A method for detecting and protecting abnormality of a resolver excitation signal

Abstract

The present invention relates to a method for detecting and protecting abnormality of a resolver excitation signal, the method comprising: setting a duty cycle based on the output of an excitation output signal detection circuit; judging the fault type based on the duty cycle; performing protection based on the fault type and displaying the fault signal. The present invention can detect the full working conditions of various excitation output signals through an excitation amplification circuit, an excitation signal abnormality detection and protection circuit, and an excitation output signal detection circuit, distinguish the resolver fault type, and provide a corresponding solution.

Description

Technical Field

[0001] The present invention relates to the technical field of excitation signal protection, and in particular to a method for detecting and protecting anomalies of a resolver excitation signal. Background Art

[0002] The resolver chip is used to generate a fixed-frequency sinusoidal excitation signal with a certain voltage bias. The resolver is a transformer used to determine the rotor position of the permanent magnet synchronous motor. It rotates with the rotor and has three sets of coils. The excitation coil is used to generate an excitation magnetic field. The positive differential coil and the cosine differential coil induce different voltage signals with the different rotor positions, which are sent to the resolver chip to decode the motor position and speed. The resolver excitation signal is used to drive the excitation coil of the resolver. The resolver excitation signal abnormality refers to the distortion of the resolver excitation signal and the short circuit of the resolver excitation signal. When the resolver circuit works abnormally, it will cause the motor to work abnormally, which poses an application risk. If the resolver abnormal state is not protected, the circuit may be irreparably damaged. The resolver excitation output signal is a key signal for driving the resolver excitation coil. The distortion of this signal affects the motor rotor position and motor control.

[0003] Chinese patent CN107834515B discloses a resolver excitation system and its short-circuit protection circuit and method, which are used to detect whether a short-circuit fault occurs in the resolver excitation system. When a short-circuit fault occurs in the resolver excitation system, the excitation power amplifier circuit in the resolver excitation system is controlled to stop outputting the excitation signal, and the output current of the system is pulled down to near zero, thereby avoiding the problem of serious heating caused by a large current flowing through the device; and outputting a fault state feedback signal to the controller of the resolver excitation system, so that the controller stops outputting the initial excitation signal and enters a protection state. This patent only protects the excitation output signal from being short-circuited to the ground. Since the protection circuit is implemented by hardware, it is easy to misprotect when interference occurs, and there is no excitation output distortion signal detection circuit, so it is impossible to detect and process the excitation output signal short-circuited to a high voltage and the excitation output signal distortion signal, and it is impossible to detect and protect the excitation output signal under all working conditions.

[0004] Chinese patent CN109802357B discloses a resolver excitation circuit with hiccup protection, including an operational amplifier circuit and a push-pull power amplifier circuit connected in sequence, two reverse series diodes are added at the base of the power amplifier triode of the push-pull power amplifier circuit, and the power supply provides current through the reverse series diodes, so that the push-pull power amplifier circuit can be controlled to be turned on and off by the reverse series diodes, thereby achieving the purpose of controlling the positive and negative excitation output of the resolver. The present invention performs short-circuit protection on the resolver excitation circuit by controlling the on and off of the push-pull power amplifier circuit, protects the power amplifier triode, simplifies the control strategy, and saves circuit cost; the patent ensures that the triode of the push-pull power amplifier circuit is completely turned off when the resolver excitation is short-circuited to the ground or to the power supply through the hiccup design of the short-circuit protection control signal, and further protects the resolver excitation circuit. The patent controls the opening and closing of the push-pull power amplifier circuit by hiccups, so that the system can intermittently open and connect the power supply when the output is short-circuited, so as to achieve the purpose of intermittent output of the system and control heating. However, the defect of this patent is that even if the system outputs intermittently, large current will still flow through the internal components during output, and the problem of component heating has not been solved.

[0005] There is also an excitation protection based on the output of the resolver hardware decoding chip in the prior art. When an excitation short circuit occurs, this technology causes the resolver hardware decoding chip to continue sending excitation, and its protection circuit can only passively implement protection actions, so that the protection of the entire system falls far behind the moment when the excitation short circuit occurs. The controller can only determine that the resolver is not working normally through the resolver decoding signal.

[0006] The power supply of the resolver chip of the present invention is controlled by a switch tube. When the resolver excitation output distortion and short circuit are detected, the resolver chip power supply switch is disconnected in time. The resolver chip generates an excitation signal, which is passed through a push-pull amplifier circuit to generate an excitation output signal with a certain driving capability. The comparator sets a suitable comparison level to detect the excitation output signal. The NAND gate circuit is used to filter the interference signal. The microcontroller and the detection signal jointly control the transistor of the excitation amplifier circuit to turn off, thereby protecting the excitation amplifier circuit. The microcontroller determines the fault type by judging the detection signal and protects the resolver system. When the resolver signal is abnormal, the present invention can perform system protection on the resolver circuit to prevent further damage caused by the abnormality, and can give the type of fault and perform protection according to the type.

