CN104802649B - A kind of controller of current vortex retarder - Google Patents

Abstract

The invention discloses a controller for an eddy current retarder. The controller includes a single-chip microcomputer, a signal input module connected to the single-chip microcomputer, an indicator light, a CAN communication interface, a driving circuit and a current sampling circuit, wherein the IGBT module of the driving circuit passes through The AND gate circuit U3 is connected to the single-chip microcomputer, and the current sampling circuit includes a sampling resistor R3, a retarder coil group L, an overcurrent protection circuit U4, a sampling signal conditioning circuit U5, and the like. The invention has simple structure and reliable performance. By collecting information such as engine speed, throttle opening, vehicle speed and temperature, etc., it can judge the current vehicle load status and braking demand, etc., adjust the output duty ratio of the IGBT module by itself, and reduce the speed of the retarder. The current of the coil can automatically reduce the output braking force, realize automatic load adjustment control, and ensure driving safety.

Description

A kind of eddy current retarder controller

technical field

The invention relates to the technical field of automobile control, in particular to an eddy current retarder controller.

Background technique

At present, the eddy current retarder is generally used in the braking of large vehicles to improve the braking force of the vehicle during driving. The eddy current retarder system is divided into two parts, the control circuit and the actuator. The actuator is a set of excitation The mechanical assembly composed of the coil and the corresponding mechanical structure, the control circuit generates a corresponding braking force on the rotating shaft (drive shaft) of the actuator by passing current to the excitation coil of the actuator, and brakes the vehicle. The traditional eddy current retarder controller generally adopts the step-by-step control method, as shown in Figure 1, according to the change of the control switch (hand brake or foot brake signal), multiple sets of excitation coils L1, L2, L3, L4 connects or disconnects the power in batches to adjust the driving braking force; the switch tube generally adopts the BTS550 power device of Infineon Company. The current change rate of the over-power device is large, which is not conducive to the long-term use of the power drive device. After the power device is powered on for a long time, the internal working temperature of the controller will increase, which will affect the service life of the product, and it cannot be adjusted according to the load change during use. The braking force of the eddy current retarder is adjusted, and the effect is poor when the vehicle is light-loaded or no-loaded, which reduces the stability of the driving brake.

The name of the patent is: Eddy Current Retarder Braking Torque Control Method and Drive Controller [Patent No.: ZL201010146019.9] mentions that the vehicle speed signal and rotor temperature signal are collected in real time by the microprocessor. When the temperature is normal, the microprocessor The controller outputs a PWM control signal with a fixed duty cycle according to the current gear position, and implements open-loop control on the braking torque of the eddy current retarder; when the temperature exceeds the limit, the microprocessor implements closed-loop control to control the rotor temperature at the threshold temperature Nearby, in this method, the temperature limit is used as the open-loop or closed-loop control limit, and PWM control is added to the step-by-step control, and after multi-level step-by-step + PWM control, the braking torque generated by it is small, and the system is affected by the temperature. The impact is relatively large. When the vehicle is heavily loaded, the electric brake cannot be intervened in advance, which will cause insufficient braking force and poor braking effect.

Using a similar control scheme, the patent name is: combined braking system eddy current retarder controller and control method [patent number: ZL201010590330.2] mentioned that the controller, after the brake pedal is stepped on, according to the PWM control signal, Calculate the real-time braking force of the vehicle based on the position of the pedal and the speed of the vehicle, then calculate the slope of the vehicle, and then look up the table to obtain the braking force ratio, and apply a PWM control signal with a corresponding duty cycle to the retarder electromagnetic coil to achieve auxiliary braking . The program calculates the real-time braking force of the car after inputting relevant signals, and then applies the braking force to the braking system. Traffic conditions (mountain road, high speed, rain, snow), car load status (no load, heavy load) and other factors are related, because the braking force required by the car during acceleration or braking on flat roads, climbing, and downhill Each is different, and the actual application effect of this scheme will be significantly affected by the output braking effect due to the deviation of parameter calculation.

Contents of the invention

In order to overcome the above disadvantages, the present invention provides an eddy current retarder controller with simple structure, reliable performance, and the ability to automatically change the output braking force according to the load state of the vehicle.

