Gear control circuit for air heater of electric automobile

Abstract

The utility model provides an electric automobile wind heater gear control circuit which comprises a low-voltage power supply, a high-voltage power supply, a plurality of PTC (Positive Temperature Coefficient) heating elements, a plurality of relays, a fuse and a temperature controller, normally open contacts of the relays are respectively connected in series in power supply loops of the corresponding PTC heating elements, and the power supply loops of the PTC heaters are connected between the positive electrode and the negative electrode of the high-voltage power supply; the fuse is connected in series between a high-voltage power supply positive electrode and a contact of the relay, the temperature controller is connected in series between a positive polarity end of a relay coil and a low-voltage power supply input end, and the high-voltage battery can supply power to the PTC heater with low cost. The control circuit further comprises a plurality of diodes, a plurality of capacitors and a plurality of TVS tubes. According to the control circuit, multi-gear control can be achieved through the multiple relays, PTC heating is achieved with low cost, and besides, the control circuit further comprises the fuse protector to achieve over-current protection and the temperature controller to achieve over-temperature protection.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle PTC heating, in particular to a gear control circuit of an electric vehicle air heater. Background Art

[0002] In electric vehicles, PTC heaters are commonly used to heat the interior air and enhance comfort. To precisely control heating power, a gear control circuit is required. This circuit can select different heating power gears based on user needs, thereby precisely adjusting the interior temperature. This gear control technology allows PTC heaters to adapt more flexibly to different operating environments, meeting both rapid temperature rise requirements and energy-saving operation after reaching the target temperature. Furthermore, through the integration of an intelligent control system, gear switching can be automatically controlled, enhancing the heater's ease of use and intelligence. Utility Model Content

[0003] The purpose of this utility model is to provide a gear control circuit for an electric vehicle air heater, which can heat the PTC through a high-voltage battery at a low cost, and then send hot air through a fan to warm the driver. The specific technical solution is as follows:

[0004] A gear control circuit for an electric vehicle air heater includes a low-voltage power supply interface, multiple PTC heating elements, multiple relays, and a high-voltage power supply interface. The coil side of the relay is connected in series between the positive and negative poles of the low-voltage power supply interface, and the contact side of the relay is connected in series with the corresponding PTC heating element and then connected to the high-voltage power supply interface. Multi-gear control of PTC heating can be achieved by controlling the multiple PTC heating elements through the multiple relays.

[0005] Furthermore, the low-voltage power supply interface includes a low-voltage input end, a first low-voltage output end and a second low-voltage output end, and the multiple relays include a first relay and a second relay, one end of the coil side of the first relay is connected to the low-voltage input end, and the other end is connected to the first low-voltage output end, and one end of the coil side of the second relay is connected to the low-voltage input end, and the other end is connected to the second low-voltage output end.

[0006] Furthermore, the multiple PTC heating elements include a first PTC heating element and a second PTC heating element, the first PTC heating element is connected to the positive pole of the high-voltage power supply end via the contact side of the first relay, and the other end is connected to the negative pole of the high-voltage power supply end; one end of the second PTC heating element is connected to the positive pole of the high-voltage power supply end via the contact side of the second relay, and the other end is connected to the negative pole of the high-voltage power supply end.

[0007] Furthermore, the contact sides of the first relay and the second relay are both single-pole single-throw switches, the static contacts of the single-pole single-throw switches are connected to the positive HV+ of the high-voltage power supply interface, and the moving contacts of the single-pole single-throw switches are respectively connected to the first PTC heating element and the second PTC heating element.

[0008] Furthermore, the two ends of the first relay coil are connected in parallel to a first capacitor and a first freewheeling diode, and the two ends of the second relay coil are connected in parallel to a second capacitor and a second freewheeling diode.

[0009] Furthermore, a diode is connected in series between the positive polarity end of the first relay coil side, the positive polarity end of the second relay coil side, and the low voltage input end.

[0010] Furthermore, it also includes a first TVS tube and a second TVS tube, one end of the first TVS tube is connected to the low-voltage input end, and the other end is connected to the first low-voltage output end, and one end of the second TVS tube is connected to the low-voltage input end, and the other end is connected to the second low-voltage output end.

[0011] Furthermore, it also includes a thermostat, which is connected in series between the low-voltage input end and the positive polarity end of the first relay coil and the positive polarity end of the second relay coil.

[0012] Furthermore, it also includes a fuse, which is connected in series between the positive HV+ of the high-voltage power supply interface and the static contacts of the first relay and the second relay.

[0013] Furthermore, the relay can be equivalently replaced by a switch with equivalent functions.

