A full direct current power supply system adapting to pulse load characteristics

Abstract

The present application relates to the field of electrical engineering, in particular to a kind of full DC power supply system suitable for pulse load characteristics.The system includes control unit, chassis engine, generator, rectifier unit, energy storage unit and distribution unit;Wherein, rectifier unit uses uncontrolled rectification+BUCK type step-down topology, and constant voltage control strategy, specifically: double-loop control mode of outer ring voltage control+inner ring current control, output DC 600V DC bus is stabilized at set voltage value, realizes the constant voltage control of output voltage.Solve the energy supply problem of equipment single vehicle operation, and the problem that traditional electric car system constant current strategy and equipment pulse load are difficult to match.Using the power supply structure of rectifier unit+energy storage unit (capacitor), remove lithium battery in traditional electric drive system, avoid the safety problem of lithium battery, and the system safety is high.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering, and more specifically to an all-DC power supply system adapted to pulse load characteristics. Background Technology

[0002] With the increasing demands of modern society for emergency response, highly mobile operations, and the rapid deployment and autonomous operation capabilities of mobile platforms, integrating complex systems into independent vehicle-mounted environments (referred to as "single vehicles") and achieving independent and efficient operation has become a clear trend in related technological fields. Providing power to high-power equipment systems under single-vehicle conditions is a problem that must be solved.

[0003] Traditional high-power vehicle-mounted equipment typically uses an AC substation as its power source. However, an AC substation usually occupies an independent transportation unit, making it impossible to operate a single vehicle. Electric vehicle chassis, on the other hand, have an energy supply capacity of hundreds of kilowatts. Under single-vehicle conditions, using the chassis power system as the energy source is a possible solution for the equipment to operate under single-vehicle conditions.

[0004] The typical electric vehicle chassis power system is oriented towards vehicle movement and is a constant power DC power supply system, which is incompatible with the pulse load electrical characteristics of the superstructure equipment. Therefore, a power supply system that uses the vehicle's electric drive as the power source and is adapted to the pulse load characteristics urgently needs to be developed. Summary of the Invention

[0005] In order to solve the problems of the prior art and achieve the goal of a power supply system that uses vehicle electric drive as a power source and is adapted to pulse load characteristics, this application provides a full DC power supply system adapted to pulse load characteristics.

[0006] The technical solution adopted is as follows:

[0007] A fully DC power supply system adapted to pulse load characteristics includes a control unit, chassis engine, generator, rectifier unit, energy storage unit, and power distribution unit;

[0008] The control unit includes a chassis control unit and a generator control unit. The chassis control unit sends control commands to the chassis engine and the rectifier unit through the generator control unit to control the operation of the chassis engine and the rectifier unit.

[0009] The chassis engine is the chassis engine of an electric vehicle, and it operates at a constant speed.

[0010] The generator is coaxially connected to the chassis engine. When the chassis engine rotates, it drives the generator to work on the same shaft to generate three-phase alternating current.

[0011] The rectifier unit adopts an uncontrolled rectification + BUCK type step-down topology to convert the three-phase AC power generated by the generator into DC power; the input terminal of the rectifier unit is electrically connected to the output terminal of the generator.

[0012] The energy storage unit is connected in parallel to the DC bus output by the rectifier unit, and uses an electrolytic capacitor as the energy storage element.

[0013] The power distribution unit allocates electrical energy according to the power demand of the load.

[0014] Furthermore, the alternating current generated by the generator has a frequency of 200Hz-400Hz.

[0015] Furthermore, the uncontrolled rectification + BUCK buck topology adopted by the rectifier unit is specifically as follows:

[0016] The input of the uncontrolled rectifier circuit is connected to three-phase AC power, and its output is a DC bus voltage; the input of the BUCK-type step-down circuit is connected to the output of the uncontrolled rectifier circuit, and its output is connected to the load and outputs a DC voltage.

[0017] Furthermore, the uncontrolled rectifier circuit consists of six diodes. The first and fourth diodes are connected in series to form the first bridge arm, the second and fifth diodes are connected in series to form the second bridge arm, and the third and sixth diodes are connected in series to form the third bridge arm. The midpoints of the first, second, and third bridge arms are connected to phases A, B, and C of the three-phase AC power, respectively. The cathodes of the first, second, and third diodes are connected together to form the positive terminal of the rectifier output, and the anodes of the fourth, fifth, and sixth diodes are connected together to form the negative terminal of the rectifier output.

[0018] Furthermore, the BUCK-type buck converter includes a switching transistor, a freewheeling diode, an inductor, and an output capacitor; the drain of the switching transistor is connected to the positive output of the uncontrolled rectifier circuit, the source of the switching transistor is connected to the first terminal of the inductor, and the control terminal of the switching transistor is connected to an external control signal; the freewheeling diode is connected between the source of the switching transistor and the negative output of the uncontrolled rectifier circuit; the second terminal of the inductor is connected to the positive output of the BUCK-type buck converter; and the output capacitor is connected between the positive and negative outputs of the BUCK-type buck converter.

