Charging electric drive multiplexing circuit for heavy-load engineering vehicle

Abstract

The invention relates to the technical field of electronics, and discloses a heavy-load engineering vehicle charging electric drive multiplexing circuit which comprises a power frequency rectifying unit, a first switch, an energy conversion unit, a second switch, a third switch, a fourth switch and a control unit. A driving control module of the control unit controls a first switch, a third switch and a fourth switch to be switched off and a second switch to be switched on, so that energy output by a vehicle-mounted storage battery is output after passing through an energy conversion unit to drive a three-phase motor to rotate; a charging control module of the control unit controls a first switch, a third switch, a fourth switch and a first MOS tube in the energy conversion unit to be switched on and a second switch to be switched off, the energy conversion unit is simplified to be a buck converter, and a winding of a three-phase motor is multiplexed to be an energy storage inductor. An external power frequency alternating current passes through the power frequency rectification unit, the buck converter and the energy storage inductor to charge a vehicle-mounted storage battery.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, and in particular to a charging and electric drive multiplexing circuit for high-load engineering vehicles. Background Technology

[0002] The electrification of heavy-duty engineering vehicles is becoming increasingly common, such as forklifts, scissor lifts, and transport vehicles. The motor drivers of this series of vehicles are characterized by low input DC voltage but high output current. The input DC voltage is generally 36V to 144V, and the maximum output current can reach 800A.

[0003] Reference Figure 1 The diagram shows the topology of a traditional motor driver. The battery converts electrical energy into kinetic energy through an energy conversion unit to drive the motor. The energy conversion unit is a three-phase full-bridge converter. Since the battery voltage of electric engineering vehicles is up to 144V, the power devices in the energy conversion unit only need to withstand 200V.

[0004] High-load electric engineering vehicles are mostly charged using AC 220V, refer to Figure 2 The diagram shows the structure of a charger for a high-load electric engineering vehicle. The AC 220V is rectified by the power frequency and then by the high-frequency inverter to charge the battery. The high-frequency inverter rectification unit is a full-bridge converter. The AC 220V is rectified by the power frequency to become DC 300V. Due to the parasitic parameters of the circuit and components, the withstand voltage of the power devices in the high-frequency inverter rectification unit is 600V.

[0005] As the requirements for cost and size of heavy-load electric engineering vehicles become increasingly stringent, motor drivers and chargers, as essential components of every heavy-load electric engineering vehicle, occupy a significant amount of space. In traditional solutions, the two systems exist separately, resulting in redundant components, large size, and high cost, which is detrimental to vehicle lightweighting and cost control. Some existing multiplexed circuits, in order to achieve reuse, mostly only reconstruct the circuit path by adding a large number of switching devices. This makes the topology cumbersome, the control logic extremely complex, and the reuse incomplete. Therefore, they are still insufficient in reducing the size and cost of heavy-load engineering vehicles. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the inability of the prior art to effectively reduce the size and cost of heavy-load engineering vehicles by reusing drive and charging circuits.

[0007] To solve the above-mentioned technical problems, the present invention provides a charging and electric drive multiplexing circuit for high-load engineering vehicles, comprising: The power frequency rectifier unit has its first AC input terminal and second AC input terminal connected in parallel to the two ends of an external power frequency AC power supply, converting the power frequency AC power into DC power output; The first switch has its input terminal connected to the positive output terminal of the power frequency rectifier unit, and its output terminal connected to the positive terminal of the DC bus. The energy conversion unit has its first phase input terminal connected to the positive terminal of the DC bus and its third phase input terminal connected to the negative terminal of the DC bus. It is used to convert DC power into three-phase AC power when there is DC power input, and output it to the three-phase motor of the heavy-load engineering vehicle through the three-phase output terminal. The second switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the positive terminal of the DC bus; wherein, the negative terminal of the on-board battery is connected to the negative terminal of the DC bus. The third switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the second phase input terminal of the energy conversion unit. The fourth switch has its input terminal connected to the negative output terminal of the power frequency rectifier unit, and its output terminal connected to the negative terminal of the DC bus. The control unit, which is communicatively connected to the first switch, second switch, third switch, fourth switch, and energy conversion unit, includes: The drive control module is used to control the first, third, and fourth switches to open and the second switch to close, so that the energy output from the vehicle battery is output after passing through the energy conversion unit to drive the three-phase motor of the heavy-load engineering vehicle to rotate. The charging control module is used to control the first switch, the third switch, the fourth switch and the first MOSFET in the energy conversion unit to close and the second switch to open. It simplifies the energy conversion unit into a step-down converter and reuses the windings of the three-phase motor as an energy storage inductor, so that the external power frequency AC power can charge the vehicle battery through the power frequency rectifier unit, the step-down converter and the energy storage inductor.

[0008] Preferably, the control unit controls the first switch, the third switch, and the fourth switch to open, and the second switch to close. At this time: The first phase input terminal of the energy conversion unit is connected to the positive terminal of the on-board battery of a heavy-load engineering vehicle; The second phase input terminal of the energy conversion unit is connected to the negative terminal of the on-board battery of a heavy-load engineering vehicle; The energy output from the on-board battery of the heavy-load engineering vehicle is converted into three-phase alternating current through the energy conversion unit, and then output from the three-phase output terminal to the three-phase motor to drive the three-phase motor to rotate.

