TWI844394B - Electronic device with battery management - Google Patents

Abstract

An electronic device includes a first battery, a second battery, a first transistor, a second transistor, a third transistor, a fourth transistor, and a controller. The first transistor is electrically connected between the supply voltage and a first node. The second transistor is electrically connected between the first node and the first battery. The third transistor is electrically connected between the supply voltage and a second node. The fourth transistor is electrically connected between the second node and the second battery. The controller turns off the second transistor, turns on the third transistor, turns off the first transistor, and turns on the fourth transistor in sequence to switch the supply voltage from the voltage of the first battery to the voltage of the second battery.

Description

Electronic devices for battery management

The present invention relates to an electronic device and a power supply method thereof, and in particular to an electronic device that uses two or more batteries for power supply and a power supply method that switches between different batteries for power supply.

Lithium-ion batteries have high energy density and can store more electricity. They also have a longer lifespan and can be charged and discharged multiple times, but their discharge power is relatively low, and they often need to be connected in parallel to increase the discharge power. Other lithium batteries, such as lithium-iron batteries, have a discharge power that is 8 to 10 times that of lithium-ion batteries, which means they can output higher instantaneous currents and are more suitable for situations with high discharge requirements, such as when climbing a hill, high instantaneous currents allow the motor to generate greater torque. If you can use lithium-ion batteries on ordinary roads to obtain the maximum amount of electricity, and use lithium-iron batteries or other batteries with high discharge characteristics when high torque is required, the characteristics of the motor can be brought into full play.

Electric assisted bicycles on the market are generally equipped with a battery as a power supply. However, in order to increase the riding mileage, another battery is often added. Since different battery types have different performance and voltage values, two or more batteries may not be used in parallel and must be switched. Therefore, the controller needs to select a suitable battery for power supply according to different situations.

The present invention proposes an electronic device powered by two or more batteries and a power supply method for switching between different batteries. By using transistors that sequentially conduct and non-conduct the batteries, power supply can be smoothly switched from one battery to another. In addition, power supply can be switched to a more suitable battery according to the battery status and/or output current to maintain better power quality.

In view of this, the present invention proposes an electronic device, including a first battery, a second battery, a first transistor, a second transistor, a third transistor, a fourth transistor and a controller. The first battery has a first battery voltage, and the second battery has a second battery voltage. The first transistor is electrically connected between a supply voltage and a first node, and includes a first parasitic diode. The second transistor is electrically connected between the first node and the first battery, and includes a second parasitic diode, wherein the first parasitic diode and the second parasitic diode are used to provide the maximum of the first battery voltage and the supply voltage to the first node. The third transistor is electrically connected between the supply voltage and a second node, and includes a third parasitic diode. The fourth transistor is electrically connected between the second node and the second battery, and includes a fourth parasitic diode, wherein the third parasitic diode and the fourth parasitic diode are used to provide the maximum of the second battery voltage and the supply voltage to the second node. The controller sequentially turns off the second transistor, turns on the third transistor, turns off the first transistor, and turns on the fourth transistor, thereby switching the supply voltage from the first battery voltage to the second battery voltage.

According to an embodiment of the present invention, the first transistor includes a first first terminal, a first second terminal and a first control terminal, and the first parasitic diode includes a first anode terminal and a first cathode terminal, wherein the first anode terminal is electrically connected to the first first terminal, and the first cathode terminal is electrically connected to the first second terminal. The second transistor includes a second first terminal, a second second terminal and a second control terminal, and the second parasitic diode includes a second anode terminal and a second cathode terminal, wherein the second anode terminal is electrically connected to the second first terminal, and the second cathode terminal is electrically connected to the second second terminal. The third transistor includes a third first terminal, a third second terminal and a third control terminal, and the third parasitic diode includes a third anode terminal and a third cathode terminal, wherein the third anode terminal is electrically connected to the third first terminal, and the third cathode terminal is electrically connected to the third second terminal. The fourth transistor includes a fourth first terminal, a fourth second terminal and a fourth control terminal, and the fourth parasitic diode includes a fourth anode terminal and a fourth cathode terminal, wherein the fourth anode terminal is electrically connected to the fourth first terminal, and the fourth cathode terminal is electrically connected to the fourth second terminal.

According to one embodiment of the present invention, when the second transistor is not conducting first, the second parasitic diode is used to prevent the supply voltage from charging the first battery. When the third transistor is then conducting after the second transistor is not conducting, the fourth parasitic diode is used to prevent the supply voltage from charging the second battery.

