Power supply system

Abstract

The invention discloses a power supply system. The power supply system comprises an interface, an external power supply circuit, a battery power supply circuit and a first capacitor, the interface is used for being externally connected with a power supply; the interface is also connected with an input end of the external power supply circuit, a first output end of the external power supply circuit and a first output end of the battery power supply circuit are connected with a first load through the first capacitor, and the other end of the first capacitor is grounded. The power supply system provides two power supply modes of an external power supply and a battery for the load, the two power supply modes respectively supply power to the load, and since the output ends of the external power supply circuit and the battery power supply circuit are provided with the first capacitors, the output voltage is maintained based on the principle that the voltages at the two ends of the capacitors cannot suddenly change and energy storage discharge is realized; in the switching process of the two power supply modes, the two power supply modes are seamlessly connected to supply power to the load, and the phenomena of load outage, power supply voltage drop and the like are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power supply system. Background Art

[0002] The traditional power supply circuit supplies power to the load through an external power supply combined with a DC / DC converter, or supplies power to the load through a battery. In the process of switching from supplying power to the load through a DC / DC converter combined with an external power supply to supplying power to the load through a battery, or from supplying power to the load through a battery to supplying power to the load through an external power supply combined with a DC / DC converter, voltage drops may occur (that is, the switching between the two power supply modes cannot be seamlessly connected to supply power to the load), thereby affecting the normal use of the load. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a power supply system to overcome the defects of the prior art that power outages and voltage drops may occur during the switching process between an external power source and a battery, and that the load cannot be supplied with power seamlessly.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A power supply system comprises: an interface, an external power supply circuit, a battery power supply circuit and a first capacitor; the interface is used for an external power supply; the interface is also connected to an input end of the external power supply circuit, a first output end of the external power supply circuit and a first output end of the battery power supply circuit are both connected to a first load through the first capacitor, and the other end of the first capacitor is grounded.

[0006] Optionally, the external power supply circuit includes a converter and a first unidirectional conductive switch, the input end of the converter is connected to the input end of the external power supply circuit, the output end of the converter is connected to the anode of the first unidirectional conductive switch, and the cathode of the first unidirectional conductive switch is connected to the first output end of the external power supply circuit.

[0007] Optionally, the external power supply circuit further includes:

[0008] An external power clamp filter module; the input end of the converter is connected to the input end of the external power supply circuit through the external power clamp filter module;

[0009] and / or, a second capacitor; one end of the second capacitor is connected to the output end of the converter, and the other end of the second capacitor is grounded;

[0010] and / or, an inductor; one end of the second capacitor is connected to the output end of the converter through the inductor;

[0011] And / or, a sampling component; the sampling component comprises a first resistor, a second resistor and a feedforward capacitor, one end of the first resistor is connected to one end of the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and a feedback pin of a DC / DC converter chip included in the converter, and the other end of the second resistor is grounded; the feedforward capacitor is connected in parallel with the first resistor;

[0012] And / or, a fourth unidirectional conductive switch; the anode of the fourth unidirectional conductive switch is connected to the output end of the converter, the cathode of the fourth unidirectional conductive switch is connected to the second output end of the external power supply circuit, and the second output end of the external power supply circuit is used to connect a second load.

[0013] Optionally, one end of the second capacitor is connected to the inductor through a first power line, one end of the second capacitor is connected to the anode of the first unidirectional conductive switch through a second power line, and one end of the second capacitor is connected to the anode of the fourth unidirectional conductive switch through a third power line.

[0014] Optionally, the battery powered circuit comprises a battery and at least one of the following:

[0015] a second unidirectional conductive switch; an anode of the second unidirectional conductive switch is connected to the output terminal of the battery, and a cathode of the second unidirectional conductive switch is connected to the first output terminal of the battery power supply circuit;

[0016] A first switch tube; an input end of the first switch tube is connected to an output end of the battery, an output end of the first switch tube is connected to a first output end of the battery power supply circuit, and a control end of the first switch tube is connected to the first load;

[0017] a third unidirectional conductive switch; an anode of the third unidirectional conductive switch is connected to the output end of the battery, and a cathode of the third unidirectional conductive switch is connected to the second output end of the battery power supply circuit; the second output end of the battery power supply circuit is used to connect a second load.

[0018] Optionally, the battery power supply circuit further includes:

[0019] A second switch tube; an input end of the second switch tube is connected to an output end of the battery, an output end of the second switch tube is connected to a second output end of the battery power supply circuit, and a control end of the second switch tube is connected to the second load;

[0020] and / or, a third capacitor; one end of the third capacitor is connected to the output ends of the external power supply circuit and the battery power supply circuit respectively, and the other end of the third capacitor is grounded;

[0021] And / or, a fourth capacitor; the battery included in the battery power supply circuit is connected to the anodes of the second unidirectional conductive switch and the third unidirectional conductive switch respectively through one end of the fourth capacitor, and the other end of the fourth capacitor is grounded.

[0022] Optionally, the power supply system further includes a charging module, the output end of the charging module is connected to the charging end of the battery power supply circuit, and the input end of the charging module is connected to one end of a second capacitor included in the external power supply circuit;

[0023] And / or, the charging module is connected to a first load and / or a second load; the first load and / or the second load is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the output voltage is not within a preset range; the charging module is used to start upon receiving the charging instruction sent by the first load and / or the second load to charge the battery;

[0024] And / or, the power supply system also includes a processor, which is electrically connected to the charging module, and the processor is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the judgment is no.

[0025] Optionally, the capacitance value of the second capacitor is determined according to at least one of the following: a switching frequency of the converter, an operating current of the load, and a ripple current;

[0026] And / or, the impedance characteristic curve of the second capacitor matches the switching frequency of the converter.

[0027] Optionally, the power supply system further includes a first switch tube, an input end of the first switch tube is connected to an anode of the second unidirectional conductive switch, an output end of the first switch tube is connected to a cathode of the second unidirectional conductive switch, and a control end of the first switch tube is connected to the first load and / or the second load;

[0028] And / or, the power supply system further includes a second switch tube, an input end of the second switch tube is connected to an anode of the third unidirectional conductive switch, an output end of the second switch tube is connected to a cathode of the third unidirectional conductive switch, and a control end of the second switch tube is connected to the first load and / or the second load;

[0029] And / or, the power supply system further includes a third switch tube, an input end of the third switch tube is connected to the anode of the first unidirectional conductive switch, an output end of the third switch tube is connected to the cathode of the first unidirectional conductive switch, and a control end of the third switch tube is connected to the first load and / or the second load;

[0030] And / or, the power supply system also includes a fourth switch tube, the input end of the fourth switch tube is connected to the anode of a fourth unidirectional conductive switch included in the external power supply circuit, the output end of the fourth switch tube is connected to the cathode of the fourth unidirectional conductive switch, and the control end of the fourth switch tube is connected to the first load and / or the second load.

[0031] Optionally, the first load is an LTE module, and the second load is a GPS module; the power supply system further includes a normally closed low-voltage dropout linear regulator, and the output end of the external power supply circuit and the output end of the battery power supply circuit are connected to the GPS module through the low-voltage dropout linear regulator;

[0032] The LTE module is also in communication connection with the low-dropout linear regulator, and the LTE module is used to send an activation signal to the low-dropout linear regulator to activate the low-dropout linear regulator to supply power to the GPS module;

[0033] And / or, the power supply system further includes a processor, the processor is electrically connected to the low voltage dropout linear regulator, and the processor is used to send an enable signal to the low voltage dropout linear regulator to enable the low voltage dropout linear regulator to supply power to the GPS module;

[0034] And / or, the processor is electrically connected to control ends of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube respectively.

[0035] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0036] The positive progressive effect of the present invention is that the power supply system of the present invention provides two power supply modes for the load, namely, an external power supply and a battery. The two power supply modes supply power to the load respectively. Since a first capacitor is provided at the output end of the external power supply circuit and the battery power supply circuit, the output voltage is maintained based on the principle that the voltage across the capacitor cannot change suddenly and energy storage and discharge are carried out. This ensures that the two power supply modes are seamlessly connected to supply power to the load during the switching process of the two power supply modes, and there will be no load power-off phenomenon, power supply voltage drop phenomenon, etc. The embodiments of the present invention also have the advantages of low cost, high circuit reliability, and not prone to failure problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A circuit diagram of an external power supply circuit of a power supply system providing power to an LTE module according to an exemplary embodiment of the present invention;

[0038] Figure 2A circuit diagram of a power supply system for simultaneously supplying power to an LTE module and a GPS module is provided for an exemplary embodiment of the present invention;

[0039] Figure 3 A circuit diagram of a battery in a power supply system providing power to an LTE module according to an exemplary embodiment of the present invention;

[0040] Figure 4 A circuit diagram of a power supply system provided by an exemplary embodiment of the present invention, in which a battery supplies power to an LTE module and a GPS module at the same time;

[0041] Figure 5 A circuit diagram of a power supply system for supplying power to an LTE module and charging a battery at the same time, provided as an exemplary embodiment of the present invention;

[0042] Figure 6 A circuit diagram of a power supply system provided by an exemplary embodiment of the present invention for simultaneously supplying power to an LTE module and a GPS module and charging a battery;

[0043] Figure 7 A discharge curve diagram of a second capacitor C1 of a power supply system after a DC / DC converter is powered off, provided by an exemplary embodiment of the present invention;

[0044] Figure 8 A circuit diagram of a power supply system including a processor provided by an exemplary embodiment of the present invention;

[0045] Fig. 9 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0046] Fig.10 A circuit diagram of an external power supply circuit of a power supply system provided by an exemplary embodiment of the present invention for supplying power to an LTE module and a GPS module;

[0047] Fig.11 A top view of a PCB board of a power supply system provided by an exemplary embodiment of the present invention;

[0048] Fig.12 A cross-sectional view of a PCB board of a power supply system provided by an exemplary embodiment of the present invention;

[0049] Fig.13 A cross-sectional view of a PCB board of another power supply system provided by an exemplary embodiment of the present invention;

[0050] Fig.14 A circuit diagram of an external power supply circuit provided by an exemplary embodiment of the present invention for independently supplying power to an LTE module and a GPS module;

[0051] Fig.15 A schematic diagram of a loop gain curve of a DC / DC converter feedback system measured when a power supply system includes a feedforward capacitor provided by an exemplary embodiment of the present invention;

[0052] Fig.16 A transient response diagram of a load provided by a power supply system according to an exemplary embodiment of the present invention when the power supply system does not include a feed-forward capacitor;

[0053] Fig.17 A schematic diagram of a loop gain curve of a DC / DC converter feedback system measured when a power supply system includes a feedforward capacitor provided by an exemplary embodiment of the present invention;

[0054] Fig.18 A transient response diagram of a load that supplies power to a load when a power supply system includes a feed-forward capacitor provided by an exemplary embodiment of the present invention;

[0055] Fig.19 An actual power supply circuit diagram of an LTE module provided by an exemplary embodiment of the present invention;

[0056] Fig. 20 A power transition period variation waveform diagram of an LTE module provided by an exemplary embodiment of the present invention;

[0057] Fig.21 A schematic diagram of a ripple voltage of a power supply at a power supply end of an LTE module provided by an exemplary embodiment of the present invention;

[0058] Fig. 22 A schematic diagram of a ripple voltage of a power supply at a power supply end of another LTE module provided by an exemplary embodiment of the present invention;

[0059] Fig.23 A schematic diagram of the radiation value emitted by a vehicle-mounted wireless device in a test frequency band of 30MHz to 1GHz provided by an exemplary embodiment of the present invention;

[0060] Fig.24 A schematic diagram of test results of a static test of a GPS antenna of a wireless vehicle-mounted device in an open space is provided as a result of a static test of the GPS antenna of the wireless vehicle-mounted device in an open space according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0061] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0062] Prefixes such as "first" and "second" are used in the embodiments of the present invention only to distinguish different description objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of prefixes such as ordinal numbers to distinguish description objects in the embodiments of the present invention does not constitute a limitation on the described objects. For the statement of the described objects, please refer to the description in the context of the claims or embodiments, and no unnecessary limitation should be constituted due to the use of such prefixes. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0063] The embodiment of the present invention provides a power supply system, which includes an interface, an external power supply circuit, a battery power supply circuit and a first capacitor. The interface is used for an external power supply; the interface is also connected to the input end of the external power supply circuit, the output end of the external power supply circuit and the output end of the battery power supply circuit are both connected to a load through one end of the first capacitor, and the other end of the first capacitor is grounded.

[0064] The power supply system of the embodiment of the present invention provides two power supply modes for the load, namely, an external power supply and a battery. The two power supply modes supply power to the load respectively. Since a first capacitor is provided at the output end of the external power supply circuit and the battery power supply circuit, the output voltage is maintained based on the principle that the voltage across the capacitor cannot change suddenly and energy storage and discharge are carried out. This ensures that the two power supply modes are seamlessly connected to supply power to the load during the switching process of the two power supply modes, and there will be no load power-off phenomenon, power supply voltage drop phenomenon, etc. The embodiment of the present invention also has the advantages of low cost, high circuit reliability, and not prone to failure problems.

[0065] In this embodiment, the first capacitor may be a single capacitor; or may be obtained by connecting a plurality of capacitors in series and / or in parallel, and the capacitances of the capacitors may be the same or different.

[0066] The source power supply device of the embodiment of the present invention can supply power to one load or to multiple loads at the same time. When the source power supply device has the ability to supply power to multiple loads at the same time, the number of external power supply circuits and battery power supply circuits is multiple, and the number of external power supply circuits and battery power supply circuits matches the number of loads.

[0067] In one embodiment, each external power supply circuit includes a converter and a unidirectional conductive switch, the input end of the converter is connected to the input end of the external power supply circuit, the output end of the converter is connected to the input end of the unidirectional conductive switch, and the output end of the unidirectional conductive switch is connected to the output end of the external power supply circuit.

[0068] In one embodiment, each battery-powered circuit includes a battery and a unidirectional conductive switch, wherein an input end of the unidirectional conductive switch is connected to an output end of the battery, and an output end of the unidirectional conductive switch is connected to an output end of the battery-powered circuit.

[0069] The unidirectional conductive switch may be, but is not limited to, one of the following: an isolation diode, a triode, a MOSFET, an IGBT, a thyristor, a relay, etc. The converter may be, but is not limited to, one of the following: a DC / DC converter, a BOOST power converter, a BUCK-BOOST converter, a flyback isolation converter, etc.

[0070] When the traditional power supply circuit supplies power to multiple loads at the same time, there is also a fatal problem of instantaneous drop when multiple loads flip, which causes mutual interference between the loads due to the instantaneous drop problem, affecting the normal operation of the loads. The power supply system of the embodiment of the present invention adopts the output capacitor of the converter (energy storage capacitor + high-frequency capacitor) to separately lead out multiple power supply lines to supply power to each load respectively, and maintains the stability of the output voltage according to the negative feedback of the converter and the voltage stabilization system and the principle that the voltage at both ends of the capacitor cannot change suddenly and the energy storage discharge is used, successfully avoiding the problem of instantaneous drop caused by multiple loads working at the same time. And high-frequency capacitor filtering can filter out high-frequency noise generated by each load.

