Voltage acquisition module of power factor improvement circuit and air conditioner
By employing a peak hold circuit and a voltage divider module in the power factor improvement circuit, the problem of high cost of large-volume electrolytic capacitors was solved, and the capacitance value and circuit board size were reduced, thus lowering the cost.
Patent Information
- Application Number
- CN202520209154.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-02-10
AI Technical Summary
In existing power factor improvement circuits, the high cost of large-volume electrolytic capacitors results in a large overall PCB size, making it difficult to reduce the capacitance value to achieve cost reduction.
A peak hold circuit is constructed using a first unidirectional conduction module and a first capacitor module. The first unidirectional conduction module charges the first capacitor module in one direction, causing its voltage to reach the peak level and stabilize. Combined with a voltage divider module and a resistor module, the capacitance value and volume are reduced, ensuring that the controller can acquire a stable voltage.
This technology enables the controller to acquire a stable voltage even with small capacitance values, reducing waveform distortion caused by fluctuations, minimizing the size of capacitors and circuit boards, and lowering costs.
Smart Images
Figure CN223899130U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of circuit technology for home appliances, and in particular to voltage acquisition modules for power factor improvement circuits and air conditioners. Background Technology
[0002] In recent years, harmonic standards have been established for electrical products other than home appliances, so power factor improvement circuits are commonly used in electrical products.
[0003] In power factor improvement circuits, large-volume components such as electrolytic capacitors are expensive, and the overall PCB size is also large.
[0004] The technical problem this application aims to solve is how to reduce the capacitance value of electrolytic capacitors in large-volume components and achieve cost reduction. Utility Model Content
[0005] The purpose of this application is to provide a voltage acquisition module for a power factor improvement circuit and an air conditioner, in order to solve the technical problem of how to reduce the capacitance value of large-volume components such as electrolytic capacitors and achieve cost reduction.
[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions.
[0007] In a first aspect, embodiments of this application provide a voltage acquisition module applied to a power factor improvement circuit, the power factor improvement circuit including a controller and a controlled module, the controller acquiring the output voltage of the controlled module through the voltage acquisition module;
[0008] The voltage acquisition module includes a first unidirectional conduction module and a first capacitor module;
[0009] The input terminal of the first unidirectional conduction module is connected to the voltage output terminal of the controlled module, the output terminal of the first unidirectional conduction module is connected to the first terminal of the first capacitor module, and the second terminal of the first capacitor module is grounded; the first terminal of the first capacitor module is connected to the voltage acquisition terminal of the controller.
[0010] Optionally, the voltage acquisition module further includes a voltage divider module, wherein the input terminal of the first unidirectional conduction module is connected to the voltage output terminal of the controlled module through the voltage divider module;
[0011] The voltage divider module includes a first resistor module and a second resistor module;
[0012] The voltage output terminal of the controlled module, the first resistor module, the second resistor module and ground are connected in sequence;
[0013] The connection point between the first resistor module and the second resistor module is connected to the input terminal of the first unidirectional conduction module.
[0014] Optionally, the voltage acquisition module further includes a third resistor module, which is connected to both ends of the first capacitor module.
[0015] Optionally, the first unidirectional conduction module is a diode, the input terminal of the first unidirectional conduction module is the anode of the diode, and the output terminal of the first unidirectional conduction module is the cathode of the diode.
[0016] Optionally, the controlled module includes a rectifier module, an inductor module, a switch module, a second unidirectional conduction module, and a second capacitor module;
[0017] The input terminal of the rectifier module is used to connect to an AC power source;
[0018] The first output terminal of the rectifier module is connected to the first terminal of the inductor module, the second terminal of the inductor module is connected to the first terminal of the switch module and the first terminal of the second unidirectional conduction module, and the second terminal of the switch module is connected to the second output terminal of the rectifier module.
[0019] The second terminal of the second unidirectional conduction module is connected to the first terminal of the second capacitor module, and the second terminal of the second capacitor module is connected to the second output terminal of the rectifier module; the first and second terminals of the second capacitor module are used to connect to the load; the first terminal of the second capacitor module is the voltage output terminal of the controlled module.
