Heating control circuit and wind turbine generator frequency conversion system
By introducing a heating control circuit into the wind turbine frequency conversion system, and using multiple temperature sensors and voltage comparators to control the heater, the problem of condensation on the surface of power electronic devices is solved, effective temperature management is achieved, and the devices are protected from condensation damage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2026-03-24
AI Technical Summary
Existing temperature control systems cannot effectively prevent condensation on the surface of power electronic devices in wind turbine frequency conversion systems, especially when the ambient temperature rises, the existing system fails to heat in time to prevent condensation.
A heating control circuit is used. The surface temperature of the power electronic device is collected by a first temperature sensor and the ambient temperature is collected by a second temperature sensor. A differential amplifier calculates the temperature difference and a voltage comparator controls the heater to heat the power electronic device so that its surface temperature is higher than the dew point temperature, thus preventing condensation.
It effectively avoids condensation on the surface of power electronic devices, protects the devices from moisture damage, and improves the reliability and durability of the system.
Smart Images
Figure CN224032707U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to temperature control technical field especially is related to a heating control circuit and wind turbine generator system variable frequency system. BACKGROUND
[0002] The temperature control of wind turbine generator system variable frequency system is very important, and poor temperature control can damage power electronic devices in the wind turbine generator system variable frequency system due to condensation and damp, especially the insulated gate bipolar transistor (IGBT) of the frequency converter in the wind turbine generator system variable frequency system. The IGBT is not only valuable, but also takes a long time to replace, especially the water-cooled IGBT, which often takes 4-5 hours to replace. Therefore, the temperature of the IGBT and other power electronic devices needs to be controlled to prevent water condensation on the surface of the IGBT and other power electronic devices to avoid damage to the power electronic devices due to damp.
[0003] At present, the humidity of the environment where the power electronic devices in the existing wind turbine generator system variable frequency system are located is often kept constant. On this basis, the wind turbine generator system variable frequency system controls the temperature of the IGBT and other power electronic devices through a temperature control system. The temperature control method is to collect the surface temperature of the power electronic devices, and when the surface temperature is lower than the dew point temperature of the specific humidity and the normal temperature, the power electronic devices are heated to prevent condensation on the surface of the power electronic devices.
[0004] However, the dew point temperature that causes condensation on the surface of the power electronic devices is related to the ambient temperature of the environment where the power electronic devices are located. Under specific humidity conditions, the dew point temperature of the device surface is often lower than the specific temperature value of the ambient temperature, so the dew point temperature often changes with the change of the ambient temperature. When the ambient temperature rises, the dew point temperature at which condensation occurs on the surface of the power electronic devices will also rise. The existing temperature control system only considers the surface temperature of the power electronic devices, but does not consider the ambient temperature of the environment where the power electronic devices are located. When the ambient temperature of the environment where the power electronic devices are located rises, the surface temperature of the power electronic devices may still be higher than the dew point temperature at normal temperature, so even if the surface temperature of the power electronic devices is lower than the dew point temperature at the current environment, the temperature control system will not heat the power electronic devices, which may cause condensation on the surface of the power electronic devices. Therefore, the existing temperature control system cannot effectively prevent condensation on the surface of the power electronic devices. UTILITY MODEL CONTENTS
[0005] Therefore, the utility model provides a heating control circuit and wind turbine generator system variable frequency system, which mainly aims to solve the technical problem that the existing temperature control system cannot effectively prevent condensation on the surface of the power electronic devices.
[0006] To achieve the above object, the utility model provides a heating control circuit first, the heating control circuit includes first temperature sensor, second temperature sensor, difference amplifier, first voltage comparator, voltage source and heater;
[0007] The first temperature sensor is arranged on the outer surface of the power electronic device, is used for collecting the surface temperature of the power electronic device, and sends the first temperature signal in the form of voltage signal to the first input end of the difference amplifier;
[0008] The second temperature sensor is arranged in the power cabinet where the power electronic device is located, is used for collecting the ambient temperature in the power cabinet, and sends the second temperature signal in the form of voltage signal to the second input end of the difference amplifier;
[0009] The output end of the difference amplifier is connected with the noninverting input end of the first voltage comparator, and the voltage output end of the voltage source is connected with the inverting input end of the first voltage comparator, for outputting the output voltage of preset voltage value to the inverting input end;
[0010] The output end of the first voltage comparator is connected with the control end of the heater, for sending the heating enable signal to the heater when the voltage value received from the noninverting input end is higher than the preset voltage value, to make the heater heat the power electronic device.
