charger

Abstract

To provide a battery charger capable of suppressing the influence of electrical characteristics of a power source.SOLUTION: A battery charger comprises a controller that controls a boost circuit. The controller comprises: an FB module that outputs an FB command based on a squared difference between a target voltage and an actual voltage of the boost circuit; an FF module that outputs an FF command based on the target voltage; and a driver that generates a PWM signal that drives a switching element of the boost circuit from a total value of the FB command and the FF command. The controller (1) performs frequency sweeping of the target voltage while setting the FB command to zero, and identifies a disturbance peak frequency on a board diagram of a disturbance transfer function from the target voltage to current flowing through the reactor, and (2) determines an FB gain included in the FB module so that a difference between a control peak frequency and the disturbance peak frequency on the board diagram of a control transfer function of the controller when it is assumed that an ideal power supply is connected to a low-voltage end is greater than a predetermined threshold frequency width.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The technology disclosed in this specification relates to a charger including a boost circuit and a controller.

Background Art

[0002] For example, Patent Document 1 discloses a charger for charging a battery of an electric vehicle. The electric vehicle includes an electric motor that drives wheels and an inverter that converts DC power of the battery into AC power and supplies it to the electric motor. The charger of Patent Document 1 uses the coil of the electric motor and the switching element of the inverter as a boost circuit. The charger of Patent Document 1 can charge a battery with a voltage higher than the voltage of the power source using the boost circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The controller comprises a feedback module, a feedforward module, and a driver. The feedback module outputs a feedback command based on the difference between the square of the target voltage and the square of the actual voltage. The feedforward module outputs a feedforward command based on the target voltage. The driver generates a duty cycle command for the switching element from the sum of the feedback and feedforward commands, and generates a pulse width modulated signal with that duty cycle. The generated pulse width modulated signal is supplied to the switching element. Hereafter, the pulse width modulated signal will be referred to as a PWM (Pulse Width Modulation) signal.

[0007] Prior to starting charging, the controller performs the following two processes: (1) Set the feedback command to zero and frequency sweep the target voltage to identify the disturbance peak frequency on the Bode plot of the disturbance transfer function from the target voltage to the current flowing through the reactor. (2) Determine the FB gain included in the feedback module such that the difference between the control peak frequency and the disturbance peak frequency on the Bode plot of the controller's control transfer function, assuming an ideal power supply without disturbances is connected to the low-voltage terminal, is greater than a predetermined threshold frequency width. Through these processes, interference between the disturbance transfer function and the control transfer function is avoided, and the influence of the power supply's electrical characteristics on the controller's feedback control during battery charging can be suppressed.

[0008] The charger disclosed herein can suppress the influence of the electrical characteristics of a power supply on the feedback control, even when a power supply with unknown electrical characteristics is connected.

[0009] The controller should determine the FB gain such that the control peak frequency is higher than the disturbance peak frequency. By having the control bandwidth cover the disturbance bandwidth, the difference between the target voltage and the actual voltage, including the disturbance, can be reduced.

[0010] The controller should store several different FB gains and the control peak frequencies when each FB gain is selected. In this case, the controller selects the FB gain from among the several FB gains such that the difference between the control peak frequency and the disturbance peak frequency is greater than the threshold frequency range and closest to the threshold frequency range. The controller's control transfer function, assuming an ideal power supply without disturbances is connected to the low-voltage terminal, can be determined in advance through simulation. An "ideal power supply without disturbances" can be defined in the simulation by setting a power supply model in which the output current of the power supply remains constant regardless of voltage fluctuations at the low-voltage terminal. Several different FB gains and the control peak frequencies when each FB gain is selected can be determined in advance through simulation. After identifying the disturbance peak frequency, the controller can quickly determine the FB gain.

