Drive Circuit, Inverter and Electrical Equipment

Abstract

The present invention discloses a drive circuit, an inverter and an electrical equipment. The drive circuit includes: a rectifying and filtering circuit connecting the power grid and the load, and a protection circuit connected to the output end of the rectifying and filtering circuit. The protection circuit stabilizes the output voltage of the rectifying and filtering circuit, detects faults of the rectifying and filtering circuit and outputs fault signals. The drive circuit proposed by the present invention can handle the instantaneous high voltage generated by the surge signals and harmonic components in the power grid and the energy fed back by the load, and stabilize the output voltage of the circuit; at the same time, it can detect overcurrent faults when the circuit has an overcurrent situation, and thus can protect the circuit and the load connected to the circuit from damage.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and particularly to a driving circuit, an inverter, and an electrical device. Background Art

[0002] The rectifier filter circuit connecting the load and the power grid usually causes damage to the components in the rectifier filter circuit and the load due to the voltage spikes generated by the leakage inductance of the inductor and the capacitance oscillation. To prevent this situation, an RCD absorption circuit is usually added between the rectifier filter circuit and the load to absorb large voltage spikes to protect the components in the rectifier filter circuit and the load. At the same time, the large electrolytic capacitor in the rectifier filter circuit is also replaced with a film capacitor with non-polarity, high insulation impedance, broad frequency response, small dielectric loss, and small occupied space to reduce costs and optimize the circuit.

[0003] However, during actual use, the surge signals, harmonic components surging into the power grid and the energy fed back by the load may cause the instantaneous high voltage spikes in the circuit to exceed the absorption range of the RCD absorption circuit, resulting in damage to some components. In addition, during actual operation, the circuit will not only experience voltage fluctuations but also overcurrent situations. When the circuit experiences an overcurrent situation, the circuit also lacks countermeasures for overcurrent situations, leading to major faults and dangers in use. Summary of the Invention

[0004] In order to solve the technical problem that the voltage and current fluctuations generated by the rectifier filter circuit connecting the power grid and the load in the above-mentioned prior art will damage the components in the circuit and the load, the present invention provides a driving circuit, an inverter, and an electrical device.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a driving circuit, an inverter, and an electrical device. The driving circuit includes: a rectifier filter circuit connecting the power grid and the load, and a protection circuit connected to the output end of the rectifier filter circuit. The protection circuit stabilizes the output voltage of the rectifier filter circuit, detects the faults of the rectifier filter circuit, and outputs fault signals.

[0007] Further, the protection circuit includes: a voltage stabilizing circuit, and the instantaneous high voltage at the output end of the rectifier filter circuit returns to the power grid through the voltage stabilizing circuit.

[0008] Further, the protection circuit further includes: an overcurrent detection circuit. When the current in the rectifier filter circuit exceeds the threshold current, the overcurrent detection circuit conducts and outputs an overcurrent fault signal.

[0009] In one embodiment, the voltage stabilizing circuit includes a varistor Z1 and a fuse FU, one end of the varistor Z1 is connected to the output end P of the rectifier and filter circuit, the other end of the varistor Z1 is connected to the fuse FU, the other end of the fuse FU is connected to the output end N of the rectifier and filter circuit, and the voltage of the output end P is higher than the voltage of the output end N.

[0010] In one embodiment, the overcurrent detection circuit includes a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C5, and an optocoupler isolator U1; one end of the resistor R4 is connected to the output end P of the rectifier and filter circuit, the other end of the resistor R4 is connected to the resistor R5, the other end of the resistor R5 is grounded, the positive electrode of the light-emitting diode of the optocoupler isolator U1 is connected between the resistor R4 and the resistor R5, and the positive electrode of the light-emitting diode of the optocoupler isolator U1 is also connected between the varistor Z1 and the fuse FU, the emitter of the light-emitting diode of the optocoupler isolator U1 is connected to a power supply, a capacitor C5 is connected between the emitter and emitter of the light-emitting diode of the optocoupler isolator U1, one end of the resistor R7 is connected to the emitter of the optocoupler isolator U1, the other end of the resistor R7 is grounded, and the voltage of the output end P of the filter and rectifier circuit is higher than the voltage of the output end N of the filter and rectifier circuit.

[0011] In one embodiment, the overcurrent detection circuit further includes: a controller connected to the emitter of the optocoupler isolator U1 , and the controller sends the overcurrent fault signal when the emitter of the optocoupler isolator U1 outputs a low level.