According to one embodiment of the present invention, the electronic device further includes a voltage detection circuit. The voltage detection circuit includes a first resistor, a second resistor, a fifth transistor, a third resistor, a fourth resistor and a sixth transistor. The first resistor is electrically connected between the first battery voltage and a first detection voltage. The second resistor is electrically connected to the first detection voltage. The fifth transistor electrically connects the second resistor to a ground terminal according to a first read signal. The third resistor is electrically connected between the second battery voltage and a second detection voltage. The fourth resistor is electrically connected to the second detection voltage. The sixth transistor electrically connects the fourth resistor to the ground terminal according to a second read signal. The controller uses the first read signal and the second read signal to control the voltage detection circuit to generate the first detection voltage and the second detection voltage. The controller determines the first battery voltage based on the first detection voltage and determines the second battery voltage based on the second detection voltage. When the controller determines that the second battery voltage exceeds the first battery voltage, the controller switches the supply voltage from the first battery voltage to the second battery voltage.

According to an embodiment of the present invention, the supply voltage is used to supply power to a motor drive circuit, wherein the motor drive circuit drives a motor according to the supply voltage. The controller further reads the battery information of the first battery and the second battery and detects an output current of the supply voltage. When the output current exceeds a predetermined current, the controller uses the first transistor, the second transistor, the third transistor and the fourth transistor to output the second battery voltage as the supply voltage.

According to one embodiment of the present invention, the electronic device further includes a current detection circuit. The current detection circuit is used to detect the output current and generate a current detection signal. The controller determines whether the output current exceeds the predetermined current based on the current detection signal.

The present invention further provides a power supply method for switching between a first battery voltage of a first battery and a second battery voltage of a second battery to supply a supply voltage. A first transistor is electrically connected between the supply voltage and a first node, a second transistor is electrically connected between the first node and the first battery, a third transistor is electrically connected between the supply voltage and a second node, and a fourth transistor is electrically connected between the second node and the second battery. The power supply method includes: using the first battery to supply the supply voltage; determining whether to switch to the second battery for power supply; when determining to switch to the second battery, first turning off the second transistor; when the second transistor is not conducting, then turning on the third transistor; when the third transistor is conducting, then turning off the first transistor; and when the first transistor is not conducting, then turning on the fourth transistor, so that the second battery supplies the supply voltage.

According to one embodiment of the present invention, the first transistor further includes a first parasitic diode, and includes a first anode terminal and a first cathode terminal, wherein the first anode terminal is electrically connected to the first first terminal, and the first cathode terminal is electrically connected to the first second terminal. The second transistor further includes a second parasitic diode, and includes a second anode terminal and a second cathode terminal, wherein the second anode terminal is electrically connected to the second first terminal, and the second cathode terminal is electrically connected to the second second terminal. The third transistor further includes a third parasitic diode, and includes a third anode terminal and a third cathode terminal, wherein the third anode terminal is electrically connected to the third first terminal, and the third cathode terminal is electrically connected to the third second terminal. The fourth transistor further includes a fourth parasitic diode, and includes a fourth anode terminal and a fourth cathode terminal, wherein the fourth anode terminal is electrically connected to the fourth first terminal, and the fourth cathode terminal is electrically connected to the fourth second terminal. The second transistor is not turned on first, so that the second parasitic diode prevents the supply voltage from charging the second battery. When the second transistor is not turned on and the third transistor is turned on, the second parasitic diode and the fourth parasitic diode are used to select the one with the highest voltage between the first battery and the second battery to supply the supply voltage. Through the first control end, the second control end, the third control end and the fourth control end, the first transistor, the second transistor, the third transistor and the fourth transistor are controlled to be conductive or non-conductive.

According to an embodiment of the present invention, the step of determining whether to switch to the second battery for power supply further includes: detecting the first battery voltage of the first battery; detecting the second battery voltage of the second battery; and when the first battery voltage is less than the second battery voltage, determining to switch to the second battery for power supply.

According to an embodiment of the present invention, the supply voltage is used to supply power to a motor driving circuit, wherein the motor driving circuit drives a motor according to the supply voltage, wherein the power supply method further includes: determining whether an output current of the supply voltage exceeds a predetermined current; when it is determined that the output current exceeds the predetermined current, first turning off the second transistor, then turning on the third transistor, then turning off the first transistor, and then turning on the fourth transistor, so that the second battery supplies power to the supply voltage; when the output current is not less than the predetermined current, When the above-mentioned second battery is used for power supply, it is determined whether the above-mentioned output current is lower than the above-mentioned predetermined current when the above-mentioned second battery is used for power supply; when the above-mentioned output current is lower than the above-mentioned predetermined current, the above-mentioned first battery is used for power supply; when the above-mentioned output current is not lower than the above-mentioned predetermined current, the above-mentioned second battery is used for power supply; it is determined whether to stop driving the above-mentioned motor; when it is determined that the above-mentioned motor is not stopped, the above-mentioned step of determining whether the above-mentioned output current of the above-mentioned supply voltage exceeds the above-mentioned predetermined current is executed; and when it is determined that the above-mentioned motor is stopped from being driven, the above-mentioned power supply method is terminated.