[0020] The power factor improvement circuit also includes a switch drive module and a current detection module;
[0021] The controller is connected to the control terminal of the switch module through the switch driver module;
[0022] The controller is used to obtain the current flowing through the switching module or the inductor module through the current detection module.
[0023] Optionally, the second unidirectional conduction module includes a fast recovery diode.
[0024] Optionally, the capacitance value of the second capacitor module is less than or equal to 100μF.
[0025] Optionally, the current detection module is connected in series with the switch module.
[0026] Optionally, the current detection module is connected in series with the inductor module.
[0027] Secondly, embodiments of this application provide an air conditioner, which includes the voltage acquisition module described in the first aspect.
[0028] Compared with the prior art, this application has the following advantages:
[0029] In the voltage acquisition module provided in this application embodiment, the first unidirectional conduction module and the first capacitor module constitute a peak hold circuit. By unidirectionally charging the first capacitor module through the first unidirectional conduction module, the voltage of the first capacitor module can reach the peak level and stabilize, avoiding large fluctuations and reducing the possibility of subsequent waveform distortion caused by fluctuations. Even if a small capacitor is used at the output of the power factor improvement circuit, the controller can still acquire a stable voltage, thereby reducing the possibility of subsequent waveform distortion caused by fluctuations. Therefore, the capacitance value and volume of the capacitor in the power factor improvement circuit can be reduced, further reducing the size of the circuit board and contributing to cost reduction in the product. Attached Figure Description
[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0031] Figure 1 This is a schematic diagram of a power factor improvement circuit;
[0032] Figure 2 A schematic diagram of the control principle of a power factor improvement circuit;
[0033] Figure 3 for Figure 1 The diagram shows the Iref 1 waveform of the power factor improvement circuit using an electrolytic capacitor.
[0034] Figure 4 for Figure 1 The diagram shows the Iref 2 waveform of the power factor improvement circuit using an electrolytic capacitor.
[0035] Figure 5 for Figure 1 The diagram shows the Vdc waveform of the power factor improvement circuit when using electrolytic capacitors.
[0036] Figure 6 for Figure 1 The diagram shows the input current of the power factor improvement circuit when using an electrolytic capacitor.
[0037] Figure 7 for Figure 1 The diagram shows the Iref 1 waveform of the power factor improvement circuit when a small capacitor is used.
[0038] Figure 8 for Figure 1The diagram shows the Iref 2 waveform of the power factor improvement circuit when a small capacitor is used.
[0039] Figure 9 for Figure 1 The diagram shows the Vdc waveform of the power factor improvement circuit when a small capacitor is used.
[0040] Figure 10 for Figure 1 The diagram shows the input current of the power factor improvement circuit when using a small capacitor.
[0041] Figure 11 A schematic diagram of a power factor improvement circuit provided in an embodiment of this application is shown. The power factor improvement circuit includes a voltage acquisition module with peak hold function.
[0042] Figure 12 This is a schematic diagram illustrating how the voltage acquisition module maintains the peak value.
[0043] Figure 13 A schematic diagram of a voltage acquisition module including a voltage divider module provided in an embodiment of this application;
[0044] Figure 14 for Figure 13 The circuit shown is illustrated with a simulation waveform diagram. Detailed Implementation
[0045] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described in the accompanying drawings can generally be arranged and designed in various different configurations.
[0046] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0047] In the description of this application, it should be noted that:
[0048] Relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations;
[0049] "Connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.
[0050] like Figure 1 , Figure 1 A power factor improvement circuit is shown that can be used on the DC voltage (Vdc) on the boost output side of an inverter. This power factor improvement circuit is a boost circuit.
