Three-phase bridge type PWM (Pulse Width Modulation) controllable rectifier suitable for high-power bulldozer

Abstract

The utility model provides a three-phase bridge type PWM controllable rectifier suitable for a high-power bulldozer. The three-phase bridge type PWM controllable rectifier comprises a UVW three-phase inlet wire fuse, an AC input voltage sensor, an AC input current sensor, a three-phase bridge type PWM controllable rectification circuit, a discharge resistor, a bus support capacitor, a bus output current sensor and a bus output voltage sensor. The three-phase bridge type PWM controllable rectification circuit comprises six controllable switching device IGBT groups to form three groups of double parallel IGBT structures, sine wave PWM control is carried out on input voltage of each phase, and on and off of input current are controlled; in an electronic control system of the bulldozer, three-phase alternating-current voltage generated by a front-end generator passes through an alternating-current input voltage sensor and an alternating-current input current sensor and then is subjected to sine-wave PWM control through three groups of double-parallel IGBT structures, sine-wave current of each phase is obtained and then direct current is output, and stable direct-current voltage is provided for next-stage equipment.

Description

Technical Field

[0001] This utility model relates to the technical field of electrical control systems for engineering machinery and three-phase bridge rectifiers, and in particular to a three-phase bridge PWM controllable rectifier suitable for high-power bulldozers. Background Technology

[0002] In electrical topologies, rectifier circuits are a crucial component of power conversion systems. Traditional rectifier circuits primarily rely on uncontrolled rectifier modules composed of power diodes, such as a bridge circuit using three diode modules for uncontrolled rectification. While this method is relatively simple in structure and low in cost, it suffers from significant drawbacks: the output voltage is fixed and determined solely by the generator voltage; the DC voltage waveform fluctuates greatly, significantly impacting the AC power grid; the power factor is uncontrollable; and there is some pulsation. These problems are particularly pronounced under harsh environmental conditions, affecting not only grid stability and the normal operation of other equipment but also significantly shortening the lifespan of electrical components.

[0003] A three-phase PWM (Pulse Width Modulation) rectifier circuit is an electronic device used for power conversion and control, primarily converting three-phase alternating current (AC) into controllable direct current (DC). The three-phase PWM rectifier circuit utilizes a three-phase bridge rectifier and PWM control technology: the three-phase bridge rectifier consists of six controllable IGBTs (Insulated Gate Bipolar Transistors), each connected to one of the three phases of the three-phase AC power supply; through appropriate control and adjustment, the rectifier's switching operation is achieved, thereby converting the three-phase AC power into controllable DC power. Therefore, the three-phase PWM controllable rectifier, with almost no additional hardware, can achieve bidirectional energy flow, realize rectification functions, stabilize DC voltage, and significantly suppress the generation and injection of harmonic currents into the AC power grid, reducing pollution to the grid.

[0004] Therefore, applying a three-phase PWM controllable rectifier to the bulldozer electronic control system for controllable rectification can stabilize the output DC voltage and adjust the output voltage value in real time according to load requirements, thereby improving the flexibility and adaptability of the bulldozer electronic control system. Utility Model Content

[0005] The problem to be solved by this utility model is to provide a three-phase bridge PWM controllable rectifier suitable for high-power bulldozers, so as to realize the three-phase AC power generated by the generator in the bulldozer electrical control system through three-phase bridge PWM controllable rectification to output stable DC power and provide a stable DC voltage for the next stage.

[0006] The present invention adopts the following technical solution: a three-phase bridge PWM controllable rectifier suitable for high-power bulldozers, comprising: an AC input voltage sensor, an AC input current sensor, a three-phase bridge PWM controllable rectifier circuit, a bus support capacitor, a bus output current sensor, and a bus output voltage sensor.

[0007] The three-phase bridge PWM controllable rectifier circuit includes three sets of dual-parallel IGBT (insulated gate bipolar transistor) structures for controlling the on and off of the input current. The three-phase input AC voltages are U-phase, V-phase, and W-phase, respectively. After passing through the AC input voltage sensor and the AC input current sensor, they pass through the three sets of dual-parallel IGBT structures. The output terminals of the three-phase bridge PWM controllable rectifier circuit are connected to the DC bus DC+ and DC-.

