Power conversion and transmission system and method for controlling same

Abstract

The invention discloses a power conversion and transmission system and a method for controlling the system. The power supply conversion and transmission system comprises a power supply sending unit, a load unit and a cable. The power supply sending unit comprises a power supply conversion circuit which is used for converting an input power supply into a relay output power supply. And a path switch coupled between the relay output power supply and the bus power supply. The cable comprises a power supply sub-cable, a communication sub-cable and a grounding sub-cable and is used for respectively coupling a transmitting end power supply node, a communication node and a grounding node of the power supply transmitting unit to corresponding nodes of the load unit, and bus current flows through the power supply sub-cable and the grounding sub-cable. At an initial time point, the voltage of the transmitting end communication node is sensed and recorded as an initial voltage level. If the difference value between the current voltage level and the initial voltage level of the sending end communication node exceeds a threshold value at a judgment time point, starting power supply limiting operation;

Description

Technical Field

[0001] The present invention relates to a power conversion and transmission system, and particularly to a power conversion and transmission system with a function of fault detection and current or power limitation. The present invention also relates to a control method for controlling the power conversion and transmission system. Background Art

[0002] Figure 1 A prior art power conversion and transmission system is shown, which includes a power transmitting unit 10 and a load unit 20, and these two units are connected by a cable 50. The power transmitting unit 10 includes a power conversion circuit 110 and a transmitting control circuit 120. The transmitting control circuit 120 is responsible for controlling the power conversion circuit 110 to generate a bus power supply (which has a bus voltage VBUS and a bus current IBUS) and supply it to the load unit 20. The power transmitting unit 10 also includes a current sensing resistor RCS. The transmitting control circuit 120 detects the bus current IBUS provided by the power transmitting unit by sensing the voltage VCS (current sensing signal) on the current sensing resistor RCS.

[0003] When the bus current IBUS exceeds a certain threshold, the transmitting control circuit will activate an overcurrent protection mechanism, and turn off the path between the cable and the power conversion circuit by controlling the path control switch to prevent overcurrent. However, in the prior art, if the current sensing resistor RCS is short-circuited, even though the bus current IBUS has exceeded the overcurrent threshold, since the short-circuit resistance of the current sensing resistor RCS is extremely low, the sensed voltage of the current sensing signal VCS will still be very small. This results in that even if an overcurrent occurs, the system still cannot correctly judge the short-circuit situation of the current sensing resistor RCS through the VCS voltage, and thus cannot activate an appropriate protection mechanism. This is an urgent shortcoming to be improved in this prior art.

[0004] In view of this, the present invention aims to propose an improved architecture of the power transmitting unit, which can still judge whether an overcurrent or a short-circuit of the current sensing resistor RCS occurs by detecting certain electrical characteristics on the terminal connected to the cable even if the current sensing resistor RCS is short-circuited. Such an improvement can overcome the deficiency of the prior art in being unable to correctly detect the short-circuit of the current sensing resistor RCS and provide a more reliable protection mechanism. Summary of the Invention

[0005] In one aspect, the present invention provides a power conversion and transmission system, including a power transmitting unit, a load unit, and a cable. The power transmitting unit includes a power conversion circuit, a charge pump circuit, a transmission control circuit, and a path switch. The power conversion circuit converts an input power supply into a relay output power supply; the charge pump circuit generates a gate voltage; the transmission control circuit controls the power conversion circuit and generates an output control signal to control the charge pump circuit. The path switch is coupled between the relay output power supply and the bus power supply, and is controlled by the gate voltage to conduct or cut off the electrical connection between the relay output power supply and the bus power supply. The path switch includes an N-type MOSFET (metal-oxide-semiconductor field-effect transistor). The load unit is coupled between the bus power supply and the load terminal ground node. The bus power supply supplies power to the load unit, and the load unit determines the bus current of the bus power supply. The cable includes a power sub-cable, a communication sub-cable, and a ground sub-cable, and is used to selectively couple the transmitting-end power node, the transmitting-end communication node, and the transmitting-end ground node of the power transmitting unit to the load-end power node, the load-end communication node, and the load-end ground node of the load unit respectively. The bus current flows through the power sub-cable and the ground sub-cable. At the judgment time point, the transmission control circuit senses the current voltage level of the transmitting-end communication node. If the current voltage level exceeds a first threshold, a power limit operation is started; or the difference between the current voltage level and the initial voltage level is calculated. If the difference exceeds a second threshold, a power limit operation is started, where the transmission control circuit senses the voltage of the transmitting-end communication node at the initial time point and records it as the initial voltage level. The time point when the output control signal turns to enabled is earlier than the initial time point and the judgment time point, and the initial time point is earlier than the judgment time point. In the power limit operation, the transmission control circuit controls the path switch to cut off, stopping the power supply to the load unit, or controls the path switch to limit the power level or current level of the bus power supply.

