A frequency converter keyboard circuit

Abstract

The utility model discloses a frequency converter keyboard circuit, including voltage stabilizing circuit, power supply circuit, voltage reducing circuit and voltage drop compensation circuit, and the input of power supply circuit is electrically connected with extension line or frequency converter control panel, and the output of voltage stabilizing circuit is electrically connected with the load element device of keyboard body, and power supply circuit, voltage reducing circuit and voltage stabilizing circuit are connected in series, and voltage drop compensation circuit is connected in parallel with voltage reducing circuit. The utility model discloses through voltage reducing compensation circuit to the detection of power supply circuit, and judge whether the power supply voltage received by power supply circuit is greater than the set threshold value. If the power supply voltage is greater than the set threshold value, then first through voltage reducing circuit reduces voltage and then exports to voltage stabilizing circuit, prevents the voltage of too high and damages the voltage stabilizing chip of voltage stabilizing circuit. If the power supply voltage is less than the set threshold value, then through voltage reducing compensation circuit short circuit voltage reducing circuit and directly connects voltage stabilizing circuit. Relative to design, greatly breaks through the restriction of prior art, makes the external lead keyboard can be led to the position of farther.

Description

Technical Field

[0001] This utility model relates to the field of frequency converter technology, and in particular to a frequency converter keyboard circuit. Background Technology

[0002] In some applications of frequency converters, an external keyboard can be connected via an extension cable to meet the needs of remote device parameter debugging and operation control. However, traditional solutions have significant limitations on the length of the external keyboard extension cable: as the cable length increases, its equivalent resistance increases significantly, resulting in a non-negligible voltage drop across the extension cable. When the voltage at the input end of the extension cable connected to the frequency converter control board interface is constant, an excessive voltage drop will cause the voltage at the output end of the extension cable connected to the keyboard interface to drop too much, causing the core keyboard circuit to malfunction due to excessive attenuation of the supply voltage.

[0003] Figure 1 This is a common inverter keyboard circuit. Normally, the keyboard interface is directly connected to the inverter control board interface, which provides a stable +5V power supply. When an external keyboard is needed, an extension cable connects the keyboard interface to the inverter control board interface. In this circuit, the +5V voltage is filtered by capacitors C1 and C2 and then connected to input pin 3 of voltage regulator chip U1. GND is connected to common pin 1 of voltage regulator chip U1. Output pin 2 of voltage regulator chip U1 is filtered by capacitors C3 and C4 and outputs a stable +3.3V voltage to power subsequent circuits. When the extension cable for the external keyboard is too long (e.g., a 0.5mm² copper extension cable exceeding 15 meters), the actual input voltage to voltage regulator chip U1 will be lower than the minimum input voltage required by the chip. This will prevent voltage regulator chip U1 from outputting a stable +3.3V voltage, affecting the normal operation of subsequent circuits. Utility Model Content

[0004] The main purpose of this utility model is to propose a frequency converter keyboard circuit, which aims to solve the technical problem that the existing solution has a large limitation on the length of the external keyboard extension cable, and the voltage drop caused by the extension cable length will cause the core keyboard circuit to fail to work properly due to excessive attenuation of the power supply voltage.

[0005] To achieve the above objectives, the present invention proposes a frequency converter keyboard circuit, including a voltage regulator circuit; it also includes a power supply circuit, a step-down circuit, and a voltage drop compensation circuit. The input terminal of the power supply circuit is electrically connected to an extension line or the frequency converter control board, and the output terminal of the voltage regulator circuit is electrically connected to the load components of the keyboard body. The power supply circuit, the step-down circuit, and the voltage regulator circuit are connected in series, and the voltage drop compensation circuit is connected in parallel with the step-down circuit.

[0006] Optionally, the step-down circuit uses a resistor R1, one end of which is electrically connected to the power supply circuit and the other end is electrically connected to the input terminal of the voltage regulator circuit.

[0007] Optionally, the voltage drop compensation circuit includes a voltage detection comparator and a voltage detection switch circuit connected in series.

[0008] Optionally, the voltage detection comparator includes a first voltage divider circuit, a first filter circuit, and a voltage comparator connected in series.

