Phase loss circuit and steering wheel electronic power assisting system

Abstract

The embodiment of the invention provides a phase loss circuit and a steering wheel electronic power assisting system, and relates to the technical field of steering wheel electronic power assisting systems. The open-phase circuit comprises an open-phase switch tube which is connected in series between the motor and the inverter. The phase loss circuit further comprises a controller and a pre-drive circuit. The pre-drive circuit comprises a switch unit and a voltage generation unit. The open-phase switch tube and the switch unit are realized by MOS (Metal Oxide Semiconductor) tubes; when a certain MOS tube in the H bridge breaks down and is short-circuited, the effect of preventing the motor of the electronic steering engine from forming a loop is achieved by controlling the open-phase switch tube to be cut off, no mechanical contact exists, an MOS tube static switch is adopted, the service life is long, the size is small, and the cost is low. The open-phase circuit can completely adopt mature discrete semiconductor devices without depending on special suppliers, and supply and cost are completely controllable.

Description

Technical Field

[0001] The present application relates to the technical field of electronic steering wheel power-assist systems, and in particular to a phase-failure circuit. Background Art

[0002] Cars often have an Electric Power Steering (EPS) system. When the driver turns the steering wheel, the electronic power steering starts working. At this time, most of the force comes from the electronic steering gear, and the driver's hand force is relatively small.

[0003] like Figure 1 , Figure 1 A common EPS H-bridge drive working circuit is shown in the figure:

[0004] VBAT supplies power to the vehicle battery;

[0005] Vbat is the inverter power supply voltage;

[0006] J1 is the power connection connector;

[0007] Q10 is the MOSFET for reverse power protection inside the controller;

[0008] C11, C12, and C9 are filter ceramic capacitors;

[0009] C10 is a large-value electrolytic capacitor;

[0010] XL1 is the common mode filter inductor;

[0011] Q1, Q2, Q3, Q4, Q5, and Q6 are the six MOSFETs of the inverter H-bridge;

[0012] M1 is a 3-phase permanent magnet AC motor;

[0013] U, V, and W are the three phase output lines of the motor.

[0014] Since EPS is an electronic product, it is inevitable that there will be faults, such as a MOS tube in the H bridge breaking down and short-circuiting. Figure 2 , Figure 3 , Figure 2 The figure shows the upper MOS tube (Q3) breaking down and short-circuiting. Figure 3The diagram shows a short circuit caused by a breakdown of the lower MOS tube (Q4). When a short circuit occurs on the upper or lower MOS tube, if the motor and the faulty H-bridge cannot be disconnected and the hand is used to forcibly steer the vehicle, a reverse power circuit will be formed, which will drive the motor to generate electricity in the reverse direction and consume energy. When the driver uses his arm to steer the vehicle, he not only has to overcome his own mechanical steering torque, but also needs to overcome the torque generated by the reverse power supply from the motor, making it more difficult for the driver to turn the steering wheel, as if the steering wheel was "stuck", greatly increasing the risk of driving due to EPS failure.

[0015] How to design a circuit so that when a MOS tube in the H-bridge breaks down and short-circuits, the motor of the electronic steering gear is prevented from forming a loop is a technical problem to be solved by the present application. Summary of the invention

[0016] The purpose of the present application is to provide a phase-off circuit and an electronic steering wheel power-assist system to solve the technical problem in the prior art of how to design a circuit so that when a MOS tube in the H-bridge breaks down and short-circuits, the motor of the electronic steering gear does not form a loop.

[0017] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0018] In a first aspect, an embodiment of the present application provides a phase-off circuit, comprising a phase-off switch tube, wherein the phase-off switch tube is connected in series between a motor and an inverter;

[0019] The phase-break circuit also includes a controller and a pre-drive circuit;

[0020] The control end of the phase-off switch tube is connected to a pre-driving circuit;

[0021] The pre-driving circuit comprises a switch unit and a voltage generating unit; the output end of the voltage generating unit is connected to the control end of the phase-off switch tube and the first end of the switch unit, and the second end of the switch unit is connected to the reference potential point;

[0022] The controller is connected to the control end of the switch unit; the phase-off switch tube and the switch unit are implemented by MOS tubes;

[0023] When the switch unit is disconnected, the voltage provided by the voltage generating unit to the control end of the phase-off switch tube makes the phase-off switch tube conduct;

[0024] When the switch unit is turned on, the voltage generating unit is short-circuited to the reference potential point through the switch unit, and the voltage provided by the pre-driving circuit to the control end of the phase-off switch tube causes the phase-off switch tube to be turned off.

