Modular electrical architecture for a low power diesel range extender

Abstract

A kind of modular electrical architecture of small power diesel range extender, it is related to hybrid power generation system, distributed energy and engineering machinery power supply technical field, to improve the problems of low diesel engine operating efficiency, insufficient dynamic response capability, single energy utilization mode, low system modular degree, poor expandability and maintainability of existing small power diesel power generation and range extension system.The technical points include mechanical power generation module, rectification filtering module, high-voltage DC conversion module, medium-voltage DC bus module, energy storage module, inverter output module, low-voltage auxiliary power supply module and main controller module;The output end of the medium-voltage DC bus module and the high-voltage DC conversion module is electrically connected, for realizing energy decoupling between power generation side, energy storage side and load side;The main controller module is in communication with the mechanical power generation module, high-voltage DC conversion module and energy storage module, for collecting the operating state of each module and outputting control instructions, to coordinate the collaborative work of each module.

Description

Technical Field

[0001] This invention relates to the fields of hybrid power generation systems, distributed energy, and power supply technology for engineering machinery, specifically a modular electrical architecture for a small-power diesel range extender. Background Technology

[0002] The mainstream electrical architecture of existing 1KW-5KW small-power diesel generator sets or range-extended power systems is as follows: the diesel engine directly drives the generator, and the electrical energy output by the generator is directly supplied to the DC load after rectification or without rectification, or converted to AC power by an inverter to supply the AC load. Although some schemes have energy storage batteries connected in parallel, the energy storage units usually only serve as starting power or simple backup power, and do not participate deeply in the system's power dispatching.

[0003] Existing low-power diesel generator sets or range-extended power systems suffer from the following technical problems in practical applications: First, the diesel engine operates inefficiently. Due to the lack of an effective power buffer, the diesel engine's output power must keep up with changes in load power in real time. Especially under low load or frequent load fluctuations, the diesel engine frequently deviates from its optimal specific fuel consumption range, resulting in a significant increase in fuel consumption and reduced economy. Second, the system's dynamic response capability is insufficient. Diesel generator sets have significant mechanical inertia, and their torque and speed adjustment response time is typically in the hundreds of milliseconds or even seconds. When the load is rapidly increased or decreased, the output voltage and frequency of the power generation system are prone to violent fluctuations, even leading to engine shutdown or system protective shutdown, which cannot meet the requirements for high dynamic response quality in low-power application scenarios. Third, the energy utilization method is singular and the overall system efficiency is low. Existing low-power solutions are mostly based on single AC or DC output, lacking the ability to flexibly schedule the energy of the energy storage unit and failing to comprehensively optimize the energy flow based on load demand, battery state of charge, and engine operating conditions. Fourth, the system has low modularity, poor scalability and maintainability. In the existing solution, the electrical units are often highly coupled, with blurred functional boundaries, inconsistent interfaces and fixed power levels. When the application scenario or load requirements change, the entire system needs to be redesigned. It is difficult to achieve flexible adaptation by adding or removing standardized modules, and the cost of troubleshooting and maintenance is high.

[0004] To address the aforementioned issues, some technologies have proposed introducing energy storage units into the system to achieve power compensation. However, these solutions mostly focus on algorithm-level optimization or single-function improvements. In low-power applications, constrained by cost, size, and system complexity, existing technologies still lack a comprehensive solution that, from the perspective of system electrical architecture, can simultaneously achieve effective decoupling, unified scheduling, and modular flexible expansion between power generation, energy storage, and load power. Summary of the Invention

[0005] The purpose of this invention is to provide a modular electrical architecture for a small-power diesel range extender, aiming to improve the problems of low diesel engine operating efficiency, insufficient dynamic response capability, single energy utilization mode, low system modularity, and poor scalability and maintainability in existing small-power diesel power generation and range extender systems.

