Multimode Control Method

Abstract

To provide a multi-mode control method for controlling the charging or discharging of an LLC resonant converter.SOLUTION: A multi-mode control method includes operating an LLC resonant converter in a burst mode when an output current of the LLC resonant converter is determined to be a light load, operating the LLC resonant converter that has been in the burst mode in a PWM mode in response to an increase in the load of the LLC resonant converter or an increase in the output voltage during charging control, or operating the LLC resonant converter that has been in the burst mode in PFM mode in response to an increase in the load or a decrease in the input voltage during discharging control, operating the LLC resonant converter that has been in the PWM mode in the PFM mode in response to a further increase in the load or a further increase in the output voltage during charging control, and operating the LLC resonant converter that has been in the PFM mode in the PSM mode in response to a further increase in the load or a further decrease in the input voltage during discharging control.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a multi-mode control method, and more particularly to a multi-mode control method applied to wide voltage range operation of LLC. [Background technology]

[0002] With the growing awareness of environmentally friendly green energy, the number of electric vehicles sold is doubling, and the demand for charging stations is also increasing. In the application of in-vehicle (electric vehicle) chargers, the LLC resonant converter configuration is widely used. For example, taking the LLC resonant converter configuration shown in Figure 1 as an example, in forward charging (i.e., an external power supply charges the battery of an electric vehicle), the input side is the VBUS side (input voltage is V BUS ), the output side is the HVDC side, and the HVDC side is a normal battery (output voltage is HVbattery), and the battery voltage differs greatly between when fully charged and when lightly charged, so the range of change in battery voltage (i.e., output voltage) is wide. In reverse discharge (i.e., discharging the electric vehicle battery to the outside), the input side is the HVDC side (input voltage is HVbattery) and the output side is the VBUS side (output voltage is VBUS), and in this case the range of input voltage is wide.

[0003] The hardware design of a conventional LLC resonant converter has two main problems. First, the burst mode period is too large. As shown in Figure 1, the battery voltage change range as input voltage (discharge mode, i.e., DCHG mode) or output voltage (charge mode, i.e., CHG mode) is too wide, resulting in an over-designed burst mode period. Second, when operating in discharge mode (DCHG mode), the required voltage cannot be supplied to the inverter. During reverse discharge operation, the voltage supplied to the VBUS side is high at 400 volts, which is insufficient to supply the required voltage to the inverter for bidirectional operation. Here, the inverter is a power factor corrector (AC-DC converter) connected to the VBUS side during forward charging, and an inverter (DC-AC converter) during reverse discharge.

[0004] In conventional control methods, in charging mode, the gain on the HVDC side is too high at low voltages, causing the control mode to switch from Pulse Frequency Modulation (PFM) mode back to burst mode, resulting in excessive ripple in the output voltage (in this case, the duty cycle is fixed at 50%). However, depending on the design of the resonant tank for different hardware, a larger current is required to exit burst mode and return to PFM mode when the HVDC side is at low voltage. For example, 220 volts and 8 amps are typically required to exit burst mode and return to PFM mode.

[0005] On the other hand, when the HVDC voltage is insufficient during discharge mode, conventional delay time control can be used to shift the output switching signal and short-circuit the transformer, thereby increasing the resonant energy and voltage gain. However, the displacement of the conventional delay control method first establishes a lookup table relationship based on the output voltage and input voltage. Because this is an open-loop lookup table method, it is necessary to carefully check each input and output condition before designing, which increases the complexity of the software and the uncertainty of the conditions.

[0006] Therefore, in order to solve the problems and technical bottlenecks of the prior art, how to design a multi-mode control method, especially a multi-mode control method applicable to wide voltage range operation of LLC, is an important issue that has been considered by the present inventors. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multi-mode control method. [Means for solving the problem]

[0008] In order to achieve the above object, a multi-mode control method according to the present invention is used for controlling charging or discharging of an LLC resonant converter, and includes controlling the LLC resonant converter to operate in burst mode when it is determined that the output current of the LLC resonant converter is lightly loaded; and controlling the LLC resonant converter that was in the burst mode to operate in PWM mode in response to an increase in the load of the LLC resonant converter or an increase in the output voltage in charging control, or controlling the LLC resonant converter that was in the burst mode to operate in PFM mode in response to an increase in the load of the LLC resonant converter or a decrease in the input voltage in discharging control; and controlling the LLC resonant converter that was in the PWM mode to operate in PFM mode in response to a further increase in the load of the LLC resonant converter or a further increase in the output voltage in charging control, or controlling the LLC resonant converter that was in the PFM mode to operate in PSM mode in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage in discharging control.

