A protection device for a frequency converter and an air conditioner

Abstract

The application discloses a protection device of a frequency converter and an air conditioner, and the device comprises: a bus overcurrent protection unit arranged between an output end of a rectifier bridge stack and a main control chip, and in the case that bus voltage output by the rectifier bridge stack is greater than a preset overcurrent protection voltage, the main control chip is caused to turn off a control signal of a power device of the frequency converter; a pressure overload protection unit located at an exhaust port of a compressor of a device to which the frequency converter belongs and arranged in a control power loop between a power supply control power supply of the main control chip and the main control chip, and in the case that pressure at the exhaust port of the compressor is greater than a preset pressure protection value, the control power loop between the power supply control power supply of the main control chip and the main control chip is caused to be disconnected, so that the main control chip is powered off. According to the scheme, on the basis of the overcurrent protection function of the power device of the frequency converter, the system pressure overload protection function of the device to which the frequency converter belongs is added, and the safety of the power device of the frequency converter is improved through the double protection functions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of air conditioners, and particularly relates to a protection device of a frequency converter and an air conditioner, in particular to an overload protection circuit of a frequency converter and an air conditioner with the overload protection circuit of the frequency converter. BACKGROUND

[0002] With the continuous development of air conditioning technology, the products of household air conditioners and commercial air conditioners are being implemented in a large area. At the same time, the reliability of the variable frequency drive technology is attracting more and more attention. However, in the related scheme, the protection function of the power device of the air conditioner frequency converter only has the overcurrent protection function of the power device, so that the protection function of the power device of the air conditioner frequency converter is less. Once the overcurrent protection function fails, the safety of the power device of the air conditioner frequency converter cannot be guaranteed.

[0003] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0004] The purpose of the present application is to provide a protection device of a frequency converter and an air conditioner, so as to solve the problem that in the related scheme, the protection function of the power device of the frequency converter only has the overcurrent protection function of the power device, and once the overcurrent protection function fails, the safety of the power device of the frequency converter cannot be guaranteed. The effect of improving the safety of the power device of the frequency converter through double protection function is achieved by increasing the system pressure overload protection function of the equipment (such as air conditioner) to which the frequency converter belongs on the basis of the overcurrent protection function of the power device of the frequency converter.

[0005] The application provides a protection device of a frequency converter, wherein the frequency converter has a driving board and a master control board; the master control board is used for sending a control signal to a power device in the driving board to control the power device in the driving board; the driving board comprises a rectifier bridge stack, a bus capacitor and an inverter bridge stack; the inverter bridge stack has a power device; after alternating current passes through the rectifier bridge stack, a bus voltage is output; the bus voltage passes through the bus capacitor and the inverter bridge stack to supply power to a motor of a device to which the frequency converter belongs; the master control board comprises a master control chip and a power supply control power supply of the master control chip; the bus voltage output by the rectifier bridge stack is connected to the master control chip after passing through the power supply control power supply of the master control chip; the protection device of the frequency converter comprises a bus overcurrent protection unit and a pressure overload protection unit; wherein the bus overcurrent protection unit is arranged between an output end of the rectifier bridge stack and the master control chip, and is used for, based on the bus voltage output by the rectifier bridge stack, in the case that the bus voltage output by the rectifier bridge stack is greater than a preset overcurrent protection voltage, making the master control chip turn off the control signal of the power device of the frequency converter to perform bus overcurrent protection on the power device of the frequency converter; the pressure overload protection unit is located at an exhaust port of a compressor of the device to which the frequency converter belongs, and is arranged in a control power supply loop between the power supply control power supply of the master control chip and the master control chip, and is used for, based on the exhaust port pressure of the compressor of the device to which the frequency converter belongs, in the case that the exhaust port pressure of the compressor is greater than a preset pressure protection value, making the control power supply loop between the power supply control power supply of the master control chip and the master control chip be disconnected to make the master control chip be powered off, and performing system pressure overload protection on the power device of the frequency converter.

[0006] In some embodiments, the power supply control power supply of the master control chip comprises a switching power supply and a first switching unit; the first switching unit has a switching side and a control side; a positive pole of the bus voltage is connected to a first connection end of the switching power supply; a negative pole of the bus voltage is connected to a second connection end of the switching power supply after passing through the switching side of the first switching unit; and the control side of the first switching unit is connected to the master control chip.