[0006] This invention is implemented as follows:

[0007] A modular electrical architecture for a low-power diesel range extender includes a mechanical power generation module, which comprises a diesel engine and a generator coaxially connected thereto for converting the chemical energy of diesel fuel into alternating current (AC) electrical energy. The module also includes:

[0008] The rectifier and filter module is electrically connected to the mechanical power generation module and is used to rectify and filter the AC power into high-voltage DC power.

[0009] The high-voltage DC-DC converter module has its input terminal electrically connected to the rectifier and filter module, and is used to convert high-voltage DC power into medium-voltage DC power.

[0010] The medium-voltage DC bus module is electrically connected to the output of the high-voltage DC converter module to achieve energy decoupling between the generation side, energy storage side and load side.

[0011] The energy storage module, connected in parallel to the medium-voltage DC bus module, is used to absorb or release energy when the load power changes, thereby smoothing out system power fluctuations.

[0012] The inverter output module is electrically connected to the medium-voltage DC bus module and is used to convert medium-voltage DC power into AC power for use by AC loads.

[0013] The low-voltage auxiliary power supply module is electrically connected to the medium-voltage DC bus and is used to convert medium-voltage DC power into low-voltage DC power.

[0014] The main controller module is connected to the mechanical power generation module, the high-voltage DC conversion module, and the energy storage module. It is used to collect the operating status of each module and output control commands to coordinate the collaborative work of each module.

[0015] Furthermore, the main controller module controls the diesel engine to operate stably within a preset high-efficiency power range, and uses the output power value corresponding to this high-efficiency power range as the target output power of the high-voltage DC-DC converter module. When the load power is less than the target output power, the module controls the high-voltage DC-DC converter module to charge the energy storage module. When the load power is greater than the target output power, the module controls the energy storage module to supplement the power difference via the medium-voltage DC bus.

[0016] Furthermore, the high-voltage direct current converter module is configured to switch charging modes according to the state of charge of the energy storage module, the charging modes including constant current charging mode and constant voltage charging mode; the main controller module communicates with the high-voltage direct current converter module via CAN bus; the main controller module sends a target output power command and output voltage setting value to the high-voltage direct current converter module, and the high-voltage direct current converter module feeds back the actual output power, module temperature and fault status to the main controller module.

[0017] Furthermore, the main controller module is configured to: cut off the load output when the state of charge of the energy storage module is lower than a first threshold; restore the load output when the state of charge recovers to a level higher than a second threshold; and control the load to consume the energy of the energy storage module when the state of charge is higher than a third threshold, until the state of charge is lower than the third threshold; wherein the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0018] Furthermore, the first threshold is a state of charge of 50%, the second threshold is a state of charge of 80%, and the third threshold is a state of charge of 90%.

[0019] Furthermore, the main controller module is configured to: control the diesel engine to shut down when the state of charge of the energy storage module is greater than a first charge threshold and the load power is less than a first power threshold for a first preset time; and control the diesel engine to start when the load power is greater than a second power threshold for a second preset time, or when the state of charge is lower than a fourth threshold.

[0020] Furthermore, the first charge threshold is 80% state of charge, the first power threshold is 300W, and the first preset time is 1 minute; the second power threshold is 300W, the second preset time is 30 seconds, and the fourth threshold is 50% state of charge.

[0021] Furthermore, the diesel engine is a single-cylinder, four-stroke, electronically controlled, air-cooled diesel engine with a high-pressure common rail system and an engine control unit; the generator is a permanent magnet synchronous generator.

[0022] Furthermore, the rated voltage of the medium-voltage DC bus is 48V to 96V; the rated output power of the modular electrical architecture is 1kW to 5kW.

[0023] Furthermore, the energy storage module is a lithium iron phosphate battery pack, and the inverter output module is a pure sine wave inverter.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention constructs an energy dispatching platform with a medium-voltage DC bus module as its core, enabling diesel engines to break free from real-time tracking of load power and operate stably in a preset high-efficiency power range for a long time, effectively solving the problem of low operating efficiency of diesel engines in existing small-power diesel range extender systems.