[0006] In a preferred embodiment, the ground sub-cable has a parasitic resistance.

[0007] In a preferred embodiment, the load unit has a resistive device, which is coupled between the load-end communication node and the load-end ground node.

[0008] In a preferred embodiment, the gate voltage level generated by the charge pump circuit is programmable.

[0009] In a preferred embodiment, the power conversion and transmission system further includes a current sensing resistor, which is configured on the current path of the bus current and is used to generate a current sensing voltage proportional to the bus current. At the judgment time point, when the voltage level of the current sensing resistor is lower than a third threshold, the transmission control circuit starts the power limit operation. The bus current level corresponding to the first threshold is greater than or equal to the bus current level corresponding to the third threshold, or the bus current level corresponding to the second threshold is greater than or equal to the bus current level corresponding to the third threshold.

[0010] In a preferred embodiment, the determination time point occurs after the readiness time point, where the readiness time point is the time point when the bus voltage rises to the steady-state voltage, or the time point when the gate voltage of the path switch rises to reach the final voltage. The determination time point can be multiple time points periodically triggered after the readiness time point, or continuous time after the readiness time point.

[0011] From another perspective, the present invention provides a method for controlling a power conversion and transmission system, which system includes a power sending unit, a load unit, and a cable. The power sending unit includes a power conversion circuit and a path switch. The power conversion circuit converts an input power supply into a relay output power supply. The path switch is coupled between the relay output power supply and the bus power supply for conducting or disconnecting the electrical connection therebetween. The load unit is coupled between the bus power supply and the load-side ground node. The bus power supply supplies power to the load unit, and the load unit determines the bus current of the bus power supply. The cable includes a power sub-cable, a communication sub-cable, and a ground sub-cable for selectively coupling the sending-end power node, the sending-end communication node, and the sending-end ground node of the power sending unit to the load-side power node, the load-side communication node, and the load-side ground node of the load unit respectively. The bus current flows through the power sub-cable and the ground sub-cable. The method includes: enabling the path switch; at the determination time point, sensing the current voltage level of the sending-end communication node; if the current voltage level exceeds a first threshold, starting a power limit operation; or calculating the difference between the current voltage level and the initial voltage level, and if the difference exceeds a second threshold, starting a power limit operation; where the voltage of the sending-end communication node at the initial time point corresponds to the initial voltage level. The enabling time point of the path switch is earlier than the initial time point and the determination time point, and the initial time point is earlier than the determination time point. The steps of the power limit operation include controlling the path switch to turn off to stop power supply to the load unit, or controlling the path switch to limit the power level or current level of the bus power supply.

[0012] In a preferred embodiment, the step of enabling the path switch includes controlling the path switch to turn on with soft start.

[0013] In a preferred embodiment, the power conversion and transmission system further includes a current sensing resistor configured on the current path of the bus current for generating a current sensing voltage proportional to the bus current. The method further includes: at the determination time point, starting the power limit operation only when the voltage level of the current sensing resistor is lower than a third threshold. The bus current level corresponding to the first threshold is greater than or equal to the bus current level corresponding to the third threshold, or the bus current level corresponding to the second threshold is greater than or equal to the bus current level corresponding to the third threshold.

[0014] The following will be described in detail through specific embodiments to more easily understand the purpose, technical content, features, and achieved effects of the present invention. Description of the Drawings

[0015] Figure 1 Shows a power conversion and transmission system of the prior art.

[0016] Figure 2 Shows a block diagram of the power conversion and transmission system in an embodiment of the present invention.

[0017] Figure 3 Shows an operating waveform diagram of an embodiment of the power conversion and transmission system of the present invention corresponding to Figure 2 .

[0018] Figure 4 Shows a block diagram of the pull-up circuit and the pull-down circuit in an embodiment of the present invention.

[0019] Figures 5A to 5C Shows schematic diagrams of several specific embodiments of the pull-up circuit and the pull-down circuit of the present invention.

[0020] Figures 6 to 9 Shows an operation flowchart of the power conversion and transmission system in several embodiments of the present invention.