[0009] In one embodiment, the PFM mode of charging control further includes controlling the LLC resonant converter to operate in the PSM mode in response to a further increase in the load of the LLC resonant converter or a further increase in the output voltage.

[0010] In one embodiment, the input side of the LLC resonant converter is a DC bus side for supplying an input voltage, and the output side of the LLC resonant converter is a battery load side for supplying a wide range of output voltages, and the LLC resonant converter performs step-down charging control when the output voltage is lower than the input voltage, or performs step-up charging control when the output voltage is higher than the input voltage.

[0011] In one embodiment, the burst mode operates at a constant duty cycle and a constant frequency.

[0012] In one embodiment, when controlling charging, the PWM mode operates with a varying duty cycle and a constant frequency, and the duty cycle when operating in the PWM mode is greater than the duty cycle when operating in the burst mode.

[0013] In one embodiment, during charging control, the PFM mode operates at a constant duty cycle and a varying frequency, the frequency when operating in the PFM mode being lower than the frequency when operating in the PWM mode.

[0014] In one embodiment, during charging control, the LLC resonant converter is controlled to operate in the PSM mode with a constant duty cycle, a constant frequency and a varying phase shift, and the frequency when operating in the PSM mode is lower than the frequency when operating in the PFM mode.

[0015] In one embodiment, when operating in the burst mode, the duty cycle is fixed at a minimum value and the frequency is fixed at a maximum frequency.

[0016] In one embodiment, when operating in the PWM mode, the duty cycle varies between 50% and a minimum value, and the frequency is fixed at a maximum frequency.

[0017] In one embodiment, when operating in the PFM mode, the duty cycle is fixed at 50% and the frequency varies between a maximum frequency and a minimum frequency.

[0018] In one embodiment, when operating in the PSM mode, the duty cycle is fixed at 50%, the frequency is fixed at a minimum frequency, and the phase shift varies between 0% and a maximum value.

[0019] In one embodiment, during discharge control, the LLC resonant converter that has been in the burst mode is controlled to operate in the PWM mode in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage.

[0020] In one embodiment, the input side of the LLC resonant converter is a battery load side for supplying a wide range of input voltages, and the output side of the LLC resonant converter is a DC bus side for supplying an output voltage, and the LLC resonant converter performs step-down discharge control when the input voltage is higher than the output voltage, and performs step-up discharge control when the input voltage is lower than the output voltage.

[0021] In one embodiment, during discharge control, the PFM mode operates with a constant duty cycle and a varying frequency, the duty cycle when operating in the PFM mode being greater than the duty cycle when operating in the burst mode, and the frequency when operating in the PFM mode being lower than the frequency when operating in the burst mode.

[0022] In one embodiment, during discharge control, the PSM mode operates with a constant duty cycle, a constant frequency and a varying phase shift, and the frequency when operating in the PSM mode is lower than the frequency when operating in the PFM mode.

[0023] In one embodiment, during discharge control, the PWM mode operates with a varying duty cycle and a constant frequency, and the duty cycle when operating in the PWM mode is greater than the duty cycle when operating in the burst mode.

[0024] In one embodiment, when operating in the PFM mode, the duty cycle is fixed at 50% and the frequency varies between a maximum frequency and a minimum frequency.

[0025] In one embodiment, when operating in the PSM mode, the duty cycle is fixed at 50%, the frequency is fixed at a minimum frequency, and the phase shift varies between 0% and a maximum value.

[0026] In one embodiment, when operating in the PWM mode, the duty cycle varies between 50% and a minimum value, and the frequency is fixed at a maximum frequency. [Effects of the Invention]

[0027] The multi-mode control method of the present invention has the following features and advantages: (1) The size of the burst mode section can be appropriately designed in a wide range of voltage applications. (2) When operating in discharge mode, the voltage required by the inverter can be stably supplied. (3) When operating in light load and low output voltage, the resonant converter is controlled to operate in PWM mode or burst mode, thereby reducing output voltage ripple. (4) When operating in discharge mode with heavy load and low input voltage, the resonant converter is controlled to operate in PSM mode, thereby increasing the voltage gain and further increasing the output voltage.

