Charging Apparatus And Operating Method For Personal Mobility Device

Abstract

The present invention relates to a battery charging device for a personal mobile device and a method of operation thereof, comprising a buck converter connected to a load and stepping down an input voltage to output an output voltage to the load, and a controller for controlling the output voltage of the buck converter, wherein the controller is configured to control the output voltage by setting the duty cycle of a power semiconductor switch included in the buck converter, thereby enabling the output voltage of various magnitudes to be output, effectively controlling the output voltage even if some modeling parameters are changed, and improving dynamic characteristics.

Description

Technology Field

[0001] The present invention relates to a battery charging device for a personal mobility device and a method of operating the same. Background Technology

[0002] Recently, personal mobility devices (PMDs), such as electric bicycles, electric kickboards, electric scooters, and electric wheels, are rapidly spreading.

[0003] Demand for Personal Mobility Devices (PMDs) is increasing due to their small size, portability, and the ability to use them on pedestrian walkways. Additionally, usage is rising because anyone can easily ride and operate PMDs without obtaining a separate license, allowing for easy access to locations inaccessible by public transportation.

[0004] Personal mobility devices (PMDs) are powered by electricity supplied from batteries, but since the battery capacity that can be installed is limited by the size of the PMD, they need to be charged periodically.

[0005] However, personal mobility devices (PMDs) are not only diverse in type but are also manufactured by numerous companies, presenting a problem where charging methods, such as charging voltage and current, vary from product to product. Additionally, since battery capacities differ for each PMD, charging times vary.

[0006] Personal Mobility Devices (PMDs) face the problem of being difficult to charge at standard charging stations because charging methods vary depending on the product type or manufacturer. Additionally, while PMDs can be charged using individual battery chargers, these chargers charge at a single rated voltage, resulting in low efficiency.

[0007] Accordingly, chargers capable of charging personal mobility device (PMD) batteries at various voltages are being developed; however, a problem arises because chargers with such a wide output voltage range require many power converters, which limits their ability to charge using universal AC voltage.

[0008] Therefore, a method to quickly and reliably charge the batteries of personal mobility devices (PMDs) is required.

[0009] A related technology is Korean Registered Patent No. 10-2282338, "Smart charging system for charging personal mobility devices." The problem to be solved

[0010] The present invention was created out of the aforementioned necessity and aims to provide a battery charging device for a personal mobility device and a method of operation thereof, which effectively charges the battery of the personal mobility device by improving the dynamic performance of the battery charger. means of solving the problem

[0011] To achieve the above-mentioned purpose, a battery charging device for a personal mobile device according to one aspect of the present invention comprises: a buck converter that steps down an input voltage and outputs an output voltage to a load; and a controller that controls the output voltage of the buck converter; wherein the controller controls the output voltage by setting the duty cycle of a power semiconductor switch included in the buck converter.

[0012] The above controller is characterized by setting the duty cycle of the power semiconductor switch based on Model Predictive Control (MPC).

[0013] The buck converter comprises: the power semiconductor switch; an inductor connected to one end of the power semiconductor switch; a diode with one end connected between the power semiconductor switch and the inductor; and a capacitor with one end connected to the diode and the other end connected to the inductor.

[0014] The above controller is characterized by controlling the buck converter in a first mode during the on time when the power semiconductor switch is turned on, and controlling the buck converter in a second mode during the off time when the power semiconductor switch is turned off.

[0015] The above controller is characterized by calculating a cost function of the buck converter based on the difference between the output power of the next control cycle and the reference output power, and calculating the duty cycle of the power semiconductor switch where the cost function becomes zero.

[0016] The above controller is characterized by calculating the duty ratio according to the slope of the output power with respect to the on time and the slope of the output power with respect to the off time.

[0017] The controller is characterized by calculating the duty ratio of the power semiconductor switch based on the slope of the output power with respect to the on time, the slope of the output power with respect to the off time, the current output power, the output power of the next control cycle, and the sampling time which is the sum of the on time and the off time.

[0018] The above controller is characterized by controlling the duty cycle of the power semiconductor switch to adjust the on time and the off time.

[0019] The above controller is characterized by calculating the slope of the output power with respect to the on time and the off time according to the slope of the inductor current with respect to the on time and the off time, and the amount of change of the output power.

[0020] The controller is characterized by calculating the slope of the inductor current with respect to the on-time and the slope of the inductor current with respect to the off-time for the inductor current that increases in the first mode and decreases in the second mode according to the magnitude of the inductor voltage applied to the inductor.

[0021] The above controller is characterized by calculating the reference output power from the reference output voltage, which is a command value, and calculating the output power of the next control cycle from the current output power and the amount of change of the output power.

[0022] The above controller is characterized by calculating the change in output power from the output voltage, the amount of change in the output voltage, the inductor current, and the amount of change in the inductor current.

[0023] It further includes a boost converter that controls the input voltage when a general-purpose current voltage is rectified and input; and a half-bridge LLC resonant converter that includes a transformer that electrically isolates the input voltage and converts the output voltage of the boost converter according to a constant conversion ratio to output to the buck converter.

[0024] A battery charging device for a personal mobile device according to one aspect of the present invention comprises: a boost converter that controls the input voltage when a general-purpose current voltage is rectified and input; a half-bridge LLC resonant converter that includes a transformer that electrically separates the input voltage and converts and outputs the output voltage of the boost converter according to a constant conversion ratio; a buck converter connected to a load and stepping down the voltage output from the half-bridge LLC resonant converter to output an output voltage to the load; and a controller that controls the output voltage by setting the duty ratio of a power semiconductor switch included in the buck converter based on model predictive control through the boost converter, the half-bridge LLC resonant converter, and the buck converter.

[0025] A method of operation for a battery charging device for a personal mobile device according to one aspect of the present invention comprises: a step in which a controller performs predictive modeling for a buck converter to calculate a change in output voltage output from the buck converter to a load and a slope of the inductor current of the buck converter; a step in which the controller calculates a change in output power using the change in output voltage and the slope of the inductor current based on model predictive control; a step in which the controller calculates a cost function regarding the buck converter; and a step in which the controller calculates the duty cycle of the buck converter based on the cost function.

[0026] In the step of calculating the duty cycle of the buck converter, the controller calculates the duty cycle at which the cost function becomes zero and controls the output voltage of the buck converter.

