Motor controller pre-charge circuit and control method thereof

Abstract

This invention discloses a pre-charging circuit for a motor controller and its control method. The pre-charging circuit includes a pre-charging resistor R, a semiconductor switch, a Zener diode, a resistor R1, and a solid-state relay. One end of the pre-charging resistor R is connected between the switch K1 and the fuse F, and the other end of the pre-charging resistor R is connected to the collector of the semiconductor switch. The emitter of the semiconductor switch is connected between the switch K1 and the bus capacitor. One end of the resistor R1 is connected to the gate of the semiconductor switch, and the other end is connected to the P-terminal of the high-voltage battery. The cathode of the Zener diode is connected to the gate of the semiconductor switch, and the anode is connected to the emitter of the semiconductor switch. The output terminal of the solid-state relay is connected to the Zener diode, and the signal control terminal is used to connect to an external control signal generation circuit. This invention achieves control of the pre-charging circuit by controlling the conduction and cutoff of the solid-state relay to control the conduction and cutoff of the semiconductor switch.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a pre-charging circuit for a motor controller and its control method. Background Technology

[0002] With the development of new energy vehicles, the design of the motor controller has become increasingly important. Because the DC input of the motor controller typically has a bus capacitor that acts as a smoothing capacitor, the contactor K1 between the controller and the battery pack cannot be directly closed during the controller startup process. Figure 1 As shown. This is mainly because at the instant of closing the circuit, the capacitor is in a short-circuit state, resulting in a large instantaneous inrush current that can damage the battery pack, fuse, and capacitor components. Therefore, a pre-charging circuit is usually needed. This circuit first charges the capacitor to a certain value through a resistor before closing the contactor to supply power to the controller, simultaneously opening the pre-charging circuit switch. Since the pre-charging circuit involves high-voltage circuitry, isolation and safety regulations must be considered. Currently, the pre-charging circuit switch K2 is implemented using a relay / contactor.

[0003] The existing pre-charging circuit implemented using contactors / relays has the following main disadvantages:

[0004] 1) There are few suitable contactor / relay models available, or very few models that meet the requirements of vehicle systems, resulting in higher costs;

[0005] 2) Contactors / relays are usually large in size, and due to the presence of internal mechanical parts, there are certain requirements for installation. Therefore, whether they are installed on a single board or on a structural component, special consideration is needed, as they occupy a lot of space.

[0006] 3) Contactors / relays contain moving mechanical parts. On the one hand, mechanical contacts have a limited lifespan, making it difficult to meet the long lifespan requirements of vehicle systems. On the other hand, the operating environment of vehicle systems is characterized by severe vibration, increasing the risk of contactor / relay failure. Summary of the Invention

[0007] The technical problem to be solved by the embodiments of the present invention is to provide a pre-charging circuit for a motor controller and a control method thereof, so as to simplify the structure, reduce the cost and extend the service life.

[0008] To address the aforementioned technical problems, this invention proposes a pre-charging circuit for a motor controller, applied in a motor controller system. The motor controller system comprises a motor controller, a high-voltage battery, a switch K1, and a fuse F. The motor controller consists of a main control circuit and a bus capacitor connected in parallel with the main control circuit. One end of the bus capacitor is connected to the N terminal of the high-voltage battery, and the other end is connected to the switch K1. The switch K1 and the fuse F are connected to the P terminal of the high-voltage battery. The pre-charging circuit includes a pre-charging resistor R, a semiconductor switch, a Zener diode, a resistor R1, and a solid-state relay. One end of the pre-charging resistor R is connected between the switch K1 and the fuse F, and the other end is connected to the collector of the semiconductor switch. The emitter of the semiconductor switch is connected between the switch K1 and the bus capacitor. One end of the resistor R1 is connected to the gate of the semiconductor switch, and the other end is connected to the P terminal of the high-voltage battery. The cathode of the Zener diode is connected to the gate of the semiconductor switch, and the anode is connected to the emitter of the semiconductor switch. The output terminal of the solid-state relay is connected to the Zener diode, and the signal control terminal is used to connect to an external control signal generation circuit.

[0009] Furthermore, resistor R1 is composed of multiple resistors connected in series and parallel.

[0010] Furthermore, a diode is connected in parallel across the Zener diode.

