A BBU charging circuit, control method, and storage system

Abstract

The present invention provides a BBU charging circuit, a control method, and a storage system, including: a left-bridge-arm MOS transistor unit, a right-bridge-arm MOS transistor unit, and an energy storage unit. The energy storage unit is connected between the left-bridge-arm MOS transistor unit and the right-bridge-arm MOS transistor unit. The input end of the left-bridge-arm MOS transistor unit is connected to a power supply, and the output end of the right-bridge-arm MOS transistor unit is connected to the input end of the BBU. The energy storage unit includes a first inductor L1 and a second inductor L2. The first inductor L1 and the second inductor L2 alternately charge and discharge as the left-bridge-arm MOS transistor unit and the right-bridge-arm MOS transistor unit are turned on or off. The currents flowing through the first inductor L1 and the second inductor L2 are superimposed to serve as the BBU charging current to charge the BBU.

Description

Technical Field

[0001] The present invention relates to the field of computers, and more particularly to a BBU charging circuit, a control method, and a storage system. Background Art

[0002] Currently, the storage systems in the industry usually adopt the main and standby redundant power supply of PSU+BBU. When the commercial power in the computer room is cut off, the storage system can seamlessly switch to the backup battery BBU for power supply when it detects the abnormal power supply of the PSU in real time. The BBU provides continuous power supply to ensure that the data in the write cache of the storage system controller is completely and safely written into non-volatile media such as HDDs and SSDs, avoiding data loss.

[0003] To ensure the business continuity of data storage, the BBU needs to have a long cycle life and reliable performance requirements. Current research has found that the charging current ripple will cause a high rise in battery temperature, and then affect the cycle life and overall performance of the battery. If the ripple is too large and the instantaneous valley value of the voltage ripple is lower than the open-circuit voltage of a single battery of the storage battery, the storage battery will discharge, and the storage battery will charge and discharge in cycles at the ripple frequency, accelerating the aging of the storage battery and affecting the health status and service life of the storage battery.

[0004] Currently, the storage system generally uses the PSU as the input, and charges the BBU through a switching power supply topology circuit. Since there is a power switch in the switching power supply topology circuit, which periodically charges and discharges the energy storage inductor, there is a ripple corresponding to the switching period. As the number of BBU charging times increases, the cycle life and reliable performance of the BBU will be severely affected. Summary of the Invention

[0005] In view of the above problems, the embodiments of the present invention provide a BBU charging circuit, a control method, and a storage system to overcome or at least partially solve the above problems.

[0006] In the first aspect of the embodiments of the present invention, a BBU charging circuit is provided, including: a left bridge arm MOS transistor unit, a right bridge arm MOS transistor unit, and an energy storage unit. The energy storage unit is connected between the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit. The input end of the left bridge arm MOS transistor unit is connected to a power supply, and the output end of the right bridge arm MOS transistor unit is connected to the input end of the BBU;

[0007] The left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit are controlled to be turned on or off by a PWM signal, where the signal is issued by a PWM controller;

[0008] The energy storage unit includes a first inductor L1 and a second inductor L2. The input ends of the first inductor L1 and the second inductor L2 are connected to the output end of the left bridge arm MOS transistor unit. The output ends of the first inductor L1 and the second inductor L2 are connected to the output end of the right bridge arm MOS transistor unit. The first inductor L1 and the second inductor L2 alternately charge and discharge as the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit conduct or turn off.

[0009] The currents flowing through the first inductor L1 and the second inductor L2 are superimposed as the BBU charging current to charge the BBU.

[0010] Optionally, it further includes a filtering unit. The filtering unit includes a first capacitor C1 and a second capacitor C2 for filtering the current in the charging circuit. Among them,

[0011] One end of the first capacitor C1 is connected to the input end of the power supply, and the other end is grounded.

[0012] One end of the second capacitor C2 is connected to the output end of the right bridge arm MOS transistor unit, and the other end is connected to the positive pole of the diode unit.

[0013] Optionally, it further includes a diode unit. The diode unit includes a first diode D1 and a second diode D2 for freewheeling the current flowing through the energy storage unit.

[0014] The left bridge arm MOS transistor unit includes a first MOS transistor Q1 and a second MOS transistor Q2.

[0015] The positive pole of the first diode D1 is connected to one end of the second capacitor C2, and the negative pole is connected to the source of the first MOS transistor Q1.

[0016] The positive pole of the second diode D2 is connected to one end of the second capacitor C2, and the negative pole is connected to the source of the second MOS transistor Q2.

[0017] Optionally, the right bridge arm MOS transistor unit includes a third MOS transistor Q3.

[0018] The PWM controller outputs corresponding signals to control the conduction and turn-off of the first MOS transistor Q1, the second MOS transistor Q2, and the third MOS transistor Q3, so that their conduction or turn-off forms different charging circuits.

[0019] The drain of the first MOS transistor Q1 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative pole of the first diode unit, and the gate is connected to the signal output end of the PWM controller.

[0020] The drain of the second MOS transistor Q2 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the second diode unit, and the gate is connected to the signal output end of the PWM controller;

[0021] The drain of the third MOS transistor Q3 is connected to the input end of the BBU, the source is connected to the output end of the energy storage unit, and the gate is connected to the signal output end of the PWM controller.

