Charger

Abstract

A charger includes a controller that controls a booster circuit. The controller includes an FB module, an FF module, and a driver. The controller (1) frequency-scans a target voltage while setting an FB command to zero, and specifies an interference peak frequency on a Bode diagram of an interference transfer function from the target voltage to a current flowing through the reactor, (2) determines an FB gain included in the FB module such that the difference between the control peak frequency and the interference peak frequency is greater than a predetermined threshold frequency width, and (3) determines the FB gain included in the FB module such that the difference between the control peak frequency and the interference peak frequency is greater than the predetermined threshold frequency width. The control peak frequency is a peak frequency on a Bode diagram of a control transfer function of the controller assuming that the ideal power supply is connected to the low voltage terminal.

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, Japanese Patent Application Laid-Open No. 2021-175363 discloses a charger for charging a battery of a battery electric vehicle. The battery electric vehicle has an electric motor for driving wheels and a converter for converting the DC power of the battery into AC power and supplying it to the electric motor. The charger of Japanese Patent Application Laid-Open No. 2021-175363 uses the coil of the electric motor and the switching element of the converter as a boost circuit. The charger of Japanese Patent Application Laid-Open No. 2021-175363 can charge a battery with a voltage higher than the voltage of the power supply using a boost circuit. Summary of the invention

[0003] The controller of the charger is provided with a feedback module in such a way that the difference between the target voltage of the boost circuit and the actual voltage (actual voltage) becomes zero. If the electrical characteristics of the power supply connected to the low voltage end of the boost circuit are close to the control characteristics of the feedback module, there is a possibility that the two interfere with each other and the voltage change (or current change) of the boost circuit in the feedback control becomes larger. This specification provides a charger that can adjust its own control system in such a way that the interference with the electrical characteristics of the power supply is reduced.

[0004] The charger disclosed in this specification includes a boost circuit and a controller. The low voltage end of the boost circuit is connected to a power supply, and the high voltage end is connected to a battery. The boost circuit includes a reactor and a switching element, and the reactor is used to boost the voltage at the low voltage end and output it from the high voltage end. The controller drives the switching element in such a way that the actual voltage at the low voltage end is consistent with the target voltage.

[0005] The controller includes a feedback module, a feedforward module, and a driver. The feedback module outputs a feedback instruction based on the difference between the square of the target voltage and the square of the actual voltage. The feedforward module outputs a feedforward instruction based on the target voltage. The driver generates a duty cycle instruction to the switching element according to the sum of the feedback instruction and the feedforward instruction, and generates a pulse width modulation signal having the duty cycle. The generated pulse width modulation signal is supplied to the switching element. It should be noted that, hereinafter, the pulse width modulation signal is referred to as a PWM signal.

[0006] The controller performs the following two processes before starting charging. (1) The feedback command is set to zero, and the target voltage is frequency scanned at the same time to determine the interference peak frequency on the Bode diagram of the interference transfer function from the target voltage to the current flowing through the reactor. (2) The FB gain included in the feedback module is determined in a manner such that the difference between the control peak frequency and the interference peak frequency is greater than the specified threshold frequency width. The control peak frequency is the peak frequency on the Bode diagram of the control transfer function of the controller when an ideal power supply that is assumed to generate no interference is connected to the low voltage end. Through the above processing, the interference between the interference transfer function and the control transfer function can be avoided, and the influence of the electrical characteristics of the power supply on the feedback control of the controller when charging the battery can be suppressed.

[0007] The charger disclosed in this specification can suppress the influence of the electrical characteristics of the power source on feedback control even when a power source with unknown electrical characteristics is connected.

[0008] The controller preferably determines the FB gain so that the control peak frequency is higher than the interference peak frequency. By covering the interference frequency band with the control frequency band, the difference between the target voltage and the actual voltage can be reduced including the interference.