[0019] Furthermore, the output voltage of the BUCK-type step-down circuit of the rectifier unit is DC 600V.

[0020] Furthermore, the constant voltage control strategy adopted by the rectifier unit is specifically a dual-loop control mode of outer-loop voltage control + inner-loop current control. In the outer-loop voltage control, Vref is the voltage setpoint and Vo is the output voltage of the rectifier unit. Vref is compared with Vo to generate a voltage error signal. The voltage error signal is processed by a proportional-integral (PI) controller to generate a current setpoint Iref. In the inner-loop current control, Iref is the current setpoint and Io is the output current of the rectifier unit. Iref is compared with Io to generate a current error signal. The current error signal is processed by a proportional-integral (PI) controller in the inner loop to output a modulation signal. After the loop calculation is completed, a PWM signal is generated and used by the drive circuit to control the switching devices.

[0021] The beneficial effects of this invention are as follows:

[0022] Traditional vehicle-mounted equipment power supply systems typically use AC substations as their power source. These substations usually occupy a separate transport unit, making single-vehicle operation impossible. A typical electric vehicle chassis power system, oriented towards vehicle travel, is a constant-power DC power supply system, which is incompatible with the pulse load electrical characteristics of the equipment.

[0023] This invention uses an electric vehicle chassis power system as the power source for onboard equipment. The power supply unit consists of a chassis engine, generator, rectifier unit, and energy storage unit. A constant voltage control strategy is employed to match the chassis power supply with the electrical load, solving the energy supply problem for single-vehicle operation and addressing the difficulty in matching the constant power strategy of traditional electric vehicle systems with the pulse load of the equipment. The power supply structure, combining a rectifier unit and an energy storage unit (capacitor), eliminates the lithium battery found in traditional electric drive systems, avoiding the safety issues associated with lithium batteries and resulting in a high level of system safety. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the all-DC power supply system according to an embodiment of the present invention;

[0025] Figure 2 This is a block diagram illustrating the working principle of the rectifier unit according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the working principle of the all-DC power supply system according to an embodiment of the present invention;

[0027] Figure 4 This is the output bus voltage waveform (continuous pulse) of an embodiment of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail.

[0029] This invention provides an all-DC power supply system adapted to pulse load characteristics, the system structure diagram is as follows. Figure 1As shown, the system includes a control unit, chassis engine, generator, rectifier unit, energy storage unit, and power distribution unit. The superstructure pulse load is not part of the system and is only used to illustrate the application environment of this system.

[0030] The components of the all-DC power supply system adapted to pulse load characteristics of the present invention will now be described:

[0031] The control unit includes a chassis control unit and a generator control unit. The chassis control unit sends control commands to the chassis engine and rectifier unit through the generator control unit to control the operation of the chassis engine and rectifier unit. At the same time, the generator control unit receives the operating status of the chassis engine and rectifier unit and reports it to the chassis control unit.

[0032] The chassis engine is the same as that used in electric vehicles, and it operates at a constant speed.

[0033] The generator is coaxially connected to the chassis engine. When the chassis engine rotates, it drives the generator to work in a continuous manner, converting mechanical energy into electrical energy and generating three-phase alternating current with a power generation capacity of hundreds of kilowatts.

[0034] The input terminal of the rectifier unit is electrically connected to the output terminal of the generator. It adopts an uncontrolled rectifier + BUCK type step-down topology to convert the three-phase AC power generated by the generator into DC 600V DC power.

[0035] In this embodiment, the uncontrolled rectifier circuit is a typical three-phase rectifier circuit. The input terminal of the uncontrolled rectifier circuit is connected to three-phase AC power, and its output terminal outputs DC bus voltage. Specifically, the uncontrolled rectifier circuit consists of six diodes (D1-D6), as follows: Figure 2 In the typical topology of the circuit, diodes D1 and D4 are connected in series to form the first bridge arm, D2 and D5 are connected in series to form the second bridge arm, and D3 and D6 are connected in series to form the third bridge arm. The midpoints of each bridge arm are used to connect to phases A, B, and C of the three-phase AC power supply, respectively. The cathodes of the upper diodes (D1, D2, D3) are connected together to form the positive rectifier output; the anodes of the lower diodes (D4, D5, D6) are connected together to form the negative rectifier output. Utilizing the unidirectional conductivity of the diodes, the three-phase AC power is directly converted into pulsating DC power without additional control signals, providing DC input power for the subsequent BUCK-type buck converter. The input filter capacitor (C1) is connected between the positive and negative output terminals of the uncontrolled rectifier circuit, serving as a filter and supporting bus, providing a relatively stable DC input for the BUCK-type buck converter.

