CN105242118B - The inductance detection method and device of PFC pfc circuit - Google Patents

Abstract

The invention discloses a power factor correction PFC circuit inductance detection method and method. The PFC circuit includes an inductance, a power switch tube and a diode. The inductance detection method includes the following steps: detecting the voltage input to the PFC circuit to Obtain an instantaneous value of the input voltage, and control the power switch to turn on when the instantaneous value of the input voltage is within a preset voltage range; during the turn-on period of the power switch, detect the current flowing through the inductor; according to the detected Calculate the rate of change of the inductor current based on the current flowing through the inductor, and calculate the inductance of the inductor according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on, so as to achieve effective inductance parameters Detection, so that the abnormality of the inductance can be found in advance and corresponding protective measures can be taken.

Description

Inductance detection method and device for power factor correction PFC circuit

technical field

The invention relates to the technical field of power factor correction, in particular to an inductance detection method of a power factor correction PFC circuit and an inductance detection device of a power factor correction PFC circuit.

Background technique

In order to reduce the pollution of current harmonics and reactive power generated by electrical equipment to the power grid, my country has promulgated national standards to limit the current harmonics of electrical equipment, and electrical equipment can only enter the market if it meets the corresponding harmonic standards. In order to use electrical equipment to meet harmonic standards, power factor correction (PFC, Power Factor Correction) needs to be performed on it.

In order to improve the power factor of electrical equipment and reduce current harmonics, the related technology proposes a power factor corrector that performs chopping on the AC side. Several times of step-up switching operations are carried out to achieve the purpose of increasing the current opening angle and reducing the input current harmonics. The related art also proposes a fast switching power factor corrector.

The power factor correctors proposed in the related art can all improve the power factor of electrical equipment and at the same time make the input current harmonics meet the national standard. However, its disadvantage is that the characteristics of the inductance of the power factor corrector may change significantly during transportation, manufacturing or operation. For example, the inductance with sendust as the magnetic core may produce Cracks on the magnetic core lead to attenuation of the inductance verification. The inductance with the silicon steel sheet as the magnetic core may also experience a large drop in inductance when the enameled wire leaks. When there is a large deviation in the inductance parameter of the power factor corrector , its input current will be able to generate more serious harmonics, or the phenomenon of instantaneous overcurrent will easily cause circuit failure.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. Therefore, an object of the present invention is to provide an inductance detection method for a power factor correction PFC circuit.

Another object of the present invention is to provide an inductance detection device for a power factor correction PFC circuit.

In order to achieve the above object, an embodiment of the present invention proposes an inductance detection method of a power factor correction PFC circuit, the PFC circuit includes an inductor, a power switch tube and a diode, and the inductance detection method includes the following steps: detecting the input to The voltage of the PFC circuit is used to obtain the instantaneous value of the input voltage, and when the instantaneous value of the input voltage is within the preset voltage range, the power switch is controlled to be turned on; The current of the inductor; calculate the rate of change of the inductor current according to the detected current flowing through the inductor, and calculate the inductance of the inductor according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on.

According to the inductance detection method of the PFC circuit proposed in the embodiment of the present invention, the voltage input to the PFC circuit is detected to obtain the instantaneous value of the input voltage, and the power switch tube is controlled to turn on when the instantaneous value of the input voltage is within the preset voltage range. During the turn-on period of the tube, the current flowing through the inductor is detected, and the rate of change of the inductor current is calculated according to the detected current flowing through the inductor, and the inductance of the inductor is calculated according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on. Therefore, the effective detection of the inductance parameter can be realized, so that the abnormality of the inductance can be found in advance and corresponding protection measures can be taken.

According to some embodiments of the present invention, calculating the rate of change of the inductor current according to the detected current flowing through the inductor specifically includes: acquiring a first inductor current value and a second inductor current value at a preset sampling time interval; according to the The first inductor current value, the second inductor current value, and the preset sampling time interval calculate the inductor current change rate.