100,500: Electronic devices

110: First Battery

120: Second battery

130: Controller

140: Voltage conversion circuit

150,200: Voltage detection circuit

160: Current detection circuit

300,600,700: Power supply method

400: Waveform

510: Motor drive circuit

520: Motor

Q1: First transistor

Q2: Second transistor

Q3: The third transistor

Q4: The fourth transistor

Q5: The fifth transistor

Q6: The sixth transistor

D1: First diode

D2: Second diode

VBAT1: First battery voltage

VBAT2: Second battery voltage

VDD: supply voltage

VDI: Internal supply voltage

VD1: First detection voltage

VD2: Second detection voltage

N1: First node

N2: Second node

G1: First control terminal

G2: Second control terminal

G3: The third control terminal

G4: The fourth control terminal

PD1: First parasitic diode

PD2: Second parasitic diode

PD3: The third parasitic diode

PD4: Fourth parasitic diode

NA1: First anode end

NA2: Second anode end

NA3: Third Anode End

NA4: Fourth Anode

NC1: First cathode end

NC2: Second cathode terminal

NC3: Third cathode terminal

NC4: Fourth cathode terminal

SD1: First read signal

SD2: Second read signal

SG1: First control signal

SG2: Second control signal

SG3: The third control signal

SG4: Fourth control signal

SCD: Current detection signal

IOUT: output current

R1: first resistor

R2: Second resistor

R3: The third resistor

R4: The fourth resistor

ST1: Phase 1

ST2: The second stage

ST3: The third stage

ST4: The fourth stage

ST5: The fifth stage

ST6: The sixth stage

ST7: The seventh stage

VF: Forward conduction voltage

SMT: Motor control signal

S301~S313,S601~S608,S701~S708: Step flow

FIG. 1 is a block diagram of an electronic device according to an embodiment of the present invention; FIG. 2 is a circuit diagram of a voltage detection circuit according to an embodiment of the present invention; FIG. 3 is a flow chart of a power supply method according to an embodiment of the present invention; FIG. 4 is a waveform diagram of a supply voltage according to an embodiment of the present invention; FIG. 5 is a block diagram of an electronic device according to another embodiment of the present invention; FIG. 6 is a flow chart of a power supply method according to another embodiment of the present invention; and FIG. 7 is a flow chart of a power supply method according to another embodiment of the present invention.

The following description is an example of the present disclosure. Its purpose is to illustrate the general principles of the present disclosure and should not be regarded as a limitation of the present disclosure. The scope of the present disclosure shall be based on the scope of the patent application.

FIG. 1 is a block diagram showing an electronic device according to an embodiment of the present invention. As shown in FIG. 1, the electronic device 100 includes a first battery 110, a second battery 120, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a controller 130, a first diode D1, a second diode D2, and a voltage conversion circuit 140.

The first battery 110 has a first battery voltage VBAT1, and the second battery 120 has a second battery voltage VBAT2. According to other embodiments of the present invention, the electronic device 100 may also include a plurality of batteries. Here, two batteries are used for explanation and are not limited to this in any form.

The first transistor Q1 is electrically connected between the supply voltage VDD and the first node N1, and includes a first control terminal G1 and a first parasitic diode PD1, wherein the first parasitic diode PD1 includes a first anode terminal NA1 and a first cathode terminal NC1, the first anode terminal NA1 is electrically connected to the supply voltage VDD, and the first cathode terminal NC1 is electrically connected to the first node N1.

The second transistor Q2 is electrically connected between the first node N1 and the first battery 110, and includes a second control terminal G2 and a second parasitic diode PD2. The second parasitic diode PD2 includes a second anode terminal NA2 and a second cathode terminal NC2, wherein the second anode terminal NA2 is electrically connected to the first node N1, and the second cathode terminal NC2 is electrically connected to the first battery 110.

The third transistor Q3 is electrically connected between the supply voltage VDD and the second node N2, and includes a third control terminal G3 and a third parasitic diode PD3. The third parasitic diode PD3 includes a third anode terminal NA3 and a third cathode terminal NC3, wherein the third anode terminal NA3 is electrically connected to the supply voltage VDD, and the third cathode terminal NC3 is electrically connected to the second node N2.