[0007] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventor studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the invention

[0008] In view of the deficiencies in the prior art, the technical solution of the present invention is to provide a method for detecting and protecting abnormalities in a resolver excitation signal, characterized in that the method comprises: setting a duty cycle based on the output of an excitation output signal detection circuit; judging a fault type based on the duty cycle; performing protection based on the fault type and displaying a fault signal.

[0009] According to a preferred embodiment, the excitation signal generates the excitation output signal having driving capability through an excitation amplifier circuit, and the setting of the duty cycle includes: setting the first threshold value as a normal duty cycle.

[0010] According to a preferred implementation, the excitation output signal detection circuit uses a comparator and sets a reference voltage Vref to perform duty cycle judgment, wherein the reference voltage Vref formula is:

[0011]

[0012] R20 is the resistance value of the twentieth resistor, R21 is the twenty-first resistor, and V0 is the power supply voltage connected to the twentieth resistor.

[0013] According to a preferred embodiment, the fault type judgment based on the duty cycle includes: judging whether the current value of the duty cycle is equal to the first threshold; if the duty cycle is equal to the first threshold, the excitation output signal is normal; if the current value of the duty cycle deviates from the first threshold, that is, it is less than or greater than the first threshold and the number of occurrences is greater than or equal to 2 times, the excitation output signal is in the first fault state; if the duty cycle is continuously the second threshold, the excitation output signal is in the second fault state; if the duty cycle is continuously the third threshold, the excitation output signal is in the third fault state.

[0014] According to a preferred embodiment, the first threshold value refers to the reference voltage Vref set based on the excitation output signal detection circuit as the reference point of the comparator, that is, the duty cycle is 50%. The second threshold value refers to the comparator outputting a high level after the excitation output signal and the reference voltage Vref pass through the comparator, that is, the duty cycle is 100%. The third threshold value refers to the comparator outputting a low level after the excitation output signal and the reference voltage Vref pass through the comparator, that is, the duty cycle is a low level. The continuous duty cycle means that the duty cycle keeps the current value unchanged within the first time period, and the first time period is two cycles after the excitation output signal and the reference voltage Vref pass through the comparator. Preferably, the first fault state refers to the distortion of the excitation output signal, the second fault state refers to the short circuit of the excitation output signal to the ground, and the third fault state refers to the short circuit of the excitation output signal to the high voltage. The present invention refines the possible fault states of the excitation output signal based on the duty cycle and provides corresponding detection methods, so that the full working conditions of various excitation output signals can be detected and the types of resolver faults can be distinguished.

[0015] According to a preferred embodiment, the excitation output signal is distorted. When the third excitation output signal distortion occurs, the driving voltage of the NPN transistor of the excitation amplifier circuit is turned off and the PNP transistor of the excitation amplifier circuit is turned off through a control signal. At the same time, the power supply is disconnected, and the fault signal is displayed to accurately identify the cause of the short circuit.

[0016] According to a preferred embodiment, when the excitation output signal is short-circuited to ground or the excitation output signal is short-circuited to a high voltage, the power supply and the excitation signal amplifying circuit are shut down, and a fault signal is displayed to accurately identify the cause of the short circuit.

[0017] The present invention also relates to a resolver excitation signal abnormality detection and protection system, characterized in that the system comprises: a resolver chip, a switch tube, a microcontroller, an excitation amplifier circuit and an excitation signal abnormality detection and protection circuit, the resolver chip is used to generate a fixed-frequency sinusoidal excitation signal with a voltage bias, the switch tube is used to disconnect the resolver chip power supply switch when the resolver excitation output is detected to be distorted or short-circuited, and the microcontroller is used to detect the state of the excitation output signal and send a control signal.

[0018] According to a preferred embodiment, the excitation amplifier circuit includes: a capacitor, a first comparator, a first triode, a second triode, a first diode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor, wherein:

[0019] One end of the first resistor is connected to the resolver chip, and is used to send the excitation signal sent by the resolver chip to the first comparator, and the other end of the first resistor is connected to the capacitor and the fourth resistor;

[0020] One end of the second resistor is connected to the power supply, and the other end is connected to the positive end of the first comparator; one end of the third resistor is grounded, and the other end is connected to the positive end of the first comparator; the second resistor and the third resistor together form a threshold of the first comparator;

[0021] The fourth resistor and the capacitor are connected in parallel to the first resistor and one end of the first comparator. In the operational amplifier circuit, the fourth resistor serves as a feedback resistor of the feedback end of the first comparator. The fourth resistor plays a role in adjusting the amplification factor and is connected in parallel with the capacitor to form a low-pass filter and a phase compensation function to prevent self-excitation due to the addition of a zero point.