[0027] The step of calculating a cost function for the above-mentioned buck converter includes: a step in which the controller calculates the slope of the output power regarding the on-time and off-time of a power semiconductor switch included in the buck converter based on the amount of change of the output power; a step in which the controller calculates the output power of the next control cycle from the current output power and the slope of the output power; a step in which the controller calculates a reference output power through voltage control; and a step in which the controller calculates the cost function from the output power of the next control cycle and the reference output power.

[0028] In the step of calculating the amount of change in the output power, the controller calculates the amount of change in the output power for the on time and the off time, respectively, using the slope of the inductor current and the amount of change in the output voltage for the on time and the off time of the power semiconductor switch included in the buck converter.

[0029] The step of calculating the amount of change in the output voltage and the slope of the inductor current of the buck converter comprises: a step of calculating the current output power based on the output voltage applied to the load and the inductor current applied to the inductor of the buck converter; a step of calculating the output impedance based on the output voltage, the output voltage of the previous control cycle, and the inductor current; and a step of calculating the amount of change in the output voltage from the output impedance.

[0030] The step of calculating the change in output voltage and the slope of the inductor current of the buck converter comprises: a step of calculating the inductor voltage from the output voltage; and a step of calculating the slope of the inductor current for the on-time and off-time corresponding to the inductor voltage, in correspondence with the on-time and off-time of a power semiconductor switch included in the buck converter. Effects of the invention

[0032] According to one aspect, the battery charging device for a personal mobility device and the method of operation thereof according to the present invention can improve dynamic characteristics and can charge the battery stably and effectively.

[0033] A battery charging device for a personal mobile device and a method of operation thereof according to one aspect of the present invention can minimize output voltage overshoot and shorten response time.

[0034] A battery charging device for a personal mobile device and a method of operation thereof according to one aspect of the present invention can generate output voltages of various sizes by using a general-purpose AC power source as an input voltage.

[0035] A battery charging device for a personal mobility device and a method of operation thereof according to one aspect of the present invention can charge batteries of various specifications regardless of the type and manufacturer of the personal mobility device. Brief explanation of the drawing

[0036] FIG. 1 is a block diagram illustrating the configuration of a battery charging device for a personal mobility device according to one embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a controller of a battery charging device according to one embodiment of the present invention. FIG. 3 is a diagram showing the circuit configuration of a battery charging device according to one embodiment of the present invention. FIG. 4 is a figure referenced to explain the operating circuit of a buck converter of a battery charging device according to one embodiment of the present invention. FIG. 5 is a figure showing the voltage and current waveforms of a buck converter of a battery charging device according to one embodiment of the present invention. FIG. 6 is a diagram showing a circuit configuration for controlling the output voltage of a buck converter of a battery charging device according to one embodiment of the present invention. FIG. 7 is a diagram illustrating the control flow of a battery charging device according to one embodiment of the present invention. FIG. 8 is a flowchart illustrating an operation method for controlling the output voltage of a battery charging device according to an embodiment of the present invention. FIG. 9 is a figure showing the simulation results for charging control of a battery charging device according to one embodiment of the present invention. Figure 10 is a figure showing the output voltage control simulation results following PI control of a general battery charger. FIG. 11 is a figure showing the output voltage control simulation result according to the MPC method of a battery charging device according to one embodiment of the present invention. FIG. 12 is a figure referenced to explain the operating principle of a battery charging device according to one embodiment of the present invention. Figure 13 is a figure showing the experimental results of output voltage control through PI control of a typical battery charger. FIG. 14 is a figure showing the experimental results of output voltage control through the MPC method of a battery charging device according to one embodiment of the present invention. FIGS. 15 and 16 are drawings showing the experimental results of output voltage control according to a change in modeling parameters of a battery charging device according to an embodiment of the present invention. Specific details for implementing the invention

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings.

[0038] In this process, the thickness of lines or the size of components depicted in the drawings may be exaggerated for the sake of clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intent or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0039] FIG. 1 is a block diagram showing the configuration of a battery charging device for a personal mobility device according to one embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a controller of a battery charging device according to one embodiment of the present invention.

[0040] A Personal Mobility Device (PMD) includes a battery and operates based on a charging current supplied from the battery. A Personal Mobility Device (PMD) may include an electric bicycle, an electric kickboard, an electric scooter, an electric wheel, etc.

[0041] The battery voltage of a personal mobility device (PMD) may be set differently depending on the type of product or the manufacturer.

[0042] A battery charging device (1) for a personal mobility device according to the present invention can charge the battery of a personal mobility device (PMD) by generating a wide range of output voltages, i.e., various sizes of output voltages, corresponding to battery voltages that are set differently depending on the type of product or manufacturer.

[0043] The battery charging device (1) includes a plurality of converters and applies a Model Predictive Control (MPC) method to improve dynamic characteristics, thereby enabling output of a wide range of output voltages.

[0044] Referring to FIGS. 1 and 2, a battery charging device (1) according to the present invention may include a power supply unit (20), a first converter (30), a second converter (40), a third converter (50), a load (60), and a controller (100).

[0045] The power supply unit (20) is connected to the power supply (10) supplied to the battery charging device (1) and rectifies the power. The power supply unit (20) may use a diode rectifier containing a plurality of diodes. At this time, the power supply (10) connected to the power supply unit (20) is a single-phase grid source.

[0046] The power supply unit (20) has an input voltage (v g ) and input current (i g ) is rectified and output to the first converter (30).

[0047] The first converter (30) improves the power factor. The first converter (30) may be a PFC Boost Converter.

[0048] The first converter (30) may include an inductor, a diode, a switching element, and a capacitor. The first converter (30) has a voltage (V High ) can be output to the second converter (40).

[0049] The first converter (30) is the voltage (V) rectified by the diode rectifier of the power supply unit (20). rec Using ) voltage(V High ) can be controlled to 400V.

[0050] In addition, the first converter (30) has an input voltage (v) of a single-phase grid source. g ) and input current (i gPower factor compensation (PFC) can be performed by making the phase between the ) identical. At this time, the first converter (30) may include a current and voltage controller which is a control IC.

[0051] The second converter (40) may be a Half-Bridge LLC Resonant Converter. The second converter (40) can convert the frequency of the input voltage to a higher frequency.

[0052] The second converter (40) comprises capacitors (C1, C2) and a switching element (S AP , S AN ), inductor (L r , L m It may include a transformer, diode, and capacitor.

