CONTROL SYSTEM AND CONTROL METHOD FOR AN ON-BOARD BATTERY CHARGER OF A VEHICLE

Abstract

Control system for a vehicle's on-board battery charger, comprising: a reactive power compensation, PFC, converter (10) which converts an alternating current input from an external AC power source into a direct current and outputs the direct current; an LLC converter (30) that receives the direct current from the PFC converter (10) and sets a level of an output voltage or output current by switching; and a controller (100) that outputs the switching frequency of the LLC converter (30) and receives the output switching frequency of the LLC converter (30) and a resonant frequency of a resonant circuit in the LLC converter (30) and sets an input terminal voltage of the LLC converter (30) so that the switching frequency of the LLC converter (30) becomes the resonant frequency, where the control (100) has: an LLC converter controller (110) that receives an output current command value and an output current measurement value from the LLC converter (30) and outputs the switching frequency of the LLC converter (30); a voltage command generator (130) that receives the switching frequency output by the LLC converter control (110) and the resonant frequency of the resonant circuit in the LLC converter (30) and outputs an intermediate value for the input terminal voltage of the LLC converter (30) such that the switching frequency of the LLC converter (30) becomes the resonant frequency; and a conversion compensator (170) that multiplies an output voltage measurement of the LLC converter (30) by a gain value, sums the product of the output voltage measurement of the LLC converter (30) and the gain value with the intermediate value of the voltage command generator (130) and outputs the sum as the intermediate circuit voltage command value; a reactive power compensation, PFC, converter control (150) which sets the intermediate circuit voltage command value output by the conversion compensator (170) and receives a voltage measurement from the input terminal of the LLC converter (30) and an output voltage of the PFC converter (10).

Description

TECHNICAL AREA

[0001] The present disclosure relates to a control system and a control method for an on-board battery charger (OBC) of a vehicle and in particular a control system and a control method for an OBC of a vehicle for generating an intermediate link voltage command / DC-link voltage command by a PL (proportional-integral) control which considers as a command a resonant switching frequency determined by a resonant capacitance and a resonant inductance in an LLC converter / LLC converter and which enables the switching frequency of the LLC converter to operate at a resonant frequency, thereby improving the efficiency of the OBC. BACKGROUND

[0002] DE 10 2013 105 475 A1 describes a burst mode control for a power converter. The burst mode control includes a burst mode initiation circuit to initiate a burst operating mode when a signal representing an output voltage of the power converter exceeds a first burst threshold level.

[0003] US 2015 / 0 097 528 A1 describes a device for charging a motor-driven device battery. The charging device comprises a first conversion module, a second conversion module, and means for controlling the first conversion module.

[0004] An environmentally friendly vehicle includes a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, a fuel cell vehicle and the like, and among these, the plug-in hybrid vehicle and the electric vehicle can be charged by a user using a household AC power source and a provided on-board battery charger (OBC).

[0005] The OBC installed inside the plug-in hybrid vehicle and the electric vehicle consists of an EMI filter to remove noise from an alternating current source (AC power source), a PFC converter / PFC transducer to control / regulate a power factor, and a DC-DC converter / DC converter to control / regulate the isolation and an output current.

[0006] An LLC converter, as a resonant-type PWM converter, uses a switching mechanism in the hardware to improve efficiency. A conventional non-resonant-type PWM converter, however, uses a method to control output voltage and current by adjusting a duty cycle, while the resonant-type LLC-PWM converter uses a method to control output voltage and current by adjusting a switching frequency. The efficiency of the resonant-type LLC-PWM converter depends heavily on the operating range of the switching frequency, and it is crucial that the switching frequency finds a resonant frequency.

[0007] Traditionally, the DC link voltage (input voltage of an LLC converter = output voltage of a PFC converter) command was generated by sensing / sampling the output voltage and current of the LLC converter. Consequently, if a sensing / sampling error occurred, the required DC link voltage was not generated. As a result, the LLC converter did not operate at its resonant frequency, leading to a reduction in OBC efficiency. Furthermore, because the DC link voltage command was generated by card extraction, a step was traditionally required to verify the switching frequency across all output voltage and current ranges, potentially resulting in additional personnel and costs.

[0008] Therefore, a solution was needed that would allow the switching frequency of the LLC converter to operate at the resonant frequency and solve these problems.