According to some embodiments of the present invention, the inductance is calculated according to the following formula:

Wherein, L _est is the inductance, V _in is the instantaneous value of the input voltage when the power switch tube is turned on, I ₂ is the second inductor current value, I ₁ is the first inductor current value, T _r is the preset sampling time interval.

According to some embodiments of the present invention, the inductance detection method of the power factor correction PFC circuit further includes: controlling the power switch tube to be turned off after the power switch tube is turned on for a preset time.

According to some embodiments of the present invention, the method for detecting the inductance of the power factor correction PFC circuit further includes: when the inductance is smaller than a preset inductance, protecting the PFC circuit according to a preset protection strategy.

In order to achieve the above object, another embodiment of the present invention proposes an inductance detection device for a power factor correction PFC circuit, the PFC circuit includes an inductor, a power switch tube, and a diode, and the inductance detection device includes: a voltage detection module, It is used to detect the voltage input to the PFC circuit to obtain the instantaneous value of the input voltage; the current detection module is used to detect the current flowing through the inductor; the control module is used to detect when the instantaneous value of the input voltage is within a preset voltage range Controlling the opening of the power switch tube during internal time; the inductance calculation module is used to detect the current flowing through the inductor through the current detection module during the opening period of the power switch tube, and according to the detected current flowing through the inductor Calculate the rate of change of the inductor current, and calculate the inductance of the inductor according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on.

According to the inductance detection device of the PFC circuit proposed by the embodiment of the present invention, the voltage input to the PFC circuit is detected by the voltage detection module to obtain the instantaneous value of the input voltage, and the control module controls the power switch when the instantaneous value of the input voltage is within a preset voltage range When the power switch tube is turned on, the electric six detection module detects the current flowing through the inductor, and the inductance calculation module calculates the rate of change of the inductor current according to the detected current flowing through the inductor, and according to the rate of change of the inductor current and the power switch tube The inductance of the inductor is calculated from the instantaneous value of the input voltage when it is turned on, so that the effective detection of the inductance parameters can be realized, and the abnormality of the inductance can be found in advance and corresponding protective measures can be taken.

According to some embodiments of the present invention, the inductance calculation module is specifically configured to acquire a first inductor current value and a second inductor current value at a preset sampling time interval, and value, the preset sampling time interval to calculate the rate of change of the inductor current.

According to some embodiments of the present invention, the inductance calculation module calculates the inductance according to the following formula:

Wherein, L _est is the inductance, V _in is the instantaneous value of the input voltage when the power switch tube is turned on, I ₂ is the second inductor current value, I ₁ is the first inductor current value, T _r is the preset sampling time interval.

According to some embodiments of the present invention, the control module is further configured to control the power switch to turn off after the power switch is turned on for a preset time.

According to some embodiments of the present invention, the control module is further configured to, when the inductance is less than a preset inductance, protect the PFC circuit according to a preset protection strategy.

Description of drawings

1 is a flow chart of an inductance detection method for a power factor correction PFC circuit according to an embodiment of the present invention;

2 is a schematic diagram of the principle of an inductance detection method for a power factor correction PFC circuit according to an embodiment of the present invention;

3 is a flow chart of an inductance detection method for a power factor correction PFC circuit according to an embodiment of the present invention;

4 is a schematic block diagram of an inductance detection device of a power factor correction PFC circuit according to an embodiment of the present invention; and

FIG. 5 is a schematic diagram of an inductance calculation module of a power factor correction PFC circuit according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

The method and device for detecting the inductance of the power factor correction PFC circuit proposed by the embodiments of the present invention are described below with reference to the accompanying drawings.