[0007] In some embodiments, the pressure overload protection unit comprises: a pressure switch; the pressure switch has a pressure detection side and a switch side; the pressure detection side of the pressure switch is arranged in a pipeline where the exhaust port of the compressor is located; the switch side of the pressure switch is arranged in a control power supply loop formed by the bus voltage, the switching power supply and the first switch unit, and is connected with the first switch unit; the pressure detection side of the pressure switch is used for detecting the exhaust pressure in the pipeline where the exhaust port of the compressor is located, and in the case that the exhaust pressure in the pipeline where the exhaust port of the compressor is located is greater than a preset pressure protection value, the switch side of the pressure switch is disconnected to disconnect the control power supply loop formed by the bus voltage, the switching power supply and the first switch unit, so as to power off the main control chip.

[0008] In some embodiments, the first switch unit comprises: a first relay module and a first switch tube module; wherein the positive pole of the bus voltage is connected to the first connection end of the switching power supply; the negative pole of the bus voltage is connected to the negative pole of the bus voltage through the contact switch of the first relay module; the main control chip is connected to the control end of the first switch tube module; the direct current power supply is connected to the first connection end of the first switch tube module; the second connection end of the first switch tube module is grounded through the coil of the first relay module; and the switch side of the pressure switch is connected in the loop where the coil of the first relay module is located.

[0009] In some embodiments, the switch side of the pressure switch is connected between the second connection end of the first switch tube module and the coil of the first relay module; or the switch side of the pressure switch is connected between the coil of the first relay module and the ground.

[0010] In some embodiments, the first switch unit further comprises: a diode module; wherein the cathode of the diode module and the anode of the diode module are connected in parallel across the coil of the first relay module; and the second connection end of the first switch tube module is connected to the cathode of the diode module; in the case that the switch side of the pressure switch is connected between the coil of the first relay module and the ground, the switch side of the pressure switch is connected between the common end of the coil of the first relay module and the anode of the diode module and the ground.

[0011] In some embodiments, the drive board further comprises: a bus capacitor charging unit; the bus capacitor charging unit is arranged between the positive pole of the bus voltage and the inverter bridge stack, and is used for controlling the charging process of the bus capacitor based on the bus voltage.

[0012] In some embodiments, the bus overcurrent protection unit comprises a sampling resistance module and a comparator; the sampling resistance module is arranged between a bus at an output end of the rectifier bridge stack and the ground, and a voltage sampling end of the sampling resistance module is connected to a first input end of the comparator; a second output end of the comparator is used for inputting a preset overcurrent protection voltage; and an output end of the comparator is connected to the master control chip.

[0013] In another aspect, the present application provides an air conditioner comprising the above-mentioned protection device for the frequency converter.

[0014] Therefore, the scheme of the present application, on the basis of the overcurrent protection function of the power device of the frequency converter, increases a pressure switch (such as the pressure switch K4) on the high-pressure pipeline of the compressor of the equipment (such as the air conditioner) to which the frequency converter belongs, connects the electrical circuit of the pressure switch (such as the pressure switch K4) in series to the bus power supply branch of the control power supply of the frequency converter, i.e., connects the pressure switch (such as the pressure switch K4) in series to the power supply circuit between the bus of the driving board of the frequency converter and the switch power supply of the control chip (such as the MCU) of the frequency converter, when the pressure switch (such as the pressure switch K4) detects that the system pressure on the high-pressure pipeline of the compressor exceeds the pressure protection value of the pressure switch (such as the pressure switch K4), the pressure switch (such as the pressure switch K4) disconnects the bus power supply branch of the control power supply of the frequency converter, so that the frequency converter stops working, and the system pressure overload protection function of the equipment (such as the air conditioner) to which the frequency converter belongs is realized, thereby, on the basis of the overcurrent protection function of the power device of the frequency converter, the system pressure overload protection function of the equipment (such as the air conditioner) to which the frequency converter belongs is increased, and the safety of the power device of the frequency converter is improved through the double protection functions.

[0015] Other features and advantages of the present application will be described in the following description, and some will become apparent from the description, or will be learned from the practice of the present application.

