Power tube fault detection and positioning circuit, photovoltaic power generation system and air conditioning system

Abstract

The application discloses a power tube fault detection and positioning circuit, a photovoltaic power generation system and an air conditioning system. The power tube fault detection and positioning circuit comprises at least one driving optocoupler which is arranged in one-to-one matching mode with a power tube, and the driving optocoupler can send a low-level signal when the power tube is abnormal. The power tube fault detection and positioning circuit further comprises a fault detection circuit which is connected to the at least one driving optocoupler respectively and can send a fault signal to a master control chip when the power tube is abnormal; and a fault positioning circuit which is arranged in one-to-one matching mode with the driving optocoupler and can trigger the matched fault positioning circuit when the power tube is abnormal. Compared with the prior art, the application can indicate the specific abnormal power tube through a light-emitting diode when the power tube is abnormal, so that the rapid positioning of the fault is realized, and the troubleshooting and maintenance are facilitated.

Description

Technical Field

[0001] This invention relates to a photovoltaic-storage-air conditioning system, and in particular to a power transistor fault detection and location circuit, a photovoltaic power generation system, and an air conditioning system. Background Technology

[0002] In existing photovoltaic (storage) air conditioning system platforms, as shown in the attached Figure 1 As shown, the photovoltaic cell voltage is connected to the high-voltage DC bus via a DC / DC converter, and then connected to the power grid via a DC / AC converter. The DC / AC converter typically uses a full-bridge topology, such as... Figure 2 As shown, to prevent simultaneous short circuits in the main power transistors of a single branch's upper and lower arms, a drive optocoupler with DESAT voltage detection is selected. When the drive optocoupler detects that the voltage at the DESAT pin exceeds the limit, it blocks the drive pulses of the main power transistors to prevent transistor failure. The full-bridge topology has four main power transistors, and four drive optocouplers are selected. Due to the limitations of the main control chip's on-chip resources, the traditional approach is to aggregate the fault signals from the four drive optocouplers and send them to the main control chip. When one main power transistor triggers DESAT protection, the main control chip can block all drive pulses. The drawback is that when one main power transistor triggers DESAT voltage abnormality protection, it is impossible to distinguish which main power transistor is abnormally protected, making troubleshooting and repair difficult.

[0003] Therefore, how to design a power transistor fault detection and location circuit, photovoltaic power generation system, and air conditioning system that can accurately locate abnormal power transistors is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0004] In response to the problem in existing technologies that cannot distinguish which power transistor is faulty when triggering DESAT voltage abnormality protection for a power transistor, this invention proposes a power transistor fault detection and location circuit, a photovoltaic power generation system, and an air conditioning system.

[0005] The technical solution of this invention is to propose a power transistor fault detection and location circuit, including at least one drive optocoupler matched one-to-one with the power transistor, wherein the drive optocoupler can emit a low-level signal when the power transistor is abnormal, and further comprising:

[0006] A fault detection circuit is connected to at least one of the driving optocouplers and can send a fault signal to the main control chip when the power transistor is abnormal.

[0007] The fault location circuit is matched one-to-one with the drive optocoupler, and can trigger the matched fault location circuit when the power transistor is abnormal.

[0008] Furthermore, the fault detection circuit employs an AND gate, and the input of the AND gate is simultaneously connected to the output of at least one of the driving optocouplers, while the output is connected to the main control chip.

[0009] Furthermore, the fault location circuit includes a control circuit that is matched one-to-one with the drive optocoupler and a display circuit that is matched one-to-one with the control circuit, and when the power transistor is abnormal, the display circuit that is matched with it emits light.

[0010] Furthermore, the control circuit employs a NOT gate, and the input terminal of the NOT gate is connected to the output terminal of a matching drive optocoupler, while the output terminal is connected to the display circuit.

[0011] Furthermore, when the power transistor malfunctions, the matching control circuit sends a high-level signal to the display circuit;

[0012] When the power transistor is functioning normally, the matching control circuit sends a low-level signal to the display circuit.

[0013] Furthermore, the display circuit includes: a resistor R1, a transistor S1, and a light-emitting diode LED1;

[0014] One end of the resistor R1 is connected to the power supply, and the other end is connected to the collector of the transistor S1. The base of the transistor S1 is connected to the output terminal of the control circuit, and the emitter is connected in series with the light-emitting diode LED1 and then grounded.