[0071] Combined with reasonable PCB layout and wiring, the power supply system also avoids the power drop problem caused by powering multiple loads at the same time.

[0072] The power supply system of the embodiment of the present invention can be applied to various scenarios, such as electric vehicles, industry, medical treatment, etc.

[0073] Combine the following Figure 1-7 , taking the example that the power supply system supplies power to two loads, the converter adopts a DC / DC converter, and the unidirectional conductive switch adopts an isolation diode, the power supply system is further explained.

[0074] The power supply system provides two power supply modes for the load: external power supply and battery power supply. The external power supply is implemented by an external power supply circuit, and the battery power supply is implemented by a battery power supply circuit. The external power supply mainly includes a DC / DC converter 94 and a first isolation diode D1. In addition, the external power supply can also include at least one of the following: an external cable 111, an external connector 92, an external power clamp filter module 91, and a second isolation diode D4. The battery power supply circuit mainly includes a battery 93. In addition, it also includes at least one of the following: a third isolation diode D2, a first switch tube Q1, a fourth isolation diode D3, and a second switch tube Q2.

[0075] The DC / DC converter 94 includes a DC / DC converter chip 90. In addition, the DC / DC converter 94 (or an external power supply circuit) may also include at least one of the following: a second capacitor C1, a freewheeling tube (or a built-in freewheeling tube of the DC / DC converter chip 90), an inductor L1, a sampling component, etc.

[0076] In one embodiment, the power supply system further includes a charging module 98 , which charges the battery 93 in combination with an external power source and a DC / DC converter 9 .

[0077] In an application scenario, the first load is the LTE module 95, and the second load is the GPS module 96. When powered by an external power supply, the 8V-100V power supply from the interface 70 is injected into the external connector 92 through the external power cable 111, and after internal clamping and filtering by the external power clamping filter module 91, it is input into the DC / DC converter 94, and after voltage reduction by the DC / DC converter 94, a stable voltage V1 (generally 5V) is generated by the second capacitor C1, which is divided into two paths: one path provides power V3 to the LTE module 95 through the isolation diode D1 and the first capacitor C5; the other path provides power V4 to the GPS module 96 through the isolation diode D4 and the third capacitor C4.

[0078] If the power supply system of this embodiment is applied to the field of electric vehicles, the interface may include but is not limited to a car interface, an electric bicycle, an electric motorcycle, a scooter, etc.

[0079] The DC / DC converter 94 may be, but is not limited to, a BUCK power topology, a BUCK-BOOST power topology, or a BOOST power topology. The second capacitor C1 may be, but is not limited to, at least one of the following: a 1 μF to 100 μF ceramic capacitor, a 2.2 μF to 2200 μF aluminum electrolytic capacitor, or a 2.2 μF to 2200 μF tantalum capacitor.

[0080] The parameters (e.g., capacitance) of the second capacitor C1 are determined according to the switching frequency of the DC / DC converter 94, the operating current of the load, and the ripple current. The parameters of the second capacitor C1 also need to consider the impedance characteristic curve of the ceramic capacitor. The impedance characteristic curve of the second capacitor C1 matches the switching frequency of the DC / DC converter, that is, the characteristic impedance of the second capacitor C1 is as close as possible to the switching frequency of the DC / DC converter 94. If an aluminum electrolytic capacitor is used, not only the impedance characteristic curve should be considered (the operating frequency of the aluminum electrolytic capacitor is below 1MHz, and the switching frequency of the DC / DC converter 94 exceeds 1MHz, so the aluminum electrolytic capacitor is not applicable), but also the ESR (series equivalent resistance) should be considered.

[0081] Function of the first isolation diode D1: When the battery 93 supplies power to the LTE module 95 and other loads through the second isolation diode D2, since the DC / DC converter 94 has no external power supply, the voltage at the output end E1 of the DC / DC converter 94 is zero, that is, the anode a voltage of the first isolation diode D1 is zero, and the cathode k voltage of the first isolation diode D1 is the power input voltage of the LTE module 95 and other loads. Therefore, the isolation diode D1 is cut off, which prevents the battery 93 from directly discharging into the DC / DC converter 94 and generating additional energy consumption when supplying power to the LTE module 95 and other loads.

[0082] Function of the fourth isolation diode D4: When the battery 93 supplies power to loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96 through the third isolation diode D3, since the DC / DC converter 94 has no external power supply, the voltage at the output terminal E1 of the DC / DC converter 94 is zero, that is, the anode a voltage of the fourth isolation diode D4 is zero, and the cathode k voltage of the fourth isolation diode D4 is the power input voltage of the loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96. Therefore, the fourth isolation diode D4 is cut off to prevent the battery 93 from directly discharging into the DC / DC converter 94 to generate additional energy consumption when supplying power to loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96.

[0083] Function of the second isolation diode D2: When the DC / DC converter 94 supplies power to the LTE module 95 load through the first isolation diode D1, since the second isolation diode D2 is arranged between the LTE module 95 and the battery 93, the load voltage of the LTE module 95 and other loads after the DC / DC converter 94 is isolated by the second isolation diode D2 is greater than the voltage of the battery 93, that is, the second isolation diode D2 is cut off, thereby preventing the DC / DC converter 94 from directly charging the battery 93 when supplying power to the LTE module 95 and other loads, and there is no need to set any charging management measures, thereby saving hardware costs and software-related settings.

[0084] Function of the third isolation diode D3: When the DC / DC converter 94 supplies power to loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96 through the fourth isolation diode D4, since the third isolation diode D3 is arranged between the low-dropout regulator (LDO) module 99 and the GPS module 96 and the battery 93, the voltage of the loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96 after the DC / DC converter 94 is isolated by the third isolation diode D3 is greater than the voltage of the battery 93, that is, the third isolation diode D3 is cut off, thereby preventing the DC / DC converter 94 from directly charging the battery 93 when supplying power to the loads such as the low-dropout regulator (LDO) module 99 and the GPS module 96, and there is no need to set any charging management measures, thereby saving hardware costs and software-related settings.

[0085] At pin 1 of the second capacitor C1 (pin 1 is the positive pole, output voltage V1), a power line is led out to the Vi input terminal of the charging module 98, the Vo output terminal of the charging module 98 is connected to the positive pole of the battery 93 (the charging end of the battery), and the negative pole of the battery 93 is grounded. The output C signal line of the LTE module 95 is connected to the e2 terminal of the charging module 98, and the LTE module 95 is used to send instructions to control the on and off states of the charging module 98 (that is, the two states of on and off). When the charging module 98 is in the on state, the battery is charged; when the charging module 98 is in the off state, the battery is stopped from being charged. Regarding stopping charging, the charging module 98 can stop charging the battery based on the instructions of the LTE module 95, or it can automatically stop charging the battery when it is determined that the battery is fully charged.

[0086] In another implementation, the charging module 98 may also be connected to the GPS module 96 for communication, and the GPS module 96 sends instructions to control the on / off state of the charging module 98 .

[0087] The power supply system of the embodiment of the present invention is divided into 6 different working conditions: ① The external power supply circuit supplies power to a load alone, such as the LTE module (such as Figure 1 ② The external power supply circuit supplies power to at least two loads at the same time, for example, the LTE module and the GPS module are powered at the same time (such as Figure 2 ③ The battery power supply circuit supplies power to a load alone, such as the LTE module (as shown in Figure 3 ④ The battery power supply circuit supplies power to at least two loads at the same time, for example, it supplies power to the LTE module and the GPS module at the same time (as shown in FIG. Figure 4 ⑤ The external power supply circuit supplies power to one load and charges the battery at the same time; ⑥ The external power supply circuit supplies power to at least two loads and charges the battery (as shown in Figure 6 shown).

[0088] The working principle of each working situation is analyzed as follows:

[0089] Working condition ①: The external power supply circuit supplies power to one load alone and the battery is not working

[0090] Taking the load as an LTE module as an example, the implementation is: the external power supply circuit supplies power to the LTE module 95 alone, and the battery 93 does not work.

[0091] Figure 1 A schematic diagram of an external power supply circuit supplying power to the LTE module alone is given. When powered by an external power supply, the 8V-100V power supply from the interface 70 is injected into the external connector 92 through the external power cable 111, and after internal clamping (suppressing surges and static electricity) and filtering (filtering out high-frequency noise) of the external power clamp filter module 91, it is input into the DC / DC converter 94, and after voltage reduction by the DC / DC converter 94, a stable voltage V1 (generally 5V) is generated by the output terminal E1 of the DC / DC converter 94 (the 1st pin of the second capacitor C1 is connected to the E1 terminal, and the 2nd pin of the second capacitor C1 is grounded), and the power supply voltage V7 is provided to the LTE module 95 through the isolation diode D1 and the first capacitor C5, and the working current in the dotted path of the power line is i1.

[0092] The LTE module 95 is connected to the LTE antenna 97a via the a1 terminal. When the LTE module 95 is working, the modulated radio frequency signal is radiated outward through the LTE antenna 97a, generating electromagnetic waves for wireless communication with the outside world.

[0093] The main voltage drop of the power supply line from the output terminal E1 of the DC / DC converter 94 to the power input terminal vd1 of the LTE module 95 is distributed across the cathode k and anode a of the first isolation diode D1, and generally a voltage drop of 0.5V to 0.7V is generated at the first isolation diode D1. If the output voltage V1 of the output terminal E1 of the DC / DC converter 94 is 5V, the power supply voltage range of the power input terminal vd1 of the LTE module 95 is calculated to be: 5V-0.5V=4.5V, 5V-0.7V=4.3V, that is, the voltage range obtained at pin 1 of the first capacitor C5 of the LTE module 95 is 4.3V to 4.5V.

[0094] Although the output terminal E1 of the DC / DC converter 94 is connected to the input terminal of the low-dropout linear regulator (LDO) module 99 through the fourth isolation diode D4, the GPS module 96 cannot be powered because the function of normally shutting down the low-dropout linear regulator (LDO) module 99 is set in the low-dropout linear regulator (LDO) module 99, and the GPS module 96 cannot work normally. The function realized at this time is that the DC / DC converter 94 alone powers the LTE module 95. When the LTE module sends a start signal to the low-dropout linear regulator, the low-dropout linear regulator starts to power the GPS module.

[0095] The enable signal B of the LTE module is connected to the e1 terminal of the low-dropout linear regulator (LDO) module 99. As long as the enable signal B of the LTE module does not send a start signal, the low-dropout linear regulator (LDO) module 99 cannot be turned on, that is, the GPS module 96 cannot work normally.

[0096] The positive electrode of the battery 93 is connected to the anode a of the second isolation diode D2, and the cathode k of the second isolation diode D2 is connected to the cathode k of the first isolation diode D1, the pin 1 of the first capacitor C5, and the power input terminal vd1 of the LTE module 95. The anode a of the first isolation diode D1 is connected to the pin 1 of the second capacitor C1. The positive electrode of the battery 93 is electrically connected to the pin 1 of the first capacitor C5, the pin 1 of the third capacitor C4, and the power input terminal vd1 of the LTE module 95 through the second isolation diode D2. However, since the voltage of the positive output voltage V4 of the battery 93 from the anode a and cathode k of the second isolation diode D2 to the power input terminal vd1 of the LTE module 95 is lower than the voltage from the output terminal E1 in the DC / DC converter 94 to the power input terminal vd1 of the LTE module 95, the second isolation diode D2 is not turned on. As long as the interface 70 provides power to the first load such as the LTE module 95 through the external cable 111 and the external power clamp filter module 91 through the DC / DC converter 94, the battery 93 will not work all the time, thus realizing the unidirectional power supply function of the external power supply. The battery 93 does not work normally and only serves as an emergency power supply, thereby extending the service life of the battery 93.

[0097] When the LTE module 95 is working and the GPS module 96 and the low-dropout linear regulator (LDO) module 99 are not working, the output power supply voltage V1 of the output terminal E1 in the DC / DC converter 94 is directly supplied to the LTE module 95 through the first isolation diode D1 and the first capacitor C5, generating a working current i8, which is processed by the baseband chip and the radio frequency chip inside the LTE module 95 to generate a radio frequency signal, which is radiated externally through the LTE antenna 97a to generate radio waves, realizing the LTE communication function; at this time, the B signal is output through the I / O pin of the LTE module 95 and connected to the EN pin of the low-dropout linear regulator (LDO) 99, so that the low-dropout linear regulator (LDO) 99 is in a closed state, and the GPS module 96 stops working. At this time, the output current of the second capacitor C1 is equal to the LTE module power supply current i8.

[0098] The input terminal Vi of the charging module 98 is connected to the output terminal E1 of the DC / DC converter 94 and the anode a of the first isolation diode D1, the output terminal Vo of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is grounded. However, since the LTE module 95 is connected to the enable terminal e2 of the charging module 98 through the enable signal C, as long as the LTE module 95 does not issue a charging instruction, the charging module 98 will not work and the battery 93 is in a disconnected state. In this way, the function of neither charging nor discharging the battery 93 is realized, which greatly extends the service life of the battery 93 (the number of times the battery 93 is charged and discharged will affect its service life).

[0099] The monitoring terminal ad of the LTE module 95 is connected to the output terminal E1 of the DC / DC converter 94. The DC / DC converter 94 supplies power to the LTE module 95 via the first isolation diode D1. As long as the LTE module 95 is in normal working state, the monitoring terminal ad of the LTE module 95 will always monitor whether the voltage of the output terminal E1 of the DC / DC converter 94 is within the normal range.

[0100] The first isolation diode D1 is generally a common silicon diode or a Schottky diode. The voltage drop of a common silicon diode is about 0.5V to 0.7V, and the voltage drop of a Schottky diode is about 0.2V to 0.5V. When calculating the output voltage of the DC / DC converter 94, the voltage drop (0.2V to 0.7V) of the first isolation diode D1 must be taken into account to ensure that the power supply voltage on the first capacitor C5 meets the minimum voltage of the LTE module 95 and ensures the normal operation of the LTE module 95; ensure that the operating voltage on the third capacitor C4 meets the low-dropout linear regulator (LDO) 99 to output a normal 1.8V voltage to meet the normal operation of the GPS module 96, and the current carrying capacity of the isolation diode D1 is greater than the operating current i8 of the LTE module 95 at full load and maximum transmission power, and a margin of more than 1 / 4 must be reserved to avoid burning out the isolation diode D1.

[0101] Working condition ②: The external power supply circuit supplies power to multiple loads at the same time and the battery is not working

[0102] Taking the load including LTE module and GPS module as an example, the external power supply circuit can supply power to LTE module and GPS module at the same time, and the battery does not work.

