Energy conversion control method and system

Abstract

The invention provides an energy conversion control method and system, and relates to the technical field of power electronics. The energy conversion control method comprises the following steps: in response to a charging start signal, controlling an input current of a low-voltage side of the energy conversion device to be maintained within a first threshold range of a first current value so as to charge a high-voltage side energy storage device; when the voltage of the high-voltage side energy storage device reaches a first voltage, the input current is adjusted to be gradually increased; when the voltage of the high-voltage side energy storage device reaches a second voltage, controlling the input current to be maintained within a second threshold range of a target current value; and when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the input current to be reduced from the target current value to a second current value and to be maintained within a third threshold range of the second current value until the voltage of the high-voltage side energy storage device reaches a first target voltage value.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to an energy conversion control method and system. Background Technology

[0002] Figure 1 This is a circuit topology diagram of a commonly used automotive DC / DC converter module. For example... Figure 1 As shown, the bidirectional operation of the DC / DC converter can be used to enable the low-voltage battery of a new energy vehicle to reverse precharge the high-voltage bus capacitor. However, due to the requirement of short precharge time, the reverse working current of the DC / DC converter is relatively large, resulting in a large turn-off current of the low-voltage side MOSFET and high stress in the low-voltage side MOSFET. Current solutions are to add an additional active absorption circuit to improve the stress problem of the MOSFET. Summary of the Invention

[0003] In order to solve at least one of the above-mentioned problems in the prior art, embodiments of this application provide an energy conversion control method and system.

[0004] This application provides an energy conversion control method applied to an energy conversion system. The energy conversion system includes: a high-voltage side energy storage device, an energy conversion device, and a low-voltage side energy storage device, which are connected sequentially. The energy conversion device converts the electrical energy of the low-voltage side energy storage device into electrical energy that can charge the high-voltage side energy storage device. The energy conversion device includes: a transformer; an LC resonant series half-bridge circuit coupled to the high-voltage side winding of the transformer; and a full-bridge rectifier circuit coupled to the low-voltage side winding of the transformer. The energy conversion control method includes: responding to a charging start signal... The input current on the low-voltage side of the energy conversion device is controlled to remain within a first threshold range of a first current value to charge the high-voltage side energy storage device; when the voltage of the high-voltage side energy storage device reaches a first voltage, the input current is adjusted to gradually increase; when the voltage of the high-voltage side energy storage device reaches a second voltage, the input current is controlled to remain within a second threshold range of a target current value; when the voltage of the high-voltage side energy storage device reaches a third voltage, the input current is controlled to decrease from the target current value to the second current value and remain within a third threshold range of the second current value until the voltage of the high-voltage side energy storage device reaches the first target voltage value.

[0005] In some embodiments, the energy conversion control method further includes: after the voltage of the high-voltage side energy storage device reaches a first target voltage value, adjusting the input current of the low-voltage side based on the real-time voltage of the high-voltage side energy storage device and a second target voltage value, so that the voltage of the high-voltage side energy storage device reaches the second target voltage value.

[0006] In some embodiments, the input current is adjusted by controlling the switching on and off of the switching transistors in the full-bridge rectifier circuit; and / or, the input current is adjusted by controlling the switching on and off of the switching transistors in the full-bridge rectifier circuit and the switching transistors in the LC resonant series half-bridge structure circuit.

[0007] In some embodiments, controlling the input current on the low-voltage side of the energy conversion device to maintain within a first threshold range of a first current value in response to a charging start signal to charge the high-voltage side energy storage device includes: generating a first PWM signal and a second PWM signal having a first duty cycle and a first frequency in response to the charging start signal, such that the input current on the low-voltage side of the energy conversion device is maintained within the first threshold range of the first current value to charge the high-voltage side energy storage device, wherein the first PWM signal and the second PWM signal are used to drive the switching transistors in the full-bridge rectifier circuit.

[0008] In some embodiments, adjusting the input current to gradually increase when the voltage of the high-voltage side energy storage device reaches a first voltage includes: controlling the duty cycle of the first PWM signal and the second PWM signal to gradually increase from the first duty cycle to a second duty cycle, and controlling the frequency of the first PWM signal and the second PWM signal to gradually decrease from a first frequency to a second frequency when the voltage of the high-voltage side energy storage device reaches the first voltage.

[0009] In some embodiments, controlling the input current to remain within a second threshold range of the target current value when the voltage of the high-voltage side energy storage device reaches a second voltage includes: generating a third PWM signal and a fourth PWM signal when the voltage of the high-voltage side energy storage device reaches a second voltage, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge circuit so that the input current remains within the second threshold range of the target current value.

[0010] In some embodiments, the third PWM signal has a phase angle difference with the first PWM signal, and the fourth PWM signal has a phase angle difference with the second PWM signal, such that the switching transistor in the full-bridge rectifier circuit reaches a zero-current turn-off state when turned off.

[0011] In some embodiments, the step of generating a third PWM signal and a fourth PWM signal when the voltage of the high-voltage side energy storage device reaches a second voltage, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge circuit so that the input current is maintained within a second threshold range of the target current value, includes: adjusting the phase shift angle between the third PWM signal and the first PWM signal and the phase shift angle between the fourth PWM signal and the second PWM signal when the voltage of the high-voltage side energy storage device reaches a second voltage, generating the third PWM signal and the fourth PWM signal, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge circuit so that the input current is maintained within a second threshold range of the target current value.

[0012] In some embodiments, when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the input current to decrease from the target current value to a second current value and maintain it within a third threshold range of the second current value until the voltage of the high-voltage side energy storage device reaches a first target voltage value includes: when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the first PWM signal and the second PWM signal to drive the switching transistor in the full-bridge rectifier circuit, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge structure circuit on the high-voltage side, so that the input current decreases from the target current value to a second current value and maintains it within a third threshold range of the second current value.

[0013] In some embodiments, when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the first PWM signal and the second PWM signal to drive the switching transistors in the full-bridge rectifier circuit, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistors in the LC resonant series half-bridge structure circuit on the high-voltage side, includes: when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the frequencies of the first PWM signal and the second PWM signal to gradually increase; controlling the frequencies of the third PWM signal and the fourth PWM signal to gradually increase, the phase angle difference between the third PWM signal and the first PWM signal to gradually increase, and the phase angle difference between the fourth PWM signal and the second PWM signal to gradually increase.

[0014] This application provides an energy conversion system comprising: a high-voltage side energy storage device, an energy conversion device, a low-voltage side energy storage device, and a control device. The high-voltage side energy storage device, the energy conversion device, and the low-voltage side energy storage device are connected sequentially, and the control device is connected to the energy conversion device. The energy conversion device converts the electrical energy of the low-voltage side energy storage device into target electrical energy, which is used to charge the high-voltage side energy storage device. The energy conversion device includes: a transformer; an LC resonant series half-bridge circuit coupled to the high-voltage side winding of the transformer; and a full-bridge rectifier circuit coupled to the low-voltage side winding of the transformer. The control device is used to implement the energy conversion control method described in any of the above embodiments.