[0016] The technical scheme of the present application will be described in further detail below with the aid of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the protection device for the frequency converter of the present application;

[0018] Figure 2 FIG. 2 is a structural schematic diagram of an embodiment of the overload protection circuit of the frequency converter of the present application. DETAILED DESCRIPTION

[0019] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0020] It is considered that, in the related scheme, the protection function of the power device of the air conditioner frequency converter only has the overcurrent protection function of the power device, so that the protection function of the power device of the air conditioner frequency converter is less, and once the overcurrent protection function fails, the safety of the power device of the air conditioner frequency converter cannot be guaranteed. In addition, for export frequency conversion air conditioner units, the safety certification requirement for the power device of the air conditioner frequency converter is relatively strict, not only the power device of the air conditioner frequency converter needs to be protected by detecting the current, but also the power device of the air conditioner frequency converter needs to be protected in combination with the system parameters of the air conditioner. That is to say, for export frequency conversion air conditioner units, the safety certification test requirement is gradually increasing and becoming more stringent; for the frequency converter of the frequency conversion air conditioner unit, the safety certification standard requires that the frequency converter must have a double line protection function for the motor open phase and motor locked-rotor experiment, that is, the protection function of the power device (such as a semiconductor) participating in control needs to have two protections.

[0021] In the related scheme, the frequency converter has an implementation scheme of overcurrent overload protection of the power module (such as a power device), which has software protection and hardware protection. The software protection protects when the sampling signal of the motor current sensor exceeds a certain current; the hardware protection compares the sampling signal of the current sensor with a resistance voltage division set value in a comparator, and when the set value is exceeded, the comparator outputs a flip signal to the protection pin of the IGBT drive chip of the power module (such as a power device) in the drive board of the motor. However, in the related scheme, the protection of the power module (such as a power device) of the frequency converter only has one layer of protection, while the safety standard requires double protection, and the two protection functions need to protect the same object and cannot have circuit overlap.

[0022] Therefore, the scheme of the present application proposes a protection device of a frequency converter, specifically an overload protection circuit of a frequency converter. On the basis of the frequency converter having the function of overcurrent overload protection of the power module in the related scheme, a control loop of a drive board of a motor is disconnected when the system pressure of the air conditioner is overloaded, so as to realize a double protection function, so as to realize a high safety protection scheme at a lower cost.

[0023] According to the embodiments of the present application, a protection device of a frequency converter is provided. Referring to Figure 1The diagram shows a structural schematic of an embodiment of the device of the present invention. The frequency converter has a drive board and a main control board; the main control board is used to send control signals to the power devices in the drive board to control the power devices in the drive board; the drive board includes: a rectifier bridge, a bus capacitor, and an inverter bridge; the inverter bridge has power devices; AC power is output as a bus voltage after passing through the rectifier bridge, and the bus voltage, after passing through the bus capacitor and the inverter bridge, supplies power to the motor of the equipment belonging to the frequency converter; the main control board includes: a main control chip, and a power supply control power source for the main control chip; the bus voltage output by the rectifier bridge is also connected to the main control chip after passing through the power supply control power source for the main control chip. Specifically, Figure 2 This is a schematic diagram of one embodiment of an overload protection circuit for a frequency converter. Figure 2 As shown, the air conditioner inverter includes: a rectifier bridge ( Figure 2 (not shown in the image), bus capacitor charging circuit of the driver board, bus capacitor ( Figure 2 (not shown in the image), inverter bridge rectifier, and main control chip (such as MCU).

[0024] Among them, the rectifier bridge rectifier ( Figure 2 (Not shown in the diagram) After rectifying the AC power, the output bus voltage Vdc is generated. The bus voltage Vdc is then charged by the bus capacitor charging circuit on the driver board and output to the bus capacitor (…). Figure 2 (Not shown in the image). Bus capacitor ( Figure 2 The output terminal (not shown) is connected to the inverter bridge rectifier. The inverter bridge rectifier includes: IGBT V1 with body diode D1, IGBT V2 with body diode D2, IGBT V3 with body diode D3, IGBT V4 with body diode D4, IGBT V5 with body diode D5, and IGBT V6 with body diode D6. Bus capacitor ( Figure 2 The first terminal (not shown) is connected to the collector of IGBT V1, the collector of IGBT V3, and the collector of IGBT V5, respectively. Bus capacitor ( Figure 2The second ends of the three diodes D1, D2 and D3 are connected to the emitter of the IGBT V4, the emitter of the IGBT V6 and the emitter of the IGBT V3 respectively. In the inverter bridge stack, the emitter of the upper bridge arm IGBT V1 is connected to the collector of the lower bridge arm IGBT V4, and the emitter of the upper bridge arm IGBT V1 is also connected to the U-phase inductor L1 of the motor M; the emitter of the upper bridge arm IGBT V3 is connected to the collector of the lower bridge arm IGBT V6, and the emitter of the upper bridge arm IGBT V3 is also connected to the V-phase inductor L2 of the motor M; the emitter of the upper bridge arm IGBT V5 is connected to the collector of the lower bridge arm IGBT V2, and the emitter of the upper bridge arm IGBT V5 is also connected to the W-phase inductor L3 of the motor M. A U-phase current sensor 11 is arranged at the input end of the U-phase inductor L1 of the motor M. A W-phase current sensor 12 is arranged at the input end of the W-phase inductor L3 of the motor M. The protection device of the frequency converter comprises a bus overcurrent protection unit and a pressure overload protection unit. Wherein,