[0103] Figure 2 The following is a schematic diagram of an external power supply circuit that supplies power to both the LTE module and the GPS module. Figure 1 The difference between the solutions in Figure 2 exist Figure 1 The scheme also adds a DC / DC converter 94 to power the low-dropout linear regulator (LDO) module 99 and the GPS module 96. The pin 1 of the third capacitor C4 is connected to the cathode k of the third isolation diode D3 and the cathode k of the fourth isolation diode D4. The anode a of the third isolation diode D3 is connected to the pin 2 of the fourth capacitor C2 and the switch K1, and the pin 1 of the switch K1 is connected to the positive electrode of the battery 93; the anode a of the fourth isolation diode D4 is connected to the output terminal E1 of the DC / DC converter 94. The total output current of the output terminal E1 of the DC / DC converter 94 is i1, the working current from the output terminal E1 of the DC / DC converter 94 to the power supply terminal vd1 of the LTE module 95 is i8, and the voltage at the pin 1 of the first capacitor C5 of the LTE module 95 and the power supply terminal vd1 of the LTE module 95 is V7; the working current from the cathode k of the fourth isolation diode D4 to the pin 1 of the third capacitor C4 of the low voltage difference linear regulator (LDO) module 99 is i2, and the voltage at the third capacitor C4 of the low voltage difference linear regulator (LDO) module 99 is V7. The voltage of the 1st pin of the LTE module is V8; since the DC / DC converter 94 first supplies power to the LTE module 95 through the first isolation diode D1 when the power is turned on, after the LTE module 95 is started, the e1 end of the low-voltage difference linear regulator (LDO) module 99 is turned on through the enable signal B of the LTE module, so that the low-voltage difference linear regulator (LDO) module 99 supplies power to the power supply end vd2 of the GPS module, and the GPS module is connected to the GPS antenna 97b through the a2 end to generate electromagnetic waves to receive weak signals transmitted from the earth's near-orbit satellite. Since the operating frequency of the LTE module 95 is 700MHz~2.7GHz, and the current consumption is large, the response to the power supply is very high, so the voltage on the 1st pin of the first capacitor C5 fluctuates greatly; the operating current of the GPS module is small, and the voltage on the 1st pin of the third capacitor C4 of the low-voltage difference linear regulator (LDO) module 99 fluctuates less, so there is a certain difference between the voltage V7 on the 1st pin of the first capacitor C5 and the voltage V81 on the 1st pin of the third capacitor C4.

[0104] The input terminal Vi of the charging module 98 is connected to the output terminal E1 of the DC / DC converter 94, the output terminal Vo of the charging module 98 is connected to the positive electrode of the battery 93, and the negative electrode of the battery 93 is grounded. However, since the LTE module 95 is connected to the enable terminal e2 of the charging module 98 through the enable signal C, as long as the LTE module 95 does not issue a charging instruction, the charging module 98 will not work, and the battery 93 is in a disconnected state, realizing the function of neither charging nor discharging the battery 93, thereby greatly extending the service life of the battery 93.

[0105] Working condition ③: The battery supplies power to one load alone

[0106] Taking the power supply to the LTE module as an example, when the battery alone powers the LTE module, how to reduce the loss in the battery power supply path and the impact of the drop problem caused by the large dynamic response of the LTE module (first load) on the GPS module (second load) are issues that need to be considered. The power supply system provided by the embodiment of the present invention can achieve the following functions:

[0107] A. The battery can supply power to the first load independently, thus reducing the loss in the battery power supply path;

[0108] B. Reduce the battery power supply, and the large dynamic response of the first load will cause the drop problem to affect the second load.

[0109] The following provides a method for implementing a battery to power the LTE module alone and reduce the loss in the battery power supply path.

[0110] The power supply circuit also includes a first switch tube, the input end of the first switch tube is connected to the anode of the second isolation diode, the output end of the first switch tube is connected to the cathode of the second isolation diode, and the control end of the first switch tube is connected to the first load and / or the second load. The first switch tube can be, but is not limited to, a triode, a thyristor, a MOSFET, an IGBT, a relay, etc.

[0111] The following example takes the connection between the LTE module and the control terminal of the first switch tube, where the first switch tube is a PNP transistor, as an example. Figure 3, the process of the battery supplying power to the LTE module alone is explained. The cathode k and anode a of the second isolation diode D2 are connected to the e pin and c pin of the PNP transistor Q1 respectively, that is, a transistor Q1 is connected across the cathode k and anode a of the second isolation diode D2. Since the normal voltage of the battery 93 is only between 3.3V and 4.2V, and the stored energy is limited, when the battery 93 supplies power to the LTE module 95 through the second isolation diode D2, a voltage drop of 0.5V to 0.7V will be generated in the second isolation diode D2, resulting in a low working voltage transmitted to the LTE module 95, that is, 3.3V to 4.2V minus a voltage drop of 0.5V to 0.7V, which brings two hazards: the first is that the limited energy stored in the battery 93 is consumed, resulting in a shorter battery life of the battery 93; when the voltage of the battery 93 is as low as 3.3V, if the maximum voltage drop of 0.7V is subtracted, only a working voltage of 2.6V can be obtained in the LTE module 95. , it is very likely that the LTE module 95 cannot work normally, so we need to find a way to reduce the voltage drop across the cathode a and the anode k of the second isolation diode D2. Therefore, a transistor Q1 with a certain power can be connected across the cathode k and the anode a of the second isolation diode D2. When the second isolation diode D2 is turned on, as long as the LTE module 95 sends an enable signal A to the b pin of the transistor Q1, the transistor Q1 is turned on. At this time, the working current i5 between the battery 93 and the power supply terminal vd1 of the LTE module 95 is divided into two paths, one path passes through the anode a of the second isolation diode D2 to the cathode k, and the other path passes through the e pin of the transistor Q1 to the c pin. Finally, the two currents are connected to the cathode k of the second isolation diode D2 and the c pin of the transistor Q1 to the power supply terminal vd1 of the LTE module 95. Since the voltage drop between the e pin and the c pin of the transistor Q1 is reduced to 0.1V~0.15V, the working current in the transistor Q1 is dominant.

[0112] a. Take the selection of the second isolation diode D2 as a common silicon diode as an example for explanation:

[0113] Taking the voltage drop (referring to the voltage difference) across the anode a and cathode k of the second isolation diode D2 as a minimum of 0.5V and the voltage drop (referring to the voltage difference) across the c pin and e pin of the transistor Q1 as a minimum of 0.1V as an example, the voltage drop across the anode a and cathode k of the second isolation diode D2 / the voltage drop Uce across the c pin and e pin of the transistor Q1 can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0114]

[0115] Taking the voltage drop (voltage difference) across the anode a and cathode k of the second isolation diode D2 as 0.7V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor Q1 as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D2 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0116]

[0117] At this time, the voltage drop range of the power path from the battery 93 to the power terminal vd1 of the LTE module 95 is approximately between 0.0833 and 0.1235V. The operating voltage of the power terminal vd1 transmitted from the battery 93 to the LTE module 95 is the battery voltage 3.3V to 4.2V minus the voltage drop of 0.0833 to 0.1235V. The operating voltage range of the LTE module 95 is approximately 3.1765V to 4.1167V. At this time, the consumption of energy stored in the battery 93 has been greatly reduced, and the battery life and service life of the battery 93 have been greatly extended. Even if the voltage of the battery 93 is as low as 3.3V, a voltage of 3.1765V can be obtained at the power terminal vd1 of the LTE module 95, which can basically meet the minimum operating voltage requirement.

[0118] b. Take the isolation diode D2 as an example to explain the selection of Schottky diode:

[0119] Taking the voltage drop (referring to the voltage difference) across the anode a and cathode k of the second isolation diode D2 as a minimum of 0.2V and the voltage drop (referring to the voltage difference) across the c pin and e pin of the transistor Q1 as a minimum of 0.1V as an example, the voltage drop across the anode a and cathode k of the second isolation diode D2 / the voltage drop across the c pin and e pin of the transistor Q1 can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0120]

[0121] Taking the voltage drop (referring to the voltage difference) across the anode a and cathode k of the second isolation diode D2 as a maximum of 0.5V and the voltage drop (referring to the voltage difference) across the c pin and e pin of the transistor Q1 as a maximum of 0.15V as an example, the voltage drop across the anode a and cathode k of the second isolation diode D2 / the voltage drop across the c pin and e pin of the transistor Q1 can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0122]

[0123] At this time, the voltage drop range of the power path from the battery 93 to the power terminal vd1 of the LTE module 95 is approximately between 0.06667V and 0.11538V. The working voltage of the power terminal vd1 transmitted from the battery 93 to the LTE module 95 is the battery voltage 3.3V to 4.2V minus the voltage drop of 0.06667V to 0.11538V. The working voltage range of the LTE module 95 is approximately 3.23333V to 4.133332V. At this time, the consumption of energy stored in the battery 93 has been greatly reduced, and the battery life and service life of the battery 93 have been greatly extended. Even if the voltage of the battery 93 is as low as 3.3V, a voltage of 3.23333V can be obtained at the power terminal vd1 of the LTE module 95, which can basically meet the minimum working voltage requirement.

[0124] It should be noted that under normal circumstances, pin 1 and pin 2 of switch K1 are closed, that is, pin 1 and pin 2 of switch K1 are connected. The function of switch K1 is that when the vehicle-mounted equipment is not used for a long time, switch K1 can be disconnected to prevent the battery 93 from supplying power to the power supply terminal vd1 of the LTE module 95 through the switch K1 and the second isolation diode D2, and to prevent the battery 93 from supplying power to the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96 through the switch K1 and the third isolation diode D3, so as to extend the service life of the battery 93.

[0125] The following provides a method for reducing the impact of the drop problem caused by the large dynamic response of the first load on the second load when the battery supplies power to multiple loads at the same time.

[0126] Figure 4 The following is a schematic diagram of the battery powering both the LTE module and the GPS module. Figure 3 Comparison of the schemes in Figure 4 The solution in the embodiment simultaneously adds a battery 93 to power the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96, and the operating current generated by the power path between the battery 93 and the 1-pin of the fourth capacitor C2 is i5. The voltage at the power supply terminal vd1 of the LTE module 95 and the 1-pin of the first capacitor C5 is V71, and the operating current generated between the 1-pin of the fourth capacitor C2 and the power supply terminal vd1 of the LTE module 95 is i7; the voltage generated at the input terminal of the low-voltage difference linear regulator (LDO) module 99 and the 1-pin of the third capacitor C4 is V81, and the operating current generated between the 1-pin of the fourth capacitor C2 and the input terminal of the low-voltage difference linear regulator (LDO) module 99 and the 1-pin of the third capacitor C4 is i6. The relationship between the working current i7 generated between pin 1 of the fourth capacitor C2 and the power supply terminal vd1 of the LTE module 95 and the working current i6 generated between pin 1 of the fourth capacitor C2 and pin 1 of the third capacitor C4 of the low dropout linear regulator (LDO) 99 satisfies: i5=i7+i6.

[0127] At this time, the LTE module 95 sends a start signal A to the enable terminal e1 of the low-voltage difference linear regulator (LDO) 99, and the low-voltage difference linear regulator (LDO) 99 starts to supply power to the power terminal vd2 of the GPS module 96. The GPS module 96 works normally and is connected to the GPS antenna through the a2 terminal. The GPS antenna receives the weak signal transmitted by the earth orbit satellite and provides the device with location information to realize the GPS positioning function.

[0128] Figure 3 The other parts of the solution have the same functions as Figure 4 Basically the same, no repetitive description is given.

[0129] Working condition ⑤: External power circuit powers the LTE module and charges the battery

[0130] Figure 5 The schematic diagram of the external power supply circuit to power the LTE module and charge the battery at the same time is given. Figure 1 Comparison of the schemes in Figure 5 The solution in the embodiment also adds an external power supply circuit and a functional signal flow diagram of the charging module 98 charging the battery 93.

[0131] The battery voltage detection terminal ab of the LTE module 95 is connected to the positive output terminal of the battery 93. As long as the LTE module 95 is in normal working condition, the battery voltage detection terminal ab of the LTE module 95 will always monitor the output voltage of the battery 93, and judge whether the working condition of the battery 93 is normal by judging whether the output voltage is within a preset range. The preset range can be set according to actual conditions, for example, set to [0V, 3.3V]. Among them, 3.3V is the discharge threshold voltage of the battery.

[0132] ①Whether the battery 93 is lower than the discharge threshold voltage (for example, the discharge threshold voltage of a lithium battery is 3.3V) during the process of supplying power to the LTE module 95 and other loads (discharging process). If it is lower than the discharge threshold voltage, the connection between the battery 93 power supply system and the load is disconnected; because the battery 93 is lower than the discharge threshold voltage, the output voltage V4 of the battery 93 will be lower than the normal value, and the LTE module 95 and other loads will obtain a voltage lower than the working power supply voltage, resulting in failure to work normally; at the same time, if the battery 93 continues to supply power to the LTE module 95 and other loads when the voltage is lower than the discharge threshold voltage, the service life of the battery 93 will be greatly shortened; ②The external power supply circuit supplies power to the battery 93 via the charging module 98. During the charging process of battery 93, the battery voltage detection terminal a of LTE module 95 constantly monitors whether the output voltage of battery 93 exceeds the charging threshold voltage (for example, the charging threshold voltage of lithium battery is 4.2V). Once the battery voltage detection terminal a of LTE module 95 constantly monitors whether the output voltage of battery 93 exceeds the charging threshold voltage (for example, the charging threshold voltage of lithium battery is 4.2V), LTE module 95 sends a shutdown signal C to the enable terminal e2 of charging module 98, so that charging module 98 stops charging battery 93, so as to avoid affecting the service life of battery 93 and prevent battery 93 from being overcharged, causing fire, explosion and other serious accidents.

[0133] Therefore, the function of the battery voltage detection terminal ab of the LTE module 95 is very important. It can not only ensure the safety of the battery 93 during the charging process (not overcharging), but also ensure the safety of the battery 93 during the discharging process (not overdischarging), while extending the service life of the battery 93.

