Pre-charging circuit, compressor and air conditioner
By constructing a pre-charge circuit using a resistor divider network and a MOSFET, combined with a high-precision voltage regulator circuit, the charging accuracy and reliability issues caused by voltage drop in the compressor's pre-charge circuit were resolved, achieving high-precision pre-charge voltage and improved system reliability.
Patent Information
- Application Number
- CN202520045482.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2035-01-09
AI Technical Summary
In the existing compressor pre-charge circuit, the voltage drop caused by the PTC resistor results in the pre-charge voltage not reaching the required accuracy, affecting the charging accuracy of the capacitor and the reliability of the product.
A pre-charge circuit is built using a resistor divider network and MOSFETs, combined with a high-precision voltage regulator circuit, and current limiting control technology is used to improve the accuracy and reliability of the pre-charge voltage.
It achieves a pre-charge voltage accuracy of 1%, effectively protecting the capacitor and pre-charge contactor, improving system reliability, and reducing product costs.
Smart Images
Figure CN223608760U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of power electronics, and relates to a pre-charge circuit, a compressor and an air conditioner. BACKGROUND
[0002] The compressor pre-charge circuit is a circuit design for protecting a compressor and related circuits, and is mainly used in devices such as air conditioner compressors of new energy vehicles.
[0003] When the compressor starts, a pre-charge relay in the pre-charge circuit is closed, and a capacitor module is charged through a pre-charge resistor. The pre-charge resistor limits the current to prevent overcurrent from damaging the circuit and the capacitor. However, the pre-charge resistor causes a voltage drop, which easily leads to a pre-charge voltage of the compressor that does not meet the required pre-charge accuracy. UTILITY MODEL CONTENTS
[0004] The utility model aims to solve one of the above technical problems, and provides a pre-charge circuit, a compressor and an air conditioner, to improve the charging accuracy and reliability of the pre-charge circuit.
[0005] The utility model provides a pre-charge circuit in a first aspect, including:
[0006] The resistor voltage dividing network includes a first resistor (R73), a second resistor (R74) and a third resistor (R75) connected in series, wherein a first end of the first resistor (R73) is connected to a power input end, and a second end of the first resistor (R73) is connected to the second resistor (R74);
[0007] The MOS tube (K13) has a first end of the first resistor (R73) connected to a drain of the MOS tube (K13), a second end of the first resistor (R73) connected to a gate of the MOS tube (K13), and a source of the MOS tube (K13) as an output end of the pre-charge circuit, and the output end of the pre-charge circuit can be connected to a load;
[0008] The high-precision voltage stabilizing circuit (N05) is connected in parallel between the first end of the first resistor (R73) and a connection end of the second resistor (R74) and the third resistor (R75).
[0009] In combination with the first aspect, in some implementation manners of the first aspect, the pre-charge circuit further includes a filter capacitor (C21) connected in parallel across the first resistor (R73).
[0010] In combination with the first aspect, in some implementation manners of the first aspect, the pre-charge circuit further includes a diode (VX4_5), wherein a positive electrode of the diode (VX4_5) is connected to the source of the MOS tube (K13), and a negative electrode of the diode (VX4_5) is grounded.
[0011] With reference to the first aspect, in some implementations of the first aspect, the pre-charge circuit further comprises a fourth resistor (R62) connected in series between the negative electrode of the diode (VX4_5) and the ground.
[0012] With reference to the first aspect, in some implementations of the first aspect, the first resistor (R73), the second resistor (R74) and the third resistor (R75) are configured to have sizes such that the second end of the first resistor (R73) generates a driving voltage of the MOS transistor (K13).
[0013] With reference to the first aspect, in some implementations of the first aspect, the charging voltage of the load is 30V, and the first resistor (R73), the second resistor (R74) and the third resistor (R75) are configured to have sizes such that the voltage difference between the second end of the second resistor (R74) and the power input end is 2.5V.
[0014] With reference to the first aspect, in some implementations of the first aspect, the voltage control circuit adopts a voltage control chip, and comprises a high-precision voltage stabilization circuit (N05).
[0015] With reference to the first aspect, in some implementations of the first aspect, the pre-charge circuit further comprises a pre-charge relay switch, one end of which is connected to the power input end, and the other end of which is connected to the load.