[0025] The bus overcurrent protection unit is arranged between the output end of the rectifier bridge stack and the main control chip, and is used for, based on the bus voltage output by the rectifier bridge stack, in the case that the bus voltage output by the rectifier bridge stack is greater than a preset overcurrent protection voltage, making the main control chip turn off the control signal of the power device of the frequency converter, so as to perform bus overcurrent protection on the power device of the frequency converter. The power device of the frequency converter at least comprises the power device in the inverter bridge stack, such as making the main control chip turn off the PWM signal of the power device in the inverter bridge stack, so as to perform bus overcurrent protection on the power device in the inverter bridge stack.

[0026] The pressure overload protection unit is located at the exhaust port of the compressor of the device to which the frequency converter belongs, and is arranged in the control power supply loop between the power supply control power supply of the main control chip and the main control chip, and is used for, based on the exhaust port pressure of the compressor of the device to which the frequency converter belongs, in the case that the exhaust port pressure of the compressor is greater than a preset pressure protection value, disconnecting the control power supply loop between the power supply control power supply of the main control chip and the main control chip, so as to make the main control chip power off, so that the main control chip is in a power-off state and cannot send the PWM signal to the power device in the inverter bridge stack of the frequency converter, that is, making the main control chip turn off the PWM signal of the power device in the inverter bridge stack of the frequency converter, so as to perform system pressure overload protection on the power device of the frequency converter.

[0027] The overload protection circuit of the frequency converter provided by the scheme of the present application is based on the frequency converter provided with the power module overcurrent overload protection function (i.e. the overcurrent protection function of the power device of the frequency converter) in the related scheme, and a scheme of double line protection is added by detecting the system pressure overload of the air conditioner to disconnect the control circuit of the motor driving board, so that the double protection function of the power module overcurrent overload protection and the system pressure overload protection is realized, and the scheme of high safety protection is realized at a lower cost. The system pressure overload protection of the air conditioner is added to improve the safety of the air conditioner. It is also to meet the safety certification test requirements of the export frequency conversion air conditioner unit through the motor locked-rotor and motor open-phase experiments in the safety certification.

[0028] In some embodiments, the power supply control power supply of the master control chip comprises: a switching power supply and a first switching unit; the first switching unit has a switching side and a control side, the switching side of the first control unit is like the contact switch of a relay K1, and the control side of the first control unit is like the coil side of the relay K1; based on the bus voltage output by the rectifier bridge stack, the positive electrode of the bus voltage is connected to the first connection end of the switching power supply; the negative electrode of the bus voltage is connected to the second connection end of the switching power supply through the switching side of the first switching unit; and the control side (such as the coil of the relay K1) of the first switching unit is connected to the master control chip. Specifically, as shown in Figure 2 The air conditioner frequency converter further comprises: a switching power supply and a control power supply circuit of the frequency converter. The control power supply circuit of the frequency converter comprises a first switching unit.

[0029] In some embodiments, the pressure overload protection unit comprises: a pressure switch, such as the pressure switch K4 in Figure 2 The pressure detection side of the pressure switch is arranged in the pipeline where the exhaust port of the compressor is located, and the switching side of the pressure switch is arranged in the control power supply circuit formed by the bus voltage, the switching power supply and the first switching unit and connected to the first switching unit. The pressure detection side of the pressure switch is used to detect the exhaust pressure in the pipeline where the exhaust port of the compressor is located, and in the case that the exhaust pressure in the pipeline where the exhaust port of the compressor is located is greater than the preset pressure protection value, the switching side of the pressure switch is disconnected to disconnect the control power supply circuit formed by the bus voltage, the switching power supply and the first switching unit, so that the master control chip is powered off, so that the master control chip is in the power-off state and cannot send the PWM signal to the power device in the inverter bridge stack of the frequency converter, that is, the master control chip turns off the PWM signal of the power device in the inverter bridge stack of the frequency converter to protect the power device of the frequency converter from system pressure overload.