[0022] Optionally, the left bridge arm MOS transistor unit further includes a fourth MOS transistor Q4, the right bridge arm MOS transistor unit further includes a fifth MOS transistor Q5, a sixth MOS transistor Q6, and a seventh MOS transistor Q7, the energy storage unit further includes a third inductor L3, and the diode unit further includes a third diode D3 and a fourth diode D4;

[0023] The drain of the fourth MOS transistor Q4 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the third diode D3, and the gate is connected to the signal output end of the PWM controller;

[0024] The drain of the fifth MOS transistor Q5 is connected to the negative electrode of the constant voltage unit and the output end of the third inductor L3, the source is grounded, and the gate is connected to the signal output end of the PWM controller;

[0025] The drain of the sixth MOS transistor Q6 is connected to the source of the third MOS transistor Q3 and the output end of the second inductor L2, the source is grounded, and the gate is connected to the signal output end of the PWM controller;

[0026] The drain of the seventh MOS transistor Q7 is connected to the positive electrode of the fourth diode D4, the source is connected to the positive electrode of the constant voltage unit, and the gate is connected to the signal output end of the PWM controller;

[0027] The input end of the third inductor L3 is connected to the source of the fourth MOS transistor Q4 and the negative electrode of the third diode D3; the output end is connected to the drain of the fifth MOS transistor Q5 and the negative electrode of the constant voltage unit;

[0028] The negative electrode of the third diode D3 is connected to the source of the fourth MOS transistor Q4 and the input end of the third inductor L3, and the positive electrode is connected to one end of the second capacitor C2;

[0029] The negative electrode of the fourth diode D4 is connected to the output end of the right bridge arm MOS unit, the positive electrode is connected to the input end of the third inductor L3, and the positive electrode is connected to the drain of the seventh MOS transistor Q7.

[0030] Optionally, the constant voltage unit includes a constant voltage source for providing the constant voltage source to the BBU charging circuit;

[0031] The positive electrode of the constant voltage unit is connected to the source electrode of the seventh MOS transistor Q7, and the negative electrode is connected to the drain electrode of the fifth MOS transistor Q5 and the output end of the third inductor L3.

[0032] Optionally, the PWM controller issues a high-level signal to control the conduction of the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit, and a low-level signal to control the turn-off.

[0033] Optionally, the second capacitor C2 is used to store electrical energy.

[0034] In a second aspect of the embodiments of the present invention, a method for controlling a BBU charging circuit is provided. The method is applied to the BBU charging circuit for charging the BBU in the first aspect of the embodiments of the present invention, and the method includes:

[0035] Real-time detect the output voltage at the output end of the BBU. When the output voltage is greater than the power supply voltage, switch the BBU charging loop in the boost mode to charge the BBU.

[0036] In a third aspect of the embodiments of the present invention, a storage system is provided. The storage system uses the control method described in the second aspect of the present invention to charge the BBU with the BBU charging circuit in the first aspect of the embodiments.

[0037] The BBU charging circuit provided by the embodiments of the present invention includes: a left bridge arm MOS transistor unit, a right bridge arm MOS transistor unit, and an energy storage unit. The energy storage unit is connected between the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit. The input end of the left bridge arm MOS transistor unit is connected to the power supply, and the output end of the right bridge arm MOS transistor unit is connected to the input end of the BBU; the PWM controller issues a signal to control the conduction or turn-off of the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit. The input ends of the first inductor L1 and the second inductor L2 are connected to the output end of the left bridge arm MOS transistor unit, and the output ends of the first inductor L1 and the second inductor L2 are connected to the output end of the right bridge arm MOS transistor unit. The first inductor L1 and the second inductor L2 are alternately charged and discharged as the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit are conducted or turned off; the current flowing through the first inductor L1 and the current flowing through the second inductor L2 are superimposed as the BBU charging current to charge the BBU.

[0038] The BBU is charged by a BBU charging circuit provided by the present invention. By controlling the conduction and cutoff of different MOS transistors through PWM, it is possible to use the superposition of two inductor currents as the output current to charge the BBU, canceling out the AC components of the inductor currents, avoiding output ripple caused by periodically charging and discharging the energy storage inductor, and thus optimizing the BBU charging method. According to the superposition of different inductor currents flowing through the charging circuit, a nearly ripple-free constant direct current with the AC components of the inductor currents canceled out is obtained to charge the BBU, that is, it is possible to achieve extremely low ripple output, charge the BBU with low ripple and high efficiency, improve the reliable performance of the BBU, slow down the aging of the storage battery, and extend the health state and service life of the storage battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0040] Figure 1 is a schematic diagram of a BBU charging circuit according to an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of the current flow direction of a BBU charging circuit according to an embodiment of the present invention in the first operating state of the Buck mode;

[0042] Figure 3 is a schematic diagram of the current flow direction of a BBU charging circuit according to an embodiment of the present invention in the second operating state of the Buck mode;

[0043] Figure 4 is a schematic diagram of the inductor current and output current waveforms of a BBU charging circuit according to an embodiment of the present invention;

[0044] Figure 5 is a schematic diagram of the current flow direction of a BBU charging circuit according to an embodiment of the present invention in the first operating state of the Boost mode;

[0045] Figure 6 is a schematic diagram of the inductor current and output current waveforms of a BBU charging circuit according to an embodiment of the present invention in the Boost mode;

[0046] Figure 7 is a schematic diagram of the current flow direction of a BBU charging circuit according to an embodiment of the present invention in the second operating state of the Boost mode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] To make the above objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, which is only a part of the embodiments of the present invention, rather than all the embodiments, and are not used to limit the present invention.

