A motor controller cover opening protection device

Abstract

The present disclosure relates to a kind of motor controller uncovering protection device, the motor controller uncovering protection device includes the boss being arranged in the upper shell cover plate bottom side of motor controller and the copper area being arranged on the control board PCB of motor controller;When the upper shell cover plate is normally installed, the lower surface of the boss is tightly attached to the surface of control board PCB, and form flat plate capacitor between the boss and the copper area.The present disclosure detects whether uncovering action occurs by detecting the capacitance between the control board of motor controller and shell, because no physical switch or device is used, with high reliability, save the number of components, circuit is simple, easy to assemble The advantage.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of new energy automobile motor controller, and particularly relates to a motor controller cover opening protection device. BACKGROUND

[0002] The voltage platform of a new energy automobile is usually a 300V platform. With the application of power semiconductors such as sic, the voltage platform of an electric vehicle is also increased to 800V. Therefore, high-voltage safety cannot be ignored. There is a high-voltage inverter device in the motor controller. In the case that the upper cover plate is not installed in place or when the staff is overhauling, the high-voltage system may be exposed to the range that can be touched by personnel at this time, which may endanger personal safety. Generally, the motor controller has a cover opening protection function. When the upper cover plate is opened, the software reports a fault and does not allow high-voltage power-on, etc. The widely used cover opening protection method is to install a micro switch in the controller. In the normal state, the upper cover plate presses the micro switch, and the micro switch is in the on state. The microprocessor detects this level signal to determine whether the upper cover plate is installed in place. When the upper cover plate is opened, the micro switch is released, and the microprocessor detects the level change to determine that the upper cover plate is opened. This scheme needs to use a micro switch. In the automobile use environment, vibration and high temperature are often encountered. The micro switch may fail due to vibration or oxidation of the spring piece, resulting in failure. Therefore, the reliability of the micro switch scheme is low.

[0003] Therefore, it is necessary to provide a new motor controller cover opening protection device to solve the above technical problems. SUMMARY

[0004] The purpose of the present disclosure is to provide a motor controller cover opening protection device to solve the above problems.

[0005] The present disclosure achieves the above-mentioned purpose by the following technical solutions:

[0006] A motor controller cover opening protection device, comprising a boss arranged at the bottom side of an upper housing cover plate of a motor controller and a copper-clad area arranged on a control board PCB of the motor controller; when the upper housing cover plate is normally installed, the lower surface of the boss is in close contact with the surface of the control board PCB, and a plate capacitor is formed between the boss and the copper-clad area.

[0007] As a further optimization scheme of the present disclosure, the copper-clad area is arranged in the second layer in the inner layer of the control board PCB.

[0008] As a further optimization scheme of the present disclosure, a cover opening protection circuit is further included, and the cover opening protection circuit comprises a microprocessor μC, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a plate capacitor C1 and a comparator U1.

[0009] The microprocessor μC is connected with one end of the first resistor R1, the other end of the first resistor R1 is connected with one end of the plate capacitor C1 and the negative input end of the comparator U1; the other end of the plate capacitor C1 is connected with one end of the third resistor R3 and the ground pin of the comparator U1; the other end of the third resistor R3 is connected with one end of the second resistor R2 and the positive input end of the comparator U1; the other end of the second resistor R2 is connected with the power input end of the comparator U1 and one end of the fourth resistor R4; the other end of the fourth resistor R4 is connected with the output end of the comparator U1 and the microprocessor μC.

[0010] As a further optimization scheme of the present disclosure, the plate capacitor formed between the boss and the copper-clad area is the plate capacitor C1 in the cover opening protection circuit.

[0011] As a further optimization scheme of the present disclosure, the microprocessor μC transmits a PWM signal to the plate capacitor C1 through the first resistor R1; the second resistor R2 and the third resistor R3 constitute a voltage divider circuit to provide a threshold voltage to the same input end of the comparator U1.

[0012] As a further optimization scheme of the present disclosure, the comparator U1 flips the level by comparing the charged peak voltage with the set threshold voltage, and the microprocessor μC judges whether the cover opening action occurs by detecting the state of the level signal.

[0013] As a further optimization scheme of the present disclosure, when the upper shell cover plate is normally installed, the comparator U1 outputs a high level; after the upper shell cover plate is opened, the comparator U1 outputs a level-flipped PWM signal.

[0014] As a further optimization scheme of the present disclosure, the size of the plate capacitor is inversely proportional to the distance between the lower surface of the boss and the surface of the control board PCB, and is proportional to the area of the copper-clad area.