[0015] The energy conversion control method and system proposed in this application enable the energy conversion device to achieve efficient pre-charging without adding extra hardware components. This not only reduces the cost of the energy conversion device but also reduces the space and volume it occupies, improving integration. Furthermore, this method reduces the impact of large currents during charging, mitigating stress on the switching transistors during high-current charging, making the entire charging process more stable, and improving the reliability of reverse charging. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a circuit topology diagram of a commonly used vehicle-mounted DC / DC converter module.

[0018] Figure 2 This is a schematic diagram of the circuit topology of an energy conversion system provided in an embodiment of this application.

[0019] Figure 3 This is a schematic flowchart of an energy conversion control method provided in an embodiment of this application.

[0020] Figure 4 This is a comparative schematic diagram of the voltage control curve of the high-voltage side energy storage device and the control curve of the low-voltage side input current during the reverse pre-charging process provided in the embodiments of this application.

[0021] Figure 5 This is a schematic diagram of the state of the low-voltage side switching transistors S1 to S4 when they are under stress, as provided in the embodiments of this application.

[0022] Figure 6 This is a schematic diagram of the driving logic of the switching transistors at each stage of the reverse precharge process provided in an embodiment of this application.

[0023] Figure 7 This is a timing diagram of the electrical parameters of the high-voltage side and low-voltage side of the energy conversion device during the switching cycle of stage 2 provided in the embodiments of this application.

[0024] Figure 8 This is a schematic diagram of the switching process during the switching cycle of stage 2 provided in the embodiments of this application.

[0025] Figure 9 This is a schematic diagram of the ZCS switching state of the low-voltage side switch tube of the stage 3 energy conversion device provided in the embodiment of this application.

[0026] Figure 10 This is a timing diagram of the electrical parameters of the high-voltage side and low-voltage side of the energy conversion device during the switching cycle of stage 3 provided in the embodiments of this application.

[0027] Figure 11 This is a schematic diagram of the switching process during the switching cycle of stage 3 provided in the embodiments of this application.

[0028] Figure 12 This is a schematic diagram of the structure of an energy conversion system provided in an embodiment of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] The term "coupled (or connected)" as used throughout the entire specification (including the claims) may refer to any direct or indirect means of connection. For example, if the text describes a first device coupled (or connected) to a second device, it should be interpreted as the first device being directly connected to the second device, or the first device being indirectly connected to the second device through other devices or some means of connection. The terms "first," "second," etc., used throughout the entire specification (including the claims) are used to name components, and are not intended to limit the upper or lower limit of the number of components, nor to limit the order of components. Furthermore, wherever possible, components / components / steps using the same reference numerals in the drawings and embodiments represent the same or similar parts. Components / components / steps using the same reference numerals or the same terms in different embodiments may be referred to mutually in the relevant descriptions.

[0031] Figure 2 This is a schematic diagram of the circuit topology of an energy conversion system provided in an embodiment of this application. For example... Figure 2 As shown in the figure, the energy conversion system 100 provided in this application embodiment includes: a high-voltage side energy storage device (e.g., may include a capacitor C1), an energy conversion device, and a low-voltage side energy storage device (not shown in the figure, but may include a battery, a low-voltage battery, and / or a low-voltage energy storage capacitor). The high-voltage side energy storage device, the energy conversion device, and the low-voltage side energy storage device are connected in sequence. The energy conversion device converts the electrical energy of the low-voltage side energy storage device into electrical energy that can charge the high-voltage side energy storage device. The energy conversion device includes: a transformer TR; an LC resonant series half-bridge structure circuit 10 coupled to the high-voltage side winding of the transformer TR; and a full-bridge rectifier circuit 20 coupled to the low-voltage side winding of the transformer TR.

[0032] The energy conversion system 100 provided in this application embodiment does not require an additional active absorption circuit and can achieve a highly efficient pre-charge function. This not only reduces the cost of the energy conversion device but also decreases its space and volume, improving integration. Furthermore, the energy conversion system 100 can reduce the impact of large currents during charging, alleviate stress on the switching transistors during high-current charging, and make the entire charging process more stable, thereby improving the reliability of reverse charging. For details, please refer to the description of the following method embodiments.

[0033] like Figure 2 As shown, in some embodiments, the LC resonant series half-bridge structure circuit 10 includes an LC resonant circuit 11 and a series half-bridge structure circuit 12; wherein, the first end of the LC resonant circuit 11 is coupled to the first end of the series half-bridge structure circuit 12, and the second end of the LC resonant circuit 11 is coupled to the high-voltage side winding of the transformer TR; the second end of the series half-bridge structure circuit 12 is coupled to the high-voltage side energy storage device (capacitor C1).

[0034] like Figure 2 As shown, in some embodiments, the series half-bridge structure circuit 12 includes: a switching bridge arm, including a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4 connected in series; and a capacitor bridge arm, including a first capacitor C2 and a second capacitor C3 connected in series; wherein, the two ends of the capacitor bridge arm are respectively connected to the two ends of the switching bridge arm, and the midpoint between the first capacitor C2 and the second capacitor C3 is coupled to the midpoint between the second switching transistor Q2 and the third switching transistor Q3, and the two ends of the capacitor bridge arm are also coupled in parallel to the two ends of capacitor C1.

[0035] like Figure 2As shown, in some embodiments, the LC resonant circuit 11 includes a resonant inductor Lr and a resonant capacitor Crp; wherein, the first end of the resonant capacitor Crp is coupled to the midpoint a between the first switch Q1 and the second switch Q2, the other end of the resonant capacitor Crp is coupled to the first end of the resonant inductor Lr, and the second end of the resonant capacitor Crp is coupled to the first end of the high-voltage winding of the transformer TR; the midpoint b between the third switch Q3 and the fourth switch Q4 is coupled to the second end of the high-voltage winding.

[0036] like Figure 2 As shown, in some embodiments, the input terminal of the full-bridge rectifier circuit 20 is coupled to the low-voltage side energy storage device, and the output terminal of the full-bridge rectifier circuit 20 is coupled to the low-voltage side winding of the transformer TR.

[0037] For example, such as Figure 2 As shown, in some embodiments, the full-bridge rectifier circuit 20 includes a fifth switch S1, a sixth switch S2, a seventh switch S3, and an eighth switch S4; the midpoint c between the fifth switch S1 and the sixth switch S2 is coupled to the first end of the low-voltage winding of the transformer TR, the midpoint d between the seventh switch S3 and the eighth switch S4 is coupled to the second end of the low-voltage winding of the transformer TR, the midpoint between the fifth switch S1 and the seventh switch S3 is coupled to the first end of the low-voltage energy storage device, and the midpoint between the sixth switch S2 and the eighth switch S4 is coupled to the second end of the low-voltage energy storage device.