[0011] In an embodiment of the utility model, the first temperature sensor is a first analog output temperature sensor, and the second temperature sensor is a second analog output temperature sensor.
[0012] In an embodiment of the utility model, the heating control circuit further includes a controller, the control end of the controller is connected with the control end of the voltage source, for controlling the voltage value of the output voltage output by the voltage source.
[0013] In an embodiment of the utility model, the heating control circuit further includes a second voltage comparator, the noninverting input end of the second voltage comparator is connected with the output end of the first temperature sensor, to receive the first temperature signal, the inverting input end of the second voltage comparator is connected with the output end of the second temperature sensor, to receive the second temperature signal, and the control end of the heater is connected with the output end of the second voltage comparator, for stopping heating the power electronic device when receiving the heating stop signal from the second voltage comparator.
[0014] In an embodiment of the utility model, the heater includes switch device and heating unit, the first end of switch device is connected with external power supply, the second end of switch device is connected with the power end of heating unit, the control end of switch device is connected with the output end of first voltage comparator, is used for being in the on state when receiving the heating enable signal from first voltage comparator, the heating unit is arranged at power electronic device, is used for when obtaining power supply from external power supply, power supply is provided for power electronic device.
[0015] In an embodiment of the utility model, the control end of the controller is also connected with the control end of the switch device to control the switch device to be in the on state or the off state.
[0016] In an embodiment of the utility model, the heating control circuit further comprises a condensation alarm; the power end of the condensation alarm is connected with the second end of the switch device, and the condensation alarm is used to issue a condensation alarm when power supply is obtained from the external power supply.
[0017] In an embodiment of the utility model, the condensation alarm is a buzzer or a flash lamp.
[0018] In an embodiment of the utility model, the heating control circuit further comprises a remote communication unit; the first interaction end of the remote communication unit is connected with the interaction end of the controller, the second interaction end of the remote communication unit is connected with a host computer at a remote end, and the remote communication unit is used to establish a communication connection between the host computer and the controller.
[0019] In addition, to achieve the above object, the utility model also provides a wind turbine generator variable frequency system, the wind turbine generator variable frequency system includes the heating control circuit as described above.
[0020] The heating control circuit and the wind turbine generator variable frequency system provided by the utility model collect the surface temperature of the power electronic device through the first temperature sensor and collect the ambient temperature of the environment where the power electronic device is located through the second temperature sensor, wherein the first temperature sensor and the second temperature sensor respectively output temperature signals in the form of an external voltage signal, and the higher the temperature value collected by the first temperature sensor and the second temperature sensor, the higher the voltage value of the temperature signal output by the first temperature sensor and the second temperature sensor. Further, the first temperature signal and the second temperature signal in the form of a voltage signal are received by the differential amplifier, the voltage difference of the voltage signals corresponding to the first temperature signal and the second temperature signal is determined, and the voltage difference is sent to the in-phase input end of the first voltage comparator in the form of a voltage.
[0021] Further, the inverting input end of the first voltage comparator receives an output voltage of a preset voltage value, wherein the preset voltage value can be a voltage value of a temperature signal in the form of a voltage signal of a temperature signal collected by a temperature sensor of a same model as the first temperature sensor and the second temperature sensor when the temperature sensor is located in an environment of a preset temperature value. Here, the preset temperature value is a temperature difference between an ambient temperature value and a dew point temperature value of a device surface under a specific humidity condition. Further, when the voltage value at the non-inverting input end of the first voltage comparator is greater than the preset voltage value, the first voltage comparator causes the heater to heat the power electronic device, so that the surface temperature of the power electronic device is higher than the dew point temperature value under the current environment, so as to effectively avoid the condensation phenomenon on the surface of the power electronic device.