The technical scheme of the present invention is as follows: a kind of eddy current retarder controller, comprises single-chip microcomputer and is connected to the signal input module (1) of single-chip microcomputer (1), indicator light (2), CAN communication interface (3), driving circuit (4) and The current sampling circuit (5) is characterized in that: the drive circuit (4) includes an AND gate circuit U3 and an IGBT module, and the AND gate circuit U3 is connected to a single-chip microcomputer; the current sampling circuit (5) includes a sampling resistor R3, The retarder coil group L, the overcurrent protection circuit U4 and the sampling signal conditioning circuit U5; the retarder coil group L is connected with the IGBT module output end of the drive circuit (4); the retarder coil group L also It is connected with the sampling resistor R3 and the overcurrent protection circuit U4; the overcurrent protection circuit U4 is connected with the sampling signal conditioning circuit U5, and is connected with the single-chip microcomputer respectively;

The signal input module (1) includes a braking voltage sampling circuit (11), a braking switch (12), a speed sensor (13) and a temperature sensor (14), and the braking voltage sampling circuit (11) is connected to the braking The pedals are connected, the brake switch (12) is connected with the brake air pressure circuit, and the speed sensor (13) and the temperature sensor (14) are connected with the retarder coil group L respectively;

When the driver depresses the brake pedal, the brake air circuit of the vehicle is connected, and as the air pressure gradually increases, S1 and S2 in the brake switch (12) are connected successively, and the signals are collected by the single-chip microcomputer, and the vehicle During the driving process, the retarder rotor on the transmission shaft rotates at high speed, and the speed sensor installed on the retarder coil group L senses the change of the retarder rotor, generates a vehicle speed pulse signal, which is collected by the single-chip microcomputer; when the vehicle is working, The engine ECU will transmit the current engine speed and throttle opening information to the CAN bus, and the information will be received by the single-chip microcomputer through the CAN communication interface. In the current load state, the engine speed under the rated load condition will produce a corresponding vehicle speed signal output, and its throttle opening will also change accordingly. When it is large or has obvious changes, it indicates that the vehicle is in a heavy-load state, otherwise it is in a light-load state. After the single-chip microcomputer collects the brake voltage signal and brake switch signal, it will adopt the corresponding control slope curve according to the currently recognized load state. .

Preferably, the retarder coil group L is composed of four groups of retarder coils (L1, L2, L3, L4) connected in parallel, one end of the retarder coil group L is connected to the output end of the IGBT module, and the other end Connect to the non-ground end of the sampling resistor R3.

Preferably, the overcurrent protection circuit U4 includes a voltage comparator, one input terminal (31) of the AND gate circuit U3 is connected to the control output terminal of the microcontroller, and the other input terminal (32) of the AND gate circuit U3 is connected to the voltage comparator connected to the output.

Preferably, the indicator light is displayed by a light column or a light bar.

Beneficial effects of the present invention: By collecting information such as engine speed, throttle opening, vehicle speed and temperature, judging the current vehicle load status and braking demand, etc., self-adjusting the output duty ratio of the IGBT module, so that the flow through the retarder The current of the coil changes to generate different braking forces to realize driving braking; when the temperature of the retarder is detected to be too high, the controller automatically reduces the output braking force to improve the reliability of vehicle braking and ensure driving safety.

Description of drawings

Fig. 1 is a schematic diagram of classification control in the prior art solution.

Fig. 2 is a schematic diagram of the structural composition in the technical solution.

FIG. 3 is a schematic diagram of the circuit structure in the technical solution.

Figure 4 shows different control slope curves.

Figure 5 shows the output duty cycle.

In the drawings: 1. Signal input module; 2. Indicator lights; 3. CAN communication interface; 4. Drive circuit; 5. Current sampling circuit; 11. Braking switch; 12. Braking voltage sampling circuit; 13. Speed sensor ; 14. Temperature sensor;

U3, AND gate circuit; U4, overcurrent protection circuit; U5, current sampling circuit; D, bidirectional voltage suppressor

R2, resistance; R3, sampling resistance; L1-L4 retarder coil; L retarder coil group;

31-32, the input end of the AND gate circuit U3; 33 the output end of the AND gate circuit U3

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figures 2 and 3, an eddy current retarder controller includes a single-chip microcomputer and a signal input module 1 connected to the single-chip microcomputer, an indicator light 2, a CAN communication interface 3, a driving circuit 4 and a current sampling circuit 5.