Wherein, the power factor correction PFC circuit can be connected to the power supply device of the inverter air conditioner. As shown in FIG. 4 , the power supply device of the inverter air conditioner may include a rectifier circuit 10 , a PFC (Power Factor Correction, power factor correction) circuit 20 and an electrolytic capacitor E1 . Wherein, the input terminal of the rectifier circuit 10 is connected with the single-phase AC power supply AC, and the rectifier circuit 10 is used to rectify the single-phase alternating current provided by the single-phase AC power supply AC to obtain rectified direct current; the PFC circuit 20 is connected to the rectifier circuit 10 Between the output terminal and the electrolytic capacitor E1, the PFC circuit 20 is used to correct the power factor of the power supply; the electrolytic capacitor E1 is connected in parallel with the load 30 . Wherein, the load 30 may preferably be a compressor M, and the load 30 may also be an internal switching power supply, a DC fan, and the like.

That is to say, the single-phase AC power supply AC is uncontrollably rectified by the rectifier circuit 10 , then passes through the PFC circuit 20 , and the output is connected to the large-capacity electrolytic capacitor E1 to supply power to the load 30 .

More specifically, the PFC circuit 20 may be a PFC circuit with a boost function, or a PFC circuit without a boost function. As shown in Figure 4, the PFC circuit 20 can be a Boost-type PFC circuit with a boost function, and the Boost-type PFC circuit can include an inductor L1, a power switch tube S1, and a diode D1, wherein one end of the inductor L1 is connected to the first end of the rectifier circuit 10 One output terminal is connected, the other end of the inductor L1 is connected to the anode of the diode D1, and there is a first node between the inductor L1 and the diode D1; the cathode of the diode D1 is connected to the positive terminal of the electrolytic capacitor E1; the collector of the power switch tube S1 is connected to the The first node is connected, the emitter of the power switch S1 is respectively connected with the second output terminal of the rectifier circuit 10 and the negative terminal of the electrolytic capacitor E1, and the gate of the power switch S1 is used to receive the control signal.

Combining with the PFC circuit in FIG. 4 , an embodiment of the present invention proposes an inductance detection method for a power factor correction PFC circuit.

FIG. 1 is a flowchart of an inductance detection method for a power factor correction PFC circuit according to an embodiment of the present invention. The PFC circuit includes an inductor, a power switch tube and a diode. As shown in Figure 1, the inductance detection method of the power factor correction PFC circuit includes the following steps:

S1: Detect the voltage input to the PFC circuit to obtain the instantaneous value of the input voltage, and control the power switch to turn on when the instantaneous value of the input voltage is within the preset voltage range.

Wherein, the voltage input to the PFC circuit is the rectified voltage. According to a specific example of the present invention, the voltage input to the PFC circuit can be detected through the voltage dividing resistors R1 and R2 shown in FIG. 4 .

According to a specific example of the present invention, as shown in Figure 2, the preset voltage interval can be (Vtl, Vth), so judging whether the instantaneous value of the input voltage is within the preset voltage interval is to judge whether the instantaneous value of the input voltage is greater than Vtl And less than Vth, when the instantaneous value of the input voltage is greater than Vtl and less than Vth, it means that the instantaneous value of the input voltage is within the preset voltage range, at this time, the control power switch is turned on, as shown in Figure 2, when the instantaneous value of the input voltage reaches Vtl , the switch control signal becomes high level, and the power switch tube is turned on.

It should be noted that, Vtl and Vth can take values between 30%-60% of the peak value of the AC input voltage, and it is guaranteed that Vtl<Vth. For example, in the case of 220V AC RMS input, the input voltage peak value is 310V, then Vtl and Vth can take values between 93V and 182V.

S2: During the turn-on period of the power switch tube, detect the current flowing through the inductor.

According to an embodiment of the present invention, the inductance detection method of the PFC circuit further includes: controlling the power switch tube to be turned off after the power switch tube is turned on for a preset time. Wherein, the preset time may be in microsecond level, for example, it may be 5-30us.