[0022] One end of the fifth resistor is connected to the power supply and the collector of the first transistor, and the other end of the fifth resistor is connected to one end of the sixth resistor and the base of the first transistor;

[0023] The other end of the sixth resistor is connected to one end of the seventh resistor via the first diode and the second diode in sequence;

[0024] The other end of the seventh resistor is connected to one end of the eighth resistor and the base of the second transistor;

[0025] The other end of the eighth resistor and the emitter of the second triode are both grounded;

[0026] The emitter of the first transistor is connected to the collector of the second transistor through the ninth resistor and the tenth resistor in sequence;

[0027] The connection point between the first diode and the second diode is the output terminal of the first comparator;

[0028] The connection point between the ninth resistor and the tenth resistor is the output end of the resolver excitation signal amplifying circuit.

[0029] According to a preferred embodiment, when the excitation output signal is distorted for the third time, the microcontroller sets the input terminal of the NAND gate to a high level, the hardware automatically turns off the driving voltage of the NPN transistor of the excitation amplifier circuit, and the microcontroller sends a control signal to turn off the PNP transistor of the excitation amplifier circuit. At the same time, the microcontroller disconnects the power supply of the resolver chip and the connection between the resolver chip, and displays the fault signal to accurately find out the cause of the short circuit; when the excitation output signal is short-circuited, the microcontroller detects the short-circuit signal, turns off the power supply of the resolver chip and the excitation amplifier circuit, protects the excitation amplifier circuit, and displays the fault signal to accurately find out the cause of the short circuit.

[0030] According to a preferred embodiment, the resolver excitation signal abnormality detection and protection circuit includes: a second comparator, a third transistor, a fourth transistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a logic NAND gate and a microcontroller, wherein:

[0031] One end of the eleventh resistor is connected to the output end of the resolver excitation signal amplifier circuit, and the other end is connected to the second comparator, and is used to send the excitation signal after passing through the amplifier circuit to the second comparator;

[0032] One end of the twelfth resistor is connected to the power supply, and the other end is connected to the positive terminal of the second comparator; one end of the thirteenth resistor is grounded, and the other end is connected to the positive terminal of the second comparator; the twelfth resistor and the thirteenth resistor together form a threshold of the second comparator;

[0033] One end of the fourteenth resistor is connected to the power supply, and the other end is connected to the output end of the second comparator;

[0034] One end of the fifteenth resistor is connected to the base of the second triode in the resolver excitation signal amplifying circuit, and the other end is connected to the collector of the third triode;

[0035] One end of the sixteenth resistor is connected to the base of the third transistor, and the other end is connected to the switch tube and the microcontroller;

[0036] One end of the seventeenth resistor is connected to the base of the first transistor in the resolver excitation signal amplifying circuit, and the other end is connected to the collector of the fourth transistor;

[0037] One end of the eighteenth resistor is connected to the base of the fourth transistor, and the other end is connected to the logic NAND gate;

[0038] The emitters of the third transistor and the fourth transistor are both grounded.

[0039] Beneficial technical effects of the present invention:

[0040] (1) By setting the duty cycle based on the output of the excitation output signal detection circuit, the distortion of various excitation output signals is detected, and the interference signal is filtered according to the number of distorted signals within a certain period of time (the duty cycle appears twice less than 50% and / or greater than 50%), the distortion of the excitation output signal is accurately detected, and the connection between the resolver chip and the resolver power supply is disconnected in time.

[0041] (2) Detect the short circuit of the excitation output signal to the ground or to a high voltage, and determine whether it is an interference signal based on whether the detection signal recovers within a certain period of time (if the duty cycle is continuously 100% or is at a low level, the excitation output signal is short-circuited to the ground or to a high voltage), accurately detect the short circuit of the excitation output signal, and protect the excitation amplifier circuit.

[0042] (3) The excitation output signal is detected by setting the appropriate comparison level through the microcontroller and comparator, and the interference signal is filtered out by the logic NAND gate. The microcontroller and the check signal jointly control the transistor shutdown of the excitation amplifier circuit, which solves the problem of easy misprotection when the resolver excitation signal is interfered.