[0038] like Figure 2 As shown, in some embodiments, the energy conversion device further includes: a filter capacitor C O Filter capacitor C O It is connected in parallel to the input terminal of the full-bridge rectifier circuit 20. Filter capacitor C O Used for energy storage and filtering.

[0039] like Figure 2 As shown, in some embodiments, the high-voltage side energy storage device includes the bus capacitor (capacitor C1) of the high-voltage battery of the new energy vehicle, and the low-voltage side energy storage device includes the low-voltage battery of the new energy vehicle. Specifically, the energy conversion system 100 can be applied to a new energy vehicle, specifically for pre-charging the high-voltage bus capacitor at the high-voltage battery end of the new energy vehicle.

[0040] It should be understood that the above description is merely one embodiment of the energy conversion device provided in this application and is not intended to limit the specific structure of the energy conversion device. For those skilled in the art, the energy conversion device can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made to the energy conversion device within the spirit and principles of this application should be considered as the energy conversion device proposed in this application. For example, the switching transistors on the high-voltage and low-voltage sides can be MOSFETs or other types of switching transistors such as insulated-gate transistors (IGBTs), and the capacitor CRP can be placed on the circuit connecting the transformer TR and point b, etc.

[0041] Figure 3 This is a schematic flowchart of an energy conversion control method provided in one embodiment of this application. The energy conversion control method provided in this application can be applied to the energy conversion system described in any of the above embodiments. Figure 3 As shown in the embodiments of this application, the energy conversion control method includes:

[0042] S101. In response to the charging start signal, control the input current on the low-voltage side of the energy conversion device to maintain within a first threshold range of the first current value, so as to charge the high-voltage side energy storage device.

[0043] S102. When the voltage of the high-voltage side energy storage device reaches the first voltage, adjust the input current to gradually increase it;

[0044] S103. When the voltage of the high-voltage side energy storage device reaches the second voltage, control the input current to be maintained within the second threshold range of the target current value.

[0045] S104. When the voltage of the high-voltage side energy storage device reaches the third voltage, control the input current to decrease from the target current value to the second current value and maintain it within the third threshold range of the second current value until the voltage of the high-voltage side energy storage device reaches the first target voltage value.

[0046] Specifically, the above-mentioned energy conversion control method is a method for controlling the power transmission from the low-voltage side to the high-voltage side of the energy conversion device. For example, it can be a reverse pre-charge control method for an on-board DC / DC converter module with bidirectional power transmission function. The following uses the reverse pre-charge control method of the on-board DC / DC converter module as an example to describe in detail the energy conversion control method provided in this embodiment:

[0047] The input current Iin on the low-voltage side of the energy conversion device and the voltage V of the high-voltage side energy storage device (high-voltage bus capacitor) C1 connected to the high-voltage side are... HVAs a control variable for the reverse pre-charge process, the input current Iin on the low-voltage side of the sampled energy conversion device is used. By controlling the magnitude of Iin, the output power during reverse pre-charge can be controlled. Figure 4 This is a comparative schematic diagram of the voltage control curve of the high-voltage side energy storage device and the control curve of the low-voltage side input current during the reverse pre-charging process provided in the embodiments of this application. Figure 4 The black line in the middle represents the voltage V of the high-voltage side energy storage device. HV The rising curve, Vset is the target pre-charge voltage, starting from 0 and passing through V1, V2, V3, and finally reaching the target voltage Vset; the gray curve is the reference curve (also known as the ideal curve) of Iin current. The control method provided in this application embodiment is to make the actual Iin current and the reference consistent during the reverse pre-charge process.

[0048] See Figure 4 The charging process of the high-voltage side energy storage device can be divided into four stages:

[0049] t0-t1: Stage 1, the low-voltage side input current Iin of the energy conversion device is controlled to be near a very small current value I1 (within the first threshold range of the first current value). During this process, the high-voltage side energy storage device on the high-voltage side of the energy conversion device is simultaneously charged, and the voltage V of the high-voltage side energy storage device is... HV It starts from 0 and slowly rises;

[0050] Specifically, to reduce the impact on electronic devices during power-on, a small current (i.e., the first current value I1, which can be 10% to 20% of the target current value Iref_set, such as 10%, 12%, 15%, 18%, or 20% of the target current value Iref_set; the first current value I1 can also be other current values ​​set according to actual conditions, this is just an example and no further restrictions are imposed) is used for pre-charging. At this time, the switching frequency of the low-voltage side MOS (S1-S4) in the full-bridge rectifier circuit of the energy conversion device is set to a high frequency (the switching frequency of the low-voltage side MOS (S1-S4) can be 300kHz, 350kHz, 400kHz, 500kHz, 340kHz, 370kHz, 280kHz, 290kHz, 289kHz, 250kHz, 480kHz, etc., this switching frequency can be other frequencies set according to actual conditions). The frequency set for the situation (this is just an example and not subject to excessive restrictions) is used to adjust the duty cycle of the low-voltage side MOS (S1-S4) in the full-bridge rectifier circuit of the energy conversion device to a small pulse width duty cycle (the duty cycle of the low-voltage side MOS (S1-S4) can be 10%, 8%, 9%, 7%, 5%, 11%, 12%, 15%, 18%, 20%, 30%, etc., and this duty cycle can be other values ​​set according to the actual situation; this is just an example and not subject to excessive restrictions). This is mainly to control the current overshoot at the moment of power-on. The duration can be set (the duration of stage 1 can be 10ms, 5ms, 3ms, 12ms, 15ms, 18ms, 20ms, 30ms, etc., and can be other durations set according to the actual situation; this is just an example and not subject to excessive restrictions). At this time, the high-voltage side MOS (Q1-Q4) in the LC resonant series half-bridge structure circuit is not driven. At time t1, the high-voltage side voltage will be pushed to the V1 value. During this stage, the Iin current is very small, and there is no stress problem for the low-voltage side MOS.

