High-voltage port capacitor discharging system and charger

Abstract

The invention discloses a high-voltage port capacitor discharging system, which comprises a direct-current bus capacitor, a bus port circuit, a transformer circuit, a high-voltage port circuit and a high-voltage port capacitor, and is characterized in that when the high-voltage port capacitor discharges, the high-voltage port circuit forms an inverter; the high-voltage port circuit is controlled by a driving signal to carry out alternating current and direct current voltage conversion of the high-voltage port capacitor, the bus port circuit forms a rectifier, and energy of the high-voltage port capacitor is discharged to a direct current bus on the bus port side through the transformer circuit, so that first-stage discharging of the high-voltage port capacitor is achieved, and second-stage discharging of the high-voltage port capacitor is achieved. And when the direct-current bus voltage at the bus port side reaches a first safety threshold value, controlling the bus port circuit to be short-circuited through the driving signal so as to realize second-stage discharge of the high-voltage port capacitor. According to the high-voltage port capacitor discharging system, no extra circuit needs to be added, a discharging path is provided for the high-voltage port capacitor, the low-voltage port does not need to be discharged, control is easy, and the electric shock risk is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicles, and in particular relates to a charging and discharging system of a high-voltage port capacitor and a charger. Background Art

[0002] The on-board charger can be divided into discrete topology and integrated topology according to whether it integrates a low-voltage DCDC converter. Taking the on-board charger with integrated topology as an example, its AC port is connected to the AC power supply or load, the high-voltage port is connected to the on-board high-voltage battery, and the low-voltage port is connected to low-voltage devices such as the low-voltage battery to realize the energy flow between the AC port, the on-board high-voltage battery, and the low-voltage battery. Regardless of the discrete topology or the integrated topology, a 500uF to 2000uF capacitor will be connected in parallel between the positive and negative of the high-voltage port. When the high-voltage switch is disconnected when parking or a collision accident occurs, the high-voltage port capacitor voltage needs to be discharged to below 60V within 3s. Usually, the motor controller is used as the control unit to realize active discharge, such as motor winding discharge, IGBT discharge, and discharge resistor discharge. If the motor controller fails and normal discharge cannot be achieved, the risk of electric shock to the relevant personnel will increase. In order to further improve the safety of the vehicle, without adding additional discharge branches, active discharge can be achieved through the on-board charger controller, such as short-circuit discharge of the low-voltage port and discharge to the low-voltage battery. Short-circuit discharge at the low-voltage port will cause overcurrent risk at the low-voltage port and increase the current stress of the switching tube; discharging to the low-voltage battery can achieve fast discharge when the high-voltage port voltage is high (>275V). Once the high-voltage port voltage is lower than 275V, the discharge speed is abnormally slow and it is difficult to meet the discharge time requirements.

[0003] The diagram of the on-board charging mechanism is as follows Figure 1 As shown, Figure 1 The discrete topology includes: Power Factor Correction (PFC) circuit, DC bus capacitor Cbus, bus port circuit, transformer Tr, and high-voltage port circuit; wherein: the PFC input port is connected to AC, and the PFC output is connected to the bus port circuit through the DC bus; the DC bus capacitor Cbus is connected between the positive and negative poles of the DC bus; the bus port circuit AC output is connected to the primary winding of the transformer Tr; the high-voltage port circuit AC input is connected to the secondary winding of the transformer Tr, and the high-voltage port circuit output is connected to the high-voltage output port of the on-board charger; the high-voltage port capacitor Chv is connected between the positive and negative poles of the high-voltage output; the high-voltage output port is connected through a high-voltage switch (such as Figure 1 As shown in K), connect the high-voltage vehicle battery. Figure 2The integrated topology includes a discrete topology on-board charger and a low-voltage DCDC converter, which are connected to the low-voltage port circuit input through the low-voltage winding of the integrated transformer Tr; the low-voltage port circuit output is connected to the low-voltage output port of the integrated on-board charger; a low-voltage port capacitor Co is connected between the positive and negative poles of the low-voltage port circuit output; the low-voltage output is used to connect a low-voltage battery or device. Summary of the invention

[0004] The purpose of the present invention is to provide a high-voltage port capacitor discharge system and charger, which can achieve rapid discharge of the high-voltage port capacitor in two stages by controlling the internal circuit of the on-board charger without adding an additional discharge branch, thereby solving the technical problem that the failure of the motor controller to achieve normal discharge will increase the risk of electric shock for related personnel.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention provides a high-voltage port capacitor discharge system, which comprises: a DC bus capacitor, a bus port circuit, a transformer, a high-voltage port circuit and a high-voltage port capacitor;

