Current detection device, method of bridge drive circuit and automobile

Abstract

The application discloses a current detection device and method of a bridge driving circuit and an automobile. The device utilizes a sampling resistor and a first switch tube to sample and detect the current in the driving circuit, and the influence of temperature is considered, so that the accuracy of current detection is improved. When the sampling resistor is short-circuited, the first switch tube can be used to continue sampling, and a redundant design is realized. Meanwhile, according to the sampling results of the sampling resistor and the first switch tube, whether the driving circuit is open-circuited or the first switch tube is short-circuited can be judged, and the reliability and safety of the bridge driving circuit are ensured.

Description

Technical Field

[0001] This invention belongs to the field of automotive electrical systems, and specifically relates to a current detection device, method, and automobile for a bridge drive circuit. Background Technology

[0002] With the rapid development of automotive intelligence and electrification technologies, new energy vehicles have placed higher demands on the reliability of drive circuits and the safety of systems. Previous bridge-type drive circuit current acquisition primarily focused on improving accuracy, but lacked countermeasures for failures in the acquisition devices themselves. This resulted in circuit malfunctions or software errors such as misjudgments and erroneous operations.

[0003] Currently, current detection in bridge drive circuits typically uses resistors as current sampling devices, i.e., sampling resistors. However, the real-time resistance value of the sampling resistor changes with temperature, a fact often overlooked during data acquisition and conversion. Furthermore, the sampling resistor exists in three states: short circuit, open circuit, and resistance change. Existing current detection devices cannot accurately determine whether to activate protection or continue data acquisition.

[0004] JP7087373B2 discloses a current detection circuit and current detection method for a semiconductor device, comprising: a current detection unit for detecting a potential difference between two ends of a first current detection resistor by inserting a first current detection resistor between a control terminal of a voltage-controlled semiconductor element having a current detection terminal and a drive circuit; a voltage detection unit for detecting the voltage across one end of the first current detection resistor; a voltage determination unit for determining whether the detection voltage output from the voltage detection unit is equal to or higher than a first threshold voltage; a voltage level adjustment unit for adjusting the voltage level of the current detection voltage at the current detection terminal by at least a logic signal of the detection signal of the current detection unit and the voltage determination signal of the voltage determination unit; and an overcurrent detection unit for outputting an overcurrent detection signal when the current detection voltage adjusted by the voltage level adjustment unit is equal to or higher than a second threshold voltage. However, it still has the following problems: (1) Using the first current sensing resistor as the sampling resistor does not take into account the influence of temperature on the resistance value of the sampling resistor, which leads to the deviation between the sampling result and the actual value increasing with the increase of temperature; (2) Using the first current sensing resistor for sampling, it is impossible to determine the situation where the first current sensing resistor itself is abnormal (such as short circuit or open circuit), and no response strategy is considered after such abnormality occurs; (3) Only the first current sensing resistor is sampled (i.e., single resistor sampling), which cannot achieve sampling redundancy. Summary of the Invention

[0005] The purpose of this invention is to provide a current detection device, method, and vehicle for a bridge drive circuit, so as to improve the accuracy of current detection and ensure the reliability and safety of the bridge drive circuit.

[0006] In a first aspect, the current detection device for the bridge drive circuit of the present invention includes a controller, a driver connected to the controller, and n detection modules. The i-th driving terminal of the driver is connected to the gate of the first switching transistor in the i-th driving loop, and the remaining driving terminals of the driver are respectively connected to the gates of other switching transistors in the bridge drive circuit. Each detection module includes a sampling resistor, a sampling resistor voltage acquisition circuit, a sampling resistor temperature detection circuit, a switching transistor temperature detection circuit, and a switching transistor on-state voltage acquisition circuit. The sampling resistor in the i-th detection module is connected in series in the bridge arm of the i-th driving loop.

[0007] The sampling resistor temperature detection circuit in the i-th detection module is positioned close to the sampling resistor. Its input is connected to the i-th driving terminal of the driver, and its output is connected to the i-th resistor temperature acquisition terminal of the controller. This circuit detects the temperature near the sampling resistor (equivalent to detecting the temperature of the sampling resistor itself) and outputs the acquired value (voltage) corresponding to the temperature of the sampling resistor to the controller.