The fourth transistor Q4 is electrically connected between the second node N2 and the second battery 120, and includes a fourth control terminal G4 and a fourth parasitic diode PD4. The fourth parasitic diode PD4 includes a fourth anode terminal NA4 and a fourth cathode terminal NC4, wherein the fourth anode terminal NA4 is electrically connected to the second battery 120, and the fourth cathode terminal NC4 is electrically connected to the second node N2.

The controller 130 provides the first control signal SG1, the second control signal SG2, the third control signal SG3 and the fourth control signal SG4 to the first control terminal G1, the second control terminal G2, the third control terminal G3 and the fourth control terminal G4 respectively, thereby controlling the first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4 to be turned on or off.

The first diode D1 and the second diode D2 are used to select the higher of the first battery voltage VBAT1 and the second battery voltage VBAT2 and provide it to the voltage conversion circuit 140. The voltage conversion circuit 140 converts the higher of the first battery voltage VBAT1 and the second battery voltage VBAT2 into an internal supply voltage VDI to supply power to the controller 130.

As shown in FIG. 1 , the electronic device 100 further includes a voltage detection circuit 150 and a current detection circuit 160. The voltage detection circuit 150 receives the first battery voltage VBAT1 according to the first read signal SD1 generated by the controller 130 to generate a first detection voltage VD1, and receives the second battery voltage VBAT2 according to the second read signal SD2 generated by the controller 130 to generate a second detection voltage VD2.

The current detection circuit 160 detects the output current IOUT of the supply voltage VDD and generates a current detection signal SCD. The controller 130 determines the size of the output current IOUT based on the current detection signal SCD.

FIG. 2 is a circuit diagram showing a voltage detection circuit according to an embodiment of the present invention. As shown in FIG. 2, the voltage detection circuit 200 includes a first resistor R1, a second resistor R2, a fifth transistor Q5, a third resistor R3, a fourth resistor R4, and a sixth transistor Q6. According to an embodiment of the present invention, the voltage detection circuit 200 of FIG. 2 corresponds to the voltage detection circuit 150 of FIG. 1.

As shown in FIG. 2, the first resistor R1 is electrically connected between the first battery voltage VBAT1 and the first detection voltage VD1. The second resistor R2 is electrically connected to the first detection voltage VD1. The fifth transistor Q5 electrically connects the second resistor R2 to the ground terminal according to the first read signal SD1.

The third resistor R3 is electrically connected between the second battery voltage VBAT2 and the second detection voltage VD2. The fourth resistor R4 is electrically connected to the second detection voltage VD2. The sixth transistor Q6 electrically connects the fourth resistor R4 to the ground terminal according to the second read signal SD2.

According to an embodiment of the present invention, when the first read signal SD1 and the second read signal SD2 output by the controller 130 in FIG. 1 are at a high logic level, the fifth transistor Q5 and the sixth transistor Q6 are turned on, the first battery voltage VBAT1 is divided by the first resistor R1 and the second resistor R2 to generate the first detection voltage VD1, and the second battery voltage VBAT2 is divided by the third resistor R3 and the fourth resistor R4 to generate the second detection voltage VD2. The controller 130 in FIG. 1 determines the voltage levels of the first battery voltage VBAT1 and the second battery voltage VBAT2 according to the first detection voltage VD1 and the second detection voltage VD2.

According to another embodiment of the present invention, when the first read signal SD1 and the second read signal SD2 are at a low logic level, the fifth transistor Q5 and the sixth transistor Q6 are not conducting to reduce power loss.

FIG. 3 is a flow chart showing a power supply method according to an embodiment of the present invention. FIG. 4 is a waveform diagram showing a supply voltage according to an embodiment of the present invention. The following description of the power supply method 300 will be accompanied by the electronic device 100 of FIG. 1, the waveform diagram 300 of FIG. 3, and the waveform diagram 400 of FIG. 4 for detailed description. In addition, the following description is based on the example that the second battery voltage VBAT2 is greater than the first battery voltage VBAT1, but is not limited to this in any form.

As shown in FIG. 3, the controller 130 in FIG. 1 uses the first battery 110 for power supply (step S301). Here, the explanation is based on the first battery 110 for power supply, and it is not limited to this in any form. As shown in FIG. 4, in the first stage ST1, the supply voltage VDD is the first battery voltage VBAT1.

Next, the controller 130 determines whether to switch to the second battery for power supply (step S302). According to one embodiment of the present invention, the controller 130 can determine whether to switch to the second battery 120 for power supply according to whether the second battery voltage VBAT2 is higher than the first battery voltage VBAT1. According to one embodiment of the present invention, as shown in FIG. 1, the controller 130 uses the first read signal SD1 and the second read signal SD2 to enable the voltage detection circuit 150 to receive the first battery voltage VBAT1 and the second battery voltage VBAT2, and generate the first detection voltage VD1 and the second detection voltage VD2.

