Heating circuit, heating control system and ventilator

Abstract

The present invention discloses a heating circuit, a heating control system, and a ventilator, comprising a control unit, a heating unit, a hysteresis comparison unit, and a monitoring unit; the heating unit is connected to a heating load and is used to enter a heating state or a non-heating state according to a first control signal and a second control signal; the monitoring unit is connected to the heating unit, the heating load, the control unit, and the hysteresis comparison unit, and is used to sample the heating load and output a target sampling signal to the hysteresis comparison unit and the control unit, respectively; the hysteresis comparison unit is connected to the heating unit and is used to output a second control signal to the heating unit according to the target sampling signal; and the control unit is connected to the heating unit and is used to output a first control signal to the heating unit according to the target sampling signal. This technical solution can implement multiple cut-off modes, ensuring that when the temperature of the heating load is abnormal, the power supply can be normally cut off, achieving closed-loop control of the heating load temperature, and improving the safety of the heating circuit.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a heating circuit, a heating control system and a ventilator. Background Art

[0002] The exhalation valve is an important component of the ventilator. When the room temperature is low or the ventilator is working for a long time, the water vapor in the patient's exhaled gas can easily condense inside the exhalation valve. On the one hand, it increases cross-infection between patients, and on the other hand, it can easily contaminate the machine. Therefore, it is particularly important to prevent the condensation of water vapor. The conventional practice is to cover the exhalation valve with a heating film, thereby maintaining the exhalation valve at a relatively constant temperature through heat conduction. As long as the temperature is appropriate, the condensation and liquefaction of water vapor can be prevented. However, the existing heating film heating circuit cannot cut off the power supply in time when the temperature of the heating film is too high, resulting in damage to the machine due to excessive temperature. Summary of the Invention

[0003] Embodiments of the present invention provide a heating circuit, a heating control system, and a ventilator to solve the problem that the existing heating circuit cannot cut off the power supply in time when the temperature of the heating load is too high.

[0004] A heating circuit comprises a control unit, a heating unit, a hysteresis comparison unit and a monitoring unit;

[0005] The heating unit is connected to the heating load and is used to enter a heating state or a non-heating state according to a first control signal and a second control signal;

[0006] The monitoring unit is connected to the heating unit, the heating load, the control unit and the hysteresis comparison unit, and is used to sample the heating load, obtain a target sampling signal, and output the target sampling signal to the hysteresis comparison unit and the control unit respectively;

[0007] The hysteresis comparison unit is connected to the heating unit and is used to perform abnormality detection according to the target sampling signal and output the second control signal to the heating unit;

[0008] The control unit is connected to the heating unit, and is configured to output the first control signal to the heating unit according to the target sampling signal.

[0009] Furthermore, the heating unit includes a first control circuit and a second control circuit, the first control circuit is used to connect the power input terminal and the positive connection terminal of the heating load, and the second control circuit is used to connect the negative connection terminal of the heating load and the ground;

[0010] The control circuit is connected to the first control circuit and the second control circuit, and is used to output the first control signal to control the on and off of the first control circuit and the second control circuit;

[0011] The hysteresis comparison unit is connected to the second control circuit and is used to output the second control signal to control the on and off of the second control circuit.

[0012] Further, the first control circuit includes a first transistor and a second transistor;

[0013] A first terminal of the first transistor is coupled to the control unit, a second terminal of the first transistor is coupled to a first terminal of the second transistor, a third terminal of the first transistor is grounded, a second terminal of the second transistor is coupled to the power input terminal, and a third terminal of the second transistor is coupled to the positive connection terminal of the heating load.

[0014] Further, the second control circuit includes a third transistor, a fourth transistor, a fifth transistor, a first diode and a second diode;

[0015] A first terminal of the third transistor is coupled to the control unit, a second terminal of the third transistor is coupled to the power supply terminal, and a third terminal of the third transistor is grounded;

[0016] The anode of the first diode is connected to the second end of the third transistor and the power supply end, the cathode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the hysteresis comparison unit;

[0017] a first terminal of the fourth transistor is connected to the cathode of the first diode and the cathode of the second diode, a second terminal of the fourth transistor is connected to the power input terminal, and a third terminal of the fourth transistor is connected to the first terminal of the fifth transistor;

[0018] A second terminal of the fifth transistor is connected to the negative connection terminal of the heating load, and a third terminal of the fifth transistor is grounded.

[0019] Furthermore, the hysteresis comparison unit includes a voltage follower and a hysteresis comparator;

[0020] The first input terminal of the voltage follower is coupled to the monitoring unit, the second input terminal of the voltage follower is connected to the output terminal of the voltage follower, and the output terminal of the voltage follower is coupled to the first input terminal of the hysteresis comparator;

[0021] The first input terminal of the hysteresis comparator is coupled to the output terminal of the hysteresis comparator, the second input terminal of the hysteresis comparator is used to receive a reference voltage signal; the output terminal of the hysteresis comparator is coupled to the heating unit.