[0051] t1-t2: Stage 2, voltage V of the high-voltage side energy storage device HV The voltage has risen to V1 (first voltage), and the low-voltage side input current Iin of the control energy conversion device gradually increases. During this process, the high-voltage side energy storage device continues to be charged, and the high-voltage side voltage V... HV It continues to rise slowly from V1;

[0052] Specifically, once the high-voltage side bus capacitor reaches a certain voltage V1 (i.e., the first voltage value, such as 5% Vset), the input current Iin on the low-voltage side needs to be gradually increased. The duty cycle of the low-voltage side MOS (S1-S4) can then be gradually increased from the small pulse width duty cycle of stage 1 to 50%. Then, frequency modulation of the low-voltage side MOS (S1-S4) begins, gradually decreasing the switching frequency to the lowest frequency f1 to increase the high-voltage side output voltage and power. At this time, the high-voltage side MOS (Q1-Q4) is still not driven. f1 is a specified value, usually f1 > fr (fr is the resonant frequency of the resonant network composed of Lr, Crp, and Crs), for example, f1 = 1.2fr, f1 = 1.3fr, f1 = 1.1fr, f1 = 1.4fr, f1 = 1.5fr, etc. f1 can be other frequencies set according to actual conditions; this is just an example and no further restrictions are imposed. At time t2, the high-voltage side voltage will be pushed to the V2 value. In stage 2, Iin is controlled to increase slowly, and there is no stress problem for the low-voltage side MOS at this time.

[0053] t2-t3: Stage 3, voltage V of the high-voltage side energy storage device HV The voltage has risen to V2 (second voltage), and the low-voltage side input current Iin of the energy conversion device has increased to near the set value Iref_set (target current value), and continues to operate stably near the set value Iref_set (within the second threshold range of the target current value);

[0054] Specifically, when the control detects that the high-voltage side output voltage reaches V2, in order to further increase the low-voltage side input current Iin and improve the high-voltage side output voltage and power, the high-voltage side MOS (Q1-Q4) is driven, and the phase shift angle DΦ of the high-voltage and low-voltage side drives is adjusted to increase the high-voltage side output voltage, so that the low-voltage side current reaches the set value (i.e., the target current value Iref_set, which can be 10A~100A, for example, 10A, 20A, 40A, 50A, 80A, 100A, etc. The target current value can also be other current values ​​set according to the actual situation; this is just an example and no further restrictions are imposed). At this time, the gain can be increased by adjusting the phase shift angle DΦ in a closed loop to improve the high-voltage side output voltage. At the same time, the switching frequency of the high-voltage side MOS (Q1-Q4) can also be adjusted in an open loop to optimize the operating state.

[0055] In stage 3, since Iin has been modulated to its maximum value, the low-voltage side MOS (S1-S4) is prone to stress problems. By adjusting the phase shift angle DΦ of the high- and low-voltage side MOS drivers, the low-voltage side MOS (S1-S4) can achieve a ZCS turn-off state (i.e., an approximate zero-current turn-off state). This makes the current flowing through S1 / S4 negative when it is turned off (at time t3), and the current flowing through S2 / S3 negative when it is turned off (at time t6), and the negative current is small. This is a ZCS turn-off state (approximate zero-current turn-off state), which can significantly reduce the voltage stress of the MOS when it is turned off (compared to the voltage stress of the MOS when it is turned off when the current is positive).

[0056] t3-t4: Phase 4, V HV The voltage has risen to V3 (the third voltage). The current Iin is actively reduced to a smaller current value I2 (the second current value) near the third threshold range of the second current value to prevent the high-voltage output voltage V from the energy conversion device from increasing. HV Overshoot.

[0057] Specifically, in stage 4, the high-voltage side output voltage is approaching the set voltage value. To prevent high-voltage side output voltage overshoot, the low-voltage side current reference (I2, i.e., the second current value, which can be 30% to 50% of the target current value Iref_set, such as 30%, 35%, 40%, 45%, or 50% of the target current value Iref_set, etc.) is actively reduced at V3 (while still maintaining a certain margin from the set voltage). This reduces the high-voltage side charging current and effectively prevents voltage overshoot. During this stage, the input current Iin decreases significantly, and the low-voltage side MOS experiences no stress issues. Typically, the V3 voltage is slightly lower than the pre-charge target voltage (e.g., 50V, 51V, 52V, 55V, 60V, 48V, 49V, 45V, etc.). The third voltage can be other values ​​set according to actual conditions; this is just an example without excessive restrictions.

[0058] The first threshold range of the first current value refers to the range of current fluctuations caused by control accuracy, measurement errors, noise, etc., when the first current value is used as the control target of the input current Iin in stage 1. This fluctuation is a reasonable range that can be understood by those skilled in the art and does not affect the effect of the invention. For example, the first threshold range of the first current value is within ±1%, ±5%, or ±10% of the first current value. The second threshold range of the target current value and the third threshold range of the second current value are similar and will not be described again here.

[0059] Figure 4 In the diagram, Iin represents the input current on the low-voltage side, VHV Iin represents the voltage of the high-voltage side energy storage device, I1 represents the initial current at the start of charging, which is usually relatively small, and Iref_set is the set target current value, which is relatively large and can speed up the pre-charging speed. The voltage from I1 to Ire_set needs to go through a slow increase phase (t1 to t2). When the voltage of the high-voltage side energy storage device approaches Vset, that is, after reaching V3, Iin is actively reduced to I2 (in order to prevent the charging current from being too large and causing the output voltage to overshoot). When the voltage of the high-voltage side energy storage device reaches Vset, it means that the reverse pre-charging is over.

[0060] As can be seen, the energy conversion control method provided in this application embodiment enables the energy conversion device to achieve efficient pre-charging function without adding additional hardware components. This not only reduces the cost of the energy conversion device but also reduces the space and volume it occupies, improving integration. Furthermore, this method reduces the impact of large currents during charging, alleviates the stress problem of the switching transistor during high-current charging, makes the entire charging process more stable, and improves the reliability of reverse charging.

[0061] In some embodiments, the method further includes: after the voltage of the high-voltage side energy storage device reaches a first target voltage value, adjusting the input current of the low-voltage side based on the real-time voltage of the high-voltage side energy storage device and a second target voltage value, so that the voltage of the high-voltage side energy storage device reaches the second target voltage value.

[0062] Specifically, the second target voltage value can be the same as or different from the first target voltage value. For example, when the second target voltage value is the same as the first target voltage value... Figure 4 As shown, when the voltage of the high-voltage side energy storage device reaches Vset, it means that the reverse pre-charge is over. However, in order to maintain the voltage of the high-voltage side energy storage device at Vset, the input current Iin on the low-voltage side can be reduced to a very small current value.

[0063] In some embodiments, the input current on the low-voltage side is adjusted by controlling the on and off states of the switching transistors in the full-bridge rectifier circuit on the low-voltage side; and / or the input current on the low-voltage side is adjusted by controlling the on and off states of the switching transistors in the full-bridge rectifier circuit on the low-voltage side and the switching transistors in the series half-bridge circuit on the high-voltage side.

[0064] Specifically, controlling the on and off of the switching transistors includes controlling parameters such as the switching frequency, duty cycle, phase shift angle, dead time, on-time sequence, modulation method, and / or switching timing of each switching transistor. By controlling the on and off of the switching transistors on the low-voltage side, or by controlling the on and off of the switching transistors on both the low-voltage and high-voltage sides, the input current on the low-voltage side can be adjusted.