[0016] The second aspect of the present application provides a compressor, comprising a capacitor (C1), a control circuit and a compressor coil, wherein:
[0017] The positive electrode of the capacitor (C1) is connected to the output end of the pre-charge circuit and to the control circuit.
[0018] The control circuit is connected to the compressor coil and further connected to the power input end through the pre-charge relay KA.
[0019] The pre-charge circuit is the pre-charge circuit provided in the first aspect of the present application.
[0020] The third aspect of the present application provides an air conditioner comprising the compressor provided in the second aspect of the present application.
[0021] Compared with the prior art, the technical effects of the present application at least include:
[0022] 1. The pre-charge circuit of the present application discards the PTC resistor pre-charge scheme of the pre-charge circuit in the prior art and adopts a field effect transistor (MOS transistor) to build a pre-charge circuit. By utilizing the characteristics of low on-voltage drop and controllable drain-source current of the field effect transistor and adopting current limiting control technology, the pre-charge voltage precision is greatly improved, and the reliability of the pre-charge capacitor is improved through current limiting.
[0023] 2. The pre-charging circuit provided by the utility model can reach 1%, which is much higher than the pre-charging scheme using PTC pre-charging resistance, can effectively protect the pre-charging capacitor and pre-charging contactor, improve system reliability, and reduce product cost. BRIEF DESCRIPTION OF DRAWINGS
[0024] In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor under the premise of the drawings.
[0025] Figure 1 It is the compressor pre-charging circuit structure schematic diagram of the utility model.
[0026] Figure 2a It is the voltage stabilizing control chip device performance diagram of the utility model.
[0027] Figure 2b It is the voltage stabilizing control chip device performance diagram of the utility model.
[0028] Figure 3 It is the MOS tube transfer characteristic curve diagram of the utility model.
[0029] Figure 4 It is the compressor pre-charging circuit structure schematic diagram of prior art. DETAILED DESCRIPTION
[0030] In order to make the technical problems, technical solutions and beneficial effects of the utility model clearer, the following will be further described in detail by combining with the drawings and embodiments.The specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model.
[0031] The prefix words such as "first", "second" in the embodiments of the application are only used to distinguish different description objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects.The use of ordinal words such as ordinal words in the embodiments of the application does not limit the described objects, and the description of the described objects should refer to the description of the context in the claims or embodiments, and should not be limited by the use of such prefix words.In addition, in the description of the embodiments, unless otherwise stated, the meaning of "a plurality of" is two or more.
[0032] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B; "and / or" herein only represents a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone.
[0033] It is known in the prior art that the compressor pre-charge circuit structure is as shown in Figure 4
[0034] After the system is powered on, the power supply charges the compressor capacitor C1 through the PTC pre-charge resistor. When the charging starts, the current flowing through the PTC resistor is large, the device generates heat, which causes the PTC resistance to increase, inhibits the current growth, and protects the capacitor C1. In theory, if there is no control circuit in the later stage, the capacitor C1 will be fully charged, at which time the voltage across C1 is equal to the input voltage. In reality, the control circuit power supply of some compressors will take power from here, which will cause the compressor to always have a small load caused by the control circuit after the charging is completed, that is, there is always a small load current on the PTC resistor after the pre-charge is completed, so there is a voltage drop across the PTC pre-charge resistor, which causes the capacitor C1 to be unable to be pre-charged to the input voltage. Through measurement, if the bus voltage Vin is 30V, C1 can only be pre-charged to 27.5V at most. In general, the pre-charge voltage is required to reach 95% of the input voltage before closing, obviously the pre-charge voltage in this case does not meet the pre-charge condition. Since the capacitor C1 has a large capacitance, closing the pre-charge relay in this case will have a negative impact on the reliability and service life of the capacitor C1.
[0035] That is, the technical solution of the pre-charge circuit using the PTC pre-charge resistor in the prior art affects the charging accuracy of the capacitor C1, the cost of the charging circuit, and the service life of the product.
[0036] To solve the above problems, the present application provides a pre-charge circuit in the first aspect, which comprises a resistance voltage dividing network, a MOS tube K13 and a voltage stabilizing control circuit.