[0021] Description of the Symbols in the Drawings

[0022] 10: Power transmitting unit

[0023] 20: Load unit

[0024] 30, 40: Connectors

[0025] 50: Cable

[0026] 51: Power sub-cable

[0027] 52: Communication sub-cable

[0028] 53: Ground sub-cable

[0029] 55, 56: Parasitic resistances

[0030] 110: Power conversion circuit

[0031] 120: Transmission control circuit

[0032] 121: Pull-up circuit

[0033] 122: Pull-up circuit

[0034] 130: Charge pump circuit

[0035] 210: Load circuit

[0036] 220: Load control circuit

[0037] 221: Pull-down circuit

[0038] 222: Pull-down circuit

[0039] CC1 / CC2: Configuration channel

[0040] EN: Output control signal

[0041] IBUS: Bus current

[0042] IPD: Pull-down current source

[0043] IPU: Pull-up current source

[0044] MSP: Path switch

[0045] NBR: Load terminal power supply node

[0046] NBT: Transmitter terminal power supply node

[0047] NCR: Load terminal communication node

[0048] NCT: Transmitter terminal communication node

[0049] NGR: Load terminal ground node

[0050] NGT: Transmitter terminal ground node

[0051] RCS: Current sensing resistor

[0052] RPD: Pull-down resistor

[0053] RPU: Pull-up resistor

[0054] T0: Time point

[0055] T1: Initial time point

[0056] T2: Readiness time point

[0057] T2a: Time point

[0058] T2b: Time point

[0059] TC: Judgment time point

[0060] VBUS: Bus voltage

[0061] VCS: Current sensing signal

[0062] VCS_TC: Current sensing signal

[0063] VDD: Supply voltage

[0064] Vdiff: Voltage difference

[0065] VG: Gate voltage

[0066] VGND': Ground potential at the ground node of the load side

[0067] VIN: Input power supply

[0068] VM: Relay output power supply

[0069] VNCT: Voltage at the communication node of the transmitting end

[0070] VNCT_T1: Initial voltage level

[0071] VNCT_TC: Current voltage level

[0072] Vthg: Conduction threshold

[0073] Vthr: Threshold

[0074] VTH0~VTH3: Thresholds Detailed implementation manners

[0075] The drawings in the present invention are all schematic, mainly intended to show the coupling relationship between each circuit and the relationship between each signal waveform. As for the circuit, signal waveform and frequency, they are not drawn according to scale. For the sake of clear illustration, many practical details will be described together in the following description, but this is not intended to limit the scope of the patent application of the present invention.

[0076] Figure 2 Shows a block diagram of a power conversion and transmission system in an embodiment of the present invention. In this embodiment, the power conversion and transmission system includes a power transmitting unit 10 and a load unit 20, and the power transmitting unit 10 and the load unit 20 are connected by a cable 50. On the side of the power transmitting unit 10, there are three connection nodes, namely: the transmitting end power node NBT, the transmitting end communication node NCT, and the transmitting end ground node NGT.

[0077] Correspondingly, on the side of the load unit 20, there are also three corresponding nodes: the load end power node NBR, the load end communication node NCR, and the load end ground node NGR.

[0078] The cable 50 is responsible for connecting the three nodes of the power transmitting unit 10 to the three corresponding nodes of the load unit 20 respectively, so as to perform the transmission of power and communication.

[0079] In an implementation manner, these nodes can be located on a connector 30 of the power transmitting unit, and the corresponding nodes of the load unit 20 can be located on the connector 40 of the load unit 20. In the case where there are connectors on both sides, this cable is completely removable. However, these connectors are not necessarily required, and it is also possible to directly couple the nodes of one of the two units through the cable 50, with a connector on only one side and a fixed connection on the other side.

[0080] In a specific embodiment, the above-mentioned cable 50, connector 30, and connector 40 are interfaces compliant with the USB-C specification. In one embodiment, the sending-end power node NBT and the receiving-end power node NBR correspond to the bus power VBUS in the USB-C specification, the sending-end communication node NCT and the receiving-end communication node NCR correspond to the configuration channels CC1 or CC2 in the USB-C specification, and the sending-end ground node NGT and the receiving-end ground node NGR correspond to the ground GND in the USB-C specification.

[0081] In a specific embodiment, the power sending unit 10 includes: a power conversion circuit 110, a sending control circuit 120, a charge pump circuit 130, as well as a path switch MSP and a current sensing resistor RCS. The load unit 20 includes: a load control circuit 220 and a load circuit 210.