[0011] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0012] [Figure 1] This is a circuit diagram of the charger, power supply, and battery. [Figure 2] This diagram shows the circuit diagram in Figure 1 redrawn as a control block diagram. [Figure 3] This is a Bode diagram of the charger's control system and power supply. [Figure 4] This is a flowchart of the gain determination process performed by the controller. [Modes for carrying out the invention]

[0013] The charger 2 of the embodiment will be described with reference to the drawings. Figure 1 shows the circuit diagram of the charger 2, power supply 100, and battery 200. The output voltage of power supply 100 is lower than the voltage of battery 200. Charger 2 is a device for boosting the output voltage of power supply 100 and charging battery 200 with the power of power supply 100. Power supply 100 contains various passive elements such as resistors 101 and capacitors 102, but their specific structure (electrical characteristics) does not need to be known. In Figure 1, resistors 101, capacitors 102, coils 103, and transformers 104 are depicted inside power supply 100, but these passive elements are merely examples.

[0014] Charger 2 and battery 200 are installed in the electric vehicle. Power supply 100 is installed outside the electric vehicle, such as at a charging station. Power supply 100 and charger 2 are connected via a charging port 21 located on the side of the electric vehicle.

[0015] Charger 2 includes a boost circuit 10 and a controller 30 that controls the boost circuit 10. The controller 30 controls the boost circuit 10 so that the battery 200 can be properly charged, but the control (particularly feedback control) may be affected by the electrical characteristics of the power supply 100. Charger 2 in this embodiment prevents the control performance of charger 2 from degrading due to interference between the electrical characteristics of the power supply 100 and the control characteristics of charger 2. Specifically, the controller 30 of charger 2 determines the feedback control gain (FB gain) so that the peak frequency of the feedback control system does not overlap with the peak frequency of the electrical characteristics (Bode plot) of the power supply 100.

[0016] The main components of the controller 30 as hardware are the central processing unit (CPU 38) and the memory device 39, which stores multiple candidate values ​​for the FB gain. The memory device 39 also stores a program that defines the processing to be executed by the CPU 38.

[0017] The boost circuit 10 will be described. A power supply 100 is connected to the low voltage terminal 11 of the boost circuit 10, and a battery 200 is connected to the high voltage terminal 12. The boost circuit 10 includes a reactor 14 and a switching element 15 for boosting the voltage at the low voltage terminal 11 and outputting it from the high voltage terminal 12. More specifically, the boost circuit 10 includes a reactor 14, a switching element 15, diodes 16a and 16b, and capacitors 17a and 17b. A reactor 14 and a diode 16b are connected in series between the low voltage terminal 11 and the high voltage terminal 12 of the boost circuit 10. One end of the reactor 14 is connected to the low voltage terminal 11, and the other end is connected to the anode of the diode 16b. The cathode of the diode 16b is connected to the high voltage terminal 12. One end (high potential side) of the switching element 15 is connected between the reactor 14 and the diode 16b, and the other end (low potential side) of the switching element 15 is connected to the ground line 13. A diode 16a is connected in reverse parallel to the switching element 15. A capacitor 17a is connected between the low voltage terminal 11 and the ground line 13, and a capacitor 17b is connected between the high voltage terminal 12 and the ground line 13.

[0018] The boost circuit 10 includes a voltage sensor 18a for measuring the voltage at the low voltage terminal 11, a voltage sensor 18b for measuring the voltage at the high voltage terminal 12, and a current sensor 19 for measuring the current flowing through the reactor 14. The measured values of these sensors are sent to the controller 30. The controller 30 controls the switching element 15 based on the measured values of these sensors. Since the structure of the boost circuit 10 shown in FIG. 1 is well known, a detailed description of its operation will be omitted.

[0019] The measured value of the voltage sensor 18a is the actual voltage (actual voltage VLs) at the low voltage terminal 11, and the measured value of the voltage sensor 18b is the actual voltage (actual voltage VHs) at the high voltage terminal 12. The measured value of the current sensor 19 is the current actually flowing through the reactor 14 (actual current Is).

