Voltage-doubling rectification cascade lithium battery equalizer and hybrid half-bridge control method

Abstract

The invention discloses a voltage-doubling rectification cascade lithium battery equalizer and a hybrid half-bridge control method. The equalizer comprises a half-bridge inverter, a buffer inductor, a multi-winding transformer, a cascade voltage-doubling rectifier and a series battery pack. According to the invention, a half-bridge inverter and passive diodes with the same number of battery units are adopted. The equalization charger comprises two operation modes, namely an external power supply equalization mode and a battery pack self-power-supply equalization mode, and the equalizer mode is switched through a relay of a single-pole double-throw switch. By adopting a hybrid half-bridge control strategy, the increase of equalizer topology is avoided, the cost of the equalizer is reduced, and a driving signal of a half-bridge inverter switch in the equalizer is determined through an extreme value of a battery voltage difference between an odd number group and an even number group and a difference value between minimum battery monomer voltages in the odd number group and the even number group. Therefore, rapid equalization of the lithium battery pack and start-stop control of the equalizer are realized to avoid energy loss. According to the method, the working efficiency of the equalizer is remarkably improved.

Description

Technical Field

[0001] The invention relates to a voltage-doubling rectifier cascade lithium battery equalizer and a hybrid half-bridge control method, belonging to the technical field of power electronic converter control. Background Art

[0002] Lithium batteries are widely used in energy storage systems, uninterruptible power supplies, electric vehicles and other fields. They not only have the characteristics of high energy density, high power density, high conversion efficiency, but also have the advantages of low self-discharge rate and large discharge current. The battery voltage of lithium batteries is 3.3-4.2V, and the high voltage source can be achieved by connecting multiple lithium batteries in series to form a battery pack. Due to the difference in self-discharge rate and internal impedance of lithium batteries when charging (discharging) in series, overcharging or over-discharging may occur during series charging (discharging). It will cause battery performance to decline, shorten service life, and even pose a safety hazard. Therefore, it is necessary to introduce battery balancing technology to redistribute and manage the energy of each battery cell, reduce the inconsistency between batteries, and thus extend the service life of the series battery pack.

[0003] Common battery balancing technologies are divided into active balancing technology and passive balancing technology. Active balancing technology is based on active switching devices to achieve voltage regulation of each battery cell. Its characteristics are that the voltage of each battery cell can be adjusted independently and the accuracy is controllable, but the circuit is relatively complex and the cost is high.

[0004] Passive active balancing technology uses passive devices such as coupled inductors, multi-winding transformers and capacitors to achieve voltage balancing of each battery cell. It is characterized by simple circuit structure, low cost and easy control. Currently, there are half-wave voltage doubler rectification, full-wave voltage doubler rectification, voltage doubler rectification cascade, etc. During the balancing process, the half-wave voltage doubler rectification balancing circuit charges the low-voltage unit, and the high-voltage unit is charged and discharged once in one switching cycle, resulting in additional energy loss. Although full-wave voltage doubler rectification improves it by only charging the low-voltage unit during the balancing process, the use of more diodes and DC blocking capacitors results in higher balancing costs and greater balancing losses.

[0005] In the prior art, the half-wave voltage doubler rectifier topology has a long balancing path, and the full-wave voltage doubler rectifier topology has too many passive devices, resulting in a large balancing loss. Summary of the invention

[0006] Purpose of the invention: In order to solve the problem of long balancing path of half-wave voltage doubler rectifier topology and the disadvantage of too many passive devices and large balancing loss of full-wave voltage doubler rectifier topology, the present invention combines the half-bridge inverter with the voltage doubler rectifier cascade topology to form a new type of equalizer, and adds a single-pole double-throw switch relay to realize multi-mode switching. And according to the balancing characteristics of this equalizer, when the initial voltages of the battery cells in the odd-even array group are inconsistent, it is difficult to balance the battery cells between the odd-even array groups during the balancing process. The present invention proposes a hybrid half-bridge control strategy to solve this problem.

[0007] The present invention improves the voltage doubler rectifier cascade equalizer, expands the application scope of the equalizer, and introduces a hybrid half-bridge control strategy to solve the problem that the voltage difference between batteries in the groups is difficult to eliminate after the intra-group balancing is completed due to the inconsistent voltage between the initial odd and even groups. The present invention not only improves the practicability of the equalizer, but also further improves the working efficiency of the equalizer.