[0037] The resistance voltage dividing network comprises a first resistor R73, a second resistor R74 and a third resistor R75 connected in series, wherein the first end of the first resistor R73 is connected to the power supply input end Vin for connecting the power supply to the entire pre-charge circuit. The second end of the first resistor R73 is connected to the first end of the second resistor R74, the second end of the second resistor R74 is connected to the first end of the third resistor R75, and the second end of the third resistor R75 is further connected to the ground.
[0038] The first resistor R73, the second resistor R74 and the third resistor R75 are connected in series to form a voltage division network, and the voltage drops of the connection points relative to the input terminal Vin of the power supply can be controlled according to the selection and configuration of the sizes of the three resistors.
[0039] The first end of the first resistor R73 is connected to the drain of the MOS transistor K13, the second end of the first resistor R73 is connected to the gate of the MOS transistor K13, and the source of the MOS transistor K13 is the output terminal of the precharge circuit.
[0040] The MOSFET device used in the case is RFR5305TRPBF, and its transfer characteristic curve is as shown in the figure. Figure 3
[0041] The high-precision voltage stabilizing circuit N05 is connected in parallel between the first end of the first resistor R73 and the connection end of the second resistor R74 and the third resistor R75.
[0042] The high-precision voltage stabilizing circuit can use ME431 or other devices with the same electrical parameters. ME431 has good thermal stability and high control precision. Figure 2a Figure 2b
[0043] In some implementations of the first aspect, the precharge circuit further comprises a filter capacitor C21 connected in parallel across the first resistor R73. The filter capacitor C21 functions to suppress the inrush current at the power-on moment of the system, avoiding the problem of instantaneous increase of current at the power-on moment, which causes damage to electronic devices.
[0044] In some implementations of the first aspect, the precharge circuit further comprises a diode VX4_5, the anode of the diode VX4_5 is connected to the source of the MOS transistor K13, and the cathode of the diode VX4_5 is grounded.
[0045] Furthermore, the precharge circuit further comprises a fourth resistor R62 connected in series between the cathode of the diode VX4_5 and the ground.
[0046] The diode VX4_5, or the combination of the diode VX4_5 and R62, can be used as a working indication circuit of the precharge circuit.
[0047] The pre-charge voltage of the air conditioner compressor is usually 30V, and thus, in the embodiment of the application, the power input terminal Vin inputs a 30V voltage.
[0048] In the above circuit implementation structure, the resistance voltage dividing network is adopted to ensure that the voltage of VAC is above 2.5V under the condition of the lowest power supply voltage of the system. The high-precision voltage stabilizing circuit ME431 is adopted to stabilize the voltage between the second end of the first resistor R73 and the power input terminal Vin to 2.5V. AC
[0049] In a specific embodiment, the device types used in the circuit of the application are as follows.
[0050] Model Bit number Number RFR5305TRPBF K13 1 ME431 N05 1 18K-0805-F R75 1 1.1K-0805-F R74 1 2.7K-0805-F R73 1 0805-100nF C21 1
[0051] The second aspect of the application provides a compressor, which comprises a capacitor C1, a control circuit and a compressor coil, wherein:
[0052] The positive pole of the capacitor C1 is connected to the output terminal of the pre-charge circuit and to the control circuit.
[0053] The control circuit is connected to the compressor coil and further connected to the power input terminal through the pre-charge relay KA.
[0054] The pre-charge circuit is the pre-charge circuit provided in the first aspect of the application.
[0055] The third aspect of the application provides an air conditioner, which comprises the compressor provided in the second aspect of the application. In addition to the air conditioner system, the compressor can also be applied to other suitable electrical products.
[0056] Taking the input voltage of 30V as an example, the working principle of the pre-charge circuit of the application applied to the compressor system is as follows.
[0057] Through the selection of the three voltage dividing resistors, the input voltage Vin generates a voltage difference of more than 2.5V at point A through the resistance voltage dividing network R73-R75, and then the high-precision voltage stabilizing circuit N05 is used to control the voltage difference to 2.5V. When the external input voltage fluctuates within the design range, the voltage difference between point A and Vin is always 2.5V.