[0009] It is preferred that the controller stores a plurality of different FB gains and the control peak frequencies when each FB gain is selected. In this case, the controller selects the FB gain whose difference between the control peak frequency and the interference peak frequency is larger than the threshold frequency width and is closest to the threshold frequency width from the plurality of FB gains. The control transfer function of the controller, assuming that an ideal power supply that does not generate interference is connected to the low voltage end, can be obtained in advance through simulation. The "ideal power supply that does not generate interference" can be set in the simulation as a power supply model in which the output current of the power supply is constant regardless of the voltage fluctuation at the low voltage end. A plurality of different FB gains and the control peak frequencies when each FB gain is selected can be obtained in advance through simulation. The controller can quickly determine the FB gain after determining the interference peak frequency.

[0010] The details and further improvements of the technology disclosed in this specification will be described in the following “Detailed Description of the Invention”. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0012] Figure 1 It is the circuit diagram of the charger, power supply and battery;

[0013] Figure 2 Yes Figure 1 The circuit diagram is redrawn in the form of a control block diagram;

[0014] Figure 3 It is the Bode diagram of the charger’s control system and power supply;

[0015] Figure 4 This is a flow chart of the gain determination process performed by the controller. DETAILED DESCRIPTION

[0016] The charger 2 of the embodiment will be described with reference to the accompanying drawings. Figure 1 The circuit diagram of the charger 2, power supply 100 and battery 200 is shown in FIG. The output voltage of the power supply 100 is lower than the voltage of the battery 200. The charger 2 is a device for boosting the output voltage of the power supply 100 and charging the battery 200 using the power of the power supply 100. The power supply 100 includes various passive components such as a resistor 101 and a capacitor 102, but the specific structure (electrical characteristics) thereof may not be detailed. Figure 1 In the figure, a resistor 101, a capacitor 102, a coil 103, and a transformer 104 are drawn in the power supply 100, but these passive components are just examples.

[0017] The charger 2 and the battery 200 are mounted on the battery-electric vehicle. The power source 100 is installed at a charging station or the like outside the battery-electric vehicle. The power source 100 and the charger 2 are connected via a charging port 21 provided on the side of the battery-electric vehicle.

[0018] The charger 2 includes a boost circuit 10 and a controller 30 for controlling the boost circuit 10. The controller 30 controls the boost circuit 10 so that the storage battery 200 can be appropriately charged, but the control (especially the feedback control) may be affected by the electrical characteristics of the power supply 100. The charger 2 of the embodiment prevents the electrical characteristics of the power supply 100 from interfering with the control characteristics of the charger 2 and thus reducing the control performance of the charger 2. Specifically, the controller 30 of the charger 2 determines the gain (FB gain) of the feedback control so that the peak frequency of the feedback control system does not overlap with the peak frequency of the electrical characteristics (Bode diagram) of the power supply 100.

[0019] The main components of the controller 30 as hardware are a central processing unit (CPU 38) and a storage device 39. A plurality of candidate values ​​of the FB gain are stored in the storage device 39. The storage device 39 also stores a program defining the processing executed by the CPU 38.

[0020] The boost circuit 10 is described. The power supply 100 is connected to the low voltage end 11 of the boost circuit 10, and the storage battery 200 is connected to the high voltage end 12. The boost circuit 10 includes a reactor 14 and a switching element 15, and the reactor 14 is used to boost the voltage of the low voltage end 11 and output it from the high voltage end 12. In more detail, the boost circuit 10 includes a reactor 14, a switching element 15, diodes 16a, 16b, and capacitors 17a, 17b. The reactor 14 and the diode 16b are connected in series between the low voltage end 11 and the high voltage end 12 of the boost circuit 10. One end of the reactor 14 is connected to the low voltage end 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 end 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 anti-parallel to the switch 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.

[0021] The boost circuit 10 includes a voltage sensor 18a for measuring the voltage of the low voltage end 11, a voltage sensor 18b for measuring the voltage of the high voltage end 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. Figure 1 The structure of the booster circuit 10 shown is well known, and therefore a detailed description of the operation will be omitted.

[0022] The voltage sensor 18a measures the actual voltage (actual voltage VLs) at the low voltage end 11, and the voltage sensor 18b measures the actual voltage (actual voltage VHs) at the high voltage end 12. The current sensor 19 measures the actual current flowing through the reactor 14 (actual current Is).