[0008] Technical solution: An improved voltage doubler rectifier cascade lithium battery equalizer, the equalizer includes a single-pole double-throw switch relay, a half-bridge inverter, a buffer inductor, a cascade voltage doubler rectifier, a high-frequency transformer with n secondary windings, and a series lithium battery group, wherein the series lithium battery group is divided into an odd number of batteries B il (i=1,2,……,n) unit and even-numbered battery B i2 (i=1,2,……,n) unit.

[0009] The SPDT switch relay is connected to the half-bridge inverter and two different input sources to switch the working mode of the voltage doubler rectifier cascade lithium battery balancer. The normally closed SPDT switch relay corresponds to the external power supply balance mode of the balancer, and the normally open SPDT switch relay corresponds to the battery pack self-power supply balance mode of the balancer.

[0010] The half-bridge inverter consists of two voltage-equalizing capacitors C1 and C2 and two switching devices S a , S b Composition. a The drain is connected to the single-pole double-throw switch relay K1 interface, S b The source is connected to the relay K2 interface of the SPDT switch, S a The source and S b The drains of are commonly connected to the first end of the buffer inductor L.

[0011] The primary like-name ends of the high-frequency transformer of n secondary windings are connected to the second end of the buffer inductor, and the primary opposite-name ends are connected to the middle of the voltage-equalizing capacitors C1 and C2; the i-th (i=1, 2, ..., n) secondary winding of the transformer has the same-name end connected to the middle pole of the i-th rectifier, and the secondary winding opposite-name end is connected to the middle stage of the i-th lithium battery.

[0012] The voltage doubler rectifier contains two odd-even batteries B il , B i2 (i=1,2,……,n) and rectifier diode D i1 , D i2 (i=1,2,……,n), the voltage doubler rectifier consists of a rectifier diode D i1 Connect the cathode of the odd numbered battery B il The positive pole of the rectifier diode D i2 Connect the anode of even numbered battery B i2 The negative pole of the rectifier diode D i1 The anode of the diode D is connected to the i2 cathode.

[0013] A hybrid half-bridge control method comprises the following steps:

[0014] Step 1: During the balancing process, the battery cell status is monitored in real time. On this basis, the voltage difference U between the odd-numbered battery group and the even-numbered battery group is calculated. B1 , U B2 for:

[0015] U B1 =U B1max -U B1min (3)

[0016] U B2 =U B2max -U B2min (4)

[0017] Step 2: Determine the voltage difference U of the battery cells in the odd-even array battery pack B1 , U B2 Whether it exceeds the set balance threshold. B1 >0.05, U B1 If >0.05, go to step 3; otherwise, go to step 4.

[0018] Step 3: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Stay consistent and go to step 8.

[0019] Step 4: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and calculate U B1min with U B2min Voltage difference, judgment |U B1min -U B2min | is related to 0.03, when |UB1min -U B2min When |>0.03, go to step 5; otherwise, go to step 8.

[0020] Step 5: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and compare U B1min with U B2min The voltage difference when U B1min >U B2min Go to step 6 when U B1min B2min Go to step 7. B1min =U B2min Go to step 8.

[0021] Step 6: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Asymmetric duty cycle complementary control, where U D is the diode voltage drop, k is the transformation ratio of the multi-winding transformer, and then proceed to step 4. At this time, the control signal duty cycle D satisfies:

[0022]

[0023] Step 7: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Complementary asymmetric duty cycle, then enter step 4, at this time the control signal duty cycle satisfies:

[0024]

[0025] Step 8: Control the half-bridge switch S a , S b The driving signal remains at a low level.

[0026] The balancer needs to perform symmetrical duty cycle half-bridge control. After the voltage of the battery pack in the group is balanced, the voltage difference between the odd and even battery packs is calculated. If it exceeds the set balance threshold, it indicates that the balancer needs to further perform asymmetrical duty cycle half-bridge control to achieve voltage balance between the batteries. When the voltage difference of all batteries does not exceed the set balance threshold, it means that the entire battery pack balance process is completed. After the balance is completed, the drive signal is stopped to avoid energy loss caused by the continued operation of the balance circuit.

