Power supply circuit and frequency converter

Abstract

The utility model provides a power supply circuit and a frequency converter. Relates to the field of compressor circuits, and aims to solve the problems of high circuit cost and large size caused by additionally arranging a relay when reducing the loss of a frequency converter at present, a thermistor short-circuit circuit with an MOS tube is adopted to short-circuit a thermistor, so that the efficiency of the frequency converter can be effectively improved, and meanwhile, the cost and the size caused by adopting a relay circuit can be reduced. And the applicability of the circuit is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a compressor circuit field, especially in a kind of power supply circuit and frequency converter. BACKGROUND

[0002] The existing commercial frequency converter includes LN input circuit, discharge circuit and rectification filter circuit three parts. Among them, LN input circuit, discharge circuit and rectification filter circuit are sequentially connected. LN input circuit mainly includes fuse F1, thermistor NTC1 and voltage-dependent resistor RV1 etc. component. Among them, when frequency converter starts, thermistor NTC1 is always in working condition, resulting in relatively large circuit loss.

[0003] A kind of power supply circuit and frequency converter with the power supply circuit are disclosed in Chinese patent (publication number CN217469754U), as shown in Figure 1 The thermistor short-circuiting circuit is connected to the ends of the thermistor, and the thermistor can be short-circuited after the frequency converter is started. The frequency converter uses the power supply circuit with the above circuit structure, which helps to reduce the loss of the frequency converter and increase the efficiency of the frequency converter. However, an additional relay is needed, which increases the cost and size of the relay circuit, restricting the use of the circuit. UTILITY MODEL CONTENT

[0004] The utility model aims at the defects of prior art, provides a kind of power supply circuit and frequency converter, uses the thermistor short-circuiting circuit with MOS tube to short-circuit thermistor, not only can effectively improve the efficiency of frequency converter, can reduce the cost and size brought by relay circuit simultaneously, increase its applicability in circuit.

[0005] The first purpose of the utility model is to provide a power supply circuit, which adopts the following technical solutions:

[0006] The input circuit, the discharge circuit and the rectification filter circuit are connected in series. The rectification filter circuit is provided with a thermistor, and the thermistor is connected in parallel with a thermistor short-circuiting circuit. The thermistor short-circuiting circuit includes a MOS tube, a first transistor, a second transistor and a first resistor. The base ends of the first transistor and the second transistor are control signal input ends. The collector end of the first transistor is connected to a positive voltage terminal. The emitter end of the first transistor is connected to one end of the first resistor and the emitter end of the second transistor. The collector end of the second transistor is grounded. The other end of the first resistor is connected to the gate end of the MOS tube. The source end of the MOS tube is connected to one end of the thermistor. The drain end of the MOS tube is connected to the other end of the thermistor.

[0007] Further, the thermistor short circuit is connected between two ends of the thermistor, and the thermistor is connected in the power supply circuit when the drain end and the source end of the MOS tube are in the off state, and the thermistor is short-circuited when the drain end and the source end of the MOS tube are in the on state.

[0008] Further, the MOS tube is an N-channel MOS tube.

[0009] Further, the rectifier filter circuit further comprises a bridge rectifier diode and a filter capacitor, two DC output ends of the bridge rectifier diode are connected to the filter capacitor respectively, and one DC output end of the bridge rectifier diode is connected to the filter capacitor in series with the thermistor.

[0010] Further, the input circuit further comprises a fuse, a voltage-dependent resistor and a power input port, one end of the fuse and one end of the voltage-dependent resistor are connected to the discharge circuit, the other end of the fuse and the other end of the voltage-dependent resistor are respectively connected to a connection terminal of the power input port, and the other end of the voltage-dependent resistor is connected to the discharge circuit.

[0011] Further, the control signal input end is connected to the controller.

[0012] Further, the first triode is an NPN triode, and the second triode is a PNP triode.

[0013] Further, the collector end of the NPN triode is connected to the positive voltage terminal, the emitter end of the NPN triode is connected to one end of the first resistor and the emitter end of the PNP triode, and the collector end of the PNP triode is grounded.

