Power supply system

Abstract

The invention provides a power supply system. The power supply system comprises a power interface, a converter, a first one-way conductive switch, a linear charging module and a battery, the power interface is connected with the anode of the first one-way conductive switch and the input end of the linear charging module through the converter, and the output end of the linear charging module is connected with the battery; the power interface is externally connected with a power supply; the converter is used for converting the voltage of the external power supply into a target voltage and outputting the target voltage to the battery to charge the battery, or outputting the target voltage to the load to supply power to the load. The linear charging module is used for charging the battery, the cost is low, and strong interference cannot be generated. And the load can be supplied with power through a group of transformers, the battery can be charged, a group of converters does not need to be additionally arranged, the heating of the linear charging module is not very high due to the setting of the target voltage, and a radiator does not need to be additionally arranged for heat dissipation.

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] Traditional power supply circuits generally use an external power supply combined with a DC / DC converter to supply power to the load, and use a switch-type charging circuit to charge the battery from the external power supply. Since the switch-type charging circuit and DC / DC converter are both switch-type power supplies, they are very strong interference sources and radiation sources, and they have very strong interference on sensitive devices (such as audio devices, radio frequency devices) and sensitive signals (audio signals, radio frequency signals, differential signals, etc.) in electronic devices. And when the charging current is large, the switch-type charging circuit will heat up very badly, and even affect the normal operation of the electronic equipment. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a power supply system in order to overcome the above-mentioned defects in the prior art.

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

[0005] A power supply system, comprising: a power interface, a converter, a first isolation diode, a linear charging module and a battery, wherein the power interface is respectively connected to an anode of the first isolation diode and an input end of the linear charging module through the converter, and an output end of the linear charging module is connected to the battery;

[0006] Power interface, used for external power supply;

[0007] A converter is used to convert the voltage of the external power supply into a target voltage, and output the target voltage to the battery through the linear charging module to charge the battery, or output the target voltage to a load connected to the cathode of the first isolation diode to power the load; wherein the target voltage is greater than or equal to the maximum charging voltage of the battery, and the output voltage of the first isolation diode falls within the working range of the load.

[0008] Optionally, the converter comprises: a DC / DC converter chip and a sampling component;

[0009] The input end of the DC / DC converter chip is connected to the input end of the converter, the output end of the DC / DC converter chip is connected to the output end of the converter, the feedback pin of the DC / DC converter chip is connected to the output end of the sampling component, and the input end of the sampling component is connected to the output end of the converter;

[0010] The target voltage is determined according to a reference voltage source of the DC / DC converter chip and a resistance value of a resistor included in the sampling component.

[0011] Optionally, the sampling component includes a first resistor and a second resistor;

[0012] One end of the first resistor is used as the input end of the sampling component, and the other end of the first resistor is used as the output end of the sampling component; one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded;

[0013] The target voltage is calculated by the following formula:

[0014] V1=V REF ×(R1 / R2+1);

[0015] Wherein, V1 represents the target voltage, VREF represents the reference voltage source, R1 represents the resistance value of the first resistor, and R2 represents the resistance value of the second resistor.

[0016] Optionally, the sampling component further includes a feedforward capacitor; the feedforward capacitor is connected in parallel with the first resistor.

[0017] Optionally, the power supply system further includes:

[0018] a second isolation diode, wherein an anode of the second isolation diode is connected to the battery, and a cathode of the second isolation diode is used to connect to a load;

[0019] And / or, a triode, the input end of the switch tube is connected to the battery, the output end of the switch tube is used to connect to the power supply end of the load; the control end of the switch tube is connected to the signal output end of the load.

[0020] Optionally, the power supply system further includes a first capacitor; one end of the first capacitor is connected to the cathodes of the first isolation diode and the second isolation diode respectively, and the other end of the first capacitor is grounded.

[0021] Optionally, the power supply system further includes 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.

[0022] Optionally, the power supply system further includes an inductor; one end of the second capacitor is connected to the output end of the converter through the inductor.

[0023] Optionally, the power supply system further includes a third capacitor; one end of the third capacitor is connected to the anode of the second isolation diode, and the other end of the second capacitor is grounded.

[0024] Optionally, the power supply system further includes: an external power clamp filter module; the input end of the converter is connected to the power interface through the external power clamp filter module.

[0025] 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.