[0028] In order to better understand the techniques, means, and advantages of the present invention which are contemplated to achieve the objects of the present invention, the objects and features of the present invention will be better understood by referring to the detailed description of the invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the invention. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a circuit diagram of an LLC resonant converter according to the present invention; [Figure 2] FIG. 2 is a schematic diagram of a first operation mode in the charging operation of the present invention. [Figure 3] FIG. 4 is a schematic diagram of a second operation mode in the charging operation of the present invention. [Figure 4]FIG. 2 is a schematic diagram of a first operation mode in the discharging operation of the present invention. [Figure 5] FIG. 4 is a schematic diagram of a second operation mode in the discharging operation of the present invention. [Figure 6] FIG. 4 is a schematic diagram of control signals for the primary and secondary side active switches in the charging operation of the present invention. [Figure 7] FIG. 10 is a schematic diagram of control signals for the primary and secondary active switches in the discharging operation of the present invention. [Figure 8] 4 is a flowchart of a first operation mode of the multi-mode control method of the present invention. [Figure 9] 4 is a flowchart of a second operation mode of the multi-mode control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The technical contents and detailed description of the present invention will be described below with reference to the drawings.

[0031] FIG. 1 is a circuit diagram of an LLC resonant converter according to the present invention. Referring to FIG. 1, this configuration is applied to a bidirectional vehicle charger in the present invention. The load on the secondary side of the above configuration is typically a battery, and both the primary and secondary sides provide active switches. For example, the primary side provides active switches VBUS_A to VBUS_D, and the secondary side provides active switches HVDC_A to HVDC_D. Depending on the scenario, it can be determined whether to use forward charging (hereinafter referred to as charging, charging operation, or charging mode (CHG mode)) or reverse discharging (hereinafter referred to as discharging, discharging operation, or discharging mode (DCHG mode)).

[0032] In the case of charging, the input side is the VBUS side, and the voltage change rate is usually low (input voltage V BUScan be considered fixed), if it is a single-phase system, the input voltage may be, for example, 400 volts, but is not limited to this, the output side is the HVDC side and is usually a battery, and the battery voltage (i.e., output voltage HVbattery) varies over a wide range depending on the usage state, and may be, for example, 220 to 430 volts, but is not limited to this. Therefore, in charging operation, the LLC resonant converter charges the battery using a step-down method when the output voltage is lower than the input voltage (for example, input voltage is 400 volts, output voltage is 220 volts), and charges the battery using a step-up method when the output voltage is higher than the input voltage (for example, input voltage is 400 volts, output voltage is 430 volts).

[0033] In the case of discharging (power flow direction is opposite to charging), the input side is the HVDC side and the output side is the VBUS side, in this case the output voltage is fixed at 400 volts, and the input voltage has a wide range of variation, for example, it may be 220 to 430 volts, but is not limited to this. Therefore, in discharging operation, the LLC resonant converter discharges in a step-up manner when the input voltage is lower than the output voltage (for example, input voltage 220 volts, output voltage 400 volts), and discharges in a step-down manner when the input voltage is higher than the output voltage (for example, input voltage 430 volts, output voltage 400 volts).

[0034] In charge mode (CHG mode), the controller extracts the battery-side voltage Vo and current Io, selects the smaller of the two control loops (voltage control loop and current control loop), calculates it, and then outputs a PWM signal to control the primary-side switches (VBUS_A to VBUS_D) and secondary-side switches (HVDC_A to HVDC_D). In discharge mode (DCHG mode), only VBUS needs to be controlled, so there is a single control loop (voltage loop). Note that the primary and secondary sides described here are defined differently due to the difference in power flow between charge mode and discharge mode. In charge mode, the VBUS side is the primary side and the HVDC side is the secondary side; conversely, in discharge mode, the HVDC side is the primary side and the VBUS side is the secondary side.

[0035] 2 is a schematic diagram of a first operation mode in the charging operation of the present invention. This figure shows how the burst mode integrates the pulse width modulation (PWM) mode and the PFM mode. As mentioned above, in the charging operation, the LLC resonant converter charges the battery in a buck conversion manner (when the input voltage is higher than the battery voltage) or in a boost conversion manner (when the input voltage is lower than the battery voltage when the battery is fully charged so that the battery voltage gradually increases).