[0015] Furthermore, the display circuit includes: resistor R1, transistor S1, transistor S2, and light-emitting diode LED1;

[0016] One end of the resistor R1 is connected to the power supply, and the other end is connected to the collector of the transistor S1 and the collector of the transistor S2 respectively. The emitter of the transistor S1 is connected to the base of the transistor S2, and the emitter of the transistor S2 is connected in series with the light-emitting diode LED1 and then grounded.

[0017] The present invention also proposes a photovoltaic power generation system, including a DC / DC conversion circuit, a bus capacitor, a DC / AC conversion circuit, and a power grid connected in sequence with photovoltaic cells. The DC / AC conversion circuit uses the above-mentioned fault detection and location circuit to detect faults in the power transistors.

[0018] Furthermore, the DC / AC conversion circuit adopts a full-bridge circuit, which includes power transistors Q1 and Q2 for forming the first bridge arm, and power transistors Q3 and Q4 for forming the second bridge arm, and each of the power transistors Q1, Q2, Q3 and Q4 is connected to a driving optocoupler.

[0019] The present invention also proposes an air conditioning system having the aforementioned photovoltaic power supply system.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] When a power transistor malfunctions, the present invention can send a fault signal to the main control chip through a fault detection circuit, enabling the main control chip to quickly block the drive pulses of all power transistors and prevent further damage to the circuit. In addition, the present invention also has a fault location circuit, which can locate the specific malfunctioning power transistor through an LED when a power transistor malfunctions, so as to quickly locate the fault and carry out troubleshooting and repair. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the topology of a photovoltaic power generation system;

[0024] Figure 2 This is a schematic diagram of the topology of a DC / AC conversion circuit;

[0025] Figure 3 The protection principle diagram for driving the optocoupler;

[0026] Figure 4 This is a schematic diagram of the protection principle when the power transistor malfunctions in a traditional solution.

[0027] Figure 5 This is a schematic diagram of the topology of the power transistor fault detection and location circuit of the present invention. Detailed Implementation

[0028] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0029] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0030] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0031] Anomaly detection of the power transistor is typically performed by driving an optocoupler. When the optocoupler detects that the voltage on the DESAT pin exceeds a limit, it will send a low-level signal. Please refer to [link / reference]. Figure 4 For DC / AC conversion circuits, the traditional approach is to set up four drive optocouplers, each used to detect the status of four power transistors. The signals from the four drive optocouplers are then combined and connected to the main control chip. When the output level of one of the drive optocouplers is low, it will pull the level FO output to the main control chip low. Although this method can determine whether a power transistor is malfunctioning and execute corresponding protection actions through the main control chip, it cannot identify the specific malfunctioning power transistor, making it inconvenient for troubleshooting and repair.

[0032] In response, this invention proposes a power transistor fault detection and location circuit, which includes at least one drive optocoupler matched one-to-one with the power transistor, and a fault detection circuit and a fault location circuit connected to the drive optocoupler.

[0033] In DC / AC conversion circuits, multiple power transistors are often used. In this invention, each power transistor is connected to a driver optocoupler to determine if it is malfunctioning. Specifically, when a power transistor malfunctions, the connected driver optocoupler will emit a low-level signal. (See [link to relevant documentation]). Figure 3 The driving optocoupler selected in this invention is a driving optocoupler with DESAT voltage detection function. When the driving optocoupler detects that the voltage of the DESAT pin exceeds the limit, it will send a low-level signal to remind the main control chip power transistor to be abnormal.

[0034] The input of the fault detection circuit is connected to the output of multiple drive optocouplers at the same time to collect the output signals of multiple drive optocouplers. Similar to the traditional setup, when there is a low-level signal in a drive optocoupler, the fault detection circuit will output a low-level signal to the main control chip regardless of whether the output signals of other drive optocouplers are high or low, so as to remind the main control chip that the power transistor has malfunctioned, so that the main control chip can perform protection actions.

[0035] Multiple fault location circuits are configured, with the number of fault detection circuits matching the number of power transistors. Each fault detection circuit is individually matched to a power transistor to achieve the fault location function. The fault location circuit also has a display function, which is triggered when a power transistor malfunctions, alerting the user to the abnormality.