[0022] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS
[0023] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:
[0024] Fig. 1 A structure schematic diagram of a heating control circuit provided by an embodiment of the present application is shown;
[0025] Fig. 2 A structure schematic diagram of another heating control circuit provided by an embodiment of the present application is shown;
[0026] Fig. 3 A structure schematic diagram of a heater provided by an embodiment of the present application is shown. DETAILED DESCRIPTION
[0027] In the following, the present application will be described in detail with reference to the drawings and in combination with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.
[0028] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined application purposes, the specific embodiments, structures, features and effects according to the present application will be described in detail below in combination with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.
[0029] The heating control circuit and the wind turbine generator system according to some embodiments of the present application are described below. Figs. 1 to 3 The heating control circuit and the wind turbine generator system according to some embodiments of the present application are described below.
[0030] As Fig. 1 An embodiment of the present application provides a heating control circuit for heating control of power electronic devices in a wind turbine generator system, wherein the power electronic devices are arranged in a power cabinet in the wind turbine generator system, and the existing wind turbine generator system has a humidity control system for maintaining the environmental humidity in the power cabinet at a constant humidity, which is mostly the design and operation humidity of the power electronic devices in the power cabinet, and the environmental humidity of the power cabinet in the existing wind turbine generator system is usually controlled between 80% and 90%.
[0031] Specifically, the heating control circuit comprises a first temperature sensor 100, a second temperature sensor 200, a differential amplifier 300, a first voltage comparator 400, a voltage source 500 and a heater 600; wherein the first temperature sensor 100 and the second temperature sensor 200 can be a first analog output temperature sensor and a second analog output temperature sensor respectively, and the models of the first analog output temperature sensor and the second analog output temperature sensor can both be LM35 temperature sensors, the output voltage of which is between +6V and -1.0V, and the output voltage is directly proportional to the collected Celsius temperature, and the output voltage of the LM35 temperature sensor increases by 10 millivolts for every 1℃ increase in Celsius temperature. Further, the differential amplifier 300 can be selected as a differential amplifier with a gain factor of 1, a differential mode gain of 1 and a common mode gain close to 0.
[0032] Further, the heater 600 can be arranged on the outer surface of the power electronic device 700 to heat the power electronic device 700, or can be arranged in a cooling water tank for water cooling of the power electronic device 700, to heat the cooling water flowing through the power electronic device 700, so as to heat the power electronic device 700 by the cooling water with higher temperature.
[0033] Further, the first voltage comparator 400 (voltage comparator) is a circuit for discriminating and comparing input signals, and is a basic unit circuit for forming a non-sinusoidal wave generating circuit.
[0034] Further, the first temperature sensor 100 is arranged on the outer surface of the power electronic device 700, and is configured to collect the surface temperature of the power electronic device 700 and send a first temperature signal in the form of a voltage signal to the first input end of the differential amplifier 300. Here, the temperature probe of the first temperature sensor 100 can be in contact with the outer surface of the power electronic device 700 to collect the surface temperature of the power electronic device 700 and output a voltage signal. Further, the first input end of the differential amplifier 300 can be the inverting input end of the differential amplifier 300.
[0035] Further, the second temperature sensor 200 is arranged in a power cabinet (not shown in the figure) in which the power electronic device 700 is located, and can be placed near the power electronic device 700 without being in contact with the power electronic device 700 to collect the ambient temperature in the power cabinet and send a second temperature signal in the form of a voltage signal to the second input end of the differential amplifier 300. Here, the second temperature sensor 200 can be arranged in other types of cabinets in which the power electronic device 700 is located, which will not be described herein. Further, the second input end of the differential amplifier 300 can be the non-inverting input end of the differential amplifier 300. Based on this, the differential amplifier 300 can output the voltage difference between the signal voltage of the second temperature signal received by the non-inverting input end and the signal voltage of the first temperature signal received by the inverting input end, and output the voltage difference in the form of a voltage signal from the output end of the differential amplifier 300, so as to represent the temperature difference between the ambient temperature and the power electronic device 700 through the voltage difference.
[0036] Further, the output end of the differential amplifier 300 is connected to the non-inverting input end of the first voltage comparator 400, and the voltage output end of the voltage source 500 is connected to the inverting input end of the first voltage comparator 400. The voltage source 500 is configured to output an output voltage with a preset voltage value to the inverting input end of the first voltage comparator 400.