Specifically, the power switch tube can be turned on or off under the control of the switch control signal output by the control module. As shown in Figure 2, when the switch control signal is at a high level, the power switch is turned on, and current flows through the inductor, and the current flowing through the inductor rises rapidly as shown in Figure 2, resulting in a measurable inductor current. After continuously outputting the high level for the preset time T, the switch control signal becomes low level, and the power switch tube is turned off, that is, the power switch tube is controlled to be turned on and then turned off after the preset time T, and the preset time is the power switch tube Continuous turn-on time, thus, because the preset time is very short (microsecond level), the power switch tube is equivalent to being turned on under the action of the pulse voltage.

Specifically, as shown in FIG. 3, the inductance detection method of the embodiment of the present invention includes the following steps:

S101: Determine whether an inductance detection instruction is received. If yes, execute step S102; if no, return to step S101.

S102: Detect the voltage input to the PFC circuit to obtain an instantaneous value of the input voltage.

S103: Determine whether the instantaneous value of the input voltage is greater than Vtl and less than Vth. If yes, execute step S104; if no, return to step S103.

S104: Control the power switch tube to be turned on.

S105: After the power switch tube is continuously turned on for a preset time T, control the power switch tube to be turned off.

Wherein, the current flowing through the inductor is the rectified current or the current input to the PFC. According to a specific example of the present invention, the current flowing through the inductor can be detected through the non-inductive resistor R3 shown in FIG. 4 . In practical applications, other methods can also be used to detect the inductor current, such as Hall sensors.

S3: Calculate the rate of change of the inductor current according to the detected current flowing through the inductor, and calculate the inductance of the inductor according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on.

That is to say, the inductance detection method of the embodiment of the present invention determines the inductance of the inductor by detecting the rate of change of the inductor current under the action of the pulse voltage.

It should be noted that, as can be seen from the above embodiments, the turn-on time of the power switch tube is very short, reaching the level of microseconds, so that during the turn-on period of the power switch tube, the voltage input to the PFC circuit remains basically unchanged, so it can be determined according to The inductance of the inductor is calculated from the instantaneous value of the input voltage when the power switch tube is turned on.

Specifically, in the embodiment of the present invention, the instantaneous value of the input voltage of the PFC circuit can be detected first, and judge whether the instantaneous value of the input voltage is within the preset voltage range. When the instantaneous value of the input voltage is within the preset voltage range, the The power switch tube is connected in series with the inductor, and the power switch tube is controlled to keep on within the preset time T, so that the current flowing through the inductor rises gradually, and the rate of change of the inductor current is calculated during this process, and according to the rate of change of the inductor current and the input The instantaneous value of the voltage is used to calculate the estimated value of the inductance.

Therefore, the inductance detection method of the embodiment of the present invention can realize the effective detection of the inductance parameter, so that the abnormality of the inductance can be found in advance and corresponding protection measures can be taken. In addition, most power factor correctors have a power switch tube connected in series with the inductor and a current detection module for detecting the inductor current, so this method does not require additional hardware costs.

According to a specific embodiment of the present invention, calculating the rate of change of the inductor current according to the detected current flowing through the inductor includes: acquiring the first inductor current value and the second inductor current value at a preset sampling time interval; The current value, the second inductor current value, and the preset sampling time interval are used to calculate the rate of change of the inductor current.

Specifically, the inductance can be calculated according to the following formula:

Among them, L _est is the inductance, V _in is the instantaneous value of the input voltage when the power switch tube is turned on, I ₂ is the second inductor current value, I ₁ is the first inductor current value, T _r is the preset sampling time interval .

Specifically, during the turn-on process of the power switch tube, the current flowing through the inductor can be sampled twice, as shown in the example in Figure 2, the first sampling is performed at the sampling time T1 to obtain the first inductor current value I ₁ , at The second sampling is performed at the sampling time T2 to obtain the second inductor current value I ₂ . Thus, after obtaining I ₁ and I ₂ , the difference between the sampling time T2 and the adoption time T1 is the preset sampling time interval T _r , and then the inductor current change rate can be calculated, and according to the current change rate and power The inductance L _{est is} calculated from the instantaneous value V _in of the input voltage when the switch tube is turned on. That is to say, in the case where the first inductor current value I ₁ , the second inductor current value I ₂ , the preset sampling time interval T _r and the instantaneous value V _in of the input voltage are all known, it can be calculated according to the formula The estimated value L _est of the inductance.