[0043] The present invention can detect all working conditions of various excitation output signals through an excitation amplifier circuit, an excitation signal abnormality detection and protection circuit, and an excitation output signal detection circuit, distinguish the type of resolver fault and provide corresponding solutions. In addition, the addition of a microcontroller and a logic NAND gate makes the protection circuit not entirely composed of hardware, thereby solving the problem of easy misprotection when interference occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a basic circuit principle diagram of a preferred embodiment of a resolver excitation output signal amplification circuit, a detection circuit, and a protection circuit of the present invention;

[0045] Figure 2 is a waveform diagram of an excitation output signal of the present invention;

[0046] Figure 3 It is a basic circuit principle diagram of the excitation output signal of the present invention;

[0047] Figure 4 It is a duty cycle output waveform diagram when the detection circuit of the present invention detects that the excitation output signal is in a normal state;

[0048] Figure 5 It is an output waveform diagram of the abnormal state 1 of the resolver excitation output signal of the present invention, in which the duty cycle is less than 50%;

[0049] Figure 6 It is an output waveform diagram of the abnormal state 2 of the resolver excitation output signal of the present invention when the duty cycle is greater than 50%;

[0050] Figure 7 The output waveform diagram of the abnormal state 3 of the resolver excitation output signal of the present invention, in which the duty ratio is greater than 50% and less than 50%;

[0051] Figure 8 It is an output waveform diagram of the resolver excitation output signal of the present invention when it is short-circuited to the ground and outputs a 100% duty cycle;

[0052] Fig. 9 It is an output waveform diagram of the resolver excitation output signal of the present invention when it is short-circuited to a high voltage output low level.

[0053] Reference numerals list

[0054] R1: the first resistor; R2: the second resistor; R3: the third resistor; R4: the fourth resistor; R5: the fifth resistor; R6: the sixth resistor; R7: the seventh resistor; R8: the eighth resistor; R9: the ninth resistor; R10: the tenth resistor; R11: the eleventh resistor; R12: the twelfth resistor; R13: the thirteenth resistor; R14: the fourteenth resistor; R15: the fifteenth resistor; R16: the sixteenth resistor; R17: the seventeenth resistor; R18: the eighteenth resistor; R19: the nineteenth resistor; R20: the twentieth resistor; R21: the twenty-first resistor; R22: the twenty-second resistor; capacitor: C; the first comparator: A1; the second comparator: A2; the third comparator: A3; the first transistor: Q1; the second transistor: Q2; the third transistor: Q3; the fourth transistor: Q4; the first diode: D1; the second diode: D2; the first logic NAND gate: UA; the second logic NAND gate UB. DETAILED DESCRIPTION

[0055] The following is a detailed description with reference to the accompanying drawings.

[0056] In the prior art, the circuit for short-circuit protection of the resolver excitation output signal only protects the excitation output signal from being short-circuited to the ground. Since the protection circuit is implemented by hardware, it is easy to misprotect when interference occurs, and there is no detection circuit for the excitation output distortion signal, so it is impossible to detect and process the excitation output signal short-circuited to a high voltage and the excitation output signal distortion signal, and it is impossible to detect and protect the excitation output signal under all working conditions. The resolver chip is used to generate a sinusoidal excitation signal with a certain voltage bias at a fixed frequency. The resolver is a transformer used to determine the rotor position of the permanent magnet synchronous motor. It rotates with the rotor and has three sets of coils. The excitation coil is used to generate an excitation magnetic field. The positive differential coil and the cosine differential coil induce different voltage signals with different rotor positions, which are sent to the resolver chip to decode the motor position and speed. The resolver excitation signal is used to drive the excitation coil of the resolver. The resolver excitation signal is abnormal, the resolver excitation signal is distorted, and the resolver excitation signal is short-circuited.

[0057] The duty cycle in the present invention refers to the percentage of the time that the excitation output signal voltage is lower than the reference voltage Vref in one cycle of the comparator.

[0058] Example 1

[0059] The present application relates to a method for detecting and protecting abnormality of a resolver excitation signal, the method comprising:

[0060] The duty cycle of the detection circuit output is set based on the excitation output signal; the fault type is determined based on the duty cycle; protection is performed based on the fault type and the fault signal is displayed.

[0061] According to a preferred embodiment, the excitation signal generates the excitation output signal having driving capability through an excitation amplifier circuit, and the setting of the duty cycle includes: setting 50% as a normal duty cycle.

[0062] According to a preferred implementation, the excitation output signal detection circuit uses a comparator and sets a reference voltage Vref to perform duty cycle judgment, wherein the reference voltage Vref formula is:

[0063]

[0064] R20 is the resistance value of the twentieth resistor, R21 is the twenty-first resistor, and V0 is the power supply voltage connected to the twentieth resistor.

