Composite detection circuit and electric device

Abstract

The application provides a composite detection circuit and an electric device, the electric device comprising a power battery, an inverter and a motor, and the composite detection circuit comprising a voltage acquisition circuit, a signal processing circuit and a frequency-voltage conversion circuit; when the inverter is connected to a charging pile to charge the power battery, the voltage acquisition circuit acquires a voltage signal output by the charging pile to the inverter and outputs a corresponding first voltage acquisition signal as a charging voltage detection signal of the power battery; when the inverter is connected to the power battery to drive the motor to work, the voltage acquisition circuit acquires a voltage signal output by the inverter to the motor and outputs a corresponding second voltage acquisition signal; the signal processing circuit converts the second voltage acquisition signal into a square wave signal with a corresponding amplitude; and the frequency-voltage conversion circuit converts the square wave signal into a level signal and outputs the level signal as a rotating speed detection signal of the motor. The application integrates a voltage detection circuit and a speed detection circuit into a composite detection circuit to reduce the complexity of the detection circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a composite detection circuit and an electric device. BACKGROUND

[0002] In an inverter integrated with a boost charging function, the charging pile voltage needs to be acquired in real time so as to control the boost charging of the power battery based on the charging pile voltage. Therefore, a charging pile voltage detection circuit is generally added in the inverter to feed back the charging pile voltage in real time. Meanwhile, when the motor enters a free rotation state, the inverter needs to acquire the rotating speed of the motor in real time so as to switch the safety state of the motor according to the rotating speed. Therefore, the inverter also integrates a motor rotating speed acquisition circuit to acquire the rotating speed of the motor in real time. It can be seen that in the prior art, two sets of circuits, i.e. the charging pile voltage detection circuit and the motor rotating speed acquisition circuit, are needed to acquire the charging pile voltage and the motor rotating speed, which occupies the PCBA area and is not conducive to miniaturization. In addition, the rotating speed acquisition circuit needs to be matched with a resolver at the motor end. When the resolver is damaged, the rotating speed of the motor cannot be acquired in real time, which reduces the safety of the system. SUMMARY

[0003] The main purpose of the present application is to provide a composite detection circuit and an electric device, which aims to reduce the complexity of the integrated boost charging detection circuit and the motor rotating speed detection circuit.

[0004] Therefore, the present application provides a composite detection circuit applied to an electric device, the electric device comprising a power battery, an inverter and a motor, and the composite detection circuit comprising:

[0005] a voltage acquisition circuit, configured to acquire a voltage signal output by a charging pile to the inverter when the inverter is connected to the charging pile to charge the power battery, and output a corresponding first voltage acquisition signal as a charging voltage detection signal of the power battery; and acquire a voltage signal output by the inverter to the motor when the inverter is connected to the power battery to drive the motor to work, and output a corresponding second voltage acquisition signal;

[0006] a signal processing circuit, configured to convert the second voltage acquisition signal into a square wave signal with a corresponding amplitude;

[0007] a frequency-voltage conversion circuit, configured to generate a level signal with a corresponding duty cycle size according to the duty cycle modulation of the square wave signal, and output the level signal as a rotating speed detection signal of the motor.

[0008] Optionally, the inverter has a charging input connected with the charging pile, an input end of the voltage acquisition circuit is connected with the charging input, an input end of the signal processing circuit is connected with an output end of the voltage acquisition circuit, and an input end of the frequency-voltage conversion circuit is connected with an output end of the signal processing circuit.

[0009] Optionally, the voltage acquisition circuit comprises:

[0010] a voltage dropping circuit, an input end of the voltage dropping circuit being connected with the charging input, the voltage dropping circuit being configured to receive a voltage signal output by the inverter to the motor and output a voltage dropping signal after voltage dropping processing on the voltage signal;

[0011] a first amplification circuit, an input end of the first amplification circuit being connected with an output end of the voltage dropping circuit, the first amplification circuit being configured to output a second voltage acquisition signal after amplification processing on the voltage dropping signal.

[0012] Optionally, the voltage acquisition circuit further comprises:

[0013] an isolation circuit, an input end of the isolation circuit being connected with an output end of the voltage dropping circuit, and an output end of the isolation circuit being connected with an input end of the first amplification circuit;

[0014] the isolation circuit being configured to isolate a voltage of the voltage dropping circuit and a voltage of the first amplification circuit.

[0015] Optionally, the signal processing circuit comprises:

[0016] a comparison circuit, an input end of the comparison circuit being connected with an output end of the voltage acquisition circuit, and an output end of the comparison circuit being connected with an input end of the frequency-voltage conversion circuit;

[0017] the comparison circuit being configured to convert a second voltage acquisition signal of the voltage acquisition circuit into a square wave signal with a corresponding amplitude and output to the frequency-voltage conversion circuit.