[0008] Furthermore, the bus support capacitor and the bus output voltage sensor are connected in parallel between the output DC bus to detect the stable DC output voltage; the bus output current sensor is connected in series with the output DC bus DC+ to detect the bus output current.

[0009] The three-phase bridge PWM controllable rectifier circuit includes six controllable switching devices IGBT groups: VQ1, VQ2, VQ3, VQ4, VQ5, and VQ6, forming three sets of dual-parallel IGBT structures: VQ1 and VQ2 in parallel, VQ3 and VQ4 in parallel, and VQ5 and VQ6 in parallel.

[0010] The input U-phase, V-phase, and W-phase voltages are respectively connected to the middle of the three sets of dual-parallel IGBT structures, and the two ends of the three sets of dual-parallel IGBT structures are respectively connected to the output DC bus DC+ and DC-.

[0011] The circuit is controlled by a three-phase bridge PWM controllable rectifier circuit, which generates a sinusoidal PWM voltage at the AC input terminal of the rectifier bridge, controls the voltage of each phase, and obtains the sinusoidal current of each phase.

[0012] Preferably, there are two AC input voltage sensors, which are connected in parallel between the U-phase and V-phase input buses and the V-phase and W-phase input buses, respectively, to detect the AC input bus voltage and control the closed-loop feedback of the input voltage.

[0013] Preferably, there are two AC input current sensors, which are set after the AC input voltage sensor and connected in series with the U-phase and V-phase input buses respectively, to detect the AC input bus current and control the input current closed-loop feedback.

[0014] Preferably, the bus support capacitor is located at the front end of the bus output current sensor to filter out output voltage ripple, stabilize the output voltage, and filter out harmonics generated in the grid-side current due to the DC bus voltage PWM modulation.

[0015] Preferably, the bus output voltage sensor is located at the rear end of the bus output current sensor to detect the output bus voltage and control the closed-loop feedback of the output DC voltage.

[0016] Preferably, the controllable rectifier further includes UVW three-phase input fuses. The controllable rectifier also includes three UVW three-phase input fuses, which are set at the front end of the AC input voltage sensor and connected to the three-phase input voltage respectively, for overload protection and short circuit protection.

[0017] Preferably, the controllable rectifier further includes a discharge resistor connected in parallel between the output DC bus of the three-phase bridge PWM controllable rectifier circuit 4 and the controllable rectifier for active discharge after power-off.

[0018] Preferably, the front end of the controllable rectifier is a generator, which inputs three-phase AC voltage to the controllable rectifier. After rectification by the controllable rectifier, a stable DC voltage is output through the output bus to power the next stage equipment.

[0019] Compared with the prior art, the present invention, by adopting the above technical solution, has the following technical effects:

[0020] 1. This utility model uses a three-phase bridge PWM controllable rectifier to replace uncontrolled rectification. By controlling the conduction angle of the three-phase bridge PWM controllable rectifier circuit, the output voltage is adjusted, making the output voltage more stable and the voltage waveform fluctuation smaller.

[0021] 2. The three-phase bridge PWM controllable rectifier of this utility model adopts a dual parallel IGBT structure, which can enable a larger output current. At the same time, due to the small size of the IGBT structure, it can effectively save space and reduce costs. In addition, the PWM controllable rectifier has high control precision and can realize stepless adjustment of output voltage and output current.

[0022] 3. The three-phase bridge PWM controllable rectifier of this utility model realizes bidirectional energy flow. When the circuit is working in the rectification state, energy flows from the grid side to the DC side load; when the circuit is working in the regeneration state, it is similar to a three-phase PWM voltage source inverter, which can feed the DC side energy back to the AC grid side. Attached Figure Description

[0023] Figure 1 This is a block diagram of the three-phase bridge PWM controllable rectifier of this utility model. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] In one embodiment of this utility model, the three-phase bridge PWM controllable rectifier of this utility model is applied to the electric control system of a bulldozer, so that the three-phase AC power generated by the generator is rectified in a controllable manner through PWM to output a stable voltage as a DC power supply.