[0015] The present disclosure has the following beneficial effects:

[0016] The present disclosure detects whether the cover opening action occurs by detecting the capacitance between the motor controller control board and the shell, and has the advantages of high reliability, saving the number of components, simple circuit and easy assembly because no physical switch or device is used. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of the present disclosure;

[0018] Figure 2 is a schematic diagram of the copper-clad area on the control board PCB of the present disclosure;

[0019] Figure 3 is a circuit diagram of the open cover protection circuit in the embodiment of the present disclosure;

[0020] Figure 4 is a waveform diagram when the cover plate is attached in the embodiment of the present disclosure;

[0021] Figure 5 is a waveform when the cover plate is opened in the embodiment of the present disclosure;

[0022] Figure 6 is a PCB layer structure diagram in the embodiment of the present disclosure.

[0023] In the figure: 1, motor controller; 2, upper shell cover plate; 3, boss; 4, control board PCB; 5, copper-clad area. DETAILED DESCRIPTION

[0024] The following further describes the present application in conjunction with the drawings, and it is necessary to point out here that the following detailed description is only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0025] As shown in Figure 1 , an open cover protection device for a motor controller includes a boss 3 arranged on the bottom side of the upper shell cover plate 2 of the motor controller 1 and a copper-clad area 5 arranged on the control board PCB 4 of the motor controller; when the upper shell cover plate is normally installed, the lower surface of the boss 3 is tightly attached to the surface of the control board PCB 4, and a flat plate capacitor is formed between the boss 3 and the copper-clad area 5.

[0026] A flat plate capacitor is formed between the boss 3 and the control board PCB. The size of this capacitor is inversely proportional to the distance between the two surfaces.

[0027] Figure 2 is a control board PCB, and a copper-clad area 5 is designed on the inner layer (2nd layer) of the PCB, and the size of the flat plate capacitor formed between the boss 3 and the PCB is proportional to the area of the copper-clad area 5.

[0028] Figure 3 is an open cover protection circuit, which includes a microprocessor μC, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a flat plate capacitor C1 and a comparator U1;

[0029] The microprocessor μC is connected with one end of the first resistor R1, the other end of the first resistor R1 is connected with one end of the flat plate capacitor C1 and the negative input end of the comparator U1; the other end of the flat plate capacitor C1 is connected with one end of the third resistor R3 and the ground pin of the comparator U1; the other end of the third resistor R3 is connected with one end of the second resistor R2 and the positive input end of the comparator U1; the other end of the second resistor R2 is connected with the power input end of the comparator U1 and one end of the fourth resistor R4; the other end of the fourth resistor R4 is connected with the output end of the comparator U1 and the microprocessor μC.

[0030] The microprocessor μC sends a PWM signal to the flat plate capacitor C1 through the first resistor R1. R2 and R3 form a voltage divider circuit to provide a threshold voltage to the same input end of the comparator U1.

[0031] Figure 4 、 Figure 5 The waveforms shown in different flat plate capacitors change the RC (RC circuit, full name resistance-capacitance circuit) charging time constant, which ultimately affects the steady-state charging peak voltage. The comparator U1 flips the level by comparing the charging peak voltage with the set threshold voltage, and the μC judges whether the cover opening action occurs by detecting the state of this level signal.

[0032] Figure 4 It is shown that the comparator U1 outputs a high level when the cover is normally installed.

[0033] Figure 5 It is shown that the comparator U1 outputs a level-flipped PWM signal after the cover is opened.

[0034] In this embodiment, it specifically includes:

[0035] For a common 4-layer PCB layer structure, it can be as shown in Figure 6 .

[0036] A copper area with a length of 40mm and a width of 40mm is arranged in the L2 layer. It can be seen that the distance from the second layer to the top layer is about 0.33mm. The commonly used material of the PCB board is glass fiber, and its relative dielectric constant can be taken as 4.1. According to the following formula, it can be calculated that:

[0037]

[0038] The size of the flat plate capacitor composed of the 40mm×40mm copper area of the second layer and the boss on the surface is about:

[0039]

[0040] The calculated result of the capacity of the flat plate capacitor is Figure 3 C1 in the above formula; further, the μC sends a 10k frequency and 50% duty cycle PWM signal, R1 can be set to 1 meg, R3 and R4 can be set to 10k, and R2 can be set to 5.1k; VCC is the supply voltage of the μC, which is generally 5V. Therefore, the voltage at the non-inverting input of the comparator U1 can be calculated as:

[0041]

[0042] Ignoring the bias current at the inverting input of U1, the peak-to-peak value of the charge and discharge of the charging and discharging circuit composed of R1 and C1 can be calculated.

[0043] Assuming that the peak voltage caused by the capacitor charging is VP, and the minimum voltage caused by the capacitor discharging is VN;

[0044] When the μC outputs a high level PWM, the charging process of the capacitor C1 can be calculated as:

[0045]

[0046] When the μC outputs a low level PWM, the discharging process of the capacitor C1 can be calculated as:

[0047]

[0048] According to the stable state of the charging and discharging, the voltage at the end of the charging is equal to the voltage at the beginning of the discharging, and the voltage at the end of the discharging is equal to the voltage at the beginning of the charging, which can be obtained as:

[0049]

[0050] In this case, since the peak voltage VP of the voltage fluctuation caused by the charging and discharging of the flat plate capacitor is less than the threshold voltage VINP of the non-inverting input of the comparator, the output of the comparator is high, and the μC detects that the output of U1 is high, which can be considered as the correct installation of the cover plate.