[0018] Optionally, the signal processing circuit further comprises:

[0019] a second amplification circuit, an input end of the second amplification circuit being connected with an output end of the voltage acquisition circuit, and an output end of the second amplification circuit being connected with an input end of the comparison circuit, the second amplification circuit being configured to amplify the second voltage acquisition signal.

[0020] Optionally, the frequency-voltage conversion circuit comprises:

[0021] a charging circuit.

[0022] A switch control circuit, a first signal input end of the switch control circuit is connected with an output end of the signal processing circuit;

[0023] A second signal input end of the switch control circuit, a DC power supply end and the charging circuit are connected with each other;

[0024] The switch control circuit is used for controlling the time of the power supply input from the DC power supply end to the charging circuit according to the duty cycle of the square wave signal, so that the charging circuit outputs a level signal corresponding to the duty cycle of the square wave signal and outputs a rotation speed detection signal of the motor.

[0025] Optionally, the switch control circuit comprises a second triode, and the charging circuit comprises a third capacitor and a fourth capacitor.

[0026] The base of the second triode is connected with the output end of the signal processing circuit, the collector of the second triode is connected with the DC power supply end, the mutual connection point thereof is connected with the first end of the third capacitor, and the emitter of the second triode is grounded; the second end of the third capacitor is connected with the input end of the MCU, the mutual connection point thereof is connected with the first end of the fourth capacitor, and the second end of the fourth capacitor is grounded.

[0027] The application further provides an electric device, which comprises a main body, a motor, a power battery, an inverter and the composite detection circuit according to any one of claims 1-8, the inverter has a charging input end connected with the charging pile, the battery connection end of the inverter is connected with the power battery, and the output end of the inverter is connected with the motor; the input end of the voltage acquisition circuit of the composite detection circuit is connected with the charging input end.

[0028] The inverter is used for converting the direct-current voltage of the power battery into an alternating-current voltage and then outputting the alternating-current voltage to the motor, so as to drive the motor to work.

[0029] Optionally, the inverter comprises three-phase bridge arm circuits, each phase bridge arm circuit comprises an upper bridge arm switch and a lower bridge arm switch, and the common end of the upper bridge arm switch and the lower bridge arm switch of any one phase bridge arm circuit can be used as the charging input end.

[0030] The application provides a composite detection circuit and an electric device, the electric device comprising a power battery, an inverter and a motor, and the composite detection circuit comprising a voltage acquisition circuit, a signal processing circuit and a frequency-voltage conversion circuit; the voltage acquisition circuit acquires a voltage signal output by a charging pile to the inverter when the inverter is connected to the charging pile to charge the power battery, and outputs a corresponding first voltage acquisition signal as a charging voltage detection signal of the power battery; the voltage acquisition circuit acquires a voltage signal output by the inverter to the motor when the inverter is connected to the power battery to drive the motor to work, and outputs a corresponding second voltage acquisition signal; the signal processing circuit converts the second voltage acquisition signal into a square wave signal with a corresponding amplitude; and the frequency-voltage conversion circuit converts the square wave signal into a level signal and outputs the level signal as a rotating speed detection signal of the motor. The voltage detection circuit and the speed detection circuit are integrated into the composite detection circuit, so that the complexity of the detection circuit is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in the drawings without creative labor.

[0032] Figure 1 The circuit flow chart of the composite detection circuit and the electric device of the present application;

[0033] Figure 2 The circuit structure chart of the composite detection circuit and the electric device of the present application;

[0034] Figure 3 The circuit structure chart of another embodiment of the composite detection circuit and the electric device of the present application.

[0035] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] Inverters with integrated boost charging functionality require real-time access to the charging pile voltage so that the power battery can be boosted and charged based on the charging pile voltage. Therefore, a charging pile voltage detection circuit is typically added to the inverter to provide real-time feedback on the charging pile voltage. Furthermore, when the motor enters the free-wheeling state, the inverter needs to acquire the motor speed in real time so that the motor can switch between safe states based on the speed. Therefore, the inverter also integrates a motor speed acquisition circuit to collect the motor speed in real time. As can be seen, in the prior art, collecting the charging pile voltage and motor speed requires two circuits: the charging pile voltage detection circuit and the motor speed acquisition circuit. This consumes PCBA space and is not conducive to miniaturization. Furthermore, the speed acquisition circuit requires the use of a resolver on the motor side. If the resolver is damaged, real-time motor speed acquisition becomes impossible, reducing system safety.

[0041] Therefore, in order to reduce the complexity of the integrated boost charging detection circuit and the motor speed detection circuit, and reduce the area occupied by the integrated boost charging detection circuit and the motor speed detection circuit on the PCBA, the application provides a composite detection circuit applied to an electric device, the electric device comprising a power battery, an inverter and a motor, the battery connection end of the inverter is connected with the power battery, and the output end of the inverter is connected with the motor; the input end of the voltage acquisition circuit of the composite detection circuit is connected with the charging input end, wherein the inverter is used to be connected with a charging pile to access a power supply and charge the power battery.