[0026] Specifically, such as Figure 1 As shown, the three-phase bridge PWM controllable rectifier includes: UVW three-phase input fuse 1, AC input voltage sensor 2, AC input current sensor 3, three-phase bridge PWM controllable rectifier circuit 4, discharge resistor 5, bus support capacitor 6, bus output current sensor 7, bus output voltage sensor 8.

[0027] UVW three-phase incoming line fuses 1, namely FU1, FU2 and FU3, are used for overload protection and short circuit protection to protect electronic equipment, prevent large currents from negatively affecting downstream devices, and extend the service life of the equipment.

[0028] AC input voltage sensors 2, namely TV1 and TV2, are connected in parallel between the U-phase and V-phase input buses and the V-phase and W-phase input buses. Their function is to detect the AC input line voltage and to provide voltage closed-loop feedback in the control system.

[0029] AC input current sensors 3, namely TA1 and TA2, are set after AC input voltage sensor 2 and connected in series on the U-phase and V-phase input buses respectively. Their function is to detect the AC input current and to provide current closed-loop feedback in the control.

[0030] The three-phase bridge PWM controllable rectifier circuit 4 includes six controllable switching devices IGBT groups: VQ1, VQ2, VQ3, VQ4, VQ5, and VQ6. It adopts a dual parallel connection technology: VQ1 and VQ2 are connected in parallel, VQ3 and VQ4 are connected in parallel, and VQ5 and VQ6 are connected in parallel, serving as the U phase, V phase, and W phase respectively. Its function is to control the conduction and cutoff of the output current.

[0031] A three-phase PWM rectifier is an electronic device used for power conversion and control, primarily converting three-phase alternating current into controllable direct current. Dual parallel IGBTs involve connecting two IGBTs in parallel to achieve current sharing, increasing power carrying capacity and improving system reliability. This technology is commonly used in high-power output applications.

[0032] It should be noted that this embodiment uses two parallel IGBTs to form a three-phase bridge PWM controllable rectifier circuit. The three-phase PWM rectifier circuit uses a three-phase bridge rectifier and PWM control technology. The three-phase bridge rectifier consists of six controllable IGBTs, which are respectively connected to the three phases of the three-phase AC power supply. The switching operation of the rectifier is realized through appropriate control and adjustment, thereby converting the three-phase AC power into controllable DC power.

[0033] The discharge resistor 5 is used for the active discharge function after the entire module is powered off, ensuring safety.

[0034] In this embodiment, there are two discharge resistors 5, namely R1 and R2, which are connected in parallel between the output DC bus of the three-phase bridge PWM controllable rectifier circuit 4.

[0035] The bus support capacitor 6 is C1, which is connected in parallel between the output DC bus after the discharge resistor 5. Its function is to filter out the ripple of the output voltage, stabilize the output voltage, and further filter out the harmonics generated in the grid current due to the PWM modulation of the DC bus voltage.

[0036] The bus output current sensor 7 is TA3, which is connected in series with the DC+ output bus to detect the bus current. Its function is to provide closed-loop feedback for the current at the control output.

[0037] The bus output voltage sensor 8 is TV3, which is used to detect the DC bus voltage at the output end and is used for closed-loop feedback of the control output voltage.

[0038] Furthermore, the bus support capacitor 6 is located at the front end of the bus output current sensor 7, and the bus output voltage sensor 8 is located at the rear end of the bus output current sensor 7.

[0039] In this embodiment, the bulldozer's overall power system has its AC side connected to the generator and its DC side connected to the inverter. Through the three-phase bridge PWM controllable rectifier proposed in this invention, the three-phase AC power generated by the generator can be controlled and rectified into a stable voltage as a DC power supply to power the downstream inverter, thereby achieving stable operation of the entire system.

[0040] Meanwhile, this embodiment achieves bidirectional energy flow through the three-phase bridge PWM controllable rectifier circuit 4. When the circuit is in rectification mode, energy flows from the grid side to the DC side load; when the circuit is in regeneration mode, it is similar to a three-phase PWM voltage-source inverter, which can feed the DC side energy back to the AC grid side.

