Controller and fault judgment method

Abstract

The embodiment of the invention provides a controller and a fault judgment method, the fault judgment method can perform fault judgment on the controller, and the controller comprises N load branches; the fault judgment method comprises a short circuit judgment step and / or an open circuit judgment step. The short circuit judgment step comprises the following steps: controlling the controllable switch tubes of the M load branches to be closed, and controlling the controllable switch tubes of the (N-M) load branches to be disconnected; acquiring a sampling signal; judging the sampling signal and a first preset value; if the sampling signal is greater than or equal to the first preset value, judging that at least one short-circuit fault occurs; the open circuit judgment step comprises the steps of judging the sampling signal and a second preset value; if the sampling signal is smaller than or equal to the second preset value, at least one controllable switch tube or load has an open-circuit fault; wherein M and N are positive integers, N > = 2, and 1 < = M < N. According to the fault judgment method, the fault of the controller can be judged.

Description

Technical Field

[0001] The present invention relates to the field of electric control technology, and in particular to a controller with multi-channel controllable switch tubes and fault detection, and a fault judgment method. Background Art

[0002] In the field of electronic control, in order to meet user needs, controllable switch tubes are often used to control the output parameters of the controller, and the output parameters are adjusted by adjusting the working state of the controllable switch tube, such as adjusting the output power, output current, output voltage, etc. In order to increase the adjustable range of the output parameters, multiple controllable switch tubes are also set. For example, multiple controllable switch tubes can be set in the control circuits of electric heaters, electroplating, and electrophoretic painting, and the output parameters of the controller can be adjusted by controlling the controllable switch tubes. In order to ensure control reliability, the controller needs to be fault-detected. Summary of the invention

[0003] The object of the present invention is to provide a controller and a fault diagnosis method, wherein the fault diagnosis method can perform fault diagnosis on the controller. The fault diagnosis method can perform fault diagnosis on the controller.

[0004] To achieve the above object, an embodiment of the present invention adopts the following technical solution:

[0005] A fault judgment method is provided, which can judge the fault of a controller, wherein the controller comprises N load branches, the load branches comprise at least one controllable switch tube and a load, the controllable switch tube and the load are connected in series, and the N load branches are connected in parallel; the fault judgment method comprises a short circuit judgment step and / or an open circuit judgment step; the short circuit judgment step comprises: controlling the controllable switch tubes of the M load branches to be closed, and controlling the controllable switch tubes of the (NM) load branches to be disconnected; obtaining a sampling signal representing the total current flowing through the N load branches; judging the magnitude of the sampling signal and a first preset value; if the sampling signal is greater than or equal to the first preset value, judging that at least one of the controllable switch tubes that are controlled to be disconnected has a short circuit fault;

[0006] The open circuit judgment step includes: judging the size of the sampling signal and a second preset value; if the sampling signal is less than or equal to the second preset value, judging that at least one controllable switch tube or load in the load branch where the controlled closed controllable switch tube is located has an open circuit fault; wherein M and N are both positive integers, and N≥2, 1≤M<N.

[0007] The fault judgment method provided in the embodiment of the present application includes steps, and the controller applicable thereto has multiple load branches, each load branch includes at least one controllable switch tube. The fault judgment method controls the controllable switch tube, samples the total current, and compares the sampling signal with the first / second preset value to perform short circuit judgment and / or open circuit judgment.

[0008] On the other hand, an embodiment of the present application further provides a controller, comprising at least N load branches, wherein the load branches comprise at least one controllable switch tube and a load, wherein the controllable switch tube and the load are connected in series, and the N load branches are connected in parallel; the controller further comprises a sampling unit and a control unit, wherein an input end of the control unit is electrically connected to the sampling unit, and an output end of the control unit is electrically connected to a control end of the controllable switch tube, and the control unit is preset with a first preset value; the sampling unit is capable of sampling the total current of the N load branches, and outputting a sampling signal representing the total current to the control unit; the control unit is at least used to perform the following short-circuit fault judgment steps: controlling the controllable switch tubes of the M load branches to be closed, and controlling the controllable switch tubes of the (NM) load branches to be disconnected; obtaining the sampling signal; judging the magnitude of the sampling signal and the first preset value; if the sampling signal is greater than or equal to the first preset value, judging that at least one of the controllable switch tubes that are controlled to be disconnected has a short-circuit fault; wherein M and N are both positive integers, and N≥2, 1≤M<N.