[0134] The relationship between the working current i38 from the output terminal E1 of the DC / DC converter 94 to the anode a of the first isolation diode D1, the charging current i8 from the anode a of the first isolation diode D1 to the Vi terminal of the charging module 98, the Vo terminal of the charging module 98 to the positive electrode of the battery 93, the negative electrode of the battery 93 to the ground, the anode a of the first isolation diode D1, the cathode k of the first isolation diode D1 to the working current i3 of the first capacitor C5 of the LTE module 95 satisfies:

[0135] i38=i8+i3;

[0136] The relationship between the total current i1 at the output terminal E1 of the DC / DC converter 94, the operating current i2 between the output terminal E1 of the DC / DC converter 94 and the fourth isolation diode D4 and the input terminal of the low-dropout linear regulator (LDO) 99, and the operating current i38 between the output terminal E1 of the DC / DC converter 94 and the anode a of the first isolation diode D1 satisfies:

[0137] i1=i2+i38;

[0138] When the battery voltage detection terminal ab of the LTE module 95 detects that the positive output terminal V4 of the battery 93 is lower than the threshold voltage of the battery 93, the C-terminal signal routing of the LTE module 95 sends a start signal C to the enable terminal e2 of the charging module 98, and the charging module 98 starts the function of charging the battery 93. The LTE module 95 does not send a start signal A to the enable terminal e1 of the low-dropout linear regulator (LDO) 99 of the LTE module 95, the low-dropout linear regulator (LDO) 99 is in the off state, and the GPS module 96 is in the off state. Since in the charging state, the voltage of the positive electrode voltage V4 of the battery 93 to the power supply terminal vd1 of the LTE module 95 through the isolation diode D2 and / or the transistor Q1 does not exceed the voltage of the output terminal E1 of the DC / DC converter 94 to the power supply terminal vd1 of the LTE module 95 through the isolation diode D1, the second isolation diode D2 and / or the transistor Q1 are in the off state, and the battery 93 in the charging state does not discharge. In summary, the function of the external power supply circuit to power the LTE module and charge the battery is realized. At the power supply terminal vd1 of the LTE module 95, the voltage at the pin 1 of the first capacitor C5 is V7, and the voltage at the pin 1 of the third capacitor C4 of the low dropout linear regulator (LDO) 99 is V81.

[0139] Figure 5 The other parts of the solution have the same functions as Figure 1 Basically the same, no repetitive description is given.

[0140] Working condition ⑥: The external power circuit supplies power to multiple loads and charges the battery at the same time

[0141] Taking the load including an LTE module and a GPS module as an example, the external power supply circuit supplies power to the LTE module and the GPS module and charges the battery.

[0142] Figure 6 The schematic diagram of the external power supply circuit for powering the LTE module and GPS module and charging the battery is given. Figure 5 Comparison of the schemes in Figure 6 The solution in the embodiment also adds the function of supplying power to the low-dropout linear regulator (LDO) 99 and the GPS module. The working current i38 from the output terminal E1 of the DC / DC converter 94 to the anode a of the first isolation diode D1 and the charging current i8 from the anode a of the first isolation diode D1 to the Vi terminal of the charging module 98, the Vo terminal of the charging module 98 to the positive electrode of the battery 93, the negative electrode of the battery 93 to the ground, the anode a of the first isolation diode D1 to the cathode k of the first isolation diode D1, and the working current i3 between the power supply terminal vd1 of the LTE module 95 satisfy the following relationship:

[0143] i38=i8+i3;

[0144] When the battery voltage detection terminal ab of the LTE module 95 detects that the positive output terminal V4 of the battery 93 is lower than the threshold voltage of the battery 93, the C-terminal signal routing of the LTE module 95 sends a start signal C to the enable terminal e2 of the charging module 98, and the charging module 98 starts the function of charging the battery 93. The LTE module 95 sends a start signal A to the enable terminal e1 of the low-dropout linear regulator (LDO) 99, the low-dropout linear regulator (LDO) 99 is in the on state, and the GPS module 96 is in the working state.

[0145] In the charging state, the voltage of the positive electrode voltage V4 of the battery 93 to the power supply terminal vd1 of the LTE module 95 through the second isolation diode D2 and / or transistor Q1 does not exceed the voltage of the output terminal E1 of the DC / DC converter 94 to the power supply terminal vd1 of the LTE module 95 through the first isolation diode D1, so the second isolation diode D2 / transistor Q1 and the third isolation diode D3 / transistor Q2 are in the cut-off state, and the battery 93 in the charging state does not discharge to the power supply terminal vd1 of the LTE module 95. In the charging state, the voltage of the positive electrode voltage V4 of the battery 93 to the input terminal of the low-voltage dropout linear regulator (LDO) 99 through the third isolation diode D3 / transistor Q2 does not exceed the voltage of the output terminal E1 of the DC / DC converter 94 to the input terminal of the low-voltage dropout linear regulator (LDO) 99 through the fourth isolation diode D4, so the third isolation diode D3 / transistor Q2 is in the cut-off state, and the battery 93 in the charging state does not discharge to the low-voltage dropout linear regulator (LDO) 99 and the GPS module 96. In summary, the external power supply circuit is used to power the LTE module and the GPS module, and to charge the battery at the same time.

[0146] At the power supply terminal vd1 of the LTE module 95 , the voltage at the pin 1 of the first capacitor C5 is V7 , and the voltage at the pin 1 of the third capacitor C4 of the low dropout linear regulator (LDO) 99 is V81 .

[0147] Figure 6 The other parts of the solution have the same functions as Figure 5 Basically the same, no repetitive description is given.

[0148] The following describes an implementation method for automatically switching the power supply mode of the power supply system, and automatically switching from an external power supply circuit to a battery power supply circuit to supply power to a load.

[0149] like Figure 3As shown, the battery 93 supplies power to the power supply terminal vd1 of the LTE module 95 via the fourth capacitor C2, the second isolation diode D2, and the first capacitor C5, which is a separate and complete battery power supply circuit path. The interface 70, the external cable 111, the external power clamp filter module 91, the DC / DC converter 94, the first isolation diode D1, and the first capacitor C5 supply power to the LTE module 95 separately, which is a separate and complete external power supply circuit path. The battery power supply circuit path and the external power supply circuit path are two independent power supply paths.

[0150] like Figure 1 , Figure 3 As shown, once the interface 70 disconnects the external power supply, the DC / DC converter 94 will stop working. Since there is no DC / DC converter 94 to replenish energy for the second capacitor C1, as the discharge voltage of the second capacitor C1 continues to decrease, when the voltage of the discharge voltage V1 from the output terminal E1 of the DC / DC converter 94 is lower than the voltage from the battery 93 to the 1st pin of the fourth capacitor C2 (voltage is V4), the anode a of the second isolation diode D2, the cathode k of the isolation diode D2 to the power terminal vd1 of the LTE module 95, the first isolation diode D1 is cut off at this time, and the battery 93 is used to supply power to the LTE module 95 via the second isolation diode D2. The working current i8 generated in the path from the battery 93, the second isolation diode D2, the transistor Q1 to the power terminal vd1 of the LTE module 95 is the working current flowing into the LTE module 95. In this way, the power supply from the external power supply circuit to the battery for the LTE module 95 is automatically switched, and the connection is seamless. During the switching process, the LTE module 95 does not have a power outage problem, and the LTE module 95 will not be disconnected from the network. The load power supply function is seamlessly switched from the external power supply circuit to the battery, without manual intervention, saving costs, and having reliable performance.

[0151] Figure 7 A discharge curve diagram of the second capacitor C1 after the DC / DC converter 94 is powered off is shown.

[0152] like Figure 2 , Figure 4As shown, once the interface 70 disconnects the external power supply, the DC / DC converter 94 will stop working. Since there is no DC / DC converter 94 to replenish energy for the second capacitor C1, as the discharge voltage of the second capacitor C1 continues to decrease, when the voltage of the discharge voltage V1 from the output terminal E1 of the DC / DC converter 94 through the anode a of the first isolation diode D1, the cathode b of the first isolation diode D1 to the power terminal vd1 of the LTE module 95 is lower than the voltage from the battery 93 to the 1st pin of the fourth capacitor C2 (the voltage is V4), the anode a of the second isolation diode D2, the cathode b of the second isolation diode D2 to the power terminal vd1 of the LTE module 95, at this time, the first isolation diode D1 is cut off, and the battery 93 provides power to the LTE module 95 through the second isolation diode D2. The working current i8 generated in the path of the battery 93, the second isolation diode D2, the transistor Q1 to the power terminal vd1 of the LTE module 95 is the working current flowing into the LTE module 95. As the discharge voltage of the second capacitor C1 continues to decrease, when the voltage of the discharge voltage V1 at the output end E1 of the DC / DC converter 94 is lower than the voltage from the battery 93 to the 1st pin of the fourth capacitor C2 (voltage is V4), the anode a of the third isolation diode D3, the cathode k of the third isolation diode D3 to the input end of the low voltage difference linear regulator (LDO) 99 through the anode a of the fourth isolation diode D4 and the cathode k of the fourth isolation diode D4, the fourth isolation diode D4 is cut off at this time, and the low voltage difference linear regulator (LDO) 99 and the GPS module 96 are powered by the battery 93 through the third isolation diode D3. In this way, the power supply from the external power supply circuit to the LTE module 95, the low-voltage difference linear regulator (LDO) 99 and the GPS module 96 is automatically switched to the battery to power the LTE module 95, the low-voltage difference linear regulator (LDO) 99 and the GPS module 96, and the connection is seamless. During the switching process, the LTE module 95 and the GPS module 96 do not have a power outage problem, and the LTE module 95 and the GPS module 96 will not be disconnected from the network. The function of seamlessly switching from the external power supply circuit to the battery to supply power to the load is achieved without manual intervention, saving costs, and having reliable performance.

[0153] like Figure 1 As shown, the voltage V1 of the output terminal E1 of the DC / DC converter 94 normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode k of the first isolation diode D1 is 0.7V (ordinary silicon diode), and the voltage drop between the anode a and the cathode k of the second isolation diode D2 is 0.7V (ordinary silicon diode) as an example for explanation:

[0154] When the interface 70 is disconnected from the external power supply, the voltage V1 at the output terminal E1 of the DC / DC converter 94 is still 5V. At this time, the discharge voltage from the second capacitor C1 obtained at the power supply terminal vd1 of the LTE module 95 is V1-0.7V=5V-0.7V=4.3V, that is, the voltage at the power supply terminal vd1 of the LTE module 95 (connected to the 1st pin of the first capacitor C5) is 4.3V; and at this time, the voltage V4 (4.2V) of the battery 93 is V4-0.5V=4.2V-0.7V=4.2V-0.7V= at the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2. 3.5V, because at this time the voltage V1 of the output terminal E1 of the DC / DC converter 94 is 4.3V from the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95, which is greater than the voltage V4 of the battery 93 (3.5V from the fourth capacitor C2 and the second isolation diode D2) at the power supply terminal vd1 of the LTE module 95. Therefore, although the DC / DC converter 94 does not continue to charge the second capacitor C1 (replenish energy to the second capacitor C1), the second capacitor C1 still continues to discharge to the power supply terminal vd1 of the LTE module 95 through the first isolation diode D1, and at the same time charges the first capacitor C5 to power the LTE module 95. Until the voltage V1 at the output terminal E1 of the DC / DC converter 94 is lower than the threshold value of 3.5V through the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95, and at this time, the voltage V4 (4.2V) of the battery 93 is discharged to the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2, and at the same time, the first capacitor C5 is charged to supply power to the LTE module 95, and at this time, the voltage V1 at the output terminal E1 of the DC / DC converter 94 is reversely estimated to be 3.5V+0.7V=4.2V, that is, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 is lower than 4.2V, the voltage V4 (4.2V) of the battery 93 is discharged to the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2, and at the same time, the first capacitor C5 is charged to supply power to the LTE module 95. After the DC / DC converter 94 is powered off, the second capacitor C1 continues to charge the first capacitor C5 and supply power to the LTE module 95. When the power supply is lower than a certain threshold, the DC / DC converter 94 power supply mode is automatically switched to the battery 93 power supply mode. During the switching process, the load is not powered off and the LTE module 95 is not disconnected from the network.

[0155] like Figure 1 As shown, the voltage V1 of the output terminal E1 of the DC / DC converter 94 normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode k of the isolation diode D1 is 0.5V (Schottky diode), and the voltage drop between the anode a and the cathode b of the isolation diode D2 is 0.5V (Schottky diode) as an example for explanation:

[0156] When the interface 70 is disconnected from the external power supply, the voltage V1 at the output terminal E1 of the DC / DC converter 94 is still 5V. At this time, the discharge voltage from the second capacitor C1 obtained at the power supply terminal vd1 of the LTE module 95 is V1-0.5V=5V-0.5V=4.5V, that is, the voltage at the power supply terminal vd1 of the LTE module 95 (connected to the 1st pin of the first capacitor C5) is 4.5V; and at this time, the voltage V4 (4.2V) of the battery 93 is V4-0.7V=4.2V-0.5V=4.2V-0.5V at the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2. =3.7V, since at this time the voltage V1 at the output terminal E1 of the DC / DC converter 94 is 4.5V via the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95, which is greater than the voltage V4 of the battery 93 via the fourth capacitor C2 and the second isolation diode D2 at the power supply terminal vd1 of the LTE module 95 3.7V, therefore, although the DC / DC converter 94 does not continue to charge the second capacitor C1 (replenish energy to the second capacitor C1), the second capacitor C1 still continues to discharge to the power supply terminal vd1 of the LTE module 95 via the first isolation diode D1, and at the same time charges the first capacitor C5 to power the LTE module 95. Until the voltage V1 at the output terminal E1 of the DC / DC converter 94 is lower than the threshold value of 3.7V through the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95, and at this time, the voltage V4 (4.2V) of the battery 93 is discharged to the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2, and at the same time, the first capacitor C5 is charged to supply power to the LTE module 95, and at this time, the reverse estimation of the voltage V1 at the output terminal E1 of the DC / DC converter 94 is 3.7V+0.5V=4.2V, that is, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 is lower than 4.2V, the voltage V4 (4.2V) of the battery 93 is discharged to the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2, and at the same time, the first capacitor C5 is charged to supply power to the LTE module 95. After the DC / DC converter 94 is powered off, the second capacitor C1 continues to charge the first capacitor C5 and supply power to the LTE module 95. When the power supply is lower than a certain threshold, the DC / DC converter 94 power supply mode is automatically switched to the battery 93 power supply mode. During the switching process, the load is not powered off and the LTE module 95 is not disconnected from the network.

[0157] The following describes the implementation method of automatically switching the power supply mode of the power supply system, which automatically switches the power supply of the load from the battery to the external power supply circuit.

[0158] like Figure 1 , Figure 3As shown, if the battery 93 supplies power to the LTE module 95 via the fourth capacitor C2, the second isolation diode D2 and / or the transistor Q1, and the first capacitor C5, once the interface 70 is connected to the external power supply, the DC / DC converter 94 will start working immediately, and at the same time, the DC / DC converter 94 will replenish energy to the second capacitor C1. As the charging voltage V1 of the second capacitor C1 continues to increase, when the charging voltage V1 of the output terminal E1 of the DC / DC converter 94 passes through the anode a of the first isolation diode D1 and the cathode k of the first isolation diode D1 to the voltage of the power supply terminal vd1 of the LTE module 95, When the voltage is higher than the voltage from the battery 93 to pin 1 of the fourth capacitor C2 (voltage is V4), the anode a of the second isolation diode D2, the cathode k of the second isolation diode D2 (and / or the e pin and c pin of the transistor Q1) to the power supply terminal vd1 of the LTE module 95, the first isolation diode D1 is turned on, and the DC / DC converter 94 provides power to the LTE module 95 via the first isolation diode D1. The working current i8 generated in the path of the DC / DC converter 94, the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95 is the working current flowing into the LTE module 95.