[0009] Preferably, the first switch, the third switch, the fourth switch, and the first MOSFET in the energy conversion unit are closed. At this time: The drain of the first MOSFET is connected to the positive output terminal of the power frequency rectifier unit, the source of the first MOSFET is connected to the cathode of the fourth body diode, and the anode of the fourth body diode is connected to the negative output terminal of the power frequency rectifier unit. The three-phase motor of the heavy-load engineering vehicle is used as three energy storage inductors. The first inductor, which is connected to the output terminal of the first phase and the output terminal of the second phase, is connected in series with the second inductor. One end of the first inductor is connected to the source of the first MOSFET, and the other end is connected to the positive terminal of the vehicle battery of the heavy-load engineering vehicle. The negative terminal of the on-board battery of a heavy-load engineering vehicle is connected to the negative output terminal of the power frequency rectifier unit. External AC power is rectified by an AC rectifier unit to output DC power. After passing through a step-down converter composed of a first MOSFET and a fourth body diode, the DC power is converted into a preset voltage to charge the on-board battery of the heavy-load engineering vehicle.

[0010] Preferably, if the heavy-load engineering vehicle is a heavy-load engineering vehicle that supports direct AC power connection, then the control unit further includes: The AC drive module is used to control the second and third switches to be open and the first and fourth switches to be closed, so that the external power frequency AC power is output after passing through the power frequency rectifier unit and the energy conversion unit, driving the three-phase motor of the heavy-load engineering vehicle to rotate.

[0011] Preferably, the heavy-load engineering vehicles that support direct AC power connection include: cranes and loaders.

[0012] Preferably, the second and third switches are disconnected, and the first and fourth switches are closed. At this time: The first AC input terminal and the second AC input terminal of the power frequency rectifier unit are connected in parallel to the two ends of the external power frequency AC power to convert the power frequency AC power into DC power output; The first and third phase input terminals of the energy conversion unit are connected to the positive and negative output terminals of the power frequency rectifier unit, respectively, to convert the DC power output by the power frequency rectifier unit into three-phase AC power, which is then output from the three-phase output terminal of the energy conversion unit to the three-phase motor of the heavy-load engineering vehicle to drive the three-phase motor to rotate.

[0013] Preferably, the power frequency rectifier unit includes: The first diode has its anode connected to one end of an external power frequency AC current, and its cathode connected to the input terminal of the first switch. The second diode has its anode connected to the other end of the external power frequency AC current, and its cathode connected to the input terminal of the first switch. The anode of the third diode is connected to the input terminal of the fourth switch, and the cathode is connected to one end of the external power frequency AC power. The fourth diode has its anode connected to the input terminal of the fourth switch, and its cathode connected to the other end of the external power frequency AC power supply.

[0014] Preferably, the energy conversion unit is a three-phase full-bridge converter.

[0015] Preferably, the energy conversion unit includes an upper bridge arm and a lower bridge arm, wherein: The upper bridge arm includes: The first MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The first body diode is connected in parallel across the first MOS transistor, with its anode connected to the source of the first MOS transistor and its cathode connected to the drain of the first MOS transistor. The second MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The second body diode is connected in parallel across the second MOSFET, with its anode connected to the source of the second MOSFET and its cathode connected to the drain of the second MOSFET. The third MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The third body diode is connected in parallel across the third MOSFET, with its anode connected to the source of the third MOSFET and its cathode connected to the drain of the third MOSFET. The lower bridge arm includes: The fourth MOSFET has its drain connected to the source of the first MOSFET, and the connection point serves as the third phase output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fourth body diode is connected in parallel across the fourth MOSFET, with its anode connected to the source of the fourth MOSFET and its cathode connected to the drain of the fourth MOSFET. The fifth MOSFET has its drain connected to the source of the second MOSFET, and the connection point serves as the second output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fifth body diode is connected in parallel across the fifth MOSFET, with its anode connected to the source of the fifth MOSFET and its cathode connected to the drain of the fifth MOSFET. The sixth MOSFET has its drain connected to the source of the third MOSFET, and the connection point serves as the first output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The sixth body diode is connected in parallel across the sixth MOS transistor, with its anode connected to the source of the sixth MOS transistor and its cathode connected to the drain of the sixth MOS transistor.

[0016] Preferably, when the energy output from the vehicle battery drives the three-phase motor of a heavy-load engineering vehicle through the energy conversion unit, the method includes: taking any MOSFET in the upper arm of the energy conversion unit and any MOSFET in the lower arm that does not belong to the same phase as the MOSFET as the MOSFET, as a group of MOSFET units, and adjusting the duty cycle of the two MOSFETs in each group of MOSFET units to control the magnitude of the three-phase AC power output by the energy conversion unit.