[0065] In some embodiments, step S101 may specifically include: in response to the charging start signal, generating a first PWM signal and a second PWM signal having a first duty cycle and a first frequency, such that the input current on the low-voltage side of the energy conversion device is maintained within a first threshold range of the first current value to charge the high-voltage side energy storage device, wherein the first PWM signal and the second PWM signal are used to drive the switching transistor in the full-bridge rectifier circuit.

[0066] For details, see Figure 4 In stage 1 (t0-t1), at time t0, the high-voltage side bus capacitor C1 is de-energized, similar to a short circuit. To reduce the impact at power-on, only a small current (e.g., 1A) is used for pre-charging at the beginning of the charging phase. During this time, the frequency of the drive signals (first PWM signal and second PWM signal) of the low-voltage side switches S1 to S4 is set to a high frequency (first frequency, e.g., 300kHz), and the duty cycle is set to a small duty cycle (first duty cycle, e.g., 10%). This controls the current overshoot at power-on. The duration of this stage can be set (e.g., 10ms). During this stage, the high-voltage side switches Q1 to Q4 are not driven. By time t1, the voltage of the high-voltage side bus capacitor C1 will be charged to the value V1. During this stage, the Iin current is very small, and there is no stress issue for the low-voltage side switches.

[0067] In some embodiments, in step S101 above, there is a 180-degree phase difference between the first PWM signal and the second PWM signal; wherein, the first PWM signal drives two switches of the full-bridge rectifier circuit to turn on and off; and the second PWM signal drives the other two switches of the full-bridge rectifier circuit to turn on and off.

[0068] For details, see Figure 2 The full-bridge rectifier circuit on the low-voltage side includes switching transistors S1, S2, S3, and S4; see [link / reference]. Figure 6 In stage 1, the first PWM signal drives the switching transistors S1 and S4 to turn on and off, and the second PWM signal drives the switching transistors S2 and S3 to turn on and off. Switches S1 and S4 alternately turn on and off with switches S2 and S3.

[0069] In some embodiments, step S102 may specifically include: when the voltage of the high-voltage side energy storage device reaches the first voltage, controlling the duty cycle of the first PWM signal and the second PWM signal to gradually increase from the first duty cycle to the second duty cycle, and controlling the frequency of the first PWM signal and the second PWM signal to gradually decrease from the first frequency to the second frequency.

[0070] It should be understood that the first PWM signal and the second PWM signal used in step S102 are inherited from step S101. In other words, the first PWM signal and the second PWM signal used in the initial stage of step S102 are the same as the first PWM signal and the second PWM signal used in the final stage of step S101.

[0071] See Figure 4 In stage 2 (t1-t2), after the high-voltage side bus capacitor C1 has a certain voltage V1 (the first voltage, for example, 5% Vset), it is necessary to gradually increase the input current Iin on the low-voltage side. At this time, the duty cycle of the drive signals (i.e., the first PWM signal and the second PWM signal) of the low-voltage side switching transistors S1 to S4 can be gradually increased to the second duty cycle (for example, 50%). Then, the frequency of the first PWM signal and the second PWM signal is adjusted from the first frequency to the second frequency f1 to increase the output voltage and power of the high-voltage side of the energy conversion device. At this time, the high-voltage side switching transistors Q1 to Q4 are still not driven. The adjusted first PWM signal and second PWM signal in stage 2 are shown in [reference]. Figure 6 The second frequency f1 can be specified, and is usually f1 > fr (fr is the resonant frequency of the resonant network composed of the inductor Lr and capacitor Crp of the energy conversion device, see [reference]). Figure 2 For example, f1 = 1.2fr. At time t2, the voltage V... HV It will be pushed up to the V2 value. During this stage, Iin is controlled to increase slowly, and there are no stress issues with the low-voltage side switching transistor. Figure 7 This is a timing diagram of the electrical parameters on the high-voltage and low-voltage sides during the Phase 2 switching cycle, where I Lr Let I_ represent the current in inductor Lr, Vab represent the voltage between points a and b, and I_ S1 / S4 I_ represents the current of switching transistors S1 / S4. S2 / S3 I_ represents the current in switching transistors S2 / S3. Q1 / Q4 I_ represents the current of switching transistors Q1 / Q4. Q2 / Q3 This indicates the current of switching transistors Q2 / Q3. Figure 8 This is a schematic diagram of the switching process during the second phase of the switching cycle. The dashed lines represent the closed switches, and the solid lines represent the open switches.

[0072] In some embodiments, step S103 may specifically include: when the voltage of the high-voltage side energy storage device reaches the second voltage, generating a third PWM signal and a fourth PWM signal, controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge structure circuit, so that the input current is maintained within the second threshold range of the target current value.

[0073] It should be understood that the first PWM signal and the second PWM signal used in step S103 are inherited from step S102. In other words, the first PWM signal and the second PWM signal used in the initial stage of step S103 are the same as the first PWM signal and the second PWM signal used in the final stage of step S102.

[0074] See Figure 4 In stage 3 (t2-t3), after the voltage of the high-voltage side energy storage device is detected to reach the second voltage V2, in order to further increase the high-voltage side output voltage of the energy conversion device, see [link to relevant documentation]. Figure 6 At this point, the high-voltage side switching transistors Q1 to Q4 are driven.

[0075] Specifically, the gain can be increased by adjusting the phase angle difference, or phase shift angle DΦ, between the high-voltage side switch drive signal and the low-voltage side switch drive signal of the energy conversion device, thereby increasing the high-voltage side output voltage of the energy conversion device. For example, the phase angle difference between the first PWM signal and the third PWM signal, and the phase angle difference between the second PWM signal and the fourth PWM signal can be adjusted synchronously.

[0076] The formula for calculating the phase shift angle DΦ is ​​as follows:

[0077]

[0078] In the formula, M is the bias constant and K is the modulation coefficient.

[0079] As the high-voltage side voltage of the energy conversion device increases, the required phase shift angle DΦ also needs to increase. Since the low-voltage side of the energy conversion device maintains a constant target current, the low-voltage side voltage is also constant. Therefore, the system maintains a constant power to charge the high-voltage side capacitor. As the high-voltage side voltage increases, the high-voltage side charging current decreases, so the system's switching frequency fs also needs to be gradually increased.

[0080] In some embodiments, the third PWM signal and the fourth PWM signal have the same duty cycle and frequency, and there is a 180-degree phase difference between the third PWM signal and the fourth PWM signal; the third PWM signal drives the two switching transistors in the LC series half-bridge structure circuit to turn on and off; the fourth PWM signal drives the other two switching transistors in the LC series half-bridge structure circuit to turn on and off.