[0008] The switching transistor temperature detection circuit in the i-th detection module is positioned close to the first switching transistor (i.e., in the i-th drive loop). The input of this circuit is connected to the i-th drive terminal of the driver, and its output is connected to the i-th switching transistor temperature acquisition terminal of the controller. The switching transistor temperature detection circuit is used to detect the temperature near the first switching transistor (equivalent to detecting the temperature of the first switching transistor) and outputs the acquired value (voltage) corresponding to the temperature of the first switching transistor to the controller.

[0009] The sampling resistor voltage acquisition circuit in the i-th detection module is connected in parallel with the sampling resistor. The controlled terminal of this sampling resistor voltage acquisition circuit is connected to the i-th resistor sampling control terminal of the controller, and the output terminal is connected to the i-th resistor voltage acquisition terminal of the controller. The sampling resistor voltage acquisition circuit is used to acquire the voltage value of the sampling resistor (i.e., the voltage drop formed on the sampling resistor due to the current flowing through it) and transmit this voltage value to the controller.

[0010] The switching transistor on-state voltage acquisition circuit in the i-th detection module is connected in parallel with the first switching transistor. The output of this circuit is connected to the i-th switching transistor on-state voltage acquisition terminal of the controller. The switching transistor on-state voltage acquisition circuit is used to acquire the voltage value when the switching transistor is turned on (i.e., the voltage drop between the drain and source of the first switching transistor after it is turned on) and transmit this voltage value to the controller.

[0011] Where n represents the number of drive loops in the bridge drive circuit, and i takes all integers from 1 to n.

[0012] Preferably, the sampling resistor voltage acquisition circuit includes a first operational amplifier module, a first controllable switch S1, and a second controllable switch S2; the first input terminal of the first operational amplifier module is connected to one end of the sampling resistor through the first controllable switch S1, the second input terminal of the first operational amplifier module is connected to the other end of the sampling resistor through the second controllable switch S2, the output terminal of the first operational amplifier module is connected to the i-th resistor voltage acquisition terminal of the controller, and the controlled terminals of the first controllable switch S1 and the second controllable switch S2 are connected to the i-th resistor sampling control terminal of the controller.

[0013] Preferably, the sampling resistor temperature detection circuit includes a second operational amplifier module, a first diode D1, and a first current-limiting resistor R1, with the first diode D1 close to the sampling resistor; the first input terminal of the second operational amplifier module is connected to the negative terminal of the first diode D1, the second input terminal of the second operational amplifier module is connected to the positive terminal of the first diode D1 and one end of the first current-limiting resistor R1, the output terminal of the second operational amplifier module is connected to the i-th resistance temperature acquisition terminal of the controller, the negative terminal of the first diode D1 is grounded, and the other end of the first current-limiting resistor R1 is connected to the i-th driving terminal of the driver.

[0014] Preferably, the switching transistor temperature detection circuit includes a third operational amplifier module, a second diode D2, and a second current-limiting resistor R2. The second diode D2 is close to the first switching transistor. The first input terminal of the third operational amplifier module is connected to the negative terminal of the second diode D2, the second input terminal of the third operational amplifier module is connected to the positive terminal of the second diode D2 and one end of the second current-limiting resistor R2, the output terminal of the third operational amplifier module is connected to the i-th switching transistor temperature acquisition terminal of the controller, the negative terminal of the second diode D2 is grounded, and the other end of the second current-limiting resistor R2 is connected to the i-th driving terminal of the driver.

[0015] Preferably, the switching transistor on-state voltage acquisition circuit is a fourth operational amplifier module. The first input terminal of the fourth operational amplifier module is connected to the source of the first switching transistor, the second input terminal is connected to the drain of the first switching transistor, and the output terminal is connected to the i-th switching transistor on-state voltage acquisition terminal of the controller.

[0016] Secondly, the current detection method for the bridge drive circuit described in this invention employs the current detection device for the aforementioned bridge drive circuit. The method includes: when the i-th drive loop is connected (i.e., the controller controls the driver to drive the corresponding switching transistor to conduct, forming the i-th drive loop), the controller performs the following steps:

[0017] The temperature T1 of the sampling resistor is determined based on the collected value input from the i-th resistor temperature acquisition terminal of the controller, and the resistance value Rc of the sampling resistor is determined based on the temperature T1 of the sampling resistor.

[0018] If U1>0, the first current I1 can be calculated using the formula: I1= U1 / Rc; where U1 is the voltage value input to the i-th resistor voltage acquisition terminal of the controller.

[0019] The temperature T2 of the first switch is determined based on the acquired value input from the temperature acquisition terminal of the i-th switch of the controller, and the on-resistance Rn of the first switch is determined based on the temperature T2 of the first switch.

