MOSFET device on-resistance measuring circuit and health monitoring method

Abstract

The invention relates to the field of MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) devices, and discloses an MOSFET device on-resistance measuring circuit and a health monitoring method. The MOSFET device on-resistance measuring circuit comprises a voltage measuring circuit and a current collecting circuit, the voltage measuring circuit comprises a first resistor R1, a first diode D1 and a first current source S1, when a to-be-measured MOSFET is conducted, current IS1 provided by the current source S1 sequentially flows through the first resistor R1, the first diode D1 and the to-be-measured MOSFET, and the current IS1 is connected with the first resistor R1, the first diode D1 and the to-be-measured MOSFET. Obtaining the break-over voltage of the MOSFET to be measured based on the break-over voltage of the first resistor R1, the break-over voltage of the first diode S1 and the voltage measured at the P1; the current acquisition circuit comprises a current sensor and is used for measuring current IDS at two ends of a drain electrode and a source electrode of the MOSFET to be measured; and obtaining the on-resistance of the to-be-tested MOSFET based on the on-voltage of the to-be-tested MOSFET and the current IDS at the two ends of the drain electrode and the source electrode.

Description

Technical Field

[0001] The present application relates to the field of MOSFET devices, and in particular to a MOSFET device on-resistance measurement circuit. Background Art

[0002] Switching power supplies are widely used in various engineering fields, and the reliability of power supply systems directly determines the reliability of various industrial products and application equipment. Metal oxide semiconductor field-effect transistors (MOSFETs), as the core components of switching power supply circuits, perform power conversion. They typically operate in a high-frequency switching mode, resulting in a failure rate as high as 31% in switching power supplies. The reliability of MOSFETs directly determines the reliability of the converters, so accurately monitoring the health of MOSFETs is crucial for system operation. Summary of the Invention

[0003] The present disclosure provides a MOSFET device on-resistance measurement circuit, including a voltage measurement circuit and a current acquisition circuit.

[0004] The voltage measurement circuit includes a first resistor R1, a first diode D1 and a first current source S1. The first current source S1 is used to provide current for the circuit. The first resistor R1 is connected to the first current source S1. The anode of the first diode D1 is connected to the first resistor R1. The cathode of the first diode D1 is connected to the drain of the MOSFET to be measured. The source of the MOSFET to be measured is grounded GND1. A measurement point P1 is set between the first diode D1 and the first resistor R1. When the MOSFET to be measured is turned on, the current I provided by the current source S1 S1 The current flows through the first resistor R1, the first diode D1 and the MOSFET to be tested in sequence, and the voltage measured at P1 is equal to the sum of the first resistor R1, the first current source S1 and the on-state voltage of the MOSFET to be tested, so that the on-state voltage of the MOSFET to be tested can be obtained based on the on-state voltage of the first resistor R1, the on-state voltage of the first diode S1 and the voltage measured at P1;

[0005] The current acquisition circuit includes a current sensor, which is used to measure the current I across the drain and source of the MOSFET under test. DS ;

[0006] Based on the on-state voltage and drain-source current I of the MOSFET to be tested DS , and obtain the first on-resistance of the MOSFET to be tested.

[0007] The present disclosure also provides a MOSFET health monitoring method, characterized in that a MOSFET device on-resistance measurement circuit according to any embodiment of the present disclosure is used to compare the first on-resistance of the MOSFET to be tested with the second on-resistance of the MOSFET to be tested, to obtain the health status information of the MOSFET, and to complete the health monitoring of the MOSFET. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0009] Figure 1 A schematic diagram of a MOSFET on-state voltage measurement circuit according to some embodiments of the present disclosure is shown;

[0010] Figure 2 A schematic diagram of a circuit for measuring the on-state voltage of a MOSFET when the source is not grounded according to some embodiments of the present disclosure is shown;

[0011] Figure 3 shows a schematic diagram of a first current source circuit according to some embodiments of the present disclosure;