[0036] A buck converter circuit performs voltage reduction conversion. Its input is connected to the output of an uncontrolled rectifier circuit, and its output is used to connect to a load and output a stable DC voltage. In this embodiment, the buck converter circuit includes a switching transistor (Q1), a freewheeling diode (D7), an inductor (L1), and an output capacitor (C2). The drain of the switching transistor (Q1) is connected to the positive output of the uncontrolled rectifier circuit, and the source of the switching transistor (Q1) is connected to the first terminal of the inductor (L1). The control terminal (G) of the switching transistor (Q1) is used to receive an external control signal to control the switching transistor's on and off states. The freewheeling diode (D7) is connected between the source of the switching transistor (Q1) and the negative output of the uncontrolled rectifier circuit. The second terminal of the inductor (L1) is connected to the positive output of the buck converter circuit. The output capacitor (C2) is connected between the positive and negative output terminals of the buck converter circuit.

[0037] The rectifier unit outputs a current of Io and an output voltage of Vo, providing stable DC power to the load through a constant voltage control strategy. Specifically, the constant voltage control strategy employed by the rectifier unit is a dual-loop control mode: outer loop voltage control + inner loop current control, achieving regulated output from the DC 600V bus. Figure 2 As shown, in the outer loop voltage control, Vref is the voltage setpoint, and Vo is the output voltage of the rectifier unit. Comparing Vref with Vo generates a voltage error signal. This signal is processed by a proportional-integral (PI) controller to generate the current setpoint Iref. The PI controller in the outer loop is responsible for eliminating steady-state errors. When the rectifier unit output voltage Vo is lower than the voltage setpoint Vref, the PI output increases, raising the current setpoint Iref; conversely, it decreases Iref. In the inner loop current control, Iref is the current setpoint, and Io is the output current of the rectifier unit. Comparing Iref with Io generates a current error signal. This signal is processed by the PI controller in the inner loop current control to output a modulation signal. The PI controller in the inner loop current control tracks the current setpoint and adjusts when there are sudden load changes or input voltage fluctuations to suppress current surges and improve system response speed and stability. After loop calculation, a PWM (Pulse Width Modulation) signal is generated, which, after passing through the drive circuit, controls the switching device (in this embodiment, the control electrode of Q1) to achieve closed-loop control of the rectifier unit.

[0038] The energy storage unit is connected in parallel to the DC 600V bus output of the rectified power supply. It uses electrolytic capacitors as energy storage elements to stabilize the DC bus and maintain system power balance. Compared to lithium batteries, it features high safety, fast charging and discharging speed, and a simple and mature design.

[0039] The power distribution unit allocates electrical energy according to the power demand of the load, supplying power to all electrical loads in the vehicle; the DC-DC converter converts DC 600V to DC 24V to provide power to the control unit.

[0040] The chassis engine and generator are the power sources for the all-DC power supply system. When the vehicle is parked, the chassis engine and generator supply power to the superstructure pulse load. The aforementioned superstructure pulse load refers to high-power electrical equipment with pulse operating characteristics installed in a single vehicle. When the vehicle is moving, the chassis engine and generator supply power for vehicle movement.

[0041] The principle block diagram of the all-DC power supply system is as follows: Figure 3 As shown. The chassis control unit in the control unit interacts with the chassis engine through the generator control unit, issuing control commands to control the chassis engine's operation. The chassis engine operates at a set speed according to the control commands from the generator control unit, driving the generator to produce three-phase AC power. The fluctuation range varies depending on the load conditions and operating settings, with the AC frequency controlled between 200-400Hz. The rectifier unit adopts an uncontrolled rectification + BUCK-type step-down topology, using a constant voltage control strategy to convert the three-phase AC power generated by the generator into DC 600V DC power. The constant voltage control strategy is specifically a dual-loop control mode of outer loop voltage control + inner loop current control, converting the three-phase AC power into stable DC 600V DC power suitable for the operating characteristics of the superstructure pulse load. This DC power is distributed to vehicle travel, superstructure pulse loads, and control units via the power distribution unit. The energy storage unit is connected in parallel to the DC 600V DC bus to support bus stability.

[0042] To verify the technical effect of this application, the following methods were adopted. Figure 3 The power supply system shown features a pulsed load that transitions between pulsed power levels in the hundreds of kilowatts range. The DC bus voltage fluctuation range can be controlled within ±60V, meeting the system's requirements. The test waveform is shown below. Figure 4 As shown in the figure. Based on the above examples, the all-DC power supply system adapted to pulse load characteristics proposed in this invention can meet the long-term reliable operation requirements of the equipment.