[0009] The controller provided in the embodiment of the present application has multiple load branches, a sampling unit and a control unit. Each load branch includes at least one controllable switch tube. The control unit can control the controllable switch tube and determine whether a short circuit fault occurs based on the comparison of the sampling signal obtained by the sampling unit with the first preset value. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of the controller circuit principle provided by the first embodiment of the present invention;

[0011] Figure 2 is a schematic diagram of the controller circuit principle provided by the second embodiment of the present invention;

[0012] Figure 3 is a schematic diagram of the controller circuit principle provided by the third embodiment of the present invention;

[0013] Figure 4 is a schematic diagram of the controller circuit principle provided by the fourth embodiment of the present invention;

[0014] Figure 5 is a schematic diagram of the controller circuit principle provided by the fifth embodiment of the present invention;

[0015] Figure 6 is a flow chart of a control method provided by an embodiment of the present invention;

[0016] Figure 7 The controller uses Figure 6 A waveform diagram of a control method;

[0017] Figure 8 It is a flow chart of a short circuit fault judgment method provided by an embodiment of the present invention;

[0018] Fig. 9 is a schematic diagram of the controller circuit principle provided by the sixth embodiment of the present invention;

[0019] Fig.10 is a schematic diagram of the controller circuit principle provided by the seventh embodiment of the present invention;

[0020] Fig.11 yes Fig.10 The fault judgment waveform diagram of the controller shown;

[0021] Fig.12 yes Figure 4 The fault judgment waveform of the controller shown. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] like Figure 1-4 As shown, in the fields of vehicle-mounted electric heating, electroplating, electrophoretic painting, etc., the controller will set up multiple load branches, and the multiple load branches are then connected in parallel to the input power supply. The load branches include controllable switching tubes and loads. That is, the controller includes N controllable switching tubes, as shown in K21, K22, ... K2N, where N is a positive integer and N≥2, the first ends of the N controllable switching tubes are electrically connected to each other, and the second end of each controllable switching tube can be electrically connected to the load. By controlling the controllable switching tube, the power / current of the load can be controlled. Figure 1 The controller circuit diagram shown does not have a protection switch tube, but in order to further improve safety, Figure 2-Figure 4In the controller, a protection switch tube is also provided, as shown in K11 / K12. The protection switch tube is also a controllable switch tube. Both the protection switch tube and the controllable switch tube can be TGBT, MOS tube, triode, thyristor, etc. When the controllable switch tube of the load branch fails, protection can be achieved by controlling the protection switch tube. For example, if a short circuit occurs in the controllable switch tube, the protection switch tube is controlled to be disconnected, and the load branch no longer works. The protection switch tube does not participate in the adjustment of the output parameters and is in a normally closed state during the control process of normal operation. Figure 2-Figure 4 The controller circuit schematic diagram shown is suitable for the controller of vehicle-mounted electric heating. The input power supply can be a high-voltage power supply Vdc. The load branch is also called a heating branch. The heating branch includes at least one controllable switch tube K2N and a heating element HN connected in series. The number of heating branches can be N. Figure 2-4 The controller shown is only taken as an example with two heating branches.

[0024] like Figure 2 As shown, in one embodiment, each heating branch further includes at least one protection switch tube K1N, which is connected in series in the heating branch; each heating branch is connected in parallel and electrically connected to the input power supply. Figure 3 As shown in / 4, the controller also includes at least one protection switch tube K1. At least two heating branches among the N heating branches are connected in parallel and then connected in series with the protection switch tube. The series-connected protection switch tube K1 and the heating branch are electrically connected to the input power supply. The heating branches of the other roads can be as follows Figure 5 Directly connected to the input power supply as shown, or Figure 2 The heating branch shown is electrically connected to the input power supply through other protection switch tubes; of course, N heating branches can also be connected in parallel and then connected in series with the protection switch tube K1, and the series protection switch tube K1 and heating branch are electrically connected to the input power supply.

[0025] In order to realize the control of the multi-channel controllable switch tubes in the above controller, the embodiment of the present application provides a control method, such as Figure 6 As shown, the control method includes the following steps:

[0026] S11: Obtain a target demand parameter Ps of the load, such as a target demand power or a target demand current;

[0027] S12: Obtaining an actual operating parameter Pr of the controller, such as actual operating power or actual operating current;

[0028] S13: Time-sharing control of controllable switch tubes: at least calculate the duty cycle of the controllable switch tubes K21 / K22...K2N according to the target demand parameter Ps and the actual operation parameter Pr, and control the working state of the controllable switch tubes by time-sharing driving. The driving signal of the controllable switch tube is a PWM signal. There are two common ways to control the controllable switch tubes of multiple load branches:

[0029] 1. Multiple load branches adopt synchronous PWM modulation. With this setting, the inrush current is large, which is the sum of the currents of multiple load branches, which is not friendly to the controller's devices.

[0030] 2. When several branches start PWM modulation first and the power is still insufficient, keep the PWM drive signal of the branch at the maximum duty cycle, and then start the PWM modulation of other branches. In this way, the load loss of the branch started first is large, and it is easy to drift or be damaged in the long run.

[0031] The present application adopts a time-sharing driving method to make the controllable switch tubes not open at the same time as much as possible, such as Figure 6 As shown, it is helpful to reduce the inrush current.