[0025] Optionally, the voltage generating unit includes a power supply circuit, a first unidirectional conduction module and a first capacitor module;

[0026] The first end of the first capacitor module is connected to the power supply of the inverter;

[0027] The power circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module;

[0028] When the power circuit has input power, the power circuit charges the first capacitor module through the first unidirectional conduction module;

[0029] The second end of the first capacitor module generates a voltage higher than the power supply of the inverter;

[0030] The second end of the first capacitor module is connected to the control end of the phase-off switch tube.

[0031] Optionally, the power supply circuit includes a bootstrap circuit;

[0032] The input end of the bootstrap circuit is connected to the power supply of the inverter;

[0033] The bootstrap circuit is used to generate a voltage higher than the power supply of the inverter;

[0034] The output end of the bootstrap circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module.

[0035] Optionally, the bootstrap circuit includes a voltage-stabilized power supply module, a second unidirectional conduction module, a comparator, and a second capacitor module;

[0036] The input end of the voltage-stabilized power supply module is connected to the power supply of the inverter;

[0037] The output end of the voltage-stabilized power supply module is connected to the first end of the second capacitor module through the second unidirectional conduction module;

[0038] The first input terminal of the comparator is connected to the PWM output terminal of the controller;

[0039] The second input terminal of the comparator is grounded;

[0040] The first power input terminal of the comparator is connected to the power supply of the inverter;

[0041] The second power input terminal of the comparator is used to receive a reference potential;

[0042] The output end of the comparator is connected to the second end of the second capacitor module; the second end of the second capacitor module is connected to the output end of the bootstrap circuit;

[0043] When the PWM signal of the controller is low, the voltage generated at the first end of the second capacitor module is the voltage at the output end of the voltage-stabilized power supply module;

[0044] When the PWM signal of the controller is high, the voltage generated at the first end of the second capacitor module is equal to the voltage of the output end of the voltage-stabilizing power supply module and the voltage of the power supply of the inverter superimposed.

[0045] Optionally, the bootstrap circuit further includes a third unidirectional conduction module and a third capacitor module;

[0046] The second end of the second capacitor module is connected to the first end of the third capacitor module through the third unidirectional conduction module;

[0047] The second end of the third capacitor module is grounded;

[0048] The first end of the third capacitor module is the output end of the bootstrap circuit.

[0049] Optionally, the phase-break circuit further includes a first voltage acquisition module;

[0050] The output end of the bootstrap circuit is connected to the first end of the first voltage acquisition module, and the second end of the first voltage acquisition module is grounded;

[0051] The controller is connected to the first voltage acquisition module to acquire the voltage at the output end of the bootstrap circuit.

[0052] Optionally, the phase failure circuit further includes a second voltage acquisition module;

[0053] The output end of the voltage-stabilized power supply module is connected to the first end of the second voltage acquisition module, and the second end of the second voltage acquisition module is grounded;

[0054] The controller is connected to the second voltage acquisition module to acquire the voltage at the output end of the voltage-stabilized power supply module;

[0055] The voltage-stabilized power supply module is a voltage stabilizer or a DCDC converter with adjustable output voltage;

[0056] The controller is connected to the control end of the voltage-stabilized power supply module.

[0057] Optionally, the phase-off circuit further includes a clamping module; the clamping module is connected between the gate and source of the phase-off switch tube.

[0058] Optionally, the clamping module is a bidirectional voltage-stabilizing Zener diode.

[0059] In a second aspect, an embodiment of the present application provides an electronic power steering system, the electronic power steering system comprising a motor and the phase-break circuit described in the first aspect.