[0030] Referring to Figure 2 In the example shown, the scheme of the present application, when realizing the function of system pressure overload protection of the air conditioner, a pressure switch K4 is added on the high-pressure pipeline of the compressor of the air conditioner, specifically, the pressure switch K4 is arranged on the pipeline where the exhaust port of the compressor of the air conditioner is located. Among them, the pressure switch K4 will actively open the contact when detecting that the system pressure is too high, thereby breaking the power supply circuit of the control coil of the relay K1, and then the contact of the collector K1 will be disconnected, and the power supply on the driving board will be in a power-off state. The working principle of the pressure switch K4 is: when the system pressure of the pipeline connected to the pressure switch K4 (such as the high-pressure pipeline of the compressor of the air conditioner) reaches the pre-set pressure protection value, the pressure switch K4 will disconnect the connection of its own electrical circuit, so that the electrical circuit of the pressure switch K4 is in an open circuit state. In this way, on the basis of the overcurrent protection function of the power device of the frequency converter in the related scheme, the electrical circuit of the pressure switch K4 is connected in series to the bus power supply branch of the control power supply of the frequency converter, when the system pressure of the compressor is greater than the pressure protection value of the pressure switch K4, the DC bus of the frequency converter is disconnected from the power supply branch of the control power supply of the frequency converter, so that the main control chip (MCU) is in a power-off state. The main control chip (MCU) is the control chip of the driving board of the frequency converter, and after the main control chip (MCU) is in a power-off state, the driving board of the frequency converter stops working, and the frequency converter also stops working, realizing the second protection function. The main control chip (MCU) refers to the main control chip of the entire frequency conversion driving board, which is used to provide control signals for IGBT and other components such as switches K2 and K3.

[0031] In some embodiments, the first switch unit includes a first relay module and a first switch tube module. The first relay module is, for example, a relay K1, and the first switch tube module is, for example, a triode Q1.

[0032] Wherein, based on the bus voltage output by the rectifier bridge stack, the positive pole of the bus voltage is connected to the first connection end of the switching power supply; the negative pole of the bus voltage is connected to the negative pole of the bus voltage through the contact switch of the first relay module; the main control chip is connected to the control end (such as the base of the transistor Q1) of the first switch tube module; the DC power supply is connected to the first connection end (such as the collector of the transistor Q1) of the first switch tube module; the second connection end (such as the emitter of the transistor Q1) of the first switch tube module is connected to the cathode of the diode module through the coil of the first relay module and then grounded; the switching side of the pressure switch is connected in the loop where the coil of the first relay module is located, that is, the switching side of the pressure switch, the control power supply loop between the power supply control power supply of the main control chip and the main control chip. Wherein, the switching power supply is used to power the main control chip (MCU) of the drive board of the frequency converter, and the pressure switch K4 is connected in series in any one of the input line and the output line in the power supply loop of the switching power supply and the main control chip (MCU).

[0033] In some embodiments, the switching side of the pressure switch is connected between the second connection end (such as the emitter of the transistor Q1) of the first switch tube module and the coil of the first relay module; or the switching side of the pressure switch is connected between the coil of the first relay module and the ground.

[0034] Referring to Figure 2 The control power supply loop of the frequency converter includes the relay K1, the drive control circuit of the relay K1, and the pressure switch K4. The drive control circuit of the relay K1 includes the transistor Q1. The positive pole P of the bus voltage Vdc is also connected to the first connection end of the switching power supply. The negative pole N of the bus voltage Vdc is also connected to the second connection end of the switching power supply through the contact switch of the relay K1. The control signal of the relay K1 output by the main control chip (such as the MCU) is input to the base of the transistor Q1. The 12V DC power supply is connected to the collector of the transistor Q1, and the emitter of the transistor Q1 is grounded GND through the coil of the relay K1 and the pressure switch K4.