[0032] In one embodiment, the controller is an electric heating controller, the load is a heating element, the target demand parameter Ps is the target demand power, and the actual operating parameter Pr is the actual operating power; the electric heating controller includes N heating branches; the heating branch includes at least one controllable switch tube and at least one heating element, and the controllable switch tube and the heating element are connected in series; the controllable switch tube adopts PWM modulation control; the branch demand power Psn of each heating branch divides the total target demand power equally, that is, the branch demand power Psn of each branch is 1 / N of the target demand power Ps, and the PWM modulation time of each controllable switch tube is delayed by T / N (T is the modulation period) in turn, that is, the PWM modulation time of each controllable switch tube is delayed by 360° / N.

[0033] Specifically, combined with Figure 7 ,by Figure 4An electric heater with two heating branches and a protection switch tube K1 electrically connected to the low voltage end DC- of the input power supply Vdc is used as an example for explanation. In this embodiment, N=2; the PWM control signal for driving the controllable switch tube K21 is recorded as HPWM1, the PWM control signal for driving the controllable switch tube K22 is recorded as HPWM2, and the PWM control signal for driving the protection switch tube K1 is recorded as LDriver. In this embodiment, T / N=T / 2, HPWM1 and LHPWM2 of the controllable switch tubes K21 and K22 are turned on with the same duty cycle, and the modulation time of LHPWM1 and LHPWM2 is delayed by T / 2, that is, the delay is 180°. When the electric heater is working normally, the protection switch tube K11 is closed, that is, LDriver controls the protection switch tube K11 to be closed, Figure 7 In the example, a high level of the PWM signal indicates that the corresponding controllable switch tube / protection switch tube can be driven to close, and a low level indicates that the switch tube is disconnected.

[0034] Furthermore, in one embodiment, the branch operating power of each heating branch is calculated based on at least the branch current, the resistance value of the heating element and the duty cycle of the controllable switch tube of the heating branch. Assuming that the resistance value of the heating element is R, the input voltage Vdc connected to the controller is U, because the resistance value of the heating element is much larger than the resistance value of other components in the heating branch, therefore, ignoring the resistance of other components in the branch, the branch current of each heating branch I = U / R, and the branch operating power of each branch Prn = I*R*D = U 2 / R*D, D is the duty cycle of the controllable switch tube; in each heating branch, the duty cycle of the controllable switch tube is calculated at least according to the target demand parameter and the actual operation parameter, including the steps of: performing PI operation on the branch demand power Psn and the branch operation power Prn to obtain the duty cycle D of the controllable switch tube of the branch. The duty cycles of the controllable switches of other branches can be equal to the duty cycle of the branch, but the start time is delayed by 180° in sequence.

[0035] refer to Figure 7 When the target demand parameter Ps is small, the duty cycle of HPWM1 and LHPWM2 is below 50%. When the above-mentioned time-sharing control method is used, the branch currents of the two roads will not overlap, and the maximum inrush current of the controller is the current of the single heating branch, and at certain times, the inrush current of the controller is 0. When the target demand parameter Ps is large, the duty cycle of HPWM1 and LHPWM2 is greater than 50%. The inrush current of the controller is only the current of the single heating branch at certain times, and the inrush current is the sum of the two heating circuits at other times. Therefore, the use of a time-sharing control method can at least reduce the inrush current at certain times, and the branch current of each road is uniform, and the heating device is heated uniformly, which is beneficial to improve the life and stability of the controller. Of course, the divided resistance sampling method can also be used, such as Figure 3As shown, a sampling resistor Rsn is provided on each heating branch.

[0036] In addition, in one embodiment, a current acquisition trigger is performed at the middle point of the high level signal of the PWM control signal of the controllable switch tube of the heating branch; after the current acquisition trigger is performed, the current sampling signal of the heating branch is obtained. Figure 7 For example, the current collection point is at the middle point of the high level of the PWM control signal. The middle point of each PWM control signal will not overlap. Figure 4 As shown, a total sampling resistor Rs is set to sample the branch current I of each path, and the total sampling resistor Rs and the parallel-connected heating branches are connected in series between the input voltages.

[0037] Furthermore, considering the current sampling time Ts, the duty cycle of the controllable switch tube has configuration requirements. In order to satisfy the requirement that the branch currents of each path can be sampled through the total sampling resistor, the minimum duty cycle Dmin>Ts / T and the maximum duty cycle Dmax<(100%-Ts / T) are set, where T is the modulation period. In one embodiment, the duty cycle of the PWM control signal of the controllable switch tube is greater than or equal to 1% and less than or equal to 99%.