[0053] The transformer can electrically separate the battery and single-phase grid power of the load (60).

[0054] The transformer has capacitors (C1, C2) and a switching element (S) on the primary side. AP , S AN ), inductor (L r , L m ) is connected, and a diode and a capacitor are connected to the secondary side to rectify and smooth the converted voltage.

[0055] Primary side voltage of the transformer (v pri ) consists of two switching elements (S AP , S AN It is generated by operating in a complementary switching state with a duty cycle of 0.5, and the secondary side voltage (v) of the transformer sec ) decreases according to the conversion ratio. At this time, open-loop control using a fixed switching frequency can be performed on the switching element.

[0056] The second converter (40) converts the voltage (V) to the third converter (50). LLC Outputs ). Output voltage (V) of the second converter (40). LLC) is generated by a diode rectifier.

[0057] The third converter (50) steps down the input voltage and delivers it to the load (60).

[0058] The third converter (50) outputs the voltage (V) from the second converter (40). LLC ) receives as input, and outputs the voltage (V) to the load (60). out It can output ). The third converter (50) can be a buck converter.

[0059] The third converter (50) is a power semiconductor switch (S buck ), inductor (L buck ), diode(D buck ), capacitor (C buck It may include ).

[0060] The load (60) connected to the third converter (50) may be a battery or a resistor. The third converter (50) provides a wide range of battery charger output voltages (V out Can control ).

[0061] The load (60) may be a battery of a personal mobility device (PMD). Output voltage (V out ) is the charging voltage of the battery.

[0062] The controller (100) controls the first converter (30) to the third converter (50) to output a voltage (V) to the load (60). out Can control ).

[0063] The controller (100) is the power semiconductor switch (S) of the third converter (50). buck By controlling the duty cycle for ) to the output voltage (V out ) can be controlled. The controller (100) can control the output voltage (V out ) can be controlled in the range of 24V to 36V.

[0064] The controller (100) uses a Model Predictive Control (MPC) method to control the power semiconductor switch (S) of the third converter (50). buck Calculate the duty cycle for ) and control the operation of the third converter (50) to output voltage (V out ) can be adjusted.

[0065] The controller (100) can set the error between the target output voltage and the actual output voltage as a cost function, and set the duty cycle of the third converter (Buck Converter) (50) so that the cost function, i.e., the error, becomes zero.

[0066] The controller (100) detects the connection status of the power source (10) or the connection status of the load (60) and can control the charging of the load (60). In addition, the controller (100) can control the output voltage (V) based on data regarding the charging voltage or charging current of the load (60) received from the load (60). out Can control ).

[0067] FIG. 3 is a diagram showing the circuit configuration of a battery charging device according to one embodiment of the present invention.

[0068] Referring to FIG. 3, the controller (100) may include a sensor (140), a memory (120), a communication unit (130), and a processor (110).

[0069] The sensor (140) may include a plurality of voltage sensors or a plurality of current sensors. Additionally, the sensor (140) may detect the connection status of the power source (10) or the load (60).

[0070] The communication unit (130) can transmit control commands of the processor (110) to the power supply unit (20), the first converter (30), the second converter (40), and the third converter (50). Additionally, the communication unit (130) can transmit data to the outside or receive data from the outside according to the control commands of the processor (110).

[0071] For example, the communication unit (130) can communicate using a wired or wireless communication module. For example, the communication unit (130) can communicate using a communication method such as serial communication, Ethernet, Wi-Fi, Bluetooth, power line communication, etc.

[0072] The memory (120) can store data regarding a plurality of converters, control data for controlling the output voltage, load data, switching data, and output voltage data. The memory (120) can store data for controlling the output of the third converter (50).

[0073] The memory (120) can store data regarding at least one of a converter control algorithm, a switching control algorithm, a duty control algorithm, and an output voltage control algorithm.

[0074] The memory (120) includes non-volatile memory such as RAM (Random Access Memory), ROM (Electrically Erased Programmable ROM), EEPROM (Electrically Erased Programmable ROM), flash memory, HDD, SSD, etc.

[0075] The processor (110) can control the operation of the battery charging device (1) based on data stored in the memory (120). The processor (110) may include at least one microprocessor.

[0076] The processor (110) can control the output of the battery charging device (1) based on data input from the sensor (140).

[0077] The processor (110) can control the operation of the first to third converters (30, 40, 50). The processor (110) can generate and apply control signals to control the operation of switching elements or power semiconductor switches provided in the first to third converters (30, 40, 50).

[0078] The processor (110) outputs an output voltage (V) according to the connected load (60). out Can control ).

[0079] The processor (110) converts the voltage (V) from the transformer of the second converter (40). LLC When ) is input to the third converter (50), the input voltage (V LLC Stepping down the output voltage (V out The third converter (50) can be controlled so that ) outputs to the load (60).

[0080] The processor (110) is a power semiconductor switch (S) included in the third converter (50). buck By setting ) the output voltage (V out Can control ).

[0081] FIG. 4 is a figure referenced to explain the operating circuit of a buck converter of a battery charging device according to one embodiment of the present invention.

[0082] Referring to FIG. 4(a), the third converter (50) can operate as shown in the normal state.

[0083] The third converter (50) is a power semiconductor switch (S buck Depending on the switching state of )(51), it can operate in mode 1 and mode 2.

[0084] The third converter (50) is a power semiconductor switch (S buck If )(51) is in the ON state, the output voltage (V) of the second converter (40) LLC )(55) This diode (D buck It is authorized as ).

[0085] At this time, the inductor (L buck )(52) contains the inductor current (i L, buck ) flows, and the inductor voltage (v L, buck ) is applied. Inductor voltage (v L, buck ) is the voltage (V) of the second converter (40). LLC )(55) and output voltage (V out )(61) is the difference, and the inductor voltage (vL, buck ) is the inductor current (i L, buck It can increase ).

[0086] Referring to FIG. 4(b), the third converter (50) is a power semiconductor switch (S buck If )(51) is in the OFF state, the power semiconductor switch (S buck The output voltage (V) of the second converter (40) by )(51) LLC )(55) is blocked.

[0087] Accordingly, the inductor voltage (v) L, buck ) is the negative output voltage (-V out ) and inductor voltage (v L, buck ) is the inductor current (i L, buck It can reduce ).

[0088] FIG. 5 is a figure showing the voltage and current waveforms of a buck converter of a battery charging device according to one embodiment of the present invention.