Wherein signal input module 1 comprises: brake voltage sampling circuit 11, brake switch 12, speed sensor 13 and temperature sensor 14, described brake voltage sampling circuit 11 is connected with brake pedal, and described brake switch 12 is connected with brake pedal. The air pressure circuit is connected, and the speed sensor 13 and the temperature sensor 14 are respectively connected with the stator coil of the retarder; the indicator light 2 is a light column or a light bar display, and the variation range of its lighting corresponds to the output duty ratio of the PWM wave; CAN One end of the communication interface 3 realizes interactive signal connection with the single-chip microcomputer, and the other end is connected with the body engine CAN network; the drive circuit 4 includes the AND gate circuit U3 and Q3 of the IGBT module, the AND gate circuit U3 is connected with the single-chip microcomputer, and the AND gate circuit U3 outputs The terminal 33 is connected to the gate of the IGBT module Q3 through the driving transistor Q1, Q2 and the driving resistor R1, the resistor R2 is connected in parallel with the bidirectional voltage suppressor D, and then connected in series with R1 to form the gate input protection circuit of the IGBT module, the output terminal of the IGBT module It is connected with the retarder coil group L, and the retarder coil group L is connected with the sampling resistor R3, the overcurrent protection circuit U4, and the sampling signal conditioning circuit U5. The retarder coil group L is composed of 4 groups of retarder coils (L1, L2, L3, L4) connected in parallel, one end of the retarder coil group L is connected to the output end of the IGBT module, and the other end is connected to the sampling resistor R3 connected to the non-ground terminal; current sampling circuit 5 includes sampling resistor R3, retarder coil group L, overcurrent protection circuit U4 and sampling signal conditioning circuit U5; described overcurrent protection circuit U4 and AND gate circuit U3, current sampling circuit U5 is connected, and is connected with the one-chip computer respectively.

As shown in Figure 3, the brake voltage signal is the signal output by the brake pedal of the vehicle. When the driver depresses the brake pedal, there is a corresponding voltage change with the depressing angle of the pedal. The voltage variation range is 0-5V, and the effective identification range is 0.5-4.5V, and the voltage is sampled by the braking voltage sampling circuit 11 connected to the single-chip microcomputer;

When the driver depresses the brake pedal, the brake air circuit of the vehicle is connected. With the gradual increase of the air pressure, S1 and S2 in the air brake switch 12 are connected successively. The signals are collected by the single-chip microcomputer at the same time. During driving, the rotor of the retarder on the transmission shaft rotates at high speed, and the speed sensor installed on the stator coil of the retarder senses the change of the rotor of the transmission shaft, generates a vehicle speed pulse signal, which is collected by the single-chip microcomputer. When the vehicle is working, the engine ECU will transmit the current engine speed, throttle opening and other information to the CAN bus, and the information will be received by the single-chip microcomputer through the CAN communication interface, and the single-chip microcomputer will comprehensively analyze the current throttle opening (throttle value) According to the relationship between the engine speed and the vehicle speed, the current load state of the vehicle can be judged. The engine speed under the rated load condition will generate a corresponding vehicle speed signal output, and the throttle opening (accelerator pedal value) will also change accordingly. At a vehicle speed, when the throttle opening is larger or has obvious changes compared with the rated operating condition, it indicates that the vehicle is in a heavy load state, otherwise it is a light load state. After the single-chip microcomputer collects the brake voltage signal and the brake switch signal, it will adopt the corresponding control slope curve according to the currently recognized load state.