[0014] The second purpose of the utility model is to provide a frequency converter, which utilizes the power supply circuit as described in the first purpose.

[0015] Further, the utility model further comprises a master control chip, a communication circuit, a feedback circuit and a driving circuit, the communication circuit comprises a PWM signal input port and a mechanical frequency conversion Drop-in input port, wherein the PWM signal input port and the mechanical frequency conversion Drop-in input port are connected to the communication circuit in a selective manner.

[0016] Compared with the prior art, the utility model has the advantages and positive effects that:

[0017] In view of the problem that adding a relay when reducing the loss of the frequency converter leads to high cost and large size of the circuit, the thermistor short circuit with the MOS tube is used to short the thermistor, which can not only effectively improve the efficiency of the frequency converter, but also reduce the cost and size caused by the relay circuit, and increase the applicability of the frequency converter in the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0019] Figure 1 It is a schematic diagram of the power supply circuit in the prior art.

[0020] Figure 2 It is a schematic diagram of the power supply circuit in the embodiments 1 and 2 of the present application.

[0021] Figure 3 It is a schematic diagram of the frequency converter in the embodiment 2 of the present application.

[0022] In the figure, 1, input circuit; 2, discharge circuit; 3, rectifier filter circuit; 4, thermistor short circuit; 5, controller; 6, power supply circuit; 7, communication circuit; 8, feedback circuit; 9, driving circuit. DETAILED DESCRIPTION

[0023] Embodiment 1

[0024] In a typical embodiment of the present application, as shown in Figures 2-3 , a power supply circuit is proposed.

[0025] In the current compressor power supply circuit 6, a thermistor short circuit 4 is connected across the thermistor NTC1, which is used to short the thermistor NTC1 after the frequency converter is started, so as to reduce the loss of the frequency converter and improve the efficiency. However, this design needs to additionally increase a relay, which leads to high cost and large size of the circuit, and limits its application. Based on this, the present embodiment proposes a power supply circuit 6, which uses a thermistor short circuit 4 with a MOS tube U1 to short the thermistor NTC1. Not only the efficiency of the frequency converter is improved, but also the use of the relay is saved, and the cost and size problems caused by the use of the relay circuit are reduced, and the applicability of the circuit in practical application is increased.

[0026] As shown in Figure 2 , the power supply circuit 6 includes the input circuit 1, the discharge circuit 2 and the rectifier filter circuit 3 connected in series, the rectifier filter circuit 3 is provided with the thermistor NTC1, and the thermistor NTC1 is connected in parallel with the thermistor short circuit 4. The power supply circuit 6 is the power supply circuit 6 of the frequency converter, wherein the discharge circuit 2 and the input circuit 1 are not improved, and the related structures can refer to the existing structures. Different from the circuit structure in Figure 1 , in the present embodiment, the thermistor NTC1 is connected into the rectifier filter circuit 3.

[0027] The input circuit 1 is responsible for receiving external power input as the input part of the whole power supply circuit 6. The discharge circuit 2 is usually used to provide a discharge path for the energy storage elements (such as capacitors) in the circuit when the power is off, so as to prevent the voltage remaining between the plug pins from causing harm to the human body. The rectifier filter circuit 3 converts the input alternating current into direct current and smoothes the output of the direct current through a filter element (such as a capacitor). The thermistor NTC1 is connected in series in the rectifier filter circuit 3, which is used to limit the current at the initial stage of power start to prevent excessive current from impacting the circuit elements. As the temperature rises, the resistance of the thermistor NTC1 gradually decreases, allowing more current to pass through.

[0028] The thermistor shorting circuit 4 includes a MOS tube U1, a first transistor Q1, a second transistor Q2 and a first resistor R1. The MOS tube U1 is used as the main switching element to short the thermistor NTC1 under the action of the control signal. The first transistor Q1 and the second transistor Q2 constitute a control signal amplification circuit, which is used to amplify the weak control signal to a sufficient degree to drive the MOS tube U1. The first resistor R1 is used as a current limiting element to protect the gate of the MOS tube U1 from excessive current impact. The control signal input end receives an external control signal for controlling the switching state of the MOS tube U1.