[0022] Furthermore, the monitoring unit includes a first temperature monitoring circuit, a second temperature monitoring circuit and a current monitoring circuit;

[0023] The first temperature monitoring circuit is connected to the first temperature detection end of the heating load, the hysteresis comparison unit and the control unit, and is used to collect the first temperature signal corresponding to the first temperature detection end and output the first temperature signal to the hysteresis comparison unit and the control unit;

[0024] The second temperature monitoring circuit is connected to the second temperature detection end of the heating load and the control unit, and is used to collect a second temperature signal corresponding to the second temperature detection end and output the second temperature signal to the control unit;

[0025] The current monitoring circuit is connected to the heating unit and the control unit, and is used to output the current sampling signal to the control unit.

[0026] Furthermore, the hysteresis comparison unit is used to output a second control signal for controlling the heating unit to enter a non-heating state when the first temperature signal is greater than a first preset temperature; and to output a second control signal for controlling the heating unit to enter a heating state when the first temperature signal is not greater than the first preset temperature.

[0027] Furthermore, the control unit is used to output a first control signal for controlling the heating unit to enter a non-heating state when the first temperature signal or the second temperature signal is greater than a second preset temperature; and to output a first control signal for controlling the heating unit to enter a heating state based on the current sampling signal, the first temperature signal and the second temperature signal when the first temperature signal and the second temperature signal are not greater than the second preset temperature.

[0028] A heating control system comprises the above-mentioned heating circuit and a heating load, wherein the heating load is a heating film.

[0029] A ventilator comprises a breathing valve and the above-mentioned heating control system, wherein the breathing valve is connected to a heating film of the heating control system.

[0030] The above-mentioned heating circuit, heating control system and ventilator connect the heating unit to the heating load so that the heating unit enters a heating state or a non-heating state according to a first control signal and a second control signal, connects the monitoring unit to the heating unit, the heating load, the control unit and the hysteresis comparison unit, and enables the monitoring unit to sample the heating load to obtain a target sampling signal, outputs the target sampling signal to the hysteresis comparison unit and the control unit respectively, connects the hysteresis comparison unit to the heating unit, enables the hysteresis comparison unit to perform anomaly detection according to the target sampling signal, outputs the second control signal to the heating unit, and finally connects the control unit to the heating unit. The control unit outputs a first control signal to the heating unit according to the target sampling signal, so that when the hysteresis comparison unit fails, the control unit outputs the first control signal to the heating unit according to the target sampling signal, so that the heating unit enters a heating state or a non-heating state, or when the control unit fails, the hysteresis comparison unit performs an abnormality detection according to the target sampling signal and outputs a second control signal to the heating unit, so that the heating unit enters a heating state or a non-heating state, thereby realizing multiple cut-off modes, ensuring that when the heating load temperature is abnormal, the power supply can be normally cut off, realizing closed-loop control of the heating load temperature, and improving the safety of the heating circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 is a circuit diagram of a heating control system according to an embodiment of the present invention;

[0033] Figure 2 is a circuit diagram of a heating unit in one embodiment of the present invention;

[0034] Figure 3 is a circuit diagram of a hysteresis comparison unit in one embodiment of the present invention;

[0035] Figure 4 is a circuit diagram of a reference unit in one embodiment of the present invention;

[0036] Figure 5 is a circuit diagram of a first temperature monitoring circuit in one embodiment of the present invention;

[0037] Figure 6 is a circuit diagram of a second temperature monitoring circuit in one embodiment of the present invention;

[0038] Figure 7 FIG. 4 is a circuit diagram of a current monitoring circuit according to an embodiment of the present invention.

[0039] In the figure: 10, heating circuit; 11, control unit; 12, heating unit; 121, first control circuit; 122, second control circuit; 13, hysteresis comparison unit; 131, voltage follower; 132, hysteresis comparator; 14, monitoring unit; 141, first temperature monitoring circuit; 142, second temperature monitoring circuit; 143, current monitoring circuit; 20, heating load. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0042] In order to fully understand the present invention, detailed structures and steps will be provided in the following description to illustrate the technical solutions proposed by the present invention. Preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may also have other implementations.

[0043] This embodiment provides a heating circuit 10 for use in Figure 1 The heating control system shown in FIG. The heating control system includes the heating circuit 10 and a heating load 20. Preferably, the heating load 20 is a heating film. In this embodiment, the heating circuit 10 is connected to the heating load 20 to heat the heating load 20 and promptly cut off power supply when the temperature of the heating load 20 is abnormal, thereby ensuring the safety of the heating control system.

[0044] This embodiment provides a heating circuit 10, such as Figure 1As shown, it includes a control unit 11, a heating unit 12, a hysteresis comparison unit 13 and a monitoring unit 14; the heating unit 12 is connected to the heating load 20, and is used to enter a heating state or a non-heating state according to a first control signal and a second control signal; the monitoring unit 14 is connected to the heating unit 12, the heating load 20, the control unit 11 and the hysteresis comparison unit 13, and is used to sample the heating load 20, obtain a target sampling signal, and output the target sampling signal to the hysteresis comparison unit 13 and the control unit 11 respectively; the hysteresis comparison unit 13 is connected to the heating unit 12, and is used to perform abnormality detection according to the target sampling signal and output a second control signal to the heating unit 12; the control unit 11 is connected to the heating unit 12, and is used to output a first control signal to the heating unit 12 according to the target sampling signal.

[0045] The first control signal refers to the signal output by the control unit 11 , and the second control signal refers to the signal output by the hysteresis comparison unit 13 .