As shown in Figure 4, the curve B in the figure is the control curve of the normal load state. In this figure, the vertical axis is the output value of the brake pedal. The PWM controller does not output. In order to achieve better control, the dead zone voltage is identified as about 0.9V. Only when the brake pedal is pressed to a certain height and the pedal output voltage is greater than 0.9V, the controller will use the brake signal , switch signal, vehicle speed signal, etc. to make corresponding output, the maximum effective value of the brake pedal is 4.5V, the horizontal axis is the output duty ratio (braking force) under the braking voltage, the maximum value is 100%, about It is 1800～2300N/M. As shown in Figure 5, under normal load conditions, when the voltage of the brake pedal is about 1.5V when the vehicle is moving, the controller outputs about 25% of the PWM wave, which is equivalent to obtaining a quarter of the braking force. When the pedal voltage is about 4.5V, the controller outputs 100% PWM wave, which is equivalent to the maximum braking force output. Curve C in Figure 4 is the control curve under heavy load conditions. It can be seen from this curve that when the brake pedal voltage is about 3V during heavy load driving, the controller has already output 100% PWM wave, so that the electric Braking intervenes in advance to achieve a good braking effect by light braking. Curve A in the figure is the control curve under light load conditions. It can be seen from this curve that when the brake pedal voltage reaches At the maximum value, the controller outputs about 75% of the PWM wave, so that the electric brake intervenes with a lag, ensuring that the braking force output is relatively low when the vehicle is lightly loaded.

In Fig. 3, the PWM driving circuit is composed of AND gate circuit U3, driving transistors Q1, Q2, driving resistor R1, resistor R2, and bidirectional voltage suppressor D, in which the driving resistor R1, resistor R2, and bidirectional voltage suppressor D are IGBT modules The input protection circuit of Q3 prevents misoperation or IGBT module Q3 damage caused by drive circuit control failure or interference, etc. The PWM wave output by the microcontroller is loaded to the IGBT module through the AND gate circuit U3, drive transistors Q1, Q2, and drive resistor R1 The gate of Q3 makes Q3 work in the switching state, and the 4 groups of coils of the retarder are connected in parallel to the output ports of the IGBT module. A magnetic field is induced and a force (braking torque) is formed. The magnitude of the force is determined by the output duty cycle of the IGBT module; as shown in Figure 5, the figure shows PWM waveforms with different duty cycles. The control waveform is used to control the switching state of the IGBT module. When the output PWM duty cycle is 100%, the IGBT module is equivalent to fully outputting the 4 groups of coils of the retarder. When the output is 50% duty cycle, it is equivalent to The retarder has 4 sets of coils for half output. When the IGBT module is working, the change of the duty ratio of the PWM wave will be displayed in the form of the indicator signal at the same time. The indicator circuit is composed of a series of luminous columns or strips, and the change range of its lighting is the same as the output of the PWM wave. The duty cycle is corresponding. When the retarder is working, the single-chip microcomputer outputs the control signal to light up the corresponding light column or light bar to display the current output state of the retarder. When the IGBT module is fully output, the light bar or light bar is all lit. Bright. When the PWM output stops, the light bars are all off. The sampling signal conditioning circuit U5 in Figure 3 is composed of a voltage follower. When a voltage is generated on R3, the voltage is amplified by 1:1 and sent to the voltage sampling input terminal of the microcontroller. The overcurrent protection circuit U4 is composed of a voltage When a voltage signal is generated on R3, the voltage is sent to the inverting input terminal of the comparator. The non-inverting input terminal of the comparator is a fixed voltage source Vref. By adjusting the comparison voltage Vref at the non-inverting input terminal of U4, The protection current value can be set, that is, the maximum current flowing through the retarder coil can be adjusted. R3 in Figure 3 is the current sampling resistor. When a current flows through the retarder coil and the sampling resistor R3, a current is generated on the sampling resistor R3 A voltage, the voltage is sent to the ADC sampling input port of the CPU through the sampling signal conditioning circuit U5, and the sampling current is monitored in real time. The voltage is also sent to the overcurrent protection circuit U4 for comparison. When the current rises due to some reasons , so that the sampling voltage rises, and the voltage of the negative input terminal of the voltage comparator U4 rises. When the voltage exceeds the value of the voltage Vref of the non-inverting input terminal of the comparator, the comparator U4 outputs a low level, and the level signal is sent to the The input terminal 2 of the AND gate U3 and the signal acquisition port of the single-chip microcomputer, the output of the AND gate circuit U3 is turned off, the PWM signal has no output, and the IGBT module Q3 stops working to prevent the IGBT module from being damaged due to over-current. At the same time, the single-chip microcomputer detects the over-current The signal will be processed accordingly.