[0009] Optionally, the voltage comparator uses the TL431 chip U2.

[0010] Optionally, the first voltage divider circuit includes resistors R6 and R10.

[0011] Optionally, the first voltage divider circuit includes a resistor R8 and a capacitor C8.

[0012] Optionally, the voltage detection switch circuit includes a second voltage divider circuit, a second filter circuit, a PNP transistor Q1, and an NPN transistor Q2 connected in series.

[0013] Optionally, the second voltage divider circuit includes resistors R5 and R9.

[0014] Optionally, the second voltage divider circuit includes a resistor R7 and capacitors C6 and C7.

[0015] The technical solution of this utility model has the following beneficial effects:

[0016] When the keyboard interface is directly connected to the inverter control board interface, or when the extension cable length is less than a certain value, the power supply voltage received by the power supply circuit will exceed the set threshold. In this case, the voltage is first reduced by a step-down circuit before being output to the voltage regulator circuit. This prevents excessive voltage from damaging the voltage regulator chip U1 AMS1117-3.3 in the voltage regulator circuit, ensuring the safety of the power supply voltage over short distances. When the extension cable length is greater than a certain value, the step-down compensation circuit short-circuits the step-down circuit and directly connects it to the voltage regulator circuit to ensure stable power supply voltage over long distances. Compared to existing designs with a maximum allowable voltage drop of only 1.5V (5V→3.5V) and a maximum allowable cable resistance of only 30Ω, this design has a maximum allowable voltage drop of 11.5V (15V→3.5V) and a maximum allowable cable resistance of 230Ω. With the same wire gauge (0.5mm² copper wire), the maximum length of the extension cable has increased from 15 meters to 115 meters, greatly breaking through the limitations of existing technology and allowing the external keyboard to be extended to a more distant location to meet further usage needs. At the same time, without changing the circuit parameters, this design can also accommodate applications that do not require an external keyboard, allowing the keyboard interface to be directly connected to the inverter control board interface, making it convenient for users. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 The circuit schematic of the keyboard circuit for an existing frequency converter design;

[0019] Figure 2 This is a circuit diagram of a frequency converter keyboard circuit according to the present invention.

[0020] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0023] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0024] This utility model proposes a keyboard circuit for a frequency converter.

[0025] like Figures 1 to 2As shown in Embodiment 1 of this utility model, the inverter keyboard circuit includes a voltage regulator circuit, a power supply circuit, a step-down circuit, and a voltage drop compensation circuit. The input terminal of the power supply circuit is electrically connected to the extension cable or the inverter control board, and the output terminal of the voltage regulator circuit is electrically connected to the load components of the keyboard body. The power supply circuit, the step-down circuit, and the voltage regulator circuit are connected in series, and the voltage drop compensation circuit is connected in parallel with the step-down circuit. Specifically, the power supply circuit uses GND as the voltage zero point and outputs an initial voltage of +15V from the inverter control board interface to the extension cable or the power supply circuit (i.e., the keyboard interface).

[0026] This invention uses a step-down compensation circuit to detect the power supply circuit and determine whether the received power supply voltage exceeds a set threshold. If the power supply voltage exceeds the threshold, it is first reduced by the step-down circuit before being output to the voltage regulator circuit. This prevents excessively high voltage from damaging the voltage regulator chip U1 AMS1117-3.3. Finally, the voltage regulator circuit processes the voltage and provides a stable 3.3V power supply to the load components of the keyboard. If the power supply voltage is less than the threshold, the step-down compensation circuit short-circuits the step-down circuit and directly connects it to the voltage regulator circuit. The voltage regulator circuit then processes the voltage and provides a stable 3.3V power supply to the load components of the keyboard.

