Current detection device and method of bridge type driving circuit and automobile

Abstract

The invention discloses a current detection device and method for a bridge drive circuit and an automobile, and the device employs a sampling resistor and a first switching tube for sampling and detection of the current in a drive loop, and gives consideration to the influence of temperature, thereby improving the accuracy of current detection. When the sampling resistor is short-circuited, the first switching tube can be used for continuously sampling, so that the redundancy design is realized; and meanwhile, whether the driving circuit is open or whether the first switching tube is short-circuited can be judged according to the sampling results of the sampling resistor and the first switching tube, so that the reliability and the safety of the bridge type driving circuit are ensured.

Description

Technical Field

[0001] The present invention belongs to the field of automobile electrical equipment, and in particular relates to a current detection device and method for a bridge drive circuit and an automobile. Background Art

[0002] With the rapid development of automobile intelligence and electrification technology, new energy vehicles have put forward higher requirements for the reliability of drive circuits and the safety of systems. In the past, the current acquisition of bridge drive circuits mainly considered improving accuracy, but there was no response measure when the acquisition device itself failed. The result was that the circuit lost its function or the software made a wrong judgment or performed a wrong operation.

[0003] At present, the current detection of bridge drive circuits usually uses resistors as current sampling devices, namely sampling resistors. However, the real-time resistance of the sampling resistor will change with temperature, which is often ignored during data collection and conversion. In addition, the sampling resistor has three states: short circuit, open circuit, and resistance change. The existing current detection device cannot accurately determine whether to perform protection or continue data collection.

[0004] JP7087373B2 discloses a current detection circuit and a current detection method for a semiconductor device, which include: a current detection unit, 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 to detect a potential difference between the two ends of the first current detection resistor; a voltage detection unit, detecting the voltage across one of the first current detection resistors; a voltage determination unit, determining whether a detection voltage output from the voltage detection unit is equal to or higher than a first threshold voltage; a voltage level adjustment unit, adjusting a voltage level of a current detection voltage of the current detection terminal at least by a logic signal of a detection signal of the current detection unit and a voltage determination signal of the voltage determination unit; and an overcurrent detection unit, 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, the following problems still exist: (1) When the first current detection resistor is used as the sampling resistor, the effect of temperature on the resistance of the sampling resistor is not taken into account, resulting in the deviation between the sampling result and the actual value increasing with the increase of temperature; (2) When sampling using the first current detection resistor, it is impossible to determine whether the first current detection resistor itself has an abnormality (such as short circuit or open circuit), and the response strategy after the abnormality occurs is not considered; (3) Only the first current detection resistor is sampled (i.e., single resistor sampling), and sampling redundancy cannot be achieved. Summary of the invention

[0005] The object of the present 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 the first aspect, the current detection device of the bridge drive circuit described in the present invention includes a controller, a driver connected to the controller and n detection modules, wherein the i-th driving end of the driver is connected to the gate of the first switch tube in the i-th driving circuit, and the remaining driving ends of the driver are respectively connected to the gates of other switch tubes 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 switch tube temperature detection circuit and a switch tube conduction voltage acquisition circuit. The sampling resistor in the i-th detection module is connected in series to the bridge arm of the i-th driving circuit.

[0007] The sampling resistor temperature detection circuit in the i-th detection module is arranged close to the sampling resistor, and the input end of the sampling resistor temperature detection circuit is connected to the i-th driving end of the driver, and the output end is connected to the i-th resistor temperature acquisition end of the controller. The sampling resistor temperature detection circuit is used to detect the temperature near the sampling resistor (equivalent to detecting the temperature of the sampling resistor) and output the acquisition value (voltage) corresponding to the temperature of the sampling resistor to the controller.

[0008] The switch tube temperature detection circuit in the i-th detection module is arranged close to the first switch tube (i.e., in the i-th drive circuit), and the input end of the switch tube temperature detection circuit is connected to the i-th drive end of the driver, and the output end is connected to the i-th switch tube temperature collection end of the controller. The switch tube temperature detection circuit is used to detect the temperature near the first switch tube (equivalent to detecting the temperature of the first switch tube), and output the collection value (voltage) corresponding to the temperature of the first switch tube to the controller.