[0048] The applicant's research found that the charging current ripple will cause a high rise in battery temperature, and then affect the battery's cycle life and overall performance. If the ripple is too large, when the instantaneous valley value of the voltage ripple is lower than the open-circuit voltage of a single battery of the battery, it will cause the battery to discharge. The battery will charge and discharge in a cycle at the ripple frequency, accelerating the aging of the battery, affecting the health state and service life of the battery. Therefore, how to reduce the current ripple in the charging current is an urgent problem to be solved.

[0049] In view of the above problems, the inventor creatively proposed a BBU charging circuit, control method, and storage system of the present invention, which preferably solved the above problems. The BBU charging circuit of the present invention will be described below.

[0050] The embodiment of the present invention provides a BBU charging circuit, including: a left bridge arm MOS transistor unit, a right bridge arm MOS transistor unit, and an energy storage unit. The energy storage unit is connected between the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit. The input end of the left bridge arm MOS transistor unit is connected to a power supply, and the output end of the right bridge arm MOS transistor unit is connected to the input end of the BBU; the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit are controlled to conduct or turn off by a PWM signal, and the signal is issued by a PWM controller; the energy storage unit includes a first inductor L1 and a second inductor L2. The input end of the first inductor L1 and the input end of the second inductor L2 are connected to the output end of the left bridge arm MOS transistor unit, and the output end of the first inductor L1 and the output end of the second inductor L2 are connected to the output end of the right bridge arm MOS transistor unit. The first inductor L1 and the second inductor L2 alternately charge and discharge with the conduction or turn-off of the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit; the current flowing through the first inductor L1 and the current flowing through the second inductor L2 are superimposed as the BBU charging current to charge the BBU.

[0051] In this embodiment, by connecting the components inside the left bridge arm MOS transistor unit, the right bridge arm MOS transistor unit, and the energy storage unit, and issuing corresponding signals through the PWM controller to control the MOS transistors in the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit to conduct or turn off to form different circuits for charging the BBU to charge the BBU. In the BBU charging circuit of the present invention, refer to Figure 1 ,Figure 1 It is a schematic diagram of a BBU charging circuit provided by an embodiment of the present invention. The left-bridge-arm MOS transistor unit includes three N-channel power first MOS transistors Q1, Q2, and Q4. The right-bridge-arm MOS transistor unit includes four N-channel power third MOS transistors Q3, Q5, Q6, and Q7. The energy storage unit includes three power inductors, namely the first inductor L1, the second inductor L2, and the third inductor L3. The diode unit includes three freewheeling diodes, namely the first diode D1, the second diode D2, and the third diode D3, and an anti-backflow diode, i.e., the fourth diode D4. The constant voltage unit is U1. The filtering unit includes the first capacitor C1 and the second capacitor C2. The source electrodes of the left-bridge-arm MOS transistor unit are connected to the negative electrodes of the freewheeling diode unit. The drain electrodes of the left-bridge-arm MOS transistors are connected to PSU_12V, i.e., the power supply. The source electrode of the third MOS transistor Q3 is connected to the drain electrode of the sixth MOS transistor Q6. The drain electrode of the third MOS transistor Q3 is connected to the power supply output. The source electrode of the seventh MOS transistor Q7 in the right-bridge-arm MOS transistor unit is connected to the positive electrode of the constant voltage source U1. The drain electrode of the seventh MOS transistor Q7 is connected to the positive electrode of the fourth diode D4. The negative electrodes of the three freewheeling diodes are connected to the power supply output. The source electrodes of the fifth MOS transistor Q5 and the sixth MOS transistor Q6 are connected to GND. The three power inductors are connected to the left- and right-bridge-arm MOS transistor units.

[0052] The BBU charging circuit provided by this embodiment can form two charging circuit modes to charge the BBU. The two modes are the Buck (step-down) mode and the Boost (step-up) mode. Among them, the Buck (step-down) mode is divided into Buck operating state 1 and Buck operating state 2, and the Boost (step-up) mode is also divided into Boost operating state 1 and Boost operating state 2. In the Buck (step-down) mode, by controlling the conduction and cutoff of different MOS transistors, the first inductor L1 and the second inductor L2 can be alternately charged and discharged periodically, and the current flowing through the first inductor L1 and the current flowing through the second inductor L2 are superimposed. Then, the superimposed current is output through the right-bridge-arm MOS transistor unit as the BBU charging current to charge the BBU. When operating in the Boost (step-up) mode, similarly, by controlling the conduction and cutoff of different MOS transistors, the third inductor L3 and the second inductor L2 are alternately charged and discharged periodically, and the current flowing through the third inductor L3 and the current flowing through the second inductor L2 are superimposed. Then, the superimposed current is output through the right-bridge-arm MOS transistor unit as the BBU charging current to charge the BBU. By superimposing the above currents, the AC components of the inductor currents, i.e., the current ripple, can be mutually offset, so that the output current has a very small ripple current to charge the BBU.