[0046] In one specific embodiment, the heating unit 12 is connected to the heating load 20 and is configured to enter a heating state or a non-heating state based on a first control signal and a second control signal. In this embodiment, when the temperature of the heating load 20 is normal, the heating unit 12 enters the heating state based on the first control signal and the second control signal and heats the heating load 20. When the temperature of the heating load 20 is abnormal, the heating unit 12 enters the non-heating state based on the first control signal and the second control signal and stops heating the heating load 20.

[0047] In a specific embodiment, the monitoring unit 14 is connected to the heating unit 12, the heating load 20, the control unit 11 and the hysteresis comparison unit 13, and is used to sample the heating load 20, obtain a target sampling signal, and output the target sampling signal to the hysteresis comparison unit 13 and the control unit 11 respectively. Optionally, the target sampling signal includes but is not limited to an electrical signal corresponding to the heating temperature and an electrical signal corresponding to the heating current. In this embodiment, the heating load 20 is sampled, the target sampling signal is obtained, and the target sampling signal is output to the hysteresis comparison unit 13 and the control unit 11 respectively, so that the hysteresis comparison unit 13 and the control unit 11 can analyze the target sampling signal and determine whether the heating temperature of the heating load 20 is abnormal, thereby realizing closed-loop control of the heating temperature of the heating load 20.

[0048] In a specific embodiment, the hysteresis comparison unit 13 is connected to the heating unit 12 and is configured to perform an abnormality detection based on the target sampling signal and output a second control signal to the heating unit 12. The control unit 11 is connected to the heating unit 12 and is configured to output a first control signal to the heating unit 12 based on the target sampling signal. In this embodiment, the hysteresis comparison unit 13 performs an abnormality detection based on the target sampling signal and outputs the second control signal to the heating unit 12, and the control unit 11 outputs the first control signal to the heating unit 12 based on the target sampling signal. Thus, when the hysteresis comparison unit 13 fails, the control unit 11 outputs the first control signal to the heating unit 12 based on the target sampling signal, causing the heating unit 12 to enter a heating state or a non-heating state. Alternatively, when the control unit 11 fails, the hysteresis comparison unit 13 performs an abnormality detection based on the target sampling signal and outputs the second control signal to the heating unit 12, causing the heating unit 12 to enter a heating state or a non-heating state. This implements multiple cutoff modes, ensuring that power supply can be properly cut off when the temperature of the heating load 20 is abnormal, achieving closed-loop control of the temperature of the heating load 20, and improving the safety of the heating circuit 10.

[0049] In this embodiment, the heating unit 12 is connected to the heating load 20, so that the heating unit 12 enters a heating state or a non-heating state according to the first control signal and the second control signal, and the monitoring unit 14 is connected to the heating unit 12, the heating load 20, the control unit 11 and the hysteresis comparison unit 13, and the monitoring unit 14 samples the heating load 20 to obtain a target sampling signal, and outputs the target sampling signal to the hysteresis comparison unit 13 and the control unit 11 respectively, and the hysteresis comparison unit 13 is connected to the heating unit 12, so that the hysteresis comparison unit 13 performs an abnormality detection according to the target sampling signal and outputs the second control signal to the heating unit 12, and finally the control unit 11 is connected to the heating unit 12. The control unit 11 outputs a first control signal to the heating unit 12 according to the target sampling signal, so that when the hysteresis comparison unit 13 fails, the control unit 11 outputs a first control signal to the heating unit 12 according to the target sampling signal, so that the heating unit 12 enters a heating state or a non-heating state, or when the control unit 11 fails, the hysteresis comparison unit 13 performs an abnormality detection according to the target sampling signal and outputs a second control signal to the heating unit 12, so that the heating unit 12 enters a heating state or a non-heating state, thereby realizing multiple cut-off modes, ensuring that when the temperature of the heating load 20 is abnormal, the power supply can be normally cut off, realizing closed-loop control of the temperature of the heating load 20, and improving the safety of the heating circuit 10.

[0050] In one embodiment, if Figure 2As shown, the heating unit 12 includes a first control circuit 121 and a second control circuit 122. The first control circuit 121 is used to connect the power input terminal HEAT_VCC and the positive connection terminal HEAT+ of the heating load 20, and the second control circuit 122 is used to connect the negative connection terminal HEAT- of the heating load 20 and the ground; the control circuit is connected to the first control circuit 121 and the second control circuit 122, and is used to output a first control signal to control the on and off of the first control circuit 121 and the second control circuit 122; the hysteresis comparison unit 13 is connected to the second control circuit 122, and is used to output a second control signal to control the on and off of the second control circuit 122.

[0051] In a specific embodiment, the first control circuit 121 is used to connect the power input terminal HEAT_VCC and the positive connection terminal HEAT+ of the heating load 20, and the second control circuit 122 is used to connect the negative connection terminal HEAT- of the heating load 20 and the ground GND, so as to form a power supply circuit for the heating load 20.