[0082] The sending control circuit 120 is used to control the power conversion circuit 110 to convert the input power VIN to generate a relay output power VM. The path switch MSP is coupled between the relay output power VM and the bus power to conduct or cut off the electrical connection between the relay output power VM and the bus power. The bus power has a bus voltage VBUS and a bus current IBUS. The bus power is connected to the sending-end power node NBT and is transmitted to the load unit 20 via the power sub-cable 51 in the cable 50, and supplies power to the load circuit 210 in the load unit 20 through the receiving-end power node NBR.

[0083] The load circuit 210 determines the consumed electrical energy and thus determines the level of the bus current IBUS. After passing through the load circuit, the current returns to the sending-end ground node NGT of the power sending unit 10 via the receiving-end ground node NGR and the ground sub-cable 53 in the cable 50. Finally, the bus current IBUS will flow through the current sensing resistor RCS and is coupled back to the power conversion circuit 110 to form a power loop.

[0084] In one embodiment, the path switch MSP is an NMOSFET (N-type metal-oxide-semiconductor field-effect transistor), and the sending control circuit 120 controls the charge pump circuit 130 to generate the gate voltage VG of the path switch MSP to control the conduction and cut-off of the path switch MSP.

[0085] In one embodiment, the level of the bus voltage VBUS is determined after communication between the transmission control circuit 120 and the load control circuit 220 through the configuration channel CC1 or CC2. The transmission control circuit 120 controls the power conversion circuit 110 to generate a relay output power supply VM with a corresponding level, and controls the path switch MSP to determine the electrical connection between the relay output power supply VM and the bus voltage VBUS. Thus, the bus power effectively transmits power to the load unit 20 through the relevant connection node.

[0086] Figure 4 The block diagram of the pull-up circuit and the pull-down circuit in an embodiment of the present invention is shown. In one embodiment, in order to determine whether the power transmission unit 10 and the load unit 20 are coupled to each other, the transmission control circuit 120 includes a pull-up circuit 121, and the load control circuit 220 includes a pull-down circuit 221. The pull-up circuit 121 is coupled to the load-side communication node NCR through the transmission communication node NCT and the communication sub-cable 52 of the cable 50, and then coupled to the pull-down circuit 221. The pull-up circuit 121 has a resistive element coupled between the transmission communication node NCT and the supply voltage VDD. The pull-down circuit 221 has a resistive element coupled between the load-side communication node NCR and the load-side ground node NGR. The resistive element will be described in detail later.

[0087] When the power transmission unit 10 and the load unit 20 are not coupled to each other, the voltage VNCT on the transmission communication node NCT is pulled up to the highest voltage, i.e., the supply voltage VDD, by the pull-up circuit 121; while the voltage VNCR on the load-side communication node NCR is pulled down to the ground voltage, i.e., 0V, by the pull-down circuit 221.

[0088] When the power transmission unit 10 and the load unit 20 are coupled through the cable 50, the pull-up circuit 121 and the pull-down circuit 221 pull the voltage VNCT on the transmission communication node NCT and the voltage VNCR on the load-side communication node NCR to an intermediate voltage through their resistive elements. This voltage is greater than 0V but less than the supply voltage VDD. The transmission control circuit 120 or the load control circuit can thus determine that the power transmission unit 10 and the load unit 20 are already coupled.

[0089] Figures 5A to 5C The schematic diagrams showing several specific embodiments of the pull-up circuit and the pull-down circuit of the present invention are shown.

[0090] As Figure 5A shown, in this embodiment, the pull-up circuit 121 includes a pull-up resistor RPU coupled between the supply voltage VDD and the transmission communication node NCT. The pull-down circuit 221 includes a pull-down resistor RPD coupled between the load-side communication node NCR and the load-side ground node NGR.

[0091] As Figure 5B shown, in this embodiment, the pull-down circuit 221 is still the pull-down resistor RPD. The pull-up circuit 122 includes a pull-up current source IPU, which is coupled between the supply voltage VDD and the transmission communication node NCT.

[0092] As Figure 5C shown, in this embodiment, the pull-up circuit 121 uses the pull-up resistor RPU. The pull-down circuit 222 includes a pull-down current source IPD, which is coupled between the load-side communication node NCR and the load-side ground node NGR.