[0053] In one embodiment, it further includes: a filtering unit, which includes a first capacitor C1 and a second capacitor C2 and is used for filtering the current in the charging circuit; wherein, one end of the first capacitor C1 is connected to the input end of the power supply, and the other end is grounded; one end of the second capacitor C2 is connected to the output end of the right-bridge-arm MOS transistor unit, and the other end is connected to the positive electrode of the diode unit.

[0054] In this embodiment, the BBU charging circuit further includes a filtering unit for filtering the current in the BBU charging circuit. One end of the first capacitor C1 is connected to the input end of the power supply, and the other end is grounded; one end of the second capacitor C2 is connected to the output end of the right-bridge-arm MOS transistor unit, and the other end is connected to the positive electrode of the diode unit. The first capacitor C1 is used for filtering the input current of the BBU charging circuit, and the second capacitor C2 is used for filtering the output current of the BBU charging circuit.

[0055] In one embodiment, it further includes a diode unit, which includes: a first diode D1 and a second diode D2 and is used for freewheeling the current flowing through the energy storage unit; the left-bridge-arm MOS transistor unit includes: a first MOS transistor Q1 and a second MOS transistor Q2; the positive electrode of the first diode D1 is connected to one end of the second capacitor C2, and the negative electrode is connected to the source electrode of the first MOS transistor Q1; the positive electrode of the second diode D2 is connected to one end of the second capacitor C2, and the negative electrode is connected to the source electrode of the second MOS transistor Q2.

[0056] In this embodiment, the BBU charging circuit further includes a diode unit, which is used for freewheeling the current flowing through the energy storage unit and discharging the remaining electric energy in the energy storage unit when charging the BBU. The first diode D1 is used for discharging the remaining electric energy in the first inductor L1 in the Buck mode, and the second diode D2 is used for discharging the remaining electric energy in the second inductor L2 in the Buck mode or the Boost mode.

[0057] In one embodiment, the right-bridge-arm MOS transistor unit includes: a third MOS transistor Q3; the PWM controller outputs corresponding signals to control the conduction and cutoff of the first MOS transistor Q1, the second MOS transistor Q2, and the third MOS transistor Q3, so that their conduction or cutoff forms different charging circuits; the drain of the first MOS transistor Q1 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the first diode unit, and the gate is connected to the signal output end of the PWM controller; the drain of the second MOS transistor Q2 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the second diode unit, and the gate is connected to the signal output end of the PWM controller; the drain of the third MOS transistor Q3 is connected to the input end of the BBU, the source is connected to the output end of the energy storage unit, and the gate is connected to the signal output end of the PWM controller.

[0058] In this embodiment, the PWM controller outputs a high-level PWM1 signal to control the conduction of the first MOS transistor Q1, and a low-level PWM1 signal to control the cutoff of the first MOS transistor Q1. The PWM controller outputs a high-level PWM2 signal to control the conduction of the second MOS transistor Q2, and a low-level PWM2 signal to control the conduction of the second MOS transistor Q2. The PWM controller outputs a high-level PWM3 signal to control the conduction of the third MOS transistor Q3, and a low-level PWM3 signal to control the conduction of the third MOS transistor Q3. Different signals can be sent according to different requirements to control the conduction and cutoff of the corresponding MOS transistors, so as to form different charging mode circuits to charge the BBU. By applying a high-level or low-level signal output by the PWM controller to the gate of the MOS transistor, its conduction or cutoff can be controlled.

[0059] In one embodiment, the left-bridge-arm MOS transistor unit further includes a fourth MOS transistor Q4, the right-bridge-arm MOS transistor unit further includes a fifth MOS transistor Q5, a sixth MOS transistor Q6, and a seventh MOS transistor Q7, the energy storage unit further includes a third inductor L3, and the diode unit further includes a third diode D3 and a fourth diode D4; the drain of the fourth MOS transistor Q4 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the third diode D3, and the gate is connected to the signal output end of the PWM controller; the drain of the fifth MOS transistor Q5 is connected to the negative electrode of the constant voltage unit and the output end of the third inductor L3, the source is grounded, and the gate is connected to the signal output end of the PWM controller; the drain of the sixth MOS transistor Q6 is connected to the source of the third MOS transistor Q3 and the output end of the second inductor L2, the source is grounded, and the gate is connected to the signal output end of the PWM controller; the drain of the seventh MOS transistor Q7 is connected to the positive electrode of the fourth diode D4, the source is connected to the positive electrode of the constant voltage unit, and the gate is connected to the signal output end of the PWM controller; the input end of the third inductor L3 is connected to the source of the fourth MOS transistor Q4 and the negative electrode of the third diode D3; the output end is connected to the drain of the fifth MOS transistor Q5 and the negative electrode of the constant voltage unit; the negative electrode of the third diode D3 is connected to the source of the fourth MOS transistor Q4 and the input end of the third inductor L3, and the positive electrode is connected to one end of the second capacitor C2; the negative electrode of the fourth diode D4 is connected to the output end of the right-bridge-arm MOS unit, and the positive electrode is connected to the input end of the third inductor L3 and the drain of the seventh MOS transistor Q7.