[0065] According to a preferred embodiment, the fault type judgment based on the duty cycle includes: judging whether the duty cycle is equal to 50%; if the duty cycle is equal to 50%, the excitation output signal is normal; if the duty cycle is less than 50% and / or greater than 50% twice, the excitation output signal is distorted; if the duty cycle is continuously 100%, the excitation output signal is short-circuited to ground; if the duty cycle is continuously at a low level, the excitation output signal is short-circuited to a high voltage.

[0066] According to a preferred embodiment, the excitation output signal is distorted. When the third excitation output signal distortion occurs, the driving voltage of the NPN transistor of the excitation amplifier circuit is turned off and the PNP transistor of the excitation amplifier circuit is turned off through a control signal. At the same time, the power supply is disconnected, and the fault signal is displayed to accurately identify the cause of the short circuit.

[0067] According to a preferred embodiment, when the excitation output signal is short-circuited to ground or the excitation output signal is short-circuited to a high voltage, the power supply and the excitation signal amplifying circuit are shut down, and a fault signal is displayed to accurately identify the cause of the short circuit.

[0068] Example 2

[0069] The present invention also relates to a resolver excitation signal abnormality detection and protection system, the system comprising: a resolver chip, a switch tube, a microcontroller, an excitation amplifier circuit and an excitation signal abnormality detection and protection circuit, the resolver chip is used to generate a fixed-frequency sinusoidal excitation signal with a voltage bias, the switch tube is used to disconnect the resolver chip power supply switch when the resolver excitation output is detected to be distorted or short-circuited, and the microcontroller is used to detect the state of the excitation output signal and send a control signal.

[0070] Figure 1The resolver excitation signal amplification circuit, detection and protection circuit are shown. The power supply of the resolver chip is controlled by a switch tube. When the resolver excitation output is distorted and short-circuited, the resolver chip power supply switch is disconnected in time; the resolver chip generates an excitation signal, which is passed through a push-pull amplifier circuit to generate an excitation output signal with a certain driving capability. The comparator sets a suitable comparison level to detect the excitation output signal. The NAND gate circuit is used to filter interference signals. The microcontroller and the detection signal jointly control the transistor shutdown of the excitation amplifier circuit to protect the excitation amplifier circuit. The microcontroller determines the fault type by judging the detection signal and protects the resolver system. The specific implementation method is as follows:

[0071] The microcontroller determines the duty cycle according to the output of the excitation output signal detection circuit and sets 50% as the normal duty cycle;

[0072] Is the duty cycle equal to 50%? If it is equal to 50%, there is no problem with the excitation output signal;

[0073] If the duty cycle is less than 50% or greater than 50% twice within a certain period of time, the microcontroller sets the NAND gate input terminal to a high level. When the third excitation output signal distortion occurs, the hardware automatically turns off the NPN transistor drive voltage of the excitation amplifier circuit, and the microcontroller sends a control signal to turn off the excitation amplifier circuit PNP. At the same time, the microcontroller disconnects the power supply of the resolver chip and the connection between the resolver chip;

[0074] The duty cycle is continuously at a low level or 100% for a certain period of time, confirming that the excitation output signal is short-circuited to the ground or high voltage. The microcontroller sends a signal to shut down the transistor of the excitation amplifier circuit to protect the excitation amplifier circuit and disconnect the power supply of the resolver chip and the resolver chip at the same time.

[0075] like Figure 1 The resolver excitation signal amplification circuit includes: a capacitor C, a first comparator A1, a first transistor Q1, a second transistor Q2, a first diode D1, a second diode D2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10, wherein:

[0076] One end of the first resistor R1 is connected to the resolver chip, and is used to send the excitation signal sent by the resolver chip to the first comparator A1. The other end of the first resistor R1 is connected to the capacitor C and the fourth resistor R4.

[0077] One end of the second resistor R2 is connected to the power supply, and the other end is connected to the positive end of the first comparator A1; one end of the third resistor R3 is grounded, and the other end is connected to the positive end of the first comparator A1; the second resistor R2 and the third resistor R3 together form a threshold of the first comparator A1;

[0078] The fourth resistor R4 and the capacitor C are connected in parallel to the first resistor and one end of the first comparator A1. In the operational amplifier circuit, the fourth resistor R4 serves as a feedback resistor of the feedback end of the first comparator A1. The fourth resistor R4 plays a role in adjusting the amplification factor and is connected in parallel with the capacitor C to form a low-pass filter and a phase compensation function to prevent self-excitation due to the addition of a zero point.