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

[0010] The switch tube conduction voltage acquisition circuit in the i-th detection module is connected in parallel with the first switch tube, and the output end of the switch tube conduction voltage acquisition circuit is connected to the i-th switch tube conduction voltage acquisition end of the controller. The switch tube conduction voltage acquisition circuit is used to collect the voltage value of the switch tube conduction (that is, the voltage drop between the drain and the source after the first switch tube is turned on) and transmit the voltage value to the controller.

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

[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 end of the first operational amplifier module is connected to one end of the sampling resistor through the first controllable switch S1, the second input end of the first operational amplifier module is connected to the other end of the sampling resistor through the second controllable switch S2, the output end of the first operational amplifier module is connected to the i-th resistor voltage acquisition end of the controller, and the controlled end of the first controllable switch S1 and the controlled end of the second controllable switch S2 are connected to the i-th resistor sampling control end 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, and the first diode D1 is close to the sampling resistor; the first input end of the second operational amplifier module is connected to the cathode of the first diode D1, the second input end of the second operational amplifier module is connected to the anode of the first diode D1 and one end of the first current limiting resistor R1, the output end of the second operational amplifier module is connected to the i-th resistor temperature collection end of the controller, the cathode 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 end of the driver.

[0014] Preferably, the switching tube temperature detection circuit includes a third operational amplifier module, a second diode D2 and a second current limiting resistor R2, and the second diode D2 is close to the first switching tube; the first input end of the third operational amplifier module is connected to the cathode of the second diode D2, the second input end of the third operational amplifier module is connected to the anode of the second diode D2 and one end of the second current limiting resistor R2, the output end of the third operational amplifier module is connected to the i-th switching tube temperature collection end of the controller, the cathode 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 end of the driver.

[0015] Preferably, the switch tube on-state voltage collection circuit is a fourth operational amplifier module, the first input end of the fourth operational amplifier module is connected to the source of the first switch tube, the second input end is connected to the drain of the first switch tube, and the output end is connected to the i-th switch tube on-state voltage collection end of the controller.

[0016] In a second aspect, the current detection method of the bridge drive circuit of the present invention adopts the current detection device of the bridge drive circuit, and the method comprises: when the i-th drive circuit is turned on (that is, the controller controls the driver to drive the corresponding switch tube to turn on to form the i-th drive circuit), the controller performs the following steps: The temperature T1 of the sampling resistor is determined according to the collected value inputted from the i-th resistor temperature collection terminal of the controller, and the resistance value Rc of the sampling resistor is determined according to the temperature T1 of the sampling resistor.

[0017] If U1>0, the first current I1 is calculated using the formula: I1= U1 / Rc; wherein U1 is the voltage value input to the i-th resistor voltage collection terminal of the controller.

[0018] The temperature T2 of the first switch tube is determined according to the collected value input by the i-th switch tube temperature collection terminal of the controller, and the on-state internal resistance Rn of the first switch tube is determined according to the temperature T2 of the first switch tube.

[0019] If U2>0, the second current I2 is calculated using the formula: I2= U2 / Rn; wherein U2 is the voltage value input to the on-state voltage collection terminal of the i-th switch tube of the controller.

[0020] If U1>0 and U2>0, then use the formula: I o =(I1+I2) / 2, calculate the current I of the i-th drive circuit o .

[0021] Preferably, the resistance value Rc of the sampling resistor is determined by: querying a preset temperature-resistance table according to the temperature T1 of the sampling resistor to obtain the resistance value corresponding to the temperature T1; and using the resistance value corresponding to the temperature T1 as the resistance value Rc of the sampling resistor. The on-state internal resistance Rn of the first switch tube is determined by: querying a preset temperature-resistance table according to the temperature T2 of the first switch tube to obtain the internal resistance corresponding to the temperature T2; and using the internal resistance corresponding to the temperature T2 as the on-state internal resistance Rn of the first switch tube. The preset temperature-resistance table is a table of correspondence between the temperature and the resistance value of the sampling resistor obtained by calibration; and the preset temperature-resistance table is a table of correspondence between the temperature and the on-state internal resistance of the first switch tube obtained by calibration.