[0038] The present application also provides a controller, such as Figure 1 As shown, the controller includes N controllable switch tubes K21 / K22...K2N, the first ends of the N controllable switch tubes are electrically connected to each other, and the second ends of the controllable switch tubes can be electrically connected to the load, N is a positive integer and N≥2; the controller also includes a control unit 20, the control unit 20 is electrically connected to the control ends of the N controllable switch tubes, and referring to the embodiment of the above control method, the control unit 20 is at least used for:

[0039] Obtain target demand parameters of load L1;

[0040] Get the actual operating parameters of the controller;

[0041] The duty cycle of the controllable switch tube is calculated at least according to the target demand parameter and the actual operation parameter, and the working state of the controllable switch tube is controlled by a time-sharing driving method.

[0042] The main topology of the controller can also be Figure 2 As shown, the controller is an electric heating controller, the load includes heating elements H1 / H2...HN, and the electric heating controller includes N heating branches; the heating branches include at least one controllable switch tube and at least one heating element, and the controllable switch tube and the heating element are connected in series; the controller also includes N protection switch tubes K11 / K12...K1N, and the N protection switch tubes are respectively connected in series in the N heating branches, and the N heating branches can be electrically connected to the input power supply.

[0043] The main topology of the controller can also be Figure 3 As shown in / 4, the controller is an electric heating controller, which includes N heating branches; the heating branches include at least one controllable switch tube and at least one heating element, and the controllable switch tube and the heating element are connected in series; the controller also includes at least one protection switch tube K1, and the N heating branches are connected in parallel and then connected in series with the protection switch tube K1, and the series-connected protection switch tube and heating branch can be electrically connected to the input power supply.

[0044] In one embodiment, the target demand parameter is the target demand power, and the actual operation parameter is the actual operation power; the controller further includes a sampling unit, such as Figure 3 Rs1 / Rs2 and Figure 4 As shown in Rs, the sampling unit is electrically connected to the load (it can be directly electrically connected or indirectly electrically connected through a controllable switch tube / protection switch tube), the sampling unit is electrically connected to the control unit 20, the control unit 20 is also used to output a PWM control signal to control the controllable switch tube, the control unit 20 samples the current of the load at the middle point of the high level signal of the PWM control signal through the sampling unit, and calculates the actual operating power according to the sampled current; the branch demand power of each heating branch is 1 / N of the target demand power, and the PWM modulation time of each controllable switch tube is delayed by T / N in turn, where T is the modulation period; the duty cycle of the controllable switch tube is calculated at least according to the target demand parameter and the actual operating parameter, including the steps of: performing PI operation on the branch demand power and the branch operating power of a certain branch to obtain the duty cycle of the controllable switch tube.

[0045] In one embodiment, the sampling unit includes a total sampling resistor, and the total sampling resistor is connected in series with the parallel heating branch between the input power supply. Assuming that the current sampling time is Ts, in order to ensure that the current of each load branch can be sampled, the minimum value of the duty cycle of the controllable switch tube is set to be greater than Ts / T and the maximum value is less than (100%-Ts / T). For example, the duty cycle of the PWM control signal of the controllable switch tube can be set to be greater than or equal to 1% and less than or equal to 99%.

[0046] In such Figure 2-5 In the controller shown in the figure, which has multiple load branches and uses controllable switch tubes to output controller parameters, if the controllable switch tube fails, the controller will fail. In order to improve the reliability of the controller, the embodiment of the present application also provides a fault judgment method, which can judge the fault of the controller, such as Fig. 9As shown, the controller includes N load branches, each of which includes at least one controllable switch tube (K21 / K22... / K2N) and a load (H1 / H2... / HN). The controllable switch tube and the load are connected in series, and the N load branches are connected in parallel. After the parallel connection, the input power supply is connected. The controllable switch tube can be controlled by the above-mentioned time-sharing control method to achieve the control of the output parameters. Figure 8 As shown, the fault judgment method includes the following short circuit judgment steps:

[0047] Step S21: controlling some of the controllable switch tubes to close, and controlling the remaining controllable switch tubes to open, which is equivalent to controlling the controllable switch tubes of the M load branches to close, and controlling the controllable switch tubes of the remaining (NM) load branches to open; that is, it is expected that the M load branches will work and current will flow through the load branches, and the remaining (NM) load branches will not work and there will be no current in the load branches.

[0048] Step S22: obtaining a sampling signal, the sampling signal representing the total current of all load branches, which is equivalent to obtaining a sampling signal representing the total current flowing through N load branches; if the controllable switch tubes are not damaged, the total current is the sum of the currents of all load branches with M controllable switch tubes closed;

[0049] Step S23: Determine the magnitude of the sampling signal and a first preset value; the first preset value is determined according to the sum of the DC currents of the M loads when no fault occurs;

[0050] Step S24: if the sampling signal is greater than or equal to the first preset value, it is determined that at least one of the controllable switch tubes that are controlled to be disconnected has a short circuit fault; wherein M and N are both positive integers, and N≥2, 1≤M<N.

