Low-loss power frequency sine wave inverter circuit

Abstract

The utility model belongs to the technical field of inverter circuits, and particularly relates to a low-loss power frequency sine wave inverter circuit which comprises a storage battery pack, a PWM inverter circuit and a primary end of a transformer winding which are electrically connected in sequence, a series-parallel switching relay is arranged on the transformer winding, and a secondary end of the transformer winding is electrically connected with an alternating current power supply port. A load detection module is arranged between the secondary end of the transformer winding and the alternating current power supply port, the load detection module is electrically connected with a comparison module, the comparison module is electrically connected with a relay switch module and a rectification signal module, and the relay switch module is electrically connected with a control terminal of a series-parallel switching relay. The rectification signal module is electrically connected with the PWM inverter circuit. According to the power frequency inverter circuit provided by the utility model, the series-parallel connection of transformer windings can be switched and the PWM duty ratio can be adjusted as required by detecting the electric power of the load, so that the effects of reducing the no-load loss of the power frequency inverter when the electric power of the load is small, reducing the energy consumption and improving the energy efficiency are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of inverter circuits, and in particular to a low-loss industrial frequency sine wave inverter circuit. Background Art

[0002] Conventional power-frequency inverters currently on the market all use standard principles to output 220V AC power. Furthermore, their switching modes are also conventional, and there's no way to reduce normal losses. Losses currently depend entirely on the quality of the materials. However, high-quality materials are expensive, but in practice, most customers demand cost-effective products. Therefore, simply reducing losses through materials alone is insufficient, which is the fundamental reason why losses in current power-frequency inverters remain stubbornly low.

[0003] For example, in the patent document with the patent number CN201320615248.X and the name “A Power Frequency Inverter Circuit”, a power frequency inverter circuit is disclosed, which includes an MCU controller, a battery, an input voltage sampling circuit, a DC bus switch current waveform correction circuit, a power frequency isolation transformer, a switch MOS tube circuit, an output voltage sampling circuit and an output load feedback circuit. The battery is connected to the DC input terminal and is connected to the DC bus switch current waveform correction circuit, the power frequency isolation transformer, the switch MOS tube circuit, the output voltage sampling circuit and the output load feedback circuit in sequence through the input voltage sampling circuit. Although its inverter efficiency reaches 92% in the power range below 3kW, it can effectively reduce the volume of the aluminum profile radiator. However, when the load power is small, there is a problem of no-load loss, and the energy-saving effect is poor. Utility Model Content

[0004] In order to solve the problem that the current general industrial frequency inverter circuit has high no-load loss and low energy conversion efficiency when the load power is small, and the energy saving effect mainly relies on the use of high-quality and expensive circuit components to improve, it is difficult to maintain a low product production cost while improving the product energy saving effect, a low-loss industrial frequency sine wave inverter circuit is provided.

[0005] A low-loss industrial frequency sinusoidal wave inverter circuit includes a battery pack, a PWM inverter circuit, and the primary end of a transformer winding electrically connected in sequence. A series-parallel switching relay is provided on the transformer winding. The secondary end of the transformer winding is electrically connected to an AC power supply port. A load detection module is provided between the secondary end of the transformer winding and the AC power supply port. The load detection module is electrically connected to a comparison module. The comparison module is electrically connected to a relay switch module and a rectifier signal module. The relay switch module is electrically connected to the control terminal of the series-parallel switching relay. The rectifier signal module is electrically connected to the PWM inverter circuit.

[0006] Furthermore, the comparison module, relay switch module and rectification signal module are all arranged in the main control MCU, and the main control MCU is electrically connected to the load detection module, the control terminal of the series-parallel switching relay and the PWM inverter circuit.

[0007] Furthermore, the AC power supply port is electrically connected to a normally closed relay and a mains input port in sequence, and the control terminal of the normally closed relay and the AC power supply port are both electrically connected to a main control MCU.

[0008] Furthermore, the output end of the normally closed relay is electrically connected to the AC / DC conversion module, the charging management module, and the battery pack in sequence.

[0009] Furthermore, the charging management module includes a power management chip, the AC / DC conversion module and the charging management module are electrically connected via a switch module, and the switch module is electrically connected to the power management chip.

[0010] Furthermore, a cooling fan is provided on the side of the PWM inverter circuit, and the cooling fan is electrically connected to the main control MCU.

[0011] Furthermore, the load detection module includes a current transformer, which is sleeved on the outside of the live wire end of the AC power supply port, and is electrically connected to the comparison module.

[0012] The advantages of the present invention are:

[0013] 1. It can effectively reduce the no-load loss of the power frequency inverter circuit when the load power is small, improve the energy conversion efficiency, and save energy and protect the environment.