[0020] If U2>0, the second current I2 can be calculated using the formula: I2= U2 / Rn; where U2 is the voltage value input to the on-voltage acquisition terminal of the i-th switch of the controller.

[0021] If U1>0 and U2>0, then use the formula: I o =(I1+I2) / 2, calculate the current I of the i-th drive loop. o .

[0022] Preferably, the method for determining the resistance value Rc of the sampling resistor is as follows: consult a preset temperature-resistance table based on the temperature T1 of the sampling resistor to obtain the resistance value corresponding to temperature T1; use the resistance value corresponding to temperature T1 as the resistance value Rc of the sampling resistor. The method for determining the on-state internal resistance Rn of the first switching transistor is as follows: consult a preset temperature-internal resistance table based on the temperature T2 of the first switching transistor to obtain the internal resistance corresponding to temperature T2; use the internal resistance corresponding to temperature T2 as the on-state internal resistance Rn of the first switching transistor. Wherein, the preset temperature-resistance table is a table of the correspondence between the temperature and resistance value of the sampling resistor obtained through calibration; the preset temperature-internal resistance table is a table of the correspondence between the temperature and on-state internal resistance of the first switching transistor obtained through calibration.

[0023] Preferably, if U1≤0 and U2>0 (corresponding to the sampling resistor voltage acquisition circuit not acquiring voltage, while the switching transistor conduction voltage acquisition circuit acquires voltage, indicating a short circuit fault in the sampling resistor), then the second current I2 is used as the current I of the i-th drive loop. o It also controls the sampling resistor voltage acquisition circuit to stop working, and the switching transistor turns on the voltage acquisition circuit to continue the acquisition work.

[0024] Preferably, if U2≤0 (indicating that the i-th drive circuit has an open circuit fault or its first switch has a short circuit fault), then the current detection of the i-th drive circuit is stopped, the sampling resistor voltage acquisition circuit is stopped, and the first switch is turned off.

[0025] Thirdly, the automobile described in this invention includes the current detection device for the aforementioned bridge drive circuit.

[0026] This invention utilizes a sampling resistor and a first switching transistor to sample and detect the current in the drive circuit, taking into account the effect of temperature, thereby improving the accuracy of current detection. Furthermore, when the sampling resistor is short-circuited, the first switching transistor can continue to sample, achieving a redundant design. At the same time, based on the sampling results of the sampling resistor and the first switching transistor, it is also possible to determine whether the drive circuit is open-circuited or whether its first switching transistor is short-circuited, thus ensuring the reliability and safety of the bridge drive circuit. Attached Figure Description

[0027] Figure 1 This is a circuit diagram of the current detection device of the H-bridge drive circuit in an embodiment of the present invention.

[0028] Figure 2 This is a flowchart of the current detection method when the first drive loop of the H-bridge drive circuit is turned on in an embodiment of the present invention.

[0029] Figure 3 This is a flowchart of the current detection method when the second drive loop of the H-bridge drive circuit is turned on in an embodiment of the present invention. Detailed Implementation

[0030] To gain a more detailed understanding of the features and technical content of the embodiments of the present invention, the implementation of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference and illustration only and are not intended to limit the embodiments of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0032] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0033] Bridge drive circuits mainly include H-bridge drive circuits, half-bridge drive circuits, and three-phase full-bridge drive circuits. This embodiment uses the H-bridge drive circuit as an example for explanation. Figure 1As shown, the H-bridge driver circuit has four switching transistors: Q1, Q2, Q3, and Q4. Switches Q1 and Q2 are connected to form the first bridge arm, and Q3 and Q4 are connected to form the second bridge arm. One end of the load 9 is connected to the midpoint of the first bridge arm (the connection point of Q1 and Q2), and the other end of the load 9 is connected to the midpoint of the second bridge arm (the connection point of Q3 and Q4). The H-bridge driver circuit has two drive loops, i.e., n=2. The first drive loop is formed by switch Q1, load 9, and switch Q4. Current flows from the power supply VDD, passing through switch Q1, load 9, and switch Q4 sequentially to ground. The second drive loop is formed by switch Q3, load 9, and switch Q2. Current flows from the power supply VDD, passing through switch Q3, load 9, and switch Q2 sequentially to ground. The first switching transistor 8 in the first drive loop is switch Q1. The first switch in the second drive circuit is switch Q3.