[0089] The controller (100) is a power semiconductor switch (S buck In response to the voltage and current generated depending on the on / off of )(51), the inductor (L buck If the current flowing through )(52) increases or decreases, the inductor current (i L, buck The formula can be derived by modeling the slope of ).

[0090] The controller (100) determines the inductor current (i) of the third converter (buck converter) (50) based on a modeled formula. L, buck Can control ).

[0091] FIG. 5(a) is a power semiconductor switch (S) provided in the third converter (50). buck This is a graph showing the on / off operation state of )(51), and FIG. 5 (b) is the diode voltage (v D, buck ) and Fig. 5(c) is the inductor voltage (v L, buck ) and (d) of FIG. 5 is the inductor current (i L, buck ) am.

[0092] As previously explained, the third converter (buck converter) (50) is a power semiconductor switch (S buck )(51) ON time (T ON It operates in the first mode during ), and the power semiconductor switch (S buck Off time (T) when )(51) is turned off (OFF) OFF It can operate in 2nd mode during ).

[0093] On time of 1st mode (T ON ) and the off-time of the second mode (T OFF The time summed up as ) is the sampling time (T samp It can be set to ).

[0094] Each interval can be defined as in the following mathematical formula 1.

[0095]

[0096] At this time, T ON power semiconductor switch (S buck )(51) is the ON time when it is ON, and T OFF is a power semiconductor switch (S buck )(51) is the off time when it is turned off, and T samp is the sampling time obtained by summing the on-time and off-time, and D BAT is a power semiconductor switch (S buck This is the duty ratio of )(51).

[0097] That is, on-time (T ON ) is the sampling time (T samp ) and power semiconductor switch(S buck It can be calculated by multiplying the duty cycle of )(51), and the off-time (T OFF ) is a power semiconductor switch (S) in 1. buck The value obtained by subtracting the duty cycle of )(51) and the sampling time (T samp It can be calculated by multiplying by ).

[0098] Diode voltage (v) D, buck ) becomes High in the first mode, and its magnitude is the output voltage (V) of the second converter (40).LLC It becomes the same value as )(55). Diode voltage (v D, buck ) becomes Low in the second mode, and its size can be 0.

[0099] Inductor voltage (v) L, buck ) becomes High in the first mode, and its magnitude is the output voltage (V) of the second converter (40). LLC Output voltage (V) at )(55) out It becomes the value obtained by subtracting )(61). Inductor voltage (v L, buck ) becomes Low in the second mode, and its magnitude is -V out This can be.

[0100] Power semiconductor switch (S buck Depending on the on / off state of )(51), the inductor voltage (v L, buck As the magnitude of ) changes, the inductor current (i L, buck The size of ) is also changed.

[0101] Inductor current (i L, buck ) increases in the first mode and decreases in the second mode.

[0102] Inductor current (i L, buck The slope of ) is the first slope (Δi) in the first mode L, ON ) and, in the second mode, the second gradient (Δi L, OFF )am.

[0103] The processor performs modeling based on the slope calculated at multiple sampling times to determine the inductor current (i L, buck Mathematical formulas for ) can be derived.

[0104] The processor [determines] the change in inductor current (Δi) as shown in the following mathematical equation 2. L, buck ) can be produced.

[0105]

[0106] At this time, the inductor voltage (v L, buck ) is the inductor current (i) according to the change over time L, buckIn response to the change in ) in the inductor (L buck It can be calculated by multiplying the inductance of )(52). Based on this, the processor (110) can calculate the sampling time (T samp Depending on ), the inductor (L buck Change in inductor current (Δi) applied to )(52) L, buck ) can be produced.

[0107] The processor (110) has the slope (Δi) of the inductor current as shown in the following mathematical equation 3. L, ON , Δi L, OFF ) can be calculated. The processor (110) calculates the amount of change in inductor current (Δi L, buck ) whole time (T ON ) and off-time (T OFF Separated by ), for each, the slope of the inductor current (Δi L, ON , Δi L, OFF ) can be produced.

[0108]

[0109] The processor (110) thus has the slope (Δi) of the inductor current during the on-time and off-time. L, ON , Δi L, OFF By calculating ), the energy conversion efficiency and operational stability according to the control of the third converter (buck converter) (50) can be maximized.

[0110] FIG. 6 is a diagram showing a circuit configuration for controlling the output voltage of a buck converter of a battery charging device according to one embodiment of the present invention.

[0111] The controller (100) can perform predictive modeling for the buck converter, which is the third converter (50). The processor (110) is the output voltage (V) of the third converter (50). out Changes in )(61) can be produced.

[0112] Referring to FIG. 6, the processor (110) applies Kirchhoff's current law to node a (Node(a)) (71) to the inductor current (i L, buck ) can be produced.

[0113] Inductor current (i L, buck ) can be defined as shown in the following mathematical formula 4.

[0114]

[0115] According to Kirchhoff's law, since the input current and output current are the same at node a (71), the inductor current (i L, buck ) is the magnitude of the output current (I out ) and capacitor current (i C It is equal to the sum of ).

[0116] At this time, capacitor current (i C ) is the capacitor (C) of the third converter (buck converter) (50). buck It is the current flowing through )(54), and the output current (I out ) is the current flowing to the load (60).

[0117] The processor (110) can perform modeling based on this to generate the gradient model described above.

[0118] Output voltage (V out Change in the amount of change (ΔV) of )(61) out ) can be operated as shown in the following mathematical formula 5 based on mathematical formula 4.

[0119]

[0120] At this time, the output impedance (Z out ) is the impedance for the load (60), and V out, k and V out, k-1 is the current output voltage and the output voltage of the previous control cycle.

[0121] Output voltage (V out Change in the amount of change (ΔV) of )(61) out ) is the current output voltage (V out, k ) and the output voltage of the previous control cycle (V out, k-1 It can be calculated from the difference of ).

[0122] Accordingly, the output impedance (Z out ) can be calculated as shown in the following mathematical formula 6.

[0123]

[0124] In addition, the processor (110) outputs an output voltage (V out )(61) and inductor current (i L, buck Based on the change in ), as shown in the following mathematical equation 7, the current output power (P out, k ) and the output power of the next control cycle (P out, k+1 ) can be produced.

[0125]

[0126] The controller (100) can perform predictive modeling of the third converter (buck converter) according to the Model Predictive Control method based on such mathematical formulas.

