Heat pump direct current direct drive method and system based on two-way MPPT and two-way energy storage

Abstract

The invention discloses a heat pump direct current direct drive method and system based on two-way MPPT and two-way energy storage, and relates to the field of heat pump control systems. According to the invention, the photovoltaic power generation system is controlled to capture light and generate power by integrating the two independent MPPT controllers; acquiring the power generation power of the photovoltaic power generation system and the load power of the heat pump, and comparing the power generation power of the photovoltaic power generation system with the load power of the heat pump; when the power generation power of the photovoltaic power generation system is larger than the load power of the heat pump, the photovoltaic power generation system supplies power to the heat pump through the bidirectional DC-DC converter, and meanwhile, the redundant electric energy is stored in the energy storage module through the bidirectional DC-DC converter, and when the power generation power of the photovoltaic power generation system is smaller than the load power of the heat pump, the redundant electric energy is stored in the energy storage module. The photovoltaic power generation system and the energy storage module supply power to the heat pump through the bidirectional DC-DC converter at the same time. Through two-way flow transmission of electric quantity, the problem of energy dynamic unbalance in an existing photovoltaic direct drive heat pump system can be effectively solved, the system stability and the photovoltaic utilization rate are improved, and meanwhile dependence on a power grid is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of heat pump control systems. Specifically, it particularly relates to a heat pump direct current (DC) direct drive method and system based on dual-channel maximum power point tracking (MPPT) and bidirectional energy storage. Background Art

[0002] Currently, there are mainly two types of technical routes for photovoltaic direct drive heat pump air conditioning systems:

[0003] For the first type of AC-coupled system, a photovoltaic inverter is used to convert solar DC power into 220V / 230V AC power, and then it is secondarily converted into DC power through an AC / DC rectification device inside the heat pump to drive the compressor. This architecture has significant energy losses: Experimental data shows that the double-stage energy conversion (DC-AC-DC) causes the overall system efficiency to decrease by 18%-25%, and the high-frequency harmonics generated in the inversion link will exacerbate the electromagnetic interference problem.

[0004] For the second type of DC direct connection system, although the DC-DC converter is used to directly match the heat pump bus voltage (usually 280 - 350V DC), it has the following technical defects:

[0005] Energy dynamic imbalance: It is difficult to match the photovoltaic output power and the heat pump load demand in real time. When the photovoltaic power generation exceeds the load demand, the excess energy is forced to discard light due to the lack of an energy storage link; when the irradiance suddenly drops, the system needs to urgently switch to the AC power grid for power supply, resulting in a risk of interruption of power supply continuity (the switching delay can reach more than 500ms).

[0006] Control islanding: The existing system does not establish a real-time communication link with the heat pump host, and cannot dynamically adjust the power supply strategy according to the operating conditions of the compressor. When the heat pump operates at part load, the case where the photovoltaic utilization rate is lower than 40% accounts for more than 60%. Summary of the Invention

[0007] Aiming at the problems in the related technologies, the present invention proposes a heat pump DC direct drive method and system based on dual-channel MPPT and bidirectional energy storage to overcome the above-mentioned technical problems existing in the existing related technologies.

[0008] To solve the above technical problems, the present invention is realized through the following technical solutions:

[0009] The present invention provides a heat pump DC direct drive method based on dual-channel MPPT and bidirectional energy storage, including the following steps:

[0010] S1. Control the photovoltaic power generation system to capture and generate electricity through an integrated dual-channel independent MPPT controller;

[0011] S2. Obtain the power generation power of the photovoltaic power generation system and the heat pump load power, and compare the power generation power of the photovoltaic power generation system and the heat pump load power;

[0012] S3. When the power generation power of the photovoltaic power generation system is greater than the heat pump load power, the photovoltaic power generation system supplies power to the heat pump through the bidirectional DC-DC converter, and at the same time stores the excess electric energy in the energy storage module through the bidirectional DC-DC converter. When the power generation power of the photovoltaic power generation system is less than the heat pump load power, the photovoltaic power generation system and the energy storage module simultaneously supply power to the heat pump through the bidirectional DC-DC converter.

[0013] Further, it includes an integrated dual-channel independent MPPT controller, a photovoltaic power generation system, a bidirectional DC-DC converter, an energy storage module, and a heat pump;

[0014] The integrated dual-channel independent MPPT controller is used to control the photovoltaic power generation system to capture light and generate electricity;

[0015] The bidirectional DC-DC converter is used to deliver the electric energy of the photovoltaic power generation system to the energy storage module and the heat pump, and can also deliver the electric energy of the energy storage module to the heat pump;

[0016] The energy storage module is used to store the excess electric energy of the photovoltaic power generation system.