[0034] like Figure 1 As shown, the current detection device of the bridge drive circuit (i.e., H-bridge drive circuit) includes: a controller 1, a driver 2 connected to the controller 1, and two detection modules. The first drive terminal NA1 of the driver 2 is connected to the gate of the first switch 8 (i.e., switch Q1) in the first drive loop, the second drive terminal NA2 of the driver 2 is connected to the gate of the first switch 8 (i.e., switch Q3) in the second drive loop, the third drive terminal NA3 of the driver 2 is connected to the gate of switch Q2, and the fourth drive terminal NA4 of the driver 2 is connected to the gate of switch Q4.

[0035] Each detection module includes a sampling resistor 3, a sampling resistor voltage acquisition circuit 4, a sampling resistor temperature detection circuit 5, a switching transistor temperature detection circuit 6, and a switching transistor on-state voltage acquisition circuit 7.

[0036] In some embodiments, the sampling resistor voltage acquisition circuit 4 includes a first operational amplifier module 41, a first controllable switch S1, and a second controllable switch S2. The sampling resistor voltage acquisition circuit 4 is connected in parallel with the sampling resistor 3. The first input terminal of the first operational amplifier module 41 is connected to one end of the sampling resistor 3 through the first controllable switch S1, and the second input terminal of the first operational amplifier module 41 is connected to the other end of the sampling resistor 3 through the second controllable switch S2.

[0037] In some embodiments, the sampling resistor temperature detection circuit 5 includes a second operational amplifier module 51, a first diode D1, and a first current-limiting resistor R1. The first input terminal of the second operational amplifier module 51 is connected to the cathode of the first diode D1, the second input terminal of the second operational amplifier module 51 is connected to the anode of the first diode D1 and one end of the first current-limiting resistor R1, and the cathode of the first diode D1 is grounded.

[0038] In some embodiments, the switching transistor temperature detection circuit 6 includes a third operational amplifier module 61, a second diode D2, and a second current-limiting resistor R2. The first input terminal of the third operational amplifier module 61 is connected to the negative terminal of the second diode D2, the second input terminal of the third operational amplifier module 61 is connected to the positive terminal of the second diode D2, and one end of the second current-limiting resistor R2. The negative terminal of the second diode D2 is grounded.

[0039] In some embodiments, the switching transistor conduction voltage acquisition circuit 7 is a fourth operational amplifier module.

[0040] For the first drive loop and the first detection module: Sampling resistor 3 is connected in series on the first bridge arm, located between switch Q1 and load 9. First diode D1 is positioned close to sampling resistor 3. The other end of first current-limiting resistor R1 (serving as the input of sampling resistor temperature detection circuit 5) is connected to the first drive terminal NA1 of driver 2. The output terminal of second operational amplifier module 51 (serving as the output of sampling resistor temperature detection circuit 5) is connected to the first resistance temperature acquisition terminal EB1 of controller 1. Second diode D2 is positioned close to switch Q1. The other end of second current-limiting resistor R2 (serving as the input of switch transistor temperature detection circuit 6) is connected to the first drive terminal NA1 of driver 2. The output terminal of third operational amplifier module 61 (serving as the output of switch transistor temperature detection circuit 6) is connected to the first switch transistor temperature acquisition terminal EC1 of controller 1. The output terminal of the first operational amplifier module 41 (which serves as the output terminal of the sampling resistor voltage acquisition circuit 4) is connected to the first resistor voltage acquisition terminal EA1 of the controller 1. The controlled terminals of the first controllable switch S1 and the second controllable switch S2 (which serve as the controlled terminals of the sampling resistor voltage acquisition circuit 4) are connected to the first resistor sampling control terminal FA1 of the controller 1. The first input terminal of the fourth operational amplifier module is connected to the source of the switching transistor Q1, the second input terminal of the fourth operational amplifier module is connected to the drain of the switching transistor Q1, and the output terminal of the fourth operational amplifier module is connected to the first switching transistor conduction voltage acquisition terminal ED1 of the controller 1.