[0159] like Figure 1 As shown, the voltage V1 of the output terminal E1 of the DC / DC converter 94 normally outputs 5V, the battery voltage is 4.2V, the voltage drop between the anode a and the cathode k of the first isolation diode D1 is 0.5V (Schottky diode), and the voltage drop between the anode a and the cathode k of the second isolation diode D2 is 0.5V (Schottky diode) as an example for explanation:

[0160] During the power-off period of the interface 70, the voltage V4 (4.2V) of the battery 93 is V4-0.5V=4.2V-0.5V=4.2V-0.5V=3.7V at the power supply terminal vd1 of the LTE module 95 through the fourth capacitor C2 and the second isolation diode D2, that is, the power supply voltage obtained at the power supply terminal vd1 (load terminal) of the LTE module 95 is 3.7V. Once the interface 70 is connected to the external power supply, the DC / DC converter 94 will start working, and at the same time, the DC / DC converter 94 will replenish energy to the second capacitor C1. As the discharge voltage of the second capacitor C1 continues to increase, when the discharge voltage of the output terminal E1 of the DC / DC converter 94 passes through the anode a of the first isolation diode D1 and the cathode k of the first isolation diode D1 to the power supply terminal vd1 of the LTE module 95, the voltage exceeds the threshold voltage of 3.7V, the second isolation diode D2 is turned off, that is, the battery 93 stops supplying power to the power supply terminal vd1 (load terminal) and automatically switches to the external power supply circuit for power supply. It can be reversely deduced: the voltage of the power supply terminal vd1 of the LTE module 95 is 3.7V + the 0.5V voltage drop of the first isolation diode D1 = 4.2V, that is, during the period when the DC / DC converter 94 replenishes energy to the second capacitor C1, as long as the voltage of the output terminal E1 of the DC / DC converter 94 exceeds the charging threshold voltage of 4.2V, the battery stops supplying power to the power supply terminal vd1 (load terminal) and automatically switches to the external power supply circuit for power supply. In this way, the power supply from the battery to the LTE module 95 is automatically switched to the external power supply circuit for powering the LTE module 95, and it is seamless. During the switching process, the LTE module 95 does not have a power outage problem, and there will be no LTE disconnection phenomenon, realizing the seamless connection from the battery to the external power supply circuit to supply power to the load, without manual intervention, saving costs, and reliable performance.

[0161] In one embodiment, the power supply system further includes a processor, which is responsible for monitoring and controlling other components included in the power supply system. Of course, the processor can also serve as a load of the power supply system, and the power supply system supplies power to the processor. The processor can be, but is not limited to, a microprocessor. Figure 8 The circuit diagram of the power supply system mainly composed of microprocessor module, LTE module, GPS module, battery power supply circuit and external power supply circuit is given. Figure 1 to Figure 6 Comparison of the schemes in Figure 8 The solution in the embodiment adds a set of microprocessor modules 101, low dropout linear regulator (LDO) modules 78 and other loads. Figure 1 to Figure 6The LTE module 95 in the embodiment can be integrated with the microprocessor to form a microprocessor module, or the LTE module 95 can be deployed separately from the microprocessor. If the LTE module 95 has a built-in microprocessor module, the monitoring terminal ad of the LTE module 95 (used to monitor the output voltage of the DC / DC converter 94) and the battery voltage detection terminal ab of the LTE module 95 can be integrated into the LTE module 95, so there is no need to separately set up the microprocessor module and the low-dropout linear regulator (LDO) module 78. Figure 8 In the solution, the microprocessor module 101 is not provided inside the LTE module 95, and the microprocessor module 101 is separated from the LTE module 95. At the same time, a set of low-dropout linear regulator (LDO) modules 78 is added to provide power to the microprocessor module 101. The monitoring terminal ad of the microprocessor module 101 is used to monitor the output voltage E1 of the DC / DC converter 94; the battery voltage detection terminal ab of the microprocessor module 101 is used to detect the output voltage V4 of the positive electrode of the battery. The C signal line outputted by the microprocessor module 101 is connected to the e2 terminal of the charging module 98, so as to control the on / off state of the charging module 98 (i.e., the two states of on and off); the B signal line outputted by the microprocessor module 101 is connected to the e1 terminal of the low-voltage difference linear regulator (LDO) module 99, so as to control the on / off state of the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96 (i.e., the two states of on and off); the A signal line outputted by the microprocessor module 101 is connected to the b pin of the transistor Q1, so as to control the on / off state of the transistor Q1. State: When the e-pin of transistor Q3 is connected to the power supply terminal vd1 of LTE module 95 (that is, the 1-pin of the first capacitor C5), the c-pin of transistor Q3 is connected to the 1-pin of capacitor C6 and the power supply terminal vd1 of LTE module 95, as long as the microprocessor module 101 outputs the A signal to turn on and off the b-pin of transistor Q1, the LTE module 95 can be turned on and off; the microprocessor module 101 outputs the M signal routing and is connected to the b-pin of transistor Q3, which is used to control the on and off state of transistor Q2 and LTE module 95 (that is, the two states of on and off). Transistor Q1, transistor Q2, and transistor Q3 can also be replaced by MOSFET, IGBT, thyristor, relay, etc.

[0162] Figure 8 The function of the microprocessor module 101 outputting the A signal routing, the B signal routing, and the C signal routing in the scheme is the same as Figure 1 to Figure 6 The functions of the LTE module 95 output A signal routing, B signal routing, and C signal routing in the solution are the same. Figure 8 The functions of the monitoring terminal ad and the battery voltage detection terminal ab of the microprocessor module 101 in the scheme are similar to Figure 1 to Figure 6 The functions of the monitoring terminal ad of the LTE module 95 and the battery voltage detection terminal ab in the solution are the same.

[0163] and Figure 1 to Figure 6 Comparison of the schemes in Figure 8 The microprocessor module 101 in the scheme has another outstanding advantage that the on / off state of the transistor Q2 and the LTE module can be completely controlled through the M signal routing. The I / O pins of the microprocessor module 101 can not only control the on / off of the charging module 98, the LTE module 95, and the GPS module 96 individually, but also use the internal delay of the I / O pins of the microprocessor module 101 to realize the power-on timing function of each module when it is turned on.

[0164] The following describes the relationship between the GPS module and the low-dropout linear regulator (LDO), BUCK or BOOST power module, and the relationship between the LTE module and the BUCK or BOOST power module.

[0165] Figure 1 to Figure 6 , Figure 8 The GPS module 96 and the low-dropout linear regulator (LDO) 99 in the illustrated solution are two separate parts for illustration. The GPS module 96 may also include a low-dropout linear regulator (LDO), that is, only the GPS module needs to be described, and the low-dropout linear regulator (LDO) 99 does not need to be listed separately. In some solutions, the GPS module 96 and the low-dropout linear regulator (LDO) 99 are separated, but in some solutions, the GPS chip in the GPS module 96 has a built-in low-dropout linear regulator (LDO) or a BUCK power supply circuit, a BOOST power supply circuit, etc. Figure 1 to Figure 6 , Figure 8 The low dropout linear regulator (LDO) 99 in the solution shown can also be replaced by a BUCK power supply circuit or a BOOST power supply circuit. Figure 1 to Figure 6 , Figure 8 The loads such as the LTE module and GPS module in the solution shown may also have built-in low-dropout linear regulators (LDO), BUCK power supply circuits, and BOOST power supply circuits, without limitation here.

[0166] Figure 1 to Figure 6 , Figure 8 In the illustrated solution, the GPS module 96 and the low-dropout linear regulator (LDO) 99 are illustrated as two separate parts. The GPS module 96 may also include a low-dropout linear regulator (LDO), that is, only the GPS module needs to be described, and the low-dropout linear regulator (LDO) 99 does not need to be listed separately. In some solutions, the GPS module 96 and the low-dropout linear regulator (LDO) 99 are separated, but in some solutions, the GPS chip in the GPS module 96 has a built-in low-dropout linear regulator (LDO) or a BUCK power supply circuit or a BOOST power supply circuit, which is not limited here.

[0167] The following is a method to solve the voltage drop and loss of the isolation diode.

[0168] Figure 1 to Figure 6 In the scheme shown, the first isolation diode D1 and the fourth isolation diode D4 are inserted between the output terminal E1 of the DC / DC converter 94 and the LTE module 95 and other loads, respectively. About 0.5V~0.7V is generated on the first isolation diode D1. When a current of 1A is passed, the calculated thermal power consumption is about 0.5W~0.7W; if a current of 1.5A is passed, the calculated thermal power consumption is about 0.75W~1.05W, and if a current of 2A is passed, the calculated thermal power consumption is about 1W~1.4W, which affects the power supply efficiency of the whole machine. Due to the distributed resistance ESR and distributed inductance ESL on the first isolation diode D1, when the load such as the LTE module 95 consumes current at a high power instant, a very large voltage drop will be generated on the first isolation diode D1. The voltage at the output terminal E1 of the DC / DC converter 94 is 4.4V, and after deducting the voltage drop of 0.5~0.7V, the operating voltage range of the LTE module 95 is about 3.7V~3.9V.

[0169] Fig. 9 A dual power supply structure is given. Figure 1 to Figure 6 Comparison of the schemes shown, Fig. 9 In the scheme, a transistor Q5 (not shown in the figure) is connected in parallel at both ends of the first isolation diode D1 between the output terminal E1 of the DC / DC converter 94 and the load. It should be noted that the transistor Q5 can also be replaced by a MOSFET, IGBT, thyristor, relay, etc. to reduce the voltage drop of the first isolation diode D1 and reduce the load power failure and network disconnection caused by the large internal resistance of the isolation diode when multiple loads consume large currents in dynamic response. When the transistor Q5 is saturated and turned on, the voltage drop between the e pin and the c pin of the transistor Q5 is about 0.1V to 0.15V. After the transistor Q5 is connected in parallel with the first isolation diode D1, the method for calculating the voltage drop is as follows:

[0170] The first isolation diode D1 is selected as a common silicon diode as an example:

[0171] Taking the voltage drop (voltage difference) across the anode a and cathode k of the first isolation diode D1 as a minimum of 0.5V, the voltage drop (voltage difference) across the c pin and e pin of the transistor Q5 as a minimum of 0.1V, and the output voltage of the output terminal E1 of the DC / DC converter 94 as 4.4V as an example, the voltage drop across the anode a and cathode k of the first isolation diode D1 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the parallel connection of different voltage drops of the two devices (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0172]

[0173] Taking the voltage drop (voltage difference) across the anode a and cathode k of the first isolation diode D1 as 0.7V at maximum and the voltage drop (voltage difference) across the c pin and e pin of the transistor Q5 as 0.15V as an example, the voltage drop across the anode a and cathode k of the isolation diode D1 / the voltage drop across the c pin and e pin of the transistor can be calculated according to the calculation formula for the voltage drop of the two devices in parallel (similar to solving the equivalent resistance of two resistors in parallel), and the calculation formula is as follows:

[0174]

[0175] At this time, the voltage drop from the output terminal E1 of the DC / DC converter 94 to the power supply terminal vd1 of the LTE module 95 is approximately between 0.0833V and 0.1235V. The output voltage V1 of the output terminal E1 of the DC / DC converter 94 is 4.4V. After subtracting the voltage drop of 0.0833V to 0.1235V, the operating voltage range of the LTE module 95 is approximately 4.3167V to 4.2765V. Fig. 9 Program and Figure 2 to Figure 7 Comparison of the schemes in Fig. 9 The voltage drop ratio of the first isolation diode D1 in parallel with the transistor Q5 is Figure 2 to Figure 7 The voltage drop of the first isolation diode D1 is 0.4167V to 0.5765V, which greatly reduces the voltage drop and loss on the first isolation diode D1.

[0176] because Fig. 9 The voltage drop ratio of the first isolation diode D1 in parallel with the transistor Q5 is Figure 1 to Figure 6 The voltage drop of the first isolation diode D1 is as small as 0.4167V to 0.5765V, which greatly reduces the problem of load power failure and network disconnection caused by the large internal resistance of the first isolation diode D1 when multiple loads dynamically respond to large currents.

[0177] The following describes a method for solving the voltage drop problem and mutual interference problem caused by a power supply system supplying power to multiple loads at the same time.

[0178] Fig.10 A schematic diagram is given of an external power supply circuit that supplies power to the LTE module and GPS module separately. Fig.10 that is Figure 2 The scheme shows a schematic diagram of the external power supply circuit that supplies power to the LTE module and the GPS module separately, and also shows the composition of the internal circuit of the DC / DC converter 94 in detail, which makes it easier to explain how to solve the voltage drop problem and mutual interference problem caused by a single power supply system supplying power to multiple loads at the same time. Fig.10The DC / DC converter 94 is only described as a BUCK power converter as an example, and the type of the DC / DC converter 94 is not limited (for example, the DC / DC converter 94 can also be a BOOST power converter, a BUCK-BOOST converter, a flyback isolation converter, etc.).

[0179] Continue reading Figure 2 , Fig.10 The DC / DC converter 94 is mainly composed of a fifth capacitor C11, a DC / DC converter chip 90, a sampling component 88, an inductor L1, a second capacitor C1, etc. The DC / DC converter chip 90 has built-in functional circuits such as an upper power switch Q8, a lower power switch Q9, a reference voltage source REF, and a clock generator 84. The drain of the upper power switch Q8 is connected to the power input pin Vin of the DC / DC converter chip 90, the source of the upper power switch Q8 is connected to the pin SW of the DC / DC converter chip 90 and the drain of the lower power switch Q9, and the source of the lower power switch Q9 is connected to the pin G9 of the DC / DC converter chip 90. The pin G9 of the chip 90 is connected to the system ground of the DC / DC converter 94, for example, the pin G9 of the DC / DC converter chip 90 is connected to the ground pin G8 of the external connector 92, the ground pin G7 of the external power clamp filter module 91, the 2nd pin of the fifth capacitor C11, the 2nd pin of the second capacitor C1, the 2nd pin of the first capacitor C5, the ground pin G4 of the LTE module 95, the 2nd pin of the third capacitor C4, the ground pin G2 of the low dropout regulator (LDO) module 99, and the ground pin G3 of the GPS module 96. The pin SW of the DC / DC converter chip 90 is connected to the 1st pin of the inductor L1, and the 2nd pin of the inductor L1 is connected to the 1st pin of the second capacitor C1. The sampling component 88 is placed close to the feedback pin FB of the DC / DC converter chip 90. A wire 86 is led out from the feedback pin FB of the DC / DC converter chip 90 to one end of a sampling component 88 , and a sampling wire 87 is led out from the other end of the sampling component 88 to the pin 1 of the second capacitor C1 .