[0060] Compared with the prior art, this application has the following beneficial effects:

[0061] The phase-off circuit provided in the embodiment of the present application can prevent the motor of the electronic steering machine from forming a loop by controlling the phase-off switch tube to be cut off when a MOS tube in the H-bridge breaks down and shorts out. It has no mechanical contacts and uses a MOS tube static switch, which has a long life, a small size and a low cost. The phase-off circuit can completely use mature semiconductor discrete devices, without relying on special suppliers, and the supply and cost are completely controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0063] Figure 1 It is a schematic diagram of the EPS H-bridge driving working circuit in the prior art;

[0064] Figure 2 for Figure 1 The schematic diagram of the circuit in which the upper MOS tube breaks down and shorts out;

[0065] Figure 3 for Figure 1 The schematic diagram of the circuit in which a MOS tube at the bottom breaks down and shorts out;

[0066] Figure 4 A schematic diagram of a phase-off circuit provided in an embodiment of the present application;

[0067] Figure 5 A schematic diagram of a voltage generating unit provided in an embodiment of the present application includes a power supply circuit, a first unidirectional conduction module and a first capacitor module;

[0068] Figure 6 A schematic diagram of a power supply circuit including a bootstrap circuit provided in an embodiment of the present application;

[0069] Figure 7 A schematic diagram of a bootstrap circuit provided in an embodiment of the present application includes a voltage-stabilizing power supply module, a second unidirectional conduction module, a comparator, and a second capacitor module;

[0070] Figure 8A schematic diagram of a lifting circuit provided in an embodiment of the present application includes a third unidirectional conduction module and a third capacitor module;

[0071] Fig. 9 For Figure 1 A schematic diagram of an implementation method of adding a phase-break circuit to the circuit shown in FIG.

[0072] Fig.10 This is a schematic diagram of the instantaneous high voltage electricity sensed during a passive emergency stop. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.

[0074] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0075] In the description of this application, it should be noted that:

[0076] Relational terms such as first and second, etc., are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations;

[0077] “Connection” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0078] In view of the failure risks described in the background technology, it is necessary to add a phase-breaking circuit in the EPS electronic control ECU circuit to solve the problem of reverse power supply to the motor and "stuck" steering wheel after H-bridge failure.

[0079] If a relay is used as a phase-off switch, this form of phase-off switch is mainly due to the large current of the steering gear, the mechanical switch contacts of the relay work at high load for a long time, and the working life is short. As the warranty period and mileage of the vehicle increase, it is not conducive to gaining a competitive advantage in the market.

[0080] like Figure 4The embodiment of the present application provides a phase-off circuit, which includes a phase-off switch tube, which is a MOS tube, and is connected in series between the motor and the inverter. When a MOS tube in the H-bridge of the inverter breaks down and short-circuits, the phase-off switch tube is controlled to be cut off, so as to avoid the motor of the electronic steering machine from forming a loop. In this way, when the driver turns the steering wheel by hand, no additional resistance is added.

[0081] like Figure 4 The phase failure circuit further includes a controller and a pre-driving circuit, the pre-driving circuit includes a switching unit and a voltage generating unit; the controller and the pre-driving circuit have the following connection relationship:

[0082] The control end of the phase-off switch tube is connected to the pre-driving circuit;

[0083] The output end of the voltage generating unit is connected to the control end of the phase-off switch tube and the first end of the switch unit, and the second end of the switch unit is connected to a reference potential point such as GND;

[0084] The controller is connected to the control end of the switch unit;

[0085] When the switch unit is disconnected, the voltage provided by the voltage generating unit to the control end of the phase-off switch tube causes the phase-off switch tube to be turned on;

[0086] When the switch unit is turned on, the voltage generating unit is short-circuited to the reference potential point through the switch unit, and the voltage provided by the pre-driving circuit to the control end of the phase-off switch tube causes the phase-off switch tube to be disconnected.