[0012] Furthermore, the output end of the rectifier and filter circuit is connected to an RCD absorption circuit, and the RCD absorption circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C2, a capacitor C3, and a diode D7. The positive electrode of the diode D7 is connected to the output end P of the rectifier and filter circuit, and the other end of the diode D7 is connected to the resistor R1. The capacitor C2 and the resistor R2 are connected in parallel and then connected to the other end of the resistor R1. The capacitor C3 and the resistor R3 are connected in parallel, and one end of the resistor R3 is connected to the resistor R2. The other end of the resistor R3 is connected to the output end N of the rectifier and filter circuit, and the voltage of the output end P is higher than the voltage of the output end N.

[0013] In one embodiment, the rectification and filtering circuit includes a three-phase full-bridge rectification circuit connected to a power grid, and an LC filtering circuit connected to the three-phase full-bridge rectification circuit, and the capacitor in the LC filtering circuit is a thin film capacitor.

[0014] The inverter is connected to the power grid using the driving circuit described above.

[0015] The electrical equipment uses the inverter.

[0016] Compared with the existing technology, the driving circuit proposed in the present invention can handle the instantaneous high voltage generated by the surge signal and harmonic components of the power grid and the energy fed back by the load, and stabilize the output voltage of the circuit; at the same time, it can detect overcurrent faults when overcurrent occurs in the circuit, thereby protecting the circuit and the load connected to the circuit from damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0018] Figure 1 4 is a connection diagram of a driving circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Currently, to prevent voltage spikes caused by inductor leakage and capacitor oscillation, which can damage components in the rectifier and filter circuits and loads, an RCD (Resistor Device) is typically added between the rectifier and filter circuits to absorb large voltage spikes and protect the rectifier and filter circuits and inverter circuits. At the same time, large electrolytic capacitors in the rectifier and filter circuits are often replaced with film capacitors that are non-polar, have high insulation impedance, wide frequency response, low dielectric loss, and occupy a small space, to reduce costs and optimize the circuit.

[0021] However, in actual use, grid surges, harmonics, and load feedback can cause transient high-voltage spikes in the circuit to exceed the tolerance of the RCD absorption circuit, potentially damaging some components. Furthermore, in actual use, the circuit can experience not only voltage fluctuations but also overcurrent, leading to significant malfunctions and potential dangers.

[0022] To solve the technical problem that voltage and current fluctuations generated by the circuit connecting the power grid and the load in the prior art can damage the circuit and components in the load, the present invention proposes a drive circuit, including: a rectifier filter circuit connecting the power grid and the load, and a protection circuit connected to the output end of the rectifier filter circuit. The protection circuit stabilizes the output voltage of the rectifier filter circuit, detects faults in the rectifier filter circuit and outputs fault signals. When there are surge signals and harmonic components in the power grid and instantaneous high voltages generated by the energy fed back from the load, the instantaneous high voltages return to the power grid through the protection circuit, thereby stabilizing the output voltage of the circuit; when the circuit has an overcurrent situation, the protection circuit can detect the overcurrent fault of the circuit and output an overcurrent fault signal.

[0023] As can be seen from the above description, the drive circuit proposed by the present invention adds a protection circuit for stabilizing the circuit voltage on the basis of the existing rectifier filter circuit. When there are instantaneous high voltages or excessive currents in the drive circuit, the protection circuit can stabilize the voltage of the circuit at a normal level, avoiding damage to the components in the circuit and the load connected to the circuit. At the same time, when the circuit has an overcurrent situation, the protection circuit can detect and output a fault signal in a timely manner, facilitating maintenance.

[0024] The principle and structure of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0025] As the Figure 1 shown, the protection circuit includes: a voltage stabilization circuit and an overcurrent detection circuit; at the output end of the rectifier filter circuit; the voltage stabilization circuit processes the instantaneous high voltages generated by the surge signals and harmonic components in the power grid and the energy fed back from the load, because the instantaneous high voltages in the circuit return to the power grid through the voltage stabilization circuit, thereby stabilizing the voltage of the circuit; the overcurrent detection circuit processes the overcurrent situation of the circuit. When the current in the rectifier filter circuit exceeds the threshold current, the overcurrent detection circuit conducts and outputs an overcurrent fault signal, detecting the overcurrent fault of the circuit.