[0022] Preferably, if U1≤0, and U2>0 (corresponding to the sampling resistor voltage acquisition circuit not sampling the voltage, but the switch tube conduction voltage acquisition circuit sampling the voltage, indicating that the sampling resistor has a short circuit fault), the second current I2 is used as the current I of the i-th drive circuit. o , and controls the sampling resistor voltage collection circuit to stop working, and the switch tube turns on the voltage collection circuit to continue the collection work.

[0023] Preferably, if U2≤0 (indicating that an open circuit fault occurs in the i-th drive circuit or a short circuit fault occurs in its first switch tube), current detection of the i-th drive circuit is stopped, the sampling resistor voltage acquisition circuit is controlled to stop working, and the first switch tube is controlled to be turned off.

[0024] In a third aspect, the automobile described in the present invention includes a current detection device for the above-mentioned bridge drive circuit.

[0025] The present invention utilizes a sampling resistor and a first switch tube to perform sampling, detects the current in a driving circuit, and takes the influence of temperature into consideration, thereby improving the accuracy of current detection; and when the sampling resistor is short-circuited, the first switch tube can be used to continue sampling, thereby realizing a redundant design; and at the same time, according to the sampling results of the sampling resistor and the first switch tube, it can also be determined whether the driving circuit is open-circuited or whether its first switch tube is short-circuited, thereby ensuring the reliability and safety of the bridge driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 4 is a circuit schematic diagram of a current detection device of an H-bridge driving circuit in an embodiment of the present invention.

[0027] Figure 2 4 is a flow chart of a current detection method when the first drive loop of the H-bridge drive circuit is turned on in an embodiment of the present invention.

[0028] Figure 3 4 is a flow chart of a current detection method when the second drive loop of the H-bridge drive circuit in an embodiment of the present invention is turned on. DETAILED DESCRIPTION

[0029] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present invention, the implementation of the embodiments of the present invention is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not intended to limit the embodiments of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0031] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be 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.

[0032] The bridge drive circuit mainly includes an H-bridge drive circuit, a half-bridge drive circuit and a three-phase full-bridge drive circuit. In this embodiment, the H-bridge drive circuit is used as an example for explanation. Figure 1As shown, the H-bridge drive circuit has four switch tubes, namely switch tube Q1, switch tube Q2, switch tube Q3, and switch tube Q4. Switch tube Q1 and switch tube Q2 are connected to form a first bridge arm, switch tube Q3 and switch tube Q4 are connected to form a second bridge arm, one end of load 9 is connected to the midpoint of the first bridge arm (i.e., the connection point of switch tube Q1 and switch tube Q2), and the other end of load 9 is connected to the midpoint of the second bridge arm (i.e., the connection point of switch tube Q3 and switch tube Q4). There are two drive loops in the H-bridge drive circuit, i.e., n=2. The first drive loop is formed by switch tube Q1, load 9, and switch tube Q4. The current flows out from the power supply VDD and passes through switch tube Q1, load 9, and switch tube Q4 to the ground in sequence. The second drive loop is formed by switch tube Q3, load 9, and switch tube Q2. The current flows out from the power supply VDD and passes through switch tube Q3, load 9, and switch tube Q2 to the ground in sequence. The first switch tube 8 in the first drive loop is switch tube Q1. The first switch tube 8 in the second driving loop is the switch tube Q3.

[0033] 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 tube 8 (i.e., switch tube Q1) in the first drive loop, the second drive terminal NA2 of the driver 2 is connected to the gate of the first switch tube 8 (i.e., switch tube Q3) in the second drive loop, the third drive terminal NA3 of the driver 2 is connected to the gate of the switch tube Q2, and the fourth drive terminal NA4 of the driver 2 is connected to the gate of the switch tube Q4.

[0034] Each detection module includes a sampling resistor 3, a sampling resistor voltage acquisition circuit 4, a sampling resistor temperature detection circuit 5, a switch tube temperature detection circuit 6 and a switch tube conduction voltage acquisition circuit 7.

[0035] 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 end 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 end of the first operational amplifier module 41 is connected to the other end of the sampling resistor 3 through the second controllable switch S2.

[0036] 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 end of the second operational amplifier module 51 is connected to the cathode of the first diode D1, the second input end 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.