[0027] ​Beneficial effect: The improved voltage-doubling rectifier cascade lithium battery equalizer and hybrid half-bridge control method proposed in the present invention add a relay of a single-pole double-throw switch to realize the switching of the equalizer mode, which are respectively an external power supply equalization mode and a battery pack self-power supply equalization mode. The hybrid half-bridge control adopts symmetrical half-bridge control and asymmetrical half-bridge control respectively, and adopts corresponding control strategies according to the real-time monitoring of the battery cell status. It realizes rapid equalization of the series lithium battery pack and effectively eliminates the battery difference between the odd-group and even-group battery cells; after the equalization is completed, the equalizer automatically stops balancing, thereby reducing the energy consumption of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The main circuit topology of the improved voltage doubler rectifier cascade lithium battery equalizer according to the embodiment of the present invention;

[0029] Figure 2 It is the main circuit topology of the improved voltage doubler rectifier cascade lithium battery equalizer in the battery pack self-powered equalization mode according to the embodiment of the present invention;

[0030] Figure 3 The main circuit topology of the improved voltage doubler rectifier cascade lithium battery equalizer in the embodiment of the present invention is in the external power supply equalization mode;

[0031] Figure 4 The improved voltage doubler rectifying cascade lithium battery equalizer of the embodiment of the present invention operates in mode 1 when the voltage of the battery cells in the odd and even groups are balanced;

[0032] Figure 5 The improved voltage doubler rectifying cascade lithium battery equalizer of the embodiment of the present invention operates in mode 2 when the voltage of the battery cells in the odd and even groups are balanced;

[0033] Figure 6 The improved voltage doubler rectifying cascade lithium battery equalizer of the embodiment of the present invention operates in mode 3 when the voltage of the battery cells in the odd and even groups are balanced;

[0034] Figure 7 The improved voltage doubler rectifying cascade lithium battery equalizer of the embodiment of the present invention operates in mode 4 when the voltage of the battery cells in the odd and even groups are balanced;

[0035] Figure 8 The improved voltage doubler rectifying cascade lithium battery equalizer of the embodiment of the present invention is a working waveform of the equalizer when the battery cell voltages in the odd and even groups are balanced;

[0036] Fig. 9 The improved voltage doubler rectifier cascade lithium battery equalizer of the embodiment of the present invention operates in mode 1 when the battery cell voltages of the odd and even groups are balanced. At this time, the initial voltage of the odd group battery cell is u Bi1< Initial voltage of even-numbered battery cells u Bi2 ;

[0037] Fig.10 The improved voltage doubler rectifier cascade lithium battery equalizer of the embodiment of the present invention operates in mode 2 when the battery cell voltages of the odd and even groups are balanced. At this time, the initial voltage of the odd group battery cell is u Bi1 < Initial voltage of even-numbered battery cells u Bi2 ;

[0038] Fig.11 The improved voltage doubler rectifier cascade lithium battery equalizer of the embodiment of the present invention operates in mode 3 when the battery cell voltages of the odd and even groups are balanced. At this time, the initial voltage of the odd group battery cell is u Bi1 < Initial voltage of even-numbered battery cells u Bi2 ;

[0039] Fig.12 The improved voltage doubler rectifier cascade lithium battery equalizer of the embodiment of the present invention is in the odd-group battery unit u Bi1 Even-numbered battery cells u Bi2 The equalizer working waveform at voltage;

[0040] Fig.13 A method for quickly achieving balancing of odd-even battery packs using a hybrid half-bridge control strategy according to an embodiment of the present invention;

[0041] Fig.14 The equivalent circuit of the improved voltage doubler rectifier cascade lithium battery equalizer according to the embodiment of the present invention;

[0042] Fig.15 The equalizer of the present invention adopts the operating waveform of hybrid half-bridge control. At this time, the switch tube S a The driving signal u gsa With switch tube S b The driving signal u gsb Asymmetric duty cycle complementary control;

[0043] Fig.16 The voltage variation curve of the lithium battery under static equalization under the open-loop control of the equalizer of the present invention;

[0044] Fig.17 The voltage variation curve of the lithium battery under static equalization under the control of the equalizer hybrid half-bridge of the present invention;