[0017] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0018] When performing its driving function, this invention disconnects the first switch, cutting off the connection between the power frequency rectifier unit and the positive terminal of the DC bus, ensuring complete electrical isolation between the high-voltage grid and the vehicle system during driving, thus guaranteeing safety. The second switch is closed, directly connecting the positive terminal of the vehicle battery to the positive terminal of the DC bus, providing the DC power required for the energy conversion unit's drive. The third and fourth switches are disconnected, breaking the charging circuit and preventing high voltage or high current interference with the charging path during driving. The energy conversion unit is then controlled to invert the DC power provided by the vehicle battery into three-phase AC power with adjustable frequency and amplitude, directly outputting it to the windings of the three-phase motor to control the motor speed, thereby achieving the driving functions of heavy-load engineering vehicles, such as driving and lifting. In this case, the invention uses the energy conversion unit as an inverter, achieving functional reuse with its function as a step-down converter in the charging function. This eliminates the need for an independent motor driver, simplifying the system structure, improving component utilization, and reducing the size and cost of the reused circuitry.

[0019] When performing its charging function, this invention closes the first switch, allowing the high-voltage direct current generated from external AC power after rectification to be connected to the positive terminal of the internal DC bus, providing the energy source for the entire charging process. Disconnecting the second switch physically isolates the vehicle battery from the direct connection to the positive terminal of the DC bus, preventing high-voltage electricity from impacting the battery and ensuring the safety and controllability of the charging process. Closing the third and fourth switches connects the positive and negative terminals of the battery to the output of the energy conversion unit, forming a complete closed-loop charging energy circuit. At this point, the components in the energy conversion unit are disassembled and reassembled, allowing the energy conversion unit to function as a step-down converter, and reusing the windings of the three-phase motor as energy storage inductors in the step-down converter. This invention controls the states of the four switches and the MOSFETs in the energy conversion unit, connecting two phases of the three-phase motor windings in series, forming a step-down converter with the first MOSFET and the fourth body diode, thus achieving battery charging control. The reuse of the windings as energy storage inductors significantly reduces the size and weight of the entire multiplexed circuit.

[0020] The charging and driving multiplexing circuit for heavy-load engineering vehicles described in this invention achieves switching between charging and driving functions based on the power frequency rectifier unit and the energy conversion unit through the combined use of the first, second, third, and fourth switches, thus realizing functional multiplexing. This invention achieves device-level multiplexing by directly reusing the three-phase motor windings as the energy storage inductor during charging, eliminating the need for additional inductors, reducing circuit size, and lowering costs. Simultaneously, reusing the same energy conversion unit for both energy conversion during motor drive and for constructing a step-down converter during charging further reduces circuit size and improves component utilization. Furthermore, the reduction in the number of components directly lowers the circuit failure rate and improves the reliability of charging and driving heavy-load engineering vehicles.

[0021] When applied to heavy-load engineering vehicles that can be directly connected to external power frequency AC, this invention closes the first and fourth switches to connect the high-voltage DC output from the power frequency rectifier to the positive and negative terminals of the DC bus, establishing a complete DC bus circuit. The second switch is then disconnected to cut off the connection between the vehicle's onboard battery and the drive circuit, preventing battery power supply. The third switch is then disconnected to cut off the battery charging circuit. At this time, the power frequency rectifier unit converts the AC power to DC power and supplies it to the DC bus. The energy conversion unit operates as a standard three-phase inverter. The control unit controls the switching on and off of the MOSFETs in the energy conversion unit to convert the DC bus power into three-phase AC power with adjustable frequency and voltage, directly driving the three-phase motor to operate, thereby enabling cranes, loaders, etc., to perform lifting, luffing, and other actions. The vehicle battery does not participate in the work at all during the entire process and remains in a static state, neither being consumed nor charged. Therefore, in situations where heavy-load engineering vehicles can be directly connected to external AC power and have a fixed power supply, using AC power can completely avoid the use of batteries, saving charge and discharge cycles, greatly extending battery life, reducing maintenance and replacement costs, and also avoiding performance degradation caused by battery charge reduction, thus improving energy utilization. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a topology diagram of a traditional motor driver; Figure 2 This is a schematic diagram of the charger structure for high-load electric engineering vehicles; Figure 3 This is a topology diagram of the high-load engineering vehicle charging and electric drive multiplexing circuit of the present invention; Figure 4 This is a topology diagram of the charging and electric drive multiplexing circuit of a heavy-load engineering vehicle when it utilizes the on-board battery drive function. Figure 5 This is a topology diagram of the charging electric drive multiplex circuit of a heavy-load engineering vehicle when it performs the charging function. Figure 6 This is a simplified topology diagram of the charging electric drive multiplex circuit for heavy-load engineering vehicles when it performs the charging function. Figure 7 This is a topology diagram of the charging and electric drive multiplexing circuit for heavy-load engineering vehicles when it performs the function of direct AC drive. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0024] Reference Figure 3 The diagram shows the topology of the high-load engineering vehicle charging and electric drive multiplexing circuit of the present invention. The specific structure includes: The power frequency rectifier unit has its first AC input terminal and second AC input terminal connected in parallel to the two ends of an external power frequency AC power supply, converting the power frequency AC power into DC power output; The first switch has its input terminal connected to the positive output terminal of the power frequency rectifier unit, and its output terminal connected to the positive terminal of the DC bus. The energy conversion unit has its first phase input terminal connected to the positive terminal of the DC bus and its third phase input terminal connected to the negative terminal of the DC bus. It is used to convert DC power into three-phase AC power when there is DC power input, and output it to the three-phase motor of the heavy-load engineering vehicle through the three-phase output terminal. The second switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the positive terminal of the DC bus; wherein, the negative terminal of the on-board battery is connected to the negative terminal of the DC bus. The third switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the second phase input terminal of the energy conversion unit. The fourth switch has its input terminal connected to the negative output terminal of the power frequency rectifier unit, and its output terminal connected to the negative terminal of the DC bus. The control unit, which is communicatively connected to the first switch, second switch, third switch, fourth switch, and energy conversion unit, includes: The drive control module is used to control the first, third, and fourth switches to open and the second switch to close, so that the energy output from the vehicle battery is output after passing through the energy conversion unit to drive the three-phase motor of the heavy-load engineering vehicle to rotate. The charging control module is used to control the first switch, the third switch, the fourth switch and the first MOSFET in the energy conversion unit to close and the second switch to open. It simplifies the energy conversion unit into a step-down converter and reuses the windings of the three-phase motor as an energy storage inductor, so that the external power frequency AC power can charge the vehicle battery through the power frequency rectifier unit, the step-down converter and the energy storage inductor.