[0007] The DC side of the bus port circuit is connected in parallel to the DC bus capacitor, the AC side of the bus port circuit is coupled to the bus port side winding of the transformer circuit, the AC side of the high-voltage port circuit is coupled to the high-voltage port side winding of the transformer circuit, and the DC side of the high-voltage port circuit is connected in parallel to the high-voltage port capacitor;

[0008] When the high-voltage port capacitor is discharged, the high-voltage port circuit forms an inverter, and controls the high-voltage port circuit to perform AC / DC voltage conversion of the high-voltage port capacitor through a driving signal;

[0009] The bus port circuit constitutes a rectifier, and the energy of the high-voltage port capacitor is discharged to the DC bus on the bus port side through the transformer circuit to achieve the first stage discharge of the high-voltage port capacitor;

[0010] When the DC bus voltage on the bus port side reaches a first safety threshold, the switch tubes of the bus port circuit are controlled to be alternately short-circuited by a driving signal to achieve the second stage discharge of the high-voltage port capacitor;

[0011] When the voltage of the high-voltage port capacitor drops to a second safety threshold, the high-voltage port capacitor stops discharging.

[0012] In one embodiment of the present invention, before the high-voltage port capacitor is discharged, a relay on the high-voltage port side is controlled to be disconnected by a driving signal, so that the high-voltage port capacitor is disconnected from the high-voltage battery on the high-voltage port side.

[0013] In one embodiment of the present invention, the AC side of the low-voltage port circuit is coupled to the low-voltage port side winding of the transformer circuit, and the DC side of the low-voltage port circuit is connected in parallel to the low-voltage port capacitor;

[0014] When the high-voltage port capacitor is discharged, the low-voltage port circuit is controlled to be short-circuited, so that when part of the energy of the high-voltage port capacitor is leaked to the low-voltage port circuit through the transformer circuit, the energy can be dissipated through short-circuit loss.

[0015] In one embodiment of the present invention, the bus port circuit includes a first bridge arm and a second bridge arm, and each of the bridge arms includes two switch tubes;

[0016] When the high-voltage port capacitor is discharged in the first stage, the driving signal of the switch tube of each bridge arm is blocked, and the body diode of the switch tube is used for uncontrolled rectification to increase the conduction loss of the body diode;

[0017] When the high-voltage port capacitor is discharged in the second stage, the upper tubes or lower tubes of the two bridge arms are alternately short-circuited by controlling the driving signal to increase the switching loss of the switch tube and share the conduction loss.

[0018] In one embodiment of the present invention, the high-voltage port circuit includes a third bridge arm and a fourth bridge arm, and each of the bridge arms includes two switch tubes;

[0019] When the high-voltage port capacitor is discharged, the third bridge arm and the fourth bridge arm form an inverter, and the upper tube of the third bridge arm, the lower tube of the fourth bridge arm, and the lower tube of the third bridge arm and the upper tube of the fourth bridge arm are controlled by a driving signal to be complementary and turned on, thereby converting the DC voltage of the high-voltage port capacitor into an AC voltage.

[0020] In one embodiment of the present invention, the high-voltage port circuit further includes a fifth bridge arm, and the fifth bridge arm includes two switch tubes;

[0021] The driving signals of the upper tube and the lower tube of the fifth bridge arm correspond to the same driving signals of the upper tube and the lower tube of the fourth bridge arm, so that the midpoint voltage of the fourth bridge arm and the fifth bridge arm is zero.

[0022] In one embodiment of the present invention, the driving signals of the upper tube and the lower tube of the first bridge arm and the second bridge arm correspond to the same driving signals of the upper tube and the lower tube of the third bridge arm.

[0023] In one embodiment of the present invention, the driving signals of the switch tubes of the bus port circuit and the high-voltage port circuit are pulse width modulation signals.

[0024] In one embodiment of the present invention, the first safety threshold is the maximum withstand voltage value of the DC bus capacitor at the bus port side.

[0025] Based on the same inventive concept, the present invention also provides a charger, which can implement the high-voltage port capacitor discharge system as described in any one of the above items.