According to an embodiment of the present invention, the controller 130 determines the magnitude relationship between the first battery voltage VBAT1 and the second battery voltage VBAT2 according to the first detection voltage VD1 and the second detection voltage VD2 generated by the voltage detection circuit 200 in FIG. 2. When the first battery 110 and the second battery 120 are batteries of the same type, the battery with a higher voltage has more power, so the controller 130 can select the battery with a higher voltage to supply power, thereby protecting the battery with a lower voltage from over-discharge.

According to another embodiment of the present invention, the controller 130 can determine whether to switch to the second battery 120 for power supply according to whether the output current IOUT of the supply voltage VDD exceeds the predetermined current and the discharge current specifications of the first battery 110 and the second battery 120. According to one embodiment of the present invention, as shown in FIG. 1, the controller 160 can know the size of the output current IOUT according to the current detection signal SCD, and select a suitable battery for power supply according to the discharge current specifications of the first battery 110 and the second battery 120.

According to other embodiments of the present invention, the controller 130 can decide whether to switch the second battery 120 to supply power according to the battery health status (SOH), battery power and/or battery temperature of the first battery 110 and the second battery 120. For example, the controller 130 can use a communication interface (not shown in FIG. 1), such as a controller area network (CAN or CAN bus), to obtain the battery health status, battery power and temperature of the first battery 110 and the second battery 120, and then select the battery with the best condition to supply power, while allowing the battery with a slightly worse condition to return to a normal state.

When it is determined in step S302 of FIG. 3 that the second battery 120 is not switched to supply power, the controller 130 does not operate, so that the first battery 110 continues to supply power (step S303). When it is determined in step S302 of FIG. 3 that the second battery 120 is switched to supply power, the controller 130 uses the second control signal SG2 to not turn on the second transistor Q2 (step S304), so that the first battery 110 supplies power to the supply voltage VDD through the second parasitic diode PD2. As shown in Figure 4, in the second stage ST2, the supply voltage VDD is the first battery voltage VBAT1 minus the forward conduction voltage VF, where it is assumed that the forward conduction voltages of the first parasitic diode PD1, the second parasitic diode PD2, the third parasitic diode PD3, and the fourth parasitic diode PD4 are all the same and are all the forward conduction voltage VF.

As shown in FIG. 3, the controller 130 then uses the third control signal SG3 to turn on the third transistor Q3 (step S305). As shown in FIG. 4, since the second battery voltage VBAT2 is greater than the first battery voltage VBAT1, in the third stage ST3, the supply voltage VDD is the second battery voltage VBAT2 minus the forward conduction voltage VF. As shown in FIG. 1, since the first transistor Q1 and the third transistor Q3 are turned on, the second parasitic diode PD2 and the fourth parasitic diode PD4 are used to select the larger of the first battery voltage VBAT1 and the second battery voltage VBAT2 to output as the supply voltage VDD. In this embodiment, the second parasitic diode PD2 is also used to prevent the supply voltage VDD from charging the first battery 110.

As shown in FIG. 3, the controller 130 then uses the first control signal SG1 to turn off the first transistor Q1 (step S306). As shown in FIG. 4, when the first transistor Q1 is not conducting, the supply voltage VDD is still the second battery voltage VBAT2 minus the forward conduction voltage VF (third stage ST3).

As shown in FIG. 3, the controller 130 turns on the fourth transistor Q4 using the fourth control signal SG4 (step S307). As shown in FIG. 4, in the fourth stage ST4, since the fourth transistor Q4 is turned on, the supply voltage VDD is equal to the second battery voltage VBAT2. In addition, the supply voltage VDD of the fourth stage ST4 gradually decreases over time. In this embodiment, the supply voltage VDD (that is, the second battery voltage VBAT2) decreases to be lower than the first battery voltage VBAT1 in the fourth stage ST4.

As shown in FIG. 3 , the controller 130 then determines whether to switch to the first battery 110 for power supply (step S308). According to some embodiments of the present invention, the controller 130 may determine whether to switch to the first battery 110 for power supply based on the battery voltage, output current IOUT, battery discharge current specification, battery health status, battery power and/or temperature.

When it is determined in step S308 of FIG. 3 that the first battery 110 is not switched to supply power, the controller 130 does not operate, so that the second battery 120 continues to supply power (step S309), and returns to step S308. When it is determined in step S308 of FIG. 3 that the first battery 110 is switched to supply power, the controller 130 uses the fourth control signal SG4 to not turn on the fourth transistor Q4 (step S310), wherein the fourth parasitic diode PD4 is turned on accordingly. Since the fourth parasitic diode PD4 is turned on, the supply voltage VDD drops to the second battery voltage VBAT2 minus the forward conduction voltage VF in the fifth stage ST5.