[0036] It should be noted that the power transistor fault detection and location circuit described in this invention is mainly designed for DC / AC conversion circuits, which have four drive optocouplers. The subsequent fault detection circuit and fault location circuit are set to match the number of drive optocouplers. However, the application of this invention is not limited to DC / AC conversion circuits. When applied to power transistor abnormality detection in other circuits, the number of drive optocouplers and fault location circuits can be adjusted accordingly, and they can be set to at least one.

[0037] The present invention, through the setting of fault detection circuit and fault location circuit, can accurately determine whether there is a power transistor malfunction in the DC / AC conversion circuit, thereby executing the protection strategy and accurately identifying the malfunctioning power transistor, which facilitates the user's maintenance actions.

[0038] Specifically, the fault detection circuit proposed in this invention is composed of AND gates, and the input of the AND gate is connected to the output of at least one driving optocoupler, and the output is connected to the main control chip.

[0039] Please see Figure 5 This is a topology diagram of the power transistor fault detection and location circuit when the present invention is applied to a DC / AC conversion circuit. The DC / AC conversion circuit uses a full-bridge circuit with four power transistors, each connected to a driver optocoupler. Figure 5 Signals FO1, FO2, FO3, and FO4 are the output signals of the four drive optocouplers. When the output signal of the drive optocoupler is low, it indicates that the power transistor connected to it is abnormal.

[0040] The fault detection circuit is Figure 5 The AND gate in the middle has its input terminal connected to the output terminal of four driving optocouplers to acquire signals FO1, FO2, FO3 and FO4. At the same time, the output terminal of the AND gate is connected to the main control chip to output the combined signal FO to the main control chip.

[0041] Since the AND gate's operation logic is (AB), as long as any one of the signals FO1, FO2, FO3, and FO4 is low, the AND gate's output signal FO will output a low-level signal. In this invention, the low-level signal is used as a fault signal. When the main control chip detects this fault signal, it will block all drive pulses, turn off all power transistors, and report a circuit fault to avoid the problem of power transistors exploding.

[0042] Furthermore, the fault location circuit proposed in this invention includes a control circuit that is matched one-to-one with the driving optocoupler and a display circuit that is matched one-to-one with the control circuit. The display circuit is used to emit light to alert the user of the abnormal power transistor, and the control circuit is used to send a control signal to the display circuit to turn on the display circuit and emit light.

[0043] The control circuit uses a NOT gate, which can output a signal opposite to its input signal. For example, when the NOT gate receives a low-level signal, the control circuit can output a high-level signal, and vice versa. In this invention, the input terminal of the NOT gate is connected to the output terminal of the driving optocoupler, and the output terminal is connected to the display circuit, so that when the power transistor is abnormal and the driving optocoupler outputs a low-level signal, it can output a high-level signal to the display circuit, thereby turning on the display circuit.

[0044] The specific working logic of its control circuit is as follows: when the power transistor is abnormal, the matching control circuit sends a high-level signal to the display circuit;

[0045] When the power transistor is functioning normally, the matching control circuit sends a low-level signal to the display circuit.

[0046] It should be noted that since the driving optocoupler is matched with the power transistor one by one, and the control circuit is matched with the driving optocoupler one by one, each power transistor is actually matched with a corresponding control circuit. The control circuit matched with it mentioned above is the control circuit matched with the power transistor.

[0047] Please see Figure 5 For the DC / AC circuit, which has four power transistors, the present invention provides four driving optocouplers and four control circuits. The four control circuits are composed of NOT gate U1, NOT gate U2, NOT gate U3 and NOT gate U4, respectively, and are used to receive signals FO1, FO2, FO3 and FO4 output by the four driving optocouplers, and output opposite signals to the display circuit.

[0048] For NOT gate U1, when signal FO1 is a high-level signal, it will output a low-level signal to the display circuit; conversely, when signal FO1 is a low-level signal, it will output a high-level signal to the display circuit.

[0049] For NOT gate U2, when signal FO2 is high, it will output a low-level signal to the display circuit; conversely, when signal FO2 is low, it will output a high-level signal to the display circuit.

[0050] For NOT gate U3, when signal FO3 is a high-level signal, it will output a low-level signal to the display circuit; conversely, when signal FO3 is a low-level signal, it will output a high-level signal to the display circuit.