[0012] Figure 4 A graph showing a change in on-resistance of a MOSFET as a function of temperature according to some embodiments of the present disclosure is shown;

[0013] Figure 5 shows a MOSFET driving circuit diagram according to some embodiments of the present disclosure;

[0014] Figure 6 An algorithm flow chart illustrating MOSFET health monitoring according to some embodiments of the present disclosure is shown;

[0015] Figure 7 A schematic diagram illustrating a method for health monitoring of a MOSFET according to some embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0017] Figure 1 A MOSFET on-state voltage measurement circuit according to some embodiments of the present disclosure is shown.

[0018] like Figure 1As shown, in some embodiments of the present disclosure, a MOSFET device on-resistance measurement circuit may include a voltage measurement circuit and a current acquisition circuit.

[0019] like Figure 1 As shown, the voltage measurement circuit includes a first resistor R1, a first diode D1 and a first current source S1. The first current source S1 is used to provide current for the circuit. The first resistor R1 is connected to the first current source S1. The anode of the first diode D1 is connected to the first resistor R1. The cathode of the first diode D1 is connected to the drain of the MOSFET Q1 to be measured. The source of the MOSFET Q1 to be measured is grounded GND1. A measurement point P1 is set between the first diode D1 and the first resistor R1. When the MOSFET Q1 to be measured is turned on (see the conduction path), Figure 1 The current source S1 provides a current I S1 The current flows through the first resistor R1, the first diode D1 and the MOSFET Q1 to be tested in sequence. The voltage measured at P1 is equal to the sum of the first resistor R1, the first current source S1 and the on-state voltage of the MOSFET to be tested. Therefore, the on-state voltage of the MOSFET Q1 to be tested can be obtained based on the on-state voltage of the first resistor R1, the on-state voltage of the first diode S1 and the voltage measured at P1.

[0020] In some embodiments of the present disclosure, the current source S1 can provide a current of the milliampere (mA) level, such as a current of 1mA-10mA, and the voltage measured at P1 is V mea ,V mea is the on-state voltage V of resistor R1 R1 , the forward voltage of diode D1 V D1 and the on-state voltage V on The sum of , as shown in formula (1):

[0021] V mea =V R1 +V D1 +V on (1)

[0022] The on-state voltage V of the MOSFET to be tested on It can be obtained according to formula (1).

[0023] In some embodiments of the present disclosure, the current acquisition circuit may include a current sensor (not shown in the drawings) for measuring the current I across the drain and source of the MOSFET to be tested. DS Based on the on-state voltage and drain-source current I of the MOSFET to be tested DS , and obtain the first on-resistance of the MOSFET to be tested.

[0024] In some embodiments of the present disclosure, the first on-resistance R on1 According to formula (2), we can get:

[0025]

[0026] In some embodiments of the present disclosure, the current sensor may be installed between the source of the MOSFET to be tested and the ground GND.

[0027] Figure 1 In the on-state voltage measurement circuit shown, the source of MOSFET Q1 is grounded. Therefore, the voltage measured when the MOSFET is on is the drain voltage to ground. Since the source is grounded, the drain voltage is equal to the drain-source voltage. However, when the source is not grounded, such as in a four-switch Buck-Boost circuit and a three-phase inverter, the source of the MOSFET on the upper bridge arm is connected to the load. Figure 1 The measurement circuit shown is used to measure the high-side MOSFET. The measurement results are obviously wrong. Therefore, the circuit should be redesigned when measuring the on-state voltage of a MOSFET whose source is not connected to ground.

[0028] Figure 2 A schematic diagram of a circuit for measuring the on-state voltage of a MOSFET Q2 when the source is not grounded according to some embodiments of the present disclosure is shown.

[0029] like Figure 2 As shown, in some embodiments of the present disclosure, when the source of the MOSFET to be tested is not grounded but connected to the MOSFET Q3, the voltage measurement circuit may include a drain voltage measurement circuit of the MOSFET to be tested, a source voltage measurement circuit and a differential circuit. Figure 2 Where Vd represents the drain voltage, Vs represents the source voltage, and Vds represents the voltage difference between the drain and source.