As shown in FIG. 3, the controller 130 then uses the first control signal SG1 to turn on the first transistor Q1 (step S311). As shown in FIG. 4, in the sixth stage ST6, since the second parasitic diode PD2 and the fourth parasitic diode PD4 are turned on and the first battery voltage VBAT1 is greater than the second battery voltage VBAT2, the supply voltage VDD is equal to the first battery voltage VBAT1 minus the forward conduction voltage VF.

As shown in FIG. 3, the controller 130 then uses the third control signal SG3 to turn off the third transistor Q3 (step S312). As shown in FIG. 4, when the third transistor Q3 is not conducting, the supply voltage VDD still maintains the first battery voltage VBAT1 minus the forward conduction voltage VF (i.e., the sixth stage ST6).

As shown in FIG. 3, the controller 130 uses the second control signal SG2 to turn on the second transistor Q2 (step S313). As shown in FIG. 4, in the seventh stage ST7, since the second transistor Q2 is turned on, the supply voltage VDD is equal to the first battery voltage VBAT1.

As shown in Figures 1, 3 and 4, the controller 130 switches the first battery 110 and the second battery 120 to supply the supply voltage VDD by controlling the first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4 to be turned on or off. In addition, the second parasitic diode PD2 and the fourth parasitic diode PD4 are used to prevent the supply voltage VDD from charging the first battery 110 or the second battery 120, and when necessary, the higher of the first battery voltage VBAT1 and the second battery voltage VBAT2 is selected to supply the supply voltage VDD.

FIG. 5 is a block diagram of an electronic device according to another embodiment of the present invention. Compared with the electronic device 100 in FIG. 1, the electronic device 500 further includes a motor driving circuit 510 and a motor 520, wherein the controller 130 selects one of the first battery voltage VBAT1 and the second battery voltage VBAT2 as the supply voltage VDD, and uses the supply voltage VDD to power the motor driving circuit 510. The controller 130 further outputs a motor control signal SMT, so that the motor driving circuit 510 drives the motor 520 according to the supply voltage VDD and the motor control signal SMT.

FIG. 6 is a flow chart showing a power supply method according to another embodiment of the present invention. The following description of the flow chart 600 of FIG. 6 will be combined with the electronic device 500 of FIG. 5 for detailed description.

As shown in FIG. 6 , the controller 130 uses the motor control signal SMT to activate the motor driving circuit 510 (step S601). Then, the controller 130 reads the battery information of the first battery 110 and the second battery 120 (step S602). According to an embodiment of the present invention, the controller 130 can obtain the battery health status, battery power and temperature of the first battery 110 and the second battery 120 through a communication interface (not shown in FIG. 5 ), such as a controller local area network.

As shown in FIG. 6 , the controller 130 selects one of the first battery 110 and the second battery 120 for power supply (step S603). According to one embodiment of the present invention, when the first battery 110 is a default battery, step S603 selects the first battery 110 for power supply so that the supply voltage VDD is equal to the first battery voltage VBAT1. The following is an example of the first battery 110 being the default battery for explanation and is not limited thereto in any form. Taking an electric assist bicycle as an example, the first battery 110 is a battery originally installed on the bicycle, and the second battery 120 is an additional backup battery, so the first battery 110 is the default battery.

When the supply voltage VDD is generated, the controller 130 controls the motor driving circuit 510 to start the motor 520 through the motor control signal SMT (step S604). Subsequently, the controller 130 determines whether to switch the battery for power supply according to the battery status of the first battery 110 and the second battery 120 (step S605). When the judgment in step S605 is yes, the controller 130 switches the second battery for power supply by controlling the first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4 (step S606). When the judgment in step S605 is no, the controller 130 continues to supply power with the first battery 110 (step S607).

According to an embodiment of the present invention, the controller 130 can obtain the first battery voltage VBAT1 and the second battery voltage VBAT2 according to the first read signal SD1 and the second read signal SD2 generated by the voltage detection circuit 150, and decide whether to switch to the second battery 120 for power supply according to the magnitude relationship between the first battery voltage VBAT1 and the second battery voltage VBAT2. For example, when the first battery 110 and the second battery 120 are batteries of the same type, a higher battery voltage represents that the battery has a higher battery capacity. When the voltage of the first battery 110 currently supplying power drops to a critical value, the controller 130 determines that the power of the first battery 110 is about to run out, and therefore decides to switch to the second battery 120 for power supply.