[0052] In one specific embodiment, the control circuit is connected to the first control circuit 121 and the second control circuit 122, and is configured to output a first control signal to control the on / off switching of the first control circuit 121 and the second control circuit 122. In this embodiment, when the temperature of the heating load 20 is abnormal, the first control circuit 121 is controlled to be disconnected, that is, the power input terminal HEAT_VCC and the positive terminal HEAT+ of the heating load 20 are disconnected, and the second control circuit 122 is controlled to be disconnected, that is, the negative terminal HEAT- of the heating load 20 is disconnected from the ground, thereby placing the heating unit 12 in a non-heating state. When the temperature of the heating load 20 is normal, the first control circuit 121 is controlled to be conductive, that is, the power input terminal HEAT_VCC and the positive terminal HEAT+ of the heating load 20 are connected, and the second control circuit 122 is controlled to be conductive, that is, the negative terminal HEAT- of the heating load 20 is connected to the ground, thereby placing the heating unit 12 in a heating state.

[0053] In a specific embodiment, the hysteresis comparison unit 13 is connected to the second control circuit 122 and is configured to output a second control signal to control the on / off switching of the second control circuit 122. In this embodiment, when the temperature of the heating load 20 is abnormal, the second control circuit 122 is controlled to be disconnected, and when the temperature of the heating load 20 is normal, the second control circuit 122 is controlled to be connected. Therefore, even if the control unit 11 fails, the second control circuit 122 can still be controlled to be disconnected when the temperature of the heating load 20 is abnormal, thereby cutting off the power supply circuit of the heating load 20. This ensures that the power supply is normally cut off when the temperature of the heating load 20 is abnormal, thereby achieving closed-loop control of the temperature of the heating load 20 and improving the safety of the heating circuit 10.

[0054] In one embodiment, if Figure 2As shown, the first control circuit 121 includes a first transistor Q1 and a second transistor Q2; a first end of the first transistor Q1 is coupled to the control unit 11 (PWM_HEAT), a second end of the first transistor Q1 is coupled to a first end of the second transistor Q2, a third end of the first transistor Q1 is grounded, a second end of the second transistor Q2 is coupled to the power input terminal HEAT_VCC, and a third end of the second transistor Q2 is coupled to the positive connection terminal HEAT+ of the heating load 20.

[0055] Optionally, the first transistor Q1 may be a triode or a field effect transistor. The second transistor Q2 may be a triode or a field effect transistor.

[0056] Preferably, the first transistor Q1 is a triode, preferably an NPN triode. The second transistor Q2 is a field effect transistor, preferably a PMOS transistor.

[0057] In a specific embodiment, the first end of the first transistor Q1 is a base, the second end of the first transistor Q1 is a collector, and the third end of the first transistor Q1 is an emitter. The first end of the second transistor Q2 is a gate, the second end of the second transistor Q2 is a source, and the third end of the second transistor Q2 is a drain.

[0058] In a specific embodiment, the heating circuit 10 also includes a resettable fuse F1, the first end of the resettable fuse F1 is connected to the second end of the second transistor Q2, and the second end of the resettable fuse F1 is connected to the power input terminal HEAT_VCC, which is used to prevent the heating current from being too high and protect the power supply connected to the power input terminal HEAT_VCC.

[0059] In a specific embodiment, the heating circuit 10 further includes a temperature-controlled switch F2, a first end of which is connected to the third end of the second transistor Q2, and a second end of which is connected to the positive connection terminal HEAT+ of the heating load 20, for automatically cutting off power supply when the temperature of the heating load 20 exceeds the operating temperature of the temperature-controlled switch F2.

[0060] In one specific embodiment, the first control circuit 121 further includes a first voltage-dividing resistor R1211, a second voltage-dividing resistor R1212, and a first pull-up resistor R1213. The first voltage-dividing resistor R1211 and the second voltage-dividing resistor R1212 are connected in series between the control unit 11 and ground, and the connection node between the first voltage-dividing resistor R1211 and the second voltage-dividing resistor R1212 is connected to the first end of the first transistor Q1. The first end of the first pull-up resistor R1213 is coupled to the power input terminal HEAT_VCC, and the second end of the first pull-up resistor R1213 is connected to the second end of the first transistor Q1 and the first end of the second transistor Q2.

[0061] In a specific embodiment, the first control circuit 121 further includes a first filter capacitor C1211 , a first end of the first filter capacitor C1211 is connected to the control unit 11 and the first end of the first transistor Q1 , and a second end of the first filter capacitor C1211 is grounded.

[0062] In this embodiment, when the heating circuit 10 begins operation or the temperature of the heating load 20 is normal, the control circuit outputs a first control signal to the first transistor Q1 to control the conduction. The first transistor Q1 is turned on, and the second transistor Q2 is turned on, thereby connecting the power input terminal HEAT_VCC and the positive connection terminal HEAT+ of the heating load 20. When the heating circuit 10 ends operation or the temperature of the heating load 20 is abnormal, the control circuit outputs a first control signal to the first terminal of the first transistor Q1 to control the shutdown of the first transistor Q1. The first transistor Q1 is turned off, and the second transistor Q2 is turned off, thereby disconnecting the power input terminal HEAT_VCC and the positive connection terminal HEAT+ of the heating load 20.