[0036] Therefore, if the converter operates at a fixed maximum frequency during charging, the duty cycle is adjusted, for example, between the maximum duty cycle (50%) and the minimum duty cycle, so that the converter operates in PWM mode. The purpose of adding PWM mode between PFM mode and burst mode is explained below. When applied to a wide range of input voltages or output voltages, the burst mode of PFM mode maintains a constant duty cycle and a constant frequency, i.e., maintains (fixes) the maximum frequency and maintains a maximum duty cycle of 50%, but generates ripple in the output voltage. Therefore, by introducing PWM mode, rather than adjusting the duty to a fixed maximum of 50%, burst mode is used at a minimum duty cycle below 50% (e.g., 10%), i.e., a variable duty cycle and constant frequency control method is used to operate the resonant converter in PWM mode. This reduces the output voltage ripple during burst mode, thereby achieving the effect of reducing output voltage ripple even under lighter loads.

[0037] Specifically, as shown in Figure 2, the horizontal axis represents the output voltage (HVDC side voltage) and the vertical axis represents the output power (i.e., output current). For example, when the output voltage is close to the minimum voltage (HVDC_min, e.g., 220 volts), the output current is small, and the output power is also small (lower than the minimum power Po_min), i.e., the resonant converter output current is lightly loaded, and the resonant converter typically operates in burst mode. As the output power increases, the resonant converter exits burst mode and enters PWM mode. When the output power further increases and exceeds the boundary power (Po_boundary), the resonant converter exits PWM mode and enters PFM mode. Note that, to accommodate fluctuations in the converter output current (output power) depending on different output voltages (i.e., HVDC side voltages), the boundary power (Po_boundary) and minimum power (Po_min) decrease as the output voltage (HVDC side voltage) increases, as shown in Figure 2. In other words, the boundary power (Po_boundary) and minimum power (Po_min) are not constant output values. Similar characteristics are also shown in FIGS. 3 to 5, but detailed explanations thereof will be omitted here.

[0038] Furthermore, as the output voltage increases, for example, when the output voltage is at the breakover voltage (HVDC_break, e.g., 300 volts), the resonant converter does not need to require as much output power to exit burst mode and enter PWM mode. In other words, the resonant converter does not need as much output power to exit burst mode and enter PWM mode. Furthermore, because the PWM mode range is narrow, a slightly higher output power is needed to exit PWM mode and enter PFM mode. Similarly, as the output voltage increases, the resonant converter is more likely to exit burst mode and enter PWM mode. By controlling the resonant converter with a fixed duty cycle (e.g., a fixed duty cycle of 50%) and a variable frequency (varies between a maximum frequency and a minimum frequency), the resonant converter is more likely to exit PWM mode and enter PFM mode, thereby entering the normal operating mode. Note that the maximum frequency of the present invention may be designed based on power and efficiency and / or the performance of the digital chip. According to the characteristics and experimental results of a hardware resonant tank, the gain curve does not change much at high frequencies. However, since the resolution of a digital chip is poor, the maximum frequency is designed taking into account the performance of the digital chip. Furthermore, the minimum frequency of the present invention may be designed based on power and efficiency, and / or the ability to smoothly output voltage when the gain peak is exceeded. This is because, according to the characteristics and experimental results of a hardware resonant tank, there is a problem that the output voltage cannot be achieved when the gain peak is exceeded at low frequencies. Therefore, the minimum frequency must be designed taking this into account. Furthermore, the maximum and minimum frequencies are designed taking into account the extreme values ​​of the entire charging and discharging process.

[0039] In other words, to accommodate a wide range of output voltages and achieve the goal of reducing output voltage ripple even when operating under very light loads, PWM mode is introduced to solve the problem that, especially when operating under very light loads, the effect of reducing voltage ripple cannot be achieved even when PFM mode enters burst mode operation.

[0040] In this way, by integrating PFM mode and burst mode through PWM mode, the situation where the voltage gain is too high when the output voltage is low or the input voltage is high can be resolved, and even when the output voltage enters burst mode, excessive fluctuations will not occur, and a more stable output effect can be achieved.