[0037] Here, the preset voltage value can be the voltage value of the temperature signal in the form of a voltage signal output by the temperature sensor of the same model as the first temperature sensor 100 and the second temperature sensor 200 when the temperature sensor is located in an environment with a preset temperature value. Here, the preset temperature value is the temperature difference between the ambient temperature value and the device surface dew point temperature value under specific humidity conditions (such as a humidity environment of 90%). Here, the actual value of the preset temperature value can be determined by experiment or test according to actual conditions.
[0038] Further, an output terminal of the first voltage comparator 400 is connected with a control terminal of the heater 600, and the first voltage comparator 400 is configured to send a heating enable signal to the heater 600 when a voltage value received from the non-inverting input terminal of the first voltage comparator 400 is higher than the preset voltage value, so as to enable the heater 500 to heat the power electronic device 700. The heating enable signal can be a high level signal output by the first voltage comparator 400, and the first voltage comparator 400 outputs the high level signal by comparing the signal voltage values of the first temperature signal and the second temperature signal.
[0039] Here, the current wind turbine generator frequency conversion system has a humidity adjusting device to keep the humidity value in the power cabinet for setting the power electronic device constant. The existing humidity adjusting device maintains the relative humidity value in the power cabinet between 80% and 95% to keep the power electronic device in a suitable humidity environment.
[0040] Further, Table 1 shows a comparison table of the common ambient temperature, relative humidity and dew point temperature in the power cabinet obtained by experiments or tests.
[0041] Here, as shown in Table 1, at each common ambient temperature, the difference between the dew point temperature and the ambient temperature is less than or equal to 0.8℃, and as the humidity decreases, the difference between the dew point temperature and the ambient temperature gradually increases.
[0042]
[0043] Table 1
[0044] Based on the above table, as long as the difference between the surface temperature of the power electronic device 700 and the ambient temperature is less than 0.8℃, the surface temperature of the power electronic device 700 is higher than the dew point temperature under the common humidity in the power cabinet, and the condensation phenomenon on the surface of the power electronic device 700 can be avoided. Based on this, the preset voltage value can be the voltage value of the temperature signal in the form of the voltage signal output by the temperature sensor of the same model as the first temperature sensor 100 and the second temperature sensor 200 in the 0.8℃ environment. In addition, the numerical value of the preset voltage value can also be set according to the actual situation, which is not limited in the present application, and is also applicable to the present embodiment.
[0045] The heating control circuit provided in the embodiment of the utility model, through the first temperature sensor gathers the surface temperature of power electronic device, and through the second temperature sensor gathers the ambient temperature of the environment where the power electronic device is located, wherein, the first temperature sensor and the second temperature sensor respectively output temperature signals in the form of external voltage signals, the higher the temperature value collected by the first temperature sensor and the second temperature sensor, the higher the voltage value of the temperature signal outputted by it. Further, the first temperature signal and the second temperature signal in the form of voltage signals are received by the differential amplifier, and the voltage difference of the voltage signals corresponding to the first temperature signal and the second temperature signal respectively is determined, and the voltage difference is sent to the non-inverting input terminal of the first voltage comparator in the form of voltage. Further, the inverting input terminal of the first voltage comparator receives the output voltage of the preset voltage value, wherein, the preset voltage value can be the voltage value of the temperature signal in the form of voltage signal outputted by the temperature sensor of the same model as the first temperature sensor and the second temperature sensor in the environment of the preset temperature value. Here, the preset temperature value is the temperature difference between the ambient temperature value and the dew point temperature value of the device surface under specific humidity conditions. Further, when the voltage value at the non-inverting input terminal of the first voltage comparator is greater than the preset voltage value, the heater heats the power electronic device, so that the surface temperature of the power electronic device is higher than the dew point temperature value under the current environment, so as to effectively avoid the condensation phenomenon on the surface of the power electronic device.