According to another embodiment of the present invention, the controller 130 can decide whether to switch to the second battery 120 for power supply based on the battery information obtained in step S602. For example, when the temperature of the first battery 110 is higher than the critical temperature, the controller 130 decides to switch to the second battery 120 for power supply; when the battery health status of the first battery 110 is lower than the critical value, the controller 130 decides to switch to the second battery 120 for power supply; when the first battery 110 is lower than a critical value, the controller 130 decides to switch to the second battery 120.

In other words, in step S605, the controller 130 selects the most suitable battery for power supply according to the battery status, which not only provides the best power quality for the motor 520, but also provides a chance for the battery with a poor status to recover.

According to one embodiment of the present invention, when the controller 130 switches from the first battery 110 to the second battery 120 for power supply in step S606, the controller 130 executes steps S304 to S307 of FIG. 3, thereby smoothly switching the first battery 110 to the second battery 120, which will not be repeated here. According to another embodiment of the present invention, when the controller 130 switches the second battery 120 to the first battery 110 for power supply in step S607, the controller 130 executes steps S310 to S313 of FIG. 3, thereby smoothly switching the second battery 120 to the first battery 110, which will not be repeated here.

After step S606 and step S607, the controller 130 determines whether to continue driving the motor 520 (step S608). When the controller 130 determines to continue driving the motor 520, the controller 130 controls the motor driving circuit 510 to continue driving the motor 520 through the motor control signal SMT, and returns to step S605. When the controller 130 determines to stop driving the motor 520, the controller 130 controls the motor driving circuit 510 to stop driving the motor 520 through the motor control signal SMT, and ends the power supply method 600.

FIG. 7 is a flow chart showing a power supply method according to another embodiment of the present invention. The following description of the flow chart 700 of FIG. 7 will be combined with the electronic device 500 of FIG. 5 for detailed description.

As shown in FIG. 7, steps S701 to S704 correspond to steps S601 to S604 of FIG. 6, respectively, and will not be repeated here. In step S705, the controller 130 obtains the magnitude of the output current IOUT of the supply voltage VDD according to the current detection signal SCD of the current detection circuit 160, and determines whether the output current IOUT exceeds the predetermined current (step S705). When the judgment in step S705 is yes, the controller 130 uses another battery for power supply (step S706). When the judgment in step S705 is no, the controller 130 uses the preset battery for power supply (step S707).

According to an embodiment of the present invention, the controller 130 selects the first battery 110 for power supply in step S703, and in step S702, it is learned that the discharge current specification of the second battery 120 is better than the discharge current specification of the first battery 110. Therefore, after the judgment in step S705 is yes, the controller 130 switches to the second battery 120 for power supply to provide the output current IOUT required by the motor 520. According to an embodiment of the present invention, the first battery 110 is a lithium-ion battery, and the second battery 120 is a lithium-iron battery, so the discharge current of the second battery 120 is greater than the discharge current of the first battery 110.

According to one embodiment of the present invention, when the controller 130 executes step S706 and switches the first battery 110 to the second battery 120 for power supply, the controller 130 executes steps S304 to S307 of FIG. 3. According to another embodiment of the present invention, when the controller 130 executes step S707 and switches the second battery 120 to the first battery 110 for power supply, the controller 130 executes steps S310 to S313 of FIG. 3.

After step S706 and step S707, the controller 130 determines whether to continue driving the motor 520 (step S708). When the controller 130 determines to continue driving the motor 520, the controller 130 controls the motor driving circuit 510 to continue driving the motor 520 through the motor control signal SMT, and returns to step S705. When the controller 130 determines to stop driving the motor 520, the controller 130 controls the motor driving circuit 510 to stop driving the motor 520 through the motor control signal SMT, and ends the power supply method 700.

The present invention proposes an electronic device powered by two or more batteries and a power supply method for switching between different batteries. By using transistors that sequentially turn on and off the batteries, power supply can be smoothly switched from one battery to another. In addition, power supply can be switched to a more suitable battery according to the battery status and/or output current to maintain better power quality.

Although the embodiments and advantages of this disclosure have been disclosed above, it should be understood that anyone with ordinary knowledge in the relevant technical field can make changes, substitutions and modifications without departing from the spirit and scope of this disclosure.