[0023] The controller 30 drives the switching element 15 using a pulse width modulation (PWM) signal with a specified duty cycle. The voltage ratio (boost ratio) between the low voltage terminal 11 and the high voltage terminal 12 is determined by the duty cycle specified by the PWM signal. The high voltage terminal 12 is connected to the battery 200, and the voltage of the high voltage terminal 12 is consistent with the voltage VB of the battery 200. The target voltage of the high voltage terminal 12 is represented by the symbol VHr, and the target voltage of the low voltage terminal 11 is represented by VLr. As mentioned above, the duty cycle 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 can be set to 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.

[0024] 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.

[0025] The controller 30 includes square operators 31, 32, differentiators 33, 34c, multipliers 34a, 34d, a feedforward module 35 (abbreviated as FF module 35), a PID controller 34b, a PI controller 34e, an adder 36, and a driver 37. All of these blocks may be implemented by software, or part 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 FB module 34).

[0026] If the boost circuit 10 is connected to the battery 200, the actual voltage VHs of 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 above, the target voltage VHr of the high voltage terminal 12 is equal to the battery voltage VB, so the input to the control system can be set to the target voltage VLr of the low voltage terminal 11. The controller 30 drives the switching element 15 in a manner that makes the actual voltage VLs of the low voltage terminal 11 consistent with the target voltage VLr. During the charging process, the current flowing through the reactor 14 and the actual voltage VLs of the low voltage terminal 11 fluctuate. Therefore, controlling in a manner that makes the actual voltage VLs consistent with the target voltage VLr will achieve electrically stable charging.

[0027] The target voltage VLr is input to the square operator 31. The square operator 31 calculates the square of the target voltage VLr. In addition, the measured value of the voltage sensor 18a (that is, the actual voltage VLs at the low voltage terminal 11) is input to the square operator 32. The square operator 32 calculates the square of the actual voltage VLs. In the differentiator 33, the square VLr of the target voltage VLr is calculated. 2 The square of the actual voltage VLs 2 For the sake of convenience, the square of the target voltage VLr is sometimes referred to as VLr. 2 The square of the actual voltage VLs 2 The difference is called the "square difference".

[0028] The square of the voltage means electric energy. Therefore, the square difference is equivalent to the difference between the electric energy set as the target and the electric energy actually supplied from the power supply 100. Reducing the square difference is equivalent to reducing the difference between the actual voltage VLs at the low voltage end 11 and the target voltage VLr. The square difference is preferably zero. In other words, the controller 30 controls the boost circuit 10 (switching element 15) in such a way that the actual voltage VLs is consistent with the target voltage VLr.

[0029] The square difference is input to the FB module 34. In the FB module 34, first, in the multiplier 34a, the square difference is multiplied by the voltage FB gain. The voltage FB gain is given by the inverse (1 / Cf) of the capacitance Cf of the capacitor 17a. The value obtained by multiplying the square difference by the voltage FB gain is input to the PID controller 34b. In the PID controller 34b, the value obtained by multiplying the square difference by the voltage FB gain is input to the proportional control term, the integral control term, and the differential control term. The illustration of the proportional control term, the integral control term, and the differential control term is omitted. The total value of the output of the proportional control term, the integral control term, and the differential control term becomes the output of the PID controller 34b. The PID controller 34b is well known, so the detailed description is omitted. The output of the PID controller 34b becomes the target value (current command Ir) of the current flowing to the reactor 14.

[0030] The actual current (actual current Is) flowing to the reactor 14 is measured by the current sensor 19. In the differentiator 34c, the difference (current difference) between the current command Ir and the actual current Is is calculated. The current difference is input to the multiplier 34d. In the multiplier 34d, the current difference is multiplied by a specified 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 above, the target voltage VHr of the high voltage terminal 12 is equal to the battery voltage VB.

[0031] 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 illustration of the proportional control term and the integral control term is omitted. The total value of the output of the proportional control term and the integral control term becomes the output of the PI controller 34e. The PI controller 34e is also well known, so the detailed description is omitted. The output of the PI controller 34e (i.e., the output of the FB module 34) becomes a feedback instruction for making the square difference approach zero. In other words, the output of the FB module 34 becomes a feedback instruction (FB instruction) for making the actual voltage VLs of the low voltage terminal 11 consistent with the target voltage VLr.