[0041] For the second drive circuit and the second detection module: Sampling resistor 3 is connected in series on the second bridge arm, located between switch Q3 and load 9. First diode D1 is positioned close to sampling resistor 3. The other end of first current-limiting resistor R1 (serving as the input of sampling resistor temperature detection circuit 5) is connected to the second drive terminal NA2 of driver 2. The output terminal of second operational amplifier module 51 (serving as the output of sampling resistor temperature detection circuit 5) is connected to the second resistance temperature acquisition terminal EB2 of controller 1. Second diode D2 is positioned close to switch Q3. The other end of second current-limiting resistor R2 (serving as the input of switch transistor temperature detection circuit 6) is connected to the second drive terminal NA2 of driver 2. The output terminal of third operational amplifier module 61 (serving as the output of switch transistor temperature detection circuit 6) is connected to the second switch transistor temperature acquisition terminal EC2 of controller 1. The output terminal of the first operational amplifier module 41 (which serves as the output terminal of the sampling resistor voltage acquisition circuit 4) is connected to the second resistor voltage acquisition terminal EA2 of the controller 1. The controlled terminals of the first controllable switch S1 and the second controllable switch S2 (which serve as the controlled terminals of the sampling resistor voltage acquisition circuit 4) are connected to the second resistor sampling control terminal FA2 of the controller 1. The first input terminal of the fourth operational amplifier module is connected to the source of the switching transistor Q3, the second input terminal of the fourth operational amplifier module is connected to the drain of the switching transistor Q3, and the output terminal of the fourth operational amplifier module is connected to the second switching transistor conduction voltage acquisition terminal ED2 of the controller 1.

[0042] like Figure 2 , Figure 3 As shown, the current detection method of the bridge drive circuit (i.e., H-bridge drive circuit) adopts the current detection device of the bridge drive circuit described above. The method is executed by the controller 1 and includes: a current detection method when the first drive circuit is turned on and a current detection method when the second drive circuit is turned on.

[0043] Controller 1 controls driver 2 to turn on switches Q1 and Q4, forming the first drive loop; at this time, switches Q3 and Q2 are in the off state. The components described below refer to those in the first detection module. For the first drive loop, controller 1 performs the following steps (see...). Figure 2 ):

[0044] Step 1: Determine the temperature T2 of switch Q1 based on the acquired value input to the temperature acquisition terminal EC1 of the first switch of controller 1, determine the on-resistance Rn of switch Q1 based on the temperature T2 of switch Q1, and then proceed to Step 2.

[0045] Since the temperature and voltage drop of the second diode D2 follow a negative linear curve, the temperature of the second diode D2 can be determined by measuring the voltage drop across it (i.e., the voltage acquired by the temperature acquisition terminal EC1 of the first switching transistor in controller 1) and then referring to a table. Furthermore, since the second diode D2 is located close to the switching transistor Q1, its temperature is used as the temperature T2 of the switching transistor Q1. Using diodes for temperature measurement is a current technology.

[0046] In some embodiments, the on-resistance Rn of the switching transistor Q1 is determined as follows: A preset temperature-internal resistance table is consulted based on the temperature T2 of the switching transistor Q1 to obtain the internal resistance corresponding to temperature T2; the internal resistance corresponding to temperature T2 is then used as the on-resistance Rn of the switching transistor Q1. The preset temperature-internal resistance table is a table of the correspondence between the temperature and on-resistance of the first switching transistor (here referring to switching transistor Q1) obtained through calibration.

[0047] Step 2: Determine if U2 > 0. If yes, proceed to step 4; otherwise (i.e., if U2 ≤ 0), proceed to step 3. Here, U2 is the voltage value input to the ED1 terminal of the first switch transistor of controller 1.

[0048] Step 3: Stop the current detection of the first drive circuit, open the first controllable switch S1 and the second controllable switch S2, turn off the switching transistors Q1 and Q4, and then end.

[0049] Step 4: Calculate the second current I2 using the formula: I2 = U2 / Rn, and then proceed to step 5.

[0050] Step 5: Determine the temperature T1 of sampling resistor 3 based on the collected value input from the first resistance temperature acquisition terminal EB1 of controller 1, determine the resistance value Rc of sampling resistor 3 based on the temperature T1 of sampling resistor 3, and then execute step 6.

[0051] Since the temperature and voltage drop of the first diode D1 follow a negative linear curve, the temperature of the first diode D1 can be determined by measuring the voltage drop across it (i.e., the voltage acquired by the first resistor temperature acquisition terminal EB1 of controller 1) and then referring to a table. Furthermore, since the first diode D1 is located close to the sampling resistor 3, its temperature is used as the temperature T1 of the sampling resistor 3. This diode-based temperature measurement method is existing technology.