[0025] In this embodiment, the drive control module controls the first switch, the third switch, and the fourth switch to open. After the second switch is closed, the following is included: The first phase input terminal of the energy conversion unit is connected to the positive terminal of the on-board battery of a heavy-load engineering vehicle; The second phase input terminal of the energy conversion unit is connected to the negative terminal of the on-board battery of a heavy-load engineering vehicle; The energy output from the on-board battery of the heavy-load engineering vehicle is converted into three-phase alternating current through the energy conversion unit, and then output from the three-phase output terminal to the three-phase motor to drive the three-phase motor to rotate.

[0026] When performing its driving function, this invention disconnects the first switch, cutting off the connection between the power frequency rectifier unit and the positive terminal of the DC bus, ensuring complete electrical isolation between the high-voltage grid and the vehicle system during driving, thus guaranteeing safety. The second switch is closed, directly connecting the positive terminal of the vehicle battery to the positive terminal of the DC bus, providing the DC power required for the energy conversion unit's drive. The third and fourth switches are disconnected, breaking the charging circuit and preventing high voltage or high current interference with the charging path during driving. The energy conversion unit is then controlled to invert the DC power provided by the vehicle battery into three-phase AC power with adjustable frequency and amplitude, directly outputting it to the windings of the three-phase motor to control the motor speed, thereby achieving the driving functions of heavy-load engineering vehicles, such as driving and lifting. In this case, the invention uses the energy conversion unit as an inverter, achieving functional reuse with its function as a step-down converter in the charging function. This eliminates the need for an independent motor driver, simplifying the system structure, improving component utilization, and reducing the size and cost of the reused circuitry.

[0027] In this embodiment, the charging control module controls the first switch, the third switch, the fourth switch, and the first MOSFET in the energy conversion unit to close. After the second switch opens, the following is included: The drain of the first MOSFET is connected to the positive output terminal of the power frequency rectifier unit, the source of the first MOSFET is connected to the cathode of the fourth body diode, and the anode of the fourth body diode is connected to the negative output terminal of the power frequency rectifier unit. The three-phase motor of the heavy-load engineering vehicle is used as three energy storage inductors. The first inductor, which is connected to the output terminal of the first phase and the output terminal of the second phase, is connected in series with the second inductor. One end of the first inductor is connected to the source of the first MOSFET, and the other end is connected to the positive terminal of the vehicle battery of the heavy-load engineering vehicle. The negative terminal of the on-board battery of a heavy-load engineering vehicle is connected to the negative output terminal of the power frequency rectifier unit. External AC power is rectified by an AC rectifier unit to output DC power. After passing through a step-down converter composed of a first MOSFET and a fourth body diode, the DC power is converted into a preset voltage to charge the on-board battery of the heavy-load engineering vehicle.

[0028] When performing its charging function, this invention closes the first switch, allowing the high-voltage direct current generated from external AC power after rectification to be connected to the positive terminal of the internal DC bus, providing the energy source for the entire charging process. Disconnecting the second switch physically isolates the vehicle battery from the direct connection to the positive terminal of the DC bus, preventing high-voltage electricity from impacting the battery and ensuring the safety and controllability of the charging process. Closing the third and fourth switches connects the positive and negative terminals of the battery to the output of the energy conversion unit, forming a complete closed-loop charging energy circuit. At this point, the components in the energy conversion unit are disassembled and reassembled, allowing the energy conversion unit to function as a step-down converter, and reusing the windings of the three-phase motor as energy storage inductors in the step-down converter. This invention controls the states of the four switches and the MOSFETs in the energy conversion unit, connecting two phases of the three-phase motor windings in series, forming a step-down converter with the first MOSFET and the fourth body diode, thus achieving battery charging control. The reuse of the windings as energy storage inductors significantly reduces the size and weight of the entire multiplexed circuit.