[0127] Through this, the controller (100) outputs the next control cycle's output voltage (V out, k+1 ) and the output power of the next control cycle (P out, k+1 ) can be predicted.

[0128] Additionally, the controller (100) can determine the optimal control input by using the predicted output power in the algorithm of the model predictive control (MPC).

[0129] Through such modeling, the controller (100) can improve control performance by taking into account the dynamic characteristics of the battery charging device (1).

[0130] FIG. 7 is a diagram illustrating the control flow of a battery charging device according to one embodiment of the present invention.

[0131] As illustrated in FIG. 7, the controller (100) can perform model predictive control (MPC).

[0132] In the voltage control step (S10), the processor (110) controls the reference output voltage (command voltage) (V) of the battery. out, ref Output voltage (V) from ) out ) is subtracted (S11), and the result is input to the PI controller to obtain the reference inductor current (i L, buck, ref) and reference output voltage (V out, ref Based on ), reference output power (command power) (P ref ) can be calculated (S13).

[0133] The processor (110), in the prediction modeling step (S20), outputs the voltage (V) in the output voltage (V out ) and inductor current(i L, buck Current output power (P) from ) out, k Calculate ) (S21).

[0134] The processor (110) outputs the voltage (V out ), inductor current(i L, buck ) and the output voltage of the previous control cycle (V out, k-1 Output impedance (Z based on ) out Calculate ) (S22).

[0135] The processor (110) has an output impedance (Z out Change in output voltage (ΔV) from ) out Calculates ) (S23).

[0136] In addition, the processor (110) outputs an output voltage (V out Based on ), the diode voltage (v) of the third converter (buck converter) (50) D, buck Calculate ) (S24), and based on this, calculate the inductor voltage (v L, buck Calculate ) (S25).

[0137] At this time, the processor (110) is a power semiconductor switch (S buck The ON time (T) during which ) is ON ON ) and the off time (T OFF The inductor voltage (v) of ) L, buck Based on the change with respect to ), the inductor current (i L, buck The processor (110) calculates the slope (Δi) of the inductor current based on the change in the inductor current. L, ON , Δi L, OFF ) can be calculated (S26).

[0138] The processor (110) is a change in output voltage (ΔV out) and current output power (P out, k Using ), the change in output power (ΔP out Calculates ) (S27).

[0139] At this time, the output power (P out ) is the output power of the battery charging device (1), and the amount of change in output power (ΔP out ) is the amount of change in output power.

[0140] The processor (110) has a current output power (P out, k ) and change in output power (ΔP out Sum the output power (P) of the next control cycle out, k+1 ) can be produced.

[0141] That is, the change in output power (ΔP out ) is the output power (P) of the next control cycle. out, k+1 Current output power (P) at ) out, k It can be calculated as the value excluding ).

[0142] Accordingly, the amount of change in output power (ΔP out ) can be calculated as shown in the following mathematical formula 8, based on mathematical formula 7.

[0143]

[0144] Meanwhile, the processor (110), in the model prediction control step (S30), [change in output power (ΔP] out ) and the slope of the inductor current (Δi L, ON , Δi L, OFF Based on ), the change in power during on-time and off-time (ΔP ON , ΔP OFF ) can be calculated (S31).

[0145] The processor (110) has a change in output power (ΔP) during the on-time and off-time as shown in the following mathematical formula 9. ON , ΔP OFF ) can be produced.

[0146]

[0147] Also, on time (T ON) and off-time (T OFF The slope (ΔP) with respect to the change in output power ON, slope , ΔP OFF, slope ) can be calculated as shown in the following mathematical formula 10 (S32).

[0148]

[0149] The processor (110) has a change in output power (ΔP) according to the on time and off time. out Considering ), the output power (P) of the next control cycle out, k+1 ) can be operated on (S33).

[0150] The processor (110) outputs the power (P) of the next control cycle based on the following mathematical formula 11. out, k+1 ) can be operated on.

[0151]

[0152] The processor (110) uses a model predictive control method to calculate a cost function (P based on the error in output power) err ) can be produced.

[0153] Cost function (P err ) consists of parameters derived by performing predictive modeling based on system design parameters. The parameters are the sampling time (T) in Equation 1. samp ), inductor of mathematical formula 3 (L buck ) and the capacitor (C) of Equation 5 buck It may include ).

[0154] In the model predictive control method, the cost function (P err ) is defined as shown in the following mathematical formula 12 using the error of the output power.

[0155]

[0156] At this time, P ref is the reference output power (command power).

[0157] The processor (110) has a cost function (P err The output voltage can be controlled so that the value of ) becomes 0.

[0158] Cost function (P err If ) is set to 0, the cost function can be redefined as shown in the following mathematical equation 13.

[0159]

[0160] The processor (110) has a cost function (P err If ) is set to 0, the slope (ΔP) for the change in output power between on-time and off-time ON, slope , ΔP OFF, slope Duty (D according to ) BAT ) can be produced.

[0161] Duty (D BAT ) can be calculated as shown in the following mathematical formula 14.

[0162]

[0163] Duty (D BAT ) is the power semiconductor switch (S) of the third converter (buck converter) (50). buck It is input to )(51), and power semiconductor switch (S buck )(51) is the duty cycle (D BAT Reference output voltage (command voltage) (V) according to ) out, ref Can control ).

[0164] FIG. 8 is a flowchart illustrating an operation method for controlling the output voltage of a battery charging device according to an embodiment of the present invention.

[0165] Referring to FIG. 8, the processor (110) performs PI control (S310) in the voltage control step, and the reference output voltage (V out, ref ) and output voltage (V out Based on ), the reference inductor current (i L, buck, ref ) and reference output power (P ref Calculates ) (S320).

[0166] In the prediction modeling stage, the processor (110) output impedance (Z out ) and change in output voltage (ΔV out Calculates ) (S330).

[0167] The processor (110) is a power semiconductor switch (S buck )(51) ON time (T ON ) and the off time (T OFF The inductor voltage (v) of ) L, buck Based on the change in ), the inductor current (i L, buck Produces ).

[0168] The processor (110) has an inductor current (i L, buck Based on the change of ), the slope of the inductor current (Δi) as shown in Equation 3 L, ON , Δi L, OFF ) can be calculated (S340).