[0052] In some embodiments, the resistance value Rc of the sampling resistor 3 is determined as follows: a preset temperature-resistance table is consulted based on the temperature T1 of the sampling resistor 3 to obtain the resistance value corresponding to temperature T1; the resistance value corresponding to temperature T1 is then used as the resistance value Rc of the sampling resistor 3. The preset temperature-resistance table is a table showing the correspondence between the temperature and resistance value of the sampling resistor obtained through calibration.

[0053] Step 6: Determine if U1 > 0. If yes, proceed to Step 8; otherwise (i.e., if U1 ≤ 0), proceed to Step 7. Here, U1 is the voltage value input to the first resistor voltage acquisition terminal EA1 of controller 1.

[0054] Step 7: Use the second current I2 as the current I of the first drive circuit. o Then, control the first controllable switch S1 to open and the second controllable switch S2 to open, and then return to execute step one.

[0055] Step 8: Calculate the first current I1 using the formula: I1 = U1 / Rc, and then proceed to step 9.

[0056] Step 9: Using the formula: I o =(I1+I2) / 2, calculate the current I of the first drive loop. o Then return to step one.

[0057] Controller 1 controls driver 2 to turn on switches Q3 and Q2, forming the second drive loop; at this time, switches Q1 and Q4 are in the off state. The components described below refer to those in the second detection module. For the second drive loop, controller 1 performs the following steps (see...). Figure 3 ):

[0058] Step 1: Determine the temperature T2 of switch Q3 based on the acquired value input from the second switch temperature acquisition terminal EC2 of controller 1, and determine the on-resistance Rn of switch Q3 based on the temperature T2 of switch Q3. Then proceed to step 2.

[0059] Since the temperature and voltage drop of the second diode D2 follow a negative linear curve, the temperature of the second diode D2 can be determined by measuring the voltage drop across it (i.e., the voltage acquired by the temperature acquisition terminal EC2 of the second switch transistor in controller 1) and referring to a table. Furthermore, since the second diode D2 is located close to the switch transistor Q3, its temperature is used as the temperature T2 of the switch transistor Q3. Using diodes for temperature measurement is a current technology.

[0060] In some embodiments, the on-resistance Rn of the switching transistor Q3 is determined as follows: A preset temperature-internal resistance table is consulted based on the temperature T2 of the switching transistor Q3 to obtain the internal resistance corresponding to temperature T2; the internal resistance corresponding to temperature T2 is then used as the on-resistance Rn of the switching transistor Q3. The preset temperature-internal resistance table is a table of the correspondence between the temperature and on-resistance of the first switching transistor (here referring to switching transistor Q3) obtained through calibration.

[0061] Step 2: Determine if U2 > 0. If yes, proceed to step 4; otherwise (i.e., if U2 ≤ 0), proceed to step 3. Here, U2 is the voltage value input to the ED2 terminal of the second switch transistor of controller 1.

[0062] Step 3: Stop the current detection of the second drive circuit, open the first controllable switch S1 and the second controllable switch S2, turn off the switching transistors Q3 and Q2, and then end.

[0063] Step 4: Calculate the second current I2 using the formula: I2 = U2 / Rn, and then proceed to step 5.

[0064] Step 5: Determine the temperature T1 of sampling resistor 3 based on the collected value input from the second resistor temperature acquisition terminal EB2, and determine the resistance value Rc of sampling resistor 3 based on the temperature T1 of sampling resistor 3. Then proceed to step 6.

[0065] Since the temperature and voltage drop of the first diode D1 follow a negative linear curve, the temperature of the first diode D1 can be determined by measuring the voltage drop across it (i.e., the voltage acquired by the second resistor temperature acquisition terminal EB2 of controller 1) and referring to a table. Furthermore, since the first diode D1 is located close to the sampling resistor 3, its temperature is used as the temperature T1 of the sampling resistor 3. This diode-based temperature measurement method is existing technology.

[0066] In some embodiments, the resistance value Rc of the sampling resistor 3 is determined as follows: a preset temperature-resistance table is consulted based on the temperature T1 of the sampling resistor 3 to obtain the resistance value corresponding to temperature T1; the resistance value corresponding to temperature T1 is then used as the resistance value Rc of the sampling resistor 3. The preset temperature-resistance table is a table showing the correspondence between the temperature and resistance value of the sampling resistor obtained through calibration.

[0067] Step 6: Determine if U1 > 0. If yes, proceed to step 8; otherwise (i.e., if U1 ≤ 0), proceed to step 7. Here, U1 is the voltage value input to the second resistor voltage acquisition terminal EA2 of controller 1.