[0041] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A three-phase bridge PWM controllable rectifier suitable for high-power bulldozers, characterized in that, The controllable rectifier includes: an AC input voltage sensor (2), an AC input current sensor (3), a three-phase bridge PWM controllable rectifier circuit (4), a bus support capacitor (6), a bus output current sensor (7), and a bus output voltage sensor (8); The three-phase bridge PWM controllable rectifier circuit (4) includes three sets of dual parallel IGBT structures for controlling the conduction and cutoff of the input current; the three-phase input AC voltages are U phase, V phase, and W phase, respectively. After passing through the AC input voltage sensor (2) and the AC input current sensor (3), they are respectively input to the three sets of dual parallel IGBT structures for sinusoidal PWM control to obtain the sinusoidal current of each phase; the output terminal of the three-phase bridge PWM controllable rectifier circuit (4) is connected to the DC bus DC+ and DC-; The bus support capacitor (6) and the bus output voltage sensor (8) are connected in parallel between the output DC bus to detect the output DC voltage; the bus output current sensor (7) is connected in series with the output DC bus DC+ to detect the output current of the bus.

2. The three-phase bridge PWM controllable rectifier suitable for high-power bulldozers according to claim 1, characterized in that, The three-phase bridge PWM controllable rectifier circuit (4) includes six controllable switching device IGBT groups: VQ1, VQ2, VQ3, VQ4, VQ5, and VQ6, forming three sets of dual parallel IGBT structures: VQ1 and VQ2 in parallel, VQ3 and VQ4 in parallel, and VQ5 and VQ6 in parallel, to perform sinusoidal PWM control on the input three-phase AC voltage.

3. The three-phase bridge PWM controllable rectifier suitable for high-power bulldozers according to claim 2, characterized in that, The input U-phase, V-phase, and W-phase voltages are respectively connected to the middle of the three sets of dual-parallel IGBT structures. Sine wave PWM control is applied to the input voltage of each phase, so that the AC input terminal of the rectifier bridge generates a sinusoidal PWM voltage and obtains the sinusoidal current of each phase. The two ends of the three sets of dual-parallel IGBT structures are respectively connected to the output DC bus DC+ and DC-.

4. The three-phase bridge PWM controllable rectifier suitable for high-power bulldozers according to claim 3, characterized in that, There are two AC input voltage sensors (2), which are connected in parallel between the U-phase and V-phase input buses and the V-phase and W-phase input buses, respectively, to detect the AC input bus voltage and control the closed-loop feedback of the input terminal voltage.

5. The three-phase bridge PWM controllable rectifier suitable for high-power bulldozers according to claim 3, characterized in that, There are two AC input current sensors (3), which are set after the AC input voltage sensor (2) and connected in series with the U-phase and V-phase input buses respectively, to detect the AC input bus current and control the input current closed-loop feedback.

6. The three-phase bridge PWM controllable rectifier for high-power bulldozers according to claim 1, characterized in that, The bus support capacitor (6) is located at the front end of the bus output current sensor (7) and is used to filter out output voltage ripple, stabilize output voltage, and filter out harmonics generated in the grid-side current due to the DC bus voltage PWM modulation.

7. The three-phase bridge PWM controllable rectifier for high-power bulldozers according to claim 6, characterized in that, The bus output voltage sensor (8) is located at the rear end of the bus output current sensor (7) and is used to detect the output bus voltage and control the closed-loop feedback of the output DC voltage.

8. The three-phase bridge PWM controllable rectifier suitable for high-power bulldozers according to claim 1, characterized in that, The controllable rectifier also includes a UVW three-phase input fuse (1). The controllable rectifier also includes three UVW three-phase input fuses (1), which are set at the front end of the AC input voltage sensor (2) and connected to the three-phase input voltage respectively for overload protection and short circuit protection.

9. The three-phase bridge PWM controllable rectifier for high-power bulldozers according to claim 1, characterized in that, The controllable rectifier also includes at least one discharge resistor (5), which is connected in parallel between the output DC bus of the three-phase bridge PWM controllable rectifier circuit (4) and is used for active discharge after the controllable rectifier is powered off.

10. The three-phase bridge PWM controllable rectifier for high-power bulldozers according to claim 1, characterized in that, The front end of the controllable rectifier is a generator, which inputs three-phase AC voltage to the controllable rectifier. After rectification by the controllable rectifier, a stable DC voltage is output through the output bus to power the next stage equipment.

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