[0037] In some embodiments, the switch tube 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 end of the third operational amplifier module 61 is connected to the cathode of the second diode D2, the second input end of the third operational amplifier module 61 is connected to the anode of the second diode D2 and one end of the second current limiting resistor R2, and the cathode of the second diode D2 is grounded.

[0038] In some embodiments, the switch tube conduction voltage acquisition circuit 7 is a fourth operational amplifier module.

[0039] For the first driving loop and the first detection module: the sampling resistor 3 is connected in series on the first bridge arm, and is located between the switch tube Q1 and the load 9. The first diode D1 is arranged close to the sampling resistor 3, the other end of the first current limiting resistor R1 (as the input end of the sampling resistor temperature detection circuit 5) is connected to the first driving end NA1 of the driver 2, and the output end of the second operational amplifier module 51 (as the output end of the sampling resistor temperature detection circuit 5) is connected to the first resistor temperature collection end EB1 of the controller 1. The second diode D2 is arranged close to the switch tube Q1, the other end of the second current limiting resistor R2 (as the input end of the switch tube temperature detection circuit 6) is connected to the first driving end NA1 of the driver 2, and the output end of the third operational amplifier module 61 (as the output end of the switch tube temperature detection circuit 6) is connected to the first switch tube temperature collection end EC1 of the controller 1. The output end of the first operational amplifier module 41 (as the output end of the sampling resistor voltage acquisition circuit 4) is connected to the first resistor voltage acquisition end EA1 of the controller 1, and the controlled end of the first controllable switch S1 and the controlled end of the second controllable switch S2 (as the controlled end of the sampling resistor voltage acquisition circuit 4) are connected to the first resistor sampling control end FA1 of the controller 1. The first input end of the fourth operational amplifier module is connected to the source of the switch tube Q1, the second input end of the fourth operational amplifier module is connected to the drain of the switch tube Q1, and the output end of the fourth operational amplifier module is connected to the first switch tube conduction voltage acquisition end ED1 of the controller 1.

[0040] For the second driving loop and the second detection module: the sampling resistor 3 is connected in series on the second bridge arm, and is located between the switch tube Q3 and the load 9. The first diode D1 is arranged close to the sampling resistor 3, the other end of the first current limiting resistor R1 (as the input end of the sampling resistor temperature detection circuit 5) is connected to the second driving end NA2 of the driver 2, and the output end of the second operational amplifier module 51 (as the output end of the sampling resistor temperature detection circuit 5) is connected to the second resistor temperature collection end EB2 of the controller 1. The second diode D2 is arranged close to the switch tube Q3, the other end of the second current limiting resistor R2 (as the input end of the switch tube temperature detection circuit 6) is connected to the second driving end NA2 of the driver 2, and the output end of the third operational amplifier module 61 (as the output end of the switch tube temperature detection circuit 6) is connected to the second switch tube temperature collection end EC2 of the controller 1. The output end of the first operational amplifier module 41 (as the output end of the sampling resistor voltage acquisition circuit 4) is connected to the second resistor voltage acquisition end EA2 of the controller 1, and the controlled end of the first controllable switch S1 and the controlled end of the second controllable switch S2 (as the controlled end of the sampling resistor voltage acquisition circuit 4) are connected to the second resistor sampling control end FA2 of the controller 1. The first input end of the fourth operational amplifier module is connected to the source of the switch tube Q3, the second input end of the fourth operational amplifier module is connected to the drain of the switch tube Q3, and the output end of the fourth operational amplifier module is connected to the second switch tube conduction voltage acquisition end ED2 of the controller 1.

[0041] 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 above-mentioned bridge drive circuit. The method is executed by the controller 1, including: a current detection method when the first drive circuit is connected and a current detection method when the second drive circuit is connected.

[0042] Controller 1 controls driver 2 to drive switch tube Q1 and switch tube Q4 to conduct to form the first drive loop; at this time, switch tube Q3 and switch tube Q2 are in the off state. The components described below refer to the components in the first detection module. For the first drive loop, controller 1 performs the following steps (see Figure 2 ): Step 1: determine the temperature T2 of the switch tube Q1 according to the collected value input by the first switch tube temperature collection terminal EC1 of the controller 1, determine the on-state internal resistance Rn of the switch tube Q1 according to the temperature T2 of the switch tube Q1, and then execute step 2.