[0026] In this embodiment, as Figure 1As shown, the rectifier and filter circuit includes a three-phase full-bridge rectifier circuit connected to the power grid and an LC filter circuit connected to the three-phase full-bridge rectifier circuit, and the capacitor in the LC filter circuit is a thin-film capacitor. The three-phase full-bridge rectifier circuit is composed of diodes D1 and D6, with diodes D1 and D2 connected in series, diodes D3 and D4 connected in series, and diodes D5 and D6 connected in series. The positive electrodes of diodes D2, D4, and D6 are connected in parallel, and the negative electrodes of diodes D1, D3, and D5 are connected in parallel. One end of the inductor L1 in the LC filter circuit is connected to the negative electrode of diode D5, and the other end of inductor L1 is connected to thin-film capacitor C1. The connection between capacitor C1 and inductor L1 serves as output terminal P, and the other end of capacitor C2 serves as output terminal N. From the entire connection structure, it can be seen that the voltage at output terminal P is higher than the voltage at output terminal N. This output terminal configuration allows the filter inductor L1 to effectively filter out high-order current harmonics caused by the switching frequency.

[0027] Furthermore, an RCD absorption circuit for absorbing peak voltage is provided at the output end of the rectifier and filter circuit. The RCD absorption circuit includes: resistor R1, resistor R2, resistor R3, capacitor C2, capacitor C3, and diode D7. The positive electrode of diode D7 is connected to the output terminal P, and the other end of diode D7 is connected to resistor R1. Capacitor C2 and resistor R2 are connected in parallel and then connected to the other end of resistor R1. Capacitor C3 and resistor R3 are connected in parallel, and one end of resistor R3 is connected to resistor R2, and the other end of resistor R3 is connected to the output terminal N. When

[0028] Furthermore, in this embodiment, the voltage stabilizing circuit includes: a varistor Z1 and a fuse FU, one end of the varistor Z1 is connected to the output end P of the rectifier and filter circuit, the other end of the varistor Z1 is connected to the fuse FU, the other end of the fuse FU is connected to the output end N of the rectifier and filter circuit, and the voltage of the output end P is higher than the voltage of the output end N.

[0029] Furthermore, in this embodiment, the overcurrent detection circuit includes: a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C4, a capacitor C5, and an optocoupler isolator U1; one end of resistor R4 is connected to the output terminal P, the other end of resistor R4 is connected to resistor R5, the other end of resistor R5 is grounded, and capacitor C4 is connected between resistor R5 and ground; the anode of the light-emitting diode of the optocoupler isolator U1 is connected between resistors R4 and R5, and the anode of the light-emitting diode of the optocoupler isolator U1 is also connected between varistor Z1 and fuse FU; the emitter of the light-emitting diode of the optocoupler isolator U1 is connected to a power supply; capacitor C5 is connected between the emitter and emitter of the light-emitting diode of the optocoupler isolator U1; one end of resistor R7 is connected to the emitter of the optocoupler isolator U1; and the other end of resistor R7 is grounded. Furthermore, the emitter of the optocoupler isolator U1 is also connected to a controller that can convert the emitter output level signal of the optocoupler isolator U1 into an overcurrent fault signal.

[0030] Based on the above circuit settings and connection conditions, the operating principle of the circuit is as follows:

[0031] During normal operation, the varistor Z1 is equivalent to an open circuit. The grid current only flows through the inductor L1, the output terminal P, the resistor R4, the fuse FU, and then flows into the output terminal N to form a loop. The load connected to the output terminal P and the output terminal N receives current normally. And at this time, no current flows through the resistor R6, so the diode of the optocoupler isolator U1 does not emit light, and the triode of the optocoupler isolator U1 is not conducting. At this time, the level connected to the collector of the controller is a high level of 3.3V. The controller receives the high-level signal and converts it into a normal operation signal, and the circuit operates without faults.

[0032] When there is an instantaneous high voltage in the circuit, on the one hand, the RCD absorption circuit will absorb part of the high voltage and stabilize the voltage at the output terminal. On the other hand, the varistor Z1 conducts, and the high voltage passes through the varistor Z1, the fuse FU, and the output terminal N back to the grid, making the output terminal voltage stable and protecting the load from being damaged by the instantaneous high voltage. At the same time, combined with the voltage detection configured in the conventional drive board, voltage fault output warnings can also be realized.

[0033] When the current in the circuit is too large (exceeding the threshold current of the circuit), the fuse FU is burned out. At this time, the fuse FU is equivalent to an open circuit. At this time, the current can flow from the output terminal P through the resistor R4 and the resistor R5 to the ground terminal. At the same time, the current will also flow from the resistor R4 and the varistor Z1 into the diode of the optocoupler isolator U1 and then through the resistor R6 to the ground terminal, and the triode of the optocoupler isolator U1 will also conduct. The 3.3V power supply flows to the ground terminal through the triode of the optocoupler isolator and the resistor R7. The controller detects that the level of the collector of the optocoupler isolator U1 is a low level. At this time, the controller converts the low-level signal into an overcurrent fault warning output to remind the user.