[0051] Take the controller as an on-board electric heater as an example, assuming that the input voltage of the on-board electric heater is Vdc, the heating element is a resistor, and its resistance is R, then the current of each load branch is Vdc / R, and the sampling signal corresponds to the total current of M load branches. If the sampling signal becomes larger, it means that the current of the sampling signal is greater than the total current of M load branches, then it is highly likely that at least one of the remaining (NM) load branches is also connected to the input voltage, and further it can be indicated that at least one of the controllable switch tubes of the load branch has a short circuit fault.

[0052] In one embodiment, the present application further provides a fault judgment method for judging whether there is an open circuit fault in a controllable switch tube, comprising the following open circuit judgment steps:

[0053] Determine the magnitude of the sampling signal and the second preset value, the sampling signal represents the total current of all load branches; the second preset value is determined according to the sum of the DC currents of the M loads of the controllable switch tubes that are controlled to be closed when no fault occurs;

[0054] If the sampling signal is less than or equal to the second preset value, it is determined that at least one controllable switch tube or a load in the load branch where the controlled closed controllable switch tube is located has an open circuit fault.

[0055] Furthermore, the heating element is a PTC resistor, and its standard resistance is assumed to be R. However, as the operating temperature changes, its resistance drifts: the higher the temperature, the greater the resistance; the standard current of each load branch Is = Vdc / R, and Is decreases as the temperature rises. Therefore, the coefficients Ks and Ko are set, the first preset value Iref1 = Ks*Is*M, and the second preset value Iref2 = Ko*Is*M, where Is is the standard current of each load branch, Ks is determined by the load resistance, the higher the temperature, the greater the load resistance and the smaller Ks; Ko is determined by the load resistance, the greater the load resistance, the smaller Ko; Ko and Ks can also take the same value, and their specific values ​​can be determined according to the circuit design and load characteristics, which are not limited in this application.

[0056] In another embodiment, if Fig.10 As shown, take two loads as an example, that is, N=2, M=1; assuming that the heating element is a resistive heating element, such as a heating film, etc., the resistance of the heating element may deviate due to production process / production batch and other reasons; in addition, as the heating element is used, its resistance may also deviate. Considering various deviations, assuming that the allowed deviation is less than V, the first preset value Iref1=Is*Ks1 and the second preset value Iref2=Is*Ko1 can be set, where Is is the standard current of each load branch, Ks1=2 / (1+V), Ko1=1 / (1+V), the allowable deviation percentage of the load resistance is less than V, Is=Vdc / R, R is the standard resistance of the heating element, and the percentage of the resistance of the heating element deviating from the standard resistance R is less than V. When V is larger, Ks1 is smaller, Ko1 is larger, and the coefficient is calculated according to the actual resistance change relationship and used in combination.

[0057] Further, taking the maximum allowable deviation percentage less than V, V = 33% as an example, that is, before the resistance of the heating element changes to R*(1+33%), the fault must be able to be identified; at this time, set Ks1 = 2 / (1+V) ≈ 1.5, Ko1 = 1 / (1+V) ≈ 0.75, and the current Ich of each load branch is related to the characteristic current Is and the percentage V: Is / (1+V) ≤ Ich (Ic1 / Ich2) ≤ Is. Considering that the worst deviation occurs in both branches (infinitely close to 33%), even if one load branch is controlled to be connected and the other is disconnected, but the input voltage is also connected due to the short-circuit fault of the controllable switch tube of this branch, the total current is large. =1.5*Is, so 1.5*Is can be set as the short-circuit judgment condition. How to ensure the reliability of fault judgment without affecting the normal operation of the controller? If the sampling signal representing the total current obtained when one control line is closed is greater than the first preset value in the worst case, it means that the other controllable switch tube that is controlled to be disconnected must have a fault. The short-circuit fault at V under the resistance deviation can be more detected. In other words, if one controllable switch tube is short-circuited, the worst case is that the two film resistors are (1+V)*R, current = Is*2 / (1+V), Ks = 2 / (1+V), so the coefficient Ks = 1.5 can meet the short-circuit judgment within <R+33%. Considering that the resistance deviation is less than V, the current Ich of each load branch ≥ Is / (1+V), so setting Ko1 = 0.75 can be used to judge the open circuit of the load branch, that is, when one controllable switch tube is open and the resistance deviation is V = 33%, the open circuit judgment coefficient Ko = 0.75. Fig.11 As shown in the control waveform, if the control protection switch tube K1 is turned on when the open circuit / short circuit fault is detected, the controllable switch tube K21 of the A-way load branch is closed, and the controllable switch tube K22 of the B-way load branch is turned off. In order to ensure that the protection switch tube K1 as the upper tube can be driven normally, after the short circuit fault is judged, the protection switch tube should also be controlled to be turned off, and the off time of the protection switch tube should be less than the minimum off time of the controllable switch tube to generate the bootstrap voltage of K11. Fig.12 As shown, if the protection switch tube is the lower tube, after the short-circuit fault is determined, there is no need to control the protection switch tube to disconnect.