[0026] 2. This invention connects the energy storage module directly in parallel to the medium-voltage DC bus module, utilizing its millisecond-level power response characteristics to instantaneously charge and discharge during load changes, thus compensating for the response lag caused by mechanical inertia in the diesel generator system and effectively solving the problem of insufficient dynamic response capability of the system.

[0027] 3. This invention achieves comprehensive optimization of system energy by uniformly collecting and coordinating the power generation, energy storage charging and discharging power and load consumption power through the main controller, effectively solving the problem of single energy utilization mode and low overall efficiency.

[0028] 4. This invention allows each functional module to be independently connected to the medium-voltage DC bus module via a standardized interface, enabling the system to be flexibly configured with modules of different power levels according to application requirements without changing the overall architecture. This effectively solves the problems of low modularity, poor scalability and maintainability in existing solutions.

[0029] 5. This invention provides a systematic solution for small-power diesel range extenders that simultaneously achieves energy decoupling, power buffering, and modular expansion at the electrical architecture level. Attached Figure Description

[0030] Figure 1 This is a block diagram of the electrical connection structure between the modules of this invention;

[0031] Figure 2 This is a schematic diagram of the overall architecture of the electrical control system of the present invention. Detailed Implementation

[0032] The following description, in conjunction with the accompanying drawings, specific embodiments, and comparative examples, provides further details:

[0033] Example 1

[0034] like Figure 1 and Figure 2 As shown, a modular electrical architecture for a small-power diesel range extender includes a mechanical power generation module, a rectifier and filter module, a high-voltage DC-DC converter module, a medium-voltage DC bus module, an energy storage module, an inverter output module, a low-voltage auxiliary power supply module, and a main controller module.

[0035] In this embodiment, the rated voltage of the medium-voltage DC bus module is 72V, the rated output power of the modular electrical architecture is 3kW, and the peak power is 5kW.

[0036] The mechanical power generation module consists of a single-cylinder, four-stroke, electronically controlled, air-cooled diesel engine and a permanent magnet synchronous generator coaxially connected to it. The diesel engine has a rated power of 4kW, equipped with a high-voltage common rail system and an engine control unit, and operates at a stable, high-efficiency speed within the range of 2600–3000 rpm. The permanent magnet synchronous generator outputs a three-phase AC voltage of 340VAC at its rated speed of 3000 rpm.

[0037] The rectifier and filter module uses a high-power three-phase rectifier bridge to rectify the 340VAC three-phase AC power output from the generator into pulsating DC power. Then, it is smoothed by an LC filter circuit composed of a large-capacity electrolytic capacitor and a choke coil to obtain a stable high-voltage DC power of about 480VDC.

[0038] The high-voltage DC-DC converter module uses a 3000W rated power DC-DC converter. Its input is connected to the 480VDC output of the rectifier and filter module, and its output is connected to the 72V medium-voltage DC bus module. The high-voltage DC-DC converter module efficiently steps down the 480VDC to 72VDC and connects it to the bus, with a maximum output power limited to 3000W. Simultaneously, this module integrates multi-stage charging management functions, which can automatically switch charging modes based on the SOC and temperature information reported by the battery management system: when SOC < 60%, a constant current charging mode is used, with the charging current not exceeding 50A; when 60% ≤ SOC < 80%, a constant voltage charging mode is used, with the charging current gradually decreasing; when SOC ≥ 80%, a float charging mode is entered, with the charging current dropping to 5A; when SOC ≥ 90%, the charging current drops to zero, and charging is complete.

[0039] The energy storage module uses a 72V / 67Ah lithium iron phosphate battery pack, which is connected in parallel to the 72V medium-voltage DC bus module. The battery pack has a built-in battery management system that communicates with the main controller via a CAN bus to report battery voltage, current, state of charge, temperature, and fault status information in real time.

[0040] The inverter output module is connected to the 72V medium-voltage DC bus module. It is a pure sine wave inverter that converts 72V DC power into 220VAC / 50Hz sine wave AC power with a continuous output power of 2.5kW, which can power AC loads.