[0087] like Figure 5 The voltage generating unit may include a power supply circuit, a first unidirectional conduction module and a first capacitor module, which have the following connection relationship:

[0088] A first end of the first capacitor module is connected to a power source of the inverter;

[0089] The power supply circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module;

[0090] When the power circuit has input power, the power circuit charges the first capacitor module through the first unidirectional conduction module, and after charging, the second end of the first capacitor module generates a voltage Vbat higher than the inverter power supply;

[0091] The second end of the first capacitor module is connected to the control end of the phase-off switch tube. After charging, the voltage at the second end of the first capacitor module can turn on the phase-off switch tube.

[0092] The input voltage of the power supply circuit can be higher than the power supply voltage of the inverter; or the input voltage of the power supply circuit can be equal to the power supply voltage of the inverter, in which case the power supply circuit has a voltage boost function.

[0093] like Figure 6 , the power supply circuit may include a bootstrap circuit, which has the following connection relationship:

[0094] The input end of the bootstrap circuit is connected to the inverter power supply;

[0095] The output end of the bootstrap circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module.

[0096] The bootstrap circuit is used to generate an output voltage higher than the voltage at the input terminal of the bootstrap circuit. Therefore, when the voltage at the input terminal of the bootstrap circuit is the voltage of the inverter power supply, the output voltage of the bootstrap circuit is higher than the voltage of the inverter power supply.

[0097] like Figure 7 The bootstrap circuit may include a voltage-stabilized power supply module, a second unidirectional conduction module, a comparator, and a second capacitor module. The voltage-stabilized power supply module may be a voltage regulator or a DCDC converter with an adjustable output voltage. The connection relationship is as follows:

[0098] The input end of the voltage-stabilized power supply module is connected to the inverter power supply;

[0099] The output end of the voltage-stabilized power supply module is connected to the first end of the second capacitor module through the second unidirectional conduction module;

[0100] The first input terminal of the comparator is connected to the PWM output terminal of the controller;

[0101] The second input terminal of the comparator is grounded;

[0102] The first power input terminal of the comparator is connected to the inverter power supply;

[0103] The second power input terminal of the comparator is used to receive a reference potential;

[0104] The output end of the comparator is connected to the second end of the second capacitor module; the second end of the second capacitor module is connected to the output end of the bootstrap circuit.

[0105] When the PWM signal of the controller is low, the voltage at the output end of the comparator is the voltage at the second power input end of the comparator, that is, the reference potential, and the voltage at the first end of the second capacitor module is the voltage at the output end of the voltage-stabilized power module;

[0106] When the PWM signal of the controller is high, the voltage at the output end of the comparator is the voltage at the first input end of the comparator, and the voltage generated at the first end of the second capacitor module is equal to the voltage of the output end of the voltage-stabilizing power supply module and the voltage of the inverter power supply superimposed on each other. Therefore, the voltage generated at the first end of the second capacitor module can charge the first capacitor module, so that the voltage at the second end of the first capacitor module is higher than the voltage Vbat of the inverter power supply.

[0107] like Figure 8, the bootstrap circuit may further include a third unidirectional conduction module and a third capacitor module;

[0108] The second end of the second capacitor module is connected to the first end of the third capacitor module through the third unidirectional conduction module;

[0109] The second end of the third capacitor module is grounded;

[0110] The first end of the third capacitor module is the output end of the bootstrap circuit.

[0111] Fig. 9 Shown in Figure 1 An implementation method of adding a phase-off circuit on the basis of the circuit shown, wherein Q7, Q8, and Q9 are phase-off switch tubes, MCU is a controller, R10 resistor, C5 capacitor, and Q11 MOS tube form a switch unit, and in the voltage generating unit: D3 is a first unidirectional conduction module, C4 is a first capacitor module, D1 is a second unidirectional conduction module, C2 is a second capacitor module, D2 is a third unidirectional conduction module, C3 is a third capacitor module, U1 is a comparator, and DCDC is a voltage-stabilized power supply module (the voltage-stabilized power supply module can adopt a linear adjustable voltage power supply chip LDO, which has a cost advantage; it can also be a switch power supply circuit, such as BOOST-BUCK DCDC buck-boost switch power supply circuit, SEPIC DCDC buck-boost switch power supply circuit, which can adapt to lower input voltage). C1, C2, C3, C4, C5, C6, C7, and C8 can adopt ceramic capacitors.