[0093] Continuing to refer to Figure 2 , in an embodiment, when the current sensing resistor RCS is operating normally, the current sensing resistor RCS generates a corresponding current sensing signal VCS according to the level of the bus current IBUS flowing through it. The transmission control circuit 120 determines whether the current exceeds a preset overcurrent threshold according to the voltage level of the current sensing signal VCS. If the voltage level of the current sensing signal VCS is greater than the threshold VTH0, it indicates that an overcurrent has occurred. At this time, the transmission control circuit 120 will activate the power limit mechanism. There are various implementation methods for power limit: for example, directly turning off the path switch MSP to stop the power conversion circuit 110 from supplying power to the load unit 20; or, limiting the output current or power of the system, such as adjusting the level of the bus current IBUS or the output power level of the bus power supply by controlling the transistor MSP or the power conversion circuit 110.

[0094] In addition to the above judgment method, there is another overcurrent detection method, which can be realized by sensing the voltage on other connection nodes. Figure 3 Showing an operation waveform diagram of an embodiment of the power conversion and transmission system corresponding to Figure 2 of the present invention. In an embodiment, the transmission control circuit 120 generates an output control signal EN to enable the charge pump circuit 130, thereby increasing the gate voltage VG to control the conduction of the path switch MSP. In an embodiment, as Figure 3 shown, after the output control signal EN turns to enabled (high potential) at time point T0, the gate voltage VG starts to rise gradually to control the soft start of the path switch MSP.

[0095] In an embodiment, the transmission control circuit 120 detects the voltage VNCT on the transmission-side communication node NCT at a judgment time point TC after the output control signal EN is enabled. If VNCT exceeds a second preset threshold VTH1 at the judgment time point TC, the transmission control circuit 120 can determine that an overcurrent has also occurred at this time; this is because the voltage VNCT on the transmission-side communication node NCT is associated with the ground voltage of the load control circuit 220.

[0096] Please refer back to Figure 2, specifically, the ground potential of the load control circuit 220 comes from the load-side ground node NGR, and there is a parasitic resistance 56 on the ground sub-cable 53 in the cable 50. As Figure 2 shown, the parasitic resistance 56 can be modeled as being coupled between the transmitter-side ground node NGT and the load-side ground node NGR. If the bus current IBUS flowing through the ground sub-cable 53 is large, when the bus current IBUS passes through the parasitic resistance 56, it will cause the ground potential gate voltage VGND' on the load-side ground node NGR to increase, which results in an increase in the voltage VNCT on the communication cable associated with the load control circuit 220. When VNCT exceeds the threshold VTH1, the transmit control circuit 120 can determine that an overcurrent (OC) has occurred. Similarly, there is a parasitic resistance 55 on the power sub-cable 51 in the cable 50.

[0097] Continue to refer to Figure 2 and Figure 3 , another method for judging overcurrent (OC) is based on the voltage change at two different time points. In one embodiment, at the initial time point T1, the transmit control circuit 120 measures the voltage VNCT on the transmitter-side communication node NCT and records it as VNCT_T1. Then, at the judgment time point TC, the transmit control circuit 120 measures the same node voltage again and records it as the current level VNCT_TC.

[0098] The transmit control circuit 120 calculates the difference between these two voltage values, that is, VNCT_TC - VNCT_T1. If this difference exceeds a preset threshold, such as VTH2, the transmit control circuit 120 can determine that an overcurrent (OC) has occurred. At this time, the transmit control circuit will, for example, turn off the path switch MOSFET to stop the power supply.

[0099] The aforementioned judgment time point TC is one or more time points after the ready time point T2. The ready time point T2, as Figure 3 shown, refers to the bus voltage VBUS rising to the steady-state voltage (such as time point T2a), or the gate voltage VG of the path switch MSP rising to its final voltage (such as time point T2b). In addition, the appropriate timing (judgment time point TC) for sensing the current level referred to in this article can be periodic, that is, sensing is performed periodically after the ready time point T2 to determine whether power limitation needs to be initiated. Another method is to continuously sense the current level VNCT_TC of the transmitter-side communication node voltage VNCT after the ready time point T2 and continuously make judgments to determine whether to initiate power limitation. On the other hand, the concepts of the initial time point T1, the ready time point T2, and the judgment time point TC in the following embodiments are the same.

[0100] Continue to refer to Figure 3, the time point when the output control signal EN is enabled is T0. T0 represents the start of the output control signal EN to control the charge pump circuit 130 to perform soft start on the path switch MSP. During this process, the charge pump circuit gradually ramps up the gate voltage VG of the path switch MSP. As Figure 3 shown, when the gate voltage VG gradually rises and exceeds the conduction threshold of the path switch MSP (for example, at the initial time point T1, the gate voltage VG exceeds the conduction threshold Vthg), the bus voltage VBUS also starts to rise, and the bus current IBUS also starts to rise.