[0063] Optionally, when the heating circuit 10 starts working or the temperature of the heating load 20 is normal, the first control signal output by the control circuit to the first end of the first transistor Q1 can be a PWM signal. The control unit 11 forms a PWM signal based on the target sampling signal obtained by the monitoring unit 14, and controls the on and off of the first transistor Q1 through the PWM signal to form a closed-loop PID temperature control. It can be understood that the first control signal can also be a high-level signal or a low-level signal. When the heating circuit 10 starts working or the temperature of the heating load 20 is normal, the control circuit outputs a high-level signal to control the first transistor Q1 to turn on. When the heating circuit 10 stops working or the temperature of the heating load 20 is abnormal, the control circuit outputs a low-level signal to control the first transistor Q1 to turn off.

[0064] In one embodiment, if Figure 2As shown, the second control circuit 122 includes a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a first diode D1, and a second diode D2; a first end of the third transistor Q3 is coupled to the control unit 11 (EN_HEAT-), a second end of the third transistor Q3 is coupled to the power supply terminal +V3A, and a third end of the third transistor Q3 is grounded; an anode of the first diode D1 is connected to the second end of the third transistor Q3 and the power supply terminal +V3A, a cathode of the first diode D1 is connected to the cathode of the second diode D2, and an anode of the second diode D2 is connected to the hysteresis comparison unit 13 (Disable_HEAT); a first end of the fourth transistor Q4 is connected to the cathode of the first diode D1 and the cathode of the second diode D2, a second end of the fourth transistor Q4 is connected to the power input terminal HEAT_VCC, and a third end of the fourth transistor Q4 is connected to the first end of the fifth transistor Q5; a second end of the fifth transistor Q5 is connected to the negative electrode connection terminal HEAT- of the heating load 20, and a third end of the fifth transistor Q5 is grounded.

[0065] In a specific embodiment, the third transistor Q3, the fourth transistor Q4, and the fifth transistor Q5 can each be a triode or a field-effect transistor. Preferably, the third transistor Q3 and the fifth transistor Q5 are triodes. The fourth transistor Q4 is a field-effect transistor. Exemplarily, the third transistor Q3 and the fifth transistor Q5 are both NPN-type triodes. The fourth transistor Q4 is a PMOS transistor. The first end of the third transistor Q3 is a base, the second end of the third transistor Q3 is a collector, and the third end of the third transistor Q3 is an emitter. The first end of the fourth transistor Q4 is a gate, the second end of the fourth transistor Q4 is a source, and the third end of the fourth transistor Q4 is a drain.

[0066] In one specific embodiment, the second control circuit 122 further includes a third voltage-dividing resistor R1221, a fourth voltage-dividing resistor R1222, a second pull-up resistor R1223, a third pull-up resistor R1224, a first drive resistor R1225, a second drive resistor R1226, and a sampling resistor R1227. The third voltage-dividing resistor R1221 and the fourth voltage-dividing resistor R1222 are connected in series between the control circuit and ground, and the connection node between the third voltage-dividing resistor R1221 and the fourth voltage-dividing resistor R1222 is connected to the first end of the third transistor Q3. The first end of the second pull-up resistor R1223 is connected to the second end of the third transistor Q3, and the second end of the second pull-up resistor R1223 is connected to the power supply terminal +V3A. The first end of the third pull-up resistor R1224 is connected to the second end of the fourth transistor Q4, and the second end of the third pull-up resistor R1224 is connected to the input power terminal. The first end of the first drive resistor R1225 is connected to the cathode of the first diode D1 and the cathode of the second diode D2. The second end of the first drive resistor R1225 is connected to the first end of the fourth transistor Q4. The first end of the second drive resistor R1226 is connected to the third end of the fourth transistor Q4 and the first end of the fifth transistor Q5. The second end of the second drive resistor R1226 is grounded. The first end of the sampling resistor R1227 is connected to the third end of the fifth transistor Q5. The second end of the sampling resistor R1227 is grounded. In this embodiment, the monitoring unit 14 is connected to the first end HEAT_GND of the sampling resistor R1227 and the third end of the fifth transistor Q5 to sample the heating load 20 and obtain a target sampling signal. The target sampling signal is a current sampling signal, i.e., corresponding to the heating current of the heating load 20. In this embodiment, when the temperature of the heating load 20 rises or falls, the hysteresis comparison unit 13 performs an abnormality detection based on the target sampling signal. When the temperature of the heating load 20 is too high, the hysteresis comparison unit 13 outputs a high-level signal to the heating unit 12. Because first diode D1 and second diode D2 form an OR gate circuit, when hysteresis comparator 13 outputs a high-level signal, fourth transistor Q4 is turned off, thereby also turning off fifth transistor Q5, severing the connection between the negative electrical connection terminal of heating load 20 and ground, thus shutting off the heating. Therefore, even if control unit 11 malfunctions and the temperature of heating load 20 is abnormal, the connection between the negative connection terminal HEAT- of heating load 20 and ground can still be promptly disconnected, thereby severing the power supply circuit and ensuring the safety and reliability of heating circuit 10.

[0067] In this embodiment, the control unit 11 and the hysteresis comparison unit 13 can both control the on and off of the second control circuit 122, so that when any unit in the control unit 11 or the hysteresis comparison unit 13 fails and the temperature of the heating load 20 is abnormal, the negative connection terminal HEAT- and the ground of the heating load 20 can still be turned off in time, thereby cutting off the power supply circuit and ensuring the safety and reliability of the heating circuit 10.

