Current-controllable single bidirectional switch circuit and control method thereof

Abstract

The application relates to the field of electronic technology, in particular to a current-controllable single / dual-direction switch circuit and a control method thereof, which comprises a driving circuit, a diode, a lithium battery, a generator and a switch tube circuit. The two or more than two transistors are connected in parallel through the setting of the switch circuit, the reaction time of controlling the direction of the lithium battery loop current can be improved, the driving circuit is connected with the control signal of the external device, the direction of the lithium battery loop current can be determined, and the switch circuit can work in a dual-control mode. The single / dual-direction switch circuit designed by the scheme also has the overcurrent protection function of the reverse current of the lithium battery loop when the external control signal is a bidirectional signal.

Description

[0001] This case is a divisional application based on the invention patent filed on April 1, 2019, with application number 201910255894.1 and titled "A Unidirectional and Bidirectional Switching Circuit and Its Control Method". Technical Field

[0002] This invention relates to the field of electronic technology, and in particular to a current-controllable unidirectional and bidirectional switching circuit and its control method. Background Technology

[0003] As a sunrise industry, the lithium battery industry boasts broad market prospects. In today's global electronics and information industry, mobile communications, laptops, and digital cameras are the three fastest-growing sectors. Lithium batteries offer advantages such as high operating voltage, high specific energy, long cycle life, low self-discharge rate, and no memory effect. However, lithium battery power systems present charging and discharging protection issues. Because lithium batteries cannot be charged under extremely low temperatures, but can be discharged, problems arise regarding the current direction control in the lithium battery circuit and excessive current in the power lithium battery. Early lithium battery current control used relay switching. However, relay contacts have a limited lifespan and significant contact resistance variations, leading to sparking during switching, potential damage, and safety concerns. Using electronic switches (such as MOSFETs or IGBTs) is a reliable current switching method; however, electronic switches require reliable on / off control and reliable overcurrent protection circuits to operate safely. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a unidirectional and bidirectional switching circuit and its control method.

[0005] To solve the above-mentioned technical problems, the first technical solution adopted by the present invention is as follows:

[0006] A unidirectional and bidirectional switching circuit includes a driving circuit, a diode, a lithium battery, a generator, and a switching transistor circuit, wherein the switching transistor circuit includes two or more transistors connected in parallel with each other.

[0007] The positive terminal of the lithium battery is electrically connected to the anode of the diode and the drain of two or more transistors connected in parallel. The negative terminal of the lithium battery is electrically connected to the negative terminal of the generator. The cathode of the diode is electrically connected to the driving circuit, the positive terminal of the generator, and the source of two or more transistors connected in parallel. The gate of the two or more transistors connected in parallel is electrically connected to the driving circuit. The driving circuit is electrically connected to the control signal of the peripheral device.

[0008] The second technical solution adopted in this invention is:

[0009] A control method for a unidirectional and bidirectional switching circuit includes the following steps:

[0010] S1. Collect the loop current value of the lithium battery and receive control signals;

[0011] S2. Determine whether the circuit current value of the lithium battery collected in step S1 is positive.

[0012] S3. If not, determine the type of control signal received;

[0013] If the received control signal is a unidirectional signal, all transistors in the switching circuit will be turned off;

[0014] If the received control signal is a bidirectional signal, then all transistors in the switching circuit will be turned on.

[0015] The beneficial effects of this invention are as follows:

[0016] By setting up a switching circuit and connecting two or more transistors in parallel, the response time for controlling the direction of the lithium battery circuit current can be improved. Connecting the drive circuit to the control signal of the external device allows for determination of the direction of the lithium battery circuit current and enables the switching circuit to operate in a dual-control mode. The bidirectional switching circuit designed in this scheme also has overcurrent protection against reverse current in the lithium battery circuit when the external control signal is bidirectional. It not only reliably switches the current but also controls the switching at different current points, optimizing the control method. For example, in the low-temperature state of the lithium battery, the DSP controls the switching of the charging current; when the lithium battery temperature rises, it can control the charging current at different temperatures. Attached Figure Description

[0017] Figure 1 A circuit diagram of a unidirectional and bidirectional switching circuit according to the present invention;

[0018] Figure 2 The circuit diagram is shown in a second embodiment of a unidirectional and bidirectional switching circuit according to the present invention.