[0014] 2. Utilize MCU linkage to automatically switch the series and parallel connection of transformer windings and the PWM duty cycle. Automatic operation does not require manual control and is easy to use.

[0015] 3. When the mains power supply is sufficient, the battery pack can be continuously charged to maintain sufficient power. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is the connection principle block diagram of the low-loss industrial frequency sine wave inverter circuit;

[0018] Figure 2This is the circuit schematic diagram of the AC power supply terminal, normally closed relay, mains input port and load detection module;

[0019] Figure 3 This is the circuit schematic diagram of the transformer winding;

[0020] Figure 4 This is the circuit schematic diagram of the PWM inverter circuit;

[0021] Figure 5 This is the circuit schematic diagram of the main control MCU;

[0022] Figure 6 This is the circuit schematic diagram of the AC / DC conversion module and the charging management module;

[0023] Figure 7 This is the circuit schematic diagram of the cooling fan.

[0024] Figure ID:

[0025] 1. Battery pack; 2. PWM inverter circuit; 3. Transformer winding; 4. Series-parallel switching relay; 5. AC power supply port; 6. Load detection module; 7. Main control MCU; 701. Comparison module; 702. Relay switch module; 703. Rectification signal module; 8. Normally closed relay; 9. Mains power input port; 10. AC / DC conversion module; 11. Charging management module; 111. Power management chip; 12. Switch module; 13. Cooling fan. DETAILED DESCRIPTION

[0026] In order to solve the problem that the current general industrial frequency inverter circuit has high no-load loss and low energy conversion efficiency when the load power is small, and the energy saving effect mainly relies on the use of high-quality and expensive circuit components to improve, it is difficult to maintain a low product production cost while improving the product energy saving effect, a low-loss industrial frequency sine wave inverter circuit is provided.

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "within", "in" and "a" cited in this specification are only for the convenience of description and are not intended to limit the scope of the implementation of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the implementation of the present invention, and should be stated in advance.

[0029] In the description of this utility model, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the utility model and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the utility model. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and should not be construed to indicate or imply relative importance or implicitly specify the number of the technical features referred to. Thus, a feature defined as "first," "second," and the like may explicitly or implicitly include one or more of such features. In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can mean fixed connection, removable connection, or integral connection; they can mean direct connection, indirect connection through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0030] like Figures 1 to 7 As shown, this embodiment provides a low-loss industrial frequency sinusoidal wave inverter circuit, including a battery pack 1, a PWM inverter circuit 2, and a primary end of a transformer winding 3 electrically connected in sequence, a series-parallel switching relay 4 is provided on the transformer winding 3, and a secondary end of the transformer winding 3 is electrically connected to an AC power supply port 5. A load detection module 6 is provided between the secondary end of the transformer winding 3 and the AC power supply port 5, and the load detection module 6 is electrically connected to a comparison module 701, and the comparison module 701 is electrically connected to a relay switch module 702 and a rectifier signal module 703. The relay switch module 702 is electrically connected to a control terminal of the series-parallel switching relay 4, and the rectifier signal module 703 is electrically connected to the PWM inverter circuit 2.

[0031] The DC power output by the battery pack 1 is converted into AC power by the PWM inverter circuit 2 and the transformer winding 3, and then supplied to the load connected to the AC power supply port 5. The load detection module 6 typically utilizes a current transformer. The comparison module 701 determines and compares the load power detected by the load detection module 6, thereby initiating corresponding actions by the relay switch module 702 and the rectifier signal module 703.

[0032] The specific operating mechanism of this embodiment is as follows:

[0033] 1. When the load power detected by the load detection module 6 is less than 200W, the series-parallel switching relay 4 does not operate, the transformer winding 3 remains connected in series, and the PWM signal duty cycle output by the rectifier signal module 703 to the PWM inverter circuit 2 is 50% of the normal mode. This effectively reduces the no-load loss of the power frequency inverter circuit when the load power is low. Losses can be reduced by up to 70%, effectively reducing energy consumption.

[0034] 2. When the load power detected by the load detection module 6 is greater than 200W, the series-parallel switching relay 4 is activated, the transformer winding 3 is switched to parallel, and the duty cycle of the PWM signal output by the rectifier signal module 703 to the PWM inverter circuit 2 is 100%, ensuring sufficient power output.

[0035] The comparison module 701, relay switch module 702, and rectifier signal module 703 are all housed within the main control MCU 7, which is electrically connected to the load detection module 6, the control terminals of the series-parallel switching relay 4, and the PWM inverter circuit 2. The modules for determining and sending linkage signals can be integrated into commonly available MCU chips (such as the STM32F0 series MCUs) to ensure long-term stable operation of the circuit.