[0020] The controller 30 drives the switching element 15 with a PWM (Pulse Width Moduration) signal having a predetermined duty ratio. The voltage ratio (boost ratio) between the low voltage terminal 11 and the high voltage terminal 12 is determined by the duty ratio defined by the PWM signal. The high voltage terminal 12 is connected to the battery 200, and the voltage of the high voltage terminal 12 coincides with the voltage VB of the battery 200. Let the target voltage of the high voltage terminal 12 be represented by the symbol VHr, and the target voltage of the low voltage terminal 11 be represented by VLr. As described above, the duty ratio included in the PWM signal determines the boost ratio Vratio (= VHr / VLr). Here, the target voltage VHr of the high voltage terminal 12 corresponds to the battery voltage VB. Therefore, the control target value of the boost circuit 10 may be the voltage of the low voltage terminal 11 (target voltage VLr). Specifically, since the target boost ratio Vratio = VB / VLr, the target voltage VLr = VB / Vratio. The controller 30 drives the switching element 15 so that the actual voltage VLs of the low voltage terminal 11 coincides with the target voltage VLr.

[0021] The controller 30 controls the boost circuit 10 (switching element 15) based on the target voltage VLr and the measured values of the sensors 18a, 18b, and 19. Next, the configuration of the controller 30 will be described. A

[0022] The controller 30 includes a squarer 31, 32, a differentiator 33, 34c, multipliers 34a, 34d, a feedforward module 35 (abbreviated as the FF module 35), a PID controller 34b, a PI controller 34e, an adder 36, and a driver 37. All of these blocks may be realized by software, or some of them may be configured by hardware. The multipliers 34a, 34d, the PID controller 34b, the differentiator 34c, and the PI controller 34e are collectively referred to as a feedback module 34 (abbreviated as the FB module 34).

[0023] When the boost circuit 10 is connected to the battery 200, the actual voltage VHs at the high-voltage terminal 12 becomes equal to the battery voltage VB. The target boost ratio Vratio = VB / VS = VHr / VLr required to boost the output voltage VS of the power supply 100 to the battery voltage VB is determined. As mentioned earlier, since the target voltage VHr at the high-voltage terminal 12 is equal to the battery voltage VB, the input to the control system may be the target voltage VLr at the low-voltage terminal 11. The controller 30 drives the switching element 15 so that the actual voltage VLs at the low-voltage terminal 11 matches the target voltage VLr. During charging, the current flowing through the reactor 14 and the actual voltage VLs at the low-voltage terminal 11 fluctuate. Therefore, controlling the system so that the actual voltage VLs matches the target voltage VLr leads to electrically stable charging.

[0024] The target voltage VLr is input to the squaring unit 31. The squaring unit 31 calculates the square of the target voltage VLr. Also, the measured value of the voltage sensor 18a (i.e., the actual voltage VLs at the low voltage terminal 11) is input to the squaring unit 32. The squaring unit 32 calculates the square of the actual voltage VLs. In the differencer 33, the square of the target voltage VLr VLr 2 and the square of the actual voltage VLs VLs 2 The difference is calculated. Below, for the sake of explanation, we will use the square of the target voltage VLr VLr. 2 and the square of the actual voltage VLs VLs 2 The difference between two values ​​is sometimes referred to as the "squared difference."

[0025] The square of the voltage represents electrical energy. Therefore, the squared difference corresponds to the difference between the target electrical energy and the energy actually supplied from the power supply 100. Reducing the squared difference is equivalent to reducing the difference between the actual voltage VLs at the low-voltage terminal 11 and the target voltage VLr. It is desirable for the squared difference to be zero. In other words, the controller 30 controls the boost circuit 10 (switching element 15) so that the actual voltage VLs matches the target voltage VLr.

[0026] The squared difference is input to the FB module 34. In the FB module 34, the squared difference is first multiplied by the voltage FB gain in the multiplier 34a. The voltage FB gain is given by the reciprocal of the capacitance Cf of capacitor 17a (1 / Cf). The value obtained by multiplying the squared difference by the voltage FB gain is input to the PID controller 34b. In the PID controller 34b, the value obtained by multiplying the squared difference by the voltage FB gain is input to the proportional control term, integral control term, and differential control term. The diagrams for the proportional control term, integral control term, and differential control term are omitted. The sum of the outputs of the proportional control term, integral control term, and differential control term becomes the output of the PID controller 34b. The PID controller 34b is well known, so a detailed explanation is omitted. The output of the PID controller 34b becomes the target value (current command Ir) of the current flowing through the reactor 14.