[0009] The foregoing is intended to promote an understanding of the background of the present invention and is not intended to imply that the present invention lies within the field of prior art which is already known to a person skilled in the art. SUMMARY

[0010] The present invention has been made taking into account the above problems that arise in the prior art, and the present invention is intended to propose a control system and a control method for an on-board battery charger (OBC) of a vehicle for generating a DC-link voltage command by a proportional-integral control, which considers / takes into account as a command a resonant switching frequency determined by a resonant capacitance and a resonant inductance in an LLC converter and which enables the switching frequency of the LLC converter to operate at a resonant frequency, thereby improving the efficiency of the OBC.

[0011] The present invention provides a control system and a control method for an on-board battery charger with the features of the independent claims. Further advantageous embodiments are the subject of the dependent claims.

[0012] A control system for an on-board computer (OBC) of a vehicle according to the present disclosure for achieving the above objective comprises a reactive power compensation converter / power factor correction converter that converts an AC input from an external AC source into a DC current and outputs the DC current; an LLC converter that, by switching, adjusts / sets a level of an output voltage or output current with respect to the DC input from the reactive power compensation converter; and a controller that outputs the switching frequency of the LLC converter and receives the output switching frequency of the LLC converter and the resonant frequency of a resonant circuit in the LLC converter and adjusts / sets an input terminal voltage of the LLC converter so that the switching frequency of the LLC converter becomes the resonant frequency.

[0013] The controller includes an LLC converter controller that receives an output current command value and an output current measurement from the LLC converter and outputs the switching frequency of the LLC converter; a voltage command generator that receives the switching frequency output from the LLC converter controller and the resonant frequency of the resonant circuit in the LLC converter and outputs a voltage command value from the input terminal of the LLC converter, so that the switching frequency of the LLC converter becomes the resonant frequency; and a reactive power compensation converter controller that receives the voltage command value from the input terminal of the LLC converter, output by the voltage command generator, and a voltage measurement from the input terminal of the LLC converter and adjusts / sets an output voltage of the reactive power compensation converter.

[0014] The control is further characterized in that it has a conversion compensator which sums a value that multiplies the output voltage measurement value of the LLC converter by a gain value and the output value of the voltage command generator and outputs the voltage command value of the input terminal of the LLC converter.

[0015] The gain value of the conversion compensator is determined taking into account the turns ratio of a transformer in the LLC converter.

[0016] The reactive power compensation converter control includes a voltage regulator that receives the voltage command value of the input terminal of the LLC converter, output by the voltage command generator, and the voltage measurement of the input terminal of the LLC converter, and outputs an input current command value; and a current regulator that receives the output input current command value, a voltage measurement of an external AC source, and an input current measurement, and outputs a switching duty cycle of the reactive power compensation converter control.

[0017] A control method for an OBC of a vehicle according to the present disclosure comprises receiving an output current command value and an output current measurement value of an LLC converter and outputting a switching frequency of the LLC converter; and receiving the output switching frequency of the LLC converter and a resonant frequency of a resonant circuit in the LLC converter and setting / adjusting an input terminal voltage of the LLC converter such that the switching frequency of the LLC converter becomes the resonant frequency.

[0018] Setting / adjusting an input terminal voltage of the LLC converter involves receiving the output switching frequency and the resonant frequency of the resonant circuit in the LLC converter and outputting a voltage command value from the input terminal of the LLC converter, so that the switching frequency of the LLC converter becomes the resonant frequency; and receiving the output voltage command value from the input terminal of the LLC converter and a voltage measurement from the input terminal of the LLC converter, and setting / adjusting an output voltage of a reactive power compensation converter.

[0019] Outputting a voltage command value from the input terminal of the LLC converter is characterized by summing the voltage command value from the input terminal of the LLC converter and a value that multiplies the output voltage measurement value of the LLC converter by a gain value, and outputting the voltage command value from the input terminal of the LLC converter.

[0020] The gain value is determined taking into account the turns ratio of a transformer in the LLC converter.

[0021] According to the control system and control procedure for the vehicle's OBC of the present disclosure, it is possible to improve the efficiency of the OBC by generating the DC link voltage command through a proportional-integral control which takes into account as a command the resonant switching frequency determined by the resonant capacitance and the resonant inductance of the LLC converter and allows the switching frequency of the LLC converter to operate at the resonant frequency.

[0022] As a result, no additional specialist personnel are required due to command card extraction, and costs are saved by having the DC link voltage command issued by the controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other tasks, features, and advantages of the present disclosure will become clearer from the following detailed description in conjunction with the accompanying drawings. The figures show: Fig. 1 to 3 a block diagram representing a control system for an OBC of a vehicle according to an embodiment of the present disclosure; and Fig. 4 a flowchart representing a control procedure for an OBC of a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] A control system and a control procedure for an OBC of a vehicle according to various embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0025] Fig. Figures 1 to 3 show a block diagram representing a control system for an OBC of a vehicle according to an embodiment of the present disclosure, and Fig. Figure 4 shows a flowchart illustrating a control procedure for an OBC of a vehicle according to an embodiment of the present disclosure.