Wherein, the preset sampling time interval T _r =T2-T1, T1 and T2 are the sampling moments within the continuous on-time T of the power switch tube respectively. The preset sampling time interval T _r is set reasonably. In the time interval from T1 to T2, it is necessary to ensure that the inductor current has a sufficiently large rate of change, and at the same time, it must be ensured that the inductor current cannot be too large to avoid overcurrent faults.

The following is an example of calculating the values of T _r , T1 and T2: Assume that the nominal value of the inductance is L0=400uH, Vtl is 150V, and Vth is 160V. To ensure that the total change rate of the inductor current is around dI=10A, It is desirable to keep on the time T=2*L0*dI/(Vtl+Vth)=25.8us. In order to ensure that the current sampling point avoids the ringing phenomenon caused by the action of the power switch tube, T1=10%T, T2=90%T, therefore, _Tr =T2-T1=20.6us.

In addition, the inductance detection method of the power factor correction PFC circuit further includes: when the inductance is smaller than a preset inductance, protecting the PFC circuit according to a preset protection strategy. That is to say, when the inductance is less than the preset inductance, it means that the inductance is abnormal, and protective measures can be taken in advance, such as controlling the power factor correction PFC circuit to disable, or using the communication interface to send a prompt signal of abnormal inductance.

In addition, it should be noted that since the inductance detection method of the embodiment of the present invention may cause a certain current peak during the working process, which may affect the normal operation of the power factor correction PFC circuit, therefore, this method needs to be executed before the PFC circuit works normally. The inductance detection method of the embodiment of the invention.

In summary, according to the inductance detection method of the PFC circuit proposed by the embodiment of the present invention, the voltage input to the PFC circuit is detected to obtain the instantaneous value of the input voltage, and the power switch tube is controlled when the instantaneous value of the input voltage is within the preset voltage range. Turn-on, during the turn-on period of the power switch tube, detect the current flowing through the inductor, and calculate the rate of change of the inductor current according to the detected current flowing through the inductor, and calculate according to the rate of change of the inductor current and the instantaneous value of the input voltage when the power switch tube is turned on The inductance of the inductor can be effectively detected, so that the abnormality of the inductor can be detected in advance and corresponding protective measures can be taken.

Another aspect of the present invention also provides an inductance detection device for a power factor correction PFC circuit.

FIG. 4 is a schematic diagram of an inductance detection device of a power factor correction PFC circuit according to an embodiment of the present invention. As shown in FIG. 4 , the PFC circuit includes an inductor L1 , a power switch tube S1 and a diode D1 , and the inductance detection device 100 includes: a voltage detection module 101 , a current detection module 102 , a control module 103 and an inductance calculation module 104 .

Wherein, the voltage detection module 101 is used to detect the voltage input to the PFC circuit 10 to obtain the instantaneous value of the input voltage. Wherein, the voltage input to the PFC circuit 10 is the rectified voltage. Specifically, the voltage detection module 101 may include a voltage detection unit and a voltage signal processing unit, wherein the voltage signal processing unit may be a single-chip microcomputer (MCU) or a digital signal processor (DSP), and the voltage detection unit is used to detect the voltage input to the PFC circuit 10 to output a voltage detection signal; the voltage signal processing unit is used to process the voltage detection signal output by the voltage detection unit to obtain the instantaneous value of the input voltage. DSP) and combined with the voltage detection unit to obtain the instantaneous value of the input voltage. According to a specific example of the present invention, the voltage detection unit includes voltage dividing resistors R1 and R2 shown in FIG. 4 .