[0029] Specifically, in this embodiment of the invention, if the heavy-load engineering vehicle is a heavy-load engineering vehicle that supports direct AC power connection, then the control unit further includes: The AC drive module is used to control the second and third switches to be open and the first and fourth switches to be closed, so that the external power frequency AC power is output after passing through the power frequency rectifier unit and the energy conversion unit, driving the three-phase motor of the heavy-load engineering vehicle to rotate.

[0030] At this time, the first AC input terminal and the second AC input terminal of the power frequency rectifier unit are connected in parallel to the two ends of the external power frequency AC power, converting the power frequency AC power into DC power output; the first phase input terminal and the third phase input terminal of the energy conversion unit are respectively connected to the positive output terminal and the negative output terminal of the power frequency rectifier unit, converting the DC power output by the power frequency rectifier unit into three-phase AC power, which is output from the three-phase output terminal of the energy conversion unit to the three-phase motor of the heavy-load engineering vehicle, driving the three-phase motor to rotate.

[0031] Heavy-load engineering vehicles that support direct AC power connection, including cranes and loaders.

[0032] The charging and driving multiplexing circuit for heavy-load engineering vehicles described in this invention achieves switching between charging and driving functions based on the power frequency rectifier unit and the energy conversion unit through the combined use of the first, second, third, and fourth switches, thus realizing functional multiplexing. This invention achieves device-level multiplexing by directly reusing the three-phase motor windings as the energy storage inductor during charging, eliminating the need for additional inductors, reducing circuit size, and lowering costs. Simultaneously, reusing the same energy conversion unit for both energy conversion during motor drive and for constructing a step-down converter during charging further reduces circuit size and improves component utilization. Furthermore, the reduction in the number of components directly lowers the circuit failure rate and improves the reliability of charging and driving heavy-load engineering vehicles.

[0033] Specifically, in this embodiment of the invention, the power frequency rectifier unit includes: The first diode D1 has its anode connected to one end of the external power frequency AC current, and its cathode connected to the input terminal of the first switch. The second diode D2 has its anode connected to the other end of the external power frequency AC current, and its cathode connected to the input terminal of the first switch. The third diode D3 has its anode connected to the input terminal of the fourth switch and its cathode connected to one end of the external power frequency AC power. The fourth diode, D4, has its anode connected to the input terminal of the fourth switch, and its cathode connected to the other end of the external power frequency AC current.

[0034] Specifically, in this embodiment of the invention, the energy conversion unit is a three-phase full-bridge converter, comprising an upper bridge arm and a lower bridge arm, wherein: The upper bridge arm includes: The first MOSFET Z1 has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The first body diode D5 is connected in parallel across the first MOS transistor, with its anode connected to the source of the first MOS transistor and its cathode connected to the drain of the first MOS transistor. The second MOSFET Z2 has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The second body diode D6 is connected in parallel across the second MOSFET, with its anode connected to the source of the second MOSFET and its cathode connected to the drain of the second MOSFET. The third MOSFET Z3 has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The third-body diode D7 is connected in parallel across the third MOSFET, with its anode connected to the source of the third MOSFET and its cathode connected to the drain of the third MOSFET. The lower bridge arm includes: The fourth MOSFET Z4 has its drain connected to the source of the first MOSFET, and the connection point serves as the third phase output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fourth body diode D8 is connected in parallel across the fourth MOSFET, with its anode connected to the source of the fourth MOSFET and its cathode connected to the drain of the fourth MOSFET. The fifth MOSFET Z5 has its drain connected to the source of the second MOSFET, and the connection point serves as the second output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fifth body diode D9 is connected in parallel across the fifth MOSFET, with its anode connected to the source of the fifth MOSFET and its cathode connected to the drain of the fifth MOSFET. The sixth MOSFET Z6 has its drain connected to the source of the third MOSFET, and the connection point serves as the first output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The sixth body diode D10 is connected in parallel across the sixth MOSFET, with its anode connected to the source of the sixth MOSFET and its cathode connected to the drain of the sixth MOSFET.

[0035] In this invention, when the energy output from the vehicle battery drives the three-phase motor of a heavy-load engineering vehicle through the energy conversion unit, the method includes: taking any MOS transistor in the upper arm of the energy conversion unit and any MOS transistor in the lower arm that does not belong to the same phase as the MOS transistor as a group of MOS transistor units, and adjusting the duty cycle of the two MOS transistors in each group of MOS transistor units to control the magnitude of the three-phase AC power output by the energy conversion unit.

[0036] The charging and driving multiplexing circuit for heavy-load engineering vehicles described in this invention achieves switching between charging and driving functions based on the power frequency rectifier unit and the energy conversion unit through the combined use of the first, second, third, and fourth switches, thus realizing functional multiplexing. This invention achieves device-level multiplexing by directly reusing the three-phase motor windings as the energy storage inductor during charging, eliminating the need for additional inductors, reducing circuit size, and lowering costs. Simultaneously, reusing the same energy conversion unit for both energy conversion during motor drive and for constructing a step-down converter during charging further reduces circuit size and improves component utilization. Furthermore, the reduction in the number of components directly lowers the circuit failure rate and improves the reliability of charging and driving heavy-load engineering vehicles.