[0030] The drain voltage measurement circuit includes a second resistor R2, a second diode D2, and a second current source S2. The second current source S2 is used to provide current for the drain voltage measurement circuit. The second resistor R2 is connected to the second current source S2. The anode of the second diode D2 is connected to the second resistor R2. The cathode of the second diode D2 is connected to the drain of the MOSFET Q2 to be measured.

[0031] The source voltage measurement circuit includes a third resistor R3, a third diode D3, and a third current source S3. The current source S3 is used to provide current for the source voltage measurement circuit. The third resistor R3 is connected to the third current source S3. The anode of the third diode D3 is connected to the third resistor R3. The cathode of the third diode D3 is connected to the source of the MOSFET Q2 to be measured and the drain of the MOSFET Q3.

[0032] The differential circuit includes a fourth resistor R4, a fifth resistor R5, and a seventh resistor R7. The fourth resistor R4 is installed between the output terminal of the current source S2 and GND2. The fifth resistor R5 is installed between the inverting input terminal of the operational amplifier U and the output port of the first current source S1. The seventh resistor R7 is installed between the inverting input terminal of the operational amplifier U and the output terminal of the operational amplifier U.

[0033] The drain voltage of the MOSFET to be tested is obtained based on the drain voltage measurement circuit, the source voltage of the MOSFET to be tested is obtained based on the source voltage measurement circuit, and the on-state voltage of the MOSFET to be tested is obtained based on the differential operation of the drain voltage of the MOSFET to be tested and the source voltage of the MOSFET to be tested.

[0034] like Figure 2 The drain voltage measurement circuit shown measures the drain voltage of the MOSFET, and the source voltage measurement circuit measures the source voltage of the MOSFET. The on-state voltage of the MOSFET can be obtained by performing a differential operation on the drain voltage of the MOSFET and the source voltage of the MOSFET.

[0035] Figure 3 A first current source circuit schematic diagram according to some embodiments of the present disclosure is shown.

[0036] like Figure 3 As shown, in some embodiments of the present disclosure, the first current source S1 includes a first transistor B1, a second transistor B2 and an eighth resistor R, the first transistor B1 and the second transistor B2 are identical, and the current source positive polarity power supply +V CC The emitters of the first transistor B1 and the second transistor B2 are connected to the negative polarity power supply -V EE , and the first transistor B1 and the second transistor B2 are connected to each other through the base-collector. Figure 3 In FIG, c1 and c2 represent the collectors of the first transistor B1 and the second transistor B2 respectively; b1 and b2 represent the bases of the first transistor B1 and the second transistor B2 respectively.

[0037] The parameters of the first transistor B1 and the second transistor B2 are exactly the same, that is, the current amplification factor β1 = β2, and the base open-circuit reverse drain current I ceo1 =I ceo2 , and the base-emitter voltages of the two transistors are equal, the voltage drop between the emitter and base of the transistor is V BE1 =V BE2 , so the transistor emitter current I E1 =I E2 , collector current I C1 =I C2 When the transistor's current amplification factor β is large, the base current IB can be ignored, so the collector current I C2 Approximately equal to the reference current I REF ,Right now

[0038]

[0039] When R is determined, I REF Also confirmed, I C2 Also confirmed, I C2 As I REF Mirror image, I O =I C2 =I REF , when the relative areas A1 and A2 of the emitter junctions of the two transistors are different, the output current of the first current source S1 is:

[0040]

[0041] By using the current source in some embodiments of the present disclosure, a specific output current can be obtained.

[0042] Those skilled in the art will appreciate that other current sources in the present disclosure may also be used. Figure 3 The current source shown will not be described in detail here.