[0058] Further, such as Figure 2As shown, if the controller further includes N protection switch tubes, and the N protection switch tubes are respectively connected in series in N load branches, the load branch can be electrically connected to the input power supply (such as DC+ / DC-); the short circuit judgment step and the open circuit judgment step also include: controlling the protection switch tube to be closed, specifically, controlling the N protection switch tubes to be closed, so that the fault of the controllable switch tube can be detected. In this embodiment, in order to detect the fault of the protection switch tube, the fault judgment method can be set to also include a protection switch tube fault detection step: controlling the N protection switch tubes to be disconnected, judging whether the sampling signal is greater than a third preset value, if the sampling signal is greater than or equal to the third preset value, it is judged that at least one protection switch tube has a short circuit fault; the sampling signal represents the total current of all load branches, the third preset value is 0 or a value slightly larger than 0, theoretically, if all protection switch tubes are disconnected, the total current of the load branch is 0, but if the total current is greater than 0, it means that at least one protection switch tube has a fault.

[0059] Similarly, if Figure 3 As shown in / 4 / 10, the controller includes a protection switch tube K1, which protects the load branch connected in parallel (such as Fig.10 The load branches A and B in the controllable switch are connected in series, and after the series connection, the protection switch tube and the load branch can be electrically connected to the input power supply; the short-circuit judgment step and the open-circuit judgment step also include: controlling the protection switch tube to close; the fault judgment method also includes a protection switch tube fault detection step: controlling the protection switch tube to open, judging whether the sampling signal is greater than a third preset value, if the sampling signal is greater than or equal to the third preset value, it is judged that at least the controllable switch tube has a short-circuit fault; the third preset value is greater than or equal to 0, and optionally, the third preset value is 0 or a value slightly larger than 0, and the protection switch tube can be used as both an upper tube and a lower tube.

[0060] Based on the above fault judgment method, the present application also provides a controller with a fault judgment function. The technical effects and implementation principles of the two can refer to each other. Fig. 9 As shown, at least N load branches are included, each load branch includes at least one controllable switch tube and a load, after the controllable switch tube and the load of each load branch are connected in series, the N load branches are connected in parallel; the controller also includes a sampling unit 30 and a control unit 20, an input end of the control unit 20 is electrically connected to the sampling unit 30, and an output end of the control unit 20 is electrically connected to the control end of the controllable switch tube, specifically, different output ends can be electrically connected to different controllable switch tubes, and the control unit is preset with a first preset value;

[0061] The sampling unit 30 is capable of sampling the total current of the N load branches and outputting a sampling signal representing the total current to the control unit;

[0062] The control unit is at least used to perform the following short circuit fault judgment steps:

[0063] Control the controllable switch tube of the load branch of the M path to be closed, and control the controllable switch tube of the load branch of the (NM) path to be opened;

[0064] Get the sampling signal;

[0065] Determine the magnitude of the sampling signal and the first preset value;

[0066] If the sampling signal is greater than or equal to the first preset value, it is determined that at least one of the controllable switch tubes that are controlled to be disconnected has a short circuit fault;

[0067] Wherein, M and N are both positive integers, and N≥2, 1≤M<N.

[0068] In another embodiment, the control unit is also pre-set with a second preset value, and the controller is further configured to perform the following open circuit fault determination steps:

[0069] Determine the magnitude of the sampling signal and a second preset value;

[0070] If the sampling signal is less than or equal to the second preset value, it is determined that at least one controllable switch tube or a load in the load branch where the controlled closed controllable switch tube is located has an open circuit fault.

[0071] Furthermore, the controller also includes N protection switch tubes, and its main topology is as follows: Figure 2 As shown, N protection switch tubes are respectively connected in series in N load branches, and the output end of the control unit is also electrically connected to the control end of the protection switch tube. At this time, if the control logic of the protection switch tube is the same, one output end can be used to be electrically connected to the control end of the N protection switch tubes;

[0072] The short-circuit fault judgment step and the open-circuit fault judgment step further include: controlling the protection switch tube to close;

[0073] The control unit 20 can also be used to perform the following protection switch failure judgment steps:

[0074] Control N protection switch tubes to disconnect, and determine whether the sampling signal is greater than a third preset value. If the sampling signal is greater than or equal to the third preset value, it is determined that at least one of the controllable switch tubes has a short circuit fault; the third preset value is greater than or equal to 0, and can be selected as a value slightly greater than 0, such as 0.2.

[0075] like Fig.10In another embodiment, the controller includes a protection switch tube K1, which is connected in series with the load branch after being connected in parallel. After being connected in series, the protection switch tube and the load branch can be electrically connected to the input power supply, and the output end of the control unit 20 is also electrically connected to the control end of the protection switch tube;

[0076] The short-circuit fault judgment step and the open-circuit fault judgment step also include: controlling the protection switch tube to close;

[0077] The control unit 20 is also used to perform the following protection switch failure judgment steps:

[0078] The protection switch tube is controlled to be disconnected, and it is determined whether the sampling signal is greater than a third preset value. If the sampling signal is greater than or equal to the third preset value, it is determined that at least the controllable switch tube K has a short circuit fault; the third preset value is greater than or equal to 0.