[0041] FIG. 3 is a schematic diagram of a second operation mode in the charging operation of the present invention. Compared with the first operation mode shown in FIG. 2, the second operation mode further adds phase-shift modulation (PSM) control. In charging operation, the secondary side becomes the synchronous rectification side. In PFM mode and PWM mode, whether to turn on the synchronous rectification function can be determined according to efficiency requirements. Furthermore, the originally open-loop phase-shift control method can be changed to a closed-loop control method. When the frequency gradually drops to the minimum frequency due to insufficient voltage gain, the phase shift on the synchronous rectification side can be performed at a constant frequency and duty, i.e., a constant duty cycle (e.g., duty cycle fixed at 50%), a constant frequency (e.g., frequency fixed at the minimum frequency), and a variable phase shift (e.g., phase shift variable between 0% and the maximum value) control method can increase the voltage conversion ratio. The parameters can be easily adjusted by simply determining the minimum frequency and limiting the maximum amount of phase shift. Therefore, PSM mode control with delay control can achieve high output voltages and high voltage gains under heavy loads, which cannot be achieved by PFM mode operation alone in closed-loop and low-frequency applications. The maximum phase shift value of the present invention may be designed based on power and efficiency, and / or may be designed to ensure smooth voltage output when the gain peak is exceeded. This is because, based on the characteristics of the hardware resonant tank and experimental results, there is a problem in that the output voltage cannot be achieved when the gain peak is exceeded at low frequencies. Therefore, the maximum phase shift value must be designed taking this into account. Furthermore, the maximum phase shift value is designed taking into account the extreme values ​​of the entire charge / discharge process.

[0042] FIG. 6 is a schematic diagram of the control signals of the primary-side and secondary-side active switches during charging operation of the present invention, showing the duty cycle controlled between a minimum and a maximum value. As shown in the figure, the duty cycle is controlled between a minimum and a maximum value by expanding from the minimum duty cycle indicated by the solid line to the maximum duty cycle indicated by the dashed line. For example, as the load increases, the duty cycle can be increased from the minimum to the maximum, or the frequency can be varied by switching to PFM mode (normal operation mode). The minimum duty cycle of the present invention may be designed based on power and efficiency, and / or the performance of the gate driver and the digital chip. The maximum duty cycle of the present invention is 50%, based on the fact that the present invention is a resonant converter. Furthermore, the minimum and maximum duty cycles are designed taking into account the extreme values ​​of the entire charging and discharging process.

[0043] 4 is a schematic diagram of the first operation mode in the discharge operation of the present invention. The resonant converter operates in normal operation, i.e., PFM mode, and when the frequency gradually decreases and reaches the minimum limit frequency, delay time control is initiated, causing the resonant converter to operate in PSM mode, in which the purpose of delay time control is achieved by phase shifting the switching signal to stabilize the output voltage.

[0044] Specifically, if the load becomes heavy during discharge operation and the input voltage is insufficient to supply a stable output voltage, delay time control is used to shift the secondary side switching signal to short-circuit the transformer and forcibly increase the resonant energy, thereby increasing the voltage gain and maintaining a stable output voltage.

[0045] FIG. 5 is a schematic diagram of a second operating mode in the discharge operation of the present invention. Compared to the first operating mode shown in FIG. 4, the second operating mode adds a PWM mode between the PFM mode and the burst mode. The operating mode is adjusted according to different input voltage and output voltage conditions. For example, when the load is light or the input voltage is low, the device can operate in burst mode or PWM mode. When the load becomes heavy or the input voltage drops, the device switches to PFM mode. When the load increases further or the input voltage drops further, and the frequency reaches its lowest frequency, the device switches to PSM mode. This increases the voltage gain and controls the output voltage to be stable.

[0046] Figure 7 is a schematic diagram of the control signals for the primary-side and secondary-side active switches in the discharging operation of the present invention. As mentioned above, when operating in discharging mode (DCHG mode), if the input voltage is insufficient or the output load becomes excessive, the resonant converter will not be able to supply the voltage required by the inverter. Therefore, phase shift control is used to maintain the output voltage so that the required voltage can be supplied to the inverter. As shown in the figure, in normal synchronous rectification control, the primary-side switches (HVDC_A to HVDC_D) and secondary-side switches (VBUS_A to VBUS_D) are controlled correspondingly. However, in PSM mode operation, by shifting the switches on the secondary side (i.e., the VBUS side), for example, switch A (i.e., VBUS_A) is phase-shifted so that the conduction times of switch A and switch C (i.e., VBUS_C) overlap, shorting the transformer and forcibly increasing resonant energy, and similarly, switch B (i.e., VBUS_B) is phase-shifted so that the conduction times of switch B and switch D (i.e., VBUS_D) overlap, shorting the transformer and forcibly increasing resonant energy, thereby increasing the voltage gain and maintaining the output voltage. Note that in PSM mode operation in charging mode, as described in this paragraph, the secondary side switches (i.e., switches HVDC_A and HVDC_B on the synchronous rectification side) are also phase-shifted in a similar way to increase the voltage gain.