[0068] Step 7: Use the second current I2 as the current I of the second drive circuit. o Then, control the first controllable switch S1 to open and the second controllable switch S2 to open, and then return to execute step one.

[0069] Step 8: Calculate the first current I1 using the formula: I1 = U1 / Rc, and then proceed to step 9.

[0070] Step 9: Using the formula: I o =(I1+I2) / 2, calculate the current I of the second drive circuit. o Then return to step one.

[0071] Furthermore, for the half-bridge drive circuit, although it only has two switching transistors, such as Q1 and Q2, it still has two drive loops. In the first drive loop, the first switching transistor is Q1, and the first drive loop is formed by Q1 and the load. Current flows from the power supply VDD, sequentially through Q1 and the load to ground. In the second drive loop, the first switching transistor is Q2, and the second drive loop is formed by Q2 and the load. Current flows from the power supply VDD, sequentially through the load and Q2 to ground. The circuit detection device and detection method are similar to those described above and will not be repeated here.

[0072] This invention also provides an automobile that includes the current detection device of the bridge drive circuit described above.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A current detection device for a bridge drive circuit, comprising a controller (1) and a driver (2) connected to the controller (1), wherein the i-th drive terminal of the driver (2) is connected to the gate of a first switching transistor (8) in the i-th drive circuit; characterized in that, It also includes n detection modules; each detection module includes a sampling resistor (3), a sampling resistor voltage acquisition circuit (4), a sampling resistor temperature detection circuit (5), a switching transistor temperature detection circuit (6), and a switching transistor conduction voltage acquisition circuit (7); the sampling resistor (3) in the i-th detection module is connected in series on the bridge arm of the i-th drive loop, the sampling resistor temperature detection circuit (5) is arranged close to the sampling resistor (3), and its input terminal is connected to the i-th drive terminal of the driver (2), and its output terminal is connected to the i-th resistor temperature acquisition terminal of the controller (1), and the switching transistor temperature detection circuit (6) is arranged close to the first switching transistor (8). The circuit is arranged such that the input terminal is connected to the i-th driving terminal of the driver (2) and the output terminal is connected to the i-th switching tube temperature acquisition terminal of the controller (1). The sampling resistor voltage acquisition circuit (4) is connected in parallel with the sampling resistor (3) and the controlled terminal is connected to the i-th resistor sampling control terminal of the controller (1) and the output terminal is connected to the i-th resistor voltage acquisition terminal of the controller (1). The switching tube conduction voltage acquisition circuit (7) is connected in parallel with the first switching tube (8) and the output terminal is connected to the i-th switching tube conduction voltage acquisition terminal of the controller (1). Wherein, n represents the number of driving loops in the bridge driving circuit, and i takes all integers from 1 to n in sequence. When the i-th drive circuit is connected, the controller (1) determines the temperature T1 of the sampling resistor (3) based on the collected value input from its i-th resistor temperature acquisition terminal, determines the resistance value Rc of the sampling resistor (3) based on the temperature T1 of the sampling resistor (3), determines the temperature T2 of the first switch tube (8) based on the collected value input from its i-th switch tube temperature acquisition terminal, and determines the on-resistance Rn of the first switch tube (8) based on the temperature T2 of the first switch tube (8); if U1>0, the first current I1 is calculated using the formula: I1= U1 / Rc; where U1 is the voltage value input from the i-th resistor voltage acquisition terminal of the controller (1); if U2>0, the second current I2 is calculated using the formula: I2= U2 / Rn; where U2 is the voltage value input from the i-th switch tube on-resistance voltage acquisition terminal of the controller (1); if U1>0 and U2>0, the second current I2 is calculated using the formula: I o =(I1+I2) / 2, calculate the current I of the i-th drive loop. o .

2. The current detection device for the bridge drive circuit according to claim 1, characterized in that: The sampling resistor voltage acquisition circuit (4) includes a first operational amplifier module (41), a first controllable switch S1, and a second controllable switch S2. The first input terminal of the first operational amplifier module (41) is connected to one end of the sampling resistor (3) through the first controllable switch S1, and the second input terminal of the first operational amplifier module (41) is connected to the other end of the sampling resistor (3) through the second controllable switch S2. The output terminal of the first operational amplifier module (41) is connected to the i-th resistor voltage acquisition terminal of the controller (1). The controlled terminals of the first controllable switch S1 and the second controllable switch S2 are connected to the i-th resistor sampling control terminal of the controller (1).