The current detection module 102 is used to detect the current flowing through the inductor L1. Wherein, the current flowing through the inductor is the rectified current or the current input to the PFC. Specifically, the current detection module 102 may include a current detection unit and a current signal processing unit, wherein the current signal processing unit may be a single-chip microcomputer (MCU) or a digital signal processor (DSP), and the current detection unit is used to detect the current flowing through the inductor L1 The current to output the current detection signal; the current signal processing unit is used to process the current detection signal output by the current detection unit to obtain the inductance current value, that is, the current detection module 102 through a single chip microcomputer (MCU) or a digital signal processor (DSP) And combined with the current detection unit to obtain the inductor current value. According to a specific example of the present invention, the current detection unit includes a non-inductive resistor R3 shown in FIG. 4 . In practical applications, other methods can also be used to detect the inductor current, such as Hall sensors.

The control module 103 is used for controlling the power switch Q1 to be turned on when the instantaneous value of the input voltage is within a preset voltage range.

According to an embodiment of the present invention, the control module 103 is further configured to: control the power switch tube Q1 to turn off after the power switch tube Q1 is turned on for a preset time. Wherein, the preset time may be in microsecond level, for example, it may be 5-30us.

Specifically, the power switch tube Q1 can be turned on or off under the control of the switch control signal output by the control module 103 . As shown in Figure 2, when the switch control signal is at a high level, the power switch Q1 is turned on, and a current flows through the inductor, and the current flowing through the inductor rises rapidly as shown in Figure 2, generating a measurable inductor current. After continuously outputting a high level for a preset time T, the switch control signal becomes a low level, and the power switch tube Q1 is turned off, that is, the control module 103 controls the power switch tube Q1 to be turned on and then turned off for a preset time T, and the preset time is is the continuous turn-on time of the power switch tube. Therefore, because the preset time is very short (microsecond level), the power switch tube Q1 is equivalent to being turned on under the action of the pulse voltage.

The inductance calculation module 104 is used to detect the current flowing through the inductor through the current detection module 102 during the turn-on period of the power switch tube, and calculate the rate of change of the inductor current according to the detected current flowing through the inductor, and according to the rate of change of the inductor current and the power switch tube The inductance of the inductor is calculated from the instantaneous value of the input voltage when it is turned on, wherein the control module 103 and the inductance calculation module 104 can be single-chip microcomputers (MCUs) or digital signal processors (DSPs). That is to say, the inductance calculation module 104 can determine the inductance of the inductor L1 by detecting the rate of change of the inductor current under the action of the pulse voltage.

It should be noted that, as can be seen from the above embodiments, the turn-on time of the power switch tube is very short, reaching the level of microseconds, so that during the turn-on period of the power switch tube, the voltage input to the PFC circuit remains basically unchanged, so it can be determined according to The inductance of the inductor is calculated from the instantaneous value of the input voltage when the power switch tube is turned on.

Specifically, in the embodiment of the present invention, the instantaneous value of the input voltage of the PFC circuit 20 can be detected by the voltage detection module 101 first, and then the control module 103 judges whether the instantaneous value of the input voltage is within a preset voltage range. When the value is within the preset voltage range, the control module 103 controls the power switch tube Q1 to keep on for a preset time T, so that the current flowing through the inductor L1 gradually increases, and the inductance calculation module 104 can calculate the rate of change of the inductor current during this process , and according to the rate of change of the inductor current and the instantaneous value of the input voltage, the estimated value of the inductance is calculated.

Therefore, the inductance detection device of the embodiment of the present invention can realize the effective detection of the inductance parameter, so that the abnormality of the inductance can be found in advance and corresponding protection measures can be taken. In addition, most power factor correctors have a power switch tube connected in series with the inductor and a current detection module for detecting the inductor current, so this method does not require additional hardware costs.

According to a specific example of the present invention, as shown in FIG. 2, the preset voltage interval may be (Vtl, Vth), so that the control module 103 may determine whether the instantaneous value of the input voltage is within the preset voltage interval (Vtl, Vth), that is In order to judge whether the instantaneous value of the input voltage is greater than Vtl and less than Vth, when the instantaneous value of the input voltage is greater than Vtl and less than Vth, it means that the instantaneous value of the input voltage is within the preset voltage range. At this time, the control module 103 controls the power switch to turn on, as shown in the figure In the example of 2, when the instantaneous value of the input voltage reaches Vtl, the switch control signal becomes high level, and the power switch tube Q1 is turned on.