[0058] A stable voltage difference of -1.776V relative to Vin is generated at point B through a voltage division network of resistors R73 and R74, which controls the gate of the MOSFET. According to the characteristic curve of the MOSFET, the MOSFET device works in the variable resistance region at Vgs of -1.776V, and the maximum current is limited within 210mA. The compressor pre-charge capacitor is connected at Vout, and the charging current of the compressor capacitor can be controlled at about 200mA through the circuit, which greatly reduces the impact on the capacitor and improves the reliability of the capacitor. At the same time, since the on-resistance of the MOSFET in the on state is extremely low, the voltage of the compressor capacitor can be charged to 99% of the input voltage. Through actual measurement, when the input voltage is 30V, the pre-charge voltage can reach 29.73V. At this time, when the pre-charge relay KA of the compressor is closed again, there will be no negative impact on the capacitor C1 in the rear stage.
[0059] The pre-charge circuit provided by the utility model can improve the reliability of the power system. Since the current limiting technology is adopted, the scheme has the short circuit protection function. Through testing, even if the output end is directly short-circuited to the negative pole of the power supply, the MOSFET will not be damaged.
[0060] The pre-charge circuit provided by the utility model measures that the pre-charge voltage reaches 29.73V when the input voltage is 30V, and the pre-charge precision is higher than 1%.
[0061] The pre-charge circuit provided by the utility model does not need an external PTC resistor, and the space occupied by the electric control is reduced. Compared with the external PTC resistor pre-charge scheme in the prior art, the price is low, the cost of the external PTC resistor is between 40-60 yuan, and the cost of the pre-charge circuit of the utility model is within 3.5 yuan.
[0062] The above only describes the preferred embodiments of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement within the spirit and principle of the utility model should be included in the protection scope of the utility model.
Claims
1. A pre-charging circuit, characterized in that, include: Resistor voltage divider network: includes a first resistor (R73), a second resistor (R74), and a third resistor (R75) connected in series, wherein the first end of the first resistor (R73) is connected to the power input terminal, and the second end of the first resistor (R73) is connected to the second resistor (R74). MOSFET (K13): The first end of the first resistor (R73) is connected to the drain of the MOSFET (K13), the second end of the first resistor (R73) is connected to the gate of the MOSFET (K13), and the source of the MOSFET (K13) is the output of the pre-charge circuit, the output of which can be connected to a load. High-precision voltage regulator circuit (N05): Connected in parallel to the first terminal of the first resistor (R73) and the connection terminals of the second resistor (R74) and the third resistor (R75).
2. The pre-charging circuit as described in claim 1, characterized in that, It also includes a filter capacitor (C21), which is connected in parallel across the first resistor (R73).
3. The pre-charging circuit as described in claim 1, characterized in that, It also includes a diode (VX4_5), the positive terminal of which is connected to the source of the MOSFET (K13), and the negative terminal of which is grounded.
4. The pre-charging circuit as described in claim 3, characterized in that, It also includes a fourth resistor (R62), which is connected in series between the negative terminal of the diode (VX4_5) and the ground point.
5. The pre-charging circuit as described in claim 1, characterized in that, The values of the first resistor (R73), the second resistor (R74), and the third resistor (R75) are configured such that the second terminal of the first resistor (R73) generates the driving voltage of the MOS transistor (K13).
6. The pre-charging circuit as described in claim 1, characterized in that, The charging voltage of the load is 30V, and the values of the first resistor (R73), the second resistor (R74), and the third resistor (R75) are configured such that the voltage difference between the second terminal of the second resistor (R74) and the power input terminal is 2.5V.
7. The pre-charging circuit as described in claim 1, characterized in that, The voltage regulation control circuit uses a voltage regulation control chip, including a high-precision voltage regulation circuit (N05).
8. The pre-charging circuit as described in any one of claims 1 to 7, characterized in that, It also includes a pre-charge relay switch, one end of which is connected to the power input terminal and the other end is connected to the load.
9. A compressor, characterized in that, Includes capacitor (C1), control circuit, and compressor coil, wherein: The positive terminal of capacitor (C1) is connected to the output terminal of the pre-charge circuit and then to the control circuit. The control circuit is connected to the press coil and further connected to the power input terminal via the pre-charge relay KA; The pre-charging circuit is the pre-charging circuit described in any one of claims 1 to 8.
10. An air conditioner, characterized in that, Includes the compressor described in claim 9.