[0051] In another case, the upper cover plate is opened, and since the distance between the flat plate capacitors becomes larger, the capacitance becomes very small at this time, and the charging network composed of 1 meg and the smaller capacitor can be quickly filled, thereby causing the voltage at the inverting input of the comparator to be greater than the voltage at the non-inverting input. In this case, the voltage of the comparator will be flipped from high to low, and the μC detects this change, which can be considered as the cover plate of the controller being opened.

[0052] In actual application, the threshold voltage of the comparator can be adjusted to a suitable value according to the actual size of the flat plate capacitor, so as to avoid false alarms.

[0053] Structurally: the upper shell cover plate of the motor controller is designed to have a boss which is attached to the surface of the control board PCB in normal state; a copper-coated area of the same size as the boss is set in the 2nd layer of the PCB at the position corresponding to the boss. The boss and the copper-coated area constitute a plate capacitor, and the size of the capacitor can be detected to determine whether the cover opening action has occurred.

[0054] Circuit: the PWM signal sent by the μC charges the plate capacitor through the resistance, and the voltage change caused by the charging and discharging of the capacitor; if the upper cover plate is closed, the plate capacitor capacity is relatively large at this time, and the voltage change caused by the charging and discharging of the capacitor through the resistance during the high level period of the PWM sent by the μC is less than the flip threshold voltage of the comparator, so the output of the comparator remains fixed at high level; when the cover is opened, the plate capacitor capacity becomes very small due to the increase of the distance between the two poles, in this case, the PWM of the μC is sufficient to charge the voltage on the capacitor to the flip threshold voltage of the comparator during the high level period, so the comparator will output a jump from high to low level, and the μC can detect the jump to determine whether the cover opening action has occurred, and take corresponding protection measures to protect personal safety.

[0055] The above-described embodiments only express several embodiments of the present disclosure, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, which are within the protection scope of the present disclosure.

Claims

1. An electric machine controller open cover protection device, characterized by, The application relates to a motor controller (1) which comprises a boss (3) arranged on the bottom side of an upper housing cover plate (2) of the motor controller (1) and a copper-clad area (5) arranged on a control board PCB (4) of the motor controller (1); when the upper housing cover plate (2) is normally installed, the lower surface of the boss (3) is tightly attached to the surface of the control board PCB (4), and a flat plate capacitor is formed between the boss (3) and the copper-clad area (5). The copper-clad area (5) is arranged in the second layer of the inner layer of the control board PCB (4). The application further relates to an open cover protection circuit which comprises a microprocessor (muC), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a flat plate capacitor (C1) and a comparator (U1); one end of the microprocessor (muC) is connected with one end of the first resistor (R1), the other end of the first resistor (R1) is connected with one end of the flat plate capacitor (C1) and the negative input end of the comparator (U1); the other end of the flat plate capacitor (C1) is connected with one end of the third resistor (R3) and the ground pin of the comparator (U1); the other end of the third resistor (R3) is connected with one end of the second resistor (R2) and the positive input end of the comparator (U1); the other end of the second resistor (R2) is connected with the power input end of the comparator (U1) and one end of the fourth resistor (R4); the other end of the fourth resistor (R4) is connected with the output end of the comparator (U1) and the microprocessor (muC). The flat plate capacitor formed between the boss (3) and the copper-clad area (5) is the flat plate capacitor (C1) in the open cover protection circuit.

2. An open cover protection device for a motor controller according to claim 1, wherein The microprocessor (muC) transmits a PWM signal to the flat plate capacitor (C1) through the first resistor (R1); the second resistor (R2) and the third resistor (R3) constitute a voltage dividing circuit to provide a threshold voltage to the same direction input end of the comparator (U1).

3. A motor controller cover protection device according to claim 2, wherein The comparator (U1) flips the level by comparing the charged peak voltage with the set threshold voltage, and the microprocessor (muC) judges whether the open cover action occurs by detecting the state of the level signal.

4. A motor controller cover protection device as claimed in claim 3, wherein, When the upper housing cover plate (2) is normally installed, the comparator (U1) outputs a high level; after the upper housing cover plate (2) is opened, the comparator (U1) outputs a level-flipped PWM signal.

5. The motor controller cover protection device of claim 1, wherein, The size of the flat plate capacitor is inversely proportional to the distance between the lower surface of the boss (3) and the surface of the control board PCB (4) and is proportional to the area of the copper-clad area (5).

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