[0043] Since the temperature and voltage drop of the second diode D2 form a negative linear curve, the voltage drop on the second diode D2 (i.e., the voltage collected by the first switch tube temperature collection terminal EC1 of the controller 1) can be measured to know the temperature of the second diode D2; and since the second diode D2 is arranged close to the switch tube Q1, the temperature of the second diode D2 is used as the temperature T2 of the switch tube Q1. The method of using a diode to measure temperature belongs to the prior art.

[0044] In some embodiments, the on-state internal resistance Rn of the switch tube Q1 is determined by: querying a preset temperature-internal resistance table according to the temperature T2 of the switch tube Q1 to obtain the internal resistance corresponding to the temperature T2; and using the internal resistance corresponding to the temperature T2 as the on-state internal resistance Rn of the switch tube Q1. The preset temperature-internal resistance table is a corresponding relationship table between the temperature and the on-state internal resistance of the first switch tube (here, the switch tube Q1) obtained by calibration.

[0045] Step 2: Determine whether U2>0, if yes, execute step 4, otherwise (ie, when U2≤0), execute step 3. Wherein, U2 is the voltage value inputted by the first switch tube conduction voltage acquisition terminal ED1 of the controller 1.

[0046] Step 3: stop the current detection of the first driving circuit, control the first controllable switch S1 to be turned off, control the second controllable switch S2 to be turned off, control the switch tube Q1 and the switch tube Q4 to be turned off, and then end.

[0047] Step 4: Use the formula: I2= U2 / Rn to calculate the second current I2, and then execute step 5.

[0048] Step 5: determine the temperature T1 of the sampling resistor 3 according to the collected value input by the first resistance temperature collection terminal EB1 of the controller 1 , determine the resistance value Rc of the sampling resistor 3 according to the temperature T1 of the sampling resistor 3 , and then execute step 6.

[0049] Since the temperature and voltage drop of the first diode D1 form a negative linear curve, the voltage drop on the first diode D1 (i.e., the voltage collected by the first resistor temperature collection terminal EB1 of the controller 1) can be measured to know the temperature of the first diode D1; and since the first diode D1 is arranged close to the sampling resistor 3, the temperature of the first diode D1 is used as the temperature T1 of the sampling resistor 3. The method of measuring temperature using a diode belongs to the prior art.

[0050] In some embodiments, the resistance Rc of the sampling resistor 3 is determined by: querying a preset temperature-resistance table according to the temperature T1 of the sampling resistor 3 to obtain a resistance corresponding to the temperature T1; and using the resistance corresponding to the temperature T1 as the resistance Rc of the sampling resistor 3. The preset temperature-resistance table is a table of correspondence between the temperature and resistance of the sampling resistor obtained by calibration.

[0051] Step 6: Determine whether U1>0, if yes, execute step 8, otherwise (ie when U1≤0), execute step 7. Wherein, U1 is the voltage value inputted by the first resistor voltage acquisition terminal EA1 of the controller 1.

[0052] Step 7: Use the second current I2 as the current I of the first drive circuit o , and control the first controllable switch S1 to be turned off, the second controllable switch S2 to be turned off, and then return to execute step 1.

[0053] Step 8. Use the formula: I1= U1 / Rc to calculate the first current I1, and then execute step 9.

[0054] Step 9: Use formula: I o =(I1+I2) / 2, calculate the current I of the first drive circuit o , then return to step 1.

[0055] Controller 1 controls driver 2 to drive switch tube Q3 and switch tube Q2 to conduct to form the second drive loop; at this time, switch tube Q1 and switch tube Q4 are in the off state. The components described below refer to the components in the second detection module. For the second drive loop, controller 1 performs the following steps (see Figure 3 ): Step 1: determine the temperature T2 of the switch tube Q3 according to the collected value input by the second switch tube temperature collection terminal EC2 of the controller 1, determine the on-state internal resistance Rn of the switch tube Q3 according to the temperature T2 of the switch tube Q3, and then execute step 2.