[0026] The positive and progressive effects of the present invention are: the present invention uses a linear charging module to charge the battery, the linear charging module is low in cost, and will not produce very strong interference to affect the normal operation of sensitive devices and sensitive signals in the electronic equipment containing the linear charging module. In addition, the converter converts the external power supply into a target voltage that meets the charging requirements of the battery and the working voltage requirements of the load, so that a set of transformers can both supply power to the load and charge the battery, without the need to add an additional set of converters, which can reduce costs, and the setting of the target voltage makes the heat generation of the linear charging module not very high, and there is no need to add an additional heat sink for heat dissipation, which can further reduce costs and size. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A circuit diagram of a power supply system provided for an exemplary embodiment of the present invention;

[0028] Figure 2 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0029] Figure 3 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0030] Figure 4 A circuit diagram of another power supply system provided for an exemplary embodiment of the present invention;

[0031] Figure 5 A schematic diagram of a charging process of a power supply system provided by an exemplary embodiment of the present invention;

[0032] Figure 6 A schematic diagram of a charging process of another power supply system provided by an exemplary embodiment of the present invention;

[0033] Figure 7 A schematic diagram of a power supply ripple voltage provided by a power supply system for supplying power to a load according to an exemplary embodiment of the present invention;

[0034] Figure 8 A schematic diagram of a power supply ripple voltage provided by a power supply system for supplying power to a load according to an exemplary embodiment of the present invention;

[0035] Fig. 9A schematic diagram of test results of radiation values ​​emitted in a test frequency band of 30MHz to 1GHz for a vehicle-mounted wireless device provided by a power supply system according to an exemplary embodiment of the present invention;

[0036] Fig.10 A schematic diagram of test results of a power supply system provided by an exemplary embodiment of the present invention applied to a static test of a GPS antenna of a wireless vehicle-mounted device in an open space. DETAILED DESCRIPTION

[0037] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0038] 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.

[0039] An embodiment of the present invention provides a power supply system, which includes: a power input end, a converter, a first unidirectional conductive switch, a linear charging module and a battery, wherein the power input end is connected to the anode of the first unidirectional conductive switch and the input end of the linear charging module through the converter, and the output end of the linear charging module is connected to the battery.

[0040] The power input terminal is used for an external power source. The converter is used to convert the voltage of the external power source into a target voltage, and output the target voltage to the battery through the linear charging module to charge the battery, or output the target voltage to the load connected to the cathode of the first unidirectional conductive switch to supply power to the load; wherein the target voltage is greater than or equal to the maximum charging voltage of the battery, and the output voltage of the first unidirectional conductive switch falls within the working range of the load.

[0041] The present invention uses a linear charging module to charge the battery. The linear charging module has low cost and will not generate very strong interference to affect the normal operation of sensitive devices and sensitive signals in the electronic equipment containing the linear charging module. In addition, the converter converts the external power supply into a target voltage that meets the charging requirements of the battery and the working voltage requirements of the load, so that a set of transformers can both supply power to the load and charge the battery, without the need to add an additional set of converters, which can reduce costs. In addition, the setting of the target voltage makes the heat generation of the linear charging module not very high, and there is no need to add an additional heat sink for heat dissipation, which can further reduce costs and size.

[0042] 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.

[0043] 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.

[0044] The following further describes the power supply system by taking the battery power supply system applied to the field of electric vehicles, the converter using a DC / DC converter, and the unidirectional conductive switch using an isolation diode as an example.

[0045] See also Figure 1 When powered by an external power source, the 8V-100V power source from the power interface 70 (for example, a car cigarette lighter, an electric bicycle, an electric motorcycle, or a scooter) 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 Ve1 (generally 5V) is generated by the output terminal E1 of the DC / DC converter 94 (the 1st pin of the output capacitor C1 (the second capacitor) is connected to the E1 terminal, and the 2nd pin of the output capacitor C1 is connected to the ground G), and the power supply voltage V31 is provided to the LTE module 95 (load) through the isolation diode D1 (the first unidirectional conductive switch) and the capacitor C5 (the first capacitor), and the working current in the K1 path of the power line is i11. Among them, the capacitor C5 can be a single capacitor, or multiple capacitors of the same capacitance or multiple capacitors of different capacitance.

[0046] The path of the power line from the output terminal E1 of the DC / DC converter 94 to the common terminal E2 is K1. The LTE module 95 is connected to the antenna 97 through the a1 terminal. When the LTE module 95 is working, the modulated radio frequency signal is radiated to the outside through the antenna 97, generating electromagnetic waves for wireless communication with the outside world.

[0047] In the K1 path of the power supply line, the main voltage drop is distributed at the cathode k and anode a of the isolation diode D1, and generally a voltage drop of 0.5V to 0.7V is generated in the isolation diode D1. If the output voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is 5V, it is calculated that the power supply voltage range of the power input terminal vd1 of the LTE module 95 is 5V-0.5V=4.5V, 5V-0.7V=4.3V, that is, the voltage range obtained at pin 1 of the capacitor C5 of the LTE module 95 is 4.3V~4.5V.