[0035] In some embodiments, the first switch unit further includes a diode module, such as a diode D7. Wherein, the cathode of the diode module and the anode of the diode module are connected in parallel across the coil of the first relay module; and the second connection end (such as the emitter of the transistor Q1) of the first switch tube module is connected to the cathode of the diode module; in the case that the switching side of the pressure switch is connected between the coil of the first relay module and the ground, the switching side of the pressure switch is connected between the common end of the coil of the first relay module and the anode of the diode module and the ground.

[0036] See Figure 2 In the example shown, the control power supply circuit of the frequency converter also includes: diode D7, which provides a discharge path for the coil of relay K1. The emitter of transistor Q1 is also connected to the cathode of diode D7. The two ends of diode D7 are connected in parallel across the coil of relay K1.

[0037] In some embodiments, the protection device for the frequency converter described in the present invention, the drive board, further includes: a bus capacitor charging unit, such as a bus capacitor charging circuit; the bus capacitor charging unit is disposed between the positive terminal of the bus voltage and the inverter bridge rectifier, and is used to control the charging process of the bus capacitor based on the bus voltage.

[0038] See Figure 2 The example shown includes a bus capacitor charging circuit on the driver board, comprising: switch K2, switch K3, and resistor R1. Switch K3 is connected in series with resistor R1, and then in parallel with switch K2. The positive terminal P of the bus voltage Vdc is connected to the bus capacitor ( ) after passing through switch K2. Figure 2 The first terminal (not shown in the diagram). The negative terminal N of the bus voltage Vdc is connected to the bus capacitor ( Figure 2 The second terminal (not shown in the diagram). Switches K2 and K3 can both be relays, serving as bus capacitor charging relays for the drive board of motor M. Specifically, the bus capacitor charging unit, based on the bus voltage, controls the charging process of the bus capacitor, including: when the bus capacitor begins charging, the bus capacitor charging unit controls switch K2 to open and switch K3 to close, thereby limiting the current of the bus capacitor charging process through resistor R1 to allow the bus capacitor to charge slowly; after the bus capacitor is fully charged, the unit controls switch K2 to close and switch K3 to open, thereby reducing the power consumption of resistor R1.

[0039] In some embodiments, the bus overcurrent protection unit includes: a sampling resistor module and a comparator, wherein the sampling resistor module is such as a bus current sampling resistor.

[0040] The sampling resistor module is arranged between the bus of the output end of the rectifier bridge stack and the ground, and the voltage sampling end of the sampling resistor module is connected to the first input end of the comparator; the second output end of the comparator is used for inputting a preset overcurrent protection voltage; and the output end of the comparator is connected to the main control chip, such as an overcurrent protection signal input end of the main control chip, to output an overcurrent protection trigger signal to the main control chip. The comparator is used for comparing the bus voltage output by the rectifier bridge stack with the preset overcurrent protection voltage, and in the case that the bus voltage output by the rectifier bridge stack is greater than the preset overcurrent protection voltage, an overcurrent protection signal is output to the main control chip, so that the main control chip turns off the control signal of the power device of the frequency converter, such as a PWM signal of the power device in the inverter bridge stack of the frequency converter, to perform bus overcurrent protection on the power device of the frequency converter.

[0041] In combination ​ In the example shown, the scheme of the present application realizes the overcurrent protection function of the power device of the frequency converter, specifically, in the power ground network of the DC bus of the frequency converter, a bus current sampling resistor for sampling the current of the DC bus is connected in series, the bus current sampling resistor converts the current signal of the DC bus into a voltage signal of the DC bus, and the voltage signal of the DC bus and a protection voltage signal for realizing the overcurrent protection function of the power device of the frequency converter are simultaneously input into a comparator. When the sampling voltage signal (i.e. the voltage signal of the DC bus) is greater than the protection voltage signal, the output of the comparator is reversed, and the output signal of the comparator is connected to the main control chip (such as an MCU), so that the overcurrent protection signal can be recognized, the overcurrent protection of the bus current is realized, and the overcurrent protection function of the power device of the frequency converter is realized. This protection serves as the first heavy protection for the power device of the frequency converter.