[0046] In one embodiment, the heating control circuit further comprises a controller; the controller can be a computer device such as a single-chip microcomputer. Specifically, the control end of the controller is connected with the control end of the voltage source, for controlling the voltage value of the output voltage outputted by the voltage source, so that the relevant staff can adjust the output voltage value of the voltage source through the controller, so that the heating control circuit can be suitable for more humidity environments.
[0047] Further, the control end of the controller is also connected with the control end of the switching device, so as to control the switching device to be in the conducting state or the disconnected state. Further, the heating control circuit further comprises a remote communication unit; the first interaction end of the remote communication unit is connected with the interaction end of the controller, the second interaction end of the remote communication unit is connected with the host computer at the remote end, and the remote communication unit is used to establish a communication connection between the host computer and the controller. Here, the host computer can be a monitoring computer at the remote control center, so that the staff at the monitoring computer can remotely operate and control the controller. The embodiments provided in the application enable the relevant staff to remotely control the heating control circuit, thereby improving the operability of the heating control circuit.
[0048] In an optional embodiment, as Fig. 2As shown, the heating control circuit further comprises a second voltage comparator 800.
[0049] Specifically, a non-inverting input terminal of the second voltage comparator 800 is connected with an output terminal of the first temperature sensor 100 to receive the first temperature signal, and an inverting input terminal of the second voltage comparator 800 is connected with an output terminal of the second temperature sensor 200 to receive the second temperature signal.
[0050] Further, a control terminal of the heater 600 is connected with an output terminal of the second voltage comparator 800, so as to stop heating the power electronic device 700 when a heating stop signal is received from the second voltage comparator 800.
[0051] Here, when the signal voltage value of the first temperature signal received by the second voltage comparator 800 is greater than the signal voltage value of the second temperature signal, it indicates that the surface temperature of the power electronic device 700 collected by the first temperature sensor 100 is greater than the ambient temperature in the power cabinet collected by the second temperature sensor 200, at this time, the power electronic device 700 has no risk of condensation, and the heater 600 can be turned off. The embodiments provided in the present application can stop supplying power to the heater 600 when the power electronic device 700 has no risk of condensation, so that the heater 600 is in a dormant state to save energy.
[0052] In one embodiment, as shown in Fig. 3 As shown, the heater comprises a switching device 610 and a heating unit 620; here, the switching device 610 can be a relay, and the heating unit 620 can be an electric heater.
[0053] Specifically, a first terminal of the switching device 610 is connected with an external power supply E, a second terminal of the switching device 610 is connected with a power supply terminal of the heating unit 620, and a control terminal of the switching device 610 is connected with an output terminal of the first voltage comparator 400, so that the switching device 610 is in a conductive state when the heating enable signal is received from the first voltage comparator 400.
[0054] Further, the heating unit 620 is arranged at the power electronic device (not shown in the figure) to supply power to the power electronic device when power is obtained from the external power supply E. Here, the output end of the first voltage comparator 400 can be connected with the relay coil of the relay as the switching device 610, the first end of the normally open contact of the relay is connected with the external power supply E, and the second end of the normally open contact is connected with the power supply end of the heating unit 620. When the relay coil does not receive the high-level heating enable signal from the first voltage comparator 400, the normally open contact is disconnected, the heating unit 620 cannot obtain working power from the external power supply E, and it is in a stop state. In contrast, when the relay coil receives the voltage from the first voltage comparator 400, the normally open contact is turned on, the heating unit 620 can obtain working power from the external power supply E, and it is in a running state and heats the power electronic device. The technical solution provided in the application can realize the power supply control of the heating unit based on a simple control circuit to control whether the heating unit can heat the power electronic device, thereby reducing the hardware cost of the heating control circuit.
[0055] In one embodiment, the heating control circuit further comprises a condensation alarm; specifically, the power supply end of the condensation alarm is connected with the second end of the switching device, and the condensation alarm is used to send a condensation alarm when power is obtained from the external power supply. The condensation alarm can be a buzzer or a flash lamp. If the output end of the first voltage comparator sends a heating enable signal to the heater, the condensation alarm will be powered on to send a condensation alarm to prompt the relevant staff to pay attention to the possibility of condensation of the power electronic device.
[0056] On the other hand, the embodiment of the utility model provides a wind turbine generator variable frequency system, which comprises the heating control circuit as described above.