[0045] Symbol names in the figure: K1-K2——single-pole double-throw switch relay switch; Sa-Sb——half-bridge switch tube; u AB ——half-bridge inverter output AC voltage; u' AB ——The voltage after the half-bridge inverter output AC voltage is converted to the secondary side of the transformer; u CD——voltage on the primary side of the transformer; L——buffer inductance; L'——inductance value after buffer inductance is converted to the secondary side of the transformer; i' L ——The current value of the buffer inductor current converted to the secondary side of the transformer; i T11 ——Buffer inductor current; i T12 -i Tn2 ——The current of the first secondary side to the nth secondary side of the multi-winding transformer; i M11 -i Mn1 ——Charging current of odd-numbered battery cells; i M12 -i Mn2 ——Charging current of an even-numbered battery cell; T——Multi-winding high-frequency transformer; n1——Primary winding of a multi-winding high-frequency transformer; n21-n2i——First secondary winding to nth secondary winding of a multi-winding transformer; D 11 -D n1 ——Odd-number rectifier diodes; D 12 -D n2 ——even-numbered array of rectifier diodes; B 11 -B n1 ——Odd-number battery cells; B 12 -B n2 ——Even array of battery cells. DETAILED DESCRIPTION

[0046] The present invention is further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0047] This embodiment improves the working mode of the voltage-doubling rectifier cascade lithium battery equalizer and the disadvantage of inconsistent balancing between the odd-array battery cells and the even-array battery cells of the equalizer. An external power supply balancing mode is added through a single-pole double-throw switch relay, and real-time monitoring of the battery cell status is performed. At the same time, a hybrid half-bridge control strategy is disclosed, which can realize a method for fast balancing of odd-array battery cells and even-array battery cells.

[0048] An improved voltage doubler rectifier cascade lithium battery equalizer Figure 1 As shown, the balancer includes a single-pole double-throw switch relay, a half-bridge inverter, a buffer inductor, a cascade voltage doubler rectifier, a high-frequency transformer with n secondary windings, and a series lithium battery group, wherein the series lithium battery group is divided into odd-numbered batteries B il (i=1,2,……,n) unit and even-numbered battery B i2 (i=1,2,……,n) unit.

[0049] The SPDT switch relay is connected to the half-bridge inverter and two different input sources to switch the working mode of the voltage doubler rectifier cascade lithium battery balancer. The normally closed SPDT switch relay corresponds to the external power supply balance mode of the balancer, and the normally open SPDT switch relay corresponds to the battery pack self-power supply balance mode of the balancer.

[0050] The half-bridge inverter consists of two voltage-equalizing capacitors C1 and C2 and two switching devices S a , S b Composition. a The drain is connected to the single-pole double-throw switch relay K1 interface, S b The source is connected to the relay K2 interface of the SPDT switch, S a The source and S b The drains of are commonly connected to the first end of the buffer inductor L.

[0051] The same-named ends of the primary side of the multi-winding transformer are connected to the second end of the buffer inductor, and the opposite-named ends of the primary side are connected to the middle of the voltage-equalizing capacitors C1 and C2; the same-named ends of the i-th (i=1, 2, ..., n) secondary winding of the multi-winding transformer are connected to the middle pole of the i-th rectifier, and the opposite-named ends of the secondary winding are connected to the middle stage of the i-th lithium battery.

[0052] The voltage doubler rectifier contains two lithium batteries B il , B i2 (i=1,2,……,n) and rectifier diode D i1 , D i2 (i=1,2,……,n), the i-th voltage doubler rectifier consists of D i1 The anode of the i-th lithium battery is connected to the negative electrode, D i2 The cathode of D is connected to the positive electrode of the i-th lithium battery; i1 The cathode is connected to D i2 anode; a cascade voltage doubler rectifier is connected by the positive electrode of the jth (j=1, 2, ..., (n-1)) lithium battery group and the negative electrode of the (j+1)th lithium battery group.

[0053] Improved voltage doubler rectifier cascade lithium battery equalizer When the single-pole double-throw switch relay is in the normally open state, such as Figure 2 As shown, the series lithium battery pack is used as the input source of the half-bridge inverter, the improved voltage doubler rectifier cascade lithium battery balancer is in the battery pack self-powered balance mode, and the series lithium battery pack is statically balanced; when the single-pole double-throw switch relay is in the normally closed state as shown in FIG. Figure 3 The DC source on the left provides the input source for the half-bridge inverter to balance the charging of the series-connected lithium battery pack.