[0051] For NOT gate U4, when signal FO4 is high, it will output a low-level signal to the display circuit; conversely, when signal FO4 is low, it will output a high-level signal to the display circuit.

[0052] Furthermore, in one embodiment of the present invention, the display circuit includes: a resistor R1, a transistor S1, and a light-emitting diode LED1;

[0053] In this circuit, one end of resistor R1 is connected to the power supply, and the other end is connected to the collector of transistor S1. The base of transistor S1 is connected to the output of the control circuit, and the emitter is connected in series with LED1 and then grounded.

[0054] Since the control circuit is connected to the base of transistor S1 and the emitter of transistor S1 is grounded, the conduction state of transistor S1 can be determined by the level output of the control circuit. When the control circuit outputs a high-level signal, transistor S1 conducts, and LED1 lights up to remind the user that the power transistor connected to it is malfunctioning.

[0055] In a preferred embodiment of the present invention, the display circuit includes: a resistor R1, a transistor S1, a transistor S2, and a light-emitting diode LED1;

[0056] In this circuit, one end of resistor R1 is connected to the power supply, and the other end is connected to the collector of transistor S1 and the collector of transistor S2 respectively. The emitter of transistor S1 is connected to the base of transistor S2, and the emitter of transistor S2 is connected in series with LED1 and then grounded.

[0057] Compared to the connection method in the previous embodiment, this connection method adds a transistor S2 for control. It uses transistor S2 to increase the current output to the light-emitting diode LED1, thus avoiding the problem of insufficient brightness of the light-emitting diode LED1.

[0058] Its working principle is as follows: when the control circuit outputs a high-level signal, the base of transistor S1 receives the high-level signal and is in the conducting state. At the same time, it pulls up the level of the base of transistor S2, so that transistor S2 is turned on. At this time, the power supply supplies power to LED1 through transistors S1 and S2, so that LED1 lights up.

[0059] When the control circuit outputs a low-level signal, the base of transistor S1 receives the low-level signal and is in the cut-off state. At this time, the emitter of transistor S1 sends a low-level signal to the base of transistor S2, causing transistor S2 to be cut off. At this time, transistors S1 and S2 are cut off at the same time, and LED1 does not light up.

[0060] Please see Figure 5 For DC / AC circuits, this invention provides four display circuits: a first display circuit consisting of resistor R1, transistor S1, transistor S2, and LED1; a second display circuit consisting of resistor R2, transistor S3, transistor S4, and LED2; a third display circuit consisting of resistor R3, transistor S5, transistor S6, and LED3; and a fourth display circuit consisting of resistor R4, transistor S7, transistor S8, and LED4. In this invention, the abnormal power transistor can be determined based on the specific display circuit that emits light.

[0061] When power transistor Q1 is connected to the first display circuit, power transistor Q2 to the second display circuit, power transistor Q3 to the third display circuit, and power transistor Q4 to the fourth display circuit, if LED1 lights up, it indicates that power transistor Q1 is faulty; if LED2 lights up, it indicates that power transistor Q2 is faulty; if LED3 lights up, it indicates that power transistor Q3 is faulty; and if LED4 lights up, it indicates that power transistor Q4 is faulty. By setting these parameters, the faulty power transistor can be accurately identified, facilitating troubleshooting and repair.

[0062] Please see Figure 1 The present invention also proposes a photovoltaic power generation system, which includes a DC / DC conversion circuit, a bus capacitor, a DC / AC conversion circuit, and a power grid connected in sequence to the photovoltaic cells. The DC / AC conversion circuit uses the aforementioned fault detection and location circuit to detect faults in the power transistors within it.

[0063] Please see Figure 2 The DC / AC conversion circuit proposed in this invention adopts a full-bridge circuit, which includes power transistors Q1 and Q2 for forming the first bridge arm, and power transistors Q3 and Q4 for forming the second bridge arm. Power transistors Q1, Q2, Q3, and Q4 are all connected to a driving optocoupler for detecting abnormal states of the power transistors.