[0042] Reference Figure 1 In an embodiment of the application, the composite detection circuit comprises:

[0043] The voltage acquisition circuit 10 is used to acquire the voltage signal output by the charging pile to the inverter when the inverter is connected with the charging pile to charge the power battery, and output the corresponding first voltage acquisition signal as the charging voltage detection signal of the power battery; and the voltage acquisition circuit 10 is used to acquire the voltage signal output by the inverter to the motor when the inverter is connected with the power battery to drive the motor to work, and output the corresponding second voltage acquisition signal;

[0044] The signal processing circuit 20 is used to convert the second voltage acquisition signal into a square wave signal with a corresponding amplitude;

[0045] The frequency-voltage conversion circuit 30 is used to generate a level signal with a corresponding duty cycle size according to the duty cycle modulation of the square wave signal, and output the level signal as the speed detection signal of the motor.

[0046] It can be understood that the existing boost charging detection circuit is generally realized by resistance voltage division. Specifically, after the high-voltage electricity of the charging pile is converted into low-voltage electricity within 5V, the low-voltage electricity is output to an operational amplifier, and after amplification processing by the operational amplifier circuit and filtering processing by the filter circuit, a corresponding second voltage collection signal is output to the MCU. The MCU acquires the charging pile voltage in real time according to the second voltage collection signal, so as to control the boost charging of the power battery based on the charging pile voltage. In addition, the existing speed sampling circuit is generally realized by a rotary transformer. Specifically, the excitation signal amplification circuit outputs an excitation signal to the rotary transformer of the motor, and the rotary transformer outputs two paths of sine / cosine signals related to the speed to the position decoding circuit. The position decoding circuit analyzes the sine / cosine signals and outputs corresponding position signals to the MCU. The MCU acquires the motor speed in real time according to the position signals, so as to switch the safety state based on the motor speed. It can be seen that in the prior art, two sets of circuits are required to collect the charging pile voltage and the motor speed, namely the charging pile voltage detection circuit and the motor speed sampling circuit. Since the two sets of circuits operate independently, the detection circuit is complex and occupies a large area of PCBA, which is not conducive to miniaturization. In addition, in the process of collecting the motor speed in the prior art, the speed sampling circuit needs to be used with the rotary transformer at the motor end. When the rotary transformer is damaged, the motor speed cannot be collected in real time, and the MCU cannot switch the safety state through the motor speed, thereby reducing the safety of the system. Therefore, the present application proposes a composite detection circuit, which integrates the voltage collection circuit 10 for collecting the charging pile voltage and the frequency-voltage conversion circuit 30 for collecting the motor speed into a composite detection circuit, so as to realize the collection of the charging pile voltage and the collection of the motor speed through the same detection circuit, thereby reducing the complexity of the integrated boost charging detection circuit and the motor speed detection circuit and reducing the area occupied by PCBA.

[0047] It needs to be understood that the composite detection circuit proposed by the present application is applied to an electric device to detect the charging voltage of the electric device and the motor speed of the electric device. The electric device includes a power battery, an inverter and a motor. When the electric device is connected to a charging pile, the inverter is turned on to transmit the charging voltage input by the charging pile to the power battery to charge the power battery. When the electric device is not connected to the charging pile, the inverter converts the direct current voltage of the power battery into corresponding alternating current voltage to the motor to drive the motor to operate. In combination with the composite detection circuit proposed by the present application, when the electric device is connected to the charging pile, the motor is in a stationary state, and at this time the voltage collection circuit 10 collects the voltage output by the charging pile to the inverter. When the electric device is not connected to the charging pile, the motor is in a starting state, and at this time the voltage collection circuit 10 collects the voltage output by the inverter to the motor.

[0048] In practical application, when the electric device is connected to the charging pile, the inverter is connected to the charging pile to charge the power battery, the voltage acquisition circuit 10 acquires the voltage signal output by the charging pile to the inverter, and outputs the corresponding first voltage acquisition signal as the charging voltage detection signal of the power battery to the MCU, and the MCU acquires the charging pile voltage in real time according to the charging voltage detection signal to control the boost charging of the power battery; when the electric device is not connected to the charging pile, the inverter is connected to the power battery to drive the motor to work, and the voltage acquisition circuit 10 acquires the voltage signal output by the inverter to the motor, and outputs the corresponding second voltage acquisition signal to the signal processing circuit 20. It should be understood that the second voltage acquisition signal is a sinusoidal voltage signal, and the signal processing circuit 20 converts the received sinusoidal voltage signal into a square wave signal with a corresponding amplitude and outputs it to the frequency-voltage conversion circuit 30. The frequency-voltage conversion circuit 30 converts the square wave signal into a level signal and outputs the level signal to the MCU as the speed detection signal of the motor. The MCU detects the current speed of the motor in real time according to the received speed detection signal, so as to switch the safety state according to the high and low of the motor speed.