[0057] It should be noted that the internal circuit connection mode of the first temperature sensor, the second temperature sensor, the differential amplifier, the first voltage comparator, the second voltage comparator, the voltage source, the switching device, and the heating unit can be determined according to actual conditions, and the embodiment is not specifically limited. In addition, the connection mode of each device can be determined according to the specific selection of the device, and the embodiment is not specifically limited. The circuit function of the heating control circuit provided in the embodiment is mainly realized through the circuit connection relationship between each circuit module, and does not depend on the program module in a certain circuit module for realization. In addition, each circuit module in the heating control circuit can be realized through an analog circuit or a digital circuit, and for a controller that can implant a program module, the realization of the module function can be realized through the program module provided by the prior art.
[0058] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but can not therefore be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled person in the art, without departing from the utility model concept, several modifications and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.
Claims
1. A heating control circuit, characterized by, The heating control circuit comprises a first temperature sensor, a second temperature sensor, a differential amplifier, a first voltage comparator, a voltage source and a heater; The first temperature sensor is arranged on the outer surface of the power electronic device, and is configured to collect the surface temperature of the power electronic device and send a first temperature signal in the form of a voltage signal to a first input end of the differential amplifier; The second temperature sensor is arranged in a power cabinet where the power electronic device is located, and is configured to collect the ambient temperature in the power cabinet and send a second temperature signal in the form of a voltage signal to a second input end of the differential amplifier; An output end of the differential amplifier is connected to a non-inverting input end of the first voltage comparator, and a voltage output end of the voltage source is connected to an inverting input end of the first voltage comparator, so as to output an output voltage with a preset voltage value to the inverting input end; An output end of the first voltage comparator is connected to a control end of the heater, so as to send a heating enable signal to the heater when the voltage value received from the non-inverting input end is higher than the preset voltage value, so as to heat the power electronic device by the heater.
2. The heating control circuit of claim 1, wherein, The first temperature sensor is a first analog output temperature sensor, and the second temperature sensor is a second analog output temperature sensor.
3. The heating control circuit of claim 1, wherein, The heating control circuit further comprises a controller; A control end of the controller is connected to a control end of the voltage source, so as to control the voltage value of the output voltage output by the voltage source.
4. The heating control circuit of claim 1, wherein, The heating control circuit further comprises a second voltage comparator; A non-inverting input end of the second voltage comparator is connected to an output end of the first temperature sensor to receive the first temperature signal, and an inverting input end of the second voltage comparator is connected to an output end of the second temperature sensor to receive the second temperature signal; A control end of the heater is connected to an output end of the second voltage comparator, so as to stop heating the power electronic device when a heating stop signal is received from the second voltage comparator.
5. The heating control circuit of claim 3, wherein, The heater comprises a switching device and a heating unit; A first end of the switching device is connected to an external power source, a second end of the switching device is connected to a power supply end of the heating unit, and a control end of the switching device is connected to an output end of the first voltage comparator, so as to be in a conductive state when the heating enable signal is received from the first voltage comparator; The heating unit is arranged at the power electronic device, and is configured to supply power to the power electronic device when power is obtained from the external power source.
6. The heating control circuit of claim 5, wherein, The control end of the controller is further connected to the control end of the switching device, so as to control the switching device to be in a conductive state or a disconnected state.
7. The heating control circuit of claim 5, wherein, The heating control circuit further comprises a condensation alarm; A power supply end of the condensation alarm is connected to the second end of the switching device, and the condensation alarm is configured to issue a condensation alarm when power is obtained from the external power source.
8. The heating control circuit of claim 7, wherein, The condensation alarm is a buzzer or a flash lamp.
9. The heating control circuit of claim 6, wherein, The heating control circuit further comprises a remote communication unit; The first interaction end of the remote communication unit is connected with the interaction end of the controller, and the second interaction end of the remote communication unit is connected with a host computer of a remote end, and the remote communication unit is used for establishing a communication connection between the host computer and the controller.
10. A wind turbine generator variable frequency system characterized by, The wind turbine generator frequency conversion system comprises the heating control circuit according to any one of claims 1 to 9.