[0032] On the other hand, the target voltage VLr is also input to the FF module 35. The FF module 35 multiplies the inverse of the target voltage VLr by the actual voltage Vs of 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 instruction (FF instruction) for making the boost ratio (high voltage terminal voltage / low voltage terminal voltage) of the boost circuit 10 close to the target boost ratio Vratio. In other words, the output of the FF module 35 becomes an FF instruction for making the actual voltage VLs of the low voltage terminal 11 close to the target voltage VLr.

[0033] The FF instruction and the FB instruction are summed by the adder 36. The output of the adder 36 becomes a boost ratio instruction for making 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 instruction is input to the driver 37. The driver 37 converts the boost ratio instruction into a duty cycle (Duty instruction). The driver 37 further generates a PWM signal based on the Duty instruction. The PWM signal generated by the driver 37 is a pulse signal with a period Tc, and the ratio 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.

[0034] like Figure 1 As shown, a feedback loop based on the difference (square difference) between the target voltage VLr and the actual voltage VLs is formed in the controller 30. If the controller 30 drives the switch element 15, the actual voltage VLs of the low voltage terminal 11 follows the target voltage VLr. More specifically, through the FF instruction, the actual voltage VLs quickly approaches the target voltage VLr. Through the FB instruction, the variation of the difference between the actual voltage VLs and the target voltage VLr is suppressed.

[0035] As mentioned above, the power supply 100 includes some passive components, but the electrical characteristics of the power supply 100 are unknown. The electrical characteristics of the power supply 100 may affect the feedback control of the controller 30. Figure 2 Let me explain this.

[0036] Figure 2 Yes Figure 1 The circuit diagram is redrawn in the form of control blocks. Figure 2 In the figure, the elements in the FB module 34 (multipliers 34a, 34d, PID controller 34b, differentiator 34c, PI controller 34e) are omitted from the illustration.

[0037] The controller 30 generates a control value (PWM signal) based on the target voltage VLr and the actual voltage VLs of the low voltage end 11 and the current (actual current Is) flowing through the reactor 14 , and supplies the generated PWM signal to the booster circuit 10 (switching element 15 ).

[0038] The controller 30 includes an FB module 34, an FF module 35, and a driver 37. The FB module 34 outputs an FB command based on the square difference between the target voltage VLr and the actual voltage VLs. It should be noted that the actual current Is (see Figure 1 ). The FF module 35 outputs an FF command based on the target voltage VLr. The driver 37 generates a duty command for the switching element based on the total value of the FB command and the FF command, and generates a PWM signal including the duty command. The generated PWM signal is supplied to the boost circuit 10 (switching element 15).

[0039] During the driving of the switching element 15, the actual voltage VLs varies due to various main reasons. The variation of the actual voltage VLs is expressed as a variation of the current flowing to the reactor 14 through the electrical characteristics of the power supply 100. Hereinafter, the current flowing to the reactor 14 will be expressed only as the reactor current. The variation of the reactor current caused by the electrical characteristics of the power supply 100 becomes interference for the control system. Therefore, the variation of the reactor current caused by the electrical characteristics of the power supply 100 is called the interference current Id. In addition, the transfer function until the variation of the actual voltage VLs is expressed as the variation of the actual current Is through the electrical characteristics of the power supply 100 is called the interference transfer function.

[0040] Most 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 referred to as the main current Ia. The actual current Is measured by the current sensor 19 is the total value of the main current Ia and the disturbance current Id. Figure 2 The adder 40 indicates that the main current Ia and the interference current Id are added together to form an actual current Is, which is sent to the controller 30 .

[0041] from Figure 1 and Figure 2It is obvious that the current flowing to the reactor 14 due to the electrical characteristics of the power supply 100 can be regarded as interference (interference current Id) for the control system. The interference current Id will affect the FB command. If it is assumed that the peak frequency of the transfer function of the FB module 34 is close to the peak frequency of the interference current Id, the influence becomes larger. Specifically, the FB command will be greatly disturbed by the change of the interference current Id.

[0042] Therefore, after the power supply 100 is connected and before the battery 200 is charged, the controller 30 performs the following processing to adjust the control system parameter (FB gain) so as to reduce the influence of the disturbance current Id (ie, the electrical characteristics of the power supply 100 ).