[0060] In this embodiment, by adding the above-mentioned components and the connection relationships of the above-mentioned components in the charging circuit of the BBU, in addition to forming a Buck-mode BBU charging circuit, a Boost-mode BBU charging circuit can also be formed. Because when charging the BBU in the Buck-mode BBU charging circuit, only the case where the output voltage is less than the power supply voltage can be satisfied, and the case where the output voltage is greater than the power supply voltage cannot be satisfied. By adding the above-mentioned components and correctly connecting the components, the mode where the output voltage is greater than the power supply voltage, that is, the Boost mode, can be achieved. In this mode, the third inductor L3 and the second inductor L2 can be alternately charged and discharged periodically, and the current flowing through the third inductor L3 and the current flowing through the second inductor L2 can be superimposed, and then the superimposed current is output through the right-bridge-arm MOS transistor unit as the BBU charging current to charge the BBU.

[0061] In one embodiment, the constant voltage unit includes a constant voltage source for providing the constant voltage source to the BBU charging circuit; the positive electrode of the constant voltage unit is connected to the source electrode of the seventh MOS transistor Q7, and the negative electrode is connected to the drain electrode of the fifth MOS transistor Q5 and the output end of the third inductor L3.

[0062] In this embodiment, a BBU charging circuit in Boost mode also requires a constant power supply. Since it is necessary to ensure that the voltage at the input end of the third inductor L3 is greater than the voltage at the output end to linearly increase the current on the inductor L3, a constant voltage source is provided. The positive electrode of the constant voltage unit is connected to the source electrode of the seventh MOS transistor Q7, and the negative electrode is connected to the drain electrode of the fifth MOS transistor Q5 and the output end of the third inductor L3. In this case, it can be ensured that the current on the second inductor L2 linearly decreases, and the current on the inductor L3 linearly increases, so as to realize a stable voltage with extremely small output current ripple after current superposition to charge the BBU.

[0063] In one embodiment, the PWM controller issues a high-level signal to control the conduction of the left-bridge MOS transistor unit and the right-bridge MOS transistor unit, and a low-level signal to control the turn-off.

[0064] In this embodiment, the PWM controller issues a high-level signal to control the conduction of the MOS transistors in the left-bridge MOS transistor unit and the right-bridge MOS transistor unit, and a low-level signal to control the turn-off of the MOS transistors. Different charging circuits can be formed by controlling the conduction and turn-off of different MOS transistors.

[0065] In one embodiment, the second capacitor C2 is used to store electrical energy.

[0066] In this embodiment, when in Buck mode and Boost mode, current will flow through the second capacitor C2, and the second capacitor C2 will store energy. In Boost mode, it releases electrical energy to charge the BBU.

[0067] The following will give a detailed description in combination with the specific BBU charging circuit embodiments provided by the present invention:

[0068] First, when it is known that the power of the BBU has not reached the threshold for charging, the BBU is charged. The power supply voltage in the embodiment of the present invention is 12V, and the BBU is a 4S3P battery pack. The output voltage of the battery BBU is detected in real time through the battery management system. When it is detected that the output voltage of the BBU is less than 12V, the charging circuit operates in the Buck mode. At this time, the PWM controller outputs PWM3 to maintain a high level and acts on the gate of the third MOS transistor, causing the third MOS transistor Q3 to conduct. The PWM controller outputs PWM4, PWM5, PWM6, and PWM7 to maintain a low level, respectively acting on the fourth MOS transistor Q4, the fifth MOS transistor Q5, the sixth MOS transistor Q6, and the seventh MOS transistor Q7 to turn off. The PWM controller adjusts the output voltage by adjusting the conduction duty cycles of PWM1 and PWM2, that is, the conduction times of the corresponding first MOS transistor Q1 and the second MOS transistor Q2 in Buck operating state 1 and Buck operating state 2, to output a very small ripple stable voltage to charge the BBU.

[0069] When in Buck operating state 1, refer to Figure 2 , Figure 2 is a schematic diagram of the current flow direction of a BBU charging circuit in the first operating state of the Buck mode in the embodiment of the present invention. In this state, PWM2 is in a low level state, and PWM1 is in a high level state. At this time, the second MOS transistor Q2 is turned off, and the first MOS transistor Q1 is turned on. The PSU_12V power supply current flows through the first MOS transistor Q1, the first inductor L1, the third MOS transistor Q3, the second capacitor C2, and the first capacitor C1 in sequence. The current on the first inductor L1 linearly increases to store electrical energy, and the current flow direction is as shown by the dotted line below the first inductor L1 in Figure 3 ; the electrical energy stored in the second inductor L2 continues to flow through the third MOS transistor Q3, the capacitor C2, and the diode D2, and the current on the inductor L2 linearly decreases to release electrical energy, and the current flow direction is as shown by the dotted line below the second inductor L2 in Figure 3 . The PWM controller adjusts the output voltage by adjusting the duty cycles of PWM1 and PWM2. Since the output voltage is not much different from the input voltage, the conduction duty cycle of PWM1 is maintained at a relatively high level, that is, in the Buck mode, it is in operating state 1 for a long time. In this state, the mathematical expressions of the currents on the first inductor L1 and the second inductor L2 are as follows:

[0070]

[0071]

[0072] where T1 is the conduction time of the first MOS transistor Q1 and also the turn-off time of the second MOS transistor Q2, and ΔI L1 is the current ripple of the first inductor L1; ΔI L2is the current ripple of the first inductor L1; Vout is the output voltage of the BBU charging circuit and also the input voltage of the BBU, and PSU_12V is the power supply voltage.