[0042] The scheme of the present application combines the first heavy protection function, that is, on the basis that the related scheme has the overcurrent overload protection of the power module (such as the power device) of the frequency converter, a pressure switch K4 is added on the high-pressure pipeline of the compressor, when the system load of the air conditioner is detected to be too high, the control signal of the relay K1 in the control power supply circuit of the frequency converter is disconnected, so that the double overload protection of the frequency converter is realized. The combination of the first heavy protection function and the second heavy protection function can realize the double line protection function of the frequency converter, can improve the safety of the air conditioner, and in addition, for the export frequency conversion air conditioner unit, the safety certification test requirements of the export frequency conversion air conditioner unit can also be met.

[0043] The technical scheme of the present application is characterized in that: on the basis of the over-current protection function of the power device of the frequency converter, a pressure switch (such as pressure switch K4) is added to the high-pressure pipeline of the compressor of the equipment (such as air conditioner) to which the frequency converter belongs, the electrical circuit of the pressure switch (such as pressure switch K4) is connected in series to the bus power supply branch of the control power supply of the frequency converter, that is, the pressure switch (such as pressure switch K4) is connected in series to the power supply circuit between the bus of the drive board of the frequency converter and the switching power supply of the control chip (such as MCU) of the frequency converter, when the pressure switch (such as pressure switch K4) detects that the system pressure on the high-pressure pipeline of the compressor exceeds the pressure protection value of the pressure switch (such as pressure switch K4), the pressure switch (such as pressure switch K4) disconnects the bus power supply branch of the control power supply of the frequency converter, so that the frequency converter stops working, and the system pressure overload protection function of the equipment (such as air conditioner) to which the frequency converter belongs is realized, thereby, on the basis of the over-current protection function of the power device of the frequency converter, the system pressure overload protection function of the equipment (such as air conditioner) to which the frequency converter belongs is added, and the safety of the power device of the frequency converter is improved through the double protection function.

[0044] According to the embodiment of the present application, an air conditioner corresponding to the protection device of the frequency converter is also provided. The air conditioner can include the protection device of the frequency converter described above.

[0045] Since the processing and functions realized by the air conditioner of the present embodiment are basically corresponding to the embodiments, principles and examples of the device, the description of the present embodiment will not be elaborated here, and the related descriptions in the foregoing embodiments can be referred to, which will not be repeated here.

[0046] The technical scheme of the present embodiment is characterized in that: on the basis of the over-current protection function of the power device of the frequency converter, a pressure switch (such as pressure switch K4) is added to the high-pressure pipeline of the compressor of the equipment (such as air conditioner) to which the frequency converter belongs, the electrical circuit of the pressure switch (such as pressure switch K4) is connected in series to the bus power supply branch of the control power supply of the frequency converter, that is, the pressure switch (such as pressure switch K4) is connected in series to the power supply circuit between the bus of the drive board of the frequency converter and the switching power supply of the control chip (such as MCU) of the frequency converter, when the pressure switch (such as pressure switch K4) detects that the system pressure on the high-pressure pipeline of the compressor exceeds the pressure protection value of the pressure switch (such as pressure switch K4), the pressure switch (such as pressure switch K4) disconnects the bus power supply branch of the control power supply of the frequency converter, so that the frequency converter stops working, and the system pressure overload protection function of the equipment (such as air conditioner) to which the frequency converter belongs is realized, thereby, on the basis of the over-current protection function of the power device of the frequency converter, the system pressure overload protection function of the equipment (such as air conditioner) to which the frequency converter belongs is added, and the safety of the power device of the frequency converter is improved through the double protection function.

[0047] In summary, those skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0048] The above description is only the preferred embodiment of the application, and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall fall within the scope of the claims of the application.