[0064] The abnormal state is generally as follows: the power transistors in the same bridge arm are turned on simultaneously, causing the DC / AC conversion circuit to be open. For example, when power transistors Q1 and Q2 are turned on at the same time, the first bridge arm is equivalent to a wire, which will short-circuit the subsequent circuit. This will cause the voltage on power transistors Q1 and Q2 to rise rapidly. The driver optocoupler is connected to power transistors Q1 and Q2. When a short circuit occurs, the voltage on power transistors Q1 and Q2 exceeds the voltage limit of the DESAT pin of the driver optocoupler. At this time, the driver optocoupler will send a low-level signal to the main control chip, thereby reminding the main control chip that there is a power transistor abnormality and that the driver pulse of the power transistor needs to be blocked to cut off the power transistor and avoid the problem of transistor failure.

[0065] After the photovoltaic power generation system adopts the power transistor fault detection and location circuit proposed in this invention, it can not only detect the occurrence of faults and provide timely protection, but also accurately identify the specific faulty power transistor, which facilitates maintenance.

[0066] The present invention also proposes an air conditioning system having the aforementioned photovoltaic power generation system.

[0067] Compared with the prior art, the present invention can send a fault signal to the main control chip through the fault detection circuit when the power transistor is abnormal, so that the main control chip can quickly block the drive pulses of all power transistors to avoid further damage to the circuit. In addition, the present invention can also locate the specific abnormal power transistor through the light-emitting diode when the power transistor is abnormal, so as to achieve rapid location and troubleshooting and repair.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power transistor fault detection and location circuit, comprising at least one drive optocoupler matched one-to-one with a power transistor, wherein the drive optocoupler can emit a low-level signal when the power transistor malfunctions, characterized in that, Also includes: A fault detection circuit is connected to at least one of the driving optocouplers and can send a fault signal to the main control chip when the power transistor is abnormal. The fault location circuit is matched one-to-one with the drive optocoupler, and can trigger the matched fault location circuit when the power tube is abnormal. The fault detection circuit uses an AND gate, and the input of the AND gate is simultaneously connected to the output of at least one of the driving optocouplers, and the output is connected to the main control chip. The fault location circuit includes a control circuit that is matched one-to-one with the drive optocoupler and a display circuit that is matched one-to-one with the control circuit. When the power transistor is abnormal, the display circuit matched with it emits light. The control circuit uses a NOT gate, and the input of the NOT gate is connected to the output of a matching drive optocoupler, and the output is connected to the display circuit.

2. The power transistor fault detection and location circuit according to claim 1, characterized in that, When the power transistor malfunctions, the matching control circuit sends a high-level signal to the display circuit. When the power transistor is functioning normally, the matching control circuit sends a low-level signal to the display circuit.

3. The power transistor fault detection and location circuit according to claim 1, characterized in that, The display circuit includes: resistor R1, transistor S1, and light-emitting diode LED1; One end of the resistor R1 is connected to the power supply, and the other end is connected to the collector of the transistor S1. The base of the transistor S1 is connected to the output terminal of the control circuit, and the emitter is connected in series with the light-emitting diode LED1 and then grounded.

4. The power transistor fault detection and location circuit according to claim 1, characterized in that, The display circuit includes: resistor R1, transistor S1, transistor S2, and light-emitting diode LED1; One end of the resistor R1 is connected to the power supply, and the other end is connected to the collector of the transistor S1 and the collector of the transistor S2 respectively. The emitter of the transistor S1 is connected to the base of the transistor S2, and the emitter of the transistor S2 is connected in series with the light-emitting diode LED1 and then grounded.

5. A photovoltaic power generation system, comprising a DC / DC conversion circuit, a bus capacitor, a DC / AC conversion circuit, and a power grid connected in sequence to photovoltaic cells, characterized in that, The DC / AC conversion circuit uses the fault detection and location circuit as described in any one of claims 1 to 4 to detect faults in the power transistor.

6. The photovoltaic power generation system according to claim 5, characterized in that, The DC / AC conversion circuit adopts a full-bridge circuit, which includes power transistors Q1 and Q2 for forming the first bridge arm, and power transistors Q3 and Q4 for forming the second bridge arm. Each of the power transistors Q1, Q2, Q3, and Q4 is connected to a driving optocoupler.

7. An air conditioning system, characterized in that, The air conditioning system has a photovoltaic power generation system as described in any one of claims 5 to 6.

Images