[0112] The MCU can be configured with the following ports:

[0113] The Vbat_A / D terminal is the sampling interface of the DC bus voltage. Fig. 9 The resistors R11 and R12 form a second voltage acquisition module;

[0114] The D / A terminal is the voltage adjustment setting interface of the voltage-stabilized power supply module;

[0115] The PWM end is used to output the PWM wave. The core operating frequency and duty cycle of the bootstrap circuit are debugged and set here.

[0116] The Vh_A / D terminal is the voltage sampling interface of the bootstrap circuit output. Fig. 9 The resistors R8 and R9 form a first voltage acquisition module;

[0117] The I / O terminal is the gate drive switch signal of the Q11MOS tube. When the level is high, the source and drain of the Q11MOS tube are connected, and the phase-off circuit is disconnected; when the level is low, the source and drain of the Q11MOS tube are in a high-impedance state, and the phase-off circuit is connected.

[0118] Vo is the output voltage of the voltage-stabilized power supply module, Vsw is the working voltage of the capacitor in the bootstrap circuit, which is an approximate square wave composed of Vo and (Vbat+Vo), Vh is the high-voltage regulated voltage output by the bootstrap circuit, Vpg is the regulated voltage after Vh passes through the single-phase conduction of the diode, and VCC is the low voltage used for the logic circuit shared with the MCU in the ECU, which is generally 5V.

[0119] Fig. 9 The principles of the illustrated embodiment are as follows:

[0120] The voltage-stabilized power supply module can convert the 12V Vbat voltage into a regulated output Vo, for example 10V. The single-phase conduction voltage drop of the three diodes D1, D2, and D3 is not considered for the time being. The second capacitor module C2 and the comparator U1 are combined into a bootstrap circuit, and the controller outputs a PWM wave. When the comparator "+" pole PWM is at a low level, the lower end of the second capacitor module C2 is grounded, and the second capacitor module C2 is unidirectionally conducted through the second unidirectional conduction module D1 to be fully charged, and the voltage is equal to Vo; when the comparator "+" pole PWM is at a high level, the lower end of the second capacitor module C2 is connected to Vbat, the voltage of the second capacitor module C2 is raised, and the charge is discharged. At this time, Vsw=Vbat+Vo, and the third capacitor module C3 is charged through the third unidirectional conduction module D2; after the voltage of the third capacitor module C3 is stably charged, a stable Vh=Vbat+Vo can be obtained. The third capacitor module C3 continues to charge the first capacitor module C4 through the diode. The upper terminal potential of the first capacitor module C4 = Vh. Since the lower terminal of the first capacitor module C4 is connected to Vbat, the actual charge voltage stored in C4 is VC4 = Vh-Vbat = Vbat+Vo-Vbat = Vo.

[0121] When the phase-off circuit needs to be opened, the controller I / O terminal outputs a low-level signal to turn off the Q11MOS tube. At this time, the first capacitor module C4 discharges to the gate drive network of the three phase-off switch tubes (the gate drive network includes R1, C6, R2, C7, R3 and C8) through the R4 resistor, and the source of the phase-off switch tube is connected to the H-bridge arm. When the level is maximum, the upper tube of the H-bridge is turned on, and the source of the phase-off switch tube is connected to the voltage Vbat. Therefore, the minimum turn-on voltage of each phase-off switch tube is approximately Vh-Vbat=Vbat+Vo-Vbat=Vo, which is approximately the set value of 10V.

[0122] When the source of the phase-off switch tube is at the minimum level, the lower tube of the H bridge is turned on, and Vh is directly added to the gate of the phase-off switch tube. The source of the phase-off switch tube is connected to GND. At this time, the voltage is too high, and the clamping module connected in parallel to the phase-off switch tube clamps the voltage to limit the voltage. Generally, the voltage limit is 16V, which is the maximum gate drive voltage of the phase-off MOSFET. Fig. 9 , the clamping module can be a bidirectional voltage-stabilizing Zener diode.