[0054] A hybrid half-bridge control method, wherein the half-bridge inverter uses symmetrical half-bridge control and asymmetrical half-bridge control. When the odd-group battery cells and the even-group battery cells are balanced within the group, symmetrical half-bridge control is used, wherein the switch tube S a ,S b The driving signal u GS Waveform Figure 8 As shown in the figure, in one switching cycle, the equalizer operation is divided into four modes, corresponding to Figure 4-Figure 7 ,in Figure 4 , Figure 5 Balance the odd-numbered battery cells. Figure 6 , Figure 7 The even array battery cells are balanced within the group. When the odd array battery cells and the even array battery cells are balanced between groups, it is assumed that the initial voltage u of the odd array battery cells in the battery group Bi1 < Initial voltage of even-numbered battery cells u Bi2 , using asymmetric half-bridge control, where the switch tube S a ,S b The driving signal u GS Waveform Fig.12 As shown in the figure, in one switching cycle, the equalizer operation is divided into three modes, where Fig. 9 , Fig.10 The odd-numbered battery cells with low voltage are charged, and no balancing current flows through the even-numbered battery cells, thereby quickly eliminating the voltage difference between the odd-numbered and even-numbered battery cells. Fig.11 There is no balancing current flowing through the odd-group battery and the even-group battery. Bi1 >Even array battery cells u Bi2 The circuit operation characteristics are symmetrical with the above analysis and will not be elaborated here.

[0055] Mode 1 Figure 4 ]:At t0, the switch tube S a Conducting, multi-winding transformer primary voltage u CD From negative to positive, the diodes corresponding to the odd-numbered battery groups are turned on, i L (t) increases linearly and reaches its maximum value at the end of mode 1, and the odd-group battery cells begin to receive the charging current.

[0056] Mode 2 Figure 5 ]:At t1, the switch tube S a is turned off. Since the inductor current cannot change suddenly, the current flows through the switch tube S b The body diode of the switch tube S forms a freewheeling loop. bThe transformer primary and secondary voltage directions remain unchanged, the diodes corresponding to the odd-numbered battery groups continue to conduct, and the odd-numbered battery cells are still charged.

[0057] In the period t2-t4, the circuit starts the negative half-cycle working process. The circuit operation characteristics are symmetrical with the above analysis. Similarly, the corresponding modal diagrams correspond to Figure 6-Figure 7 , I will not go into details here.

[0058] Mode 1 Fig. 9 ]: Switching tube S a conduction, buffering inductor current i L The diodes corresponding to the odd-numbered batteries are turned on, and the secondary current of the transformer charges the odd-numbered batteries through the diodes. At the end of mode 1, i.e., at t1, i L(t) reaches the maximum value in the positive direction.

[0059] Mode 2 Fig.10 ]: Switching tube S b Conducting, half-bridge output voltage u AB From positive to negative, i L The odd-group battery's corresponding diode is still turned on, and the odd-group battery is in a charging state. At t2, the odd-group battery's charging current drops to 0.

[0060] Mode Three Fig.11 ]: Transformer primary voltage u CD From positive to negative, the asymmetric current on the primary side of the transformer passes through the transformer, causing the iron core to be magnetized, and no current passes through the secondary side of the transformer. At this time, no current passes through both the odd-group battery and the even-group battery.

[0061] The present invention proposes an equivalent circuit of an improved voltage doubler rectifier cascade lithium battery equalizer as follows: Fig.13 The balancing circuit first adopts a symmetrical half-bridge control strategy to balance the voltage within the odd and even battery groups. The voltage of the batteries within the group is equal. According to the principle of mutual clamping of primary voltages, the balancing principle can be summarized as follows: only the module with the smallest voltage in the odd (or even) battery group will be in u AB The positive half cycle (or negative half cycle) receives energy from the half-bridge inverter, thereby achieving voltage balance among all modules in the even (odd) group.