Claims

1. A protection device for a frequency converter, characterized in that The variable frequency device has a driving board and a main control board; The main control board is used for sending a control signal to a power device in the driving board to control the power device in the driving board; the driving board comprises a rectifier bridge stack, a bus capacitor and an inverter bridge stack; the inverter bridge stack has a power device; after alternating current passes through the rectifier bridge stack, a bus voltage is output; the bus voltage passes through the bus capacitor and the inverter bridge stack to supply power to a motor of a device to which the variable frequency device belongs; the main control board comprises a main control chip and a power supply control power supply of the main control chip; the bus voltage output by the rectifier bridge stack is connected to the main control chip through the power supply control power supply of the main control chip; the protection device of the variable frequency device comprises a bus overcurrent protection unit and a pressure overload protection unit; wherein The bus overcurrent protection unit is arranged between an output end of the rectifier bridge stack and the main control chip, and is used for, based on the bus voltage output by the rectifier bridge stack, in a case where the bus voltage output by the rectifier bridge stack is greater than a preset overcurrent protection voltage, making the main control chip turn off the control signal of the power device of the variable frequency device to perform bus overcurrent protection on the power device of the variable frequency device; The pressure overload protection unit is located at an exhaust port of a compressor of the device to which the variable frequency device belongs, and is arranged in a control power supply loop between the power supply control power supply of the main control chip and the main control chip, and is used for, based on the exhaust port pressure of the compressor of the device to which the variable frequency device belongs, in a case where the exhaust port pressure of the compressor is greater than a preset pressure protection value, making the control power supply loop between the power supply control power supply of the main control chip and the main control chip be disconnected, so that the main control chip is powered off, and the power device of the variable frequency device is protected from system pressure overload.

2. The protection device for a frequency converter according to claim 1, characterized in that The power supply control power supply of the main control chip comprises a switching power supply and a first switch unit; the first switch unit has a switch side and a control side; a positive electrode of the bus voltage is connected to a first connection end of the switching power supply; a negative electrode of the bus voltage is connected to a second connection end of the switching power supply through the switch side of the first switch unit; the control side of the first switch unit is connected to the main control chip.

3. The protection device for a frequency converter according to claim 2, characterized in that, The pressure overload protection unit comprises a pressure switch; the pressure switch has a pressure detection side and a switch side; the pressure detection side of the pressure switch is arranged in a pipeline where the exhaust port of the compressor is located; the switch side of the pressure switch is arranged in a control power supply loop formed by the bus voltage, the switching power supply and the first switch unit, and is connected to the first switch unit; The pressure detection side of the pressure switch is used for detecting the exhaust pressure in the pipeline where the exhaust port of the compressor is located, and in a case where the exhaust pressure in the pipeline where the exhaust port of the compressor is located is detected to be greater than a preset pressure protection value, the switch side of the pressure switch is disconnected, so that the control power supply loop formed by the bus voltage, the switching power supply and the first switch unit is disconnected, and the main control chip is powered off.

4. The protection device for a frequency inverter according to claim 3, characterized in that, The first switch unit comprises a first relay module and a first switch tube module; wherein The positive pole of the bus voltage is connected to the first connection end of the switching power supply; the negative pole of the bus voltage is connected to the negative pole of the bus voltage through the contact switch of the first relay module; the master control chip is connected to the control end of the first switch tube module; the direct current power supply is connected to the first connection end of the first switch tube module; the second connection end of the first switch tube module is grounded through the coil of the first relay module; and the switch side of the pressure switch is connected in the loop in which the coil of the first relay module is located.

5. The protection device for a frequency inverter according to claim 4, characterized in that, Wherein, The switch side of the pressure switch is connected between the second connection end of the first switch tube module and the coil of the first relay module, or the switch side of the pressure switch is connected between the coil of the first relay module and the ground.

6. The protection device for a frequency converter according to claim 5, characterized in that The first switch unit further comprises a diode module; wherein The cathode of the diode module and the anode of the diode module are connected in parallel across the coil of the first relay module; and the second connection end of the first switch tube module is connected to the cathode of the diode module. In the case where the switch side of the pressure switch is connected between the coil of the first relay module and the ground, the switch side of the pressure switch is connected between the common end of the coil of the first relay module and the anode of the diode module and the ground.

7. The protection device for a frequency inverter according to claim 1, characterized in that, The drive board further comprises a bus capacitor charging unit; the bus capacitor charging unit is arranged between the positive pole of the bus voltage and the inverter bridge stack, and is used to control the charging process of the bus capacitor based on the bus voltage.

8. The protection device of a frequency converter according to any one of claims 1 to 7, characterized by The bus overcurrent protection unit comprises a sampling resistor module and a comparator; wherein The sampling resistor module is arranged between the bus of the output end of the rectifier bridge stack and the ground, and the voltage sampling end of the sampling resistor module is connected to the first input end of the comparator; the second output end of the comparator is used to input a preset overcurrent protection voltage; and the output end of the comparator is connected to the master control chip.

9. An air conditioner characterized by comprising: Comprise: The protection device of the frequency converter according to any one of claims 1 to 8. The protection device of the frequency converter according to any one of claims 1 to 8.

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