[0048] Although the common terminal E2 is connected to the input terminal of the low-dropout linear regulator (LDO) module 99, the low-dropout linear regulator (LDO) module 99 is provided with a function of normally shutting down the low-dropout linear regulator (LDO) module 99, so that the GPS module 96 (load) cannot be powered, and the GPS module 96 cannot work normally. The function realized at this time is that the DC / DC converter 94 supplies power to the LTE module 95 alone.

[0049] The enable signal B of the LTE module 95 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.

[0050] The positive electrode of the battery 93 is connected to the anode a of the isolation diode D2 (the second unidirectional conductive switch), the cathode k of the isolation diode D2 is connected to the cathode k of the isolation diode D1, the common terminal E2, the pin 1 and the pad of the capacitor C5, and the pin 1 and the pad of the capacitor C4, and the anode a of the isolation diode D1 is connected to the pin 1 and the pad of the output capacitor C1 in the DC / DC converter 94. That is, the positive electrode of the battery 93 is electrically connected to the common terminal E2, the pin 1 and the pad of the capacitor C5, and the pin 1 and the pad of the capacitor C4 through the isolation diode D2. However, since the voltage from the positive output voltage Ve2 of the battery 93 to the common terminal E2 through the anode a and cathode k of the isolation diode D2 is lower than the voltage from the output terminal E1 to the common terminal E2 in the DC / DC converter 94, the isolation diode D2 is not conducting. As long as the car cigarette lighter port 70 provides power to the LTE module 95 and other loads 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. In this way, the unidirectional power supply function of the external power supply is realized, and the battery 93 does not work normally, and only serves as an emergency power supply, thereby extending the service life of the battery 93.

[0051] 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 capacitor C1 in the DC / DC converter 94 outputs the power supply voltage Ve1, which is directly supplied to the LTE module 95 through the isolation diode D1 and the capacitor C5, generating the working current i11, which is processed by the baseband chip and the radio frequency chip inside the LTE module 95 to generate the radio frequency signal, which is radiated to the outside through the LTE antenna 97, generating radio waves, and 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 the off state, and the GPS module 96 stops working. At this time, the output current of the output capacitor C1 in the DC / DC converter 94 is equal to the LTE module power supply current i11.

[0052] 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 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 connected to the ground G (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 send a charging indication signal, the charging module 98 will not work, and the battery 93 is in a disconnected state, thus realizing the function of neither charging nor discharging the battery 93, greatly extending the service life of the battery 93 (the number of times the battery 93 is charged and discharged will affect its service life). In this embodiment, the charging module adopts a linear charging module.

[0053] 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 isolation diode. 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.

[0054] The 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 isolation diode D1 must be taken into account to ensure that the power supply voltage on the 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 capacitor C4 meets the low voltage difference linear regulator (LDO) 99 to output a normal 1.8V voltage to meet the normal operation of the GPS module 96. The current carrying capacity of the isolation diode D1 is greater than the operating current i11 under the conditions of the LTE module 95 (at full load LTE maximum transmission power) + GPS module 96 working at the same time, and a margin of more than 1 / 4 is reserved to avoid burning out the isolation diode D1.

[0055] Figure 2 A schematic diagram of an external power supply + DC / DC converter to power the LTE module and GPS module separately is given. Figure 2 that is Figure 1 A partial enlargement of Figure 1 The internal circuit of the DC / DC converter chip 90, the peripheral circuit of the DC / DC converter 94, and the internal components of the charging module 98 are displayed. Figure 2 The battery is a lithium-ion battery, a BUCK power topology, and a linear charging chip is used as an example for illustration. The type of battery 93 (it can also be a lead-acid battery, a nickel-hydrogen battery, etc.), the structure of the power topology (for example, it can also be a BOOST or BUCK-BOOST power topology, etc.), and the linear charging chip forming a linear charging module can also be changed to a linear charging solution composed of discrete components. Figure 2 As shown, the DC / DC converter 94 is mainly composed of an input capacitor C11, a DC / DC converter chip 90, a sampling component 88, an inductor L1, an output capacitor C1, etc. The DC / DC converter chip 90 has an upper power switch Q8, a lower power switch Q9, and a reference voltage source V REF, clock generator 84 and other functional circuits, 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, 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 DC / DC converter chip 90 is connected to the system ground powered by 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, pin 2 of the input capacitor C11, pin 2 of the output capacitor C1, pin 2 of the capacitor C5, the ground pin G4 of the LTE module 95, pin 2 of the 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 pin 1 of the inductor L1, and the pin 2 of the inductor L1 is connected to the pin 1 of the output capacitor C1. The sampling component 88 is placed close to the feedback pin FB of the DC / DC converter chip 90. A trace 86 is led from the feedback pin FB of the DC / DC converter chip 90 to one end of the sampling component 88, and a sampling trace 87 is led from the other end of the sampling component 88 to the pin 1 position of the output capacitor C1.