[0026] First, with reference to Fig. 1 and Fig. 2. A control system for an on-board computer (OBC) of a vehicle according to an embodiment of the present invention comprises a power factor correction (PFC) converter 10, which converts an alternating current input from an external AC source into a direct current and outputs the direct current; an LLC converter 30, which sets a level of an output voltage or output current with respect to the direct current input from the PFC converter 10 by switching; and a controller 100, which outputs a switching frequency of the LLC converter 30 and receives the output switching frequency of the LLC converter 30 and a resonant frequency of a resonant circuit in the LLC converter 30 and sets an input terminal voltage of the LLC converter 30 such that the switching frequency of the LLC converter 30 becomes the resonant frequency.

[0027] In this process, the PFC converter 10 reduces invalid power from an external AC power source, converts it into a DC voltage, and outputs it.

[0028] The LLC converter 30, as a resonant-type PWM converter, receives the DC voltage output by the reactive power compensation section and sets and outputs a level of an output voltage or current.

[0029] The controller 100 can include an LLC converter controller 110, a voltage command generator 130 and a reactive power compensation converter controller 150.

[0030] The controller 100 and its sub-controllers, including the LLC converter controller 110, the voltage command generator 130 and the reactive power compensation converter controller 150, are an electrical circuit that executes software commands, thereby performing various functions, which are described below.

[0031] The following equation 1 specifies a transfer function for an output voltage / input voltage of the resonant circuit (a resonant tank) in the LLC converter 30, and it is understood that the switching frequency (fs) and an intermediate circuit voltage (Vdc) of the LLC converter 30 have a directly proportional characteristic. Accordingly, the present disclosure serves to variably control the intermediate circuit voltage so that the switching frequency of the LLC converter 30 operates at the resonant frequency of the resonant circuit using the directly proportional characteristic of the switching frequency and the intermediate circuit voltage. As a result, the present disclosure can improve the operating efficiency of the OBC. VOVDC=fs2fr2(m−1)n(mfs2fr2−1)2+fs2fr2(fs2fr2−1)2(m−1)2(π2Lr / Cr8n2Ro)2 (V0: an output voltage of the LLC converter 30 V) DC : an input voltage of the LLC converter 30 (PFC output voltage), f s: a switching frequency of the LLC converter 30, f r : a resonant frequency of the resonant circuit in the LLC converter 30, m:Lr+LmLr, n: a winding ratio Np(Ns), R o : one output terminal resistance of the LLC converter 30)

[0032] Next, the operation of the controller 100 is described. The controller 100 can output the switching frequency of the LLC converter 30 and receive the output switching frequency of the LLC converter and the resonant frequency of the resonant circuit in the LLC converter, and adjust an input voltage of the LLC converter 30 so that the switching frequency of the LLC converter 30 becomes the resonant frequency. More precisely, the controller 100 receives an output voltage command from the LLC converter 30 and outputs the switching frequency output by the LLC converter controller 110, and performs proportional-integral control (PL control) through the voltage command generator 130 so that the switching frequency follows a command value of the resonant frequency.An intermediate circuit voltage command value, specifying a command value of the input terminal of the LLC converter 30, is output by the voltage command generator 130; the value is input into the reactive power compensation converter control 150; an operating value (duty value) of the reactive power compensation converter control 150, which allows the switching frequency of the LLC converter 30 to operate at the resonant frequency, is output; and an output voltage of the PFC converter 10 is set.

[0033] With reference to Fig. 3 The LLC converter control 110, as an embodiment of the present disclosure, can comprise an LLC voltage regulator that receives the output voltage command of the LLC converter 30 and extracts an output current command value, and an LLC current regulator 112 that receives the output current command value and an output current measurement value and outputs the switching frequency of the LLC converter 30 by means of a proportional-integral control (Pl control).

[0034] The voltage command generator 130 receives the switching frequency and the resonant frequency of the resonant circuit in the LLC converter 30 output by the LLC converter controller 110 and outputs the voltage command value of the input terminal of the LLC converter 30 by means of a proportional-integral control (PI control), so that the switching frequency follows a command value of the resonant frequency.