[0081] For details, see Figure 3 The LC-type series half-bridge circuit includes switching transistors Q1 to Q4; see [link / reference] Figure 6In stage 3, the third PWM signal drives the switching transistors Q1 and Q4 to turn on and off, and the fourth PWM signal drives the switching transistors Q2 and Q3 to turn on and off. Switches Q1 and Q4 alternately turn on and off with switches Q2 and Q3.

[0082] In some embodiments, during stage 3, the duty cycle and frequency of the third PWM signal and the fourth PWM signal are consistent with the duty cycle and frequency of the first PWM signal / second PWM signal. Specifically, since the duty cycle and frequency of the first PWM signal and the second PWM signal are consistent, the duty cycles and frequencies of the first to fourth PWM signals are all consistent.

[0083] In some embodiments, in stage 3, there is a phase angle difference between the third PWM signal and the sub-PWM signal, and the phase angle difference between the fourth PWM signal and the second PWM signal, so that the switching transistor in the full-bridge rectifier circuit can achieve a zero-current turn-off state when turned off.

[0084] For details, see Figure 4 In stage 3 (t2-t3), since Iin has been modulated to its maximum value during the charging process, stress problems are typically generated in the low-voltage side switching transistors S1 to S4 of the energy conversion device: such as Figure 5 As shown, since lead inductance is common in circuits, when a large current flows through the MOSFET and it is turned off, the energy on the lead inductance will be relatively high. This energy will continue to charge the junction capacitance (Cs1) of the MOSFET after it is turned off, thereby increasing the stress Vds of the MOSFET.

[0085] Therefore, at this stage, see Figure 9 By adjusting the phase shift angle DΦ between the high-voltage and low-voltage side switching transistor drive signals of the energy conversion device, the current flowing through switching transistors S1 / S4 when they are turned off is negative (at time t23), and the current flowing through switching transistors S2 / S3 when they are turned off is negative (at time t26). Moreover, the negative current is small, achieving the ZCS turn-off state (approximately zero current turn-off state). Compared with the voltage stress when the switching transistors are turned off when the current is positive, the voltage stress when the switching transistors are turned off is significantly reduced. Figure 10 This is a timing diagram of the electrical parameters of the high-voltage and low-voltage sides of the energy conversion device during the switching cycle of stage 3. Figure 11 This is a schematic diagram of the switching of the energy conversion device during the switching cycle of stage 3. In this diagram, the switch tubes represented by dashed lines are closed switches, and the switch tubes represented by solid lines are open switches.

[0086] In some embodiments, step S103 specifically includes: when the voltage of the high-voltage side energy storage device reaches the second voltage, generating a third PWM signal and a fourth PWM signal, adjusting the phase shift angle between the third PWM signal and the first PWM signal and the phase shift angle between the fourth PWM signal and the second PWM signal, so that the input current is maintained within the second threshold range of the target current value, and the third PWM signal and the fourth PWM signal are used to drive the switching transistor in the LC resonant series half-bridge structure circuit.

[0087] For details, see Figure 6 In order to keep the capacitor on the high-voltage side of the energy conversion device charging at a constant power in stage 3, and as the voltage of the high-voltage side energy storage device increases, the charging current on the high-voltage side of the energy conversion device needs to decrease. Therefore, the phase angle difference between the control signals on the high-voltage side and the low-voltage side of the energy conversion device (the phase shift angle between the third PWM signal and the first PWM signal and the phase shift angle between the fourth PWM signal and the second PWM signal) needs to increase, and the switching frequency of the system needs to increase.

[0088] In some embodiments, step S104 may specifically include: when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the first PWM signal and the second PWM signal to drive the switching transistor in the full-bridge rectifier circuit, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistor in the LC resonant series half-bridge structure circuit on the high-voltage side, so that the input current decreases from the target current value to the second current value and is maintained within the third threshold range of the second current value.

[0089] It should be understood that the first to fourth PWM signals used in step S104 are inherited from step S103. In other words, the first to fourth PWM signals used in the initial stage of step S104 are the same as the first to fourth PWM signals used in the final stage of step S103.

[0090] In some embodiments, step S104 may specifically include: when the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the frequency of the first PWM signal and the second PWM signal to gradually increase; controlling the frequency of the third PWM signal and the fourth PWM signal to gradually increase, the phase angle difference between the third PWM signal and the first PWM signal to gradually increase, and the phase angle difference between the fourth PWM signal and the second PWM signal to gradually increase.

[0091] For details, see Figure 4 Stage 4 (t3-t4), at this time the voltage V HVThe voltage is approaching the pre-charge target voltage Vset. To prevent output voltage overshoot, the low-voltage side input current Iin of the energy conversion device is actively reduced to a smaller value I2 at a voltage V3 that still maintains a certain margin from the pre-charge target voltage Vset. This reduces the high-voltage side charging current and effectively prevents voltage overshoot. During this stage, the Iin current decreases significantly, and there are no stress issues with the low-voltage side switching transistor. Typically, voltage V3 is slightly lower than the pre-charge target voltage Vset (e.g., 50V). For details, see [link to documentation]. Figure 6 In stage 4, the gain can be increased by further adjusting the phase angle difference (i.e., the phase shift angle DΦ) between the high-voltage side switch drive signal and the low-voltage side switch drive signal, thereby increasing the high-voltage side output voltage of the energy conversion device. For example, the phase angle difference between the first and third PWM signals, and the phase angle difference between the second and fourth PWM signals can be adjusted synchronously. Simultaneously, the system's switching frequency fs also needs to be gradually increased to reduce the low-voltage side input current Iin and charging power of the energy conversion device.

[0092] See Figure 4 In some embodiments, after stage 4 (after t4), that is, after the voltage V of the high-voltage side energy storage device... HV After reaching the first target voltage value Vset, in order to maintain the voltage of the high-voltage side energy storage device at Vset, the input current Iin on the low-voltage side of the energy conversion device can be reduced to a very small current value. The control logic at this stage can be as follows: See Figure 12 When the voltage V HV After reaching the first target voltage value Vset (after t4), the voltage control loop takes over. The high-voltage side HV voltage sampling signal Vsen_HV (a signal reduced from the current voltage of the high-voltage side energy storage device, which can be regarded as the current voltage of the high-voltage side energy storage device) and the voltage reference value Vref_HV (a signal reduced from the first target voltage value Vset, which can be regarded as the first target voltage value Vset) enter the voltage control loop to obtain the output signal VAO. Iref_set is the set current value. The smaller of the two signals VAO output by the voltage control loop and the set current value Iref_set is taken. The module (smaller output) receives an output signal Iref (smaller value), which serves as the reference for the current control loop. This signal, along with the low-voltage side input current sampling signal Isen_LV, enters the current control loop, resulting in an output signal CAO. The CAO signal and the high-voltage side sampling signal Vsen_HV serve as the input signals for the PWM control module. The control unit determines the final switching frequency fs and the phase shift angle DΦ between the high-voltage and low-voltage side drive signals of the energy conversion device to reduce the low-voltage side input current Iin of the energy conversion device, thereby maintaining the voltage of the high-voltage side energy storage device at the first target voltage value Vset. For example, the control unit can lower the phase shift angle DΦ and / or increase the switching frequency fs of the switching transistor.