[0043] In some embodiments of the present disclosure, the MOSFET device on-resistance measurement circuit may further include a controller for receiving the on-voltage and drain-source current I of the MOSFET to be measured in real time. DS , and outputs the first on-resistance value of the MOSFET to be tested in real time.

[0044] In some embodiments of the present disclosure, the controller (e.g., control unit MCU) may select STM32G474 from STMicroelectronics (ST), DSP28335 from Texas Instruments (TI), or Loongson GSC3290. The selection principle is that there must be enough ADC channels to process the collected data and perform calculations, and a high-precision timer (HRTIM) must be available to meet the needs of switch control.

[0045] In some embodiments of the present disclosure, the MOSFET device on-resistance measurement circuit may further include a temperature acquisition system for monitoring the temperature of the MOSFET to be measured in real time.

[0046] In some embodiments of the present disclosure, the temperature acquisition system may include a temperature sensor.

[0047] In some embodiments of the present disclosure, the temperature sensor may be installed near the source of the MOSFET to be tested.

[0048] Figure 4A graph showing the variation of MOSFET on-resistance with temperature according to some embodiments of the present disclosure is shown.

[0049] In some embodiments of the present disclosure, based on the curve of the on-resistance of the MOSFET to be measured changing with temperature, a formula for the on-resistance of the MOSFET to be measured at different temperatures is fitted and pre-stored in a controller. After the controller receives temperature information from a temperature acquisition system, it obtains a second on-resistance value of the MOSFET to be measured at the temperature.

[0050] The on-resistance curve of a certain type of MOSFET changes with temperature is as follows Figure 4 As shown, formula (5) can be obtained by fitting:

[0051] R on =1.41×10 -7 T 3 +8.62×10 -5 T 2 +0.03T+6.653 (5)

[0052] Formula (5) can be used to calculate the change in on-resistance of the same MOSFET at different temperatures.

[0053] In some embodiments of the present disclosure, a formula obtained by curve fitting of the on-resistance of the MOSFET to be tested versus temperature can be pre-stored in the controller. After receiving temperature information from the temperature acquisition system, the controller obtains the second on-resistance value of the MOSFET to be tested at the temperature.

[0054] In some embodiments of the present disclosure, the controller first receives temperature information collected by the temperature sensor, obtains the temperature of the environment in which the MOSFET is located at that time, and calculates the on-resistance of the MOSFET at that temperature according to formula (5). For example, when the MOSFET operates in an environment of 25°C, the calculated on-resistance value is:

[0055] R on =1.41×10 -7 ×25 3 +8.62×10 -5 ×25 2 +0.03×25+6.653=7.46mΩ (6)

[0056] The controller then compares the second on-resistance value calculated according to formula (5) with the first on-resistance calculated according to formula (2) to complete the health monitoring of the MOSFET to be tested.

[0057] In some embodiments of the present disclosure, when the first on-resistance calculated according to formula (2) exceeds 50% of the second on-resistance calculated according to formula (5), it is determined that the MOSFET has failed.

[0058] In some embodiments of the present disclosure, the MOSFET device on-resistance measurement circuit may further include a drive circuit. The drive circuit is provided at the gate of the MOSFET to be measured to ensure that the MOSFET to be measured is smoothly turned on.

[0059] Figure 5 A MOSFET driving circuit diagram according to some embodiments of the present disclosure is shown.

[0060] like Figure 5 As shown, in some embodiments of the present disclosure, when the source of the MOSFET Q1 to be tested is grounded, a common ground driving circuit can be used, wherein the transistor Q T1 and transistor Q T2 For NPN transistor, Q T1 The collector is connected to the working power supply V cc The positive end, Q T2 The collector is connected to the working power supply V cc Ground GND4. Q T1 and Q T2 The emitters of Q are connected together as output to drive MOSFET. T1 and Q T2 The bases of the two terminals are connected together and connected to the HRTIM of the controller, Q T1 and Q T2 To increase the discharge speed, you can add g Connect a resistor R in parallel g_off and diode D off The driving circuit increases the voltage source V CC The current supply capability can quickly complete the charging process of the gate capacitance input.