It should be noted that, Vtl and Vth can take values between 30%-60% of the peak value of the AC input voltage, and it is guaranteed that Vtl<Vth. For example, in the case of 220V AC RMS input, the input voltage peak value is 310V, then Vtl and Vth can take values between 93V and 182V.

According to a specific embodiment of the present invention, the inductance calculation module 104 is specifically configured to obtain the first inductor current value and the second inductor current value at a preset sampling time interval, and according to the first inductor current value and the second inductor current value, The rate of change of the inductor current is calculated at a preset sampling interval.

Specifically, the inductance calculation module 104 can calculate the inductance according to the following formula:

Among them, L _est is the inductance, V _in is the instantaneous value of the input voltage when the power switch tube is turned on, I ₂ is the second inductor current value, I ₁ is the first inductor current value, T _r is the preset sampling time interval .

Specifically, during the turn-on process of the power switch tube Q1, the current through the inductor L can be sampled twice by the current detection module 102. As shown in the example in FIG. 2, the first sampling is performed at the sampling time T1 to obtain the first The inductor current value I ₁ is sampled for the second time at the sampling time T2 to obtain the second inductor current value I ₂ . Thus, after the inductance calculation module 104 obtains I ₁ and I ₂ , the difference between the sampling time T2 and the adoption time T1 is the preset sampling time interval T _r , and then the rate of change of the inductor current can be calculated, and according to the current The inductance L _{est is} calculated from the rate of change and the instantaneous value V _in of the input voltage when the power switch tube Q1 is turned on. That is to say, as shown in Fig. 5, when the first inductor current value I ₁ , the second inductor current value I ₂ , the preset sampling time interval T _r and the instantaneous value V _{in of} the input voltage are all known, The inductance calculation module 104 can calculate according to the formula The estimated value L _est of the inductance.

Wherein, the preset sampling time interval T _r =T2-T1, T1 and T2 are the sampling moments within the continuous on-time T of the power switch tube Q1 respectively. The preset sampling time interval T _r is set reasonably. In the time interval from T1 to T2, it is necessary to ensure that the inductor current has a sufficiently large rate of change, and at the same time, it must be ensured that the inductor current cannot be too large to avoid overcurrent faults.

The following is an example of calculating the values of T _r , T1 and T2: Assume that the nominal value of the inductance is L0=400uH, Vtl is 150V, and Vth is 160V. To ensure that the total change rate of the inductor current is around dI=10A, It is desirable to keep on the time T=2*L0*dI/(Vtl+Vth)=25.8us. In order to ensure that the current sampling point avoids the ringing phenomenon caused by the action of the power switch tube, T1=10%T, T2=90%T, therefore, _Tr =T2-T1=20.6us.

In addition, the control module 103 is also configured to protect the PFC circuit 20 according to a preset protection strategy when the inductance is smaller than the preset inductance. That is to say, when the inductance is less than the preset inductance, it means that the inductance is in an abnormal state, and the control module 103 can take protective measures in advance, such as controlling the power factor correction PFC circuit 20 to disable, or using the communication interface to send a notification of abnormal inductance. Signals etc.

In addition, it should be noted that since the inductance detection device of the embodiment of the present invention may cause a certain current peak during the working process, which may affect the normal operation of the power factor correction PFC circuit, therefore, the inductance must be performed before the PFC circuit works normally. detection.