[0034] In this embodiment, since the resistors R4 and R5 in the overcurrent detection circuit are set as common fixed resistors with relatively small resistance values, mainly for sampling and detecting whether the optocoupler isolator U1 has an overcurrent situation, the current flowing out from the output terminal and flowing into the ground terminal is small, and its stabilizing effect on the output current is negligible. However, in other embodiments, the type, connection method, and resistance value setting of the resistors R4 and R5 can be changed to make the current flowing into the ground terminal by the overcurrent detection circuit larger, so as to play a role in stabilizing the output current of the circuit.

[0035] In summary, the drive circuit proposed by the present invention can handle the instantaneous high voltage generated due to the surge signals and harmonic components in the grid and the energy fed back by the load, and stabilize the output voltage of the circuit; at the same time, it can detect overcurrent faults when there is an overcurrent situation in the circuit, and thus can protect the circuit and the load connected to the circuit from being damaged.

[0036] The present invention also provides an inverter connected by using the driving circuit proposed above, and an electrical device using the inverter. The electrical device can be a compressor, an air conditioner, a wireless charging power supply, and so on.

[0037] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A driving circuit, comprising: A rectifier filter circuit connecting the power grid and the load, characterized in that it further comprises: a protection circuit connected to the output end of the rectifier filter circuit, the protection circuit stabilizing the output voltage of the rectifier filter circuit, detecting a fault of the rectifier filter circuit and outputting a fault signal; the protection circuit includes: a voltage stabilizing circuit; the protection circuit further includes: an overcurrent detection circuit, when the current in the rectifier filter circuit exceeds the threshold current, the overcurrent detection circuit conducts and outputs an overcurrent fault signal; the voltage stabilizing circuit includes a varistor Z1 and a fuse FU; the overcurrent detection circuit includes a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C5, and an optocoupler isolator U1; one end of the resistor R4 is connected to the output end P of the rectifier filter circuit, the other end of the resistor R4 is connected to the resistor R5, the other end of the resistor R5 is grounded, the positive electrode of the light-emitting diode of the optocoupler isolator U1 is connected between the resistor R4 and the resistor R5, and the positive electrode of the light-emitting diode of the optocoupler isolator U1 is also connected between the varistor Z1 and the fuse FU, the collector of the triode of the optocoupler isolator U1 is connected to the power supply, a capacitor C5 is connected between the collector and the emitter of the triode of the optocoupler isolator U1, one end of the resistor R7 is connected to the emitter of the triode of the optocoupler isolator U1, the other end of the resistor R7 is grounded, and the voltage of the output end P of the rectifier filter circuit is higher than the voltage of the output end N of the rectifier filter circuit; the negative electrode of the diode of the optocoupler isolator U1 is connected to the ground terminal through the resistor R6.

2. The drive circuit according to claim 1, characterized in that The instantaneous high voltage at the output end of the rectifier filter circuit returns to the power grid through the voltage stabilizing circuit.

3. The drive circuit according to claim 1, characterized in that, One end of the varistor Z1 is connected to the output end P of the rectifier filter circuit, the other end of the varistor Z1 is connected to the fuse FU, the other end of the fuse FU is connected to the output end N of the rectifier filter circuit, and the voltage of the output end P is higher than the voltage of the output end N.

4. The drive circuit according to claim 1, characterized in that, The overcurrent detection circuit further includes: a controller connected to the collector of the triode of the optocoupler isolator U1, and the controller issues the overcurrent fault signal when the collector of the triode of the optocoupler isolator U1 outputs a low level.

5. The drive circuit according to claim 1, characterized in that, An RCD absorption circuit is connected to the output end of the rectifier filter circuit, and the RCD absorption circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C2, a capacitor C3, and a diode D7. The positive electrode of the diode D7 is connected to the output end P of the rectifier filter circuit, the other end of the diode D7 is connected to the resistor R1, the capacitor C2 and the resistor R2 are connected in parallel and then connected to the other end of the resistor R1, the capacitor C3 and the resistor R3 are connected in parallel, and one end of the resistor R3 is connected to the resistor R2, the other end of the resistor R3 is connected to the output end N of the rectifier filter circuit, and the voltage of the output end P is higher than the voltage of the output end N.

6. The drive circuit according to claim 1, wherein, The rectifying and filtering circuit includes a three-phase full-bridge rectifying circuit connected to the power grid and an LC filtering circuit connected to the three-phase full-bridge rectifying circuit, and the capacitor in the LC filtering circuit is a thin-film capacitor.

7. Inverter, characterized in that, Connect the inverter to the power grid using the driving circuit according to any one of claims 1-6.

8. Electrical equipment, characterized in that, Use the inverter according to claim 7.

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