[0027] The actual current (actual current Is) flowing through the reactor 14 is measured by the current sensor 19. The difference between the current command Ir and the actual current Is (current difference) is calculated in the differencer 34c. The current difference is input to the multiplier 34d. In the multiplier 34d, the current difference is multiplied by a predetermined current FB gain. The current FB gain is given by "-L / Tc / VHr". Here, the symbol L is the inductance of the reactor 14, the symbol Tc is the control period, and the symbol VHr is the target voltage of the high voltage terminal 12. As mentioned earlier, the target voltage VHr of the high voltage terminal 12 is equal to the battery voltage VB.

[0028] The value obtained by multiplying the current difference by the current FB gain is input to the PI controller 34e. In the PI controller 34e, the value obtained by multiplying the current difference by the current FB gain is input to the proportional control term and the integral control term. The diagrams for the proportional control term and the integral control term are omitted. The sum of the outputs of the proportional control term and the integral control term becomes the output of the PI controller 34e. The PI controller 34e is well known, so a detailed explanation is omitted. The output of the PI controller 34e (i.e., the output of the FB module 34) becomes a feedback command to bring the squared difference closer to zero. In other words, the output of the FB module 34 becomes a feedback command (FB command) to match the actual voltage VLs at the low voltage terminal 11 to the target voltage VLr.

[0029] Meanwhile, the target voltage VLr is also input to the FF module 35. The FF module 35 multiplies the reciprocal of the target voltage VLr by the actual voltage Vs at the high-voltage terminal 12. That is, the FF module 35 outputs the actual voltage Vs / target voltage VLr. The output of the FF module 35 becomes a feedforward command (FF command) to bring the boost ratio (high-voltage terminal voltage / low-voltage terminal voltage) of the boost circuit 10 closer to the target boost ratio Vratio. In other words, the output of the FF module 35 becomes an FF command to bring the actual voltage VLs at the low-voltage terminal 11 closer to the target voltage VLr.

[0030] The FF command and FB command are added together in the adder 36. The output of the adder 36 is a boost ratio command to make the boost ratio (high voltage terminal voltage / low voltage terminal voltage) of the boost circuit 10 follow the target boost ratio Vratio. The boost ratio command is input to the driver 37. The driver 37 converts the boost ratio command into a duty cycle command. The driver 37 further generates a PWM signal from the duty cycle command. The PWM signal generated by the driver 37 is a pulse signal with period Tc, and the proportion of the HIGH potential in the control period Tc of one pulse corresponds to the duty cycle. The PWM signal output by the driver 37 is supplied to the switching element 15.

[0031] As shown in Figure 1, the controller 30 has a feedback loop based on the difference (squared difference) between the target voltage VLr and the actual voltage VLs. When the controller 30 drives the switching element 15, the actual voltage VLs at the low voltage terminal 11 follows the target voltage VLr. More specifically, the FF command causes the actual voltage VLs to quickly approach the target voltage VLr. The FB command suppresses fluctuations in the difference between the actual voltage VLs and the target voltage VLr.

[0032] As mentioned earlier, the power supply 100 contains several passive components, but its electrical characteristics are unknown. The electrical characteristics of the power supply 100 may affect the feedback control of the controller 30. This will be explained using Figure 2.

[0033] Figure 2 is a redrawn version of the circuit diagram in Figure 1, showing it as a control block. Note that in Figure 2, the elements within the FB module 34 (multipliers 34a, 34d, PID controller 34b, differencer 34c, and PI controller 34e) are omitted from the illustration.