[0014] The utility model provides an electric vehicle air heater gear control circuit, which has the following beneficial effects:

[0015] The utility model provides an electric vehicle air heater gear control circuit, which can use multi-channel relays to achieve multi-speed control and realize PTC heating at low cost. In addition, it also includes a fuse to achieve overcurrent protection and a thermostat to achieve overtemperature protection. The control circuit also has anti-interference and anti-surge functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is a schematic diagram of a gear control circuit of an electric vehicle air heater provided by the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the accompanying drawings provided by the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. According to the following description, the advantages and features of the present invention will become more apparent. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0018] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connection" and "connected" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] In the description of the present invention, the terms "up", "down", "left", "right", "front", "back", "center", "horizontal", "vertical", "top", "bottom", "inside", "outside" and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0020] Example

[0021] This embodiment provides a gear control circuit for an electric vehicle air heater. Figure 1 As shown, the circuit includes a low-voltage power supply interface, a first relay K1, a second relay K2, a first heating element PTC1, a second heating element PTC2, and a high-voltage power supply interface. The coil side of the first relay K1 and the coil side of the second relay K2 are both connected to the low-voltage power supply interface, while the contact side of the first relay K1 and the contact side of the second relay K2 are connected in series to the high-voltage power supply circuits of the first heating element PTC1 and the second heating element PTC2, respectively. This control circuit uses multiple relays to achieve multi-speed control of PTC heating. This control circuit is described in detail below.

[0022] In a specific implementation, the low-voltage power supply interface includes a low-voltage input terminal (i.e., Pin 5 of the low-voltage connector), a first low-voltage voltage output terminal (i.e., Pin 4 of the low-voltage connector), and a second low-voltage voltage output terminal (i.e., Pin 3 of the low-voltage connector). The high-voltage power supply interface includes a high-voltage positive electrode HV+ and a high-voltage negative electrode HV-. The contact side of the first relay K1 is connected in series with the power supply circuit of the first heating element PTC1. One end of the coil side of the first relay K1 is connected to the low-voltage input terminal, and the other end is connected to the first low-voltage output terminal. The contact side of the second relay K2 is connected in series with the power supply circuit of the second heating element PTC2. One end of the coil side of the second relay K2 is connected to the low-voltage input terminal, and the other end is connected to the second low-voltage voltage output terminal. One end of the first heating element PTC1 is connected to the positive HV+ of the high-voltage power supply interface via the contact side of the first relay K1, and the other end is connected to the negative HV- of the high-voltage power supply interface; one end of the second heating element PTC2 is connected to the positive HV+ of the high-voltage power supply interface via the contact side of the second relay K2, and the other end is connected to the negative HV- of the high-voltage power supply interface.

[0023] Optionally, the switches of the first relay K1 and the second relay K2 are both single-pole single-throw switches, whose static contacts are connected to the positive HV+ of the high-voltage power supply interface, and whose moving contacts are respectively connected to the first heating element PTC1 and the second heating element PTC2.

[0024] Optionally, a diode D1 is connected in series between the positive polarity end of the first relay K1 coil and the positive polarity end of the second relay K2 coil and the low voltage input end to prevent the positive and negative poles of the low voltage power supply from being reversed.

[0025] Optionally, a freewheeling diode D2 and a capacitor C1 are connected in parallel at both ends of the coil of the first relay K1, and a freewheeling diode D3 and a capacitor C2 are connected in parallel at both ends of the coil of the second relay K2. The cathode of the freewheeling diode D2 is connected to the first low-voltage output terminal, and the cathode of the freewheeling diode D3 is connected to the second low-voltage output terminal. The freewheeling diodes are used to absorb the reverse electromotive force generated when the relay switches from being closed to being opened.

[0026] Optionally, the first relay K1 and the second relay K2 can be equivalently replaced by switches with equivalent functions such as contactors.

[0027] Optionally, the control circuit further includes a first TVS diode 1 and a second TVS diode 2. One end of the first TVS diode 1 is connected to the low-voltage input terminal and the other end is connected to the first low-voltage output terminal. One end of the second TVS diode 2 is connected to the low-voltage input terminal and the other end is connected to the second low-voltage output terminal. The first TVS diode 1 and the second TVS diode 2 are used to absorb surges, prevent static electricity, provide overvoltage protection, and protect against ESD.

[0028] In another specific implementation process, the control circuit also includes a temperature controller Temp, which is used to collect the temperature of the heating core of the first heating element PTC1 and the second heating element PTC2. The temperature controller is connected in series between the low-voltage input end and the positive polarity end of the coil of the first relay K1 and the positive polarity end of the coil of the second relay K2, that is, the temperature controller is connected in series in the power supply circuit of the first relay K1 and the power supply circuit of the second relay K2. When the temperature collected by the thermostat exceeds the set value, the power supply circuit of the first relay K1 and the power supply circuit of the second relay K2 will be cut off, and the first heating element PTC1 and the second heating element PTC2 will stop working to prevent damage caused by overheating.