[0061] like Figure 5 As shown, in some embodiments of the present disclosure, a current limiting resistor R 11 , used to prevent excessive current. V test Refers to the voltage at the test terminal.

[0062] Figure 6 A schematic diagram of a method for monitoring MOSFET health according to some embodiments of the present disclosure is shown. Figure 7 A flow chart illustrating an algorithm for health monitoring of a MOSFET according to some embodiments of the present disclosure is shown.

[0063] like Figure 6 and Figure 7As shown, in some embodiments of the present disclosure, a MOSFET health monitoring method uses a MOSFET device on-resistance measurement circuit according to any embodiment of the present disclosure to compare the first on-resistance of the MOSFET to be tested with the second on-resistance of the MOSFET to be tested, obtain the health status information of the MOSFET, and complete the health monitoring of the MOSFET.

[0064] Figure 6 The schematic diagram of the MOSFET to be tested when the source is grounded is only shown as an example. Those skilled in the art will understand that the schematic diagram of the MOSFET to be tested can also be shown as an example. Figure 2 The circuit diagram shown here is applied when the source of the MOSFET under test is not grounded. Figure 6 middle.

[0065] like Figure 7 As shown, in some embodiments of the present disclosure, the interval for the temperature acquisition system to acquire temperature and the interval for the current acquisition circuit to acquire current is 0.5S. For example, the controller adopts MCU.

[0066] Those skilled in the art will understand Figure 7 AD conversion (Analog-to-Digital Conversion) refers to the process of converting a continuously changing analog signal into a discrete digital signal (binary code).

[0067] In some embodiments of the present disclosure, when the first on-resistance of the MOSFET to be tested exceeds 50% of the second on-resistance of the MOSFET to be tested, it is determined that the MOSFET has failed.

[0068] In some embodiments of the present disclosure, a backup MOSFET of the same model as the MOSFET under test is connected in parallel to the MOSFET under test. When the MOSFET under test is detected to be faulty, the backup MOSFET is put into the system to avoid system shutdown.

[0069] According to some embodiments of the present disclosure, the MOSFET device on-resistance measurement circuit and health monitoring method can monitor the health status of the MOSFET in real time by accurately measuring the MOSFET on-resistance, and has the advantages of simple structure and accurate results.

[0070] According to some embodiments of the present disclosure, the MOSFET device on-resistance measurement circuit and health monitoring method, combined with a controller, can achieve online real-time measurement.

[0071] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A MOSFET device on-resistance measurement circuit, characterized in that: Including voltage measurement circuit and current acquisition circuit, The voltage measurement circuit includes a first resistor R1, a first diode D1 and a first current source S1. The first current source S1 is used to provide current for the circuit. The first resistor R1 is connected to the first current source S1. The anode of the first diode D1 is connected to the first resistor R1. The cathode of the first diode D1 is connected to the drain of the MOSFET to be measured. The source of the MOSFET to be measured is grounded. A measurement point P1 is set between the first diode D1 and the first resistor R1. When the MOSFET to be measured is turned on, the current I S1 The current flows through the first resistor R1, the first diode D1 and the MOSFET to be tested in sequence, and the voltage measured at P1 is equal to the sum of the first resistor R1, the first current source S1 and the on-state voltage of the MOSFET to be tested, so that the on-state voltage of the MOSFET to be tested can be obtained based on the on-state voltage of the first resistor R1, the on-state voltage of the first diode S1 and the voltage measured at P1; The current acquisition circuit includes a current sensor for measuring the current I across the drain and source of the MOSFET to be tested. DS ; Based on the on-state voltage of the MOSFET to be tested and the current I DS , and obtain the first on-resistance of the MOSFET to be tested.

2. The MOSFET device on-resistance measurement circuit according to claim 1, wherein: The current sensor is installed between the source of the MOSFET to be tested and the ground terminal.