[0073] When in the second Buck operating state, refer to Figure 3 , Figure 3 is a schematic diagram of the current flow direction of a BBU charging circuit in the second Buck mode operating state according to an embodiment of the present invention. In this state, PWM1 is in the low level state and PWM2 is in the high level state. At this time, the first MOS transistor Q1 is turned off and the second MOS transistor Q2 is turned on. The PSU_12V power supply current flows through the second MOS transistor Q2, the second inductor L2, the third MOS transistor Q3, the second capacitor C2, and the first capacitor C1 in sequence. The current on the second inductor L2 linearly increases to store electrical energy, and the current flow direction is as shown by the dotted line below the second inductor L2 in Figure 4 ; the electrical energy stored in the first inductor L1 is freewheeled through the third MOS transistor Q3, the second capacitor C2, and the first diode D1, and the current on the inductor L1 linearly decreases to release electrical energy, and the current flow direction is as shown by the dotted line below the first inductor L1 in Figure 3 . The PWM controller adjusts the output voltage by adjusting the duty cycles of PWM1 and PWM2. In this state, the mathematical expressions of the currents on the first inductor L1 and the second inductor L2 are as follows:

[0074]

[0075]

[0076] where T2 is the turn-off time of the first MOS transistor Q1 and also the turn-on time of the second MOS transistor Q2; ΔI L1 is the current ripple of the first inductor L1; ΔI L2 is the current ripple of the first inductor L1; Vout is the output voltage of the BBU charging circuit and also the input voltage of the BBU, and PSU_12V is the power supply voltage.

[0077] Through the charging circuit in the Buck mode, the currents on the first inductor L1 and the second inductor L2 can be calculated by the above calculation formulas in the above two modes. Refer to Figure 4 , Figure 4This is a schematic diagram of the inductor current and output current waveforms of a BBU charging circuit in the Buck mode according to an embodiment of the present invention. In the figure, the abscissa is time and the ordinate is the magnitude of the current ripple. Taking the first peak in the figure as an example, the top current waveform in the figure is the current of inductor L1, the middle is the current of inductor L2, and the bottom is the output current in this mode. The output current in this mode is the superposition of the currents on the first inductor L1 and the second inductor L2. The superposed current is the output current. In the superposition, the AC components of the inductor currents can cancel each other out, and the output current is approximately a constant DC without ripple, thereby realizing a very small ripple output of the BBU charging circuit in the Buck mode.

[0078] During the charging process, the output voltage of the BBU will continuously increase. When the duty cycle of the corresponding MOS transistor in the Buck mode is turned to the maximum and still cannot meet the voltage requirement of the BBU, that is, when the battery management system detects the output voltage of the battery BBU in real time, that is, when it is detected that the output voltage of the BBU is greater than 12V, the Buck mode at this time cannot meet the charging voltage requirement of the BBU, so the working mode of the charging circuit is switched to the Boost mode.

[0079] When in the Boost operating state 1, refer to Figure 5 , Figure 5 This is a schematic diagram of the current flow of a BBU charging circuit in the Boost mode operating state 1 according to an embodiment of the present invention. In this state, the signals PWM4, PWM3, and PWM7 issued by the PWM control room are in the high level state, PWM5 and PWM6 are in the low level state, the second MOS transistor Q2, the third MOS transistor Q3, the fourth MOS transistor Q4, and the seventh MOS transistor Q7 are turned on, and the fifth MOS transistor Q5 and the sixth MOS transistor Q6 are turned off. The second inductor L2 has been fully charged with energy in the Boost mode operating state 2, and the third inductor L3 has discharged and released all the energy in the Boost mode operating state 2. The PSU_12V power supply current flows through the second MOS transistor Q2, the second inductor L2, the third MOS transistor Q3, the second capacitor C2, and the first capacitor C1 in sequence. At this time, the second inductor L2 releases energy through the third MOS transistor Q3. At this time, the energy required by the BBU is provided by the PSU and the second inductor L2. The current on the inductor L2 linearly decreases to release electrical energy, and the current flow is as shown by the dotted line under the second inductor L2 in Figure 5 ; At the same time, the PSU_12V power supply current flows through the fourth MOS transistor Q4, the third inductor L3, the constant voltage unit U1, the seventh MOS transistor Q7, the second capacitor C2, and the first capacitor C1 in sequence. The current on the third inductor L3 linearly increases to store electrical energy, and the current flow is as shown by Figure 5as shown by the dashed line under the third inductor L3; the PWM controller adjusts the output voltage by adjusting the duty cycles of PWM2, PWM3, PWM4, PWM5, PWM6, and PWM7, so that the output voltage of the BBU charging circuit is maintained in a stable state. In this mode, ignoring the diode voltage drop, the mathematical expressions of the currents on the second inductor L2 and the third inductor L3 are as follows:

[0080]

[0081]

[0082] T3 represents the PWM signal drive conduction time of the second MOS transistor Q2, the third MOS transistor Q3, the fourth MOS transistor Q4, and the seventh MOS transistor Q7; ΔI L2 is the current ripple of the first inductor L1, and ΔI L3 is the current ripple of the third inductor L3; Vout is the output voltage of the BBU charging circuit and also the input voltage of the BBU, PSU_12V is the power supply voltage, and U1 is the voltage of the constant voltage source.