100: Electronic devices

110: First Battery

120: Second battery

130: Controller

140: Voltage conversion circuit

150: Voltage detection circuit

160: Current detection circuit

Q1: First transistor

Q2: Second transistor

Q3: The third transistor

Q4: The fourth transistor

D1: First diode

D2: Second diode

VBAT1: First battery voltage

VBAT2: Second battery voltage

VDD: supply voltage

VDI: Internal supply voltage

VD1: First detection voltage

VD2: Second detection voltage

N1: First node

N2: Second node

G1: First control terminal

G2: Second control terminal

G3: The third control terminal

G4: The fourth control terminal

PD1: First parasitic diode

PD2: Second parasitic diode

PD3: The third parasitic diode

PD4: Fourth parasitic diode

NA1: First anode end

NA2: Second anode end

NA3: Third Anode End

NA4: Fourth Anode

NC1: First cathode end

NC2: Second cathode terminal

NC3: Third cathode terminal

NC4: Fourth cathode terminal

SD1: First read signal

SD2: Second read signal

SG1: First control signal

SG2: Second control signal

SG3: The third control signal

SG4: Fourth control signal

SCD: Current detection signal

IOUT: output current

Claims (6)

A battery management electronic device includes: a first battery having a first battery voltage; a second battery having a second battery voltage; a first transistor electrically connected between a supply voltage and a first node and including a first parasitic diode; a second transistor electrically connected between the first node and the first battery and including a second parasitic diode, wherein the first parasitic diode and the second parasitic diode are used to provide the largest of the first battery voltage and the supply voltage to the first node; a third transistor electrically connected to the supply voltage and a second node and includes a third parasitic diode; a fourth transistor electrically connected between the second node and the second battery and includes a fourth parasitic diode, wherein the third parasitic diode and the fourth parasitic diode are used to provide the maximum of the second battery voltage and the supply voltage to the second node; and a controller, which sequentially turns off the second transistor, turns on the third transistor, turns off the first transistor, and turns on the fourth transistor to switch the supply voltage from the first battery voltage to the second battery voltage. The electronic device of claim 1, wherein the first transistor comprises a first first terminal, a first second terminal and a first control terminal, the first parasitic diode comprises a first anode terminal and a first cathode terminal, wherein the first anode terminal is electrically connected to the first first terminal, and the first cathode terminal is electrically connected to the first second terminal; wherein the second transistor comprises a second first terminal, a second second terminal and a second control terminal, the second parasitic diode comprises a second anode terminal and a second cathode terminal, wherein the second anode terminal is electrically connected to the second first terminal, and the second cathode terminal is electrically connected to the second first terminal. The third second terminal; wherein the third transistor includes a third first terminal, a third second terminal and a third control terminal, and the third parasitic diode includes a third anode terminal and a third cathode terminal, wherein the third anode terminal is electrically connected to the third first terminal, and the third cathode terminal is electrically connected to the third second terminal; wherein the fourth transistor includes a fourth first terminal, a fourth second terminal and a fourth control terminal, and the fourth parasitic diode includes a fourth anode terminal and a fourth cathode terminal, wherein the fourth anode terminal is electrically connected to the fourth first terminal, and the fourth cathode terminal is electrically connected to the fourth second terminal. As in claim 1, the electronic device, wherein when the second transistor is not conducting first, the second parasitic diode is used to prevent the supply voltage from charging the first battery; wherein when the third transistor is then conducting after the second transistor is not conducting, the fourth parasitic diode is used to prevent the supply voltage from charging the second battery. The electronic device of claim 1 further comprises: a voltage detection circuit, comprising: a first resistor electrically connected between the first battery voltage and a first detection voltage; a second resistor electrically connected to the first detection voltage; a fifth transistor electrically connecting the second resistor to a ground terminal according to a first read signal; a third resistor electrically connected between the second battery voltage and a second detection voltage; a fourth resistor electrically connected to the second detection voltage; and a sixth transistor electrically connecting the fourth resistor to a ground terminal according to a second read signal. The resistor is electrically connected to the ground terminal; wherein the controller uses the first read signal and the second read signal to control the voltage detection circuit to generate the first detection voltage and the second detection voltage; wherein the controller determines the first battery voltage according to the first detection voltage, and determines the second battery voltage according to the second detection voltage; wherein when the controller determines that the second battery voltage exceeds the first battery voltage, the controller switches the supply voltage from the first battery voltage to the second battery voltage. An electronic device as claimed in claim 1, wherein the supply voltage is used to power a motor drive circuit, wherein the motor drive circuit drives a motor according to the supply voltage; wherein the controller further reads the battery information of the first battery and the second battery and detects an output current of the supply voltage; wherein when the output current exceeds a predetermined current, the controller uses the first transistor, the second transistor, the third transistor and the fourth transistor to output the second battery voltage as the supply voltage. The electronic device of claim 5 further includes: a current detection circuit for detecting the output current and generating a current detection signal; wherein the controller determines whether the output current exceeds the predetermined current based on the current detection signal.

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