[0101] Next, after the path switch MSP is conducting to a certain extent, the bus voltage VBUS reaches the same level as the relay output power supply VM (for example, near T2a), and the bus current IBUS also tends to be stable during this process. In addition, the gate voltage VG will continue to rise to the optimal level, which is related to the level of the bus voltage VBUS and the required on-resistance value of the path switch MSP by the system. In one view, the output voltage of the charge pump circuit 130 (i.e., the gate voltage VG) is a programmable voltage, so it can support soft start and adaptively set its final value according to the level of the bus voltage VBUS and the target on-resistance value of the path switch MSP.

[0102] Continue to refer to Figure 3 , specifically, the aforementioned initial time point T1 can be the time point when the gate voltage VG rises to reach the conduction threshold Vthg of the path switch MSP, or the time point when the bus voltage VBUS rises to reach a threshold Vthr, where the selection of the threshold Vthr can indicate that the bus voltage VBUS has been confirmed to start rising.

[0103] In addition to providing various methods for judging overcurrent (OC), the present invention also has another important function, that is, to judge whether the current sensing resistor RCS is faulty by the contradiction between two sets of information. The following specifically describes embodiments of various methods for judging the fault of the current sensing resistor RCS according to the present invention.

[0104] Please continue to refer to Figure 3 , at the judgment time point TC, the transmission control circuit 120 can measure the current level VNCT_TC of the transmission end communication node. If VNCT_TC is greater than a threshold VTH1, and at the same time the current sensing voltage VCS is less than another threshold VTH3, the transmission control circuit 120 can judge that the current sensing resistor RCS is faulty (for example, short-circuited), and turn off the path switch MSP.

[0105] The above judgment is based on the following logic: when the current level VNCT_TC of the transmitting communication node is greater than the threshold VTH1, it indicates that the bus current IBUS is quite large; however, if the current sensing voltage VCS is less than the threshold VTH3, which means that the current flowing through the current sensing resistor RCS seems to be very small, there is a contradiction between the two pieces of information. Therefore, the transmission control circuit 120 can infer that the current sensing resistor RCS may be faulty. Since a fault in the current sensing resistor RCS may lead to inaccurate current sensing, the best measure is to turn off the path switch MSP to protect the system.

[0106] In this embodiment, the threshold VTH1 corresponds to the level of the bus current IBUS being IBUS1, and the threshold VTH3 corresponds to the level of the bus current IBUS being IBUS3. In one embodiment, the current level IBUS1 is greater than or equal to the current level IBUS3.

[0107] In another embodiment, at the judgment time point TC, the transmission control circuit 120 can determine whether the current sensing resistor RCS is faulty based on whether there is a contradiction between the difference Vdiff between VNCT_TC and VNCT_T1 (i.e., Vdiff = VNCT_TC - VNCT_T1) and the current sensing voltage VCS. Specifically, if the above difference Vdiff is greater than a threshold VTH2, and at the same time the current sensing voltage VCS is less than another threshold VTH3, the transmission control circuit 120 can determine that the current sensing resistor RCS is faulty (e.g., short-circuited) and turn off the path switch MSP.

[0108] In this embodiment, the threshold VTH2 corresponds to the level of the bus current IBUS being IBUS2, and the threshold VTH3 corresponds to the level of the bus current IBUS being IBUS3. In one embodiment, the current level IBUS2 is greater than or equal to the current level IBUS3.

[0109] Figures 6 to 9 Show the operation flowcharts of the power conversion and transmission system in several embodiments of the present invention. The following describes the method steps for controlling the power conversion and transmission system to perform power limiting through these several flowcharts.

[0110] Refer to Figure 6 , in this embodiment, after the power limiting method starts, first enter step S10: determine whether the power transmitting unit 10 and the load unit 20 are coupled to each other.

[0111] If it is determined in step S10 that the coupling is successful, then enter step S20: enable the output control signal EN. Then, enter step S30: sense the current level VNCT_TC of the transmitting communication node voltage VNCT at the judgment time point TC after the readiness time point T2.

[0112] Next, enter step S40: Determine whether the current level VNCT_TC exceeds the threshold VTH1. If the current level VNCT_TC is greater than a threshold VTH1, it indicates that overcurrent or other abnormal conditions may have occurred. In this case, enter step S50: Activate power supply limitation; otherwise, return to step S30 to continue sensing the current level of VNCT_TC.