[0051] A power factor improvement circuit may consist of a controller and a controlled module. The controller may be an MCU, and the connection relationship of the controller is not entirely... Figure 1 Not shown, the controlled module includes a rectifier module, an inductor module L1, a switch module SW1, a second unidirectional conduction module D5, and a second capacitor module C1. The switch module SW1 may include an IGBT or a MOSFET. The second unidirectional conduction module D5 may be a fast recovery diode.
[0052] The power factor improvement circuit receives alternating current (AC) as input. This AC current is rectified by a rectifier module, which includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The first output terminal of the rectifier module is connected to the first terminal of the inductor module L1. The second terminal of the inductor module L1 is connected to the first terminal of the switch module SW1 and the first terminal of the second unidirectional conduction module D5. The second terminal of the switch module SW1 is connected to the second output terminal of the rectifier module. The second terminal of the second unidirectional conduction module D5 is connected to the first terminal of the second capacitor module C1. The second terminal of the second capacitor module C1 is connected to the second output terminal of the rectifier module. The first and second terminals of the second capacitor module C1 are used to connect to the load. The first terminal of the second capacitor module C1 is the voltage output terminal of the controlled module, and the second terminal of the second capacitor module C1 is ground (GND).
[0053] The second terminal of the switching module SW1 can be connected to the second output terminal of the rectifier module through a current detection module, thereby enabling the detection of the current I passing through the switching module SW1. SW The detection.
[0054] Regarding the output voltage Vdc of the power factor improvement circuit, which is the voltage between the first and second terminals of the second capacitor module C1, multiple resistors can be connected between the first and second terminals of the second capacitor module C1 to divide the voltage. A certain proportion of the voltage of the second capacitor module C1 can be used to connect to the MCU to realize the detection of the output voltage.
[0055] The MCU can control the switching module SW1 to open and close based on the detection of current and output voltage through the switching driver module. For example... Figure 2The output voltage Vdc is set to be greater than the square root of the AC input voltage. The difference ΔV between the output voltage Vdc detected by the voltage detection module and the set value is calculated using an AVR (Auto Voltage Regulator), resulting in Iref1. The AVR can be a PI controller for voltage control. The MCU controls ΔV to be as close to zero as possible, meaning the output voltage Vdc matches its set value. In the diagram, ABS represents an absolute value function. Iref2 is obtained by multiplying the voltage detected by the absolute value-modified voltage detection module by Iref1, synchronizing the AC input voltage with Iref2. Then, an ACR (Auto Current Regulator) is used to ensure the current Isw passing through the switching module SW1 matches Iref2. The ACR can be a PI controller for current control. The resulting PWM signal is used to control the switching module SW1, thus satisfying the requirement that the output voltage Vdc matches the set value while improving the power factor.
[0056] for Figure 1 As shown, the second capacitor module C1 requires a large electrolytic capacitor. When the capacitance of the second capacitor module C1 is 1000μF, the waveforms of the power factor improvement circuit are as follows. Figures 3 to 6 ,like Figure 3 Although Vdc will generate a ripple voltage of a few percentage points, the signal waveform of Iref 2 is not distorted, such as Figure 4 No harmonics are generated in the voltage waveform of Vdc and the input current waveform of the AC power supply, such as... Figure 5 , Figure 6 .
[0057] If the electrolytic capacitor in the second capacitor module C1 is replaced with a capacitor with a smaller capacitance value, since the second capacitor module C1 is the DC power source for the load, a reduction in capacitance will result in a large current charging and discharging, and generate ripple current.
[0058] For example, the capacitance value of the second capacitor module C1 is reduced to tens of μF for simulation. The input voltage of the power factor improvement circuit is set to 220Vrms (310V peak), a 50Ω resistor is used as the load, and the second capacitor module C1 uses a 20μF capacitor. The waveforms are as follows. Figures 7 to 10 At this time, the voltage Vdc of the second capacitor module C1 will generate a ripple voltage exceeding 10%. Therefore, although the Vdc value detected by the MCU is considered a DC value, it is not actually a DC value. In other words, the value of Iref 1 is also not a DC value. Figure 7 Furthermore, when multiplied by the voltage detected by the absolute value-based voltage detection module, Iref 2 becomes distorted, such as... Figure 8 Therefore, Vdc generates a ripple voltage such as Figure 9 Harmonic currents are generated in the input current, such as Figure 10 The power factor deteriorated, with the simulated power factor being 89.5%.