[0056] Taking the output voltage V1 of the output terminal E1 of the DC / DC converter 94 as 4.436V as an example, how to set the output voltage V1 (target voltage) of the DC / DC converter 94 (taking the BUCK power supply as an example) is described.

[0057] Figure 3 Another schematic diagram is given of an external power supply + DC / DC converter to power the LTE module and GPS module separately. Figure 3 is Figure 2 On the basis of the scheme, the specific composition of the sampling component 88 is given in detail. The sampling component 88 includes a resistor R1, a resistor R2, and a feedforward capacitor C8. Pin 2 of the resistor R1 is connected to pin 1 of the resistor R2, and pin 2 of the resistor R2 is connected to ground G (grounded). Pin 1 of the feedforward capacitor C8 is connected to pin 1 of the resistor R1, and pin 2 of the capacitor C8 is connected to pin 2 of the resistor R1. A sampling line 87 is led out from pin 1 of the output capacitor C1 and connected to pin 1 of the feedforward capacitor C8 and pin 1 of the resistor R1. A line 86 is led out from the feedback pin FB of the DC / DC converter chip 90 and connected to pin 2 of the feedforward capacitor C8, pin 1 of the resistor R2, and pin 2 of the resistor R1. C1 is an advanced phase compensation capacitor at the feedback end, which has the function of accelerating and stabilizing the output voltage V1. Taking the output voltage V1 of 4.436V at the output end E1 of the DC / DC converter 94 as an example, how to set the output voltage of the BUCK is illustrated. Assume that the reference power supply V of the DC / DC converter chip 90 is V REFIt is 0.8V, R1=100KΩ, R2=22KΩ.

[0058] Output voltage V1 = V REF ×(R1 / R2+1)=0.8V×(100KΩ / 22KΩ+1)=4.436V

[0059] The charging module 98 (including the linear charging chip) has a built-in power switch Q7 (only a triode is used as an example for explanation, and the type of the power switch Q7 is not limited. The power switch can also be a thyristor, IGBT, MOSFET, relay, etc.), the e pin of the power switch Q7 is connected to the Vi input terminal of the charging module 98, the c pin of the power switch Q7 is connected to the Vo output terminal of the charging module 98, the b pin of the power switch Q7 is connected to the internal control circuit 72, and the internal control circuit 72 is connected to the e2 terminal of the charging module 98. The power line is led out from the 1 pin (1 pin is the positive pole, and the output voltage Ve1) of the output capacitor C1 of the DC / DC converter 94 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, and the negative pole of the battery 93 is connected to the ground G (ground). The LTE module output C signal routing is connected to the e2 terminal of the charging module 98, which is used to control the on and off state of the charging module 98 (that is, the two states of on and off).

[0060] 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 LTE module 95 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 digital transmission current is 589mA in EGSM900 1D / 4U PCL=5 mode, the maximum value of the digital transmission current is 541mA in WCDMAB1HSDPA541 mode, and the maximum value of the digital transmission current is 710mA in LTE B3 mode; in LTEDRX=5 mode, the maximum value of the standby current is 5.5μA; the instantaneous current of RF transmission reaches 3A.

[0061] Table 1 Characteristics of a certain model of LTE module power supply

[0062]

[0063]

[0064] By adjusting the parameters of the sampling component 88, the voltage at the output terminal E1 of the DC / DC converter 94 is 4.35V to 4.7V. After being isolated by the isolation diode D1 (generating a voltage drop of about 0.7V), a voltage of 3.736V (4.436V-0.7V=3.736V) to 4.0V (4.7V-0.7V=4.0V) is obtained at the vd1 terminal of the LTE module 95. The voltage of 3.736V to 4.0V is not only The operating voltage range is within the range of V to 4.4V, and is very close to the typical operating voltage of 3.8V of the LTE module 95. The maximum voltage at the vd1 end of the LTE module 95 is 4.0V, and a 0.4V margin must be reserved. Otherwise, once the voltage at the output end E1 of the DC / DC converter 94 exceeds 5.1V, minus the 0.7V voltage drop of the isolation diode D1, the voltage at the vd1 end of the LTE module 95 will exceed the maximum voltage of 4.4V, causing damage to the LTE module 95.

[0065] The maximum voltage of the fully charged battery 93 is 4.2V, so the minimum output voltage of the output terminal E1 of the DC / DC converter 94 must be greater than 4.2V. Considering that the power switch Q7 inside the charging module 98 still has a voltage drop of 0.1V to 0.15V, the minimum voltage of the output terminal E1 of the DC / DC converter 94 is set to 4.35V, which just meets the maximum voltage of 4.2V for the charging module 98 to fully charge the battery 93. Otherwise, the battery 93 cannot be fully charged to meet the 4.2V requirement.