[0093] For example, in one specific embodiment of this application, such as Figure 12 As shown, the method may further include:

[0094] The data acquisition device 30, coupled to the capacitor C1 and the full-bridge rectifier circuit 20, is configured to acquire in real time the input current Iin of the full-bridge rectifier circuit 20 and the voltage V of the capacitor C1. HV Based on the input current Iin of the full-bridge rectifier circuit 20 and the voltage V of capacitor C1 HV This generates the sampled current value Isen_LV and the sampled voltage value Vsen_HV;

[0095] The control device 40 (specifically, a processor) is coupled to the acquisition device 30, the LC resonant series half-bridge circuit 10, and the full-bridge rectifier circuit 20, and is configured to generate drive signals for the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20 based on the sampled current value Isen_LV and the sampled voltage value Vsen_HV.

[0096] The driving device 50, coupled to the control device 40, the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20, is configured to drive the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20 to turn on and off based on the driving signal, so that the low-voltage side energy storage device charges the capacitor C1 with the target current.

[0097] like Figure 12 As shown, in some embodiments, the control device 40 includes:

[0098] The voltage control loop module 41, coupled to the acquisition device 30, is configured to generate a first output signal VAO based on the sampled voltage value Vsen_HV and the voltage reference value Vref_HV after the voltage of capacitor C1 reaches the target voltage value Vset. The function of the voltage control loop module 41 is to maintain the output voltage of the energy conversion device within the set value, which is usually achieved through proportional-integral control.

[0099] Small unit 42 is coupled to the voltage control loop module 41 and is configured to compare the first output signal VAO and the set current value Iref_set to obtain the smaller value Iref between the first output signal VAO and the set current value Iref_set.

[0100] The current control loop module 43, coupled to the smaller sampling unit 41 and the acquisition device 30, is configured to generate a second output signal CAO based on the smaller value Iref and the sampled current value Isen_LV. The function of the current control loop module 43 is to maintain the input current of the energy conversion device within a set value, which is usually achieved through proportional-integral control.

[0101] Control unit 44, coupled to the acquisition device 30, the current control loop module 43, the LC resonant series half-bridge circuit 10, the full-bridge rectifier circuit 20, and the drive device 50, is configured as follows:

[0102] The voltage V across capacitor C1 HV Before the target voltage value Vset is reached, based on the sampled voltage value Vsen_HV, drive signals are generated for the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20, so that the drive device 50 drives the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20 to turn on and off based on the drive signals, thereby enabling the low-voltage side energy storage device to charge the capacitor C1 with the target current;

[0103] The voltage V across capacitor C1 HV After reaching the target voltage value Vset, based on the sampled voltage value Vsen_HV and the second output signal CAO, drive signals are generated for the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20. This causes the drive device 50 to drive the switching transistors in the LC resonant series half-bridge circuit 10 and the full-bridge rectifier circuit 20 to turn on and off based on the drive signals, thereby increasing the voltage V of capacitor C1. HV Maintain at the target voltage value Vset.

[0104] like Figure 12 As shown, in some embodiments, the acquisition device 30 may specifically include:

[0105] High-voltage side voltage sampling unit 31 is coupled to the control unit 44 and capacitor C1, and is used to collect the voltage V of capacitor C1. HV And based on the voltage V of capacitor C1 HV Generate the sampled voltage value Vsen_HV;

[0106] The resonant current sampling unit 32 is coupled to the LC resonant circuit 11 and the control unit 44, and is used to collect the resonant current.

[0107] The low-voltage side current sampling unit 33 is coupled to the full-bridge rectifier circuit 20 and the control unit 44, and is used to collect the input current Iin of the full-bridge rectifier circuit 20 and generate a sampling current value Isen_LV based on the input current Iin;

[0108] The low-voltage side voltage sampling unit 34 is coupled to the full-bridge rectifier circuit 20 and the control unit 44, and is used to acquire the input voltage V on the low-voltage side. LV And based on the input voltage V LV Generate the low-voltage side sampling voltage Vsen_LV.

[0109] like Figure 12 As shown, in some embodiments, the driving signal includes a first PWM signal, a second PWM signal, a third PWM signal, and a fourth PWM signal; the driving device 50 includes:

[0110] The first driving unit 51 is coupled to the control unit 44 and the LC resonant series half-bridge structure circuit 10 respectively. It is configured to drive the two switching transistors in the LC resonant series half-bridge structure circuit 10 to turn on and off based on the third PWM signal, and to drive the other two switching transistors in the LC resonant series half-bridge structure circuit 10 to turn on and off based on the fourth PWM signal.

[0111] The second driving unit 52 is coupled to the control unit 44 and the full-bridge rectifier circuit 20 respectively, and is configured to drive the two switching transistors in the full-bridge rectifier circuit 20 to turn on and off based on the first PWM signal, and to drive the other two switching transistors in the full-bridge rectifier circuit 20 to turn on and off based on the second PWM signal.

[0112] like Figure 12 As shown, when the energy conversion device transmits power in the forward direction, that is, when transmitting power from the high-voltage side to the low-voltage side, the voltage at points a and b can be obtained by modulating the driving of the first switch Q1 to the fourth switch Q4. HV V HV / 2 The energy conversion device transmits power in reverse, that is, from the low-voltage side to the high-voltage side. The first switch Q1 and the fourth switch Q4 on the high-voltage side are driven simultaneously, and the second switch Q2 and the third switch Q3 are driven simultaneously. Points a and b only have voltage V. HVThe circuit operates at two voltage levels: 0 and 1. A resonant network composed of resonant inductor Lr and resonant capacitor Crp keeps the circuit in a resonant state. Transformer TR provides isolation and voltage transformation. The capacitor C1 connected to the high-voltage side can be the high-voltage bus capacitor from the high-voltage battery side. By modulating the driving of the fifth to eighth switches S1 to S4 on the low-voltage side and the first to fourth switches Q1 to Q4 on the high-voltage side, power can be transferred from the low-voltage side to the high-voltage side, charging the bus capacitor C1 to the set voltage, thus achieving the reverse pre-charge function.

[0113] This embodiment also discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by a computer, the computer can perform the methods provided in the above-described method embodiments.