[0049] The application provides a composite detection circuit applied to an electric device, the electric device comprising a power battery, an inverter and a motor, and comprising a voltage acquisition circuit 10, a signal processing circuit 20 and a frequency-voltage conversion circuit 30. The voltage acquisition circuit 10 is used for acquiring the voltage signal output by the charging pile to the inverter when the inverter is connected to the charging pile to charge the power battery, and outputting the corresponding first voltage acquisition signal as the charging voltage detection signal of the power battery; and acquiring the voltage signal output by the inverter to the motor when the inverter is connected to the power battery to drive the motor to work, and outputting the corresponding second voltage acquisition signal. The signal processing circuit 20 is used for converting the second voltage acquisition signal into a square wave signal with a corresponding amplitude. The frequency-voltage conversion circuit 30 is used for converting the square wave signal into a level signal and outputting the level signal as the speed detection signal of the motor. The application integrates the voltage detection circuit and the speed detection circuit into a composite detection circuit, so as to realize the acquisition of the charging pile voltage and the acquisition of the motor speed through the composite detection circuit, thereby reducing the complexity of the detection circuit and reducing the area occupied by the PCBA.

[0050] In an embodiment, referring to Figure 2 , the inverter has a charging input end connected with the charging pile, the input end of the voltage acquisition circuit 10 is connected with the charging input end; the input end of the signal processing circuit 20 is connected with the output end of the voltage acquisition circuit 10; and the input end of the frequency-voltage conversion circuit 30 is connected with the output end of the signal processing circuit 20.

[0051] It can be understood that in the embodiment, the inverter has a charging input end connected with the charging pile, when the electric device accesses the charging pile, the inverter is turned on to transmit the charging voltage input by the charging pile to the power battery, the voltage acquisition circuit 10 acquires the voltage output by the charging pile to the inverter through the charging input end, and outputs the corresponding first voltage acquisition signal as the charging voltage detection signal of the power battery to the MCU, and the MCU acquires the charging pile voltage in real time according to the charging voltage detection signal; when the electric device does not access the charging pile, the voltage acquisition circuit 10 acquires the voltage output by the inverter to the motor through the charging input end, and outputs the corresponding second voltage acquisition signal to the signal processing circuit 20.

[0052] In an embodiment, referring to Figure 2 , the voltage acquisition circuit 10 comprises:

[0053] a voltage drop circuit, an input end of the voltage drop circuit being connected with the charging input end; the voltage drop circuit being used for receiving the voltage signal output by the inverter to the motor, and outputting a voltage drop signal after performing voltage drop processing on the voltage signal;

[0054] a first amplification circuit, an input end of the first amplification circuit being connected with an output end of the voltage drop circuit; the first amplification circuit being used for outputting the second voltage acquisition signal after performing amplification processing on the voltage drop signal.

[0055] It can be understood that in the embodiment, the voltage acquisition circuit 10 comprises the voltage drop circuit and the first amplification circuit. Wherein, the voltage drop circuit is used for, when the electric device accesses the charging pile, acquiring the high voltage output by the charging pile to the inverter through the charging input end, and performing voltage drop processing on the high voltage to reduce the high voltage to a voltage within a certain range, and outputting the voltage drop signal after the voltage drop processing to the first amplification circuit; the first amplification circuit receives the voltage drop signal, and outputs the corresponding first voltage acquisition signal after performing amplification processing on the voltage drop signal, the first voltage acquisition signal being output as the charging voltage detection signal of the power battery to the MCU, and the MCU acquires the charging voltage of the charging pile in real time according to the charging voltage detection signal, so as to control the boost charging of the power battery according to the charging voltage of the charging pile, thereby improving the charging efficiency of the power battery. In addition, the voltage drop circuit is used for, when the electric device does not access the charging pile, acquiring the voltage output by the inverter to the motor through the charging input end, performing voltage drop processing on the voltage of the motor, and outputting the voltage drop signal to the first amplification circuit, the first amplification circuit outputting the corresponding second voltage acquisition signal to the signal processing circuit 20 after performing amplification processing on the voltage drop signal, so that the signal processing circuit 20 performs signal processing according to the second voltage acquisition signal.

[0056] In an embodiment, referring to Figure 2 , the voltage acquisition circuit 10 further comprises:

[0057] An isolation circuit, an input end of the isolation circuit is connected with an output end of the voltage drop circuit, and an output end of the isolation circuit is connected with an input end of the first amplification circuit;

[0058] The isolation circuit is configured to isolate the voltage of the voltage drop circuit and the voltage of the first amplification circuit.