[0066] If the voltage Ve1 at the output terminal E1 of the DC / DC converter 94 is adjusted to 4.8V, it is reduced by 0.7V through the isolation diode D1, and a voltage of 4.1V is obtained at the power supply terminal vd1 of the LTE module 95. Combined with the accuracy error of the internal feedback of the DC / DC converter 94 and the fluctuation of the voltage Ve1 at the output terminal E1, it is very likely to exceed the maximum operating voltage of 4.4V of the power supply terminal vd1 of the LTE module 95 in Table 1, causing damage to the LTE module 95. If the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is adjusted to 6V, a voltage of 5.3V is obtained at the power terminal vd1 of the LTE module 95. It is also necessary to add a BUCK power supply or a BUCK-BOOST power supply between the output terminal E1 of the DC / DC converter 94 and the power terminal vd1 of the LTE module 95 to meet the basic requirement of the 3.2-4.4V working voltage of the power terminal vd1 of the LTE module 95. The cost is greatly increased, and the layout density of the printed circuit board is also increased. At the same time, the dynamic response capability of the two-stage DC / DC converter is much lower than that of the single-stage DC / DC converter (for example Figure 2-3The DC / DC converter solution shown in the figure) shows that the drop phenomenon of the power supply terminal vd1 of the LTE module 95 is more obvious. Another problem is that the charging module 98 between the output terminal E1 of the DC / DC converter 94 and the battery 93 adopts a low-cost linear charging solution. As long as the output voltage of the output terminal E1 of the DC / DC converter 94 exceeds 4.35V, it can meet the maximum charging voltage requirement of 4.2V of the battery 93. When the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 exceeds 4.8V, the greater the voltage drop of the charging module 98 between the output terminal E1 of the DC / DC converter 94 and the battery 93, the greater the heat power consumption generated in the charging module 98, and heat dissipation is another troublesome problem.

[0067] In summary, the voltage Ve1 of the output terminal E1 of the DC / DC converter 94 is adjusted to 4.35V~4.7V, which meets the requirement of the charging module 98 composed of the linear charging chip for the maximum charging voltage of 4.2V for the battery 93. The use of a single-stage DC / DC converter also meets the LTE module's operating voltage range of 3.2V~4.4V. At the same time, the charging module 98 composed of a linear charging chip (or a linear charging module composed of discrete devices) is cheaper than the charging module 98 composed of a switching charging chip. The charging module 98 composed of a linear charging chip (or a linear charging module composed of discrete devices) does not generate high-frequency switching noise like the switching charging module when working, which affects the performance of the GPS antenna and the LTE antenna, and also affects the EMI radiation index, achieving multiple goals at one stroke.

[0068] Figure 4 The schematic diagram of external power supply + DC / DC converter to power LTE module and charge battery is given. Figure 1 Comparison of the schemes in Figure 4 The solution in the embodiment also adds an external power supply + DC / DC converter 94 and a charging module 98 to charge the battery 93, as shown in the functional signal flow diagram.

[0069] The battery voltage detection terminal ad 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 ad of the LTE module 95 will always monitor the output voltage of the battery 93 to determine whether the working condition of the battery 93 is normal: ① Whether the battery 93 is lower than the discharge threshold voltage (for example, the lithium battery discharge threshold voltage 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 battery 93 power supply system must be 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 loads such as the LTE module 95 will obtain a voltage lower than the working power supply voltage, resulting in failure to work normally; at the same time, the battery 93 continues to supply power to the LT when it is lower than the discharge threshold voltage. ② When the external power supply + DC / DC converter 94 charges the battery 93 via the charging module 98, the battery voltage detection terminal ad of the LTE module 95 constantly monitors whether the output voltage of the battery 93 exceeds the charging threshold voltage. Once the battery voltage detection terminal ad of the LTE module 95 detects that the output voltage of the battery 93 exceeds the charging threshold voltage, the LTE module 95 sends a shutdown signal C to the enable terminal e2 of the charging module 98, so that the charging module 98 stops charging the battery 93, thereby avoiding affecting the service life of the battery 93 and preventing the battery 93 from being overcharged, causing fire, explosion and other serious accidents.

[0070] Therefore, the function of the battery voltage detection terminal ad 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.

[0071] The relationship between the working current i38 from the output terminal E1 of the DC / DC converter 94 to the anode a of the isolation diode D1, the charging current i8 from the anode a of the 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 isolation diode D1, the cathode k of the isolation diode D1 to the working current i3 between the 1st pin of the capacitor C5 of the LTE module 95 satisfies:

[0072] i38=i8+i3;

[0073] 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 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 isolation diode D1 satisfies:

[0074] i1=i2+i38;

[0075] When the battery voltage detection terminal ad 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-voltage dropout linear regulator (LDO) 99 of the LTE module 95, the low-voltage dropout linear regulator (LDO) 99 is in the off state, and the GPS module 96 is in the power-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 / 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 isolation diode D2 / transistor Q1 is in the off state, and the battery 93 in the charging state does not discharge. In summary, the function of external power supply + DC / DC converter 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 capacitor C5 is V7, and the voltage at the pin 1 of the capacitor C4 of the low voltage dropout linear regulator (LDO) 99 is V81.