[0123] The gate drive voltage of the phase-off switch tube is between the output voltage Vo of the voltage regulator module and 16V; the 16V upper limit voltage is designed to protect the hardware of the phase-off switch tube, and the Vo lower limit can be accurately adjusted and set through the D / A end of the controller. Considering the voltage drop of the diode itself and the fluctuation consumption of the bootstrap circuit, the controller can collect the voltage difference between the Vh_A / D end and the Vbat_A / D end, accurately calculate the tube voltage drop of the D1 and D2 diodes, and indirectly obtain the tube voltage drop of the D3 diode. Then, the actual data value collected by the Vh_A / D end is subtracted from the tube voltage drop of the D3 diode to obtain the precise minimum voltage value of the gate drive. If it is too low, the controller can adjust the output voltage of the voltage regulator module through the D / A end to increase it. If it is too high, the output voltage of the voltage regulator module can be adjusted to decrease. Among them, the Vbat_A / D end is not necessary, and the collection value inside the EPS ECU can be shared. There is no need to add a separate sampling circuit here.

[0124] The above analysis shows the process of opening and closing the phase-off switch tube. The closing process is relatively simple. When the controller I / O terminal outputs a low level, the Q11MOS tube is turned on, and the voltage of Vpg is directly pulled to GND. Regardless of the working state of the H bridge, the source level of the phase-off switch tube is ≥ GND level, and the gate drive network discharge circuit of the three phase-off switch tubes is opened, and the phase-off circuit is instantly closed; at the same time, the controller's D / A terminal can be used to set the zero voltage to shut down. This discharge process is relatively slow. Considering functional safety, it is recommended that when shutting down the phase-off circuit, the I / O terminal low level and the D / A setting to zero voltage are performed at the same time to ensure reliable and safe shutdown and avoid EPS "stuck".

[0125] This solution can achieve full control of the phase-off circuit. At the same time, from the above analysis, it can also be necessary to adjust the gate voltage of the phase-off switch tube to control the internal resistance of the phase-off switch tube after it is turned on, and indirectly adjust the temperature rise inside the ECU: at high temperatures, increase the Vo voltage and reduce the internal resistance of the phase-off switch tube to reduce the heat generation and the internal temperature of the ECU, thereby improving the thermal reliability of the ECU; at low temperatures, reduce the Vo voltage and increase the internal resistance of the phase-off switch tube to increase the heat generation and the internal temperature of the ECU, thereby increasing the electrolytic capacitor ( Fig. 9 The temperature of C10 in the circuit can be increased to reduce its internal resistance, thus ensuring the DC bus filtering effect.

[0126] When the motor is blocked passively or stopped passively, a high voltage is sensed instantaneously. Fig.10, Vbat is the DC bus voltage waveform of the H-bridge, and a part of the instantaneous high voltage induced by the motor is absorbed by the large-capacitance electrolytic capacitor of the H-bridge, forming a bus voltage increase waveform, as shown in the figure marked △V; VC4 is the voltage difference waveform across the first capacitor module C4 after the bootstrap circuit charges the first capacitor module C4. Due to the instantaneous high voltage induced by the motor, the voltage at the lower end of the first capacitor module C4 is Vbat, and the absolute voltage of the first capacitor module C4 to GND is passively floated and raised, and the voltage difference of the first capacitor module C4, due to the superposition of the delayed response of the bootstrap circuit, VC4 fluctuates slightly and is relatively stable.

[0127] The VGS in the figure is the relative waveform of the gate and source of the phase-out switch tube. Taking into account that the voltage at this location will have a Vo, 16V fluctuating waveform when the H-bridge is working, the detailed waveform is omitted, and only the relative changes in the instantaneous high voltage induced by the motor are shown. Due to the existence of the first capacitor module C4, VGS fluctuates slightly and is relatively stable, and the phase-out switch tube is normally opened and will not be turned off.