[0079] One end of the fifth resistor R5 is connected to the power supply and the collector of the first transistor Q1, and the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the base of the first transistor Q1;

[0080] The other end of the sixth resistor R6 is connected to one end of the seventh resistor R7 through the first diode D1 and the second diode D2 in sequence;

[0081] The other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and the base of the second transistor Q2;

[0082] The other end of the eighth resistor R8 and the emitter of the second transistor Q2 are both grounded;

[0083] The emitter of the first transistor Q1 is connected to the collector of the second transistor Q2 through the ninth resistor R9 and the tenth resistor R10 in sequence;

[0084] The connection point between the first diode D1 and the second diode D2 is the output terminal of the first comparator A1;

[0085] The connection point between the ninth resistor R9 and the tenth resistor R10 is the output end of the resolver excitation signal amplifying circuit.

[0086] The above-mentioned resolver excitation signal amplifier circuit is a circuit connected by two transistors of different polarities, using two power BJT tubes or MOSFET tubes with the same parameters, which exist in the circuit in a push-pull manner, each responsible for the waveform amplification task of the positive and negative half cycles. When the circuit is working, only one of the two symmetrical power switch tubes is turned on at a time, so the conduction loss is small and the efficiency is high. It should be noted that the first transistor Q1 is an NPN transistor, and the second transistor Q2 is a PNP transistor.

[0087] like Figure 1 The detection and protection circuit includes: a second comparator A2, a third transistor Q3, a fourth transistor Q4, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a NAND equivalent logic NAND gate UA, UB and a microcontroller, wherein:

[0088] One end of the eleventh resistor R11 is connected to the output end of the resolver excitation signal amplifier circuit, and the other end is connected to the second comparator A2, for sending the excitation signal after passing through the amplifier circuit to the second comparator A2;

[0089] One end of the twelfth resistor R12 is connected to the power supply, and the other end is connected to the positive end of the second comparator A2; one end of the thirteenth resistor R13 is grounded, and the other end is connected to the positive end of the second comparator A2; the twelfth resistor R12 and the thirteenth resistor R13 together form a threshold of the second comparator A2;

[0090] One end of the fourteenth resistor R14 is connected to the power supply, and the other end is connected to the output end of the second comparator A2;

[0091] One end of the fifteenth resistor R15 is connected to the base of the second triode Q2 in the resolver excitation signal amplifying circuit, and the other end is connected to the collector of the third triode Q3;

[0092] One end of the sixteenth resistor R16 is connected to the base of the third transistor Q3, and the other end is connected to the switch tube and the microcontroller;

[0093] One end of the seventeenth resistor R17 is connected to the base of the first transistor Q1 in the resolver excitation signal amplifying circuit, and the other end is connected to the collector of the fourth transistor Q4;

[0094] One end of the eighteenth resistor R18 is connected to the base of the fourth transistor Q4, and the other end is connected to the logic NAND gates UB and UA in sequence;

[0095] The emitters of the third transistor Q3 and the fourth transistor Q4 are both grounded.

[0096] The output end of the second logic NAND gate UB is connected to the eighteenth resistor R18, and the two input ends of the second logic NAND gate UB are short-circuited and connected to the output end of the first logic NAND gate UA; the input ends of the first logic NAND gate UA are respectively connected to the output end of the second comparator A2 and the control signal output end of the microcontroller. The two input ends of the second logic NAND gate UB are short-circuited to turn it into a logic NOT gate, and the different input conditions of the input ends of the first logic NAND gate UA filter out interference signals.

[0097] When the duty cycle is less than 50% or greater than 50% twice within a certain period of time, the microcontroller detects that the duty cycle of the excitation output signal (i.e., the number of distortions) is abnormal, and the microcontroller outputs a control signal to set one of the input terminals of the first logic NAND gate UA to a high level. When the excitation output signal is distorted for the third time, the second comparator outputs a high level, and the first logic NAND gate UA outputs a low level, and then the second logic NAND gate UB outputs a high level after the input terminal is short-circuited, so that the hardware automatically turns off the first triode Q1. At the same time, the microcontroller sends a control signal to turn off the second triode Q2, and disconnects the power supply of the resolver chip and the resolver chip through the switch tube, and displays the fault signal of the distortion of the excitation output signal detected at this time.

[0098] When the duty cycle is continuously 100%, the microcontroller determines whether it is an interference signal based on whether the detection signal is restored within a certain period of time. If so, the excitation output signal is normal, if not, the control signal is output. At this time, both input terminals of the first logic NAND gate UA are high level, and the hardware automatically turns off the first transistor Q1. At the same time, the microcontroller sends a control signal to turn off the second transistor Q2, and disconnects the power supply of the resolver chip and the connection between the resolver chip through the switch tube, and displays the fault signal of the excitation output signal detected at this time being short-circuited to the ground.