[0059] It can be understood that in the embodiment, the voltage acquisition circuit 10 further comprises an isolation circuit, which is arranged between the voltage drop circuit and the first amplification circuit, and is configured to provide a high-low voltage isolation function to output a low voltage signal on the high voltage side to the low voltage side. For example, the voltage drop circuit performs voltage drop on the high voltage output by the charging pile to an inverter, and outputs a corresponding low voltage signal. At this time, the isolation circuit transmits the low voltage signal of the voltage drop circuit to the first amplification circuit, thereby realizing the high-low voltage isolation function.

[0060] In an embodiment, referring to Figure 2 , the voltage drop circuit comprises a first resistor R1 and a second resistor R2, and the first amplification circuit comprises a first operational amplifier U2. A first end of the first resistor R1 is connected with a positive electrode of the charging pile, a second end of the first resistor R1 is connected with a first end of the second resistor R2, and a second end of the second resistor R2 is connected with a negative electrode of the charging pile. An input end of the first operational amplifier U2 is connected with an output end of the isolation circuit, and an output end of the first operational amplifier U2 is connected with an input end of the signal processing circuit 20. The isolation circuit comprises an isolation operational amplifier U1, an input end of the isolation operational amplifier U1 is connected with the second end of the second resistor R2, and an output end of the isolation operational amplifier U1 is connected with a second end of the fifth resistor R5 and a second end of the fourth resistor R4 respectively.

[0061] It can be understood that in the embodiment, the voltage drop circuit comprises a first resistor R1 and a second resistor R2; the first amplification circuit comprises a first operational amplifier U2, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; and the isolation circuit comprises an isolation operational amplifier U1.

[0062] In actual application, after the high voltage of the charging pile is reduced by the first resistor R1 and the second resistor R2, the voltage is reduced to a voltage within a certain range, and a corresponding voltage drop signal is output; the isolation operational amplifier U1 provides a high-low voltage isolation function to output a low voltage signal on the high voltage side to the low voltage side, that is, the isolation operational amplifier U1 outputs the voltage drop signal of the voltage drop circuit to the first operational amplifier U2 through the fourth resistor R4 and the fifth resistor R5; the first operational amplifier U2 amplifies the voltage drop signal output by the isolation operational amplifier U1 by a fixed ratio to form a voltage acquisition signal available for the MCU, and outputs the voltage acquisition signal to the signal processing circuit 20.

[0063] The voltage acquisition circuit 10 comprises a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first resistor R1, and a second resistor R2.

[0064] In an embodiment, referring to Figure 3 , the signal processing circuit 20 comprises:

[0065] a comparison circuit, an input end of the comparison circuit being connected with an output end of the voltage acquisition circuit 10, and an output end of the comparison circuit being connected with an input end of the frequency-voltage conversion circuit 30.

[0066] It can be understood that, in the embodiment, the signal processing circuit 20 comprises the comparison circuit and the filter circuit. The filter circuit is configured to perform filter processing on the second voltage acquisition signal output by the voltage acquisition circuit 10. The comparison circuit is configured to convert the second voltage acquisition signal after the filter processing into a square wave signal with a corresponding amplitude, and output the square wave signal to the frequency-voltage conversion circuit 30.

[0067] In addition, the comparison circuit in the embodiment is implemented by a comparator U4. The comparator U4 can generate a periodic square wave according to the received signal, that is, the comparator U4 can generate a square wave signal with a corresponding amplitude according to the second voltage acquisition signal. The square wave signal determines the ratio of the high-level time and the low-level time of the square wave. Therefore, the comparison circuit in the embodiment is configured to generate a square wave signal with a corresponding amplitude. The generated square wave signal drives the frequency-voltage conversion circuit 30 to be turned on / off, so that the frequency-voltage conversion circuit 30 outputs a corresponding speed detection signal in the process of being turned on / off.

[0068] In another embodiment, referring to Figure 2 , the signal processing circuit 20 comprises:

[0069] a comparison circuit, an input end of the comparison circuit being connected with an output end of the voltage acquisition circuit, and an output end of the comparison circuit being connected with an input end of the frequency-voltage conversion circuit;

[0070] the comparison circuit is configured to convert a second voltage acquisition signal of the voltage acquisition circuit into a square wave signal with a corresponding amplitude, and output the square wave signal to the frequency-voltage conversion circuit;

[0071] a second amplification circuit, an input end of the second amplification circuit being connected with an output end of the voltage acquisition circuit, and an output end of the second amplification circuit being connected with an input end of the comparison circuit; the second amplification circuit is configured to perform amplification processing on the second voltage acquisition signal.