[0019] Figure 3 Here is an overall circuit diagram of a unidirectional and bidirectional switching circuit according to the present invention;

[0020] Figure 4 The present invention provides a flowchart of the steps of a control method for a unidirectional and bidirectional switching circuit according to the present invention.

[0021] Label Explanation:

[0022] 1. Drive circuit; 2. Lithium battery; 3. Generator; 4. Switching transistor circuit; 5. Transistor voltage drop sampling circuit; D1, Diode. Detailed Implementation

[0023] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0024] The most crucial concept of this invention lies in solving the lithium battery charging and discharging protection problem through the cooperation between the drive circuit, diode, lithium battery, generator, and switching transistor circuit.

[0025] Please refer to Figures 1 to 3 The present invention provides a technical solution:

[0026] A unidirectional and bidirectional switching circuit includes a driving circuit, a diode, a lithium battery, a generator, and a switching transistor circuit, wherein the switching transistor circuit includes two or more transistors connected in parallel with each other.

[0027] The positive terminal of the lithium battery is electrically connected to the anode of the diode and the drain of two or more transistors connected in parallel. The negative terminal of the lithium battery is electrically connected to the negative terminal of the generator. The cathode of the diode is electrically connected to the driving circuit, the positive terminal of the generator, and the source of two or more transistors connected in parallel. The gate of the two or more transistors connected in parallel is electrically connected to the driving circuit. The driving circuit is electrically connected to the control signal of the peripheral device.

[0028] As can be seen from the above description, the beneficial effects of the present invention are as follows:

[0029] By setting up a switching circuit and connecting two or more transistors in parallel, the response time for controlling the direction of the lithium battery circuit current can be improved. Connecting the drive circuit to the control signal of the external device allows for determination of the direction of the lithium battery circuit current and enables the switching circuit to operate in a dual-control mode. The bidirectional switching circuit designed in this scheme also has overcurrent protection against reverse current in the lithium battery circuit when the external control signal is bidirectional. It not only reliably switches the current but also controls the switching at different current points, optimizing the control method. For example, in the low-temperature state of the lithium battery, the DSP controls the switching of the charging current; when the lithium battery temperature rises, it can control the charging current at different temperatures.

[0030] Furthermore, it also includes a diode voltage drop sampling circuit, which is electrically connected to the anode of the diode, the cathode of the diode, and the driving circuit, respectively.

[0031] As can be seen from the above description, the tube voltage drop sampling protection circuit is simple, low in cost, and has a fast response speed, and its loudness can reach the 100ns level.

[0032] Furthermore, the control signal is a unidirectional signal or a bidirectional signal.

[0033] As described above, when the control signal is unidirectional, the current can only flow in the positive direction and cannot flow in the reverse direction. The lithium battery's loop current flows from 0 to the positive direction or from the negative direction to the positive direction. The oscillation of the switching transistor circuit can be prevented by setting a delay time. When the control signal is bidirectional, the switching transistor circuit is always in the on state, and the lithium battery's loop current can flow in either the positive or negative direction.

[0034] Furthermore, the number of transistors is 2-6.

[0035] Furthermore, the transistor is a MOS transistor or an IGBT transistor.

[0036] As described above, MOSFETs are currently used in low-voltage ranges; for example, at 100V, their internal resistance can be as low as 1 milliohm, resulting in only 10W of current draw after 100A. Multiple MOSFETs connected in parallel can achieve low-power, high-efficiency electronic switches. IGBTs are used at high voltages (300V-1000V) and operate on a similar principle to MOSFETs. Currently, the collector voltage V... CE It can also operate at around 1.5V, and all of them are high-efficiency electronic switches (operating frequency > 5KHz).

[0037] Please refer to Figure 4 Another technical solution provided by the present invention:

[0038] A control method for a unidirectional and bidirectional switching circuit includes the following steps:

[0039] S1. Collect the loop current value of the lithium battery and receive control signals;

[0040] S2. Determine whether the circuit current value of the lithium battery collected in step S1 is positive.

[0041] S3. If not, determine the type of control signal received;

[0042] If the received control signal is a unidirectional signal, all transistors in the switching circuit will be turned off;

[0043] If the received control signal is a bidirectional signal, then all transistors in the switching circuit will be turned on.

