TWI901977B - Circuit protection system and circuit protection method - Google Patents

Abstract

A circuit protection system and a circuit protection method are provided. The circuit protection system includes a switch unit, a current comparison unit and a pulse-width modulation (PWM) signal generation unit. The switch unit is connected between a battery output terminal of a battery module and a load input terminal of a load device, and has a first control terminal. The current comparison unit is configured to detect a battery current at the battery output terminal, and determine whether or not a current value of the battery current exceeds a predetermined current value. When the current value exceeds the predetermined current value, the current comparison unit outputs an overflow signal to stop outputting a PWM signal, such that the switch unit remains in an open-circuit state. Otherwise, the current comparison unit outputs non-overflow signal to continuously output the PWM signal, such that the switch unit is turned on or off according to a duty cycle.

Description

Circuit protection systems and methods

This invention relates to a protection system and a protection method, and more particularly to a circuit protection system and a circuit protection method.

When a power supply is connected to a device, a surge current is generated in the input capacitor of the connected drive unit. Taking an electric motorcycle as an example, when a battery is installed in an electric vehicle, different magnitudes of surge current will be generated depending on the load of the electric vehicle connected to the battery; or, each time the vehicle is started or restarted, due to vibration or in the case of interconnection between carriages, the input power supply is prone to interruption or short-term unstable power supply.

A common solution is to select components with higher current capacity to avoid the large current stress generated during switching, thereby reducing the instantaneous peak current and preventing component damage. However, components with higher current capacity increase cost and space requirements.

The technical problem to be solved by this invention is to provide a circuit protection system and method for existing circuits, which can prevent surge current from exceeding the current withstand capacity of circuit components, thereby achieving the effect of protecting circuit components.

To solve the aforementioned technical problems, one of the technical solutions adopted by this invention is to provide a circuit protection system applicable to battery modules and load devices electrically connected to each other. The circuit protection system includes a switching unit, a current comparison unit, and a pulse-width modulation (PWM) signal generation unit. The switching unit is connected between the battery output terminal of the battery module and the load input terminal of the load device, and has a first control terminal. The current comparison unit is used to detect the battery current at the battery output terminal and determine whether the battery current value exceeds a predetermined current value. The PWM signal generation unit is used to continuously generate a PWM signal to control the switching unit to switch via the first control terminal. When the battery current exceeds the preset current value, the current comparison unit outputs an overcurrent signal to shut down the PWM signal generator, thus stopping the PWM signal output and keeping the switching unit in an open-circuit state. When the battery current does not exceed the preset current value, the current comparison unit outputs a no-overcurrent signal to continuously output the PWM signal, causing the switching unit to switch according to the PWM signal's operating cycle.

To solve the aforementioned technical problems, another technical solution adopted by this invention is to provide a circuit protection method for a storage battery, comprising: configuring a switching unit connected between the battery output terminal of the battery module and the load input terminal of the load device, and the switching unit having a first control terminal; configuring a current comparison unit to detect the battery current at the battery output terminal and determine whether the battery current value exceeds a predetermined current value; configuring a PWM signal generation unit to generate a PWM signal to pass through the first control terminal. The control unit switches between the on and off states. In response to the battery current exceeding a predetermined current value, the current comparison unit outputs an overcurrent signal to shut down the PWM signal generator, thereby stopping the output of the PWM signal and keeping the switch unit in the off state. In response to the battery current not exceeding the predetermined current value, the current comparison unit outputs a no-overcurrent signal to continue outputting the PWM signal, allowing the switch unit to switch according to the operating cycle of the PWM signal.

To further understand the features and technical content of this invention, please refer to the following detailed description and drawings of this invention. However, the drawings provided are for reference and illustration only and are not intended to limit this invention.

The following specific embodiments illustrate the implementation of the "circuit protection system and circuit protection method" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention.

Referring to Figure 1, this embodiment of the invention provides a circuit protection system 100 applicable to a battery module 1 and a load device 2 electrically connected to each other. The circuit protection system 100 includes a switching unit 3, a current comparison unit 4, and a pulse-width modulation (PWM) signal generation unit 5. The battery module 1 may be, for example, a battery for an electric vehicle, while the load device 2 may include, for example, a power converter and an engine drive system for an electric vehicle.

The switching unit 3 may have a first control terminal 30, a first terminal 31 and a second terminal 32. The switching unit 3 is connected between the battery output terminal 10 of the battery module 1 and the load input terminal 20 of the load device 2, and has a first control terminal 30.