To sum up, according to the inductance detection device of the PFC circuit proposed by the embodiment of the present invention, the voltage input to the PFC circuit is detected by the voltage detection module to obtain the instantaneous value of the input voltage, and when the instantaneous value of the input voltage is within the preset voltage range The control module controls the turn-on of the power switch tube. During the turn-on period of the power switch tube, the current flowing through the inductor is detected by the electric six detection module. Calculate the inductance of the inductor based on the instantaneous value of the input voltage when the power switch tube is turned on, so that the effective detection of the inductance parameters can be realized, so that the abnormality of the inductance can be found in advance and corresponding protective measures can be taken.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial", The orientation or positional relationship indicated by "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or element Must be in a particular orientation, be constructed in a particular orientation, and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (10)

1. a kind of inductance detection method of PFC pfc circuit, which is characterized in that the pfc circuit includes inductance, work( Rate switching tube and diode, the inductance detection method include the following steps：

Detection is input to the voltage of the pfc circuit to obtain input voltage instantaneous value, and exists in the input voltage instantaneous value It is open-minded that the power switch tube is controlled when in predeterminated voltage section；

During the power switch tube is opened, the electric current of the inductance is flowed through in detection；

According to the Current calculation inductive current change rate for flowing through inductance described in detecting, and according to the inductive current change rate Input voltage instantaneous value when being opened with the power switch tube calculates the inductance value of the inductance.

2. the inductance detection method of PFC pfc circuit according to claim 1, which is characterized in that according to inspection The Current calculation inductive current change rate for flowing through inductance measured, specifically includes：

The first inductor current value and the second inductor current value are obtained in default sampling time interval；

The inductance electricity is calculated according to first inductor current value and the second inductor current value, the default sampling time interval Rheology rate.

3. the inductance detection method of PFC pfc circuit according to claim 2, which is characterized in that according to Lower formula calculates the inductance value：

Wherein, L_estFor the inductance value, V_inInput voltage instantaneous value when being opened for the power switch tube, I₂It is described Two inductor current values, I₁For first inductor current value, T_rFor the default sampling time interval.

4. the inductance detection method of PFC pfc circuit according to claim 1, which is characterized in that further include：

The power switch tube is controlled after the power switch tube opens preset time to close.

5. the inductance detection method of the PFC pfc circuit according to any one of claim 1-4, feature exist In further including：

When the inductance value is less than default inductance value, the pfc circuit is protected according to default Preservation tactics.

6. a kind of inductance detection device of PFC pfc circuit, which is characterized in that the pfc circuit includes inductance, work( Rate switching tube and diode, the inductance detection device include：

Voltage detection module is input to the voltage of the pfc circuit to obtain input voltage instantaneous value for detecting；

Current detection module, for detecting the electric current for flowing through the inductance；

Control module is opened for controlling the power switch tube when the input voltage instantaneous value is in predeterminated voltage section It is logical；

Inductance computing module, it is described for being flowed through by current detection module detection during the power switch tube is opened The electric current of inductance, and according to the Current calculation inductive current change rate for flowing through inductance described in detecting, and according to the electricity Input voltage instantaneous value when inducing current change rate and the power switch tube are opened calculates the inductance value of the inductance.

7. the inductance detection device of PFC pfc circuit according to claim 6, which is characterized in that the electricity Sense computing module is specifically used for,

The first inductor current value and the second inductor current value are obtained in default sampling time interval, and according to first inductance electricity Flow valuve and the second inductor current value, the default sampling time interval calculate the inductive current change rate.

8. the inductance detection device of PFC pfc circuit according to claim 7, which is characterized in that the electricity Feel computing module and the inductance value is calculated according to following formula：

Wherein, L_estFor the inductance value, V_inInput voltage instantaneous value when being opened for the power switch tube, I₂It is described Two inductor current values, I₁For first inductor current value, T_rFor the default sampling time interval.

9. the inductance detection device of PFC pfc circuit according to claim 6, which is characterized in that the control Molding block is additionally operable to, and the power switch tube is controlled after the power switch tube opens preset time and is closed.

10. the inductance detection device of the PFC pfc circuit according to any one of claim 6-9, feature It is, the control module is additionally operable to, when the inductance value is less than default inductance value, according to default Preservation tactics to described Pfc circuit is protected.