[0043] (Processing 1) First, the controller 30 sets the FB instruction to zero, and performs a frequency sweep on the target voltage VLr to obtain a Bode diagram of the interference transfer function from the target voltage VLr to the reactor current (actual current Is). Then, the controller 30 determines the peak frequency (interference peak frequency) on the Bode diagram. "Frequency sweeping the target voltage VLr" means causing the target voltage VLr to vibrate while gradually increasing the frequency from zero. The controller 30 gradually increases the vibration frequency of the target voltage VLr, and measures the actual current Is at prescribed frequency intervals. "Actual current Is / target voltage VLr" at each frequency is equivalent to the gain on the Bode diagram. Figure 3 The upper part of FIG. 1 shows a graph G1 of an example of a disturbance transfer function. The symbol fdp represents the disturbance peak frequency. It should be noted that the transfer function from the change of the actual voltage VLs to the disturbance current Id is the disturbance transfer function, but since the FB command is set to zero, the change of the actual voltage VLs is equal to the change of the target voltage VLr. Therefore, by setting the FB command to zero and sweeping the frequency of the target voltage VLr, a Bode diagram of the disturbance transfer function can be obtained.

[0044] If the peak frequency on the Bode diagram of the control system approaches the disturbance peak frequency fdp, the control performance deteriorates. The controller 30 executes the following (process 2).

[0045] (Processing 2) The controller determines the FB gain included in the FB module 34 in such a manner that the difference between the control peak frequency fcp and the interference peak frequency fdp is greater than the specified threshold frequency width Wf. The control peak frequency fcp is the peak frequency on the Bode diagram of the control transfer function when an ideal power supply assuming no interference is connected to the low voltage terminal 11. Figure 3 The middle graph G2 is a Bode plot when the control peak frequency fcp is larger than the interference peak frequency fdp by more than the threshold frequency width Wf (fcp-fdp>Wf). Figure 3The lower graph G3 is a Bode diagram when the interference 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 so that the Bode diagram of the control system becomes the graph G2 or G3. The threshold frequency width Wf is set to, for example, tens of kilohertz.

[0046] The storage device 39 of the controller 30 stores a plurality of different FB gains and a control peak frequency fcp when each FB gain is selected. It should be noted that the "control transfer function of the controller when an ideal power supply that does not generate interference is connected to the low voltage end" is obtained in advance through simulation. The "ideal power supply that does not generate interference" can be set in the simulation to be a power supply model in which the output current of the power supply is constant even if the voltage at the low voltage end fluctuates. The plurality of different FB gains and a control peak frequency fcp when each FB gain is selected are stored in advance in the storage device 39 of the controller 30.

[0047] The controller 30 selects the FB gain from the plurality of FB gains in such a manner that the difference between the control peak frequency fcp and the interference peak frequency fdp is larger than the threshold frequency width Wf and is closest to the threshold frequency width Wf. When there are candidate control peak frequencies fcp on the low frequency side and the high frequency side of the interference peak frequency fdp, respectively, the controller 30 selects the FB gain corresponding to the control peak frequency fcp that is larger than the interference peak frequency fdp.

[0048] By increasing the difference between the control peak frequency fcp and the disturbance peak frequency, it is possible to suppress the influence of the electrical characteristics of the power supply 100 on the feedback control.

[0049] It should be noted that the FB gain includes Figure 1 The voltage FB gain set for the multiplier 34a and the current FB gain set for the multiplier 34d. In addition to these gains, the FB gain can also include gains (proportional gain, integral gain, and differential gain) included in the PID controller 34b and the PI controller 34e.

[0050] Since the capacitance of the capacitor 17a is included in the voltage FB gain, it cannot be adjusted using the software of the controller 30 (the control program of the controller 30). On the other hand, the current FB gain includes a control period Tc. The control period Tc of the controller 30 is equal to the period of the carrier used to generate the PWM signal. More precisely, the control period Tc is equal to an integer multiple of the period of the carrier. Therefore, by adjusting the period of the carrier, the FB gain can be adjusted. This adjustment can be performed using software. In addition, the proportional gain, integral gain, and differential gain included in the PID controller 34b and the PI controller 34e can also be changed using software. As described above, the FB gains corresponding to a plurality of different control peak frequencies fcp are predetermined by simulation and stored in the storage device 39.