[0029] The base ends of the first transistor Q1 and the second transistor Q2 are the control signal input end. When the control signal input end receives a high-level signal, the first transistor Q1 is turned on to apply a positive voltage to the gate of the MOS tube U1 through the first resistor R1, so that the MOS tube U1 is turned on to short the thermistor NTC1. At the same time, the second transistor Q2 is also in the on state, but its main function is to provide an additional current path to ensure that the MOS tube U1 can be reliably turned on. When the control signal input end receives a low-level signal, the first transistor Q1 and the second transistor Q2 are both cut off, the MOS tube U1 is turned off, and the thermistor NTC1 is reconnected to the circuit. The overall performance of the frequency converter is improved, the operating cost is reduced, the reliability and stability of the circuit are enhanced, and the flexibility and applicability of the circuit in practical application are increased.

[0030] The thermistor shorting circuit 4 is used to short the thermistor NTC1 under certain conditions. When the drain end and the source end of the MOS tube U1 are in the off state, the thermistor NTC1 is normally connected in the power supply circuit 6 to play a role in current limiting protection. When the drain end and the source end of the MOS tube U1 are connected, the thermistor NTC1 is shorted, thereby reducing its influence in the circuit, reducing the loss and improving the efficiency.

[0031] The MOS tube U1 uses an N-channel MOS tube U1 as the main switching element, and the N-channel MOS tube U1 is turned on when the gate voltage is higher than the source voltage. The rectifier filter circuit 3 is provided with a bridge rectifier diode D2 and a filter capacitor C5. The bridge rectifier diode D2 can convert the input alternating current into direct current. The bridge rectifier is composed of four diodes, forming a full-wave rectifier circuit, which ensures that there is current flowing through the load in each half cycle. The filter capacitor C5 can smooth the output of the direct current and reduce voltage fluctuations. The two direct current output terminals of the bridge rectifier diode D2 are respectively connected to the positive and negative electrodes of the filter capacitor C5, forming a filter circuit. The thermistor NTC1 is connected in series between one direct current output terminal of the bridge rectifier diode D2 and the filter capacitor C5, and is used to limit the starting current.

[0032] The input circuit 1 also includes a fuse, a voltage-dependent resistor, and a power input port. One end of the fuse and one end of the voltage-dependent resistor are connected to the discharge circuit 2. The other end of the fuse and the other end of the voltage-dependent resistor are respectively connected to one connection terminal of the power input port. The other end of the voltage-dependent resistor is connected to the discharge circuit 2. The fuse provides overcurrent protection. When the current in the circuit exceeds the rated value, the fuse melts and cuts off the circuit, preventing equipment damage or fire. The voltage-dependent resistor provides overvoltage protection. When the voltage in the circuit exceeds the rated voltage of the voltage-dependent resistor, its resistance rapidly decreases, directing the overvoltage to ground, protecting the circuit from damage.

[0033] The power input port connects to an external power source, providing power to the entire circuit.

[0034] As shown in Figure 2 and Figure 3 , the control signal input terminal is connected to the controller 5 for receiving control signals. The controller 5 can use a single-chip microcomputer or the like. It can send high or low level signals to the control signal input terminal of the thermistor short circuit 4 according to the preset logic or external input signals, thereby controlling the switching state of the MOS tube U1.

[0035] The first transistor Q1 is an NPN transistor Q1, with its collector terminal connected to a positive voltage terminal and its emitter terminal connected to one end of the first resistor R1 and the emitter terminal of the second transistor Q2 (PNP type). When the base receives a high level signal, the NPN transistor is turned on.

[0036] The second transistor Q2 is a PNP transistor Q2, with its collector terminal grounded and its emitter terminal connected to the emitter terminal of the NPN transistor. When the NPN transistor is turned on, the PNP transistor Q2 is also turned on, providing a sufficient voltage difference for the gate of the MOS tube U1 to turn on.

[0037] By using MOS tube U1 to replace the relay, the cost and size of the circuit are reduced, the efficiency of the frequency converter is improved, and the loss is reduced.

[0038] Embodiment 2

[0039] In another typical embodiment of the utility model, as shown in Figure 3 A frequency converter is provided.