[0026] The present invention provides a high-voltage port capacitor discharge system, which uses an on-board charger for active discharge without the need for additional circuits. It can provide a discharge path for the high-voltage port when the motor controller cannot discharge normally, and does not need to discharge the low-voltage port. The control is simple, which further reduces the risk of electric shock and improves the safety and reliability of the vehicle. At the same time, the bus port adopts a two-stage control method of uncontrolled rectification and complementary short circuit of the upper and lower tubes. In the first stage, part of the energy of the high-voltage port can be quickly transferred to the bus port, and part of the energy will be consumed in the process. The reactive power is very small and the discharge speed is very fast. In the latter stage, the bus port switch loss is increased, and the discharge speed is further accelerated compared to the method of short-circuiting only the upper tube or the lower tube. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0028] Figure 1 It is a structural schematic diagram of the existing discrete topology of the on-board charger.

[0029] Figure 2 This is a schematic diagram of the structure of the existing on-board charger integrated topology.

[0030] Figure 3 A structural block diagram of a high-voltage port capacitor discharge system provided by an exemplary embodiment of the present application.

[0031] Figure 4 A circuit diagram of a high-voltage port capacitor discharge system provided by an exemplary embodiment of the present application.

[0032] Figure 5 A first-stage discharge control timing diagram of a high-voltage port capacitor discharge system provided by an exemplary embodiment of the present application.

[0033] Figure 6 A second-stage discharge control timing diagram of a high-voltage port capacitor discharge system provided by an exemplary embodiment of the present application.

[0034] The reference numerals are as follows:

[0035] 100 Bus port circuit

[0036] 200 Transformer Circuit

[0037] 300 High Voltage Port Circuit

[0038] 400 Low Voltage Port Circuit DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0042] In order to solve the technical problem that the motor controller failure cannot achieve normal discharge, which increases the risk of electric shock for relevant personnel, the present invention provides a high-voltage port capacitor discharge system, which realizes the rapid discharge of the high-voltage port capacitor by controlling the internal circuit of the on-board charger in two stages without adding an additional discharge branch. Among them, the first stage is to discharge the energy on the high-voltage port capacitor to the DC bus on the bus port side until the DC bus voltage reaches the first safety threshold, and the second stage is to realize the rapid discharge of the residual energy of the high-voltage port capacitor through the switch tube loss (conduction and switching loss) and transformer loss of the internal circuit of the on-board charger. These embodiments will be discussed in detail below.

[0043] See also Figure 3As shown, in an exemplary embodiment of the present application, the high-voltage port capacitor discharge system includes a DC bus capacitor Cbus, a bus port circuit 100, a transformer circuit 200, a high-voltage port circuit 300, a high-voltage port capacitor Chv, a low-voltage port circuit 400, and a low-voltage port capacitor Co. The DC side of the bus port circuit 100 is connected in parallel with the DC bus capacitor Cbus, the AC side of the bus port circuit 100 is coupled to the bus port side winding of the transformer circuit 200, the AC side of the high-voltage port circuit 300 is coupled to the high-voltage port side winding of the transformer circuit 200, the DC side of the high-voltage port circuit 300 is connected in parallel with the high-voltage port capacitor Chv, the AC side of the low-voltage port circuit 400 is coupled to the low-voltage port side winding of the transformer circuit 200, and the DC side of the low-voltage port circuit 400 is connected in parallel with the low-voltage port capacitor Co.

[0044] It should be noted that the high-voltage port capacitor discharge system is not only applicable to discrete topologies, but also to integrated topologies. In addition, the high-voltage port capacitor discharge system is also applicable to half-bridge converters, LLC resonant converters, CLLC resonant converters, LC resonant converters, CLLLC resonant converters and DAB converters.

[0045] For details, please refer to Figure 4 As shown, Figure 4 A circuit schematic diagram of an integrated three-port topology in a vehicle charger is shown, wherein the integrated three-port topology includes three port circuits A, B, and C, which correspond to bus port circuit 100, high voltage port circuit 300, and low voltage port circuit 400, respectively. The bus port side includes a DC bus capacitor Cbus, the high voltage port side includes a high voltage port capacitor Chv, and the low voltage port side includes a low voltage port capacitor Co. In addition, the integrated three-port topology also includes a transformer circuit 200, and the transformer circuit 200 includes a first transformer T1 and a second transformer T2, the first transformer T1 includes a magnetic core, an A port side winding n1, and a B port side winding n2, and the second transformer T2 includes a magnetic core, a B port side winding n3, a C port side winding n4, and a C port side winding n5. The A port is connected to a power factor correction (PFC) circuit, the B port is connected to a vehicle high voltage battery, and the C port is connected to a vehicle low voltage battery.