[0113] Figure 7 The power supply limitation method shown is similar to Figure 6 the method shown, with the difference being that: in Figure 7 the embodiment of, after step S20 (output control signal EN is enabled), enter step S25. In S25, sense and record the initial voltage level VNCT_T1 of the transmitting end communication node voltage VNCT at the initial time point T1. Then, after step S25, enter step S30, and sense the current level VNCT_TC of the transmitting end communication node voltage VNCT at the judgment time point TC after the readiness time point T2.

[0114] After step S30, enter step S401, and determine whether the difference between the current level VNCT_TC and the initial voltage level VNCT_T1 is greater than VTH2. If the difference is greater than a threshold VTH2, then enter step S50 to activate power supply limitation; otherwise, return to step S30 to continue sensing the current level of VNCT_TC.

[0115] Figure 8 The power supply limitation method shown is similar to Figure 6 the method shown, with the difference being that: after step S20 (output control signal EN is enabled), enter step S301. In step S301, in addition to sensing the current level VNCT_TC of the transmitting end communication node voltage VNCT at the judgment time point TC after the readiness time point T2, also sense the current level VCS_TC of the current sensing signal VCS at the same time.

[0116] Then, after step S301, enter step S401. In S401, determine whether VNCT_TC is greater than VTH1 and whether VCS_TC is less than VTH3. If both of these conditions are met (i.e., VNCT_TC is greater than VTH1 and VCS_TC is less than VTH3), then enter step S50 to activate power supply limitation; if the conditions are not met, return to step S301 to continue sensing.

[0117] Figure 9 The power supply limitation method shown is similar to Figure 7The method shown is similar, with the difference being that after step S25 (sensing the initial level of VNCT_T1), step S301 is entered. At the determination time point TC after the readiness time point T2, the current level VNCT_TC of VNCT is sensed, and at the same time, the current level VCS_TC of the current sensing signal VCS is also sensed.

[0118] Then, after step S301, step S403 is entered. In S403, it is judged whether the difference Vdiff between VNCT_TC and VNCT_T1 is greater than VTH2, and at the same time, it is judged whether VCS_TC is less than VTH3. If both of these conditions are met, step S50 to activate power limitation is entered; if the two conditions are not fully met, the process returns to step S301 to continue sensing.

[0119] Figure 8 Similar to Figure 9 the method shown, both judge whether there is a contradiction through two pieces of information respectively from the current sensing signal VCS and the voltage VNCT of the sending - end communication node. When VNCT shows that the bus current is relatively large while the current sensing signal VCS shows a low current, this may indicate that the current sensing resistor RCS has short - circuited, so it is necessary to enter step S50 to activate power limitation.

[0120] The present invention has been described above with respect to preferred embodiments. However, the above description is only for making those skilled in the art easily understand the content of the present invention and is not intended to limit the scope of the rights of the present invention. Each of the described embodiments is not limited to being applied alone and can also be combined. For example, two or more embodiments can be combined, and some components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the so - called "processing or operating or generating a certain output result according to a certain signal" in the present invention is not limited to the signal itself, but also includes, when necessary, converting the signal between voltage and current, current and voltage, and / or ratio conversion, etc., and then processing or operating according to the converted signal to generate a certain output result. Thus, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combination methods, which are not listed one by one here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A power conversion and transmission system, comprising: A power supply unit, comprising: A power conversion circuit for converting an input power into a relay output power; a charge pump circuit for generating a gate voltage; a transmission control circuit for controlling the power conversion circuit and generating an output control signal for controlling the charge pump circuit; as well as a path switch, coupled between the relay output power supply and a bus power supply, and controlled by the gate voltage to turn on or off the electrical connection between the relay output power supply and the bus power supply, wherein the path switch comprises an N-type MOSFET; A load unit is coupled between the bus power source and a load-end ground node, wherein the bus power source is used to supply power to the load unit, and the load unit determines a bus current of the bus power source; as well as a cable, comprising a power sub-cable, a communication sub-cable and a ground sub-cable, for selectively coupling a sending-end power node, a sending-end communication node and a sending-end ground node of the power sending unit to a load-end power node, a load-end communication node and a load-end ground node of the load unit, respectively, wherein the bus current flows through the power sub-cable and the ground sub-cable; At a determination time point, the transmission control circuit senses a current voltage level of the transmission end communication node, and if the current voltage level exceeds a first threshold, a power limiting operation is initiated; or At the determination time point, the transmission control circuit calculates a difference between the current voltage level and an initial voltage level, and if the difference exceeds a second threshold, the power limiting operation is initiated, wherein the transmission control circuit senses a voltage of the transmitting end communication node at an initial time point and records it as the initial voltage level; The time point when the output control signal is enabled is earlier than the initial time point and the judgment time point, wherein the initial time point is earlier than the judgment time point; In the power limiting operation, the sending control circuit controls the path switch to be turned off to stop supplying power to the load unit, or controls the path switch to limit the power level or current level of the bus power.

