matches the corresponding kinetic energy recovery intensity, converting kinetic energy into electrical energy stored in a lithium battery. When the user needs to use an external load, pressing a button selects the output voltage, and the system releases the previously stored electrical energy from the lithium battery at the specified voltage to power the load. When the load's power demand is high and the power converted from kinetic energy recovery is insufficient, the user can use the Type-C interface for external fast charging to quickly replenish the lithium battery.

[0066] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A lithium battery charging and discharging management system based on kinetic energy recovery, characterized in that, It includes a kinetic energy recovery and power generation module, an external fast charging module, a lithium battery management module, an external discharge module, and a user interaction module; The kinetic energy recovery power generation module and the external fast charging module are connected to the lithium battery management module through a charging switch and selection circuit. The lithium battery management module is connected to the external discharge module through a discharge switch circuit. The user interaction module inputs control signals to the charging switch and selection circuit, the discharge switch circuit and the external discharge module to realize human-computer interaction. The kinetic energy recovery power generation module includes a permanent magnet synchronous motor, a rectifier circuit, and a kinetic energy recovery intensity intelligent control circuit. The kinetic energy recovery intensity intelligent control circuit includes a back EMF detection circuit, an overvoltage protection circuit, and a high withstand voltage conversion circuit connected in sequence. The back EMF detection circuit is also connected to a microcontroller. The back EMF detection circuit includes three resistors, one NMOS field-effect transistor, and one capacitor. Two resistors are connected in series and then in parallel on the DC bus to form a voltage divider circuit, and one resistor serves as a current-limiting resistor. The capacitor is connected in parallel with the lower half of the resistors in the voltage divider circuit to form a filter circuit. The gate of the NMOS field-effect transistor is connected to the microcontroller through the current-limiting resistor, and the drain of the NMOS field-effect transistor is connected to the Zener diode of the overvoltage protection circuit. The overvoltage protection circuit includes three resistors, a Zener diode, a transistor, and a PMOS field-effect transistor. The high-voltage withstand voltage conversion circuit includes a DC-DC chip, a resistor, a diode, an inductor, and two electrolytic capacitors. The diode, inductor, and DC-DC chip are connected in the form of a Buck circuit. One electrolytic capacitor and the diode are connected in parallel across the two ends of the inductor. The other electrolytic capacitor is placed between the DC-DC chip and the DC bus. One end of the resistor is connected to the port of the DC-DC chip, and the other end is grounded.

2. The lithium battery charging and discharging management system according to claim 1, characterized in that, The external fast charging module includes a Type-C interface, a fast charging protocol handshake circuit, and a voltage conversion circuit connected in sequence.

3. The lithium battery charging and discharging management system according to claim 1, characterized in that, The user interaction module includes LED indicator lights and buttons. The LED indicator lights can provide battery power indication, kinetic energy recovery prompts and system fault warnings, while the buttons provide kinetic energy recovery switch and discharge voltage selection.

4. The lithium battery charging and discharging management system according to claim 1, characterized in that, The external discharge module includes an output voltage control circuit, a load overcurrent protection circuit, and a load connected in sequence.

5. The lithium battery charging and discharging management system according to claim 1, characterized in that, The charging switch and selection circuit consists of two parts: one part is used to control kinetic energy recovery, and the other part is used to control fast charging. Both parts include two resistors, one NMOS field-effect transistor, one PMOS field-effect transistor, one MCU, and one capacitor; the specific connections are as follows: Two resistors form a voltage divider circuit, and the divided voltage is sent to the microcontroller port. The PMOS field-effect transistor is connected in series with the DC bus. The gate of the NMOS field-effect transistor is connected to the microcontroller, the drain is connected to the gate of the PMOS field-effect transistor, and the source of the NMOS field-effect transistor is grounded.

6. The lithium battery charging and discharging management system according to claim 5, characterized in that, The section for controlling kinetic energy recovery also includes a capacitor, and the two resistors and capacitor that form the voltage divider circuit are shared with the back EMF detection circuit.

7. The lithium battery charging and discharging management system according to claim 6, characterized in that, The capacitance of the capacitor is 5uF.

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