[0180] The output terminal E1 of the DC / DC converter 94 supplies power to the LTE module 95 through the first isolation diode D1, and to the low-dropout regulator (LDO) module 99 and the GPS module 96 through the fourth isolation diode D4. The GPS module 96 is a low-power load, but it is extremely sensitive to the drop and noise in the power supply, while the LTE module 95 is a high-speed load that consumes a large current instantly. The operating frequency of the LTE module 95 is a high-speed flip at 700MHz to 2.7GHz, and the DC / DC converter 94 is required to provide a fast response. When the LTE module 95 flips at a high speed of 700MHz to 2.7GHz, a momentary drop phenomenon will occur at both ends of the first capacitor C5. Since the capacitance of the first capacitor C5 is relatively large, according to the characteristics of the capacitor, the voltage at both ends of the capacitor cannot change suddenly. The first capacitor C5 plays a role in instantaneous discharge for the LTE module 95 to consume a large current at a high-speed flip of 700MHz to 2.7GHz, so as to suppress the momentary drop phenomenon. The second capacitor C1 will continuously charge the first capacitor C5 through the first isolation diode D1 to supplement the energy lost by the instantaneous discharge of the first capacitor C5 to the LTE module 95, and alleviate the power supply voltage drop caused by the instantaneous discharge of the first capacitor C5 to the LTE module 95. However, since there is a 0.5V to 0.7V voltage drop when the first isolation diode D1 is flowing, that is, there is a large DC resistance and distributed inductance, which greatly hinders the second capacitor C1 from quickly charging the first capacitor C5 through the first isolation diode D1. In addition, there is a long power supply line between the second capacitor C1 and the first capacitor C5, and the power supply line also has a DC resistance and distributed inductance, which will also hinder the second capacitor C1 from quickly charging the first capacitor C5 through the first isolation diode D1. The first capacitor C5 quickly discharges to the LTE module 95, and the second capacitor C1 charges the first capacitor C5 at a low to medium speed through the first isolation diode D1, which will cause a more obvious drop phenomenon on the first capacitor C5. If the conventional method is adopted: the LTE module 95 is connected in parallel with the low-dropout regulator (LDO) module 99, that is, the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96 share a power supply, the drop phenomenon on the first capacitor C5 and the noise generated by the drop will be coupled to the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96, causing the GPS module 96 to not work properly (for example, the crystal oscillator power supply in the GPS module 96 is unstable, resulting in jitter and frequency deviation). Figure 2In the scheme shown, the power supply voltage drop phenomenon is in the following order of severity: LTE module 95 power supply terminal vd1>LTE module 95 power supply terminal vd1 to the power supply line of the first capacitor C5>1 pin of the first capacitor C5>the power supply line of the first capacitor C5 to the cathode k of the first isolation diode D1>the first isolation diode D1>the power supply line of the anode a of the first isolation diode D1 to the second capacitor C1>1 pin of the second capacitor C1 (the output terminal E1 in the DC / DC converter 94), that is, the closer to the LTE module 95 power supply terminal vd1, the more serious the power supply voltage drop phenomenon is. The closer to pin 1 of the second capacitor C1 (output terminal E1 in the DC / DC converter 94), the less obvious the power supply voltage drop phenomenon is, because the second capacitor C1 is an energy storage and discharge element, and the second capacitor C1 can quickly discharge the load when a large current drops instantly. At the same time, the inductor in the DC / DC converter 94 continuously charges the second capacitor C1 (replenishes energy to the second capacitor C1) and discharges the load (for example, the first isolation diode D1 and the LTE module 95, the third isolation diode D3 and the low dropout regulator (LDO) module 99 and the LTE module 95). When the voltage across the second capacitor C1 suddenly drops (that is, the voltage decreases), the signal obtained by sampling from the 2nd pin of the second capacitor C1 is coupled to the feedback pin FB of the DC / DC converter chip 90 through the sampling component 88, and is injected into the error amplifier 85 of the DC / DC converter chip 90 through the feedback pin FB. After the error amplifier 85 compares the error signal with the reference voltage REF, the error signal is injected into the PWM driver inside the DC / DC converter chip 90. The PWM driver needs to compare the error signal with the clock generated by the clock generator 84, so that the conduction time of the upper power switch Q8 and the lower power switch Q9 can be adjusted to inject energy into the inductor L1 (the energy is the product of the input voltage and current from the power input pin Vin of the DC / DC converter chip 90), and then the magnetic field energy and electric field energy of the inductor L1 and the second capacitor C1 are converted to each other to stabilize the output voltage V1. Therefore, when the first isolation diode D1 and LTE module 95 suddenly experience voltage drops, the entire feedback system of the sampling element and the internal switch drive system of the DC / DC converter chip 90 are linked to allow the inductor L1 to charge the second capacitor C1 to maintain the stability of the voltage at pin 1 of the second capacitor C1. Based on this analysis result, the following power supply circuit solution and PCB board power line routing solution are adopted:

[0181] Since the battery 93 and the external power supply circuit adopt a dual power supply solution, an isolation diode (such as a first isolation diode D1 and a fourth isolation diode D4) must be added between the LTE module 95, the low-dropout regulator (LDO) module 99, the GPS module 96 and the output terminal E1 of the external power supply circuit to prevent the battery 93 from discharging to the DC / DC converter 94 when the battery 93 supplies power to the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96, thereby affecting the battery life and service life of the battery 93. Life; isolation diodes (such as the second isolation diode D2 and the third isolation diode D3) must be added between the LTE module 95, the low-dropout regulator (LDO) module 99, the GPS module 96 and the battery 93 to prevent the DC / DC converter 94 from directly charging the battery 93 when the output end E1 of the DC / DC converter 94 supplies power to the LTE module 95, the low-dropout regulator (LDO) module 99 and the GPS module 96 without any management measures, which affects the service life of the battery 93 and is prone to overcharging and fire and other safety accidents.

[0182] In order to prevent the LTE module 95 from consuming a large current and causing a voltage drop when transmitting at maximum power, and to prevent the related noise from coupling to the low-dropout regulator (LDO) module 99 and the GPS module 96, thereby affecting the normal operation of the GPS module 96, it is necessary to add a first isolation diode D1 (and / or a transistor, MOSFET, IGBT, thyristor, relay, etc.) between the DC / DC converter 94 and the LTE module 95; and add a fourth isolation diode D4 between the DC / DC converter 94 and the low-dropout regulator (LDO) module 99 and the GPS module 96; see Fig.10 The power line 62 from the anode a of the first isolation diode D1 to the pin 1 of the second capacitor C1, the power line 63 from the anode a of the fourth isolation diode D4 to the pin 1 of the second capacitor C1, and the power line 61 from the inductor L1 to the pin 1 of the second capacitor C1 are separated.

[0183] The purpose of separating the power line 61 from the inductor L1 to pin 1 of the second capacitor C1 from the anode a of the first isolation diode D1 to pin 1 of the second capacitor C1 and the power line 62 and the power line 63 from the anode a of the fourth isolation diode D4 to pin 1 of the second capacitor C1 is to allow the square wave energy output by the inductor L1 to be fully filtered out by the second capacitor C1 at pin 1 of the second capacitor C1, so that the filtering and energy storage and discharge functions of the second capacitor C1 can be fully utilized to ensure that the voltage at the output terminal E1 of the DC / DC converter 94 is stable and clean, rather than allowing the square wave energy output by the inductor L1 to be directly output to the anode a of the first isolation diode D1 and the anode a of the fourth isolation diode D4 without passing through pin 1 of the second capacitor C1, resulting in the square wave energy of the DC / DC converter 94 being injected into the LTE module 95 and the GPS module 96, causing the LTE module 95 and the GPS module 96 to work abnormally.

[0184] The power line 62 from the anode a of the first isolation diode D1 to the pin 1 of the second capacitor C1 is separated from the power line 63 from the anode a of the fourth isolation diode D4 to the pin 1 of the second capacitor C1, and they both draw power from pin 1 of the second capacitor C1 for the purpose of preventing the LTE module 95 from generating a drop phenomenon and related noise from coupling to the low dropout regulator (LDO) module 99 and the GPS module 96, thereby affecting the normal operation of the GPS module 96. The power line 62 from the anode a of the first isolation diode D1 to the pin 1 of the second capacitor C1 is separated from the power line 63 from the anode a of the fourth isolation diode D4 to the pin 1 of the second capacitor C1, and both are powered separately from pin 1 of the second capacitor C1. The voltage drop generated by the LTE module 95 will be maintained by the second capacitor C1 and the entire DC / DC converter 94 to maintain the stability of the output terminal E1 of the DC / DC converter 94, and the noise coupling generated by the drop of the LTE module 95 will be absorbed by the second capacitor C1. Therefore, the voltage drop phenomenon and related noise coupling generated by the anode a of the first isolation diode D1 will not be coupled to the anode a of the fourth isolation diode D4, and will not affect the low dropout regulator (LDO) module 99 and the GPS module 96, affecting the normal operation of the GPS module 96.

[0185] The first isolation diode D1 and the isolation diode D4 can be replaced by triodes, MOSFETs, IGBTs, thyristors, relays, etc., and triodes, MOSFETs, IGBTs, thyristors, relays, etc. can also be connected in parallel at both ends of the isolation diode D1 and the isolation diode D4 to reduce the 0.2V~0.7V voltage drop and thermal power consumption in the first isolation diode D1 and the fourth isolation diode D4. The voltage drop of the Schottky diode used in the first isolation diode D1 and the fourth isolation diode D4 is 0.2V~0.5V, and the voltage drop of the ordinary silicon diode used in the first isolation diode D1 and the fourth isolation diode D4 is 0.6V~0.7V.

[0186] Fig.11 A top view of a power supply device for supplying power to multiple loads on a PCB board is given. Fig.12 A cross-sectional view of a power supply device for supplying power to multiple loads in the vertical direction of the PCB board is given. Fig.13 A cross-sectional view of another power supply device for supplying power to multiple loads in the vertical direction of a PCB board is given.

[0187] Fig.10 is the circuit diagram, and Fig.11 that is Fig.10 An implementation of the circuit diagram scheme in PCB board 59, Fig.11 for Fig.10 A top view of the PCB board 59 of the solution. Fig.10 , Fig.11 The second capacitor C1 includes a large-capacity capacitor C11 (such as an aluminum electrolytic capacitor, a tantalum capacitor, a solid-state capacitor, a ceramic capacitor with a capacity of more than 1uF, a niobium capacitor, a super capacitor, etc.), and a high-frequency capacitor C10 (such as a ceramic capacitor with a capacity of 0.1uF and less, a CBB capacitor, a film capacitor, etc.). The large-capacity capacitor C11 is used to filter out the square wave and energy storage discharge output by the inductor L1, and the high-frequency capacitor C10 is used to filter out the high-frequency noise generated by the DC / DC converter 94 during the switching process; at the same time, the high-frequency capacitor C10 can also filter out the high-frequency noise generated by each load during high-speed flipping: for example, during the high-speed flipping process of the LTE module 95, the noise transmitted through the power line 65 and the first isolation diode D1 (for example, when the LTE module 95 is transmitting at maximum power, the power supply voltage drops to generate multiple harmonic noises), so as to avoid the high-frequency noise generated by each load during high-speed flipping from being coupled to the external power connector 111 and the interface 70 through the DC / DC converter 94, resulting in the product's EMI radiation and conduction exceeding the standard. Pin 2 of the inductor L1 is connected to pin 1 of the high-frequency capacitor C10 and pin 1 of the large-capacity capacitor C11 through the power line 61, and then two power lines are independently led out from the -X direction toward the X direction at pin 1 of the large-capacity capacitor C11: power line 62 and power line 63. The power line 62 is independently led out from pin 1 of the large-capacity capacitor C11 and connected to the anode a of the first isolation diode D1 through pin 1 of the first capacitor C5, and the cathode k of the first isolation diode D1 is connected to the power supply terminal vd1 of the LTE module 95 through the power line 65; the power line 63 is independently led out from pin 1 of the large-capacity capacitor C11 and connected to the anode a of the fourth isolation diode D4 through pin 1 of the third capacitor C4, and the cathode k of the fourth isolation diode D4 is connected to the input terminal of the low-dropout regulator (LDO) module 99 through the power line 64.

[0188] The power line 61 from the 2nd foot of the inductor L1 to the 1st foot of the high-frequency capacitor C10 and the 1st foot of the large-capacity capacitor C11, the power line 62 from the 1st foot of the large-capacity capacitor C11 to the anode a of the first isolation diode D1, and the power line 63 from the 1st foot of the large-capacity capacitor C11 to the anode a of the fourth isolation diode D4 are in a That is, the power lines 61, 62 and 63 are separated separately, so that the square wave energy output by the inductor L1 can be fully filtered by the high-frequency capacitor C10 and filtered by the large-capacity capacitor C11, and then discharged through the respective isolation diodes to be output to each load. Since the power lines 62 and 63 are not directly connected, the power lines 62 and 63 are connected at pin 1 of the large-capacity capacitor C11. Therefore, the power supply voltage drop and high-frequency harmonic noise generated by the LTE module 95 are coupled to pin 1 of the large-capacity capacitor C11 through the first isolation diode D1 and the power line 62. The internal feedback of the large-capacity capacitor C11 and the DC / DC converter 94, the conduction time of the driving power switches Q8 and Q9, and the charging mechanism of the inductor L1 for the large-capacity capacitor C11 (the high-frequency capacitor C10 and the large-capacity capacitor C11 are both components of the second capacitor C1) are used to stabilize the voltage at pin 1 of the large-capacity capacitor C11. Therefore, the power supply voltage drop and high-frequency harmonic noise generated by the LTE module 95 are coupled to the power line 63, the fourth isolation diode D4, the power line 64 and the low-dropout regulator (LDO) module 99 and the GPS module 96, which can be almost ignored. Fig.11 The large-capacity capacitor C11 given in the figure is a plug-in type aluminum electrolytic capacitor (only a plug-in type aluminum electrolytic capacitor is used as an example) and is installed on the bottom layer of the PCB board 65 ( Fig.11 After the pins 1 and 2 of the large-capacity capacitor C11 pass through the PCB board 65, they are on the top layer of the PCB board 65 ( Fig.11 Inductor L1, high frequency capacitor C10, first isolation diode D1, fourth isolation diode D4, first capacitor C5, and third capacitor C4 are all SMT components (referred to as SMT components), which are all installed on the top layer of PCB board 65 ( Fig.11 The power supply lines 61, 62, 63, 65 and 64 are all arranged on the top layer of the PCB board 65 ( Fig.11 Labeled as L01 layer).