[0068] In one embodiment, if Figure 3 As shown, the hysteresis comparison unit 13 includes a voltage follower 131 and a hysteresis comparator 132; the first input end of the voltage follower 131 is coupled to the monitoring unit 14 (ADC NTC1), the second input end of the voltage follower 131 is connected to the output end of the voltage follower 131, and the output end of the voltage follower 131 is coupled to the first input end of the hysteresis comparator 132; the first input end of the hysteresis comparator 132 is coupled to the output end of the hysteresis comparator 132, and the second input end of the hysteresis comparator 132 is used to receive a reference voltage signal; the output end of the hysteresis comparator 132 is coupled to the heating unit 12.

[0069] In this embodiment, the voltage follower 131 receives the target sampling signal of the monitoring unit 14, which is a voltage sampling signal corresponding to the temperature of the heating load 20. The target sampling signal is output to the hysteresis comparator 132 through the voltage follower 131 for comparison, so that the hysteresis comparator 132 determines whether the temperature of the heating load 20 is abnormal based on the voltage signal. When the temperature of the heating load 20 is abnormal, the second control signal is output to the heating unit 12 to cut off the connection between the positive connection terminal HEAT+ of the heating load 20 and the power input terminal HEAT_VCC, thereby cutting off the power supply in time.

[0070] Further, if Figure 4 As shown, the hysteresis comparison unit 13 includes a reference unit, which is used to provide the reference voltage signal.

[0071] In one specific embodiment, the reference unit includes an operational amplifier; a first input of the operational amplifier is coupled to a power supply terminal +V3A, a second input of the operational amplifier is coupled to an output of the operational amplifier, and the output of the operational amplifier is coupled to a second input of the hysteresis comparator 132. In this embodiment, the voltage of the power supply terminal +V3A and the configuration of the operational amplifier can be configured based on practical experience to provide a suitable reference voltage signal. It should be noted that the reference unit can also utilize techniques known to those skilled in the art to ensure that the reference unit can provide a suitable reference voltage signal, and this is not limited here.

[0072] For example, Figure 3As shown, the first input terminal of the voltage follower 131 is connected to the monitoring unit 14 (ADC NTC1) via a resistor R1311. The output terminal of the voltage follower 131 is connected to the first input terminal of the hysteresis comparator 132 via a resistor R1312. One end of a capacitor C1311 is connected to the resistor R1311 and the output terminal of the voltage follower 131, and the other end is grounded. The first input terminal of the hysteresis comparator 132 is connected to the output terminal of the hysteresis comparator 132 via a resistor R1313. The second input terminal of the hysteresis comparator 132 is connected to the reference unit via a resistor R1314. One end of the capacitor C1312 is connected to the resistor R1314 and the second input terminal of the hysteresis comparator 132, and the other end is grounded. Resistors R1315 and R1316 are connected in series between the power supply terminal +V3A and the heating unit 12 (Disable HEAT). The junction point between the resistors R1315 and R1316 is connected to the output terminal of the hysteresis comparator 132.

[0073] like Figure 4 As shown, the first input terminal of the operational amplifier is connected to the power supply terminal +V3A via a resistor R1331, and the second input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a resistor R1332 and grounded via a resistor R1333. The output terminal of the operational amplifier is connected to the second input terminal (VREF) of the hysteresis comparator 132 via a resistor R1334. One end of a resistor R1335 is connected to the first input terminal of the operational amplifier, and the other end is grounded. A capacitor C1331 is connected in parallel with the resistor R1335. One end of a capacitor C1332 is connected to the second input terminal (VREF) of the hysteresis comparator 132, and the other end is grounded.

[0074] In one embodiment, if Figure 5-7 As shown, the monitoring unit 14 includes a first temperature monitoring circuit 141, a second temperature monitoring circuit 142 and a current monitoring circuit 143; the first temperature monitoring circuit 141 is connected to the first temperature detection end of the heating load 20, the hysteresis comparison unit 13 and the control unit 11, and is used to collect a first temperature signal corresponding to the first temperature detection end, and output the first temperature signal to the hysteresis comparison unit 13 and the control unit 11; the second temperature monitoring circuit 142 is connected to the second temperature detection end of the heating load 20 and the control unit 11, and is used to collect a second temperature signal corresponding to the second temperature detection end, and output the second temperature signal to the control unit 11; the current monitoring circuit 143 is connected to the heating unit 12 and the control unit 11, and is used to output a current sampling signal to the control unit 11.

[0075] In this embodiment, two first temperature monitoring circuits 141 and second temperature monitoring circuits 142 are provided to perform temperature detection to prevent one circuit from failing while the other circuit can perform temperature detection normally, thereby more reliably detecting the temperature of the heating load 20 and facilitating closed-loop control of the temperature of the heating load 20.