3. The MOSFET device on-resistance measurement circuit according to claim 1, wherein: When the source of the MOSFET Q2 to be tested is not grounded, The voltage measurement circuit includes a MOSFET drain voltage measurement circuit, a source voltage measurement circuit and a differential circuit. The drain voltage measurement circuit includes a second resistor R2, a second diode D2, and a second current source S2. The second current source S2 is used to provide current for the drain voltage measurement circuit. The second resistor R2 is connected to the second current source S2. The anode of the second diode D2 is connected to the second resistor R2. The cathode of the second diode D2 is connected to the drain of the MOSFET Q2 to be measured. The source voltage measurement circuit includes a third resistor R3, a third diode D3 and a third current source S3. The current source S3 is used to provide current for the source voltage measurement circuit. The third resistor R3 is connected to the third current source S3. The anode of the third diode D3 is connected to the third resistor R3. The cathode of the third diode D3 is connected to the source of the MOSFET Q2 to be measured and the drain of the MOSFET Q3. The differential circuit includes a fourth resistor R4, a fifth resistor R5 and a seventh resistor R7, the fourth resistor R4 is installed between the output terminal of the current source S2 and GND2, the fifth resistor R5 is installed between the inverting input terminal of the operational amplifier U and the output port of the first current source S1, and the seventh resistor R7 is installed between the inverting input terminal of the operational amplifier U and the output terminal of the operational amplifier U; The drain voltage of the MOSFET to be tested is obtained based on the drain voltage measurement circuit, the source voltage of the MOSFET to be tested is obtained based on the source voltage measurement circuit, and the on-state voltage of the MOSFET to be tested is obtained based on the differential operation of the drain voltage of the MOSFET to be tested and the source voltage of the MOSFET to be tested.

4. The MOSFET device on-resistance measurement circuit according to claim 1, wherein: The controller is also included to receive the on-state voltage of the MOSFET to be tested and the current I across the drain and source electrodes measured in real time. DS , and outputs the first on-resistance value of the MOSFET to be tested in real time.

5. The MOSFET device on-resistance measurement circuit according to claim 4, characterized in that: According to the curve of the on-resistance change of the MOSFET to be tested with temperature, the on-resistance formula of the MOSFET to be tested at different temperatures is fitted and pre-stored in the controller. After the controller receives the temperature information from the temperature acquisition system, it obtains the second on-resistance of the MOSFET to be tested at the temperature.

6. The MOSFET device on-resistance measurement circuit according to claim 4, characterized in that: It also includes a temperature acquisition system for real-time monitoring of the temperature of the MOSFET to be tested.

7. The MOSFET device on-resistance measurement circuit according to claim 1, characterized in that: The first current source S1 includes a first transistor B1, a second transistor B2 and an eighth resistor R. The first transistor B1 and the second transistor B2 are identical. The positive polarity power supply of the current source +V CC The emitters of the first transistor B1 and the second transistor B2 are connected to the negative polarity power supply -V EE , and the first transistor B1 and the second transistor B2 are connected to each other through the base-collector.

8. A MOSFET health monitoring method, characterized in that: Using the MOSFET device on-resistance measurement circuit according to any one of claims 1 to 7, the first on-resistance of the MOSFET to be measured and the second on-resistance of the MOSFET to be measured are compared to obtain the health status information of the MOSFET, thereby completing the health monitoring of the MOSFET.

9. The MOSFET health monitoring method according to claim 8, characterized in that: When the first on-resistance of the MOSFET to be tested exceeds 50% of the second on-resistance of the MOSFET to be tested, it is determined that the MOSFET is failed.

10. The MOSFET health monitoring method according to claim 8, characterized in that: A spare MOSFET of the same model as the MOSFET to be tested is connected in parallel to the MOSFET to be tested. When the MOSFET to be tested is detected to be faulty, the spare MOSFET is put into the system to avoid system shutdown.

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