[0036] The AC power supply port 5 is electrically connected to a normally closed relay 8 and a mains input port 9 in sequence. The control terminal of the normally closed relay 8 and the AC power supply port 5 are both electrically connected to the main control MCU 7. When the mains supply is stable, the mains normally closed relay 8 outputs power to the AC power supply port 5 directly to power the load. When the main control MCU 7 detects a mains power outage, it closes the normally closed relay 8 and disconnects the mains input port 9, automatically switching the circuit to inverter mode for ease of use.

[0037] The output of the normally closed relay 8 is electrically connected in sequence to the AC / DC conversion module 10, the charging management module 11, and the battery pack 1. When the AC power supply is stable, the AC / DC conversion module 10 and the charging management module 11 (rectifier circuit) convert the AC power into a DC power source for charging the battery pack 1, maintaining a sufficient charge in the battery pack 1.

[0038] The charging management module 11 includes a power management chip 111. The AC / DC conversion module 10 and the charging management module 11 are electrically connected via a switch module 12, which is electrically connected to the power management chip 111. In this embodiment, the switch module 12 uses an optocoupler switch, and the power management chip 111 uses an SC9103. This allows for prompt charging halts in the event of a circuit fault, preventing damage to the battery pack 1 and improving device safety.

[0039] A cooling fan 13 is provided on the side of the PWM inverter circuit 2 and is electrically connected to the main control MCU 7. Since the PWM inverter circuit 2 generates considerable heat during operation, a cooling fan 13 is provided to cool the circuit to ensure long-term stable operation of the device. The main control MCU 7 can adjust the speed of the cooling fan 13 according to the operating status.

[0040] The load detection module 6 includes a current transformer, which is sleeved onto the outside of the live wire terminal of the AC power supply port 5 and is electrically connected to the comparison module 701. In this embodiment, the load detection module 6 uses a ZHT123 miniature current transformer, which can reduce the footprint of the circuit hardware and ensure accurate and stable data output of the detected load power.

[0041] During operation of this embodiment, when the AC power supply is sufficient, the AC power supply, normally closed relay 8, directly outputs the AC power to the load, while the battery pack 1 continues to charge. When the main control MCU 7 detects a power outage, it activates normally closed relay 8 to disconnect the AC power circuit, causing the circuit to enter an inverter state. At this point, the DC power output from the battery pack 1 is converted to AC power by the PWM inverter circuit 2 and transformer winding 3, and then output to the AC power supply port 5, replacing the AC power supply for the load.

[0042] The above content is a further detailed description of the present invention in combination with specific preferred implementation methods. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. That is, all equivalent changes and modifications made within the scope of this application should still fall within the scope of the present invention.

Claims

1. Low-loss industrial frequency sine wave inverter circuit, characterized in that: It includes a battery pack, a PWM inverter circuit, and a primary end of a transformer winding that are electrically connected in sequence. A series-parallel switching relay is provided on the transformer winding. The secondary end of the transformer winding is electrically connected to an AC power supply port. A load detection module is provided between the secondary end of the transformer winding and the AC power supply port. The load detection module is electrically connected to a comparison module. The comparison module is electrically connected to a relay switch module and a rectifier signal module. The relay switch module is electrically connected to a control terminal of the series-parallel switching relay. The rectifier signal module is electrically connected to the PWM inverter circuit.

2. The low-loss industrial frequency sine wave inverter circuit according to claim 1, characterized in that: The comparison module, relay switch module and rectification signal module are all arranged in the main control MCU, and the main control MCU is electrically connected to the load detection module, the control terminal of the series-parallel switching relay and the PWM inverter circuit.

3. The low-loss industrial frequency sine wave inverter circuit according to claim 2, characterized in that: The AC power supply port is electrically connected to the normally closed relay and the mains input port in sequence, and the control terminal of the normally closed relay and the AC power supply port are both electrically connected to the main control MCU.

4. The low-loss industrial frequency sine wave inverter circuit according to claim 3, characterized in that: The output end of the normally closed relay is electrically connected to the AC / DC conversion module, the charging management module, and the battery pack in sequence.

5. The low-loss industrial frequency sine wave inverter circuit according to claim 4, characterized in that: The charging management module includes a power management chip. The AC / DC conversion module and the charging management module are electrically connected via a switch module, and the switch module is electrically connected to the power management chip.

6. The low-loss industrial frequency sine wave inverter circuit according to claim 2, characterized in that: A cooling fan is provided on the side of the PWM inverter circuit, and the cooling fan is electrically connected to the main control MCU.

7. The low-loss industrial frequency sine wave inverter circuit according to claim 1, characterized in that: The load detection module includes a current transformer, which is sleeved on the outside of the live wire end of the AC power supply port and is electrically connected to the comparison module.

Images