[0047] 8 is a flowchart of a first operation mode of the multi-mode control method of the present invention. The multi-mode control method is used to control the charging or discharging of an LLC resonant converter, and includes controlling the LLC resonant converter to operate in burst mode when it is determined that the output current of the LLC resonant converter is a light load (S11, S21).

[0048] During charging control, the LLC resonant converter is controlled to operate in PWM mode in response to an increase in the load on the LLC resonant converter or an increase in the output voltage (S12), or during discharging control, the LLC resonant converter is controlled to operate in PFM mode in response to an increase in the load on the LLC resonant converter or a decrease in the input voltage (S22).

[0049] During charging control, the LLC resonant converter is controlled to operate in PFM mode in response to a further increase in the load of the LLC resonant converter or a further increase in the output voltage (S13), or during discharging control, the LLC resonant converter is controlled to operate in PSM mode in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage (S23).

[0050] FIG. 9 is a flowchart of a second operation mode of the multi-mode control method of the present invention. Specifically, during charge control, S10 in FIG. 9 corresponds to S11 in FIG. 8, S20 corresponds to S12 in FIG. 8, and S30 corresponds to S13 in FIG. 8. Compared to the first operation mode shown in FIG. 8, during charge control in PFM mode (S13), the LLC resonant converter is controlled to operate in PSM mode (S40) in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage. On the other hand, during discharge control, S10 in FIG. 9 corresponds to S21 in FIG. 8, S20 corresponds to S22 in FIG. 8, and S30 corresponds to S23 in FIG. 8. Compared to the first operation mode shown in FIG. 8, during discharge control in burst mode (S21), the LLC resonant converter is controlled to operate in PWM mode (S20) in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage. In this way, as shown in FIG. 9, the LLC resonant converter can operate in multiple modes, including burst mode, PWM mode, PFM mode, and PSM mode, whether it is charge control or discharge control, and can operate in accordance with charge and discharge operations over a wide range of voltages.

[0051] In summary, the features and advantages of the present invention are as follows: (1) In application of a wide range of input voltages or output voltages, the size of the burst mode section is appropriately designed. (2) When operating in discharge mode, it stably supplies the voltage required by the inverter. (3) During charging operation, when the load is light and the output voltage is low, the resonant converter is controlled to operate in PWM mode or burst mode, thereby reducing the ripple of the output voltage. (4) During discharge operation, when operating under heavy load and low input voltage, the resonant converter is controlled to operate in PSM mode, increasing the voltage gain and maintaining a stable output voltage.

[0052] The above describes in detail preferred embodiments of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to such examples, and does not limit the scope of the present invention. The entire scope of the present invention is based on the following claims. The spirit and similar modifications that conform to the scope of the claims of the present invention should be included in the scope of the present invention. Those skilled in the art can easily think of modifications and alterations within the technical scope of the present invention, and such modifications and alterations are also included in the scope of the following claims. [Explanation of symbols]

[0053] VBUS_A~VBUS_D active switch HVDC_A~HVDC_D active switch HVDC_min Minimum voltage HVDC_break Breakover voltage HVDC_max Maximum voltage Po_min Minimum power Po_boundary Boundary power Po_max Maximum power

Claims

1. 1. A multi-mode control method for controlling charging or discharging of a battery using an LLC resonant converter, comprising: When it is determined that the output current of the LLC resonant converter is a light load, controlling the LLC resonant converter to operate in a burst mode; When charging the battery, controlling the LLC resonant converter in the burst mode to operate in a PWM mode in response to an increase in the load on the LLC resonant converter or a rise in the output voltage, and further controlling the LLC resonant converter to operate in a PFM mode in response to a further increase in the load on the LLC resonant converter or a further rise in the output voltage; When discharging the battery, controlling the LLC resonant converter in the burst mode to operate in the PFM mode in response to an increase in the load of the LLC resonant converter or a decrease in the input voltage, and further controlling the LLC resonant converter to operate in the PSM mode in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage; In the PFM mode of the charge control to the battery, controlling the LLC resonant converter to operate in the PSM mode in response to a further increase in the load of the LLC resonant converter or a further increase in the output voltage, When controlling charging of the battery, the PSM mode operates at a constant duty cycle, a constant frequency and a varying phase shift; A multimode control method, characterized in that the frequency when operating in the PSM mode is lower than the frequency when operating in the PFM mode.