[0079] In order to compare the sampling signal with the first / second / third preset value, the control unit may also be provided with a comparison circuit.

[0080] refer to Figure 4 In the main topology shown in the topology, the protection switch tube is the lower tube, that is, the first end of the protection switch tube K1 is electrically connected to one end of the load branch, and the other end of the load branch can be electrically connected to the positive end DC+ of the input power supply, the second end of the protection switch tube is electrically connected to one end of the sampling unit, and the other end of the sampling unit can be electrically connected to the negative end DC- of the input power supply.

[0081] Alternatively, refer to Fig.10 As shown, the protection switch tube is an upper tube, that is, the first end of the protection switch tube K1 can be electrically connected to the positive end DC+ of the input power supply, the second end of the protection switch tube K1 is electrically connected to one end of the load branch, the other end of the load branch is electrically connected to one end of the sampling unit 30, and the other end of the sampling unit 30 can be electrically connected to the negative end DC- of the input power supply; the control unit 20 is also used to control the protection switch tube K1 to disconnect after a short-circuit fault is determined, and the disconnection time of the protection switch tube is less than the minimum off time of the controllable switch tube K2N.

[0082] In one embodiment, the first preset value Iref1 = Ks*Is*M, and the second preset value Iref2 = Ko*Is*M, wherein Is is the standard current of each load branch, Ks is determined by the load resistance, and the larger the load resistance, the smaller Ks; Ko is determined by the load resistance, and the larger the load resistance, the smaller Ko.

[0083] In another embodiment, N=2, M=1; the first preset value Iref1=Is*Ks1, the second preset value Iref2=Is*Ko1, wherein Is is the standard current of each load branch, Ks1=2 / (1+V), Ko1=1 / (1+V), and the allowable deviation percentage of the load resistance is less than V; the controllable switch tube adopts PWM modulation control, and the control unit 20 performs total current sampling at the midpoint of the high-level signal of the PWM control signal of the controllable switch tube through the sampling unit 30.

[0084] It should be noted that electrical connection includes direct electrical connection and indirect electrical connection. The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the present invention can still be modified or replaced by equivalents, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A fault diagnosis method, capable of diagnosing a fault of a controller, characterized in that: The controller comprises N load branches, each of which comprises at least one controllable switch tube and a load, wherein the controllable switch tube and the load are connected in series, and the N load branches are connected in parallel; The fault judgment method includes a short circuit judgment step and / or an open circuit judgment step; The short circuit determination step comprises: Control the controllable switch tube of the load branch of the M path to be closed, and control the controllable switch tube of the load branch of the (NM) path to be opened; Acquiring a sampling signal representing a total current flowing through the N load branches; Determine the magnitude of the sampling signal and a first preset value; If the sampling signal is greater than or equal to the first preset value, it is determined that at least one of the controllable switch tubes that are controlled to be disconnected has a short circuit fault; The open circuit determination step comprises: Determine the magnitude of the sampling signal and a second preset value; If the sampling signal is less than or equal to the second preset value, it is determined that at least one controllable switch tube or a load in the load branch where the controlled closed controllable switch tube is located has an open circuit fault; Wherein, M and N are both positive integers, and N≥2, 1≤M<N.

2. The fault diagnosis method according to claim 1, characterized in that: The first preset value Iref1 = Ks*Is*M, and the second preset value Iref2 = Ko*Is*M, wherein Is is the standard current of each load branch, Ks is determined by the load resistance, and the larger the load resistance, the smaller Ks; Ko is determined by the load resistance, and the larger the load resistance, the smaller Ko.

3. The fault diagnosis method according to claim 1, characterized in that: N=2, M=1; the first preset value Iref1=Is*Ks1, the second preset value Iref2=Is*Ko1, wherein Is is the standard current of each load branch, Ks1=2 / (1+V), Ko1=1 / (1+V), and the allowable deviation percentage of the load resistance is less than V.

4. The fault judgment method according to any one of claims 1 to 3, characterized in that: The controller further includes N protection switch tubes, the N protection switch tubes are respectively connected in series in the N load branches, and the load branches can be electrically connected to the input power supply; the short circuit judgment step and the open circuit judgment step also include: controlling the protection switch tube to close; the fault judgment method also includes a protection switch tube fault detection step: controlling the N protection switch tubes to open, judging whether the sampling signal is greater than a third preset value, and if the sampling signal is greater than or equal to the third preset value, judging that at least one of the controllable switch tubes has a short circuit fault; Alternatively, the controller includes a protection switch tube, the protection switch tube is connected in series with the load branch after being connected in parallel, and the protection switch tube and the load branch after being connected in series can be electrically connected to the input power supply; the short circuit judgment step and the open circuit judgment step also include: controlling the protection switch tube to be closed; the fault judgment method also includes a protection switch tube fault detection step: controlling the protection switch tube to be disconnected, judging whether the sampling signal is greater than a third preset value, and if the sampling signal is greater than or equal to the third preset value, it is judged that at least the controllable switch tube has a short circuit fault; The third preset value is greater than or equal to 0.