[0046] The bus port circuit 100 includes a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a first switch tube S1 and a second switch tube S2 connected in series, the second bridge arm includes a third switch tube S3 and a fourth switch tube S4 connected in series, the midpoint of the first bridge arm is connected to the first end of the resonant inductor Lr, the midpoint of the second bridge arm is connected to the first end of the first resonant capacitor Cr1, the second end of the resonant inductor Lr is connected to the first end of the excitation inductor Lm and the same-name end of the A-end winding n1 of the first transformer T1, and the second end of the first resonant capacitor Cr1 is connected to the second end of the excitation inductor Lm and the opposite-name end of the A-end winding n1 of the first transformer T1.

[0047] The high-voltage port circuit 300 includes a third bridge arm, a fourth bridge arm and a fifth bridge arm connected in parallel. The third bridge arm includes a fifth switch tube S5 and a sixth switch tube S6 connected in series. The fourth bridge arm includes a seventh switch tube S7 and an eighth switch tube S8 connected in series. The fifth bridge arm includes a ninth switch tube S9 and a tenth switch tube S10 connected in series. The midpoint of the third bridge arm is connected to the first end of the second resonant inductor Cr2. The midpoint of the fourth bridge arm is connected to the opposite end of the B-end winding n2 of the first transformer T1 and the same end of the B-end winding n3 of the second transformer T2. The midpoint of the fifth bridge arm is connected to the first end of the transformer leakage inductor Ls. The second end of the second resonant capacitor Cr2 is connected to the same end of the B-end winding n2 of the first transformer T1. The second end of the transformer leakage inductor Ls is connected to the opposite end of the B-end winding n3 of the second transformer T2. The opposite end of the B-end winding n2 of the first transformer T1 is connected to the same end of the B-end winding n3 of the second transformer T2.

[0048] The low-voltage port circuit 400 includes an eleventh switch tube S11, a twelfth switch tube S12, a thirteenth switch tube S13 and a fourteenth switch tube S14. The opposite-name end of the C-end winding n4 of the second transformer T2 is connected to the same-name end of the C-end winding n5 of the second transformer T2. The first end of the eleventh switch tube S11 is connected to the opposite-name end of the C-end winding n5 of the second transformer T2. The thirteenth switch tube S13 is first connected in parallel with the first diode D1 and then in series with the first capacitor C1, and then connected in parallel to the two ends of the eleventh switch tube S11. The first end of the twelfth switch tube S12 is connected to the same-name end of the C-end winding n4 of the second transformer T2. The fourteenth switch tube S14 is first connected in parallel with the second diode D2 and then in series with the second capacitor C2, and then connected in parallel to the two ends of the twelfth switch tube S12. The second end of the eleventh switch tube S11 is connected to the second end of the twelfth switch tube S12.

[0049] The high-voltage port capacitor Chv is connected in parallel to the DC side of the high-voltage port circuit 300, the DC bus capacitor is connected in parallel to the DC side of the bus port circuit 100, and the low-voltage port capacitor Co is connected in parallel to the DC side of the low-voltage port circuit 400. A filter inductor Lvf is also connected between the high-voltage port circuit 300 and the high-voltage port capacitor Chv to filter out the high-frequency component of the high-voltage port capacitor voltage and to pass DC and block AC.

[0050] It should be noted that the switch tubes S1 to S14 are metal oxide semiconductor field effect transistors (MOSFET). In this embodiment, the switch tubes are N-type MOSFET tubes. Of course, in other embodiments, the switch tubes may also be IGBT tubes. In addition, the driving signals of the switch tubes of the bus port circuit 100, the high voltage port circuit 300, and the low voltage port circuit 400 are pulse width modulation signals (PWM), and the switching frequency is fs. The high or low switching frequency affects the discharge rate of the high voltage port capacitor Chv.

[0051] See also Figure 4 As shown, in an exemplary embodiment of the present application, before the high-voltage port capacitor Chv is discharged, the relay RL on the high-voltage port side is controlled to be disconnected by a driving signal, so that the high-voltage port capacitor Chv is disconnected from the high-voltage battery on the high-voltage port side.