[0059] This application provides a voltage acquisition module that enables the controller to obtain the output voltage Vdc of the controlled module, ensuring a good power factor even when the electrolytic capacitor in the second capacitor module C1 is replaced with a capacitor of a smaller value.
[0060] like Figure 11 The voltage acquisition module includes a first unidirectional conduction module D6 and a first capacitor module C2. The input terminal of the first unidirectional conduction module D6 is connected to the voltage output terminal of the controlled module, which can be the positive terminal of the second capacitor module C1. The output terminal of the first unidirectional conduction module D6 is connected to the first terminal of the first capacitor module C2, and the second terminal of the first capacitor module C2 is grounded. The first terminal of the first capacitor module C2 is connected to the voltage acquisition terminal of the controller.
[0061] The first unidirectional conduction module D6 can be a diode. The input terminal of the first unidirectional conduction module D6 is the anode of the diode, and the output terminal of the first unidirectional conduction module D6 is the cathode of the diode.
[0062] The first unidirectional conducting module D6 and the first capacitor module C2 constitute a peak holding circuit. By unidirectionally charging the first capacitor module C2 through the first unidirectional conducting module D6, the voltage of the first capacitor module C2 can be brought to a peak level and stabilized. This peak value is then used to replace the originally sampled voltage. Even if the originally sampled voltage fluctuates significantly, the stable peak value ensures that the voltage remains stable. Figure 12 The voltage collected now avoids large fluctuations and reduces the possibility of subsequent waveform distortion caused by fluctuations.
[0063] Therefore, even if the second capacitor module C1 in the power factor improvement circuit uses a small capacitor, such as one less than or equal to 100μF, the controller can still acquire a stable voltage, thereby reducing the possibility of waveform distortion caused by fluctuations. This allows for a reduction in the capacitance value and size of the capacitors in the power factor improvement circuit, further reducing the size of the circuit board and contributing to lower product costs.
[0064] like Figure 13 The voltage acquisition module may also include a voltage divider module. The input terminal of the first unidirectional conduction module may not be directly connected to the voltage output terminal of the controlled module, but is connected to the voltage output terminal of the controlled module through the voltage divider module. The voltage divider module can reduce the voltage by a certain ratio, thereby facilitating detection by controllers such as MCUs.
[0065] The voltage divider module may include a first resistor module and a second resistor module. The voltage output terminal of the controlled module, the first resistor module, the second resistor module and ground are connected in sequence. The connection point of the first resistor module and the second resistor module is connected to the input terminal of the first unidirectional conduction module. Figure 13 In the embodiment shown, the first resistor module includes resistor R1, resistor R2 and resistor R3, and the second resistor module includes resistor R4.
[0066] The voltage acquisition module may also include a third resistor module R5, which is connected across the first capacitor module C2. The third resistor module R5 and the first capacitor module C2 form a low-pass filter, and the third resistor module R5 can also safely release the voltage of the first capacitor module C2 in the event of power failure.
[0067] Figure 13 In the illustrated embodiment, the current detection module is connected in series with the switch module SW1, and the current detected by the current detection module is the current passing through the switch module SW1. If the current detection module is set to be connected in series with the inductor module L1, the current detected by the current detection module is the current passing through the inductor module L1, and the controller controls the switch module SW1 based on the current of the inductor module L1 and the voltage detected by the voltage acquisition module.
[0068] Using the voltage acquisition module described above, and still employing a small capacitor for simulation, with the power factor correction circuit input voltage set to 220Vrms (310V peak), a 50Ω resistor used as the load, and the second capacitor module C1 using a 20μF capacitor, the simulated waveform is as follows. Figure 14 Iref 1 will no longer change, although Vdc will still produce similar results. Figure 9 The ripple voltage and current command Iref2 were not distorted, the harmonic current of the input current was greatly improved, and the power factor was as high as 98%.