[0034] The controller 30 generates a control value (PWM signal) based on the target voltage VLr and actual voltage VLs at the low-voltage terminal 11, and the current (actual current Is) flowing through the reactor 14, and supplies the generated PWM signal to the boost circuit 10 (switching element 15).

[0035] The controller 30 comprises an FB module 34, an FF module 35, and a driver 37. The FB module 34 outputs an FB command based on the squared difference between the target voltage VLr and the actual voltage VLs. The actual current Is is also used to generate the FB command (see Figure 1). The FF module 35 outputs an FF command based on the target voltage VLr. The driver 37 generates a duty cycle command for the switching element from the sum of the FB command and the FF command, and generates a PWM signal including that duty cycle command. The generated PWM signal is supplied to the boost circuit 10 (switching element 15).

[0036] While the switching element 15 is being driven, the actual voltage VLs fluctuates due to various factors. This fluctuation in the actual voltage VLs manifests as a fluctuation in the current flowing through the reactor 14 via the electrical characteristics of the power supply 100. Hereinafter, the current flowing through the reactor 14 will simply be referred to as the reactor current. The fluctuation in the reactor current caused by the electrical characteristics of the power supply 100 becomes a disturbance to the control system. Therefore, the fluctuation in the reactor current caused by the electrical characteristics of the power supply 100 is called the disturbance current Id. Furthermore, the transfer function from the fluctuation in the actual voltage VLs to its manifestation as a fluctuation in the actual current Is via the electrical characteristics of the power supply 100 is called the disturbance transfer function.

[0037] The majority of the reactor current flows due to the operation of the switching element 15. The reactor current caused by the operation of the switching element 15 is called the main current Ia. The actual current Is measured by the current sensor 19 is the sum of the main current Ia and the disturbance current Id. Figure 2 shows that the adder 40, which adds the main current Ia and the disturbance current Id, is sent to the controller 30 as the actual current Is.

[0038] As is clear from Figures 1 and 2, the current flowing through the reactor 14 due to the electrical characteristics of the power supply 100 can be considered a disturbance (disturbance current Id) for the control system. The disturbance current Id affects the FB command. If the peak frequency of the transfer function of the FB module 34 is close to the peak frequency of the disturbance current Id, the effect becomes larger. Specifically, the FB command is greatly disturbed by fluctuations in the disturbance current Id.

[0039] Therefore, after the power supply 100 is connected, the controller 30 performs the following process before charging the battery 200, adjusting the parameters of the control system (FB gain) so that the influence of the disturbance current Id (i.e., the electrical characteristics of the power supply 100) is reduced.

[0040] (Process 1) First, the controller 30 sets the FB command to zero and sweeps the target voltage VLr by frequency to obtain the Bode plot of the disturbance transfer function from the target voltage VLr to the reactor current (actual current Is). The controller 30 then identifies the peak frequency (disturbance peak frequency) on the Bode plot. "Sweeping the target voltage VLr by frequency" means oscillating the target voltage VLr while gradually increasing the frequency from zero. The controller 30 measures the actual current Is at predetermined frequency intervals while gradually increasing the oscillation frequency of the target voltage VLr. The "actual current Is / target voltage VLr" at each frequency corresponds to the gain on the Bode plot. The upper part of Figure 3 shows graph G1, an example of a disturbance transfer function. The symbol fdp represents the disturbance peak frequency. The disturbance transfer function is the transfer function from the fluctuation of the actual voltage VLs to the disturbance current Id, but since the FB command is set to zero, the fluctuation of the actual voltage VLs is equal to the fluctuation of the target voltage VLr. Therefore, by setting the FB command to zero and sweeping the target voltage VLr by frequency, the Bode plot of the disturbance transfer function can be obtained.

[0041] If the peak frequency on the Bode plot of the control system is close to the disturbance peak frequency fdp, the control performance deteriorates. The controller 30 performs the following (process 2).