[0037] Based on the above embodiments, in this embodiment of the invention, the functions of driving and charging are reused by changing the switch state. The circuit topology is represented as follows under different switch states:

[0038] ① Complete charging and electric drive multiplexing circuit:

[0039] Reference Figure 3 The diagram shown is a topology diagram of the charging and driving multiplexing circuit for heavy-duty engineering vehicles according to the present invention. The charging and driving multiplexing circuit includes: external power frequency AC (220V AC), power frequency rectifier unit, vehicle battery, three-phase motor, and energy conversion unit. The energy conversion unit is responsible for energy conversion, including the battery outputting kinetic energy to the motor through the energy conversion unit, and also the 220V AC charging of the battery.

[0040] One end of the 220V AC power supply is connected to the anode of D1 and the cathode of D3. The other end of the 220V AC power supply is connected to the anode of D2 and the cathode of D4. The cathode of D1 is connected to the cathode of D2 and also connected to the first switch. The anode of D3 is connected to the anode of D4 and also connected to the fourth switch. The other end of the first switch is connected to the positive terminal V+ of the DC bus, and the other end of the fourth switch is connected to the negative terminal V- of the DC bus. The positive terminal of the vehicle battery is connected to one end of the second switch and one end of the third switch. The negative terminal of the vehicle battery is connected to the negative terminal V- of the DC bus. The other end of the second switch is connected to the positive terminal V+ of the DC bus, and the other end of the third switch is connected to the source of the second MOSFET Z2 in the energy conversion unit. The drains of the first MOSFET Z1, the second MOSFET Z2, and the third MOSFET Z3 are simultaneously connected to the positive terminal V+ of the DC bus. The body diodes D5 and D6 of the first MOSFET Z1, the second MOSFET Z2, and the third MOSFET Z3 are also connected to the source of the second MOSFET Z2. The anodes of transistors 6 and 7 are connected to the positive terminal V+ of the DC bus; the sources of transistors Z4, Z5, and Z6 are simultaneously connected to the negative terminal V- of the DC bus, and the cathodes of the body diodes D8, D9, and D10 of Z4, Z5, and Z6 are connected to the negative terminal V- of the DC bus; the source of transistor Z1 is connected to the anode of the first body diode D5, the drain of transistor Z4, and the cathode of the fourth body diode D8, and is also connected to the W-phase input terminal of the motor; the source of transistor Z2 is connected to the anode of the second body diode D6, the drain of transistor Z5, and the cathode of the fifth body diode D9, and is also connected to the V-phase input terminal of the three-phase motor, and is also connected to one end of the third switch; the source of transistor Z3 is connected to the anode of the third body diode D7, the drain of transistor Z6, and the cathode of the sixth body diode D10, and is also connected to the U-phase input terminal of the motor.

[0041] ② Circuit topology under battery-driven control function: Reference Figure 4 The diagram shows the topology of the charging and electric drive multiplexing circuit for a heavy-load engineering vehicle when it utilizes the on-board battery's driving function. In this circuit, the first, third, and fourth switches are open, the second switch is closed, and the on-board battery converts electrical energy into kinetic energy through the energy conversion unit to drive the three-phase motor.

[0042] ③ Circuit topology under charging control function:

[0043] Reference Figure 5 The diagram shows the topology of the charging electric drive multiplexing circuit for a heavy-load engineering vehicle when it is used for charging. The first, third, and fourth switches are closed, the second switch is open, and the power MOSFETs Z2, Z3, Z4, Z5, and Z6 in the energy conversion unit are disconnected.

[0044] Reference Figure 6 The diagram shown is a simplified topology of the charging and electric drive multiplexing circuit for heavy-load engineering vehicles when it performs the charging function. The motor can be simplified by connecting three inductors L1, L2, L3, L1 and L2 in series, which together with Z1 and D8 form a step-down converter. The AC 220V is rectified to approximately 300V DC by the power frequency rectifier, which controls the power device Z1. The 300V DC is then converted to the set voltage by the step-down converter.

[0045] ④ Circuit topology under AC drive control function:

[0046] Reference Figure 7 The diagram shows the topology of a high-load engineering vehicle charging and electric drive multiplexing circuit when it directly drives the vehicle with AC power. The second and third switches are open, while the first and fourth switches are closed, converting AC power into DC power, which is then output through the energy conversion unit to drive a three-phase motor, thus converting AC energy into mechanical energy. In situations with a fixed external AC power supply, this mode completely eliminates the need for batteries, saving all charge and discharge cycles, greatly extending battery life, and reducing maintenance and replacement costs.