[0041] The low-voltage auxiliary power supply module is a 48V to 12V DC-DC module with an input voltage range of 30 to 96V, an output voltage of 12V, and an output current of 10A. It is used to provide low-voltage DC power to the main controller, engine ECU, solenoid valves, and other control, detection, and execution units.

[0042] The main controller module adopts a general vehicle controller and communicates with the engine ECU, high voltage DC-DC converter module, battery management system and inverter output module through CAN bus. It is used to collect the operating status of each module and output control commands to coordinate the work of each module.

[0043] The main controller module controls the diesel engine to operate stably within a preset high-efficiency power range (corresponding to a speed range of 2600-3000 rpm), and uses the output power value corresponding to this high-efficiency power range as the target output power of the high-voltage DC-DC converter module. When the load power is less than the target output power, the high-voltage DC-DC converter module is controlled to charge the energy storage module; when the load power is greater than the target output power, the energy storage module is controlled to supplement the difference in power through the medium-voltage DC bus module.

[0044] The main controller module and the high-voltage direct current converter module communicate via a CAN bus. The main controller module sends the target output power command and output voltage setpoint to the high-voltage direct current converter module; the high-voltage direct current converter module reports the actual output power, module temperature, and fault status in each control cycle. When the actual output power deviates from the target by more than ±5% and persists for more than 100ms, the high-voltage direct current converter module actively reports a power tracking anomaly alarm, and the main controller performs secondary scheduling compensation accordingly.

[0045] The main controller module is configured to: cut off the load output when the state of charge of the energy storage module is lower than the first threshold (50% state of charge); restore the load output when the state of charge recovers to above the second threshold (80% state of charge); and control the load to consume the energy of the energy storage module when the state of charge is above the third threshold (90% state of charge) until the state of charge is lower than the third threshold.

[0046] The main controller module is also configured to: control the diesel engine to shut down when the state of charge of the energy storage module is greater than 80% and the load power is less than 300W for 1 minute; and control the diesel engine to start when the load power is greater than 300W for 30 seconds, or when the state of charge is less than 50%.

[0047] In this embodiment, the overall dimensions of the machine are 775×557×547mm, the weight of the machine is ≤200kg, the operating temperature range is -20℃~+50℃, the relative humidity is 10~95% (non-condensing), the operating altitude is ≤3000m, and the heat dissipation method is air cooling.

[0048] Example 2

[0049] In another embodiment of the present invention, the rated voltage of the medium-voltage DC bus module is 48V, and the rated output power of the modular electrical architecture is 1kW. Correspondingly, the high-voltage DC converter module steps down the rectified and filtered high-voltage DC power to 48V for connection to the bus, the energy storage module uses a 48V lithium iron phosphate battery pack, and the inverter output module inverts the 48V DC power into 220VAC / 50Hz AC power. The functions and connections of the remaining modules are the same as in Embodiment 1.

[0050] Example 3

[0051] In another embodiment of the present invention, the rated voltage of the medium-voltage DC bus module is 96V, and the rated output power of the modular electrical architecture is 5kW. The high-voltage DC-DC converter module steps down the rectified and filtered high-voltage DC power to 96V and connects it to the bus. The energy storage module uses a 96V lithium iron phosphate battery pack. The functions and connections of the remaining modules are the same as in Embodiment 1.

[0052] Example 4

[0053] As an embodiment of the invention regarding communication redundancy, the communication bus between the main controller and each module is configured with both CAN bus and RS-485 bus. Under normal operating conditions, the system uses the CAN bus as the main communication link; when the main controller detects an abnormality in CAN bus communication, the modular electrical architecture automatically switches to RS-485 bus operation to maintain basic power output function, ensuring that the system can still operate in degraded mode under communication failure conditions.