[0017] Further, the photovoltaic power generation system is connected to the heat pump through a 315V DC bus, and the bidirectional DC-DC converter is connected and installed on the 315V DC bus, and the bidirectional DC-DC converter is connected to the energy storage system through a 51.2V DC bus.

[0018] Further, the energy storage module is a lithium battery pack, and the bidirectional DC-DC converter establishes communication with the BMS of the lithium battery through CAN communication and charges the lithium battery using the SOC charging strategy.

[0019] Further, the bidirectional DC-DC converter is connected to the control system of the heat pump through CAN communication.

[0020] The present invention has the following beneficial effects:

[0021] 1. In the present invention, a dual-bus architecture of 315V DC on the photovoltaic side and 51.2V DC on the energy storage side is constructed, and bidirectional energy flow is realized through the bidirectional DC-DC converter. When the power generation power of the photovoltaic power generation system is greater than the heat pump load power, the photovoltaic power generation system supplies power to the heat pump through the bidirectional DC-DC converter, and at the same time stores the excess electric energy in the energy storage module through the bidirectional DC-DC converter. When the power generation power of the photovoltaic power generation system is less than the heat pump load power, the photovoltaic power generation system and the energy storage module simultaneously supply power to the heat pump through the bidirectional DC-DC converter; through the bidirectional flow and delivery of electric energy, the problem of energy dynamic imbalance in the existing photovoltaic direct-drive heat pump system can be effectively solved, the system stability and photovoltaic utilization rate can be improved, and at the same time, the dependence on the power grid can be reduced.

[0022] 2. In the present invention, the photovoltaic power generation system is controlled by integrating a dual-channel independent MPPT controller, which can improve the photovoltaic capture efficiency compared with a single-channel system, thereby enhancing the power generation efficiency of the photovoltaic power generation system.

[0023] 3. In the present invention, a CAN communication protocol is established for data interaction with the heat pump control system to achieve millisecond-level coordinated control of the power supply strategy and the heat pump load, further improving the stability of the heat pump operation.

[0024] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To more clearly illustrate the technical solutions of the embodiments of the invention, the following will briefly introduce the drawings required for describing the embodiments. Obviously, the drawings in the following description are only some embodiments of the invention, and for those of ordinary skill in the art, without creative efforts, additional drawings can be obtained based on these drawings.

[0026] Figure 1 It is the flowchart of the heat pump direct drive control of the present invention;

[0027] Figure 2 It is the block diagram of the heat pump direct drive control system of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the invention with reference to the drawings in the embodiments of the invention. Obviously, the described embodiments are only some embodiments of the invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the invention without creative efforts fall within the scope of protection of the invention.

[0029] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "top", "middle", "inner", etc. indicating the orientation or position relationship are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the invention.

[0030] Embodiment 1

[0031] Please refer to Figure 1 As shown, this embodiment is a heat pump DC direct drive method based on dual-channel MPPT and bidirectional energy storage, including the following steps:

[0032] S1. Control the photovoltaic power generation system to capture and generate electricity by integrating a dual-channel independent MPPT controller;

[0033] S2. Obtain the power generation power of the photovoltaic power generation system and the heat pump load power, and compare the power generation power of the photovoltaic power generation system with the heat pump load power;

[0034] S3. When the power generation power of the photovoltaic power generation system is greater than the heat pump load power, the photovoltaic power generation system supplies power to the heat pump through the bidirectional DC-DC converter, and at the same time stores the excess electric energy in the energy storage module through the bidirectional DC-DC converter. When the power generation power of the photovoltaic power generation system is less than the heat pump load power, the photovoltaic power generation system and the energy storage module supply power to the heat pump through the bidirectional DC-DC converter at the same time.

[0035] Among them, through the bidirectional flow and transmission of electric energy, the problem of energy dynamic imbalance in the existing photovoltaic direct-drive heat pump system can be effectively solved, the system stability and photovoltaic utilization rate can be improved, and at the same time, the dependence on the power grid can be reduced through the bidirectional flow and transmission of electric energy.