[0128] If there is no first capacitor module C4 in the figure, due to the existence of the anti-EMI capacitor at the gate of the phase-out switch tube, it stores charge itself, and one end of it is connected to the high-voltage induction current, the absolute voltage of the EMI capacitor relative to GND increases, causing the D3 diode to be reversely cut off, and the gate of the phase-out switch tube is discharged due to the gate Zener diode and gate-source leakage current. The charge stored in the second capacitor module C2 cannot be maintained, and if △V>7V, the phase-out switch tube will be mistakenly shut down.

[0129] Due to the existence of the first capacitor module C4 with a relatively large capacitance, and the reason why its lower terminal is connected to Vbat, it floats together with the DC bus voltage, and relies on the discharge of the stored charge to maintain the on state of the phase-off switch tube, pass through the transition period of △V, and successfully avoid the risk moment.

[0130] Regarding cost and supply, since the phase-off circuit is only used in EPS parts in the automotive industry, the market for dedicated driver chips for the matching phase-off 3 MOSFETs is very niche. The leading EPS component suppliers have customized their own IC solutions, such as Bosch Automotive Electronics, for their own use. There is only one American company on the market that has an independent and mature solution for this purpose, and the supply channel is single. Other foreign semiconductor suppliers have launched solutions integrated into the H-bridge pre-driver. To use this function, the EPS ECU manufacturer needs to replace the H-bridge pre-driver together. This type of solution has a long development cycle and high risk. Similar solutions for other products can be applied by domestic semiconductor manufacturers, and in theory can be used as reference, but due to comprehensive cost and layout space issues, they are not competitive. Taking into account the current semiconductor market and the current situation in China, and the possibility of being subject to the international environment at any time, the phase-off pre-driver circuit solution proposed in this case can be completely composed of mature domestic semiconductor discrete devices. Fig. 9The pre-drive circuit is composed entirely of discrete devices. All components are ordinary resistors, capacitors, diodes, small-signal MOSFETs, comparators and LDO voltage regulators. The cost is comparable to the integrated solution A6861 / A6862 of the American company Allegro, and the drive voltage has better accuracy and can be set. At the same time, it can cooperate with the ECU to complete the internal temperature control strategy under extreme ambient temperatures. The most surprising thing is that the circuit can be completely domestically produced and the supply is not affected by changes in the international environment.

[0131] At the same time, the discrete solution of this case can make up for the loss of the EPS terminal protection function, or when the vehicle turns and hits the curb, the EPS ECU is forced to shut down the phase-off circuit accidentally due to the instantaneous passive stop of the motor, and the reverse induction of high-voltage surge electricity. Since the motor current cannot change suddenly, the risk of damage to the phase-off circuit that prevents "stuck" is caused. At the same time, the circuit of this case can cope with extreme high and low temperature conditions. Without affecting the driver's feel, the ECU adjusts the direct resistance of the phase-off switch tube online to improve the working temperature of the ECU itself.

[0132] Based on the above embodiments, the embodiments of the present application further provide an electronic power steering system, which includes a motor and the above-mentioned phase-break circuit.

[0133] In summary, the advantages of this solution include:

[0134] 1. This solution provides a set of phase-off MOSFET circuit pre-drive solutions that can replace the dedicated IC solutions of foreign semiconductor manufacturers or integrated in the H-bridge pre-drive;

[0135] 2. Compared with the solutions of foreign manufacturers, this solution is more flexible and has developed new beneficial functions. For example, according to the ambient temperature, it is determined whether the heating of MOSFET needs to be improved to optimize the working temperature of the ECU itself; at the same time, it adds protection measures against passive stalling of the motor and damage to the phase-break circuit caused by excessive surge voltage;

[0136] 3. It can be fully realized by adopting domestic mature semiconductor discrete devices.

[0137] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.

[0138] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A phase-break circuit, characterized in that: It includes a phase-off switch tube, which is connected in series between the motor and the inverter; The phase-break circuit also includes a controller and a pre-drive circuit; The control end of the phase-off switch tube is connected to a pre-driving circuit; The pre-driving circuit comprises a switch unit and a voltage generating unit; the output end of the voltage generating unit is connected to the control end of the phase-off switch tube and the first end of the switch unit, and the second end of the switch unit is connected to the reference potential point; The controller is connected to the control end of the switch unit; the phase-off switch tube and the switch unit are implemented by MOS tubes; When the switch unit is disconnected, the voltage provided by the voltage generating unit to the control end of the phase-off switch tube makes the phase-off switch tube conduct; When the switch unit is turned on, the voltage generating unit is short-circuited to the reference potential point through the switch unit, and the voltage provided by the pre-driving circuit to the control end of the phase-off switch tube causes the phase-off switch tube to be turned off.