[0044] Furthermore, step S3 also includes:

[0045] If so, all transistors in the switching circuit are turned on.

[0046] Furthermore, it also includes:

[0047] A first rate limit and a second rate limit are preset. The first rate limit is less than the second rate limit and both the first and second rate limits are negative.

[0048] When the received control signal is a bidirectional signal and the lithium battery loop current value is negative, the lithium battery loop current value is compared with the first current limit value and the second current limit value respectively.

[0049] If the loop current value is greater than the first current limit value and less than the second current limit value, then all transistors in the switching circuit are turned off;

[0050] If the loop current value is greater than the second current limit value, all transistors in the switching circuit are turned on.

[0051] As can be seen from the above description, when the switching circuit operates in bidirectional signal mode, it can protect the negative current of the lithium battery circuit and prevent overcurrent. The first current limit value and the second current limit value are mainly used to protect the transistor from entering a high-frequency oscillation state and are coordinated with the delayed switching time to ensure reliable on / off electronic switching.

[0052] Please refer to Figure 1 and Figure 3 Embodiment 1 of the present invention is as follows:

[0053] A unidirectional and bidirectional switching circuit includes a driving circuit 1, a diode D1, a lithium battery 2, a generator 3, and a switching transistor circuit 4, wherein the switching transistor circuit 4 includes two or more transistors connected in parallel with each other.

[0054] The positive terminal of the lithium battery 2 is electrically connected to the anode of the diode D1 and the drain of two or more transistors connected in parallel. The negative terminal of the lithium battery 2 is electrically connected to the negative terminal of the generator 3. The cathode of the diode is electrically connected to the positive terminal of the drive circuit 1, the generator 3, and the source of two or more transistors connected in parallel. The gate of the two or more transistors connected in parallel is electrically connected to the drive circuit 1. The drive circuit 1 is electrically connected to the control signal of the peripheral device.

[0055] The driving circuit 1 includes a first transistor, a second transistor, and an integrated chip. The emitter of the first transistor is electrically connected to the emitter of the second transistor, and the integrated chip is electrically connected to the collector of the first transistor and the collector of the second transistor, respectively.

[0056] Please refer to Figure 2 and Figure 3 Embodiment two of the present invention is as follows:

[0057] The difference between Embodiment 2 and Embodiment 1 is that Embodiment 2 also includes a diode voltage drop sampling circuit 5, which is electrically connected to the anode of the diode, the cathode of the diode, and the driving circuit 1.

[0058] The control signal can be a unidirectional signal or a bidirectional signal.

[0059] The number of transistors is 2-6, preferably 4.

[0060] The transistor is a MOS transistor or an IGBT transistor.

[0061] The tube voltage drop sampling circuit 5 includes an amplifier comparator and an electronic switch, and the amplifier comparator is electrically connected to the electronic switch.

[0062] Please refer to Figure 4 Embodiment 3 of the present invention is as follows:

[0063] A control method for a unidirectional and bidirectional switching circuit includes the following steps:

[0064] S1. Collect the loop current value of the lithium battery and receive the control signal; specifically, collect the loop current value of lithium battery 2 and receive the control signal, i.e., a unidirectional signal or a bidirectional signal.

[0065] S2. Determine whether the loop current value of lithium battery 2 collected in step S1 is positive.

[0066] S3. If not, determine the type of the received control signal; specifically, if the collected loop current value of lithium battery 2 is not positive, determine the type of the received control signal.

[0067] If the received control signal is a unidirectional signal, all transistors in the switching transistor circuit 4 will be turned off;

[0068] If the received control signal is a bidirectional signal, then all transistors in the switching transistor circuit 4 will be turned on.

[0069] If so, all transistors in switching circuit 4 will be turned on.

[0070] When the received control signal is a unidirectional signal and the loop current of lithium battery 2 is negative, a delay time can be set, which can be adjusted to about 10-100ms.

[0071] A first rate limit and a second rate limit are preset. The first rate limit is less than the second rate limit and both the first and second rate limits are negative.

[0072] When the received control signal is a bidirectional signal and the loop current value of lithium battery 2 is negative, the loop current value of lithium battery 2 is compared with the first current limiting value and the second current limiting value respectively.