[0056] Since the temperature and voltage drop of the second diode D2 form a negative linear curve, the voltage drop on the second diode D2 (i.e., the voltage collected by the second switch tube temperature collection terminal EC2 of the controller 1) can be measured to know the temperature of the second diode D2; and since the second diode D2 is arranged close to the switch tube Q3, the temperature of the second diode D2 is used as the temperature T2 of the switch tube Q3. The method of using a diode to measure temperature belongs to the prior art.

[0057] In some embodiments, the on-state internal resistance Rn of the switch tube Q3 is determined by: querying a preset temperature-internal resistance table according to the temperature T2 of the switch tube Q3 to obtain the internal resistance corresponding to the temperature T2; and using the internal resistance corresponding to the temperature T2 as the on-state internal resistance Rn of the switch tube Q3. The preset temperature-internal resistance table is a table of corresponding relations between the temperature and the on-state internal resistance of the first switch tube (here, the switch tube Q3) obtained by calibration.

[0058] Step 2: Determine whether U2>0, if yes, execute step 4, otherwise (ie, when U2≤0), execute step 3. Wherein, U2 is the voltage value inputted by the second switch tube conduction voltage acquisition terminal ED2 of the controller 1.

[0059] Step 3: stop the current detection of the second driving circuit, control the first controllable switch S1 to be turned off, control the second controllable switch S2 to be turned off, control the switch tube Q3 and the switch tube Q2 to be turned off, and then end.

[0060] Step 4: Use the formula: I2= U2 / Rn to calculate the second current I2, and then execute step 5.

[0061] Step 5: determine the temperature T1 of the sampling resistor 3 according to the collected value input by the second resistor temperature collection terminal EB2, determine the resistance Rc of the sampling resistor 3 according to the temperature T1 of the sampling resistor 3, and then execute step 6.

[0062] Since the temperature and voltage drop of the first diode D1 form a negative linear curve, the voltage drop on the first diode D1 (i.e., the voltage collected by the second resistor temperature collection terminal EB2 of the controller 1) can be measured to know the temperature of the first diode D1; and since the first diode D1 is arranged close to the sampling resistor 3, the temperature of the first diode D1 is used as the temperature T1 of the sampling resistor 3. The method of measuring temperature using a diode belongs to the prior art.

[0063] In some embodiments, the resistance Rc of the sampling resistor 3 is determined by: querying a preset temperature-resistance table according to the temperature T1 of the sampling resistor 3 to obtain a resistance corresponding to the temperature T1; and using the resistance corresponding to the temperature T1 as the resistance Rc of the sampling resistor 3. The preset temperature-resistance table is a table of correspondence between the temperature and resistance of the sampling resistor obtained by calibration.

[0064] Step 6: Determine whether U1>0, if yes, execute step 8, otherwise (ie when U1≤0), execute step 7. Wherein, U1 is the voltage value inputted by the second resistor voltage acquisition terminal EA2 of the controller 1.

[0065] Step 7: Use the second current I2 as the current I of the second drive circuit o , and control the first controllable switch S1 to be turned off, the second controllable switch S2 to be turned off, and then return to execute step 1.

[0066] Step 8. Use the formula: I1= U1 / Rc to calculate the first current I1, and then execute step 9.

[0067] Step 9: Use formula: I o =(I1+I2) / 2, calculate the current I of the second drive circuit o , then return to step 1.

[0068] In addition, for the half-bridge drive circuit, although it only has two switch tubes, such as switch tube Q1 and switch tube Q2, it still has two drive loops. The first switch tube in the first drive loop is switch tube Q1, and the first drive loop is formed by switch tube Q1 and the load. The current flows out from the power supply VDD, and passes through the switch tube Q1 and the load to the ground in sequence. The first switch tube in the second drive loop is switch tube Q2, and the second drive loop is formed by switch tube Q2 and the load. The current flows out from the power supply VDD, and passes through the load and switch tube Q2 to the ground in sequence. Its circuit detection device and detection method are similar to the above description and will not be repeated here.

[0069] An embodiment of the present invention further provides a car, which includes the current detection device of the bridge drive circuit.