2. The phase-break circuit according to claim 1, characterized in that: The voltage generating unit includes a power supply circuit, a first unidirectional conduction module and a first capacitor module; The first end of the first capacitor module is connected to the power supply of the inverter; The power circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module; When the power circuit has input power, the power circuit charges the first capacitor module through the first unidirectional conduction module; The second end of the first capacitor module generates a voltage higher than the power supply of the inverter; The second end of the first capacitor module is connected to the control end of the phase-off switch tube.

3. The phase-break circuit according to claim 2, characterized in that: The power supply circuit includes a bootstrap circuit; The input end of the bootstrap circuit is connected to the power supply of the inverter; The bootstrap circuit is used to generate a voltage higher than the power supply of the inverter; The output end of the bootstrap circuit is connected to the second end of the first capacitor module through the first unidirectional conduction module.

4. The phase-break circuit according to claim 3, characterized in that: The bootstrap circuit includes a voltage-stabilized power supply module, a second unidirectional conduction module, a comparator and a second capacitor module; The input end of the voltage-stabilized power supply module is connected to the power supply of the inverter; The output end of the voltage-stabilized power supply module is connected to the first end of the second capacitor module through the second unidirectional conduction module; The first input terminal of the comparator is connected to the PWM output terminal of the controller; The second input terminal of the comparator is grounded; The first power input terminal of the comparator is connected to the power supply of the inverter; The second power input terminal of the comparator is used to receive a reference potential; The output end of the comparator is connected to the second end of the second capacitor module; the second end of the second capacitor module is connected to the output end of the bootstrap circuit; When the PWM signal of the controller is low, the voltage generated at the first end of the second capacitor module is the voltage at the output end of the voltage-stabilized power supply module; When the PWM signal of the controller is high, the voltage generated at the first end of the second capacitor module is equal to the voltage of the output end of the voltage-stabilizing power supply module and the voltage of the power supply of the inverter superimposed.

5. The phase-break circuit according to claim 4, characterized in that: The bootstrap circuit further includes a third unidirectional conduction module and a third capacitor module; The second end of the second capacitor module is connected to the first end of the third capacitor module through the third unidirectional conduction module; The second end of the third capacitor module is grounded; The first end of the third capacitor module is the output end of the bootstrap circuit.

6. The phase-break circuit according to claim 3, characterized in that: The phase-break circuit further includes a first voltage acquisition module; The output end of the bootstrap circuit is connected to the first end of the first voltage acquisition module, and the second end of the first voltage acquisition module is grounded; The controller is connected to the first voltage acquisition module to acquire the voltage at the output end of the bootstrap circuit.

7. The phase-break circuit according to claim 4, characterized in that: The phase-break circuit further includes a second voltage acquisition module; The output end of the voltage-stabilized power supply module is connected to the first end of the second voltage acquisition module, and the second end of the second voltage acquisition module is grounded; The controller is connected to the second voltage acquisition module to acquire the voltage at the output end of the voltage-stabilized power supply module; The voltage-stabilized power supply module is a voltage stabilizer or a DCDC converter with adjustable output voltage; The controller is connected to the control end of the voltage-stabilized power supply module.

8. The phase-break circuit according to claim 1, characterized in that: The phase-off circuit also includes a clamping module; the clamping module is connected between the gate and the source of the phase-off switch tube.

9. The phase-break circuit according to claim 8, characterized in that: The clamping module is a bidirectional voltage-stabilizing Zener diode.

10. An electronic steering wheel power assist system, characterized in that: The electronic steering wheel power-assist system comprises a motor and a phase-break circuit as described in any one of claims 1 to 9.

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