[0035] The resonant frequency specifies a frequency determined by a resonant capacitance (Cr) and a resonant inductance (Lr) of the resonant circuit in the LLC converter 30, and the switching frequency specifies a frequency output by the LLC converter control 110.

[0036] The reactive power compensation converter control 150 can, as an embodiment of the present disclosure, comprise a voltage regulator 152, which receives the voltage command value of the input terminal of the LLC converter 30 output by the voltage command generator 130 and a voltage measurement of the input terminal of the LLC converter 30 and outputs an input current command value, and a current regulator 154, which receives the output input current command value, a voltage measurement of an external AC source and an input current measurement and outputs a switching duty cycle of the reactive power compensation converter control.

[0037] The voltage regulator 152 outputs the input current command value flowing through an inductor of the PFC converter 10 via a proportional-integral (PI) controller, with reference to the output voltage measurement of the PFC converter 10 and the voltage command value of the input terminal of the LLC converter 30, which is output by the voltage command generator 130. The current regulator 154 receives a value that multiplies the output RMS input current command value by the output voltage measurement of an external AC power source and the input current measurement flowing through the inductor of the PFC converter 10, and outputs a switching duty cycle of the power compensation converter controller 150 via a proportional-integral (PI) controller.

[0038] In Fig. 3. According to an embodiment of the present disclosure, the control system for the vehicle's OBC can further comprise a conversion compensator 170 which sums a value that multiplies the output voltage measurement value of the LLC converter 30 by a gain value and the output value of the voltage command generator 130, and which outputs the voltage command value of the input terminal of the LLC converter 30.

[0039] The conversion compensator 170 is implemented / realized by a processor which has an associated non-volatile memory that stores software instructions which, when executed by the processor, provide the functionalities of the conversion compensator 170.

[0040] The processor can take the form of one or more processors and an associated memory that stores program instructions, and in some examples the one or more processors can be used to implement the functions of both the controller 100 and the processor.

[0041] It is advantageous to reduce the load on the PLC control in the voltage command generator 130 and achieve a stable response by summing the value output by the voltage command generator 130 and the value multiplied by the gain value of the output voltage measurement of the LLC converter 30, and outputting the voltage command value of the input terminal of the LLC converter 30. The gain value (K) of the conversion compensator 170 can be determined by a turns ratio (N). p :N s ) of a transformer in the LLC converter and other factors are determined.

[0042] With reference to Fig. 4. A control method for an OBC of a vehicle according to an embodiment of the present disclosure may include receiving an output current command value and an output current measurement value of an LLC converter and outputting a switching frequency of the LLC converter (S100); and receiving the output switching frequency of the LLC converter and a resonant frequency of a resonant circuit in the LLC converter and adjusting / adjusting an input terminal voltage of the LLC converter such that the switching frequency of the LLC converter becomes the resonant frequency (S500).

[0043] The output of the switching frequency of the LLC converter (S100) receives an output voltage command from the LLC converter and extracts the output current command value, and receives the extracted output current command value and the output current measurement value and outputs the switching frequency of the LLC converter through a proportional-integral control (PI control).

[0044] Setting / adjusting the input terminal voltage of the LLC converter (S500) receives the output switching frequency and the resonant frequency of the resonant circuit in the LLC converter and outputs the voltage command value of the input terminal of the LLC converter, so that the switching frequency becomes the resonant frequency (S300); and outputs an input current command value flowing through an inductor in a reactive power compensation converter through a proportional-integral control (PI control) with reference to the output voltage command value of the input terminal of the LLC converter and an output voltage measurement of the reactive power compensation converter.The input voltage setting / adjustment of the LLC (S500) receives a value that multiplies the output RMS input current command value by an input voltage measurement from an external AC source and the input current measurement flowing through the inductor of the power compensation converter. This outputs a switching duty cycle for the power compensation converter control via a proportional-integral (PL) control (S500). Finally, a DC link voltage command, through repeated control / regulation, specifies the output voltage of the power compensation converter control, generated by the output switching duty cycle, ensuring that the switching frequency of the LLC converter operates at the resonant frequency.As a result, it is possible to improve the efficiency of the OBC; by issuing the DC link voltage command through the controller, no additional specialist personnel are required due to command card extraction and the like, and costs are saved.

[0045] The control method for the vehicle's OBC according to an embodiment of the present disclosure can sum the output voltage command value of the input terminal of the LLC converter (S300) and the value that multiplies the output voltage measurement value of the LLC converter by the gain value, and output the voltage command value of the input terminal of the LLC converter.