[0036] Embodiment 2

[0037] Please refer to Figure 2 As shown, a heat pump DC direct-drive system based on dual-channel MPPT and bidirectional energy storage in this embodiment includes an integrated dual-channel independent MPPT controller, a photovoltaic power generation system, a bidirectional DC-DC converter, an energy storage module, and a heat pump;

[0038] The integrated dual-channel independent MPPT controller is used to control the photovoltaic power generation system to capture light and generate electricity;

[0039] The bidirectional DC-DC converter is used to deliver the electric energy of the photovoltaic power generation system to the energy storage module and the heat pump, and can also deliver the electric energy of the energy storage module to the heat pump;

[0040] The energy storage module is used to store the excess electric energy of the photovoltaic power generation system.

[0041] Specifically, the photovoltaic power generation system is connected to the heat pump through a 315V DC bus, and the bidirectional DC-DC converter is connected and installed on the 315V DC bus. The bidirectional DC-DC converter is connected to the energy storage system through a 51.2V DC bus; when the power generation power of the photovoltaic power generation system exceeds the heat pump demand, the excess electric energy is converted into 58.4Vdc by the bidirectional DC-DC converter and stored in the energy storage module. When the photovoltaic power is insufficient (such as at night or on cloudy days), the bidirectional DC-DC converter boosts the 51.2Vdc in the energy storage module to 315Vdc to supplement the heat pump load demand and ensure the continuity of power supply.

[0042] Specifically, the energy storage module is a lithium battery pack. The bidirectional DC-DC converter establishes communication with the BMS of the lithium battery through CAN communication, and uses the SOC charging strategy to charge the lithium battery. It can monitor the battery SOC (state of charge), SOH (state of health), charge and discharge current, optimize the charge and discharge strategy, avoid overcharging and over-discharging, and automatically adjust the power supply mode when the SOC is lower than the safety threshold to ensure system safety.

[0043] Specifically, the bidirectional DC-DC converter is connected to the control system of the heat pump through CAN communication, and obtains the operating state of the heat pump (such as the compressor power demand) through CAN communication, realizes the millisecond-level coordinated adjustment of the power supply strategy, avoids system power mismatch caused by sudden load changes, and improves the power supply stability.

[0044] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0045] The preferred embodiments of the invention disclosed above are only used to help explain the invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the invention, so that those skilled in the art can understand and utilize the invention well.

Claims

1. A heat pump direct current direct drive method based on dual - path MPPT and bidirectional energy storage, characterized in that, It includes the following steps: S1. Control the photovoltaic power generation system to capture light and generate electricity through an integrated dual-channel independent MPPT controller; S2. Obtain the power generation power of the photovoltaic power generation system and the heat pump load power, and compare the power generation power of the photovoltaic power generation system with the heat pump load power; S3. When the power generation power of the photovoltaic power generation system is greater than the heat pump load power, the photovoltaic power generation system supplies power to the heat pump through a bidirectional DC-DC converter, and at the same time stores the excess electric energy in the energy storage module through the bidirectional DC-DC converter. When the power generation power of the photovoltaic power generation system is less than the heat pump load power, the photovoltaic power generation system and the energy storage module supply power to the heat pump through the bidirectional DC-DC converter at the same time.

2. The heat pump direct current direct drive system based on dual-channel MPPT and bidirectional energy storage according to claim 1, characterized in that: It includes an integrated dual-channel independent MPPT controller, a photovoltaic power generation system, a bidirectional DC-DC converter, an energy storage module and a heat pump; The integrated dual-channel independent MPPT controller is used to control the photovoltaic power generation system to capture light and generate electricity; The bidirectional DC-DC converter is used to deliver the electric energy of the photovoltaic power generation system to the energy storage module and the heat pump, and can also deliver the electric energy of the energy storage module to the heat pump; The energy storage module is used to store the excess electric energy of the photovoltaic power generation system.

3. The heat pump direct current direct drive system based on dual - path MPPT and bidirectional energy storage according to claim 2, wherein: The photovoltaic power generation system is connected to the heat pump through a 315V DC bus, and the bidirectional DC-DC converter is connected and installed on the 315V DC bus. The bidirectional DC-DC converter is connected to the energy storage system through a 51.2V DC bus.

4. A heat pump direct current direct drive system based on dual - path MPPT and bidirectional energy storage according to claim 2, wherein: The energy storage module is a lithium battery pack. The bidirectional DC-DC converter establishes communication with the BMS of the lithium battery through CAN communication and charges the lithium battery using the SOC charging strategy.

5. A heat pump direct current direct drive system based on dual-channel MPPT and bidirectional energy storage according to claim 2, characterized in that: The bidirectional DC-DC converter is connected to the control system of the heat pump through CAN communication.

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