[0040] A frequency converter includes a master control chip 5, a power supply circuit 6, a communication circuit 7, a feedback circuit 8, and a drive circuit 9. The connection relationship of the above components is known and will not be described again.

[0041] Among them, the functions of each functional circuit in the frequency converter are as follows:

[0042] The input of the communication circuit 7 is controlled by the master control chip 5, which controls the shutdown, opening and speed of the frequency converter.

[0043] The feedback circuit 8 samples the output current and bus voltage of the frequency converter and feeds back, which is used to provide current protection, voltage protection, etc.

[0044] The drive circuit 9 is used to provide three-phase output voltage of the compressor.

[0045] The power supply circuit 6 in this embodiment uses the power supply circuit in Embodiment 1 above.

[0046] When the power supply circuit 6 uses the power supply circuit in Embodiment 1 above, the NTC1 thermal resistor can be short-circuited after the frequency converter is started, effectively reducing the loss of the frequency converter and increasing the efficiency of the frequency converter.

[0047] On the basis of the above structure, the communication circuit 7 structure of the present embodiment is also improved to solve the problem that the current communication circuit mostly uses PWM communication mode, which is single in communication mode and cannot be compatible with Drop in mechanical frequency conversion communication mode.

[0048] Among them, the communication circuit 7 includes a PWM signal input port and a mechanical frequency conversion Drop-in input port, and the PWM signal input port and the mechanical frequency conversion Drop-in input port are connected to the communication circuit in a selective manner.

[0049] The PWM signal input port and the mechanical frequency conversion Drop-in input port are input ports J3 of the communication circuit 7. The output end of the communication circuit 7 is labeled PWMIN and is connected to the capture port of the master control chip 5 to detect the PWM frequency.

[0050] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A power supply circuit comprising an input circuit, a discharge circuit and a rectification filter circuit connected in series, characterized by, The rectification filter circuit is provided with a thermistor, and the thermistor is connected in parallel with a thermistor short-circuiting circuit.

2. The power supply circuit of claim 1, wherein, The thermistor short-circuiting circuit is connected between two ends of the thermistor, and the thermistor is connected in the power supply circuit when the drain electrode and the source electrode of the MOS tube are in an open state, and the thermistor circuit is short-circuited when the drain electrode and the source electrode of the MOS tube are in a closed state.

3. The power supply circuit of claim 1 or 2, wherein The MOS tube is an N-channel MOS tube.

4. The power supply circuit of claim 1, wherein, The rectification filter circuit further comprises bridge rectifier diodes and a filter capacitor, two direct current output terminals of the bridge rectifier diodes are respectively connected to the filter capacitor, and one direct current output terminal of the bridge rectifier diodes is connected to the filter capacitor in series with the thermistor.

5. The power supply circuit of claim 1 or 4, wherein The input circuit further comprises a fuse, a voltage-dependent resistor and a power input port; one end of the fuse and one end of the voltage-dependent resistor are connected to the discharge circuit, the other end of the fuse and the other end of the voltage-dependent resistor are respectively connected to one connection terminal of the power input port; and the other end of the voltage-dependent resistor is connected to the discharge circuit.

6. The power supply circuit of claim 1, wherein, The control signal input terminal is connected to a controller.

7. The power supply circuit of claim 1, wherein, The first triode is an NPN triode, and the second triode is a PNP triode.

8. The power supply circuit of claim 7, wherein, The collector electrode of the NPN triode is connected to a positive voltage terminal, the emitter electrode of the NPN triode is connected to one end of the first resistor and the emitter electrode of the PNP triode, and the collector electrode of the PNP triode is grounded.

9. A frequency converter, characterized in that The power supply circuit according to any one of claims 1-8 is used.

10. The frequency converter of claim 9, wherein, The power supply circuit further comprises a master control chip, a communication circuit, a feedback circuit and a driving circuit, the communication circuit comprises a PWM signal input port and a mechanical frequency conversion Drop-in input port; wherein the PWM signal input port and the mechanical frequency conversion Drop-in input port are connected to the communication circuit in an alternative manner.

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