[0169] The processor (110) has a current output voltage (V) as in Equation 7. out, k ) and inductor current(i L, buck Current output power (P) from ) out, k Calculate ) and the output power (P) of the next control cycle. out, k+1 ) can be calculated (S350).

[0170] The processor (110) is the output power (P) of the next control cycle. out, k+1 Based on ), as shown in Equation 8, the change in output power (ΔP out A formula for ) can be calculated (S360)

[0171] The processor (110) is a change in output power (ΔP out ) and the slope of the inductor current (Δi L, ON , Δi L, OFF Based on ), the change in power during the on-time and off-time (ΔP) as shown in Equation 9 ON , ΔP OFF Calculate ) (S370).

[0172] In addition, the processor (110) has a change in power (ΔP) between the on-time and off-time. ON , ΔP OFF From ) as shown in Equation 10, the slope (ΔP) for the change in output power during on-time and off-time ON, slope , ΔPOFF, slope Calculates ) (S380).

[0173] The processor (110) has a change in output power (ΔP) according to the on time and off time. out Considering ), the output power (P) of the next control cycle out, k+1 ) can be recalculated (S390).

[0174] The processor (110) performs predictive modeling as in Equation 12 and comprises a cost function (P) composed of derived parameters. err ) can be calculated (S400).

[0175] In this case, the parameter is the sampling time (T samp ), inductor (L buck The inductance and capacitor (C) of ) buck It is the capacitance of ).

[0176] The processor (110) has a cost function (P err Set ) to 0, and accordingly, the slope (ΔP) for the change in output power during on-time and off-time ON, slope , ΔP OFF, slope Duty (D according to ) BAT ) can be calculated (S410).

[0177] The processor (110) has a duty cycle (D BAT Based on ), the power semiconductor switch (S) of the third converter (50), which is a buck converter buck Controls )(51). Power semiconductor switch (S buck )(51) is the set duty cycle (D BAT A switching operation is performed according to ), and accordingly, an output voltage (V) of a certain magnitude is applied to the load (60). out ) can be authorized.

[0178] The battery charging device (1) of the present invention has a duty cycle (D BAT By calculating ) and controlling the third converter (50), the output voltage (V) for the load (60) out It can control ) and improve dynamic characteristics accordingly.

[0179] FIG. 9 is a figure showing the simulation results for charging control of a battery charging device according to one embodiment of the present invention.

[0180] FIG. 9(a) is a diagram showing the voltage of a single-phase grid power supply, FIG. 9(b) is a diagram showing the current of a single-phase grid power supply, FIG. 9(c) is a diagram showing the output voltage of a first converter (PFC boost converter) (30), FIG. 9(d) is a diagram showing the output voltage of a second converter (HB LLC resonant converter) (40), FIG. 9(e) is a diagram showing the output current of a battery charging device, and FIG. 9(f) is a diagram showing the output voltage of a battery output device.

[0181] The battery charging device (1) of the present invention can control the output voltage and output current based on model prediction control. The simulation results are as shown in (a) to (f) of FIG. 9.

[0182] The simulation parameters are a single-phase grid source of 220 Vms / 60Hz, a transformer turn-ratio of 17:8, an output capacitor of 980μF, an output inductor of 87μH, and a resistor of load of 3Ω. In addition, the switching frequency was set to 80 kHz and the control period to 12.5 μs.

[0183] As shown in FIG. 9 (a) and (b), the voltage (v) of the single-phase grid power supply g ) and current(i g ) appears in the same phase through the first converter (PFC boost converter) (30).

[0184] As shown in FIG. 9(c), the output voltage (V) of the first converter (PFC boost converter) (30) HIGH) is controlled to 400V. As shown in FIG. 9 (d), the output voltage (V) of the second converter (40) LLC ) outputs 100V depending on the transformer's conversion ratio.

[0185] Accordingly, as shown in FIG. 9 (e) and (f), the output current (I) of the third converter (buck converter) (50) out ) is 12A, output voltage (V out ) is controlled at 36V.

[0186] FIG. 10 is a figure showing the output voltage control simulation result according to PI control of a general battery charging device, and FIG. 11 is a figure showing the output voltage control simulation result according to the MPC method of a battery charging device according to an embodiment of the present invention.

[0187] Figure 10 shows the simulation results for controlling the output voltage through general PI control. Figures 10(a) and 11(a) show reference output voltage and output voltage and output current varying between 24V and 36V, and Figures 10(b) and 11(b) are enlarged waveforms of Figures 10(a) and 11(a).

[0188] Referring to FIG. 10(a), the reference output voltage (V out, ref ) changes from 24V to 36V at 0.3 seconds, and from 36V to 24V at 0.5 seconds.

[0189] At this time, when the output voltage is controlled based on PI in a general charger, the bandwidth was set to 3000 Hz and 150 Hz, respectively, considering the switching frequency.

[0190] Output voltage (V out ) is the reference output voltage (V) by the PI controller out, ref Its magnitude varies depending on ). Output voltage (V out ) increases from 24V in 0.3 seconds to reach 36V, and it takes a certain amount of time to reach 36V.

[0191] Accordingly, the proportional gain and integral gain of the current controller are 0.369 and 783, respectively, and the proportional gain and integral gain of the voltage controller are 0.132 and 9.4, respectively.

[0192] According to the enlarged waveform as shown in Figure 10 (b), the output voltage (V out The decision time for ) to reach 36V is approximately 40ms. Output voltage (V out Even when changing from 36V to 24V, it takes about 40ms to 50ms.

[0193] Meanwhile, referring to FIG. 11(b), the reference output voltage (V out, ref ) changes from 24V to 36V at 0.3 seconds, and from 36V to 24V at 0.5 seconds.

[0194] Referring to FIG. 11 (a) and (b), when the output voltage of the battery charging device (1) is controlled based on model predictive control, the output voltage (V out ) is the reference output voltage (V out, ref It increases at 0.3 seconds, as shown in ). At this time, the output voltage (V out The decision time until it reaches 36V is approximately 9ms.

[0195] As such, it can be seen that when controlling the output voltage using Model Predictive Control (MPC) and when controlling the output voltage through PI control, the decision time differs, at 9ms and 40ms, respectively.

[0196] When the battery charging device (1) controls the output voltage based on model prediction control, the decision time for changes in voltage magnitude is significantly reduced, so the time to output voltage to the load (60) can be shortened compared to general PI control, and the dynamic characteristics can be improved by about 4 times.