[0073] If the loop current value is greater than the first current limit value and less than the second current limit value, then all transistors in the switching transistor circuit 4 are turned off;

[0074] If the loop current value is greater than the second current limit value, then all transistors in the switching circuit 4 are turned on.

[0075] the loop current value can be set as X, the first current limiting value is -3A, and the second current limiting value is -1A;

[0076] if -3 < X < -1, all transistors of the switching tube circuit are turned off;

[0077] if X > -1, all transistors of the switching tube circuit are turned on.

[0078] In summary, the present invention provides a unidirectional and bidirectional switching circuit and a control method therefor. By arranging a switching circuit and connecting two or more of said transistors in parallel with each other, the response time for controlling the direction of the loop current of a lithium battery can be improved; by connecting the driving circuit to an external control signal, the direction of the loop current of the lithium battery can be determined, and the switching circuit can be operated in a dual control mode. When the externally connected control signal is a bidirectional signal, the unidirectional and bidirectional switching circuit designed according to the present solution further has an overcurrent protection function for reverse loop current of the lithium battery; it can not only switch current reliably, but also can be controlled to switch at different current points, which optimizes the control mode. For example, when the lithium battery is in a low-temperature state, the DSP controls the charging current switching, and after the lithium battery temperature rises back, controlled current charging can be realized at different temperatures.

[0079] The above description is only embodiments of the present invention, and is not intended to limit the patent scope of the present invention. Any equivalent transformation made by using the content of the description and drawings of the present invention, whether directly or indirectly applied to the relevant technical field, is similarly included in the patent protection scope of the present invention.

Claims

1. A current-controllable unidirectional and bidirectional switching circuit, characterized in that, It includes a drive circuit, a diode, a lithium battery, a generator, and a switching transistor circuit, wherein the switching transistor circuit includes two or more transistors connected in parallel with each other; The positive terminal of the lithium battery is electrically connected to the anode of the diode and the drain of two or more transistors connected in parallel. The negative terminal of the lithium battery is electrically connected to the negative terminal of the generator. The cathode of the diode is electrically connected to the driving circuit, the positive terminal of the generator, and the source of two or more transistors connected in parallel. The gate of the two or more transistors connected in parallel is electrically connected to the driving circuit. The driving circuit is electrically connected to the control signal of the peripheral device. The control signal is a unidirectional signal or a bidirectional signal. It also includes a diode voltage drop sampling circuit, which includes an amplifying comparator and an electronic switch. The amplifying comparator is electrically connected to the anode of the diode, the cathode of the diode, the switching transistor circuit, and the electronic switch, respectively. The electronic switch is electrically connected to the driving circuit and the switching transistor circuit, respectively.

2. The current-controllable unidirectional and bidirectional switching circuit according to claim 1, characterized in that, The number of transistors is 2-6.

3. The current-controllable unidirectional and bidirectional switching circuit according to claim 1, characterized in that, The transistor is a MOS transistor or an IGBT transistor.

4. A control method for a current-controllable unidirectional and bidirectional switching circuit as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Collect the loop current value of the lithium battery and receive control signals; S2. Determine whether the circuit current value of the lithium battery collected in step S1 is positive. S3. If not, determine the type of control signal to be received; If the received control signal is a unidirectional signal, all transistors in the switching circuit will be turned off; If the received control signal is a bidirectional signal, then all transistors in the switching circuit will be turned on.

5. The control method for a current-controllable unidirectional and bidirectional switching circuit according to claim 4, characterized in that, Step S3 also includes: If so, all transistors in the switching circuit are turned on.

6. The control method for the current-controllable unidirectional and bidirectional switching circuit according to claim 4, characterized in that, Also includes: A first rate limit and a second rate limit are preset. The first rate limit is less than the second rate limit and both the first and second rate limits are negative. When the received control signal is a bidirectional signal and the lithium battery loop current value is negative, the lithium battery loop current value is compared with the first current limit value and the second current limit value respectively. If the loop current value is greater than the first current limit value and less than the second current limit value, then all transistors in the switching circuit are turned off; If the loop current value is greater than the second current limit value, all transistors in the switching circuit are turned on.

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