[0076] Figure 4 The other parts of the solution have the same functions as Figure 1 Basically the same, no repetitive description is given.

[0077] In one embodiment, the battery 93 is a lithium-ion battery, the negative electrode of which is a graphite crystal, and the positive electrode is usually lithium dioxide. When charging, lithium ions move from the positive electrode to the negative electrode and are embedded in the graphite layer. When discharging, lithium ions detach from the negative electrode surface in the graphite crystal and move to the positive electrode. Therefore, during the charging and discharging process of the battery, lithium always appears in the form of lithium ions, rather than in the form of metallic lithium. Therefore, this type of battery is called a lithium-ion battery, or lithium battery for short. Secondary lithium batteries have the advantages of high energy density, no memory effect, light weight, no pollution, long cycle life, and low self-discharge. Polymer lithium batteries have the following advantages: no battery leakage problem, the battery does not contain liquid electrolyte, and uses colloidal solid; can be made into thin batteries: 3.6V400mAh capacity, its thickness can be as thin as 0.5mm; the battery can be designed into a variety of shapes; the battery can be bent and deformed: the polymer battery can be bent up to about 900; can be made into a single high voltage: liquid electrolyte batteries can only obtain high voltage by connecting several batteries in series, and since polymer batteries do not have liquid themselves, they can be made into a multi-layer combination in a single battery to achieve high voltage; the capacity will be twice that of lithium-ion batteries of the same size.

[0078] The rated voltage of lithium-ion batteries is 3.6V (some products are 3.7V), and the termination voltage of charging when fully charged is related to the battery anode material: 4.2V for graphite anode material; 4.1V for coke anode material. The internal resistance of different anode materials is also different. The internal resistance of coke anode is slightly larger, and its discharge curve is also slightly different. It is generally called 4.1V lithium-ion battery and 4.2V lithium-ion battery. Most of the ones used now are 4.2V, and the termination discharge voltage of lithium-ion batteries is 2.5V~2.75V (the battery factory gives the operating voltage range or the termination discharge voltage, and the parameters are slightly different). In the lithium battery labeling, 3.7V refers to the platform voltage of the battery during discharge, and 4.2 volts refers to the voltage when fully charged.

[0079] Lithium batteries need to be fully charged before storage. They can be stored at 20°C for more than half a year, and lithium batteries are suitable for storage at low temperatures. In a lithium battery power supply system, three circuits are required: ① Lithium battery charging circuit. Lithium batteries have high charging requirements and need to be charged with a dedicated constant voltage and constant current charger; ② Lithium battery protection circuit. The protection circuit provides overcharge, over-discharge, short circuit overcurrent, and over-temperature protection for lithium batteries; ③ Lithium battery output circuit. A 3.7V lithium battery is 4.2V after being fully charged, and the discharge platform voltage is 3.7V. For embedded systems or other load circuits, the 3.7V voltage needs to be stepped up or down to 5V, 3.3V, etc. before it can be used.

[0080] The following introduces the charging and discharging requirements of lithium batteries. (1) Charging of lithium batteries: Lithium batteries have high charging requirements and need to be charged with a dedicated constant voltage and constant current charger. Usually, constant current charging is performed to 4.2V / cell and then constant voltage charging is performed. When the constant voltage charging current drops below 100mA, charging should be stopped. Overcharging of lithium batteries: According to the structural characteristics of lithium batteries, the maximum charging termination voltage is 4.2V. Continuing to charge after the battery is fully charged will cause the battery to be overcharged. Since the negative electrode capacity of lithium batteries is higher than the positive electrode capacity during design, overcharging will cause too much lithium ions in the positive electrode to be consumed, which will damage the battery and make the battery scrapped. The charging current (mA) is 0.1 to 1.5 times the battery capacity (for example, for a 1000mAh battery, the charging current can be controlled between 100 and 1500mA). The charging current between 0.2C and 0.8C is more suitable. The conventional charging current can be selected at about 0.5 times the battery capacity, and the charging time is about 2 to 3 hours. (2) Discharge of lithium batteries: Due to the internal structure of lithium batteries, lithium ions cannot all move to the positive electrode during discharge. Some lithium ions must be retained at the negative electrode to ensure that the lithium ions can be smoothly embedded in the channel during the next charge. Otherwise, the battery life will be shortened accordingly. In order to ensure that some lithium ions remain in the graphite layer after discharge, the minimum discharge termination voltage must be strictly limited, that is, the lithium battery cannot be over-discharged.