2. The power conversion and transmission system according to claim 1, wherein: The ground sub-cable has a parasitic resistance.

3. The power conversion and transmission system according to claim 1, wherein: The load unit has a resistive device coupled between the load-end communication node and the load-end ground node.

4. The power conversion and transmission system according to claim 1, wherein: The level of the gate voltage generated by the charge pump circuit is programmable.

5. The power conversion and transmission system according to claim 1, wherein: Also includes a current sensing resistor, disposed on the current path of the bus current, for generating a current sensing voltage proportional to the bus current; Wherein, at the judgment time point, when the voltage level of the current sensing resistor is lower than a third threshold value, the sending control circuit starts the power limiting operation; The level of the bus current indicated by the first threshold is greater than or equal to the level of the bus current indicated by the third threshold, or the level of the bus current indicated by the second threshold is greater than or equal to the level of the bus current indicated by the third threshold.

6. The power conversion and transmission system according to claim 1, wherein: The judgment time point occurs after a ready time point; The ready time point is the time point when the bus voltage rises to a steady-state voltage; or The ready time point is the time point when the gate voltage of the path switch rises to a final value voltage.

7. The power conversion and transmission system according to claim 6, wherein: The judgment time points are multiple time points that are periodically triggered after the ready time point, or the judgment time points are continuous time after the ready time point.

8. A method for controlling a power conversion and transmission system, the power conversion and transmission system comprising a power transmission unit, a load unit and a cable, the power transmission unit comprising: A power conversion circuit for converting an input power into a relay output power; and a path switch coupled between the relay output power supply and a bus power supply, for conducting or disconnecting the electrical connection between the relay output power supply and the bus power supply; wherein the load unit is coupled between the bus power supply and a load-end grounding node, wherein the bus power supply is used to supply power to the load unit, and the load unit determines a bus current of the bus power supply; wherein the cable includes a power sub-cable, a communication sub-cable and a grounding sub-cable, for selectively coupling a sending-end power node, a sending-end communication node and a sending-end grounding node of the power sending unit to a load-end power node, a load-end communication node and a load-end grounding node of the load unit, respectively, wherein the bus current flows through the power sub-cable and the grounding sub-cable; the method comprises: Start the enable of the path switch; At a determination time point, sensing a current voltage level of the transmitting communication node; and If the current voltage level exceeds a first threshold, a power limiting operation is initiated; or Start the enable of the path switch; At a determination time point, calculating a difference between the current voltage level and an initial voltage level; as well as If the difference exceeds a second threshold, the power limiting operation is initiated; The voltage of the transmitting end communication node at an initial time point corresponds to the initial voltage level; The enabling time point of starting the path switch is earlier than the initial time point and the determination time point, wherein the initial time point is earlier than the determination time point; The steps of the power limiting operation include: The path switch is controlled to be turned off to stop supplying power to the load unit, or the path switch is controlled to limit the power level or current level of the bus power.

9. The method of claim 8, wherein: The step of starting the enabling of the path switch includes: controlling the path switch to be turned on by soft start.

10. The method of claim 8, wherein: The power conversion and transmission system further includes a current sensing resistor, which is disposed on the current path of the bus current and is used to generate a current sensing voltage proportional to the bus current; The method further comprises: At the determination time point, the power limiting operation is initiated only when the voltage level of the current sensing resistor is lower than a third threshold value; The level of the bus current indicated by the first threshold is greater than or equal to the level of the bus current indicated by the third threshold, or the level of the bus current indicated by the second threshold is greater than or equal to the level of the bus current indicated by the third threshold.

11. The method of claim 8, wherein: The judgment time point occurs after a ready time point; The ready time point is the time point when the bus voltage rises to a steady-state voltage; or The ready time point is the time point when the gate voltage of the path switch rises to a final value voltage.

12. The method of claim 11, wherein: The judgment time points are multiple time points that are periodically triggered after the ready time point, or the judgment time points are continuous time after the ready time point.

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