[0027] When the keyboard interface is directly connected to the inverter control board interface, or when the extension cable length is less than a certain value, the power supply voltage received by the power supply circuit will exceed the set threshold. In this case, the voltage is first reduced by a step-down circuit before being output to the voltage regulator circuit. This prevents excessive voltage from damaging the voltage regulator chip U1 AMS1117-3.3 in the voltage regulator circuit, ensuring the safety of the power supply voltage over short distances. When the extension cable length is greater than a certain value, the step-down compensation circuit short-circuits the step-down circuit and directly connects it to the voltage regulator circuit to ensure stable power supply voltage over long distances. Compared to existing designs with a maximum allowable voltage drop of only 1.5V (5V→3.5V) and a maximum allowable cable resistance of only 30Ω, this design has a maximum allowable voltage drop of 11.5V (15V→3.5V) and a maximum allowable cable resistance of 230Ω. With the same wire gauge (0.5mm² copper wire), the maximum length of the extension cable has increased from 15 meters to 115 meters, greatly breaking through the limitations of existing technology and allowing the external keyboard to be extended to a more distant location to meet further usage needs. At the same time, without changing the circuit parameters, this design can also accommodate applications that do not require an external keyboard, allowing the keyboard interface to be directly connected to the inverter control board interface, making it convenient for users.

[0028] like Figure 2As shown, the power supply circuit uses GND as the voltage zero point. Its input terminal is electrically connected to the inverter's control board interface or extension line, and its output terminal is electrically connected to the input terminals of the buck circuit and voltage drop compensation circuit. The buck circuit specifically uses resistor R1. One end of resistor R1 is electrically connected to the output terminal of the power supply circuit, and the other end is electrically connected to the input pin 3 of the voltage regulator circuit. The voltage regulator circuit consists of capacitors C1 and C2 for input filtering, a voltage regulator chip U1, and capacitors C3 and C4 for output filtering. Capacitors C1 and C2 are connected in parallel, with one common terminal connected to the common pin 1 of the voltage regulator chip U1, and the other common terminal connected to the input pin 3 of the voltage regulator chip U1. The common pin 1 of the voltage regulator chip U1 is connected to GND. Capacitors C3 and C4 are connected in parallel, with one common terminal connected to the output pin 2 of the voltage regulator chip U1, and the other common terminal connected to the common pin 1 of the voltage regulator chip U1. The function of the voltage regulator circuit is to stabilize the voltage input to the step-down circuit or voltage drop compensation circuit to a fixed output voltage (3.3V) to provide power to the load components of the keyboard.

[0029] In this embodiment, the voltage drop compensation circuit includes a voltage detection comparator and a voltage detection switch circuit connected in series. The voltage detection comparator is used to detect the magnitude of the supply voltage received by the power supply circuit and determine whether the supply voltage is greater than a set threshold. The voltage detection switch circuit is used to short-circuit the step-down circuit and directly connect it to the voltage regulator circuit based on the detection result (i.e., when the supply voltage is greater than the set threshold). Specifically, the voltage detection comparator includes a first voltage divider circuit, a first filter circuit, and a voltage comparator connected in series. The voltage comparator uses a TL431 chip U2. The first voltage divider circuit includes resistors R6 and R10, and resistors R8 and C8. Further, the voltage detection switch circuit includes a second voltage divider circuit, a second filter circuit, a PNP transistor Q1, and an NPN transistor Q2 connected in series. The second voltage divider circuit includes resistors R5 and R9, and resistors R7, C6, and C7.

[0030] During operation, the power supply voltage received by the power supply circuit is divided and filtered by the first voltage divider circuit and the first filter circuit, and then input to the TL431 chip U2 through input pin 2. The TL431 chip U2 detects the magnitude of the power supply voltage received by the power supply circuit and determines whether the voltage exceeds a set threshold. When the extension line length exceeds a certain value, a voltage drop occurs across the equivalent resistance of the extension line, causing the power supply voltage received by the power supply circuit to fall below the set threshold. At this time, the voltage received by the TL431 chip U2 is lower than the internal reference voltage of the TL431 chip U2, causing the voltage at output pin 1 of the TL431 chip U2 to change from low to high. The voltage output from output pin 1 is then divided and filtered by the second voltage divider circuit and the second filter circuit, causing the NPN transistor Q2 to change from the cutoff state to the conduction state. When the NPN transistor Q2 changes from cutoff to conduction, the PNP transistor Q1 also changes from cutoff to conduction, thus short-circuiting resistor R1 to directly connect to the voltage regulator circuit, ensuring stable power supply voltage over long distances.