[0081] The discharge end voltage is usually 3.0V / cell, and the minimum cannot be lower than 2.5V / cell. The discharge cut-off voltage is generally determined based on the discharge current. 0.2C-2C discharge is generally set at 1.0V / cell, and above 3℃, such as 5C or 10C discharge, it is set at 0.8V / cell. The battery discharge time is related to the battery capacity and the discharge current. Battery discharge time (hours) = battery capacity / discharge current The lithium battery discharge current (mA) should not exceed 3 times of the battery capacity. (For example, for a 1000mAH battery, the discharge current should be strictly controlled within 3A) Otherwise, the battery will be damaged.

[0082] The following describes the lithium battery charging process. Figure 5 The charging process of lithium-ion batteries can be divided into: trickle charging (low-voltage pre-charging), constant current charging, constant voltage charging and charging termination.

[0083] The charging method of lithium battery is voltage-limited constant current, which is controlled by IC chip. The typical charging method is: first detect the voltage of the battery to be charged. If the voltage is lower than 3V, pre-charge it first, and the charging current is 1 / 10 of the set current. After the voltage rises to 3V, enter the standard charging process. Figure 6 The standard charging process is: constant current charging with a set current, when the battery voltage rises to 4.20V, it is changed to constant voltage charging, and the charging voltage is kept at 4.20V. At this time, the charging current gradually decreases, and when the current drops to 1 / 10 of the set charging current, the charging is completed.

[0084] (1) Trickle charge stage (when the battery is over-discharged and the voltage is low)

[0085] The dielectric inside the lithium battery will undergo some physical changes, causing the charging characteristics to deteriorate and the capacity to decrease. At this stage, the lithium battery can only be charged slowly through a trickle, so that the dielectric inside the lithium battery slowly returns to a normal state. Trickle charging is used to pre-charge (recovery charge) a fully discharged battery. When the battery voltage is lower than about 3V, trickle charging is used. The trickle charging current is one-tenth of the constant current charging current, that is, 0.1C (taking a constant charging current of 1A as an example, the trickle charging current is 100mA).

[0086] (2) Constant current charging stage (the battery recovers from over-discharge to normal state) When the battery voltage rises above the trickle charge threshold, the charging current is increased for constant current charging. The current of constant current charging is between 0.2C and 1.0C. The battery voltage gradually increases with the constant current charging process. Generally, the voltage set for a single battery is 3.0-4.2V (3) Constant voltage charging stage (it is already more than 85% full and is slowly replenishing) When the battery voltage rises to 4.2V, the constant current charging ends and the constant voltage charging stage begins. The current is based on the saturation of the battery cell. As the charging process continues, the charging current slowly decreases from the maximum value. When it decreases to 0.01C, the charging is considered to be terminated. Among them, C is a method of expressing the nominal capacity of the battery against the current. For example, if the battery has a capacity of 1000mAh, 1C is a charging current of 1000mA.

[0087] (3) Charging termination: There are two typical charging termination methods, using the minimum charging current to judge Or use a timer (or a combination of the two). The minimum current method monitors the charging current during the constant voltage charging phase. The charging is terminated when the charging current decreases to the range of 0.02C to 0.07C. The second method starts from the beginning of the constant voltage charging stage and terminates the charging process after two hours of continuous charging.

[0088] The above charging method takes about 2.5 to 3 hours to charge a fully discharged battery. Advanced chargers also use more safety measures. For example, if the battery temperature exceeds the specified window (usually 0°C to 45°C), the charging will be suspended. After charging is completed, if the battery voltage is detected to be lower than the recharge threshold voltage of the charging IC, charging will be resumed.

[0089] The following is the testing process of the present invention:

[0090] In order to prove the rationality and practicality of the design of the power supply system provided by the embodiment of the present invention, Figure 1 Taking the application of the power supply system of the medium power supply in the wireless vehicle tracker as an example, the following tests were performed on the DC / DC converter output voltage: (1) power supply output voltage test, (2) power supply output voltage ripple test, and EMI radiation test.

[0091] (1) Power supply related testing and analysis process

[0092] Figure 7 The output voltage waveform of the DC / DC module is given when the load current is 3A;

[0093] Test conditions: wireless vehicle tracker, oscilloscope TDS2012C (sampling frequency 2GS / s, bandwidth 100MHz), digital power supply 66319D.

[0094] like Figure 7As 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 66319D 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 the oscilloscope TDS2012C+ probe to be a maximum value of 4.52V and a minimum value of 4.20V, which meets the design requirements.

[0095] like Figure 8 As shown, the LTE module is in GPRS maximum power CAT1 B1 mode. Figure 1 The power supply system 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 94.

[0096] (2) Power supply output voltage ripple test

[0097] The following describes the DC / DC module powering the LTE module. In GPRS mode, the maximum power is CAT1. B1 condition mode The power ripple of the power supply terminal vd1 of the LTE module.Under LTE B3 (FDD mode), when the transmit power is 20.19dB, 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.