[0072] It can be understood that, in the embodiment, the signal processing circuit 20 comprises a second amplification circuit, a filter circuit and a comparison circuit. The second amplification circuit is configured to amplify the second voltage collection signal output by the voltage collection circuit 10; the filter circuit is configured to filter the second voltage collection signal after the amplification; and the comparison circuit is configured to convert the second voltage collection signal after the filtering into a square wave signal with a corresponding amplitude, and output the square wave signal to the frequency-voltage conversion circuit 30.

[0073] In an embodiment, with reference to Figure 2 , the second amplification circuit comprises a second operational amplifier U3, the filter circuit comprises a twelfth resistor R12 and a first capacitor C1, and the comparison circuit comprises a comparator U4; an input end of the second operational amplifier U3 is connected with an output end of the voltage collection circuit 10, an output end of the second operational amplifier U3 is connected with a first end of the twelfth resistor R12, a second end of the twelfth resistor R12 is connected with a negative end of the comparator U4, a mutual connection point thereof is connected with a first end of the first capacitor C1, and the first capacitor C1 is grounded; and a positive end of the comparator U4 is connected with an output end of the comparator U4.

[0074] It can be understood that, in the embodiment, the second amplification circuit comprises a second operational amplifier U3, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11; the filter circuit comprises a twelfth resistor R12 and a first capacitor C1; and the comparison circuit comprises a comparator U4, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15 and a sixteenth resistor R16.

[0075] In actual application, the second voltage collection signal is input to the second amplification circuit through the ninth resistor R9, the second amplification circuit amplifies the input second voltage collection signal in proportion and then outputs; the twelfth resistor R12 and the first capacitor C1 constitute a high-frequency filter circuit, to amplify the direct current component in the signal output by the second amplification circuit by one-to-one, and to reduce the alternating current component in the signal output by the second amplification circuit, so as to complete high-frequency filtering processing, and the second voltage collection signal after the high-frequency filtering processing is output to the inverting end of the comparator U4; at this time, the comparator U4 compares the second voltage collection signal with a reference voltage, generates a corresponding square wave signal, and outputs the square wave signal to the frequency-voltage conversion circuit 30 through the output end.

[0076] In the embodiment, the thirteenth resistor R13, the fourteenth resistor R14, the fifteenth resistor R15 and the sixteenth resistor R16 constitute a positive feedback circuit to feed back the signal outputted by the comparator U4 to the non-inverting terminal of the comparator U4. It is understood that when the comparator U4 compares the signals, the higher flip level is generated by the comparator U4 when the comparison voltage changes from low to high, and the lower flip level is generated by the comparator U4 when the comparison voltage changes from high to low, the difference between the higher flip level and the lower flip level is called the hysteresis, and the size of the positive feedback circuit determines the size of the hysteresis voltage. Since the hysteresis voltage affects the comparison accuracy of the comparator U4, the size of the positive feedback circuit can be changed to avoid the influence of the hysteresis voltage generated by the comparator U4 on the comparison accuracy.

[0077] In the signal processing circuit 20, the resistance value of the fourteenth resistor R14 is much smaller than the resistance value of the fifteenth resistor R15, the resistance value of the sixteenth resistor R16 is much larger than the resistance value of the thirteenth resistor R13 plus the fourteenth resistor R14, and the resistance value of the sixteenth resistor R16 is much larger than the resistance value of the thirteenth resistor R13 plus the fifteenth resistor R15.

[0078] In an embodiment, with reference to Figure 2 , the frequency-voltage conversion circuit 30 comprises:

[0079] a charging circuit;

[0080] a switch control circuit, a first signal input end of the switch control circuit being connected with an output end of the signal processing circuit;

[0081] a second signal input end, a DC power supply end and the charging circuit of the switch control circuit being connected with each other;

[0082] the switch control circuit, for controlling the time of the power inputted by the DC power supply end to the charging circuit to charge, so that the charging circuit outputs the level signal corresponding to the duty cycle of the square wave signal, and outputs the rotation speed detection signal of the motor.

[0083] It can be understood that, in the embodiment, the frequency-voltage conversion circuit 30 comprises a charging circuit and a switch control circuit. The switch control circuit is configured to receive the square wave signal output by the signal processing circuit 20, and output a signal to turn on / off the path between the DC power supply end and the ground, so as to control the on-time and off-time of the charging circuit. For example, when the path between the DC power supply end and the ground is turned on, the charging circuit is in an on state, and the charging circuit outputs a corresponding level signal to the MCU; when the path between the DC power supply end and the ground is turned off, the charging circuit is in an off state, and the charging circuit outputs a corresponding level signal to the MCU. At this time, the level signal is output to the MCU as a motor speed detection signal, and the MCU detects the speed of the motor according to the speed detection signal.