[0047] When performing its driving function, this invention disconnects the first switch, cutting off the connection between the power frequency rectifier unit and the positive terminal of the DC bus, ensuring complete electrical isolation between the high-voltage grid and the vehicle system during driving, thus guaranteeing safety. The second switch is closed, directly connecting the positive terminal of the vehicle battery to the positive terminal of the DC bus, providing the DC power required for the energy conversion unit's drive. The third and fourth switches are disconnected, breaking the charging circuit and preventing high voltage or high current interference with the charging path during driving. The energy conversion unit is then controlled to invert the DC power provided by the vehicle battery into three-phase AC power with adjustable frequency and amplitude, directly outputting it to the windings of the three-phase motor to control the motor speed, thereby achieving the driving functions of heavy-load engineering vehicles, such as driving and lifting. In this case, the invention uses the energy conversion unit as an inverter, achieving functional reuse with its function as a step-down converter in the charging function. This eliminates the need for an independent motor driver, simplifying the system structure, improving component utilization, and reducing the size and cost of the reused circuitry. When performing its charging function, this invention closes the first switch, allowing the high-voltage direct current generated from external AC power after rectification to be connected to the positive terminal of the internal DC bus, providing the energy source for the entire charging process. Disconnecting the second switch physically isolates the vehicle battery from the direct connection to the positive terminal of the DC bus, preventing high-voltage electricity from impacting the battery and ensuring the safety and controllability of the charging process. Closing the third and fourth switches connects the positive and negative terminals of the battery to the output of the energy conversion unit, forming a complete closed-loop charging energy circuit. At this point, the components in the energy conversion unit are disassembled and reassembled, allowing the energy conversion unit to function as a step-down converter, and reusing the windings of the three-phase motor as energy storage inductors in the step-down converter. This invention controls the states of the four switches and the MOSFETs in the energy conversion unit, connecting two phases of the three-phase motor windings in series, forming a step-down converter with the first MOSFET and the fourth body diode, thus achieving battery charging control. The reuse of the windings as energy storage inductors significantly reduces the size and weight of the entire multiplexed circuit. When applied to heavy-load engineering vehicles that can be directly connected to external power frequency AC, this invention closes the first and fourth switches to connect the high-voltage DC output from the power frequency rectifier to the positive and negative terminals of the DC bus, establishing a complete DC bus circuit. The second switch is then disconnected to cut off the connection between the vehicle's onboard battery and the drive circuit, preventing battery power supply. The third switch is then disconnected to cut off the battery charging circuit. At this time, the power frequency rectifier unit converts the AC power to DC power and supplies it to the DC bus. The energy conversion unit operates as a standard three-phase inverter. The control unit controls the switching on and off of the MOSFETs in the energy conversion unit to convert the DC bus power into three-phase AC power with adjustable frequency and voltage, directly driving the three-phase motor to operate, thereby enabling cranes, loaders, etc., to perform lifting, luffing, and other actions.The vehicle battery does not participate in the work at all during the entire process and remains in a static state, neither being consumed nor charged. Therefore, in situations where heavy-load engineering vehicles can be directly connected to external AC power and have a fixed power supply, using AC power can completely avoid the use of batteries, saving charge and discharge cycles, greatly extending battery life, reducing maintenance and replacement costs, and also avoiding performance degradation caused by battery charge reduction, thus improving energy utilization.

[0048] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0049] 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 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0050] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0051] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0052] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A charging and electric drive multiplexing circuit for high-load engineering vehicles, characterized in that, include: The power frequency rectifier unit has its first AC input terminal and second AC input terminal connected in parallel to the two ends of an external power frequency AC power supply, converting the power frequency AC power into DC power output; The first switch has its input terminal connected to the positive output terminal of the power frequency rectifier unit, and its output terminal connected to the positive terminal of the DC bus. The energy conversion unit has its first phase input terminal connected to the positive terminal of the DC bus and its third phase input terminal connected to the negative terminal of the DC bus. It is used to convert DC power into three-phase AC power when there is DC power input, and output it to the three-phase motor of the heavy-load engineering vehicle through the three-phase output terminal. The second switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the positive terminal of the DC bus; wherein, the negative terminal of the on-board battery is connected to the negative terminal of the DC bus. The third switch has its input terminal connected to the positive terminal of the on-board battery of the heavy-load engineering vehicle, and its output terminal connected to the second phase input terminal of the energy conversion unit. The fourth switch has its input terminal connected to the negative output terminal of the power frequency rectifier unit, and its output terminal connected to the negative terminal of the DC bus. The control unit, which is communicatively connected to the first switch, second switch, third switch, fourth switch, and energy conversion unit, includes: The drive control module is used to control the first, third, and fourth switches to open and the second switch to close, so that the energy output from the vehicle battery is output after passing through the energy conversion unit to drive the three-phase motor of the heavy-load engineering vehicle to rotate. The charging control module is used to control the first switch, the third switch, the fourth switch and the first MOSFET in the energy conversion unit to close and the second switch to open. It simplifies the energy conversion unit into a step-down converter and reuses the windings of the three-phase motor as an energy storage inductor, so that the external power frequency AC power can charge the vehicle battery through the power frequency rectifier unit, the step-down converter and the energy storage inductor.

2. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 1, characterized in that, The control unit disconnects the first, third, and fourth switches, and closes the second switch. At this time: The first phase input terminal of the energy conversion unit is connected to the positive terminal of the on-board battery of a heavy-load engineering vehicle; The second phase input terminal of the energy conversion unit is connected to the negative terminal of the on-board battery of a heavy-load engineering vehicle; The energy output from the on-board battery of the heavy-load engineering vehicle is converted into three-phase alternating current through the energy conversion unit, and then output from the three-phase output terminal to the three-phase motor to drive the three-phase motor to rotate.

3. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 1, characterized in that, When the first, third, and fourth switches are controlled to close, and the first MOSFET in the energy conversion unit is closed, then: The drain of the first MOSFET is connected to the positive output terminal of the power frequency rectifier unit, the source of the first MOSFET is connected to the cathode of the fourth body diode, and the anode of the fourth body diode is connected to the negative output terminal of the power frequency rectifier unit. The three-phase motor of the heavy-load engineering vehicle is used as three energy storage inductors. The first inductor, which is connected to the output terminal of the first phase and the output terminal of the second phase, is connected in series with the second inductor. One end of the first inductor is connected to the source of the first MOSFET, and the other end is connected to the positive terminal of the vehicle battery of the heavy-load engineering vehicle. The negative terminal of the on-board battery of a heavy-load engineering vehicle is connected to the negative output terminal of the power frequency rectifier unit. External AC power is rectified by an AC rectifier unit to output DC power. After passing through a step-down converter composed of a first MOSFET and a fourth body diode, the DC power is converted into a preset voltage to charge the on-board battery of the heavy-load engineering vehicle.

4. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 1, characterized in that, If the heavy-load engineering vehicle is a heavy-load engineering vehicle that supports direct AC power connection, then the control unit further includes: The AC drive module is used to control the second and third switches to be open and the first and fourth switches to be closed, so that the external power frequency AC power is output after passing through the power frequency rectifier unit and the energy conversion unit, driving the three-phase motor of the heavy-load engineering vehicle to rotate.

5. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 4, characterized in that, Heavy-load engineering vehicles that support direct AC power connection, including cranes and loaders.

6. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 4, characterized in that, When the second and third switches are open and the first and fourth switches are closed, at this time: The first AC input terminal and the second AC input terminal of the power frequency rectifier unit are connected in parallel to the two ends of the external power frequency AC power to convert the power frequency AC power into DC power output; The first and third phase input terminals of the energy conversion unit are connected to the positive and negative output terminals of the power frequency rectifier unit, respectively, to convert the DC power output by the power frequency rectifier unit into three-phase AC power, which is then output from the three-phase output terminal of the energy conversion unit to the three-phase motor of the heavy-load engineering vehicle to drive the three-phase motor to rotate.

7. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 1, characterized in that, The power frequency rectifier unit includes: The first diode has its anode connected to one end of an external power frequency AC current, and its cathode connected to the input terminal of the first switch. The second diode has its anode connected to the other end of the external power frequency AC current, and its cathode connected to the input terminal of the first switch. The anode of the third diode is connected to the input terminal of the fourth switch, and the cathode is connected to one end of the external power frequency AC power. The fourth diode has its anode connected to the input terminal of the fourth switch, and its cathode connected to the other end of the external power frequency AC power supply.

8. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 1, characterized in that, The energy conversion unit is a three-phase full-bridge converter.

9. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 8, characterized in that, The energy conversion unit includes an upper bridge arm and a lower bridge arm, wherein: The upper bridge arm includes: The first MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The first body diode is connected in parallel across the first MOS transistor, with its anode connected to the source of the first MOS transistor and its cathode connected to the drain of the first MOS transistor. The second MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The second body diode is connected in parallel across the second MOSFET, with its anode connected to the source of the second MOSFET and its cathode connected to the drain of the second MOSFET. The third MOSFET has its drain connected to the positive terminal of the DC bus and its gate connected to the control unit. The third body diode is connected in parallel across the third MOSFET, with its anode connected to the source of the third MOSFET and its cathode connected to the drain of the third MOSFET. The lower bridge arm includes: The fourth MOSFET has its drain connected to the source of the first MOSFET, and the connection point serves as the third phase output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fourth body diode is connected in parallel across the fourth MOSFET, with its anode connected to the source of the fourth MOSFET and its cathode connected to the drain of the fourth MOSFET. The fifth MOSFET has its drain connected to the source of the second MOSFET, and the connection point serves as the second output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The fifth body diode is connected in parallel across the fifth MOSFET, with its anode connected to the source of the fifth MOSFET and its cathode connected to the drain of the fifth MOSFET. The sixth MOSFET has its drain connected to the source of the third MOSFET, and the connection point serves as the first output terminal of the energy conversion unit; its source is connected to the negative terminal of the bus voltage, and its gate is connected to the control unit. The sixth body diode is connected in parallel across the sixth MOS transistor, with its anode connected to the source of the sixth MOS transistor and its cathode connected to the drain of the sixth MOS transistor.

10. The high-load engineering vehicle charging and electric drive multiplexing circuit according to claim 9, characterized in that, When the energy output from the vehicle battery passes through the energy conversion unit to drive the three-phase motor of a heavy-load engineering vehicle, the following steps are taken: any MOSFET in the upper bridge arm of the energy conversion unit and any MOSFET in the lower bridge arm that does not belong to the same phase as the MOSFET are taken as a group of MOSFET units, and the duty cycle of the two MOSFETs in each group of MOSFET units is adjusted to control the magnitude of the three-phase AC power output by the energy conversion unit.

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