[0062] The present invention discloses a hybrid half-bridge control control strategy, which selects different half-bridge control modes for intra-group balancing and inter-group balancing of odd-group battery cells and even-group battery cells in order to improve the balancing efficiency of the series battery pack. Fig.14 , which has 8 steps, as follows:

[0063] Step 1: During the balancing process, the battery cell status is monitored in real time. On this basis, the voltage difference U between the odd-numbered battery group and the even-numbered battery group is calculated. B1 , U B2 for:

[0064] U B1 =U B1max -U B1min (7)

[0065] U B2 =U B2max -U B2min (8)

[0066] Step 2: Determine the voltage difference U of the battery cells in the odd-even array battery pack B1 , U B2 Whether it exceeds the set balance threshold. B1 >0.05, U B1 If >0.05, go to step 3; otherwise, go to step 4.

[0067] Step 3: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Stay consistent and go to step 8.

[0068] Step 4: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and calculate U B1min with U B2min Voltage difference, judgment |U B1min -U B2min | is related to 0.03, when |U B1min -U B2min When |>0.03, go to step 5; otherwise, go to step 8.

[0069] Step 5: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and compare U B1min with U B2min The voltage difference when U B1min >U B2min Go to step 6 when U B1min B2min Go to step 7 when U B1min =U B2min Go to step 8.

[0070] ​Step 6: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Asymmetric duty cycle complementary control, where U D is the diode voltage drop, k is the transformation ratio of the multi-winding transformer, and then proceed to step 4. At this time, the control signal duty cycle satisfies:

[0071]

[0072] Step 7: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Complementary asymmetric duty cycle, then enter step 4, at this time the control signal duty cycle satisfies:

[0073]

[0074] Step 8: Control the half-bridge switch S a , S b The driving signal remains at a low level.

[0075] In step 4, it is determined whether there is an obvious battery difference between the odd and even array battery cells. B1min -U B2min |>0.03, that is, there is an obvious difference, and the equalizer continues to work. B1min -U B2min |<0.03, that is, there is a significant difference, then turn off the switch tube S a , S b signal, the equalizer stops working.

[0076] In step 5, the voltage comparison relationship between the odd-group battery cells and the even-group battery cells is identified. B1min B2min The odd-numbered battery cells should be charged when U B1min >U B2min Even groups of battery cells should be charged at the same time.

[0077] ​In summary, the present invention proposes an improved voltage doubler rectifier cascade lithium battery equalizer and a hybrid half-bridge control strategy. The improved topology expands the use scope of the equalizer and increases the market practicability. A hybrid half-bridge control strategy is proposed to address the low efficiency of intra-group and inter-group equalization of odd-even battery groups. In the case of avoiding increasing the circuit topology, not only fast intra-group equalization of odd-even battery groups but also fast inter-group equalization of odd-even battery groups is achieved. After the equalization is completed, the half-bridge inverter switch tube maintains a low-level drive signal to avoid energy loss when the equalization cannot be suspended and continued. It has important application and promotion value for the equalization of electric vehicles and energy storage battery systems.

Claims

1. A voltage doubler rectifier cascade lithium battery equalizer, characterized in that: The balancer includes a single-pole double-throw switch relay, a half-bridge inverter, a buffer inductor, a cascade voltage doubler rectifier, a high-frequency transformer with n secondary windings, and a series-connected lithium battery pack, wherein the series-connected lithium battery pack is divided into an odd number of batteries B il Unit with even number of batteries B i2 Unit, i = 1, 2, ..., n; The single-pole double-throw switch relay is connected to the half-bridge inverter and two different input sources. The normally closed state of the single-pole double-throw switch relay corresponds to the external power supply balancing mode of the balancer, and the normally open state of the single-pole double-throw switch relay corresponds to the battery pack self-power supply balancing mode of the balancer.

2. The voltage doubler rectifier cascade lithium battery equalizer according to claim 1, characterized in that: The half-bridge inverter consists of two voltage-sharing capacitors C1 and C2 and two switching devices S a , S b Composition: Switching device S a The drain is connected to the single-pole double-throw switch relay K1 interface, the switch device S b The source is connected to the relay K2 interface of the SPDT switch, S a The source and S b The drains of are commonly connected to the first end of the buffer inductor L.

3. The voltage doubler rectifier cascade lithium battery equalizer according to claim 2, characterized in that: The primary like-name ends of the high-frequency transformer of the n secondary windings are connected to the second end of the buffer inductor, and the primary opposite-name ends are connected to the middle of the voltage-equalizing capacitors C1 and C2; the i-th secondary winding of the transformer has the same-name end connected to the middle pole of the i-th rectifier, and the secondary winding has the opposite-name end connected to the middle stage of the i-th lithium battery.