[0114] This embodiment also provides a computer-readable storage medium storing a computer program that causes the computer to perform the methods provided in the above-described method embodiments.

[0115] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0116] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0117] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0118] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0119] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0120] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An energy conversion control method, characterized in that, This invention relates to an energy conversion system comprising: a high-voltage side energy storage device, an energy conversion device, and a low-voltage side energy storage device, which are connected sequentially. The energy conversion device converts the electrical energy of the low-voltage side energy storage device into electrical energy that can charge the high-voltage side energy storage device. The energy conversion device includes: a transformer; an LC resonant series half-bridge circuit coupled to the high-voltage side winding of the transformer; and a full-bridge rectifier circuit coupled to the low-voltage side winding of the transformer. The energy conversion control method includes: In response to a charging start signal, the input current on the low-voltage side of the energy conversion device is controlled to be maintained within a first threshold range of a first current value in order to charge the high-voltage side energy storage device. When the voltage of the high-voltage side energy storage device reaches the first voltage, the input current is adjusted to gradually increase it; When the voltage of the high-voltage side energy storage device reaches the second voltage, the input current is controlled to be maintained within the second threshold range of the target current value; When the voltage of the high-voltage side energy storage device reaches the third voltage, the input current is controlled to decrease from the target current value to the second current value and maintained within the third threshold range of the second current value until the voltage of the high-voltage side energy storage device reaches the first target voltage value.

2. The energy conversion control method according to claim 1, characterized in that, The energy conversion control method further includes: After the voltage of the high-voltage side energy storage device reaches the first target voltage value, the input current of the low-voltage side is adjusted based on the real-time voltage of the high-voltage side energy storage device and the second target voltage value, so that the voltage of the high-voltage side energy storage device reaches the second target voltage value.

3. The energy conversion control method according to claim 1, characterized in that, The input current is adjusted by controlling the on and off states of the switching transistors in the full-bridge rectifier circuit; and / or, The input current is adjusted by controlling the switching transistors in the full-bridge rectifier circuit and the switching transistors in the LC resonant series half-bridge circuit to turn on and off.

4. The energy conversion control method according to claim 3, characterized in that, The step of controlling the input current on the low-voltage side of the energy conversion device to maintain within a first threshold range of a first current value in response to a charging start signal, in order to charge the high-voltage side energy storage device, includes: In response to the charging start signal, a first PWM signal and a second PWM signal with a first duty cycle and a first frequency are generated, such that the input current on the low-voltage side of the energy conversion device is maintained within a first threshold range of the first current value to charge the high-voltage side energy storage device. The first PWM signal and the second PWM signal are used to drive the switching transistors in the full-bridge rectifier circuit.

5. The energy conversion control method according to claim 4, characterized in that, When the voltage of the high-voltage side energy storage device reaches a first voltage, adjusting the input current to gradually increase it includes: When the voltage of the high-voltage side energy storage device reaches the first voltage, the duty cycle of the first PWM signal and the second PWM signal is gradually increased from the first duty cycle to the second duty cycle, and the frequency of the first PWM signal and the second PWM signal is gradually decreased from the first frequency to the second frequency.

6. The energy conversion control method according to claim 5, characterized in that, When the voltage of the high-voltage side energy storage device reaches a second voltage, controlling the input current to remain within a second threshold range of the target current value includes: When the voltage of the high-voltage side energy storage device reaches the second voltage, a third PWM signal and a fourth PWM signal are generated. The third PWM signal and the fourth PWM signal are used to drive the switching transistor in the LC resonant series half-bridge circuit so that the input current is maintained within the second threshold range of the target current value.

7. The energy conversion control method according to claim 6, characterized in that, The third PWM signal has a phase angle difference with the first PWM signal, and the fourth PWM signal has a phase angle difference with the second PWM signal, so that the switching transistor in the full-bridge rectifier circuit reaches a zero-current turn-off state when it is turned off.

8. The energy conversion control method according to claim 7, characterized in that, When the voltage of the high-voltage side energy storage device reaches the second voltage, a third PWM signal and a fourth PWM signal are generated. These signals are then used to control the switching transistors in the LC resonant series half-bridge circuit, ensuring that the input current remains within the second threshold range of the target current value. This includes: When the voltage of the high-voltage side energy storage device reaches the second voltage, a third PWM signal and a fourth PWM signal are generated. The phase shift angle between the third PWM signal and the first PWM signal and the phase shift angle between the fourth PWM signal and the second PWM signal are adjusted so that the input current is maintained within the second threshold range of the target current value. The third PWM signal and the fourth PWM signal are used to drive the switching transistor in the LC resonant series half-bridge structure circuit.

9. The energy conversion control method according to claim 8, characterized in that, When the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the input current to decrease from the target current value to a second current value and maintain it within a third threshold range of the second current value, until the voltage of the high-voltage side energy storage device reaches a first target voltage value, includes: When the voltage of the high-voltage side energy storage device reaches the third voltage, the first PWM signal and the second PWM signal are controlled to drive the switching transistor in the full-bridge rectifier circuit, and the third PWM signal and the fourth PWM signal are controlled to drive the switching transistor in the LC resonant series half-bridge structure circuit on the high-voltage side, so that the input current decreases from the target current value to the second current value and is maintained within the third threshold range of the second current value.

10. The energy conversion control method according to claim 9, characterized in that, When the voltage of the high-voltage side energy storage device reaches a third voltage, controlling the first PWM signal and the second PWM signal to drive the switching transistors in the full-bridge rectifier circuit, and controlling the third PWM signal and the fourth PWM signal to drive the switching transistors in the LC resonant series half-bridge structure circuit on the high-voltage side, includes: When the voltage of the high-voltage side energy storage device reaches the third voltage, the frequencies of the first PWM signal and the second PWM signal are gradually increased; the frequencies of the third PWM signal and the fourth PWM signal are gradually increased, the phase angle difference between the third PWM signal and the first PWM signal is gradually increased, and the phase angle difference between the fourth PWM signal and the second PWM signal is gradually increased.

11. An energy conversion system, characterized in that, The energy conversion system includes: a high-voltage side energy storage device, an energy conversion device, a low-voltage side energy storage device, and a control device. The high-voltage side energy storage device, the energy conversion device, and the low-voltage side energy storage device are connected in sequence, and the control device is connected to the energy conversion device. The energy conversion device converts the electrical energy of the low-voltage side energy storage device into target electrical energy, which is used to charge the high-voltage side energy storage device. The energy conversion device includes: a transformer; an LC resonant series half-bridge circuit coupled to the high-voltage side winding of the transformer; and a full-bridge rectifier circuit coupled to the low-voltage side winding of the transformer. The control device is used to implement the energy conversion control method according to any one of claims 1 to 10.

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