[0189] Connect the ground pin G8 of the external connector 92, the ground pin G7 of the external power clamp filter module 91, the pin 2 of the capacitor C11, and the pin G9 of the DC / DC converter chip 90 from the top layer of the PCB board 65 ( Fig.11The ground line GH11 is led out from the 2nd pin of the high-frequency capacitor C10 and the 2nd pin of the large-capacity capacitor C11 (marked as L01 layer) and connected to the 2nd pin of the high-frequency capacitor C10 and the 2nd pin of the large-capacity capacitor C11. After the DC / DC converter 94 is fully filtered by the high-frequency capacitor C10 and the large-capacity capacitor C11, the ground line GH1 is led out from the 2nd pin of the large-capacity capacitor C11 (top layer of PCB board 65) and connected to the 2nd pin of the first capacitor C5 and the 2nd pin of the third capacitor C4 respectively. At the same time, a plurality of ground vias 52 are set near the 2nd pin of the first capacitor C5, and a plurality of ground vias 51 are set near the 2nd pin of the third capacitor C4. The inductor L1, the high-frequency capacitor C10, the large-capacity capacitor C11, the first isolation diode D1, the fourth isolation diode D4, the first capacitor C5, the third capacitor C4, the LTE module 95, and the low-dropout linear regulator (LDO) module 99 are on the bottom layer ( Fig.11 The grounding line GH4 is set at the projection position of the PCB board 65 (marked as L04 layer). The grounding line GH4 is a large-area copper foil, which is used to provide a return path for the inductor L1, the high-frequency capacitor C10, the large-capacity capacitor C11, the first isolation diode D1, the fourth isolation diode D4, the first capacitor C5, the third capacitor C4, etc. At the same time, the grounding line GH4 is on the bottom layer ( Fig.11 Marked as L04 layer) connects pin 2 of large-capacity capacitor C11, ground via 52, and ground via 51.

[0190] Fig.12 that is Fig.10 Another implementation of the circuit diagram scheme in PCB board 59, Fig.12 for Fig.10 A cross-sectional view of the PCB board 59 in the vertical direction. Fig.10 , Fig.12, the inductor L1, the power line 61, the high-frequency capacitor C10, the large-capacity capacitor C11, the power line 62, the first isolation diode D1, the first capacitor C5, the LTE module 95, etc. are arranged on the top layer of the PCB board 59. From -X to X direction, the power line 61 is led out from the 1st pin of the inductor L1 and connected to the 1st pin of the high-frequency capacitor C10 and the 1st pin of the large-capacity capacitor C11 respectively, and then the power line 62 is separately led out from the 1st pin of the large-capacity capacitor C11 to the anode a of the first isolation diode D1, and the cathode k of the first isolation diode D1 leads the power line 65 to the power terminal vd1 of the LTE module 95. That is, the power line 61 led out from the 1st pin of the inductor L1 is filtered by the high-frequency capacitor C10, the large-capacity capacitor C11 and the energy storage discharge, and then sent to the power terminal vd1 of the LTE module 95 through the power line 62, the first isolation diode D1, and the power line 65, so the power output by the DC / DC converter 94 to the power terminal vd1 of the LTE module 95 is stable and clean. The ground copper foil GH2 is set on the second layer of the PCB board 59 to provide a return path for the inductor L1, the power line 61, the high-frequency capacitor C10, the large-capacity capacitor C11, the power line 62, the first isolation diode D1, the first capacitor C5, the LTE module 95, etc., to reduce the return path of the power path and reduce the noise of the power supply.

[0191] The fourth isolation diode D4, the third capacitor C4, the low voltage difference linear regulator (LDO) module 99, and the GPS module 96 are arranged on the bottom layer of the PCB board 65. The large-capacity capacitor C11 is a plug-in capacitor (such as an aluminum electrolytic capacitor), and the 1st pin (through-hole pin) of the large-capacity capacitor C11 is inserted into the through-hole pad 58, and the 1st pin of the large-capacity capacitor C11 and the through-hole pad 58 are connected with low impedance by soldering. The power supply line 63 is led out from the bottom through-hole pad 58 of the PCB board 65 and connected to the anode a of the fourth isolation diode D4, and the cathode k of the fourth isolation diode D4 is led out to the power supply line 64 and connected to the input end of the low voltage difference linear regulator (LDO) module 99, and the output end of the low voltage difference linear regulator (LDO) module 99 is connected to the GPS module 96. The power line 63 is not directly connected to the power line 61, but is connected together through pin 1 of the large-capacity capacitor C11. Therefore, the power line 61 led out from pin 1 of the inductor L1 is filtered by the high-frequency capacitor C10, the large-capacity capacitor C11, and the energy storage is discharged, and then sent to the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96 through pin 1 of the large-capacity capacitor C11, the through-hole pad 58, the power line 63, the fourth isolation diode D4, and the power line 64. Therefore, the power output by the DC / DC converter 94 to the low-voltage difference linear regulator (LDO) module 99 and the GPS module 96 is stable and clean.

[0192] The power line 63 is not directly connected to the power line 62, but is connected together through the pin 1 of the large-capacity capacitor C11 and the through-hole pad 58. When the LTE module 95 generates a power supply voltage drop and high-frequency harmonic noise, it is coupled to the pin 1 of the large-capacity capacitor C11 through the first isolation diode D1 and the power line 62. The internal feedback of the large-capacity capacitor C11 and the DC / DC converter 94, the conduction time of the driving power switches Q8 and Q9, and the charging mechanism of the inductor L1 to the large-capacity capacitor C11 (the high-frequency capacitor C10 and the large-capacity capacitor C11 are both components of the second capacitor C1) stabilize the voltage of the pin 1 of the large-capacity capacitor C11. Therefore, the power supply voltage drop and high-frequency harmonic noise generated by the LTE module 95 are coupled to the power line 63, the fourth isolation diode D4, the power line 64, the low-dropout regulator (LDO) module 99, and the GPS module 96, which can be almost ignored.

[0193] Continue reading Fig.10 , Fig.13 , Fig.10 is the circuit diagram, and Fig.13 that is Fig.10 Another embodiment of the circuit diagram scheme in PCB board 59, Fig.13 for Fig.10 A cross-sectional view of the PCB board 59 in the vertical direction. Fig.12 Compare, Fig.13 That is to Fig.12 The large-capacity capacitor C11 in the circuit is changed from a plug-in capacitor to a chip capacitor. Fig.12 The pin 1 (through-hole pin) and through-hole pad 58 of the large-capacity capacitor C11 are changed into power vias 53 (the number is at least 1), that is, the power supply from the pin 1 of the large-capacity capacitor C11 to the low-dropout regulator (LDO) module 99 and the GPS module 96 at the bottom of the PCB board 59 is realized by changing the layer through the power via 53, and Fig.12 The solution is that pin 1 of the large-capacity capacitor C11 supplies power to the low-dropout regulator (LDO) module 99 and the GPS module 96 at the bottom layer of the PCB board 59 by changing the layer through pin 1 (through-hole pin) of the large-capacity capacitor C11 and the through-hole pad 58. Apart from this, the principles of other parts are the same and will not be repeated.

[0194] In summary Figure 10 to Figure 13 The analysis and conclusions in the paper show that the scheme is scientific and reliable, meets the design requirements, and is feasible after actual test verification.

[0195] The following is a solution to improve the dynamic response of DC / DC converters and improve the voltage drop problem caused by power supply of multiple loads.

[0196] Fig.14A schematic diagram of an external power supply circuit supplying power to the LTE module and GPS module separately is given. Fig.14 That is to Fig.10 The sampling component 88 in FIG. 8 is specifically decomposed into a resistor R1, a resistor R2, and a feedforward capacitor C8. The other parts are the same and will not be described again. Fig.14 The DC / DC converter 94 shown in the figure adopts a BUCK power supply topology structure, and a feedforward capacitor C8 is connected in parallel across the resistor R1 in the sampling component 88. The feedforward capacitor C8 is used to improve the response speed of the feedback system of the DC / DC converter 94, thereby improving the dynamic response capability of the DC / DC converter 94 with load, reducing the output ripple, and greatly improving the load of multiple loads (for example Fig.14 The power supply of the LTE module 95, the low-dropout linear regulator (LDO) module 99 and the GPS module 96) produces a voltage drop problem.

[0197] A(s) is the open loop gain of the DC / DC converter 94 power system. For the convenience of discussion, we assume that A(s) already includes the second capacitor C1, the load (e.g. Fig.14 The influence of other factors such as LTE module 95, low dropout linear regulator (LDO) module 99 and GPS module 96). Fig.14 The voltage V1 at the output terminal E1 of the DC / DC converter 94 when the feedforward capacitor C8 is not used is:

[0198]

[0199] Wherein, β is the feedback coefficient, OUT represents the voltage at the output terminal E1 of the DC / DC converter 94, and G(s) represents the loop gain.

[0200] From the above, it can be concluded that: by adjusting the resistors R1 and R2 in the sampling component 88, the voltage V1 at the output terminal E1 of the DC / DC converter 94 can be changed, but at the same time, the bandwidth of G(s) is also narrowed. Reasonable use of the feedforward capacitor C8 can improve the bandwidth and response speed of the power supply. At this time, the loop gain is: It can be obtained that the feedforward capacitor C8 does not change the output of the DC / DC converter, but introduces a pair of low-frequency zero fz and high-frequency pole fp to the system. The zero point will increase the phase margin, and the pole will deteriorate the phase margin. Only by keeping the zero point and the pole as far away as possible can more phase margin be obtained. However, the distance between the zero-pole pair introduced by the feedforward capacitor C8 is fixed in the logarithmic coordinate, because

[0201]

[0202] Based on this, it can be determined that the effect of the feedforward capacitor C8 is more obvious when R1 / R2 is larger, and it has no effect when R1 = 0. When R1 / R2 is determined, the feedforward capacitor C8 needs to be reasonably selected.

[0203] The following introduces the selection of feedforward capacitor C8:

[0204] In order to take into account the bandwidth and phase margin of the system, the optimal feedforward capacitor value can be obtained by following the steps below:

[0205] 1. Measure the system crossover frequency fc without feedforward capacitor C8;

[0206] 2. The zeros and poles introduced by the selected feedforward capacitor C8 satisfy:

[0207]

[0208] For example:

[0209] Fig.15 The loop gain curve of the DC / DC converter 94 feedback system measured without the feedforward capacitor C8 is shown. The DC / DC converter 94 (using the BUCK power supply topology) is set to 5V, and the resistors R1 = 105kΩ and R2 = 20kΩ are used. At this time, β = 0.16. Using a loop analyzer, the loop gain curve of the system is measured without the feedforward capacitor C8, as shown in FIG. Fig.15 As shown in the figure, C is the phase curve and D is the gain curve. Fig.16 As shown, taking the load transient response test of the DC / DC converter 94 with the BUCK power topology as an example, when the load jumps from 1A to 3A, the voltage V1 at the output terminal E1 of the DC / DC converter 94 has a maximum voltage jump (that is, voltage drop) of 340mV.

[0210] The loop gain curve after connecting 110pF feedforward capacitor C8 in parallel across resistor R1 is as follows: Fig.17 As shown in the figure, C is the phase curve and D is the gain curve. It can be seen that the crossover frequency becomes 72.4kHz, the bandwidth is doubled, and the phase margin is also increased to 50°. Fig.18 The load transient response diagram of the DC / DC converter using a 110pF feedforward capacitor is shown. Fig.18 As shown, taking the same load transient response test of the DC / DC converter 94 with a BUCK power topology as an example, after a 110pF feed-forward capacitor C8 is connected in parallel across the resistor R1, the maximum voltage jump (that is, voltage drop) of the voltage V1 at the output terminal E1 of the DC / DC converter 94 is reduced from 340mV to 200mV, which is a significant improvement.

[0211] In summary, the reasonable use of feedforward capacitor C8 can significantly improve the dynamic characteristics of the power supply. The optimal value of feedforward capacitor C8 is based on the optimal compromise between system bandwidth and phase margin. In actual application, the bandwidth and margin requirements of DC / DC converter 94 are appropriately increased or decreased to further optimize the bandwidth or margin.

[0212] LTE module power supply requirements when working

[0213] Table 1 shows the characteristics of a certain type of LTE module power supply. From Table 1, it can be seen that the minimum operating voltage of the LTE module is 3.2V, the typical value is 3.8V, and the maximum value is 4.4V; the maximum instantaneous drop of the LTE module under the maximum RF output condition is 0.4V (400mV); the maximum value of the data transmission current is 589mA in the EGSM900 1D / 4U PCL=5 mode, the maximum value of the data transmission current is 541mA in the WCDMA B1 HSDPA541 mode, and the maximum value of the data transmission current is 710mA in the LTE B3 mode; in the LTE DRX=5 mode, the maximum value of the standby current is 5.5μA; the instantaneous current of the RF transmission reaches 3A.

[0214] Table 2 shows the basic requirements of a certain type of LTE module power pin for power supply. Fig.19 The actual power supply circuit of a certain model of LTE module is given.

[0215] From Table 2, Fig.19 It can be seen that the power terminal vd1 of the LTE module 95 includes two sets of power pins: a baseband power pin VBAT_BB and a radio frequency power pin VBAT_RF. Figure 1 to Figure 6 , Figure 10 to Figure 13 The first capacitor C5 in the circuit actually includes: ① a large-capacity capacitor C50 (a 100μF low ESR capacitor) set at the baseband power supply pin VBAT_BB, a high-frequency capacitor C11 (a 0.1μF chip ceramic capacitor), a high-frequency capacitor C52 (a 33pF chip ceramic capacitor), and a high-frequency capacitor C53 (a 10pF chip ceramic capacitor); ② a large-capacity capacitor C54 (a 100μF low ESR capacitor) set at the RF power supply pin VBAT_RF, a high-frequency capacitor C55 (a 0.1μF chip ceramic capacitor), a high-frequency capacitor C56 (a 33pF chip ceramic capacitor), and a high-frequency capacitor C57 (a 10pF chip ceramic capacitor).

[0216] Table 1 Characteristics of a certain model of LTE module power supply

[0217]

[0218]

[0219] Table 2 Basic requirements of power supply for power pins of a certain model of LTE module

[0220]

[0221] Fig. 20 The waveform diagram of the jump cycle change of the LTE module battery 93 is given. When the LTE module 95 is transmitting at maximum, there is a burst pulse of 1 / 8 TDMA cycle every 4.615ms (lasting 577μs), such as Fig. 20 As shown, during the burst pulse (drop) stage, the power supply must be able to provide a sufficiently high peak current to ensure that the power supply voltage provided to the power supply terminal vd1 of the LTE module 95 does not drop to the minimum operating voltage of the LTE module 95. For example, Table 1 gives the minimum operating voltage of a certain model of LTE module 95 as 3.2V. At the maximum transmission power level of the LTE module 95, the peak current of the RF power pin VBAT_RF (the power terminal vd1 of the LTE module 95 includes the RF power pin VBAT_RF and the baseband power pin VBAT_BB) in the LTE module 95 will reach about 2A, and the peak current of the baseband power pin VBAT_BB (the power terminal vd1 of the LTE module 95 includes the RF power pin VBAT_RF and the baseband power pin VBAT_BB) in the LTE module 95 will reach about 1A. The peak currents of the two groups of power pins combined can reach about 3A, which will cause the power supply voltage of the RF power pin VBAT_RF and the baseband power pin VBAT_BB in the LTE module 95 to drop. For example, if the power supply voltage drops below 3.2V, the system will reset, shut down or restart. To ensure that the LTE module 95 can work stably and normally, the drop voltage of the RF power pin VBAT_RF and the baseband power pin VBAT_BB in the LTE module 95 should not exceed 400mV.

[0222] The following describes the implementation method of calculating the pulse width of the jump according to the jump period change waveform of the LTE module battery 93.