[0054] Alternative implementation methods

[0055] Without departing from the core idea of ​​this invention, the following equivalent substitutions should all fall within the protection scope of this invention:

[0056] The voltage rating of the medium-voltage DC bus module can be 48V, 60V, 72V or 96V;

[0057] Energy storage modules can use batteries of different capacities or different chemical systems;

[0058] The inverter output module can be configured for different AC voltage or frequency specifications;

[0059] Communication methods can include CAN, RS-485, or other industrial buses;

[0060] Diesel engines can be of different numbers of cylinders or different cooling methods;

[0061] The generator can be a permanent magnet synchronous motor, an electrically excited motor, or other types of motors.

[0062] Working principle of this invention: This invention uses a medium-voltage DC bus module as its core to construct an energy transmission path from generator to bus to load. A diesel engine drives a permanent magnet synchronous generator to produce three-phase AC power, which is rectified and filtered to convert into high-voltage DC power. This DC power is then stepped down by a high-voltage DC converter module to the medium-voltage DC bus module. The energy storage module, inverter output module, and low-voltage auxiliary power supply module are all connected in parallel to the medium-voltage DC bus module.

[0063] During operation, the main controller collects the real-time operating status of each module via the CAN bus, including: engine speed, generator output power, actual output power of the high-voltage DC-DC converter module, bus voltage, state of charge and charge / discharge status of the energy storage module, and load power. The main controller internally runs a power scheduling algorithm, integrating the above information to generate a set of mutually matching instructions, which are then simultaneously sent to the engine ECU, the high-voltage DC-DC converter module, and the battery management system.

[0064] The core scheduling logic follows the principle of energy conservation: the generator output power equals the sum of the high voltage DC converter module output power and the energy storage module charging power minus the energy storage module discharge power and system losses.

[0065] The main controller solves the above energy conservation equation based on the load power and the state of charge of the energy storage module, and obtains a unique feasible solution for the engine target power, the target output power of the high voltage DC converter module and the target charging and discharging power of the energy storage module, and executes it simultaneously.

[0066] The main controller keeps the diesel engine operating stably within a preset high-efficiency power range (corresponding to a speed range of 2600-3000 rpm), ensuring that the diesel engine operates within its optimal specific fuel consumption range for extended periods. Under conditions of sudden load changes, the energy storage module, directly connected in parallel to the medium-voltage DC bus module, can respond to load changes within milliseconds. When the load suddenly increases, the energy storage module immediately discharges to replenish the power gap; when the load suddenly decreases, the energy storage module absorbs excess energy to recharge. This eliminates the need for the diesel engine to adjust to instantaneous load fluctuations, allowing it to consistently operate stably within the preset high-efficiency speed range, thereby significantly improving fuel economy. Compared to traditional diesel generator sets, fuel savings are more than 25% higher at the same power output.

[0067] Meanwhile, the high-voltage direct current converter module provides impedance isolation and power decoupling between the generator and the medium-voltage DC bus module, making the generator output voltage and the bus voltage independent of each other. The generator output voltage fluctuates with the speed, and after processing by the high-voltage direct current converter module, a stable medium-voltage DC power is output to the bus. There is no longer a hard-binding relationship between the diesel engine speed and the bus voltage, thus providing a physical basis for independent optimization of the diesel engine speed.