4. The voltage doubler rectifier cascade lithium battery equalizer according to claim 1, characterized in that: The voltage doubler rectifier comprises two odd-even batteries B il , B i2 , and the rectifier diode D i1 , D i2 The voltage doubler rectifier consists of a rectifier diode D i1 Connect the cathode of the odd numbered battery B il The positive pole of the rectifier diode D i2 Connect the anode of even numbered battery B i2 The negative pole of the rectifier diode D i1 The anode of the diode D is connected to the i2 cathode.

5. A hybrid half-bridge control method for the voltage doubler rectifier cascade lithium battery equalizer as claimed in claim 1, characterized in that: The balancer needs to perform symmetrical duty cycle half-bridge control; after achieving voltage balance in the battery pack within the group, calculate the voltage difference between the odd and even battery packs; if it exceeds the set balance threshold, it indicates that the balancer needs to further perform asymmetrical duty cycle half-bridge control to achieve voltage balance between batteries in the group; when the voltage difference of all batteries does not exceed the set balance threshold, it indicates that the entire battery pack balance process is completed; After the equalization is completed, the driving signal is stopped to avoid energy loss caused by the continued operation of the equalization circuit; Real-time monitoring of odd and even battery voltages, identification of balancing modes, |U B1max -U B1min |>0.05 or |U B2max -U B2min When |>0.05, U B1min , U B2min The lowest battery voltage in the odd-numbered battery group and the even-numbered battery group respectively, the batteries in the battery group are balanced, and according to the principle of mutual clamping of primary voltages, the battery cell with the smallest voltage in the odd-numbered and even-numbered arrays receives the energy of the half-bridge inverter, thereby achieving voltage balance between the batteries in the odd-numbered and even-numbered arrays.

6. The control method of the hybrid half-bridge according to claim 5, characterized in that: When the odd-group battery cells and the even-group battery cells are balanced, |U B1min -U B2min |>0.03, indicating that there is still a voltage difference between the odd and even battery cell groups, and it is difficult to eliminate it during the balancing process. It is necessary to charge the odd and even battery cell low-voltage battery cells to quickly eliminate the voltage difference between the groups, thereby achieving battery balancing.

7. The control method of the hybrid half-bridge according to claim 5, characterized in that: The series lithium battery pack not only realizes fast balancing of the batteries within the odd and even groups, but also realizes fast balancing of the battery voltages between the odd and even groups. After the balancing is completed, the half-bridge inverter switch tube maintains a low-level drive signal to avoid energy loss caused by the balancer continuing to work.

8. The control method of the hybrid half-bridge according to claim 5, characterized in that: The steps include: Step 1: During the balancing process, the battery cell status is monitored in real time; the voltage difference U between the odd-numbered battery group and the even-numbered battery group is calculated. B1 , U B2 ; Step 2: Determine the voltage difference U of the battery cells in the odd-even array battery pack B1 , U B2 Whether it exceeds the set balance threshold; when U B1 , U B2 If the set balance threshold is exceeded, go to step 3, otherwise go to step 4; Step 3: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Keep it consistent and go to step 8; Step 4: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and calculate U B1min with U B2min Voltage difference, judgment |U B1min -U B2min | and the set value m, when |U B1min -U B2min |>m, go to step 5, otherwise go to step 8; Step 5: Detect the minimum voltage U of the battery cells in the odd-numbered battery pack B1min The minimum voltage U of the battery cells in the even-numbered battery group B2min , and compare U B1min with U B2min The voltage difference when U B1min >U B2min Go to step 6 when U B1min B2min Go to step 7 when U B1min =U B2min Go to step 8;​ Step 6: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Asymmetric duty cycle complementary control, where U D is the diode voltage drop, k is the transformation ratio of the multi-winding transformer, and then proceed to step 4. At this time, the control signal duty cycle satisfies: Step 7: Control the switch S in the half-bridge inverter a The driving signal u gsa With switch tube S b The driving signal u gsb Complementary asymmetric duty cycle, then enter step 4, at this time the control signal duty cycle satisfies: Step 8: Control the half-bridge switch S a , S b The driving signal remains at a low level.

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