[0042] (Process 2) The controller determines the FB gain included in the FB module 34 such that the difference between the control peak frequency fcp and the disturbance peak frequency fdp on the Bode plot of the control transfer function, assuming an ideal power supply without disturbances is connected to the low-voltage terminal 11, is greater than a predetermined threshold frequency width Wf. Graph G2 in the middle of Figure 3 is the Bode plot when the control peak frequency fcp is greater than the disturbance peak frequency fdp by more than the threshold frequency width Wf (fcp-fdp>Wf). Graph G3 in the lower part of Figure 3 is the Bode plot when the disturbance peak frequency fdp is greater than the control peak frequency fcp by more than the threshold frequency width Wf (fdp-fcp>Wf). Both graphs G2 and G3 represent the case where |fdp-fcp|>Wf. The controller 30 determines the FB gain of the FB module 34 such that the Bode plot of the control system is graph G2 or G3. The threshold frequency width Wf is set to, for example, several tens of kilohertz.

[0043] The controller 30's memory device 39 stores multiple different FB gains and the control peak frequency fcp when each FB gain is selected. The controller's control transfer function, assuming an ideal power supply without disturbances is connected to the low-voltage terminal, is determined in advance through simulation. An ideal power supply without disturbances can be created in the simulation by setting a power supply model where the output current of the power supply remains constant even if the voltage at the low-voltage terminal fluctuates. Multiple different FB gains and the control peak frequencies when each FB gain is selected are pre-stored in the controller 30's memory device 39.

[0044] The controller 30 selects an FB gain from among several FB gains such that the difference between the control peak frequency fcp and the disturbance peak frequency fdp is greater than the threshold frequency width Wf and is closest to the threshold frequency width Wf. If there are candidate control peak frequencies fcp on both the low-frequency and high-frequency sides of the disturbance peak frequency fdp, the controller 30 selects an FB gain corresponding to the control peak frequency fcp that is greater than the disturbance peak frequency fdp.

[0045] By increasing the difference between the control peak frequency fcp and the disturbance peak frequency, the influence of the electrical characteristics of power supply 100 on the feedback control can be suppressed.

[0046] Note that the FB gain includes the voltage FB gain set in multiplier 34a and the current FB gain set in multiplier 34d in Figure 1. In addition to these gains, the FB gain may also include the gains (proportional gain, integral gain, and derivative gain) included in the PID controller 34b and PI controller 34e.

[0047] The voltage FB gain includes the capacitance of capacitor 17a, and therefore cannot be adjusted by the controller 30's software (control program for controller 30). On the other hand, the current FB gain includes the control period Tc. The control period Tc of controller 30 is equal to the period of the carrier wave used to generate the PWM signal. More precisely, the control period Tc is equal to an integer multiple of the carrier wave period. Therefore, the FB gain can be adjusted by adjusting the carrier wave period. This adjustment is possible by software. In addition, the proportional gain, integral gain, and differential gain included in the PID controller 34b and PI controller 34e can also be changed by software. As mentioned earlier, the FB gains corresponding to each of the multiple different control peak frequencies fcp are predetermined by simulation and stored in the memory device 39.

[0048] Figure 4 shows a flowchart of the FB gain determination process. In step S2, the following processes are performed: The controller 30 sets the FB command to zero and sweeps the target voltage VLr by frequency. The actual voltage VLs also changes frequency according to the frequency sweep of the target voltage VLr. While the frequency sweep is being performed, the reactor current (actual current Is) is measured at predetermined frequency intervals. The value of actual current Is / target voltage VLr is plotted on a frequency graph. That is, a Bode plot of the disturbance transfer function is obtained. The controller 30 identifies the peak (disturbance peak frequency) in the disturbance Bode plot.

[0049] Once the frequency sweep is complete, the controller 30 executes step S3. In step S3, the controller 30 selects an FB gain from among the multiple FB gains stored in the memory device 39 such that |fdp-fcp|>Wf.

[0050] If multiple FB gains are selected in step S3 (step S4: YES), step S5 is executed. The controller 30 selects one FB gain where fcp-fdp > Wf and the difference between fcp and fdp is closest to Wf. The controller 30 sets the selected FB gain as the FB gain of the FB module 34 (step S6). If only one FB gain is selected in step S4, the controller 30 sets the selected FB gain as the gain of the FB module 34 (step S4: NO, S6).