[0084] In an embodiment, with reference to Figure 2 , the switch control circuit comprises a second transistor Q2, and the charging circuit comprises a third capacitor C3 and a fourth capacitor C4.

[0085] The base of the second transistor Q2 is connected with the output end of the signal processing circuit 20, the collector of the second transistor Q2 is connected with the DC power supply end, the mutual connection point thereof is connected with the first end of the third capacitor C3, and the emitter of the second transistor Q2 is grounded. The second end of the third capacitor C3 is connected with the input end of the MCU, the mutual connection point thereof is connected with the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is grounded.

[0086] It can be understood that, in the embodiment, the switch control circuit further comprises a second transistor Q2, a seventeenth resistor R17, an eighteenth resistor R18, a twentieth resistor R20 and a twenty-second resistor R22; the charging circuit comprises a third capacitor C3, a fourth capacitor C4, a first diode D1 and a second diode D2.

[0087] In actual application, when the second triode Q2 is turned on according to the square wave signal, the connection path between the DC power supply end and the ground is turned on. At this time, the charging circuit forms a loop and starts to work, and the first diode D1 charges the fourth capacitor C4 with a fixed amount of charge to charge the third capacitor C3 and the fourth capacitor C4; when the second triode Q2 is turned off according to the square wave signal, the connection path between the DC power supply end and the ground is turned off. At this time, the third capacitor C3 and the fourth capacitor C4 are discharged to output the corresponding level signal to the MCU, and the level signal is output to the MCU as the motor speed detection signal, so that the MCU detects the speed of the motor according to the received speed detection signal, and controls the motor to switch to the safe state according to the speed of the motor. It should be understood that the square wave signal is a PWM signal, and the size of the duty cycle will affect the on / off time of the second triode Q2, and the on / off time of the second triode Q2 will affect the frequency of the output level signal to the MCU, therefore, the MCU can detect the speed of the motor according to the size of the duty cycle in the square wave signal.

[0088] In the above frequency-voltage conversion circuit 30, the second triode Q2 is used to switch between the saturation region and the cutoff region according to the square wave signal, so as to turn on / off the connection path between the DC power supply end and the ground; the resistance value of the twentieth resistor R20 needs to be small enough to ensure that the charge of the third capacitor C3 is charged to the maximum value each time the square wave signal is high; the value of the fourth capacitor C4 needs to be as large as possible to ensure that the response time of the speed signal is fast enough; the value of the nineteenth resistor R19 needs to ensure that the output speed signal is still within the specified range under the maximum frequency of the input square wave signal.

[0089] The application further provides an electric device, which comprises a main body, a motor, a power battery, an inverter and a composite detection circuit as described above, the inverter has a charging input end connected with the charging pile, a battery connection end of the inverter is connected with the power battery, and an output end of the inverter is connected with the motor; the input end of the voltage acquisition circuit of the composite detection circuit is connected with the charging input end.

[0090] The inverter is used for converting the direct-current voltage of the power battery into an alternating-current voltage and then outputting the alternating-current voltage to the motor to drive the motor to work.

[0091] It can be understood that in the embodiment, the electric device includes a motor, a power battery and an inverter. The inverter is composed of six MOS tubes, i.e., a first MOS tube S1, a second MOS tube S2, a third MOS tube S3, a fourth MOS tube S4, a fifth MOS tube S5 and a sixth MOS tube S6. When the electric device is connected to a charging pile, the six MOS tubes are turned on to transmit a charging voltage input by the charging pile to the power battery to charge the power battery. When the electric device is not connected to the charging pile, the six MOS tubes are turned on / off to convert a direct current voltage of the power battery into a corresponding alternating current voltage and output to the motor to drive the motor to work.

[0092] In an embodiment, the inverter includes three-phase bridge arm circuits, each of which includes an upper bridge arm switch and a lower bridge arm switch; and the common end of the upper bridge arm switch and the lower bridge arm switch of any one of the three-phase bridge arm circuits can be used as a charging input end.

[0093] It can be understood that in the embodiment, when the charging pile is connected to the inverter through the charging input end, the voltage acquisition circuit 10 acquires a voltage output by the charging pile to the inverter through the charging input end, converts the voltage of the charging pile into a first voltage acquisition signal and outputs the first voltage acquisition signal to the MCU; when the charging pile is not connected to the inverter, the voltage acquisition circuit 10 acquires a voltage output by the inverter to the motor through the charging input end, converts the voltage of the motor into a second voltage acquisition signal and outputs the second voltage acquisition signal to the signal processing circuit 20 to make the signal processing circuit 20 process the second voltage acquisition signal.

[0094] The above description is only optional embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields based on the inventive concept of the present application and the content of the specification and drawings are included in the patent protection scope of the present application.