[0011] Furthermore, the solid-state relay is an optically isolated / magnetically isolated / capacitively isolated solid-state relay.

[0012] Furthermore, the solid-state relay is an optocoupler relay.

[0013] Accordingly, embodiments of the present invention also provide a control method for the pre-charging circuit of a motor controller, comprising:

[0014] Pre-charge step: The solid-state relay is disconnected. The voltage difference between the high-voltage battery and the bus capacitor passes through resistor R1 and Zener diode, causing the voltage on the Zener diode to exceed the turn-on voltage of the semiconductor switch. The semiconductor switch is then turned on, thus charging the bus capacitor.

[0015] Charging stop procedure: Control the solid-state relay to conduct, so that the voltage across the high-voltage battery and the bus capacitor falls across the resistor R1, the voltage across the Zener diode approaches 0, the semiconductor switch is cut off and in the open state, and the charging of the bus capacitor ends.

[0016] The beneficial effects of this invention are as follows:

[0017] 1) This invention does not use mechanical contact devices such as contactors / relays, which can improve the reliability and service life of the entire system and has certain economic benefits;

[0018] 2) The components used in this invention are all PCB board components, which can be flexibly arranged. On the one hand, this can reduce the size and installation complexity of the equipment, and on the other hand, it can withstand higher vibration and shock, making it more suitable for automotive applications.

[0019] 3) The devices used in this invention are available in a wide variety of types, and there is no supply risk;

[0020] 4) This invention is achieved by using a resistor Zener diode and a low-cost solid-state relay with an additional small-current semiconductor switch (IGBT / MOSFET), which greatly improves the cost advantage compared to relay / contactor solutions using mechanical contacts. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of a pre-charging circuit in existing technology.

[0022] Figure 2 This is a circuit diagram of the pre-charging circuit of the motor controller according to an embodiment of the present invention.

[0023] Figure 3 This is a flowchart of the control method for the pre-charging circuit of the motor controller according to an embodiment of the present invention. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] In this embodiment of the invention, directional indicators (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0026] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0027] Please refer to Figure 2 The motor controller pre-charging circuit of this embodiment includes a pre-charging resistor R, a semiconductor switch, a Zener diode, a resistor R1, and a solid-state relay.

[0028] The motor controller pre-charge circuit can be applied to a motor controller system. The motor controller system consists of a motor controller, a high-voltage battery, a switch K1, and a fuse F. The motor controller consists of a main control circuit and a bus capacitor connected in parallel with the main control circuit. One end of the bus capacitor is connected to the N terminal of the high-voltage battery, and the other end is connected to the switch K1. The switch K1 is connected to the P terminal of the high-voltage battery through the fuse F.

[0029] Since the switch and resistor in the precharge circuit are connected, this embodiment of the invention uses a semiconductor switch (MOSFET / IGBT), a Zener diode, a resistor R1, and a solid-state relay to realize the switching of the precharge circuit. Because current solid-state relays have relatively low output voltage and load current capabilities, isolation is achieved using a solid-state relay, while voltage withstand and current carrying are achieved using an IGBT / MOSFET. Together, they fulfill the functions of a traditional contactor / relay.

[0030] The semiconductor switch is either a MOSFET or an IGBT. One end of the pre-charge resistor R is connected between switch K1 and fuse F, and the other end of the pre-charge resistor R is connected to the collector of the semiconductor switch. The emitter of the semiconductor switch is connected between switch K1 and the bus capacitor. One end of resistor R1 is connected to the gate of the semiconductor switch, and the other end is connected to the P terminal of the high-voltage battery. The cathode of the Zener diode is connected to the gate of the semiconductor switch, and the anode is connected to the emitter of the semiconductor switch. The output terminal of the solid-state relay is connected to the Zener diode, and the signal control terminal is used to connect to an external control signal generation circuit.