[0099] When the duty cycle is continuously at a low level, the microcontroller determines whether it is an interference signal based on whether the detection signal is restored within a certain period of time. If so, the excitation output signal is normal, if not, a control signal is output. At this time, one input end of the first logic NAND gate UA is at a high level, and the other input end is at a low level, and the hardware cannot automatically turn off the first transistor Q1. The microcontroller sends a control signal to turn off the second transistor Q2, and disconnects the power supply of the resolver chip and the resolver chip through the switch tube, thereby protecting the excitation amplifier circuit. The microcontroller displays the fault signal of the excitation output signal detected at this time being short-circuited to high voltage.

[0100] Figure 2 shows the excitation output signal waveform, Figure 3 The excitation output basic circuit is shown, including a third comparator A3, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21 and a twenty-second resistor R22, wherein:

[0101] One end of a nineteenth resistor R19 is connected to the excitation output, and the other end is connected to the third comparator A3;

[0102] One end of the twentieth resistor R20 is connected to the power supply, and the other end is connected to the positive end of the third comparator A3; one end of the twenty-first resistor R21 is grounded, and the other end is connected to the positive end of the third comparator A3; the twentieth resistor R20 and the twenty-first resistor R21 together form a threshold of the second comparator A2;

[0103] One end of the twenty-second resistor R22 is connected to the power supply, and the other end is connected to the output end of the third comparator A3.

[0104] The resolver chip generates an excitation signal which is passed through the resolver excitation signal amplification circuit to generate an excitation output signal with a certain driving capability. The third comparator A3 sets a suitable comparison level to detect the excitation output signal. The connection point between the twentieth resistor R20 and the twenty-first resistor R21 is set to the reference voltage V ref . Reference voltage V ref It refers to a voltage in the circuit that is independent of load, power supply, temperature drift, time, etc., but can always remain constant. In the present invention, the power supply voltage connected to the twentieth resistor R20 is set to V0, then the reference voltage V ref The formula is:

[0105]

[0106] That is, V ref The middle value of the sine signal is output to excite the third comparator A3, and the output signal is a square wave signal with a duty cycle of 50%. The microcontroller considers this signal as a normal signal, and its signal waveform is as follows Figure 4 The duty cycle output waveform of the resolver excitation output signal in the normal state is shown.

[0107] It should be noted that the nineteenth resistor R19, the twentieth resistor R20, the twenty-first resistor R21, the twenty-second resistor R22 and the third comparator A3 are actually equivalent to the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the second comparator A2 in the detection and protection circuit. They are separately mentioned to explain the principle.

[0108] The resolver excitation output signal is the key signal for driving the resolver excitation coil. The distortion of this signal affects the motor rotor position and the motor control. The resolver excitation output signal needs to be short-circuited in many ways, including but not limited to protecting the excitation output signal from short-circuiting to ground, protecting the excitation output signal from short-circuiting to high voltage, and detecting and processing the distortion signal of the excitation output signal.

[0109] When the excitation output sinusoidal signal is distorted, there are three situations to determine the distortion.

[0110] First case: Figure 5 The output condition in which the duty cycle of the resolver excitation output signal is abnormal is shown to be less than 50%.

[0111] Second case: Figure 6 The figure shows the output condition where the duty cycle of the resolver excitation output signal is abnormal and is greater than 50%.

[0112] The third case: Figure 7 It shows that the duty cycle of the resolver excitation output signal in an abnormal state is greater than 50% and less than 50%.

[0113] In the above three situations, the excitation output signal is distorted, and the duty cycle is less than 50% or greater than 50% twice within a certain period of time. At this time, the microcontroller sets the NAND gate input terminal to a high level. When the excitation output signal is distorted for the third time, the hardware automatically turns off the driving voltage of the NPN transistor (i.e., the first transistor Q1) of the excitation amplifier circuit, and the microcontroller sends a control signal to turn off the PNP transistor (i.e., the second transistor Q2) of the excitation amplifier circuit. At the same time, the microcontroller disconnects the power supply of the resolver chip and the resolver chip, and displays the fault signal to accurately identify the cause of the short circuit.

[0114] When the excitation output sinusoidal signal is short-circuited, there are two cases to determine the short circuit.

[0115] First case: Figure 8 The output is shown shorted to ground for a 100% duty cycle.

[0116] Second case: Fig. 9 The case of a short circuit to a high voltage output low level is shown.

[0117] The above two short-circuited excitation output signal conditions will damage the excitation amplifier circuit. The microcontroller detects the short-circuit signal and promptly shuts down the power supply of the resolver chip and the excitation signal amplifier circuit to protect the excitation amplifier circuit, and displays the fault signal to accurately troubleshoot the cause of the short circuit. By detecting that the duty cycle is continuously low or 100% for a certain period of time, after confirming that the excitation output signal is short-circuited to the ground or high voltage, the microcontroller sends a signal to shut down the transistor of the excitation amplifier circuit to protect the excitation amplifier circuit, and at the same time disconnect the power supply of the resolver chip and the resolver chip.