2. The input side of the LLC resonant converter is a DC bus side for supplying an input voltage, and the output side of the LLC resonant converter is a battery load side for supplying a wide range of output voltages; 2. The multi-mode control method according to claim 1, wherein the LLC resonant converter performs step-down charging control of the battery when the output voltage is lower than the input voltage, or performs step-up charging control of the battery when the output voltage is higher than the input voltage.

3. 2. The multi-mode control method of claim 1, wherein the burst mode operates at a constant duty cycle and a constant frequency.

4. When controlling charging of the battery, the PWM mode operates with a varying duty cycle and a constant frequency; 2. The multi-mode control method of claim 1, wherein the duty cycle when operating in the PWM mode is greater than the duty cycle when operating in the burst mode.

5. When controlling charging of the battery, the PFM mode operates at a constant duty cycle and a varying frequency; 2. The multi-mode control method according to claim 1, wherein the frequency when operating in the PFM mode is lower than the frequency when operating in the PWM mode.

6. 4. The multi-mode control method of claim 3, wherein when operating in the burst mode, the duty cycle is fixed at a minimum value and the frequency is fixed at a maximum frequency.

7. 5. The multi-mode control method of claim 4, wherein when operating in the PWM mode, the duty cycle varies between 50% and a minimum value and the frequency is fixed at a maximum frequency.

8. 6. The multi-mode control method of claim 5, wherein when operating in the PFM mode, the duty cycle is fixed at 50% and the frequency varies between a maximum frequency and a minimum frequency.

9. 7. The multi-mode control method of claim 6, wherein when operating in the PSM mode, the duty cycle is fixed at 50%, the frequency is fixed at a minimum frequency, and the phase shift varies between 0% and a maximum value.

10. 2. The multi-mode control method according to claim 1, wherein, during discharge control of the battery, the LLC resonant converter that was in the burst mode is controlled to operate in the PWM mode in response to a further increase in the load of the LLC resonant converter or a further decrease in the input voltage.

11. an input side of the LLC resonant converter is a battery load side for supplying a wide range of input voltages, and an output side of the LLC resonant converter is a DC bus side for supplying an output voltage; 2. The multi-mode control method according to claim 1, wherein the LLC resonant converter performs step-down discharge control of the battery when the input voltage is higher than the output voltage, and performs step-up discharge control of the battery when the input voltage is lower than the output voltage.

12. When controlling discharge to the battery, the PFM mode operates at a constant duty cycle and varying frequency; 2. The multi-mode control method of claim 1, wherein a duty cycle when operating in the PFM mode is greater than a duty cycle when operating in the burst mode, and a frequency when operating in the PFM mode is lower than a frequency when operating in the burst mode.

13. When controlling the discharge to the battery, the PSM mode operates at a constant duty cycle, a constant frequency, and a varying phase shift; 2. The multi-mode control method according to claim 1, wherein the frequency when operating in the PSM mode is lower than the frequency when operating in the PFM mode.

14. When controlling the discharge of the battery, the PWM mode operates with a varying duty cycle and a constant frequency; 11. The multi-mode control method of claim 10, wherein the duty cycle when operating in the PWM mode is greater than the duty cycle when operating in the burst mode.

15. 13. The multi-mode control method of claim 12, wherein when operating in the PFM mode, the duty cycle is fixed at 50% and the frequency varies between a maximum frequency and a minimum frequency.

16. 14. The multi-mode control method of claim 13, wherein when operating in the PSM mode, the duty cycle is fixed at 50%, the frequency is fixed at a minimum frequency, and the phase shift varies between 0% and a maximum value.

17. 15. The multi-mode control method of claim 14, wherein when operating in the PWM mode, the duty cycle varies between 50% and a minimum value and the frequency is fixed at a maximum frequency.

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