[0031] like Figure 2 As shown, in this embodiment of the invention, the gate drive power supply of the semiconductor switch (IGBT / MOSFET) is generated through resistor R1 and Zener diode Dz. When pre-charging is required, the control circuit controls the optocoupler relay to disconnect. Since there is no voltage across the bus capacitor, the voltage difference between the battery voltage and the bus capacitor passes through resistor R1 and Dz. By selecting an appropriate resistor and the Zener diode Dz's voltage regulation value, a voltage will be generated across Dz. As long as the voltage across Dz exceeds the IGBT / MOSFET's turn-on voltage, the IGBT / MOSFET will conduct, thus charging the bus capacitor. When charging is not required, the control circuit controls the optocoupler relay to conduct. The voltages across the battery and bus capacitor fall entirely across resistor R1, and the voltage across Dz is close to 0. The IGBT / MOSFET is cut off and in an open state, ending the charging of the bus capacitor. This embodiment of the invention achieves control over the IGBT / MOSFET's conduction and cut-off by controlling the optocoupler relay, thereby controlling the pre-charging circuit.

[0032] In one implementation, resistor R1 is composed of multiple resistors connected in series and parallel.

[0033] As one implementation method, in order to ensure the reliable turn-on and turn-off of the IGBT, a diode is connected in parallel across the Zener diode.

[0034] In one implementation, the solid-state relay is an optically isolated / magnetically isolated / capacitively isolated solid-state relay.

[0035] In one implementation, the solid-state relay is an optocoupler relay. The optocoupler relay can be any other type of isolated solid-state relay.

[0036] Please refer to Figure 3 The control method for the pre-charging circuit of the motor controller according to an embodiment of the present invention includes:

[0037] Pre-charge step: The solid-state relay is disconnected. The voltage difference between the high-voltage battery and the bus capacitor passes through resistor R1 and Zener diode, causing the voltage on the Zener diode to exceed the turn-on voltage of the semiconductor switch. The semiconductor switch is then turned on, thus charging the bus capacitor.

[0038] Charging stop procedure: Control the solid-state relay to conduct, so that the voltage across the high-voltage battery and the bus capacitor falls across the resistor R1, the voltage across the Zener diode approaches 0, the semiconductor switch is cut off and in the open state, and the charging of the bus capacitor ends.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pre-charging circuit for a motor controller, applied in a motor controller system, the motor controller system comprising a motor controller, a high-voltage battery, a switch K1, and a fuse F, the motor controller comprising a main control circuit and a bus capacitor connected in parallel with the main control circuit, one end of the bus capacitor being connected to the N terminal of the high-voltage battery, and the other end being connected to the switch K1, the switch K1 being connected to the P terminal of the high-voltage battery via the fuse F, characterized in that... The pre-charge circuit includes a pre-charge resistor R, a semiconductor switch, a Zener diode, a resistor R1, and a solid-state relay. One end of the pre-charge resistor R is connected between the switch K1 and the fuse F, and the other end of the pre-charge resistor R is connected to the collector of the semiconductor switch. The emitter of the semiconductor switch is connected between the switch K1 and the bus capacitor. One end of the resistor R1 is connected to the gate of the semiconductor switch, and the other end is connected to the P terminal of the high-voltage battery. The cathode of the Zener diode is connected to the gate of the semiconductor switch, and the anode is connected to the emitter of the semiconductor switch. The output terminal of the solid-state relay is connected to the Zener diode, and the signal control terminal is used to connect to an external control signal generation circuit.

2. The motor controller pre-charging circuit as described in claim 1, characterized in that, Resistor R1 is composed of multiple resistors connected in series and parallel.

3. The motor controller pre-charging circuit as described in claim 1, characterized in that, A diode is also connected in parallel across the Zener diode.

4. The motor controller pre-charging circuit as described in claim 1, characterized in that, The solid-state relay is an optically isolated / magnetically isolated / capacitively isolated solid-state relay.

5. The motor controller pre-charging circuit as described in claim 4, characterized in that, The solid-state relay is an optocoupler relay.

6. A control method for the pre-charge circuit of a motor controller as described in any one of claims 1-5, characterized in that, include: Pre-charge step: The solid-state relay is disconnected. The voltage difference between the high-voltage battery and the bus capacitor passes through resistor R1 and Zener diode, causing the voltage on the Zener diode to exceed the turn-on voltage of the semiconductor switch. The semiconductor switch is then turned on, thus charging the bus capacitor. Charging stop procedure: Control the solid-state relay to conduct, so that the voltage across the high-voltage battery and the bus capacitor falls across the resistor R1, the voltage across the Zener diode approaches 0, the semiconductor switch is cut off and in the open state, and the charging of the bus capacitor ends.

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