[0068] In summary, this invention constructs an energy dispatching platform centered on a medium-voltage DC bus module, enabling diesel engines to operate stably within a preset high-efficiency power range without relying on real-time load power tracking. This effectively solves the problem of low diesel engine operating efficiency in existing low-power diesel range extender systems. Furthermore, this invention directly connects an energy storage module in parallel to the medium-voltage DC bus module, utilizing its millisecond-level power response characteristics for instantaneous charging and discharging during load changes. This compensates for the response lag caused by mechanical inertia in diesel generator systems, effectively solving the problem of insufficient dynamic response capability. Through unified acquisition and coordinated dispatching of generator power, energy storage charging and discharging power, and load power consumption by the main controller, this invention achieves comprehensive energy optimization of the system, effectively solving the problem of single energy utilization methods and low overall efficiency. Finally, by independently connecting each functional module to the medium-voltage DC bus module using standardized interfaces, this invention allows the system to flexibly configure modules of different power levels according to application requirements without changing the overall architecture, effectively solving the problems of low modularity, poor scalability, and poor maintainability in existing solutions. This invention provides a systematic solution for small-power diesel range extenders that simultaneously achieves energy decoupling, power buffering, and modular expansion at the electrical architecture level.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modular electrical architecture for a low-power diesel range extender, comprising a mechanical power generation module, wherein the mechanical power generation module includes a diesel engine and a generator coaxially connected thereto, for converting the chemical energy of diesel fuel into alternating current electrical energy, characterized in that, Also includes: The rectifier and filter module is electrically connected to the mechanical power generation module and is used to rectify and filter the AC power into high-voltage DC power. The high-voltage DC-DC converter module has its input terminal electrically connected to the rectifier and filter module, and is used to convert high-voltage DC power into medium-voltage DC power. The medium-voltage DC bus module is electrically connected to the output of the high-voltage DC converter module to achieve energy decoupling between the generation side, energy storage side and load side. The energy storage module, connected in parallel to the medium-voltage DC bus module, is used to absorb or release energy when the load power changes, thereby smoothing out system power fluctuations. The inverter output module is electrically connected to the medium-voltage DC bus module and is used to convert medium-voltage DC power into AC power for use by AC loads. The low-voltage auxiliary power supply module is electrically connected to the medium-voltage DC bus and is used to convert medium-voltage DC power into low-voltage DC power. The main controller module is connected to the mechanical power generation module, the high-voltage DC conversion module, and the energy storage module. It is used to collect the operating status of each module and output control commands to coordinate the collaborative work of each module.

2. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The main controller module controls the diesel engine to operate stably within a preset high-efficiency power range, and uses the output power value corresponding to this high-efficiency power range as the target output power of the high-voltage DC converter module. When the load power is less than the target output power, the module controls the high-voltage DC converter module to charge the energy storage module. When the load power is greater than the target output power, the module controls the energy storage module to supplement the difference power through the medium-voltage DC bus.

3. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The high-voltage direct current converter module is configured to switch charging modes according to the state of charge of the energy storage module. The charging modes include constant current charging mode and constant voltage charging mode. The main controller module communicates with the high-voltage direct current converter module via a CAN bus. The main controller module sends a target output power command and an output voltage setting value to the high-voltage direct current converter module, and the high-voltage direct current converter module feeds back the actual output power, module temperature and fault status to the main controller module.

4. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The main controller module is configured to: cut off the load output when the state of charge of the energy storage module is lower than a first threshold; restore the load output when the state of charge recovers to a level higher than a second threshold; and control the load to consume the energy of the energy storage module when the state of charge is higher than a third threshold, until the state of charge is lower than the third threshold; wherein the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

5. The modular electrical architecture of the low-power diesel range extender according to claim 4, characterized in that, The first threshold is a state of charge of 50%, the second threshold is a state of charge of 80%, and the third threshold is a state of charge of 90%.

6. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The main controller module is configured to: control the diesel engine to stop when the state of charge of the energy storage module is greater than a first charge threshold and the load power is less than a first power threshold for a first preset time; and control the diesel engine to start when the load power is greater than a second power threshold for a second preset time, or when the state of charge is lower than a fourth threshold.

7. The modular electrical architecture of the low-power diesel range extender according to claim 6, characterized in that, The first charge threshold is 80% state of charge, the first power threshold is 300W, and the first preset time is 1 minute; the second power threshold is 300W, the second preset time is 30 seconds, and the fourth threshold is 50% state of charge.

8. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The diesel engine is a single-cylinder, four-stroke, electronically controlled, air-cooled diesel engine with a high-pressure common rail system and an engine control unit; the generator is a permanent magnet synchronous generator.

9. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The rated voltage of the medium-voltage DC bus is 48V to 96V; the rated output power of the modular electrical architecture is 1kW to 5kW.

10. The modular electrical architecture of the low-power diesel range extender according to claim 1, characterized in that, The energy storage module is a lithium iron phosphate battery pack, and the inverter output module is a pure sine wave inverter.

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