[0051] exist Figure 4 A flowchart of the FB gain determination process is shown in S2. In S2, the following process is performed. The controller 30 sets the FB instruction to zero and performs a frequency scan on the target voltage VLr. According to the frequency scan of the target voltage VLr, the actual voltage VLs will also undergo frequency changes. During the frequency scan, the reactor current (actual current Is) is measured at a specified frequency interval. The value of the actual current Is / target voltage VLr is plotted on the frequency curve. That is, a Bode diagram of the interference transfer function is obtained. The controller 30 determines the peak value (interference peak frequency) in the interference Bode diagram.

[0052] When the frequency sweep is completed, the controller 30 executes S3 . In S3 , the controller 30 selects a FB gain that satisfies |fdp−fcp|>Wf from among the plurality of FB gains stored in the storage device 39 .

[0053] In the case where multiple FB gains are selected in S3 (S4: Yes), S5 is executed. The controller 30 selects a 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 (S6). In the case where one FB gain is selected in S4, the controller 30 sets the selected FB gain as the gain of the FB module 34 (S4: No, S6).

[0054] Through the above processing, the FB gain that can suppress the influence of the electrical characteristics of the power supply 100 is set for the control system. Figure 4 After the processing, the controller 30 drives the switching element 15 using the set FB gain to charge the battery 200.

[0055] The controller 30 sets the FB gain after measuring the actual transfer function (disturbance transfer function) of the power supply 100. Therefore, even when the charger 2 is connected to a power supply with unknown electrical characteristics, it is possible to implement feedback control with little influence of the electrical characteristics of the power supply (influence of disturbance).

[0056] Points to note regarding the technology described in the embodiments are described. The charger may also include multiple boost circuits connected in parallel. The technology of using the switching elements of the converter and the coils of the electric motor as a boost converter is known. The coils of the electric motor function as reactors. In this case, each coil and the switching elements of the three phases constitute a boost circuit. The converter and the electric motor constitute three boost circuits connected in parallel. The charger disclosed in this specification may also include multiple boost circuits that utilize the switching elements of the converter and the coils of the electric motor.

[0057] The PID controller 34b and the PI controller 34e are well known. The control system design technology of the PID controller 34b and the PI controller 34e is also well known. The charger 2 disclosed in this specification has the following characteristics: a plurality of FB gains are prepared in advance in the controller 30, and an appropriate FB gain (an FB gain suitable for suppressing interference) is set according to the electrical characteristics of the connected power supply.

[0058] A PI controller or a PD controller may be used instead of the PID controller 34b that defines the control rule of the FB module 34. Similarly, a PID controller or a PD controller may be used instead of the PI controller 34e.

[0059] The specific examples of the present invention are described in detail above, but they are only examples and do not limit the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exert technical usefulness in the form of individual or various combinations, and are not limited to the combination recorded in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes at the same time, and achieving one of the purposes itself has technical usefulness.

Claims

1. A charger having: A boost circuit, wherein the low voltage end is connected to a power source, the high voltage end is connected to a battery, and the boost circuit includes a reactor and a switching element, wherein the reactor is used to boost the voltage at the low voltage end and output it from the high voltage end; and a controller to drive the switching element in such a manner that the actual voltage of the low voltage terminal is consistent with the target voltage, The controller has: a feedback module, outputting a feedback instruction based on a difference between the square of the target voltage and the square of the actual voltage; A feedforward module outputs a feedforward instruction based on the target voltage; and a driver that generates a pulse width modulation signal for driving the switching element according to a total value of the feedback instruction and the feedforward instruction, The controller sets the feedback instruction to zero and simultaneously performs a frequency sweep on the target voltage to determine a disturbance peak frequency on a Bode diagram of a disturbance transfer function from the target voltage to the current flowing through the reactor. The controller determines the FB gain included in the feedback module in such a way that the difference between a control peak frequency and the interference peak frequency is larger than a specified threshold frequency width, wherein the control peak frequency is the peak frequency on the Bode diagram of the control transfer function of the controller when an ideal power supply assuming no interference is connected to the low voltage end.

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

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

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