3. The current detection device for the bridge drive circuit according to claim 1, characterized in that: The sampling resistor temperature detection circuit (5) includes a second operational amplifier module (51), a first diode D1 and a first current limiting resistor R1. The first diode D1 is close to the sampling resistor (3). The first input terminal of the second operational amplifier module (51) is connected to the negative terminal of the first diode D1. The second input terminal of the second operational amplifier module (51) is connected to the positive terminal of the first diode D1 and one end of the first current limiting resistor R1. The output terminal of the second operational amplifier module (51) is connected to the i-th resistance temperature acquisition terminal of the controller (1). The negative terminal of the first diode D1 is grounded. The other end of the first current limiting resistor R1 is connected to the i-th driving terminal of the driver (2).

4. The current detection device for the bridge drive circuit according to claim 1, characterized in that: The switching transistor temperature detection circuit (6) includes a third operational amplifier module (61), a second diode D2, and a second current-limiting resistor R2. The second diode D2 is close to the first switching transistor (8). The first input terminal of the third operational amplifier module (61) is connected to the negative terminal of the second diode D2. The second input terminal of the third operational amplifier module (61) is connected to the positive terminal of the second diode D2 and one end of the second current-limiting resistor R2. The output terminal of the third operational amplifier module (61) is connected to the i-th switching transistor temperature acquisition terminal of the controller (1). The negative terminal of the second diode D2 is grounded. The other end of the second current-limiting resistor R2 is connected to the i-th driving terminal of the driver (2).

5. The current detection device for the bridge drive circuit according to claim 1, characterized in that: The switching transistor conduction voltage acquisition circuit (7) is a fourth operational amplifier module. The first input terminal of the fourth operational amplifier module is connected to the source of the first switching transistor (8), the second input terminal is connected to the drain of the first switching transistor (8), and the output terminal is connected to the i-th switching transistor conduction voltage acquisition terminal of the controller (1).

6. A current detection method for a bridge drive circuit, employing the current detection device as described in any one of claims 1 to 5, characterized in that, The method includes: When the i-th drive loop is connected, the controller (1) performs the following steps: The temperature T1 of the sampling resistor (3) is determined based on the collected value input at its i-th resistor temperature acquisition terminal, and the resistance value Rc of the sampling resistor (3) is determined based on the temperature T1 of the sampling resistor (3). If U1>0, the first current I1 is calculated using the formula: I1= U1 / Rc; where U1 is the voltage value input to the i-th resistor voltage acquisition terminal of the controller (1); The temperature T2 of the first switch tube (8) is determined based on the collected value input from the temperature acquisition terminal of its i-th switch tube, and the on-resistance Rn of the first switch tube (8) is determined based on the temperature T2 of the first switch tube (8). If U2>0, then the second current I2 is calculated using the formula: I2= U2 / Rn; where U2 is the voltage value input to the i-th switch voltage acquisition terminal of the controller (1); If U1>0 and U2>0, then use the formula: I o =(I1+I2) / 2, calculate the current I of the i-th drive loop. o .

7. The current detection method for the bridge drive circuit according to claim 6, characterized in that: The method for determining the resistance value Rc of the sampling resistor (3) is as follows: consult the preset temperature-resistance table according to the temperature T1 of the sampling resistor (3) to obtain the resistance value corresponding to the temperature T1; take the resistance value corresponding to the temperature T1 as the resistance value Rc of the sampling resistor (3). The method for determining the on-resistance Rn of the first switch (8) is as follows: based on the temperature T2 of the first switch (8), look up the preset temperature-internal resistance table to obtain the internal resistance corresponding to temperature T2; and use the internal resistance corresponding to temperature T2 as the on-resistance Rn of the first switch (8). The preset temperature-resistance table is a table showing the correspondence between the temperature and resistance of the sampling resistor obtained through calibration; the preset temperature-internal resistance table is a table showing the correspondence between the temperature and on-state internal resistance of the first switching transistor obtained through calibration.

8. The current detection method for the bridge drive circuit according to claim 6, characterized in that: If U1≤0 and U2>0, then the second current I2 is taken as the current I of the i-th driving loop. o And control the sampling resistor voltage acquisition circuit (4) to stop working.

9. The current detection method for the bridge drive circuit according to claim 6, characterized in that: If U2≤0, the current detection of the i-th drive loop is stopped, the sampling resistor voltage acquisition circuit (4) is stopped, and the first switch (8) is turned off.

10. A car, characterized in that: The current detection device includes the bridge drive circuit as described in any one of claims 1 to 5.

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