[0197] FIG. 12 is a figure referenced to explain the operating principle of a battery charging device according to one embodiment of the present invention.

[0198] The battery charging device (1) outputs a constant magnitude of output voltage (V) to the load (60) based on model predictive control (MPC). OUT Can output ).

[0199] Referring to FIG. 12(a), the input voltage (v) of the single-phase grid power supply g ) and input current (i g ) has the same phase.

[0200] Output voltage (V) of the first converter (PFC boost converter) (30) HIGH ) is controlled at approximately 400V.

[0201] Referring to FIG. 12(b), the output voltage (V) of the second converter (40) LLC ) is controlled to approximately 100V. The output voltage (V) of the second converter (40) LLC ) can be changed depending on the transformer's conversion ratio.

[0202] The output current (I) of the third converter (buck converter) (50) out ) is 12A at high signal, output voltage (V out ) is controlled to 36V at a high signal. At this time, one scale on the horizontal axis of the diagram is 10 msec / div, and one scale on the vertical axis is 5 A / div and 20 V / div, respectively.

[0203] FIG. 13 is a figure showing the experimental results of output voltage control through PI control of a general battery charging device. FIG. 14 is a figure showing the experimental results of output voltage control through an MPC method of a battery charging device according to an embodiment of the present invention.

[0204] FIG. 13(b) is an enlarged waveform of FIG. 13(a), and FIG. 14(b) is an enlarged waveform of FIG. 14(a). In this case, one division of the horizontal axis in FIG. 13(a) and FIG. 14(a) is 500 msec / div, and one division of the horizontal axis in FIG. 13(b) and FIG. 14(b) is 50 msec / div. Also, one division of the vertical axis is 5 A / div and 20 V / div, respectively.

[0205] Referring to FIG. 13 (a) and (b), when controlling the output voltage through PI control, the output current (I out ) and output voltage (V out The decision time required to change the size of ) is approximately 41ms.

[0206] The output current (I) of the third converter (buck converter) (50) out ) is 8A at the low signal and 12A at the high signal, and the output voltage (V out ) is 24V at low signal and 36V at high signal.

[0207] Meanwhile, when controlling the output voltage using Model Predictive Control (MPC) as illustrated in FIG. 14 (a) and (b), the output current (I out ) and output voltage (V out The decision time required to change the size of ) is approximately 19ms.

[0208] At this time, the battery charging device (1) using model predictive control (MPC) controls the output voltage in the same scenario as the PI control of FIG. 13.

[0209] That is, when controlling the output voltage under the same conditions, the battery charging device (1) performing model predictive control (PMC) has a reduced decision time due to signal magnitude change compared to the battery charging device performing PI control, and accordingly, the output voltage control speed is faster and the dynamic characteristics can be improved.

[0210] At this time, in the model predictive control (PMC), the battery charging device (1) sets the error between the reference output power and the current output power as a cost function, and calculates the duty cycle at which the cost function becomes zero as described in Equation 14 above.

[0211] The battery charging device (1) of the present invention can effectively control the output voltage by calculating a duty cycle in which the cost function becomes zero and controlling the third converter (buck converter) (50).

[0212] FIGS. 15 and 16 are drawings showing the experimental results of output voltage control according to a change in modeling parameters of a battery charging device according to an embodiment of the present invention.

[0213] FIG. 15(a) is the experimental result of changing the inductance parameter to 0.5 times, FIG. 15(b) is the experimental result of changing the inductance parameter to 1.5 times, FIG. 15(c) is the experimental result of changing the capacitance parameter to 0.5 times, and FIG. 15(d) is the experimental result of changing the capacitance parameter to 1.5 times. In FIG. 15 and FIG. 16, one division on the horizontal axis is 50 msec / div, and one division on the vertical axis is 5 A / div and 20 V / div, respectively.

[0214] The controller (100) controls the output voltage according to the same scenario as the simulation scenario of FIG. 14 described above, but controls the output voltage of the battery charging device (1) by setting the modeling parameters differently as in FIG. 15 (a) to (d).

[0215] An inductor (L) provided in the third converter (buck converter) (50). buck The inductance or capacitor (C) of ) buck Even if the capacitance of ) is changed, as shown in FIG. 15 (a) to (d), the controller (100) outputs the voltage (V) from 24V to 36V based on Model Predictive Control (MPC). out ) can be controlled. In addition, even if the controller (100) changes the parameters, it can reduce the time required for output voltage change compared to PI control, thereby controlling the output voltage (V out Can control ).

[0216] Accordingly, the battery charging device and the method of operation according to one aspect of the present invention can improve dynamic characteristics when charging a battery of a personal mobility device (PMD) by using a model predictive control (MPC) method.

[0217] A battery charging device and a method of operation according to one aspect of the present invention can output an output voltage over a wide range and can effectively control the output voltage even if some modeling parameters are changed.

[0218] A battery charging device and a method of operation according to one aspect of the present invention can be reliably used even in personal mobility devices (PMDs) in which battery specifications differ depending on the model or manufacturer.

[0219] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom.

[0220] Therefore, the true technical scope of protection of the present invention should be determined by the following patent claims. Explanation of the symbols

[0221] 1: Battery charging device 10: Single-phase grid power 20: Power supply 30: First Converter (PFC Boost Converter) 40: Second Converter (Half-Bridge LLC Resonant Converter) 50: 3rd Converter (Buck Converter) 51: Power semiconductor switch(S buck ) 52: Inductor (L buck ) 53: Diode(D buck ) 54: Capacitor (C buck ) 60: Subordinate 61: Output voltage (V out ) 100: Controller 110: Processor 120: Memory 130: Communications Department