[0223] from Fig. 20 It is known that the pulse width of the LTE module 95 at the maximum transmission power is about 577μs. The conversion formula based on the period T and frequency f is as follows: T = 1 / f; then f = 1 / T = 1 / 577μs = 1 / 577x10-6s = 1.733kHz;

[0224] When the LTE module 95 is at the maximum transmission power, the pulse width of the jump is about 577μs, and the corresponding drop pulse interference frequency band is 1.733kHz.

[0225] And for Figure 1 to Figure 6 , Figures 9 to 13The DC / DC converter in the scheme shown in the figure, if the BUCK, BOOST, BUCK-BOOST power supply scheme is adopted, the BUCK power supply generally works at tens of kHz to several MHz, and the BUCK power supply is combined with the internal output capacitor and then with Figure 1 to Figure 6 , Figures 9 to 13 The PCB stacking and layout scheme shown (the power supply scheme for the LTE module 95 and the GPS module 96 needs to be separated from pin 1 of the second capacitor C1), the BUCK, BOOST, and BUCK-BOOST power supply schemes are fully capable of suppressing the interference caused by the 1.733kHz drop pulse generated by the LTE module 95.

[0226] The following describes the testing process of the power supply system of the present invention:

[0227] In order to prove the rationality and practicality of the design of the power supply circuit provided by the embodiment of the present invention, Figure 1 Taking the application of the power circuit in a wireless vehicle tracker as an example, the following tests were performed on the DC / DC converter output voltage: power supply output voltage test, power supply output voltage ripple test, and EMI radiation test.

[0228] 1. Power supply related testing and analysis process

[0229] Fig.21 The output voltage waveform of the DC / DC module is given when the load current is 3A;

[0230] Test conditions: wireless vehicle tracker, oscilloscope (sampling frequency 2GS / s, bandwidth 100MHz), digital control power supply.

[0231] like Fig.21 As shown, the DC / DC module 94 in the wireless vehicle tracker uses a BUCK chip, sets the input voltage to 12V, and sets the output voltage Ve1 to 4.4V. The digital control power supply provides an external 12V power supply to the DC / DC module 94 in the wireless vehicle tracker. When the DC / DC module 94 outputs a load current of 2A, the output voltage Ve1 at the output terminal E1 of the DC / DC module 94 is measured by an oscilloscope TDS2012C+ probe to be a maximum value of 4.52V and a minimum value of 4.20V, which meets the design requirements.

[0232] like Fig. 22 As shown, the LTE module is in GPRS maximum power CAT1 B1 mode. Figure 1 The power supply circuit shown in the figure is tested to obtain a maximum voltage of 4.08V, a minimum voltage of 3.96V, an average voltage of 4.02V, a maximum ripple voltage of about 200mV, and a minimum ripple voltage of about 120mV at the power supply terminal vd1 of the LTE module 95.

[0233] Table 3 shows the power ripple of the power supply terminal vd1 of the LTE module when the DC / DC module supplies power to the LTE module under the maximum power CAT1 B1 condition in the GPRS mode. Under LTE B1 (FDD mode), when the transmit power is 20.19dB, the power supply ripple voltage is 200mV; under LTE B3 (FDD mode), when the transmit power is 18.96dB, the power supply ripple voltage is 200mV; under LTE B5 (FDD mode), when the transmit power is 20.92dB, the power supply ripple voltage is 160mV; under LTEB8 (FDD mode), when the transmit power is 20.74dB, the power supply ripple voltage is 200mV; under LTE B34 (FDD mode), when the transmit power is 20.32dB, the power supply ripple voltage is 220mV; under LTE B38 (FDD mode), when the transmit power is 19.28dB, the power supply ripple voltage is 230mV; under LTE B39 (FDD mode), when the transmit power is 19.41dB, the power supply ripple voltage is 220mV; under LTE Under LTE B40 (FDD mode), when the transmit power is 20.13dB, the power supply ripple voltage is 220mV; under LTE B41 (FDD mode), when the transmit power is 18.4dB, the power supply ripple voltage is 220mV. Under LTE B1 (FDD mode), LTE B3 (FDD mode), LTE B5 (FDD mode), LTE B8 (FDD mode), LTEB34 (FDD mode), LTE B38 (FDD mode), LTE B38 (FDD mode), LTE B39 (FDD mode), LTE B40 (FDD mode), LTE B41 (FDD mode), the power supply ripple voltage is within the range required by LTE module 95.

[0234] Table 3 The DC / DC module supplies power to the LTE module. The power ripple voltage of the power supply terminal vd1 of the LTE module under the condition of maximum power CAT1 B1 in GPRS mode

[0235] Working mode of LTE module 95 Power supply ripple voltage power LTE B1 (FDD mode) 200mV 20.19dB LTE B3 (FDD mode) 200mV 18.96dB LTE B5 (FDD mode) 160mV 20.92dB LTE B8 (FDD mode) 200mV 20.74dB LTE B34 (TDD mode) 220mV 20.32dB LTE B38 (TDD mode) 230mV 19.28dB LTE B39 (TDD mode) 220mV 19.41dB LTE B40 (TDD mode) 220mV 20.13dB LTE B41 (TDD mode) 220mV 18.4dB

[0236] 2. EMI radiation test and analysis process

[0237] Fig.23The radiation values ​​of the wireless vehicle equipment in the 30MHz to 1GHz test frequency band are given for explanation. Both the RE radiation test standard and the CE conducted emission test standard adopt the EN55022-2008 / GB9254-2008 standard, and the 0.15MHz to 0.5MHz / 0.5MHz to 30MHz / 30MHz to 1GHz / 1GHz to 6GHz frequency bands of the wireless vehicle equipment are tested. These frequency bands meet the Class B test requirements in the EN55022-2008 / GB9254-2008 standard. Fig.23 The radiation values ​​emitted by the wireless vehicle-mounted equipment in the 30MHz to 1GHz test frequency band are given. Fig.23 The straight line A in the middle is the safety limit of the 3C standard. If the value is lower than this safety limit, it is qualified. Curve B is the fluctuation curve of the radiation data of the tested product. Fig.23 It can be seen that line B is far away from line A and there is a large margin, which is much smaller than the safety standard value, indicating that EMI radiation is well controlled.

[0238] 3. Static test of GPS antenna

[0239] Fig.24 The static test of GPS antenna of wireless vehicle-mounted device in an open space is given, and the situation of each satellite in the sky that can be searched by the wireless vehicle-mounted device at a certain time point is given. Fig.24 It can be concluded that there are 9 satellites that meet the C / No value ≥ 40, while the specification requires 4 or more satellites to meet the C / No value ≥ 40 for accurate positioning, which far exceeds this requirement. Fig.10 , Fig.11 In the power circuit and power stacking solution shown, the LTE module 95 does not interfere with the GPS module.

[0240] Fig.24"PRN" is the specific GPS satellite number that the wireless vehicle-mounted device can search for in a certain open location and at a certain point in time, which are: GPS satellite 1, GPS satellite 2, GPS satellite 3, GPS satellite 6, GPS satellite 11, GPS satellite 14, GPS satellite 17, GPS satellite 19, GPS satellite 30, GPS satellite 28, GPS satellite 199, GPS satellite 50, GPS satellite 40, GPS satellite 41; there are 9 satellites that meet the C / No value ≧40, which are: GPS satellite 2 (C / No value = 40), GPS satellite 11 (C / No value = 42), GPS satellite 14 (C / No value = 42), GPS satellite 17 (C / No value = 42), GPS satellite 18 (C / No value = 43), GPS satellite 20 (C / No value = 44), GPS satellite 21 (C / No value = 45), GPS satellite 22 (C / No value = 46), GPS satellite 23 (C / No value = 47), GPS satellite 24 (C / No value = 48), GPS satellite 25 (C / No value = 49), GPS satellite 26 (C / No value = 47), GPS satellite 27 (C / No value = 48), GPS satellite 28 (C / No value = 49), GPS satellite 29 (C / No value = 40), GPS satellite 30 (C / No value = 41), GPS satellite 31 (C / No value = 41), GPS satellite 32 (C / No value = 41), GPS satellite 33 (C / No value = 41), GPS satellite 34 (C / No value = 41), GPS satellite 35 (C / No value = 42), GPS satellite 36 (C / No value = 43), GPS satellite 37 (C / No value = 41), GPS satellite 38 (C / No value = 41), GPS satellite 39 (C / No value = "BAND" is the corresponding bandwidth; "AZI" is the corresponding satellite's overhead viewing angle, which are: 43, 249, 52, 271, 244, 157, 5, 329, 195, -, 148, 148, 257, 237; "ELE" is the corresponding satellite's elevation angle, which are: 8, 11, 34, 48, 16, 75, 48, 38, 16, -, 59, 59, 20, 46.

[0241] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A power supply system, characterized in that: include: An interface, an external power supply circuit, a battery power supply circuit and a first capacitor; the interface is used for an external power supply; the interface is also connected to the input end of the external power supply circuit, the first output end of the external power supply circuit and the first output end of the battery power supply circuit are both connected to a first load through one end of the first capacitor, and the other end of the first capacitor is grounded.

2. The power supply system according to claim 1, characterized in that: The external power supply circuit includes a converter and a first unidirectional conductive switch, the input end of the converter is connected to the input end of the external power supply circuit, the output end of the converter is connected to the anode of the first unidirectional conductive switch, and the cathode of the first unidirectional conductive switch is connected to the first output end of the external power supply circuit.

3. The power supply system according to claim 2, characterized in that: The external power supply circuit further includes: an external power clamp filter module; the input end of the converter is connected to the input end of the external power supply circuit through the external power clamp filter module; and / or, a second capacitor; one end of the second capacitor is connected to the output end of the converter, and the other end is grounded; and / or, an inductor; one end of the second capacitor is connected to the output end of the converter through the inductor; And / or, a sampling component; the sampling component comprises a first resistor, a second resistor and a feedforward capacitor, one end of the first resistor is connected to one end of the second capacitor, the other end of the first resistor is respectively connected to one end of the second resistor and a feedback pin of a DC / DC converter chip included in the converter, and the other end of the second resistor is grounded; the feedforward capacitor is connected in parallel with the first resistor; And / or, a fourth unidirectional conductive switch; the anode of the fourth unidirectional conductive switch is connected to the output end of the converter, the cathode of the fourth unidirectional conductive switch is connected to the second output end of the external power supply circuit, and the second output end of the external power supply circuit is used to connect a second load.

4. The power supply system according to claim 3, characterized in that: One end of the second capacitor is connected to the inductor through the first power line, one end of the second capacitor is connected to the anode of the first unidirectional conductive switch through the second power line, and one end of the second capacitor is connected to the anode of the fourth unidirectional conductive switch through the third power line.

5. The power supply system according to any one of claims 2 to 4, characterized in that: The battery powered circuit includes a battery and at least one of the following: a second unidirectional conductive switch; an anode of the second unidirectional conductive switch is connected to the output terminal of the battery, and a cathode of the second unidirectional conductive switch is connected to the first output terminal of the battery power supply circuit; A first switching tube; The input end of the first switch tube is connected to the output end of the battery, the output end of the first switch tube is connected to the first output end of the battery power supply circuit, and the control end of the first switch tube is connected to the first load; a third unidirectional conductive switch; an anode of the third unidirectional conductive switch is connected to the output end of the battery, and a cathode of the third unidirectional conductive switch is connected to the second output end of the battery power supply circuit; the second output end of the battery power supply circuit is used to connect a second load.

6. The power supply system according to claim 5, characterized in that: The battery powered circuit further comprises: A second switch tube; an input end of the second switch tube is connected to an output end of the battery, an output end of the second switch tube is connected to a second output end of the battery power supply circuit, and a control end of the second switch tube is connected to the second load; and / or, a third capacitor; one end of the third capacitor is connected to the output ends of the external power supply circuit and the battery power supply circuit respectively, and the other end of the third capacitor is grounded; And / or, a fourth capacitor; the battery included in the battery power supply circuit is connected to the anodes of the second unidirectional conductive switch and the third unidirectional conductive switch respectively through one end of the fourth capacitor, and the other end of the fourth capacitor is grounded.

7. The power supply system according to claim 5, characterized in that: The power supply system further includes a charging module, the output end of the charging module is connected to the charging end of the battery power supply circuit, and the input end of the charging module is connected to one end of a second capacitor included in the external power supply circuit; And / or, the charging module is connected to a first load and / or a second load; the first load and / or the second load is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the output voltage is not within a preset range; The charging module is used to start up upon receiving a charging instruction sent by the first load and / or the second load, so as to charge the battery; And / or, the power supply system also includes a processor, which is electrically connected to the charging module, and the processor is used to determine whether the output voltage of the battery is within a preset range, and send a charging instruction to the charging module when the judgment is no.

8. The power supply system according to claim 4, characterized in that: The capacitance value of the second capacitor is determined according to at least one of the following: the switching frequency of the converter, the working current of the load, and the ripple current; And / or, the impedance characteristic curve of the second capacitor matches the switching frequency of the converter.

9. The power supply system according to claim 5, characterized in that: The power supply system further includes a first switch tube, wherein an input end of the first switch tube is connected to an anode of the second unidirectional conductive switch, an output end of the first switch tube is connected to a cathode of the second unidirectional conductive switch, and a control end of the first switch tube is connected to the first load and / or the second load; And / or, the power supply system further includes a second switch tube, an input end of the second switch tube is connected to an anode of the third unidirectional conductive switch, an output end of the second switch tube is connected to a cathode of the third unidirectional conductive switch, and a control end of the second switch tube is connected to the first load and / or the second load; And / or, the power supply system further includes a third switch tube, an input end of the third switch tube is connected to the anode of the first unidirectional conductive switch, an output end of the third switch tube is connected to the cathode of the first unidirectional conductive switch, and a control end of the third switch tube is connected to the first load and / or the second load; And / or, the power supply system also includes a fourth switch tube, the input end of the fourth switch tube is connected to the anode of a fourth unidirectional conductive switch included in the external power supply circuit, the output end of the fourth switch tube is connected to the cathode of the fourth unidirectional conductive switch, and the control end of the fourth switch tube is connected to the first load and / or the second load.

10. The power supply system according to claim 9, characterized in that: The first load is an LTE module, and the second load is a GPS module; the power supply system further includes a normally closed low-voltage dropout linear regulator, and the output end of the external power supply circuit and the output end of the battery power supply circuit are connected to the GPS module through the low-voltage dropout linear regulator; The LTE module is also in communication connection with the low-dropout linear regulator, and the LTE module is used to send an activation signal to the low-dropout linear regulator to activate the low-dropout linear regulator to supply power to the GPS module; And / or, the power supply system further includes a processor, the processor is electrically connected to the low voltage dropout linear regulator, and the processor is used to send an enable signal to the low voltage dropout linear regulator to enable the low voltage dropout linear regulator to supply power to the GPS module; And / or, the processor is electrically connected to control ends of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube respectively.

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