[0052] Specifically, the output side of the high-voltage port is connected to a vehicle-mounted high-voltage battery. When the motor controller fails and cannot be discharged normally, the voltage of the high-voltage port capacitor Chv needs to be discharged to below the second safety threshold in a short time. Therefore, when the high-voltage port capacitor Chv is actively discharged, the high-voltage switch on the high-voltage port side needs to be disconnected by controlling the drive signal, so that the high-voltage port capacitor Chv is disconnected from the high-voltage battery on the high-voltage port side. It should be noted that in this embodiment, the second safety threshold is 60V, and the high-voltage switch is a relay RL.

[0053] The following will be combined Figures 4 to 6 The working principle of the high-voltage port capacitor discharge system is described below.

[0054] See also Figure 4 and Figure 5 As shown, Figure 5This is a control timing diagram of the first stage discharge of the high-voltage port capacitor Chv. In an exemplary embodiment of the present application, the specific working process of the first stage discharge of the high-voltage port capacitor Chv is as follows:

[0055] The high-voltage port circuit 300 is actively controlled, and the fifth switch tube S5 of the third bridge arm, the eighth switch tube S8 of the fourth bridge arm, the sixth switch tube S6 of the third bridge arm, and the seventh switch tube S7 of the fourth bridge arm of the high-voltage port circuit 300 are controlled by PWM signals to be complementary and turned on. The fourth bridge arm and the fifth bridge arm constitute an inverter, which converts the DC voltage of the high-voltage port capacitor Chv into an AC voltage with decreasing amplitude. It should be noted that, in this embodiment, the duty cycle of the PWM signal is 50%. Of course, in other embodiments, the duty cycle of the PWM signal can also be customized according to actual application requirements. In addition, if the high-voltage port circuit 300 has a fifth bridge arm, the upper and lower tube driving signals thereof are the same as those of the upper and lower tubes of the fourth bridge arm, that is, the driving signal of the ninth switch tube S9 of the fifth bridge arm is the same as that of the seventh switch tube S7 of the fourth bridge arm, and the driving signal of the tenth switch tube S10 of the fifth bridge arm is the same as that of the eighth switch tube S8 of the fourth bridge arm, so that the midpoint voltage between the fourth bridge arm and the fifth bridge arm is zero.

[0056] The bus port circuit 100 adopts an uncontrolled rectification strategy to block the switch tube drive signals on the first bridge arm and the second bridge arm of the bus port circuit 100, that is, the first switch tube S1, the second switch tube S2, the third switch tube S3 and the fourth switch tube S4 are blocked by setting the drive signal low, and the body diodes of the switch tubes S1 to S4 are used for uncontrolled rectification to increase the conduction loss of the body diode. For the integrated topology with the low-voltage port circuit 400, the low-voltage port circuit 400 is controlled to remain short-circuited by the drive signal, that is, the drive signals of the eleventh switch tube S11 and the twelfth switch tube S12 are always set high, and the thirteenth switch tube S13 and the fourteenth switch tube S14 are not applied with drive signals, and are not turned on by default.

[0057] Part of the energy of the high-voltage port capacitor Chv is converted by the transformer circuit 200 and discharged to the DC bus on the bus port side. When the DC bus voltage on the bus port side rises to the first safety threshold, the first stage discharge of the high-voltage port capacitor is terminated. It should be noted that the first safety threshold is the maximum withstand voltage value of the DC bus capacitor Cbus on the bus port side.

[0058] See also Figure 4 and Figure 6 As shown, Figure 6This is a control timing diagram of the second stage discharge of the high-voltage port capacitor Chv. In an exemplary embodiment of the present application, the specific working process of the second stage discharge of the high-voltage port capacitor Chv is as follows:

[0059] The high-voltage port circuit 300 is actively controlled, and the fifth switch tube S5 of the third bridge arm, the eighth switch tube S8 of the fourth bridge arm, the sixth switch tube S6 of the third bridge arm, and the seventh switch tube S7 of the fourth bridge arm of the high-voltage port circuit 300 are complementary turned on through a PWM signal, and the fourth bridge arm and the fifth bridge arm constitute an inverter to convert the DC voltage of the high-voltage port capacitor into an AC voltage with decreasing amplitude. It should be noted that when the high-voltage port capacitor Chv is discharged in the second stage, the active control process of the high-voltage port circuit 300 is completely consistent with the first stage discharge of the high-voltage port capacitor Chv.