[0098] (3) EMI radiation test and analysis process

[0099] Fig. 9 The 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 wireless vehicle equipment is tested in the 0.15MHz to 0.5MHz / 0.5MHz to 30MHz / 30MHz to 1GHz / 1GHz to 6GHz frequency bands. These frequency bands meet the Class B test requirements in the EN55022-2008 / GB9254-2008 standard. Figure 6 A refers to the safety limit of the 3C standard. If it is lower than this safety limit, it is qualified; B refers to the fluctuation curve of the radiation data of the tested product. Fig. 9 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.

[0100] Fig.10The static test of GPS antenna of wireless vehicle-mounted equipment in an open location is given. Fig.10 Where "PRN" is the specific GPS satellite number that the wireless vehicle-mounted device can search for at a certain open location and at a certain time point, 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 = 43), GPS satellite 34 (C / No value = 41), GPS satellite 35 (C / No value = 41), GPS satellite 36 (C / No value = 41), GPS satellite 37 (C / No value = 43), GPS satellite 19 (C / No value = 40), GPS satellite 30 (C / No value = 40), GPS satellite 28 (C / No value = 42), GPS satellite 50 (C / No value = 48), GPS satellite 41 (C / No value = 40); and "BAND" is the corresponding; "AZI" is the corresponding satellite's overhead viewing angles are: 43, 249, 52, 271, 244, 157, 5, 329, 195, -, 148, 148, 257, 237; "ELE" is the corresponding satellite's elevation angles are: 8, 11, 34, 48, 16, 75, 48, 38, 16, -, 59, 59, 20, 46.

[0101] 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: A power interface, a converter, a first unidirectional conductive switch, a linear charging module and a battery, wherein the power interface is respectively connected to the anode of the first unidirectional conductive switch and the input end of the linear charging module through the converter, and the output end of the linear charging module is connected to the battery; Power interface, used for external power supply; A converter is used to convert the voltage of the external power supply into a target voltage, and output the target voltage to the battery through the linear charging module to charge the battery, or output the target voltage to a load connected to the cathode of the first unidirectional conductive switch to power the load; wherein the target voltage is greater than or equal to the maximum charging voltage of the battery, and the output voltage of the first unidirectional conductive switch falls within the working range of the load.

2. The power supply system according to claim 1, characterized in that: The converter comprises: a DC / DC converter chip and a sampling component; The input end of the DC / DC converter chip is connected to the input end of the converter, the output end of the DC / DC converter chip is connected to the output end of the converter, the feedback pin of the DC / DC converter chip is connected to the output end of the sampling component, and the input end of the sampling component is connected to the output end of the converter; The target voltage is determined according to a reference voltage source of the DC / DC converter chip and a resistance value of a resistor included in the sampling component.

3. The power supply system according to claim 2, characterized in that: The sampling component includes a first resistor and a second resistor; One end of the first resistor is used as the input end of the sampling component, and the other end of the first resistor is used as the output end of the sampling component; one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded; The target voltage is calculated by the following formula: V1=V REF ×(R1 / R2+1); Where V1 represents the target voltage, V REF represents a reference voltage source, R1 represents the resistance value of the first resistor, and R2 represents the resistance value of the second resistor.

4. The power supply system according to claim 3, characterized in that: The sampling component further includes a feedforward capacitor; the feedforward capacitor is connected in parallel with the first resistor.

5. The power supply system according to any one of claims 1 to 4, characterized in that: The power supply system also includes: a second unidirectional conductive switch, wherein an anode of the second unidirectional conductive switch is connected to the battery, and a cathode of the second unidirectional conductive switch is used to connect to a load; And / or, a switch tube, the input end of the switch tube is connected to the battery, the output end of the switch tube is used to connect to the power supply end of the load; the control end of the switch tube is connected to the signal output end of the load.

6. The power supply system according to claim 5, characterized in that: The power supply system further includes a first capacitor; one end of the first capacitor is connected to the cathodes of the first unidirectional conductive switch and the second unidirectional conductive switch respectively, and the other end of the first capacitor is grounded.

7. The power supply system according to claim 6, characterized in that: The power supply system further includes 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.

8. The power supply system according to claim 7, characterized in that: The power supply system also includes an inductor; one end of the second capacitor is connected to the output end of the converter through the inductor.

9. The power supply system according to claim 5, characterized in that: The power supply system further includes a third capacitor; one end of the third capacitor is connected to the anode of the second unidirectional conductive switch, and the other end of the third capacitor is grounded.

10. The power supply system according to claim 5, characterized in that: The power supply system further includes: an external power clamp filter module; the input end of the converter is connected to the power interface through the external power clamp filter module.

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