[0070] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope 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 an i-th driving end of the driver (2) is connected to a gate of a first switch tube (8) in an i-th driving 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 switch tube temperature detection circuit (6) and a switch tube conduction voltage acquisition circuit (7); the sampling resistor (3) in the i-th detection module is connected in series to 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 the input end is connected to the i-th drive end of the driver (2), and the output end is connected to the i-th resistor temperature acquisition end of the controller (1), and the switch tube temperature detection circuit (6) is close to the first switch tube (8 ), and the input end is connected to the i-th driving end of the driver (2), the output end is connected to the i-th switch tube temperature collection end of the controller (1), the sampling resistor voltage collection circuit (4) is connected in parallel with the sampling resistor (3), the controlled end is connected to the i-th resistor sampling control end of the controller (1), the output end is connected to the i-th resistor voltage collection end of the controller (1), and the switch tube conduction voltage collection circuit (7) is connected in parallel with the first switch tube (8), and the output end is connected to the i-th switch tube conduction voltage collection end of the controller (1); wherein n represents the number of drive loops in the bridge drive circuit, and i is all integers from 1 to n in sequence.

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

3. The current detection device of the bridge drive circuit according to claim 1, characterized in that: The sampling resistor temperature detection circuit (5) comprises a second operational amplifier module (51), a first diode D1 and a first current limiting resistor R1, wherein the first diode D1 is close to the sampling resistor (3); a first input end of the second operational amplifier module (51) is connected to the cathode of the first diode D1, a second input end 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, an output end of the second operational amplifier module (51) is connected to the i-th resistor temperature collection end of the controller (1), a cathode of the first diode D1 is grounded, and the other end of the first current limiting resistor R1 is connected to the i-th drive end of the driver (2).

4. The current detection device of the bridge drive circuit according to claim 1, characterized in that: The switch tube temperature detection circuit (6) comprises a third operational amplifier module (61), a second diode D2 and a second current limiting resistor R2, the second diode D2 being close to the first switch tube (8); the first input end of the third operational amplifier module (61) is connected to the cathode of the second diode D2, the second input end of the third operational amplifier module (61) is connected to the anode of the second diode D2 and one end of the second current limiting resistor R2, the output end of the third operational amplifier module (61) is connected to the i-th switch tube temperature collection end of the controller (1), the cathode of the second diode D2 is grounded, and the other end of the second current limiting resistor R2 is connected to the i-th drive end of the driver (2).

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

6. A current detection method for a bridge drive circuit, using the current detection device according to any one of claims 1 to 5, characterized in that: The method includes: When the i-th drive circuit is turned on, the controller (1) performs the following steps: Determine the temperature T1 of the sampling resistor (3) according to the collected value inputted from the i-th resistor temperature collection terminal, and determine the resistance value Rc of the sampling resistor (3) according to the temperature T1 of the sampling resistor (3); If U1>0, the first current I1 is calculated using the formula: I1= U1 / Rc; wherein U1 is the voltage value input to the i-th resistor voltage collection terminal of the controller (1); Determining the temperature T2 of the first switch tube (8) according to the collected value inputted by the i-th switch tube temperature collection terminal, and determining the on-state internal resistance Rn of the first switch tube (8) according to the temperature T2 of the first switch tube (8); If U2>0, the second current I2 is calculated using the formula: I2= U2 / Rn; wherein U2 is the voltage value input to the on-state voltage collection terminal of the i-th switch tube 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 circuit o .

7. The current detection method of 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: according to the temperature T1 of the sampling resistor (3), a preset temperature-resistance table is searched to obtain the resistance value corresponding to the temperature T1; and the resistance value corresponding to the temperature T1 is used as the resistance value Rc of the sampling resistor (3); The method for determining the on-state internal resistance Rn of the first switch tube (8) is as follows: according to the temperature T2 of the first switch tube (8), a preset temperature-internal resistance table is searched to obtain the internal resistance corresponding to the temperature T2; and the internal resistance corresponding to the temperature T2 is used as the on-state internal resistance Rn of the first switch tube (8); The preset temperature-resistance table is a table of correspondence between the temperature and the resistance of the sampling resistor obtained through calibration; the preset temperature-internal resistance table is a table of correspondence between the temperature and the on-state internal resistance of the first switching tube obtained through calibration.

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

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

10. An automobile, characterized in that: A current detection device comprising a bridge drive circuit as claimed in any one of claims 1 to 5.

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