[0060] The bus port circuit 100 is actively controlled, and the upper tube and the lower tube of the first bridge arm and the second bridge arm of the bus port circuit 100 are alternately short-circuited by PWM signals, that is, the upper tubes of the first bridge arm and the second bridge arm or the lower tubes of the first bridge arm and the second bridge arm are simultaneously turned on or off, so that the first switch tube S1 of the first bridge arm, the third switch tube S3 of the second bridge arm, the resonant inductor Lr, the transformer excitation inductor Lm, the A-end winding n1 of the first transformer T1 and the first resonant capacitor Cr1 form an AC circuit, or the second switch tube S2 of the first bridge arm, the fourth switch tube S4 of the second bridge arm, the resonant inductor Lr, the transformer excitation inductor Lm, the A-end winding n1 of the first transformer T1 and the first resonant capacitor Cr1 form an AC circuit. The upper tube and the lower tube of the first bridge arm and the second bridge arm are alternately short-circuited to increase the switching loss of the switch tube, and to evenly distribute the conduction loss to avoid uneven heat distribution. It is worth noting that the driving signals of the upper and lower tubes of the first bridge arm and the second bridge arm correspond to the same driving signals of the upper and lower tubes of the third bridge arm. If the low-voltage port circuit 400 exists in the integrated topology, the low-voltage port circuit 400 is controlled to be short-circuited by the driving signal, that is, the driving signals of the eleventh switch tube S11 and the twelfth switch tube S12 are always set high. The thirteenth switch tube S13 and the fourteenth switch tube S14 are not applied with driving signals and are not turned on by default.

[0061] It should be noted that when the high-voltage port capacitor Chv is discharged, the low-voltage port circuit 400 is controlled to be short-circuited, so that part of the energy of the high-voltage port capacitor Chv is discharged to the low-voltage port circuit 400 through the second transformer T2, and the energy can be dissipated through short-circuit loss.

[0062] By discharging the voltage of the high-voltage port capacitor Chv in the first stage and the second stage, the voltage of the high-voltage port capacitor Chv is quickly discharged to below the second safety threshold. When the voltage of the high-voltage port capacitor Chv is lower than the second safety threshold, the high-voltage port capacitor Chv stops discharging.

[0063] In summary, the present invention provides a high-voltage port capacitor discharge system, including a DC bus capacitor Cbus, a bus port circuit 100, a transformer circuit 200, a high-voltage port circuit 300 and a high-voltage port capacitor Chv. When the high-voltage port capacitor Chv is discharged, the high-voltage port circuit 300 constitutes an inverter, and the high-voltage port circuit 300 is controlled by a drive signal to perform AC / DC voltage conversion of the high-voltage port capacitor Chv. The bus port circuit 100 constitutes a rectifier. The energy of the high-voltage port capacitor Chv is discharged to the DC bus on the bus port side through the transformer circuit 200 to achieve the first stage discharge of the high-voltage port capacitor Chv. When the DC bus voltage on the bus port side reaches a first safety threshold, the bus port circuit 100 is controlled to be short-circuited by a drive signal to achieve the second stage discharge of the high-voltage port capacitor Chv. When the voltage of the high-voltage port capacitor Chv drops to a second safety threshold, the high-voltage port capacitor Chv stops discharging. The high-voltage port capacitor discharge system uses an on-board charger for active discharge without the need for additional circuits. It can provide a discharge path for the high-voltage port when the motor controller cannot discharge normally, and does not need to discharge the low-voltage port. The control is simple, further reducing the risk of electric shock and improving the safety and reliability of the vehicle. At the same time, the bus port adopts a two-stage control method of uncontrolled rectification and complementary short circuit of the upper and lower tubes. In the first stage, part of the energy of the high-voltage port can be quickly transferred to the bus port, and part of the energy will be consumed in the process. The reactive power is very small and the discharge speed is very fast. In the latter stage, the switching loss of the bus port is increased to further accelerate the discharge speed compared to the method of only short-circuiting the upper tube or the lower tube.