[0051] Through the above process, an FB gain is set in the control system that can suppress the influence of the electrical characteristics of the power supply 100. After the process shown in Figure 4 is completed, the controller 30 drives the switching element 15 using the set FB gain and charges the battery 200.

[0052] The controller 30 sets the FB gain after measuring the actual transfer function (disturbance transfer function) of the power supply 100. Therefore, the charger 2 can achieve feedback control with minimal influence (influence of disturbances) from the electrical characteristics of the power supply, even when a power supply with unknown electrical characteristics is connected.

[0053] Points to note regarding the technology described in the examples are stated below. The charger may have multiple boost circuits connected in parallel. A technique is known in which the switching elements of an inverter and the coils of an electric motor are used as boost converters. The coils of the electric motor function as reactors. In this case, each of the three phase coils and the switching element constitutes a boost circuit. The inverter and electric motor constitute three boost circuits connected in parallel. The charger disclosed herein may have multiple boost circuits utilizing the switching elements of an inverter and the coils of an electric motor.

[0054] PID controllers 34b and PI controllers 34e are well known. The control system design techniques for PID controllers 34b and PI controllers 34e are also well known. The charger 2 disclosed herein is characterized by having a controller 30 that has a plurality of FB gains prepared in advance and setting an appropriate FB gain (an FB gain suitable for suppressing disturbances) according to the electrical characteristics of the connected power supply.

[0055] A PI controller or PD controller may be used instead of the PID controller 34b that defines the control rules for the FB module 34. Similarly, a PID controller or PD controller may be used instead of the PI controller 34e.

[0056] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of symbols]

[0057] 2: Charger 10: Boost circuit 11: Low voltage terminal 12: High voltage terminal 13: Ground wire 14: Reactor 15: Switching element 16a, 16b: Diode 17a, 17b: Capacitor 18a, 18b: Voltage sensor 19: Current sensor 21: Charging port 30: Controller 31, 32: Square unit 33: Differential unit 34: Feedback module (FB module) 34a, 34d: Multiplier 34b: PID controller 34c: Differential unit 34e: PI controller 35: Feedforward module (FF module) 36, 40: Adder 37: Driver 38: CPU 39: Memory device 100: Power supply 101: Resistor 102: Capacitor 103: Coil 104: Transformer 200: Battery

Claims

1. A boost circuit comprising a reactor and a switching element for boosting the voltage of the low-voltage terminal and outputting it from the high-voltage terminal, with the low-voltage terminal connected to a power supply and the high-voltage terminal connected to a battery, A controller that drives the switching element so that the actual voltage at the low-voltage terminal matches the target voltage, It is equipped with, The aforementioned controller, A feedback module that outputs a feedback command based on the difference between the square of the target voltage and the square of the actual voltage, A feedforward module that outputs a feedforward command based on the target voltage, A driver that generates a pulse width modulated signal to drive the switching element from the sum of the feedback command and the feedforward command, It is equipped with, The aforementioned controller, While setting the feedback command to zero, the target voltage is frequency swept to identify the disturbance peak frequency on the Bode plot of the disturbance transfer function from the target voltage to the current flowing through the reactor. The FB gain included in the feedback module is determined such that the difference between the control peak frequency and the disturbance peak frequency on the Bode plot of the controller's control transfer function is greater than a predetermined threshold frequency width, assuming that an ideal power supply free from disturbances is connected to the low-voltage terminal. charger.

2. The charger according to claim 1, wherein the controller determines the FB gain such that the control peak frequency is higher than the disturbance peak frequency.

3. The controller stores a plurality of different FB gains and the control peak frequency when each FB gain is set. The charger according to claim 1 or 2, wherein from among a plurality of FB gains, the FB gain is selected such that the difference between the control peak frequency and the disturbance peak frequency is greater than the threshold frequency width and is closest to the threshold frequency width.

Images