[0083] In Boost mode, Vout is greater than PSU_12V. The current on the inductor L2 linearly decreases. By setting the magnitude of the constant voltage source U1, the current on the third inductor L3 linearly increases, so that Vout - U1 is less than PSU_12V. Here, the magnitude of the constant voltage source U1 can be set according to the requirements of the actual circuit and is not specifically limited.

[0084] Through the charging circuit in the Boost mode operating state, the currents on the second inductor L2 and the third inductor L3 can be calculated. Refer to Figure 6 , Figure 6 is a schematic diagram of the inductor current and output current waveforms of a BBU charging circuit in Boost mode in an embodiment of the present invention. In the figure, the abscissa is time and the ordinate is the magnitude of the current ripple. Taking the first peak appearing in the figure as an example, the top current waveform in the figure is the current of the second inductor L2, the middle is the current of the third inductor L3, and the bottom is the output current in this mode. The output current in this mode is the superposition of the currents on the second inductor L2 and the third inductor L3. The output current is the superposed current. In the superposition, the AC components of the inductor currents can cancel each other out, and the output current is approximately a constant direct current without ripple, thereby realizing a very small ripple output of the BBU charging circuit in Boost mode.

[0085] Since it is necessary to ensure the normal operation of Boost mode working state 1, it is necessary to discharge the electric energy stored in the third inductor L3 to prepare for charging the BBU using Boost mode working state 1 next time. Therefore, it is necessary to use Boost mode working state 2 to charge the BBU.

[0086] When in Boost working state 2, refer to Figure 7 , Figure 7 is a schematic diagram of the current flow of a BBU charging circuit according to an embodiment of the present invention in Boost mode working state 2. In this state, PWM4, PWM3, and PWM7 emitted by the PWM controller are in the low level state, and PWM5 and PWM6 are in the high level state. At this time, the third MOS transistor Q3, the fourth MOS transistor Q4, and the seventh MOS transistor Q7 are turned off, and the second MOS transistor Q2, the fifth MOS transistor Q5, and the sixth MOS transistor Q6 are turned on. In this state, the PSU_12V power supply current flows to the second MOS transistor Q2, the second inductor L2, and the third MOS transistor Q6. The PSU_12V charges the second inductor L2, and the current on the inductor L2 linearly increases for energy storage. The current flow is as shown by the dotted line below the second inductor L2 in Figure 7 . At the same time, the third inductor L3 conducts freewheeling through the fifth MOS transistor Q5 and the third diode D3, and the current on L3 linearly decreases to release electric energy. The current flow is as shown by the dotted line below the third inductor L3 in Figure 7 . Since the charging current of the BBU cannot be interrupted, in this mode, the charging current of the BBU is temporarily provided by the capacitor C2. The current flow is as shown by the dotted line beside the second capacitor C2 in Figure 7 .

[0087] Through the BBU charging circuit provided by the present invention, in Buck and Boost modes, it can be controlled to use the superposition of two inductor currents as the output current, cancel the AC components of the inductor currents with each other, avoid the output ripple caused by periodically charging and discharging the energy storage inductor, thereby optimizing the BBU charging method, slowing down the aging of the storage battery, and extending the health state and service life of the storage battery.

[0088] In the second aspect of an embodiment, a method for controlling a BBU charging circuit is provided. The method is applied to the BBU charging circuit for charging the BBU described in the first aspect of the embodiment of the present invention. The method includes: real-time detecting the output voltage at the output end of the BBU, and when the output voltage is greater than the power supply voltage, switching the BBU charging loop in boost mode to charge the BBU.

[0089] In this embodiment, the output voltage of the battery BBU is detected in real time by the battery management system. When it is detected that the output voltage of the BBU is less than 12V, the charging circuit operates in the Buck mode. As the output voltage of the BBU continues to increase, when the duty cycle of the corresponding MOS transistor in the Buck mode reaches the maximum and still cannot meet the voltage requirement of the BBU, the operating mode of the charging circuit is switched to the Boost mode. That is, when it is detected in real time that the output voltage at the output end of the BBU is greater than 12V (where 12V is the power supply voltage), the charging circuit in the boost mode is switched to charge the BBU. The boost mode is the Boost mode, and only at this time can the charging requirement of the BBU be met.

[0090] In the third aspect of an embodiment, the third aspect of the embodiments of the present invention provides a storage system, and the storage system uses the control method described in the second aspect of the present invention to charge the BBU through the BBU charging circuit in the first aspect of the embodiment.

[0091] In summary, the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. The present invention can be used not only in the fields of computer, storage system power supply systems, but also in the field of new energy battery management such as electric vehicles, improving battery charging management, delaying the decline and aging of battery packs, extending the service life of battery packs, and reducing the maintenance cost of battery packs.

[0092] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of methods, devices, electronic devices, and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a device for implementing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0093] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device implements the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable terminal device provide for implementing the process Figure 1 in one process or multiple processes and / or blocks Figure 1 steps of the functions specified in one block or multiple blocks.

[0095] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

[0096] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of another identical element in the process, method, article or terminal device comprising the element.