During the running of the vehicle, when the temperature of the retarder rises due to continuous braking or other reasons, the single-chip microcomputer detects the temperature signal, and when the temperature rises to the set value, the system enters the power reduction output mode. The current vehicle speed, load status, retarder temperature and other parameters automatically reduce the output PWM duty cycle to make the output current lower, ensuring that the eddy current retarder works within a safe and reasonable range.

Although the specific embodiments of the present invention have been described and illustrated in detail above, it should be pointed out that we can make various equivalent changes and modifications to the above-mentioned embodiments according to the concept of the present invention, and the functional effects produced by it are still the same. Anything beyond the spirit covered by the accompanying drawings shall fall within the protection scope of the present invention.

Claims (4)

1. An eddy current retarder controller, including a single-chip microcomputer and a signal input module (1), an indicator light (2), a CAN communication interface (3), a drive circuit (4) and a current sampling circuit (5) connected to the single-chip microcomputer ), characterized in that: the drive circuit (4) includes an AND gate circuit U3 and an IGBT module, and the AND gate circuit U3 is connected to a single-chip microcomputer; the current sampling circuit (5) includes a sampling resistor R3, a retarder coil group L, overcurrent protection circuit U4 and sampling signal conditioning circuit U5; the retarder coil group L is connected to the output end of the IGBT module of the drive circuit (4); the retarder coil group L is also connected to the sampling resistor R3 and The overcurrent protection circuit U4 is connected; the overcurrent protection circuit U4 is connected with the sampling signal conditioning circuit U5, and is respectively connected with the single-chip microcomputer; the signal input module (1) includes a braking voltage sampling circuit (11), a braking switch (12), speed sensor (13) and temperature sensor (14), the brake voltage sampling circuit (11) is connected to the brake pedal, the brake switch (12) is connected to the brake air pressure circuit, the The speed sensor (13) and temperature sensor (14) are respectively connected with the retarder coil group L; when the driver steps on the brake pedal, the brake air circuit of the vehicle is connected, and as the air pressure gradually increases, the brake S1 and S2 in the switch (12) are turned on successively, and the signal is collected by the single-chip microcomputer. During the running of the vehicle, the rotor of the retarder on the transmission shaft rotates at high speed, and the speed sensor installed on the coil group L of the retarder senses The change of the rotor of the retarder generates a vehicle speed pulse signal, which is collected by the single-chip microcomputer; when the vehicle is working, the engine ECU will transmit the current engine speed and throttle opening information to the CAN bus, and the information is transmitted by the single-chip microcomputer through the CAN communication interface. After reception, the single-chip microcomputer comprehensively analyzes the relationship between the engine speed and the vehicle speed under each throttle opening at present, and judges the current load state of the vehicle. The engine speed under the rated load condition will generate a corresponding vehicle speed signal output, and the throttle opening will also have a Corresponding changes, when the throttle opening at a certain speed is larger than that under the rated load condition or there is a significant change, it indicates that the vehicle is in a heavy load state, otherwise it is in a light load state, and the single chip microcomputer collects the braking voltage signal After the brake switch signal is activated, the corresponding control slope curve will be adopted according to the currently recognized load state. 2. The eddy current retarder controller according to claim 1, characterized in that: the retarder coil group L is composed of four sets of retarder coils (L1, L2, L3, L4) connected in parallel, the One end of the retarder coil group L is connected to the output end of the IGBT module, and the other end is connected to the non-ground end of the sampling resistor R3. 3. The eddy current retarder controller according to claim 1, characterized in that: the overcurrent protection circuit U4 comprises a voltage comparator, an input terminal (31) of the AND gate circuit U3 and a control output terminal of the single-chip microcomputer The other input terminal (32) of the AND gate circuit U3 is connected with the output terminal of the voltage comparator. 4. The eddy current retarder controller according to claim 1, characterized in that: the indicator light is displayed by a light column or a light bar.