5. A controller, characterized in that: At least N load branches are included, and the load branches include at least one controllable switch tube and a load, the controllable switch tube and the load are connected in series, and the N load branches are connected in parallel; the controller also includes a sampling unit and a control unit, an input end of the control unit is electrically connected to the sampling unit, an output end of the control unit is electrically connected to the control end of the controllable switch tube, and the control unit is preset with a first preset value; The sampling unit is capable of sampling the total current of the N load branches and outputting a sampling signal representing the total current to the control unit; The control unit is at least used to perform the following short circuit fault judgment steps: Control the controllable switch tube of the load branch of the M path to be closed, and control the controllable switch tube of the load branch of the (NM) path to be opened; Acquiring the sampling signal; Determine the magnitude of the sampling signal and the first preset value; If the sampling signal is greater than or equal to the first preset value, it is determined that at least one of the controllable switch tubes that are controlled to be disconnected has a short circuit fault; Wherein, M and N are both positive integers, and N≥2, 1≤M<N.

6. The controller according to claim 5, characterized in that: The control unit is preset with a second preset value, and the controller is also used to perform the following open circuit fault judgment steps: Determine the magnitude of the sampling signal and a second preset value; If the sampling signal is less than or equal to the second preset value, it is determined that at least one controllable switch tube or a load in the load branch where the controlled closed controllable switch tube is located has an open circuit fault.

7. The controller according to claim 6, characterized in that: The controller further includes N protection switch tubes, the N protection switch tubes are respectively connected in series in the N load branches, and the output end of the control unit is also electrically connected to the control end of the protection switch tube; The short-circuit fault judgment step and the open-circuit fault judgment step further include: controlling the protection switch tube to close; The control unit is also used to perform the following protection switch tube fault judgment steps: Control N of the protection switch tubes to disconnect, determine whether the sampling signal is greater than a third preset value, and if the sampling signal is greater than or equal to the third preset value, determine that at least one of the protection switch tubes has a short circuit fault; the third preset value is greater than or equal to 0.

8. The controller according to claim 6, characterized in that: The controller includes a protection switch tube, which is connected in series with the load branch after being connected in parallel. After the series connection, the protection switch tube and the load branch can be electrically connected to the input power supply, and the output end of the control unit is also electrically connected to the control end of the protection switch tube; The short-circuit fault judgment step and the open-circuit fault judgment step further include: controlling the protection switch tube to close; The control unit is also used to perform the following protection switch tube fault judgment steps: Control the protection switch tube to disconnect, determine whether the sampling signal is greater than a third preset value, and if the sampling signal is greater than or equal to the third preset value, determine that at least the protection switch tube has a short circuit fault; the third preset value is greater than or equal to 0.

9. The controller according to claim 8, characterized in that: The first end of the protection switch tube is electrically connected to one end of the load branch, and the other end of the load branch can be electrically connected to the positive end of the input power supply. The second end of the protection switch tube is electrically connected to one end of the sampling unit, and the other end of the sampling unit can be electrically connected to the negative end of the input power supply. or, The first end of the protection switch tube can be electrically connected to the positive end of the input power supply, the second end of the protection switch tube is electrically connected to one end of the load branch, the other end of the load branch is electrically connected to one end of the sampling unit, and the other end of the sampling unit can be electrically connected to the negative end of the input power supply; the control unit is also used to control the protection switch tube to disconnect after a short-circuit fault is determined, and the disconnection time of the protection switch tube is less than the minimum shutdown time of the controllable switch tube.

10. The controller according to any one of claims 6 to 9, characterized in that: The first preset value Iref1 = Ks*Is*M, and the second preset value Iref2 = Ko*Is*M, wherein Is is the standard current of each load branch, Ks is determined by the load resistance, and the larger the load resistance, the smaller Ks; Ko is determined by the load resistance, and the larger the load resistance, the smaller Ko.

11. The controller according to any one of claims 6 to 9, characterized in that: N=2, M=1; the first preset value Iref1=Is*Ks1, the second preset value Iref2=Is*Ko1, wherein Is is the standard current of each load branch, Ks1=2 / (1+V), Ko1=1 / (1+V), and the allowable deviation percentage of the load resistance is less than V; the controllable switch tube adopts PWM modulation control, and the control unit samples the total current at the midpoint of the high-level signal of the PWM control signal of the controllable switch tube through the sampling unit.

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