Claims

Claim 1 A boost converter that controls the input voltage when a general-purpose AC voltage is rectified and input; a half-bridge LLC resonant converter that includes a transformer for electrically isolating the input voltage and converts and outputs the output voltage of the boost converter according to a constant conversion ratio; a buck converter that steps down the voltage output from the half-bridge LLC resonant converter and outputs the output voltage to a load; and a controller that controls the output voltage of the buck converter; A battery for a personal mobility device, comprising: open-loop control using a fixed switching frequency is performed on the switching element of the half-bridge LLC resonant converter; the controller controls the output voltage by setting the duty cycle of a power semiconductor switch included in the buck converter based on model predictive control through the boost converter, the half-bridge LLC resonant converter, and the buck converter; the controller calculates a cost function of the buck converter based on the difference between the reference output power and the output power of the next control cycle for the output power from the buck converter to the load; calculates the duty cycle of the power semiconductor switch such that the cost function becomes zero; calculates the duty cycle of the power semiconductor switch according to the slope of the output power with respect to the on-time when the power semiconductor switch is turned on and the slope of the output power with respect to the off-time when the power semiconductor switch is turned off; and the controller calculates the slope of the output power with respect to the on-time and the slope of the output power with respect to the off-time according to the slope of the inductor current with respect to the on-time and the off-time, and the amount of change of the output power. Charging device. Claim 2 A battery charging device for a personal mobile device according to claim 1, characterized in that the controller sets the duty cycle of the power semiconductor switch based on Model Predictive Control (MPC). Claim 3 A battery charging device for a personal mobile device according to claim 1, wherein the buck converter comprises: the power semiconductor switch; an inductor connected to one end of the power semiconductor switch; a diode with one end connected between the power semiconductor switch and the inductor; and a capacitor with one end connected to the diode and the other end connected to the inductor. Claim 4 A battery charging device for a personal mobility device according to claim 3, characterized in that the controller controls the buck converter in a first mode during the on time and controls the buck converter in a second mode during the off time. Claim 5 delete Claim 6 delete Claim 7 A battery charging device for a personal mobile device according to claim 1, wherein the controller calculates the duty ratio of the power semiconductor switch based on the slope of the output power with respect to the on time, the slope of the output power with respect to the off time, the current output power, the output power of the next control cycle, and the sampling time which is the sum of the on time and the off time. Claim 8 A battery charging device for a personal mobile device according to claim 1, wherein the controller controls the duty cycle of the power semiconductor switch to adjust the on time and the off time. Claim 9 delete Claim 10 A battery charging device for a personal mobility device according to claim 4, wherein the controller calculates the slope of the inductor current with respect to the on-time and the slope of the inductor current with respect to the off-time for the inductor current that increases in the first mode and decreases in the second mode according to the magnitude of the inductor voltage applied to the inductor. Claim 11 A battery charging device for a personal mobility device according to claim 1, characterized in that the controller calculates the reference output power from the reference output voltage which is a command value, and calculates the output power of the next control cycle from the current output power and the amount of change of the output power. Claim 12 A battery charging device for a personal mobile device, characterized in that, in claim 11, the controller calculates the change in output power from the output voltage, the amount of change in the output voltage, the inductor current, and the amount of change in the inductor current. Claim 13 delete Claim 14 A boost converter that controls the input voltage when a general-purpose AC voltage is rectified and input; a half-bridge LLC resonant converter that includes a transformer that electrically isolates the input voltage and converts and outputs the output voltage of the boost converter according to a constant conversion ratio; a buck converter connected to a load and stepping down the voltage output from the half-bridge LLC resonant converter to output an output voltage to the load; and a controller that controls the output voltage by setting the duty cycle of a power semiconductor switch included in the buck converter based on model predictive control through the boost converter, the half-bridge LLC resonant converter, and the buck converter. A battery charging device for a personal mobile device, comprising: open-loop control using a fixed switching frequency is performed on the switching element of the half-bridge LLC resonant converter; the controller calculates a cost function of the buck converter based on the difference between the reference output power and the output power of the next control cycle for the output power from the buck converter to the load, calculates the duty cycle of the power semiconductor switch such that the cost function becomes zero, calculates the duty cycle of the power semiconductor switch according to the slope of the output power for the on-time when the power semiconductor switch is turned on and the slope of the output power for the off-time when the power semiconductor switch is turned off, and the controller calculates the slope of the output power for the on-time and the slope of the output power for the off-time according to the slope of the inductor current for the on-time and the off-time, and the amount of change of the output power. Claim 15 A controller performs predictive modeling for a buck converter to calculate a change in output voltage output from the buck converter to a load and a slope of the inductor current of the buck converter; a controller calculates a change in output power output from the buck converter to the load based on model predictive control using the change in output voltage and the slope of the inductor current; a controller calculates a cost function for the buck converter; and a controller calculates the duty cycle of the buck converter based on the cost function; wherein the step of calculating a cost function for the buck converter comprises: a controller calculating a slope of the output power with respect to the on-time and off-time of a power semiconductor switch included in the buck converter based on the change in output power; a controller calculating the output power of the next control cycle from the current output power and the slope of the output power; and a controller calculating a reference output power through voltage control. A method of operation of a battery charging device for a personal mobile device, comprising: a step in which the controller calculates the cost function from the output power of the next control cycle and the reference output power; wherein, in the step of calculating the duty ratio of the buck converter, the controller calculates the duty ratio so that the cost function becomes zero and controls the output voltage of the buck converter, and calculates the duty ratio of the power semiconductor switch based on the slope of the output power with respect to the on time and the slope of the output power with respect to the off time, wherein the buck converter receives voltage input through a boost converter and a half-bridge LLC resonant converter, the half-bridge LLC resonant converter converts the input voltage according to a constant conversion ratio, and open-loop control using a fixed switching frequency is performed on the switching element of the half-bridge LLC resonant converter. Claim 16 delete Claim 17 delete Claim 18 A method of operation for a battery charging device for a personal mobile device, wherein, in the step of calculating the amount of change in the output power, the controller calculates the amount of change in the output power for the on time and the off time, respectively, using the slope of the inductor current and the amount of change in the output voltage for the on time and the off time of the power semiconductor switch included in the buck converter. Claim 19 In claim 15, the step of calculating the amount of change in the output voltage and the slope of the inductor current of the buck converter comprises: a step of calculating the current output power based on the output voltage applied to the load and the inductor current applied to the inductor of the buck converter; a step of calculating the output impedance based on the output voltage, the output voltage of the previous control cycle, and the inductor current; and a step of calculating the amount of change in the output voltage from the output impedance; characterized in that it comprises a method of operation of a battery charging device for a personal mobile device. Claim 20 In claim 15, the step of calculating the amount of change of the output voltage and the slope of the inductor current of the buck converter comprises: a step of calculating the inductor voltage from the output voltage; and a step of calculating the slope of the inductor current for the on-time and off-time corresponding to the inductor voltage in correspondence with the on-time and off-time of a power semiconductor switch included in the buck converter; a method of operation of a battery charging device for a personal mobile device.

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