[0046] As a result, it is advantageous to reduce the load on a PI controller and obtain a stable response by summing the output voltage command value of the LLC converter's input terminal and the value that multiplies the LLC converter's output voltage measurement by the gain value, and outputting the voltage command value to the LLC converter's input terminal. The gain value (K) can be determined by a turns ratio (N). p :N s ) of a transformer in the LLC converter 30 and other factors are determined.

[0047] As described above, the control system and control method for the vehicle's OBC, according to various embodiments of the present disclosure, generate the DC link voltage command by means of a proportional-integral control which takes into account as a command the resonant switching frequency determined by the resonant capacitance and the resonant inductance of the LLC converter, and enables the switching frequency of the LLC converter to operate at the resonant frequency, thereby improving the efficiency of the OBC.

[0048] Furthermore, no additional specialist personnel are required due to command card extraction and the like, and costs can be saved by having the DC link voltage command issued by the controller.

[0049] Although various embodiments of the present disclosure have been described for illustrative purposes, a person skilled in the art will recognize that various modifications, additions and substitutions are possible without deviating from the scope and teaching of the disclosure as disclosed in the attached claims.

Claims

[1] Control system for an on-board battery charger of a vehicle, comprising: a reactive power compensation, PFC, converter (10) which converts an alternating current input from an external AC power source into a direct current and outputs the direct current; an LLC converter (30) that receives the direct current from the PFC converter (10) and sets a level of an output voltage or output current by switching; and a controller (100) that outputs the switching frequency of the LLC converter (30) and receives the output switching frequency of the LLC converter (30) and a resonant frequency of a resonant circuit in the LLC converter (30) and sets an input terminal voltage of the LLC converter (30) so that the switching frequency of the LLC converter (30) becomes the resonant frequency, where the control (100) has: an LLC converter controller (110) that receives an output current command value and an output current measurement value from the LLC converter (30) and outputs the switching frequency of the LLC converter (30); a voltage command generator (130) that receives the switching frequency output by the LLC converter control (110) and the resonant frequency of the resonant circuit in the LLC converter (30) and outputs an intermediate value for the input terminal voltage of the LLC converter (30) such that the switching frequency of the LLC converter (30) becomes the resonant frequency; and a conversion compensator (170) that multiplies an output voltage measurement of the LLC converter (30) by a gain value, sums the product of the output voltage measurement of the LLC converter (30) and the gain value with the intermediate value of the voltage command generator (130) and outputs the sum as the intermediate circuit voltage command value; a reactive power compensation, PFC, converter control (150) which sets the intermediate circuit voltage command value output by the conversion compensator (170) and receives a voltage measurement from the input terminal of the LLC converter (30) and an output voltage of the PFC converter (10). [2] Control system for the OBC of the vehicle according to claim 1, wherein the gain value of the conversion compensator (170) is determined taking into account a turns ratio of a transformer in the LLC converter (30). [3] Control system for the OBC of the vehicle according to claim 1, wherein the PFC converter control comprises: a voltage regulator (152) that receives the intermediate circuit voltage command value output by the conversion compensator (170) and the voltage measurement of the input terminal of the LLC converter (30) and outputs an input current command value; and a current controller (154) that receives the output input current command value, a voltage measurement from the external AC source and an input current measurement, and outputs a switching duty cycle of the PFC converter control (150). [4] Tax procedure for an on-board battery charger of a vehicle, comprising: Receiving an output current command value and an output current measurement value of an LLC converter (30) and outputting (S100) a switching frequency of the LLC converter (30), and Receiving the output switching frequency of the LLC converter (30) and a resonant frequency of a resonant circuit in the LLC converter (30) and setting an input terminal voltage of the LLC converter (30) such that the switching frequency of the LLC converter (30) becomes the resonant frequency, where setting an input connection voltage of the LLC converter (30) has: Receiving the output switching frequency and the resonant frequency of the resonant circuit in the LLC converter (30) and outputting an intermediate value for the input terminal voltage of the LLC converter (30) such that the switching frequency of the LLC converter (30) becomes the resonant frequency; and Summing the intermediate value for the input terminal voltage of the LLC converter (30) and a product of the output voltage measurement of the LLC converter (30) and a gain value, receiving a voltage measurement of the input terminal of the LLC converter (30) and outputting (S300) the DC link voltage command; Receiving the intermediate circuit voltage command and a voltage measurement of the input terminal of the LLC converter (30) and setting (S500) an output voltage of a reactive power compensation, PFC, converter (10). [5] Control method for the OBC of the vehicle according to claim 4, wherein the gain value is determined taking into account a turns ratio of a transformer in the LLC converter (30).

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