Claims

1. A composite detection circuit applied to an electric device, the electric device comprising a power battery, an inverter and a motor, characterized in that, The composite detection circuit comprises: a voltage acquisition circuit, configured to acquire a voltage signal output by a charging pile to an inverter when the inverter is connected to the charging pile to charge a power battery, and output a corresponding first voltage acquisition signal as a charging voltage detection signal of the power battery; and acquire a voltage signal output by the inverter to a motor when the inverter is connected to the power battery to drive the motor to work, and output a corresponding second voltage acquisition signal; a signal processing circuit, configured to convert the second voltage acquisition signal into a square wave signal with a corresponding amplitude; a frequency-voltage conversion circuit, configured to generate a level signal with a corresponding duty cycle size according to a duty cycle of the square wave signal, and output the level signal as a rotation speed detection signal of the motor.

2. The composite detection circuit according to claim 1, wherein The inverter has a charging input end connected to the charging pile, an input end of the voltage acquisition circuit is connected to the charging input end, an input end of the signal processing circuit is connected to an output end of the voltage acquisition circuit, and an input end of the frequency-voltage conversion circuit is connected to an output end of the signal processing circuit.

3. The composite detection circuit according to claim 2, wherein The voltage acquisition circuit comprises: a voltage drop circuit, an input end of the voltage drop circuit is connected to the charging input end, and the voltage drop circuit is configured to receive the voltage signal output by the inverter to the motor, and output a voltage drop signal after voltage drop processing on the voltage signal; a first amplification circuit, an input end of the first amplification circuit is connected to an output end of the voltage drop circuit, and the first amplification circuit is configured to output the second voltage acquisition signal after amplification processing on the voltage drop signal.

4. The composite detection circuit according to claim 3, wherein The voltage acquisition circuit further comprises: an isolation circuit, an input end of the isolation circuit is connected to an output end of the voltage drop circuit, and an output end of the isolation circuit is connected to an input end of the first amplification circuit; the isolation circuit is configured to isolate a voltage of the voltage drop circuit and a voltage of the first amplification circuit.

5. The composite detection circuit according to claim 1, wherein The signal processing circuit comprises: a comparison circuit, an input end of the comparison circuit is connected to an output end of the voltage acquisition circuit, and an output end of the comparison circuit is connected to an input end of the frequency-voltage conversion circuit; the comparison circuit is configured to convert the second voltage acquisition signal of the voltage acquisition circuit into a square wave signal with a corresponding amplitude, and output the square wave signal to the frequency-voltage conversion circuit.

6. The composite detection circuit according to claim 5, wherein The signal processing circuit further comprises: a second amplification circuit, an input end of the second amplification circuit is connected to an output end of the voltage acquisition circuit, and an output end of the second amplification circuit is connected to an input end of the comparison circuit; the second amplification circuit is configured to perform amplification processing on the second voltage acquisition signal.

7. The composite detection circuit according to claim 1, wherein The frequency-voltage conversion circuit comprises: a charging circuit; a switch control circuit, a first signal input end of the switch control circuit is connected to an output end of the signal processing circuit; a second signal input end, a DC power supply end and the charging circuit of the switch control circuit are connected to each other; the switch control circuit is configured to control a time for which a power supply input by the DC power supply end charges the charging circuit according to a duty cycle size of the square wave signal, so that the charging circuit outputs a level signal corresponding to the duty cycle size of the square wave signal, and outputs the level signal as a rotation speed detection signal of the motor.

8. The composite detection circuit according to claim 7, wherein The switch control circuit comprises a second triode; the charging circuit comprises a third capacitor and a fourth capacitor; The base of the second triode is connected with the output end of the signal processing circuit, the collector of the second triode is connected with the DC power supply end, the mutual connection point thereof is connected with the first end of the third capacitor, and the emitter of the second triode is grounded; the second end of the third capacitor is connected with the input end of the MCU, the mutual connection point thereof is connected with the first end of the fourth capacitor, and the second end of the fourth capacitor is grounded.

9. An electrically powered device, characterized in that The electric device comprises a main body, a motor, a power battery, an inverter and the composite detection circuit as claimed in any one of claims 1-8, the inverter has a charging input end connected with the charging pile, the battery connection end of the inverter is connected with the power battery, and the output end of the inverter is connected with the motor; the input end of the voltage acquisition circuit of the composite detection circuit is connected with the charging input end; The inverter is used for converting the direct current voltage of the power battery into alternating current voltage and then outputting the alternating current voltage to the motor, so as to drive the motor to work.

10. The electrically powered device of claim 9, wherein, The inverter comprises three-phase bridge arm circuits, each phase bridge arm circuit comprises an upper bridge arm switch and a lower bridge arm switch; the common end of the upper bridge arm switch and the lower bridge arm switch of any one phase bridge arm circuit can be used as the charging input end.

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