[0064] Based on the same inventive concept, the present invention also provides a charger, which can realize the high-voltage port capacitor discharge system described in any of the above embodiments. The charger includes but is not limited to a vehicle-mounted charger. Since the charger provided in this embodiment belongs to the same inventive concept as the high-voltage port capacitor discharge system described in any of the above embodiments, it has at least the same beneficial effects as the high-voltage port capacitor discharge system, and will not be described one by one here.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A high voltage port capacitor discharge system, characterized in that: Including DC bus capacitor, bus port circuit, transformer circuit, high voltage port circuit and high voltage port capacitor; The DC side of the bus port circuit is connected in parallel to the DC bus capacitor, the AC side of the bus port circuit is coupled to the bus port side winding of the transformer circuit, the AC side of the high-voltage port circuit is coupled to the high-voltage port side winding of the transformer circuit, and the DC side of the high-voltage port circuit is connected in parallel to the high-voltage port capacitor; When the high-voltage port capacitor is discharged, the high-voltage port circuit forms an inverter, and controls the high-voltage port circuit to perform AC / DC voltage conversion of the high-voltage port capacitor through a driving signal; The bus port circuit constitutes a rectifier, and the energy of the high-voltage port capacitor is discharged to the DC bus on the bus port side through the transformer circuit to achieve the first stage discharge of the high-voltage port capacitor; When the DC bus voltage on the bus port side reaches a first safety threshold, the switch tubes of the bus port circuit are controlled to be alternately short-circuited by a driving signal to achieve the second stage discharge of the high-voltage port capacitor; When the voltage of the high-voltage port capacitor drops to a second safety threshold, the high-voltage port capacitor stops discharging.

2. The high voltage port capacitor discharge system according to claim 1, characterized in that: Before the high-voltage port capacitor is discharged, the relay on the high-voltage port side is controlled to be disconnected by a driving signal, so that the high-voltage port capacitor is disconnected from the high-voltage battery on the high-voltage port side.

3. The high voltage port capacitor discharge system according to claim 1, characterized in that: It also includes a low-voltage port circuit and a low-voltage port capacitor, wherein the AC side of the low-voltage port circuit is coupled to the low-voltage port side winding of the transformer circuit, and the DC side of the low-voltage port circuit is connected in parallel to the low-voltage port capacitor; When the high-voltage port capacitor is discharged, the low-voltage port circuit is controlled to be short-circuited, so that when part of the energy of the high-voltage port capacitor is leaked to the low-voltage port circuit through the transformer circuit, the energy can be dissipated through short-circuit loss.

4. The high voltage port capacitor discharge system according to claim 1, characterized in that: The bus port circuit comprises a first bridge arm and a second bridge arm, and each of the bridge arms comprises two switch tubes; When the high-voltage port capacitor is discharged in the first stage, the driving signal of the switch tube of each bridge arm is blocked, and the body diode of the switch tube is used for uncontrolled rectification to increase the conduction loss of the body diode; When the high-voltage port capacitor is discharged in the second stage, the upper tubes or lower tubes of the two bridge arms are alternately short-circuited by controlling the driving signal to increase the switching loss of the switch tube and share the conduction loss.

5. The high voltage port capacitor discharge system according to claim 1, characterized in that: The high-voltage port circuit comprises a third bridge arm and a fourth bridge arm, and each of the bridge arms comprises two switch tubes; When the high-voltage port capacitor is discharged, the third bridge arm and the fourth bridge arm form an inverter, and the upper tube of the third bridge arm, the lower tube of the fourth bridge arm, and the lower tube of the third bridge arm and the upper tube of the fourth bridge arm are controlled by a driving signal to be complementary and turned on, thereby converting the DC voltage of the high-voltage port capacitor into an AC voltage.

6. The high voltage port capacitor discharge system according to claim 5, characterized in that: The high-voltage port circuit further includes a fifth bridge arm, and the fifth bridge arm includes two switch tubes; The driving signals of the upper tube and the lower tube of the fifth bridge arm correspond to the same driving signals of the upper tube and the lower tube of the fourth bridge arm, so that the midpoint voltage of the fourth bridge arm and the fifth bridge arm is zero.

7. The high voltage port capacitor discharge system according to claims 4 and 5, characterized in that: The driving signals of the upper tube and the lower tube of the first bridge arm and the second bridge arm correspond to the same driving signals of the upper tube and the lower tube of the third bridge arm.

8. The high voltage port capacitor discharge system according to claim 4 or 5, characterized in that: The driving signals of the switch tubes of the bus port circuit and the high-voltage port circuit are pulse width modulation signals.

9. The high voltage port capacitor discharge system according to claim 1, characterized in that: The first safety threshold is the maximum withstand voltage value of the DC bus capacitor at the bus port side.

10. A charger, characterized in that: The charger can implement the high-voltage port capacitor discharge system as described in any one of claims 1 to 9.

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