[0069] The voltage acquisition module described above can be applied not only to Boost (full-bridge) power factor correction circuits, but also to other types of power factor correction circuits (such as interleaved PFC, bridgeless PFC, and totem-pole PFC), demonstrating high versatility. Furthermore, it eliminates the need for additional switches to address interference issues, resulting in lower cost and easier handling.
[0070] Based on the above embodiments, this application also provides an air conditioner, including the power factor improvement circuit described above. The voltage acquisition of the power factor improvement circuit uses the voltage acquisition module described above, which can reduce the capacitor capacity and achieve the effect of reducing PCB cost and size.
[0071] The apparatus and system embodiments described above are merely illustrative. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement these embodiments without any creative effort.
[0072] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A voltage acquisition module, characterized in that, The circuit is applied to a power factor improvement circuit, which includes a controller and a controlled module. The controller acquires the output voltage of the controlled module through the voltage acquisition module. The voltage acquisition module includes a first unidirectional conduction module and a first capacitor module; The input terminal of the first unidirectional conduction module is connected to the voltage output terminal of the controlled module, the output terminal of the first unidirectional conduction module is connected to the first terminal of the first capacitor module, and the second terminal of the first capacitor module is grounded; the first terminal of the first capacitor module is connected to the voltage acquisition terminal of the controller.
2. The voltage acquisition module as described in claim 1, characterized in that, The voltage acquisition module further includes a voltage divider module, and the input terminal of the first unidirectional conduction module is connected to the voltage output terminal of the controlled module through the voltage divider module; The voltage divider module includes a first resistor module and a second resistor module; The voltage output terminal of the controlled module, the first resistor module, the second resistor module and ground are connected in sequence; The connection point between the first resistor module and the second resistor module is connected to the input terminal of the first unidirectional conduction module.
3. The voltage acquisition module as described in claim 1, characterized in that, The voltage acquisition module also includes a third resistor module, which is connected to both ends of the first capacitor module.
4. The voltage acquisition module as described in claim 1, characterized in that, The first unidirectional conduction module is a diode, the input terminal of the first unidirectional conduction module is the anode of the diode, and the output terminal of the first unidirectional conduction module is the cathode of the diode.
5. The voltage acquisition module as described in claim 1, characterized in that, The controlled module includes a rectifier module, an inductor module, a switch module, a second unidirectional conduction module, and a second capacitor module; The input terminal of the rectifier module is used to connect to an AC power source; The first output terminal of the rectifier module is connected to the first terminal of the inductor module, the second terminal of the inductor module is connected to the first terminal of the switch module and the first terminal of the second unidirectional conduction module, and the second terminal of the switch module is connected to the second output terminal of the rectifier module. The second terminal of the second unidirectional conduction module is connected to the first terminal of the second capacitor module, and the second terminal of the second capacitor module is connected to the second output terminal of the rectifier module; the first and second terminals of the second capacitor module are used to connect to the load; the first terminal of the second capacitor module is the voltage output terminal of the controlled module. The power factor improvement circuit also includes a switch drive module and a current detection module; The controller is connected to the control terminal of the switch module through the switch driver module; The controller is used to obtain the current flowing through the switching module or the inductor module through the current detection module.
6. The voltage acquisition module as described in claim 5, characterized in that, The second unidirectional conduction module includes a fast recovery diode.
7. The voltage acquisition module as described in claim 5, characterized in that, The capacitance value of the second capacitor module is less than or equal to 100μF.
8. The voltage acquisition module as described in claim 5, characterized in that, The current detection module is connected in series with the switch module.
9. The voltage acquisition module as described in claim 5, characterized in that, The current detection module is connected in series with the inductor module.
10. An air conditioner, characterized in that, The air conditioner includes the voltage acquisition module as described in any one of claims 1 to 9.