The current comparison unit 4 detects the battery current Ibat at the battery output terminal 10 and determines whether the current value of the battery current Ibat exceeds a predetermined current value. The PWM signal generation unit 5 generates a PWM signal Spwm, which controls the switching unit 3 to switch via the first control terminal 30. When the current value of the battery current Ibat exceeds the predetermined current value, the current comparison unit 4 outputs an overcurrent signal Sov to shut down the PWM signal generation unit 5, thereby stopping the output of the PWM signal Spwm and keeping the switching unit 3 in an open circuit state. When the battery current Ibat does not exceed the predetermined current value, the current comparison unit 4 outputs an overcurrent signal Snov to continuously output the PWM signal Spwm, causing the switching unit 3 to switch according to the working cycle of the PWM signal Spwm.

Figure 1 illustrates the architecture of the circuit protection system 100 in a simplified manner. Please refer further to Figure 2, which is a circuit layout diagram of the circuit protection system of an embodiment of the present invention. One possible embodiment of the circuit protection system 100 is described further below, but the present invention is not limited to the circuit layout of Figure 2. As shown in Figure 2, the battery module 1 and the load device 2 are electrically connected at both ends, and the first terminal 31 of the switching unit 3 is connected to one of the ends, such as the battery output terminal 10. The switching unit 3 may be, for example, an N-type or P-type metal oxide semiconductor field effect transistor (MOSFET), and the first control terminal 30, the first terminal 31, and the second terminal 32 may correspond to the gate, the source, and the drain, respectively, but the present invention is not limited thereto.

The current comparison unit 4 includes a reference current source 40 and a current comparator 41. The reference current source 40 can be used to provide a reference current Iref with a predetermined current value. The current comparator 41 has a first input terminal (+ terminal) coupled to the battery output terminal 10, a second input terminal (- terminal) coupled to the reference current source 40, and an output terminal 410 coupled to the second control terminal 52 of the PWM signal generation unit 5.

In principle, the current comparator 41 compares the battery current Ibat with the reference current Iref and outputs a comparison signal Scom based on the comparison result. In an actual circuit, the current comparator 41 can be, for example, a voltage comparator, which converts two input currents into corresponding voltage signals through a conversion circuit and then compares the magnitudes of these voltage signals. For example, the battery current Ibat can be converted into voltage by a resistor R1 coupled to the battery output terminal 10 at one end, and the voltage at node N1, connected to the other end of the resistor R1, can be captured as a current detection point. The battery current Ibat corresponding to that voltage can then be calculated based on the resistance value of the resistor R1. In addition, for signal stability, the output terminal 410 of the current comparator 41 can also be coupled with resistor R2 and capacitor C1, but the invention is not limited thereto.

If the battery current Ibat does not exceed the predetermined current value, a comparison signal Scom with a first-order value can be output as an overcurrent-free signal Snov. If the current comparator 41 finds that the battery current Ibat exceeds the predetermined current value, a comparison signal Scom with a second-order value can be output as an overcurrent signal Sov.

It should be noted that, in order to protect circuit components, an appropriate predetermined current value needs to be designed to regulate the battery current Ibat. Even if an excessive current is generated, it can immediately prevent surge current from damaging the circuit components. The so-called surge current may be generated when the battery module 1 is switched from a disassembled state to a mounted state and directly electrically connected to the load device 2. Taking an electric vehicle system as an example, this surge current is generated, for instance, when replacing the battery module 1 by placing a fully charged battery module 1 into the battery compartment.

On the other hand, as shown in FIG2, the PWM signal generation unit 5 may include a signal generator 50 and a logic control circuit 51. The signal generator 50 is used to generate an initial PWM signal Spwm0, and the logic control circuit 51 has a first input terminal 510 coupled to the signal generator, a second input terminal 511 coupled to the output terminal 410 of the current comparator 41, and an output terminal 512 coupled to the first control terminal 30.

The control mode of the logic control circuit 51 needs to be designed such that when an overcurrent signal Sov is received, the initial PWM signal Spwm0 is prevented from being output to the switching unit 3, and when no overcurrent signal Sov is received, the initial PWM signal Spwm0 is allowed to be output to the switching unit 3.

For example, the second input terminal 511 of the logic control circuit 51 can serve as the second control terminal 52 of the PWM signal generating unit 5, so that when no overcurrent signal Snov is received, the PWM signal Spwm is output from the output terminal 512, and when an overcurrent signal Sov is received, the shutdown control signal is output to keep the switching unit 3 in the open circuit state.

For a further example, the logic control circuit 51 can be a gate. When the battery current Ibat does not exceed the predetermined current value, the comparison signal Scom has a high level (first level). When the battery current Ibat exceeds the predetermined current value, the comparison signal Scom has a low level (second level). Therefore, when the comparison signal Scom has a high level, the gate outputs the initial PWM signal Spwm0 as the aforementioned PWM signal Spwm. When the comparison signal Scom has a low level, the gate outputs a low-level signal as a shutdown control signal, keeping the switching unit 3 in the open circuit state.