[0031] like Figure 2 As shown, the voltage drop compensation circuit also includes resistors R2, R3, and R4. PNP transistor Q1 is connected in parallel with resistor R1 used in the step-down circuit. One end of resistor R2 is connected to the emitter of PNP transistor Q1, and the other end is connected to the base of PNP transistor Q1. One end of resistor R4 is connected to the base of PNP transistor Q1, and the other end is connected to the collector of NPN transistor Q2. The emitter of NPN transistor Q2 is connected to GND. One end of resistor R7 is connected to the base of NPN transistor Q2, and the other end is connected to the common point of resistors R5 and R9. The other end of resistor R9 is connected to GND. The other end of resistor R5 is connected to one end of resistor R3, and the other end of resistor R3 is connected to the output terminal of the power supply circuit. The common point of resistors R3 and R5 is connected to output pin 1 of TL431 chip U2. The common pin 3 of TL431 chip U2 is connected to GND. Input pin 2 of TL431 chip U2 is connected to one end of resistor R8. The other end of resistor R8 is connected to the common point of resistors R6 and R10. The other end of resistor R10 is connected to GND. The other end of resistor R6 is connected to the output terminal of the power supply circuit. One end of capacitor C5 is connected to the output terminal of the power supply circuit, and the other end is connected to GND. One end of capacitor C8 is connected to input pin 2 of TL431 chip U2, and the other end is connected to common pin 3 of TL431 chip U2. Capacitors C6 and C7 are connected in parallel. One common terminal of C6 and C7 is connected to the base of NPN transistor Q2, and the other common terminal is connected to the emitter of NPN transistor Q2.

[0032] In other embodiments, a dedicated voltage monitoring IC, solid-state relay, or similar device can be used instead of a voltage drop compensation circuit to achieve the same effect. This means detecting and determining whether the supply voltage is greater than a set threshold, and short-circuiting the step-down circuit to directly connect to the voltage regulator circuit when the supply voltage is less than the set threshold, thus ensuring stable supply voltage over long distances.

[0033] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A frequency converter keypad circuit, comprising a voltage regulator circuit; characterized in that, It also includes a power supply circuit, a step-down circuit, and a voltage drop compensation circuit. The input terminal of the power supply circuit is electrically connected to an extension line or a frequency converter control board, and the output terminal of the voltage regulator circuit is electrically connected to the load components of the keyboard body. The power supply circuit, the step-down circuit, and the voltage regulator circuit are connected in series, and the voltage drop compensation circuit is connected in parallel with the step-down circuit.

2. The inverter keyboard circuit according to claim 1, characterized in that, The step-down circuit uses resistor R1, one end of which is electrically connected to the power supply circuit, and the other end is electrically connected to the input terminal of the voltage regulator circuit.

3. The inverter keyboard circuit according to claim 1, characterized in that, The voltage drop compensation circuit includes a voltage detection comparator and a voltage detection switch circuit connected in series.

4. The inverter keyboard circuit according to claim 3, characterized in that, The voltage detection comparator includes a first voltage divider circuit, a first filter circuit, and a voltage comparator connected in series.

5. The inverter keyboard circuit according to claim 4, characterized in that, The voltage comparator uses the TL431 chip U2.

6. The inverter keyboard circuit according to claim 4, characterized in that, The first voltage divider circuit includes resistor R6 and resistor R10.

7. The inverter keyboard circuit according to claim 4, characterized in that, The first voltage divider circuit includes a resistor R8 and a capacitor C8.

8. The inverter keyboard circuit according to claim 3, characterized in that, The voltage detection switch circuit includes a second voltage divider circuit, a second filter circuit, a PNP transistor Q1, and an NPN transistor Q2 connected in series.

9. The inverter keyboard circuit according to claim 8, characterized in that, The second voltage divider circuit includes resistors R5 and R9.

10. The inverter keyboard circuit according to claim 8, characterized in that, The second voltage divider circuit includes resistor R7 and capacitors C6 and C7.

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