[0076] In a specific embodiment, if Figure 5As shown, the first temperature detection circuit includes a first common-mode inductor L1411, a first capacitor C1411, a second capacitor C1412, a third capacitor C1413, a fourth capacitor C1414, a fifth capacitor C1415, a first resistor R1411, a second resistor R1412, a third resistor R1413, a fourth resistor R1414, a fifth resistor R1415 and a first comparator U1411; a first input end of the first common-mode inductor L1411 is connected to the positive electrode NTC1+ of the first temperature detection end of the heating load 20, a second input end of the first common-mode inductor L1411 is connected to the negative electrode NTC1- of the first temperature detection end of the heating load 20, a first output end of the first common-mode inductor L1411 is connected to the power supply end +V3A, and a second output end of the first common-mode inductor L1411 is coupled to the first input end of the first comparator U1411. The second input terminal of the first comparator U1411 is coupled to the output terminal of the first comparator U1411 and ground. The positive terminal of the first comparator U1411 is connected to the power supply terminal +V3A, and the negative terminal of the first comparator U1411 is connected to ground. The first capacitor C1411 and the second capacitor C1412 are connected in series between the first output terminal and the second output terminal of the first common-mode inductor L1411. The first end of the third capacitor C1413 is connected to the power supply terminal +V3A, and the second end of the third capacitor C1413 is connected to the first end of the first resistor R1411, the first end of the second resistor R1412, and the second output terminal of the first common-mode inductor L1411. The second end of the first resistor R1411 is grounded, and the second end of the second resistor R1412 is connected to the first input terminal of the first comparator U1411. The first end of the third resistor R1413 is connected to the second input terminal of the first comparator U1411, and the second end of the third resistor R1413 is grounded. A first end of the fourth resistor R1414 is connected to the first end of the third resistor R1413 and the second input end of the first comparator U1411, and a second end of the fourth resistor R1414 is connected to the output end of the first comparator U1411. A first end of the fifth resistor R1415 is connected to the output end of the first comparator U1411, and a second end of the fifth resistor R1415 is connected to the hysteresis comparator unit 13 and the control unit 11. A first end of the fourth capacitor C1414 is connected to the power supply terminal +V3A and the positive terminal of the first comparator U1411, and a second end of the fourth capacitor C1414 is grounded. A first end of the fifth capacitor C1415 is connected to the second end of the fifth resistor R1415, the hysteresis comparator unit 13, and the control unit 11, and a second end of the fifth capacitor C1415 is grounded.

[0077] In a specific embodiment, if Figure 6As shown, the second temperature detection circuit includes a second common-mode inductor L1421, a sixth capacitor C1421, a seventh capacitor C1422, an eighth capacitor C1423, a ninth capacitor C1424, a tenth capacitor C1425, a sixth resistor R1421, a seventh resistor R1422, an eighth resistor R1423, a ninth resistor R1424, a tenth resistor R1425 and a second comparator U1421. The specific connection relationship of the above components is shown in FIG. Figure 6 As shown, no further details are given here.

[0078] In a specific embodiment, the current monitoring circuit 143 includes a third common-mode inductor L1431, an eleventh capacitor C1431, a twelfth capacitor C1432, a thirteenth capacitor C1433, a fourteenth capacitor C1434, a fifteenth capacitor C1435, an eleventh resistor R1421, a twelfth resistor R1422, a thirteenth resistor R1423, a fourteenth resistor R1424, a fifteenth resistor R1425, and a third comparator U1431. The specific connection relationship of the above components is shown in FIG. Figure 7 As shown, no further details are given here.

[0079] It should be noted that the first temperature detection circuit and the second temperature detection circuit may also adopt existing temperature detection circuits, and the current monitoring circuit 143 may also adopt existing current monitoring circuit 143, which is not limited here.

[0080] In one embodiment, the hysteresis comparison unit 13 is configured to output a second control signal for controlling the heating unit 12 to enter a non-heating state when the first temperature signal is greater than a first preset temperature; and to output the second control signal for controlling the heating unit 12 to enter a heating state when the first temperature signal is not greater than the first preset temperature. In this embodiment, the hysteresis comparison unit 13 outputs the second control signal for controlling the heating unit 12 to enter a non-heating state when the first temperature signal is greater than the first preset temperature; and outputs the second control signal for controlling the heating unit 12 to enter a heating state when the first temperature signal is not greater than the first preset temperature. Thus, even if the control unit 11 fails and the temperature of the heating load 20 is abnormal, the negative connection terminal HEAT- of the heating load 20 can still be promptly disconnected from the ground, thereby severing the power supply circuit and ensuring the safety and reliability of the heating circuit 10.

[0081] In one embodiment, the control unit 11 is used to output a first control signal for controlling the heating unit 12 to enter a non-heating state when the first temperature signal or the second temperature signal is greater than a second preset temperature; and output a first control signal for controlling the heating unit 12 to enter a heating state based on the current sampling signal, the first temperature signal, and the second temperature signal when the first temperature signal and the second temperature signal are not greater than the second preset temperature.

[0082] The second preset temperature is lower than the first preset temperature. For example, the second preset temperature is 45 degrees and the first preset temperature is 50 degrees.

[0083] In this embodiment, the control unit 11 outputs a first control signal for controlling the heating unit 12 to enter a non-heating state when the first temperature signal or the second temperature signal is greater than a second preset temperature. When the first temperature signal and the second temperature signal are not greater than the second preset temperature, the control unit 11 outputs a first control signal for controlling the heating unit 12 to enter a heating state based on the current sampling signal, the first temperature signal, and the second temperature signal. This allows the power supply circuit to be promptly cut off when the temperature of the heating load 20 is abnormal. Furthermore, if the control unit 11 malfunctions and is unable to cut off the power supply to the heating load 20 at the second preset temperature, the hysteresis comparator 13 can also cut off the power supply circuit when the temperature of the heating load 20 reaches the first preset temperature, thereby ensuring the safety and reliability of the heating circuit 10.