Based on the above framework, further reference can be made to Figure 3, which is a flowchart of the circuit protection method of the present invention. The present invention further provides a circuit protection method applicable to the circuit protection system described in the embodiments corresponding to Figures 1 and 2, but is not limited thereto.

As shown in Figure 3, the circuit protection method may include the following steps: Step S10: Configure the PWM signal generation unit to generate a PWM signal to control the switching unit for switching via the first control terminal. Step S11: Configure the current comparison unit to detect the battery current at the battery output terminal. Step S12: Determine whether the battery current value exceeds a predetermined current value. In step S12, if the battery current value exceeds the predetermined current value, the circuit protection method proceeds to step S13: Configure the current comparison unit to output an overcurrent signal to shut down the PWM signal generation unit, thereby stopping the output of the PWM signal and keeping the switching unit in an open-circuit state.

In step S12, if the battery current value does not exceed the predetermined current value, the circuit protection method proceeds to step S14: the current comparison unit is configured to output an overcurrent signal to continuously output a PWM signal, so that the switching unit switches according to the working cycle of the PWM signal.

The detailed operating mechanism shown in Figure 2 has been explained in detail in the embodiment shown in Figure 2, and will not be repeated here. Therefore, in the circuit protection method and system provided by this invention, protection is provided during the battery startup phase or during sudden events by adding a PWM signal and a current comparator. This prevents the surge current from exceeding the current capacity of the circuit components when the electric vehicle encounters temporary situations, thus protecting the circuit components. In particular, it reduces component consumption to extend service life and protects both front-end and rear-end devices, improving reliability. Furthermore, the circuit of the circuit protection system of this invention is simplified, reducing erroneous actions in the electronic circuit while meeting product design specifications.

Please refer further to Figure 4, which is a schematic diagram of the simulation results of the first control terminal, load input terminal, and PWM signal of the circuit protection system of this embodiment. As shown in Figure 4, the voltage V1 of the first control terminal, the voltage V2 of the load input terminal, and the voltage V3 of the PWM signal change over time. As shown in the figure, by regulating the battery current Ibat, the voltage V2 of the load input terminal can be obtained to rise steadily over time in the start-up state, which has a very good suppression effect on surge current. Even under the same operating cycle, the circuit protection system provided by this invention can still suppress surge current under different load conditions. Furthermore, the operating cycle of the PWM signal can be adjusted according to the load conditions, and the surge current suppression effect can be achieved in different operating cycles.

[Beneficial effects of the implementation]

One of the beneficial effects of this invention is that the circuit protection system and method provided by this invention can protect the battery during the start-up phase or during a sudden event by adding a PWM signal and a current comparator. This prevents the surge current from exceeding the current capacity of the circuit components when the electric vehicle encounters a temporary situation, thus achieving the effect of protecting the circuit components.

The above-disclosed content is merely a preferred feasible embodiment of the present invention and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention's description and drawings are included within the scope of the patent application of the present invention.

Circuit Protection System: 100 Battery Module: 1 Battery Output: 10 Load Device: 2 Load Input: 20 Switching Unit: 3 First Control Terminal: 30 First Terminal: 31 Second Terminal: 32 Current Comparison Unit: 4 Reference Current Source: 40 Current Comparator: 41 Output: 410 PWM Signal Generation Unit: 5 Signal Generator: 50 Logic Control Circuit: 51 First Input: 510 Second Input: 511 Output: 512 Second Control Terminal: 52 PWM Signal: Spwm Battery Current: Ibat Reference Current: Iref Overcurrent Signal: Sov No Overcurrent Signal: Snov Comparison Signal: Scom Initial PWM Signal: Spwm0 Resistors: R1, R2 Capacitor: C1

Figure 1 is a block diagram of the circuit protection system of the present invention.

Figure 2 is a circuit layout diagram of the circuit protection system of the present invention.

Figure 3 is a flowchart of the circuit protection method of the present invention.

Figure 4 is a schematic diagram of the simulation results of the first control terminal, load input terminal and PWM signal of the circuit protection system of the present invention.

Circuit protection system: 100 Battery module: 1 Battery output terminal: 10 Load device: 2 Load input terminal: 20 Switching unit: 3 First control terminal: 30 First terminal: 31 Second terminal: 32 Current comparison unit: 4 PWM signal generation unit: 5 PWM signal: Spwm Battery current: Ibat Overcurrent signal: Sov No overcurrent signal: Snov

Claims (5)