[0118] It should be noted that the above specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention description and its drawings are illustrative and do not constitute a limitation of the claims. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for detecting and protecting abnormality of a resolver excitation signal, characterized in that: The method comprises: Setting a duty cycle based on a detection circuit output of an excitation output signal; Determine the fault type based on the duty cycle; Provide protection based on fault type and display fault signals; The excitation signal is passed through an excitation amplifier circuit to generate the excitation output signal having driving capability. The step of setting the duty cycle includes: setting the first threshold value as a normal duty cycle; The fault type determination based on the duty cycle includes: Determining whether the current value of the duty cycle is equal to the first threshold; If the duty cycle is equal to the first threshold, the excitation output signal is normal; If the current value of the duty cycle deviates from the first threshold, that is, is less than or greater than the first threshold and the number of occurrences is greater than or equal to 2 times, the excitation output signal is in the first fault state; If the duty cycle is continuously at the second threshold, the excitation output signal is in the second fault state; If the duty cycle is continuously at the third threshold, the excitation output signal is in the third fault state; The first fault state refers to the distortion of the excitation output signal, the second fault state refers to the short circuit of the excitation output signal to the ground, and the third fault state refers to the short circuit of the excitation output signal to the high voltage; The excitation output signal detection circuit uses a comparator and sets a reference voltage Vref to perform duty cycle judgment, wherein the reference voltage Vref formula is: ； R20 is the resistance value of the twentieth resistor R20, R21 is the resistance value of the twenty-first resistor R21, and V0 is the power supply voltage connected to the twentieth resistor R20; When the excitation output signal is distorted, the microcontroller detects that the duty cycle of the excitation output signal is abnormal, and the microcontroller outputs a control signal to set one of the input terminals of the first logic NAND gate UA to a high level. When the excitation output signal is distorted for the third time, the comparator outputs a high level, and outputs a low level through the first logic NAND gate UA, and then outputs a high level through the second logic NAND gate UB after short-circuiting the input terminal, turning off the driving voltage of the NPN transistor of the excitation amplifier circuit and turning off the PNP transistor of the excitation amplifier circuit through the control signal, while disconnecting the power supply, displaying the fault signal, and accurately troubleshooting the cause of the short circuit.

2. The resolver excitation signal abnormality detection and protection method according to claim 1, characterized in that: The first threshold value refers to the reference voltage Vref set based on the excitation output signal detection circuit as the reference point of the comparator, that is, the duty cycle is 50%.

3. The resolver excitation signal abnormality detection and protection method according to claim 2, characterized in that: The second threshold value means that after the excitation output signal and the reference voltage Vref pass through the comparator, the comparator outputs a high level, that is, the duty cycle is 100%. The third threshold value refers to the comparator outputting a low level after the excitation output signal and the reference voltage Vref pass through the comparator, that is, the duty cycle is a low level. The continuous duty cycle means that the duty cycle keeps the current value unchanged within a first time period, and the first time period is two cycles after the excitation output signal and the reference voltage Vref pass through the comparator.

4. The resolver excitation signal abnormality detection and protection method according to claim 3, characterized in that: When the excitation output signal is short-circuited to the ground or the excitation output signal is short-circuited to a high voltage, the power supply and the excitation signal amplifying circuit are shut down, and a fault signal is displayed to accurately identify the cause of the short circuit.

5. A resolver excitation signal abnormality detection and protection system, characterized in that: The system executes the resolver excitation signal abnormality detection and protection method according to any one of claims 1 to 4, and the system comprises: Resolver chip, switch tube, microcontroller, excitation amplifier circuit, and excitation signal abnormality detection and protection circuit, The resolver chip is used to generate a fixed-frequency sinusoidal excitation signal with a voltage bias. The switch tube is used to disconnect the power supply switch of the resolver chip when the resolver excitation output is detected to be distorted or short-circuited. The microcontroller is used to detect the state of the excitation output signal and send out a control signal.

6. The resolver excitation signal abnormality detection and protection system according to claim 5, characterized in that: When the third excitation output signal is distorted, the microcontroller sets the NAND gate input terminal to a high level, and the hardware automatically turns off the drive voltage of the NPN transistor of the excitation amplifier circuit. The microcontroller sends a control signal to turn off the drive voltage of the PNP transistor of the excitation amplifier circuit. At the same time, the microcontroller disconnects the power supply of the resolver chip and the resolver chip through the switch tube, and displays the fault signal. When the excitation output signal is short-circuited, the microcontroller detects the short-circuit signal, shuts off the power supply of the resolver chip and the excitation amplifier circuit, protects the excitation amplifier circuit, and displays a fault signal.

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