[0043] This invention relates to an all-DC power supply system adapted to pulse load characteristics. Using the electric vehicle chassis power system as the power source for onboard equipment, the system comprises a chassis engine, generator, rectifier unit, and energy storage unit to form the power supply unit. A constant voltage control strategy is employed to match the chassis power supply with the electrical load, solving the energy supply problem for single-vehicle operation and addressing the difficulty in matching the constant power strategy of traditional electric vehicle systems with pulse loads. The power supply structure, consisting of a rectifier unit and an energy storage unit (capacitor), eliminates the lithium battery found in traditional electric drive systems, thus avoiding the safety issues associated with lithium batteries and resulting in a high level of system safety.

[0044] While the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the invention. Any equivalent changes or modifications made without departing from the spirit and scope of the invention are also within the scope of protection of the invention. Therefore, the scope of protection of the present invention should be determined by the claims of this application.

Claims

1. A full DC power supply system adapted to pulse load characteristics, characterized in that, The system includes a control unit, a chassis engine, a generator, a rectifier unit, an energy storage unit, and a power distribution unit; The control unit includes a chassis control unit and a generator control unit. The chassis control unit sends control commands to the chassis engine and the rectifier unit through the generator control unit to control the operation of the chassis engine and the rectifier unit. The chassis engine is the chassis engine of an electric vehicle, and it operates at a constant speed. The generator is coaxially connected to the chassis engine. When the chassis engine rotates, it drives the generator to work on the same shaft to generate three-phase alternating current. The rectifier unit adopts an uncontrolled rectification + BUCK type step-down topology to convert the three-phase AC power generated by the generator into DC power; the input terminal of the rectifier unit is electrically connected to the output terminal of the generator. The energy storage unit is connected in parallel to the DC bus output by the rectifier unit, and uses an electrolytic capacitor as the energy storage element. The power distribution unit allocates electrical energy according to the power demand of the load.

2. The all-DC power supply system adapted to pulse load characteristics according to claim 1, characterized in that, The alternating current generated by the generator has a frequency of 200Hz-400Hz.

3. The all-DC power supply system adapted to pulse load characteristics according to claim 1, characterized in that, The uncontrolled rectification + BUCK buck topology adopted by the rectifier unit is specifically as follows: The input of the uncontrolled rectifier circuit is connected to three-phase AC power, and its output is a DC bus voltage; the input of the BUCK-type step-down circuit is connected to the output of the uncontrolled rectifier circuit, and its output is connected to the load and outputs a DC voltage.

4. The all-DC power supply system adapted to pulse load characteristics according to claim 3, characterized in that, The uncontrolled rectifier circuit consists of six diodes. The first and fourth diodes are connected in series to form the first bridge arm, the second and fifth diodes are connected in series to form the second bridge arm, and the third and sixth diodes are connected in series to form the third bridge arm. The midpoints of the first, second, and third bridge arms are connected to phases A, B, and C of the three-phase AC power supply, respectively. The cathodes of the first, second, and third diodes are connected together to form the positive terminal of the rectifier output, and the anodes of the fourth, fifth, and sixth diodes are connected together to form the negative terminal of the rectifier output.

5. The all-DC power supply system adapted to pulse load characteristics according to claim 4, characterized in that, The BUCK-type buck converter includes a switching transistor, a freewheeling diode, an inductor, and an output capacitor. The drain of the switching transistor is connected to the positive output of the uncontrolled rectifier circuit, the source of the switching transistor is connected to the first terminal of the inductor, and the control terminal of the switching transistor is connected to an external control signal. The freewheeling diode is connected between the source of the switching transistor and the negative output of the uncontrolled rectifier circuit. The second terminal of the inductor is connected to the positive output of the BUCK-type buck converter. The output capacitor is connected between the positive and negative outputs of the BUCK-type buck converter.

6. The all-DC power supply system adapted to pulse load characteristics according to claim 5, characterized in that, The output voltage of the BUCK-type step-down circuit of the rectifier unit is DC 600V.

7. The all-DC power supply system adapted to pulse load characteristics according to claim 5, characterized in that, The constant voltage control strategy adopted by the rectifier unit is a dual-loop control mode of outer loop voltage control + inner loop current control. In the outer loop voltage control, Vref is the voltage setpoint and Vo is the output voltage of the rectifier unit. Vref is compared with Vo to generate a voltage error signal. After the voltage error signal is processed by the proportional-integral (PI) converter, the current setpoint Iref is generated. In the inner loop current control, Iref is the current setpoint and Io is the output current of the rectifier unit. Iref and Io are compared to generate a current error signal. The current error signal is processed by the proportional-integral controller (PI) of the inner loop current and then output as a modulation signal. After the loop calculation is completed, a PWM signal is generated and then used by the drive circuit to control the switching device.

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