[0029] In another specific implementation, the control circuit further includes a fuse U1 for protecting against circuit overload and short circuit. Fuse U1 is connected in series between the positive terminal HV+ of the high-voltage power supply interface and the static contacts on the coil side of the first and second relays. When the current in the operating circuit of the heating element exceeds the rated current of the fuse, the fuse generates heat, causing the wire to melt, thereby severing the circuit.

[0030] The operating principle of the electric vehicle air heater gear control circuit is as follows: the circuit's low-voltage supply voltage is 12V, and the high-voltage supply voltage is 200V-456V, with four gears, 0 to 3. In gear 0, both the first relay K1 and the second relay K2 are disconnected, and neither the first heating element PTC1 nor the second heating element PTC2 is heated. In gear 1, the first relay K1 is closed, the second relay K2 is disconnected, and the first heating element PTC1 zone (three heating elements) is heated. In gear 2, the second relay K2 is closed, the first relay K1 is disconnected, and the second heating element PTC2 zone (five heating elements) is heated. In gear 3, both the first relay K1 and the second relay K2 are closed, and the first heating element PTC1 zone (eight heating elements) is heated. The circuit also has overtemperature protection: it stops when the core temperature exceeds a set temperature (e.g., 110°C) and resumes operation when it is less than or equal to the set temperature (e.g., 75°C). Furthermore, the circuit has anti-interference and surge protection features.

[0031] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

Claims

1. A gear control circuit for an electric vehicle air heater, characterized in that: It includes a low-voltage power supply interface, multiple PTC heating elements, multiple relays and a high-voltage power supply interface. The coil side of the relay is respectively connected in series between the positive and negative poles of the low-voltage power supply interface, and the contact side of the relay is connected in series with the corresponding PTC heating element and then connected to the high-voltage power supply interface respectively. The multiple relays control the multiple PTC heating elements to achieve multi-speed control of PTC heating.

2. The electric vehicle air heater gear control circuit according to claim 1, characterized in that: The low-voltage power supply interface includes a low-voltage input end, a first low-voltage output end and a second low-voltage output end. The multiple relays include a first relay and a second relay. One end of the coil side of the first relay is connected to the low-voltage input end, and the other end is connected to the first low-voltage output end. One end of the coil side of the second relay is connected to the low-voltage input end, and the other end is connected to the second low-voltage output end.

3. The electric vehicle air heater gear control circuit according to claim 2, characterized in that: The multiple PTC heating elements include a first PTC heating element and a second PTC heating element, the first PTC heating element is connected to the positive pole of the high-voltage power supply end via the contact side of the first relay, and the other end is connected to the negative pole of the high-voltage power supply end; one end of the second PTC heating element is connected to the positive pole of the high-voltage power supply end via the contact side of the second relay, and the other end is connected to the negative pole of the high-voltage power supply end.

4. The electric vehicle air heater gear control circuit according to claim 3, characterized in that: The contact sides of the first relay and the second relay are both single-pole single-throw switches, the static contacts of the single-pole single-throw switches are connected to the positive HV+ of the high-voltage power supply interface, and the moving contacts of the single-pole single-throw switches are respectively connected to the first PTC heating element and the second PTC heating element.

5. The electric vehicle air heater gear control circuit according to claim 2, characterized in that: The two ends of the first relay coil are connected in parallel to a first capacitor and a first freewheeling diode, and the two ends of the second relay coil are connected in parallel to a second capacitor and a second freewheeling diode.

6. The electric vehicle air heater gear control circuit according to claim 5, characterized in that: A diode is connected in series between the positive polarity end of the first relay coil side, the positive polarity end of the second relay coil side, and the low voltage input end.

7. The electric vehicle air heater gear control circuit according to claim 6, characterized in that: It also includes a first TVS tube and a second TVS tube, one end of the first TVS tube is connected to the low-voltage input end, and the other end is connected to the first low-voltage output end, and one end of the second TVS tube is connected to the low-voltage input end, and the other end is connected to the second low-voltage output end.

8. The electric vehicle air heater gear control circuit according to any one of claims 2 to 7, characterized in that: A thermostat is also included, and the thermostat is connected in series between the low voltage input terminal and the positive polarity end of the first relay coil and the positive polarity end of the second relay coil.

9. The electric vehicle air heater gear control circuit according to claim 4, characterized in that: A fuse is also included, and the fuse is connected in series between the positive HV+ of the high-voltage power supply interface and the static contacts of the first relay and the second relay.

10. The electric vehicle air heater gear control circuit according to any one of claims 1 to 7, characterized in that: The relay can be equivalently replaced by a switch with equivalent functions.

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