A circuit protection system is applicable to a battery module and a load device electrically connected to each other. The circuit protection system includes: a switching unit connected between a battery output terminal of the battery module and a load input terminal of the load device, and having a first control terminal; a current comparison unit for detecting a battery current at the battery output terminal and determining whether the current value of the battery current exceeds a predetermined current value; and a pulse-width modulation (PWM) generation unit for generating a PWM signal to control the switching unit to switch via the first control terminal. Specifically, in response to the battery current exceeding a predetermined current value, the current comparison unit outputs an overcurrent signal to shut down the PWM signal generator to stop outputting the PWM signal, thus keeping the switching unit in an open-circuit state; conversely, in response to the battery current not exceeding the predetermined current value, the current comparison unit outputs a no-overcurrent signal to continuously output the PWM signal, causing the switching unit to switch according to a working cycle of the PWM signal; the current comparison unit includes: a reference current source for providing a reference current having the predetermined current value; and A current comparator has a first input terminal coupled to the output terminal of the battery, a second input terminal coupled to the reference current source, and an output terminal coupled to a second control terminal of the PWM signal generation unit. The current comparator obtains a voltage value after the battery current flows through a resistor, compares this voltage value with the voltage corresponding to the reference current to determine whether the battery current value exceeds a predetermined current value, and outputs a comparison signal according to the comparison result. The PWM signal generation unit includes: a signal generator for generating an initial PWM signal; and... A logic control circuit has a first input terminal coupled to a signal generator, a second input terminal coupled to the output terminal of a current comparator, and an output terminal coupled to the first control terminal, wherein the second input terminal of the logic control circuit serves as the second control terminal, and the logic control circuit is configured to output the PWM signal from its output terminal when the no-overcurrent signal is received, and to output a shutdown control signal to keep the switching unit in an open circuit state when the overcurrent signal is received; The logic control circuit is a gate that responds to the battery current value not exceeding the predetermined current value, the comparison signal having a first level, and responds to the battery current value exceeding the predetermined current value, the comparison signal having a second level; the gate is further configured to output the PWM signal when the comparison signal has the first level, and to output the shutdown control signal having the second level when the comparison signal has the second level, so that the switching unit remains in an open circuit state. The circuit protection system as described in claim 1, wherein the comparison signal output in response to the current value of the battery current exceeding the predetermined current value serves as the overcurrent signal; and the comparison signal output in response to the current value of the battery current not exceeding the predetermined current value serves as the no-overcurrent signal. The circuit protection system as described in claim 1, wherein a surge current is generated when the battery module is directly electrically connected to the load device in response to the transition of the battery module from a disassembled state to a loaded state. A circuit protection method for a storage battery includes: configuring a switching unit connected between a battery output terminal of a battery module and a load input terminal of a load device, wherein the switching unit has a first control terminal; configuring a current comparison unit to detect a battery current at the battery output terminal and determine whether the current value of the battery current exceeds a predetermined current value; configuring a PWM signal generation unit to generate a PWM signal to control the switching unit to switch via the first control terminal; in response to the battery current value exceeding the predetermined current value, configuring the current comparison unit to output an overcurrent signal to shut down the PWM signal generation unit to stop outputting the PWM signal, thereby keeping the switching unit in an open circuit state; In response to the battery current value not exceeding the predetermined current value, the current comparison unit is configured to output a no-overcurrent signal to continuously output the PWM signal, causing the switching unit to switch according to the working cycle of the PWM signal. The current comparison unit includes: a reference current source for providing a reference current having the predetermined current value; and a current comparator having a first input terminal coupled to the battery output, a second input terminal coupled to the reference current source, and an output terminal coupled to a second control terminal of the PWM signal generation unit. The current comparator obtains a voltage value after the battery current flows through a resistor, and compares this voltage value with a voltage corresponding to the reference current to determine whether the battery current value exceeds a predetermined current value. Based on the comparison result, it outputs a comparison signal. The PWM signal generation unit includes: a signal generator for generating an initial PWM signal; and a logic control circuit having a first input terminal coupled to the signal generator, a second input terminal coupled to the output terminal of the current comparator, and an output terminal coupled to the first control terminal, wherein the second input terminal of the logic control circuit serves as the second control terminal. The circuit protection method further includes: The logic control circuit is configured to output the PWM signal from its output terminal when the no-overcurrent signal is received; the logic control circuit is configured to output a shutdown control signal to keep the switching unit in an open-circuit state when the overcurrent signal is received, wherein the logic control circuit is a gate, and the comparison signal has a first threshold in response to the current value of the battery current not exceeding the predetermined current value, and a second threshold in response to the current value of the battery current exceeding the predetermined current value; the gate is configured to output the PWM signal when the comparison signal has the first threshold; and When the comparison signal has the second level, the gate is configured to output the closing control signal with the second level to keep the switching unit in the open circuit state. The circuit protection method as described in claim 4, wherein the comparison signal output in response to the current value of the battery current exceeding the predetermined current value serves as the overcurrent signal, and the comparison signal output in response to the current value of the battery current not exceeding the predetermined current value serves as the no-overcurrent signal.