[0097] The above has introduced in detail a BBU charging circuit, control method, and storage system provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A BBU charging circuit, characterized in that, It includes: A left bridge arm MOS transistor unit, a right bridge arm MOS transistor unit, a diode unit, an energy storage unit, and a filtering unit. The energy storage unit is connected between the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit. The input end of the left bridge arm MOS transistor unit is connected to a power supply, and the output end of the right bridge arm MOS transistor unit is connected to the input end of the BBU; The left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit are controlled to conduct or turn off by a PWM signal, and the signal is sent by a PWM controller; the filtering unit includes a first capacitor C1 and a second capacitor C2; The energy storage unit includes a first inductor L1 and a second inductor L2. The input ends of the first inductor L1 and the second inductor L2 are connected to the output end of the left bridge arm MOS transistor unit. The output ends of the first inductor L1 and the second inductor L2 are connected to the output end of the right bridge arm MOS transistor unit. The first inductor L1 and the second inductor L2 alternately charge and discharge with the conduction or turn-off of the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit; The currents flowing through the first inductor L1 and the second inductor L2 are superimposed to be used as the BBU charging current to charge the BBU; Among them, the right bridge arm MOS transistor unit includes: a third MOS transistor Q3; the left bridge arm MOS transistor unit includes a fourth MOS transistor Q4. The right bridge arm MOS transistor unit further includes a fifth MOS transistor Q5, a sixth MOS transistor Q6, and a seventh MOS transistor Q7. The energy storage unit further includes a third inductor L3. The diode unit includes a third diode D3 and a fourth diode D4; The drain of the fourth MOS transistor Q4 is connected to the power supply, the source is connected to the input end of the energy storage unit and the negative electrode of the third diode D3, and the gate is connected to the signal output end of the PWM controller; The drain of the fifth MOS transistor Q5 is connected to the negative electrode of the constant voltage unit and the output end of the third inductor L3, the source is grounded, and the gate is connected to the signal output end of the PWM controller; The drain of the sixth MOS transistor Q6 is connected to the source of the third MOS transistor Q3 and the output end of the second inductor L2, the source is grounded, and the gate is connected to the signal output end of the PWM controller; The drain of the seventh MOS transistor Q7 is connected to the positive electrode of the fourth diode D4, the source is connected to the positive electrode of the constant voltage unit, and the gate is connected to the signal output end of the PWM controller; The input end of the third inductor L3 is connected to the source of the fourth MOS transistor Q4 and the negative electrode of the third diode D3, and the output end is connected to the drain of the fifth MOS transistor Q5 and the negative electrode of the constant voltage unit; The negative electrode of the third diode D3 is connected to the source of the fourth MOS transistor Q4 and the input end of the third inductor L3, and the positive electrode is connected to one end of the second capacitor C2; The negative electrode of the fourth diode D4 is connected to the output terminal of the right bridge arm MOS unit, the positive electrode is connected to the input terminal of the third inductor L3, and the positive electrode is connected to the drain of the seventh MOS transistor Q7; The constant voltage unit includes a constant voltage source for providing the constant voltage source to the BBU charging circuit; The positive electrode of the constant voltage unit is connected to the source of the seventh MOS transistor Q7, and the negative electrode is connected to the drain of the fifth MOS transistor Q5 and the output terminal of the third inductor L3.

2. The BBU charging circuit according to claim 1, wherein One end of the second capacitor C2 is connected to the output terminal of the right bridge arm MOS transistor unit, and the other end is connected to the positive electrode of the diode unit.

3. The BBU charging circuit according to claim 2, characterized in that, It further includes a diode unit, and the diode unit further includes: a first diode D1 and a second diode D2 for freewheeling the current flowing through the energy storage unit; The left bridge arm MOS transistor unit further includes: a first MOS transistor Q1 and a second MOS transistor Q2; The positive electrode of the first diode D1 is connected to one end of the second capacitor C2, and the negative electrode is connected to the source of the first MOS transistor Q1; The positive electrode of the second diode D2 is connected to one end of the second capacitor C2, and the negative electrode is connected to the source of the second MOS transistor Q2.

4. The BBU charging circuit according to claim 3, wherein The corresponding signals are output by the PWM controller to control the conduction and cut-off of the first MOS transistor Q1, the second MOS transistor Q2, and the third MOS transistor Q3, and their conduction or cut-off forms different charging circuits; The drain of the first MOS transistor Q1 is connected to the power supply, the source is connected to the input terminal of the energy storage unit and the negative electrode of the first diode unit, and the gate is connected to the signal output terminal of the PWM controller; The drain of the second MOS transistor Q2 is connected to the power supply, the source is connected to the input terminal of the energy storage unit and the negative electrode of the second diode unit, and the gate is connected to the signal output terminal of the PWM controller; The drain of the third MOS transistor Q3 is connected to the input terminal of the BBU, the source is connected to the output terminal of the energy storage unit, and the gate is connected to the signal output terminal of the PWM controller.

5. The BBU charging circuit according to claim 1, wherein The PWM controller issues a high-level signal to control the conduction of the left bridge arm MOS transistor unit and the right bridge arm MOS transistor unit, and a low-level signal to control the cut-off.

6. The BBU charging circuit according to claim 1, wherein The second capacitor C2 is used for storing electrical energy.

7. A control method for a BBU charging circuit, characterized in that The method is applied to the BBU charging circuit for charging the BBU according to any one of claims 1-6, and the method includes: Real-time detecting the output voltage at the output terminal of the BBU, and when the output voltage is greater than the power supply voltage, switching the BBU charging circuit in the boost mode to charge the BBU.

8. A storage system, characterized in that, The storage system uses the BBU charging circuit according to any one of claims 1-6 to charge the BBU.

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