[0084] This embodiment provides a heating control system, including the above-mentioned heating circuit 10 and a heating load 20 , where the heating load 20 is a heating film.

[0085] This embodiment provides a ventilator, including a breathing valve and the above-mentioned heating control system, wherein the breathing valve is connected to the heating film of the heating control system.

[0086] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A heating circuit, characterized in that: It includes a control unit, a heating unit, a hysteresis comparison unit and a monitoring unit; The heating unit is connected to the heating load and is used to enter a heating state or a non-heating state according to a first control signal and a second control signal; The monitoring unit is connected to the heating unit, the heating load, the control unit and the hysteresis comparison unit, and is used to sample the heating load, obtain a target sampling signal, and output the target sampling signal to the hysteresis comparison unit and the control unit respectively; The hysteresis comparison unit is connected to the heating unit and is used to perform abnormality detection according to the target sampling signal and output the second control signal to the heating unit; The control unit is connected to the heating unit and is configured to output the first control signal to the heating unit according to the target sampling signal; The heating unit includes a first control circuit and a second control circuit, the first control circuit is used to connect the power input terminal and the positive connection terminal of the heating load, and the second control circuit is used to connect the negative connection terminal of the heating load and the ground; The control unit is connected to the first control circuit and the second control circuit, and is used to output the first control signal to control the on and off of the first control circuit and the second control circuit; The hysteresis comparison unit is connected to the second control circuit and is used to output the second control signal to control the on and off of the second control circuit; The first control circuit includes a first transistor and a second transistor; A first terminal of the first transistor is coupled to the control unit, a second terminal of the first transistor is coupled to a first terminal of the second transistor, a third terminal of the first transistor is grounded, a second terminal of the second transistor is coupled to the power input terminal, and a third terminal of the second transistor is coupled to the positive connection terminal of the heating load.

2. The heating circuit according to claim 1, wherein: The second control circuit includes a third transistor, a fourth transistor, a fifth transistor, a first diode and a second diode; A first terminal of the third transistor is coupled to the control unit, a second terminal of the third transistor is coupled to the power supply terminal, and a third terminal of the third transistor is grounded; The anode of the first diode is connected to the second end of the third transistor and the power supply end, the cathode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the hysteresis comparison unit; a first terminal of the fourth transistor is connected to the cathode of the first diode and the cathode of the second diode, a second terminal of the fourth transistor is connected to the power input terminal, and a third terminal of the fourth transistor is connected to the first terminal of the fifth transistor; A second terminal of the fifth transistor is connected to the negative connection terminal of the heating load, and a third terminal of the fifth transistor is grounded.

3. The heating circuit according to claim 1, wherein: The hysteresis comparison unit includes a voltage follower and a hysteresis comparator; The first input terminal of the voltage follower is coupled to the monitoring unit, the second input terminal of the voltage follower is connected to the output terminal of the voltage follower, and the output terminal of the voltage follower is coupled to the first input terminal of the hysteresis comparator; The first input terminal of the hysteresis comparator is coupled to the output terminal of the hysteresis comparator, the second input terminal of the hysteresis comparator is used to receive a reference voltage signal; the output terminal of the hysteresis comparator is coupled to the heating unit.

4. The heating circuit according to claim 1, wherein: The monitoring unit includes a first temperature monitoring circuit, a second temperature monitoring circuit and a current monitoring circuit; The first temperature monitoring circuit is connected to the first temperature detection end of the heating load, the hysteresis comparison unit and the control unit, and is used to collect the first temperature signal corresponding to the first temperature detection end and output the first temperature signal to the hysteresis comparison unit and the control unit; The second temperature monitoring circuit is connected to the second temperature detection end of the heating load and the control unit, and is used to collect a second temperature signal corresponding to the second temperature detection end and output the second temperature signal to the control unit; The current monitoring circuit is connected to the heating unit and the control unit, and is used to output a current sampling signal to the control unit.

5. The heating circuit according to claim 4, characterized in that The hysteresis comparison unit is used to output a second control signal for controlling the heating unit to enter a non-heating state when the first temperature signal is greater than a first preset temperature; and to output a second control signal for controlling the heating unit to enter a heating state when the first temperature signal is not greater than the first preset temperature.

6. The heating circuit according to claim 4, characterized in that The control unit is used to output a first control signal for controlling the heating unit to enter a non-heating state when the first temperature signal or the second temperature signal is greater than a second preset temperature; and output a first control signal for controlling the heating unit to enter a heating state based on the current sampling signal, the first temperature signal and the second temperature signal when the first temperature signal and the second temperature signal are not greater than the second preset temperature.

7. A heating control system, characterized in that: The heating circuit comprises the heating circuit according to any one of claims 1 to 6 and a heating load, wherein the heating load is a heating film.

8. A ventilator, characterized in that: The heating control system comprises a breathing valve and the heating control system according to claim 7, wherein the breathing valve is connected to the heating film of the heating control system.

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